鼓泡浆态反应器中浸没表面的传热研究

Investigation of heat transfer with an immersed heating element in a bubble column slurry reactor

在内径98 mm的鼓泡浆态反应器内,考察了工艺参数对浸没表面与浆液间的传热系数的影响。浆态反应器轴向装有一个外径20 mm,长120 mm的测量传热膜系数用的铜制元件。为了模拟浆态FT合成反应系统,三相系统由N2、液体石蜡和石英砂(平均粒径53μm、110μm、180μm)或63μm以下的Fe2O3组成。工艺参数变化范围如下:表观气速0.005 m/s^0.08m/s,温度353 K^453 K,压力0.1 MPa^0.8 MPa,固体的质量分数0~20%,初始液位高度625 mm^1 240 mm。本研究使用单孔板、多孔板、烧结金属板三种气体分布器类型。结合实验数据,应用最小二乘法求得各个参数值,得到的无因次传热系数关联式为St=0.179(ReFr)-0.25Pr-0.66,相关指数0.98,最大偏差18%。该关联式可应用于气-液和粒径小于100μm的气-液-固体系。

The effects of process variables on the heat transfer between an immersed heating element surface and solid/liquid mixture were investigated in a bubble column of 98 mm i.d. The reactor was fitted with an axially mounted immersed heater which was made of copper with 20 mm od and 120 mm long. In order to simulate the system of the slurry phase Fischer-Tropsch synthesis, the three phase system was composed of nitrogen, paraffin liquid, quartz sand of mean particle diameter 53 μm, 110μm, 180μm or Fe2O3 powders less than 63μm. Process variables were examined in the following range： superficial gas velocity 0.005 m/s - 0.08 m/s, temperature 353 K - 453 K, pressure 0.1 MPa - 0.8 MPa and solids concentration 0 - 20%. Three types of gas distributor were used in this study. A dimensionless correlation for the heat transfer coefficient is obtained by the leastsquare regress and presented as follows： St=0.179（ReFr）^0.25Pr^-0.66. It fits the experimental data with an average deviation of 18% and can be applicable to both a gas-liquid and a gas-liquid-solid system with small particle less than 100μm.