低碳混合醇分离序列的合成与热集成工艺

为降低低碳混合醇的分离能耗,应用探试法、有序搜索法及调优法合成了一系列分离序列,并利用ASPEN PLUS软件中RADFRAC精馏模块,选用NRTL-RK热力学模型,对合成的各种分离序列进行模拟与优化,得到了各分离序列的工艺参数,设备参数及年总费用(ATC)。在此基础上,把塔间热集成精馏应用于以上得到的最优分离序列中,提出了两种热集成分离工艺并进行了优化计算,得到了相关数据。研究结果表明:热集成工艺具有明显的节能效果和显著的综合经济效益,其中热集成工艺2是分离本体系的最优工艺路线。     

基于标准化矩阵模型的综合能源系统优化方法

针对集成能源系统的优化问题,提出一种标准化的集成能源系统矩阵建模方法并建立了综合能量系统的线性规划模型。在此基础上,实现了综合能源系统的结构优化、设计优化和运行优化。以综合能源效率为目标函数,建立了系统结构优化的数学模型,对区域综合能源系统进行优化结构规划。在满足区域用户总冷、热、电需求的基础上,提出了对同一类型的能量转换设备选择两种或两种以上设备并联运行的建议,进一步提高系统的综合能效和可靠性。针对区域综合能源系统运行优化,以运维成本为目标函数,对区域综合能源系统进行优化运行规划,优化各设备单元的小时运行策略。     

可移动式微型冷热电联产系统热电运行分析

介绍了一种集成可移动式微型冷热电联产系统,该系统采用了16kW的发电机组,集成式热管理器以及热水驱动的硅胶-水吸附式冷水机组,系统在发电的同时,回收发电机组缸套水余热和烟气余热,实现冷、热、电综合供能.对该系统在冬季运行工况下了运行性能进行了试验研究分析,确定了系统的运行规律,及其产生这些运行规律的原因,为认识该系统并对系统实施进一步的优化提供了依据.     

回收DMF的多效热泵精馏工艺研究

针对传统DMF回收工艺存在的高能耗问题,提出多效热泵精馏回收DMF工艺流程。在建立多效热泵精馏的能量平衡模型的基础上,利用ASPEN PLUS软件中的RADFRAC模块和UNIQUAC热力学计算模型,对该回收工艺进行模拟优化计算,确定各种工艺的最佳操作条件。在计算结果的基础上,对提出的各种工艺过程进行技术经济分析,以综合经济效益最佳为目标函数,确定了DMF回收的最佳多效热泵精馏工艺流程。     

考虑消纳风电的区域综合能源系统电转气与储能设备优化配置

电转气(PtG)技术与多类型储能设备相结合,可以大量增加可再生能源的就地消纳,减小系统弃风.针对区域内集成有电、气、热、冷多种能源的综合能源系统,首先对系统进行建模,具体介绍了电转气技术与多类型储能设备的工作原理.其次,以综合能源系统总年费用最低为目标,建立电转气与多类型储能设备的联合优化配置模型,并采用Big-M方法...     

甲醇-醋酸乙烯变压精馏工艺的研究与模拟

甲醇-醋酸乙烯属于共沸物体系,目前分离方法主要有共沸精馏、萃取精馏、变压精馏等操作。与共沸精馏、萃取精馏相比,变压精馏具有工艺简单、无需引入第三组分及通过热耦合降低能耗等优点。在验证了NRTL对甲醇-醋酸乙烯模拟计算精确可靠的基础上,采用Aspen Plus软件对其进行分析,确认该体系属于压力敏感体系,提出了甲醇-醋酸乙烯变压精馏工艺流程。利用灵敏度分析工具分析了理论塔板数、进料位置、回流比及侧采位置等工艺参数对该工艺分离效果的影响,优化后的工艺参数为:减压塔28块理论板,进料位置为第12块板,回流比为0.6;加压塔27块理论板,进料位置为第14块板,回流比为0.575,侧采位置为第23块板。模拟计算结果表明,变压精馏可以有效分离甲醇-醋酸乙烯,甲醇质量分数可达99.89%,醋酸乙烯产品质量分数可达99.61%,与原萃取精馏工艺相比,该工艺可节省蒸汽9.07t/h,可减少废水20.75t/h。     

催化裂化干气制乙苯装置苯耗高的原因分析及改进措施探讨

从原料组成、反应产物吸收稳定系统、精馏分离过程等方面分析了大连石化公司催化裂化干气制乙苯装置苯耗较高的原因。总结了历年来在降低装置苯耗方面所采取的措施,即加强对原料催化裂化干气及苯质量指标的监控,优化烃化／反烃化反应控制,优化吸收稳定系统及精馏分离系统。分析了制约装置苯耗进一步降低的主要因素。提出了进一步完善催化裂化干气制乙苯第二代技术和利用催化裂化干气制乙苯第三代技术对装置进行改造的两种进一步降低苯耗的设想方案。     

