应用夹点技术实现换热网络的优化

文章首先介绍了过程能量综合方法夹点技术的基本原理,后在对东北某石化厂常压装置模拟的基础上用夹点技术对其原油换热网络进行了节能改造优化。改造后的换热网络同原有的换热网络相比,节省了加热炉需提供的部分热量,从而节省了大量的燃料油,同时冷却负荷量也降低相同数量,避免了公用工程的双重浪费;而且本着利旧的原则充分利用了现有闲置的换热器;各段和全局的传热温差变化比较均匀,同时换热网络的总传热系数也得到较大提高。     

A novel process configuration for co-production of NGL and LNG with low energy requirement

In this study a novel integrated process configuration for NGL/LNG production is introduced and analyzed. This configuration uses two mixed refrigerant cycles in order to supply the required refrigeration for production of both NGL and LNG. The results showed that not only liquefaction efficiency of the process is considerable (0.414 kWh/kg LNG) but also it can recover the ethane (from a rich typical feed gas (methane 75%, and heavier hydrocarbons 23%)) higher than 93.3%. Four multi stream heat exchangers were utilized, the composite curves of them shows that they have been designed optimally. These heat exchangers perform their role for both targets simultaneously due to the integration of the NGL and LNG processes. Even though this point increases their size, but the total capital costs of the plant decrease. This process can be used for large LNG plants in the natural gas refineries. It can also be said that the overall efficiency will be higher for the leaner feed gases.     

采用双(多)壳程换热器来促进换热网络的进一步优化

文中从过程工业换热流程优化的角度论述了采用双（多）壳程换热器的重要性和必要性,并从单个匹配和整个换热网络两方面进行了理论分析,指出采用双（多）壳程换热器具有降低换热器投资,提高换热网络热回收率和过程系统的能量综合优化化水平等多重效果。     

ACHEMA 2022 – Heat Exchanger

ACHEMA is an international exhibition for innovation and development in the process industry. Heat exchangers are necessary parts of many process engineering plants. This report intends to highlight the presented novelties in relation to heat exchangers at ACHEMA 2022. The trends and challenges of heat exchangers were explored in discussions with exhibitors and through presentations at the congress. The field of application for heat exchangers broadens as well as their performance increases. Existing designs are enhanced, traditional types of heat exchangers are combined, and software is developed based on both traditional models and artificial intelligence. An overview of relevant innovations and developments in heat exchangers is given.     

PTA氧化反应冷凝器传热传质行为分析

针对PTA氧化反应中冷凝器内的醋酸、水和氮气混合蒸气冷凝过程,考虑冷凝过程中惰性气体和气相醋酸-水缔合效应,分析了各级换热器内传热传质行为以及传递对换热器设计的影响。计算结果表明,高溶剂浓度下的冷凝过程是气相在近似相平衡状态进行,可以忽略气相中传递限制,而随着气相中溶剂含量的减少,组分在换热器进口段的传热传质效果对换热面积设计影响尤其明显。     

节能型甲醇精馏工艺研究

提出两种节能型甲醇精馏新工艺。在改进的三塔双效精馏工艺中,加压塔的蒸汽不仅用作常压塔的热源,还同时供给预塔的再沸器。四塔双效精馏工艺在传统三塔流程中新增一个加压塔,它的蒸汽用于预塔的再沸器,新增加压塔的塔顶得到精甲醇产品,塔底排出废水。对两种新工艺进行了稳态模拟,结果表明各换热器的两侧有合适的温差,换热器可以正常工作,对3种工艺的对比表明,改进的三塔工艺比传统三塔工艺节能16.67%,四塔工艺比传统三塔工艺节能16.17%。     

石墨改性聚全氟乙丙烯导热中空纤维及其换热器的研制

塑料换热器在化工废水处理、酸碱盐循环设备等特殊领域具有重大应用价值,近年来得到了极大的发展。为提高换热器的整体换热效果,提高塑料换热器的最高使用温度,采用石墨作为填料,对聚全氟乙丙烯进行填充改性,以此制备出管壁薄、管径小且导热性能优良的复合材料导热中空纤维,将其加工后制作成换热器。重点探讨了石墨添加量及工艺加工条件对中空纤维物化性能的影响规律,并且通过冷热流体流程的变换及流量的改变研究其对自制的换热器总体换热性能的影响及规律。结果表明,利用石墨改性聚全氟乙丙烯复合导热材料制作的中空纤维换热器,价格低廉、体积小质量轻、单位体积换热系数较高且换热性能优异。     

A computerized and integrated approach for heat exchanger network design in multipurpose batch plants

