Re-refining of used Lube oils A Seminar Report
Submitted byMr. Shyambahadur Yadav, B.E. (Chem.) In partial fulfillment for the award of the degree Of BACHELOR OF ENGINEERING IN CHEMICAL ENGINEERING Under the guidance of Prof. Ananya Dey
DEPARTMENT OF CHEMICAL ENGINEERING SHIVAJIRAO.S.JONDHALE COLLEGE OF ENGINEERING, DOMBIVLI (EAST) – 421203 421203 UNIVERSITY OF MUMBAI 2012-2013
SHIVAJIRAO.S.JONDHALE COLLEGE OF ENGINEERING, DEPARTMENT OF CHEMICAL ENGINEERING DOMBIVLI (EAST) – 421203 421203
CERTIFICATE
This is to certify that the Seminar report entitled ― Re-refining of used Lube oils”
carried out by Mr.Shyambahadur Yadav of B.E. Chemical Engineering, during the
academic year 2012 – 2012 – 2013, 2013, is a bonafide work submitted to the Department of Chemical Engineering of Shri. Shivajirao.S.Jondhale College of Engineering.
Seminar Guide
Internal Examiner
Head of Department Chemical Engg. Dept.
External Examiner
Dr. J. W. Bakal Principal
INDEX
CHAPTER
1
CONTENT
INTRODUCTION
2
HISTORY
3
LITERATURE REVIEW 3.1 PROPERTIES 3.2 TYPES 3.3 ADDITIVES 3.4 CONTAMINANTS IN USED LUBE OIL 3.5 ENVIRONMENTAL IMPACT 3.6 VACUUM DISTILLATION PROCESS OF REFINING 3.7 ADVANTAGE OF RE-REFINING 3.8 APPLICATION
4
CONCLUSION
REFERENCES
CHAPTER 1 INTRODUCTION
Lubricating oil is the type of petroleum product which is employed to reduce wear of
one or both surfaces in close proximity, and moving relative to each another in an engine or machine. It is also called as engine oil. Its viscosity is comparatively higher than the other petroleum products. It is manufactured by refining the petroleum by atmospheric or vacuum distillation process. Typically lubricants contain 90% base oil (most often petroleum fractions, called minerals oil) and less than 10% additives. If one thinks of lubricants today, the first type to come to mind are mineral oilbased. Mineral oil components continue to form the quantitatively most important foundation of lubricants. Petrochemical components and increasingly derivatives of natural, harvestable raw materials from the oleo-chemical industry are finding increasing acceptance because of their environmental compatibility and some technical advantages. On average, lubricating oils, which quantitatively account for about 90% of lubricant consumption, consist of about 93% base oils and 7% chemical additives and other components (between 0.5 and 40 %). The development of lubricants is closely linked to the specific applications and application methods. As a simple description of materials in this field makes little sense, the following sections will consider both lubricants and their application.
CHAPTER 2 HISTORY The oil re-refining industry has existed for many years and has evolved over time, being subject to pressures from both industry and society. In the early years, used oil was sometimes filtered and re-used, but most often it was dumped on the ground and in water, and occasionally burned as a fuel. Over time, efforts were made to recover spent oil, and by the mid-1960’s, there were more than 100 small companies reprocessing over one hundred million gallons of used oil annually in the United States. These companies generally employed the ―acid/clay‖ re-refining process, wherein a large amount of sulfuric acid and clay was used to treat the used oil. Although the technology produced an acceptable, but sub-standard base oil, it also created substantial hazardous waste by products, including acid-tar and oil saturated clay.
