Determination of pneumatic transport capabilities of dry pulverised coal suitable for entrained flow processes

The use of pulverised coal in integrated gasification combined cycle (IGCC) power plant is currently under development. The results of a project to determine the suitability of Chinese coals for dry feed to the entrained flow gasifier that forms part of the above cycle are presented. This paper also includes some basic material characterisation of the pulverised coal.Pneumatic conveying test rigs were used in conjunction with a mathematical model to generate conveying characteristics for coal at high back pressures. The overall strategy was to test both coal and surrogate at atmospheric back pressure to compare the two materials' performance, under similar conveying conditions; and to test the surrogate material at elevated back pressure, and use this data to validate a mathematical model. The similarity of behaviours of the two materials then allowed the model to be applied to the data measured for coal and so generate conveying characteristics at conditions typical of entrained flow.The mathematical model used to scale the results to high back pressures, which characterise entrained flow processes, is based on the assumption that the influence of the pressure drop due to solids is independent of the back pressure, in the range of conditions considered. Conveying characteristics were generated at a variety of back pressures ranging from 1 to 25 bar. A brief analysis of the minimum conveying velocity is also presented.