CCB 4013 PLANT DESIGN PROJECT I SEMESTER SEPTEMBER 2014
DESIGN OF FORMALDEHYDE PRODUCTION PLANT
GROUP 4
ANWAR FARID BIN SHAHUDIN
14778
BASEM MOHAMMED ALI ALI
14988
CHUA YIN CHING
14771
DANESKUMAR A/L MANOGARAN
15049
EFI ISKANDAR BIN ZAINUDDIN
16219
CHEMICAL ENGINEERING DEPARTMENT UNIVERSITI TEKNOLOGI PETRONAS SEPTEMBER 2014
1
CERTIFICATION OF APPROVAL
CCB 4013 PLANT DESIGN PROJECT I SEMESTER SEPTEMBER 2014
DESIGN OF FORMALDEHYDE PRODUCTION PLANT
GROUP 4
ANWAR FARID BIN SHAHUDIN
14778
BASEM MOHAMMED ALI ALI
14988
CHUA YIN CHING
14771
DANESKUMAR A/L MANOGARAN 15049 EFI ISKANDAR BIN ZAINUDDIN
16219
APPROVED BY:
_______________________ DR. BHAJAN LAL (Group Supervisor) DATE: CHEMICAL ENGINEERING DEPARTMENT UNIVERSITI TEKNOLOGI PETRONAS
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ACKNOWLEDGEMENT Upon completion of Final Year Plant Design Project, project team would like to express their heartfelt gratitude to individuals and organization that have helped the team through the process. Without assistance and guidance, it would not be a smooth and successful process. First of all, sincere thanks and highest appreciation goes to the most important person who has played a very big role in this project, the project supervisor, Dr. Bhajan Lal. Throughout the process, he had given proper guidance to the team and ensures the team is on the right track of the process.
The project team would also like to express their gratitude to Chemical Engineering Department of Universiti Teknologi PETRONAS (UTP) for providing Final Year Plant Design Project course for the program as a platform for the students to apply the knowledge from undergraduate studies in actual application on plant design.
The team would like to thank the Final Year Plant Design Project’s committees, especially Dr. Sekhar Bhatacharjee for giving his insights on the process design and frequent updates on the materials and documents related in completing the project. Thanks for their efforts in organizing seminars and briefing for all the project teams to let them understand the procedure of the project and guide them in the process. The seminars and briefings were indeed very helpful and insightful.
Sincere gratitude goes to Group 4 team members for their team spirits, hard work and determination. Last but not least, project team would like to appreciate individuals that are either directly or indirectly involved in making this project a grand success.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY .................................................................................................... 8 CHAPTER 1: INTRODUCTION ....................................................................................... 10 1.1
Background ............................................................................................................ 10
1.2
Problem Statement ................................................................................................. 11
1.3
Objective ................................................................................................................ 12
1.4
Scope of work ........................................................................................................ 13
CHAPTER 2: 2.1
LITERATURE REVIEW ............................................................. 14
Introduction to Feed Properties .............................................................................. 14
2.1.1 Background of Methanol ...................................................................................... 14 2.1.2 Production of Methanol – Indirect Route via Syngas ........................................... 15 2.1.3 Applications of Methanol...................................................................................... 15 2.2
Introduction to Product Properties ......................................................................... 16
2.2.1 Background of Formaldehyde ............................................................................... 16 2.2.2 Routes of Exposures to Formaldehyde ................................................................. 16 2.2.3 Applications of Formaldehyde .............................................................................. 17 2.3
Market Survey and Analysis .................................................................................. 18
2.3.1 Global supply and demand .................................................................................... 18 2.3.2 Price Trends for Raw Materials & Products ......................................................... 22 2.4
Site Location Feasibility Study .............................................................................. 30
2.4.1 Site Considerations................................................................................................ 30 2.4.2 Selection Criteria................................................................................................... 30 2.4.3 Potential Plant Locations....................................................................................... 33 2.4.4 Weighted Evaluation ............................................................................................. 36 2.4.5 Plant Layout .......................................................................................................... 40 CHAPTER 3: PRELIMINARY HAZARD ANALYSIS .................................................. 41 3.1
Introduction to Hazard Analysis ............................................................................ 41
3.2
Previous Accidents on Similar Type of Plant ........................................................ 43
3.2.1 Explosion of drums in Kalyani, Nadia District, West Bengal, India .................... 43 3.2.2 Explosion in a resins production unit at Georgia-Pacific Resins, Inc. in Columbus, Ohio................................................................................................................................ 45 3.3
Material and Chemical Hazards in Feed ................................................................ 46
3.3.1 Methanol ............................................................................................................... 46 3.4
Material and Chemical Hazards of By-products .................................................... 47
3.4.1 Formic acid ........................................................................................................... 47
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3.4.2 Carbon monoxide, CO .......................................................................................... 47 3.4.3 Carbon dioxide, CO2 ............................................................................................. 47 3.5
Material and Chemical Hazards of Product ........................................................... 47
3.5.1 Formaldehyde ....................................................................................................... 47 3.6
Possibility of Reducing Potential Consequences of an Accident ........................... 50
3.6.1 Implementing Inherent Safety Aspects ................................................................. 50 3.6.2 The Layers of Protection Analysis (LOPA) .......................................................... 51 3.7
Safety and Environmental Regulations .................................................................. 53
3.7.1 Requirements by Local Safety Regulations and Design Guidelines ..................... 53 CHAPTER 4: CONCEPTUAL DESIGN ANALYSIS ..................................................... 57 4.1
Preliminary Reactor Design ................................................................................... 57
4.1.1 General Process for Formalin Production ............................................................. 57 4.1.2 Silver Catalyst Processes ...................................................................................... 59 4.1.3 4.2
Formox Process .............................................................................................. 63
Process Operating Mode ........................................................................................ 65
4.2.1 Batch Operation .................................................................................................... 66 4.2.2 Continuous Operation ........................................................................................... 67 4.3
Preliminary Reactor Optimization ......................................................................... 71
4.3.1 Incomplete conversion of methanol with distillative recovery of methanol ......... 71 4.3.2 Complete Conversion of methanol (BASF) .......................................................... 72 4.3.3 Formox Process ..................................................................................................... 73 4.4
Economic Potential Analysis ................................................................................. 74
4.4.1 Incomplete conversion of methanol with distillative recovery of methanol ......... 74 4.4.2 Complete Conversion of methanol (BASF) .......................................................... 74 4.4.3 Formox Process ..................................................................................................... 74 4.5
Justification of Process Route Selection ................................................................ 75
CHAPTER 5: HEAT INTEGRATION ............................................................................. 76 5.1
Pinch Analysis ....................................................................................................... 76
5.1.1 Stream Data Extraction ......................................................................................... 76 5.1.2 Problem Table Algorithm ..................................................................................... 77 5.1.3 Composite Curve................................................................................................... 79 5.1.4 Heat Exchanger Network (HEN) Design .............................................................. 80 CHAPTER 6: PROCESS FLOWSHEETING .................................................................. 82 CONCLUSION AND RECOMMENDATION ................................................................. 84 REFERENCES..................................................................................................................... 85
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LIST OF FIGURES Figure 1: World demand for methanol in 2007...................................................................... 14 Figure 2: West Europe Methanol Supply & Demand ............................................................ 18 Figure 3: Middle East Methanol Supply & Demand ............................................................. 19 Figure 4: Southeast Asia Methanol Supply & Demand ......................................................... 19 Figure 5: Northeast Asia Methanol Supply & Demand ......................................................... 19 Figure 6: South America Methanol Supply & Demand ......................................................... 20 Figure 7: North America Methanol Supply & Demand ......................................................... 20 Figure 8: Global Formaldehyde Supply & Demand .............................................................. 21 Figure 9: Global Formaldehyde Demand by Region ............................................................. 21 Figure 10: World Methanol Demand by Region ................................................................... 22 Figure 11: West Europe Price Trend...................................................................................... 23 Figure 12: Northeast/Southeast Asia Price Trends ............................................................... 23 Figure 13: US Methanol Price Trend ..................................................................................... 24 Figure 14: Methanol Pricing Mechanism............................................................................... 24 Figure 15: Molybdenum Oxide Price Trend(MetalPrices.com, 2014)................................... 25 Figure 16: Ferromolybdenum Price Trend (MetalPrices.com, 2014) .................................... 25 Figure 17: Iron Oxide Pricing (StandardCeramic.com, 2014) ............................................... 26 Figure 18: Vanadium Pentoxide Pricing (StandardCeramic.com, 2014) ............................... 26 Figure 19: Silver Price Trend (SilverPrice.com, 2014).......................................................... 27 Figure 20: Schematic Diagram on selection of site criterion ................................................. 30 Figure 21: Kedah Map and location of Gurun ....................................................................... 38 Figure 22: Plant Layout ......................................................................................................... 40 Figure 23: Layers of Protection Concept ............................................................................... 51 Figure 24: Characteristics and features of methanol .............................................................. 58 Figure 25: Flowchart of formaldehyde production by the BASF process ............................. 61 Figure 26: Flowchart of formaldehyde production with recovery of methanol by distillation ............................................................................................................................................... 62 Figure 27: Flowchart of formaldehyde production by the Formox process ........................... 63 Figure 28: Batch operation..................................................................................................... 66 Figure 29: Continuous operations .......................................................................................... 67 Figure 30: Block diagram of incomplete conversion of methanol with distillative recovery of methanol................................................................................................................................. 71 Figure 31: Block diagram of complete conversion of methanol (BASF) .............................. 72 Figure 32: Block diagram of Formox process ....................................................................... 73 Figure 33: Combined composite curve .................................................................................. 80
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Figure 34: Grand composite curve ......................................................................................... 80 Figure 35: Heat Exchanger Network (HEN) grid .................................................................. 81 Figure 36: PFD before integration ......................................................................................... 82 Figure 37: PFD after integration ............................................................................................ 82
LIST OF TABLES Table 1: Overview of methanol applications ......................................................................... 15 Table 2: Price range of catalysts ............................................................................................ 27 Table 3: Price range of various companies for formaldehyde ............................................... 28 Table 4: Price range for materials .......................................................................................... 29 Table 5: Comparisons of possible locations (Jasmir & Nadzri, 2010; McMorrow & Talip, 2001) ...................................................................................................................................... 33 Table 6: Weightage criteria .................................................................................................... 36 Table 7: Weighted evaluation on potential site ...................................................................... 37 Table 8: Job hazard analysis (JHA) for explosion of drums in Kalyani, Nadia District, West Bengal, India (Bhattacharjee et al., 2014) .............................................................................. 44 Table 9: Summary of chemical hazards information ............................................................. 48 Table 10: Preventive measure to reduce risk at workplace .................................................... 50 Table 11: Basic strategies in inherent safety chemical process ............................................. 52 Table 12: Specifications of the methanol for production of formaldehyde ........................... 58 Table 13: Comparison of between batch and continuous process operation ......................... 68 Table 14: Economic comparison of three process routes....................................................... 75 Table 15: Stream Data ........................................................................................................... 76 Table 16: Shifted temperature ................................................................................................ 77 Table 17: Temperature Portioning Table ............................................................................... 78 Table 18: Heat cascade diagram ............................................................................................ 78
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EXECUTIVE SUMMARY Formaldehyde is a commonly used chemical compound that exists in various forms and at room temperature, is a colorless, distinctive, strong and even pungent smelling, flammable and gaseous substance. Formaldehyde has been used in a number of industries for various purposes such as: for the manufacturing of building materials – like pressed wood products (mostly as an adhesive resin), fiber board, plywood, cigarette smoke, fuel burning appliances and kerosene space heaters. Additional uses in household products include: additive for permanent –press, an ingredient in glues, and as a preservative in medical laboratories – as embalming fluid, and as a sterilizer. Since Formaldehyde is a by-product of combustion and other inherent processes, it can be found in significant concentrations and in various environments. The main objective of this project is to design an economically feasible formaldehyde production plant with the plant capacity of 50, 000 ton per year. The development of plant should consider all the relevant criteria required in order to make the most optimize production plant. The location chosen for the plant is in Labuan because raw material ethanol is easily transported from the port to plant area. The first two chapters of the project emphasizes on the introduction and literature review. The problem statement, objectives and scope of study of the project are being discussed thoroughly in the first chapter. Chapter 2 gives details regarding existing process description for formaldehyde manufacture, the process route chosen, physical and
chemical
properties
of
materials
involved
in
formaldehyde production,
economic outlook and site feasibility study.