Many of these original acid/clay
facilities became ―super -fund‖ clean-up sites. Starting in the 1970s, the use of acid clay re-refining was discouraged by environmental regulators and is currently outlawed in most countries around the world. In the late 1970’s, alternative processes were developed to treat the used oil in a more environmentally friendly manner. By and large these efforts were spearheaded by used oil gatherers who needed a means of ―disposing‖ of the oil they gathered. Their primary revenue stream was generated through the charges levied in collecting the oil. Once collected, they needed an economic means of turning it into an environmentally acceptable, salable product. Their focus was not on creating high quality products but rather in treating a waste stream to market it for higher value. The first of the ―next-generation‖ technologies was the Phillips Re-Refined Oil Process (PROP). This technology was developed during the energy crunch of the 1970s as a potential solution for recovering the base oil from used oil. This technology involved ―demetalizing‖ the oil (effectively removing the metals) with diammonium phosphate, which created a metal phosphate precipitate. The oil was then filtered, distilled and hydrotreated. The PROP technology was successful in producing low quality base oils;
however, there were several environmental concerns that arose due to the need to dispose of large quantities of oil soaked, heavy metal laden, precipitate and filter media. One of the purchasers of the technology was Mohawk Oil in Canada. Once Mohawk understood the shortcomings of the PROP technology, they decided to modify it (by removing the de-metallization section and adding a wiped film evaporator and a different chemical treatment regimen), thereby creating a novel process. Mohawk’s innovations where further adapted by Evergreen Oil (California) and Safety-Kleen Systems Inc.. (Illinois) in the United States and formed the basis for the technology that is currently being used by these companies. Although there are many types of lube oils to choose from, mineral oils are the most commonly used because the supply of crude oil has rendered them inexpensive; moreover, a large body of data on their properties and use already exists. Another advantage of mineral-based lube oils is that they can be produced in a wide range of viscosities — viscosity refers to the substance's resistance to flow — for diverse applications. They range from low-viscosity oils, which consist of hydrogen-carbon chains with molecular weights of around 200 atomic mass units (amu), to highly viscous lubricants with molecular weights as high as 1000 amu. Mineral-based oils with different viscosities can even be blended together to improve their performance in a given application. The common 1OW-30 motor oil, for example, is a blend of low viscous oil (for easy starting at low temperatures) and highly viscous oil (for better motor protection at normal running temperatures). First used in the aerospace industry, synthetic lubricants are usually formulated for a specific application to which mineral oils are ill-suited. For example, synthetics are used where extremely high operating temperatures are encountered or where the lube oil must be fire resist. Waste / Used oil is generally referred to Petroleum oil, which has lost its required properties and therefore cannot be used as such for any application in its present form. Every year large quantities of waste s, Fuel and metallic particles that create the need for oil replacement. It is also very hazardous for environme nt.
CHAPTER 3 3.1 PROPERTIES OF LUBRICATING OIL Lubricating oils are fluids such as engine oils, gear, hydraulic oils, turbine oils, etc. The properties of lubricating oil are, keeping moving parts apart, reduce friction, transfer heat carry away contaminants & debris, transmit power, protect against wear, prevent corrosion, seal for gases, stop the risk of smoke and fire of objects, prevent rust. Keep moving parts apart
Lubricants are typically used to separate moving parts in a system. This has the benefit of reducing friction and surface fatigue, together with reduced heat generation, operating noise and vibrations. Lubricants achieve this by several ways. The most common is by forming a physical barrier i.e., a thin layer of lubricant separates the moving parts. This is analogous to hydroplaning; the loss of friction observed when a car tire is separated from the road surface by moving through standing water. This is termed hydrodynamic lubrication. In cases of high surface pressures or temperatures, the fluid film is much thinner and some of the forces are transmitted between the surfaces through the lubricant. Reduce friction
Typically the lubricant-to-surface friction is much less than surface-to-surface friction in a system without any lubrication. Thus use of a lubricant reduces the overall system friction. Reduced friction has the benefit of reducing heat generation and reduced formation of wear particles as well as improved efficiency. Lubricants may contain additives known as friction modifiers that chemically bind to metal surfaces to reduce surface friction even when there is insufficient bulk lubricant present for hydrodynamic lubrication, e.g. protecting the valve train in a car engine at startup. Transfer heat