基于LE-ELM的锂电池热过程时空建模方法北大核心CSCD

锂电池管理系统对于锂电池的效率、寿命和安全至关重要,而电池管理系统对电池的控制、热管理和故障诊断等都需要依赖于准确的电池热过程模型。然而锂电池热过程属于一种具有强非线性特征的分布参数系统,电池内部的温度分布是时空耦合的,并且具有无限维的特性,使得建模存在很大的困难。针对上述问题,本工作提出了一种基于LE-ELM的锂离子电池热过程建模方法。首先使用基于拉普拉斯特征映射(laplacian eigenmaps,LE)的局部非线性降维方法构建空间基函数,以表征系统固有的非线性拓扑特征;利用所得的基函数进行时空分离,获得原始数据的低阶时序表达;然后用极限学习机(extreme learning machine,ELM)以时间系数和对应的电流电压输入信号来近似低阶时序模型。最后集成辨识出的ELM模型与空间基函数,通过时空综合重构出锂离子电池的全局时空模型。为验证算法的有效性,使用所提出的方法对三元软包锂电池热过程进行建模。     

基于神经网络的超临界机组过热汽温设定值优化补偿

基于历史运行数据对过热器喷水减温系统特性进行神经网络建模,在不改变机组原过热汽温控制逻辑和PID参数的前提下,采用基于预测模型的前馈补偿和反馈补偿相结合的策略,在控制回路的顶层对过热汽温设定值进行实时优化补偿,以改善过热汽温控制效果,并借助600 MW超临界机组仿真机进行仿真试验研究.结果表明:采用设定值优化补偿方案可明显提升过热汽温的控制品质,验证了优化方案的有效性.     

分壁精馏技术进展

分壁精馏技术作为一种完全热耦合型的分离过程,具有节能降耗的显著特点。本文首先从分壁精馏技术的出现与发展、分离过程、技术关键和适用范围四个方面作了详细介绍。分壁精馏技术作为一种全新的分离技术,其计算方法、控制方法和结构设计是该技术的三个关键因素,本文分别对其研究现状和存在问题作了详细的阐述,并结合现有的工业应用案例介绍了该技术在不同领域的应用进展,最后指出国内应该加快技术的工业化应用进程,并积极进行知识产权的保护。     

Design of heat integrated distillation systems for a light ends separation plant

This paper presents an industrial case-study: the synthesis of partially thermally coupled and heat-integrated distillation systems applied to the light ends separation section of a crude distillation plant. The distillation systems presented in this work employ the thermal coupling and the heat-integration principles to significantly reduce the heat requirements with respect to the traditional simple column train.The work started from the simulation of the existing plant, by which the parameters of the system were identified. Then the possible sequences of simple columns with sharp splits were identified for the considered application, and all the columns of the configurations were designed. The corresponding thermally coupled sequences were obtained by using a simple procedure derived from the literature and the heat-integrated partially coupled configuration (HIPC) was also considered.In order to verify the examined distillation systems, all the simple and complex configurations were simulated by rigorous numerical models. On the basis of the numerical simulations, the energy requirements for each configuration were evaluated. A rating of the different plants was then performed, based on the total annual cost, allowing to identify the best plant configuration. A thermally coupled configuration showed the best performances for the considered separation.     

Energy savings in heat-integrated distillation columns

The heat-integrated distillation column (HIDiC) provides one of the most effective applications of heat-pump technologies to industrial processes. It reinforces a separation process and yields larger energy savings than other methods such as overhead-to-reboiler heat pumps, which involve moving heat between the hottest and coldest points in the distillation column. A simulation study of this column has been applied to the benzene-toluene system to evaluate energy consumption and the required number of stages for comparison with a conventional column. In an example, the total energy requirements were reduced about 60% below those for a conventional column.     

Optimal heat distribution in the internally heat-integrated distillation column (HIDiC)

The internally heat-integrated distillation column (HIDiC) is an interesting separation alternative to the conventional column or the vapor recompression distillation (VRC). In an HIDiC, the influence of heat distribution along the column section has a significant impact on the design and optimization in addition to the compressor pressure ratio. In this work, the optimization of heat distribution in the HIDiC is completely investigated through the application of flowsheet modeling and optimization solver in Aspen Plus. A commercial-scale propylene/propane splitter is used as a case study to illustrate the effect of heat distribution on energy or cost performance. A comparison of the optimum HIDiC structures obtained from different objective functions is discussed. Some optimum HIDiC structures could be evolved into Linde double columns with a side rectifier, which is a common application found in air separation process. This structure is potentially another interesting alternative to the conventional VRC.     

Design of internally heat-integrated distillation column (HIDiC): Uniform heat transfer area versus uniform heat distribution

The internally heat-integrated distillation column (HIDiC) is a complex column configuration which is more energy efficient than the equivalent conventional column or the distillation column with direct vapor recompression scheme (VRC). Exploiting the heat integration between two diabatic sections operating at different pressures of the HIDiC can greatly enhance the energy performance of the system. On the other hand, the design and optimization of HIDiC is more difficult than those of the conventional distillation column or the column with VRC. The former involves many design parameters, and the most critical one is the pressure ratio between both diabatic sections. However, the heat distribution along the diabatic sections is also another significant factor not yet thoroughly investigated. In this work, two typical distribution schemes, i.e. uniform heat transfer area and uniform heat distribution, are studied by applying a novel approach to solve the simulation problem in Aspen Plus 2004.1. The comparison of both distributing schemes is discussed via two widely-used case studies, namely benzene-toluene separation and propylene-propane splitter.     

