结晶精馏耦合流程分离MDI同分异构体的新工艺

提出了一套关于结晶精馏耦合分离MDI同分异构体的工艺流程,该新工艺采用先结晶后精馏,精馏产物再返回结晶器的方法.分别对结晶和精馏流程进行了模拟分析,并从能耗角度对新工艺与原有工艺进行比较.结果表明,该结晶精馏耦合分离MDI同分异构体工艺所得结晶产品中4,4′-MDI纯度达到99%以上时,其能耗仅是真空精馏工艺能耗的1/2～2/7.新工艺工业化后将产生良好的经济效益.     

外环流气泡塔结晶器传递特性与结晶的研究

基于对气泡塔结晶器内弹状流传递特征与结晶分离机理的分析,提出一种新型气泡塔结晶器,即外环流气泡塔层式结晶器.以己内酰胺-环己酮物系为例,通过结晶实验,对其结晶效率、晶层纯度及弹状流参数等进行了研究,并与常规的Rutgers气泡塔结晶器进行了对比.在此基础上,分析了外环流气泡塔层式结晶器结晶分离和操作的原理.     

分步结晶工艺控制的改进探讨

分步结晶工艺目前普遍采用的温度控制法的不足,主要是通过控制结晶器内导热介质慢速降温或升温来操作,对控制系统精度要求高,但不易有效控制结晶器结晶和发汗的速率。因此提出控制换热量直接控制结晶器的思路,并结合精萘生产实际,得到了较为完善的带散热补偿和工艺温差放大的换热速率-温度控制结晶器控制方案。新控制方案能精准稳定、直接有效地控制结晶和发汗速率,提高结晶分离效率,有较好的经济性,值得在分步结晶工艺中推广应用。     

溶液结晶用于分离人造麝香的研究

对酮麝香溶液结晶的分离进行了系统地研究， 给出了全部计算公式， 同时克服了传统结晶器的缺点， 设计了一种可以实现多级分离的结晶器， 并建立了该结晶器的实验装置， 它集结晶、过滤、洗涤于一体。实验结果与计算结果对比令人满意     

结晶法提纯对二氯苯的研究

本研究采用一种新型的结晶器对从对二氯苯和邻二氯苯的混合物中分离对二氯苯的过程进行了研究,结晶器的操作过程是通过晶析与吹洗两个步骤来完成的。这种结晶器与其它类型的结晶装置相比具有结构简单,便于操作,能耗低和操作周期短等特点。本文对结晶温度为-10℃～45℃之间、对二氯苯浓度为40%～95%的对二氯苯和邻二氯苯混合物的结晶过程     

膜结晶技术的发展及其在蛋白质结晶中的应用

膜结晶技术作为一种新兴的分离净化技术近几年得到了较快发展。阐述了膜结晶技术的产生背景、膜结晶器的类型、膜结晶技术的基本过程、原理及其优点,介绍了膜结晶蛋白质的优点及膜结晶技术在蛋白质结晶中的应用情况,最后展望了膜结晶技术的发展前景。     

一种煤化工污水处理、分质结晶工艺的中试研究

针对碎煤气化污水处理存在的生化出水COD、酚、氨氮含量高,结晶杂盐未纯化、分离等问题,提出了碎煤气化污水处理全流程工艺,并利用中试装置对该工艺进行验证。中试装置由生化、回用、膜浓缩和蒸发结晶4个工段组成。试验结果表明,经该工艺处理后:生化出水的COD、总酚、氨氮分别降至67 mg/L,0.025 mg/L和4.25mg/L;回用和膜浓缩段的再生水优于GB50050—2007中关于再生水的水质要求;硫酸钠结晶盐折算成干基后达到GB/T6009—2014《工业无水硫酸钠》的二类合格品标准,氯化钠结晶产品达到GB/T5462—2015《工业盐》的优级标准。试验结果证明中试全流程工艺满足污水处理资源化利用、实现"零排放"的要求,具备很好的工业化价值。     

