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, EstoniaTable 3: Results – Multiperiod ModelBase Case - Case 1CHP DH Load [%] 100 90 80 70 60 50 40 30 totalTime [h] 2440 530 530 530 530 530 - - 212 daysFuel Input [MW] 25.90 23.19 20.39 17.47 14.58 11.91 - - 109.56 GWhPower [MW] 6.29 5.64 4.91 4.06 3.22 2.54 - - 26.13 GWhDistrict Heat [MW] 16.50 14.85 13.20 11.55 9.90 8.25 - - 70.85 GWhCHP + Pyrolysis - Case 2CHP DH Load [%] 100 90 80 70 60 50 40 30 totalTime [h] 2440 530 530 530 530 530 - - 212 daysFuel Input [MW] 25.90 36.49 44.24 52.42 60.21 53.88 - - 194.13 GWhPower [MW] 6.29 5.54 4.69 3.71 2.88 2.25 - - 25.45 GWhDistrict Heat [MW] 16.50 14.85 13.20 11.55 9.90 8.25 - - 70.85 GWhPyrolysis Slurry [MW] 12.21 21.16 30.60 39.58 36.76 - - 74.31 GWhCHP + Pyrolysis - Prolonged Operation Hours - Case 3CHP DH Load [%] 100 90 80 70 60 50 40 30 totalTime [h] 2266 633 633 633 633 633 633 633 279 daysFuel Input [MW] 25.90 36.49 44.24 52.42 60.21 50.97 39.56 28.88 256.62 GWhPower [MW] 6.29 5.54 4.69 3.71 2.88 2.27 1.71 1.18 28.17 GWhDistrict Heat [MW] 16.50 14.85 13.20 11.55 9.90 8.25 6.60 4.95 81.26 GWhPyrolysis Slurry [MW] 0.00 12.21 21.16 30.60 39.58 33.79 26.11 19.00 115.46 GWhTable 4: Results - PEF and CO2 CoefficientBase CaseCase 1CHP + PyrolysisCase2CHP + Pyrolysis -Prolonged OperationCase 3Required Backup Power MWh 27.8 27.8 15.5Total PEF [-] 0.80 0.79 0.68CO2 Coefficient kg/MWh 38.6 42.1 -5.3CONCLUSION AND DISCUSSIONThe work shows that by integration of a CHP plant withwood pyrolysis operation hours can be increases by30%, a valuable product can be co-produced and PEEas well as the CO 2 emission coefficient of the DHN canbe substantially improved. As next steps morecomprehensive data of the fuel supply chain should beimplemented to get more realistic values that willapprove the trend shown with this work. The processcan be further improved by integrating heat that is setfree during the condensation of the pyrolysis liquid andgaseous product. The heat is available in atemperature range from approximately 500 °C to 25 °Cand could hence be used for steam superheating,feedwater preheating, but also for DH generation. Thisintegration is not a simple task since many plantparameters influence each other. The heat integrationmust be carried out together with a pinch analysis toassure an energy efficient integration.174Another open question is the influence of the realpyrolysis gas on the combustion temperature and fluegas properties. In order to gather more details of thepyrolysis process a simple pyrolysis model is currentlyunder development. Together with the power plantmodel the integration can be further optimised aimingfor highest PEE along with low CO 2 emissioncoefficients.Further an economic analysis should be carried out inorder to show potential economic benefits. Theintegration itself seems to be viable – a statement thatis supported by a press release from June 2009 whereboiler manufacturer Metso and forestry company UPMannounced the development of a new viable fastpyrolysis process benefitting from the integration with aCHP plant [11].Concerning the European standards used forevaluation, it can be said that the power bonus methodcan be easily adapted to a polygeneration concept