乙酸乙酯-乙腈萃取精馏的模拟优化

应用化工模拟软件Aspen Plus对乙酸乙酪-乙腈最低共沸物系的连续萃取精馏过程进行了模拟与优化。通过绘制拟二元汽液平衡相图,筛选出合适的萃取剂为二甲基亚砜(DMsO)。确定了双塔连续萃取精馏的工艺流程,并利用灵敏度分析考察了萃取精馏塔的全塔理论板数、原料进料位置、萃取剂进料位置、回流比、溶剂比(萃取剂对原料的体积比)等因素对分离效果的影响。确定的最佳工艺方案为:全塔理论板数为33,原料和萃取剂分别在第26块和第5块理论板进料,回流比为1.5,溶剂比为3。模拟与优化结果为乙酸乙酯.乙腈萃取精馏分离过程的设计和操作提供了依据。     

萃取精馏法分离甲醇/乙酸乙酯/乙酸甲酯共沸物的研究

由于甲醇/乙酸乙酯和甲醇/乙酸甲酯体系均存在共沸现象,因此对于甲醇/乙酸乙酯/乙酸甲酯三元混合物,采用普通的精馏方法很难将甲醇有效分离。本文采用萃取精馏的方法,首先分别比较了不同萃取剂对甲醇/乙酸乙酯和甲醇/乙酸甲酯体系相对挥发度的影响,并选择较为合适的萃取剂。接着利用流程模拟软件Aspen Plus对萃取精馏过程进行了全流程模拟,并对溶剂比、萃取塔理论塔板数、原料与萃取剂进料位置、萃取剂进料温度等因素对分离效果的影响进行了考察,得出了如下较优的工艺参数:萃取塔理论板数为80块,萃取塔原料进料位置为第19块板,萃取塔萃取剂进料位置为第3块板,萃取塔萃取剂进料温度为40℃,溶剂比为3.0;回收塔理论板数为5块,进料位置为第3块板。通过萃取精馏分离工艺,得到的甲醇产品纯度达到0.999以上,其中的羰基化合物质量含量小于20×10~6,符合国标GB338-2011中优等品的标准。     

低浓度DMF废水的热集成回收新工艺

针对普通精馏回收低浓度废水中的DMF能耗高问题,本文提出了6种热集成节能方案,尽可能充分利用各物流的潜热和显热,以期达到降低能耗的目的:1)初始三效精馏工艺;2)增加多级进料预热器的三效精馏;3)四效精馏工艺;4)带热泵的三效精馏;5)单塔热泵精馏;6)改进的单塔热泵精馏。并应用Aspen Plus流程模拟软件对6种节能方案进行了模拟计算。结果表明:对于低浓度DMF废水体系,多效精馏和热泵精馏与普通单塔精馏相比,均有显著的节能效果;增加多级进料预热系统,充分利用物流的潜热和显热,能耗明显降低;四效精馏与增加多级进料预热器的三效精馏节能效果相当;热泵精馏比多效精馏更加节能;改进的单塔热泵精馏最节能,节能率达到79%,每小时仅需3.6t的低压蒸汽,就可处理10t的废水,回收0.5t的DMF。六种节能方案比普通精馏节省约37.1%、47.6%、47.2%、67.9%、73.3%、79.0%的能耗。本文的研究结果对老装置的改造和新装置的设计有一定的指导意义。     

带有热量集成的乙醇-水萃取精馏过程模拟

使用Aspen Plus,首先对乙醇-水萃取精馏过程的7种萃取剂的分离效能进行了模拟比较,结果显示:丙三醇DMSO乙二醇DMF糠醛苯甲醛NMP;接着,以丙三醇为萃取剂,设计了最优的萃取精馏工艺流程,并确定了萃取精馏过程中萃取精馏塔(理论板数:16,回流比:2,原料进料位置:12,萃取剂的进料量:230 kmol/hr和进料位置:4)和溶剂回收塔(理论板数:7,进料位置:3和回流比:3)的最佳工艺条件;最后,本文还利用热量集成的方法对系统的废热进行了回收利用,不但节约能耗3262.72 kW,还顺产1 MPa低压蒸汽127 kmol/hr。本研究为乙醇.水萃取精馏分离工艺的工业化提供了理论依据和设计参数。     

丙酮和正己烷共沸体系萃取精馏的模拟优化

利用化工流程模拟软件Aspen Plus以NMP为萃取剂对丙酮和正己烷共沸物系的双塔连续萃取精馏过程进行了模拟计算与优化。确定最优工艺方案为:萃取精馏塔理论板数32,正己烷与丙酮原料进料位置为第25块理论板,萃取剂进料位置为第4块理论板数,溶剂比1.8,回流比1;溶剂回收塔理论板数为7块,回流比为0.6,进料位置为第4块理论板数。萃取精馏塔塔顶产品正己烷含量达到99.84%,萃取剂回收塔塔顶丙酮含量达到99.88%。模拟和优化结果为分离过程的优化操作和设计提供理论依据。     

