海水替代淡水在江蓠加工中的应用研究

用海水替代淡水进行江蓠加工生产,是解决江蓠加工需要消耗大量淡水的有效途径,具有良好的社会效益和经济效益。实验结果表明,通过pH控制,使海水的pH=6．O～6,5,使用0．55％HCl作为酸化液,0.40％H2C2O4作为二次酸化、增白液,海水完全可以用于江蓠的加工生产,替代率高达73％。     

Flotation of a carbonate rich sedimentary phosphate rock

A large portion of the world's phosphate reserves are sedimentary type containing appreciable amounts of carbonate minerals. These are the most difficult type of deposits to beneficiate. The depletion of other reserves easier to beneficiate, necessitates research to find methods of mineral processing for carbonate rich sedimentary phosphate deposits. In this study, a new flotation method is described which was applied successfully in a laboratory scale flotation cell. Flotation of Al-Jalamid phosphate rock (sedimentary type with high carbonates and low silica content) found in northern Saudi Arabia was studied using a fatty acid as collector and sodium sulfate as a flotation aid.     

Nature of carbonaceous deposits on the alumina supported transition metal oxide catalysts in the wet air oxidation of phenol

Al₂O₃ supported transition metal (Mn, Fe, Co, Ni, and Cu) oxide catalysts were prepared and tested for the wet oxidation of phenol. The supported copper oxide catalysts showed the highest catalytic activity due to their highest surface reducibility. There was carbonaceous deposits on the used catalysts for the wet oxidation of phenol and the supported manganese oxide catalysts showed the highest amount of carbonaceous deposits. These carbonaceous deposits must have their own micropores which resulted in the decrease of the pore volume and the increase of the surface area. The NMR and FTIR spectroscopy showed that the carbonaceous deposits were mostly of aromatic nature and contained some oxygen-bearing groups such as carboxylic acids and alcohols.     

Study on deactivation of Cu–Zn–Al catalysts in the synthesis of N-ethylethylenediamine

The performance of a Cu–Zn–Al catalyst employed in the synthesis of N-ethylethylenediamine from ethylenediamine and ethanol was studied. The results showed that the activity of the Cu–Zn–Al catalyst decreased with time-on-stream. Fresh and deactivated catalysts were characterized by XRD, XPS, N₂ adsorption–desorption and TEM. It was found that the crystallite size of Cu and ZnO in the deactivated catalyst were much bigger than those for the fresh catalyst. In addition, channels in the deactivated catalyst were blocked by carbonaceous deposits, so the surface area and pore volumes of the deactivated catalyst were much smaller than in the fresh catalyst. Therefore, it was concluded that the deactivation of the Cu–Zn–Al catalyst was mainly caused by the growth in the Cu and ZnO crystallite sizes and carbonaceous deposits.     

Solar stills made with tubes for sea water desalting

The report concerns basic technological features of simple solar stills utilizing tubes for sea water desalting. The evaporation section comprises horizontal transparent thin-walled plastic or glass tubes, of ~0.10–0.25 m inner diameter, half-filled with sea water which absorbs solar radiation. The condensation section is physically separated from the evaporation section, in a shaded space below it, and comprises horizontal plastic or metal tubes of ~0.01 m inner diameter. The wall thickness of condenser plastic tubes is rather small, ~50 μm.

Water vapour released by solar radiation in evaporator tubes flows into condenser tubes to be condensed into produced fresh water by delivering condensation latent heat to atmospheric air. Heat transfer by air convection may be helped by surface winds, often available in coastal areas. Enhanced fresh water productivity is expected with respect to conventional solar stills in which sea water evaporation and water vapour condensation occur in one confined space. Technological features of the proposed solar stills are analysed in some detail and specific experimental work is suggested on prototype solar stills in view of clarifying relevant aspects concerning transparent and opaque construction materials, assembling procedures, and the role of the various operative parameters vis-à-vis energy efficiency and fresh water productivity.     

