PETROLEUM REFINING

PETROLEUM INDUSTRY Petroleum comes from the Latin terms petra, "rock," and oleum, "oil." It is used to describe a broad range of hydrocarbons that are found as gases, liquids, or solids beneath the surface of the earth. The two most common forms are natural gas and crude oil. HISTORY 1500 AD - Chinese dig oil wells greater than 2000’ deep 1846 – Abraham Gessnerof Novascotia, Canada devised a process to produce kerosene from coal. 1847 - First “rock oil” refinery in England 1854 - Ignasi Lukasi Siewicz began producing kerosene from hand dug oil wells near the town of Krosno, Poland. 1856 – World’s first petroleum refinery was built in Ploiesti, Romania using the abundant oil available. 1858 – First oil well was drilled in Ontario, Canada by James Miller Williams. 1859 – Petroleum industry began when Edwin Drake found oil near Titusville Pennsylvania with 69’ oil well producing 35bpd. 1870 - US Largest oil exporter; oil was US 2nd biggest export Early 20th Century – Introduction of internal combustion engine and its use in automobiles created a market for gasoline that was impetus for fairly rapid growth of the petroleum industry. Early 1940’s - Most Petroleum Refineries in the United States consisted simply of Crude oil distillation units. Some refineries also had vacuum distillation units as well as thermal cracking units such as visbreakers. 1942 - First Fluidized Catalytic Cracker (FCC) commercialized 1970 - First Earth Day; EPA passes Clean Air Act 2005 - US Refining capacity is 17,042,000 bpd, 23% of World’s 73MM II. RAW MATERIALS Natural Gas - is a mixture of lightweight alkanes, accumulates in porous rocks. A typical sample of 
natural gas contains about 80% methane (CH4), 7% ethane (C2H6), 6% propane (C3H8), 4% butane and isobutane (C4H10), and 3% pentanes (C5H12). The C3, C4, and C5 hydrocarbons are removed before the gas is sold. The propane and butanes removed from natural gas are usually liquefied under pressure and sold as liquefied petroleum gases (LPG). Crude Oil - is a composite mixture of hydrocarbons (50-95% by weight) occurring naturally. Crude oil consists mostly of hydrocarbons with small amounts of other organic chemical compounds that may contain nitrogen, oxygen or sulfur. It may also contain trace amounts of metals such as iron, nickel, copper and vanadium. SOURCES OF PETROLEUM Tar Sands (Oil Sands) – are combination of clay, sand, water, and bitumen (a heavy black viscous oil). Tar sands are mined and processed to generate oil similar to oil pumped from conventional oil wells, but extracting oil from tar sands is more complex than conventional oil recovery. Oil Shale – a rock that contains significant amounts of organic material in the form of kerogen. Up to 1/3 of the rock can be solid organic material. Liquid and gaseous hydrocarbons can be extracted from the oil shale, but the rock must be heated and/or treated with solvents. This is usually much less efficient than drilling rocks that ill yield oil or gas directly into a well. CONSTITUENTS OF PETROLEUM Aliphatics (Open Chain Hydrocarbons) n-Paraffin series (Alkanes), – comprises a larger fraction of most crudes than any other. They have poor antiknock properties. e.g. n-hexane, n-heptane Iso-paraffin series (Iso-alkanes), – branched chain materials perform better in internal-combustion engines than n-paraffins. They may be formed by catalytic reforming, alkylation, polymerization, or isomerization. e.g. 2-methylhexane Olefin Series (Alkenes), – generally absent in crudes, but cracking produce them. They improve the antiknock quality of gasoline. e.g. ethylene, propylene, butylene Ring Compounds Naphthene Series (Cycloalkanes) – second most abundant series of compounds. Has the same chemical formula as the olefins, but lacks their instability and reactivity because the molecular configuration permits them to be saturated and unreactive like the alkanes. e.g. methylcyclopentane, cyclohexane Aromatic Series (Benzenoid Series), – they have high antiknock value and good storage stability. They are formed by refining processes. e.g. benzene, toluene Lesser Components – sulfur, nitrogen, metals (Fe, Mo, Na, Ni, V) *Octane Number (ON)- measure of the knock resistance of the gasoline. Also known as antiknock. *Knock Resistance – fuels ability not to self ignite and burn in an uncontrolled way while the fuel is being compressed. MANUFACTURING PROCESS Petroleum Refining - refers to the process of converting crude oil into useful products. Crude oil is composed