反应隔壁精馏塔合成乙酸丁酯模拟研究

提出用反应隔壁精馏塔合成乙酸丁酯的工艺流程,以反应隔壁精馏塔代替常规乙酸正丁酯反应精馏塔和乙酸正丁酯产品精制塔,将反应隔壁精馏过程和常规反应精馏生产过程模拟比较,在相同生产能力和产品纯度要求下,反应隔壁精馏塔可降低能耗30%以上,同时可减少设备投资。最后,对提出的反应隔壁生产乙酸丁酯的生产流程进行优化,考察进料位置、采出进料比、副塔液相分配比等因素对乙酸丁酯生产过程能耗和乙酸丁酯产品纯度的影响,并得到适宜的生产操作条件。     

酯交换合成碳酸二乙酯反应精馏工艺的模拟

碳酸二乙酯是一种性能优良的绿色溶剂,在锂离子电池行业中应用广泛。以碳酸二甲酯和乙醇为原料,采用反应精馏工艺生产碳酸二乙酯是目前的主流工艺。由于该反应分为两步进行,因此如何调节工艺参数来提高反应物转化率和产品收率是工业生产中的重要问题。本文以实验得出的动力学方程、UNIQUAC热力学模型,应用Aspen Plus流程模拟软件实现了工业实际反应精馏工艺流程的模拟,详细讨论了进料位置、回流比、进料配比等因素对反应精馏塔性能的影响。结果表明,模拟值与实验值吻合良好,在回流比为4.5～5,混合进料第20块板,进料醇酯比2.5:1,反应段（2～31）块板,空速小于0.18 hr^-1时,反应精馏塔性能最佳。模拟结果对反应精馏合成碳酸二乙酯的工艺设计和过程优化具有重要指导意义。     

催化精馏隔壁塔合成乙酸乙酯的模拟研究

提出应用催化精馏隔壁塔合成乙酸乙酯的新工艺流程,以催化精馏隔壁塔替代常规催化精馏塔及乙酸乙酯塔.利用Aspen Plus模拟软件,模拟催化精馏隔壁塔及常规工艺流程,比较分析2种工艺流程塔内的液相组成分布以及温度分布,并分析液相分配比对催化精馏隔壁塔的影响.证明催化精馏隔壁塔既可节能25.7%,又可降低设备投资费用和操作费用.     

异戊二烯萃取精馏过程的能量分析与节能

萃取剂的选取、用量及萃取精馏流程的集成是影响萃取精馏过程能耗的重要因素。本文对从C_5馏分中萃取精馏分离异戊二烯过程的能耗进行了分析,在ACN为萃取剂条件下,采用常规塔序热集成方案可以节能42．91%,在满足工艺指标的条件下,采用热偶精馏流程可以节省过程能耗58．70%。     

乙酸甲酯催化精馏水解塔过程模拟

分析乙酸甲酯催化精馏水解过程,建立该实验塔物理模型,据此合理简化,建立平衡级与固定床相结合的数学模型及其计算方法.应用该模型方法对本工艺试验的3种催化精馏塔型,分别按2种工况模拟实验过程,得到了与实测数据吻合良好的计算结果.验证了该模型和计算方法的适用性和准确性,能够为过程放大和工艺条件优化提供可靠数据.     

石油馏分三种蒸馏曲线数学模型的研究

石油馏分三种蒸馏曲线换算的经验计算图表,依然是炼油工业设计、生产和科研中广泛使用的计算方法。但文献中有关石油馏分三种蒸馏曲线相关模型形式复杂、相对误差大,只能单向换算。本文研究了石油馏分的恩氏蒸馏曲线分别与实沸点蒸馏曲线、平衡汽化蒸馏曲线各段温差关系图之后,提出一个形式简单、误差相对小、能双向换算的新数学模型。结果表明:其计算结果与该曲线给出的数值吻合好,计算准确度高,明显优于前人的模型。     

利用压力影响恒沸点由反应精馏精制THF

研究压力如何影响恒沸点,探索改变操作压力由反应精馏精制四氢呋喃（THF）可行性,模拟计算考察了压力对THF／水体系恒沸点的影响,结果表明体系压力增加,恒沸物中THF摩尔分率减少。通过两塔在不同压力下操作,利用反应精馏技术可从1,4－丁二醇制备高纯度的THF。     

多变量预测控制软件在加氢分馏装置控制中的应用

针对加氢分馏装置分馏塔工艺特点,重点分析加氢分馏塔所面临的控制问题,采用多变量预测控制软件APC—Adcon,通过实验测试、模型辨识、控制器和切换逻辑设计等工作实现该工业分馏塔系的多变量预测控制,显著提高两塔运行参数的平稳性,有效降低操作人员的操作难度。实际应用的结果表明该多变量预测控制系统可有效地克服干扰、确保工艺参数的平稳运行。通过该系统的应用使在相同的负荷下,燃料气减少5％,显著提高分馏塔的分离能力,组分切割更为合理,航空煤油收率提高0.4％,取得了显著的经济效益。     

Compressing convolutional neural networks with cheap convolutions and online distillation

