Wet Scrubber Technology for Controlling Biomass Gasification Emissions

摘要

A lumber facility had installed a small gasifier (< 1 MW) to gasify wood chips which are a byproduct of sawmill operations. The syngas produced by the gasifier is combusted in a dual fuel internal combustion engine (ICE) to produce electricity. Waste energy from the ICE in the form of hot water is used for drying lumber in a drying kiln at the site. An electrostatic precipitator (ESP) was used to clean the syngas produced by the gasifer. Operating problems developed with the ESP which caused the system to be taken out of service.Modifications were made to the syngas cleaning system to replace the ESP with a Venturi scrubber. The Venturi operates downstream of a packed bed absorber which uses sub-cooling to condense water vapor. Sub-cooling grows the particulate to a larger size so they can be collected at higher efficiency in the Venturi scrubber. The Venturi removal efficiency for particulate matter larger than 1 micron in diameter is equal to or greater than the ESP. It is less efficient than the ESP for particles smaller than 1 micron in diameter; however, the engine can tolerate material of this size. The results of the modifications show that a Venturi scrubber system can be used to effectively control air emission from biomass gasifiers.