Optimization Design Of VOC Treatment Process For The Production Of 50,000 Tons Of Tobacco Acetate Tow

Cellulose Acetate has a long history as a filter in cigarettes.Dry Spinning is used as the forming process for the raw materials of acetate fiber in China.After this process,a factory with an annual output of 50,000 tons produces about 35,000 cubic meters of acetone waste gas per hour.Acetone belongs to VOC in our country must be treated before it can be discharged.Because of the economic cost and treatment effect,both at home and abroad choose the recovery method as the treatment method.At present,most factories in China use activated carbon and adsorption-distillation process to treat waste gas.However,in the VOC treatment process,the activity of the adsorbent is sharply reduced,and the energy consumption and material consumption of the process are far greater than the other problems.In order to solve this problem,this paper investigates and analyzes the process and energy consumption of a acetate fiber company,and sets up the adsorption bed experimental equipment according to the actual production process.Using stainless steel column filled with activated carbon to simulate the actual carbon bed,through the standard gas-air ratio,bubbling water to increase humidity to simulate the actual waste gas feed in the process,explored the waste gas humidity,waste gas velocity,water occupying the active carbon position,effects of different regeneration modes of activated carbon and waste gas feeding temperature on adsorption capacity of activated carbon.The results show that: 1)The water content and the position of the water in the activated carbon and the way of regeneration are the key factors affecting the adsorption performance of the activated carbon,and according to the adsorption curve,20% water content is the most economical water content of the activated carbon.2)The influence of the outer water content of the activated carbon on the adsorption is greater than that of the inner water content of the activated carbon.After the desorption,the activated carbon can obviously remove the outer water of the activated carbon by drying,thus enhancing the adsorption effect.3)Because of the competitive adsorption between water and acetone,the gas velocity has little effect on the adsorption capacity of activated carbon.4)The inlet temperature of waste gas can affect the adsorption capacity of activated carbon due to the influence of water content in the activated carbon.5)The results of the study on the steam desorption of Acetone from activated carbon show that the total amount of steam has a great influence on the desorption of Acetone,but the steam temperature and pressure have a little influence on the desorption of Acetone.According to the experimental results,the adsorption bed was improved and the water content of activated carbon was set at 20%,thus the adsorption capacity of acetone on the new adsorption bed was increased by 46% and the life of activated carbon was increased by 1.4 years,about 27,000 tons of steam are saved every year.Deducing the desorption steam pressure to 2 bar improves the stability of distillation and reduces the consumption of circulating water.Secondly,by changing the preheating medium of Dilute Acetone and utilizing the heat of the bottom liquid of the column,the steam is saved by 23,000 tons and the consumption of circulating water by 170,000 tons per year.The MEO is separated from Acetone and water by adding water and resting on the basis of the difference in density and solubility between the collection tank and separation tank.The separated Acetone is re-distilled,resulting in an additional recovery of 76 tons of acetone per year.Also,the MEO was separated and condensed,thus reducing the overhead of the MEO by 85%.Finally,according to the improvement effect,except the project of improving the dilute acetone preheating process can not be carried out due to objective reasons,all other projects have been validated effectively.According to the new process,about 12,000 tons of steam,43,000 tons of circulating water,47 tons of acetone and 83% of the cost of hazardous waste treatment can be saved each year.At the same time,the adsorption time was increased from 60 to 82 minutes to meet the design requirements.