12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, EstoniaDISTRICT HEATING AND COOLING WITH LARGE CENTRIFUGAL CHILLER-HEATPUMPSUlrich PietruchaFriotherm AG, SwitzerlandABSTRACTWith prices for primary energy resources soaring, therecovery of "waste energy" was getting into the focus ofattention within the last years. Also the global climatechange reminded us to limit the use of primary energyresources to a minimum, thus exploiting "waste energy"potentials wherever feasible. The process of upgradinglow grade waste heat is especially interesting wherelarge amounts of such energy are available at onepoint, e.g. next to sewage water treatment plants,alongside main sewers, in power plants or close toground water sources.Even if the "waste energy" potential is abundant andeasily exploitable, the aspect of overall thermalefficiency is considered crucial for the final decision toinvest in large heat recovery installations.Number of units 2TypeUNITOP® 50 FY/34FYRefrigerantR134aHeat source medium Raw waste waterRaw sewage water inlet 10.0 °C ... ~ 15 °CRaw sewage flow water flow 3800 m3/hHeating water temp. in/out 60 / 90 °CHeating water flow824 m3/hPower at terminal9‘750 kWHeat capacity27‘600 kWCoefficient of performance 2.83 up to >3.0INTRODUCTIONDescribed are five applications of large centrifugal heatpumps-chillers for the use in large districtheating/cooling systems.Application 1: Heat recovery from raw sewage waterand hot water production at 90 °C.Application 2: Combined heating and cooling with araw sewage water heat pump/chiller installation. Thisplant is operated successful since 1989.Application 3: Combined heating and cooling: acombination of cooling with simultaneously heatproduction in summer and heat recovery from cleanedsewage water in winter.Application 4: Heat recovery from wet flue gascleaning processApplication 5: Combined heating and cooling inStockholm1. SKOYEN VEST PLANT IN OSLO: HOT WATERPRODUCTION AT 90 °CThis is the world's largest heat pump plant using rawwaste water as heat source. It is installed in a cavernalongside one of the main waste water channels inOslo. With 2 heat pumps a heating capacity of 27'600kW is generated by recovering heat from raw wastewater.One of the Skoyen heat pumps2. THE SANDVIKA PLANT IN OSLO: COMBINEDHEATING AND COOLING FROM A RAW SEWAGEWATER HEAT PUMPThis is the oldest combined chiller/ heat pumpinstallation in the world, producing simultaneouslycooling, taking out heat from raw sewage water andproducing heating capacity for the district heatingsystem.The heat pumps are in successful operation since 1989and each one has an additional heat exchanger, whichis used either as raw sewage evaporator or as rawsewage water condenser.Each heat pump has an overall operating time of about160'000 hours, means the heat pumps were operatedsince 1989 each year for more than 8'400 hours.A 3rd larger heat pump was taken into operation in2008.258