Chapter 3 mainly focuses on preliminary hazard analysis. The hazards for formaldehyde are identified and the control measures are detected. Apart from that, the environmental issues are taken into consideration to produce a green, sustainable and environmental friendly process of the formaldehyde plant.
Chapter 4 focuses on highlighting the main section of the project design, which is the conceptual design analysis. The hierarchical approaches are briefly discussed as it is a systematic approach to determine the type of process implemented. The reactor design and separation synthesis are also being reviewed to produce a feasible and economical plant design. Plant would be operated in continuous mode. The preferred reactor used for this project is plug flow reactor and this selection of reactors is important to maximize the production of formaldehyde. Using different patents as basis, three process flow sheets are developed. The most feasible process flow is chosen from
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the highest yield of product and comparison between economic potential 1 and economic potential 2 for all the three process flow sheets.
Chapter 5 explains the process of implementing heat integration on the integrated plant. The heat integration study is done by applying the pinch analysis method. Design grid diagram, grand composite curve and heat exchanger network (HEN) are developed with the aid of SPRINT software. Heat integration is necessary in order to optimize the energy usage in the plant. The process flow sheeting before and after implementing heat exchanger network are attached in this section.
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CHAPTER 1: INTRODUCTION 1.1
Background The purpose of this project is to design a plant that produce formalin which is 37
weight % of formaldehyde in water as the main product of the overall process and to execute the design and evaluation on safety aspects, site selection, conceptual design, material and energy balance, heat integration and preliminary economic evaluation. Formaldehyde is an organic compound with the formula CH2O or HCHO. It is the simplest aldehyde and is also known by its systematic name methanal. The common name of this substance comes from its similarity and relation to formic acid. A gas at room temperature, formaldehyde is colorless and has a characteristic pungent, irritating odor. It is an important precursor to many other materials and chemical compounds. In 1996, the installed capacity for the production of formaldehyde was estimated to be 8.7 million tonnes per year.(G.Reuss) Commercial solutions of formaldehyde in water, commonly called formol, were formerly used as disinfectants and for preservation of biological specimens. It is commonly used in nail hardeners and/or nail varnish. Formaldehyde is more complex than other simple carbon compounds in that it adopts several different forms. One vital derivative is the cyclic trimer metaformaldehyde or 1,3,5-trioxane with the formula (CH2O)3. There is as well an infinite polymer called paraformaldehyde. These compounds behave similarly as the molecule CH2O. When dissolved in water, formaldehyde forms a hydrate, methanediol, with the formula H2C(OH)2. This also exists in equilibrium with various oligomers (short polymers), depending on the concentration and temperature. A saturated water solution, of about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". A small amount of stabilizer, such as methanol, is usually added to suppress oxidation and polymerization. A typical commercial grade formalin may contain 10–12% methanol in addition to various metallic impurities. Formaldehyde can be produced by various reactions such as the catalytic oxidation, dehydrogenation and also direct oxidation of methane. Catalytic oxidation remains as the most viable and economical process to produce formaldehyde yet. And most commonly used catalysts
for
this
process
are
silver metal
an iron and molybdenum or vanadium oxides.
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or
a
mixture
of
1.2
Problem Statement From the Methanol Market Services Asia (MMSA) report (2013) on Formaldehyde
Supply and Demand Balance, we can see that the demand of formaldehyde has been increasing gradually since the year of 2009. For the year 2013, there is an increase in formaldehyde demand of 4.92%. In 5 years’ time since 2009, we can see an increase in demand of staggering 36.38%. This shows that, the global consumption of formaldehyde is increasing with a very good pace. Especially here in Asia as most of the countries are growing economically.
In Malaysia, there are only a few significant plants that are producing formaldehyde such as ChemstationAsia, Hexza Corporation, and NewQuest Trading under Kuok Groups. Formaldehyde Industry is still growing and the demands for Formaldehyde are quite high globally.
The project team is responsible to design an integrated formaldehyde production plant with formaldehyde production capacity of 50,000 metric ton per year (MTPY) to meet customers demand in Malaysia as well as targeted countries in the Southeast Asia region that has a high demand on formaldehyde. Various
factors
and
relevant issues
are taken
into
consideration when
designing a new petrochemical plant. Factors that need to be emphasized are safety issues related to process, health and environment; plant location, energy consumption and proper process route to ensure the plant are operated through green, sustainable and environmental friendly process.
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1.3
Objective
The main objective of the plant design project is to produce the required amount of product while ensuring that the plant operations is economically feasible without disregarding the environmental and safety aspect. The team is required to propose the best design at the end of this project. Apart from that, the objectives of this design project include the following:
To study about the raw materials and product used in the process. The study encompasses their properties, market survey, cost, application, supply and demand of the global market. To study on the alternatives routes of producing the products. To identify and select the best process route to produce the desired products to propose a proper plant location for the design project. To determine the safety precaution actions for the plant. To develop the complete material and energy balance calculations. To generate material, energy balances and heat integration network for a petrochemical plant using computer aided design engineering software (e.g. ICON/HYSIS). To evaluate the economic feasibility of the plant by determining the economic potentials for all possible routes.
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1.4
Scope of work
In order to ensure the work progress is in accordance with the timeline of proposed activities, milestones and deadlines, details and proper scope of work need to be established and well-planned. Below are the details of the scope of work in order to reach the objectives in this course:
Conducting literature review from journals, books, and any other reliable studies regarding the raw materials, chemical and physical properties of the intermediate product, product and by-product, economic evaluations for the production of product, usage of the desirable product, main and alternative routes product’s
production,
safety
and
for
desired
environmental considerations and any other
related issues Identifying and selecting the best process route for a particular design project, developing the best possible process flow sheet for the selected chemical process route. Determining the plant location based on several factors such as costs, transportation, accessibility, utilities tariff, raw materials supply and local legal requirements. Developing the complete material and energy balance calculations for all processes as well as heat integration for the selected process. Determining the economic potential and cost estimation for all processes. Applying related computer-aided design and engineering software such as HYSYS, Microsoft Office Visio, MATLAB and AutoCAD as tools for designing task.
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CHAPTER 2: 2.1
LITERATURE REVIEW
Introduction to Feed Properties 2.1.1 Background of Methanol Methanol, also called as methyl alcohol or wood alcohol, is colorless, water –soluble
liquid with a mild alcoholic odor. It freezes at -97.6°C, boils at 64.6°C and has a density of 791 kg/m3 at 20°C. Today, methanol is mainly a feedstock for the chemical process industry used for the production of varied chemical products and materials. Worldwide, almost 65% of the methanol production is used to obtain formaldehyde. Figure 1 below shows the world demand for methanol in 2007 (Cheng, 1994).
Figure 1: World demand for methanol in 2007
Methanol is a high production volume chemical with many commercial uses and it is a basic building block for hundreds of chemical products. Many of its derivatives are used in the construction, housing or automotive industries. Consumer products that contain methanol include varnishes, shellacs, paints, windshield washer fluid, antifreeze, adhesives, de-icers, and Sterno heaters (Olah, Goeppert, & Prakash, 2009). In 2009, the Methanol Institute estimated a global production capacity for methanol of about 35 million metric tons per year
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(close to 12 billion gallons), a production capacity in the United States (U.S.) of nearly 3.7 million metric tons (1.3 billion gallons), and a total U.S. demand for methanol of over 8 million metric tons. Methanol is among the highest production volume chemicals reported in the U.S. EPA’s Toxic Release Inventory (TRI) (Cheng, 1994; Olah et al., 2009). While production has switched to other regions of the world, demand for methanol is growing steadily in almost all end uses. A large reason for the increase in demand is its use in the production of biodiesel, a low-sulfur, high-lubricity fuel source. 2.1.2 Production of Methanol – Indirect Route via Syngas The conversion of natural gas to methanol via syngas is a widely used industrial process. Methanol synthesis from syngas is an exothermic reaction and operates at high temperature, around 200-300°C (Cheng, 1994). Production of syngas is traditionally performed in one step by steam reforming. Many of the modern processes adopt two-step reforming, which is primary steam and auto-thermal reforming. According to Olah et al., the primary reformer is simplified and reduced in size and can be operated at a reduced temperature. Oxygen is blown to the auto-thermal reformer first to produce carbon monoxide and water with heat generation. The secondary reforming operates at higher temperature to ensure low leakage of methane. The combined process is integrated to produce stoichiometric syngas for methanol synthesis. The process reduces energy consumption and investment and is particularly suitable for larger capacities. The two step reforming process has been used by Topsoe, Lurgi, Mitsubishi and others (Olah et al., 2009).
2.1.3 Applications of Methanol Applications of methanol in the energy industry may be via four approaches: methanol to gasoline conversion, methanol to methyl tert-butyl ether (MTBE) for reformulated gasoline, neat methanol or methanol blends as automobile and fuels, and dissociation or reforming of methanol to syngas for a variety of fuel usage (Cheng, 1994). Table 1 below shows the overview of methanol applications. Table 1: Overview of methanol applications Direct derivatives or uses
Secondary derivatives or uses
Fuel or fuel additives Neat methanol fuel Methanol blended with gasoline MTBE TAME Methanol to gasoline
Oxygenate in gasoline Oxygenate in gasoline
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Chemicals Formaldehyde
Urea-formaldehyde resins Phenolic resins Acetylenic chemicals Polyacetal resins Vinyl acetate Acetic anhydride Ethyl acetate
Acetic acid
Chloromethanes Methyl chloride Methylene chloride
Organic paint-removal solvent Solvent and cleaning applications
Other uses Solvent Antifreeze Inhibitor Substrate
2.2
Introduction to Product Properties 2.2.1 Background of Formaldehyde Formaldehyde, the largest chemical product derived from methanol, is a colorless,
corrosive and flammable gas with a pungent, suffocating odor. Formaldehyde is available in the environment from either natural or industrial sources. Formaldehyde is produced in large quantities industrially. It is predominantly used commercially as a solution in water at concentrations in the range of 25 – 56 % formaldehyde (Anonymous, 2000). A solution of approximately 37% formaldehyde is commonly known as formalin and is used as a tissue fixative for histology and pathology. Formalin is a common constituent used in the manufacture of many complex materials. It is used in the production of resin polymers for permanent adhesives such as those used in fiber board, particle board, plywood and carpeting. It is also used in foam insulation and as paper and textile finishing treatments. Formaldehyde at approximately 5% in a solution with water is used as a disinfectant and fumigant in hospitals, ships, dwellings and animal handling facilities, as it is effective in killing most bacteria, viruses and fungi (Anonymous, 1994). Formaldehyde can be considered to occur naturally in the environment because it is produced form the breakdown of methane by sunlight. Formaldehyde is also formed from the combustion of organic materials such as wood fires and tobacco smoke. 2.2.2 Routes of Exposures to Formaldehyde The possible routes of exposure to formaldehyde are ingestion, inhalation, dermal absorption and rarely, blood exchange as in dialysis.
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2.2.2.1 Air Assuming a breathing volume of 20 m3 per day for an average adult, given the air levels mentioned above and making assumptions of the time spent in various environments, one can calculate inhalation exposure per day. Average time estimates lead to the conclusion that people spend 60–70% of their time in the home, 25% at work and 10% outdoors. If one assumes that normal work exposures are similar to home exposures, and the data given on the occurrence of formaldehyde in air are used, the daily exposure resulting from breathing is about 1 mg/day, with a few exposures at > 2 mg/day and a maximum of about 8 mg/day (Organization, 2001). 2.2.2.2 Food Formaldehyde occurs naturally in foods, and foods may be contaminated as a result of fumigation, cooking and release from formaldehyde-resin-based tableware. Formaldehyde has been used as a bacteriostatic agent in some foods, such as cheese. Fruits and vegetables typically contain 3–60 mg/kg, milk and milk products about 1 mg/kg, meat and fish 6–20 mg/kg and shellfish 1–100 mg/kg. The daily intake is difficult to evaluate, but a rough estimate from the available data is in the range of 1.5–14 mg/day for an average adult, most of it in a bound and unavailable form (Organization, 2001). 2.2.3 Applications of Formaldehyde Formaldehyde is used extensively in the woodworking and cabinet-making industries. Urea-formaldehyde is used in the glues that bond particle board together. The particle board is used underneath wood veneer and plastic laminate. Cabinets, bank counters, and veneered and laminated woodwork all use particle board containing urea-formaldehyde under the plastic laminate and wood veneer (Pinto, Gladstone, & Yung, 1980). According to Pinto et al., formaldehyde is a common building block for the synthesis of more complex compounds and materials. Products generated from formaldehyde include urea formaldehyde resin, melamine resin, phenol formaldehyde resin, polyoxymethylene plastics, 1, 4-butanediol, and methylene diphenyl diisocyanate. The textile industry uses formaldehyde-based resins as finishers to make fabrics crease-resistant. Formaldehyde-based materials are keys to the manufacture of automobiles, and used to make components for the transmission, electrical system, engine block, door panels, axles and brake shoes.
