国产化单机日产水1万吨的反渗透海水淡化工程

叙述了六横国产化单机1万m3/d反渗透海水淡化工程的工艺设计、设备配置、系统控制及部分国产关键技术、设备应用的基本情况。通过对该反渗透海水淡化系统的调试和试运行,结果表明该系统运行参数稳定,设备运行正常,性能指标达到设计要求,产品水符合国家生活饮用水标准。工程国产化率已达70%以上,且系统造水能耗仅为2.56 kWh/m3,已达到国内外先进水平。根据该项目情况,概要地分析了该系统的造水成本,经济和社会效益。     

10万吨/日反渗透海水淡化系统示范与应用

介绍了浙石化10万吨/日反渗透海水淡化示范工程项目的工艺设计,设备配置等基本情况,该项目中首次应用Φ4 000的超大型卧式滤器,同时实现了目前国内最大单机规模35 000 m~3/d的海水反渗透装置的设计和应用。通过对该反渗透海水淡化系统的调试和试运行,结果表明该系统运行参数稳定,设备运转正常,各项性能指标均达到了设计要求。根据该项目当地的实际情况,项目吨水成本3.08元/m~3,其中吨水电耗成本1.882元/m~3,吨水药耗成本0.275元/m~3,在原有海淡吨水成本上,均实现了有效的下降。     

MVC在某核电厂海水淡化设计的应用

海水淡化可有效解决核电厂淡水水源问题,其工艺主要包括蒸馏法和膜法。国内已运行的滨海核电厂大多设有海水淡化系统,并且均采用膜法海水反渗透工艺。本文根据某先进压水堆核电厂的特点,通过对蒸馏法的机械蒸汽压缩(MVC)及膜法的海水反渗透(SWRO)工艺的技术经济比较和研究,提出采用技术经济指标优、正常运行无需连续供应蒸汽、设备简单紧凑、运行维护方便、受海水水质和水温影响较小的MVC作为该核电厂的海水淡化工艺,为核电厂海水淡化的设计提供借鉴。     

膜法海水淡化系统在印尼巴淡电厂中的应用

介绍了印尼BATAM燃煤电厂海水淡化工程的工艺概况,通过整个系统的调试,对该海水淡化系统在调试和试运中出现的问题进行了分析,为整个海水淡化系统平稳的运行和产水水质提供了有力的保障。实践表明,多介质过滤器+一级海水淡化反渗透+二级淡水反渗透工艺处理印尼BATAM的海水,系统运行稳定,水质达到生产用水要求。     

海水淡化反渗透系统的系列化研究

我国反渗透海水淡化(SWRO)工程中工艺、设备等方面存在的一些问题影响了海水淡化制水成本。反渗透系统的系列化研究,不仅可以降低海水淡化成本,还可以为海水淡化技术研发和应用提供技术依据。本文详细介绍了对产水量为5~500m3.d-1的典型反渗透系统的工艺、节能技术和可靠性的研究,并形成了系列化产品的设计。通过此研究,优化了系统工艺,降低了系统能耗,为系统的安装制造提供了有力保证。     

海水淡化膜在焦化废水回用处理上的应用案例

利用海水淡化装置将焦化废水回用项目反渗透浓盐水进一步浓缩,减少浓盐水的排放,提高系统回用水收率。迁安某焦化厂在原有回用水系统中增设海水淡化装置,将反渗透浓水回收,运行结果表明:海水淡化装置应用于浓盐水的回收,装置运行稳定。装置回收率达到45%;海水淡化装置脱盐率达到99.2%,氯离子去除率达到99.3%,装置产水符合工业循环冷却水水质标准。     

小型海淡系统的自增压能量回收装置

运用自增压正位移泵的蓄能增压原理,研制了自增压正位移泵以回收小型反渗透系统的浓水排放能量。试验结果表明,该装置及其小型反渗透海水淡化系统运行性能稳定,产水水质、水量均满足设计要求,系统吨水能耗可降至4.2 kW·h/m~3以下。     

