反渗透和压力延迟渗透耦合脱盐系统的能效优化研究

针对开环和闭环两类结构的反渗透-压力延迟渗透耦合脱盐系统进行了模型构建与系统优化分析。首先,以标准化比能耗为目标函数,构建了开环结构和闭环结构耦合系统的非线性约束优化模型。在优化模型中,引入包括半透膜性能、操作状态及设计变量的无量纲参数组,建立反渗透和压力延迟渗透单元过程的特征方程以简化模型。同时,为了保证比较的公平性,开环结构的总体能耗中额外包含了预处理和后处理能耗。通过求解上述优化模型,系统地比较和分析了无量纲半透膜总面积和水回收率同时变化导致的最优标准化比能耗、膜面积分配和操作压力的变化规律。结果表明,在水回收率处于正常水平(≤0.55)且系统总面积充足(≥0.9)时,闭环结构在节能及减少预处理费用方面比开环结构具有更明显优势。     

大型反渗透海水淡化工程能耗降低方法探讨

探讨了降低海水淡化能耗的方法,对能量回收装置性能进行了对比分析,并对大型反渗透海水淡化工程提出了"深井取水 预处理(UF/MF) 高产水量RO膜 AT TURBO/PX"工艺,提高反渗透装置进膜压力、平均膜通量、回收率,降低吨水能耗,对今后大型反渗透海水淡化工程设计有一定的借鉴意义.     

卷式膜元件反渗透脱硼海水淡化系统多目标优化研究

对卷式膜元件反渗透脱硼海水淡化网络系统进行多目标优化。采用不可逆热力学模型描述盐和硼的跨膜传质过程,加入系统流量约束保障反渗透系统安全运行。采用增强型ε-约束算法对多目标优化问题进行求解,引入模糊决策法在Pareto非劣解中筛选优化折中解。对于特定的装置参数,优化方案均采用二级反渗透系统,反渗透方案的成本在0.72～0.97$/m~3、能耗在3.09～3.96 k W h/m~3。随着成本的降低,系统回收率呈增加趋势,一级反渗透的压力容器个数逐渐降低,操作压力和压力容器内产水通量逐渐增加,而二级反渗透上述参数变化不大,进水p H保持在10.4~11.0以保证系统脱硼率。通过成本构成分析可知,将第1级反渗透平均通量控制在14.0 L/(m~3·h)时在经济与能耗上较为均衡。     

高回收率反渗透海水淡化工艺的应用研究进展

回收率是反渗透系统设计中一个非常关键的参数,决定着进水处理系统(取水、预处理系统和高压泵)的尺寸和占地面积。但系统回收率的提高需要较高的操作压力,由此带来较快的膜污染和频繁的膜元件清洗与更换。目前,在不加剧膜污染的条件下进一步提高海水淡化系统回收率的方法已成为该领域研究热点。本文详细综述了国内外高回收率反渗透海水淡化工艺的应用研究进展,包括基于纳滤海水软化的集成膜过程和热膜耦合海水淡化过程,以及这些过程面临的结垢问题和影响因素,并针对目前的研究方向提出了建议。     

反渗透浓水回收利用技术的改造

<正>1反渗透装置现状安徽晋煤中能化工股份有限公司(以下简称中能公司)现有1套300 t/h脱盐水装置,工艺采用预处理+反渗透+EDI,反渗透为100 m3/h×3组合,系统回收率75%,单套反渗透系统产纯脱盐水量100 m3/h,浓水排放量为33～34 m3/h,整套反渗透系统浓水排放量约为102 m3/h。每套反渗透系统的浓水在浓水排放阀截流之前压力达     

反渗透技术在尾矿废水处理中的应用

针对高含盐量、高硬度的尾矿废水,采用锰砂过滤、在线絮凝过滤、活性炭过滤和投加针对性的阻垢剂作预处理,主体工艺采用反渗透技术对其进行处理.分别考察了反渗透系统在50%和70%回收率的条件下,预处理工艺的处理效果、反渗透膜的污染情况以及反渗透膜脱盐率的影响因素.试验结果表明,顸处理效果良好,其产水SDI基本保持在3.5左右;反渗透系统运行稳定,反渗透膜没有出现明显污染倾向;在进水水质、水温、膜通量和操作压力一定的条件下,反渗透膜进水流量与脱盐率成正比.     