Both gas and liquid lubricants can transfer heat. However, liquid lubricants are much more effective on account of their high specific heat capacity. Typically the liquid
lubricant is constantly circulated to and from a cooler part of the system, although lubricants may be used to warm as well as to cool when a regulated temperature is required. This circulating flow also determines the amount of heat that is carried away in any given unit of time. High flow systems can carry away a lot of heat and have the additional benefit of reducing the thermal stress on the lubricant. Thus lower cost liquid lubricants may be used. The primary drawback is that high flows typically require larger sumps and bigger cooling units. A secondary drawback is that a high flow system that relies on the flow rate to protect the lubricant from thermal stress is susceptible to catastrophic failure during sudden system shut downs. An automotive oil-cooled turbocharger is a typical example. Turbochargers get red hot during operation and the oil that is cooling them only survives as its residence time in the system is very short i.e. high flow rate. If the system is shut down suddenly (pulling into a service area after a high speed drive and stopping the engine) the oil that is in the turbo charger immediately oxidizes and will clog the oil ways with deposits. Over time these deposits can completely block the oil ways, reducing the cooling with the result that the turbo charger experiences total failure typically with seized bearing. Non-flowing lubricants such as greases & pastes are not effective at heat transfer although they do contribute by reducing the generation of heat in the first place. Carry away contamination
Lubricant circulation systems have the benefit of carrying away internally generated debris and external contaminants that get introduced into the system to a filter where they can be removed. Lubricants for machines that regularly generate debris or contaminants such as automotive engines typically contain detergent and dispersant additives to assist in debris and contaminant transport to the filter and removal. Over time the filter will get clogged and require cleaning or replacement, hence the recommendation to change a car's oil filter at the same time as changing the oil. In closed systems such as gear boxes the filter may be supplemented by a magnet to attract any iron fines that get created. It is apparent that in a circulatory system the oil will only be as clean as the filter can make it, thus it is unfortunate that there are no industry standards by which consumers
can readily assess the filtering ability of various automotive filters. Poor filtration significantly reduces the life of the machine (engine) as well as making the system inefficient. Transmit heat
Lubricants known as hydraulic fluid are used as the working fluid in hydrostatic power transmission. Hydraulic fluids comprise a large portion of all lubricants produced in the world. The automatic transmission's torque converter is another important application for power transmission with lubricants. Protect against wear
Lubricants prevent wear by keeping the moving parts apart. Lubricants may also contain anti-wear or extreme pressure additives to boost their performance against wear and fatigue. Prevent corrosion
Good quality lubricants are typically formulated with additives that form chemical bonds with surfaces, or exclude moisture, to prevent corrosion and rust. Seal for gases
Lubricants will occupy the clearance between moving parts through the capillary force, thus sealing the clearance. This effect can be used to seal pistons and shafts
Some other properties of lubricating oil are given below:
UNIT
VISCOSITY (CST)
ENGINE
40
FLASH
FIRE
POUR
VISCOSITY
DENSITY
POINT
POINT
POINT
INDEX
(Kg/m^3)
(°C)
(°C)
(°C)
150
170
85
880
-46
OIL
VISCOSITY
The viscosity of oil is its tendency to resist flow. A liquid of high viscosity flows very slowly. In variable climates, for example, automobile owners change oil according to prevailing seasons. Oil changes are necessary because heavy oil becomes too thick or sluggish in cold weather, and light oil becomes too thin in hot weather. The higher the temperature of an oil, the lower its viscosity becomes; lowering the temperature increases the viscosity. On a cold morning, it is the high viscosity or stiffness of the lube oil that makes an automobile engine difficult to start. The viscosity must always be high enough to keep a good oil film between the moving parts. Otherwise, friction will increase, resulting in power loss and rapid wear on the parts.
FLASH POINT
The flash point of an oil is the temperature at which enough vapor is given off to flash when a flame or spark is present. The minimum flash points allowed for Navy lube oils are all above 300°F. However, the temperatures of the oils are always far below 300°F under normal operating conditions.
FIRE POINT
. The fire point of a fuel is the temperature at which it will continue to burn for at least 5 seconds after ignition by an open flame. At the flash point, a lower temperature, a substance will ignite briefly, but vapor might not be produced at a rate to sustain the fire. Most tables of material properties will only list material flash points, but in general the fire points can be assumed to be about 10 °C higher than the flash points. However, this is no substitute for testing if the fire point is safety critical.