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2.3
Market Survey and Analysis
2.3.1 Global supply and demand The players for methanol supplies are in West Europe, Middle East, Southeast Asia, Northeast Asia, South America and North America region. According to market review by Johnson (2012), all regions roughly have steady or increasing production and demands. Production and demands from aforementioned region can be seen in Figure 1-6.
Figure 2: West Europe Methanol Supply & Demand
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Figure 3: Middle East Methanol Supply & Demand
Figure 4: Southeast Asia Methanol Supply & Demand
Figure 5: Northeast Asia Methanol Supply & Demand
19
Figure 6: South America Methanol Supply & Demand
Figure 7: North America Methanol Supply & Demand
Based from figures above, the methanol can be easily acquired from South America, Southeast Asia and Middle East since their production outweighs their demand domestically. As for formaldehyde, the supply and demand can be seen in Figure 7 & 8.
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Figure 8: Global Formaldehyde Supply & Demand
Figure 9: Global Formaldehyde Demand by Region
21
Both of these figures shows that a market window particularly for demand of formaldehyde is steadily increasing in size and the three regions in focus are Northeast asia, North America and Europe. Therefore, these regions are where the potential customers can be found.
Figure 10: World Methanol Demand by Region
2.3.2 Price Trends for Raw Materials & Products The production of formaldehyde is made possible thanks to the raw material: methanol. Thus, in order to select the most reasonably priced raw material, the price trends from different regions should be considered. Costs from transportation will be considered too for raw materials. Besides that, the product price should be considered as well as to justify whether the plant will be profitable or not.
22
2.3.2.1 Raw material prices - Methanol
Figure 11: West Europe Price Trend
Figure 12: Northeast/Southeast Asia Price Trends
23
Figure 13: US Methanol Price Trend
Based on the three price trends, the price trend of Notheast/Southeast Asia is the most reasonable ($300-350/ton) and considering it is the price setter, methanol would best be bought from Northeast/southeast Asia region.
Figure 14: Methanol Pricing Mechanism
24
2.3.2.2 Catalyst prices There are various types and combinations of catalyst involved in oxidation of methanol to form formaldehyde. There are molybdenum oxide, ferromolybdenum, iron oxide, vanadium pentoxide and silver,
Figure 15: Molybdenum Oxide Price Trend(MetalPrices.com, 2014)
Figure 16: Ferromolybdenum Price Trend (MetalPrices.com, 2014)
25
Figure 17: Iron Oxide Pricing (StandardCeramic.com, 2014)
Figure 18: Vanadium Pentoxide Pricing (StandardCeramic.com, 2014)
26
Figure 19: Silver Price Trend (SilverPrice.com, 2014)
Table 2: Price range of catalysts Catalysts
Price(USD)/kg
Molybdenum Oxide
20.00
Ferromolybdenum
24.00
Iron Oxide
7.60
Vanadium Pentoxide 60.00 518.27
Silver
Based on Table 2 above, the cheapest catalyst is iron oxide while the most expensive is silver. For peak performance, ferromolybdenum and vanadium pentoxide can be deployed with price below $100/kg which still less expensive compared to silver.
2.3.2.3 Product prices - Formaldehyde The most important aspect of planning and designing of a plant is to ensure the products produce is highly marketable and at a competitive prices in order to generate profits.
The statistics on formaldehyde pricing is classified as the pricing corresponds to feedstock of companies. However, by comparing the price range provided by selected companies, the pricing for formaldehyde in production can be estimated.
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Table 3: Price range of various companies for formaldehyde Manufacturer MasterTech Shijiazhuang Xinlongwei Chemical Co., Ltd. Henan CXH Purity Industrial And Trading Co., Ltd. Henan Luckybee New Technology Co., Ltd.
Price Range $ 31890.00/ton $350-500 / ton
Purity
Min. Order
Supply Ability
1 Twenty-Foot 5000 Ton/Tons Container per Month 1 Twenty-Foot 4000 Ton/Tons Container per Month
$387-419 / ton
5 Tons
Qingdao Xinyongan $400-450/ ton Chemicals Co., Ltd
5 Metric Tons
Quzhou Juhui Chemical $100-300/piece Materials Co., Ltd. Zouping Changshan $1000-3000 Town Zefeng Fertilizer /ton Factory Zhejiang Junhao Chemical Co., Ltd.
20 Tons
Xinxiang Kolanky Technical Co., Ltd. Henan Xinxiang No. 7 Chemical Co., Ltd. Zhejiang Junhao Chemical Co., Ltd Guangzhou Derou Chemical Industry Co., Ltd. Xinxiang Kolanky Technical Co., Ltd. YongHua Chemical Technology (Jiangsu) Co., Ltd. Toronto Research Chemicals
$1450-1850 / ton $1450-1850 / ton
18 Tons
Beijing Hwrk Chem Co.,ltd. Guangzhou Puen Scientific Instrument Co., Ltd. Fishersci Beijing Ouhe Technology Co. Ltd
$95670/ton
1 Ton
1 Metric Ton
18 Tons
1500 Metric Ton/Metric Tons per Month 1000 Metric Ton/Metric Tons per Month 10000 Ton/Tons per Month 1,000 Ton/Tons per Month 2000 Metric Ton/Metric Tons per Month 880 Ton/Tons per Month 880 Ton/Tons per Month
1 Metric Ton $1000-10000 /ton
1000 Kilograms
$1450-1850 / ton $260-520 / ton
18 Tons
$183981539679 / ton
1 Metric Ton
300 Metric Ton/Metric Tons per Month 880 Ton/Tons per Month 10 Metric Ton/Metric Tons per Day
96%
$511051899448 /ton
98%
$44330/ton $24530/tonl
96% 98%
Based on the supply ability, purity, pricing range and minimum order, the preferable price for selling formaldehyde is in range of $20000-100000/ton. 28
By referring Table 3, based on the supply ability, purity, pricing range and minimum order, the preferable price for selling formaldehyde is in range of $20000100000/ton. After compiling the price range and trend of reactant, catalysts and product, the following table is formed: Table 4: Price range for materials Material
Price range
Methanol
$300-350/ton
Iron Oxide
$7.60/kg
Ferromolybdenum + Vanadium pentoxide $84.00/kg $20000-100000/ton
Formaldehyde
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2.4
Site Location Feasibility Study
2.4.1 Site Considerations The selection of site for our formaldehyde production plant is very vital, so that it has all the support required to make maximum profit with minimum operating cost. There are many important factors that must be considered when selecting a suitable site.
2.4.2 Selection Criteria
Raw Material Availability Political, Economic and Strategic Consideration
Location With Respect To Marketing Area
Waste Disposal
Transportation
Land Availability & Cost
Utilities
Labour Supply
Figure 20: Schematic Diagram on selection of site criterion
30
2.4.2.1 Raw Material Availability In order to select the best location to build a chemical plant, a major factor to be considered is the source of raw materials. In this project, the plant needs to have a capacity to produce formaldehyde at the rate of 50,000 tons/year. In order to produce these large amounts of product, a large volume of raw material is needed. Therefore, the plant should be located near to the source of its raw material (e.g. methanol) or have an easy access to the raw material. The considerations of this factor are important to lower the cost of operation. Furthermore, other factors such as raw materials storage, transportation expenses, supply availability and reliability were also taken into account.
2.4.2.2 Location with Respect to the Marketing Area The cost of production versus the cost of transportation determines the selection of location with respect to the above criteria. Most chemical process plant has significantly higher production cost compared to the cost for bulk transportation. Therefore, most of the time the location selected is near to the transportation hub particularly sea port. This will enable the delivery of the finished products to customer as quickly and as cheaply possible.
2.4.2.3 Transportation Water, railroads, and highways are the common means of transportation used by major industrial concerns. The kind and amount of products and raw materials determine the most suitable type of transportation facilities. If possible, the plant site should have access to all three types of transportation. Land transport such as road and rail transport is being increasingly used. The road transport is more suitable for a local distribution from a central warehouse meanwhile the rail transport is more suitable for long distance transport of bulk chemicals as it cheaper. Seaport facilities will help in the exportation and importation of the product and raw materials via tankers while the availability of airport is convenient for the movement of personnel and essential equipment supplies.
2.4.2.4 Utilities Basic facilities such as water supply, power supply and supporting utilities must be located near to the location site in order to run the chemical process more convenient and effective. Power requirements are high in most industrial plants, and fuel is ordinarily required to supply these utilities. Consequently, power and fuel can be combined as one major factor in the choice of a plant site. Large quantities of water supply are needed for cooling and general use in a chemical plant.
31
2.4.2.5 Labor Supply An adequate labor supply is still needed from various disciplines despite of the increasing usage of the automation. Plant should be located where sufficient labor supply is available. The
labor
will
mainly
involve
in
the
construction,
management,
operation and the maintenance of the plant. Skilled construction workers will usually be brought in from outside local area but there should be an adequate pool of unskilled workers available locally and workers suitable for training to operate the plant. Available, inexpensive manpower from the surrounding area will contribute in reducing the cost of operation. Besides that, the turnover rates, local pay rates and competing industries must also be considered. 2.4.2.6 Suitable land Availability The cost of the land depends on the location selected. Enough space area with reasonable land prices should be identified and selected in order to reduce the investment cost in designing a plant location. It is important to choose the lowest land price when starting a new plant to gain the highest economic value. That said, the land must also be suitable and should be spacious keeping in mind of a future expansion. 2.4.2.7 Waste Disposal A good industrial site is when it is provided with a good waste disposal facility. It is important to provide an efficient and correct waste disposal in order to prevent or reduce any pollution which then can affect the human. If there are none, then the best way is to choose the area which is the nearest to this facility. However, this factor is not a great concern as the operations of this plant only produce water as the waste and the plant itself will be built with a wastewater treatment plant.
2.4.2.8 Political, Economic and Strategic Consideration Stable country and political situation where there is not much possible public disturbance. Financial incentives provided by the government and the tax policy. Financial facilities provided by the local businesses. Local regulations on zoning, building codes, nuisance aspects, and transportation facilities can have a major influence on the final choice of a plant site. Based on the factors listed above, possible locations are evaluated and location of the plant will determined based on the evaluation.
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2.4.3 Potential Plant Locations Listed are the choices of location 1. Gurun Industrial Estate, Pahang 2. Kota Kinabalu Industrial Park, Sepangar 4. Lahad Datu Industrial Park, Sabah
Table 5: Comparisons of possible locations (Jasmir & Nadzri, 2010; McMorrow & Talip, 2001) Selection Criteria Land price Area available Water supplier Electricity supplier Methanol supplier
Gurun, Kedah
Kota Kinabalu Industrial Park
RM7.00 psf ( Gurun RM 28-RM 30 psf (KKIP) Industrial zone) 1528.5 hectares N/A
Lahad Datu Industrial Park RM 30 psf 1618.7 hectares
- PETRONAS CUF
Diversified Water Resources Sdn. - PETRONAS CUF Bhd. - LahadDatu Water Supply SdnBhd - PETRONAS CUF KKIP Power Sdn. Bhd. - PETRONAS CUF - TenagaNasionalBerhad PETRONAS Petronas Labuan Methanol plant Petronas Labuan Methanol Fertilizer Kedah plant Gurun
Highway
North-South highway
KK-Sulaman highway
Malaysia Federal Route 13
Railway
Gurun Railway Station Sultan Abdul Halim Airport Penang Port (60km) Pulau Bunting Port (project completion 2016) 19km Large population
-
-
Airport Port facility
Labor Supply Waste disposal
Political, Economic and Strategic
Kota Kinabalu International Airport Lahad Datu Airport (KKIA) 5 km from Sepangar Container Port - Liquid & Dry Terminal
Large population
- PETRONAS CUF -Dewan Bandaraya Kota Kinabalu - Majlis Perbandaran Kedah Companies developing infrastructure of industrial park:
33
Bulk
Large population - PETRONAS CUF
Investment Incentives
Pioneer status Investment
tax
Considera tion
allowance Income tax exemption of 100% for 5 years commencing from the year company derives statutory income, or Investment tax allowance (ITA) of 100% on qualifying capital expenditure for 5 years Stamp duty exemption on instruments of acquisition or leasing of property relating to industrial park Companies undertaking promoted activities in the industrial park: Customised incentives based on merit of each case, or Income tax exemption of 100% for 8 years commencing from the year company derives statutory income, or Investment tax allowance (ITA) of 100% on qualifying capital expenditure for 5 years - Import duty and sales tax exemption on raw materials, components, machinery,
34
equipment, spare parts and consumables that are not produced locally and used directly in the activity.
