Investigation of application of extractive distillation method in chloroform manufacture

Transcription

1 Invetigation of application of etractive ditillation ethod in chlorofor anufacture Proceeding of uropean Congre of Cheical ngineering (CC-6) Copenhagen, Septeber 2007 Invetigation of application of etractive ditillation ethod in chlorofor anufacture L.S. Gordeev, M.B. Glebov,.M. Koltova, N.V. Hitrov D. Mendeleyev Univerity of Cheical Technology of Ruia, Dep. Cybernetic of Cheical technol. Procee, Miukaya q., 9, Mocow, Ruia; tel , e-ail fa: Abtract The reearch of a purification proce of chlorofor fro ipuritie by a ethod of an etractive ditillation i ubitted. Coparion the chee of chlorofor purification i eecuted on the bai of two eparation agent: ethylen glycol and 2-phenoyethanol. On the bai of econoical criterion the epediency of uage of the eparation agent 2- phenoyethanol i hown. Keyword: tractive ditillation, chlorofor, atheatical odel 1. Introduction The chlorofor anufactured on the bai of a chlorination of ethane, contain ipuritie of ethane - ethylenic erie and deand pecial tage of purification. The ain difficulty i introduced by eparation of cloely boiling ipuritie, in particular, 1,1 - dichlorethane and ci - dichloroethylene. Soe way of purification of chlorofor are known: 1. A chlorination of ipuritie up to higher-boiling derivative by ece of chlorine with initiation of reaction by a olar lap irradiation [1] or by contact with porou aterial at heightened teperature [2] with the ubequent ditillation. The lack of thee ethod are : it i poible electively to eliinate only ci - dichloroethylene, while at a chlorination of a 1,1-dichlorethane the chlorofor i iultaneouly chlorinated. At finihing of the content of a 1,1-dichlorethane 0,02 % in product the lo of chlorofor up to 50 % can be reached. 2. In coniderable loe of chlorofor reult alo the ethod of purification by reaction of ipuritie with etching acid at the preence of pentachlorated antiony a catalyt with the ubequent eparation of ipuritie by an adorption on olecular ieve. 3. There i a et of ethod of chlorofor purification, where the ulfuric acid in cobination, for eaple, with a foric aldehyde act. In operational anufacture of chloroethane the chlorofor ubject to purification by an oleu (batch proce by duration about 6 hour), then neutralize by alkali liquor and ubject to dewatering by azeotropic ditillation [3]. Thi ethod, a well a previou, reult in loe

2 of chlorofor at all tage of purification. Beide, it deand the conuption of reactant (oleu, alkali), that reult in foration of wate (pent ulfuric acid and pent alkali liquor). 2. The etraction ditillation ethod In thi reearch the ethod of an etractive ditillation for the olution of the indicated proble of purification of chlorofor i offered. For thi purpoe by the author the election of eparation agent i carried out and for the elected eparation agent on the bai of the conducted eperiental reearche the therodynaic odel of a vapour-liquid equilibria in a ulticoponent yte 1,1 - dichlorethane - ci - dichloroethylene - chlorofor - carbon tetrachloride - eparation agent i contructed. With uage of the baic equation of an etractive ditillation the efficiency of elected eparation agent application i deontrated. The bet election agent have appeared the ubtance of glycol cla. On the bae of a vapour-liquid equilibria reearche the election of the eparation agent wa carried out. The calculation of change of a relative volatility cloely boiling coponent at the introducing of the eparation agent wa conducted on an equation [4] ( ) F1 F2 lg = (1) 1 Here i concentration of eparation agent. The function F for a ternary yte coniting fro coponent 1 and 2 given iture and eparation agent ("") i deterined by epreion F = 1 lgγ lgγ 2 + lgγ (2) where γ 1, γ 2, γ - activity coefficient of coponent 1, 2 and eparation agent, repectively. Value of electivity S ( ) S = (3) epree ean increae of a relative volatility coefficient of coponent of conidered binary iture conditioned by preence of the eparation agent. F1 F2 In the table 1, 2 the value of a difference and electivity S calculated on the equilibriu data for two invetigated eparation agent ethylen glycol and 2-phenoyethanol are ubitted. It i viible, that the difference of function of tate F i poitive, that peak about fulfilent of the ain diparity of etractive ditillation. The value of electivity S deontrate, that the firt coponent (1,1-dichlorethane or ci - dichloroethylene) at interaction with the eparation agent becoe ore volatile, than, if the eparation agent wa not. In work the dependence of activity coefficient fro ole fraction of ethylen glycol and 2- phenoyethanol in binary iture fored by ubtance, preent during an etractive ditillation have invetigated. Fro the obtained data it follow, that in yte a 1,1-dichlorethane - ethylen glycol, ci - dichloroethylene - ethylen glycol and 1,1-dichlorethane - 2- phenoyethanol, ci - dichloroethylene - 2- phenoyethanol of electivity value for ethylen glycol and 2-2

