SOLAR WATER PREHEATING FOR OPEN DISTRICT HEATING NETS - SYSTEM INTEGRATION OF LARGE-SCALE FACILITIES

摘要

In combined heat and power (CHP) plants with so-called open district heating nets, large quantities of cold water (e.g. 12 °C) are heated to supply temperatures (e.g. 60 °C) using fossil fuels. Such water can be effectively preheated by solar thermal systems before conventional heating to supply temperature. Due to high basic load, low inlet temperature and good climatic conditions in most parts of the Commonwealth of Independent States (CIS), extraordinary solar gains and solar heat generation costs of less than 1 Euro-Cent/kWh_(th) can be achieved during the frost-free season. The purpose of this investigation is to identify the most suitable solution to integrate large-scale solar thermal installations into the complex process of CHP plants in Central Asia and Russia. The influence of a solar thermal system on the CHP process and on the electricity generation has been investigated based on the actual process of the central CHP plant in Bishkek (Kyrgyzstan). The results indicate that the construction of a large solar thermal plant is possible under the present technical boundary conditions. Preheating of feed water does only have a small impact on power production of electricity, which will be overcompensated by the heat production of a solar thermal system.