Thermal Mode Experiments On Vertical Loading Packing

Aiming at the existence of wall flow effect, large scale fluid uneven distribution and amplification effect caused by radial fluid flow in packing tower, thermal mode experiments on vertical loading packing were conducted.In industrial scale distillation column with diameter of 800mm, with ethanol water system, total reflux conditions, a research of hydrodynamics and mass transfer performance for vertical loading style and flat loading style corrugated plate packing and metal wire mesh packing have been conducted.The experimental results show that in the same conditions per meter packing pressure drop of vertical loading corrugated plate packing was reduced by an average of 36.52% compared to flat loading one, pressure drop of unit theoretical plate was reduced by an average of 28.24% and height equivalent to a theoretical plate increased by an average of 18.15%; The change of per meter packing pressure drop and pressure drop of unit theoretical plate between vertical loading wire mesh packing and flat loading one were not obvious, but height equivalent to a theoretical plate increased by an average of 10.99%.To design the current vertical loading packing, the ordinary structured packing was divided into eight mass transfer units. The units are independent of each other, and equivalent to eight small packing tower. If radial flow of liquid could be cut off by this, the problem of fluid uneven distribution will be solved, amplification effect weakened and mass transfer efficiency improved. However, the experimental results show that mass transfer efficiency of two kinds of vertical loading packing are reduced compared with flat loading packing, which is contrary to our expectation. So the conception of vertical loading packing is inconsistent with the facts.A new type of liquid distributor has been used in the vertical loading packing tower. The quality of distributor distribution was evaluated by Perry method, and results were verified by experimental of hydraulics. The results show that the distribution uniformity of this distributor is good. So uneven initial distribution cannot occur in these experiments.Wall flow mathematical model of vertical loading packing was established through the fluid distribution mechanism analysis. The view is that the problem of radial flow is solved in vertical packing tower, but wall flow has increased by the unitized structure. And the preliminary design does not consider reallocation of liquid in axial direction. All the reasons lead to local non-uniform distribution of liquid, poor condition of gas-liquid contact and decrease in mass transfer efficiency.