3 phenoyethanol are approiately identical. Allowing electivity value it i poible to draw a concluion, that gaining of ethylen glycol or 2- phenoyethanol to yte a 1,1- dichlorethane - chlorofor and ci - dichloroethylene - the chlorofor hould produce increae of a relative volatility of 1,1-dichlorethane and ci - dichloroethylene. The purpoe of an etractive ditillation i the ditillation of 1,1-dichlorethane and ci - dichloroethylene ipuritie fro chlorofor together with ditillate. At the ae tie it i neceary, that the concentration of chlorofor wa aiu in cube, and the concentration of 1,1-dichlorethane and ci - dichloroethylene wa iniu taking into account the requireent of ipurity level in the chlorofor product. n fig. 1, 2 influence of ditillate flow rate on the content of the ain ipurity of 1,1- dichlorethane and chlorofor in a botto product of etractive ditillation colun (eparation agent 2-phenoyethanol) i hown. F1 F2 Table 1. Value of a difference and electivity S for the ethylen glycol eparation agent. i 1,1-dichlorethane - chlorofor F1i F2i ( i ) i ci - dichloroethylene - chlorofor F1i F2i ( i ) 0,9 0,3537 2,2579 0,0491 1,1198 0,8 0,2812 1,9109 0,0393 1,0948 0,7 0,2162 1,6455 0,0310 1,0742 0,6 0,1597 1,4444 0,0232 1,0550 0,5 0,1110 1,2915 0,0164 1,0385 0,4 0,0717 1,1797 0,0106 1,0248 0,3 0,0408 1,0986 0,0061 1,0139 0,2 0,0182 1,0429 0,0025 1,0059 0,1 0,0047 1,0110 0,0008 1,002 i F1 F2 Table 2. Value of a difference phenoyethanol. and S electivity for the ectioning agent 2- i Ci - dichloroethylene - chlorofor F1i F2i ( ) 0,989 0,2916 1,9571 0,984 0,2939 1,9677 0,976 0,2960 1,9771 0,95 0,2962 1,9780 0,90 0,2968 1,9795 i i 3

4 ole fraction of 1,1-dichlorethane 0, ,0004 0, ,0003 0, ,0002 0, ,0001 0, Flow rate of ditillate, kole/hour Fig. 1. Dependence of the content of 1,1-dichlorethane in cube of etractive ditillation colun fro quantity of ditillate. Mole fraction of chlorofor 0,19 0,17 0,15 0,13 0,11 0,09 0,07 0,05 0, Flow rate of ditillate, kole/hour Fig.2. Dependence of the content of chlorofor in cube of etractive ditillation colun fro quantity of ditillate. 4

