热力蒸汽压缩式海水淡化系统热力分析

通过对热力蒸汽压缩式海水淡化装置的分析，建立起其数学模型，模拟计算结果表明，与一般蒸汽直接加热式真空海水淡化系统比较，采用热力蒸汽压缩式海水淡化系统，其能耗明显降低．此外，对不同的蒸发温度下的工作蒸汽耗量进行了模拟计算，所得结论对热力蒸汽压缩式海水淡化系统的设计与使用管理有指导意义。     

A desalination battery

Water desalination is an important approach to provide fresh water around the world, although its high energy consumption, and thus high cost, call for new, efficient technology. Here, we demonstrate the novel concept of a "desalination battery", which operates by performing cycles in reverse on our previously reported mixing entropy battery. Rather than generating electricity from salinity differences, as in mixing entropy batteries, desalination batteries use an electrical energy input to extract sodium and chloride ions from seawater and to generate fresh water. The desalination battery is comprised by a Na(2-x)Mn(5)O(10) nanorod positive electrode and Ag/AgCl negative electrode. Here, we demonstrate an energy consumption of 0.29 Wh l(-1) for the removal of 25% salt using this novel desalination battery, which is promising when compared to reverse osmosis (~ 0.2 Wh l(-1)), the most efficient technique presently available.     

Exergy recuperative CO2 gas separation in pre-combustion capture

The integrated coal gasification combined cycle (IGCC) can achieve higher power generation efficiency than conventional pulverized coal combustion power plants. However, a CO₂ capture process prevents improving power generation efficiency of IGCC, because CO₂ separation from gas mixtures requires huge amounts of energy. Therefore, in this study, we analyzed the CO₂ separation process in the pre-combustion capture process using a process simulator (PRO/II) in the steady state, and proposed a new process using a modularity based on self-heat recuperation (SHR) technology to decrease energy consumption. Pre-combustion capture was applied in the IGCC plant, which involved coal gasification and CO-shift conversion with CO₂ capture. The results show that the energy consumption for the CO₂ separation process using SHR was decreased by two-thirds. This means that the power generation efficiency can be improved by SHR compared with conventional IGCC with a CO₂ capture process.     

MSF/RO/ED海水淡化技术研究

综述了世界水资源形势以及海水淡化技术的发展现状,概括了海水淡化技术的主要方法,着重介绍了多级闪蒸海水淡化法(MSF)、反渗透法(RO)和电渗析法(ED),从各种装置的组件、能耗以及淡化过程等入手,总结3种方法的优势与不足,针对性提出了解决问题的方法以及发展方向,以降低使用成本,并探讨和展望了今后的海水淡化技术。     

Preliminary theoretical analyses of thermal performance and available energy consumption of two-stage cascade cycle heat pump water heater

In this paper, the analysis model of thermal performance and available energy of two-stage cascade cycle heat pump water heater (HPWH) was established. For the first time, the equivalent transformation thermodynamic analysis method and available energy consumption equation were employed to carry out the theoretical analyses of thermal performance and available energy consumption for two-stage cascade cycle HPWH. And the correctness of the analysis approach proposed in this paper was verified by an example. The calculation results showed a significant agreement with the results derived by the first law of thermodynamics and energy conservation law. The available energy analysis of two-stage cascade cycle HPWH clearly revealed the available energy consumption rates for different working processes, including heat transfers of heat exchangers, flow of heat-carrying fluid, working medium cycle, output of hot water, etc. This approach could be conveniently used in the analyses of thermal performance and available energy consumption for actual complex thermal system with irreversible process. This paper provided the theoretical basis for the actual optimization design and operation analysis of cascade type heat pump systems, and furthermore, the results of the calculation instance would also have a certain reference value.     

Optimal scheduling of biocide dosing for seawater-cooled power and desalination plants

Thermal desalination systems are typically integrated with power plants to exploit the excess heat resulting from the power-generation units. Using seawater in cooling the power plant and the desalination system is a common practice in many parts of the world where there is a shortage of freshwater. Biofouling is one of the major problems associated with the usage of seawater in cooling systems. Because of the dynamic variation in the power and water demands as well as the changes in the characteristics of seawater and the process, there is a need to develop an optimal policy for scheduling biocide usage and cleaning maintenance of the heat exchangers. The objective of this article is to introduce a systematic procedure for the optimization of scheduling the dosing of biocide and dechlorination chemicals as well as cleaning maintenance for a power production/thermal desalination plant. A multi-period optimization formulation is developed and solved to determine: the optimal levels of dosing and dechlorination chemicals; the timing of maintenance to clean the heat-exchange surfaces; and the dynamic dependence of the biofilm growth on the applied doses, the seawater-biocide chemistry, the process conditions, and seawater characteristics for each time period. The technical, economic, and environmental considerations of the system are accounted for. A case study is solved to elucidate the applicability of the developed optimization approach.     

