System and method for heating primary air, feed water and circulating water through bypass smoke

Abstract

The invention discloses a system and method for heating primary air, feed water and circulating water through bypass smoke. A hot smoke outlet of a coal-fired boiler of the system comprises a hot smoke main way and a hot smoke bypass. The hot smoke main way communicates with a smoke bin chamber of a tri-section bin preheater, and the smoke bin chamber communicates with a cold smoke main way. A baffle door is mounted in the hot smoke bypass and sequentially communicates with a feed water heat exchanger, a high-temperature primary air heat exchanger, an air heater circulating water heat exchanger and a low-temperature primary air heat exchanger. The low-temperature primary air heat exchanger communicates with a cold smoke bypass. The feed water heat exchanger heats the feed water, the low-temperature primary air heat exchanger and the high-temperature primary air heat exchanger heat the cold primary air, and a water pipe and the air heater circulating water heat exchanger heat the circulating water. The method includes the steps that the feed water, the primary air and the circulating water are simultaneously heated through waste heat of the bypass smoke. Utilization of the waste heat of the smoke is greatly improved, and the system and method are more beneficial for environmental protection, energy saving and cost reduction.

Description

technical field [0001] The invention relates to a system and method, in particular to a system and method for heating primary air, feed water and circulating water by using bypass flue gas. Background technique [0002] The air preheater is one of the important components of the pulverized coal boiler system, which plays a role in reducing the exhaust gas temperature, increasing the temperature of the combustion air, making the fuel easy to ignite, stable combustion and improving combustion efficiency. The air preheater mainly includes three compartments, shell and tube two forms. At present, more than 90% of coal-fired boilers in power stations use three-compartment air preheaters, and the three compartments circulate hot flue gas, primary air and secondary air respectively. In the current pulverized coal boiler system, the high-temperature flue gas generated by the coal-fired boiler is mainly sent to the three-compartment air preheater to heat the air for combustion (that...

AI Technical Summary

Problems solved by technology

In the current pulverized coal boiler system, the high-temperature flue gas generated by the coal-fired boiler is mainly sent to the three-compartment air preheater to heat the air for combustion (that is, the secondary air). The heat of the flue gas is sufficient, which leads to a waste of energy; at the same time, the waste heat of the flue gas in the bypass has not been fully utilized in cascades, which not only causes a waste of energy, but also is not conducive to environmental protection and energy saving. The system and method for heating the primary air, feed water and heater circulating water at the same time will consume a lot of energy to heat the primary air, feed water and heater circulating water, which will increase the operating cost to a certain extent

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