连续式电吸附海水淡化技术研究

针对海水淡化膜价格昂贵、能耗高、寿命短、预处理要求高、产水率低等缺点,研究了一种基于连续式电吸附工艺的海水淡化工艺,包括预处理集成系统、电吸附系统、反渗透系统。该工艺具有成本低、寿命长、能耗低、占地面积小、回收率高等优点。     

液隙式热泵膜蒸馏海水淡化系统的热力性能分析

热泵膜蒸馏是一种新型的膜分离技术，在处理高浓度盐水方面具有很大的优势，而目前的热泵膜蒸馏系统存在渗透量较低、冷却水消耗量大等问题。为提高渗透量、减少冷却水的消耗，设计了一种新型液隙式热泵膜蒸馏的海水淡化系统，通过在Aspen Plus中自定义膜模块建立经过实验验证的系统仿真模型，研究了进料液温度、渗透侧温度及进料流量对系统膜通量及能效比等热力参数的影响。结果表明，渗透侧温度降低可引起渗透量增加和能效比减小，且在低渗透侧温度情况下渗透侧温度的改变对能效比影响更大。随着渗透侧温度变化，存在一个渗透侧温度使造水比最大且吨水能耗最小，研究工况下最大造水比可达3.42，最小吨水能耗为463 MJ/t，且该最佳渗透侧温度随进料液温度增加而增加。进料液流量增加可引起渗透量和能效比增加，引起吨水能耗升高和造水比降低，当进料液流量小于3 L/min时，进料液流量增加对吨水能耗和造水比的负面影响较显著，进料液温度为50℃时，料液流量从1.5 L/min增至3 L/min，造水比的降低幅度可达33.5%；料液流量从4.5 L/min增至6 L/min时，造水比的降低幅度降至10.6%。     

小型反渗透膜系统的集成设计

针对西北地区苦咸水淡化问题，进行了小型反渗透系统最佳工艺设计研究，在保证系统回收率的情况下，比较了淡水背压和段间加压工艺，将膜品种与段间加压工艺进行集成优化，改善了膜通量均衡问题，减少了膜污染，降低了能耗。     

(二)反渗透法

反渗透法是海水淡化最有发展前途的一种方法。该方法的核心是使用只让溶剂通过而不让溶质通过的半透膜。原理当纯水和盐溶液分别在一张半透膜的两边时,纯水通过膜扩散,并且稀释了盐溶液。这种现象就叫做渗透。由于盐浓度的差别,好象有一个压力压在纯水这边,使它流经     

正渗透过程中汲取质反向渗透研究进展

正渗透(FO)作为一种浓度驱动的膜技术,因其膜污染轻、能耗低和回收率高等优点而逐渐成为膜技术领域的研究热点之一。汲取质的反向渗透是正渗透过程中不可忽视的现象,但其研究相对比较滞后。本文主要介绍了汲取质反渗模型的研究进展,分析了渗透压差、膜表面流速、膜结构与膜材料、温度、汲取质种类、膜取向、离子水力半径等因素对汲取质反向渗透的影响情况,并发现汲取质的反向渗透通量可由其浓度或汲取液渗透压的一元多项式表达。总体而言,FO模式的汲取质反渗模型经过不断发展已相对比较完善,而压力阻尼渗透(PRO)模式的反渗模型则缺陷较大,有待进一步研究;此外,关于汲取质反渗过程影响因素及其影响机制的研究对于汲取质、膜材料的选择与开发,以及正渗透过程的优化均具有重要的指导作用,因此会引起越来越多的关注。     

Multi-objective optimization of reverse osmosis networks by lexicographic optimization and augmented epsilon constraint method

This study proposes a multi-objective optimization (MOO) of reverse osmosis (RO) networks for seawater desalination. The membrane transport model takes into consideration of the longitudinal variation of the velocity, the pressure, and the concentration in the membrane modules. The RO network with three type energy recovery device options (pressure exchanger (PX), Hydraulic Turbocharger, and turbine) is introduced. Lexicographic optimization (for calculation of a more effective payoff table) and augmented ε-constraint method (to avoid inefficient Pareto solutions) are proposed to solve the MOO problem. A fuzzy decision maker is introduced to derive the most efficient solution among Pareto-optimal solutions. Firstly, different energy recovery option studies show that using PX is seen to be the most profitable option. Exergy analysis is used to evaluate the contribution of the equipments in energy degradation. Secondly, the proposed multi-objective framework simultaneously optimizes the total annualized cost (TAC) and energy consumption. With the increases of weighting for the main objective function: TAC, the most efficient solution moves to lower TAC direction. Finally, system recovery rate is added as the third objective function. It is reasonable to stay at the appropriate system recovery rather than to increase up to its limit and generating high energetic losses.     

Investigation of different operational strategies for the variable operation of a simple reverse osmosis unit

Recent studies and projects showed that a combination of a reverse osmosis desalination plant with a wind power supply is technologically feasible if the reverse osmosis plant is operated with fluctuating and intermittent loads and thus follow the energy supply characteristic of the wind turbine. On this background the goal of this paper is to simulate the system behaviour of a simple reverse osmosis plant under changing process parameters (e.g. feed pressure, recovery or feed flow). These variations are systematized within so-called operational strategies. Therefore, four different operational strategies are analysed in detail with regard to given restrictions e.g. by the membrane system. For each of these strategies the specific energy consumption over the total usable load range is computed with the simulated hydraulic characteristics of each operational strategy. The analysis of the gathered data shows that a membrane system should be operated with constant permeate recovery under fluctuating wind power. This operational strategy provides low specific energy consumption over a broad load range.     

