海水脱硫散堆填料塔流体流动及传热研究

Study of the Fluid Flow and Heat Transfer in a Seawater Desulfurization Bulk Packing Tower

在大型可移动式海水脱硫试验台上进行了中试规模的试验,在体积平均法的基础上,结合试验数据获得的压损拟合公式建立了描述散堆填料塔内气、液两相的流动及传热模型;通过计算,获取了在不同液气比下塔内流体速度、孔隙率分布、压力分布及海水温度分布,并就压力损失和海水出口温度与试验值进行了对比,预测值与试验值吻合较好。分析计算结果发现,靠近壁面处存在着显著的壁流现象,其形成原因是近壁面处的孔隙率明显高于中间区域。海水温度在顶部分布较不均匀,靠近壁面处海水温度波动较大,向塔中心处逐渐趋于均匀,沿塔高度从上到下,温度逐渐下降均匀,到塔高一半处基本不再变化(△T<0.1 K),说明在塔高一半处气液间的热交换已基本完成。

On a large-sized movable type seawater desurfurization test rig,a pilot-scale test was performed.On the basis of the volumetric average method,in combination with the pressure loss fitting formula obtained from the test data,a model for depicting the gas-liquid two-phase flow and heat transfer in a bulk packing tower was established.Through calculation,the speed,porosity,pressure and seawater temperature distribution of the fluid inside the tower at different liquid-gas ratios were acquired and the pressure loss and seawater outlet temperature were compared with the test values.The predicted values are in relatively good agreement with the test ones.The analytic and calculation results show that a wall-surface flow phenomenon conspicuously exists in places nearing the wall surface,of which the causes lie in that the porosity nearing the wall surface is obviously higher than that in the central area.The seawater temperature distribution at the top portion is not comparatively uniform while that nearing the wall surface has a relatively big fluctuation and gradually tends to be uniform towards the central area of the tower.From the top to the lower portion along the height of the tower,the seawater temperature gradually decreases and no longer changes(basically) when reaching the half height of the tower(△T<0.1 K),indicating that the heat exchange at the half height of the tower has been basically completed.