电厂空气预热器漏风率的测量

空气预热器的作用是回收烟气热量并对一、二次风进行加热,其性能对大型电站锅炉的热效率有显著影响。电站锅炉一般采用回转式的空气预热器,由于动静间隙的存在,一部分空气流入烟气中形成"漏风"。漏风率可以通过测量空气预热器出入口的烟气氧量进行计算得出,但该方法存在较大不确定性,且实施过程复杂烦琐,高精度和易于实施的测量方法仍是试验研究的重要方向。对空气预热器的漏风进行热平衡分析,得出了计算漏风的可行方法。得益于温度测量的较高精度,提供的方法能够分辨出漏风率的细小变化。生产现场一般都具备充分的温度测量装置,并且温度测量的实施较为方便,因而本方法有益于对漏风率的变化情况进行现场监测。

Measurement of Air Leakage Rate for Air Heater in Power Plants

Air heaters are used in power plants to reduce the exhaust gas temperature of boilers. For boilers with large capacities, air heater is very important to improve its thermal efficiency. Rotary air heaters are widely adopted in power plants. Due to the gap between rotor and static parts, part of air leaked into flue gas. The air leakage rate can be calculated by measuring the concentration change of oxygen in flue gas. Since the concentration measuring is very complicate and tardy, more method is needed to grasp the air leakage rate. The heat balance of leaked air and flue gas gives a possible way to calculate the air leakage rate, which is easier to be carried out. The accuracy of the method is satisfactory due to the high accuracy of temperature measuring. With the sufficient temperature monitoring facilities in power plants, the method can be applied conveniently.