Donaldson Membranes teamed up with German filter bag manufacturer, Fasse Industrietextilien GmbH, to improve filter element life and reduce environmental emission levels at a biomass power plant in eastern Germany.
The Power Plant
The power plant is a pure electricity plant, originally built as a sugar factory, fuelled by brown coal, which has been reconfigured as a biomass incineration plant, with all existing equipment being updated, renewed or extended. The plant utilises biomass in the form of old growth products and recycled wood as fuel to generate electricity to supply the surrounding area.
Biomass used for heat and power generation accounts for nearly 5% of Germany’s primary energy source. In 2007 biomass accounted for 93% of the heat supplied from renewable energies. As with this plant, the wood used is exclusively for energy production through combustion, and comprises low-grade wood varieties from forests, fast-growing species plantations, remnants from the wood-processing industry and scrap wood.
The plant combines these different classes of wood, to ensure that the fuel that enters the incinerator has an even calorific content to ensure a continuous energy output.
The biomass fuel, at a rate of 30 tonnes per hour, is incinerated on a continuously moving metal grate at 1000-1200oC, producing 450oC steam which powers a maximum of 3 generators producing electricity at an average rate of 14 MW/h.
The flue gas that is generated passes via a mechanical pre-separator to a fabric filter baghouse comprising seven compartments of filter bags.
The original filter bags installed were running ineffectively with a cloud of black smoke visible above the plant’s exhaust stack and the plant came under increasing pressure from the German government to implement an environmental control system and to reduce their particulate emission levels below the regulation 20m3/h.
Fasse Industrietextilien GmbH were drafted in to help combat a problem the plant was experiencing with the baghouse filter, the differential pressure was too high and the ventilation system was continuously working at maximum load.
Fasse Industrietextilien GmbH recommended the following as a solution: install low-cost PPS (Polyphenylsulphide) filter bags, with the possibility of purchasing a new set of bags if the process conditions deteriorated. In addition they suggested installing one of the seven baghouse chambers with bespoke #6255 Tetratex Ultra High Efficiency Woven Fibreglass filter bags, to highlight the increased benefits if Tetratex ePTFE membrane filter media over conventional filtration products.
Due to technical issues in the process, the baghouse was not in use for a year, after which time the only sleeves still in tact in the filter chambers were the #6255 Tetratex Ultra High Efficiency bags; the alternative PPS bags had become tarnished and stressed. A further technical defect with the cleaning cycle led to oil and water from the compressor coming into contact with the sleeves, whilst the Tetratex filter bags remained in a good condition, the PPS bags had to be replaced.