The demand on chemicals such as ammonia, urea, methanol etc. is continuously increasing worldwide; however, the pressure on the production costs leads to both: (i) looking for more efficient units and technologies, and (ii) looking for alternative resources. Recently natural gas (NG), being the main source for production of chemicals, became extremely expensive or sometimes even not available in some regions in Asia-Pacific. As a result, the chemicals produced on NG basis became non-affordable. Therefore, the use of new and cheaper sources such as low grade local coals could be an alternative not only to save, but also to provide a long-term, sustainable perspective for the whole sector. This issue became extremely topical in countries having huge reserves of low rank coals, such as Indonesia and India.
Gasification is a process of thermal conversion of solid carbonaceous materials into a gaseous fuel called syngas. Coal gasification is an efficient technology for a range of sustainable systems for producing low emissions electricity and other high value products such as chemicals, synthetic fuels etc.
The paper presents the High Temperature Winkler (HTW) gasification process which is specially designed for utilization of low rank feedstock such as coals with high ash content, devolatilisation and partial oxidation of coal char and volatiles take place and by (ii) a free board, where the gasification reactions occur. This process has been used for decades for
industrial production of chemicals.
The recent development of the high pressure HTW process will be reviewed. Further, gasification of low rank coals such as Indonesian coals with respect to gasification temperatures, conversion rates and syngas quality will be discussed. The main HTW design steps required for an industrial scale design are presented. Special attention will be given to
accumulated experience in gasifying low rank coals and subsequent industrial production of chemicals.
Paper presented at International Conference Asian Nitrogen and Syngas, Jakarta, 2014 (pdf)