35
2.4.4 Weighted Evaluation The two proposed sites are evaluated in a table as per below. The ranking was done from 1 (poor), 2 (fair), 3 (good), 4 (very good) to 5 (excellent). Table 6: Weightage criteria Factors
5-4 Marks
3-2 Marks
Land price
Price of land below RM Price of land more than Price of land more than 20 psf
Natural
gas Able
RM 20 psf to
obtain
RM30 psf
large Able to obtain natural Unable to obtain natural
natural gas supply locally
supplier
1-0 Marks
gas supply from near gas supply locally or neighboring countries
from near neighboring countries
Water supplier
Able
to
obtain
large Able to obtain water Unable to obtain enough
water supply from the supply from neighboring water supply same state to
state
Electricity
Able
obtain
large Able to obtain electricity Unable to obtain enough
supplier
electricity supply from supply from neighboring electricity supply the same state
state
<10 km proximity to port <30 km proximity to port >30 km proximity to port
Port facility
facility Availability
Airport
facility
of Availability of domestic Unavailability of airport
international airport
Political, Economic
airport
Complete network and Complete
Railway
facility
network
well maintained railway
railway
Excellent tax benefits
Good tax benefits
and
Strategic Consideration
36
of Unavailability of railway
No tax benefits
Table 7: Weighted evaluation on potential site
Selection Criteria
Gurun
Industrial Kota
Kinabalu
Lahad
Datu
Industrial
Park,
Area
Industrial Park
5
2
2
5
3
3
Water supplier
5
3
5
Electricity supplier
5
4
5
Port facility
3
5
5
Airport
5
5
5
Railway
5
0
0
Highway
5
3
5
Waste disposal
5
3
5
Tax Benefits
5
-
4
Total
48
29
40
Percentage
96%
58%
80%
Ranking
1
3
2
Land price Raw
materials
supplier
37
Sabah
Based on matrix comparison in the above table, Gurun Industrial Estate has been chosen as a proposed location to build formaldehyde plant. The following are the attractive features of Gurun Industrial Estate:
Figure 21: Kedah Map and location of Gurun
After researching suitable plant locations, we have decided to suggest the location to be in Gurun, Kedah, Malaysia as it is closest to one of the methanol suppliers in Malaysia. Gurun Industrial area is a suitable place to set up a plant. The advantages are including cheap industrial land prices. Furthermore it has become a platform mainly for petrochemical industries (PETRONAS Fertilizer Kedah) and other technology industry. There are several major factories in Gurun industrial zone, namely Perwaja Steel, Modenas and Naza. There are also good roads and highways for ease of transportation. Gurun can be reached via the federal highway within Kedah, the North-South Expressway and it even has its own train station. The main junction in the town center connects the western part of Kedah to the town of Jeniang and the district of Sik.
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Below are details of PETRONAS Fertilizer Kedah (PFK), the methanol supplier of interest. Methanol Supplier Company Name
: PETRONAS Fertilizer (Kedah) Sdn Bhd
Type
: Wholly Owned
Address
: KM3 Jalan Jeniang, PO Box 22, 08300 Gurun, Kedah, Malaysia
Principal Activity
: Production of ammonia, granular urea, methanol, and formaldehyde.
Principle Activity
: Petrochemicals
Capacity
: 375,000 MT/Year Ammonia, 600,000 MT/year Urea, 66000 MT/year Methanol
Uses (Methanol)
: Methanol is used as raw materials for glycerine; paper and textile; pharmaceuticals industries, formaldehyde and fuel
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2.4.5 Plant Layout
Figure 22: Plant Layout
According to Figure 17, which is a simple plant layout, the process area and non-process area are separated. The places where most workers are present, such as administration building, laboratory, control room and cafeteria should be located near to each other to minimize travelling time for the worker to go from one place to another. In addition, the plant also has a storage tank to store methanol and warehouse to store the end products. The warehouse is built with a loading and unloading bay for customers to collect the finished product. The loading and unloading bay is monitored by the guards in the guard room. Lastly, the plant also has garden for landscaping, parking lots and a security building. Trees are also planted in plant site to induce a good and healthy environment. Moreover, visitors lounge is equipped with an entertainment room for the guests and potential buyers.
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CHAPTER 3: PRELIMINARY HAZARD ANALYSIS 3.1 Introduction to Hazard Analysis System hazard analysis is the most crucial elements in the System Safety. The hazard analysis is the examination of a system to identify and classify each potential hazard according to its severity and like hood of occurrence and to develop the mitigation measures to those hazards to protect the public (Hardy, 2010). There are four main types of hazard analysis that regularly being used in the industries. i.
Preliminary Hazard Analysis (PHA).
The PHA starts in the concept phase of project. This analysis targeting to identify the safetycritical areas in the project, hazards and the safety design of the project. Besides that, it also focus in evaluating the hazards and the operation requirement in the project. This PHA will provide the important information regarding the causes and control of the hazards. It is the first step or initial effort in the hazard analysis that starts during the initial design phase of the project. The identification of the most ranked hazard and control measures will provide the basic or foundation to analysis that will come later as the cycle of project development in the progress. ii.
Subsystem Hazard Analysis (SSHA).
PHA is the precedent of SSHA. This SSHA was design to work on the safety risk assessment of the project‟s subsystem that is more detail and thorough than the information provided by PHA. The SSHA will checks and verifies that the design of the project‟s subsystem will follow the safety requirement and also explore the previously undetected hazards. It also checks on the risks of the subsystem‟s design, the human factor, and the functionality of the components. HHSA also investigate the
functional
relationship of the tools used including the software, and also suggesting the method of controlling the hazards. The SSHA effort should begin when the preliminary design and concept definition are established, and it should continue through the detailed design of components and software.
41
iii.
System/ Integrated Hazard Analysis (SHA/IHA).
Integrated Hazard Analysis should identify hazard causes and controls that cross system functional and physical boundaries and should identify the organizations responsible for assuring mitigation for the hazard causes. An integrated hazard is an event or condition that is caused by or controlled by multiple systems, elements, or subsystems. Systems that cross one or more system or element are considered integrated systems and they are addressed by an integrated hazard analysis. iv. The
Operating and Support Hazard Analysis (O&SHA). general
purpose
of
the
O&SHA
is
to
perform
a
detailed
safety risk
assessment of a system’s operational and support procedures. The O&SHA examines human induced hazards to hardware, software, equipment, facilities, and the environment. An O&SHA describes what a human can do to create hazards and how the hardware, software, equipment, facilities, and environment can create hazards for humans. Generally, the O&SHA examines those operations that are procedurally controlled activities. It identifies and evaluates hazards resulting from the implementation of operations or tasks performed by persons during maintenance.
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3.2
Previous Accidents on Similar Type of Plant 3.2.1 Explosion of drums in Kalyani, Nadia District, West Bengal, India The incident occurred on 26 Aug. 2001 around 2:45 p.m.in Kalyani, Nadia District, West Bengal,
India. On this day, ammonia was used as catalysts instead of the normal operation of using caustic soda. Hence, there was no safety procedure on using ammonia as catalyst, unlike the usage of caustic soda which the procedure was readily documented and well-known of. The operation was however started with manual control with the supervision of an expert. The phenol, formaldehyde and liquid ammonia were stored in separate storage tanks (Bhattacharjee, Neogi, & Das, 2014). Liquid ammonia was added manually by an operator into the reactor and stirring arrangement was started slowly. During the addition, the catalyst somehow spilled on the hand on the operator and he felt some burning effect out of the incident. The temperature of the reaction mass was already raised by steam heating to nearly 100ºC and it kept on shooting up drastically. The supervisor sensed the change of situation and instructed to drain the reaction mass into drums available from the plant. These few drums which had been filled up were closed with lids and transferred to open distance. There were still some reactants left in the reactor. According to Bhattacharjee et al., after few minutes, those drums exploded one after another. The residual mass in the reactor was drained to the other empty drums and those drums were not closed. These drums did not explode. Job hazard analysis (JHA) is a valuable technique used for hazard identification and risk assessment in industrial processes. JHA identified the proper job procedure after carefully studying and recording each step of the job and then identifying the existing or potential job hazards to determine the best way to perform the job to reduce or completely eliminate the hazards potential. The JHA consists of three main steps: 1. Identification–– chooses a specific job, break down the job into a sequence of stages and identify the possible incident that might occur during the work. 2. Assessment–– evaluate the risk that might occur during the work. 3. Action––measure to reduce or eliminate the risk.
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Table 8: Job hazard analysis (JHA) for explosion of drums in Kalyani, Nadia District, West Bengal, India (Bhattacharjee et al., 2014) Basic job steps
Potential hazards or injuries This process is based Wrong catalysts make on ammonia catalyst runaway reaction occur.
Cause
Adequate cooling Inadequate cooling arrangement increases temperature should be provided
As the temperature increases in the reactor, the reaction rate also increases. As the reaction rate increases the generation of water vapor also increases which increases the pressure in the reactor
Adequate vent arrangement in the extreme condition should be provided; otherwise, there is possibility of explosion due to over pressure.
In store, material should be kept in proper order. Display of MSDS in working areas is required to avoid mixing the wrong chemical in the process
Wrong reactants or catalysts or wrong sequences in the input to the reactor can also make the reaction runaway
Chemicals should be labelled and the use of PPEs for carrying the chemicals
Proper reactants or catalyst should be identified and used for the reaction and also used in proper sequence
Any kind of operating Accident, blast, or negligence explosion occurs
Required safe job procedures Wrong catalyst Proper catalyst should concentration nitric be added acid used
Reaction is highly Implement various exothermic, so any protective measures negligence can make such as trainings the situation accident prone
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3.2.2 Explosion in a resins production unit at Georgia-Pacific Resins, Inc. in Columbus, Ohio. At approximately 10:42 a.m. on Wednesday, Sept. 10, 1997, an explosion occurred in a resins production unit at Georgia-Pacific Resins, Inc. in Columbus, Ohio. The blast was reported to be felt at least 2 miles and possibly as far as 7 miles away according to various news accounts and other reports. As a result of the explosion, one worker was killed and four others injured. The explosion extensively damaged the plant. The explosion also resulted in the release of a large quantity of liquid resin and smaller quantities of other chemicals within the facility. Three fire fighters were injured during the response, treated for first-degree chemical burns, and released. Georgia-Pacific was manufacturing a phenolic resin in an 8,000-gallon batch reactor when the incident occurred. An operator charged raw materials and catalyst to the reactor and turned on steam to heat the contents. A high temperature alarm sounded and the operator turned off the steam. Shortly after, there was a large, highly energetic explosion that separated the top of the reactor from the shell. The top landed 400 feet away. The shell of the reactor split and unrolled, and impacted against other vessels. A nearby holding tank was destroyed and another reactor was partially damaged. The explosion killed the operator and left four other workers injured. Accident investigation had been performed and analyzed. Some of inherent safer design strategies such as moderate, minimize and substitute can be implemented here to prevent such incidents from happening in the future. Under substitution, the process of phenol-formaldehyde reactions can be substituted or amended with other alternative process routes. Typically, phenol-formaldehyde reactions are highly exothermic and sensitive to a variety of physical and chemical conditions. Once a reaction is initiated, heat generated by the reaction increases the reaction rate generating more heat. For minimization, we can look into minimizing the potential for human error occurrence. Possible human errors should be anticipated and carefully evaluated because a simple error could have catastrophic results. Managers should implement various protective measures, such as temperature control, instrumentation, and interlocks to eliminate opportunities for human error, especially in critical manual operations. To eliminate or rather reduce human error, standard operating procedures (SOPs) should always be updated and safe to be abided by the operators. Touching in the SOPs, it should be evaluated and modified when necessary to minimize the likelihood of an undetected human error. Supervisors should audit SOPs regularly, including the direct observation of employees and conducting employee interviews to ensure the SOPs are fully understood. Adequate numbers of trainings must be provided to the operator who is responsible to perform the specific job. New workers should be under close monitoring of supervisors when performing new procedures. They are also encouraged to work along-side with the experienced supervisors to pick-up new skills to handle the job better in the future, thus reducing human error occurrence indirectly.
