Dynamic modeling and improvement on ash deposition and thermal-hydraulic characteristics in a waste heat boiler of cement kiln

Ash deposition is the key factor restricting the heat utilization efficiency of a waste heat boiler in the cement kiln. The reasonable design of heat-transfer surfaces is a crucial issue for reducing ash deposition. In this paper, in order to overcome the manufacturing difficulty or unpractical problems of most heat-transfer surfaces, different designs based on the characteristics of the elliptical tube were proposed. To explore the overall performance of these designs, a detailed CFD model is established to study the ash deposition and thermal-hydraulic characteristics, and the dynamic mesh method is adopted to simulate the dynamic growth process of the ash deposited layer. Compared with the reference scheme (case 1), the performance evaluation criteria PEC of the novel design (case 3) in the clean state is improved by 13%, and the fouling thermal resistance and thermal attenuation coefficient are significantly reduced. Therefore, the novel designs that can effectively reduce particle deposition while maintaining easy manufacturing and acceptable thermal-hydraulic performance are applicable to waste heat utilization of dust-laden exhaust gas.

Automated summary

This paper focuses on reducing ash deposition in a waste heat boiler in the cement kiln by improving the performance of heat-transfer surfaces through different designs based on the characteristics of the elliptical tube. A detailed CFD model is used to study ash deposition and thermal-hydraulic characteristics, and the dynamic mesh method is employed to simulate the dynamic growth process of the ash deposited layer. The novel designs effectively reduce particle deposition while maintaining easy manufacturing and acceptable thermal-hydraulic performance for waste heat utilization of dust-laden exhaust gas.