从煤焦油分离提纯蒽和咔唑工艺改进探讨

溶剂结晶-精馏法是目前从煤焦油中分离提纯蒽和咔唑的比较先进成熟的已工业化工艺,其杂质的脱除主要在溶剂结晶部分,操作步骤多,但杂质分离效果还不是很理想,最终影响产品纯度。通过实验研究,发现结晶物中高杂质母液的滞留是该工艺杂质分离效果难以提高的关键因素。提出了溶剂结晶结合抽滤-精馏法新工艺,给结晶箱组合气液分离器,实现结晶同步抽滤功能,降低结晶物的母液滞留量,可提高分离效果,减少溶剂循环量,提高产品纯度和回收率,降低装置能耗,增加产能,有较好的经济性。     

结晶器保护渣渣膜结构的模拟研究

通过获得现场不同位置及由结晶器渣膜热流模拟仪获得不同时刻的渣膜,对比分析了渣膜的厚度、结晶率、晶体的分布、大小、类型. 结果表明,结晶器渣膜热流模拟仪铜探头浸入45 s时获得的实验室渣膜与现场弯月面附近45 s的现场渣膜厚度和结晶率相当;现场渣膜随位置在晶体分布上演变规律与实验室渣膜随时间的演变类似;现场渣膜与实验室渣膜的晶体的类型相同,但是晶体大小还存在差异. 因此,可以通过结晶器渣膜热流模拟仪方便、有效的模拟实际结晶器内保护渣渣膜的结晶行为.     

PTA装置氧化单元结晶器的模拟研究

利用PRO/II模拟软件,对精对苯二甲酸(PTA)装置对二甲苯(PX)氧化单元结晶器进行了模拟研究,建立了对苯二甲酸(TA)晶体的结晶动力学模型以及第一结晶器、第二结晶器和第三结晶器的模拟模块,并进行了其应用分析。结果表明:模拟结果与设计数据的偏差在可接受的范围内,可以应用于PTA装置的工程设计;利用结晶器模拟模块,可得到结晶器的TA晶体生成量和TA粒径随结晶器温度和体积的变化规律;对于采用的BP-AMOCO工艺的PTA装置,在最优温度和压力条件下以单个结晶器代替串接的3台结晶器进行生产不一定具有优势。     

连续管式结晶器研究进展

结晶是大多数化工生产过程中必不可缺的步骤。目前,大部分结晶过程采用间歇结晶,但间歇结晶的生产模式存在批次间差异、生产成本过高等缺点。因此,连续结晶作为新的结晶模式逐渐成为研究的重点。其中,连续管式结晶器具有较窄的停留时间分布和较高的生产效率等优势,已广泛应用于工业结晶。针对连续管式结晶器研究现状进行了详细介绍,总结了管式结晶器普遍存在的问题和解决方法,并介绍了辅助设备和技术在连续管式结晶器中的应用。最后,总结了管式结晶器的进一步发展方向。     

Separation and purification of two isomorphic steroids by a novel extractive drowning out crystallization

A novel extraction drowning out crystallization technology was brought forward for separation and purification of two isomorphic steroid pharmaceutical intermediates. In this process, extraction and crystallization are conducted in the same crystallizer simultaneously. The two immiscible (partial miscible) liquid phases were achieved by adding water into the toluene–DMF system. The role played by water is both as an antisolvent for a crystallization and a trigger to generate two immiscible phases for extraction. The advantage of this method is that two relative pure product can be achieved in a crystallization process. The experimental result shows a good prospect of this method for industrial separation of the studied two isomorphic steroids.     

熔融结晶的过程强化

熔融结晶作为一种绿色高效的分离技术具有选择性高、能量消耗低、无须溶剂参与等优势,但在结晶理论研究、连续化生产、专用结晶器设计和工业放大等方面仍面临挑战。熔融结晶分离效率受物系性质、原料纯度和晶体生长速率限制。因此,熔融结晶过程的合理设计和过程优化对提高熔融结晶技术的能量和过程效率具有重要意义。基于熔融结晶技术在化工分离过程中的实际需求和应用前景,从熔融结晶过程工艺优化、晶体层生长表面设计、过程工艺耦合三方面论述熔融结晶过程中晶体成核、生长的强化方式,为达到高效率、低能耗的熔融结晶分离过程提供可行性指导。最后,概述了目前熔融结晶技术的主要研究焦点并对发展方向进行了展望。     

Product quality improvement of batch crystallizers by a batch-to-batch optimization and nonlinear control approach

