Coal gasification atmosphere

Norton, J. F. (ed). High Temperature Materials Corrosion in Coal Gasification Atmospheres, Applied Science Publishers, London (1984)... 

Long-term exposure of selected high temperature alloys at 932°C in a coal gasification atmosphere containing O-S ) H2S (after Hill and Meyer )... 

Fig. 7.76 Superimposed simplified thermodynamic stability diagrams for three elements with oxygen and sulphur at 871°C. The shaded rectangle indicates possible activity ranges in coal gasification atmospheres (after Stringer )...

Figure 2-4. Stability diagram for different metals, oxides and carbides at 950 °C. The hatched area characterizes the composition of a coal gasification atmosphere is the carbon activity (Schendler, 1983).

Figure 2-19. Internal carburization around a crevice in Alloy 800H after 167 h at 800 °C in a coal gasification atmosphere (Schiitze and Rahmel, 1983).

Instrumentation is rapidly becoming more electronic. However, many users prefer pneumatic, and computer compatibility is available with either although electronic interface with computers is generally preferred. One coal gasification company prefers pneumatic because they feel the inherent corrosive atmosphere around such plants is not kind to electronic equipment. 

In Fig. 7.68 the oxidising and sulphiding potentials of four different atmospheric environments, i.e. conventional coal combustion (A), fluidised bed combustion (B), conventional coal gasification (C) and coal gasification using nuclear heat (D), are shown on the thermochemical phase stability... 

Cu will be unaffected by the atmosphere, whilst at other atmospheric compositions the pure oxides will be stable. Figure 7.76 illustrates a simplified diagram at 871°C for three metallic elements Cr/Mn/Ni-S-O in a heat-resisting alloy the range for coal gasification is also included. It is clear that CrjOj is stable in all these atmospheres, but NiS will be stable under these atmospheric conditions above 620°C in the form of a eutectic liquid with Ni. Thus, an alloy of Cr and Ni may produce either of these phases or their mixtures leading to corrosion problems. 

Stoic Also called Foster Wheeler-Stoic and FW-Stoic. A two-stage, nonslagging coal gasification process, operated under atmospheric pressure and using air as the oxidant. Initially developed by Stoic Combustion Limited Pty, South Africa licensed and further developed by Foster Wheeler Corporation, United States. First used in South Africa in 1950 now widely used in Europe, the United States, and South Africa. 

Wellman A coal gasification process, widely used since its introduction in the 1950s. Air and steam, at atmospheric pressure, are passed through a fixed bed of coal supported on a rotating ash bed. See also Riley-Morgan. 

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. 

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