Power Generation System for Using Unused Energy in District Heating Pipelines

When the hot water for district heating (DH) is supplied through a thermal grid, a pressure differential control valve (PDCV) in a substation protects the users' equipment from the high pressure water and helps to supply DH water to long distance. It also controls the constant temperature and adjusts the constant pressure in the thermal grid. However, cavitation occurs in PDCV due to the use of high pressure DH water. It causes frequent failures, many problems and energy losses. It makes a complaint to both the operator and the user. In order to solve these problems, we have introduced the hydroelectric power generation method to replace PDCV with hydraulic turbine, convert the unused differential pressure within a DH pipe into electricity. When a differential pressure power generation system is operated in the user's substation, power generation of about 10 to 20 MWh and reduction of carbon dioxide emission to about 7 tons can be seen for a year. It is possible to install more than 3,000 out of about 10,000 of the district heating in Korea. It can grow into a new energy business model. It is also calculated that the DH plant has a power saving effect. The cost of the DH pump power can reduce by more than 3%, and the efficiency of CHP plant can increase by more than 0.3% because 10% defective of PDCV is decreased. (C) 2018 The Authors. Published by Elsevier Ltd.