Air injecting and backflow flue gas entraining heat exchanger for radiant tube combustion device

Abstract

The invention relates to the technology of a heat exchanger, in particular to an air injecting and backflow flue gas entraining heat exchanger for a radiant tube combustion device. The heat exchanger comprises a heat exchanger shell with a four-way structure, wherein the heat exchanger shell is connected with an inner core tube, a heat exchange tube and a high-temperature air injection tube; the high-temperature air injection tube has a conical reducing tube structure and is used for forming an air injection channel; the air injection nozzle end of the heat exchanger shell is connected with a main combustion nozzle through a corrugated pipe; and the flue gas inlet end of the heat exchanger shell is communicated with a radiant tube. In the heat exchanger, a conical reducing air injection pipe is added, negative pressure zone entrainment flue gas is formed, and the flue gas is mixed with preheated air; on the basis of effective heat exchange of the heat exchange tube, the preheating temperature of air is increased effectively; after the flue gas is mixed with the air, the oxygen concentration in a combustion zone is reduced, the generation amount of NOx is reduced, and the discharge amount of pollutants is reduced; fin structures arranged on the outer and inner sides in a staggered way increase a heat exchange area, and the turbulence scale of the flue gas and the air, improve a heat exchange effect, and utilize the flue gas afterheat efficiently; and the components are easy to assemble and disassemble.

Description

technical field [0001] The patent of the present invention relates to the technical field of heat exchange devices, in particular to a heat exchange device used in conjunction with a radiant tube combustion device to preheat combustion-supporting air. Background technique [0002] At present, in industries with high product quality requirements such as metal heat treatment and material melting, it is difficult for the traditional direct heating method to meet the process requirements. The indirect heating method of radiant tube combustion devices has been widely promoted and applied. In order to improve combustion efficiency and make full use of energy, most of these combustion devices are equipped with heat exchangers to preheat combustion air. Generally, there are two main forms of heat exchangers for radiant tube combustion devices: (1) heat exchangers used in conjunction with suction radiant tubes. The heat transfer effect is enhanced by adding a pockmarked surface to t...

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Problems solved by technology

This kind of heat exchanger has small air flow resistance loss, but the heat exchange efficiency is low. At the flue gas temperature of 1000 °C, the air can only be preheated to 350-400 °C, and the exhaust gas is above 650 °C; (2) with the drum The heat exchanger used with the embedded radiant tube, this kind of heat exchanger mostly adopts the structure type of jet flow and finned tube, that is, the outer tube of the heat exchanger is equipped with finned tube, and the inner tube adopts multi-stroke jet flow structure to improve Heat transfer effect

This kind of heat exchanger has a large loss of air flow resistance and requires a large air supply pressure, but the heat exchange efficiency is high. At a flue gas temperature of 1000 °C, the air can be preheated to above 500 °C and the exhaust gas temperature can be reduced to 600 °C. below ℃

In addition, the temperature of the combustion air is low, and there is NO x big emissions problem

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