Batch crystallization is one of the widely used processes for separation and purification in many chemical industries. Dynamic optimization of such a process has recently shown the improvement of final product quality in term of a crystal size distribution (CSD) by determining an optimal operating policy. However, under the presence of unknown or uncertain model parameters, the desired product quality may not be achieved when the calculated optimal control profile is implemented. In this study, a batch-to-batch optimization strategy is proposed for the estimation of uncertain kinetic parameters in the batch crystallization process, choosing the seeded batch crystallizer of potassium sulfate as a case study. The information of the CSD obtained at the end of batch run is employed in such an optimization-based estimation. The updated kinetic parameters are used to modify an optimal operating temperature policy of a crystallizer for a subsequent operation. This optimal temperature policy is then employed as new reference for a temperature controller which is based on a generic model control algorithm to control the crystallizer in a new batch run.     

气泡管结晶提纯萘新工艺

引言精萘是制取2-萘酚等多种精细化工中间体的原料．生产精萘是将工业萘中的主要杂质硫茚分离出去．因硫茚和萘的沸点十分接近,用精馏方法分离硫茚很不经济．当今世界上大多利用萘与硫茚凝固点的差异经过结晶来提纯萘,但这些提纯方法存在着某些缺点,例如设备庞大笨重、分离效率低或能耗高等．本文采用参数泵分步结晶新工艺和开发的直立弹状气泡管结晶器提纯制取精萘,则克服了通常方法的缺点．l用于提纯萘的参数泵分步结晶工艺1.1参数泵分步结晶提纯萘的工艺原理参数泵分步结晶工艺是近年来发展起来的新技术．参数泵结晶法提纯萘由结晶、…     

晶体填充床结晶器分离提纯对二氯苯

用设计的晶体填充床结晶器,从对二氯苯、邻二氯苯的混合物系中分离提纯对二氯苯,考察了晶体床层高度、回流比、进料浓度、搅拌转速等操作因素对结晶器分离性能的影响,并分析了结晶器的操作过程.     

Improving the efficiency of gas hydrate crystallization due to the application of gas separation membranes

To improve the efficiency in of the separation and purification of gases by the method of gashydrate crystallization, the possibility of combining it with the membrane method has been studied. A mathematical model has been proposed for the hybrid-membrane gas-hydrate method. The application of membrane methods in gas-hydrate crystallization has been shown to prevent admixtures from concentration in a crystallizer and, thus, to considerably improve the efficiency of the gas separation and purification process. The proposed model of gas separation and purification was used to calculate the ratio of freon-12 purification from nitrogen and oxygen. The application of membrane gas separation with the purpose to prevent an admixture from concentration in a crystallizer was shown to increase the efficiency of freon-12 purification from nitrogen and oxygen via gas-hydrate crystallization by more than an order of magnitude at a high product takeoff (no less than 0.6).     

Effect of sinusoidal Taylor vortex flow on cooling crystallization of L-lysine

An elliptical Couette-Taylor (ECT) crystallizer with a unique sinusoidal Taylor vortex flow was developed to promote the recovery and size distribution of L-lysine crystals in cooling crystallization. When using the ECT crystallizer, the recovery was enhanced to a maximum of 100% with a mean residence time of only 15 min. When comparing the crystallization efficiency, the recovery and size distribution of the L-lysine crystals in the ECT crystallizer were over 33% and 50% higher, respectively, than those in the conventional MSMPR crystallizer and slightly higher than those in the circular Couette-Taylor (CT) crystallizer. This improved crystallization in the ECT crystallizer was explained in terms of the sinusoidal profile of the Taylor vortex intensity. Plus, since the nucleation and growth processes determine the recovery and crystal size distribution, the mean residence time, inner cylinder rotation speed, and feed concentration were all varied to investigate their influence on the crystallization efficiency.     

具有静态混合单元的气泡分步结晶过程研究

在气泡分步结晶工艺基础上 ,开发了静态混合气泡结晶技术来提纯均四甲苯。实验表明 ,将静态混合单元引入传统气泡结晶器后 ,拓宽了有效鼓泡气速范围 ,明显改善了结晶过程气体均布及压强均布等状况 ,强化了传热、传质过程 ,提高了晶体纯度