Classifying Gasification Methods

There are many methods for the desulfurization of nature gas, which can be classified into dry desulfurization, wet desulfurization, and catalytic adsorption. In the dry desulfurization, some solid sorbents, such as iron oxide, zinc oxide, activated carbon (AC), zeolites, and molecular sieves, are used. In wet desulfurization method, liquid-phase chemical/physical solvent absorption systems are usually used for scrubbing H2S amine-based processes are subject to equipment corrosion, foaming, amine-solution degradation, and evaporation, and require extensive wastewater treatment. As a result, this sulfur removal technology is complex and capital intensive,44 although the processes are still employed widely in the industry. The desulfurization of coal gasification gas will be reviewed in detail in Section 5.5. In the catalytic-adsorption method, the sulfur compounds are transformed into H2S by catalytic HDS or into elemental sulfur or SOx by selective catalytic oxidation (SCO), and then, the reformed H2S and SOx are removed by the subsequent adsorption. 

Five main methods of feedstock recycling have been considered in this book, classified according to the degradation conditions and the products obtained chemical depolymerization, gasification, thermal treatments, catalytic cracking and reforming, and hydrogenation. 

According to their mechanical technology, i.e. to the method of feeding the coal to the gasifier and to its behaviour in it, coal gasification processes may be classified into... 

Q>al gasification processes for ammonia production can be classified according to the method of gasification as fixed-bed G-urgi), fluidized bed (Winkler), or entrained bed (Koppers-Totzek and Texaco). Tne so-called fixed bed ga cation is more accurately called a moving bed. Lump coal (5-30 mm) is charged at the top arxi descends countercurrently to the gas stream. As it descends, it is first dried and preheated, then carbonized, and fi-... 

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