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3.3
Material and Chemical Hazards in Feed 3.3.1 Methanol 3.3.1.1 Accidental release and first aid measures of methanol Inhalation of methanol is a major health concern. Inhalation of high airborne concentrations of
methanol can cause headaches, sleepiness, nausea, confusion and even death. The odor threshold of methanol is few times higher than the threshold limit value-time weighted average. Depending upon severity of poisoning and the promptness of treatment, survivors might suffer permanent blindness or nervous effects. Methanol however has minor effect to eye contact. It may cause eyes irritation and burning. In case of contact, immediately flush eyes with plenty of water for continuous 15 minutes. Methanol is a flammable liquid which can burn without a visible flame. The release can cause an immediate risk of fire and explosion. All ignition sources should be eliminated, absorbent materials should be used. Inherent safety design such as installation of dikes around methanol feed is favorable to contain spill from spreading to nearby equipment. Cleanup of methanol feed should be managed by same teams of trained workers only to make sure the consistency of operating procedures. While operating it, personal protective wear such as fire-fighting should be worn and all ignition sources should be kept far away. 3.3.1.2 Storage and handling of methanol When transferring or storing methanol, dedicated systems are preferable. Non-dedicated systems should be cleaned, flushed and sampled before being used, in order to ensure product integrity. Equipment should be clearly labeled to indicate that it is for methanol service only. When not in use, the equipment must be protected from contamination. In handling methanol, all ignition sources such as smoking and open flame should be eliminated. Passive protective measure such as explosion proof electrical equipment should be use. Furthermore, accurate procedural steps of using proper electrical grounding should be in place to avoid accidents. In terms of storage, methanol should be stored in enclosed area to avoid ignition and human contact for safety purpose. Dikes must be installed around the storage tank to avoid spreading of spill in case leakage occurs. Storage tanks of welded construction are normally satisfactory. They should be designed and built in conformance with good engineering practice for the material being stored. While plastics can be used for short term storage, they are generally not recommended for long-term storage due to deterioration effects and the subsequent risk of contamination.
46
3.4
Material and Chemical Hazards of By-products 3.4.1 Formic acid 3.4.1.1 Accidental release and first aid measures of formic acid In case of eye or skin contact, flush the affected part with tap water for continuous 15 minutes to
avoid irritation. If there is serious inhalation of formic acid, the victim should be evacuated to a safe area as soon as possible. Tight clothing is loosening up such as a collar, tie, belt or waistband. If breathing is difficult, oxygen is administered. If small spill of formic acid occurs, it is diluted with water and mop up, or absorbed with an inert dry material to be placed in an appropriate waste disposal container. 3.4.2 Carbon monoxide, CO 3.4.2.1 Accidental release and first aid measures of CO If CO is inhaled, remove to uncontaminated area. Artificial respiration must be provided if not breathing. If breathing is difficult, oxygen should be administered by qualified personnel. If large amount of CO is ingested, immediate medical attention is required. In terms of fire-fighting measures, CO has severe fire hazard and explosion hazard. The vapor is heavier than air, and may ignite at distant ignition sources and flash back. Vapor/air mixtures are explosive and containers may rupture or explode if exposed to heat. Under accidental release measure; heat, flames, sparks and other sources of ignition should be avoided. Water spray can be used to reduce vapors. Unnecessary people should be kept away from the area. This can be done by putting up safety labels or isolate the hazard area. 3.4.3 Carbon dioxide, CO2 3.4.3.1 Accidental release and first aid measures of CO2 In case of CO2 is contact to skin and frostbite or freezing occur, immediately flush with plenty of lukewarm water (105-115 F; 41-46 C). Hot water is prohibited to be applied. If warm water is not available, gently wrap affected parts in blankets. Get immediate medical attention.
3.5
Material and Chemical Hazards of Product 3.5.1 Formaldehyde 3.5.1.1 Accidental release and first aid measures of formaldehyde In case of accidental release of formaldehyde, rubber gloves and chemical splash goggles must be
put on to avoid skin and eye contact with the chemical. To clean up formaldehyde, absorbent paper is used to pick up all liquid spill material. The absorbent paper is then sealed, as well as contaminated clothing, in a vapor-tight plastic bag for eventual disposal. All contaminated surfaces are washed with a soap and water solution. For fire-fighting measure, alcohol foam, CO2, or dry chemical can be used to
47
fight fire. If there is skin contact with formaldehyde, the affected area must be washed thoroughly under flowing water with soap solution. 3.5.1.2 Storage and handling of formaldehyde When the workers are handling formaldehyde, PPE must always be worn. Hands washing must be performed after handling is done. Workers should have minimal direct contact of formaldehyde while handling it. Furthermore, formaldehyde should be stored in such place that is well-ventilated, cool and dry. Summary of the chemical and physical properties of the main chemical component involved, and potential hazards posed by the materials or chemicals used and produced by this plant are shown in Table 9. Table 9: Summary of chemical hazards information
Chemical
Class
Risk
Methanol
Flammable Irritant
Iron oxide
Formalin
Flash point
Safety Measures
Handling/storage
Can cause 11oC erythema or dermatitis. Toxicity can cause blindness.
First Aid: Rinse/wash affected area with running water, get fresh air. Fire Fighting: Use CO2 to extinguish, suppress gases with water jet
Keep in well-ventilated area, away from sources of ignition. Ensure all equipment is electrically grounded before transfer.
Irritant
Can cause lung -damage, irritating to eye and skin.
First Aid: Rinse/wash affected area with running water, get fresh air.
Ensure storage can support its weight and doesn’t strain in reaching for materials.
Irritant Corrosive
Carcinogenic 50oC and can cause inflammation
First Aid: Rinse/wash affected area with running water, get fresh air.
Keep away from heat. Keep away from sources of ignition. Ground all equipment containing material. Store in a segregated, cool, wellventilated area. Keep container tightly closed and sealed until ready for use.
Fire Fighting: Use dry chemical powder, alcohol foam, water spray or fog.
48
Formic acid
Corrosive Flammable
Can cause 49.5oC severe skin burns and eyes damage
First Aid: Rinse/wash affected area with running water, get fresh air. Take off clothing and don’t induce vomiting if swallowed Fire Fighting: Use water spray, alcoholresistant foam, dry chemical or carbon dioxide.
Ground all equipment and lines. Ensure absence of ignition source. Protect from physical damage. Store in upright position and in cool, dry, wellventilated area.
Methyl formate
Irritant
Toxic to 19oC nervous system and organs. Irritating to eyes and skin.
First Aid: Rinse/wash affected area with running water, get fresh air.
Ensure storage can support its weight and doesn’t strain in reaching for materials. Keep away from heat. Keep away from sources of ignition. Ground all equipment containing material. Store in a segregated, cool, wellventilated area. Refrigerated room is more preferable.
Fire Fighting: Use dry chemical powder, alcohol foam, water spray or fog.
Methane
Flammable
Asphyxiating 188oC and may cause frostbite.
First Aid: Flush affected area with cool/lukewarm water, get fresh air. Take off clothing and get fresh air. If necessary, give artificial resuscitation Fire Fighting: Use dry chemical or CO2. Water spray or fog. Do not extinguish a leaking gas fire unless leak can be stopped.
49
Ground all equipment and lines. Ensure absence of ignition source. Protect from physical damage. Store in upright position and in cool, dry, wellventilated area.
3.6
Possibility of Reducing Potential Consequences of an Accident 3.6.1 Implementing Inherent Safety Aspects An ‘inherently safer’ approach to hazard management is one that tries to avoid or eliminate
hazards, or reduce their magnitude, severity or likelihood of occurrence, by careful attention to the fundamental design and layout. Less reliance is placed on ‘add-on’ engineered safety systems and features, and procedural controls which can and do fail (Mansfield, Poulter, Kletz, & Britain, 1996). Table 10: Preventive measure to reduce risk at workplace Type of Description Example measure Minimize hazard using process or equipment Passive Containment dike around design features which reduce frequency or formaldehyde and methanol consequence without the active functioning of storage tanks. any device. Fire-resistant walls around methanol feed – methanol is highly flammable. Controls, safety interlocks, automatic shut down systems Multiple active elements Sensor -detect hazardous condition Logic device - decide what to do Control element -implement action Prevent incidents, or mitigate the consequences of incidents
Procedural Standard operating procedures, safety rules and standard procedures, emergency response procedures, training
Active
50
High level alarm in a tank shuts automatic feed valve A sprinkler system which extinguishes a fire Emergency shutdown system
Confined space entry procedures. Cleanup procedure for absorber
3.6.2 The Layers of Protection Analysis (LOPA) The various measures for prevention and mitigation of major accidents may be thought of as ‘lines of defence’ (LODs) or ‘layers of protection’ (LOPs). These lines or layers serve to either prevent an initiating event (such as loss of cooling or overcharging of a material to a reactor, for example) from developing into an incident (typically a release of a dangerous substance), or to mitigate the consequences of an incident once it occurs (Babu, 2007). This is illustrated in Figure 18 below.
Figure 23: Layers of Protection Concept
Other than focusing on the Layer of Protection Concept, designing an inherently safer system or facility is another good approach to prevent such a tragedy to take place in future. Inherently safer design is a new and different approach to chemical process safety. Instead of working with existing hazards in a chemical process and adding layers of protection, the engineer is challenged to reconsider the design and eliminate or reduce the source of the hazard within the process (Allen and Shonnard, 2012). Approaches to the design of inherently safer processes have been grouped into four categories of Minimize, Moderate, Substitute and Simplify which will has the further breakdown in Table 3 below.
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Table 11: Basic strategies in inherent safety chemical process Strategy
Description
Example
Minimize
Practice of using small quantities of hazardous substances or energy that involved in a certain process. By doing so, consequences of unwanted accidents such as fire and explosion can be eventually reduced. At the same time, it improves the effectiveness and feasibility of other protective system as well.
Size of methanol and formaldehyde storage tanks should be as practical as possible.
Moderate
Use less hazardous conditions or facilities
Usage of a suitable and compatible catalyst type to lower the activation energy of the reaction. Concentration of methanol in feed should be minimized to nearest possible without affecting the process production. Dilution is applied in our process route to inject methanol into produced formaldehyde.
Simplify
Designing the facility to make it easier to operate
Substitute
Changing process to use less hazardous materials to produce less hazardous reaction chemistry. In addition, we can also replace a hazardous material with a less hazardous one.
52
Reactors and absorbers should be designed to withstand the operation pressures to reduce the maintenance costs of equipment. Simplest process route with highest production should be used. Process route with less equipment create lesser hazards. Process route is substituted with the one gives lower operating cost.
