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DESIGN PROJECT ± CHE 3204 CHAPTER 1: INTRODUCTION CHAPTER 1: INTRODUCTION 1.1 Problem statement The project is about designing a biodiesel plant for the production of 40,000 tons per year …Full description
The supply of energy for various operations such as transportation, power generation and heating is of critical concern in the world today. Fossil fuels like crude oil that have been the traditional source of energy are non-renewable. Prices of fossil fuels like crude oil and natural gas have increased significantly in the past five years. This, along with increasing concerns about global warming, has led to a search for alternatives to fossil fuels. Hence, the use of new sources of energy like fuel cells, solar energy or bioethanol has become a priority. Ethanol in particular shares some of the storage and distribution advantages traditional fuels hold over other energy sources like hydrogen. Ethanol, which is one important industrial chemical can be produced extensively from biomass such as corn (maize), corn cob, rice, sweet sorghum, cassava and other diversified carbohydrate-containing materials, Its production has increased all over the world in the last few years through both expansion of existing plants and construction of new facilities. "Ethanol from corn is a more environmentally sustainable fuel than oil" says Jeff Tweedy of Syngenta. "It represents a crucial boost to the rural economy". Jeff and his colleagues are keen to strengthen the position of corn in this forward–looking sector. "Syngenta is currently developing a corn that could raise the efficiency of ethanol plants. At this moment, producers have to add special enzymes needed in the conversion of starch into sugar", Tweedy say. "Our aim is to have a corn already containing the important alpha amylase enzyme, which is one of the key enzymes required for ethanol production". In the United States, ethanol is usually produced using a technology called the "Dry-grind process" that utilizes corn kernels as feedstock to produce ethanol. As a result of the effort to sustainably substitute ethanol for gasoline as transportation fuel, the production of ethanol in the United States has risen up to 6 billion gallons per year in 2006 (Singh, 2006). Growers of corn in the US now devote over one-ninth of the crop area to corn for biofuels. Each bushel of corn produces about 2.8gallons of ethanol. That works out approximately 760litres per hectare. One acre of corn can produce enough ethanol to run a car for about 115,000km on a 1:9 mix with conventional unleaded gasoline.
Historically, early internal combustion engines were built to run on a variety of fuels, including alcohols and alcohol-hydrocarbon blends. In 1907 the United States Department of Agriculture investigated the use of alcohol as a motor fuel. A subsequent study by the United States Bureau of Mines concluded that engines could provide up to 10% higher power on alcohol fuels than on gasoline. Mixtures of alcohol and gasoline were used on farms in the United States in the early 1900s. For transportation purposes, the first Ford Model T automobiles could be run on either gasoline or ethanol using a manually adjustable carburetor. However, the development of low cost gasoline displaced other automobile fuels and the diesel engine further solidified the hold of petroleum fuels on the transportation sector. Ethanol was occasionally used, particularly in rural regions, when gasoline supplies were short or when corn prices were low.
More recently Brazil has been producing bioethanol on a large scale and now runs most of its vehicles on ethanol-gasoline blends, thus proving the viability of ethanol as a fuel. It also provides proof that the market can accommodate a major shift in automative fuel. In the United States there are some Flexible Fuel Vehicles (FFVs) that run on a blend of ethanol and gasoline called E85 (85% ethanol and 15% gasoline).
The issue of feasibility of ethanol as a fuel has been under considerable debate. Early research indicated that the net energy balance in the production of corn-based ethanol is negative (Pimentel, 1991), in the sense that more energy is required to produce a unit of ethanol than what it provides when burned. More recent studies based on newer process data that also includes co-product energy credits indicate a positive net energy balance (Shapouri et al., 1995).
Fuel ethanol also presents some challenges. It is corrosive, and materials that normally would not be affected by low percentage ethanol blends, have been found to dissolve in the presence of higher ethanol concentrations. Dedicated ethanol vehicles must use unplated steel, stainless steel, black iron or bronze, which have all shown acceptable resistance to ethanol corrosion, or they have to use non-metallic materials such as thermoset reinforced fiberglass or neoprene rubber (IFQC, 2004).
AIM AND OBJECTIVES
The aim of this work is to design a plant model for the production of motor-grade ethanol (that can be used with gasoline) using corn syrup as feedstock. The objectives are as follows:
Designing a process plant with production capacity of 100,000-metric tons/year of fuel ethanol from corn syrup.
Determining methods for energy reduction of the fuel ethanol plant
Use of pervaporators to replace separation columns in the process.
Total Cost estimation for the plant
SCOPE OF WORK
This design work entails creating a model for producing fuel grade ethanol from corn syrup using Aspen HYSYS, calculating material and energy balances for the various streams, determining equipment specification and estimating total cost for the plant using Aspen HYSYS.
RELEVANCE OF WORK
This study can be used to improve the design and optimize the structure in the ethanol production process thereby minimizing the energy input and increasing energy efficiency.
Ethanol (ethyl alcohol) is an alcohol found in alcoholic beverages. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline. World ethanol production for transport fuel tripled between 2000 and 2007 from 17 billion to more than 52 billion liters. From 2007 to 2008, the share of ethanol in global gasoline type fuel use increased from 3.7% to 5.4%. In 2011 worldwide ethanol fuel production reached 22.36 billion U.S. liquid gallons (bg) (84.6 billion liters), with the United States as the top producer with 13.9 bg (52.6 billion liters), accounting for 62.2% of global production, followed by Brazil with 5.6 bg (21.1 billion liters). Ethanol fuel has a "gasoline gallon equivalency" (GGE) value of 1.5 US gallons (5.7 L), which means 1.5 gallons of ethanol produces the energy of one gallon of gasoline.
Ethanol fuel is widely used in Brazil and in the United States, and together both countries were responsible for 87.1% of the world's ethanol fuel production in 2011. Most cars on the road today in the U.S. can run on blends of up to 10% ethanol, and ethanol represented 10% of the U.S. gasoline fuel supply derived from domestic sources in 2011. Since 1976 the Brazilian government has made it mandatory to blend ethanol with gasoline, and since 2007 the legal blend is around 25% ethanol and 75% gasoline (E25). By December 2011 Brazil had a fleet of 14.8 million flex-fuel automobiles and light trucks and 1.5 million flex-fuel motorcycles that regularly use neat ethanol fuel (known as E100). Corn ethanol is ethanol made from corn that is used as a biomass. Corn ethanol is produced by means of ethanol fermentation and distillation. Corn ethanol is mainly used as an oxygenate in gasoline to produce a low level blend. To a lesser extent, it is used as fuel for E85 flex-fuel vehicles.
ENVIRONMENTAL AND SOCIAL ISSUES
Since most U.S. ethanol is produced from corn and the required electricity from many distilleries comes mainly from coal plants, there has been considerable debate on the sustainability of corn-based bio-ethanol in replacing fossil fuels. Controversy and concerns relate to the large amount of arable land required for crops and its impact on grain supply, direct and indirect land use change effects, as well as issues regarding its energy balance and carbon intensity considering the full life cycle of ethanol production, and also issues regarding water use and pollution due to the increase expansion of ethanol production.
The initial assumption that biofuels were good for the environment because they had a smaller carbon footprint is in debate over the contention that the production of grain alcohol, and therefore E85, may actually have a greater environmental impact than fossil fuel.
That view says that one must consider:
The impact of fertilizers and carbon requiring inputs vs carbon offsetting byproducts like distillers grains.
The carbon footprint of the agricultural machinery run to plant, harvest and apply chemicals.
The environmental impact of those chemicals themselves, including fertilizers and pesticides necessary for efficient mass-production of the grains used.
The larger amount of energy required to ship and process the grains and turn them into alcohol, versus the more efficient process of converting oil into gasoline or diesel.
Even resources such as water, needed in huge amounts for grain production, can have serious environmental impact, including ground water depletion, pollution runoff, and algae blooms from waste runoff.
The U.S. Department of Energy has published facts stating that current corn-based ethanol results in a 19% reduction in greenhouse gases, and is better for the environment than other gasoline additives such as MTBE. Ethanol produced today results in fewer greenhouse gas (GHG) emissions than gasoline and is fully biodegradable, unlike some fuel additives.
Today, on a life cycle basis, ethanol produced from corn results in about a 20 percent reduction in GHG emissions relative to gasoline. With improved efficiency and use of renewable energy, this reduction could be as much as 52 percent.
In the future, ethanol produced from cellulose has the potential to cut life cycle GHG emissions by up to 86 percent relative to gasoline.
Ethanol blended fuels currently in the market – whether E10 or E85 – meet stringent tailpipe emission standards.
Ethanol readily biodegrades without harm to the environment, and is a safe, high-performance replacement for fuel additives such as MTBE.
Others say that ethanol from corn, as a fuel available now, and cellulosic ethanol in the future are both much better fuels for the environment. Ethanol derived from sugar-beet as used in Europe or sugar-cane as grown in Brazil in industrial scale is generally seen as having a very positive CO2 balance with up to 80% reduction in well-to-wheel CO2. A University of Nebraska study in 2009 showed corn ethanol directly emits 51% less greenhouse gas than gasoline. However this study does not take into account the greenhouse gasses involved in production and transportation
ECONOMIC IMPACT OF CORN ETHANOL
The use of ethanol for fuel has had a damaging impact on food markets, especially in poorer countries. In the United States, ethanol is mostly made from yellow corn, and as the market boomed for alternative fuel, yellow corn went up in price. Many farmers saw the potential to make more money, and switched from white corn to yellow corn. White corn is the main ingredient of tortillas in Mexico, and as the supply dropped, the price doubled, making the base of most Mexican foods unaffordable. Many people see this as unacceptable, and want no overlap between food crops and fuel crops. Others point out that the earth is thought to be able to support double the current human population, and press that the resources available, such as unused farmable land, should be better handled.
The Renewable Fuels Association (RFA), the ethanol industry's lobby group, claims that ethanol production does increase the price of corn by increasing demand. RFA claims that ethanol production has positive economic effect for US farmers, but it does not elaborate on the effect for other populations where field corn is part of the staple diet. An RFA lobby document states that "In a January 2007 statement, the USDA Chief Economist stated that farm program payments were expected to be reduced by some $6 billion due to the higher value of a bushel of corn. Corn production in 2009 reached over 13.2 billion bushels, and a per acre yield jumped to over 165 bushels per acre.
On March 9, 2011, Senator Dianne Feinstein from California introduced a bill that repealed the corn subsidies in the U.S. She is quoted, telling Congress "Ethanol is the only industry that benefits from a triple crown of government intervention: its use is mandated by law, it is protected by tariffs, and companies are paid by the federal government to use it. It's time we end this practice once and for all".
Alternatives to corn as a feedstock
Remnants from food production such as corn stover could be used to produce ethanol instead of food corn.
The use of cellulosic biomass to produce ethanol is a new trend in biofuel production. Fuels from these products are considered second generation biofuels and are considered by some to be a solution to the food verses fuel debate. The possibility of using this material has been acknowledged by the scientific community and the political community as well. Bioethanol is a form of quasi-renewable energy that can be produced from agricultural feedstocks. It can be made from very common crops such as sugar cane, potato, cassava and corn. There has been considerable debate about how useful bioethanol is in replacing gasoline. Concerns about its production and use relate to increased food prices due to the large amount of arable land required for crops, as well as the energy and pollution balance of the whole cycle of ethanol production, especially from corn. Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.
Cellulosic ethanol offers promise because cellulose fibers, a major and universal component in plant cells walls, can be used to produce ethanol. According to the International Energy Agency, cellulosic ethanol could allow ethanol fuels to play a much bigger role in the future than previously thought.
CHEMISTRY OF FERMENTATION
During ethanol fermentation, glucose and other sugars in the corn (or sugarcane or other crops) are converted into ethanol and carbondioxide.