风光互补海水淡化系统的技术经济分析

介绍了5 m~3/d风光互补发电反渗透海水淡化装置,阐述其工艺方案、设备选型、控制模式、功率及电耗,并从装置的建设投资费用、运行维护费用、制水成本3方面进行经济分析,表明该装置综合制水成本约为13.77元/m~3。归纳总结出风光互补发电海水淡化系统的经济性影响因素,并建议进一步研究蓄电池的充放电控制、RO海水淡化工艺优化、高压泵和能量回收装置的合理选择等关键技术,以提升风光互补发电RO海水淡化系统的经济性。     

钢铁企业海水淡化工程实例

某钢铁公司对电厂冷却用海水进行淡化脱盐处理用于其工业生产,以该海水淡化厂工程为例,介绍了采用"折板絮凝沉淀+V型滤池+UF+SWRO+二级BWRO"海水淡化工艺的设计与应用情况.运行效果表明,该反渗透法海水淡化工艺,搭配折板絮凝沉淀+V型滤池+UF预处理,长期运行产水水量与水质稳定,SWRO回收率与脱盐率达45％、98...     

正位移式阀控能量回收装置盐水连续进料过程特性研究

能量回收装置是反渗透海水淡化系统的关键设备之一，对降低系统运行能耗和造水成本至关重要。正位移式阀控能量回收装置以反渗透淡化系统排放的高压盐水作为进料，通过在水压缸中直接增压原料海水的方式来实现压力能回收利用。但在装置运行过程中常常存在高压盐水进料不连续（即流量有较大波动）等问题，直接影响了反渗透淡化系统运行的稳定性。本丈在分析造成上述问题原因的基础上，通过改进控制方案，使得高压盐水进料过程中的流量和压力波动问题得到有效解决，保证了盐水进料的连续性。针对阀控能量回收装置运行过程中低压进料海水仍存在流量和压力波动的现象，文章提出了两个具体的措施，即通过多套装置并联运行及在进料海水管路上设置旁路的方式来解决。     

Optimal design of an electrodialysis brackish water desalination plant

This paper considers the optimal design and operation of electrodialysis (ED) desalination plants. In general an ED plant aims to produce potable water from a high salinity source, like brackish water or high salinity water. The system is modelled mathematically as mixed-integer non-linear programming (MINLP) optimization problem, determining the number of desalination stages, the membrane area, the total required energy so as to minimise the total annualised cost of the investment accounting for both infrastructure and operating costs. Two examples from the literature illustrate the applicability of the proposed approach and evaluate the quality of the results obtained.     

Desalination using ambient air: simulation and energy optimization

This work applies to process design, simulation, analysis, and optimization to minimize the energy requirements for producing desalinated water using ambient air (humidification and dehumidification process). The only operating cost is for the use of air blower to supply air flowrate of 65-70 kmol/h. The production rate is 1 gpm of desalinated water per 2.25 gpm of saline water. By using process simulation and applying energy optimization concepts, the process parameters were manipulated and analyzed so that the feed saline water to the column is used to cool the exit air stream. The proposed approach reduced the solar energy requirement by 65%, and the cooling energy is eliminated. A case study is pursued to show the effectiveness of using process simulation and energy optimization concepts.     

A reverse osmosis desalting plant operated by gas turbines

Power plants in Kuwait use gas turbines (GT) only for a few hours to produce power at peak load times. Peak loadoccurs in the summer due to the air-conditioning load. As an example, the average number of operating hours for six gas turbines in the Doha East power plant was 16 in the summer of 2001. There is little concern about efficiency of these GT since they work for a very short time during the year. However, a recent increase in desalted seawater demand suggests the use of these GT to operate reverse osmosis (RO) desalting systems all year around. The summer outside design temperature in Kuwait for air-conditioning calculations is 48°C dry bulb temperature (DBT), and 28°C wet bulb temperature (WBT); but the ambient temperature can easily reach 60°C. Gas turbine power output and efficiency are drastically reduced by the increase in temperature of intake air to the gas turbine's compressor, especially during harsh Kuwaiti summer conditions. Thus, it is essential to investigate cooling of air intake to the GT compressor. The performance of a typical GT unit and its ability to produce desalted waterby a RO desalting system at different ambient temperatures are presented. Calculation of needed capacities for the cooling of intake air to the GT compressor was performed for evaporative cooling, single and multiple mechanical vapor compression cycles, and combined indirect evaporation cooling with the refrigeration system. The improvements of power output and efficiency due to the cooling of air intake of the GT and the resulting increase in desalted water are also presented.     