Fresh water by reverse osmosis based desalination: simulation and optimisation

The reverse osmosis (RO) desalination process to make fresh water from seawater has been studied here. First, a model for the process is developed. Sensitivity of different operating parameters (feed flow rate, feed pressure) and design parameters (internal diameter, total number of tubes) on the recovery ratio are studied via repetitive simulation. Finally, an optimisation framework for the process is developed so as to maximize the recovery ratio or a profit function using different energy recovery devices, subjectto general constraints. The optimal operating parameters (feed flow rate, feed pressure) and design parameters (internal diameter, total number of tubes) are determined by solving the optimisation problem using an efficient successive quadratic programming (SQP) based method. The optimal values for the decision variables depend on the constraints introduced, and are also sensitive to variations in water and energy prices, as well as feed concentration. The use ofthe emerging energy recovery devices is widely justified, reporting much higher reductions in operating costs than the traditional technology used for this purpose. Using a pressure exchanger device, it is possible to reduce energy consumption by up to 50%.     

Cost analysis of seawater desalination with reverse osmosis in Turkey

Economically usable water resources per capita are decreasing due to excessive population increase each year in Turkey. For this reason, new water resources should be found in the near future. The potential water resources are seawater or well water both of which need removal of salinity. The most promising treatment method for salinity is reverse osmosis. While reverse osmosis becomes widespread, the cost of the process will decrease. There is no detailed information about cost of seawater desalination in Turkey. In this study, a cost analysis of seawater desalination in Turkey was performed for reverse osmosis systems. The basic parameters of cost analysis such as capacity, recovery, membrane life, energy, chemical costs and flux were evaluated based on the effects on capital, operating and total production costs.     

正渗透原理及分离传质过程浅析

正渗透是一种新兴的膜分离技术,因其低能耗、抗污染、对污染物截留能力广等的潜力,在脱盐、废水处理、农业和电力等领域的应用前景备受瞩目。本文介绍了正渗透概念和原理,通过正渗透传递过程的现象学模型,对浓差极差极化与质量传递的关系作出分析,提出了强化正渗透传质过程的一些建议。     

A review on the forward osmosis applications and fouling control strategies for wastewater treatment

During the last decades, the utilization of osmotic pressure-driven forward osmosis technology for wastewater treatment has drawn great interest, due to its high separation efficiency, low membrane fouling propensity, high water recovery and relatively low energy consumption. This review paper summarizes the implementation of forward osmosis technology for various wastewater treatment including municipal sewage, landfill leachate, oil/gas exploitation wastewater, textile wastewater, mine wastewater, and radioactive wastewater. However, membrane fouling is still a critical issue, which affects water flux stability, membrane life and operating cost. Different membrane fouling types and corresponding fouling mechanisms, including organic fouling, inorganic fouling, biofouling and combined fouling are therefore further discussed. The fouling control strategies including feed pre-treatment, operation condition optimization, membrane selection and modification, membrane cleaning and tailoring the chemistry of draw solution are also reviewed comprehensively. At the end of paper, some recommendations are proposed.     

Analysis and optimization of pressure retarded osmosis for power generation

Model‐based analysis and optimization of pressure retarded osmosis (PRO) for power generation is focused. The effects of membrane properties (hydraulic permeability and mass‐transfer characteristics), design conditions (inlet osmotic pressures, inlet flows, and membrane area) and operating condition (applied pressure) on power density and efficiency are systematically investigated. A dimensionless design parameter , originally developed in analysis and optimization of reverse osmosis, is used to quantify the effect of dilution in draw solution (DS) as water permeates through membrane. An optimization method is developed to maximize PRO performance. It is shown that dilution and concentration polarization significantly reduce the maximum power density, and the optimal shifts away from . Moreover, power density and efficiency follow opposite trends when varying process conditions including DS flow rate and membrane area. Enhancing membrane properties is crucial to improve the economic feasibility of PRO. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1233–1241, 2015     

某电厂反渗透膜系统的化学清洗

分析了某电厂反渗透系统装置运行参数的变化、反渗透膜污染物的主要组成,确定了清洗方案。通过清洗液浊度、清洗液pH、一二段压差变化等指标,确定清洗终点。该装置化学清洗后进水压力大幅降低,产水脱盐率达到设计要求,产品水的回收率基本达到设计值,取得满意的清洗效果。     

Design, simulation and economic analysis of a stand-alone reverse osmosis desalination unit powered by wind turbines and photovoltaics

The fresh water shortage is a significant problem in many areas of the world such as deserts, rural areas, Mediterranean countries and islands. However, renewable energy potential in these areas is usually high using solar and wind energy. A desalination unit powered by renewable energy sources is a promising solution for this problem. This paper presents the design of a stand-alone hybrid wind-PV system to power a seawater reverse osmosis desalination unit, with energy recovery using a simplified spreadsheet model. A daily and monthly simulation and economic analysis were also performed. The calculated fresh water production cost was 5.2 ?/m³, and the realized energy saving was up to 48% when a pressure-exchanger-type energy recovery unit is considered.