C6H12O6 2C2H5OH+ 2CO2 + heat
Like any fermentation reaction, the fermentation is not 100% selective, and other side products such acetic acid, glycols and many other products are formed to a considerable extent and need to be removed during the purification of the ethanol. The fermentation takes place in aqueous solution and the resulting solution after fermentation has an ethanol content of around 15%. The ethanol is subsequently isolated and purified by a combination of adsorption and distillation techniques. The purification is very energy intensive.
During combustion ethanol reacts with oxygen to produce carbon dioxide, water, and heat:
C2H5OH + 3O2 2CO2 + 3H2O + heat
Starch and cellulose molecules are strings of glucose molecules. It is also possible to generate ethanol out of cellulosic materials. That, however, requires a pretreatment that splits the cellulose into glycose molecules and other sugars that subsequently can be fermented. The resulting product is called cellulosic ethanol, indicating its source.
Ethanol may also be produced industrially from ethene (ethylene), by hydrolysis of the double bond in the presence of catalysts and high temperature.
C2H4 + H2O C2H5OH
By far the largest fraction of the global ethanol production, however, is produced by fermentation.
Ethanol is a quasi-renewable energy source because while the energy is partially generated by using a resource, sunlight, which cannot be depleted, the harvesting process requires vast amounts of energy that typically comes from non-renewable sources.
Creation of ethanol starts with photosynthesis causing a feedstock, such as sugar cane or a grain such as maize (corn), to grow. These feedstocks are processed into ethanol.
About 5% of the ethanol produced in the world in 2003 was actually a petroleum product. It is made by the catalytic hydration of ethylene with sulfuric acid as the catalyst. It can also be obtained via ethylene or acetylene, from calcium carbide, coal, oil gas, and other sources. Two million tons of petroleum-derived ethanol are produced annually. The principal suppliers are plants in the United States, Europe, and South Africa. Petroleum derived ethanol (synthetic ethanol) is chemically identical to bio-ethanol and can be differentiated only by radiocarbon dating.
Bio-ethanol is usually obtained from the conversion of carbon-based feedstock. Agricultural feedstocks are considered renewable because they get energy from the sun using photosynthesis, provided that all minerals required for growth (such as nitrogen and phosphorus) are returned to the land. Ethanol can be produced from a variety of feedstocks such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain, switchgrass, barley, hemp, kenaf, potatoes, sweet potatoes, cassava, sunflower, fruit, molasses, corn, stover, grain, wheat, straw, cotton, other biomass, as well as many types of cellulose waste and harvesting, whichever has the best well-to-wheel assessment.
An alternative process to produce bio-ethanol from algae is being developed by the company Algenol. Rather than grow algae and then harvest and ferment it, the algae grow in sunlight and produce ethanol directly, which is removed without killing the algae. It is claimed the process can produce 6,000 US gallons per acre (56,000 litres per ha) per year compared with 400 US gallons per acre (3,750 l/ha) for corn production.
Currently, the first generation processes for the production of ethanol from corn use only a small part of the corn plant: the corn kernels are taken from the corn plant and only the starch, which represents about 50% of the dry kernel mass, is transformed into ethanol. Two types of second generation processes are under development. The first type uses enzymes and yeast fermentation to convert the plant cellulose into ethanol while the second type uses pyrolysis to convert the whole plant to either a liquid bio-oil or a syngas. Second generation processes can also be used with plants such as grasses, wood or agricultural waste material such as straw.
There are two main types of corn ethanol production: dry milling and wet milling. The products of each type are utilized in different ways.
In the dry milling process the entire corn kernel is ground into flour and referred to as "meal." The meal is then slurried by adding water. Enzymes are added to the mash that converts starch to dextrose, a simple sugar. Ammonia is added to control the pH and as a nutrient for the yeast, which is added later. The mixture is processed at high-temperatures to reduce the bacteria levels and transferred and cooled in fermenters. This is where the yeast is added and conversion from sugar to ethanol and carbon dioxide begins.
The entire process takes between 40 to 50 hours, during which time the mash is kept cool and agitated in order to facilitate yeast activity. After the process is complete, everything is transferred to distillation columns where the ethanol is removed from the "stillage". The ethanol is dehydrated to about 200 proof using a molecular sieve system and a denaturant such as gasoline is added to render the product undrinkable. With this last addition, the process is complete and the product is ready to ship to gasoline retailers or terminals. The remaining stillage then undergoes a different process to produce a highly nutritious livestock feed. The carbon dioxide released from the process is also utilized to carbonate beverages and to aid in the manufacturing of dry ice.
The process of wet milling takes the corn grain and steeps it in a dilute combination of sulfuric acid and water for 24 to 48 hours in order to separate the grain into many components. The slurry mix then goes through a series of grinders to separate out the corn germ. Corn oil is a byproduct of this process and is extracted and sold. The remaining components of fiber, gluten and starch are segregated out using screen, hydroclonic and centrifugal separators.
The gluten protein is dried and filtered to make a corn gluten- meals co-product and is highly sought after by poultry broiler operators as a feed ingredient. The steeping liquor produced is concentrated and dried with the fiber and sold as corn gluten feed to in the livestock industry. The heavy steep water is also sold as a feed ingredient and is used as an environmentally friendly alternative to salt in the winter months. The corn starch and remaining water can then be processed one of three ways: 1) fermented into ethanol, through a similar process as dry milling, 2) dried and sold as modified corn starch, or 3) made into corn syrup.
The production of corn ethanol uses water in two ways – irrigation and processing. There are two types of ethanol processing, wet milling and dry milling, and the central difference between the two processes is how they initially treat the grain. In wet milling, the corn grain is steeped in water, and then separated for processing in the first step. Dry milling, which is more common, requires a different process. According to a report by the National Renewable Energy Laboratory, "Over 80% of U.S. ethanol is produced from corn by the dry grind process".
The basic steps for large-scale production of ethanol are: microbial (yeast) fermentation of sugars, distillation, dehydration (requirements vary), and denaturing (optional).
Prior to fermentation, some crops require saccharification or hydrolysis of carbohydrates such as cellulose and starch into sugars. Saccharification of cellulose is called cellulolysis. Enzymes are used to convert starch into sugar.
Ethanol is produced by microbial fermentation of the sugar. Microbial fermentation currently only works directly with sugars. Two major components of plants, starch and cellulose, are both made of sugars—and can, in principle, be converted to sugars for fermentation. Currently, only the sugar (e.g., sugar cane) and starch (e.g., corn) portions can be economically converted. There is much activity in the area of cellulosic ethanol, where the cellulose part of a plant is broken down to sugars and subsequently converted to ethanol.
For the ethanol to be usable as a fuel, the majority of the water must be removed. Most of the water is removed by distillation, but the purity is limited to 95–96% due to the formation of a low-boiling water-ethanol azeotrope with maximum (95.6% m/m (96.5% v/v) ethanol and 4.4% m/m (3.5% v/v) water). This mixture is called hydrous ethanol and can be used as a fuel alone, but unlike anhydrous ethanol, hydrous ethanol is not miscible in all ratios with gasoline, so the water fraction is typically removed in further treatment to burn in combination with gasoline in gasoline engines.
There are basically three dehydration processes to remove the water from an azeotropic ethanol/water mixture. The first process, used in many early fuel ethanol plants, is called azeotropic distillation and consists of adding benzene or cyclohexane to the mixture. When these components are added to the mixture, it forms a heterogeneous azeotropic mixture in vapor–liquid-liquid equilibrium, which when distilled produces anhydrous ethanol in the column bottom, and a vapor mixture of water, ethanol, and cyclohexane/benzene.
When condensed, this becomes a two-phase liquid mixture. The heavier phase, poor in the entrainer (benzene or cyclohexane), is stripped of the entrainer and recycled to the feed—while the lighter phase, with condensate from the stripping, is recycled to the second column. Another early method, called extractive distillation, consists of adding a ternary component that increases ethanol's relative volatility. When the ternary mixture is distilled, it produces anhydrous ethanol on the top stream of the column.
ENERGY REDUCTION METHODS FOR DEHYDRATION
With increasing attention being paid to saving energy, many methods have been proposed that avoid distillation altogether for dehydration. This new process includes:
USE OF MOLECULAR SIEVES: In this process, ethanol vapor under pressure passes through a bed of molecular sieve beads. The bead's pores are sized to allow absorption of water while excluding ethanol. After a period of time, the bed is regenerated under vacuum or in the flow of inert atmosphere (e.g. N2) to remove the absorbed water. Two beds are often used so that one is available to absorb water while the other is being regenerated. This dehydration technology can account for energy saving of 3,000 btu/gallon (840 kJ/L) compared to earlier azeotropic distillation.
PERVAPORATION: A definition of the process is provided by Yeom et al., (1996) and Chang et al., (1998), 'pervaporation is a membrane process used for the separation of liquid mixtures by means of partial vaporization across a permselective membrane. The permeate is then obtained as a liquid by condensation. The driving force for permeation is established by maintaining a difference in partial pressure of the permeate across the membrane. This is accomplished in vacuum pervaporation by lowering the total pressure on the downstream side of the membrane. 'The separation process is mainly due to the polarity difference and not on the volatility difference of the components in the feed. There are three different types of pervaporation processes namely:
Vapour phase permeation
BATCH PERVAPORATION: These systems are simple and flexible, but a buffer tank is required. They are ideal for smaller throughputs. The liquid feed from a batch tank is pumped through heat exchangers to recover the heat content from the product stream. It is then passed continuously through the membrane separation modules. The membrane modules are contained within vacuum chambers. The permeate is condensed and the retenate is returned back to the tank. With every pass, the retenate gradually becomes more and more concentrated. The process is then repeated until the desired purification level is achieved.
CONTINUOUS PERVAPORATION: This process consumes very little energy, operates best with low impurities in the feed and is best for larger capacities. Continuous units are typically used in a manufacturing environment where larger throughputs are required. Feed is preheated and continuously passed through a series of membrane separation modules, which are located in a vacuum chamber. Permeate from the modules is then condensed. A vacuum pump removes the incondensable from the system. To maintain a high removal efficiency of permeating components, the heat of vaporization is provided by the inter-stage heaters.
Flow diagram for Batch Pervaporation
Flow Diagram for Continuous Pervaporation
VAPOUR PHASE PERMEATION: This process is preferred for direct feeds from distillation columns or for streams with dissolved solids. However as there are no dissolved solids in the feed for this plant, this method does not need to be considered any further.
Ethanol is most commonly used to power automobiles, though it may be used to power other vehicles, such as farm tractors, boats and airplanes. Ethanol (E100) consumption in an engine is approximately 51% higher than for gasoline since the energy per unit volume of ethanol is 34% lower than for gasoline.
The higher compression ratios in an ethanol-only engine allow for increased power output and better fuel economy than could be obtained with lower compression ratios. In general, ethanol-only engines are tuned to give slightly better power and torque output than gasoline-powered engines. In flexible fuel vehicles, the lower compression ratio requires tunings that give the same output when using either gasoline or hydrated ethanol. For maximum use of ethanol's benefits, a much higher compression ratio should be used. Current high compression neat ethanol engine designs are approximately 20 to 30% more fuel efficient than their gasoline-only counterparts.
Ethanol contains soluble and insoluble contaminants. These soluble contaminants, halide ions such as chloride ions, have a large effect on the corrosivity of alcohol fuels. Halide ions increase corrosion in two ways; they chemically attack passivating oxide films on several metals causing pitting corrosion, and they increase the conductivity of the fuel. Increased electrical conductivity promotes electric, galvanic, and ordinary corrosion in the fuel system. Soluble contaminants, such as aluminum hydroxide, itself a product of corrosion by halide ions, clog the fuel system over time.
Ethanol is hygroscopic, meaning it absorbs water vapor directly from the atmosphere. Because absorbed water dilutes the fuel value of the ethanol (although it suppresses engine knock) and may cause phase separation of ethanol-gasoline blends, containers of ethanol fuels must be kept tightly sealed. This high miscibility with water means that ethanol cannot be efficiently shipped through modern pipelines, like liquid hydrocarbons, over long distances. Mechanics also have seen increased cases of damage to small engines, in particular, the carburetor, attributable to the increased water retention by ethanol in fuel.