Assessment of energy consumption in desalination of sea water on the basis of conceptual designs and surveys

Energy equivalent of sea water desalination are quoted as the most suitable measure in the phase discussing here from various survey reports in Japan which include conceptual designs of desalting plants such as dual purpose systems and MSF processes to utilize industrial waste heats.These systems are alloted for supplementing the shortage of drinking water from rivers which may dependent on the rainfall. Then, a diagram is proposed to indicate preferable region for construction of desalting plants or river development from view points of both energy consumption and economyThese ideas were applied to the survey for introducting desalting plant in an industrial city and the necessary energy to produce fresh water from the sea was estimated for the case of 1/10 arid year. The amount of the order of a little less than 1% to the total energy consumption of the city should be evaluated from the view point of total human activities     

海水淡化工艺装备研发现状

随着全球淡水资源紧缺区域增多，在过去的数十年里淡化海水因其来源广且不受降雨影响，而成为解决淡水短缺的可行方案，并得到越来越多关注和发展。海水淡化工艺（即脱盐）将海水分为两部分：淡水和高浓度的盐水。虽然海水淡化的工艺装备和支撑技术已经相当成熟，但为了不断提高技术并降低成本，国内外进行了大量的研究。该文概述了海水淡化主流技术的研究现状、工程项目以及新工艺。另外归纳了海水淡化工艺装备存在的一般问题，结合“十二五”规划，指出了海水淡化的研究方向。     

Stability of Pt/γ-Al2O3 Catalysts in Model Biomass Solutions

The stability of a Pt/??-Al₂O₃ catalyst in liquid water and aqueous solutions of 5?wt% glycerol or sorbitol at 225?°C is examined using a variety of physicochemical methods. It is demonstrated that the presence of glycerol and sorbitol significantly reduces the hydration of ??-Al₂O₃ to form boehmite as compared to treatment in pure water. The stability against hydration increases with increasing carbon chain length. Treatment with polyol solutions also results in reduced agglomeration of supported metal particles. The prevention of boehmite formation and agglomeration of metal particles are attributed to the formation of carbonaceous species on the surface. In addition to these effects, the deposits block a considerable portion of active metal surface area. IR spectroscopic analysis indicates that dehydration reactions play an important role in the formation of the carbonaceous deposits. The present results illustrate that water and dissolved biomass compounds can strongly affect the stability of heterogeneous catalysts under reaction conditions.     

The characterization of carbonaceous species from CO hydrogenation on single crystal Ru(0001) and Ru(11¯20) catalysts with high-resolution electron energy-loss spectroscopy

The CO hydrogenation on single-crystal ruthenium catalysts has been studied utilizing an elevated-pressure micro-reactor and high resolution electron energy loss spectroscopy (HREELS). It is found that carbonaceous deposits identified following CO hydrogenation are essentially identical to those observed in the study of methane decomposition. Three distinct forms of carbonaceous intermediates are identified; these are methylidyne (CH), vinylidene (CCH₂), and graphitic carbonaceous species.     

Catalytic steam reforming of chlorocarbons: trichloroethane, trichloroethylene and perchloroethylene

The effective destruction of trichloroethane, trichloroethylene and perchloroethylene by steam reforming with a commercial nickel catalyst has been demonstrated. Conversion levels of up to 0.99999 were attained in both laboratory and semi-pilot experiments, with the products consisting of HCl, H₂ and carbon oxides. Care had to be exercised in maintaining these high conversion levels to prevent parallel pyrolysis reactions that resulted in carbonaceous deposits and catalyst deactivation. The importance of these pyrolysis reactions appears to follow established incinerability patterns and is more pronounced for alkanes than alkenes.

By using relatively large amounts of catalyst in the large semi-pilot reactor, it was possible to maintain high conversions for up to 50 h without appreciable carbon deposition in the bed. However, the activity of the catalyst for the water gas shift reaction declined progressively with process time. This deactivation effect was reversed by treatment with steam over prolonged periods, leading to the speculation that shift activity is poisoned by exposure to HCl in the product.

This process offers an attractive alternative to conventional technologies (thermal incineration and catalytic combustion) for the destruction of chlorocarbons used as industrial solvents or found in waste streams, and applicable process conditions are given.     

