System capable of preventing water vapor in flue gas recirculating pipeline of gas-fired boiler from condensing

Abstract

The invention discloses a system capable of preventing water vapor in a flue gas recirculating pipeline of a gas-fired boiler from condensing, and relates to the technical field of safe operation of the gas-fired boilers. The system comprises an air preheating system, a return water heating system, a flue gas recirculating system and an absorption type heat pump flue gas waste heat utilization system. While the system operates, a lithium bromide absorption type heat pump is used for cooling flue gas on the tail part of the boiler to a temperature of about 30 DEG C, and return water and part ofcombustion-supporting air are preheated. Preheated air and circulated flue gas are fed into a furnace hearth to support combustion after being mixed, and the temperature of a gas mixture is higher than a dew point of the water vapor before the gas mixture enters the furnace hearth, so that condensed water is not generated. On the premise of sufficiently utilizing flue gas waste heat, the problemthat the pipeline and a fan are damaged as water vapor in the flue gas recirculating pipeline is condensed especially in winter in North is effectively solved. Besides, water vapor in the flue gas isrecycled, so that economical efficiency and safety of boiler operation are improved.

Description

technical field [0001] The invention belongs to the field of gas boilers, and in particular relates to a system for avoiding water vapor condensation in gas boiler flue gas recirculation pipes. Background technique [0002] In recent years, with the development of natural gas mining technology and the promotion of the "coal-to-gas" policy, the proportion of natural gas in primary energy consumption has increased year by year. However, at present, the exhaust gas temperature of natural gas boilers is generally high, resulting in a large amount of sensible heat and latent heat in the flue gas not being recycled, resulting in serious energy waste. In addition, in order to control NO in the combustion process of natural gas x Generated, many gas boilers are equipped with flue gas recirculation system. In practical applications, the temperature of the extracted recirculated flue gas is generally lowered after being mixed with cold air, and condensation of water vapor occurs in ...

AI Technical Summary

Problems solved by technology

The invention not only realizes waste heat recovery of flue gas, but also effectively solves the problem of water vapor condensation and damage to flue gas recirculation pipes and fans after the recirculation flue gas is mixed with cold air, and improves the economy and safety of system operation

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