非供暖季除盐水制水系统运行方式的优化与改造

现有除盐水制水设备运行方式和除盐水补水方式下,制水设备频繁启停、循环水旁流水利用量十分有限.通过对除盐水补水管道改造实现330MW、660MW除盐水箱互补.优化除盐水制水设备运行方式,从而提高660MW补给水处理的制水量,以期增加循环水旁流水利用量改善循环水水质.     

脱盐水站外排水回收利用技改

东明润邦化工有限公司脱盐水站使用的主要水处理设备包括多介质过滤器、超滤、一、二级反渗透及EDI等装置,对原水进行逐级处理,每经过一级过滤,就会有大量水外排,造成极大的浪费,为了对外排水回收利用,公司对脱盐水站进行了有效的改造,将脱盐水站外排水回收重新利用,一路作为循环水补水,一路去脱盐水站代替新鲜水,节约了大量的新鲜水,目前改造项目使用情况良好。     

改进极值策略的多目标粒子群算法及其在PX氧化过程中应用

提出了一种新的用于求解多目标问题的粒子群算法,该算法采用一种新的全局极值和个体极值选取策略,提升了种群逼近Pareto最优前沿的稳定性和精度,同时为了提升种群跳出局部最优的能力,提出两步变异操作.此外还采用了外部存档存储每一代产生的非支配解,并且使用动态更新的拥挤距离来维持外部存档的规模.然后,通过典型的ZDT系列测试函数对该算法进行评估,并与MOEA/D、NNIA和NSGA-Ⅱ 3种多目标优化算法进行比较.实验结果显示,新算法相较于其他算法具有较好的分布性与收敛性.最后将其应用于PX氧化反应操作优化中,在相同计算成本的条件下,新算法优化后的醋酸和PX燃烧损失明显下降,成本损失大幅减少.     

基于多目标进化算法的对二甲苯氧化反应过程优化操作

针对单目标优化算法在求解优化问题时普遍存在易陷入局部最优的缺陷,本文提出采用基于精英选择和个体迁移的多目标优化方法来求解单目标优化问题,通过对原问题目标进行有效分解,将其分解为多个子目标,通过对多个子目标的优化来扩大搜索范围,加快算法的收敛速度。仿真结果表明,与文献中方法相比,采用多目标方法来求解单目标问题能显著提高算法收敛速度,将其应用于对二甲苯(PX)氧化反应过程的优化操作,在相同计算成本条件下,醋酸和PX燃烧损失明显下降,成本损失大幅减少。     

基于多目标教学优化算法在二甲苯吸附分离过程优化中的应用

以C8芳烃混合物的吸附分离过程作为研究对象, 应用多目标教学优化算法(multi-objective teaching-learning-based optimization algorithm, MOTLBO)对模拟移动床多目标优化问题进行求解。采用TMB方法, 建立了模拟移动床模型, 并对两个典型的模拟移动床多目标操作优化问题进行了优化设计。通过与NSGA-Ⅱ算法的比较, 证明了多目标教学优化算法在求解模拟移动床多目标优化问题上的有效性和优势。此外, 还分析了抽出液流量、抽余液流量以及步进时间等对多目标优化非劣解的影响, 优化结果为模拟移动床分离过程的工艺设计和操作提供了依据。     

除盐水站浓水回收处理及再回用

中海石油中捷石化有限公司通过水平衡测试后对企业用水进行了潜力分析及优化方案研究。结合公司实际情况,决定首先实施除盐浓水回收处理及再回用项目,通过利旧原污水处理中水回用系统的部分除盐设施,节省了大量投资。项目完成后,实现了对公司除盐水站所排浓水的回收处理,回用至循环水系统作补水,节约了大量新鲜水,为公司节水减排工作做出巨大贡献。     

芳烃抽提过程多目标优化

芳烃抽提是芳烃生产过程的重要环节,其生产调优对提高整个芳烃联合装置的效益具有重要意义。基于流程模拟及响应面分析方法,得到了芳烃抽提过程的产品纯度模型及能耗模型。建立了以产品纯度最大化及过程能耗最小化的多目标优化模型。提出了一种改进的自适应加权求和算法,并用于多目标优化模型的求解。求解结果表明新算法在Pareto最优解分布的均匀性上与原算法相当,但求解效率要高于原算法。给出了不同产品等级下的最佳操作参数,采用优化后的操作参数可有效地提高产品纯度并降低过程能耗。提出的多目标优化模型及求解算法用于芳烃抽提过程的操作调优,可有效地提高决策的准确性。     

