Chapter 1&2. 7 chemical blocks (1) Ethylene (2) Propylene (3) Butenes & Butadiene (4) Methane (5) Benzene (6) Toluene (7) Xylene : olefins (1) Ethylene (2) Propylene (3) Butenes & Butadiene (olefins) (BTX) (5) Benzene (6) Toluene (7) Xylene (Aromatic hydrocarbon) (4) Methane (petrochemical) petroleum natural gas. 7 chemical blocks synthesis gas (syngas) : mixture of carbon monoxide(co) and
hydrogen(h 2 ) Natural gas ( ) - methane, CO 2, H 2 S. Associated gas gas crude oil Non-associated gas gas crude oil - source of energy. Dry natural gas. 85~95% methane. Wet natural gas 0.3 gal/1000ft 3. Condensable hydrocarbon. Dry gas water content (humidity) treatment. Dry sour gas (or sour natural gas) hydrogen sulfide (H 2 S) CO 2. natural gas acid gases hydrogen sulfide CO 2. Acid gas removal mono and diethanolamines (MEA, DEA). molecular sieve (zeolite). Natural gas humidity adjustment hydrate (powder ) H 2 O. Hydrocarbon + H 2 O hydrate formation (under pressure and temp in gas pipe line). Glycol H 2 O
( ) ethylene glycol, diethylene glycol. -, water is soluble in EG, but gas is not soluble. - Silica gel molecular sieve H 2 O. Wet natural gas condensation hydrocarbon - (liquid propane ). Condensable hydrocarbon (natural gas liquids) - propane liquefied petroleum gas(lpg). LPG propane butane. Natural gas (1) Humidity (2) Condensable hydrocarbon (3) Hydrogen sulfide, CO 2 methane. Liquefied Natural gas : ( ) water vapor < 10 ppm carbon dioxide < 100 ppm H 2 S < 50 ppm Associated gas ( ) - oil, associated gas excess gas. Natural gas liquids (NGL) natural gas associated gas
.(ethane~pentane ). LPG propane butane. Petroleum composition and classification. Petroleum (crude oil) natural gas, gasoline, naphtha, kerosene, fuel and lubricating oils, paraffin wax, etc. nonhomogeneous mixture., main hydrocarbon.(s, O 2, N 2, CH compounds), dissolved gases, metallic compound. Specific crude oil, refinery process. high cyclo paraffin (naphthene) crude oil ethylene aromatics. (petroleum) hydrocarbon : (1) hydrocarbon (2) gasoline fraction normal paraffins (straight chain) branched paraffins alkyl cyclopentanes alkyl cyclohexanes alkyl benzenes (3) 5 gasoline fraction.(see page9) Nonhydrocarbon compounds : - Sour crude oil > {(0.05cubic feet of H 2 O)/(100 gallons)} - Crude oil density sulfur (S)
. - Hydrocarbon H2S,nitrogen, oxygen compounds, metallic compounds. (crude oil) classification (1) Light Paraffinic wax (hydrocarbon ). (2) Paraffinic wax asphalt. (3) Naphthenic or asphaltic wax asphalt (4) Aromatic aromatic. Mixed crude oil paraffinic naphthenic. The correlation Index, BMCI ( paraffinic?, mixed? or aromatic? ) BMCI(the us Bureau of Mines Correlation Index) BMCI=48,640/K + 473.7/d 456.8 (0 for paraffins, 100 for benzene). K= the mid-boiling point of a fraction in Kelvin degrees. D= the specific gravity of the fraction at 60/60 F Crude oil quality (1) specific gravity density. API (degrees) = (141.5) / (Sp. Gr. 60/60 F) 131.5 (2) Pour point oil wax crude oil? (3) Sulfur further treatment is needed. (corrosive and reduce the lifetime of the engine). (4) Carbon residue heating coke. Do not evaporate.
(5) Ash content amount of ash left after burning oil. - metallic salts, metal oxide, silicon oxide Total World Oil Reserves Jan.1, 1978 646 billion barrels 1 barrel = 31.5 gallon = 120 l 2.2 ) 1. (65-90%) 20 C.,, 2. ( ) (C 5,C 6 70~140 C..,. 140~200 C (C 7 ~C 9 ) 3. gas oil 4. (residual oil) 175~275 C 200~370 C 370 C C 9 ~C 16,,,. C 15 ~C 25...
