渗透汽化-隔壁塔精馏耦合初步分离费托合成水的过程研究

费托合成水中含有醇、酮、酸等多种高附加值含氧有机物可提取出来作为高附加值产品,但由于费托合成水处量大,共沸体系复杂,通常需要首先对其进行初步分离。设计了直接两塔精馏、渗透汽化-两塔精馏、直接隔壁塔精馏、渗透汽化-隔壁塔精馏四种可供选择的初步分离工艺。根据渗透汽化实验数据在Aspen Plus中构建渗透汽化过程模型并进行模拟,结合灵敏度分析得到精馏过程的最佳工艺参数和模拟结果,并对四种工艺的能耗和有效能损失进行对比。结果表明,渗透汽化-隔壁塔精馏工艺具有明显的节能优势,其能耗较直接两塔精馏可降低15.85%,有效能损失降低45.74%。经渗透汽化膜预浓缩后,溶液的浓度可进入隔壁塔的适宜分离浓度区间,以充分发挥隔壁塔优势。由于渗透汽化所需能量可由余热等低品位热源提供,在余热充足的煤化工领域中可显著降低有效能损失。对于该过程而言,当渗透汽化膜价格低于438元/m²时,渗透汽化-隔壁塔精馏耦合工艺将会表现出较高的经济性。     

Energy efficient control of a BTX dividing-wall column

Dividing-wall column (DWC) is considered nowadays the new champion in distillation, as it can bring substantial reduction in the capital invested as well as savings in the operating costs. This work presents the simulation results of energy efficient control and dynamics of a dividing-wall column (DWC). In order to allow a fair comparison of the results with previously published references, the case-study considered here is the industrially relevant ternary separation of the mixture benzene-toluene-xylene (BTX) in a DWC. Rigorous simulations were carried out in Aspen Plus and Aspen Dynamics. Several conventional control structures based on PID control loops (DB/LSV, DV/LSB, LB/DSV, LV/DSB) were used as a control basis. These control structures were enhanced by adding an extra loop controlling the heavy component composition in the top of the prefractionator, by using the liquid split as an additional manipulated variable, thus implicitly achieving minimization of energy requirements. The results of the dynamic simulations show relatively short settling times and low overshooting especially for the DB/LSV and LB/DSV control structures. Moreover, the energy efficient control proposed in this work allows the operation of DWC with minimum energy requirements or maximum purity of products.     

DWC塔反应精馏法合成乙酸乙酯的工艺研究

实验研究隔离壁塔反应精馏法催化合成乙酸乙酯系列工艺条件,发现该方法有生产工艺简单,条件温和,时间短,产品中副产物少,转化率高,产品质量较好,可以在反应的同时,对产物进行初步分离以便充分有效利用能源,具有较好的经济效益等优点。隔离壁塔反应精馏法合成乙酸乙酯最佳工艺条件：催化剂用量占总投料量的3‰,反应时间2 h,釜温控制180℃,柱温控制110℃,反应床层高度120 cm,乙酸和乙醇投料比1∶1.3（mol比）,回流比1∶3时,乙酸转化率达到98.90%。     

Kaibel隔板塔用于多晶硅还原工段三氯氢硅分离的模拟研究

将Kaibel隔板塔代替常规三塔顺序分离流程用于多晶硅还原工段中三氯氢硅分离。在简捷计算基础上,利用Multifrac模型进行了严格稳态模拟。主要研究了TCS产品和STC产品采出位置、液体分配比和汽体分配比等参数的影响。结果表明：与常规三塔顺序分离流程相比,Kaibel隔板塔可节约能耗26.43%,设备数量大大减少。     

隔壁塔中新型气相分配器的多相流模拟及控制机制

在隔壁塔中加入了以科恩达效应为基础的新型气相分配器并以此建模利用Fluent进行多相流模拟。结果显示在加入液相的情况下，新型气相分配器依然遵循科恩达效应。即气相从分配器的细缝喷出带走其周围气相，在分配器下方形成负压，以此实现调控Rv的目的。类比气相分配器的工作原理，在预分馏塔的塔板之间选择一位置引出一定量气相，此相当于分配器喷出的气相。在主塔段输入相同量的气相，此相当于分配器入口处气相。通过改变输入或输出的气速来调节Rv。模拟结果显示，在温度或浓度控制结构的基础上加入此控制机制可以更好地实现气相分配的效果。     

新型气相分配器对隔板填料塔性能的影响

针对一种新型隔板塔气相分配器，搭建了一套直径600mm、高度5600mm的隔板填料塔冷模实验系统，探究了液相分配比变化对气相分配比产生的影响以及新型气相分配器在隔板填料塔内的分配效果。结果显示：在本实验系统中，液相分配比在1～6之间变化时，隔板塔内气相分配比与液相分配比呈负相关的关系，即液流喷淋密度增大的一侧气体量反而会减少，气相分配比最多可由0.95降至0.6左右，这使得隔板塔远离高效操作区，严重影响了隔板塔内的传质效率；喷淋密度分别为6.27m³/(h·m²)、9.41m³/(h·m²)、15.68m³/(h·m²)时，分配器在隔板填料塔中具有较好的分配性能，可以通过分配器上的调节液位高度，使得喷淋密度增大的一侧，气相流量增多，气相分配比可由0.85调节至1.25左右，加强了气液两相传质，保证了隔板塔的高效运行。     

Design and optimization of a dividing wall column for debottlenecking of the acetic acid purification process

The dividing wall column (DWC) has gained increasing application in a variety of chemical processes because of its potentiality in energy and capital cost savings in multicomponent separations. The main objective in this work is investigation of its use for removing the bottleneck phenomenon within the column when increasing the throughput of an existing distillation process, particularly, the acetic acid (AA) purification process. Optimal column sequence design, involving both conventional and DWC, is considered. The internal recycle flow distribution around the dividing wall was investigated as a primary optimizing variable. Several column arrangements were analyzed to show that the DWC requires less investment and energy costs than conventional distillation, the Petlyuk column, or the prefractionator arrangement.     

分壁式精馏塔分离醇类三元物系的实验研究

自行设计分壁式精馏塔用于分离乙醇-正丙醇-正丁醇三元物系,并获取最优的操作条件。当进料中乙醇-正丙醇-正丁醇的质量比为1∶3∶1,回流比为7,液体分配比为1∶3,气体分配比为1∶1时,实验的分离效果最佳,塔顶产品中乙醇的质量分数为98.15%、侧线产品中正丙醇的质量分数为95.67%、塔釜产品中正丁醇的质量分数为94.77%。     

Optimization and control of vertical double wall dividing-wall column for separating a quaternary system

In this paper, the new separation structure (VDWDWC) for separation of a quaternary system is proposed for the first time, which has lower energy consumption and higher separation efficiency than the traditional three-column and Kaibel column. Sensitivity analysis and response surface optimization (RSM) are applied to the structural design and parameter optimization of VDWDWC. In addition, the dynamic control of VDWDWC is also investigated. Specifically, the performances of temperature-composition cascade control (TC-CC) with and without feed-forward ratio control are compared and analyzed. The results suggested that the TC-CC structure can achieve outstanding controllability for VDWDWC, when the feed flow rate and feed composition is disturbed. In particular, TC-CC with feed-forward ratio control has better dynamic response: the maximum deviation was reduced by 53.7%, and the settling times are significantly shortened, while the steady state deviation of product purity was slightly reduced.