Pressure industrial gasification processes operated

If coal is intended to serve as fuel for industrial gasification processes, it is smart to borrow know-how for coal characterization from combustion research because of its long and comprehensive history. Hence, well-known analysis methods and classification schemes will appear, which must be always reviewed in the light of gasification conditions that differ from combustion in terms of oxidant (oxygen and steam instead of air), operation pressure (20-100 bar), and overall reducing atmospheres (products are CO and H2 instead of CO2, H2O). 

If not denoted as an atmospheric or high-pressure process, all industrial gasification technologies operate between 26 and 65 bar. That is the range required by IGCC applications (gas turbine inlet pressure) and various chemical syntheses as described previously. 

All the industrial processes are autothermal, 30 to 40% of the coal utilized being burnt to attain the required high reaction temperatures. This is also the case for the Lurgi pressure gasification process carried out in a mechanically agitated solid bed at ca. 1200°C (as used e.g. in Sasolburg in South Africa), for the Koppers-Totzek process in which the coal is used in the form of flyash (atmospheric pressure, 1400 to 1600°C) and for the Winkler process operating with a pressureless fluidized bed at 800 to 1100°C. 

Conventional acid gas removal processes produce purified coal gas and a concentrated acid gas. The H2S and COS in this low-pressure acid gas stream convert easily and efficiently to high-value liquid elemental sulfur. Sulfur recovery processes are commercially well-proven technologies that the oil, chemical, and natural gas industries have used extensively for over 50 years. In fact, U.S. oil refineries have been required to operate their sulfur plants with over 99.8% sulfur recovery for many years. The conversion of H2S to sulfur in coal gasification processes has a number of technical and economic advantages over sulfur recovery from SOj in direct coal combustion processes. 

During the 1980s, C.E. cooperated with Mitsubishi Heavy Industries (MHI) on the development of the Japanese IGC coal gasification process. The key difference between the original C.E. gasification development and the Japanese IGC process is pressurized operation in the Japanese design. As discussed above, the Japanese are currently operating a 200 t/d pilot plant unit. 

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