Brine concentration

Electrodialysis. Electro dialytic membrane process technology is used extensively in Japan to produce granulated—evaporated salt. Filtered seawater is concentrated by membrane electro dialysis and evaporated in multiple-effect evaporators. Seawater can be concentrated to a product brine concentration of 200 g/L at a power consumption of 150 kWh/1 of NaCl (8). Improvements in membrane technology have reduced the power consumption and energy costs so that a high value-added product such as table salt can be produced economically by electro dialysis. However, industrial-grade salt produced in this manner caimot compete economically with the large quantities of low cost solar salt imported into Japan from Austraha and Mexico. 

Sole, /. brine, salt water salt spring, -be-reiter, m. brine mixer, -eindampfer, m. brine concentrator, -erzeuger, m. brine mixer. 

Active hydrologic conditions exist because large volumes of water would have to pass brine through a basin to reach observed brine concentrations. 

Brine concentration versus voltage and current efficiency... 

The particular amphoteric resin that is employed in the BDH process has a high affinity for calcium and magnesium chloride in concentrated sodium chloride brines. In dilute solutions the selectivity is lost, so that regeneration can be effected with a simple water wash. The process was found to be effective over a wide range of hardness and brine concentrations. 

In trials at different feedwater concentrations, the FT-30 membrane showed single-pass seawater desalting capabilities at up to 6.0 percent synthetic seawater. Basically, any combination of pressure and brine concentration at room temperature that gave a membrane flux of 15 gfd also resulted in a 99 percent level of salt rejection. 

Membranes as a Function of Temperature, Pressure, and Brine Concentration. 

In summary, the FT-30 membrane is a significant improvement in the art of thin-film-composite membranes, offering major improvements in flux, pH resistance, and chlorine resistance. Salt rejections consistent with single-pass production of potable water from seawater can be obtained and held under a wide variety of operating conditions (ph, temperature, pressure, and brine concentration). This membrane comes close to being the ideal membrane for seawater desalination in terms of productivity, chemical stability, and nonbiodegradability. 

Bromine (Br) is the most important genetic trace element for potash within salt deposits. Bromide minerals do not form during the crystallization of salts from seawater rather bromine tends to accumulate with increasing brine concentration and occurs only as a trace in solid solution as a substitute for chlorine in the precipitating chloride minerals. 

Figure 21 Refinery wastewater recycle/zero liquid discharge scheme. Pretreatment and reverse osmosis are used to recycle water, and brine concentrator and crystallizer are used to treat the rejects to achieve zero liquid discharge. (From Ref. 78.)...

In most commercial processes, the compound is either derived from the sea water or from the natural brines, both of which are rich sources of magnesium chloride. In the sea water process, the water is treated with lime or calcined dolomite (dolime), CaO MgO or caustic soda to precipitate magnesium hydroxide. The latter is then neutralized with hydrochloric acid. Excess calcium is separated by treatment with sulfuric acid to yield insoluble calcium sulfate. When produced from underground brine, brine is first filtered to remove insoluble materials. The filtrate is then partially evaporated by solar radiation to enhance the concentration of MgCb. Sodium chloride and other salts in the brine concentrate are removed by fractional crystallization. 

A 50-ml autoclave was charged with the step 1 product (50.0 g) and 18 M sulfuric acid (0.41 g) and then sealed and treated with hexafluoroacetone (73.0 g) and heated to 60°C for 41 hours. The mixture was added to aqueous and extracted with 200 ml diisopropyl ether. The organic layer was washed with brine, concentrated, and 92.4 g of a colorless liquid isolated as a mixture of two isomers. The isomer 1 (preferred) to isomer 2 ratio was 70 30, respectively. 

Figure 16-16 gives the viscosity of water at atmospheric pressure as a function of temperature and brine concentration.9 Figure 16-17 gives an adjustment for pressure. 

Figure 16-22 has several uses. If the concentration of dissolved solids is known, the resistivity of the water at any temperature can be determined. If the resistivity of a brine at surface temperature is measured, it can be converted to reservoir temperature. Finally, if the resistivity is measured, the brine concentration can be estimated. 

Cooling Water Salinity and Brine Disposal Optimized with Electrodialysis Water Recovery/Brine Concentration System... 