A 2004 MIT study and an earlier paper published by the Society of Automotive Engineers identify a method to exploit the characteristics of fuel ethanol substantially better than mixing it with gasoline. The method presents the possibility of leveraging the use of alcohol to achieve definite improvement over the cost-effectiveness of hybrid electric. The improvement consists of using dual-fuel direct-injection of pure alcohol (or the azeotrope or E85) and gasoline, in any ratio up to 100% of either, in a turbocharged, high compression-ratio, small-displacement engine having performance similar to an engine having twice the displacement. Each fuel is carried separately, with a much smaller tank for alcohol. The high-compression (for higher efficiency) engine runs on ordinary gasoline under low-power cruise conditions. Alcohol is directly injected into the cylinders (and the gasoline injection simultaneously reduced) only when necessary to suppress 'knock' such as when significantly accelerating. Direct cylinder injection raises the already high octane rating of ethanol up to an effective 130. The calculated over-all reduction of gasoline use and CO2 emission is 30%. The consumer cost payback time shows a 4:1 improvement over turbo-diesel and a 5:1 improvement over hybrid. The problems of water absorption into pre-mixed gasoline (causing phase separation), supply issues of multiple mix ratios and cold-weather starting are also avoided.
Ethanol's higher octane rating allows an increase of an engine's compression ratio for increased thermal efficiency. In one study, complex engine controls and increased exhaust gas recirculation allowed a compression ratio of 19.5 with fuels ranging from neat ethanol to E50. Thermal efficiency up to approximately that for a diesel was achieved. This would result in the fuel economy of a neat ethanol vehicle to be about the same as one burning gasoline. Since 1989 there have also been ethanol engines based on the diesel principle operating in Sweden. They are used primarily in city buses, but also in distribution trucks and waste collectors. The engines, made by Scania, have a modified compression ratio, and the fuel (known as ED95) used is a mix of 93.6% ethanol and 3.6% ignition improver, and 2.8% denaturants. The ignition improver makes it possible for the fuel to ignite in the diesel combustion cycle. It is then also possible to use the energy efficiency of the diesel principle with ethanol. These engines have been used in the United Kingdom by Reading Transport but the use of bioethanol fuel is now being phased out.
ENGINE COLD START DURING WINTER
High ethanol blends present a problem to achieve enough vapor pressure for the fuel to evaporate and spark the ignition during cold weather (since ethanol tends to increase fuel enthalpy of vaporization). When vapor pressure is below 45 kPa starting a cold engine becomes difficult. To avoid this problem at temperatures below 11 °C (52 °F)), and to reduce ethanol higher emissions during cold weather, both the US and the European markets adopted E85 as the maximum blend to be used in their flexible fuel vehicles, and they are optimized to run at such a blend.
At places with harsh cold weather, the ethanol blend in the US has a seasonal reduction to E70 for these very cold regions, though it is still sold as E85. At places where temperatures fall below 12 °C (10 °F) during the winter, it is recommended to install an engine heater system, both for gasoline and E85 vehicles. Sweden has a similar seasonal reduction, but the ethanol content in the blend is reduced to E75 during the winter months.
Brazilian flex fuel vehicles can operate with ethanol mixtures up to E100, which is hydrous ethanol (with up to 4% water), which causes vapor pressure to drop faster as compared to E85 vehicles. As a result, Brazilian flex vehicles are built with a small secondary gasoline reservoir located near the engine. During a cold start pure gasoline is injected to avoid starting problems at low temperatures. This provision is particularly necessary for users of Brazil's southern and central regions, where temperatures normally drop below 15 °C (59 °F) during the winter. An improved flex engine generation was launched in 2009 that eliminates the need for the secondary gas storage tank. In March 2009 Volkswagen do Brasil launched the Polo E-Flex, the first Brazilian flex fuel model without an auxiliary tank for cold start.
ETHANOL FUEL MIXTURES
To avoid engine stall due to "slugs" of water in the fuel lines interrupting fuel flow, the fuel must exist as a single phase. The fraction of water that an ethanol-gasoline fuel can contain without phase separation increases with the percentage of ethanol. This shows, for example, that E30 can have up to about 2% water. If there is more than about 71% ethanol, the remainder can be any proportion of water or gasoline and phase separation does not occur. The fuel mileage declines with increased water content. The increased solubility of water with higher ethanol content permits E30 and hydrated ethanol to be put in the same tank since any combination of them always results in a single phase. Somewhat less water is tolerated at lower temperatures. For E10 it is about 0.5% v/v at 70 F and decreases to about 0.23% v/v at 30 F.
In many countries cars are mandated to run on mixtures of ethanol. All Brazilian light-duty vehicles are built to operate for an ethanol blend of up to 25% (E25), and since 1993 a federal law requires mixtures between 22% and 25% ethanol, with 25% required as of mid July 2011. In the United States all light-duty vehicles are built to operate normally with an ethanol blend of 10% (E10). At the end of 2010 over 90 percent of all gasoline sold in the U.S. was blended with ethanol. In January 2011 the U.S. Environmental Protection Agency (EPA) issued a waiver to authorize up to 15% of ethanol blended with gasoline (E15) to be sold only for cars and light pickup trucks with a model year of 2001 or newer. Other countries have adopted their own requirements.
Beginning with the model year 1999, an increasing number of vehicles in the world are manufactured with engines that can run on any fuel from 0% ethanol up to 100% ethanol without modification. Many cars and light trucks (a class containing minivans, SUVs and pickup trucks) are designed to be flexible-fuel vehicles using ethanol blends up to 85% (E85) in North America and Europe, and up to 100% (E100) in Brazil. In older model years, their engine systems contained alcohol sensors in the fuel and/or oxygen sensors in the exhaust that provide input to the engine control computer to adjust the fuel injection to achieve stochiometric (no residual fuel or free oxygen in the exhaust) air-to-fuel ratio for any fuel mix. In newer models, the alcohol sensors have been removed, with the computer using only oxygen and airflow sensor feedback to estimate alcohol content. The engine control computer can also adjust (advance) the ignition timing to achieve a higher output without pre-ignition when it predicts that higher alcohol percentages are present in the fuel being burned. This method is backed up by advanced knock sensors – used in most high performance gasoline engines regardless of whether they are designed to use ethanol or not – that detect pre-ignition and detonation.
HYDROUS ETHANOL CORROSION
High alcohol fuel blends are reputed to cause corrosion of aluminum fuel system components. However, studies indicate that the addition of water to the high alcohol fuel blends helps prevent corrosion. This is shown in SAE paper 2005-01-3708 Appendix 1.2 where gasoline/alcohol blends of E50, nP50, IP50 nB50, IB50 were tested on steel, copper, nickel, zinc, tin and three types of aluminum. The tests showed that when the water content was increased from 2000ppm to 1%, corrosion was no longer evident except some materials showed discolouration.
In theory, all fuel-driven vehicles have a fuel economy (measured as miles per US gallon, or liters per 100 km) that is directly proportional to the fuel's energy content. In reality, there are many other variables that come into play that affect the performance of a particular fuel in a particular engine. Ethanol contains approx. 34% less energy per unit volume than gasoline, and therefore in theory, burning pure ethanol in a vehicle reduces miles per US gallon 34%, given the same fuel economy, compared to burning pure gasoline. Since ethanol has a higher octane rating, the engine can be made more efficient by raising its compression ratio. In fact, using a variable turbocharger, the compression ratio can be optimized for the fuel, making fuel economy almost constant for any blend. For E10 (10% ethanol and 90% gasoline), the effect is small (~3%) when compared to conventional gasoline, and even smaller (1–2%) when compared to oxygenated and reformulated blends. For E85 (85% ethanol), the effect becomes significant. E85 produces lower mileage than gasoline, and requires more frequent refueling. Actual performance may vary depending on the vehicle. Based on EPA tests for all 2006 E85 models, the average fuel economy for E85 vehicles resulted 25.56% lower than unleaded gasoline. The EPA-rated mileage of current United States flex-fuel vehicles should be considered when making price comparisons, but E85 is a high performance fuel, with an octane rating of about 94–96, and should be compared to premium.
In one estimate the US retail price for E85 ethanol is 2.62 US dollar per gallon or 3.71-dollar corrected for energy equivalency compared to a gallon of gasoline priced at 3.03-dollar. Brazilian cane ethanol (100%) is priced at 3.88-dollar against 4.91-dollar for E25 (as July 2007).
CONSUMER PRODUCTION SYSTEMS
While biodiesel production systems have been marketed to home and business users for many years, commercialized ethanol production systems designed for end-consumer use have lagged in the marketplace. In 2008, two different companies announced home-scale ethanol production systems. The AFS125 Advanced Fuel System from Allard Research and Development is capable of producing both ethanol and biodiesel in one machine, while the E-100 MicroFueler from E-Fuel Corporation is dedicated to ethanol only.
EXPERIENCE BY COUNTRY
The world's top ethanol fuel producers in 2011 were the United States with 13.9 billion U.S. liquid gallons (bg) (52.6 billion liters) and Brazil with 5.6 bg (21.1 billion liters), accounting together for 87.1% of world production of 22.36 billion US gallons (84.6 billion liters). Strong incentives, coupled with other industry development initiatives, are giving rise to fledgling ethanol industries in countries such as Germany, Spain, France, Sweden, China, Thailand, Canada, Colombia, India, Australia, and some Central American countries.
All biomass goes through at least some of these steps: it needs to be grown, collected, dried, fermented, and burned. All of these steps require resources and an infrastructure. The total amount of energy input into the process compared to the energy released by burning the resulting ethanol fuel is known as the energy balance (or "energy returned on energy invested"). Figures compiled in a 2007 by National Geographic Magazine point to modest results for corn ethanol produced in the US: one unit of fossil fuel energy is required to create 1.3 energy units from the resulting ethanol. The energy balance for sugarcane ethanol produced in Brazil is more favorable, with one unit of fossil-fuel energy required to create 8 from the ethanol. Energy balance estimates are not easily produced, thus numerous such reports have been generated that are contradictory.
For instance, a separate survey reports that production of ethanol from sugarcane, which requires a tropical climate to grow productively, returns from 8 to 9 units of energy for each unit expended, as compared to corn, which only returns about 1.34 units of fuel energy for each unit of energy expended. A 2006 University of California Berkeley study, after analyzing six separate studies, concluded that producing ethanol from corn uses much less petroleum than producing gasoline. Carbon dioxide, a greenhouse gas, is emitted during fermentation and combustion. This is canceled out by the greater uptake of carbon dioxide by the plants as they grow to produce the biomass. When compared to gasoline, depending on the production method, ethanol releases less greenhouse gases.
Compared with conventional unleaded gasoline, ethanol is a particulate-free burning fuel source that combusts with oxygen to form carbon dioxide, water and aldehydes. The Clean Air Act requires the addition of oxygenates to reduce carbon monoxide emissions in the United States. The additive MTBE is currently being phased out due to ground water contamination, hence ethanol becomes an attractive alternative additive. Current production methods include air pollution from the manufacturer of macronutrient fertilizers such as ammonia.
A study by atmospheric scientists at Stanford University found that E85 fuel would increase the risk of air pollution deaths relative to gasoline by 9% in Los Angeles, US: a very large, urban, car-based metropolis that is a worst-case scenario. Ozone levels are significantly increased, thereby increasing photochemical smog and aggravating medical problems such as asthma.
In 2002, monitoring the process of ethanol production from corn revealed that they released VOCs (volatile organic compounds) at a higher rate than had previously been disclosed. The U.S. Environmental Protection Agency (EPA) subsequently reached settlement with Archer Daniels Midland and Cargill, two of the largest producers of ethanol, to reduce emission of these VOCs. VOCs are produced when fermented corn mash is dried for sale as a supplement for livestock feed. Devices known as thermal oxidizers or catalytic oxidizers can be attached to the plants to burn off the hazardous gases.
