严寒地区大型燃气锅炉排烟加热空气方式的优化与应用
Optimization of Air Heating in Large Gas-fired Boiler by Flue Gas Waste Heat in Cold Areas

由于严寒地区冬季室外空气的温度低，助燃的空气进入锅炉会产生爆燃和震动、燃烧效率降低。同时大型供热系统回水温度高，燃气锅炉排烟温度较高，排烟余热深度利用中，烟温降低程度受到回水温度条件限制。本文提出了新的烟气加热空气方式，与常规烟气加热空气方式相比，减少了设备耗材、体积及阻力，应用于大型燃气供热锅炉烟气余热深度梯级利用的节能改造。工程实测表明：烟气余热回收和助燃空气加热系统，可将烟气温度降到锅炉回水温度及以下，锅炉燃气利用热效率提高了13.2%，烟气余热回收率为66.7%，实现了排烟余热深度利用，并解决了助燃空气进入锅炉产生爆燃和震动的问题，为严寒地区燃气锅炉烟气余热深度利用与助燃空气加热提供了参考。
Because the outdoor air temperature in cold regions is severely low in winter, the combustion-supporting air will cause deflagration and vibration while directly supplied to the boiler and the combustion efficiency is also decreased. At the same time, the temperature of the return water in a large heating system, and the exhaust gas from the gas boiler, are both high. Thus, the exhaust gas could not be cooled down to a relatively low temperature by the return water during the waste heat utilization process. This paper presents a new way to heat the air by using flue gas waste heat, which is smaller, requires less space, and has less resistance compared with conventional heat exchange equipment. The proposed method can be applied to the flue gas waste heat deep-utilization of a large gas heating boiler. Field test results show that the flue gas waste heat deep-utilization and the combustion-supporting air heating system can cool the flue gas temperature near to or even lower than the return water temperature of heating network. The utilization efficiency of gas combustion is increased by 13.2 %, and the recovery rate of the flue gas waste heat is 66.7 %. Then, flue gas waste heat deep recovery is realized, and the problem in which the combustion-supporting air causes deflagration and vibration while directly supplied to the boiler is solved. The paper provides a reference for flue gas waste heat deep-utilization in cold regions, and for combustion-supporting air heating system optimization