皂化废碱液蒸发浓缩工艺改进及防垢研究
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摘要
环己酮装置中环己烷氧化成醇酮产物的选择性为75%-85%,形成的氧化副产物小部分随产物进到蒸馏系统形成轻质油和X油,大部分通过氢氧化钠碱洗形成环己烷氧化废碱液排出装置。该废碱液的特点是:排放量大、成分复杂、COD含量高。目前,国内外处理废碱液的方法主要有化学法和焚烧法。化学法虽可以较多地回收废碱液中的己二酸、环己酮、环己醇、戊酸等有机物,但对污染的消除不够彻底,且工艺复杂,设备腐蚀严重,运行成本较高。而焚烧法处理废碱液则具有工艺简单、能够彻底消除污染的优点,但是在蒸发浓缩过程中,由于废碱液的热敏性,容易在加热管内壁面上结成垢,从而严重影响传热和物料流动,影响醇酮装置的正常运行,成为石油化工亟待解决的问题。因此,寻求适宜的防垢措施,解决废碱液蒸发过程中蒸发装置的结垢问题,对环己酮行业具有十分重要的工业价值。
本课题以中石化巴陵分公司的环己烷皂化废碱液蒸发焚烧处理技术为背景,针对环己酮皂化废碱液蒸发浓缩过程中蒸发器的结垢问题,分析结垢成因,提出把原有的自然循环升膜式蒸发器改为强制循环蒸发器,以提高管内物料的流速,降低结垢速度,利于传热和防垢;蒸发器保证有足够的静液柱高度,防止料液在加热管沸腾及垢层形成;添加防垢性能更好的添加剂等防垢措施。通过实验,研究了皂化废碱液蒸发浓缩过程中防垢添加剂对加热管结垢的影响,复配出了防垢性能较好的防垢剂,有效减缓了加热面垢层的形成速度,并对废碱液蒸发过程中添加防垢添加剂的阻垢机理进行了探讨,在废碱液中,防垢剂PAA&PAAS侧重于分散絮凝作用和晶格畸变作用,YH-1则侧重于微团作用和再生-自解脱膜作用,复配后存在较好的协同效应,达到高效阻垢的目的。
本文从防垢角度入手,达到延长设备运行时间和清洗周期,提高蒸发效率,降低处理皂化废碱液成本的目的。为巴陵石化公司实施技术改造,提供依据。
Cyclohexanone and cyclohexanol are now produced by liquidphase oxidation of cyc- lohexane in an industrial scale. However, the production process generates cyclohexanone and cyclohexanol in a total yield of about 75% to 85%. Most of the byproducts are discharged from the reactor in the form of waste water after alkali washing,while the other small part comes to the distilltion system as the light weitht oil and X oil. The waste lye has many characteristics such as a large quantity of discharge, complicated composition and high value of COD. Nowadays, chemical methods or burning are used to treat with the waste lye. Although the chemical method is mainly used to recycle oadipic acid, cyclohexanone, cyclohexanol, valeric acid, etc in the waste lye, cann’t avoid enviroment pollution by organic, and the process is complex, equipment is severely corroded , operating costs is higher. The burning method has the advantages of a simple process, can completely eliminate the enviroment pollution, because of the heat sensitive of waste lye, easily generated fouling in heated tube wall surface during the process of evaporation, which seriously affects the heat transfering and material flowing, and the normal operation of cyclohexanone and cyclohexanol devices, has become a petrochemical questions that need to be solved. Therefore, the search for suitable anti-scaling measures to solve the evaporation device scaling problem during the evaporation process of waste lye, has a very important industrial value of cyclohexanone sector.
