用能分析在蒸馏装置生产技术中的应用

低碳经济实质是能源高效利用,核心是能量生产技术和减排技术的创新,提出从节能减排、低碳发展的内在规律出发,基于蒸馏装置现场标定数据,应用＂＂的概念,对炼油蒸馏工艺生产过程进行用能过程系统进行计算、总结、分析,找出装置用能的薄弱环节,制定优化改进措施,实现炼油生产装置低能耗、低污染、低排放为基础的生产,提高经济效益,促进低碳经济发展。     

液化天然气过程的热力学分析

利用R K S方程建立了天然气和液化天然气焓火用计算的热力学模型;对 2×104 m3 /d液化天然气液化过程进行了模拟计算;计算了各设备的火用损失和液化过程的火用效率;热力学计算分析结果表明,装置的最大火用损环节是循环压缩机,其次是透平膨胀机和气波制冷机。本装置利用自身所产尾气作为燃气发动机的燃料,进而利用燃气发动机带动循环压缩机,节省了大量电能,回收了排放尾气的能源,有效地解决了压缩机的高能耗问题。     

煤间接液化中费托合成单元装置的分析

在基于PRO/Ⅱ对低温费托合成系统进行模拟及优化的基础上,采用热力学分析方法,对低温费托合成系统进行了量衡算,分析了系统中各主要能耗单元的效率和损失状况。计算结果表明,系统中损失最大的过程是费托合成反应过程。费托合成反应器是损失最大的设备,效率为86.80%,损失占了总损失的85.15%;冷凝液回流泵效率最低,只有6.71%;效率最高的为石蜡收集槽、石蜡泵、石蜡中间槽等,几乎没有损失。采用热力学分析方法可以更准确地揭示系统中各环节和设备的最大损失,为改进设备、节约能源提供目标和对策。     

Thermodynamic efficiency of membrane-assisted distillation processes

Membrane processes are considered as comparably mild separation processes offering the potential for significant energy savings compared with azeotropic distillation processes. Despite higher investment and material costs, they are of particular interest for improving the energy efficiency in the chemical industry. However, energy savings of more than 20%–30% are rarely reported and even a general superiority can be disputed. To further elucidate this controversial, the current study pursues a quantitative assessment of the thermodynamic efficiency of pervaporation and vapor permeation processes with stand-alone distillation and hybrid membrane-assisted distillation processes for the separation of azeotropic mixtures. The results confirm the case-dependent potential of distillation processes to outperform membrane-assisted separations in terms of energy efficiency, considering proper heat integration. Although energy efficiency is becoming significantly important, it should be considered in the context of economic performance to determine an optimal trade-off and to select the best process alternative during conceptual process design.     

复杂精馏塔的用能分析法

针对多组分分离复杂精塔的用能分析,结合精馏原理和夹点分析方法,采用塔的总曹线描述塔内能流沿的分布,并发展了复杂精馏塔的用能分析法。实例应用表明本文所提出的方法是指导分离系统用能优化和热集成的有效工具。     

Distillation Control Structure Selection for Energy‐Efficient Operations

Few studies have been reported concerning the energy efficiency of various distillation column control structures. The choice of an energy‐efficient control configuration by incorporating thermodynamics second law in the selection criteria is described. In addition to a relative gain array for assessing control loop interactions, a relative exergy array is used in evaluating the energy efficiency of various control structures. The preferred control structure should have both good operability and good energy efficiency as distillation columns are the major energy consumer in the chemical industry. The performance of the control structures in the dynamic mode is analyzed in detail. The proposed method is demonstrated on two binary distillation columns: methanol‐water separation and benzene‐toluene separation. Dynamic simulation results prove the efficiency of the proposed distillation control structure selection method.     

