Comprehensive recycling system and method of waste heat in thermal power plant

Abstract

The invention discloses a comprehensive recycling system and a method of waste heat in a thermal power plant. The comprehensive recycling system of the waste heat comprises a closed heating medium water cycle heat exchange system, recovers both steam exhaust waste heat of an induced draft fan driving a steam turbine and smoke discharge waste heat at the tail part of a boiler; on the one hand, the total heat of recovered whole plant waste heat is increased; and on the other hand, the system and the method can be used for replacing high-quality heat energy with higher heat energy utilization rate by two low-quality heat with low heat energy utilization rate and higher heat power value, so that the power consumption rate of whole plant can be reduced, the standard coal consumption of power generation can be reduced, and the unit operation economy is greatly improved.

Description

【Technical field】 [0001] The invention belongs to the field of thermal power plants, and relates to a system and method for comprehensive recovery and utilization of waste heat in thermal power plants. 【Background technique】 [0002] The induced draft fan is a large energy consumer in thermal power plants, and its power accounts for about 1% of the power consumption rate of thermal power plants. In order to reduce the power consumption rate of power plants and increase the external power supply capacity of power plants, major domestic power groups have adopted The scheme of the steam turbine driving the induced draft fan. [0003] It is understood that at present, most domestic induced draft fan driven steam turbines have their own condensers, and there are two common cooling methods for their condensers: one is cooling by an open circulating cooling water system; the other is using an indirect circulation method Allow to cool. The advantage of the former is that the back ...

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Problems solved by technology

The advantage of the former is that the back pressure of the driving steam turbine is low and the operating efficiency is high, and the disadvantage is that there is evaporation loss of cooling water; the advantage of the latter is that there is no evaporation loss of cooling water, but the disadvantage is that the back pressure of the driving steam turbine is high and the operation less efficient

[0004] From the above situation, it can be seen that no matter which of the above two condenser cooling schemes is adopted, there will be a loss at the cold end, and a large amount of latent heat of vaporization in the exhaust steam of the driving steam turbine will be discharged to the atmosphere, which is wasted in vain.

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