Coal gasification fluidized bed

C02 Acceptor A fluidized bed coal gasification process in which the heat is provided by the exothermic reaction of carbon dioxide with calcium oxide. Developed by the Conoco Coal Development Company in the 1970s. 

Computer Modeling of Fluidized Bed Coal Gasification Reactors... 

A computer model has been developed to provide numerical simulations of fluidized bed coal gasification reactors and to yield detailed descriptions, in space and time, of the coupled chemistry, particle dynamics and gas flows within the reactor vessels. Time histories and spatial distributions of the important process variables are explicitly described by the model. With this simulation one is able to predict the formation and rise of gas bubbles, the transient and quasi-steady temperature and gas composition, and the conversion of carbon throughout the reactor. 

Wang, X., Jin, B., Zhong, W. (2009). Three-dimensional simulation of fluidized bed coal gasification. Chemical Engineering and Processing, 48, 695—705. 

Figure 1 Fluidized bed, coal gasification schemes nearing demonstration.

High-Temperature Winkler Fluidized-Bed Coal Gasification Process. 2-16... 

Some fluidized-bed coal gasification development is taking place outside the United States. Even gasification systems originally developed in the United States (such as U-Gas and Westinghouse/KRW) are now continuing to be developed abroad. 

Xie J, Zhong WQ, Jin BS, Shao YJ, Huang YJ Eulerian—Lagrangian method for three-dimensional simulation of fluidized bed coal gasification, Adv Powder Technol 24 382-392, 2013. 

The computer model is based upon a continuum description of fluidization in coal gasification reactors. In general, fluidized flows are dominated by specific physicochemical processes and, hence, require particular theoretical representations. For example, in the heavily loaded gas-particle regime appropriate to fluidization, the solid particles dominate the transport of momentum and energy. This aspect of fluidization is reflected in the mathematical descriptions which have been used in the fluidized bed model. 

The chemistry component of the model is, in most aspects, identical to the chemistry of the classical models of fluidized bed gasification. A major difference between the classical reactor models and the present fluidized bed coal gasifier computer model is that the classical models require specification of the bed hydrodynamics, such as bubble size. The present model can predict bubble size and the associated solids mixing. Again it is expected that the two types of models are complimentary. The present model can be used to define the hydrodynamics in the hot reactive environment and these hydrodynamics (e.g., bubble size) can then be used as... 

Coal gasification, fluidized-bed coal combustion, waste incineration Separation of metal dust, fiu-idized-bed coal combustion, waste incineration Catalyst recovery, coal-fired boilers, metal smelting, soot filtration Applications up to 1500 C Coal gasification, fluidized-bed coal combustion, waste incineration, soot filtration... 

Williams, A., et al. Combustion and Gasification of Coal New brk Taylor Sc Francis, 2000. Provides an overview of coal combustion and gasification with special attention to the properties of coal, combustion mechanism of coal, combustion in fluidized beds, the gasification process, industrial applications, and environmental impact. 

The current DOE CCT projects which may be built include KRW and Tampella/U-Gas coal gasification systems (64). These two similar agglomerating fluidized-bed co gasification processes are being considered for IGCC application based on air-blown operation and advanced hot gas clean-up. 

Most of the fluidized bed coal combustion and gasification models ignore freeboard reactions of volatiles and char For shallow beds, volatiles bum predominantly in the freeboard In addition the char particles splashing from the bed surface can also react with the oxygen in the freeboard Yates and Rowe (ll8) have proposed a model for the reactions occurring in the freeboard Such an approach can be adopted for modelling the freeboard reactions in the FBC ... 

The means by which synthetic gaseous fuels could be produced from a variety of biomass sources are variable and many of the known gasification technologies can be appHed to the problem (70,71,76—82). For example, the Lurgi circulatory fluidized-bed gasifier is available for the production of gaseous products from biomass feedstocks as well as from coal (83,84). 

New furnace concepts in evolutionary stages include fluidized-bed furnaces (25), coal gasification furnaces (26), and MHD furnaces (27,28). Of these technologies, fluidized-bed combustion has reached commercial-scale operations (Fig. 11). 

The description given apphes to DR processes that are based on the use of gaseous reductants ia shaft furnaces, batch retorts, and fluidized beds. In the processes that use sohd reductants, eg, coal (qv), the reduction is accomphshed to a minor extent first by volatiles and reduciag gases that are released as the coal is heated and then by CO that is formed by gasification of fixed carbon contained ia the coal char with CO2. Reductioa by sohd carboa and coal volatiles ia kilns is insignificant. 

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