Coal gasification products

Typical compositions for several oxygen-blown coal gasification products are shown in Table 9-4. 

Coal gasification production of synthetic gas from coal. 

Sasol (Suid-Afrikaans Sintetiese Olie) in South Africa has one of the largest coal gasification production operations in the world with the three plants.1 One plant produces only chemicals and the other plants produce both liquid fuels and chemical feedstocks from coal. In 1994, Sasol s total ammonia capacity was over 500,000 tons per year.54... 

This principle can be, and has been, applied to hi temperature gas mixtures. Specifically, the removal of H,S from fuel gas streams (natural gas and coal gasification product streams). Since the membrane is exposed to the same pressure on both sides, there is no theoretical limit to the pressure at which the process operates. Also, since there is no reaction or absorption equilibrium, there is no theoretical limit to removal. 

Molten carbonate fuel cells can use hydrogen, carbon monoxide, natural gas, propane, landfill gas, marine diesel, and coal gasification products as the fuel. MCFCs producing 10 kW to 2 MW MCFCs have been tested with a variety of fuels and are primarily targeted to electric utility applications. MCFCs for stationary applications have been successfully demonstrated in several locations throughout the world. 

Figure 13-18. Flow diagram for the production of synthesis gas for methanol or synthetic natural gas (SNG) from coal gasification product gas. Udengaardand Berzins, 1985. Reproduced with permission from Acid and Sour Gas Treating Processes, edited by S. A. Newman, copyright 1985, Gulf Publishing Company...

Ammonia from coal gasification has been used for fertilizer production at Sasol since the beginning of operations in 1955. In 1964 a dedicated coal-based ammonia synthesis plant was brought on stream. This plant has now been deactivated, and is being replaced with a new faciUty with three times the production capacity. Nitric acid is produced by oxidation and is converted with additional ammonia into ammonium nitrate fertilizers. The products are marketed either as a Hquid or in a soHd form known as Limestone Ammonium Nitrate. Also, two types of explosives are produced from ammonium nitrate. The first is a mixture of fuel oil and porous ammonium nitrate granules. The second type is produced by emulsifying small droplets of ammonium nitrate solution in oil. 

In 1984, the Ube Ammonia Industry Co. began operating the largest Texaco coal gasification complex to date. This faciUty is located in Ube City, Japan, and has a rated gasification capacity of 1500 t/day of coal, and production capacity of 1000 t/day of ammonia. The plant has successfully gasified coals from Canada, AustraUa, South Africa, and China. At the present time the plant uses a mixture of petroleum coke and coal (43). 

The importance of coal gasification as a means of produciag fuel gas(es) for iadustrial use caimot be underplayed. But coal gasification systems also have undesirable features. A range of undesirable products are also produced which must be removed before the products are used to provide fuel and/or to generate electric power (see Power generation) (22,41). 

Chemistry. Coal gasification iavolves the thermal decomposition of coal and the reaction of the carbon ia the coal, and other pyrolysis products with oxygen, water, and hydrogen to produce fuel gases such as methane by internal hydrogen shifts... 

Coal gasification technology dates to the early nineteenth century but has been largely replaced by natural gas and oil. A more hydrogen-rich synthesis gas is produced at a lower capital investment. Steam reforming of natural gas is appHed widely on an iadustrial scale (9,10) and ia particular for the production of hydrogen (qv). 

Methanol, a clean burning fuel relative to conventional industrial fuels other than natural gas, can be used advantageously in stationary turbines and boilers because of its low flame luminosity and combustion temperature. Low NO emissions and virtually no sulfur or particulate emissions have been observed (83). Methanol is also considered for dual fuel (methanol plus oil or natural gas) combustion power boilers (84) as well as to fuel gas turbines in combined methanol / electric power production plants using coal gasification (85) (see Power generation). 

B. K. Schmid and D. M. Jackson, "The SRC-11 Process," paper presented at Third Annual International Conference on Coal Gasification and Eiquefaction. University of Pittsburgh, Aug. 3—5, 1976 D. M. Jackson and B. K. Schmid, "Production of Distillate Fuels by SRC-11," paper presented at ACS Div. of Ind. and Eng. Chem. Symposium, Colorado Spriags, Col., Feb. 12,1979. 

This process is one of the three commercially practiced processes for the production of acetic anhydride. The other two are the oxidation of acetaldehyde [75-07-0] and the carbonylation of methyl acetate [79-20-9] in the presence of a rhodium catalyst (coal gasification technology, Halcon process) (77). The latter process was put into operation by Tennessee Eastman in 1983. In the United States the total acetic anhydride production has been reported to be in the order of 1000 metric tons. 

For central station power generation the open cycle system using electrically conducting coal combustion products as the working fluid is employed. The fuel typically is pulverized coal burned directly in the MHD combustor, although in some plant designs cleaner fuels made from coal by gasification or by beneficiation have been considered (8—10) (see Fuels, synthetic). 

The high cost of coal handling and preparation and treatment of effluents, compounded by continuing low prices for cmde oil and natural gas, has precluded significant exploitation of coal as a feedstock for methanol. A small amount of methanol is made from coal in South Africa for local strategic reasons. Tennessee Eastman operates a 195,000-t/yr methanol plant in Tennessee based on the Texaco coal gasification process to make the methyl acetate intermediate for acetic anhydride production (15). 

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