3.7
Safety and Environmental Regulations 3.7.1 Requirements by Local Safety Regulations and Design Guidelines Through the designing the plant for the production of formaldehyde, we should taking care on
important aspect through the environment considerations as well to ensure safety compliances in the plant. In Malaysia, several laws and legislation to should be referred and followed such as Electricity Supply Act 1990, Occupational Safety and Health Act 1994 (OSHA), Environment Impact Assessment (EIA) Procedures and Requirements in Malaysia, Environmental Quality Act 1974 (EQA) and Factory and Machinery Act 1967 (FMA). The important of those legislations were to help us to designing a better plant that giving minimum impact to the surrounding neighborhood and also the long terms of environmental effect. PEAR refers as the effects of any single thing happened in the plant must be based on personnel, environment, assets and reputations of the company. Hence, they should be better mitigation measure for reduce any unwanted incident to occur. Proper planning in designing the equipment is required in providing the safest process with an economical value. The designing of the equipment should follow codes and standards that have been provided through American Society of Mechanical Engineers (ASME), American Petroleum Institute (API) or even PETRONAS Technical Standard (PTS) that is developed by PETRONAS. In compliance with process safety management, hazards as well should be identified earlier through Hazard and Operability Studies (HAZOP) which is the most common practice in any of petrochemical plants, Hazard Identification Study (HAZID), Layer of Protection Analysis (LOPA) or “What If” Study. It is important to maintain the asset integrity of the plant and ensure earlier prevention steps have been taken foreseeing any hazard that could happen threatening the safety of the plant. By following those rules, regulations and guidelines, the plant can proceed for its operation in taking considerations on the safety issues, hazard and environment perspective for mitigate the possible ways to generate sustainable development. Following are the industrial laws and acts that are to be adhered before designing a plant. 3.7.1.1
Environmental Quality Act (EQA) 1974
Malaysian government has established the legal and institutional framework for environmental protection. The purpose is to promote environmental friendly and sustainable development. During early stage of planning, investors are encouraged to consider the environmental factor. They should consider several factors including the pollution control, waste management, waste prevention and effluent waste water/discharge. The objective of this law is upon the prevention, abatement and control pollution and enhancement of environment by restricting discharge of waste which applies to the whole Malaysia. Follows are the subsidiaries act related to process plant industry:
53
a)
Environmental Quality (Prescribed Premises) (Scheduled Wastes Treatment and Disposal Facilities) Regulations 1989
b)
Environmental Quality (Clean Air) Regulations 1978
c)
Environmental Quality (Prescribed Activities) (Environmental Impact Assessment) Order 1987
d)
Environmental Quality (Prescribed Activities) (EIA) Order 1987
e)
Environmental Quality (Licensing) Regulations, 1977
f)
Environmental Quality (Sewage and Industrial Effluents) Regulations, 1979.
g)
Environmental Quality (Refrigerant Management) Regulations 1999.
h)
Environmental Quality (Scheduled Wastes) Regulations 2005
i)
Environmental
Quality
(Prescribed
Premises)
Facilities) Order 1989
54
(Scheduled
Treatment
and
Disposal
3.7.1.2
Occupational Safety and Health Act (OSHA) 1994
Occupational safety and health is a cross-disciplinary area concerned with protecting the safety, health and welfare of people engages in work or employment. The reasons for establishing good occupational safety and health standards are frequently identified as: •
Moral - An employee should not have to risk injury at work, nor should others associated with the work environment.
•
Economic- many governments realize that poor occupational safety and health performance results in cost to the state (for example through the social payments to the incapacitated, costs for medical treatment).
•
Legal - Occupational safety and health requirements may be reinforced in civil law and/or criminal law; it is accepted that without the extra "encouragement" of potential regulatory action or litigation, many organizations would not act upon their implied moral obligations.
The Occupational Safety and Health Act 1994 (Act 514) is a piece of Malaysian legislation which has been gazette on 25th February 1994 by the Malaysian parliament. The purpose of this act is to make further provision for securing that safety, health and welfare of persons at work, for protecting others against risks to safety or health in connection with the activities of persons at work. The Act has been applied throughout Malaysia to the industries specified in the First Schedule: 1.
Manufacturing
2.
Mining and Quarrying
3.
Construction
4.
Agriculture, Forestry and Fishing
5.
Utilities (electricity, gas, water and sanitary services)
6.
Transport, storage and communication
7.
Wholesale and retail trades
55
8.
Hotel and restaurants
9.
Finance, insurance, real estate and business services
10.
Public services and statutory authorities.
Follows are the list of regulations under this Act: 1. Occupational Policy
Safety
and
Health
(Employers'
Safety
and
Health
General
Statements) (Exception) Regulations 1995 2. Occupational Hazards)
Safety
and
Health
(Control
of
Industry
Major
Accident
Regulations 1996 3.
Occupational Safety and Health (Safety and Health Committee) Regulations 1996
4.
Occupational Safety and Health (Classification, Packaging and Labelling of Hazardous Chemicals) Regulations 1997
5.
Occupational Safety and Health (Safety and Health Officer) Regulations 1997
6.
Occupational Safety and Health (Prohibition of Use of Substance) Order 1999
7. Occupational Chemicals
Safety
and
Health
(Use
and
Standards
of
Exposure
of
Hazardous to Health) Regulations 2000 8.
Occupational
Safety
and
Health
(Notification
of
Accident,
Dangerous
Occurrence, Occupational Poisoning and Occupational Disease) Regulation 2004
56
CHAPTER 4: CONCEPTUAL DESIGN ANALYSIS 4.1
Preliminary Reactor Design
4.1.1 General Process for Formalin Production Formaldehyde reacts with many compounds to produce methylol derivatives. It can react with phenol, urea, melamine and even organometallic compounds to give metallic substituted methylol compounds. Formaldehyde is produced industrially from methanol. There are three processes that are mainly used in the industry to produce formaldehyde. The processes are as follow: A. Partial oxidation and dehydrogenation with air in the presence of silver catalyst crystals, steam, and excess methanol at 680-720°C with 97 - 98% conversion of methanol. B. Partial oxidation and dehydrogenation with air in the presence of crystalline silver or silver gauze, steam, and excess methanol at 600-650°C with 77-78% of methanol conversion. The conversion is completed by distilling the product and recycling the unconverted methanol. C. Oxidation only with excess air in the presence of a modified iron -molybdenum vanadium oxide at 250 - 400°C with 98 -99% methanol conversion.
In formaldehyde production plant, most uses methanol as their feedstock rather than using natural gas key compound as their feedstock as the process for converting the latter substances such as propane or butane are not major industrial significance for economic reasons. Methanol conversion process does not compete with processes that use partial dehydrogenation of CO or oxidation of methane because of the higher yields of the former process. As the main feedstock is methanol the specifications of the methanol for production of formaldehyde are listed in Table 10. Yet, crude aqueous methanol obtained by high-, mediumor low-pressure synthesis can also be used for those processes. The methanol contains low concentration of inorganic impurities and limited amounts of other inorganic compounds. Therefore the need for the methanol to be subjected to purification and preliminary distillation to remove low-boiling point components arises.
57
Table 12: Specifications of the methanol for production of formaldehyde Parameter
Specifications
Methanol content
> 99.85 wt%
Relative density
0.7928 g/cm3
Maximum boiling point range
1°C
Acetone and acetaldehyde content
< 0.003 wt%
Ethanol content
< 0.001 wt%
Volatile iron content
< 2 µg/L
Sulfur content
< 0.0001 wt%
Chlorine content
< 0.15 wt%
For the sake of simplicity the methanol feedstock is assumed to have 100% purity with specification as follows for our references:
Figure 24: Characteristics and features of methanol
58
4.1.2 Silver Catalyst Processes The silver catalyst processes to formaldehyde are usually taking place at an atmospheric pressure and at 600 - 720°C. The reaction temperature depends on the excess of methanol in the methanol-air mixture. The composition of the mixture must lie outside the explosive limits. The amount of air that is used is too, determined by the catalytic quality of the silver surface. The following main reactions occur during conversion of methanol to formaldehyde: CH3OH ≈ CH2O + H2 ΔH = +84kJ/mol
(1)
H2 + 1/2 O2 → H2O ΔH = -243 kJ/mol
(2)
CH3OH + 1/2 O2 → CH2O + H2O ΔH = -159 kJ/mol
(3)
The extent, to which each of these reactions occurs, depends on process data. However byproducts are also formed in the following secondary reactions. CH2O → CO + H2 ΔH = +12.5 kJ/mol
(4)
CH3OH + 3/2 O2 → CO2 + 2 H2O ΔH = -674 kJ/mol
(5)
CH2O + O2 → CO2 + H2O ΔH = -519 kJ/mol
(6)
Other byproducts include methyl formate, methane and formic acid. The endothermic dehydrogenation reaction (1) is highly temperature-dependent, conversion increasing from 50 % at 400°C to 90 % at 500°C and to 99% at 700°C. The temperature dependence of the equilibrium constant for reaction Kp is given by: log Kp = (4600/T)-6.470 Kinetic studies with silver on carrier show that reaction (1) is a first order reaction. Thus, the rate of formaldehyde formation is a function of the available oxygen concentration and the oxygen residence time on the catalyst surface: 𝑑𝑐𝐹 = 𝑘𝑐𝑜 𝑑𝑡 where cF
=
formaldehyde concentration
co
=
oxygen concetration
59
k
=
rate constant
t
=
time
A complete reaction mechanism for the conversion of methanol to formaldehyde over a silver catalyst has not yet been proposed but there are some authors postulate that a change in mechanism occurs at ca. 650°C. However there are new findings that look into the reactions mechanism from spectroscopic investigations which indicate the influence of different atomic oxygen species on reaction pathway and selectivity. The production of formaldehyde over a silver catalyst is carried out under strictly adiabatic conditions. Temperature measurements both above and in the silver layer show that sites still containing methanol are separated from sites already containing predominantly formaldehyde only by a few millimeters.. The oxygen in the process air is shared between the exothermic reactions, primarily reaction (2) and, to a lesser extent depending on the process used, the secondary reactions (5) and (6). Thus, the amount of processed air controls the desired reaction temperature and the extent to which endothermic reactions (1) and (4) occur. The addition of inert material to the reactants is also another important factor affecting the yield of formaldehyde and methanol conversion besides, the catalyst temperature. Water is added to spent methanol-water-evaporated feed mixtures and nitrogen is added to air and air-off-gas mixtures, which are recycled to dilute the methanol-oxygen reaction mixture. The throughput per unit of catalyst area provides another way of improving the yield and affecting the side reactions. The theoretical yield of formaldehyde obtained from reactions (1) - (6) can be calculated from actual composition of the plant off-gas by using the following equation: −1
(%𝐶𝑂2 ) + (%𝐶𝑂) 𝑌𝑖𝑒𝑙𝑑 (𝑚𝑜𝑙%) = 100 [+ 𝑟 + ] 0.528(%𝑁2 ) + (%𝐻2 ) − 3(𝐶𝑂2 ) − 2(%𝐶𝑂)
Percentage signifies concentrations in vol% and r is the ratio of mole of unreacted methanol to moles of formaldehyde produced. The equation takes into account the hydrogen and oxygen balance and the formation of byproducts.
60
4.1.2.1 Complete conversion of methanol (BASF)
Figure 25: Flowchart of formaldehyde production by the BASF process From Figure 20 above, the labelling of the equipment are as per follow: a) Evaporator b) Blower c) Reactor d) Boiler e) Heat exchanger f) Absorption column g) Steam generator h) Cooler i)
Super heater
61
4.1.2.2 Incomplete conversion and distillative recovery of methanol
Figure 26: Flowchart of formaldehyde production with recovery of methanol by distillation From Figure 21 above, the labelling of the equipment are as per follow: a) Evaporator b) Blower c) Reactor d) Boiler e) Distillation column f) Absorption column g) Steam generator h) Cooler i)
Super heater
j)
Anion-exchange unit
62
4.1.3
Formox Process
Figure 27: Flowchart of formaldehyde production by the Formox process From Figure 22 above, the labelling of the equipment are as per follow: a) Evaporator b) Blower c) Reactor d) Boiler e) Heat exchanger f) Formaldehyde absorption column g) Circulation system for heat-transfer oil h) Cooler i)
Anion-exchange unit
In Formox, a metal oxide (iron, molybdenum, or vanadium oxide) is used as a catalyst for methanol conversion to formaldehyde. Many of this process has been patented since 1921.