The calculation of exactly how much carbon dioxide is produced in the manufacture of bioethanol is a complex and inexact process, and is highly dependent on the method by which the ethanol is produced and the assumptions made in the calculation. A calculation should include:
The cost of growing the feedstock
The cost of transporting the feedstock to the factory
The cost of processing the feedstock into bioethanol
Such a calculation may or may not consider the following effects.
The cost of the change in land use of the area where the fuel feedstock is grown.
The cost of transportation of the bioethanol from the factory to its point of use
The efficiency of the bioethanol compared with standard gasoline
The amount of Carbon Dioxide produced at the tail pipe.
The benefits due to the production of useful bi-products, such as cattle feed or electricity.
The January 2006 Science article from UC Berkeley's ERG, estimated reduction from corn ethanol in GHG to be 13% after reviewing a large number of studies. In a correction to that article released shortly after publication, they reduce the estimated value to 7.4%. A National
Geographic Magazine overview article (2007) puts the figures at 22% less CO2 emissions in production and use for corn ethanol compared to gasoline and a 56% reduction for cane ethanol. Carmaker Ford reports a 70% reduction in CO2 emissions with bioethanol compared to petrol for one of their flexible-fuel vehicles.
An additional complication is that production requires tilling new soil which produces a one-off release of GHG that it can take decades or centuries of production reductions in GHG emissions to equalize. As an example, converting grass lands to corn production for ethanol takes about a century of annual savings to make up for the GHG released from the initial tilling.
Change in land use
Large-scale farming is necessary to produce agricultural alcohol and this requires substantial amounts of cultivated land. University of Minnesota researchers report that if all corn grown in the U.S. were used to make ethanol it would displace 12% of current U.S. gasoline consumption. There are claims that land for ethanol production is acquired through deforestation, while others have observed that areas currently supporting forests are usually not suitable for growing crops. In any case, farming may involve a decline in soil fertility due to reduction of organic matter, a decrease in water availability and quality, an increase in the use of pesticides and fertilizers, and potential dislocation of local communities. New technology enables farmers and processors to increasingly produce the same output using less inputs.
Cellulosic ethanol production is a new approach that may alleviate land use and related concerns. Cellulosic ethanol can be produced from any plant material, potentially doubling yields, in an effort to minimize conflict between food needs vs. fuel needs. Instead of utilizing only the starch by-products from grinding wheat and other crops, cellulosic ethanol production maximizes the use of all plant materials, including gluten. This approach would have a smaller carbon footprint because the amount of energy-intensive fertilisers and fungicides remain the same for higher output of usable material. The technology for producing cellulosic ethanol is currently in the commercialization stage.
Using biomass for electricity instead of ethanol
Converting biomass to electricity for charging electric vehicles may be a more "climate-friendly" transportation option than using biomass to produce ethanol fuel, according to an analysis published in Science in May 2009 "You make more efficient use of the land and more efficient use of the plant biomass by making electricity rather than ethanol", said Elliott Campbell, an environmental scientist at the University of California at Merced, who led the research. "It's another reason that, rather than race to liquid biofuels, we should consider other uses of bio-resources".
For bioenergy to become a widespread climate solution, technological breakthroughs are necessary, analysts say. Researchers continue to search for more cost-effective developments in both cellulosic ethanol and advanced vehicle batteries.
Health costs of ethanol emissions
For each billion ethanol-equivalent gallons of fuel produced and combusted in the US, the combined climate-change and health costs are $469 million for gasoline, $472–952 million for corn ethanol depending on biorefinery heat source (natural gas, corn stover, or coal) and technology, but only $123–208 million for cellulosic ethanol depending on feedstock (prairie biomass, Miscanthus, corn stover, or switchgrass).
Efficiency of common crops
As ethanol yields improve or different feedstocks are introduced, ethanol production may become more economically feasible in the US. Currently, research on improving ethanol yields from each unit of corn is underway using biotechnology. Also, as long as oil prices remain high, the economical use of other feedstocks, such as cellulose, become viable. By-products such as straw or wood chips can be converted to ethanol. Fast growing species like switchgrass can be grown on land not suitable for other cash crops and yield high levels of ethanol per unit area.
Reduced petroleum imports and costs
One rationale given for extensive ethanol production in the U.S. is its benefit to energy security, by shifting the need for some foreign-produced oil to domestically produced energy sources. Production of ethanol requires significant energy, but current U.S. production derives most of that energy from coal, natural gas and other sources, rather than oil. Because 66% of oil consumed in the U.S. is imported, compared to a net surplus of coal and just 16% of natural gas (2006 figures), the displacement of oil-based fuels to ethanol produces a net shift from foreign to domestic U.S. energy sources.
According to a 2008 analysis by Iowa State University, the growth in US ethanol production has caused retail gasoline prices to be US $0.29 to US $0.40 per gallon lower than would otherwise have been the case.
There are various social, economic, environmental and technical issues with biofuel production and use, which have been discussed in the popular media and scientific journals. These include: the effect of moderating oil prices, the "food vs fuel" debate, poverty reduction potential, carbon emissions levels, sustainable biofuel production, deforestation and soil erosion, loss of biodiversity, impact on water resources, as well as energy balance and efficiency.
Leon Duray qualified third for the 1927 Indianapolis 500 auto race with an ethanol-fueled car. The IndyCar Series adopted a 10% ethanol blend for the 2006 season, and a 98% blend in 2007. In drag racing, there are Top Alcohol classes for dragsters and funny cars since the 1970s.
The American Le Mans Series sports car championship introduced E10 in the 2007 season to replace pure gasoline. In the 2008 season, E85 was allowed in the GT class and teams began switching to it.
In 2011, the three national NASCAR stock car series mandated a switch from gasoline to E15, a blend of Sunoco GTX unleaded racing fuel and 15% ethanol. Ethanol fuel may also be utilized as a rocket fuel. As of 2010, small quantities of ethanol are used in lightweight rocket-racing aircraft.
REPLACEMENT OF KEROSENE
There is still extensive use of kerosene for lighting and cooking in less developed countries, and ethanol can have a role in reducing petroleum dependency in this use too. A non-profit named Project Gaia seeks to spread the use of ethanol stoves to replace wood, charcoal and kerosene. There is also potential for bioethanol replacing some kerosene use in domestic lighting from feedstocks grown locally. Pure ethanol is a very flammable fuel and hence dangerous to use in rural households. Thus a specially designed stove cum lantern running on 50% ethanol water mixture has been tested by Nimbkar Agricultural Research Institute in rural areas.
MATERIAL AND ENERGY BALANCE
If the ethanol plant is taken as a single system, the overall inputs and outputs at the system boundary will be as represented in the figure below. The inputs are corn and water plus energy, while the outputs are ethanol, solids (by products), wastewater, and CO2.
The above single unit can be further broken down into smaller unit operations which includes: milling, mashing, cooking, liquefaction, saccharification, fermentation, pervaporation, solids separation, evaporation, and drying. To resolve the material balance for the corn to ethanol plant, we first define the unit operations of the block diagram which will subsequently guide us in the development of the process flow diagram and mass balance across each of the units.
WATER + SO2 STEAM ENZYMES
Bi2 Ci2 Ci3
CORN MILLING MEAL MASHING MASH COOKING/LIQUEFACTION WASTEWATER
Ai (A) Ao Bi1 (B) Bo Ci1 (C) Co1
ENZYMES LIQUIDIFED MASH
Di3 Di2 Di1 WATER
ULTRA-FILTRATION MASH FERMENTATION CO2 SCRUBBER Eo1
Fo1 (F) Fi1 Do1 (D) Do2 Ei1 (E) WASTEWATER
H2O RESIDUE FROM FILTER DR YER DDGS
Go2 PERVAPORATOR 1 Hi (H) Io2
ETHANOL + WATER
H20 PERVAPORATOR 2 Ethanol > 97% STORAGE
Ho2 (H) Ho1 Ji TANK
Block Diagram of the Corn-Ethanol Plant.
Process Flow Diagram of the Corn-Ethanol Plant.
For each of the block the material balance is written as:
Materials In = Materials Out
i.e Mi = Mo (i = input; o = output)
The mass balance calculation starts with corn inputs. The table below lists the composition of corn.
MASS CONTENT (%)
ETHANOL PRODUCTION: Process Calculations
[C6H10O5]n + (n-1) H2O n [C6H12O6]
Molecular wt. of Glucose: 12 X 6 +1 X 12 + 16 X 6 = 180g/mol
Avg. Monomer weight of starch/ cellulose:
12 X 6+1 X 10 + 16 X 5 = 162g/mol
Mol. Wt of Water: 18g/mol
Hydrolytic gain = (n 180)/ (n 162+18) = 1.11
For every glucose monomer, one molecule of water is added during hydrolysis and therefore results in increased substrate weight during starch/cellulose hydrolysis. This increase is referred to as Hydrolytic gain.
Efficiency of hydrolysis process is determined by many factors including composition, pretreatment, enzyme concentration and operating conditions.
Efficiency of enzymatic starch hydrolysis (70-95%) is dependent on amylose/amylopectin ratio and resistant starch.
C6H12O6 2C2H5OH + 2CO2 + Heat
Fermenting one mole glucose, results in 2 moles of ethanol and 2 moles of carbon dioxide.
On a weight basis:
180 g of glucose 92 g ethanol + 88 g Carbon dioxide
i.e. Ethanol = 0.51 glucose (w/w);
Carbon dioxide=0.49 glucose (w/w)
Efficiency of well controlled fermentation is very high (>95% conversion efficiency).
Ethanol Yield Calculation:
What is the yield of corn ethanol (gal per bushel) in a conventional dry grind process?
Basis: Corn (10% moisture, 70% starch, 7% protein, 6% oil, 5% fiber, 2% ash)
Resistant starch is 3% of total starch
Efficiency of hydrolysis is 95%.
Efficiency of fermentation is 98%.
DDGS moisture content as 12% (wb)
One bushel = 56lb = 56 / 2.2 = 25.45kg
Total starch= 25.45 x 0.70 = 17.82kg
Resistant starch = 0.03 x 17.82 = 0.54kg
Hydrolysable starch = 17.82 - 0.54 = 17.28kg
Glucose produced = 0.9 x 1.11 x 17.28 = 17.27kg
Ethanol produced = 0.98 x 0.51 x 17.27= 8.63kg
Gal of ethanol = 8.63 / 3 = 2.88 gallons of ethanol
DDGS (dry weight) = 17.82 x (0.07 + 0.06 + 0.05 + 0.02) + Resistant starch + residual starch = 3.564 + 0.54 + 17.28 X 0.1 = 5.83kg
DDGS (Assuming 12% moisture) = 1.12 x 5.83 =6.53kg
Ethanol Yield = 2.88 Gal/ bushel of corn
Overall process efficiency = 0.9 x 0.98 = 0.882
From the yield gotten, we can further evaluate the amount of corn needed to produce 100,000 metric tonnes of ethanol since it requires 25.45kg to produce 8.63kg of ethanol (i.e 8.63 / 25.45 = 0.339).
METRIC TONNES TO KG (PLANT CAPACITY)
100,000 metric tonnes = 100,000 X 1000 = 100,000,000kg of ethanol / year
REQUIRED CORN FEEDSTOCK
100,000,000 / 0.339 = 294,985,250.74kg of corn
Expressed in bushel = 294,985,250.74 / 25.45 = 11,590,776 bushel of corn.
Assuming plant's uptime of 95% per annum, plant's operating hours is calculated by:
0.95 X 365 X 24 = 8322 hours
Corn feedstock per hour = 294,985,250.74 / 8322 = 35,446.44kg corn / hour.
