Gasification Performance of Australian Lignites in a Pressurized Fluidized Bed Gasifier Process Development Unit Under Air and Oxygen-enriched Air Blown Conditions

Abstract

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°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°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.