Thermoelectricity in Heterogeneous Nanofluidic Channels

Ionic fluids are essential to energy conversion, water desalination, drug delivery, and lab‐on‐a‐chip devices. Ionic transport in nanoscale confinements and complex physical fields still remain elusive. Here, a nanofluidic system is developed using nanochannels of heterogeneous surface properties to investigate transport properties of ions under different temperatures. Steady ionic currents are observed under symmetric temperature gradients, which is equivalent to generating electricity using waste heat (e.g., electronic chips and solar panels). The currents increase linearly with temperature gradient and nonlinearly with channel size. Contributions to ion motion from temperatures and channel properties are evaluated for this phenomenon. The findings provide insights into the study of confined ionic fluids in multiphysical fields, and suggest applications in thermal energy conversion, temperature sensors, and chip‐level thermal management.     

纳滤膜脱盐及其在海水软化中的应用

采用卷式纳滤膜进行了MgSO4、K2SO4、MgCl2等5种物质的脱盐性能研究,考察了进料操作压力和浓度对表现截留率和膜通量的影响,在此基础上研究了操作压力对海水脱盐性能的影响.实验表明,纳滤膜性能稳定,能除去海水中90％以上的SO42-以及50％以上的Mg2+和Ca2+,大幅度降低了海水的硬度,可解决传统上海水淡化过程中易结垢离子对膜的污染问题;纳滤膜软化海水可以降低海水淡化后期处理的成本和能耗;采用纳滤膜软化海水在技术上是可行的.     

电站锅炉烟气余热利用技术方案研究

超临界电站锅炉排烟热损失量很大,对锅炉尾部烟气余热进行回收利用可以有效提高电厂的热经济性,减少煤耗,降低环境污染。目前火电厂最广泛提高烟气余热利用效率的方式是加装低温省煤器装置。对某超临界机组锅炉余热利用技术进行研究,分析不同低温省煤器布置方案,提出采用双级低温省煤器回收电站锅炉余热利用技术方案,即采用低温烟气与低加凝结水换热技术、前置式空气预热器与低温省煤器组合的能源梯级利用方式,实现最优节能及最佳投资收益。     

Energy efficiency of RO and FO–RO system for high-salinity seawater treatment

Forward osmosis (FO) has been proposed as an alternative method for seawater desalination, wherein reverse osmosis (RO) membrane technology is used for regeneration of the draw solution. Previous studies have indicated that a standalone RO unit is more energy efficient than an FO–RO system, and as such it was recommended that an FO–RO system is best employed only for the desalination of high-salinity seawaters. This study examined FO–RO applicability in more detail by examining the impact of seawater salinity, impact of an energy recovery device (ERD), and the effect of membrane fouling. For comparison purposes, the performance of the FO process was improved to minimize the impact of concentration polarization and optimize the concentration of draw solution. Model calculations revealed that FO–RO is more energy efficient than RO when no ERD was employed. However, results showed that there was no significant difference in the power consumption between the FO–RO system and the RO unit at high seawater salinities particularly when a high-efficiency ERD was installed. Moreover, the FO–RO system required more membrane area than a conventional RO unit which may further compromise the FO–RO desalination cost.     

Intensification of Ethylene Production from Naphtha via a Redox Oxy-Cracking Scheme: Process Simulations and Analysis

Ethylene production by the thermal cracking of naphtha is an energy-intensive process (up to 40 GJ heat per tonne ethylene), leading to significant formation of coke and nitrogen oxide (NO_x), along with 1.8–2 kg of carbon dioxide (CO₂) emission per kilogram of ethylene produced. We propose an alternative process for the redox oxy-cracking (ROC) of naphtha. In this two-step process, hydrogen (H₂) from naphtha cracking is selectively combusted by a redox catalyst with its lattice oxygen first. The redox catalyst is subsequently re-oxidized by air and releases heat, which is used to satisfy the heat requirement for the cracking reactions. This intensified process reduces parasitic energy consumption and CO₂ and NO_x emissions. Moreover, the formation of ethylene and propylene can be enhanced due to the selective combustion of H₂. In this study, the ROC process is simulated with ASPEN Plus® based on experimental data from recently developed redox catalysts. Compared with traditional naphtha cracking, the ROC process can provide up to 52% reduction in energy consumption and CO₂ emissions. The upstream section of the process consumes approximately 67% less energy while producing 28% more ethylene and propylene for every kilogram of naphtha feedstock.     

