本文選題：氯甲烷 + 二甲醚�。� 參考：《大連理工大學》2015年碩士論文

【摘要】：氯甲烷是丁基橡膠合成的重要溶劑。在溶劑循環(huán)精制過程中,以尾氣排放掉的氯甲烷約占溶劑總量的十分之一,進一步回收尾氣中的氯甲烷,已成為企業(yè)重點考慮的問題。排放的三股尾氣中鈍化尾氣與其他尾氣組成存在顯著差異,組成中含有大量二甲醚(25mo1%),且與氯甲烷沸點極為接近,難以通過常規(guī)手段分離,所以將其單獨處理；而另兩股尾氣氯甲烷濃度(其一：3.5 mo1%；其二：20 mmo1%)差異較大,根據(jù)這一特點,進行梯級回收處理。因此,本文的工作主要分為以下兩個部分：(1)氯甲烷與二甲醚的沸點非常接近,難以精餾分離,工業(yè)上通常利用濃硫酸與二甲醚的反應來提純氯甲烷,分離費用高,且存在安全隱患。根據(jù)兩種氣體與H+形成氫鍵能力的差別,提出以水為吸收劑脫除氯甲烷中的二甲醚。為了吸收過程的準確模擬與優(yōu)化,利用二甲醚-氯甲烷、二甲醚-水、氯甲烷-水三個二元體系的相平衡數(shù)據(jù)比較了UNIQUAC、NRTL 和 NRTL-RK三種組分活度系數(shù)評估模型的準確性。結(jié)果表明,NRTL-RK模型的評估結(jié)果與實驗數(shù)據(jù)吻合度更高,平均相對偏差小于2.5%。在此基礎(chǔ)上,使用NRTL-RK模型預測三元體系的氣液相平衡,分析了不同溫度和壓力條件下水對氯甲烷和二甲醚的分離系數(shù)和溶解度影響,發(fā)現(xiàn)隨著液相中二甲醚含量的增加,水溶液性質(zhì)逐漸偏向二甲醚,增加了氯甲烷溶解度,導致分離系數(shù)不斷降低,尤其是低溫時較為明顯,并從熱力學角度給出水吸收二甲醚適宜的溫度、壓力范圍。在以上研究的基礎(chǔ)上,設(shè)計以水為吸收劑的吸收-解吸工藝,對鈍化尾氣中氯甲烷進行回收處理。采用Aspen Plus模擬軟件對工藝進行模擬優(yōu)化,考察了吸收塔壓力、吸收劑溫度、解吸塔壓力對二甲醚吸收率、氯甲烷損失率及再生能耗的影響,優(yōu)化結(jié)果表明,氯甲烷回收率達到95.7%,純度為99.1 mo1%,單耗僅為0.016￥·kg-1。此外,水吸收工藝避免了腐蝕性吸收劑濃硫酸的使用,更加安全清潔高效。(2)針對于濃度差異的常規(guī)氯甲烷尾氣,直接混合回收,使得物料返混,分離能耗增加。因此,設(shè)計壓力梯級利用、氯甲烷梯級濃縮的壓縮冷凝-膜-PSA耦合回收流程。其工藝特點：膜分離裝置濃縮低濃度氯甲烷,壓縮冷凝回收高濃度氯甲烷,PSA深度脫除氯甲烷。對工藝進行模擬優(yōu)化,考察了冷凝溫度對氯甲烷吸收率的影響以及膜面積對壓縮冷凝裝置和PSA裝置負荷的影響。結(jié)果表明：膜面積增大,有利于減少PSA裝置負荷,同時可增加壓縮冷凝進氣氯甲烷流量。通過經(jīng)濟效益核算,優(yōu)選膜面積80 m2、冷凝溫度-35℃,可實現(xiàn)回收率為99.25%,放空氣中氯甲烷含量小于40 g/m3,創(chuàng)造經(jīng)濟效益近111萬元。
[Abstract]:Chloromethane is an important solvent in the synthesis of butyl rubber. In the process of solvent recycling refining, the amount of chloromethane emitted from tail gas is about 1/10 of the total solvent, and it has become an important problem for enterprises to recover chloromethane from tail gas. There is significant difference between passivation tail gas and other tail gas components, which contains a large amount of dimethyl ether (25mo1%), and is very close to the boiling point of chloromethane, so it is difficult to be separated by conventional means. However, the concentration of chloromethane (1: 3.5 mo1; 2: 20 mmo1%) in the other two streams of tail gas varies greatly. According to this characteristic, cascade recovery is carried out. Therefore, the work of this paper is divided into the following two parts: (1) the boiling point of chloromethane and dimethyl ether is very close, it is difficult to be separated by distillation. In industry, the reaction of concentrated sulfuric acid and dimethyl ether is usually used to purify chloromethane, and the separation cost is high. And there are hidden safety problems. According to the difference of hydrogen bonding ability between two gases and H, water is used as absorbent to remove dimethyl ether from chloromethane. In order to accurately simulate and optimize the absorption process, the accuracy of the evaluation models for the activity coefficients of UNIQUACU NRTL and NRTL-RK were compared using the phase equilibrium data of three binary systems: dimethyl ether-chloromethane, dimethyl ether-water and chloromethane water. The results show that the evaluation results of NRTL-RK model are more consistent with the experimental data, and the average relative deviation is less than 2.5. On this basis, the NRTL-RK model was used to predict the vapor-liquid equilibrium of the ternary system. The effects of water at different temperatures and pressures on the separation coefficient and solubility of chloromethane and dimethyl ether were analyzed. It was found that with the increase of the content of dimethyl ether in liquid phase, The properties of aqueous solution gradually deviate to dimethyl ether and increase the solubility of chloromethane, which leads to the constant decrease of separation coefficient, especially at low temperature. The suitable temperature and pressure range for water absorption of dimethyl ether are given from the point of view of thermodynamics. On the basis of the above research, an absorption-desorption process with water as absorbent was designed to recover chloromethane from passivation tail gas. The process was simulated and optimized by Aspen Plus simulation software. The effects of absorber pressure, absorbent temperature and desorption column pressure on dimethyl ether absorption rate, loss rate of chloromethane and regeneration energy consumption were investigated. The recovery rate of chloromethane was 95.7%, the purity was 99.1 mol ~ (-1), and the unit consumption was only 0.016 kg ~ (-1). In addition, the water absorption process avoids the use of corrosive absorbent concentrated sulfuric acid, and is safer, cleaner and more efficient. (2) aiming at the conventional chloromethane tail gas with different concentration, the material is remixed and recovered directly, and the separation energy consumption is increased. Therefore, the compression condensing-membrane-PSA coupling recovery process with pressure cascade utilization and chloromethane cascade concentration is designed. The characteristics of the process are as follows: low concentration chloromethane is concentrated in membrane separator, and high concentration chloromethane is recovered by compression condensation. The effects of condensation temperature on the absorption rate of chloromethane and the effect of film area on the load of compression condenser and PSA unit were investigated. The results show that the increase of membrane area is beneficial to reduce the load of PSA unit and increase the flow rate of compressed condensate inlet chloromethane. The optimum film area is 80m2, the condensation temperature is -35 鈩，

本文編號：2066845