TASK 1: Indirect gasification and gas filtration
Filtration is typically one of the first gas cleanup steps in gasification
concepts. In air or oxygen-blown biomass gasification concepts the optimal
filtration temperature is in the range of 400-550 °C. At higher temperatures
the tar-laden gasification gas forms a sticky, coke and soot containing cake
on the filter surface which ultimately results in filter blinding.
To avoid filter blinding issues, the gasification gas must be cooled down
before filtration and reheated before reforming which reduces the process
efficiency (Figure 1). In an improved process concept the filter unit would
operate at the same temperature level (at appr. 750 °C) as the gasifier and
the reformer when also heat exchanger investments could be avoided.
In this project, the hot gas filtration will be studied and developed for the
indirect gasification with emphasis on the research related to filter blinding
phenomenon. Experimental work will be carried out with a bench-scale
pressurised hot gas filtration unit (ALMA) which was successfully tested in
the UCGFunda project in 2010.
The main objective is to study which process conditions favour filter blinding
and how it can be prevented at higher temperatures. Test runs will be carried
out with a gas composition typical for indirect steam gasification both at
atmospheric and elevated pressures. The main variables to be studied are as
• Filtration temperature
• Particulate (fly ash)
concentration in the gasification gas
• Tar concentration in the
• Introduction of different sorbents and additives.