精馏塔的柔性分析与柔性改造优化研究

本文对单个精馏塔的柔性分析模型、策略方法进行了研究,建立了精馏塔的柔性分析数学模型,指出精馏过程柔性分析的关键是研究其操作上限,以“三环节”能量流结构理论为基础,建立了精馏塔柔性优化改造的数学模型和策略方法,并给出了应用实例。     

基于塔总组合曲线的内部热耦合精馏塔优化设计方法

基于塔总组合曲线（CGCC）,提出了一种简化内部热耦合精馏塔（HIDiC）结构的图形设计方法。在完成精馏段（或提馏段）单塔段中间换热器优化设置的基础上,结合精馏段与提馏段CGCC的集成图,以HIDiC的可减小过程总（火用）损为目标,确定HIDiC热耦合中间换热器的最优设计。以苯乙烯-乙苯HIDiC为例,计算结果表明,设置中间换热器后,HIDiC可减小过程总（火用）损最大值为1.951 MW,HIDiC的冷凝器、再沸器负荷分别下降63.6%和68.4%;热耦合中间换热器分别设置于精馏段第2、12、和38块塔板,提馏段第20、28和36块塔板,热负荷依次为0.841、1.496和2.053 MW。     

Thermodynamic Modeling and Exergy Analysis of A Combined High-Temperature Proton Exchange Membrane Fuel Cell and ORC System for Automotive Applications

A combined system consisting of a high-temperature proton exchange membrane fuel cell (HT-PEMFC) and an organic Rankine cycle (ORC) is provided for automotive applications in this paper. The combined system uses HT-PEMFC stack cathode exhaust gas to preheat the inlet gas and the ORC to recover the waste heat from the stack. The model of the combined system was developed and the feasibility of the model was verified. In addition, the evaluation index of the proposed system was derived through an energy and exergy analysis. The numerical simulation results show that the HT-PEMFC stack, cathode heat exchanger, and evaporator contributed the most to the total exergy loss of the system. These components should be optimized as a focus of future research to improve system performance. The lower current density increased the ecological function and the system efficiency, but reduced the system’s net out-power. A higher inlet temperature and higher hydrogen pressures of the stack and the lower oxygen pressure helped improve the system performance. Compared to the HT-PEFC system without an ORC subsystem, the output power of the combined system was increased by 12.95%.     

Conceptual Design of Double‐Feed Reactive Distillation Columns

The feasibility and feasible range of operating parameters for double‐feed reactive distillation columns are evaluated, based on the combination of pinch point map analysis for the middle‐section in the compositional space and the feed angle method as an efficient shortcut design method. Limiting bounds for operating parameters are determined where the properties of singular points change. The existence and values of such bounds may vary in double‐feed reactive distillation columns depending on the nature of the system under study. The methodology is illustrated by production of methyl acetate and ethyl acetate. An efficient method is described to identify the most promising candidates of double‐feed reactive distillation columns and to study the design flexibility in terms of operating parameters.     

Thermodynamic Analysis of Glycerol Steam Reforming

A thermodynamic analysis of steam reforming of glycerol using the stoichiometric method has been performed. Since the aim of this work is to study product distribution and coke formation in equilibrium, two different models have been proposed: (a) CO as primary product and (b) CO₂ as primary product. Moreover, substantial information regarding the behavior of the different reactions could be acquired. Product distribution at equilibrium has been investigated in a broad range of conditions: temperature (600–1200 K), water‐to‐glycerol feed molar ratio (0:1–10:1), and pressure (1–9 atm). Glycerol conversion results completely over the whole range of the mentioned conditions. Consequently, product distribution at equilibrium is determined by water gas shift (WGS) and methanation or methane steam reforming reactions. Finally, high temperatures and a high water‐to‐glycerol feed molar ratio favor hydrogen production and decrease both methane and coke.     

Second‐Law Based Thermodynamic Analysis of a Novel Heat Exchanger

In the present investigation, second‐law based thermodynamics analysis was applied to a new heat exchanger with helical baffles. The helical baffles are designed as quadrant ellipses and each baffle occupies one quadrant of the cross‐section of the shell side. Experimental tests were carried out with cold water in the tube side with a constant flow rate, and hot oil on the shell side with flow rate range from 4–24 m³/h. The temperatures and pressures for the inlet and outlet of both sides were measured. The heat transfer, pressure drop, entropy generation, and exergy loss of the new heat exchanger were investigated and compared with the results for a conventional shell‐and‐tube heat exchanger with segmental baffles. The computed results indicated that both the entropy generation number and exergy losses of the new heat exchanger design are lower than those of the heat exchanger with segmental baffles, which means that the novel heat exchanger has a higher efficiency than the heat exchanger with segmental baffles, from the second‐law based thermodynamics viewpoint.     

