Research On A High-efficiency Polypropylene Structured Packing In Carbon Dioxide Chemical Absorption Tower

The post-combustion CO₂ capture is considered the most promising technology,however,the high investment costs restrict its extensive application.At present,the stainless steel packing in the CO₂ chemical absorption tower has a series of problems such as high price,difficult transportation and installation.Choosing low cost polypropylene packing instead of stainless steel packing can greatly reduce the cost.However,the traditional polypropylene packing is poor in hydrophilicity and difficult to be wetted in practical use,which greatly affects the CO₂ absorption effect in the tower.Therefore,it is necessary to improve the current polypropylene packing by hydrophilic modification and develop a more efficient polypropylene structured packing.In the experiment,maleic anhydride grafted polypropylene hydrophilic was chosen as the modifier which was added to the polypropylene raw material through a melt blending modification method.The experimental results show that the addition of the modifier can effectively improve the hydrophilicity of the material.The best hydrophilic modification effect was obtained at the addition of 30wt%,and the static water contact angle of the material was reduced from about 110°to about 80°.Further,the surface embossing method was used to construct porous microstructures on the surface of the material,and the effect of porous structures with different pore sizes on the hydrophilicity of the material was studied.Specifically,a porous structure with a pore size of 200 microns was formed on the surface of the material,and the hydrophilicity of the material surface was greatly increased after the pre-wetting treatment.On the basis of laboratory research,the modified formula and surface embossing method were applied to the production,and a batch of new high-efficiency polypropylene structured packing samples were produced.After that,the performance of these modified packings were tested on the laboratory platform.The experimental results show that the effective mass transfer area of the modified packing increased about 30%,and its hydrodynamic characteristics were superior to the same type of stainless steel packing.In order to have a comprehensive understanding of the properties of modified packings,the effects of packing specific surface area,liquid distribution in the tower and installation angle of packing discs on packing performance were also studied.The experimental results showed that the mass transfer performance of packings with smaller specific surface area decreased,but smaller pressure drop,dynamic liquid holding capacity and greater flooding gas velocity were obtained.When the liquid distribution in the tower deteriorates,the mass transfer performance of the packing deteriorates,but part of the non-uniformity of the liquid flow could be eliminated by the modified packing.When packing’s installation angle became smaller,the relative position of the flow channel in the packing would change as well.The uniformty of the flow would decrease and the changes in the liquid phase flow between the packing disks are more severe,so the mass transfer performance of the packing decreases,and a higher pressure drop was obtained while the liquid flooding gas velocity decreases.In general,the modified polypropylene structured packing greatly improved the mass transfer performance and had a good industrial application prospect.