Gasification concept

Figure 6.5 shows the process configuration of different FB gasification concepts, from single-reactor concepts to twin fluid-bed systems. The FB gasifiers are operated in a typical temperature window of 800-950°C. Producers of such FB gasifiers (also including air... 

The use of air alone leads to a relatively low calorific value product gas, of the order of 4-6 MJ/mi (LHV basis), which is not attractive for H2 production in view of the large bulk of N2 to be separated from it compared to a preseparation from the air. Only the application of hydrogen in ammonia production would need N2 as cofeedstock. Therefore, in this context only steam- or oxygen-blown gasification concepts are dealt with. The raw product gas can, thus, be produced by an oxygen-blown or indirectly heated steam-blown processes. 

There are more than 150 companies around the world that are marketing systems based on gasification concepts. Many of these are optimized for specific wastes or particular scales of dedicated energy production operations. They vary widely in the extent to which they are proven in operation. In addition, there are more than 100 facilities operating around the world. 

What, then, does the future hold This author believes that the catalytic hydrocarbonization/gasification concept will ultimately achieve commercial success for the production of liquid and gaseous fuels from coal. In selected applications, the mild hydrocarbonization of western coal to produce liquid and gaseous fuels with power generation from the low-sulfur char may also be commercially attractive. Finally, further development of the flash hydropyrolysis technology, as exemplified by the Rocketdyne project, may eventually lead to a technically and economically attractive liquefaction process. But the most important questions still remain unanswered. Does private industry have sufficient interest to pursue the possibilities Where is the interest focused Will a private consortium build a hydrocarbonization/ cogeneration complex using western coal Will the phoenix arise from the ashes ... 

Braun, C.F., and Co., "Factored Estimates of Western Coal Commercial Gasification Concepts", ERDA Report No. FE-2240-5, October, 1976. 

Drift, A. (2002). An overview of innovative biomass gasification concepts. In "Proc. PV in Europe Conf.". WIP, Munich ETA, Florence. 

In response to the considerations of the previous section, a FZK study group has selected the two-step straw gasification concept in Fig. 5 as a good basis for the fiirther development of straw gasification [11], Only cheap straw chops are considered as feed, whereas reactor slagging by sintering ash is avoided with a two-stage concept. 

Table VII presents the estimated investments. The methanol case investment reflects the same gasifier type as used for the IBG and SNG cases. A conceptual Chem Systems methanol synthesis step is used. EPRI is sponsoring the development of the Chem Systems technology (5 ). The ammonia case investment reflects the same wood gasification concepts, employs pressure swing adsorption for hydrogen gas purification (based on information provided by the Linde Division, Union Carbide Corporation), and uses a conventional high-pressure ammonia synthesis loop.

Figure 9.1 Suggestions for advanced gasification concepts, (a) Press-feeding of fine coal into moving-bed gasifiers, (b) Internal circulation gasifier (INCI). (c) Hybrid-wall entrained-flow gasification.

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