垃圾焚烧炉受热面结渣实验研究

Experimental Study on the Slagging of Power Station Incinerator

垃圾焚烧烟气中的飞灰在焚烧炉过热器区域结渣,可能导致焚烧炉停机,影响焚烧发电的经济性。为探索焚烧炉受热面结渣机制,采用燃油产生的烟气和工业焚烧炉的飞灰混合模拟垃圾焚烧烟气,研究了过热器的运行工况、温度、布置形式、几何尺寸等对结渣过程的影响。利用扫描电镜/能谱分析、X射线荧光分析和X射线衍射等方法分析了渣的成分与物相。结果表明:高温烟气有利于渣块的形成,在实验过程中当温度高于450℃时,开始形成黏结性积灰,当温度高于460℃时,受热面开始结渣。管子壁面温度对结渣有直接影响,降低管壁温度可以抑制结渣过程。几何因素(管径)对结渣影响较大,直径较小的管子更容易结渣。另外,含有低熔点、高黏结性物质较多的颗粒更容易沉积形成结渣。渣中主要物相为:Ca2SiO4、Ca9(Al6O18)、Ca2Al(AlSiO7)、Fe2O3。低熔点化合物如KCl、CaCl2在结渣的初始层起到了黏合剂的作用。几何因素、温度对结渣过程的影响与实际垃圾焚烧炉改造和运行状况吻合。

The fly ash in the flue gas during waste incineration deposits on and fouls the superheater,which leads to abnormal operation and emergency shutdown of power station.In order to study the fouling and slagging process the fly ash taken from the on-site waste incinerator was mixed with the oil combustion exhaust gas to investigate the influences of temperature,heating surface arrangement and dimension on the slagging and fouling.The scanning electron microscopy（SEM）/energy dispersive X-ray（EDX）,X-ray fluorescence（XRF） and X-ray diffractometer（XRD） analytical methods were also employed to determine the chemical composition of slagging.The experimental results showed that high temperature favor slagging formation.The fouling occurs as the flue gas temperature exceeds 450 ℃,and slagging occurs as temperature rises above 460 ℃.The heating surface wall temperature directly affects the slagging so that decrease in wall temperature can retard the slagging formation.The diameter of tubes has a significant influence on the slagging.The less the diameter the slagging more likely occurs.Stagger arrangement is prone to be fouled compared with in-line arrangement.The sticky fly ash of low melting point with Ca2SiO4、Ca9（Al6O18）、Ca2Al（AlSiO7）、Fe2O3 is easy to deposit and foul.The low melting point compounds,such as KCl and CaCl2 serve as bond during slagging initiation.The effects of temperature and heating surface arrangement on slagging discovered in the experiments coincide with the retrofitting and operating results of the commercial incinerators.