Research On Low Temperature Flue Gas Waste Heat Utilization System Of Power Plant Boiler

Energy is one of the basic problems that influence the healthy development of economy and society. With the rapid development of our economy, the contradiction of energy supply and demand is increasingly serious, so one feasible way for solving the problem is to increase the fossil energy utilization ratio. The coal-fired power plants provide most of the electricity in China, but consume lots of coal and industry water. Boiler in power plant is the basic equipment of energy transfer and change system, energy conservation of which will directly affect the whole performance of the power plant and it is signality to the strategy of energy saving and environmental protection. And the waste heat loss takes more than half of the whole thermal loss of the boiler, so to reduce the waste heat loss is a important way to reduce the energy consumption in power plant.This paper has made an overall analysis on a low temperature flue gas waste heat utilization system which is directly and easy performed. Equivalent enthalpy drop method and heat balance of steam-water system are used to analyses the difference of energy saving potential among different integration modes, it is shown that to heat up the former low pressure heater when possible can get a better effect. And also the water consumption in the desulphurization system without gas-gas heater will be greatly reduced because of the decreased inlet temperature results from the low temperature flue gas waste heat utilization system. However, the energy recovered is low grade heat, large heat exchange area is needed to ensure the heat transfer effect. What is more, the more energy the integration mode recovered, the larger heat exchange area it needs. The corrosion problem is always the key factor that limits the depth of the waste heat utilization. An experiment is designed and processed to verify the differences of anti-corrosion capacity among different materials. When the low temperature flue gas waste heat utilization system is used in engineering application, the energy saving effect, the water saving effect, the heat exchange area consumption and anti-corrosion material consumption all should be considered to match the practical land occupation and investment situation, only in this way can the profit be largest.