Microscopic investigation of carbonaceous deposits formed in a solvent-treated coal reactor

The mode of occurrence and optical characteristics of the carbonaceous deposits from a 3 t/d process development unit solvent-treated coal reactor were investigated by optical microscopy to increase understanding of the formation and development of reactor blockage materials such as mesophase and semicoke. The solid deposits showed a layered texture consisting of mesophase matrix as a binder, particles of non-plastic coal, pyrolytic carbon and mineral matter. The layered appearance of the deposits was due to variations in the proportions of the microscopic constituents and pores. The variations in reflectance values of the carbonaceous deposits from the centre of the reactor to the wall provided evidence of the thermal alteration after deposition. Based on these results, the formation and sedimentation of carbonaceous deposits and subsequent secondary alteration processes are discussed.     

Removal of Carbonaceous Residue with Wet Hydrogen in Greensheet Processing for Multilayer Ceramic Module: I, Residue Formation and Intrinsic Chemical Kinetics

An experimental and mathematical investigation of the removal of carbonaceous residue deposited on the ceramic substrate in the fabrication of multilayer ceramic modules has been conducted. Such carbonaceous residue is formed when the organic binder is pyrolyzed during the firing of greensheets. This Part I is concerned specifically with the formation of carbonaceous residue and the intrinsic kinetics of its subsequent removal in a mixture of water vapor with hydrogen. The reaction is of first order with respect to the amount of the carbonaceous residue and depends on the water vapor and hydrogen partial pressures according to a Langmuir-Hinshelwood kinetic expression.     

Fresh water,energy, and food from the sea and the sun

Surface waters of tropic and sub-tropic seas hold most of the solar energy retained by the earth; but the heat therein may be increased even more by heat which can be added by intensive solar heaters. The sea water so heated naturally or additionally by the sun, when flash evaporated, gives vapors which may be passed through a heat engine to give power, then condensed at a lower pressure to give fresh water, which may be much more valuable than the power produced. Heat of condensation is removed by circulating cold sea water from a depth of a few thousand feet. This water from the deep also has considerable nutrients for sea plants and animals coming from the degradation of former sea life; and these nutrients may be used in well studied mariculture systems to grow commercial food fish in ponds adjacent the land-based plant. Various arrangements of flows of the several liquid streams are presented to illustrate variations to the process which will produce fresh water and/or electric power, also food fish. These modifications may be optimized with various component systems, some of which are well known and evaluated in this usage, including the use of a second thermodynamic fluid, conventional multistage flash evaporation, also two of its variations: Controlled Flash Evaporation and Vapor Reheat. Calculations indicate that even without the use of intensive solar heaters, a profitable desalination and mariculture operation may be expected which would pay for its substantial cost in two or three years of profits; however, the incorporation of certain intensive solar heaters may increase the profitability significantly.     

An electrodialysis sea water desalination system powered by photovoltaic cells

An electrodialysis sea water desalination system powered by photovoltaic (PV) cells is beeing developed. In this sort of system, the most important subject is a way to apply the varying electric power from the PV cells directry to electrodialysis with a small capacity lead battery. We use a partially desalinated water (PDW) storage system for this. When a large electric output from the PV cells is obtained, sea water is desalinated to partially desalinated water (PDW: salinity of which is between sea water and fresh water) and when a small output is obtained, the desalination from PDW to fresh water is completed. In this system, as varying outputs from the PV cells are used directly in electrodialysis, the capacity of the lead battery is reduced, and an economical system is realized. A demonstration plant (capacity: 10m/day) was constructed for this system, and has been operating since June, 1986.     

An experimental study on an inclined solar water distillation system

An inclined solar water distillation system was designed and tested under actual environmental conditions of northern Cyprus. Unlike solar still systems, the feed water falls down on the solar absorber plate, and the system produces fresh water and hot water simultaneously. It was suspected that the longer the flowing water is held on the absorber plate, the greater the rate of evaporation, leading to an increase in the amount of distilled water. Therefore, the system was tested with three variants: bare plate, black-cloth wick, and black-fleece wick. As was expected, the wicks increased the fresh water generation by two or three times of a bare plate. The hot water temperature was good enough for domestic usage.     

The effect of oxygen on the aromatization of methane over the Mo/HZSM‐5 catalyst

The aromatization of methane over a Mo/HZSM‐5 catalyst was carried out in the presence of oxygen. It is shown that the addition of a small amount of oxygen is beneficial to improve the durability of the catalyst. UV‐Raman spectra disclose that the carbonaceous deposits formed on the HZSM‐5 are mainly polyolefinic and aromatic, while that on the Mo/HZSM‐5 is mainly polyaromatic. The small amount of O₂ added may partly remove the coke deposits on the active sites and keep the catalyst as MoO_xC_y/HZSM‐5, thus resulting in an improvement of the catalytic performance of the Mo/HZSM‐5 catalyst. This revised version was published online in July 2006 with corrections to the Cover Date.     

