Refining thermal cracking

H2S is found with the reservoir gas and dissolved in the crude (< 50 ppm by weight), but it is formed during refining operations such as catalytic cracking, hydrodesulfurization, and thermal cracking or by thermal decomposition of sulfur[Pg.322]

Manufacture of Monomers. The monomers of the greatest interest are those produced by oligomerization of ethylene (qv) and propylene (qv). Some olefins are also available as by-products from refining of petroleum products or as the products of hydrocarbon (qv) thermal cracking. 

Ethyleneamines are used in certain petroleum refining operations as well. Eor example, an EDA solution of sodium 2-aminoethoxide is used to extract thiols from straight-mn petroleum distillates (314) a combination of substituted phenol and AEP are used as an antioxidant to control fouling during processing of a hydrocarbon (315) AEP is used to separate alkenes from thermally cracked petroleum products (316) and TEPA is used to separate carbon disulfide from a pyrolysis fraction from ethylene production (317). EDA and DETA are used in the preparation and reprocessing of certain... 

Figure 2 shows a simplified flow plan for a typical conversion type refinery. The atmospheric P/S residuum can be fed to a vacuum pipestill. The vacuum tower enables the refiner to cut deeper into the crude, at the same time avoiding high temperatures (above about 750 °F) which cause thermal cracking with resultant deposition of coke and tarry residues in the equipment. 

By the mid-1930s, catalytic technology entered into petroleum refining. To a greater extent than thermal cracking, catalysis permitted the close control of the rate and direction of reaction. It minimized the formation of unwanted side reactions, such as carbon formation, and overall improved the yield and quality of fuel output. 

Before the advent of the catalytic cracking process, thermal cracking was the primary process available to convert low-value feedstocks into lighter products. Refiners still use thermal processes, such as delayed coking and visibreaking, for cracking of residual hydrocarbons. 

Cracking (Chapter 3 Focus On) A process used in petroleum refining in which large alkanes are thermally cracked into smaller fragments. 

Gyro Also called Gyro-cracking. An early vapor-phase thermal cracking process for refining petroleum. 

Thermal cracking was the first crude oil refining process to contribute more useful products from a barrel of oil than straight distillation [80]. Houdry s development of catalytic cracking shortly before World War II spurred then Standard Oil of New... 

Because of the tendency of thermal cracking to produce coke as a by-product of the process, most refiners have replaced thermal cracking units with catalytic cracking processes. However, in certain parts of the world, thermal cracking units still exist. 

Crude oil typically contains little to no olefinic compounds. Through refining and processing, however, olefins are produced and become a part of various crude oil fractions. Olefins can be found in thermally cracked and catalytically cracked gasoline fractions as well as in FCC cycle oils and coker gas oils. For this reason, it is not unusual for finished gasoline and distillate blends to contain a high-olefin-content stream. 

The use of cracked stocks in No. 2 has meant additional problems for the refiner. Besides having to refine for odor and color, he is also faced with a stability problem. While catalytic cracking as a rule produces a more stable oil than does thermal cracking, there are still compounds present which on aging will form insoluble sludge. This sludge, if permitted to form, clogs burner screens, and eventually results in trouble. 

Some refiners used atmospheric coke stills to prepare clean charging stock for the thermal cracking units. The clean stock formed less coke, so the thermal cracking units could stay on stream longer without shutting down to clean out the coke (18),... 

Thermal Cracking—A refining process which decomposes, rearranges, or combines hydrocarbon molecules by the application of heat without the aid of a catalyst. 

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