Gasification of a bituminous coal in 15MWth KEDA®circulating fluidized-bed gasifier with high-temperature preheating

Abstract

The industrial-scale high-temperature preheating air-blown KEDA®circulating fluidized-bed (KEDA®CFB) gasification process has been developed by KEDA(ANHUI) Clean Energy Co., Ltd. to produce industrial fuel gas. This paper presents the design and the first operational results of a 15MWth industrial-scale demonstration KEDA®CFB plant where about 3.6 tons bituminous coal was gasified per hour. The influences of the steam to coal ratio (SC), the equivalence ratio (ER), and the oxygen concentration (OC) on gas composition, gas high heating value (HHV), carbon conversion efficiency (CCE), and cold gas efficiency (CGE) were investigated systematically. It is shown that increasing SC from 0.18 to 0.38 favors the water–gas reaction and CO–shift reaction that causes H2 and CO2 content in the raw gas to rise. As ER increases to 0.27, it is conducive to the partial combustion and Boudouard reactions of char, and the HHV and CGE of gas products are 6.38 MJ/Nm3 and 66.8%, respectively. As OC increased from 21 vol% to 27 vol%, the CCE increased from 71.8% to 79.8% mainly due to the increase of gasification reaction rate and residence time. The operational results in this work can significantly contribute to the design and operation of industrial-scale gasifiers, and the development of numerical models.