Coking process developments

Delayed Coking", is a semi-continuous process, developed at the end of the 1930 s. The reaction is conducted at 450-500°C under relatively low pressure, four atmospheres, maximum. 

An important raw material used in the manufacture of steel is coke, a nearly pure form of carbon. To supply themselves with coke, steelmakers developed the process of destructive distillation of coal. 

Waterloo Centre for Process Development. A Plastofrost study of Western Canadian coking coals. Final Report prepared for the Canada Department of Supply and Services and the Canada Department of Energy, Mines and Resources, Ottawa, Canada, 1989. 

We found the latter factor-voids to be important. Experimental results showed that when green coke was calcined under the new methods, and the derived calcined coke was observed by scanning electron microscopy (Figure 2) and its pore size distribution was measured by mercury porosimetry (Figure 3), microcracks of significant sizes (1 to 60 microns) were developed. This was an important contribution to the reduction of the thermal expansion coefficients of the calcined coke processed under the new method. 

Table V shows the X-ray parameters obtained from the cokes by two different calcining methods. X-ray diffractometry of interlayer spacing (doo2) and apparent crystalline size (Lc) indicated no particular difference between cokes processed under the two methods. Furthermore, no specific differences were found on these samples after graphitization, These facts show that the new calcining method would not lead to adverse effects on the development and rearrangement of coke crystallines.

Meta-4 A process for converting ethylene and 2-butene into propylene by metathesis. The process operates in the liquid phase at low temperatures in the presence of heterogeneous catalyst based on rhenium oxide on alumina. The catalyst is constantly regenerated by coke combustion. Developed by IFP and the Chinese Petroleum Corporation of Taiwan. A demonstration plant was operated from 1988 to 1990 and the process was demonstrated at Kaohsiung, Taiwan, in 1999. Now offered by Axens. 

D. L. Trimm in Fundamental Aspects of the Formation and Gasification of Coke in L. F. Albright, B. L. Crynes, W. H. Corcoran (eds.), Pyrolysis Theory and Industrial Practice , Academic Press, New York, 1983 L. F. Albright, B. L. Crynes, W. H. Corcoran (eds.), Pyrolysis Theory and Industrial Practice , Academic Press, New York, 1983 T. J. Ford, Ind. Eng. Chem. Fundam., 25, 240, 1986 Coastal Isobutane Cracking Process developed by Foster Wheeler P. B. Venuto and E. T. Habib, Fluid Catalytic Cracking with Zeolite Catalysts , Marcel Dekker, New York, 1979... 

SAPO-34 has a high activity for the MTO reaction, but unfortunately there is fast deactivation caused by coke formation (79-81). Thus, detailed knowledge of the kinetics (82) and mechanism of the reaction (83-85) is important and necessary for process development. The MTO reaction serves as a case study illustrating the use of TEOM for measurement of mass changes during reactions with fast deactivation. The following problems were addressed by means of this technique ... 

Tower-still coking. For many years, coking was carried out as a batch process in which reduced crude (or other heavy oil) was heated by direct fire in horizontal vessels. Because they were equipped with condenser towers, these coke stills were known as tower stills. The charge was heated until all the volatile products had been driven overhead. The layer of red-hot coke remaining in the still was allowed to cool and was then removed manually by laborers who entered the still. More-economical coking processes were later developed that operate on a continuous basis. 

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