应用降膜结晶法将十二烷二酸从同系物中分离及精制

Separation and purification of dodecanedioic acid (DDDA) from its homologous compounds were studied experimentally by falling film crystallization (FFC). The influences of various operation parameters, including crystallizing time, flow rate of melt and temperature of glycerine bath, on purity of DDDA and crystallizing rate were investigated. Over 99% (by mole) DDDA was obtained for a feed composition of 96% (by mole). The main factors affecting the separation efficiency are flow rate of melt and temperature of glycerine bath. The crystallizing layer of DDDA was further purified by sweating and blasting. A set of optimized operation data are provided for better understanding the mechanism of heat and mass transfer in FFC, and for further industrial application of DDDA purification process.     

降膜结晶法精制对苯二甲酸二甲酯的研究

对苯二甲酸二甲酯 (DMT)是生产聚酯的基本原料 ,由于精制工艺流程长 ,导致DMT成本高 ,降低了竞争力。本文将降膜结晶技术用于DMT的分离精制 ,得到了高纯度的产品 ,讨论了各种操作条件对结晶速度和产品纯度的影响 ,确定了最优操作条件     

用降膜结晶法分离人造麝香的研究

用降膜结晶技术提纯人造麝香,考察了物料循环时间、油浴温度和料液的过热度对结晶过程的影响,分析了发汗温度和发汗升温速率与结晶过程中分配系数及结晶率的关系。综合考察产品质量及生产效率,得到用降膜结晶提纯麝香DDHI的适宜的生产条件。在适宜条件下,对DDHI的质量分数为75％左右的原料进行三级结晶,每级母液及发汗液循环回上一级使用,最后所得产品质量分数大于98％,结晶率达到53％以上。     

十二烷二酸二甲酯粗品的精馏-结晶纯化

采用精馏-结晶法分离以环己酮为原料合成十二烷二酸二甲酯的粗品,探讨了各种工艺条件对结晶分离的影响.结果表明:结晶分离最佳工艺条件为:m(精馏双酯)∶m(甲醇)=1∶0.8～1.5,结晶溶液始温30℃左右,终温5～8 ℃,降温速率2～3 ℃/min,搅拌速度5～25 r/min;结晶母液中甲醇可通过蒸馏回收循环使用,残留双酯返回精馏系统.所得十二烷二酸二甲酯的纯度可达99.5%以上,符合医药中间体、香料等行业的使用要求.     

从歧化松香提取分离脱氢枞酸的工艺研究

以歧化松香为原料,进行了脱氢枞酸分离纯化的新工艺研究。优化工艺条件为:歧化松香与90%乙醇的用量比为0.4 g/m L,反应时间20 min,反应温度65℃,分别用50%和75%乙醇-水溶剂各重结晶4次和3次,脱氢枞酸的得率16.9%,纯度98.9%。     

从歧化松香提取分离脱氢枞酸的工艺研究

以歧化松香为原料,进行了脱氢枞酸分离纯化的新工艺研究。优化工艺条件为:歧化松香与90%乙醇的用量比为0.4 g/m L,反应时间20 min,反应温度65℃,分别用50%和75%乙醇-水溶剂各重结晶4次和3次,脱氢枞酸的得率16.9%,纯度98.9%。     

MWB降膜结晶法精萘装置的工艺及生产

我厂的精萘生产工艺大体可分为三个阶段,第一阶段从50年代至80年代末,精萘生产工艺沿用前苏联技术,即由焦油蒸馏所得的萘油馏分生产压榨菜,菜饼熔化后经酸洗净化和简单蒸馏得产品精萘。由于该工艺存在生产环境恶劣、洗涤需消耗大量酸碱且有外排废液、煤气直接加热蒸馏釜,装置热效率低且不安全以及压榨设备的备品备件奇缺,难以长期维持稳定生产等原因,于1989年停产,并转产工业萘。第二阶段从1989年至1994年,采用双炉双塔工艺,以萘洗混合馏分为原料生产工业萘,不仅较好地解决了上述问题,还极大地改善了操作环境。1992年以来为第三阶段,为提高萘     

对-二甲苯深度氯化产物的结晶法分离及结构研究

根据国标GB／T21845—2008选择结晶所用溶剂为4：1（体积比）的丙酮和水混合溶液，用结晶法对深度氯化的对-二甲苯产物进行分离，分离产率达到82％以上；气相色谱法测定产物为纯度达99．63％的α，α，α，α＇，α＇，α＇-六氯对二甲苯。用紫外光谱（UV）和红外光谱（IR）对分离所得产物结构进行表征。     