基于能耗的热量表耐久性 试验经济性分析

针对热量表耐久性试验中的能耗问题,基于理论计算的方法对耐久性试验装置运行时能耗进行了分析,给出了串联不同批次数量热量表时,耐久性试验装置的耗能及其对应每一批次热量表的均耗能量,比较了串联批次数量不同时每一批次耗能量的大小;同时,分析了水源保温在热量表耐久性试验中的能耗问题.结果表明,影响热量表耐久性试验经济性的主要因素...     

Energy recovery using vapour recompression

The multiple‐effect principle can be used to reduce thermal energy requirements in thermal processes. According to this principle the energy is used several times over, according to the number of effects. Another possibility consists in increasing the pressure of the heat emitted by the process in the form of vapours to such a level so as to reuse it in the process. Jet pumps or mechanical recompressors, which are frequently operated in the rough vacuum range, are used for this purpose. This principle is explained in examples of thermal separation technology.     

Membrane Engineering for Green Process Engineering

Green process engineering, which is based on the principles of the process intensification strategy, can provide an important contribution toward achieving industrial sustainable development. Green process engineering refers to innovative equipment and process methods that are expected to bring about substantial improvements in chemical and any other manufacturing and processing aspects. It includes decreasing production costs, equipment size, energy consumption, and waste generation, and improving remote control, information fluxes, and process flexibility. Membrane-based technology assists in the pursuit of these principles, and the potential of membrane operations has been widely recognized in the last few years. This work starts by presenting an overview of the membrane operations that are utilized in water treatment and in the production of energy and raw materials. Next, it describes the potential advantages of innovative membrane-based integrated systems. A case study on an integrated membrane system (IMS) for seawater desalination coupled with raw materials production is presented. The aim of this work is to show how membrane systems can contribute to the realization of the goals of zero liquid discharge (ZLD), total raw materials utilization, and low energy consumption.     

Mushrooms as Efficient Solar Steam‐Generation Devices

Solar steam generation is emerging as a promising technology, for its potential in harvesting solar energy for various applications such as desalination and sterilization. Recent studies have reported a variety of artificial structures that are designed and fabricated to improve energy conversion efficiencies by enhancing solar absorption, heat localization, water supply, and vapor transportation. Mushrooms, as a kind of living organism, are surprisingly found to be efficient solar steam‐generation devices for the first time. Natural and carbonized mushrooms can achieve ≈62% and ≈78% conversion efficiencies under 1 sun illumination, respectively. It is found that this capability of high solar steam generation is attributed to the unique natural structure of mushroom, umbrella‐shaped black pileus, porous context, and fibrous stipe with a small cross section. These features not only provide efficient light absorption, water supply, and vapor escape, but also suppress three components of heat losses at the same time. These findings not only reveal the hidden talent of mushrooms as low‐cost materials for solar steam generation, but also provide inspiration for the future development of high‐performance solar thermal conversion devices.     

工业余热热泵及余热网络化利用的研究现状与发展趋势

当前工业能源消耗中所排放的低品位余热量大面广,若采用高效的余热利用技术将这部分余热回收,将具有显著的节能效果。工业余热热泵技术可以实现余热品位的提升或容量的扩大,一方面可以将回收的热量应用到工业流程中,另一方面可以在区域供热及供冷方面发挥作用。本文分析了压缩式热泵、吸收式热泵与化学热泵的特点与发展趋势。目前三种热泵技术都在工质、循环以及系统创新方面得到了较大的发展,但是在容量、能效比、温升与可靠性方面存在不可兼得的瓶颈问题。此外,工业余热根据种类以及温度品位的不同,适用场合与特点也各不相同。但目前在余热回收利用的设备与系统方面,缺乏针对不同余热特点的指导性设计准则。未来的研究需要集中在发展效率高、容量大、热适应性好、稳定可靠的热泵技术,形成各余热热泵互补利用的广谱化设计准则。同时需要通过对余热的热、电、冷、储、运的网络化利用进行余热系统高质化集成,实现工业余热的高效利用。     