63
Usually the oxide mixture has an Mo:Fe atomic ratio of 1.5-2.0, small amounts of V2O5. CuO, Cr2O3, CoO and P2O5 are also present. Special conditions are prescribed for both the process and the activation of catalyst. The Formox process has been described as two-step oxidation reaction in the gaseous state which involves an oxidized and a reduced catalyst. CH3OH + Kox → CH2O + H2O + Kred Kred + ½ O2 → Kox
∆H= -159 kJ/mol
CH2O + ½ O2 ≈ CO + H2O
∆H= -215 kJ/mol
In the temperature range 270 – 400°C, conversion at atmospheric pressure is virtually complete. However, conversion is temperature dependent because at > 470°C the following side reaction increases considerably: CH2O + ½ O2 ≈ CO + H2O
∆H= -215 kJ/mol
The methanol oxidation is inhibited by water vapor. A kinetic describing the rate of reaction by a power law kinetic rate of expression of the form. 𝑦
𝑥 𝑟 = 𝑘𝑃𝐶𝐻 𝑃 𝑃𝑧 3 𝑂𝐻 𝑂2 𝐻2 𝑂
Where x = 0.94 ± 0.06; y = 0.10 ± 0.05 and z = -0.45 ± 0.07. The rate is independent of formaldehyde partial pressure. The measured activation energy is 98 ± 6 kJ/mol. Methanol feed is passed to a steam-heated evaporator. Freshly blown-in air and recycled off-gas from the absorption tower are mixed and, if necessary, pre-heated by means of the product stream in a heat exchanger before being fed into the evaporator. Atypical reactor for this process has a shell with a diameter of ca. 2.5 m that contains tubes only 1.0 – 1.5 m in length. A high-boiling heat transfer oil circulates outside the tubes and remove the heat of reaction from the catalyst in tubes. The process employs excess air and temperature is controlled isothermally to a value of ca. 340°C; steam is simultaneously regenerated in a boiler. The air-methanol feed must be a flammable mixture, but if the oxygen content is reduced to 10 mole% by partially replacing air with tail gas from absorption tower, the methanol content in the feed can be increased without forming an explosive mixture. After leaving the reactor, the gasses are cooled to 110°C in a heat exchange unit and are passed to the bottom of an absorber column. The formaldehyde concentration is regulated by controlling the amount of process water added at the top of the column. The product is removed from the water-cooled circulation system at the bottom of absorption column and is fed through an anion-exchange unit to reduce the formic acid content. The final product contains up to 55wt% formaldehyde and 0.5 – 1.5% wt %
64
methanol. The resultant methanol conversion ranges from 95 – 99 mol % and depends on the selectivity, activity, and spot temperature by the catalyst, the latter being influenced by the heat transfer rate and the throughput rate. The overall plant yield is 88 – 91 mol %. Well-known processes using the Formox method have been developed by Perstorp/Reichhil (Sweden, Great Britain, and United States), Lummus (United States), Montecatini (Italy), and Hiag/Lurgi (Austria). The tail gas does not burn by itself as it consists essentially of N2, O2, and CO2, with a few percent of combustible components such as dimethyl ether, carbon monoxide, methanol, and formaldehyde. Combustion of Formox tail gas for the purpose of generating is not economically justifiable. Two methods of reducing atmospheric emission have been developed. The off gas can be burned either with additional fuel at a temperature of 700 - 900°C or in a catalytic incinerator at 450 – 550°C. However the latter system employs a heat exchanger and is only thermal-efficient if supplementary fuel for start-up is provided and if abnormal ratio of oxygen: combustible components are used. 4.2 Process Operating Mode Chemical reactors are vessels designed to contain chemical reactions. It is the site of conversion of raw materials into products and is also called the heart of a chemical process. The design of a chemical reactor where bulk drugs would be synthesized on a commercial scale would depend on multiple aspects of chemical engineering. Since it is a very vital step in the overall design of a process, designers ensure that the reaction proceeds with the highest efficiency towards the desired output, producing the highest yield of product in the most cost effective way. Reactors are designed based on features like mode of operation or types of phases present or the geometry of reactors. They are thus called: •
Batch or Continuous depending on the mode of operation.
•
Homogeneous or Heterogeneous depending upon the phases present.
They may also be classified as: •
Stirred Tank Reactor
•
Tubular Reactor
•
Packed Bed Reactor
•
Fluidized Bed Reactor
65
4.2.1 Batch Operation
Figure 28: Batch operation Meanwhile, batch reactor is the generic term for a type of vessel widely used in the process industries. Its name is something of a contradiction since vessels of this type are used for a variety of process operations such as solids dissolution, product mixing, chemical reactions, batch distillation, crystallization, liquid/liquid extraction and polymerization. In some cases, they are not referred to as reactors but have a name which reflects the role they perform (such as crystallizer, or bio reactor). Batch operation has the following characteristics •
Time variant conditions
•
Discontinuous production
•
Downtime for cleaning and filling
•
Flexibility
Many reactors particularly in the fine chemical industry are operated in a pure batch manner. During the reaction period there is a change in substrate and product concentration with time. The other periods, example are emptying, cleaning, filling, are time lost. 4.2.1.1 Benefits of Batch Operation Batch reactors are very versatile and are used for a variety for different unit operations (batch distillation, storage, crystallization, liquid-liquid extraction etc). Batch operation is most flexible. Reactors can be used for multiple purposes. This is particularly important or the fine chemical industry where multiple products are produced in one plant. Batch reactors are excellent at handling difficult materials like slurries or products with a tendency to foul. Batch reactors represent an effective and economic solution for many types of slow reactions.
66
4.2.2 Continuous Operation
Figure 29: Continuous operations Continuous reactors (alternatively referred to as flow reactors) carry material as a flowing stream. Reactants are continuously fed into the reactor and emerge as continuous stream of product. Continuous reactors are used for a wide variety of chemical and biological processes within the food, chemical and pharmaceutical industries. A survey of the continuous reactor market will throw up a daunting variety of shapes and types of machine. Beneath this variation however lies a relatively small number of key design features which determine the capabilities of the reactor. When classifying continuous reactors, it can be more helpful to look at these design features rather than the whole system. Continuous operation has the following characteristics:
Continuous production
Steady state after start-up period (usually)
No variation of concentrations with time
Constant reaction rate
Ease of balancing to determine kinetics
No down-time for cleaning, filling, etc.
The steady state will develop only after a start-up period usually 4 times the residence time (t= V/F). Continuous reactors are mainly used for large-scale production. Frequent use is made of continuous reactors in the laboratory for studying kinetics.
67
4.2.2.1 Benefits of Continuous operation The rate of many chemical reactions is dependent on reactant concentration. Continuous reactors are generally able to cope with much higher reactant concentrations due to their superior heat transfer capacities. Plug flow reactors have the additional advantage of greater separation between reactants and products giving a better concentration profile. The small size of continuous reactors makes higher mixing rates possible. The output from a continuous reactor can be altered by varying the run time. This increases operating flexibility for manufacturers. Table below summaries the comparison of between batch and continuous process:
Table 13: Comparison of between batch and continuous process operation Description Types materials
Batch Process
Continuous Process
of Can be used with all types of Easier for use with flowing materials materials (with non-flow materials, (today, almost any material can be it is easier to use the batch process). produced with the continuous process; investment cost is the decisive factor).
Installation size
Relatively large installations. Very Relatively small installations. big investment in land and Significant savings in land and installations. installations.
Reactor
Changes occur in the concentrations At all locations, conditions are of materials over time. constant over time (durable conditions).
Volume produces
Better for production.
a
small-volume Better for large scale production and long run process.
Feeding raw Raw materials are fed before the Constant feeding of raw materials start of the reaction. during the entire reaction process. materials
It is easier to Control of the Simple control. set of actions control reaction conditions (pH, Manual in the system pressure, temperature). control can also be done.
68
Complex control. Automatic control must be used. Control of reactor conditions is more difficult. Control must be exercised over the rate of flow of the materials.
Product(s)
Extraction of materials only after all Continuous extraction of products at the actions is finished with the all times during the reaction. conclusion of the reaction.
Trouble shooting
A fault or dealing with a batch requiring “repair” does not cause problems in the other stages. Appropriate tests are conducted after each stage.
Quantities produced
Preferable when production of small Preferable for large scale production. quantities of a specific material is planned.
Variety products the plant
The installations are interconnected, so a fault in one causes a stoppage in all the others. Material that has been damaged cannot be repaired under the same working conditions. It must be isolated and the process restarted.
of Preferable when the plant produces a Preferable for a in wide variety of materials and when permanent product. the product is likely to be changed now and again, while using the same reactor.
Product development stage
central
and
Preferable when the process is Preferable after the conclusion of all relatively new and still unfamiliar. the stages of grossing-up and In this case the initial investment is economic feasibility tests. in a smaller batch reactor, and thus the economic risk is smaller.
69
Parameters Flow
Batch Operation Disconnected, with dominant flows Moderate Moderate High Moderate and Moderate
Flexibility Capital Investment Maintenance Cost Labour Skill Volume of Feed Product Product Quality Power Consumption Residence Time of Feed
Not constant High Long
some
Continuous Operation Continuous Very low Very high Moderate Very high Very high Constant Low Short
70
4.3
Preliminary Reactor Optimization 4.3.1 Incomplete conversion of methanol with distillative recovery of methanol 9
10
8 1
2
5
6
3
4
7
Figure 30: Block diagram of incomplete conversion of methanol with distillative recovery of methanol Streams Molar Flow (kmol/hr) MetOH H2O N2 O2 CH2O Total Mass Flow (kg/hr) MetOH H2O N2 O2 CH2O Total
1
2
3
4
5
6
7
8
9
10
100 0 3761.905 1000 0 4861.905
112.6 1.9682 3761.905 1000 0 4876.473
14.1876 100.3806 3761.905 950.7938 87.4 4914.667
14.1876 319.24 0 0 87.4 420.8276
0 100.5634 0 0 0 100.5634
0 0 3761.905 950.7938 0 4712.699
0.70938 220.6842 0 87.4 308.7936
13.47822 2.007612 0 0 0 15.48583
0.87822 0 0 0 0 0.87822
12.6 2.007612 0 0 0 14.60761
3200 0 105333.3 32000 0 140533.3
3603.2 35.4276 105333.3 32000 0 140972
454.0032 1806.851 105333.3 30425.4 2622 140641.6
454.0032 5746.32 0 0 2622 8822.323
0 1810.142 0 0 0 1810.142
0 0 105333.3 30425.4 0 135758.7
22.70016 3972.315 0 0 2622 6617.016
431.303 36.13702 0 0 0 467.4401
28.10304 0 0 0 0 28.10304
403.2 36.13702 0 0 0 439.337
71
4.3.2 Complete Conversion of methanol (BASF) 8
7
6 1
2
5
3
4
Figure 31: Block diagram of complete conversion of methanol (BASF) Streams Molar Flow (kmol/hr) MetOH H2O N2 O2 CH2O Total Mass Flow (kg/hr) MetOH H2O N2 O2 CH2O Total
1
2
3
4
5
6
7
8
100 0 3761.905 1000 0 4861.905
100 3.254 3761.905 1000 0 4865.159
3 100.254 3761.905 951.5 97 4913.659
3 244.9241 0 0 97 344.9241
0 146.6752 0 0 0 146.6752
0 2.00508 3761.905 951.5 0 4715.41
0 0 3761.905 951.5 4713.405
0 2.00508 0 0 0 2.00508
3200 0 105333.3 32000 0 140533.3
3200 58.572 105333.3 32000 0 140591.9
96 1804.572 105333.3 30448 2910 140591.9
96 4408.634 0 0 2910 7414.634
0 2640.153 0 0 0 2640.153
0 36.09144 105333.3 30448 0 135817.4
0 0 105333.3 30448 0 135781.3
0 36.09144 0 0 0 36.09144
72
4.3.3 Formox Process 8
7
6 1
2
5
3
4
Figure 32: Block diagram of Formox process Streams Molar Flow (kmol/hr) MetOH H2O N2 O2 CH2O Total Mass Flow (kg/hr) MetOH H2O N2 O2 CH2O Total
1
2
3
4
5
6
7
8
100 0 3761.905 1000 0 4861.905
100 3.254 3761.905 1000 0 4865.159
1 102.254 3761.905 950.5 99 4914.659
1 249.9741 0 0 99 349.9741
0 149.7652 0 0 0 149.7652
0 2.04508 3761.905 950.5 0 4714.45
0 0 3761.905 950.5 4712.405
0 2.04508 0 0 0 2.04508
3200 0 105333.3 32000 0 140533.3
3200 58.572 105333.3 32000 0 140591.9
32 1840.572 105333.3 30416 2970 140591.9
32 4499.534 0 0 2970 7501.534
0 2695.773 0 0 0 2695.773
0 36.81144 105333.3 30416 0 135786.1
0 0 105333.3 30416 0 135749.3
0 36.81144 0 0 0 36.81144
73
4.4
Economic Potential Analysis
4.4.1 Incomplete conversion of methanol with distillative recovery of methanol EP1 = Revenue – Cost of Raw Material =
6617.016 kg/hr (RM 490.00 per kg) – 100 kg/hr (RM 1.91688 per kg)
=
RM 3242, 146.52
4.4.2 Complete Conversion of methanol (BASF) EP1 = Revenue – Cost of Raw Material =
74114.63 kg/hr (RM 490.00 per kg) – 100 kg/hr (RM 1.91688 per kg)
=
RM 36315, 977.01
4.4.3 Formox Process EP1 = Revenue – Cost of Raw Material =
74114.63 kg/hr (RM 490.00 per kg) – 100 kg/hr (RM 1.91688 per kg)
=
RM36315, 977.01
74
4.5 Justification of Process Route Selection Considering the economics aspects of the three formaldehyde process in practice, it is certainly obvious that the size of the plant and the cost of methanol will be vital. The Formox process is proven to be advantageous. Regarding the attainable yield of formaldehyde; still, in comparison with the silver process, Formox requires larger plant and higher investment cost. For the purpose of cost comparison, a study has been carried out on basis of $ 200 /t and a plant production capacity of 20 000 t/a of 37 wt% formaldehyde. The results are tabulated as follows: Table 14: Economic comparison of three process routes Complete Methanol Conversion
Formox Process
6.6
Incomplete Conversion and Methanol Recovery 8.6
1.24
1.22
1.15
255 Methanol 250 Catalyst and 5 Chemical Byproduct credit n.a.. (stream) 12 Utilities LP Steam 3.4 Power purchased 3.4 Cooling water 2.9 Process water 2.4 267 Variable cost, $/t 27 Direct fixed cost, $/t 18 Total allocated fixed cost, $/t 312 Total cash cost, $/t 33 Depreciation, $/t 345 Production cost, $/t 33 Return of Capital investment (ROI), $/t 378 Cost of production and ROI, $/t
252 247 5
227 232 7
n.a.
