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。     

Evaluation of various additives at Jubail phase I during reliability trials

Jubail Phase I consists of 6 dual purpose units, each having a boiler, turbine and desalination unit. Total design output is 30.06 mIgd of distillate and 360 MW of power, each desalination unit designed to produce 5.01 mIgd at maximum brine recycle temperature of 90.6°C using polyphosphate as the scale control additive. Long operating experience with polyphosphate [1] showed it to be a moderately effective scale control additive. It was decided to evaluate other additives available on the market, compare their effectiveness for scale control, and to conclude which one would give longest operating time before the plant performance ratio drops necessitating acid cleaning. Belgard EVN was employed as the scale control additive during commissioning and reliability trials of unit Nos. 1 and 3. Albrivap B and Flocon 247 were used on unit Nos. 2 and 4, respectively. This paper presents experience with these additives during the first four reliability trials.     

氨气提工艺尿素生产中操作的改进

实验证明,由Snam公司提供的尿素操作方法与实际状况出入很大。为此,通过降低高压系统 的氨碳比、关闭中压氨冷凝器至液氨贮槽的气相切断阀、提高低压分解温度、改进二氧化碳压缩机 、水解装置和高压甲铵泵的操作方法等措施,使尿素装置达到了安全、稳定、经济运行的目的。     

Hybrid systems in seawater desalination—practical design aspects, present status and development perspectives

Ever since seawater desalination has been applied on an industrial scale, and particular in the countries of the Arabian Gulf, the application of desalination processes in dual-purpose facilities—water and power—as a hybrid configuration has been discussed in many feasibility investigations and also planning concepts. It is above all the combination of reverse osmosis with thermal processes that has found increasing interest with the aim of ensuring, as economically as possible, uniform water supplies under the specific, greatly varying load conditions in the Gulf countries. Such design concepts for hybrid configurations encompass straightforward structures with a low degree of coupling between membrane and thermal desalination processes, but range up to very complex configurations with strong interconnections on both the water side and thermally, as well as with several desalination processes connected in series or in parallel. Classical hybrid concepts in which the permeate from an RO desalination component is mixed with distillate from thermal desalination have already been implemented in Saudi Arabian dual-purpose plants, like Jeddah and Yanbu-Medina. Although hybrid systems of greater complexity have been addressed in many design studies and publications, up to now none has been brought to fruition. Coming into consideration asthe design basis for determining the capacity shares of the various desalination processes operated in a hybrid configuration are: arrangement of thermal cycle of the power plant component; water/power ratio of the dual-purpose seawater desalination and power plant; provision of undiminished water production of the desalination plant as electricity generation varies; provision of a specified drinking water quality with regard to composition and salt content; combination of all these aspects. Also gaining in importance are concerns of environmental pollution and sustainable development when selecting seawater desalination and power plant configurations, as well as their optimization when considering desalination and electricity generation as a whole. In the practical design of hybrid membrane and thermal systems, aspects come to light, though, that restrict linking of the two systems and joint utilization of facilities, as conceived in studies and conceptual design investigations. This applies both for common utilization of intakes and the use of heated up cooling water from thermal processes as a feed stream for the RO part of the desalination process. Additionally, requirements of drinking water composition, particularly chloride content, TDS and compliance with a specific residual content of boron, influence specifically the design of the membrane process part and its share in the total desalination capacity. Such practical aspects have greatly influenced the design and configuration of the Fujairah hybrid plant for which, from a total desalination capacity of 100 MIGD (454,600 m³/d), the share of 37.5 MIGD (170,500 m³/d) makes its seawater RO plant the biggest currently being constructed anywhere in the world. From the findings of the engineering of this plant and the idea that, by increasing interconnection between the two processes on the water side, it is possible to advance a hybrid configuration of this type with regard to cost optimization in the membrane installation, but also by joint utilization of the intake equipment, perspectives result for applied research efforts over the near and long terms, for example: long-term behavior of membranes at elevated temperatures; tendency for biofouling in membrane process with common utilization of cooling water and brine; influences of such interconnections on the overall availability of the facility. But also for the operation and maintenance organization of such large facilities, consequences can be foreseen for the future development of hybrid plants, particularly for operation management and organisation of the interplay of the different power plant and desalination systems, monitoring of SWRO membrane replacement and cleaning, as well as controlling water quality.     

Industrial experiences of electric filtration in vegetable oil technology

Electric filtration is used to remove bleaching earth and other electrically charged particles from vegetable oils and fats. The grain size of bleaching earth does not significantly influence its separation during application of electric filtration. Therefore, it will be possible to separate bleaching earth with very small grains and increased capability for adsorption. The generation of an electrical field in an insulating fluid is the physical basis of the electric filtration, and under these conditions the generated Coulomb-power moves the bleaching earth grains to one of the electrodes where they will be separated. Electric filtration is available for industrial use. A modular unit enables the testing of all industrial applications directly in the refinery, and it permits the fulfilment of the requirements for the integration of an ÖHMI filtration^® unit in the whole process. Tests on a laboratory and a pilot plant scale have supplied the basis for smooth running of the first industrial plant installed in a large German edible oil refinery. Compact electric filtration plants enable a bleaching earth filtration largely independent of the grain size of the bleaching earth; they reduce the consumption of electric power, they can be adapted to each capacity due to the construction principal of the filter cell moduls, they decrease all expenditure of cleaning and the wear of the filter elements and clothes compared to the conventional cake filtration.     