Simulation and Analysis of a Single‐Effect Thermal Vapor‐Compression Desalination System at Variable Operation Conditions

A mathematical model is developed to analyze a single‐effect thermal vapor compression (TVC) desalination system. The effects of the variation of operation conditions such as the intake seawater temperature and the mass flow rate of cooling water on the system performance are investigated for a specific desalination unit. The system performance is found to decrease when the intake seawater temperature is different from the design value. By adjusting the mass flow rate of cooling water, a better system performance can be obtained when the intake seawater temperature differs from the design conditions. Decreasing the cooling water flow rate to values lower than the design value can lead to a better performance when the intake seawater temperature is lower than the design value, and the system performance reaches a peak point when the cooling water flow rate decreases to a definite level. A better performance can also be obtained by increasing the cooling water flow rate to values higher than design value, when the intake seawater temperature is higher than the design value and the system performance also reaches a peak point when the cooling water flow rate increases to a definite level.     

Feasibility study and performance assessment for the integration of a steam-injected gas turbine and thermal desalination system

This study proposes a systematic approach for retrofitting a steam-injection gas turbine (SIGT) with a multi-effect thermal vapor compression (METVC) desalination system. The retrofitted unit's product cost of the fresh water (RUPC) was used as a performance criterion, which comprises the thermodynamic, economic, and environmental attributes when calculating the total annual cost of the SIGT–METVC system. For the feasibility study of retrofitting the SIGT plant with the METVC desalination system, the effects of two key parameters were analyzed using response surface methodology (RSM) based on a central composite design (CCD): the steam air ratio (SR) and the temperature difference between the effects of the METVC system (?T_METVC) on the fresh water production (Q_freshwater) and the net power generation (W_net) of the SIGT–METVC system. Multi-objective optimization (MOO) which minimizes the modified total annual cost (MTAC) and maximizes the fresh water flow rate was performed to optimize the RUPC of the SIGT–METVC system. The best Pareto optimal solution showed that the SIGT–METVC system with five effects is the best one among the systems with 4–6 effects. This system under optimal operating conditions can save 21.07% and 9.54% of the RUPC, compared to the systems with four and six effects, respectively.     

Desalting of subsurface water using spiral-wound reverse osmosis (RO) system: technical and economic assessment

Subsurface water rise is a major problem in Kuwait. The impact of this problem is manifested in surface water ponds, cracks in buildings, flooded basements and damaged roads. Dewatering this water of moderate salinity is necessary. Being in an arid area with very limited water resources, treatment and recycling of the subsurface water could be very important to a country like Kuwait. For this purpose, a pilot study was carried out by KISR to desalinate the subsurface water using the reverse osmosis (RO) technique. The main aim of this study is to assess the viability and economic feasibility of using RO technology. This paper outlines the results of over 8000 operating hours performance data of an RO plant utilizing spiral-wound membranes (SW) used to desalinate subsurface water with TDS of about 11,000 mg/1 and an economic feasibility evaluation. Results indicate that the (SW) RO system is a viable technique to desalinate this type of water. The improvements in TDS, COD and BOD were 99%, 96% and 42%, respectively. The economic feasibility evaluation indicates that the unit cost of desalting subsurface water by RO is 0.235 KD/m³ (0.776 US$/m³), which is considered to be economically feasible for a small-scale plant.     

