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利用Eulerian-Lagrangian模型耦合飞灰沉积模型对一台化工废液焚烧卧式余热锅炉的飞灰沉积和分布进行数值模拟。Realizable k-模型计算炉膛内部的气相湍流,离散坐标法求解包括飞灰粒子的辐射换热和散射影响的辐射换热过程。基于经验黏附模型和临界动能理论,建立了适用于废液焚烧飞灰粒子的沉积模型,对飞灰粒子黏附/反弹和已沉积粒子的脱落过程进行数值预测。结果表明,粒子尺寸是影响沉积率以及沉积分布的主要因素。大粒子在惯性作用下主要沉积于凝渣管排迎风侧,而小粒子由于热泳、湍流波动的影响能够沉积于换热管的迎风和背风侧。此外,随着管表面温度升高,沉积率逐渐增大。通过对一台废液焚烧卧式余热回收锅炉现场测量表明,模拟结果与实际测量结果吻合较好。
The Eulerian-Lagrangian coupled model of fly ash deposition was used to simulate the fly ash deposition and distribution in a horizontal waste heat boiler with chemical waste liquid combustion. The Realizable k-model calculates the gas-phase turbulence inside the furnace, and the discrete coordinate method solves the radiation heat transfer process including the radiation heat transfer and scattering of the fly ash particles. Based on the empirical adhesion model and the theory of critical kinetic energy, a deposition model suitable for waste liquid incineration fly ash particles was established, and the numerical predictions of the adhesion / rebound of fly ash particles and the detachment of deposited particles were carried out. The results show that the particle size is the main factor affecting the deposition rate and sedimentary distribution. Under the action of inertia, the large particles mainly deposit on the windward side of the coagulant tube while the small particles can be deposited on the windward and leeward sides of the heat exchange tube due to the influence of the thermophoresis and turbulence. In addition, the deposition rate increases as the tube surface temperature increases. The field measurement of a horizontal waste heat recovery boiler for waste liquid burning shows that the simulation results are in good agreement with the actual measurement results.