MSF Desalination plants. Availability,reliability and safety analysis

While good MSF desalination plant performance exerts a positive influence on plant economics, as part of water supply systems in isolated regions, the availability of the desalination system becomes a major design criteria. Reliability problems have historically been a major cause of poor performance for desalination plants. The emphasis of this paper is on the importance of availability modeling methodology to MSF desalination plant reliability problems by providing a context in which the effect of unit unavailability can be quantified.An assessment is made of failures and outages which impact the availability of MSF desalination plants. Limited fault tree logic for system failures is developed and reliability data from the literature is incorporated, where possible. The impact of other water supply system failures on the reliability requirements of the desalination plant is quantified as are the effects of increased average water system demands.The single largest influence on the effective capacity of a water supply system based on MSF desalination of sea water is found to be the availability and maintainability of the desalination plant. Forced outages as a result of equipment failure are significant, but other dominant contributions to unit unavailability include externally caused problems, such as silting. The design configuration of the desalination plant is also found to have an impact on the acceptability of water supply system performance.     

混合碳四全加氢催化剂第一次再生过程分析

混合碳四来自丁二烯抽提装置和MTBE装置生产的含炔碳四、炼厂轻烃回收装置生产的重碳四,该部分碳四经过全加氢饱和其中的烯烃和炔烃后可作为裂解原料。混合碳四中烯烃含量(摩尔分数)较高,通常占65%以上。随着装置运行,烯烃在反应器中聚合、结焦,长时间累积会堵塞催化剂孔道,造成催化剂活性下降,床层压差升高,影响产品质量和装置运行,需要停车再生催化剂。分析了再生过程,评价了再生结果,为装置后续运行提供了理论基础。     

炼厂丙烯的精制处理

以实际生产为例,炼厂丙烯经过脱水、脱硫、再脱水精制后可达到聚合丙烯要求,为聚丙烯装置补充原料,满足聚丙烯装置高负荷生产需要,并确保聚丙烯产品质量。     

氨汽提尿素装置高压设备腐蚀状况分析

对运行了10a的氨汽提装置4台高压设备进行全面检测,根据大修期间腐蚀检测情况,结合设备自身的特点,论述斯那姆氨汽提尿素装置高压设备的腐蚀问题。     

Ultrafiltration membrane cleaning technology and mechanism based on seawater desalination pilot equipment

In order to clean the ultrafiltration membrane in the process of seawater desalination, this paper studied the cleaning effects of backwash water and chemical agents on the ultrafiltration membrane by using the ultrafiltration pilot equipment. Effects of different backwash water on the transmembrane pressure difference were studied. The results showed that the cleaning effect was in the order of fresh water (tap water) > ultrafiltration water > reverse osmosis concentrated water. In addition, cleaning effect was as follows: citric acid > oxalate > hydrochloric acid > sodium hypochlorite > sodium hydroxide. Citric acid had the best cleaning effect, and the pure water penetration rate could be restored from 283.24 L/(m²·h) to 571.56 L/(m²·h). Moreover, the effect of alkali washing and acid washing together is better than that of cleaning alone. After cleaning with sodium hydroxide and then citric acid, the pure water transmission rate can recover from 283.24 L/(m²·h) to 818.81 L/(m²·h). The results of this study have a good application prospect for the maintenance of ultrafiltration membrane in seawater desalination.     

Coupling of nuclear heating reactor with desalination process

A seawater desalination plant using a nuclear heating reactor (NHR) coupled with the multi-effect distillation (MED) process was developed by the Institute of Nuclear Energy Technology, Tsinghua University, China. The seawater desalination plant was designed to supply potable water demand to some coastal location or island where both fresh water and energy sources are severely lacking. The NHR design possesses intrinsic and passive safety features, which was demonstrated by the NHR-5 experiences. The intermediate circuit and steam circuit were designed as the safety barriers between the NHR and MED desalination systems. With the power range of the heating reactor within 10 to 200 MWt, the desalination plant could provide 8,000 to 160,000 m³/d of potable water of appropriate quality. The design concept and parameters, safety features, and comparative investigation of coupling schemes are presented in the paper.     