反渗透膜分离技术的创新性进展

水是地球上不可替代的宝贵的自然资源,是人类赖以生存和生产的不可缺少的基本物质.当前缺水已成为世界性问题,成为制约社会进步和经济发展的瓶颈,解决水资源的供需矛盾,对我国的可持续发展是非常迫切的和重要的.用海水淡化技术向大海要淡水,是自古以来人们所梦寐以求的,现在已变为现实,其中反渗透法海水淡化发展最为迅速,不仅技术上完全可行,而且在许多情况下是最经济的选择.简述了自上世纪50年代以来反渗透法海水淡化(SWRO)的提出和发展概况;重点介绍了反渗透不对称膜和复合膜的发展,特别是复合膜品种的不断增多与性能的不断改进和提高;中空纤维和卷式反渗透膜组器技术的创新,特别是卷式反渗透膜组器的设计和制备技术的改进及组器的性能提高和大型化;效率不断提高的高压泵和能量回收装置,特别是能量回收装置结构形式的不断改进和能量回收效率的不断提高;实用于不同要求的各种SWRO工艺,如二级海水淡化工艺、一级海水淡化工艺、高压一级海水淡化工艺、高效两段海水淡化工艺、SWRO与纳滤(NF)、与多级闪蒸(MSF)或多效(MED)集成的海水淡化工艺以及微滤(MF)或超滤(UF)作为预处理等,另外,简述了大型反渗透法海水淡化厂对环境的影响,如与能耗相关的CO2的排放、浓海水排海、占地、噪音和景观等;最后对反渗透技术的延伸进行了简介.     

热舒适空调的能量设计因子研究

为确定热舒适需求与空调节能设计过程中的关键能量设计要素之间的关联性,提出了一种基于热舒适的空调能量设计因子提取及其重要度计算方法。在热舒适空调节能设计过程框架的基础上,建立了基于热舒适需求的功能质量屋,并将热舒适性转化为空调功能及权重等设计信息;分析功能的能量特性,针对与能耗相关的功能,给出了能量设计因子提取策略,以及能量设计因子对热舒适及能耗综合影响程度量化方法。以家用空调为例,提取了基于热舒适的能量设计因子,对容积效率和传热系数两项耦合因子进行了分解,并对整体层能量设计因子的热舒适性及能耗的影响系数进行计算,按综合影响系数由大到小排序,结果为压缩机功率、系统控制方式、通风量和换热量。     

A systems-integration approach to the optimization of macroscopic water desalination and distribution networks: a general framework applied to Qatar’s water resources

The objective of this article is to introduce an optimization-based approach for the integrated design and operation of macroscopic water networks. A structural representation approach is developed to embed all potential configurations of interest. This representation accounts for water resources, desalination plants, water users, wastewater treatment facilities, and storage. Water recycle/reuse is enhanced via the use of treated water. Water utilization is improved by minimizing the losses of discharged water resulting from the linkage of power plants and thermal desalination plants and the lack of integration between water production and consumption. Excess water is saved in storage systems or injected in aquifers for strategic (long-term) storage. The developed approach also accounts for the economic values of water uses and storage and for the cost of water production and allocation. An optimization formulation is developed and solved to determine the optimal operation of the infrastructure. The solution also determines the optimal monthly allocation and storage of water resources. A case study is solved for managing the water resources in the State of Qatar while accounting for desalination, distribution, and storage. The solution indicates that storage in tanks reaches its maximum capacity in less than a month while storage in aquifers continues throughout the year as a strategic step towards water security. The solution also illustrates the need to treat wastewater in addition to using desalination of seawater. The output water streams with different qualities are assigned to proper destinations.     

二元冰吸收式制备技术

二元冰具有优异的传热、流动特性,使用它后能够减小热交换器的热损失、水泵的能耗和设备体积等,优化热交换器的结构.吸收式制冷可以利用热能为动力,尤其是可以利用低品位热能为动力的优点使其在空调领域得到了较大发展.二元冰吸收式制备技术可以同时兼备这两项优点,但如何有效保持冰晶的尺寸在一定范围之内是该技术目前存在的主要问题,从蒸发器的结构设计和制冷剂性质优化这两方面入手,可以较好的解决这一问题.