To help simplify our design basis, we will be working with a flow rate expressed in seconds. That is, 35,446.44kg corn / hour to kg corn / sec = 35,446.44 / 3600 = 9.84 kg corn / sec.
Process Flow Calculations Biofuel Feedstock and Production
Basis: 9.8 kg of Corn / sec. (10% moisture, 70% starch, 7% protein, 6% fiber, 5% oil, 2% ash)
Resistant starch is 3% of total starch
Efficiency of hydrolysis (liquefaction and saccharification) is 95%.
Efficiency of fermentation is 98%.
Efficiency of Scrubbing is 90%
Efficiency of Ultra-filtration is 98%
Efficiency of Pervaporation is 95%
Composition of stream leaving fermenter 15% ethanol, 75% water and 10% mash.
DDGS moisture content as 12% (wb)
Mash solids content is 34%
From the feedstock calculation above, it is clear that we require a corn feed rate of 9.8 kg/sec to be able to deliver an annual production sum of 100,000 metric tonnes (100,000,000kg) ethanol per year with our assumed plant operating hour of 95% per annum (8322 hours).
The mass balance calculation starts with corn inputs. The starch (the actual material that makes ethanol) is then mixed with water and turns into glucose followed by fermentation and production of ethanol.
Corn : 9.84kg corn/sec
Starch in corn : At 70% starch content in corn = 0.7 X 9.84 = 6.89kg starch
Water : 0 kg
Corn grits (grinded) : 9.84kg corn/sec
Starch in corn : 6.89kg corn/sec
Water : 0kg
Starch at 70% corn grits = 39.61% X 0.7 = 27.74% starch content in corn mash leaving mash.
In determining the amount of water required to prepare the mash, we assumed equal volume of water to corn grits to help ensure that a well-watered slurry is formed. The density of corn grits and water are given as 673kg/m3 and 1000kg/m3 respectively. Therefore:
Volume of 9.84kg corn grits = 9.84 = 0.015m3
Mass of water with that volume of 0.015m3 = Volume X Density = 0.015 X 1000 = 15kg water
These expressions are from the basic mass, density, volume relationship i.e Volume = Mass
In determining the amount of steam and enzymes used in the liquefaction stage, we looked up literature for the exact specifications prescribed for this process. 0.0555kg is the amount of water required for every 1kg of starch hydrolyzed. Regarding the enzymes needed in the reactions, the amount of α-amylase to be added is 0.05% w/w of the corn. (Ramkumar, et. al, 2008)
Since 1kg of starch requires 0.0555kg water, 6.89kg starch will require 6.89 X 0.0555 = 0.38kg starch. But we fed water in excess of 0.12kg to help ensure that the starch is the limiting reactant in the hydrolytic process. This excess 0.12kg water is recovered alongside resistant starch and enzyme's waste in the wastewater.
0.05 w/w of enzymes to corn mash = 0.05 X 24.84 = 1.24kg α-amylase
This is how we came about the steam requirement of 0.5kg and 1.24kg enzymes for the hydrolysis process.
Since only 0.38kg/sec water is used up in the hydrolysis phase, the remaining water of 0.12kg and enzymes 1.24kg are removed from the system as waste. Since the enzymes are solely involved in catalyzing the process, they are removed alongside the excess water after hydrolysis. Therefore;
Wastewater = 0.12 + 1.24 = 1.36kg/sec wastewater
In determining the amount of glucoamylase needed for saccharification and the yeast required for fermentation, we again consulted the work of Ramkumar, et. al. For fermentation 2.765×10-4 kg yeast per kg corn feed processed while the required glucoamylase is 0.12% w/w of the incoming mash. (Ramkumar, et. al, 2008)
0.0012kg w/w of glucoamylase to incoming mash = 0.0012 X 25.22 = 0.03kg glucoamylase/sec fed in.
The amount of yeast used in the fermenter is a function of the amount of corn feed. (Ramkumar, et. al, 2009). Corn feed is 9.84kg. Therefore:
Yeast required = 9.84 X fermentation 2.765X10-4 = 2.72X10-3kg/sec required
The reaction stoichiometry on a weight basis can be written as:
HYDROLYSIS OF STARCH
2(C6H10O5)n + nH2O α-amylase nC12H22O11
244g 18g 254g
1kg starch + 0.0555kg water α-amylase 1.0555kg maltose
1kg maltose + 0.0526kg water α-amylase 1.0526kg glucose
From our design assumptions:
0.97 = % of hydrolysable starch.
0.95 = % efficiency of hydrolysis.
Hydrolysable starch = 97%. Therefore starch in fermenter is gotten as:
0.97 X 6.89 X 0.95 = 6.35kg/sec hydrolysable starch. Where 6.89kg is the total starch content in the corn. Relating the hydrolysable starch in the process to the chemical equations above, it is deducible that since 1kg starch yields 1.0555kg maltose, 6.35kg starch will produce 6.35 X 1.0555 = 6.70kg maltose. This maltose will further yield 6.70 X 1.0526 = 7.05kg glucose since 1kg maltose is known in chemistry to produce 1.0526kg glucose.
From the fermentation reaction on mass basis, we observe that 1kg glucose yields 0.47kg ethanol and 0.42kg carbon dioxide. Considering this, our 7.05kg/sec of glucose will yield:
ETHANOL: 7.05 X 0.47 = 3.31kg ethanol/sec
CO2 : 7.05 X 0.42 = 2.96kg CO2/sec
But since 98% efficiency is assumed for the fermentation process, this yield cannot be obtained in practice, we must multiply through by 0.98 to get the obtainable yield. i.e:
ETHANOL at 98% Efficiency: 3.31 X 0.98 = 3.23kg ethanol/sec
CO2 at 98% Efficiency: 2.90 X 0.98 = 2.90kg CO2/sec
Also from our design assumption of 15% of alcohol content in the fermented mash, we have total mash mass = 3.23 = 21.53kg/sec fermented mash leaving fermenter.
75% water in this stream is: 21.53 X 0.75 = 16.15kg H20 in stream / sec
10% mash in stream: 21.53 X 0.10 = 2.15kg mash in stream / sec
Since there are only two outlets in the fermenter, every other component leaves via Do2 as unfermented starch, other corn components and resistant starch. This feed is gotten by subtracting the fermented mash from the total feed mass. i.e:
Total feed – Output 1 = Output 2
25.22 + 0.03 + 2.72X10-03 - 21.53 = 3.72300kg/sec
This is how the outputs from the fermenter were determined.
Low conc. CO2 : 3.723kg
Water : 1kg
Highly Conc. CO2 : 2.61kg
Wastewater : 2.113kg
Since the efficiency of the scrubber is taken to be at 90% and the feed to the scrubber is 3.7230kg/sec of which 2.90kg is CO2 (from calculations in fermenter above). A 90% scrubber will only be able to extract CO2 of 2.90 X 0.9 = 2.61kg CO2/sec.
Assuming a wash water with feed rate of 1kg/sec into the scrubber, the output from the bottom of the scrubber is gotten as:
Wash water + unextracted CO2 + mash = 1kg + (2.90 – 2.61= 0.29) + (3.7230 – 2.90 = 0.823) = 2.11kg wastewater / sec.
Fermented Mash : 21.53kg
Water : 1kg
Filtrate : 19.03kg
Residue : 2.50kg
Filter is supposed to remove the 10% solids that in the fermented mash from the fermenter i.e (0.1 X 21.53 = 2.153kg). But at 98% ultra-filter efficiency only 0.98 X 2.153 = 2.11kg solids are removed. The inefficiency of 2% also results in the removal of 2% ethanol and water. i.e:
0.02 X 3.23 = 0.065kg Ethanol removed alongside solids by filter.
0.02 X 16.15 = 0.32kg Water removed alongside solids by filter.
Total mass of residue = water removed + ethanol removed + solids removed = 0.32 + 0.065 + 2.11 = 2.50kg wet residue / sec
Filtrate is gotten by simply subtracting the amount of residue from the feed into filter:
Total feed – residue = filtrate
21.53 - 2.50 = 19.03kg filtrate /sec
Composition of feed leaving filter:
Mass of components in feed – mass removed in residue = new mass stream
Ethanol: 3.23 -- 0.065 = 3.17kg ethanol / sec
Water: 16.15 – 0.32 = 15.83kg water / sec
Mash : 2.15 -- 2.11 = 0.043kg mash / sec
PERVAPORATOR 1 (G)
Filtrate from filter : 19.03kg
Water removed : 15.67kg
Impure Ethanol : 3.36kg
Since the pervaporator is assumed to operate at a 99% efficiency, it will be able to remove 0.99 X 15.83 = 15.67kg water / sec. This leaves our second output with a mass of 3.36kg/sec with new water content of 15.83 – 15.67 = 0.16kg H2O / sec now left in the stream, ethanol of 3.17 kg/sec and solid mash of 0.043kg mash / sec
Total mass of stream to pervaporator 2 = Input - Permeate
19.03 – 15.67 = 3.36kg feed to second pervaporator.
3.17kg of the 3.36kg fed to pervaporator 2 is ethanol, this gives an ethanol concentration of:
3.17 X 100 = 94.35% ethanol
Water removed : 0.157kg
Conc. Ethanol : 3.20kg
Pervaporator 2 is assumed to operate at a 98% efficiency, it will be able to remove 0.98 X 0.16 = 0.157kg water / sec. This leaves our second output with a mass of (3.36 – 0.157) = 3.203kg/sec with new water content of 0.16 – 0.157 = 0.003kg H2O / sec now left in the stream, ethanol of 3.17 kg/sec and solid mash of 0.043kg mash / sec
Total mass of ethanol stream to storage = Input - Permeate
3.36 – 0.15 = 3.21kg / sec feed to storage.
3.17kg/sec of the 3.21kg / sec to storage is ethanol, this gives an ethanol concentration of:
3.17 X 100 = 98.75% ethanol
0.003 X 100 = 0.09% water
0.043 X 100 = 1.33% mash
This ethanol concentration of 98.75% is considered commercial grade and pure enough for automobile usage, therefore we can afford to store till it is transported to either point of sale or use.
Residue from Filter : 2.50kg
DDGS : 2.4kg
Wastewater : 0.1kg
For a feed of 2.50kg/sec coming into the dryer from the filter:
We have already established in the material balance for the filter that 2.11kg/sec is solid mash, which 2.11 X 100 = 84.4% solids. This means we have a moisture content of 100 - 84.4 = 15.6%.
It is required that the moisture content in the DDGS be reduced to 12%.
At 12% moisture, DDGS weight will be 88% = 2.11 = 2.40kg/sec. This means the mass of the
DDGS and moisture combined must be reduced to 2.40kg/sec, this can only be achieved in the dryer by removal moisture of 2.5 – 2.4 = 0.1kg moisture / sec.
The energy balance for the various streams are shown in the workbook for each of them from the ASPEN HYSYS Simulation. The molar enthalpy, heat flow and molar entropy for each stream is presented in a table below the workbook.
EQUIPMENT SPECIFICATION AND SIZING
The fermenter has a cylindrical geometry and is vertical in orientation. For a fermenter design, a Conversion Reactor is preferable to a batch reactor or continuous stirred tank reactor for several reasons which include: Large throughput, easier online analysis, simplicity and Batch reactor would require inoculation with new microbes following each batch. The required volume for the fermenter is 2600 m3, some allowance is needed in order to take account of the volume displaced by cooling tubes. It is also wise to apply a 'safety factor' in design so the final volume will stand at 2700 m3. Modeling the fermenter as a cylinder and a hemisphere, a further spreadsheet can be created to allow various parameters to be altered and the relevant overall dimensions can be found. From these dimensions, it is then feasible to calculate the surface area of the fermenter.
The heat transfer coefficient between the vessel fluid and the wall can be found from the relation:
Nu = 0.023Re0.8Pr0.4
Where Reynold's number (Re) is given by:
Here D is the impeller diameter whilst N is the motor speed in revs per second.
