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Gasification Plant

Biomasse Kraftwerk Güssing (BKG)

In Güssing an innovative process for combined heat and power production based on steam gasification has been successfully demonstrated. Biomass is gasified in a dual fluidised bed reactor. The producer gas is cooled, cleaned and used in a gas engine to produce electricity and heat. The net electricity produced is delivered to the electrical grid. The heat produced in the process is delivered to an existing district heating system and partly used internally e.g. for air preheating, steam production, etc.

Wood chips from forestry are the fuel for the plant. The wood trunks, naturally dried by storage in the forest, are delivered to the CHP-plant and chipped. The used biomass chips have a water content of about 25-40%, they are fed into the fluidised bed reactor via screw feeders.

The fluidised bed gasifier consists of two zones, a gasification zone and a combustion zone. The gasification zone is fluidised with steam which is generated by waste heat of the process, to produce a nitrogen free producer gas. The combustion zone is fluidised with air and delivers the heat for the gasification process via the circulating bed material.

The producer gas is cooled in a heat exchanger (from 850°C – 900°C to about 150°C – 180°C) and cleaned in a two stage cleaning system: Firstly a fabric filter separates the particles and some of the tar from the producer gas. These particles are recycled to the combustion zone of the gasifier. In a second stage the gas is liberated from tar in a scrubber. Used scrubber liquid, saturated with tar and condensate, is partly vaporized and fed for thermal disposal into the combustion zone of the gasifier. The temperature of the clean producer gas is reduced to about 40 °C in the scrubber. The producer gas is finally fed into a gas engine. If the gas engine is not in operation the whole amount of producer gas can be burned in a backup boiler to produce heat.

The heat of the engine’s flue gas is used to produce heat for district heating. The flue gas from the combustion zone is used for air preheating, superheating steam as well as to deliver heat to the district heating grid. The flue gas of the combustion zone passes a filter for particle separation and is released via a stack to the environment. The plant fulfils all emission requirements. There is only one solid residue which is the fly ash from the flue gas. This fly ash is fully burned out, the loss of ignition is lower than 0.5 w- %. The plant produces no condensate which has to be disposed externally.

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