AUTOIGNITION POINT
The auto-ignition point of an oil is the temperature at which the flammable vapors given off from the oil will burn. This kind of burning will occur without the application of a spark or flame. For most lubricating oils, this temperature is in the range of 465° to 815°F.
POUR POINT The pour point of a liquid is the lowest temperature at which it becomes semi solid and loses its flow characteristics. In crude oil a high pour point is generally associated with high paraffin content, typically found in crude deriving from a larger proportion of plant material. That type of crude oil is mainly derived from a kerogen Type II.
3.2 TYPES OF LUBRICATING OIL In 1999, an estimated 37,300,000 tons of lubricants were consumed worldwide. Automotive applications dominate, but other industrial, marine, and metal working applications are also big consumers of lubricants. Although air and other gas-based lubricants are known, e.g., in fluid bearings), liquid and solid lubricants dominate the market, especially the former. Lubricants are generally composed of a majority of base oil plus a variety of additives to impart desirable characteristics. Although generally lubricants are based on one type of base oil, mixtures of the base oils also are used to meet performance requirements. Base oil group
Mineral oil term is used to encompass lubricating base oil derived from crude oil. The American Petroleum Institute (API) designates several types of lubricant base oil: a) Group I – Saturates <90% and/or sulfur >0.03%, and Society of Automotive Engineers (SAE) viscosity index (VI) of 80 to 120. Manufactured by solvent extraction, solvent or catalytic dewaxing, and hydro-finishing processes. Common Group I base oil are 150SN (solvent neutral), 500SN, and 150BS (brightstock) b) Group II – Saturates over 90% and sulfur under 0.03%, and SAE viscosity index of 80 to 120. Manufactured by hydrocracking and solvent or catalytic dewaxing processes. Group II base oil has superior anti-oxidation properties since virtually all hydrocarbon molecules are saturated. It has water-white co lor. c) Group III – Saturates > 90%, sulfur <0.03%, and SAE viscosity index over 120. Manufactured by special processes such as isohydromerization. Can be manufactured from base oil or sax wax from dewaxing process. d) Group IV – Polyalphaolefins (PAO) e) Group V – All others not included above such as naphthenics, PAG, esters.
In North America, Groups III, IV and V are now described as synthetic lubricants, with group III frequently described as synthesised hydrocarbons, or SHCs. In Europe, only Groups IV and V may be classed as synthetics. The lubricant industry commonly extends this group terminology to includ e: a)
Group I+ with a Viscosity Index of 103 – 108
b)
Group II+ with a Viscosity Index of 113 – 119
c)
Group III+ with a Viscosity Index of at least 140
Can also be classified into three categories depending on the prevailing compositions: a)
Paraffinic
b)
Naphthenic
c)
Aromatic Lubricants for internal combustion engines contain additives to reduce oxidation and improve lubrication. The main constituent of such lubricant product is called the base oil, base stock. While it is advantageous to have a high-grade base oil in a lubricant, proper selection of the lubricant additives is equally as important. Thus some poorly selected formulation of PAO lubricant may not last as long as more expensive formulation of Group III+ lubricant.
3.3 ADDITIVES
A large number of additives are used to impart performance characteristics to the lubricants. The main families of additives are: a)
Antioxidants
b)
Detergents
c)
Anti-wear
d)
Metal deactivators
e)
Corrosion inhibitors, Rust inhibitors
f)
Friction modifiers
g)
Extreme Pressure
h)
Anti-foaming agents
i)
Viscosity index improvers
j)
Demulsifying/Emulsifying
k)
Stickiness improver, provide adhesive property towards tool surface (in metalworking)
l)
Complexing agent (in case of greases)
Note that many of the basic chemical compounds used as detergents (example: calcium sulfonate) serve the purpose of the first seven items in the list as well. Usually it is not economically or technically feasible to use a single do-it-all additive compound. Oils for hypoid gear lubrication will contain high content of EP additives. Grease lubricants may contain large amount of solid particle friction modifiers, such as graphite, molybdenum sulfide.
