Jinichi Tomuro

Characteristics of air-blown gasification in an entrained-bed coal gasifier.

The characteristics of air-blown coal gasification has been studied in a process development unit of an entrained-bed gasifier. Taiheiyo and Ermelo coals were used in this work. Comparing the experimental results obtained in the two-stage gasification method, it was confirmed that there is an appropriateair distribution ratio in the two-stage method which results in the reduction of the difference in the carbon conversions of Taiheiyo and Ermelo coals. Carbon conversion shows a linear relationship with the ratio of total supplied oxygen to the carbon contents in the coals.The ratio of the experimental value, ηg (cold gas efficiency), to the theoretical value, η*g was introduced as a performance index of the gasifier. On the basis of a slag flow temperature comparison, it was concluded that only a small difference existed in the performance indexes of the air-blown and the oxygen-blown gasifications in this gasifier.

Development of fluidized bed heat exchanger for hot gas containing tar. Effects of operating temperature and bed height on tar capture.

Tar coking might lead a serious trouble in the coal gasification plant, especially when the gasification temperatures are relatively low. Fluidized-ed heat exchanger has a good potential not only to prevent such a coking trouble but to recover heat from a hot gas leaving the gasifier. In this parer, effects of bed temperature and bed height on tar capture were investigated using an apparatus with 0.208m in diameter and 1.4m in height. The amount of accumulated coke on solid in fluidized-bed heat exchanger did not very significantly at temperatures ranging 392 to 554 t . However, at a temperature as low as 427 t, condensed tar did not decompose rapidly and a small amount of liquid tar was expected to appear on the fluidized solids, resulting agglomeration and unstable operation of the fluidized-bed heat exchanger.At temperatures of 447°C or higher, fluidzed-bed heat exchanger could be operated steadily without agglomeration of the solids. The bed height of the fluidized-bed heat exchanger affected strongly the amount of tar removed through the bed.