Steam cracking Industrial plant

Figure 2Z0 summarizes the complete arrangements of the different units of the hot and cold sections of an industrial steam cracking plant... 

Reactions of a light gas with a liquid are almost always exothermic. Though very important in industry, endothermic reactions are exclusively gas phase reactions. It seems more economical to produce, in large scale endothermic processes (steam cracking, catalytic reforming and steam reforming), reactive intermediates from which, by exothermic reactions the wide variety of chemicals are synthetized. So, enthalpy of reaction cannot be used as a cri-terium to classify three phase industrial processes and, in the design of such plants, heat removal and temperature control are always important problems, sometimes critical ones. 

Activation in industrial plants is usually carried out by means of the feed stream of steam and hydrocarbons and sometimes with hydrogen addition at a high steam-to-carbon ratio (5—10) and at low pressure [389]. The hydrocarbons crack thermally and the resulting hydrogen or carbon acts as an initiator for the reduction process. As soon as metallic nickel is available, the steam reforming process will produce sufficient hydrogen for a quick reduction of the catalyst. 

Cracking or Thermal Decomposition. Even the phenomenon of cracking is not a modem development. Tme, the large plants and the wholesale manufacture of decomposition products are new, but thermal decomposition was actually practiced in the distillation of coal and oil shale even before the days of the oil industry. During the first years of the petroleum industry a cracking distillation, in addition to the customary distillation with steam, was practiced. The cracking distillation is reported to have been discovered accidentally in 1861. A distillation in a 16-bbl still had been half completed, and the Stillman had built a strong fire. The Stillman intended to be away an hour but was unable to return until... 

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