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, Estoniasites should be at least 9 km/year. This way theprocess of ageing will slow down and also the averageage will stabilize on a certain mark. One of the possiblesolutions is to replace the pipes with higher intensity of3–4% until reaching the 17–20 years average age andthen reduce the length of renovated pipes per year tothe 2–2,5% of the whole length of DH network.CONCLUSIONSDistrict heating networks in Estonia are mostly old andin bad condition. The state of the district heatingnetworks of Tallinn is typical for the rest of Estonian DHnetworks. That‘s why the result of damage analysismade for the DH network of Tallinn can be used for theother networks in Estonia.The AS Tallinna Küte enterprise makes operation of85% from the length of district heating networks inTallinn. Tallinna Küte data about the damages wereused for assessment.Places of damages in the DH system are following:armature, compensator, pipes and construction. Mostof the damages happened in the pipes.As regards the character of damages, the typicaldamages are caused by external corrosion, internalcorrosion, defect of construction, defect of installationand wrong service. The major part of damages iscaused by external corrosion of pipes.The age of networks, the quality of construction worksand the network operation conditions are the mostimportant factors, which influence the damages indistrict heating networks. The number of damages canbe reduced by reducing the average age of thenetworks. This is possible by replacing the old pipelinesand other networks systems elements. The intensity ofreplacement works during last 25 years was less thanone percent from the whole length of pipes.Seven forecasts for pipes average age accordingdifferent intensity of renovation works were simulated:for current intensity of renovation (3,06 km/year) andfor intensities when 1%, 1,5%, 2%, 2,5%, 3% and 4%of total DH system length would be annually renovated.It was concluded, that for maintaining the networksaverage age at least at former level, the rate of oldpipelines replacement should exceed the 2,5% of thewhole length of DH system.AKNOWLEDGMENTThis work has been partly supported by the EuropeanSocial Fund within the researcher mobility programmeMOBILITAS (2008–2015), 01140B/2009REFERENCES[1] Cogeneration and district energy sustainableenergy technologies for today…and tomorrow,<strong>International</strong> Energy Agency, 2009.[2] Long-term Public Fuel and Energy SectorDevelopment Plan until 2015, Riigi. Teataja, RT I,23.12.2004, 88, 601[3] Hlebnikov, A.; Siirde, A. The major characteristicparameters of the estonian district heatingnetworks, their problems and development. // The11th <strong>International</strong> <strong>Symposium</strong> on District Heatingand Cooling: University of Iceland, 2008, 141–148.[4] Tallinna küte webpage, www.soojus.ee[5] A. Hlebnikov "The analysis of efficiency andoptimization of district heating networks inEstonia", Doctoral Thesis, Tallinn University ofTechnologies, 2010.282