烟台发电厂循环冷却排污水的深度处理及其回用

介绍了烟台发电厂投入运行的循环冷却排污水的深度处理系统,该系统由预处理、预除盐、一级除盐、深度除盐等部分组成,它以电厂的循环排污水作为水源制取除盐水,与原有的水处理车间的除盐水一起供应烟台市供热管网首站用水和电厂锅炉用水.系统投入运行后降低了循环水的浓缩倍数,改善了循环水的运行工况,解决了电厂中循环水排污水处理难的问题,实现了循环冷却排污水的回收利用,达到了循环水的零排放,提高了水利用率,降低了电厂的水耗.     

通用炼油厂水系统优化模型开发与应用

传统水系统优化往往只考虑了新鲜水用量,而忽视了除盐水、除氧水、各等级蒸汽、蒸汽冷凝水、循环冷却水等类型的水,缺乏对各类型水量关联性的研究。针对这种局限性,提出了包含多种类型水的通用用水过程模型,以及通用炼油厂水系统优化的超结构和相应的数学模型,模型中集成了各装置及各种类型水之间关联的物料衡算方程。利用商业软件GAMS对某炼油厂的水系统进行建模求解,案例分析结果表明,除盐水用量有所下降,回用水用量增加,在优化前后雨水量保持469.36 t·h^-1的情况下,系统的新鲜水用量从489.44 t·h^-1减小到283.94 t·h^-1,以系统新鲜水量和雨水量之和为基准,节水率达到21.4%。加工吨原油取水量从0.649 t减小至0.510 t,接近国内先进水平。案例研究表明,提出的优化模型能够有效地计算整个炼油厂水系统的新鲜水用量,验证了该模型的实用性。     

基于多目标优化精馏系统综述

综述了精馏系统中多目标的优化问题,分析列举了人工神经网络、正交设计、响应面、遗传算法和粒子群算法在精馏系统多目标优化中的应用,旨在总结精馏系统中的优化算法,寻求最优操作条件的解法,为精馏塔的多目标优化提供参考。结果表明,针对于目前精馏系统的复杂多变性及混合规划问题,这些算法可以很好地对精馏系统进行建模,预测精馏模型,预测值与模拟值拟合较好,有较高的精度。且可用于求解精馏过程中的最优操作条件,降低系统的不可逆性,实现了精馏系统的节能优化,提高了产品质量,降低了能耗。最后指出了多目标优化精馏系统方法的可行性,也表明在实际生产中将多种优化算法相结合进行多步优化的可行性。     

Desalination in Australia operational experience and future prospects

To provide high quality fresh water to meet peak demands at times of drought in large population centres and to satisfy the requirements for water standards in industrial processes are perhaps the prime attractions of sea water desalination plants. Australia, the driest of earth's continents, will probably have a need for such water supply supplementation and industrial process application long before desalting is applied generally to agriculture or rural production. As the cost of fossil fuel gradually increases, it would also seem likely that the thermal energy required for desalting will come from nuclear fuels. In this paper the existing fresh water resources of the Australian continent are briefly surveyed. Present costs associated with supplying fresh water for industrial and domestic consumption to selected communities at representative locations of the Australian continent are assessed. The technology and economics of large scale sea water desalination plants operating on thermal cycles are discussed. In particular, the multi-stage flash evaporator principle is reviewed and its potential discussed. Consideration is given to the advantages and disadvantages of nuclear powered heat sources. Proposals are made for the control and conjunctive use of reservoirs and desalination plants. The optimisation of desalination plant size and its integration with reservoir storage schemes in two potential Australian locations is discussed.     

微粒群算法在干燥器多变量优化设计中的应用

建立了以具有废气循环的回转干燥系统年总费用为目标函数的优化设计数学模型,在此基础上探讨了惯性权因子对微粒群算法性能的影响,并应用微粒群算法求解干燥器优化设计数学模型,对干燥器出口废气温度与循环比进行优化设计。结果表明,带动态非线性惯性因子的微粒群算法对求解多变量的干燥优化设计问题具有方法简单、所需微粒群规模小、收敛速度快等特点;采用部分废气循环并进行优化设计对干燥系统的节能具有十分重要的意义,对湿空气出口温度和废气循环比进行优化设计,其年总费用比无废气循环的常规设计节省18．2%,比循环比为0．2时的常规设计节省12．6%。     

净化水在常减压装置的回用

通过技术改造,将污水汽提装置净化水在常减压装置电脱盐注水、配剂用水工序使用,代替原设计新鲜水,装置新鲜水消耗大幅降低。减少使用新鲜水的同时降低了污水处理厂负荷和污水处理费用。     

On the reduction of desalting energy and its cost in Kuwait

All seawater desalting processes, multi-stage flash (MSF), multi-effect boiling (MEB), mechanical vapor compression (MVC) and seawater reverse osmosis (SWRO) consume significant amounts of energy. The recent increase of fuel oil cost raises the cost of energy consumed for desalting water and the final water cost, and creates more interest in using more energy efficient desalting systems.