of hundreds of different hydrocarbon molecules, which are separated through the process of refining. Three main steps: Separation – refers to the process of distillation. Crude oil is heated in a furnace so that hydrocarbons can be separated via their boiling points. The lightest fractions rise to the top and the heaviest fractions settle at the bottom. Conversion - The various hydrocarbons produced are then chemically altered to make them more suitable for their intended purpose.e.g. naphthas are "reformed" from paraffins and naphthenes into aromatics. Treatment (Purification) – It is the final process of refining, and includes combining processed products to create various octane levels, vapor pressure properties, and special properties for products used in extreme environments. e.g. removal of sulfur from diesel fuel for it to meet clean air guidelines A. SEPARATION 1. Crude Oil Desalting - The crude oil contains salt in the form of dissolved salt in the tiny droplet of water which forms a water-in oil emulsion. This water cannot be separated by gravity or through mechanical means. It is separated through electrostatic water separation. This process is called desalting. * Types of Salt in Crude Oil - these chlorides, except NaCl, hydrolyze at high temperature to hydrogen chloride. DESALTING PROCESS: Water Washing - Water is mixed with the incoming crude oil through a mixing valve. The water dissolves salt crystals and the mixing distributes the salts into the water, uniformly producing very tiny droplets. Demulsifying agents are added at this stage to aide in breaking the emulsion by removing the asphaltenes from the surface of the droplets. Heating - The crude oil temperature should be in the range of since the water-oil separation is affected by the viscosity and density of the oil. Coalescence - The water droplets are so fine in diameter in the range 1-10 mm that they do not settle by gravity. Coalescence produces larger drops that can be settled by gravity. This is accomplished through an electrostatic electric field between two electrodes. The electric field ionizes the water droplets and orients them so that they are attracted to each other. Agitation is also produced and aides in coalescence. Settling 2. Atmospheric Distillation - takes place in a distilling column at or near atmospheric pressure. The crude oil is heated to oC and the vapour and liquid are piped into the distilling column. The liquid falls to the bottom and the vapour rises, passing through a series of perforated trays (sieve trays). Heavier hydrocarbons condense more quickly and settle on lower trays and lighter hydrocarbons remain as a vapour longer and condense on higher trays. The temperature of tray is progressively cooler from bottom to top. 3. Vacuum Distillation - To further distil the residual oil from the atmospheric distillation column, the distillation must be performed at absolute pressures as low as 10-50 mmHg so as to limit the operating temperature to less than . Vacuum Distillation is the reduced temperature requirement at lower pressures. Vacuum Distillation increases the relative volatility of the key components. 4. Solvent Deasphalting - This is the only physical process where carbon is rejected from heavy petroleum fraction such as vacuum residue. Propane in liquid form (at moderate pressure) is usually used to dissolve the whole oil, leaving asphaltene to precipitate. The deasphalted oil (DAO) has low sulphur and metal contents since these are removed with asphaltene. This oil is also called ‘‘Bright Stock’’ and is used as feedstock for lube oil plant. The DAO can also be sent to cracking units to increase light oil production. 5. Solvent Extraction - In this process, lube oil stock is treated by a solvent, such as phenol and furfural, which can dissolve the aromatic components in one phase (extract) and the rest of the oil in another phase (raffinate). The solvent is removed from both phases and the raffinate is dewaxed. 