Fresh sea water feed is first deaerated and then precooled by heat exchange against the two product streams, brine and fresh water product. It enters the freezer at about 37° F., is cooled further to 25° F. by evaporation, and is partially frozen. Because the freezer is maintained at 3.3 mm. of mercury pressure (25° F.), the brine concentration is 7%, and half of the water in the sea water is removed. The slurry is diluted by recycle brine that has been filtered in the separation column. 

Results are shown graphically in Figure 4 for a brine temperature of 220°F., condenser tube velocity of 5 feet per second, blowdown temperature of 90°F., and brine concentration of twice sea water. As can be seen, a minimum water cost for these conditions is obtained with a 50-stage plant operating with a terminal temperature difference of about 4°F. Similar calculations were made for a blowdown concentration of 1.5 times sea water and for a once-through system. By cross plotting, it was then possible to determine the optimum blowdown salt concentration for the plant. It was about 1.7 times sea water. However, the curve is almost flat in the range of 1.5 to 2.0 times sea water. 

A solution of 72.08 g (0.19 mol) of 5-bromo-l-pentanyl acetate in 1.4 L of MeOH was treated with 38 mL of a 1.0 molar solution of tetrabutylammonium hydroxide and the mixture was stirred at room temperature for 3.0 h, 3.0 mL of AcOH was added and the solution was evaporated at 35°C. The residue was dissolved in 400 mL of EtOAc and the solution was washed with saturated NaHC03, brine, dried, and evaporated to give 60.45 g (94% yield) of the intermediate hydroxy ester (an analytical sample may be obtained by crystallization from 70% EtOAc in hexane, m.p. 58-61°C. A stirred solution of 60.25 g of the hydroxyester in 700 mL of EtOAc was cooled to 5°C and treated with 75.5 mL (3 equiv.) of triethylamine and 32.6 mL (2.35 equiv.) of methanesulfonyl chloride. The mixture was stirred at 6°C for 2.0 h, transferred to a separatory funnel and washed sequentially with water, 2 N HCI, and brine. Concentration of the EtOAc to ca. 300 mL and dilution cooled to 0°C and treated with 75.5 mL (3 equiv.) of triethylamine and 32.6 mL (2.35 equiv.) of methanesulfonyl chloride. The mixture was stirred at 6°C for 2.0 h transferred to a separatory funnel and washed sequentially with water, 2 N HCI, and brine. Concentration of the EtOAc to ca. 300 mL and dilution with 250 mL of hexane led to crystallization (0°C, 18 h). The product was collected by filtration and washed with some cold hexane - EtOAc (1 1) to give 66 g (84% yield) of methyl (R,S)-6-acetyl-3,4-dihydro-7-[5-[(methylsufonyl)oxy]pentyloxy]-2H-l-benzopyran-2-carboxylate m.p. 73-76°C. 

Methyl magnesium chloride (3.0 Molar solution in THF, 790 mmol) was added dropwise over 30 min to the CeCI3 slurry at 0°C. After stirring 2 hours, the mixture was cooled to -5°C and a toluene (600 mL) solution of the ethyl 2-(3(S)-(3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-hydroxy-propyl)benzoate (152 mmol) was added dropwise over 1 hour. The reaction mixture was stirred another hour before the addition of 2 M HOAc (600 mL) and toluene (600 mL). The organic layer was washed with saturated aq. NaHC03 and with brine. Concentration in vacuo and purification of the residue by flash chromatography (30% EtOAc in toluene) gave 63.48 g (91%) of the 2-(2-(3(S)-(3-(2-(7-chloro-2-quinolinyl)ethenyl)phenyl)-3-hydroxypropyl)phenyl)-2-propanol. 

It follows from the above explanation that electrolysis of alkali chlorides in an electrolyzer without a diaphragm must be interrupted before curve h which represents the concentration of hypochlorite oxygen changes into a horizontal line only under this condition is the process economical, as a prolonged electrolysis would result in a waste of current without any further increase in th<) hypochlorite content. Moreover, care should be taken to prevent the hypochlorite ions formed from being electrochemically oxidized, as this would result in lower current efficiency and lower hypochlorite concentration in the liquor produced. This process is influenced by a number of factors, e. g. brine concentration, hydrogen ion concentration, anode material, current density, temperature, and last but not least a suitable design of the electrolyzer. 

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