Viscosity of sea water solutions

The kinematic viscosity of sea water solutions and concentrates up to 11% salt by weight and from 0 to 200°C have been measured in a pressurized glass capillary viscometer. All precipitation was prevented during testing; carbonates and hydroxides by slight acidification (to pH 4.5) with concentrated (36N) sulfuric acid, and calcium sulfate by preheating and filtration under pressure. The precision of the results is ± 0.001 centistokes. Existing data on density of sea water solutions were correlated and used to calculate the dynamic viscosity in centipoises. Smoothed values presented should be accurate to ± 0.003 centipoises above 20°C and ± 0.005 below 20°. The results compare well with other authors' values for synthetic sea water.     

Drinking water from sea water by forward osmosis

Potable water may be extracted from a saline source, such as the ocean, using a concentrated solution of nutrients and a semipermeable membrane. This paper applies the previously presented theory (1) of the forward osmosis extractor to this case and compares that theory with experiment. Theory and experiment are found to match well. Calculated and observed magnitudes of water extraction rate and nutrient utilization indicate that practical devices may be constructed. It is found that the volume of water obtained per mass of nutrient meets the human requirement for fluids and nutrient. Optimization of the system is discussed.     

Reverse osmosis in the desalination of brackish water and sea water

To make RO an economical process, plant and operating costs have been reduced by developing compact modules, led by polyamide hollow fibre modules which recover energy from the reject when desalinating highly saline brackish water and seawater. Such plants only start to pay their way at product rates of around 400m³ /d +. Energy costs for desalination systems with lower capacities can also be reduced considerably by operating the RO plants at conversion rates of more than 30%. To what extent the required higher conversion rates can be obtained for a particular application depends on concentration of scales-forming content matter (calcium sulphate, strontium sulphate, barium sulphate and calcium carbonate), salt content of the raw water, concentration of fouling substances such as iron, manganese, anorganic and organic matter, risk of biological growth due to algae, shells and bacteria. The scope and type of conditioning and pre-treatment are based on these factors.     

Investigation on sea water desalination plants in Spain

The main desalination research and development programs and the demand for fresh water on the Spanish coasts are outlined. The experimental plants of the Moncloa (Madrid) (MSF, vapor compression, reverse osmosis and others) and their computer programs are described as are also the pilot plants of Lanzarote (Canary Islands). The close collaboration between private enterprise and the Spanish Government is discussed.     

Production of magnesite from sea water in Britain

Refractories and Industrial Ceramics -     

浓海水鼓泡过程中的气泡行为

鼓泡操作可强化浓海水蒸发过程,其气泡的大小及运动行为对浓海水蒸发过程有显著影响。实验通过搭建两种不同尺寸的鼓泡池,针对单鼓泡口、双鼓泡口及鼓泡阵列,在不同气量、鼓泡口深度与鼓泡口间距条件下,考察大气泡群与小气泡群在不同运动过程的行为。结果表明,在气体流量更低的情况下,液面上的小气泡群比大气泡群具有更高的表面覆盖度,更易于增加液相扰动,并能迸射出更多的小液滴,提出小气泡更适合于鼓泡浓缩晒盐过程。通过单因素实验优化后,小气泡群的覆盖率可以达到90%,蒸发速率可比传统滩晒过程增加1～1.5倍。优化后操作参数为：单鼓泡口气流量为0.4 L·min^-1、鼓泡口深度为8 cm、鼓泡口间距为12 cm。     

Nucleation in the flash boiling of sea water

Some results from an experimental investigation into the mechanism of bubble nucleation in the flash boiling of water are presented. Conditions similar to those found in polyphosphate dosed MSF plants have been studied. The experiments suggest that the naturally occurring nucleation sites in sea water give an effective site radius of the order of 15–20 microns. Such sites with the help of dissolved gases would be effective only over the top quarter of the flash range in a typical plant. Diffusion of gas towards the sites is thought to be responsible for the time delays of the order of seconds between decompression and nucleation.     

Alkaline scale formation in boiling sea water brines

A laboratory method for the study of alkaline scale is described. Evaporator conditions are easily simulated in experiments of relatively short duration (5 hours). Reproducible results have been achieved by chemical analysis for total scale which consisted of mixtures of calcium carbonate and magnesium hydroxide. Experiments with natural sea water show the amount and composition of alkaline scale to be a function of temperature, brine concentration, bicarbonate ion concentration, and flow conditions through the evaporator. The transition between calcium carbonate and magnesium hydroxide was shown to be influenced by factors other than temperature. A new mechanism for alkaline scale formation is proposed in this paper. The first step involves a unimolecular breakdown of bicarbonate ion to form hydroxide ion. This concept is in disagreement with the generally accepted mechanism described in the literature.     

Electrolytic scale formation in sea water distillation systems

Preliminary investigations on the electrodeposition of scales under galvanic and external currents is presented in this paper. Effect of time, current, temperature and sea water salinity on electrodeposition is studied. It is observed that magnesium hydroxide is the major constituent of the electrodeposits.     