3.4 IMPACT OF USED LUBE OIL ON HEALTH AND ENVIRONMENT
A release of used oil to the environment, whether by accident or otherwise, threatens ground and surface waters with oil contamination there by endangering drinking water supply and aquatic organisms. Used oil can damage the environment in several different ways: a)
Spilled oil tends to accumulate in the environment, causing soil and water pollution. Oil decomposes very slowly. It reduces the ox ygen supply to the microorganisms that break the oil down into non-hazardous compounds.
b)
Toxic gases and harmful metallic dust particles are produced by the ordinary combustion of used oil. The high concentration of metal ions, lead, zinc, chromium and copper in used oil can be toxic to ecological systems and to human health if they are emitted from the exhaust stack of uncontrolled burners and furnaces.
c)
Some of the additives used in lubricants can contaminate the environment. E.g. zinc dialkyl dithiophosphates, molybdenum disulphide, and other organo-metallic compounds.
d)
Certain compounds in used oil - eg poly-aromatic hydrocarbons (PAH) - can be very dangerous to one's health. Some are carcinogenic and mutagenic. The PAH content of engine oil increases with operating time, because the PAH formed during combustion in petrol engines accumulates in the oil.
e)
Lubricating oil is transformed by the high temperatures and stress of an engine's operation. This results in oxidation, nitration, cracking of polymers and decomposition of organ- metallic compounds
f)
Other contaminants also accumulate in oil during use - fuel, antifreeze/coolant, water, wear metals, metal oxides and combustion products.
g)
It reduces or prevents air and light to reach at the life of bodies which are covered by oil.
h)
One litre of Used / Waste oil can ruin 1 million litre of fresh water and has the ability to destroy both the pure and waste water drainage system
i) j)
It affects the photosynthesis of plant. It causes the oil toxic.
3.5 CONTAMINANT OF USED OIL a) Some contaminants, such as chlorinated solvents, are picked up by the waste oil during use b) or during storage waiting for collection. However, not all chlorine found in waste oil is c) necessarily the result of contamination; small amounts (up to hundreds of ppm) may have d) come from additives in the original product. There are some other contaminants which get e) added to Waste Oils due to the operational conditions. They are: Water a)
Fuel burns to CO2 and H2O. When an engine is cold, such generated water can pass
b)
through to the lube oil.
Fuel
Unburnt petrol / diesel passes through to the lube oil during engine start-ups. Carbon a)
Forms as a result of incomplete combustion when an engine is warming up and it passes
b)
through to the lube oil.
Dust
Small particles pass into the engine through the ai r breather. Metals
Due to normal component wear and tear. Oxidation Products a)
Additive chemicals at elevated temperatures in the presence of oxygen can oxidize forming
b)
corrosive acids
3.6 RE-REFINING OF USED LUBRICATING OIL BY VACUUM DISTILLATION Dewatering of waste oil
The oil is de-watered in large settling tanks, wherein the heavier water settles to the bottom of the tank and the light oil floats on top. The water at the bottom is drained off and should normally be treated before disposal. However this does not remove the water completely and small quantity still remains. Then this dewatering oil is subjected to vacuum distillation to remove all contaminants present in it. Vacuum Distillation
This is the core process for lubricating oil re-refining. In India, the general practice is to refine waste oil in a vacuum process. The de-watered oil is heated in vacuum distillation tower under vacuum. As the temperature in the distillation tower rise, the temperature of various components waste oil increases. Temperature in the tower maintained in descending order from top to bottom. The various components after reaching at their respective boiling point, they tends to vaporize and start to liberated and rise as vapour to be condensed in a condenser. The tower is filled with de-watered waste lubricating oil. The capacity of the tower may be 6600litres. It takes about one hour to charge the tower completely and for oil to pick up the sensible heat from the tower. As the temperature of the dewatered oil rises, the ware present in the oil is removed first and at around 170°C180°C, gasoline and diesel is vapourised and released from the oil and from the tower. At this time vacuum inside the tower ranges from 15 torr (.0197 atm) to 20 torr (.0263 atm). After removal of diesel the pressure inside the tower is brought to less than one torr. This can be done by using a vacuum pump. The lube oil is the main product and its distillation starts around 270°C and continues upto 300°C- 320°C. Most of the lubricating oil distils out during this process. Metals, dust, rust, soot are the bottom product which are drained out for disposal. Total time taken for the process is about 7-8 hours.