Environmental impacts of the mega desalination project: the Red–Dead Sea conveyor

The Dead Sea is the lowest point on the earth. Historically, its level was 392 m below sea level. Due to the diversion of the water that is feeding the sea from the north and to the construction of industrial facilities in the south to extract minerals, the Dead Sea level nowadays has been lowered to 417 m. Furthermore, the surface area of the sea has been reduced from 940 km² in 1960s to 637 km² today.

In an attempt to restore the Dead Sea to its original level, and to find a reliable source of fresh water in the region which suffers from chronic water scarcity, the Red Dead Sea conveyor (RDSC) project has been proposed. RDSC would convey seawater from the Red Sea (Gulf of Aqaba) to the Dead Sea to save it from vanishing, and to produce desalinated water and hydroelectric power by utilizing the difference in elevations between the Red and Dead seas.

The proposed project is expected to have great impact on the regional socio-economic development. However, many questions need to be answered before proceeding with such a mega project. Some of the answers needed are related to the environmental impacts of the project. The present paper is an attempt to address the major environmental impacts associated with the implementation of the RDSC project. Both positive and negative impacts were considered in the analysis.

The analysis revealed that brine reject is the main adverse environmental problem. The amount of brine has been estimated to be 1050 MCM/y. In addition to salt content, the reject brine contains several chemical additives, chemical cleaning solutions and pretreatment chemicals that are discharged with the brine. Another significant adverse impact that is identified is the impact on the fragile marine environment of the Gulf of Aqaba. The semi enclosed nature of this marine environment, which encourages its unique biological diversity, also makes it particularly susceptible to pollution. Therefore, measures that should be taken during the construction and operation of the project to protect the marine environment were recommended.     

An electrodialysis sea water desalination system powered by photovoltaic cells

An electrodialysis sea water desalination system powered by photovoltaic (PV) cells is beeing developed. In this sort of system, the most important subject is a way to apply the varying electric power from the PV cells directry to electrodialysis with a small capacity lead battery. We use a partially desalinated water (PDW) storage system for this. When a large electric output from the PV cells is obtained, sea water is desalinated to partially desalinated water (PDW:salinity of which is between sea water and fresh water) and when a small output is obtained, the desalination from PDW to fresh water is completed. In this system, as varying outputs from the PV cells are used directly in electrodialysis, the capacity of the lead battery is reduced, and an economical system is realized. A demonstration plant (capacity:10m³/day) was constructed for this system, and has been operating since June, 1986.     

Carbonation of the hydration products of tricalcium silicate

C₃S has been hydrated for increasing time and stored for 2.5 years under normal atmosphere, the fresh and aged materials being characterized by X-ray diffraction and infrared spectroscopy. The carbonation occuring during storage gives rise to complete disappearance of CSH gel while portlandite remains in appreciable amount; the siliceous residue is an amorphous silica similar to common silica gels. The carbonates formed are vaterite and aragonite, the latter being relatively more important in samples with a low degree of hydration.     

Humidification-dehumidification desalination system driven by geothermal energy

The work presented in this paper focuses on desalinating sea water system using a humidification-dehumidification process as it is supplied with water heated by geothermal energy as clean and renewable natural resources of energy. Computer simulation of the behavior under various working conditions of the desalination system was carried out to predict the variations of key output. Such variables include the ratio of sea water mass flow rate related to air mass flow rate, cooling water temperature difference across the condenser, geothermal source inlet temperatures to the heat exchanger and the amount of produced distilled water. To validate the computer program, a comparison between the experimental and theoretical results was conducted, and a good agreement had been obtained. The result showed that, the optimum value of the ratio between sea water mass flow rate to air mass flow rate was found to be in the range of 1.5 to 2.5. Improvement in the fresh water productivity at the optimum ratio of sea water mass flow rate to the air flow rate was observed by increasing both the geothermal source inlet temperature and the cooling water temperature difference across the condenser.