5 The nature of the obtained dependence peak about neceity of earch of optiu quantity of ditillate flow rate. At liitation on total quantity of ipuritie in a botto product of etractive ditillate colun, not uperior 0,025 %, the optiu ditillate flow rate ha equal 9 kole/hour. In a fig. 3 the dependence of the content of the ain ipurity of 1,1-dichlorethane in a botto product of etractive ditillation colun fro reflu nuber i hown. A well a it wa neceary to epect thi influencing wa eential. Mole fraction of 1,1-dichlorethane 0, , , , , , , Reflu nuber Fig. 3. Dependence of the content of 1,1-dichlorethane (eparation agent 2-phenoyethanol) in botto product of etractive ditillation colun fro reflu nuber. It i intereting to learn influencing of quantity of eparation agent flow rate on eparation of ipuritie in colun. For thi purpoe quantity of the eparation agent and it input tep wa varied. It wa obtained, that under increaing of quantity of eparation agent flow rate the decreaing of concentration in a botto product both ipurity of 1,1-dichlorethane and chlorofor take place. Therefore quantity of eparation agent flow rate wa deterined by optiization at liitation on ipurity level in grocery chlorofor. (60 kole/hour). For final election of the eparation agent the iulation of three-colun chee for eparation 1,1-dichlorethane - ci dichloroethylene - chlorofor - carbon tetrachloride iture wa conducted. In the firt colun of the chee the eparation of carbon tetrachloride i carried out. In the econd colun the proce of etractive ditillation with eparation of ipuritie of 1,1-dichlorethane and ci - dichloroethylene with ditillate i carried out. At lat, in the third colun after eparation of eparation agent in the evaporator the final clearing of chlorofor fro ipuritie and eparation agent i realized. The atching of two eparation chee with uage of ethylen glycol and 2-phenoyethanol a the eparation agent ha hown, that the grocery chlorofor of deanded quality 5

6 (content of a 1,1-dichlorethane no ore than 0,002 %, and coon ipurity level no ore than 0,025 %) can be obtained in both chee at approiately identical regie and deign paraeter. Therefore it wa epedient to copare the chee with allowance for of cot of the eparation agent. Such atching i lited in table 3. Table 3. Matching of two chee of chlorofor purification on the bai 2- phenoyethanol and ethylen glycol The chee with 2- phenoyethanol The chee with ethylen glycol 1. Cot of heating tea, $/year Heat required for evaporation of iture by heating tea in colun botto: ev i= 1 ( ) Q = ( R+ 1) D y r M N i i i Q ev = , 61, kj/hour Q ev = ,83, kj/hour Cot of evaporation in colun botto, $/year e = $/year e = $/year 2. Cot on eparation agent eparation agent, $/year Total quantity of the eparation agent: eparation agent, kg/year 2 phenoyethanol = 21899, 76 kg/year ethylen glycol = 18386,26 kg/year Cot on eparation agent eparation agent, $/year 2-phenoyethanol = $/year ethylen glycol = $/year Cot on heating tea and eparation agent total, $/year total = $/year total = $/year The obtained outcoe have hown, that taking into account the cot of eparation agent the uage of chlorofor purification chee with 2-phenoyethanol i ore econoically jutified. 3. Concluion 1) The ecological aving technology of chlorofor purification fro ipuritie i invetigated. 2) On the baic equation of etractive ditillation the applicability of 2-phenoyethanol and ethylen glycol a eparation agent in the chee of purification of chlorofor fro cloely boiling coponent are invetigated and jutified. 3) The iulation of three colun chee of chlorofor purification i conducted and the regie paraeter of the chee with application of ethylen glycol and 2-phenoyethanol are deterined. 4) The baic deign paraeter of colun of carbon tetrachloride eparation, etractive ditillation and final purification of chlorofor in the eparation chee with uage of ethylen glycol and 2-phenoyethanol are deterined. 5) Matching the eparation chee on the bai of ethylen glycol, 2- phenoyethanol i conducted and epediency of uage of the eparation agent 2- phenoyethanol alo i revealed. 6

7 Table of ybol: ( ), epre average value of a factor of a relative volatility of the firt and econd coponent in all range of their concentration accordingly in preence and in abence of the eparating agent; F function of tate of a yte (equation (2)); S value of electivity; concentration of the eparation agent in iture; Y activity coefficient. Reference 1. Frederick, C.D., Method of recovering high purity chlorofor and carbon tetrachloride, US patent N , ( ). 2. Kukielka, J., Baru, M., Stajzczyk, M., PL patent N , ( ). 3. Regulation of the functioning anufacture "CHIMPROM". 4. Kogan, V.B., Azeotropic and etractive ditillation, Leningrad: Cheitry, RF (1971). Thi work wa eecuted at partial financial upport of Minitry of education and cience of Ruian Federation. The project РНП