A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 1994

This study is aimed to find energy conservation opportunities in a typical combined heat and power district heating(CHP/DH) plant in P.R. China. Environmental benefit of the plant in the form of reduced emission has also been analyzed. There is a strong fluctuation of steam demand on the CHP/DH plant. In summer, the plant has to operate at low loads because of reduced steam demand. Energy analysis of the boilers and turbo-generators shows that their efficiencies vary with the changes of load levels. A simulation and optimization program is developed to optimize the operation so that the loads dispatched to each boiler and turbo-generator are rationalized to minimize energy consumption while satisfying the steam demand and power constraint. The analysis shows that optimizing operation as above can lead to an energy saving of 4.2%. The CHP/DH plant has no provision for condensate recovery at present. It is estimated that recovery of condensate would be a feasible option of energy conservation with a pay back period of 2.91 years. Feasibility of using absorption chillers for space cooling as a mean of improving steam demand in summer has been studied. It is found that use of double effect absorption chillers by the users would be feasible with a pay back period of 2.4 years. Emission analysis shows that a CHP/DH plant significantly reduces emission of TSP(Total suspended particulates), CO₂ and SO₂ compared to separate small boilers used for space heating. TSP emission by the CHP/DH plant is only 10% of that of the small boilers.