In the Baling petrifaction burning technology of cyclohexane saponification waste lye of background, for the evaporator scale formation problem in the process of cyclohexanone saponification waste lye evaporation, we analyze the causes of fouling, bring forward the natural circulation climbing film evaporators instead the forced circulation evaporator, in order to improve material flow and reduce the fouling rate, in favor of heating transfer and scale prevention; The height of the static liquid column of the evaporator must be high enough to prevent the feed liquor from boiling in the heating pipe and forming fouling layer; Add more suitable additives,etc anti-scaling measures. The effect of various scale inhibitors on the retarding scaling of heating surface during the evaporation process of saponification waste lye were studied in this paper, results indicate that the mixture scale inhibitors can effectively retard foulling layer rate of the heating surface, and the scale prevention mechanism of additive during the evaporation process of waste lye was discussed. In the waste lye, scale inhibitors PAA & PAAS focused on the role of dispersion flocculati and lattice distortion, YH-1 mission focused on the role of micro-group and regeneration and selfextrication, achieve the better synergies after mixing.
By adopting the above measures, we can achieve the purpose of lengthening the production time and cleaning period of the equipment, It is propitious to improve saponification waste lye concentration and decrease the production cost. Provide a basis for the implementation technological innovation of Baling Petrochemical com- pany.
本课题以中石化巴陵分公司的环己烷皂化废碱液蒸发焚烧处理技术为背景,针对环己酮皂化废碱液蒸发浓缩过程中蒸发器的结垢问题,分析结垢成因,提出把原有的自然循环升膜式蒸发器改为强制循环蒸发器,以提高管内物料的流速,降低结垢速度,利于传热和防垢;蒸发器保证有足够的静液柱高度,防止料液在加热管沸腾及垢层形成;添加防垢性能更好的添加剂等防垢措施。通过实验,研究了皂化废碱液蒸发浓缩过程中防垢添加剂对加热管结垢的影响,复配出了防垢性能较好的防垢剂,有效减缓了加热面垢层的形成速度,并对废碱液蒸发过程中添加防垢添加剂的阻垢机理进行了探讨,在废碱液中,防垢剂PAA&PAAS侧重于分散絮凝作用和晶格畸变作用,YH-1则侧重于微团作用和再生-自解脱膜作用,复配后存在较好的协同效应,达到高效阻垢的目的。
本文从防垢角度入手,达到延长设备运行时间和清洗周期,提高蒸发效率,降低处理皂化废碱液成本的目的。为巴陵石化公司实施技术改造,提供依据。
Cyclohexanone and cyclohexanol are now produced by liquidphase oxidation of cyc- lohexane in an industrial scale. However, the production process generates cyclohexanone and cyclohexanol in a total yield of about 75% to 85%. Most of the byproducts are discharged from the reactor in the form of waste water after alkali washing,while the other small part comes to the distilltion system as the light weitht oil and X oil. The waste lye has many characteristics such as a large quantity of discharge, complicated composition and high value of COD. Nowadays, chemical methods or burning are used to treat with the waste lye. Although the chemical method is mainly used to recycle oadipic acid, cyclohexanone, cyclohexanol, valeric acid, etc in the waste lye, cann’t avoid enviroment pollution by organic, and the process is complex, equipment is severely corroded , operating costs is higher. The burning method has the advantages of a simple process, can completely eliminate the enviroment pollution, because of the heat sensitive of waste lye, easily generated fouling in heated tube wall surface during the process of evaporation, which seriously affects the heat transfering and material flowing, and the normal operation of cyclohexanone and cyclohexanol devices, has become a petrochemical questions that need to be solved. Therefore, the search for suitable anti-scaling measures to solve the evaporation device scaling problem during the evaporation process of waste lye, has a very important industrial value of cyclohexanone sector.
In the Baling petrifaction burning technology of cyclohexane saponification waste lye of background, for the evaporator scale formation problem in the process of cyclohexanone saponification waste lye evaporation, we analyze the causes of fouling, bring forward the natural circulation climbing film evaporators instead the forced circulation evaporator, in order to improve material flow and reduce the fouling rate, in favor of heating transfer and scale prevention; The height of the static liquid column of the evaporator must be high enough to prevent the feed liquor from boiling in the heating pipe and forming fouling layer; Add more suitable additives,etc anti-scaling measures. The effect of various scale inhibitors on the retarding scaling of heating surface during the evaporation process of saponification waste lye were studied in this paper, results indicate that the mixture scale inhibitors can effectively retard foulling layer rate of the heating surface, and the scale prevention mechanism of additive during the evaporation process of waste lye was discussed. In the waste lye, scale inhibitors PAA & PAAS focused on the role of dispersion flocculati and lattice distortion, YH-1 mission focused on the role of micro-group and regeneration and selfextrication, achieve the better synergies after mixing.