For the heat transfer coefficient between the vessel wall and the air, the relevant correlation can be found to be:
Nu = 0.13(GrPr) 1/3
Due to its relatively low cost, good structural properties and high availability, steel is the material of choice for construction. However, steel is prone to corrosion (rusting) and although only trace amounts of oxygen should be present in the fermenter (a prerequisite for rust), some form of galvanizing will be required. Stainless steel has not been considered due to its high cost. Carrying out a simple stress analysis on the vessel, the hoop stress can be found to be a maximum of 245kPa. Analyzing the fermenter as a thin walled pressure vessel, the thickness required to just prevent yield is 6.2mm. Applying a safety factor of 2, the thickness of the fermenter needs to be 12.4mm. The CO2 stream will pass through a water trap so as no oxygen can enter into the fermenter.
Overall height (m)
Overall Diameter (m)
Mild steel (coated)
Wall thickness (mm)
Surface area (m2)
Maximum stress in shell (Mpa)
Number of cooling tubes
Length of cooling tubes (m)
Diameter of cooling tubes (inches)
This reactor has a cylindrical shape with a hemisphere head shape, it is vertical in orientation. The design specification for the reactor is given in the table below.
A centrifugal pump was used for this design; it had a size of 4" x 4" (102 mm x 102 mm) and a maximum operating pressure of 74 psi (510KPa). The impeller shaft is made of Carbon steel and other hardware elements of the pump are made of standard plate steel, the radial bearing is the open single row ball type while the thrust bearing is the open double row ball type. Driver powers for these pumps were calculated with 75% efficiency in ASPEN HYSYS. These values were used to calculate the cost of pumps including their motor drivers.
RADIUS OF GYRATION
FRICTION LOSS FACTOR
FIRST ORDER TIME CONSTANT
MOTOR FRICTION FACTOR
FULL LOAD POWER
FULL LOAD TORQUE
FULL LOAD SPEED
MAXIMUM PRESSURE DROP
MAXIMUM SPEED EXPONENT
The ultra-filter is made from high strength, hollow fiber membranes that offer the following features:
0.03 μm nominal pore diameter for removal of bacteria, viruses, and particulates including colloids
PVDF polymeric hollow fibers for high strength and chemical resistance
Hydrophilic PVDF fibers for easy cleaning and wettability that help maintain long term performance
Outside-In flow configuration for high tolerance to feed solids and the use of air scour cleaning
U-PVC housings eliminate the need for pressure vessels and are resistant to UV light
The outside-In flow configuration is tolerant of wide ranging feed water qualities and allows air scour cleaning. The dead-end flow offers higher recovery and energy savings. The pressurized vertical shell-and-tube design eliminates the need for separate pressure vessels and allows easy removal of air from cleaning and integrity testing steps.
The hollow fiber membranes are 1.3 mm outside diameter and 0.7 mm inside diameter and are made from PVDF polymer. The fibers are strong because of a combination of the PVDF polymer, asymmetric dense spongy layer, and skins formed on each side of the fiber. The PVDF membranes offer high chemical resistance and are tolerant to temperatures of 40ºC. The hydrophilicity of the PVDF fibers is increased by using a proprietary treatment during manufacturing.
The 0.03μm nominal pore size combines high filtration performance and high flux. The smaller pore size provides stabile long term filtration performance compared to microfiltation. There are four connections on each module. The flow enters the module through the side port located on the bottom end cap. Feed begins on the outside of the fiber. The air feed is located on the bottom of the end cap and is used for air scouring on the outside of the fiber during cleaning. The concentrate (discharges flow from the outside of fiber) and filtrate ports (inside of fiber) are located on the top cap.
The two pervaporators units are cuboidal in shape, vertical in orientation and have the same dimensions. There are certain characteristic values that a pervaporation module has that separate it from other pervaporation modules, they include: Area of Membrane, Separation Factor, Permeation Rate, Operational Temperature and Operational Pressure. The type of membrane used is hydrophilic membrane because water needs to be removed. A good hydrophilic to use for this procedure would be polyvinyl alcohol.
MAXIMUM ALLOWABLE TEMPERATURE
MAXIMUM ALLOWABLE PRESSURE
SEPARATION FACTOR (α)
EFFECTIVE MEMBRANE AREA
TOTAL NUMBER OF TUBES
The cooler will have Coil(s) consisting of fully welded boxheaders with serpentine coils and hot-dip galvanized after fabrication. Coils shall be tested to 400 psi air pressure while immersed in water. Maximum operating design pressure shall be 225 psi. The coil shall be designed for free drainages of fluid at shutdown. The fluid cooler and its components shall be designed to withstand a wind load of 20 psf and withstand shipping and hoisting loads of 2g horizontal or 3g vertical. Handrails, where specified shall be capable of withstanding a 200 lb concentrated live load in any direction.
MAXIMUM PRESSURE DROP
PIPE HEAT TRACE FLUID
POWER SUPPLY FREQUENCY
5.1 PROJECT SUMMARY
Analysis Date and Time
Fri Dec 05 08:23:52 2014
Aspen HYSYS Version 2006 (188.8.131.5228)
Simulator Report Date
Thursday, December 04, 2014
Economic Analysis Type
CAPITAL COST EVALUATION BASIS
Units of Measure
Currency (Cost) Symbol
Currency Conversion Rate
System Cost Base Date
Grass roots/Clear field
Delta State, Nigeria
100,000 metric tons/year
Time Difference Between System Cost Base Date and Start Date for Engineering
User Currency Name
User Currency Description
User Currency Symbol
Operating Hours per Period
Number of Weeks per Period
Number of Periods for Analysis
The cost estimation for this project was done using ASPEN Icarus cost evaluator. Tables showing equipment cost, utility cost, capital cost and other operation cost are shown below. As shown above, all costs are in US dollars. The equipment cost was estimated based on correlations found in the internet. All equipment costs were updated to December 2008, using Chemical Engineering Economic indicators. The original price estimation data of equipment is dated to 2002. It is considered that 1 $ USD = 0,633 €= 160NGN. Conversions could be generated in Nigerian Naira (NGN).
Total Electricity Cost
Total Potable Water Cost
Total Fuel Cost
Total Instrument Air Cost
OPERATING LABOR AND MAINTENANCE COSTS
Operators per Shift
Total Operating Labor Cost
Total Maintenance Cost
Supervisors per Shift
Total Supervision Cost
Total labor and maintenance Cost
EQUPMENT PURCHASE COST
EQUIPMENT OPERATING COST
PROJECT RESULTS SUMMARY
Total Operating Labor and Maintenance Cost
Total Utilities Cost
Total Equipment Purchase Cost
Total Equipment Operating Cost
Total Construction Cost
Total Project Cost for 1 year
5.2 INVESTMENT PARAMETERS
Investment parameters to evaluate the profitability of a project were specified by including a project life, salvage value, tax rate, depreciation method, desired rate of return, escalation rates, working capital percentage, operating cost parameters, and facility operation parameters.
A project life is defined as a specific length of time over which the profitability of different projects is to be compared (Turton, 2003). The lives typically used for this purpose are 10, 12 and 15 years (Turton, 2003). In this study, a ten-year analysis period was chosen. Accordingly, all the equipment in each process was assumed to equally have ten-year of useful lives for the sake of simplicity. Salvage value is an estimated value of fixed capital investment at the end of the project life. It was conservatively specified to be zero. As a depreciation method, a straight line method most commonly used was selected. The escalation rates for project capital, products, raw materials, operating and maintenance labour and utilities were set at the default values of IPE. Working capital, which indicates funds for the operating costs required for the early operation of the plant, was set at 15% of fixed capital cost.
Operating cost parameters include operating charges, costs for plant overhead and General and Administrative (G&A). Operating supplies and laboratory charges cover the cost of the miscellaneous items required in order to run the plant and the cost of analyzing products.
5.3 PROJECT EVALUATION
Project costing and evaluation were done using Aspen Icarus Project Evaluator.
In the process of making an investment decision, the profit anticipated from an investment must be judged relative to some profitability standards. A profitability standard is a quantitative measure of profit with respect to the capital investment required to generate that profit. Several methods are used for project evaluation, and the methods can be divided into discounted techniques and non-discounted techniques. Non-discounted cash flow techniques do not consider the time value of money and therefore are not suitable for final project evaluation. The methods include payback period and return on investment. Discounted cash flow techniques are more rigorous profitability measures which involve consideration of the time value of money and estimates of the cash flows throughout the life of the process. The methods include the discounted payback period (DPP), net present value (NPV), equivalent annual value (EAV) and discounted cash flow rate of return (DCFROR).
Discounted payback period is the time required, after start-up, to recover the fixed capital investment as all cash flows discounted back to time zero. It corresponds to the time when the cumulative present value crosses over from negative to positive hitting zero. The project with the shortest time is the more favourable. However, it may lead to an economically incorrect decision, as it does not reflect cash flows after payback. The project with the shortest DPP might not produce the highest return at the end of the project life. Therefore, it should be only used to provide initial screening or supplemental information in conjunction with an analysis performed using different methods. Net present value is defined as the sum of all cash inflows and outflows as they are discounted to the present worth by the given interest rate. A positive NPV indicates that a project is acceptable and the higher the NPV, the better the potential project. To calculate NPV, an appropriate interest rate (or discount rate) needs to be defined first. This internal interest rate usually represents the minimum acceptable rate of return (MARR) that must be earned for a project to be accepted. It is normally adjusted to account for the uncertainties and risks associated with the project.
Discounted cash flow rate of return also known as internal rate of return (IRR) is defined as the interest rate at which all the cash flows are discounted in order to bring the net present value to exactly zero. It represents the highest after-tax interest at which the project can just break even (Turton 2003). If the IRR is greater than the internal interest rate, the project is regarded to be profitable. Among the various ways to measure profitability, DPP, NPV and DCFROR were the interests of this study. The break-even price was defined as the price at which the revenue from selling biodiesel product is the same as total manufacturing cost of each process (Zhang et al., 2003).
TW (Number of Weeks per Period)
T (Number of Periods for Analysis)
DTEPC (Duration of EPC Phase)
DT (Duration of EPC Phase and Startup)
WORKP (Working Capital Percentage)
OPCHG (Operating Charges)
PLANTOVH (Plant Overhead)
CAPT (Total Project Cost)
RAWT (Total Raw Material Cost)
PRODT (Total Product Sales)
OPMT (Total Operating Labor and Maintenance Cost)
UTILT (Total Utilities Cost)
ROR (Desired Rate of Return/Interest Rate)
AF (ROR Annuity Factor)
TAXR (Tax Rate)
IF (ROR Interest Factor)
ECONLIFE (Economic Life of Project)
SALVAL (Salvage Value (Percent of Initial Capital Cost))
DEPMETH (Depreciation Method)
DEPMETHN (Depreciation Method Id)
ESCAP (Project Capital Escalation)
ESPROD (Products Escalation)
ESRAW (Raw Material Escalation)
ESLAB (Operating and Maintenance Labor Escalation)
ESUT (Utilities Escalation)
START (Start Period for Plant Startup)
PODE (Desired Payout Period (excluding EPC and Startup Phases))
POD (Desired Payout Period)
DESRET (Desired Return on Project for Sales Forecasting)
END (End Period for Economic Life of Project)
GA (G and A Expenses)
DTEP (Duration of EP Phase before Start of Construction)
OP (Total Operating Labor Cost)
MT (Total Maintenance Cost)
CASHFLOW CALCULATIONS FOR THE FIRST FIVE YEARS
DEP (Depreciation Expense)
E (Earnings Before Taxes)
NE (Net Earnings)
TEX (Total Expenses (Excludes Taxes and Depreciation))
CF(Cash Flow for Project)
PVO (Present Value of Cumulative Cash Outflows)
PV (Present Value of Cash Flows)
NPV (Net Present Value)
IRR (Internal Rate of Return)
MIRR (Modified Internal Rate of Return)
NRR (Net Return Rate)
PO (Payout Period)
ARR (Accounting Rate of Return)
CASHFLOW CALCULATIONS FOR THE LAST 5 YEARS
DEP (Depreciation Expense)
E (Earnings Before Taxes)
NE (Net Earnings)
TEX (Total Expenses (Excludes Taxes and Depreciation))
CF(Cash Flow for Project)
PVO (Present Value of Cumulative Cash Outflows)
PV (Present Value of Cash Flows)
NPV (Net Present Value)
IRR (Internal Rate of Return)
MIRR (Modified Internal Rate of Return)
NRR (Net Return Rate)
PO (Payout Period)
ARR (Accounting Rate of Return)
The straight line depreciation value for this project was evaluated using Icarus project evaluator which gave a value of 77103.8 dollars every year for the period of ten years.
