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Show INTRODUCTION Vasteras District Heating Power Station is supplying about 99 percent of the consumed heat energy in the city of Vasteras and the near neighbourhood. Vasteras is a city in the middle of Sweden about 1000 km (600 miles) south of Our )ric C f YG**> • the polar circuit. The average temperature during the summer period, May to September, is about 15°C, and the average temperature during the winter period is about -5°C; the coldest week is normally -15°C to -20 C. The city has about 105,000 inhabitants and the connected heat flux is about 1000 MW. The energy consumption was in the season 81/82 about 1950 GWh. The heat is supplied from the district heating power station in a network of pipes, and all the houses have a heat exchanger instead of their own boiler In this paper I will not go into the advantages of this system, but instead will describe the district heating power station and the conversion from oil to coal firing. The power station mainly consists of four boilers and four turbines. Two of the turbines are pure back pressure turbines, which at the same time can produce 50 MW and 100 MW . There is also a possibility of bypassing the turbine with steam if only heat is requested, and then all the steam from the boilers gives the energy to the district heating system. These two boilers were converted from pure oil firing to coal firing during the winter period 1980/81 and commissioned on coal in summer 1981. The other two turbines can produce 220 MW . /350 MW , or 250 MW ./0 MW , , el th el th or, if the turbines are bypassed, about 700 MW . . One of these bigger blocks will be converted to coal firing during the winter period 1982/83 and will be commissioned in August 1983. More detailed technical data is presented in Picture No. 1 for the blocks, and the steam systems are presented in Picture No. 2. Coal Conversion 1981 When the two small units were built in 1961-63, there were discussions to install firing equipment for both oil and coal. The price difference between the fuels was not big enough at that time. The boilers that were ordered were equipped with combined coal-oil burners and with a slag hopper. 5-2 |