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Our services included engineering, procurement, construction and commissioning as well as the trial operation of the energy and district heating control centre of Forsthaus West in Bern.
For the first time ever, the energy centre combines three plants under one roof: a waste incineration plant (WIP) is interconnected with a wood-fired CHP plant (WF CHP) and a gas-powered combined-cycle power plant (CCPP). Electricity, steam and district heating are generated using waste, wood and natural gas. This combination enables flexible operation of the energy centre. It produces more district heating or more electricity from household waste, wood and natural gas depending on the season and the demand.
Power generated from waste, wood and gas
Two extraction-condensing steam turbines generate electricity using the steam from the waste incineration plant, the waste heat boiler of the gas turbine and the wood-fired CHP plant. The electrical energy is transferred via the generators to the power plant’s switch-gear to cover station service and then via transformers to the power grid.
The remaining exhaust steam is condensed in two air-cooled condenser plants (ACCP). One special feature of the ACCPs was their integration into the architectural design on the roof of the energy building.
In the energy centre, district heating is produced in two stages in two heating condenser lines from intermediate and low pressure steam. The energy centre transfers district heating to the network at a flow temperature of 180°C via four network recirculating pumps. The return comes into the power plant at 80°C. Two gas-fired peak load boilers can be brought on line when demand is higher.
District heating and steam network expansion
Redundant systems in the district heating centre guarantee that the district heating consumers are supplied at all times. Two district heating pressure accumulators each with a volume of 150 m³ serve as a hydraulic shunt to cover short-term peaks in demand. Their storage capacity is approx. 30 MWh. Two redundant steam pressurising systems which can be supplied from the various live steam systems ensure the necessary pressure in the district heating system.
Kraftanlagen was also significantly involved in ewb’s network expansion. Virtually all the established pipe laying systems were used in the process. 2,500 m DN 80 to 400 as insulated steel pipe in the plant conduit for district heating and service water. 1,100 m steel-jacket pipe DN 80 to 250 for the district heating supply. 3,100 m steel-jacket pipe DN 125 to 150 for the 40 bar process steam extraction and 3,100 m plastic-jacket pipe DN 80 for the condensate return.