Significant savings in the utility cost of batch plants can be obtained by heat integration. In this study, an integrated mathematical programming approach is developed for the determination of the cost optimal heat exchanger network for multipurpose batch chemical plants. A single step, interactive computer program (BatcHEN) which is developed for the determination of the campaigns (i.e. the set of products which can be produced simultaneously), the heat exchange areas of all possible heat exchangers in the campaigns and finally the heat exchanger network are all discussed. A matrix search algorithm is used for the determination of the campaigns. Heat exchange areas for the possible heat exchangers are found by solving a nonlinear optimization model with a grid search algorithm. Finally the heat exchanger network optimization is modeled as a mixed integer linear programming problem and then solved by the modeling and optimization software GAMS/XA.     

外部热耦合复合精馏塔的经济性与可控性评价

外部热耦合复合精馏塔系统是一种新型的精馏塔系统,通过操作在不同压力下的两个精馏塔的精馏段和提馏段之间的热传递来提高热力学效率。根据精馏段和提馏段热耦合的相对位置不同,外部热耦合复合精馏塔系统可分为对称型和非对称型两种结构。为便于设计和实现,可用外部换热器替代外部热耦合得到简化的结构。本文以乙烯乙烷物系分离过程为对象,通过对外部热耦合复合精馏塔系统建立了静动态模型,采用四点控制的方法,对三种结构的外部热耦合复合精馏塔的经济性和可控性两方面做了分析,证明了非对称型优于对称型外部热耦合复合精馏塔。同时,对使用外部换热器简化外部热耦合结构的方法提供了理论依据和参考。     

基于多元状态估计的热交换器多参数关联预警方法

随着流程工业快速发展及工艺过程复杂程度的不断增加,作为核心装备的热交换器存在有效故障早期预警难的问题。以管壳式热交换器为例,提出一种针对热交换器故障早期预警的新方法。该方法基于工艺流体温度、压力、流量等易测量参数构建、选取表征热交换器传热和流阻性能的监测指标,并引入指数移动平均（EMA）算法进行数据处理与指标动态特征提取;在多元状态估计理论（MSET）的基础上,构建表征热交换器健康运行状态的三维健康记忆矩阵,实现热交换器多变工况的融合,避免工况变化对监测指标的影响,然后针对设备当前运行观测值计算实时偏差,实现热交换器运行状态评估及故障预警;通过统计计算过程中各指标实时偏差贡献率锁定异常参数,实现故障精准定位。实验结果表明,该方法能够实现泄漏量占工艺流体流量1%以上泄漏故障预警及垢层厚度占管径2.2%以上结垢故障预警。     

波纹板换热器的传热过程分析

波纹板换热器由于传热效率高,占地面积少,热损失小等优点,在工业生产中得到了广泛的应用。文章对波纹板换热器的传热过程进行分析,测试了流体流速对换热器传热性能影响。指出在换热器选型时,要综合考虑各个因素,使换热器的传热性能与经济性之间达到优化匹配。     

基于分解算法的功热交换网络多目标优化

功热网络设计问题指在流程设计中对变压和换热过程进行耦合优化设计的问题,以此来提高整体系统的能效并降低成本。前人工作中一般采用数学规划法对功热网络建模优化。然而,由于存在变压过程和换热器面积计算的非线性约束,以及换热匹配的二元变量,整体模型往往是一个高度非凸的混合整数非线性规划模型,难以求解。本文提出一种高效的功热网络优化方法。模型中分别用透平压缩机和换热器实现功热网络中轴功和热的交换。求解过程采用分解算法,主问题中用随机算法对关键变量优化,功和热两个子网络问题中用确定性算法求解。目标函数考虑了经济和环境影响。案例测试对比了不同优化目标得到的结果以及多目标Pareto曲线,验证了所提出方法的高效性。     

基于Kern-Seaton模型结合Capdeville生物膜增长体系建立的微生物污垢模型

为研究换热设备生物污垢的形成过程,将Capdeville生物膜增长体系引入Kern-Seaton模型,建立了一个新的微生物污垢模型。采用铁细菌和管式换热装置对模型进行了实验验证。结果表明：除诱导期外,新建的微生物污垢热阻模型的计算数据和实验数据的相对误差小于20%。     

