Gas Boiler Flue Gas Waste Heat Recovery and Purification System for Combustion Air and Gas Humidification

Abstract

The invention provides a gas-fired boiler flue gas waste heat recovery and purification system with a function of humidifying combustion air and gas. The system comprises a spray type heat exchange tower, an intermediate circulating water system, a flue gas circulation device and a gas mixing device, wherein the combustion air, the gas and boiler flue gas are subjected to water-heat exchange withthe intermediate circulating water system in the spray heat exchange tower and are humidified; the humidified gas returns to a boiler through the gas mixing device to continue burning. The invention uses the intermediate circulating water as a medium to realize the humidification and recirculation of the flue gas as well as recovery of the latent heat of the flue gas under the high intermediate circulating water temperature condition; furthermore, the latent heat of the high temperature flue gas and sensible heat are utilized to heat the humidified gas and combustion air; after being subjectedto recirculation, the humidified flue gas, combustion air and gas are mixed and introduced into the gas boiler, so that NOx emission can be reduced, and the dew point of the flue gas is increased; therefore, the purposes of reducing pollutant emission from the gas boiler and improving the heating effect of the boiler are achieved.

Description

technical field [0001] The invention belongs to the technical field of flue gas waste heat recovery and purification, and in particular relates to a gas boiler flue gas waste heat recovery and purification system for humidifying combustion-supporting air and gas. Background technique [0002] The technical research on boiler flue gas waste heat recovery has a long history at home and abroad. Its development has gone through the process from simple sensible heat recovery to complex latent heat recovery mechanism, and the degree of waste heat utilization has been deepened step by step. Since the return water temperature of domestic large-scale centralized heating networks is generally 55°C, and the return water temperature of small-scale centralized heating networks is also around 45°C, this temperature is the lowest temperature that can be obtained by the spray-type flue gas waste heat recovery system without an additional low-temperature cold source temperature, but the temp...

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Problems solved by technology

Since the return water temperature of domestic large-scale centralized heating networks is generally 55°C, and the return water temperature of small-scale centralized heating networks is also around 45°C, this temperature is the lowest temperature that can be obtained by the spray-type flue gas waste heat recovery system without an additional low-temperature cold source temperature, but the temperature is higher than the flue gas dew point temperature under normal circumstances and the heat exchange temperature difference between the spray water and the flue gas is small, and the recovery effect of the latent heat of condensation of the flue gas is limited

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