Gasification behaviour of Australian coals at high temperature and pressure

Abstract

This paper presents gasification conversion data generated for a suite of Australian coals reacting with oxygen/nitrogen mixtures at 2.0 MPa pressure and at temperatures up to 1773 K, as part of a wider investigation into the gasification behaviour of Australian coals. The effects of O:C ratio, residence time and coal type on conversion levels and product gas composition were investigated under conditions relevant to those present in entrained-flow gasification systems. At higher temperatures, coal conversion levels are, as expected, higher, whilst product gas compositions continue to reflect the relevant gas phase equilibrium conditions. These gas phase equilibrium concentrations show strong dependence on the amount of carbon in the gas phase (i.e. coal conversion). The increased conversion achieved at high temperatures allows the contribution of coal-specific properties such as char structure and reactivity to be investigated in more detail than previously possible. Furthermore, at higher conversion levels the effects of coal type on product gas composition are more apparent than at lower conversion levels. These high temperature, high pressure gasification conversion data have been reconciled with high pressure bench-scale pyrolysis and char reactivity measurements, highlighting the significance of coal-specific effects of key gasification parameters.