基于海水淡化中试的超滤膜清洗工艺及机理

为了对海水淡化过程中的超滤膜进行清洗,利用超滤中试设备研究了反洗水和清洗药剂对超滤膜清洗的效果。分别研究了不同的反洗用水对于跨膜压差的影响,结果表明,清洗效果：淡水（自来水）>超滤产水>反渗透浓水。另选用不同的酸性清洗剂与碱性清洗剂进行清洗,结果表明,清洗效果：柠檬酸>草酸>盐酸>次氯酸钠>氢氧化钠,柠檬酸清洗效果最好,纯水透过速率可从283.24 L/(m²·h)恢复至571.56 L/(m²·h)。此外,实验证明碱洗+酸洗效果优于单独清洗效果,先用氢氧化钠清洗,再用柠檬酸清洗,纯水透过速率可从283.24 L/(m²·h)恢复至818.81 L/(m²·h)。本研究成果对于海水淡化过程中超滤膜的维护具有较好的应用前景。     

Implications of desalination for water resources in China — an economic perspective

China is a country with severe water shortages. Water is becoming scarcer due to population growth, industrialization and urbanization. Recent studies show that by the next 50 years water resources per capita will go down to around 1700 m³, which is the threshold of severe water scarcity. Especially in North China, water shortage has become a critical constraint factor for socioeconomic development in the long run. To solve or eliminate water shortage problems, seawater desalination draws more and more attention as an alternative water supply source. The objective of the study is to assess the potential of desalination as a viable alternate water source for China through analysis of the costs of desalination, the water demand and supply situation as well as water pricing practices in China. Based on the investment costs and estimated operation and maintenance costs, an economic appraisal for the costs of desalination for two main processes, MSF and RO, has been conducted. The study shows that there is a decline of unit cost of desalination over time and the average unit cost of the RO process was lower than that of the MSF process. A unit cost of 0.6 $/m³ for desalting brackish water and 1.0 $/m³ for seawater are suggested to be appropriate for the potential application of desalination in China. Future trends and challenges associated with water shortages and water prices are discussed, leading to conclusions and recommendations regarding the role of desalination as a feasible source of water for the future.     

减压蒸馏塔的化学清洗

研究了炼油厂加工含硫原油蒸馏装置减压塔硫化亚铁的形成,装置停工检修时硫化亚铁自燃机理及其对装置的危害。介绍了减压蒸馏塔垢样的组成;清洗此种垢样,采用的碱洗方法,清洗机理,化学清洗剂的组成;采用塔器级联循环清洗方案,有效地吸收硫化氢,确保清洗过程安全环保,清洗效果良好,无二次浮锈生成。     

低碳环保型项目怎么建

发展绿色产业,走低碳发展道路是当今任何有社会责任但当的企业必然的选择,对于经济危机后全球新的政治经济环境,发展低碳环保型企业也是转变发展方式、寻找新的经济增长点的重要举措,具有重要的现实意义。＂加快推进节能减排,加快污染防治,加快建立资源     

重油催化循环水系统的不停车化学清洗

本文主要叙述了重油催化循环水系统在正常运行状态下，采用全有机复合化学清洗剂进行不停车清洗的方案及实施效果。由于采用了较有效的水处理剂和科学方案，使清洗过程安全可靠，便于操作和管理，降低了清洗成本，收到了比较理想的效果。     

Editorial

The first seawater desalination plant by electrodialysis in the world started its operation in September, 1974 at Noshima island of Hofu city, Yamaguchi Prefecture, Japan. The capacity of the plant is 120 m³/day and the plant has been supplying fresh water from the sea for the 800 inhabitants of the island. Batchwise operation is utilized to simplify the process because of its relatively small capacity, but the operation is fully automatic to supply fresh water continuously using a storage of proper capacity. The water cost is relatively high but lower than that of conventional distillation processes of the same capacity.     

Development and optimization of ME-TVC desalination system

Significant and rapid developments have taken place recently in the multi-effect thermal vapor compression (ME-TVC) desalination system of SIDEM Company, particularly in enlarging the unit capacity. The new trend of combining ME-TVC with conventional multi-effect has allowed this unit capacity to increase from two to eight million imperial gallons per day (MIGD) in the last decade. This considerable increase in capacity, poses a real competition to the multi stage flash system (MSF) as a large-scale production plant with lower operation temperatures.A steady state mathematical model of the ME-TVC desalination system is developed in this paper using Engineering Equations Solver (EES) to evaluate the model system performance. The model validity is examined against three commercial ME-TVC units which showed good results. The main improvements in the performance during the past ten years are also outlined and discussed. Another purpose of this paper is to determine the optimum operating and design conditions of the ME-TVC desalination system through mathematical modeling optimization. A MATLAB algorithm solution is developed and used to solve model equations, where a different number of effects were tested to maximize the gain ratio using (1) Smart Exhaustive Search Method and (2) Sequential Quadratic Programming. Results showed that the maximum gain ratio varied between 8.5 and 18.5 for 4 and 12 effects with the optimal top brine temperature ranging between 55.8 and 67.5 °C and a reasonable specific heat transfer area. The optimal ranges of compression and entrainment ratios are between 1.81 to 3.68 and 0.73 to 1.65 respectively. The optimal results of 4-effect TVC unit are also compared with three commercial 4-effect units having almost the same input, which showed that further improvement in the distillate output production, compression and entrainment ratio can be achieved by combining the ME-TVC system with conventional multi-effect unit.     

惠炼电脱盐工艺运行情况分析

文章介绍了高速直流电脱盐和高效交直流电脱盐组合式工艺在惠炼常减压装置的实际应用情况,通过实践数据验证,这套工艺的脱盐脱水效果较好,能耗状况较佳,表明这套工艺是一套经济可靠、性能优良的工艺.