Pyrolysis of western canadian coals in a spouted bed

Abstract

Coal pyrolysis has been studied to determine conditions for maximum liquid yields from some Western Canadian coals. Gas, tar and char yields were determined for four coals in a 12.8 cm dia. reactor. A characteristic temperature for maximum tar yield existed for each coal at a fixed feed rate and particle size. A steady increase in tar yield was found as the average coal particle size was reduced from 2.28 to 0.65 mm. Composition of gas, and ultimate analyses of tar and char are presented as a function of operating temperature. A simple first‐order devolatilization model adequately describes the effects of coal feed rate, reaction time, and temperature on the yield of volatiles, but is insufficient to describe particle size effects.

Gas composition and temperature profiles in a spouted bed coal gasifier

“…As well the volatile content of this Balmer coal is about one-half that of the lower rank coal. Since the pyrolysis yields of C02 and CO were shown to be negligible for this coal (Jarallah and Watkinson, 1985), pyrolysis per se is thought to be less important in determining overall gas compositions than for the sub-bituminous coal. While the shapes are basically similar to those of Figure 9, there are some significant differences.…”

“…The methane content is low and essentially constant. Since the pyrolysis yields of C02 and CO were shown to be negligible for this coal (Jarallah and Watkinson, 1985), pyrolysis per se is thought to be less important in determining overall gas compositions than for the sub-bituminous coal.…”

“…Figure 4 shows typical axial composition profiles in air gasification of Forestburg coal measured at three radial positions. Jarallah and Watkinson, 1985 showed that a yield of 15 wt.% COz w/w MAF coal could be obtained by pyrolysing Forestburg coal at 600°C. The decrease in oxygen is accompanied by a significant increase in carbon dioxide; whether any carbon monoxide is produced by combustion could not be ascertained.…”

“…Evidence suggests that the fresh feed coal which enters the annulus from the fountain is still in the initial stages of pyrolysis, and thus both pyrolysis and gasification reactions occur in the upper section of the annulus. Jarallah and Watkinson, 1985 showed that a yield of 15 wt.% COz w/w MAF coal could be obtained by pyrolysing Forestburg coal at 600°C.…”

Pyrolysis with partial combustion of oil shale fines in a spouted bed

“…of British Columbia Chemical Engineering Department by Foong et al (1980Foong et al ( , 1981, Jarallah and Watkinson (1985), Wu (1986), Zhao (1986) and Tam (1986), all of them considering the application of spouted beds in high temperature processes.…”