Abstract:

A novel structure with rhombus heat transfer surface used in the waste heat boiler was researched. Numerical simulation and experimental investigation were conducted to obtain characteristics of ash distribution and deposition. A deposition model was built to predict the stick, rebound and shedding of an ash particle, and the simulation results were compared with traditional staggered and aligned tubes arrangement. The results indicated that the rhombic surface showed obvious advantages in the heat transfer and ash deposition. The deposits were mainly concentrated on the upper left side. Particle deposited on windward side due to the inertial impaction and on leeward side because of pipe wall vortex. The deposition amount of windward side was higher than that of the leeward side. The deposition increased firstly and then decreased with the increase of the particle size under the same velocity. When the gas velocity was 3 m·s^-1 and particle diameter was 5 μm, the ash particle deposition rate was up to 9.49%. For particles of the same size, the deposition rate decreased gradually with increasing velocity.

Key words: ash deposition, heat transfer surface, model, numerical simulation, experimental validation

摘要：

以一种余热锅炉中新型的受热面为研究对象，采用实验研究和数值模拟的方法研究其飞灰沉积特性。建立了菱形受热面飞灰颗粒的沉积模型，对飞灰颗粒的反弹、黏附及脱落过程进行预测，并与叉排管束和顺排管束的含灰烟气流的速度场、温度场和飞灰颗粒沉积率进行比较。结果表明，菱形受热面在换热和飞灰沉积方面优势明显。沉积主要集中于受热面左上部，颗粒由于惯性碰撞在迎风侧沉积。相同速度下，随颗粒粒径增加沉积率先增大后减小，在3 m·s^-1的烟气流速下颗粒直径为5 μm时飞灰颗粒沉积率最高，为9.49%。保持粒径不变，随速度增大沉积率逐渐降低。

关键词: 飞灰沉积, 受热面, 模型, 数值模拟, 实验验证