气化炉辐射废锅内多相流场和温度场的数值模拟

Numerical Simulation of Multiphase Flow Field and Temperature Field in a Gasification Radiant Syngas Cooler

通过直接数值模拟的方法对实际气流床煤气化辐射废锅内三维多相流流场和温度场进行了模拟。连续相流场采用Realizablek-ε湍流模型求解,而颗粒相采用基于随机过程的随机轨道模型,并采用双向耦合算法计算两相间的相互作用。温度场计算肘基于灰气体加权和模型与离散坐标法相结合的方法求解热辐射方程,同时考虑了煤渣颗粒的热辐射和散射影响,利用Ranz-Marshall关系式计算气固相间对流换热作用。结果表明:辐射废锅顶部存在一火炬状入口射流,其长度随中心流道的缩小而缩短;辐射废锅顶部、底部以及入口射流周围各自存在不同形状回流区;整体温度随鳍片水冷壁面积的增加而降低,但鳍片宽度过大可能造成水冷壁灰渣沉积堵塞;不同水冷壁布置方式的计算结果与实际测量值基本吻合。

The direct numerical simulation method was applied to an industrial scale entrained flow coal gasification radiant syngas cooler （RSC） to simulate three-dimensional multiphase flow field and temperature field.The realizable k-ε turbulence model was employed for calculating gas flow field while discrete random walk model was applied to trace of the particles,and the interaction between gas-particles was considered by two-way turbulence coupling model.The radiative properties of syngas mixture were calculated by weighted-sum-of-gray-gases （WSGG） model.The Ranz-Marshall correlation for Nusselt number was used to account for convection heat transfer between gas phase and particles.The discrete ordinates model （DOM） was used for modeling of the radiative heat transfer,and the effect of ash/slag particles on radiative heat transfer was considered.The results show that a torch shape inlet jet is formed in RSC,and its length decreases with the diameter of central channel.The recirculation zones appear around inlet jet,top and bottom of RSC.Overall temperature decreases with the heat transfer surface of fins.But the risk probability of slagging will increase with the heat transfer surface of fins.The model was validated by comparison with the industrial plant measurement data.