Brine Systems

Most commonly, diaphragm cells are supplied with well brine on a once-through basis. The treated well brine flows to the treated brine storage tanks, which usually have 12-h capacity. From there the brine is fed to the cell room. The flow to each individual electrolyzer is controlled by a rotameter. If the flow of brine to the cells is suddenly disrupted by failure of the brine feed pump, the rectifiers automatically shut down since an inadequate supply of brine to the cells is potentially unsafe. The specifications for brine for diaphragm cells are given in Table 13. 

A brine recovery lagoon is usually available to handle any major upsets in the brine system. Brine sludges or out-of-spec brine can be sent to the lagoon. Supernatant clear brine can be recovered from the lagoon. 

In most cases, operation with acidic brine is preferred because of the reduced amount of side-reaction products in the chlorine and the cell liquor. 

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The second most common alkalinity control agent is lime [1305-78-8] normally in the form of calcium hydroxide [1303-62-0], used in both water and oH muds. In the latter, the lime reacts with added emulsifiers and fatty acids to stabHi2e water-in-oH emulsions. Lime is used in brine systems containing substantial quantities of soluble calcium and in high pH lime muds. Concentrations are ca 6—57 kg/m (2—20 lb /bbl) (see Lime AND LIMESTONE). 

Where a brine system services a multiple-temperature installation such as a range of food stores, the coolant maybe too cold for some conditions, causing excessive dehydration of the product. In such cases, to cool these rooms the brine must be blended. A separate three-way blending valve and pump will be required for each room (see Figure 12.6). 

In the presence of Sun Tech IV surfactant, the interfacial tension of an Athabasca/brine system showed little or no dependence on pH. However, at a given pH, tension values increased with temperature (50-150°C). 

The computer interface system lends itself well to the determination of interfacial tension and contact angles using Equation 3 and the technique described by Pike and Thakkar for Wilhelmy plate type experiments (20). Contact angles for crude oil/brine systems using the dynamic Wilhelmy plate technique have been determined by this technique and all three of the wetting cycles described above have been observed in various crude oil/brine systems (21) (Teeters, D. Wilson, J. F. Andersen, M. A. Thomas, D. C. J. Colloid Interface Sci., 1988, 126, in press). The dynamic Wilhelmy plate device also addresses other aspects of wetting behavior pertinent to petroleum reservoirs. 

Kvaerner Chemetics have developed a novel, patented process [1] for the removal of multivalent anions from concentrated brine solutions. The prime market for this process is the removal of sodium sulphate from chlor-alkali and sodium chlorate brine systems. The sulphate ion in a brine solution can have a detrimental effect on ion-exchange membranes used in the production of chlorine and sodium hydroxide consequently tight limits are imposed on the concentration of sulphate ions in brine. As brine is continuously recycled from the electrolysers back to the saturation area, progressively more and more sulphate ions are dissolved and build up quickly in concentration to exceed the allowable process limits. A number of processes have been designed to remove sulphate ions from brine. Most of these methods are either high in capital or operating cost [2] or have large effluent flows. 

In the brine system, sulphate ions are mixed with raw salt. These ions deposit on membranes in the electrolysis process and cause loss of current efficiency [3, 4]. 

Figure 12.1 shows a scheme of the brine system for the membrane electrolysis process. The RNDS is installed at the point of depleted brine flow. Figure 12.2 illustrates the principle of the RNDS operation. The required area for the RNDS set-up in a chlor-alkali plant having a capacity of 135 000 tonnes of NaOH per annum is 54 m2. 

This chapter concentrates on the mercury technology with waste brine system, as used at Runcorn and in particular a mathematical model of a mercury cell which is being used to improve the operability and efficiency of chlorine production. In general, however, the use of the techniques described here is applicable to all cell technologies. 

Typical areas where titanium has found widespread industrial use in membrane technology are cells, anodes, anolyte headers, anolyte containers, filters, heat exchangers, chlorate removal systems and various parts of the brine system. 

Other uses of titanium are in the construction of anolyte pipes, anolyte tanks, and dissolver and maturing tanks in the brine system. Here pure titanium cannot always be justified and instead rubber linings or polymeric materials are also used. Where the demand on uptime is rigorous, titanium-lined steel may be considered instead of rubber. 

Fig. 16.21 Reversed phase HPBC-ED chromatogram of alkylphenols from SPE extract of Miller oil. See Table 16.7 for identification of peaks. Reprinted from Bennett B, Barter SR (1997) Partition behaviour of alkylphenols in crude oil brine systems under subsurface conditions. Geochim Cosmochim Acta 61 4393-4402. Copyright 1997 with permission of Elsevier...

And rez JM, Bracho CL, Sereno S, Salager JL (1993) Effect of surfactant concentration on the properties of anionic-nonionic mixed surfactant-oU-brine systems. Colloid Surface A 76 249-256... 

A correlation of the detergency performance and the equilibrium phase behavior of such ternary systems is expected, based on the results presented by Miller et al. (3,6). The phase behavior of surfactant - oil - water (brine) systems, particularly with regard to the formation of so-called "middle" or "microemulsion" phases, has been shown by Kahlweit et al. (7,8) to be understandable in teims of the... 

After listening intently, the operating foreman explained that mere traces of chrome salts in the brine system could create an explosive situation within the electrolytic chlorine cells. Traces of chrome salts in the feed brine to the chlorine cells liberate hydrogen gas in the chlorine cell gas. Hydrogen in the chlorine cell gas has a very wide explosive range. Installation of stainless steel equipment in sodium chloride brine systems has devastated chlorine processing equipment within other similar chlorine manufacturing plants. The maintenance foreman had the improper pump impeller removed immediately before any problems occurred. 

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