含油污泥油炸脱水过程中热-质耦合传递分析

以车用废润滑油为油炸介质，对辽河油田含油污泥进行了油炸脱水实验，并对油炸脱水过程中含油污泥的油、水含量及其变化率、体积平均温度及其变化率以及表面对流传热系数随时间的变化进行了量化。根据含油污泥样品脱水速率随油炸时间的不同变化趋势，将油炸脱水过程分为表面水分汽化、壳-核形成、毛细管内水分脱除以及降速干燥4个阶段。研究结果表明，含油污泥样品的脱水速率对其吸油速率有一定影响，在前3个阶段脱水速率越高，相应的吸油速率越低；在第Ⅳ阶段，由于脱水及吸油过程基本完成，含油污泥样品的脱水及吸油速率均呈递减趋势。在含油污泥样品油炸脱水过程中，对流传热系数随时间的变化趋势与其脱水速率随时间的变化趋势基本相同，最大对流传热系数为510 W/(m²·℃)。此外，通过对各阶段含油污泥样品的吸油量及脱水量对比可知，与前3个阶段相比，降速干燥阶段的脱水量较少而吸油量较大，因此在进行含油污泥油炸脱水时，可不进行该阶段操作，以减少废油的吸入量，降低过程运行成本。

Analysis of the Coupled Heat and Mass Transfer During Fry-drying Process of Oily Sludge

The fry-drying method was applied to dry oily sludge from Liaohe oilfield, and spent lubricating oil of vehicle was used as frying medium. The changes of water and oil contents, dehydration and oil uptake rates, average volume temperature and its variation rate, as well as convective heat transfer coefficient of oily sludge sample were investigated along fry-drying time. The whole fry-drying process was catalogued into four stages according to the different variation trends of oily sludge dehydration rate, which were the surface water evaporation stage, core and crust formation stage, capillary bound water drying stage and falling-rate drying stage. The experimental and calculated results demonstrated that between the dehydration rate and oil uptake rate of oily sludge sample expressed an inverse relationship during the former three stages, however, at the forth stage the two variables both decreased. The variation trend of convective heat transfer coefficient (h) in this process was similar to that of dehydration rate, and the maximum h during this process was 510 W/(m²·℃). Moreover, relatively smaller dehydration amount and larger oil uptake amount were observed at falling-rate drying stage than at previous stages. Therefore, the latest stage would be omitted in order to reduce the amount of oil uptake and operation cost.