Gasification of low-rank coal in the High-Temperature Winkler (HTW) process
D Toporov, R Abraham
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 systems for producing low-emission electricity
and other high-value products such as chemicals, synthetic fuels, etc.
The paper presents the High-Temperature Winkler (HTW) gasification
process, which is designed to utilize low-rank feedstock such as coals with
high ash content, lignite, biomass etc. The process is characterized by a
bubbling fluidized bed, where coal devolatilization and partial oxidation
and gasification of coal char and volatiles take place, and by a freeboard
where partial combustion and gasification of coal char take place.
The recent development of the high-pressure HTW process is reviewed.
Gasification of low-rank, high-ash coals with respect to gasification
temperatures, conversion rates, and syngas quality is also discussed. The
main HTW design steps required for an industrial-scale design are
presented. Special attention is given to the process modelling, including
global thermodynamic calculation as well as detailed CFD-based
simulation of a reacting fluidized bed. Three-dimensional numerical results
of the HTW process are also provided and discussed.
Keywords: coal gasification, high-temperature Winkler process, HTW, reacting
fluidized bed simulation, high-ash coal, low-rank coal, biomass, peat,
municipal solid waste.