Boiler flue gas waste heat recovery system

Abstract

The invention discloses a boiler flue gas waste heat recovery system, comprising an economizer, a pump body, a first heat exchanger, a second heat exchanger, a heating network water system and a condensed water system. The heat exchange medium side of the first heat exchanger and the pump body are communicated in sequence to form a first circulation loop, and the economizer, the heat exchange medium side of the second heat exchanger and the pump body are communicated in sequence to form a first circulation loop. Secondary circulation loop, the first water side of the first heat exchanger communicates with the condensate water system to form a first heat exchange loop, and the second water side of the second heat exchanger communicates with the heat network water system A second heat exchange circuit is formed. The invention realizes the independent heat exchange between the heating network water and the condensed water, effectively prevents the water quality interference phenomenon, and ensures that the condensed water of the host is not polluted. At the same time, the indirect heat exchange method of heat exchange between the heat exchange medium and the boiler flue gas is adopted, so that the condensed water and the heat network water are not in direct contact with the economizer, which reduces the pressure resistance requirement of the economizer and saves the cost of raw materials.

Description

technical field [0001] The invention relates to the technical field of boiler flue gas waste heat recovery, in particular to a boiler flue gas waste heat recovery system. Background technique [0002] One of the most important losses in boiler operation is the heat loss of flue gas. Reducing the loss of flue gas and rational utilization of flue gas waste heat is particularly important for saving energy and improving the economy of power plants. Low-temperature economizers are often used in the process of boiler flue gas waste heat recovery, that is, condensate water and / or heat network water are used as cold sources to absorb flue gas waste heat. When exchanging heat with condensed water during non-heating period, the condensed water absorbs exhaust heat in the low-temperature economizer, lowers the exhaust temperature, is heated by itself, raises the temperature and then returns to the low-pressure heater system of the turbine to replace part of the low-pressure heater It ...

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Problems solved by technology

[0003] Due to the different cooling sources of the flue gas waste heat system in the heating period and the non-heating period of the existing flue gas recovery system, the water side system of the low-temperature economizer needs to be switched according to the change of the load nature of the unit. During the switching process, due to condensation Water and heating network water share the pipeline between the inlet and outlet shut-off valves, so there is a problem of using the same pipeline with different water qualities alternately. If the switching between heating network water and condensate water is not performed properly, the condensate water quality is easily polluted, and the pre-washing Need to consume part of condensed water or demineralized water, waste of working fluid

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