Applications of Coal Gasification

Figure 4.1. Applications of coal gasification. MTBE, methyl tertiary butyl ether. See color insert.

OBJECTIVE To provide current and consistent information about the technical status, commercial development, and potential utility applications of coal gasification technologies. 

APPROACH The project team conducted literature and vendor surveys to gather information on the technology, environmental performance, and utility applications of coal gasification-based systems. They compiled this information into a guidebook and published it in three-ring-binder form to facilitate timely updates as new information becomes available. (Economic analysis of specific applications and capital and operating cost estimates will be published separately.)... 

The principal objective of this coal gasification guidebook update is identical to that of the original guide to provide current and consistent information about the status of commercial development and potential utiUly applications of coal gasification technologies that are commercial or near-commercial. The updated guidebook also summarizes EPRI s extensive activities in this area. 

The primary applications for large-scale jetting fluidized beds are in the area of coal gasification as described by Yang et al. (1995), Kojima et al., (1995), and Tsuji and Uemaki (1994). Smaller scale applications are for fluidized bed coating and granulation to be discussed in Chapter 6. 

Existing physical absorption AGR processes are relatively energy inefficient for application in coal gasification they use substantial amounts of steam or stripping gas to regenerate lean solvent and power to pump lean solvent into the AGR absorber. In the treatment of crude gas with substantial carbon dioxide content, work available by expansion of separated carbon dioxide from its partial pressure in the crude gas, typically 100-300 psia, to atmospheric pressure, is not recovered. In theory, an AGR process could recover and utilize this potential energy. 

Vapors containing alkali metal species have diverse implications to high temperature processes (1 ). Potential new applications of alkalies in combustion systems include—their vapor phase catalytic action in smoke reduction (2, 3), their liquid phase catalysis of coal gasification (4), and their role as electron sources for magnetohydrodynamic (MHD) combustion systems (3). In most combustion systems, however, their presence is undesirable. This is particularly true in fossil energy systems. 

Fluidized bed reactors have received increased interest in recent years owing to their application in coal gasification. The section on fluidized beds discusses critical areas in fluid bed reactor modeling. Computer simulation of both solid-catalyzed gas phase reactions as well as gas-solid reactions are included. 

The most commonly used fuel - especially for stationary applications - is natural gas, although a variety of fuels have also been tested, such as waste biogas, landfill gas, or the products of coal gasification (after the removal of any sulfur-containing impurities that might poison the anode materials). 

The decomposition of dilute mixtures of NH3 in a PBMR using Pd-alloy membranes was studied by Collins and Way [2.322], and by Gobina et aL [2.323]. This application is of potential interest in the treatment of coal gasification streams, and the laboratory results showed promise. It would be interesting to see, whether the same membranes prove robust in the real coal-gas environment. The use of a PBMR to study the hydrodechlorination of dichloroethane was reported by Chang et al. [2.324]. The reported potential advantage of the membrane would be in preferentially removing the by-product HCl, which deactivates the catalyst. The authors attribute the observed improved performance, however, to a dilution effect. 

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