Ohmic drops in the ion-exchange bed of cationic electrodeionisation cells

The work was aimed at investigating the ohmic drop in ion-exchanging resin beds in EDI cells, by using two techniques. The case of CuSO₄–H₂SO₄ solutions was treated here, using Dowex resins of various degrees of cross-linking. Impedance measurements in a dedicated cell filled with resin packed beds were interpreted by using a model for the conductivity of two-phase media. Secondly, the voltage recorded in a small EDI cell for continuous treatment of copper solutions, led to the bed conductivity, using a model for potential distribution in the cell. The consistency of the two techniques was discussed, and side electrical phenomena in the EDI cell were shown to be the source of an unexpectedly significant increase in the cell voltage.     

荣成万吨级反渗透海水淡化示范工程

本文叙述了荣成万吨级反渗透海水淡化示范工程项目第一期工程的工艺设计，设备配置，系统控制和平面布置的基本情况。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。根据该项目投资和当地情况，概要地分析了该系统的造水成本，经济和社会效益。     

A science and technology with rich vitality — desalination

Congratulations toDesalination for its prosperity and for the contributions it has made to benefit mankind. Review the past and look forward to the future for the development of desalination technologies in China.     

改进软化水生产工艺实现降本增效

齐鲁石化公司炼油厂软化水站原生产工艺存在消耗高、周期制水量少的问题。为解决这一问题,进行了简单的工艺改造。将氢离子交换器内树脂由001×7型改为D113型,利用D113树脂工交大、易再生的优点,达到节水降耗的目的,取得了显著的经济效益。     

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.     

The part of the private sector in global water planning: the role of desalination

Water is the key to further development. The private sector is already playing a major role in looking into alternatives for a balanced water supply situation with the help of advanced technologies. We were generously given many Gardens of Eden, but only a few will survive into the next century. A worldwide campaign is necessary to show the scarcity of water. The United Nations Habitat II Conference in Istanbul, June 3–14, 1996, and the preceding IDA World Conference in Abu Dhabi on Desalination and Water Sciences, 18–24 November, 1995, are the immediate platforms on which international institutions and multilateral development banks can discuss this topic and help formulate an agenda for the next century.     

Novel water treatment process — combined cationic ion-exchange bed and degasifier in a three-phase fluidized bed

A novel water treatment process, combining cationic ion exchange and bicarbonate removal in a countercurrent three-phase fluidized bed, was explored. The study was based around a laboratory scale bed. The different operating conditions and effluent quality were investigated. The results showed that concentrations of sodium and carbon dioxide in effluent decreased with increasing height of resin static layer and greater airflow velocity. The concentration of sodium and carbon dioxide in the effluent was lower than 0.1 mg/l and 5 mg/l respectively. Instantaneous conductivity that illustrated effluent quality was measured in different sections of the bed. A mathematical modeling which can simulate the changing of conductivity was built, the validity and applicability of the model for future prediction of effluent properties have been verified by the good agreement between the experimental and predicted values.     

软化水硬度实时监测钠离子交换器的设计

钠离子交换器调节松床、再生、清洗等步骤的运行时间需要依据其所产水的硬度指标,而目前对水质硬度的检测大多采用人工完成,不仅操作繁琐,而且不能实时监测软化水的硬度指标。为解决这一问题,以微控制器STM32F103RB为核心,通过专门设计的检测容器中的钙离子选择性电极对交换器的出水硬度进行实时监测,根据检测到的硬度指标自动调整各步骤的运行时间,达到降低成本、提高效率的目的。     

CARRIER-GAS DESALINATION ANALYSIS USING HUMIDIFICATION- DEHUMIDIFICATION CYCLE

Analysis of data from a staged humidification-dehumidification desalination process, using air as a carrier-gas (Dewvaporation process), reveals that the energy reuse factor, f and molar production flux, Pf (kgmoles/m²hr) are quantitatively related to the maximum temperature of saturated evaporation and the number of stages employed, N. The data spanned 3 <f< 25 with 1 < Pf< 4. The f*Pf relationship identifies a hyperbolic form for the case of realistic but large number of stages, N. The relationship can be used to elucidate the effective dry gas heat transfer coefficient from data and, in another form, predict the number of stages needed to satisfy a design after selection of the, f Pf, and the maximum temperature of water saturation. In all cases, the number of stages must exceed the desired energy reuse factor, f by an order of magnitude in order to reduce the detrimental effect of the number of stages on the f*Pf product to only 10%. For water containing up to 7000?ppm total dissolved solids (TDS), the detrimental effect of the boiling point elevation on the f*Pf product is also only 10%,     

Analysis of a mechanical vapor compression desalination system

The mechanical vapor compression (MVC) desalination system is based on distillation of seawater. The system is basically a heat exchanger that is an evaporator/condenser. The heat required to evaporate water which flows on one side of a heat transfer surface is supplied through the simultaneous condensation of the distillate-producing vapor on the other side of the surface. That is, the latent heat is exchanged in the evaporation—condensation process within the system. A compressor is the driving force for this heat transfer and provides the energy required separating the solution and overcoming dynamic pressure losses and other irreversibilities. In this study, the operation characteristics of a low-temperature MVC desalination system are investigated. In the modeling, the overall energy balance and mass balance equations and LMTD method for heat transfer are used. The tube diameter and the tube length were taken at 0.025 m and 9 m, respectively. The main dependent parameters, the compressor work and the mass flow rate of the distilled water, were investigated against the independent parameters, the evaporation side pressure, the condensation side pressure, and the water inlet temperature.     