The most used desalting systems by distillation (MSF and MEB) are usually combined with power plants in what is called co-generation power desalting plants, CPDP. Fuel is supplied to the CPDP to produce both desalted water D and power W, and the fuel cost is shared between D and W. Exergy analysis and equivalent work are among the methods used to determine the fuel energy charged to each product. When desalting systems, such as SWRO and MVC, are not combined with a power plant, the fuel energy can be directly determined from its electrical power consumption.

In this paper, the fuel energy cost charged to desalting seawater in the presently used CPDP in Kuwait is calculated based on exergy analysis. The MSF, known by its high energy consumption, is the only desalting method used in Kuwait. The MSF units consume 258 kJ/kg thermal energy by steam supplied to the brine heater BH, 16 kJ/kg by steam supplied to steam ejectors, and 4 kWh/m3 mechanical energy for pumping. These MSF units are operated either by:

(1) Steam extracted from extraction/condensing steam turbines EC/ST as in as in Doha West, Azzour, and Sabbiya CPDP. This practice is used in most Gulf area.

(2) Steam supplied directly from boilers as occurred in single purpose desalting plants as Al Shuwaikh plant; or in winter time when no steam turbines are in operation in the CPDP to supply steam to the desalting units.

The CPDP have limited water to power production ratio. While they can cope with the increase of power demand, it cannot satisfy the water demand, which is increasing with higher pace than the power demand.

The case of steam CPDP used in Kuwait is presented in this paper as a reference plant to evaluate the amount of fuel energy consumed to desalt water in MJ/m3, its cost in $/m3. The resulted high fuel cost calls for some modifications in the reference CPDP to lower the energy cost, and to increase its water to power ratio. The modifications include the use of an auxiliary back-pressure steam turbine ABPST supplied with the steam presently extracted to the MSF units. The power output of the ABPST operates MVC or SWRO desalting units; while the ABPST discharged steam operates LT-MEB desalting unit. The desalting fuel energy costs when applying these modifications are also calculated by the exergy analysis and compared with that present situation.

It is also suggested to increase desalted water output by using separate SWRO desalting units operated by the existing power plants of typical η_c = 0.388, or by new combined gas/steam turbines power cycle GT/ST-CC of typical η_c = 0.54 under construction. The SWRO with energy recovery is assumed to consume typical 5.2 kWh/m³ electric energy.     

天津PTA水系统资源的优化

对天津石化PTA装置的脱盐水(D IW)系统和新鲜水系统的现状进行了分析。通过用蒸汽凝液替代D IW,母液闪蒸蒸汽凝液回用,提高进料固含量等方法对D IW系统进行了优化。并对精制单元和氧化单元新鲜水回用进行了优化。     

Optimal design of hybrid RO/MSF desalination plants Part III: Sensitivity analysis

This is the last paper in a series of three parts entitled “Optimal design of hybrid RO/MSF desalination plants”. This research is concerned with exploring the feasibility of hybridization of multi-stage flash (MSF) and reverse osmosis (RO) technologies in order to improve the performance characteristics and process economics ofthe conventional MSF process. The research project involved an optimization study where the water cost perunit product is minimized subject to a number of constraints. In the first part, the design and cost models were presented, the optimization problem formulated and solutions for a number of cases were outlined. In the second part, results were presented and discussed. In this paper we discuss the sensitivity of water cost from the alternative plant designs to variations in some cost elements and operating conditions. In general, it is concluded that, for the same desalting capacity, hybrid RO/MSF plants can produce desalted water at a lower cost than brine recycle MSF plants, while hybrid plants are characterized, by lower specific capital costs and higher water recovery fractions. Reduction in steam cost allows MSF to compete more with hybrid RO/MSF plants. This result explains the advantage of coupling MSF plants and steam power plants where the exhaust steam from the back pressure turbine represents a relatively cheaper source of heat for the MSF process. Results showed that the RO technology exceeds all other designs over the whole range of energy, chemicals and membrane costs studied here. However, water cost of the RO process was the most sensitive to variations in membrane and electricity costs compared to other hybrid configurations.     