12
20 9.5 4.3 2.8 3.3 272 29 20
13
321 43 364 43
291 48 339 48
407
387
Total capital investment, $/t Methanol Consumption, t/t Raw Materials, $/t
75
9.6
8.0 4 1.0 240 30 21
CHAPTER 5: HEAT INTEGRATION The objective of performing heat integration is to recover as much heat as possible in the overall process. It is one of the methods to minimize and eliminate unnecessary costs by optimizing the energy as efficient as possible. By introducing heat exchangers while maintaining the operating conditions where cold streams require heating and hot streams require cooling the maximum efficiency could be achieved. Pinch Temperature Method analysis is used for this particular matter.
5.1 Pinch Analysis Before proceeding to design the heat exchanger network in the formalin plant proposed, pinch analysis has been carried out. Through the analysis, the system maximization of heat recovery, “heating and cooling utility consumption minimization” and optimization for the selection of utility sources and the trade-off between energy costs and capital costs can be achieved. Listed below is the information required prior pinch analysis:
i.
Data extraction from streams
ii.
Problem Table Algorithm (PTA)
iii.
Construction of Composite Curve (CC) and Grand Composite Curve (GCC)
iv.
Heat Exchanger Network (HEN) design
5.1.1 Stream Data Extraction The first step of heat integration is the extraction and tabulation of hot streams and cold streams of the process. The detail is as follows:
Table 15: Stream Data Stream Name
Temperature Supply (°C)
Temperature Target (°C)
Duty (kW)
∆T
Cp (kW/°C)
Cold Stream 1 Cold Stream 2
126.3 25.07
150 150
371.6 1052
23.7 124.93
15.6793 8.42072
Hot Stream 1
343
110
4070
-233
17.4678
76
The data above are retrieved from aspen HYSYS simulation. The simulation does not include external utilities and thus may only be incorporated after this analysis. The values of Cp are calculated using the following equation. 𝑄 = 𝐶𝑝|∆𝑇| Which Q
=
duty of heater and cooler (kW)
Cp
=
Heat Capacity (kW/°C)
∆T
=
Change in temperature (°C)
5.1.2 Problem Table Algorithm Before calculating the minimum utility requirements, problem table algorithm is first executed by shifting of temperatures for both hot streams and cold streams. The minimum temperature difference, ΔTmin is set to be 20 ºC. The shifted temperature for each stream is calculated by using the equation as below: 𝑆ℎ𝑖𝑓𝑡𝑖𝑛𝑔 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑓𝑜𝑟 ℎ𝑜𝑡 𝑠𝑡𝑟𝑒𝑎𝑚 = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 −
∆𝑇𝑚𝑖𝑛 2
𝑆ℎ𝑖𝑓𝑡𝑖𝑛𝑔 𝑡𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑓𝑜𝑟 𝑐𝑜𝑙𝑑 𝑠𝑡𝑟𝑒𝑎𝑚 = 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 +
∆𝑇𝑚𝑖𝑛 2
Table 16: Shifted temperature Stream Name
Shifted Supply (°C)
Temperature Shifted Temperature Target Cp (°C) (kW/°C)
Cold Stream 1 Cold Stream 2
121.3 20.07
145 145
15.67932 8.420716
Hot Stream 1
348
115
17.46781
The tabulated data below is then used to carry out temperature interval heat balance. The enthalpy values (ΔH) are calculated by multiplying ΔT with Cp. The positive value of enthalpy (ΔH) indicates the domination of cold streams, where there is a net deficit of heat in that particular temperature interval. All is surplus and the heat integration is below the pinch.
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Table 17: Temperature Portioning Table T
∆T
Interval Streams
Cp (kW/°C)
∆H (kW)
(°C) 348
Surplus/ Deficit
H1 193
-17.46781
-3371.29
Surplus
23.7
-24.726414
-586.02
Surplus
6.3
-1.78849
-11.27
Surplus
94.93
15.67932
1488.44
Deficit
145
121.3 C1 115
20.07 C1
After getting the temperature interval heat balance done, the values of ΔH for each temperature intervals are used to carry out problem table cascade in order to determine the minimum hot/cold utility and the pinch temperature for hot and cold streams.
Table 18: Heat cascade diagram Based in the table above, the minimum hot utilities is QH,min = 0 kW and the minimum cold utilities is QC,min= 2480.18 kW. This indicates that it is a “threshold problem” where only cold utility is
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required in the process. The pinch temperature of the process is 348.0 ⁰C while the pinch temperature of hot stream and cold stream are shown as below. 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 𝑃𝑖𝑛𝑐ℎ 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 +
∆𝑇𝑚𝑖𝑛 2
𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, 𝑐𝑜𝑙𝑑 = 𝑃𝑖𝑛𝑐ℎ 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 −
∆𝑇𝑚𝑖𝑛 2
𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 348.0°𝐶 +
∆𝑇𝑚𝑖𝑛 2
𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 348.0°𝐶 + 5°𝐶 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 353°𝐶 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, 𝑐𝑜𝑙𝑑 = 348.0°𝐶 −
∆𝑇𝑚𝑖𝑛 2
𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 348.0° − 5°𝐶 𝑇𝑒𝑚𝑝𝑒𝑟𝑎𝑡𝑢𝑟𝑒 𝑝𝑖𝑛𝑐ℎ, ℎ𝑜𝑡 = 343°𝐶 All of the data above are used to construct composite curve and grand composite curve which are useful to determine the heat recovery and optimizing the energy. 5.1.3 Composite Curve Grand composite curve is constructed using the heat cascade as the total of surplus and deficit heat energy are added and by using this value a shifted temperature versus total heat accumulated is then plotted. From the grand composite curve, the heat generated and heat sink can be determined. Furthermore, the value of heat utilities and cold utilities requirement from the graph can be tallied with the heat cascade. Besides that, the heat recovery can too be determined to further optimize the energy so that the starting cost of the plant will reduce. An online tools/software (http://www.uicche.org/) has been used to plot the grand composite curve and composite curve. Below is the result for combined composite curve and grand composite curve.
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Figure 33: Combined composite curve
Figure 34: Grand composite curve
5.1.4 Heat Exchanger Network (HEN) Design During pairing of the streams, two rules must be obeyed to ensure the network is feasible: i.
The temperature difference, ΔT between a pair of hot stream and cold stream must always be greater than ΔTmin (10 ºC).
ii.
CP rule (i.e. Cp,hot ≤ Cp,cold for above pinch) must not be violated unless the pair is away from pinch.
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Besides, there are three rules of thumb that must be taken into consideration during designing heat exchanger network:
Do not transfer heat across the pinch
Do not use cold utilities above the pinch
Do not use hot utilities below the pinch
The Heat Exchanger Network design is shown as in the figure below. The amount of cold utilities requirement is 2480.18 kW while no hot utilities is required.
Figure 35: Heat Exchanger Network (HEN) grid
Looking at the diagram above, the pairing is done between hot stream 1 and cold stream 1. The pairing is according to the rule that mentioned previously; both ∆T is more than ∆Tmin; the streams are only at the below pinch region and thus Cp cold must be lower than Cp hot. The diagram above also indicates that a cooling utility is needed. As for this part, it is suggested to use cold water as a medium to cool the stream right after the integration is done. For this part, it is further explained in chapter 6.
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CHAPTER 6: PROCESS FLOWSHEETING A process flow diagram is developed before heat integration. It is as below.
Figure 36: PFD before integration
Figure 37: PFD after integration
As the summary of PFD after integration requires proper design of heat exchanger unit that will be done next semester, the following will be the summary report on the PFD before integration. The following diagram is a first process flow diagram that describes all the major properties of the stream and equipment involved in it.
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CONCLUSION AND RECOMMENDATION It has been proven conceptually that the setting up of a formalin plant in Malaysia is feasible and crucial in order to meet the global high demand especially in the Northeast Asia, North America and Europe region. Construction of formalin production plant in Malaysia is technically feasible, economically attractive, has high market potential, has feasible economic potential and environmentally friendly. The plant is designed in such a way that it is safe to operate with optimum production.
Methanol is chosen as the main raw material for the production of formalin by catalytic oxidation process. Formox process is chosen as the best process route because it yielded highest amount of formalin production which is 74114.63 kg/hr. Based on economic potential evaluation, it has higher profit compared to the other processes.
From the feasibility research that was carried out, Gurun, Kedah is identified to be the best location for formalin production plant due some important factors such as the availability of sea port for the easy access for import of raw material and export of product. Besides that, the utilities required by the proposed plant are available in sufficient amount.
As for recommendations, the project team discovered that there is a necessity to obtain more in depth information on the environmental effects of the process. Next, the detailed information regarding to the process such as reaction and equipment selection could be taken into consideration as it would affect the production of formalin. This information could add more value to the project.
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REFERENCES Anonymous. (1994). Formaldehyde (Vol. 16, pp. 10). New York: Schnell Publishing Company. Anonymous. (2000). Formaldehyde (Vol. 162, pp. 44-44). NEW YORK: CHEMICAL WEEK ASSOC. Babu, J Ramesh. (2007). Layer of Protection Analysis–An effective tool in PHA: Report. Bhattacharjee, Gargi, Neogi, Susmita, & Das, Sudip Kumar. (2014). Phenol–formaldehyde runaway reaction: a case study. International Journal of Industrial Chemistry, 5(2). doi: 10.1007/s40090-014-0013-9 Cheng, Wh-Hsun. (1994). Methanol production and use: CRC Press. Jasmir, Shah Nadzri Bin, & Nadzri, Shah. (2010). Reliability Centered Maintenance Implementation at CUF Kertih. Mansfield, D, Poulter, L, Kletz, T, & Britain, Great. (1996). Improving inherent safety. OFFSHORE TECHNOLOGY REPORT-HEALTH AND SAFETY EXECUTIVE OTH. McMorrow, Julia, & Talip, Mustapa Abdul. (2001). Decline of forest area in Sabah, Malaysia: relationship to state policies, land code and land capability. Global Environmental Change, 11(3), 217-230. Olah, George A, Goeppert, Alain, & Prakash, GK Surya. (2009). Beyond oil and gas: the methanol economy: John Wiley & Sons. Organization, World Health. (2001). Chapter 5.8 Formaldehyde. Air Quality Guidelines, 2. Pinto, Joseph P, Gladstone, G Randall, & Yung, Yuk Ling. (1980). Photochemical production of formaldehyde in Earth's primitive atmosphere. Science, 210(4466), 183-184.
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