By adopting the above measures, we can achieve the purpose of lengthening the production time and cleaning period of the equipment, It is propitious to improve saponification waste lye concentration and decrease the production cost. Provide a basis for the implementation technological innovation of Baling Petrochemical com- pany.
引文
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[3]何建辉.一种皂化废碱液蒸发浓缩干燥的方法[P].CN 1293223,2001-05-02.
[4]谢方友,刘建青,王峰涛,等.用于环己酮皂化废水浓缩中的蒸发方法[P].CN:1415554, 2003-05-07.
[5]宋星星,黄敬,傅送保等.一种蒸发环己烷氧化废碱液的方法[P].CN 1336331,2002-02-20.
[6]张家森,姜雨土.皂化废碱液蒸发浓缩技术的改进[J].化工生产与技术,2006,13(3):59-61.
[7] Yiantsion S G, Karabelas A ,J .F ouling of Tube Surfaces: Modeling of Removal Kinetics[J]. AIChE. 1994 , 40(11): 1804-1813.
[8]杨善让,徐志明.换热设备的污垢与对策[M].北京科学出版社,1995.
[9]孔凡谦.碱液冷却器结垢原因及防范措施[J].化肥设计,2005,43(5):44-45.
[10]张光从,张乐.晶体生长[M].北京:科学出版社,1981.
[11] Muller S H. Mitigation of Process Heat Transfer Fouling: An Integral Approach [J] .Int. Chem. Eng. 1984 , 76(2): 97-107.
[12] Garret-price B A. Fouling of Heat Exchanger : Characteristics, Cost, Prevention,Control and Removal[M] . New Jersy: Noyes Publication, 1985.
[13]李裕芳.阻垢剂分散剂控制沉积机理探讨[J].工业水处理,1984,4(4):6-10.
[14] Epstein N, Fouling in heat exchangers in Heat exchanger theory and practi ce[M] . E ds Taborek J&Hesitt G, McGraw-Hill : Hemisphere Publishing Corp , 1983.
[15]杨祖荣.浅谈换热表面的成垢和控制方法[J].化学工程,1991,19(1):19-23.
[16]范冰.己内酰胺生产中皂化废液的处理及综合利用[J].石油化工,1997,26(10):710-714.
[17] Hasson D, Bramson D. Effective of Magnetic Water Treatment in Suppressing CaCO3 Scale Deposition[J] . Chem. Process. Dev. 1985, 24(3): 588-592.
[18] Taborek J A, Ritter R B, Palen J W. The Majour Unresolved Problem in Heat Tran- sfer[J]. Chem. Eng. Prog, 1972, 68(2): 59-67.
[19] Hasson D,Avriel M , Resnick W,Rozenman T and Windreich S. Mechanism of calcium carbonate scale deposition on heat-transfer surface[J]. I&EC Fundamentals, 1968, 7(1):59-65.
[20]陈键生,新型汽一液一固三相流化床蒸发器性能研究〔硕士论文〕,天津大学化工系,1999,4.
[21]贺运初,彭德其等,套管式换热器管间污垢循环流态化在线清洗技术,化工装备技术,1999年第五期.
[22]林瑞泰,沸腾换热,北京,科技出版社,1988.
[23]简茂先,井矿盐信箱,井矿盐技术,第12卷,1981.3, P38.
[24]张少峰,李修伦,赵景利,固体粒子在蒸发器中的防垢性能研究,河北工业大学学报,1998年第四期.
[25]程立新,杨杰辉,换热设备防结垢技术进展,石油化工设备,2000,29(4):22～25.
[26]贾丰春,李自托,董泉玉.工业循环冷却水阻垢剂研究现状与发展[J].工业水处理, 2006,26(4):12—14.
[27]常青,李效红.聚马来酸酐一丙烯酰胺一丙烯酸甲酯阻垢剂开发研究[J].兰州铁道学院学报:自然科学版.2003,22(3):21—27.
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