DIAGRAM OF VACUUM DISTILLATION TOWER FOR REREFINING OF USED LUBE OIL
3.7 ADVANTAGES OF RE-REFINING OF USED OIL Economic Reasons
The most important advantage of Re-Refining is economic. Industries are using more and more lubricants and this means more and more expenditure on lubricants. If the option of Re-Refining is adopted by these industries a lot of expenditure on lubricants can be saved and the saving can be as high as up to 50%.
Conservation of precious petroleum product
In India all lube oil is imported. If Used Oils generated in the country is processed and lube base oil is recovered import bill can be substantially reduced. Therefore Re-Refining is an import substitute. If the demand of imports of Lube Oil is reduced because of ReRefining the advantage of Re-Refining is saving of foreign exchange for the Country. Like other advanced Countries in India Re-Refining of Used Oil should be made mandatory.
Protection of Environment
Re-Refining of Used Oil can play a big role in reducing pollution. Reckless dumping of Used Oil can cause damage to land and water and burning of Used Oil as fuel can pollute air. Re-refining of used oil while saving the environment also creates wealth for the generator of used oil.
Utilization of hazardous waste
Used oil is termed as hazardous. Lube oil does not wear out with use it only gets contaminated with water, carbon and fuel etc. that means used oil when it is ready for rejection can be re-used. Re-refining of used oil is the best mode of disposal of used oil. Re-refining of the used oil is the most rational and lucrative solution for the problem of disposal of hazardous waste. This is an outstanding example of converting waste into wealth.
Lubricating oil market in India As per an IIP study, 10,00,000 tonnes of lube oil was consumed by the Indian market in 2001. 6,50,000
tonnes
per
year
is
engine
crankcase
oil.
Around 380 million dollars i.e. around Rs.17,290 million are spent in procuring base oil. Around 5,00,000 tonnes of used oil can be recycled producing 3,50,000 tonnes of refined base oil. This results in a saving of 140 million dollars i.e. about Rs.6,370 millions in foreign exchange. The above observations are based on the assumption that base oil costs US$400 for every MT.
3.8 APPLICATION a) Automotive a. Engine oils i. Petrol (Gasoline) engine oils ii. Diesel engine oils b. Automatic transmission fluid c. Gearbox fluids d. Brake fluids e. Hydraulic fluids b) Tractor (one lubricant for all systems) a. Universal Tractor Transmission Oil – UTTO b. Super Tractor Oil Universal – STOU – includes engine c) Other motors a. 2-stroke engine oils d) Industrial a. Hydraulic oils b. Air compressor oils c. Gas Compressor oils d. Gear oils e. Bearing and circulating system oils f.
Refrigerator compressor oils
g. Steam and gas turbine oils e) Aviation a. Gas turbine engine oils b. Piston engine oils f) Marine a. Crosshead cylinder oils b. Crosshead Crankcase oils c. Trunk piston engine oils d. Stern tube lubricant. e.
CHAPTER 4 CONCLUSION Thus this process of re-refining of used lubricating oil, using vacuum distillation process can be adopted. This will reduce environment pollution and save our petroleum resources and also would be well worth of it.
REFERENCE 1. M. Fuchs, The World Lubricants Market, 8th International Conference on Industrial Tribology, Calcutta, 1997 2. IARC, Classification of Mineral oils According to their Carcinogenicity, Vol. 33, 1984. 3. T. Sullivan, ―Forecast: New Price Leaders in Town,‖ Lube Report 5(27) (2005). 4. Chevron press release, April 8, 2005. 5. H. E. Henderson, ―Gas-to-Liquids,‖ Canadian Chemical News September: 17 – 19 (2003). 6.
www.lubereport.com/e_article000194571.cfm
7. T. Sullivan, ―ExMo Rules the Base Oil Roost,‖ Lube Report 5(25) (2005).