RATE OF RETURN AND PAYBACK PERIOD
ROR = Cummulative net cash flow at project end ×100%Project life ×Original Investment
PAYBACK TIME = Reciprocal of ROR (when annual savings is constant)
SAFETY CONSIDERATION AND PLANT LOCATION
Every organisation has a legal and moral obligation to safeguard the health and welfare of its employees and the general public. Safety is also good business; the good management practices needed to ensure safe operation will also ensure efficient operation. All manufacturing processes are to some extent hazardous, but in chemical processes there are additional, special, hazards associated with the chemicals used and the process conditions. The designer must be aware of these hazards, and ensure, through the application of sound engineering practice, that the risks are reduced to acceptable levels.
Safety in process design can be considered under the following broad headings:
1. Identification and assessment of the hazards.
2. Control of the hazards: for example, by containment of flammable and toxic materials.
3. Control of the process, Prevention of hazardous deviations in process variables (pressure, temperature, flow), by provision of automatic control systems, interlocks, alarms, trips; together with good operating practices and management.
4. Limitation of the loss. The damage and injury caused if an incident occurs: pressure relief, plant layout, provision of fire-fighting equipment.
SAFETY DATA SHEET FOR FUEL ETHANOL
ITEC MSDS 004, ITECSOL AC500, ITECSOL AC600, Anhydrous Ethanol, Fuel Ethanol, Ethanol for Fuel Blending, Ethanol for Gasoline, Ethanol, Denatured Ethyl Alcohol, Denatured, 200 Proof Fuel Ethanol
Can cause kidney, liver and blood disorders, May cause irritation to eyes, skin and respiratory system. Avoid liquid, mist and vapor contact. Harmful or fatal if swallowed.
Aspiration hazard; can enter lungs and cause damage. May cause irritation or be harmful if inhaled or absorbed through the skin. Extremely flammable liquid, vapors may explode.
Physical state: Liquid.
Emergency Overview: Danger! flammable liquid and vapor. Contains material that can cause target organ damage. Possible cancer hazard - contains material which may cause cancer, based on animal data.
Do not ingest. Avoid prolonged contact with eyes, skin and clothing. Keep away from heat, sparks and flame. Keep container closed. Use only with adequate ventilation. Wash thoroughly after handling. Risk of cancer depends on duration and level of exposure.
Routes of entry: Dermal contact, Eye contact, Inhalation, Ingestion.
Potential acute health effects:
Eyes: May cause severe irritation, redness, tearing, blurred vision and conjunctivitis.
Skin: Prolonged or repeated contact may cause moderate irritation, defatting (cracking), redness, itching, inflammation, dermatitis and possible secondary infection. High pressure skin injections are SERIOUS MEDICAL EMERGENCIES. Injury may not appear serious at first. Within a few hours, tissues will become swollen, discolored and extremely painful.
Inhalation: Nasal and respiratory tract irritation, central nervous system effects including excitation, euphoria, contracted eye pupils, dizziness, drowsiness, blurred vision, fatigue, nausea, headache, loss of reflexes, tremors, convulsions, seizures, loss of consciousness, coma, respiratory arrest and sudden death could occur as a result of long term and/or high concentration exposure to vapors, May also cause anemia and irregular heart rhythm. Repeated or prolonged exposure may cause behavioral changes.
Ingestion: Toxic if swallowed. This product may be harmful or fatal if swallowed. This product may cause nausea, vomiting, diarrhea and restlessness. DO NOT INDUCE VOMITING. Aspiration into the lungs can cause severe chemical pneumonitis or pulmonary edema/hemorrhage, which can be fatal, may cause gastrointestinal disturbances, symptoms may include irritation, depression, vomiting and diarrhea, may cause harmful central nervous system effects, similar to those listed under "inhalation".
Over-exposure signs/symptoms: Nasal and respiratory tract irritation, central nervous system effects including excitation, euphoria, contracted eye pupils, dizziness, drowsiness, blurred vision, fatigue, nausea, headache, loss of reflexes, tremors, convulsions, seizures, loss of consciousness, coma, respiratory arrest or sudden death could occur as a result of long term and/or high concentration exposure to vapors, may also cause anemia and irregular heart rhythm.
FIRST AID MEASURES
Eye contact: Flush immediately with large amounts of water for at least 15 minutes. Eyelids should be held away from the eyeball to ensure thorough rinsing. Seek medical advice if pain or redness continues.
Skin contact: Remove contaminated clothing and shoes. Wash exposed area thoroughly with soap and water. Remove contaminated clothing promptly and launder before reuse. Contaminated leather goods should be discarded. If irritation persists or symptoms described in the MSDS develop, seek medical attention. High pressure skin injections are SERIOUS MEDICAL EMERGENCIES. Get immediate medical attention.
Inhalation: If inhaled, remove to fresh air. If breathing is difficult, give oxygen. If not breathing, give artificial respiration. Get medical attention.
Notes to physician: No specific treatment. Treat symptomatically, Contact poison treatment specialist immediately if large quantities have been ingested or inhaled.
Protection of first-aiders: No action shall be taken involving any personal risk or without suitable training. If it is suspected that fumes are still present, the rescuer should wear an appropriate mask or self-contained breathing apparatus. It may be dangerous to the person providing aid to give mouth-to-mouth resuscitation. Wash contaminated clothing thoroughly with water before removing it, or wear gloves.
FIRE FIGHTING MEASURES
Flammability of the product: Flammable.
Products of combustion: These products are carbon oxides (CO, CO2), nitrogen and sulfur oxides (NOX, SOX), particulate matter, VOC's.
Fire hazards in the Presence of various substances: Extremely flammable in the presence of the following materials or conditions: open flames, sparks and static discharge.
Explosion hazards in the presence of various substances: Explosive in the presence of the following materials or conditions: open flames, sparks and static discharge.
Fire-fighting media and instructions
Suitable: Use dry chemical, CO2, water spray (fog) or foam.
Not suitable: Do not use water jet.
Collect contaminated fire-fighting water separately. It must not enter the sewage system, dike area of fire to prevent runoff. Decontaminate emergency personnel and equipment with soap and water. Vapor may cause flash fire. Vapors may accumulate in low or confined areas or travel a considerable distance to a source of ignition and flash back. Runoff to sewer may create fire or explosion hazard.
Special protective equipment for firefighters: Fire-fighters should wear appropriate protective equipment and self-contained breathing apparatus (SCBA) with a full face-piece operated in positive pressure mode.
Special remarks on Fire hazards: Dangerous when exposed to heat or flame. Vapors form flammable or explosive mixtures with air at room temperature. Vapor or gas may spread to distant ignition sources (pilot lights, welding equipment, electrical equipment, etc.) and flash back. Vapors may accumulate in low areas. Vapors may concentrate in confined areas. Flowing product can be ignited by self-generated static electricity. Use adequate bonding and grounding to prevent static buildup. Runoff to sewer may cause fire or explosion hazard. Containers may explode in heat of fire. Irritating or toxic substances may be emitted upon thermal decomposition. For fires involving this material, do not enter any enclosed or confined space without proper protective equipment, which may include approved self-contained breathing apparatus with full face mask. Clothing, rags or similar organic material contaminated with this product and stored in a closed space may undergo spontaneous combustion.
ACCIDENTAL RELEASE MEASURES
Personal precautions: Immediately contact emergency personnel. Eliminate all ignition sources. Keep unnecessary personnel away. Use suitable protective equipment .Do not touch or walk through spilled material. Tanks, vessels or other confined spaces which have contained product should be freed of vapors before entering. The container should be checked to ensure a safe atmosphere before entry. Empty containers may contain toxic, flammable/combustible or explosive residues or vapors. Do not cut, grind, drill, weld or reuse empty containers that contained this product. Do not transfer this product to another container unless the container receiving the product is labeled with proper DOT shipping name, hazard class and other information that describes the product and its hazards.
Environmental precautions: Avoid dispersal of spilled material and runoff and contact with soil, waterways, drains and sewers. Gasoline may contain oxygenated blend products (Ethanol, MTBE, etc.) that are soluble in water and therefore precautions should be taken to protect surface and groundwater sources from contamination. If facility or operation has an "oil or hazardous substance contingency plan", activate its procedures. Stay upwind and away from spill, wear appropriate protective equipment including respiratory protection as conditions warrant. Do not enter or stay in area unless monitoring indicates that it is safe to do so. Isolate hazard area and restrict entry to emergency crew. Review Fire Fighting Measures section before proceeding with clean up. Keep all sources of ignition (flames, smoking, flares, etc.) and hot surfaces away from release. Contain spill in smallest possible area. Recover as much product as possible (e.g., by vacuuming). Stop leak if it can be done without risk. Use water spray to disperse vapors. Spilled material may be absorbed by an appropriate absorbent, and then handled in accordance with environmental regulations. Prevent spilled material from entering sewers, storm drains, other unauthorized treatment or drainage systems and natural waterways. Contact fire authorities and appropriate federal, state and local agencies.
Methods for cleaning
Small spill: Stop leak if without risk. Move containers from spill area. Dilute with water and mop up if water-soluble or absorb with an inert dry material and place in an appropriate waste disposal container. Use spark-proof tools and explosion-proof equipment. Dispose of via a licensed waste disposal contractor.
Large spill: If emergency personnel are unavailable, contain spilled material. For small spills, add absorbent (soil may be used in the absence of other suitable materials) and use a non-sparking or explosion-proof means to transfer material to a sealable, appropriate container for disposal. For large spills, dike spilled materials or otherwise contain it to ensure runoff does not reach a waterway. Place spilled material in an appropriate container for disposal.
HANDLING AND STORAGE
Handling: Do not ingest. Avoid prolonged contact with eyes, skin and clothing. Keep container closed. Use only with adequate ventilation. Keep away from heat, sparks and flame. To avoid fire or explosion, dissipate static electricity during transfer by grounding and bonding containers and equipment before transferring material.
Use explosion-proof electrical (ventilating, lighting and material handling) equipment. Wash thoroughly after handling. Use only in well ventilated locations.
Keep away from heat, spark and flames. In case of fire, use water spray, foam, dry chemical or carbon dioxide as described in the Fire Fighting Measures section of this Safety Datasheet. Do not pressurize, cut, weld, braze, solder, drill on or near this container. "Empty" container contains residue (liquid and/or vapor) and may explode in heat of a fire. Use good personal hygiene practices. After handling this product, wash hands before eating, drinking, or using toilet facilities.
Keep out of reach of children. Failure to use caution may cause serious injury or illness. Never siphon by mouth. For use as a motor fuel only, do not use as a cleaning solvent or for other non-motor fuel uses. To prevent ingestion and exposure - Do not siphon by mouth to transfer product between containers. Use good personal hygiene practices. After handling this product, wash hands before eating, drinking, or using toilet facilities.
Storage: Store in tightly closed containers in cool, dry, isolated and well-ventilated area away from heat, sources of ignition and incompatible materials. Use non-sparking tools and explosion proof equipment. Ground lines, containers, and other equipment used during product transfer to reduce the possibility of a static induced spark. Do not "switch load" because of possible accumulation of a static charge resulting in a source of ignition. Use good personal hygiene practices.
