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|Title:||Pressure effects on steam pyrolysis of coal|
|Source:||Abichandani, J.S.,Deradourian, C.,Gannon, R.E.,Stickler, D.B.,Woodroffe, J.A.,Neoh, K.G. (1988-04). Pressure effects on steam pyrolysis of coal. Fuel Processing Technology 18 (2) : 133-146. ScholarBank@NUS Repository.|
|Abstract:||Volatiles produced when pulverized coal is subject to very rapid temperature rise (∼ 105Ks-1) can be twice as great as indicated by ASTM methods. The volatiles are released in a matter of milliseconds and, if allowed to react with background steam over tens of milliseconds, they reach an equilibrium condition with the products consisting primarily of carbon monoxide, carbon dioxide, hydrogen, and water. Rapid pyrolysis reactions will likely find application in indirect processes. Such processes (e.g., the synthesis of methanol from syngas) generally operate at pressures of 30 to 35 atmospheres, and it is recognized that operation of the gasification section of the plant at elevated pressures would save downstream compression costs. High-heating-rate, high-temperature (1600-2400 K) devolatilization experiments are carried out in a 10 liter batch reactor which serves to pyrolyze a suspension of pulverized coal in a mixture of steam and nitrogen. The high heating rate of coal particles is achieved by igniting a stoichiometric mixture of hydrogen and oxygen in nitrogen diluent. A rapid quench sampling system, designed to accept gas and particle sample from the reactor interior for a short interval (∼4 ms), at a prescribed time after initiation of reaction, is used to obtain transient reaction data. At 2400 K, steam to carbon molar ratio of 2 and reaction times greater than 100 ms, an increase in pressure from 4 bar to 45 bar is found to have a small positive effect on the coal carbon conversion. The yields of carbon monoxide and hydrogen increase correspondingly. The carbon dioxide yield is independent of pressure. From economic considerations these results are of direct importance as an increase in pressure increases the yields of desirable products (carbon monoxide and hydrogen), without affecting the yield of the undesirable product (carbon dioxide). © 1988.|
|Source Title:||Fuel Processing Technology|
|Appears in Collections:||Staff Publications|
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