Thermal desalination of sea water in thin film-plants

The paper deals with several types of thin film desalination plants with vertical and horizontal heating surfaces. Data on the characteristic features of heat exchange during boiling of sea water in such plants are given. Some equations describing performance characteristics of the plants are provided.     

海水冷却塔设计

选择带冷却塔的循环冷却系统,采用海水作为循环冷却水的补充水,是我国沿海火力发电厂以及其它工业企业冷却用水的一次革命。它改变了从海洋取水使用后又将废水排回海洋的传统做法,避免了近海的热污染;极大的减少了从海洋取水的数量,节约了大量的基建投资。我国渤海湾地区拟建的超大型机组发电工程取水均在浅滩海岸,采用直流供水系统,取水头部将深入海中十几千米甚至更远,耗资将达到十几亿甚至几十亿元人民币。根据某科研设计单位十多年“海水冷却塔试验研究”的成果以及国际上成功的工程实践并结合国情,这些工程选择带冷却塔的海水闭式循环系统从方案和技术支持上是可行的,合理的。     

潮汐影响海水沉淀池运行的原因分析与对策

海水退潮过程中反应沉淀池沉淀区出现翻池,絮凝体大量上浮严重影响出水质量.通过对海水潮汐过程中海水变化的分析,找出导致此现象发生的根本原因是海水密度和浊度变化使池内水流产生异重流.作者结合沉淀池结构对异重流流态及其对沉降效果的影响进行了分析,并在此基础上提出了有效的应对方案.     

日本海洋深层水的利用近况

1　神奇的海洋深层水[1 ]日本近年来掀起了海洋深层水热。所谓海洋深层水是指深度在 2 0 0ｍ以上的深海海水 (以下简称深层海水 )。深层海水有一系列有别于一般表层海水的奇特性质 ,例如用深层水培养的海藻体型竟然比在表层海水中培养的同种海藻大 10～ 2 0倍。深层水有类似生长促进剂的作用 ,无怪乎被日本人称作为“魔水”、“梦幻之水” ,视作新的巨大天然资源而加以开发利用。经分析 ,深层海水的确有其不可等闲视之的卓越特性 ,概括起来深层海水有如下 3种主要特性 :( 1)富营养性深层海水含有约 60种不同的硝酸盐、磷酸盐、硅酸盐等矿物…     

Electrolytic deposition for scale control in sea water distillation

This paper describes laboratory experiments on the electrolytic deposition of scaling compounds from sea water. The dependence on applied current, time of deposition and the effect of sea water stirring is studied. X-ray diffraction patterns of scales are taken to confirm their composition. The pH changes of the sea water feed occurring during the experiments under varying currents are investigated. The possible application of these studies in controlling alkaline scale is suggested. The feasibility of using electro-deposition as a means for controlling alkaline as well as calcium sulfate scales in seawater distillation plants has been ascertained.     

Advantages of the ejectocompression process in sea water desalination

The authors introduce the various techniques developed by SIDEM for seawater desalination. Among those techniques the paper presents in detail the vapour compression process by ejectocompression.The ejectocompression process has allowed SIDEM to construct packaged type units with rising maximum capacities : 600 m³/d in 1979, 1,500 m³/d in 1980, 2,600 m³/d in 1981.The authors, as an example, give the main characteristics of 1,500 and 2,600 m³/d units and review their operating experience of this type of plants.A comparison is made with Multiflash units of same capacity namely in terms of investment costs, as well as compactness, reliability, etc.     

Boiling of natural sea water in falling film evaporators

Under conditions normally encountered in falling film evaporators for sea water, the boiling mechanism is one of evaporation at the continuous liquid-vapor interface with little nucleation involved. In smooth tubes, the heat transfer coefficient for the inlet-section is considerably higher than for the rest of the tube, and thereby contributes significantly to the average overall heat transfer coefficient, especially in short tubes.In the case of natural sea water, evaporation at the liquid-vapor interface causes large interfacial instabilities. Inlet devices, such as vortex level control and flow distribution, induce instabilities at the inlet of the tubes, thereby causing increased waviness further down. Although these disturbances enhance heat transfer, they increase entrainment and the tendency for scale formation in fluted tubes.Spirally corrugated tubes have significantly better heat transfer characteristics than smooth tubes.Heat transfer improvement caused by surfactant addition in smooth tubes depends strongly on the temperature difference.     

Vegetable composts for sea water uranium extraction

Composting wood or crop residues by the addition of tanneries sludge as nitrogen supplement yields products having lower polysaccharides and protein content, but higher relative concentration of lignin material than the starting mixture. When used as sea water uranium adsorbents, the compost products exhibit higher uranium uptake (3.0–100 μg g^?1) than parent ligno-cellulosic materials (0.3–9 μg g^?1), thus achieving over 10⁴-fold uranium concentration relative to sea water. An additional distinguishing feature is the strong pH effect observed on uptake by products. The results are consistent with the expected change of parent lignin to lignin-humus in the compost product.     

Desalination of sea water by direct osmosis

Sea water can be desalinated by direct osmosis across a cellulose acetate membrane by using the osmotic pressure of a hypertonic glucose solution as the energy source. The resulting glucose solution is potable. This may prove useful for an emergency water supply in lifeboats.