6. Solvent Dewaxing - The raffinate is dissolved in a solvent (methyl ethyl ketone, MEK) and the solution is gradually chilled, during which high molecular weight paraffin (wax) is crystallized, and the remaining solution is filtered. The extracted and dewaxed resulting oil is called ‘‘lube oil’’. In some modern refineries, removal of aromatics and waxes is carried out by catalytic processes in all hydrogenation processes. B. CONVERSION 1. Cracking (Pyrolysis) - Cracking processes break down heavier hydrocarbon molecules (high boiling point oils) into lighter products such as petrol and diesel. a. Catalytic Cracking - Fluid catalytic cracking (FCC) is the main player for the production of gasoline. The catalyst in this case is a zeolite base for the cracking function. The main feed to FCC is VGO and the product is gasoline, but some gas oil and refinery gases are also produced. b. Thermal Cracking c. Catalytic Hydrocracking - For higher molecular weight fractions such as atmospheric residues (AR) and vacuum gas oils (VGOs), cracking in the presence of hydrogen is required to get light products. In this case a dual function catalyst is used. It is composed of a zeolite catalyst for the cracking function and rare earth metals supported on alumina for the hydrogenation function. The main products are kerosene, jet fuel, diesel and fuel oil. 2. Catalytic Reforming - In this process a special catalyst (platinum metal supported on silica or silica base alumina) is used to restructure naphtha fraction (C6–C10) into aromatics and iso-paraffins. The produced naphtha reformate has a much higher octane number than the feed. This reformate is used in gasoline formulation and as a feedstock for aromatic production (benzene–toluene–xylene, BTX). 3. Polymerization 4. Alkylation - process in which isobutane reacts with olefins such as butylene (C4 ) to produce a gasoline range alkylate. The catalyst in this case is either sulphuric acid or hydrofluoric acid. The hydrocarbons and acid react in liquid phase. Isobutane and olefins are collected mainly from FCC and delayed coker. 5. Isomerization - Isomerization of light naphtha is the process in which low octane number hydrocarbons (C4, C5, C6) are transformed to a branched product with the same carbon number. This process produces high octane number products. One main advantage of this process is to separate hexane (C6) before it enters the reformer, thus preventing the formation of benzene which produces carcinogenic products on combustion with gasoline. The main catalyst in this case is a Pt-zeolite base. 6. Coking a. Delayed Coking - This process is based on the thermal cracking of vacuum residue by carbon rejection forming coke and lighter products such as gases, gasoline and gas oils. The vacuum residue is heated in a furnace and flashed into large drums where coke is deposited on the walls of these drums, and the rest of the products are separated by distillation. b. Flexicoking - In this thermal process, most of the coke is gasified into fuel gas using steam and air. The burning of coke by air will provide the heat required for thermal cracking. The products are gases, gasoline and gas oils with very little coke. c. Visbreaking - This is a mild thermal cracking process used to break the high viscosity and pour points of vacuum residue to the level which can be used in further downstream processes. In this case, the residue is either broken in the furnace coil (coil visbreaking) or soaked in a reactor for a few minutes (soaker visbreaker). The products are gases, gasoline, gas oil and the unconverted residue. C. TREATMENT (PURIFICATION) 1. Hydrotreating - This is one of the major processes for the cleaning of petroleum fractions from impurities such as sulphur, nitrogen, oxy-compounds, chloro-compounds, aromatics, waxes and metals using hydrogen. The catalyst is selected to suit the degree of hydrotreating and type of impurity. Catalysts, such as cobalt and molybdenum oxides on alumina matrix, are commonly used. 2. Desulfurization IV. FINAL PRODUCTS Natural Gas Liquids – contains fewer high-boiling constituents, considerably more volatile e.g. Liquefied Petroleum Gas Light Distillates e.g. Motor Gasolines, Solvent Naphthas, Jet Fuel, Kerosene, Light heating oils *Gasoline- most important product, 45% of the crude is processed to gasoline Intermediate Distillates – distillates used mainly for transportation fuels and home heating furnaces. e.g. Heavy fuel oils, Diesel Oils, Gas Oils Heavy Distillates – suited for cracking to produce motor gasoline, used for bunker fuel for ships and in large stationary power plants. e.g. Heavy mineral oils(medicinal), heavy flotation oils, lubricating oils, waxes Residues – by-products of the refining process e.g. Lubricating oils, Fuel Oils, Petrolatum, Road Oils, Asphalts, Coke V. STANDARD TEST FOR THE RAW MATERIALS AND PRODUCTS 1. Acidity – present in aviation turbine fuels due to the acid treatment during the refining process/naturally occurring organic acids. - undesirable because it may cause metal corrosion and impairment of water separation characteristics of the fuel. 2. Ash Content – used to evaluate petroleum coke and indicates the amount of undesirable residue present. 