Principal objective is the definition of process parameters and operating limits for a model dry gas cleaning system, in which stable and economical particle filtration cycles as well as a reduction in content of HCI, SO2, NOx, certain volatile organic species (VOC) and certain metals in particulate form by simultaneous addition of sorbents and/or catalysts into the gas stream can be achieved. Important objectives are the use of existing rigid ceramic filter material at regeneration pressures below 10 bar and temperatures below 600 C; emission targets for particles and HCI are 10 mg/m3, for SO2 50 mg/m3 and for NOX 200 mg/m3.
A dry gas cleaning system for combined removal of particles and gaseous contaminants on the basis of VDI Guideline 3926, having a flow rate of 6 Nm3/h at max. 600 C will be designed, built and tested. It will then be used to establish filtration cycles for redispersed fly ash from biomass combustion during concomitant sorbent dosage to remove defined amounts of components. The particulate phase will be generated by dry dispersion of ashes; the gaseous components will be added by injection of defined amounts of HCI, SO2 and NOX. Particulate removal will be based on ceramic filter elements. Vapor phase removal processes will be based on absorption or adsorption technology using NaHCO3, Ca(OH)2 or activated charcoal. Additional filtration cycle data related to the influence of water vapor will be obtained on an existing filter unit using rigid ceramic candies of 1.5m length. That unit will be modified for these tests. Additional data will be obtained to characterise the particulate and gas phases. During the third project year, tests will be run with clean and contaminated biomass at up to 250 kg/h on an experimental incinerator. The previously designed and tested gas cleaning unit will be installed on a slip stream downstream of the incinerator to evaluated the significance of earlier obtained process parameters. Particle and gas phase as well as biomass and ash composition will be fully characterized by supporting lab data.
EXPECTED ACHIEVEMENTS AND EXPLOITATION
The data obtained will serve the definition of a reliable low energy demand process for combined dry removal of dust and certain vapor species from biomass combustion off-gas. It is expected that such a process-will run on the basis of existing filtration hardware with only minor additional investments to the filter unit for addition of chemicals. The process data will offer engineering firms the possibility of retrofitting existing gas cleaning systems.
Funding SchemeCSC - Cost-sharing contracts