Solar desalination using humidification—dehumidification technology

A numerical study has been carried out to investigate the performance of a simple solar desalination system using humidification—dehumidification processes. The desalination system consists of a solar air heater, humidifier, dehumidifier and a circulating air-driving component. The study covers the influence of different environmental, design, and operational parameters on the desalination system productivity. Environmental parameters include solar intensity, ambient temperature and wind speed. Design parameters include the solar heater base insulation, the humidifier and the dehumidifier effectiveness. Operational parameters include air circulation flow rate, feed water rate and temperature. The results indicated that the solar air heater (energy source) efficiency significantly influences system productivity. Increasing the solar intensity and ambient temperature and decreased wind velocity increases system productivity. Increasing the air flow rate up to 0.6 kg/s increases the productivity, after which it has no significant effect. The feed water flow rate has an insignificant influence on system productivity. The surprising result is that the dehumidifier effectiveness has an insignificant influence on system productivity, which has a very important implication for the system's economy. The physical explanation of this finding is given.     

Theoretical and experimental investigation of humidification-dehumidification desalination unit

A theoretical and experimental investigation of humidification-dehumidification desalination system is presented. The system is based on an open cycle for water and a closed cycle for the air stream. The air is circulated either by natural or forced circulation. The system modeling is based on various heat and mass balance equations and their numerical solution. The effect of operating parameters on the system characteristics has been investigated. An experimental test set-up has been fabricated and assembled. The set-up has been equipped with appropriate measuring and controlling devices. Detailed experiments have been carried out at various operating conditions and using several packing materials. The heat and mass transfer coefficients have been obtained experimentally and fitted in forms of empirical correlations.The results of the investigation have shown that the system productivity increases with the increase in the mass flow rate of water through the unit. Water temperature at condenser exit increases linearly with water temperature at humidifier inlet and it decreases as water flow rate increases. The higher water temperature at humidifier inlet or water flow rate, the higher is the air temperature and humidity ratio at condenser inlet and exit. A maximum productivity of 5.8 liter/h has been obtained using wooden slates packing and with forced air circulation. No significant improvement in the performance of the desalination unit has been achieved by forced circulation of air at high water temperatures. The average relative deviation of theoretical predictions from measurements is (− 0.9%) in the air temperature at condenser inlet, (3.8%) in the humidity ratio at condenser exit and (− 1%) in the water temperature at condenser exit.     

Theoretical study on multi-effect solar distillation system driven by tidal energy

Based on an analysis of the characteristics of solar and tidal energy, an innovative, multi-effect solar distillation unit for seawater desalination utilizing solar and tidal energy has been developed. The uniqueness of the system is that without being transferred to electricity, tidal energy is utilized to supply power for water supply and drainage, and vacuum extraction instead of pumps powered by electricity. So the cost can be greatly reduced. The system is based on multi-effect evaporation-condensation processes and operates under vacuum condition, so low grade solar heat can be used with a high thermal efficiency. Hydrodynamic and thermal analysis is carried out for the water supply and drainage system driven by tidal energy. The operating mechanism of the vacuum extraction system driven by tidal energy is presented. A parametric study of the behavior of the solar desalination unit has been performed.     

Performance prediction of hydraulic energy recovery (HER) device with novel mechanics for small-scale SWRO desalination system

The biggest proportion of the cost of desalted water is the energy consumption, especially for small-scale SWRO desalination system. In order to decrease the cost of desalted water, the energy recovery device is preferred to be considered in small-scale SWRO desalination system. However, the investigation of energy recovery device for small-scale SWRO system is scarce. Until now the design of energy recovery device has not been based on the results of the mathematical simulation but almost on experimental and empirical knowledge, and there are few detailed reports about the optimal design of energy recovery device for small-scale SWRO desalination system in previous articles. In the current paper, a hydraulic energy recovery (HER) device with novel mechanics is introduced, the detailed simulation results of the HER device and specific energy consumption of small-scale SWRO system equipped with the HER device are presented. The simulated results are very useful for optimal design of the HER device and its coupling SWRO desalination system.