Hydrocarbons fluid catalytic cracking

A dephlegmator process can be used to recover ethylene—ethane and heavier hydrocarbons from fluid catalytic cracking (FCC) unit off-gas (Fig. 7). Pretreated feed gas is cooled to about 230 K and then further cooled and rectified in a dephlegmator to recover 90 to 98% of the ethylene, 99 % of the... 

Fluid catalytic cracking over an acid catalyst converts residual hydrocarbons from the vacuum gas oil fraction into valuable olefins, gasoline, and diesel products. The catalytic cracking proceeds... 

Hydrocarbon feedstocks for fluid catalytic cracking units (FCCU s) contain organo-sulfur compounds. The sulfur content of these feedstocks is about 0.3% to 3.0%, expressed as elemental sulfur. 

Olefins are hydrocarbon compounds with at least two carbon atoms and having a double bond. Their unstable nature and tendency to polymerize makes them one of the very important building blocks for the chemical and petrochemical industry (Gary and Handwerk, 1994). Although olefins are produced by fluid catalytic cracking in refineries, the main production source is through steam cracking of liquefied petroleum gas (LPG), naphtha or gas oils. 

Harding, R. H., Zhao, X., Qian, K., Rajagopalan, K., and Cheng, W.-C. Fluid Catalytic Cracking Selectivities of Gas Oil Boiling Point and Hydrocarbon Fractions. Industrial Engineering Chemistry Research 35 (1996) 2561-69. 

Reynolds, B.E., E.C. Brown, and A, Silverman Clean Gasoline Via Vacuum Residium Hydrotreating and Residium Fluid Catalytic Cracking, Hydrocarbon Piocessing, 43 (April 1992). 

Several hydrocarbon processes are available for upgrading resid hydrotreating, Fluid Catalytic Cracking (FCC), coking etc., some more capital intensive than others. The most widely prevalent process is the FCC process. Therefore any advances in processing resid in FCC units will have wide application. This paper deals with concepts for developments in resid cracking, particularly in resid FCC development, evaluation and application. 

Reboiled stripping is efficient for mixtures containing a significant amount of light and intermediate components. An example is the separation of C2 and C3 fractions from a hydrocarbon mixture issued from fluid catalytic cracking. The initial precooled mixture is sent to the top of a distillation column provided only with reboiler. The top product contains gases and light components stripped out... 

Fig. 18.19. Fluid catalytic cracking—UOP LLC. Combustor style is used to crack process gas oils and moderately contaminated resids, while the two-stage unit is used for more contaminated oils. (Source Hydrocarbon Processing, 2004 Refining Process Handbook. CD-ROM. September 2004 copyright 2004 by Gulf Publishing Co., all rights reserved.)...

In petrochemical and oil refining operations, the zeolite is primarily responsible for the catalyst s activity, selectivity and stability (catalytic, thermal and hydrothermal). The fluid catalytic cracking process (FCC) is the most widely used of the oil refining process and is characterized by the use of a finely divided catalyst, which is moved through the processing unit. The catalyst particles are of such a size (about 70 pm) that when aerated with air or hydrocarbon vapor, the catalyst behaves like a liquid and can be moved easily through pipes. 

The work just cited refers to beds of small diameter. Designers and operators of large-scale catalytic fluid beds of Group A powders now appreciate that all of these beds function beyond the Lanneau-Kehoe-Davidson transition (Avidan, 1982 Squires et al., 1985). Most are turbulent beds Sasol reactors and some fluid catalytic cracking regenerators are fast beds. Sasol engineers reported successful development of a turbulent bed for hydrocarbon synthesis (Steynberg et al., 1991). 

For some widely practiced processes, especially in the petroleum industry, reliable and convenient computerized models are available from a number of vendors or, by license, from proprietary sources. Included are reactor-regenerator of fluid catalytic cracking, hydro-treating, hydrocracking, alkylation with HF or H2SO4, reforming with Pt or Pt-Re catalysts, tubular steam cracking of hydrocarbon fractions, noncatalytic pyrolysis to ethylene, ammonia synthesis, and other processes by suppliers of catalysts. Vendors of some process simulations are listed in the CEP Software Directory (AIChE, 1994). 

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