EXPOSURE CONTROL, PERSONNEL PROTECTION
Engineering measures: Use only with adequate ventilation. Use process enclosures, local exhaust ventilation or other engineering controls to keep worker exposure to airborne contaminants below any recommended or statutory limits. The engineering controls also need to keep gas, vapor or dust concentrations below any lower explosive limits. Use explosion-proof ventilation equipment.
Eyes: Safety eyewear complying with an approved standard should be used when a risk assessment indicates this is necessary to avoid exposure to liquid splashes, mists or dusts. Keep away from eyes. Eye contact can be avoided by wearing safety glasses or chemical splash goggles.
Skin: Personal protective equipment for the body should be selected based on the task being performed and the risks involved and should be approved by a specialist before handling this product. Keep away from skin. Skin contact can be minimized by wearing protective gloves such as neoprene, nitrile-butadiene rubber, etc. and, where necessary, impervious clothing and boots. Leather goods contaminated with this product should be discarded. A source of clean water should be available in the work area for flushing eyes and skin. Flame Retardant Clothing is recommended.
Respiratory: Use a properly fitted, air-purifying or air-fed respirator complying with an Approved standard if a risk assessment indicates this is necessary. Respirator selection must be based on known or anticipated exposure levels, the hazards of the product and the safe working limits of the selected respirator. If workplace exposure limits for product or components are exceeded, NIOSH approved equipment should be worn. Proper respirator selection should be determined by adequately trained personnel, based on the contaminants, the degree of potential exposure and published respiratory protection factors. This equipment should be available for non-routine and emergency use.
Hands: Chemical-resistant, impervious gloves complying with an approved standard should be worn at all times when handling chemical products if a risk assessment indicates this is necessary.
Equipment: Consult your Supervisor or S.O.P. for special handling directions.
Personal protection in Case of a large spill: Splash goggles, Full suit, Vapor respirator, Boots, Gloves. Self-contained breathing apparatus (SCBA) should be used to avoid inhalation of the product. Suggested protective clothing might not be adequate. Consult a specialist before handling this product.
Recommended Monitoring Procedures: If this product contains ingredients with exposure limits, personal, workplace atmosphere or biological monitoring may be required to determine the effectiveness of the ventilation or other control measures and/or the necessity to use respiratory protective equipment.
Hygiene measures: Wash hands, forearms and face thoroughly after handling chemical products, before eating, smoking and using the lavatory and at the end of the working period. Appropriate techniques should be used to remove potentially contaminated clothing. Wash contaminated clothing before reusing. Ensure that eyewash stations and safety showers are close to the workstation location.
Environmental Exposure Controls: Emissions from ventilation or work process equipment should be checked to ensure they comply with the requirements of environmental protection legislation. In some cases, fume scrubbers, filters or engineering modifications to the process equipment will be necessary to reduce emissions to acceptable levels.
PHYSICAL AND CHEMICAL PROPERTIES
Alcohol-like, Characteristic Gasoline Odor
73.89 to 79.45°C (165 to 175°F)
1.6 [Air = 1]
1.7 (Butyl acetate = 1)
Soluble in the cold water and hot water
STABILITY AND REACTIVITY DATA
Stability: The product is stable.
Hazardous Polymerization: Under normal conditions of storage and use, hazardous polymerization will not occur.
Conditions to avoid: Avoid all possible sources of ignition (spark or flame). Do not pressurize, cut, weld, braze, solder, drill, grind or expose containers to heat or sources of ignition. Do not allow vapor to accumulate in low or confined areas. Avoid exposure - obtain special instructions before use.
Materials to avoid: Highly reactive or incompatible with the following materials: oxidizing materials
Hazardous decomposition products: Under normal conditions of storage and use, hazardous decomposition products should not be produced.
Conditions of reactivity: Extremely flammable in the presence of the following materials or conditions: open flames, sparks and static discharge. Explosive in the presence of the following materials or conditions: open flames, sparks and static discharge
Waste disposal: The generation of waste should be avoided or minimized wherever possible. Empty containers or liners may retain some product residues. This material and its container must be disposed of in a safe way. Dispose of surplus and non-recyclable products via a licensed waste disposal contractor. Disposal of this product, solutions and any byproducts should at all times comply with the requirements of environmental protection and waste disposal legislation and any regional local authority requirements. Avoid dispersal of spilled material and runoff and contact with soil, waterways, drains and sewers. Consult your local or regional authorities.
DOT Shipping Description
Ethanol, 3, UN1170, II
Non-bulk Package Marking
Ethanol, 3, UN1170
Non-Bulk Package Label
Bulk Package Placard/Marking
49 CFR 173, 150, 173.202, 173.242
Emergency Response Guide
SAFETY CHECK LISTS
Check lists are useful aids to memory. A check list that has been drawn up by experienced engineers can be a useful guide for the less experienced. However, too great a reliance should never be put on the use of check lists, to the exclusion of all other considerations and techniques. It should be noted that no check list can be completely comprehensive, covering all the factors to be considered for any particular process or operation. A short safety check list, covering the main items which were considered in this design is given below.
Flash-point, flammability range, auto-ignition temperature, composition, stability (shock sensitive?), toxicity, corrosion, physical properties (unusual?), heat of combustion/reaction
Reactors: Exothermic heat of reaction, temperature control, emergency systems, side reactions (dangerous?), effect of contamination, effect of unusual concentrations (including catalyst) corrosion
Is there a need for pressure systems?, Is design in compliance with current codes (BS 5500), Is materials of construction adequate?, pressure relief adequate?, safe venting systems, flame arresters
fail safe, back-up power supplies, high/low alarms and trips on critical variables, temperature, pressure, flow, level, composition, back-up/duplicate systems on critical variables, remote operation of valves, block valves on critical lines, excess-flow valves, interlock systems to prevent mis-operation, automatic shut-down systems
Floating roof tanks, dykeing, loading/unloading facilities safety, earthing and ignition sources vehicles
Inert purging systems needed, compliance with electrical codes, adequate lighting, lightning protection, sewers and drains adequate, dust-explosion hazards, build-up of dangerous impurities purges, plant layout, siting of control rooms and offices, services safety showers, eye baths
Emergency water supplies, fire mains and hydrants, foam systems, sprinklers and deluge systems, insulation and protection of structures, access to buildings, fire-fighting equipment.
The location of the plant can have a crucial effect on the profitability of a project, and the scope for future expansion.
The principal factors considered are:
Location, with respect to the marketing area.
Raw material supply: The availability and price of suitable raw materials will often determine the site location. Plants producing bulk chemicals are best located close to the source of the major raw material; where this is also close to the marketing area.
Transport facilities: If practicable, a site should be selected that is close to at least two major forms of transport: road, rail, waterway (canal or river), or a sea port. Road transport is being increasingly used, and is suitable for local distribution from a central warehouse. Rail transport will be cheaper for the long-distance transport of bulk chemicals.
Availability of labour/Qualification
Availability of utilities: water, fuel, power.
Availability of and cost of suitable land.
Environmental impact and effluent disposal.
Local community considerations/ Unemployment rate
Climate: Adverse climatic conditions at site will increase costs. Abnormally low temperatures will require the provision of additional insulation and special heating for equipment and piping. Stronger locations will be needed at locations subject to high wind loads or earthquakes.
Political strategic considerations: Capital grants, tax concessions, and other inducements are often given by governments to direct new investment to preferred locations; such as areas of high unemployment. The availability of such grants can be the overriding consideration in site selection.
Using the above criteria, and considering that the plant should be located close to a refinery for easy supply, each factor was allocated a score on the basis of 1 to 5 with 1 as the worse and 5 as best, the location with the highest point was chosen. Warri in delta state was selected as the best location.
Cost of land
Nearness to market
The economic construction and efficient operation of a process unit will depend on how well the plant and equipment specified on the process flow sheet is laid out, this in turn determines the safety of workers in the area. The principal factors considered are:
Economic considerations: construction and operating costs.
The process requirements.
Convenience of operation.
Convenience of maintenance.
The cost of construction can be minimized by adopting a layout that gives the shortest run of connecting pipe between equipment, and at least amount of structural steel work. However, this will not necessarily be the best arrangement for operation and maintenance.
An example of the need to take into account process consideration is the need to elevate the base of columns to provide the necessary net positive suction head to a pump or the operating head for a thermosyphon reboiler.
Equipment that needs to have frequent attention should be located convenient to the control room. Valves, sample points, and instruments should be located at convenient positions and heights. Sufficient working space and headroom must be provided to allow easy access to equipment.
Heat exchangers need to be sited so that the tube bundles can be easily withdrawn for cleaning and tube replacement. Vessels that require frequent replacement of catalyst or packing should be located on the outside of buildings. Equipment that requires dismantling for maintenance, such as compressors and large pumps, should be places under cover.
Blast walls may be needed to isolate potentially hazardous equipment, and confine the effects of an explosion. At least two escape routes for operators must be provided from each level in process buildings.
Equipment should be located so that it can be conveniently tied in with any future expansion of the process. Space should be left on pipe alleys for future needs, and service pipes over-sized to allow for future requirements.
In recent years there has been a move to assemble sections of plant at the plant manufacturer's site. These modules will include the equipment, structural steel, piping and instrumentation. The modules are then transported to the plant site, by road or sea. The advantages of modular construction are:
Improved quality control.
Reduced construction cost.
Less need for skilled labor on site.
Some of the disadvantages are;
Higher design costs & more structural steel work.
CONCLUSIONS AND RECOMMENDATION
The report has successfully outlined a proposal for motor-grade ethanol production plant with a capacity of 100,000 metric tonnes/year of ethanol at a purity of 98.75%, using corn as the feedstock.
A potential location for the plant is Auchi; primarily due to its location near where the main feedstock (corn) for the process is readily available. It also has also been known to experience a relatively high level of peace compared to other Niger Delta regions where youth restiveness and sabotage of government efforts at setting up similar plants have been rampant.
Such a project can bring many benefits to the local area including employment and training opportunities as well as a boost to the local economy. However it is important that support is generated and key allies made such as the fuel retailers and more importantly the local residents.
From this work, it is recommended that gasoline should be replaced with fuel ethanol where possible or in case where total replacement is not possible, blending of ethanol with gasoline should be done. The fuel produced by the plant will have a positive effect on climate change. The energy released from burning the fuel is significantly less than that required to produce it. Its use will also result in an estimated 70% reduction in carbon dioxide emissions over the petrol it will replace. Ethanol fuel blends will help improve air quality by reducing the emissions of components of smog and harmful additives.
An economic analysis has shown this product to be viable under a number of market conditions; high and low government tax, oil prices and feedstock costs. The product will yield large profits with the current government subsidy on bioethanol fuel tax, and a cash-flow analysis shows that the payback period would be 5 years from project initiation under these conditions.
Considering its benefits, this plant is an environmentally and economically viable means for producing fuel ethanol for the Nigerian market. Further development of this proposal would require more accurate costing of the 'Main Plant Items', using up to date quotes. It would also be necessary to construct a fully integrated flowsheet using a commercial software package and carry out a detailed analysis of resource use, with a view to maximising resource efficiency.
It has been proposed that a full stakeholder analysis is undertaken to highlight those affected by the project.
Lastly, due to inefficiency of equipments, it is observed from the material balance that the output/sec i.e 3.21kg ethanol / sec if multiplied by 29,959,200 secs which is the plant's uptime expressed in seconds does not yield 100,000,000kg ethanol which is the annual output, rather it gives : 96,169,032kg ethanol / annum which is 3,830,968kg/annum short of the expected production capacity. To remedy this deficit, the plant's operating hours per year should be extended from the initially assumed 95% to 98% since the production of ethanol from corn is not a novel process, this is clearly within safe engineering practice for this plant. This will increase the production capacity to 99,205,948.8kg/annum = 99,205.9488 metric tonnes /annum.
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