Hot Gas Filters take out toxic emissions from gasifier and pyrolysis off-gas
Ceramic filters are probably most commonly associated with ceramic water filtration. However, in terms of hot gas ceramic filtration this works in a very different way for a different reason. Normal ceramic filters are used in large industries and factories that deal with a lot of harmful gases and very often require the release of harmful gases into the atmosphere. For this reason ceramic filtration is used to absorb some of these harmful particles before they are expelled.
The filters can operate in temperatures of up to 1000 degrees and come in various filter sizes to cater for gas flume sizes. These are high temperature devices because they ensure for continuous removal of particles from the air or gases. Filters can also contain sorbent powders which act as a dry scrubber during waste gas application. The filters are used in purpose built vessels in order to meet to a wide range of specifications.
The ceramic filtration process is seen to be used with catalytic gas treatment, dry scrubbing, incineration, pyrolosis and gasification processes. These require the process gas to be cooled and/or purified before being filtered. Every filtration process is done in chemical processes, due the effectiveness of removing particles or solids that needs to be filtered. Some of the main reasons for removing solids at high temperatures are because the gas is already at an elevated temperature and is always clean. Also the gas can contain condensable liquids or solids which need to remain in the vapour phase and once the solids have been collected there is a chance that they may change their properties if they cool down.
Ceramic filtration is also ideal for incineration processes, most commonly carcass incineration. This aids in removing acid gas from dry scrubbing with lime or sodium bicarbonate and also allows flexibility in what temperature the gases are treated. For coal gasification processes, one key issue is the effects that it has on the environment. Using a filtration system ensures that the cleaning process removes unwanted and harmful solids, through combustion gas cleaning.
Using ceramic material for filtration is ideal due to its durability and strength in extreme temperatures; these very rarely get damaged and are unaffected by sparks or by luminescent particles. Ceramic fibres are inexpensive and perform better than other rigid filtration processes. These are also ideal for thermal shock resistance and resistant to acid gasses which increase the risk of erosion. In circumstances where solids have not been efficiently removed, the outer layer of the ceramic may corrode and often cause it to be delaminated. With this comes expensive maintenance and repairs; however these occurrences are not frequent and remain uncommon. wood gasification
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Anna Stenning has researched into the ceramic filtration processes, seeing how much they benefit the environment.biomass gasification explained: large scale biomass gasification plants
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