离子色谱法测定水的硬度

EDTA法测定硬度时,某些水样干扰严重,硬度不易测准。采用离子色谱法来测定硬度,可避免此类干扰。将水样经0.45μm微孔膜过滤后一次进样,同时测出水样中的钙、镁离子含量,然后换算成以碳酸钙表示的硬度,该方法的回收率在98.2%～102.0%之间,相对标准偏差为0.94%～1.21%。     

高负硬度矿井水脱碱处理工艺研究

针对河南某矿井水处理站供水碱度过高,导致碱度严重超过回用水水质指标,采用药剂法和离子交换法去除碱度。试验结果表明:Ca(OH)_2-CaCl_2脱碱法中Ca(OH)2最佳投加量为350 mg/L,CaCl_2最佳投加量为400mg/L,去除率达86.1%,药剂成本为0.549元/m~3;NaOH-CaCl_2脱碱法中NaOH最佳投加量为350 mg/L,CaCl_2最佳投加量为850 mg/L,去除率达87.9%,药剂成本为1.555元/m3;氯型树脂脱碱法的出水脱碱率可达到99.9%,药剂成本为0.423元/m3。综合考虑出水水质和药剂成本等因素,可选用氯型树脂脱碱工艺处理矿井水。     

复杂环境下粉煤灰水泥石的离子浓度分布与维氏硬度劣化规律

地铁工程混凝土结构处于硫酸盐、氯盐及杂散电流共存的复杂环境。本文针对地铁工程环境下混凝土的耐久性问题,研究了硫酸盐、氯盐及电场共同作用下,粉煤灰掺量对水泥石内硫酸根离子浓度分布、氯离子浓度分布和维氏硬度分布的影响,并基于Logistic函数建立维氏硬度预测模型,最后采用XRD分析了水泥石劣化的机理。结果表明:随侵蚀深度的增加,水泥石内硫酸根离子浓度不断降低,氯离子浓度呈现先增后降的趋势;侵入水泥石的氯离子和硫酸根离子的含量都随粉煤灰掺量的增加而先减后增,当粉煤灰掺量为10%(质量分数)时,侵入水泥石的氯离子与硫酸根离子的含量最低;被侵蚀后的水泥石内维氏硬度分布分为劣化区、增强区和完好区三个区域;预测模型可以准确表征水泥石内维氏硬度分布规律;适量粉煤灰的掺入可以减少受侵蚀后试件内的钙矾石(AFt)和石膏含量。     

Effect of sulfate ions for sol–gel synthesis of titania photocatalyst

We have found that the use of sulfuric acid in the peptization process of sol–gel method produced SO₄²⁻-incorporated TiO₂ which is mechanically strong by firing at low temperature such as 200°C. The synthesized TiO₂ has larger specific surface area and retards the phase transition from anatase to rutile compared with that prepared from the peptization with nitric acid. The S-content of the TiO₂ fired at 200°C was 1.52 wt.%; the value has a maximum of 2.74 wt.% at 400°C. The XPS measurements indicate that S exists mainly as SO₄²⁻. The TiO₂ fired at 400°C showed the highest photocatalytic activity for ethylene degradation. Especially, we would like to emphasize the TiO₂ sintered at 200°C because they are extremely hard in spite of such a low sintering temperature. This photocatalyst may provide a great opportunity for extensive applications as self-supporting membranes.     

多通道流动电泳的计算流体力学模拟与实验研究(Ⅰ)离子分布模型

多通道流动电泳（MFE）是一种制备型流动电泳技术,采用计算流体力学方法描述MFE设备中的流体流动特性,以指导分离过程和分离设备设计.基于MFE分离过程中离子迁移方程、电解质解离方程和电中性方程建立描述各腔室pH值及离子分布的模型,并通过实验进行了验证.为后续计算流体力学模拟各腔室流场分布提供了基础.     

Seasonal fouling on seawater desalination RO membrane

A pilot study has been performed to investigate the seasonal characteristic of seawater reverse osmosis (RO) membrane fouling. Two batches of experiment during summer and winter were both performed 18 days to provide a clear picture on microbial population variability. The feed water of the pilot from seawater desalination plant has significant difference in temperature and silica content between the two seasons.In our experiments, scaling and biofouling are more serious in summer. And the permeate flux decline is closely related to the rise in microbial population, and it was dominated by cell multiplication rather than adhesion. In addition, the summer cell multiplication is much more abundant. Moreover, the extracellular polymeric substance (EPS) feature intensity detected by Fourier-transform infrared spectroscopy was also stronger in summer. The abundant EPS was one of the major reasons to cause the inorganic matter adsorption. Si, Al, Fe, Ca and Mg were found as the major inorganic foulants deposited on the Ro membranes. Silica and calcium in summer appeared obvious higher amounts than that in winter, which indicated that they should be affected by microbial action directly or indirectly more than other elements.In summary, there exists a seasonal effect on membrane scaling and fouling, and scaling is associated with biofouling in some degree. Further researches could be focus on actual association between microbial action and inorganic fouling.     

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.