烟气横掠管束外表面的积灰特性

针对石灰线生产中烟尘易沉积，烟气换热器表面积灰的问题，为开发具有自清灰功能和扩展受热面的高效传热元件，对粉尘物理、化学和外部工作过程特性进行研究，通过采用扫描电子显微镜及XRD等仪器，研究灰的粒径分布、外观形貌及化学成分等物理化学特性，并对管束外表面积灰特性进行实验研究，结果表明：石灰线粉尘粒径较大，颗粒结构紧密，表面有大小不一的孔，易产生物理沉积形成松散积灰；灰样浓度的增大会导致积灰量增加，相同时间内灰样浓度越高积灰量越大，顺风面更易产生积灰现象；烟气流速较大时，积灰量很快达到稳定，烟气流速的增加会导致迎风面积灰量减少，背风面积灰量增加，存在最佳的烟气流速使飞灰颗粒在管道表面的沉积量最小；增加横向节距、减少纵向节距有利于减少积灰量。

Ash deposition characteristics of external surface of flue gas swept across tube bundles

The problem of high exhaust temperature universally exists around the industrial boilers, which causes waste of energy. The surface of flue gas heat exchanger is easily to produce ash. To develop an efficient heat transfer element with self-cleaning function and extended heating surface, calcareous dust has the characteristic of high concentration. The characteristics of the physical, chemical and external working process of exhaust dust are studied. The physical and chemical properties of the particle size distribution, appearance and chemical composition of the ash are studied by using scanning electron microscopy, XRD and other instruments. Experimental research on the properties of heat transfer elements is carried out. The results indicated that the surface of lime dust ash have many holes with different sizes, and the particle structure is compact, it is easily to produce physical deposition to form loose ash. The increase of ash concentration will increase the amount of ash accumulation. The higher the ash concentration in the same time, the larger the ash content, and the sleek surface is more likely to be produced. When the flow velocity of flue gas is large, the amount of ash accumulation is quickly stable, and the increase of gas flow velocity will lead to the decrease of ash content in the windward area and the increase of the ash amount of the leeward area. There is the best flue gas flow velocity makes the minimum deposition of fly ash particles on the surface of the pipe. Increasing the lateral pitch and reducing the longitudinal pitch are beneficial to reduce the ash content.