3. Sulfur Content – responsible for numerous hydrotreating operations in the refinery process. 4. Flash and Fire Point – relevant to the safety and transmission of refinery products. *Flash Point – temperature above which the product flashes forming a mixture capable of inducing ignition with air. *Fire Point – temperature well above the flash point where the product could catch fire. 5. Octane Number – relevant in the reforming, isomerization and alkylation process. 6. Heat of Combustion of Petroleum – petroleum products that are used for burning or heating. - critical property of fuels intended for use is weight-limited crafts such as airplanes and hydrolysis. 7. Vapor Pressure of Crude Oil – important physical property for shipping and storage. 8. Volatility – measure of the amount of least volatile components present in the product. 9. Pour Point – the temperature at which the product ceases to flow upon further cooling. *Cloud Point - the temperature at which a cloudy appearance of the product occurs when cooling. 10. Salt Content –indicates the amount of salt dissolved in water. VI. GOVERNMENT POLICIES 1. Oil Exploration and Development Act of 1972 - The Act, conferred by Presidential Decree 87, provides the legal basis for the exploration and development of indigenous petroleum resources authorizing the grant of service contracts entered into thru public bidding, or through negotiations. 2. Presidential Decree 1857 - This law amends certain sections of PD 87, offering improved fiscal and contractual terms to service contractors with special reference to deepwater oil exploration. 3. DOE Circular No. 2003-05-005 - This Circular establishes the procedures for the Philippine contracting round in petroleum prospective areas. 4. DOE Circular No. 2003-05-006 - DC 2003-05-006 provides the guidelines to the financial and technical capabilities of a viable petroleum exploration and production company. 5. Executive Order No. 66 - This order designates the Department of Energy as the lead agency in developing the natural gas industry. 6. DOE Circular No. 2002-08-005 - The circular sets the interim rules and regulations governing the transmission, distribution and supply of natural gas. 7. Other Issuances - Philippine Environmental Policy Act (Presidential Decree 1151) Enacted in 1977, this act requires the government and the private sector to undertake environmental impact assessments of their project activities which may significantly affect the quality of the environment. 8. Philippine Environmental Code (P.D. 1152) - The Code provides a detailed prescriptions on the management of air quality, water quality, land use, natural resources and waste. 9. Environmental Impact Statement System (P.D. 1586) - The decree which took effect in 1978 provides details on Environmental Impact Statement (EIS) System. 10. National Integrated Protected Areas System Act of 1992 - The act, by virtue of Republic Act No. 7586, provides for the establishment and management of national integrated protected areas system, defining its scope and coverage. Section 14 of the NIPAS Act specifies the survey of energy resources in protected areas solely for data gathering. Any exploitation and utilization of energy resources found within NIPAS areas shall be allowed only thru passage of law by Congress. 11. The Indigenous People's Rights Act of 1997 (Republic Act 8371) - Establishes implementing mechanisms to protect and promote the rights of indigenous cultural communities/indigenous peoples. 12. Memorandum Agreement - DENR-DOE Memorandum of Agreement (MOA) On Streamlining of EIS Process for Energy VII. LIST OF PETROLEUM COMPANIES A. World’s Refineries Jamnagar Refinery (Reliance Industries) Paraguana Refinery Complex (PDVSA) SK Energy Ulsan Refinery (SK Energy) Ruwais Refinery (Abu Dhabi Oil Refining Company) Yeosu Refinery (GS Caltex) Onsan Refinery (S-Oil) Port Arthur Refinery (Motiva Enterprises) Singapore Refinery {ExxonMobil} Baytown Refinery (ExxonMobil) Ras Tanura Refinery (Saudi Aramco) Garyville Refinery (Marathon Petroleum) Baton Rouge Refinery (ExxonMobil) Galveston Bay Refinery (Marathon Petroleum) Abadan Refinery (NIOC) Corinth Refinery (Motor Oil Hellas) B. Philippine Refineries Bataan Refinery (Petron) Tabangao Refinery (Royal Dutch Shell) Batangas Refinery (Caltex/Chevron) 1