ALPHA filter systems protect gas engines

Energy from wood and other biomass products is converted into electricity and heat with high efficiency ratings in CHP plants by means of thermochemical gasification using gas engines and gas turbines.

The first purification stage for the process gas downstream from the gasifier is dust extraction.The filter system is operated with gas temperatures in excess of 280°C in order to prevent condensation of the long-chain hydrocarbons.The illustration shows a typical wood gasification plant.The Herding ALPHA filter is a surface-coated candle filter whose the inorganic base materials permit operating temperatures of up to 450°C.Compared to the conventional wet filters used to date, this eliminates problems with waste water, and with a residual dust content of 2 mg/m³ it ensures that the required gas quality is achieved.The surface of the filter is given additional protection by a precoating system which applies an auxiliary filter layer.This ensures that condensate (wood tar), which cannot be completely avoided especially during starting up operations, is intercepted and bonded.As a result, downstream gas purification stages can be run without any significant dust loads.The plants can thus be operated with dry gas conditioning and cooling, which makes plant construction simpler, ensures troublefree engine operation, reduces costs for the owner-user and increases availability.The filter housings can be supplied as gas-tight or pressure vessel versions in a range of different materials.The filter elements (clusters) are installed on the clean gas side, which saves space and results in an installation-friendly design.