Mass Transfer Behavior Of A Novel Composite Packing And Hydrodynamic Characteristics Of A Catalytic Distillation Structured Packing

Gas and liquid flow behavior in distillation packed tower is very complex. By analyzing characteristics of gas and liquid flow in different packings, two types of novel packings were developed. One is a novel composite packing, which is applied to precise distillation process; the other is a catalytic distillation structured packing, which is applied to catalytic distillation process. For the first one, mass transfer characteristics were investigated; for the latter, hydrodynamic behaviors were tested.By analyzing the flow and mass transfer characteristics of the gas and liquid phase in structured and random packing, a novel composite packing suitable for precise distillation was developed. The main purpose of the development of this kind of packing is to eliminate scale-up effect. The experiment was carried out in a distillation column, with the diameter of 100mm. The novel composite packing tested in the experiment was composed of Mellapak 350Y packing and Dixon rings, and Chlorobenzene/Ethylbenzene were used in the experiment, with the spraying density 0.2-1 m3/m2·h, and the velocity of air 0.2-1m/s. Through the experiment, liquid flow distribution similar to that in structured packing was found in the composite packing and it was also found that the mass transfer efficiency of this kind of packing were close to that of the precise distillation packing. There were more than 13 theoretical plates in this kind of packing. By analyzing the mass transfer experimental results, some shortcomings of the newly developed packing were found and strategies to improve them were put forward.In the second part of this thesis, a novel catalytic distillation structured packing was developed by eliminating the shortcomings which was found in a commonly used catalytic distillation packing. Hydrodynamic performance of the newly developed packing was investigated in a 380mm-diameter column. The testing system was air / water, the range of liquid flow rate was 0-25m3/m2·h whereas the gas flow rate range from 0.31 to 2.2m/s. The pressure drop of the packing which commonly used in industry is above 10kPa/m. Besides, the pressure drop and liquid holdup increase exponentially with the spraying density. The experimental results showed that the novel catalytic distillation structured packing could control gas liquid two-phase flow perfectly. In the normal operating conditions, pressure drop was less than 4kPa/m, and there were a linear correlation between the liquid holdup/pressure drop and the spraying density. If this novel catalytic distillation structured packing could be used in industry, production efficiency will be improved dramatically.