自回流式精馏塔在轻组分精馏中的优势及操作特性

深入分析了自回流式精馏塔与传统精馏设备的区别以及在轻组分精馏中的优势,同时分析了其在生产过程中的操作特性。     

概念与其表达式的热力学一致性研究

指出火用本性上不是严格意义上的状态函数,给出了在无限大环境参考态下多相系统火用函数一般表达式。该表达式可以被推广应用于无限大的热源和物质源,体现了火用定义和火用函数表达式的唯一性和热力学一致性。将火用和“火用变化”严格区分,避免了关于火用概念热力学本性的误解和争论,结束了现行教材中火用的模型、类别和表达式的多样化局面。最后为任意状态下的均相系统火用函数的数值计算提供了一般思路和基本公式。     

概念与其表达式的热力学一致性研究

指出(火用)本性上不是严格意义上的状态函数,给出了在无限大环境参考态下多相系统(火用)函数一般表达式.该表达式可以被推广应用于无限大的热源和物质源,体现了(火用)定义和(火用)函数表达式的唯一性和热力学一致性.将(火用)和"(火用)变化"严格区分,避免了关于(火用)概念热力学本性的误解和争论,结束了现行教材中(火用)的模型、类别和表达式的多样化局面.最后为任意状态下的均相系统(火用)函数的数值计算提供了一般思路和基本公式.     

填料塔在高压蒸馏中的应用

高压蒸馏与真空和常压操作相比,填料塔中的气液均匀分布变得更加困难,并导致气相返混增加,填料分离效率下降,但经过适当的设计,填料塔不但可以提高高压蒸馏的生产能力,而且效率也得到提高。文中介绍高压蒸馏填料塔的特点和近年来的研究进展,并总结了国内外高压蒸馏填料塔新塔设计和老塔改造的成功经验。     

碳二加氢体系热力学分析

对碳二加氢体系进行了较为详尽的热力学分析,得到不同温度条件下各反应的热焓、吉布斯自由能以及反应平衡常数,确定了主要副反应和绿油生成反应,根据计算结果指出,提高反应选择性、降低绿油生成量是碳二加氢催化剂开发所面临的主要难题,而降低乙炔在催化剂表面强吸附物种的数量,是提高选择性、抑制绿油生成的主要手段。     

丙烯腈-乙腈-水热力学分析与萃取精馏过程模拟

应用模拟软件ASPEN PLUS对丙烯腈-乙腈萃取精馏进行模拟。采用NRTL热力学模型计算液相活度系数。模拟计算出的常压下气液平衡数据与文献相比较,较为吻合。通过C_3H_3N-C_2H_3N-H_2O三元物系剩余曲线与液液相平衡图分析了丙烯腈与乙腈萃取分离的可能性及丙烯腈-水共沸物分离的可能性。最后通过模拟计算得到了沿塔各组分浓度和温度分布曲线,均能达工艺分离要求。     

对羟基苯甲酸丙酯的合成热力学分析

由对羟基苯甲酸与丙醇制备对羟基苯甲酸丙酯为一复合反应体系。用基团贡献法计算了该反应体系的标准气相生成焓、气相绝对熵、理想气体热容、气化热等基础热力学数据；并在此基础上，绘出了反应平衡常数随温度变化的曲线。热力学分析结果对实验室研究及工业化生产有一定的指导意义。     

Adsorption of Gallic Acid from Aqueous Solution Using Fixed Bed Activated Carbon Columns

Naturally occuring matter (NOM), a heterogeneous mixture of complex organic compounds, is invariably present in all surface and ground waters. These materials act as substrate for the growth of bacteria in the distribution system. The disinfection of such water by chlorination produces disinfection by products consisting of several halogenated compounds which are toxic and carcinogenic. As gallic acid is the building block of most NOM, its adsorptive removal from water has been studied using activated carbon columns. The operating variables studied are the hydraulic loading rate (HLR), bed depth (Z), and the feed concentration (C_o). The breakthrough curves are S-shaped and the breakthrough time increases with increasing Z and decreases with increasing HLR and C_o. The adsorption increases with increasing HLR and is maximum around HLR = 8 m³/hr/m². The column design parameters such as the critical bed depth and the depth of the mass transfer zone (MTZ) as calculated using the bed depth service time (BDST) approach are found to agree fairly closely with the experimental values. MTZ is smaller for the carbon cloth indicating its better adsorption characteristics. The adsorption column parameters such as the treated volume and the mass of the carbon required for a desired effluent concentration have been determined from the column data.