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, Estoniapay attention to its rotating speed which should be atthe minimum from 50 to 60 per cent of the nominalrotating speed.PART 2.INTRODUCTIONThe goal of the second part was to motivate the districtheating companies to analyse their pumping methodsand, hopefully, to lower their pumping costs.Total savings potential in district heating pumping inFinland was also estimated.This part is based on the Finnish district heatingstatistics of the year 2007 [1]. The statistics cover thedata of nearly 200 district heating companies but onlyabout 60 of them have reported the electric power usedin district heating pumping.The biggest companies have reported the pumpingenergy, thus, the pumping figure is available tocompanies which supply almost 70 per cent of alldistrict heat in Finland.STATISTICAL FINDINGSThe used pumping energy in different companies wasanalyzed by comparing the pumping energy to thefollowing parameters:Heat supply (sold heat + losses)Length of the district heating networkHeat density (supplied heat energy divided by thelength of the DH network)The following parameters were also examined but noclear correlation was to be seen, and the results aretherefore not reported in this paper:Heating output density (daily maximum heatingoutput divided by the length of the DH network)CHP productionShare of small (< 30 kW) consumersPeak load utilization timeLosses of DH network1. Heat supplyHeat supply is the same as sold heat + losses.The assumption used was that the bigger the companythe smaller the proportional pumping energy.The situation is presented in figures 6a and 6b, whereonly the companies which supply less than2500 GWh/a (Helsinki not included) are shown.Specific pumping energy (electrical power /heat supply)Fig. 6a. Example Electricity used for pumping in relation tothe size of a district heating company, heat supply0–2 500 GWh/a.Specific pumping energy (electrical power /heat supply)Fig. 6b. Electricity used for pumping in relation to the sizeof a district heating company, heat supply 0–300 GWh/a.The average pumping energy is 0.6 per cent of theheat supply. The bigger the company, the smaller theproportional pumping energy.Companies with exceptionally high pumping energy aremarked with a circle.2. Length of the district heating networkSpecific pumping energy (electrical power/ heat supply)1.6 %1.4 %1.2 %1.0 %0.8 %0.6 %0.4 %0.2 %1.6 %1.4 %1.2 %1.0 %0.8 %0.6 %0.4 %0.2 %1.7 %1.5 %1.3 %1.1 %0.9 %0.7 %0.5 %0.3 %Specific pumping energy vs. heat supplySupply 0 - 2 500 GWh/a0.0 %0 500 1000 1500 2000 2500Heat supply, GWh/aSpecific pumping energy vs. heat supplySupply 0 - 300 GWh/a0.0 %0 50 100 150 200 250 300Heat supply, GWh/aSpecific pumping energy vs. length of the DH netLength 0 - 500 km0.1 %0 100 200 300 400 500Length of the DH net, kmFig. 7a. Electricity used for pumping in relation to thelength of the district heating network, 0–1 300 km285