Visual impairment assistance systems play a vital role in improving the standard of living for visually impaired people (VIP). With the development of deep learning technologies and assistive devices, many assistive technologies for VIP have achieved remarkable success in environmental perception and navigation. In particular, convolutional neural network (CNN)-based models have surpassed the level of human recognition and achieved a strong generalization ability. However, the large memory and computation consumption in CNNs have been one of the main barriers to deploying them into resource-limited systems for visual impairment assistance applications. To this end, most cheap convolutions (e.g., group convolution, depth-wise convolution, and shift convolution) have recently been used for memory and computation reduction but with a specific architecture design. Furthermore, it results in a low discriminability of the compressed networks by directly replacing the standard convolution with these cheap ones. In this paper, we propose to use knowledge distillation to improve the performance of compact student networks with cheap convolutions. In our case, the teacher is a network with the standard convolution, while the student is a simple transformation of the teacher architecture without complicated redesigning. In particular, we introduce a novel online distillation method, which online constructs the teacher network without pre-training and conducts mutual learning between the teacher and student network, to improve the performance of the student model. Extensive experiments demonstrate that the proposed approach achieves superior performance to simultaneously reduce memory and computation overhead of cutting-edge CNNs on different datasets, including CIFAR-10/100 and ImageNet ILSVRC 2012, compared to the previous CNN compression and acceleration methods. The codes are publicly available at https://github.com/EthanZhangYC/OD-cheap-convolution.     

醋酸脱水系统的动态模拟及其控制

通过Aspen Plus软件模拟PTA生产的醋酸脱水共沸精馏系统.稳态模拟结果与现场数据吻合较好.在稳态模型的基础上,设计两种控制方案,利用Aspen Dynamics进行动态模拟,测试这两种控制方案的性能,找出较好的控制方案.模拟的结果对生产操作和控制方案的设计具有重要的指导意义.     

Comparison of pressure-swing distillation and extractive distillation with varied-diameter column in economics and dynamic control

Pressure-swing distillation and extractive distillation are two common methods for azeotrope separation. The economics and controllability are two crucial factors for evaluating the feasibility of a separation process. A varied-diameter column (VDC) was used in the process design to evaluate its economics and controllability. Five azeotropic systems were investigated in order to compare the economics of pressure-swing distillation and extractive distillation with a VDC. Results indicate that pressure-swing distillation with a VDC saves more money than extractive distillation. The dynamic control were evaluated in the acetone-methanol system for both processes with a VDC. The improved control structure for pressure-swing distillation with a VDC can handle ±20% disturbances effectively, while the improved control structure for extractive distillation with a VDC can only handle ±10% disturbances. A comparison of the two methods from the viewpoint of economics and controllability demonstrates that pressure-swing distillation is more suitable when using a VDC.     

常减压装置通用仿真器

本文介绍了仿真器在国民经济发展中的作用和意义，重点讨论了常减压装置通用仿真器的系统设计、软件功能和模型开发。本仿真器能进行常减压装置的开工过程、停工过程、正常操作（２３项）和事故处理（２７项）等培训内容。     

煤焦油蒸馏过程的改进

我国煤焦油资源丰富，但工艺落后，煤焦油分离水平不高，导致后续分离过程负荷大，环境污染程度高。为提高煤焦油分离水平，改善馏分混杂情况，减小环境污染，本文针对原流程的不足，提出2种煤焦油蒸馏改进流程，并以PRO／II为工具，对原流程及改进流程进行了模拟。模拟结果表明，改进流程大大提高了酚、萘的回收率，减轻了馏分混杂程度。从而说明，本文提出的改进流程是可行的。     

Evaluating estimation of gain directionality : Part 2: A case study of binary distillation

The analysis method presented in part 1 of this paper is applied to case studies of binary distillation using the LV and DV control configurations. Based on this we conclude that insufficient estimation of the maximum and minimum process gains for multivariable systems, i.e. gain directionality, is caused by misalignment of inputs and outputs with the corresponding input and output singular vectors, together with a high condition number. This uncertainty has a significant impact on the achievable control performance of multivariable controllers designed from the identified model. For these classes of MIMO systems we show that the uncertainty in the estimate of gain directionality can be reduced by using multi-input perturbations or preferably closed-loop identification as opposed to single-input perturbations. In the case of closed-loop identification it is sufficient to use simple single-loop proportional control, designed from limited qualitative knowledge about the plant. For standard parametric identification commonly used model evaluation techniques, such as degrees of explanation and the quality of the estimated individual transfer functions, are compared to the methodology presented in part 1. As shown, these standard evaluation techniques cannot be used to conclude whether the gain directionality has been adequately estimated. However, using the proposed method tight bounds are obtained on the quality of the estimated gain directionality. Furthermore, we illustrate that the quality of the estimate of gain directionality has a strong impact on achievable control performance, i.e. a significant error in the estimate of the low-gain direction in the plant will cause significant deterioration of the control performance whenever control action is required in this direction. Thus, by using proper scaling of the plant inputs and outputs the method presented analyses the model quality with respect to the control problem at hand.