Gasification performance of Australian lignites in a pressurized fluidized bed gasifier process development unit under air and oxygen-enriched air blown conditions

This paper discusses the gasification performance of a number of Australian lignites in a high temperature winkler (HTW) gasification process development unit (PDU) capable of running at a pressure, temperature, and feed rate of 10 bar, 1000 degrees C, and 250 kg h(-1) respectively. The fuels include three Victorian lignites, one South Australian lignite, and a char derived from a Victorian lignite. All fuels were pre-dried to less than 20% moisture content. The tests were of 3-32 h duration. The majority of the tests were conducted at 8 bar(g) pressure, 125-240 kg h(-1) feed rate, 750-920 degrees C average bed temperature, and involved steam and air or steam and oxygen-enriched air as reactants for gasification. Carbon conversion ranged between 70-87%, with further improvement limited by elutriation of carbon-rich fines originating from a large fraction of fine particles present in the feed, and brittle nature of these lignites which generate fines through attrition. An acceptable calorific value of 4 MJ kg(-1) of the fuel gas has been attained. An assessment of the reasons and the extent of loss of char through elutriation has been investigated through tests in a 1 : 1 scale cold model and characterization of the char.