Brine distributor

The brine distributor provides a uniform supply of anolyte throughout the bottom region of the anolyte compartment. In conjunction with the baffle in the upper half of the compartment, this results in a highly uniform concentration throughout the anolyte compartment, as shown in Fig. 17.14, by the measured values obtained during operation of the electrolyser at a current density of 6 kA m-2. 

Eig. 19. CME monopolar electrolyzer a, membrane b, cathode element c, half-cathode element d, current distributor e. Teflon tube f, CI2 + depleted brine manifold g, conductor rod h, CI2 + depleted brine outlet nozzle i, base frame j, recycled NaOH manifold k, recycled NaOH inlet nozzle 1, gasket (the gasket-to-element ratio is quite small) m, tie rod n, anode element o, H2 + NaOH manifold p, end plate, q, under cell bus bar (simplifies piping... 

Fig. 25. OxyTech MGC electroly2er a, membrane b, anode assembly c, manifold spacer d, anolyte outlet e, catholyte outlet f, bulkhead g, brine inlet h, NaOH inlet i, insulating channel j, bulkhead insulator k, interface material 1, cathode assembly m, interceU bus n, tie rod o, current distributor p,...

Fig. 13. A hoUow-fibet reverse osmosis membrane element. Courtesy of DuPont Permasep. In this twin design, the feedwater is fed under pressure into a central distributor tube where half the water is forced out tadiaUy through the first, ie, left-hand, fiber bundle and thus desalted. The remaining portion of the feedwater flows through the interconnector to an annular feed tube of the second, ie, right-hand, fiber bundle. As in the first bundle, the pressurized feedwater is forced out tadiaUy and desalted. The product water flows through the hoUow fibers, coUects at each end of the element, and exits there. The concentrated brine from both bundles flows through the concentric tube in the center of the second bundle and exits the element on the right.

Brine Injection - After backwashing, a 5 percent to 10 percent brine solution is injected during a 30-minute period. The maximum exchange capacity of the resin is restored with 10 percent strength of brine solution. The brine is injected through a separate distributor placed slightly above the resin bed. 

The anode gaskets and rings are of soft and ebonite rubber, respectively. The inlet box is of rubber lined mild steel construction having a feed brine (sodium chloride) distributor and mercury seal. 

Mixed-flow dissolvers are an attempt to combine the advantages of upflow and downflow. Upflow-downflow dissolvers were conceived in order to add a filtration zone for the brine produced in an upflow mode. Problems arise when suspended solids accumulate on the filter salt and impede the flow of brine. This mode is not often found in the chlor-alkali industry. Downflow-upflow dissolvers, on the other hand, are rather commonly used. A familiar example in the industry is the highly successful Lixator . The term, devised from lixiviate, is a trademark of Cargill Salt Company. The Oxford Universal Dictionary defines lixiviation as the action or process of separating a soluble from an insoluble substance by the percolation of water. The basic apparatus (Fig. 7.19) consists of a cylindrical body above a conical section with a false bottom. Water or depleted brine is fed through a spray or distributor into the bed and flows to the bottom of the vessel. At the bottom is an opening in the false bottom that allows the brine to flow into the annulus between the two shells and then up to an overflow point. 

The clarified brine overflows the chambers through restricting orifices, which collectively act as a flow distributor. The brine then overflows a stilling section into flumes that carry it to a discharge zone. Discharge is by gravity into a collecting tank from which the brine is sent on to the rest of the process. 

Good filtration also requires proper distribution of the brine flow over the cross-section of the bed. Rather than the pipe distributor found in many other fixed-bed applications, many designs use nozzles fixed to the support plate [109]. These allow brine to pass from the bottom head up into the filtration zone. They end in a capped section with slots to permit radial flow. A screen covers the slots. These nozzles must be leveled very carefully in an upflow filter in order to achieve uniform distribution of fluid. It is particularly critical to level the nozzles to obtain even distribution of the scouring air (see below). 

A. Column Internals. The analogy of brine softening to water softening does not extend to mechanical design. The systems used to soften water are not suitable for our application, where exposure conditions are quite different. More robust construction is necessary. While chemical compatibility with brine is essential, it is not the only consideration. Mechanical and thermal stability is also important. Distortion of a distributor or collecting screen, for example, can allow loss of resin or channeling of fluid. 

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