Structural Properties and Gasification Reactivity of Shenmu Fly Ash Obtained From a 5t/d Circulating Fluidized Bed Gasifier

摘要

Coal gasification is one of the key technologies for the high efficiency and clean use of coal resources. Circulating fluidized bed gasification is attracting considerable interest worldwide. The advantages of circulating fluidized bed gasification are that it can use bigger particle sizes, has a wider adaptability to a range of solid fuels, can operate at moderate temperatures and therefore emit lower amounts of nitrogen and sulfur compounds. However, the lower operating temperature can also result in the problem of high content of residual carbon in fly ash. Gasification fly ash is a by-product of the coal gasification process. To achieve "zero emission" from coal gasification technology, the environmentally safe utilization of fly ash by-products from gasifiers must be addressed and development. In this study, work has been carried out to investigate the structural properties and gasification reactivity of Shenmu fly ashes, which were obtained from a 5t/d circulating fluidized bed gasifier with different operating conditions. The structural properties of fly ashes were characterized with SEM, XRD and BET study. The gasification reactivity of fly ashes with CO2 was analyzed by isothermal and non-isothermal thermogravimetric technology. A comparative investigation of fly ashes and fast pyrolyzed Shenmu char was also conducted. The results proved fly ashes to be more active than Shenmu char, which could be attributed to the lower graphitization degrees, the smaller particle sizes and higher specific surface areas of fly ashes.