基于智能预测和机理模型的换热网络清洗决策

原油石化装置的换热器常受到结垢影响,导致换热器性能衰退严重,换热网络性能也会随之衰退,同时换热器之间的耦合关系,导致不同换热器的性能衰退对换热网络整体性能变化的影响不同。以往的清洗决策主要是根据单台换热器性能衰退到一定程度来制定的,这会导致换热网络整体可能处在较差的运行状态。因此,本文提出一种基于智能预测和机理模型的换热网络清洗决策方法,基于换热器的运行数据建立智能预测模型,获得换热器性能变化趋势,结合换热网络的性能模拟模型,进一步获得换热网络的性能变化趋势,从而从换热网络整体性能变化的角度来制定清洗方案。研究表明,对收集到的原油换热器运行数据,建立神经网络预测模型,具有较好的预测精度。通过对原油精馏装置换热网络的案例分析,当HE1、HE2和HE5三台换热器同时发生性能衰退时,换热网络年度公用工程能耗费用将增加12.1%。与传统基于单台换热器性能衰退情况制定的清洗方案相比,从换热网络整体性能衰退角度制定的清洗方案,年度额外公用工程费用减少13.1%,损失费用减少14.1%,年度总费用减少13.8%,而清洗次数仅增加3台次。     

综合性能优化在板翅式换热器设计中的应用

采用综合性能优化设计方法,运用计算机语言编制程序,以单位传热量的可用能损失率最小为目标函数,寻求流动参数的最佳值,利用换热器两侧流动换热过程的流动与换热的准则关系式,在设定挟热热流密度和选定换热器某个结构尺寸的基础上,采用迭代的方式完成燃气．空气单侧翅片的板翅式换热单元的结构参数、流动参数与换热性能的优化设计。     

SMGK型换热器的应用

介绍了SMGK型换热器的开发和应用情况。该换热器采用了静态混合器、折流杆和带导流板传热夹套3项强化传热技术,提高了传热系数,并在合成氨厂作为变换热交换器试用成功。     

Numerical optimization of heat recovery steam cycles: Mathematical model, two-stage algorithm and applications

Most of the advanced integrated energy systems need a heat recovery steam cycle (HRSC), either fired or unfired, that recovers the waste heat from gas turbines and process units in order to generate electric power and supply mechanical power to compressors, heat to endothermic processes, and steam to external users. The key feature of such HRSCs is the integration between the heat recovery steam generator (HRSG) and the external heat exchangers. This paper presents a rigorous mathematical programming model, a linear approximation, and a two-stage algorithm for optimizing the design of integrated HRSGs and HRSCs, simultaneously considering the HRSG together with the heat recovery steam network and the intensive steam cycle variables. A detailed application of the methodology is described for an integrated gasification combined cycle plant with CO₂ capture and results for other interesting plants are reported. A significant efficiency gain is obtained with respect to usual practice designs.     

Design of multiple shell and tube heat exchangers in series: E shell and F shell

Multiple shell and tube heat exchangers in the series are employed to handle the temperature cross in the chemical process industries. Depending on the degree of temperature cross, certain number of heat exchangers (either E or F shell type) need to be connected in series such that the temperature cross in each exchanger is within allowable limit. Determination of the number of exchangers for the given terminal temperatures is essential during heat exchanger design phase. In this paper, using finite difference calculus, modeling has been done to calculate the number of shells required for both E and F shell cases. In addition, equations are developed to determine hot and cold fluid temperature profiles across all heat exchangers. Design procedure is illustrated with the help of a case study and the capital cost of both cases is compared. Issues related to E shell and F shells are also discussed.     

交错螺旋折流板管壳式换热器壳侧传热与阻力性能

对交错搭接螺旋折流板换热器壳侧的流动与传热性能进行了实验研究,着重研究了内插假管及不同螺旋角度对壳程传热和阻力的影响,并与传统弓形折流板换热器进行了对比.结果表明,假管的存在反而使传热综合性能下降,同时,在相同的壳侧流量下,螺旋折流板换热器的壳程阻力和壳侧传热系数均随螺旋角的增大而减少,且小于同样条件下弓形折流板换热器的相应值.与弓形折流板换热器相比,螺旋折流板换热器的特点是单位压降下的壳侧传热系数高.     

Exergy analysis of multi-stage crude distillation units

This paper aims to investigate the multi-stage effect on crude distillation units (CDUs) in thermodynamics. In this regard, we proposed three-, four-, five-, and six-stage CDU processes with all variables constrained to be almost the same except for the number of stages. We also analyzed the energy and exergy to assess the energy consumed by each process. Because additional distillation units would share the processing load and thus prevent products with low boiling points from overheating, the heat demand of the CDUs decreases with increasing stages and thus reduces the heat supply. Exergy loss is considered as a key parameter to assess these processes. When the exergy losses in heat exchangers are disregarded, the three- and four-stage CDUs have lower exergy losses than the five- and six-stage CDUs. When the overall exergy losses are considered, the optimum number of stages of CDUs depends on the exergy efficiency of heat integration.