Planning and optimization of dynamic plant operation

Dynamic optimization is currently gaining attention in the design, synthesis and operation of industrial processes. Recent developments in the optimization algorithms, in the commercial tools and in the computation power of computer systems make it possible for process engineers to optimize the dynamic plant operations. Planning a plant operation can also be made in the scope of optimization. Dynamic optimization is usually used for developing optimal operation policies for new operational situations such as startup procedures, load changes, product changeovers. This paper attempts to give an overview to the methods, available tools and their properties for the planning and dynamic optimization of chemical processes. We will report our experiences in process optimization and show the results achieved in several practical applications: startup for distillation columns with and without sidestreams; heat-integrated distillation columns; multiple-fraction reactive batch distillation. The realization of the developed optimal policies to the real plants shows the benefit and potential of the optimization.     

Estimation and reduction of CO2 emissions from crude oil distillation units

Distillation systems are energy-intensive processes, and consequently contribute significantly to the greenhouse gases emissions (e.g. carbon dioxide (CO₂). A simple model for the estimation of CO₂ emissions associated with operation of heat-integrated distillation systems as encountered in refineries is introduced. In conjunction with a shortcut distillation model, this model has been used to optimize the process conditions of an existing crude oil atmospheric tower unit aiming at minimization of CO₂ emissions. Simulation results indicate that the total CO₂ emissions of the existing crude oil unit can be cut down by 22%, just by changing the process conditions accordingly, and that the gain in this respect can be doubled by integrating a gas turbine. In addition, emissions reduction is accompanied by substantial profit increase due to utility saving and/or export.     

Transient analysis of heat pump assisted distillation systems. 2 Column and system dynamics

A model to simulate the transient behaviour of a heat pump assisted distillation column is presented. The packed bed distillation column is treated as a distributed parameter system with time and space as independent parameters. The column modelling using appropriate basic equations, their application to binary systems, the solution scheme to the model equations and the distillation column simulation algorithm are described. The heat pump simulation algorithm is then coupled with this algorithm and the column transient behaviour with and without heat pump assist is obtained. The results are compared with earlier steady state data in the literature.     

Energy expenditure in the thermal separation of hydrocarbon mixtures using a sequence of heat-integrated distillation columns

The thermal separation of hydrocarbon mixtures is assumed to take place in a sequence of heat-integrated distillation columns (HIDiC) coupled, via a heat exchanger network (HEN), with a refrigeration system. Using the approach based on Pinch Analysis, a procedure is proposed for minimising the compressor shaftwork in the refrigeration system. The theoretical considerations are illustrated by a test example in which a mixture of selected hydrocarbons (methane, ethane, ethene, propene) is separated in a sequence of HIDiC columns coupled with a refrigeration system.     

Design and control of an ideal heat-integrated distillation column (ideal HIDiC) system separating a close-boiling ternary mixture

Despite the fact that a stand-alone ideal heat-integrated distillation column (ideal HIDiC) can be thermodynamically efficient and operationally stable, the application of an ideal HIDiC system to separate a close-boiling multi-component mixture is still a challenging problem because of the possibility of strong interactions within/between the ideal HIDiCs involved. In this work, employment of two ideal HIDiCs to separate a close-boiling ternary mixture is studied in terms of static and dynamic performance. It is found that the ideal HIDiC system can be a competitive alternative with a substantial energy saving and comparable dynamic performance in comparison with its conventional counterpart. The direct sequence appears to be superior to the indirect sequence due to the relatively small vapor flow rates to the compressors. Controlling the bottom composition of the first ideal HIDiC with the pressure elevation from the stripping section to the rectifying section helps to suppress the disturbances from the feed to the second ideal HIDiC. Special caution should, however, be taken when the latent heat of the distillates is to be recovered within/between the ideal HIDiCs involved, because a positive feedback mechanism may be formed and give rise to additional difficulties in process operation.     

Improving energy recovery for water minimisation

A graphical approach for the design of heat-integrated water systems has been proposed to improve conceptual understanding for implications of heat recovery in water systems, as well as to provide systematic design guidelines for selecting most appropriate integrated options in practice. The developed design method aims to fully exploit water reuse potentials between water-using operations, and simultaneously to minimise any potential degradation of energy recovery resulted from water reuse. Graphical representations of heat-integrated water systems and their manipulation have been applied to investigate systematically design interactions, impacts associated with stream merging and splitting, and influences of non-isothermal mixing on heat recovery. Water Energy Balance Diagram has been developed to improve energy recovery in water reuse network. Energy-efficient and cost-effective configuration for heat recovery has been identified, using improved Separate System Approach. The proposed approach significantly reduces both water and energy requirements for single-contaminant water systems.