结晶法分离精制混合植物甾醇中b–谷甾醇和豆甾醇

利用豆甾醇和b–谷甾醇在正戊醇和环己酮中的溶解性差异以及两种甾醇在环己酮中溶解度对温度的依赖性不同，研究了以正戊醇和环己酮为溶剂，用结晶法从精制植物甾醇中分离豆甾醇和b–谷甾醇的工艺方法. 实验结果表明，以环己酮为溶剂，混合植物甾醇经过3次分级结晶后，b–谷甾醇含量达到87%；以环己酮或正戊醇为溶剂，通过5次重结晶后，豆甾醇含量达到92%.     

用精馏-降膜结晶耦合技术提纯对二氯苯

用精馏-降膜结晶耦合工艺分离对二氯苯。考察了降膜结晶操作中冷却剂温度、发汗升温速率对产品的影响,结果表明,冷却剂的温度为38℃,发汗速率为0. 5℃/min,可使w(对二氯苯)≥99 7%,单程收率>58%。与使用精馏工艺相比,总能耗下降71 7%。     

Freeze Concentratton by Layer Crystallization

ABSTRACT

Layer crystallization in laminar falling films has been studied for freeze concentration applications. A binary mixture of water and sucrose has been tested in order to compare with literature results from suspension crystallizers. The concentration of sucrose in ice, which is a measure for loss of solute. were from 0.4 to 26.5% for bulk concenwlions of sucrose of 5 to 40%. respectively. The time averaged ice growth rates varied from 3. l0-7 l0 3-10-6 m/s. The results are related to expressions for maximum ice growth rate developed from the gradient criteria. Also an expression for maximum ice growth rate from irreversible thermodvnamics is oresented. Althoueh the exwrimental results show that one–step layercrystallization has amuch lower separation effect than suspension crystallizers with washcolumns, multistep layer crystallization could provide an economical favourable freeze concentration process. A multistep process that combines freeze concentration and reverse osmosis is proposed. A case study shows that it is possibleto reduce the investment costs to less than half of existing processes, for dewatering capacity of 700kg per hour. The energy consumption is also reduced.     

萃取结晶过程研究进展

分类讨论了目前萃取结晶技术在无机盐及有机物分离领域中的应用现状、发展趋势和相应的分离原理,概括得到萃取结晶的一般原理。与传统的蒸发、结晶过程相比,萃取结晶技术具有很多优势,必将得到更大的发展。     

Purification of Acetic Acid Wastewater using Layer Melt Crystallization

Abstract

Ice crystalline layers were prepared from a binary eutectic mixture of acetic acid and water using layer melt crystallization. The crystalline layers were obtained under the conditions of the cooling temperature at 269, 268, and 267 K, the feed compositions of 0.5, 1.0, and 5.0 wt% acetic acid, and the cooling rates of 0.1, 0.5, and 1.0 K/min. After crystallization, sweating operations were carried out for various crystalline layers obtained in crystallization. The effect of sweating on the impurity behavior inside crystalline layer was investigated. The crystalline layer formed in higher growth rate was purified more easily by sweating operations. Effective distribution coefficient in the sweating process was in the range of 0.2 to 0.01, which depended on the crystalline layers formed in crystallization process. Eventually, layer melt crystallization can be used for the treatment of acetic acid wastewater.     

Separation of Acetic Acid from Acetic Acid-Water Mixture by Crystallization

Separation of acetic acid from acetic acid and water mixture was carried out by melt crystallization. The effect of the cooling rate, the amount of seeds, the seeding temperature, the sweating rate, and the sweating fraction on the distribution coefficient was investigated. The acetic acid was successfully separated by single-stage melt crystallization. As the sweating fraction is increased, the crystalline layers grown at lower cooling rates are purified more highly. Eventually, the crystallization rate is much more important than the sweating rate. The effective distribution coefficient ranges from 0.01 to 0.25 for the crystal growth rates of 1.2 × 10^?6 m/s to 4 × 10^?6 m/s.     

我公司焦化苯结晶点偏低原因分析及措施

通过原因分析 ,确定影响焦化苯结晶点的主要因素为饱和烃、CS2 的含量过高 ,采取相应分离措施 ,焦化苯结晶点升高 ,确保了焦化苯的一级品率。