Investigation into the gasification characteristics of SA power station coals

Abstract

Electricity demand in South Africa is increasing at a rate of 1000 MW per year. Whilst there is increasing pressure to adopt non-fossil fuel electricity generating technologies, the abundant reserves and low cost of coal makes it the preferred energy source to meet increasing electricity demand for the foreseeable future. The challenge in the future is to enhance both the efficiency and environmental acceptability of coal use by adopting clean coal technologies (CCTs). Integrated gasification combined cycle (IGCC) is a potential CCT that could be applied in South Africa to increase efficiency and reduce carbon dioxide emissions. IGCC also holds the advantage of reduced water consumption and the potential for co-production of liquid and gaseous fuels and chemicals. Fine coal gasification is a key enabling technology for the implementation of IGCC plants. Fluidised bed gasification is being evaluated by the CSIR as a potential fine coal gasification process for incorporation into future IGCC plants. A suite of four South African coals has been identified as being possible fuels for power stations which would operate for three or four decades, towards the middle of this century. This paper presents the results of coal characterisation, thermogravimetric analysis (TGA) and pilot plant gasification tests to ascertain the performance of the selected coals under fluidised bed gasification conditions. Based on the experimental results a model is being developed for the fluidised bed coal gasification process. The use of the model to predict the performance of fluidised bed gasifiers is also described in the paper