Optimisation of petroleum refinery water network systems retrofit incorporating reuse,regeneration and recycle strategies

Scarcities in freshwater supply and increasingly stringent rules on wastewater discharges have emerged as major environmental concerns for petroleum refineries. Hence, this work attempts to develop an optimisation framework for refinery water network systems design and retrofit that integrates the complementary advantageous features of water pinch analysis (WPA). The framework explicitly incorporates water minimisation strategies by first postulating a superstructure representation that embeds all feasible flowsheet alternatives for implementing water reuse, regeneration and recycle (W3R) opportunities. Subsequently, a nonlinear programming (NLP) model is formulated based on the superstructure and computational experiments on a real‐world case study are conducted using the GAMS/CONOPT3 modelling language platform. Post‐optimality analysis on the numerical results are performed to achieve the desired water reuse quality, hence presenting a viable framework to aid decision‐making in water network systems synthesis. © 2011 Canadian Society for Chemical Engineering     

AquoMin: A software tool for Mass-Exchange Networks targeting and design

This study addresses the work developed at Process Integration Group of CPQ to build a software tool in the area of Pollution Prevention, regarding the Mass-Exchange Networks (MEN) targeting and design.Given a set of mass transfer operations and their limiting data, AquoMin can analyse different options to reduce fresh water consumption and minimise wastewater production. The available strategies to optimise these targets are (i) process without waste water reutilisation, (ii) process with waste reutilisation, and (iii) process with waste regeneration reuse. These options are analysed in two stages: first the targeting and then the design. The former stage uses algorithms based on pinch analysis to obtain the minimum consumption of external water and also the minimum wastewater production. These targets are then used in the second stage, the MEN design.The regeneration reuse strategy needs an extra step in the MEN design stage, which uses pinch analysis concepts to generate a mass balance model to obtain a set of optimal design parameters, the Split Operation Parameters (SOP). Furthermore, work on regeneration with recycle and reuse has been also developed. It was created a general algorithm to obtain the targets for this strategy: the external water source flowrate and the regeneration and recycle flowrate.A small AquoMin tutorial is presented using an Example Problem. The regeneration reuse strategy is focused and the methodology employed in both targeting and design stages were improved. Different scenarios evaluating the MEN structure's complexity and equipment cost were also developed and compared in the regeneration reuse strategy. In the regeneration recycle and reuse strategy, the Example Problem was used to emphasise a new option for the regeneration concentration value and the results of all the strategies are compared.Finally, a five operations’ Case Study was solved to obtain the targets and designs to accomplish the three Process Integration Strategies with a final reduction of 60% in the fresh water consumption.     

Structural effects of ion‐exchange membrane on the separation of L‐phenylalanine (L‐Phe) from fermentation broth using electrodialysis

The effects of membrane structure on the separation of L ‐phenylalanine (L ‐Phe) by electrodialysis from a fermentation broth and on the fouling tendency were investigated in this study. Two anion‐exchange membranes (Neosepta AFX and AM‐1, Tokuyama, Japan) were selected and characterized using the chronopotentiometry method. For a fresh membrane, AFX showed a lower electrical resistance and a lower permselectivity than AM‐1. After being fouled with humic acid, however, the electrical resistance of AFX was higher than that of AM‐1. The L ‐Phe selectivities for both membranes were lower than those of the fresh membranes. The result may be attributed to the structural difference between AFX and AM‐1 membranes. AFX has a lower repulsion force against the co‐ion and could be more strongly affected by the foulants than AM‐1 because AFX has a more porous structure than AM‐1. Experiments on the separation of L ‐Phe from the fermentation broth were carried out using two different stack configurations, ie desalting electrodialysis and water‐splitting electrodialysis. It was observed that the recovery efficiency of L ‐Phe through electrodialysis for 100 min reached 95% for AFX and 85% for AM‐1. In the desalting configuration of electrodialysis, the solution pH must be adjusted to alkaline conditions to recover the L ‐Phe through the anion‐exchange membrane. On the contrary, it was possible to recover the L ‐Phe without adjustment of the solution pH in the water‐splitting electrodialysis because OH^? generated from the bipolar membrane converted neutral L ‐Phe into an anion. © 2002 Society of Chemical Industry