, (see 2.2 also) p. 60 Refinery Processes ( ). Crude oil Fuel(64%) + Petrochemical (6%) -1979 Fuel (89%) + Petrochemical (11%) -1990. Crude oil two commercial processes Heavy Oil Cracking (HOC) Thermal pyrolysis of the resulting hydrocarbon. Major Products Olefins-ethylene, propylene, and mixed C4 s Aromatic hydrocarbon (BTX). Refinery Processes (1) Physical separation processes- Distillation Absorption
Adsorption Extraction Distillation a physical separation Process based on differences in boiling points ( ). - processing. gasoline, naphtha, gas oil, diesel oil. vacuum distillation. - Vacuum distillation: to avoid cracking the long-chain hydrocarbons. Gas oil top product Lube oil Asphalt bottom - Vacuum distillation middle distillates. Absorption a process used to collect gases in a liquid absorbent. Adsorption a process used to free petroleum gases from trace amounts of undesired gases or vapors by adsorbing them on a solid material.. Solid material have a large surface area. ( molecular sieve, silica gel, alumina ) Solvent extraction Liquid solvents
. ( ) Propane deasphalting the liquid propane dissolves paraffinic hydrocarbons and leaves aromatic and asphaltic material. (2) Conversion Processes to produce more gasoline and better gasoline.. The four major gasoline making and octane boosting processes are: catalytic cracking( ) catalytic reforming ( ) hydrocracking ( ) alkylation ( ) Petroleum Refinery Processes (Conversion) Thermal conversion process Catalytic conversion process (1) Thermal conversion process the first process used to increase gasoline production. viscosity breaking (visbreaking) improvement of its pour point by including a mild thermal-cracking step. coking a severe thermal cracking process used to obtain light
products and coke from topped crude and heavy residues which cannot be directly fed into a catalytic cracking unit because of their high metal and asphaltic content. Steam cracking steam thermal cracking olefin. (2) Catalytic conversion process catalytic reforming process ( ) catalytic cracking process ( ) hydrocracking ( ) hydrotreating ( ) hydrorefining ( ), alkylation polymerization dimerization isomerization catalytic process. Catalytic reforming process ( ) A process used to produce a higher quality gasoline. The feed to a catalytic reforming unit is naphtha, either virgin or produced from a thermal or catalytic hydrocracking unit. - Benzene, toluene and xylene (BTX) are produced from naphtha during catalytic reforming by two distinct types of reaction. - ( ) The dehydrogenation of naphthenes :
- cyclohexene -> benzene C 7 naphthene -> toluene CH 3 C 8 naphthene -> xylene CH 3 CH 3. Catalyst the catalysts generally used for catalytic reforming. platinum.. Reforming reaction occur at different rate and degrees of conversion depending on the themperature, hydrogen partial pressure and catalyst used. ( ) Aromatization the dehydrogenation of cyclohexanes to benzene and methyl benzenes is completely fast and endothermic. ( H = 49.08 kcal/mol ) + 3H 2 C 6 H 12 C 6 H 6 - The production of benzene is favored by high temp. and low pressure. Hydrocracking is a cracking reaction where by high molecular weight hydrocarbons pyrolyze to lower molecular weight paraffins and Olefins in the prsence of hydrogen.. Hydrocracking is a hydrogen-consuming reaction that leads to higher gas
production. Dealkylation like hydrocracking, is a hydrogen-consuming reaction, At higher hydrogen partial pressure, dealkylation is more favorable. ( ) R + H 2 + RH -, yield. Hydrocracking the most versatile modern petroleum refining processes. is specially adapted to the processing of low value stocks such as those that are not suitable for a catalytic cracking or reforming unit because of high metal, nitrogen and/or sulfur content. - Is also suitable for high aromatic feeds which cannot be processed easily by conventional catalytic cracking processes. catalytic cracking the main advantage is increased gasoline production, and the formation of hydrocarbon components having high antiknock properties. Another advantage is the production of C 3 and C 4 hydrocarbons for LCP uses. Hydrogen reforming (or hydrogen treating)- a process designed to reduce the sulfur content of atmospheric residue, vacuum gas oil, and vacuum resides.
Isomerization Alkilation do not increase the quantity of gasoline but do contribute to the quality of the gasoline. Dimerization Isomerization a small volume but important refinery process. Normal butane is isomerized to isobutene to be used for the alkylation of isobutylene and other olefins for the production of high octane hydrocarbons such as isooctane. Alkylation generally applies to the acid catalyzed reaction between isobutene and various light olefins. The product is highly branched paraffin hydrocarbons, alkylate, used for blending to improve the octane number of gasoline. Dimerization propylene- propane mixture to give isohexanes or propylenebutene mixture to yield isoheptenes: to upgrade the octane number. Both phosphoric acid and sulfuric acid are used as catalysts. Octane value a number indicating the degree of knocking of a fuel mixture under standard test conditions. - Pure normal heptane(a very high knocking fuel)is arbitrarily assigned an octane number of zero, while isooctane (a branched chain paraffin) is assigned 100. Thus a rating of 80 for a given fuel indicates that its degree of knocking in a standard test engine is equal to that of a mixture of 80 parts isooctane and 20 parts n-heptane ( 80 ). - Lead alkyl compound (usually tetraethyl or tetramethyl lead) octane value 100 unleaded
(Petroleum Refining Reactions) -. (a) (steam cracking) n- (b) (catalytic cracking) 5 12. (c) (hydrocracking).,,, H2S, NH3, H 2 O. (d) (polymerization, oligomerization) H 2 SO 4 H 3 PO 4. (oligomers). (e) (alkylation) - (, )., (f) (catalytic reforming) - / /, BTX. (g) (dehydrogenation) -.
styrene, propylene. (h) (dimerization) -. n-butane isobutene, n-pentane isopentane, n-hexane -> isohexane, n- butene -> isobutene. o-, m-xylene -> p-xylene (i) (hydrocracking) -,, H 2 S, NH 3, H 2 O..