The Process Research Of Absorption Recovery Of Industrial Waste Gas Of Acetone

In the pharmaceutical, chemical manufacturing and other related industriesproduction, bulk drugs and other latter product were usually traditionally handled bysolvent washing, vacuum filtration, and vacuum drying process. To wash and make themedicines dry, the solvent and water were vacuum-pumped finally. And acetone is themainly used solvent. In the conventional process, large amounts of acetone solvent areevaporated, and the acetone concentration and the emission volume is unstable andintermittent. So far, the recovery method of absorption is mainly continuous. There aresome limitations when acetone vapor laden airs are intermittently discharged. Andthere are no specifically studies for exhaust gas recycling by absorption method whenthey are intermittently discharged. Therefore, according to the characteristics ofacetone emissions, this paper proposed a new absorption-desorption operation—cycleabsorption-desorption process. And according to its intermittent nature, absorption anddesorption were completed in a column.Firstly, according to the material balance and energy balance, this paperestablished a mathematical model of absorber and desorption column, and select NRTLproperty method for the process, which provide data for further research process. Thenbased on the principle of selecting absorbers, part of the absorbers were filtered out.And by means of chemical process simulation software Aspen Plus, the differentabsorption effect was compared. And compared with other absorbents, water is anideal absorbent.Secondly, according to the characteristic of new technology, various factorsaffecting the absorption process was investigated, such as liquid-vapor ratio, platenumber, the position of liquid back to the tower, the ratio of the li quid back to thetower and the temperature of the liquid back to the tower, etc. Via simulation, someof the data has been obtained to meet the emissions standards and consume lessabsorbent. Liquid-vapor ratio was1.5. The number of theoretical plates is12. Theabsorbing liquid was returned to the column in the tenth plate.60%of the absorptionliquid was returned to the column. According to the optimization results, the basicstructure of the absorption column was designed and the diameter of the column is0.7m. Based on this, the number of the desorption column theoretical plate wasdesigned as18.And by simulation, some conclusion were drawn. When the feedentered into the plate from the ninth plate and reflux ratio is2.8, we can get betterseparation and consume less energy. Finally, according to the size of column, theapproximate range of the feed rate was calculated. In view of relatively hightemperature of the bottoms liquid, the feed can be heated by it.Finally, on the basis of steady-state model and the knowledge of control theory,we completed absorption-desorption process dynamic simulation, which by definingthe geometry of unit operations and the relationship between pressure and flow,designing control loop and setting PID controller parameters. We analyzed thedynamic response of the exhaust gas and the Acetone in the absorption liquid whenfeed amount is changed. So did the column top temperature and the purity of theoverhead product. From the feed flow rate change response, it can be concluded thatthe control system can meet the smooth control of the feed flow at the load fluctuationof10%.This dynamic model can be used to guide the actual production.