Ion exchange unit

Pretreatment of aqueous streams may be required prior to using ion exchange. Suspended soHds that can plug an ion-exchange unit should be reduced to the 10 p.m level. Organics that can foul resins can be removed by carbon adsorption. Iron [7439-89-6] and manganese [7439-96-5], commonly present in ground waters, should be removed because they precipitate on the resin. 

Soluble iron or aluminum carryover ia the clarifier effiueat may result from inorganic coagulant use therefore, elimination of the inorganic coagulant can minimise the deposition of these metals ia filters, ion-exchange units, and cooling systems. 

Influent The solution which enters an ion-exchange unit. 

Upflow The operation of an ion-exchange unit in which solutions are passed in at the bottom and out at the top of the container. 

Purity of water. The purity of distilled or de-ionised water is commonly checked by conductimetric measurements. The conductivity of pure water is about 5 x 10-8Q-1 cm-1, and the smallest trace of ionic impurity leads to a large increase in conductivity. Conductimetric monitoring is employed in laboratories to check the operation of ion exchange units producing de-ionised water, and finds similar industrial application where processes requiring the use of very pure water (e.g. manufacture of semiconductors) are carried on. 

Demineralised water, from which all the minerals have been removed by ion-exchange, is used where pure water is needed for process use, and as boiler feed-water. Mixed and multiple-bed ion-exchange units are used one resin converting the cations to hydrogen and the other removing the acid radicals. Water with less than 1 part per million of dissolved solids can be produced. 

The required size of an ion-exchange unit is dependent upon the composition and volume of plating dragout. Each ion-exchange resin has a maximum capacity for recovery of specific ions. The ion-exchange unit s size (volume of resin) is determined by the amount of metal to be removed from the recovered solutions. 

The deionization system will be designed to handle the proposed expansion. It should be large enough that the ion exchange unit can replenish storage tanks while the plant is running at full capacity. 

The ion exchange system will be capable of processing 200,000 lb/hr. A two-bed ion exchange unit will be specified. The minimum resin volume is 200 ft3. This was calculated on the basis of 2 GPM/ft3 resin.62 During the summer the extra wash water will be sent directly to the river. It does not appear to be warm enough to justify a cooling tower and should contain no pollutants. 

H Pressure drop includes 10psi for flowthrough ion exchange unit. 

Downing, D.G. Calculating Minimum Cost Ion-Exchange Units, Chemical Engineering, Dec. 6, 1965, p. 170. 

Continuous ion-exchange units are also available in which ion exchange and resin regeneration both occur constantly. In this case both the resin bed and the fluid being purified are in motion. Continuous units are usually more economical than batch units when the rate of ion removal exceeds 1 lb/min (0.5 kg/min).39... 

TABLE 16-8 Self Diffusion Coefficients in Polystyrene-Divinylbenzene Ion Exchangers (Units of 10 7 cm Vs) ... 

The refining effect of ion exchange treatment is of sufficient magnitude to permit the elimination of a substantial portion of activated carbon, or bone char requirement. At least a portion of the cost of operation of the ion exchange unit is thus paid for by the savings in requirement of color adsorbent. 

The conventional ion-exchange method also has some major disadvantages, such as the high capital investment (both an ion-exchange unit and an electrolytic unit are needed), and the increased complexity of operation (only a few high-volume laboratories have used this method successfully). However, it remains an option for those laboratories that must meet strict limits on... 

With the in situ ion-exchange method (Fig. 5), dilute sulfuric acid is used to precipitate the silver in the resin beads as silver sulfide instead of removing it with regenerant. The resin that is inside the ion exchange unit is used for many cycles without a loss in capacity. When the resin eventually loses its capacity to recover silver, or when there is sufficient silver to make recovery worthwhile, it is sent to a silver refiner who incinerates it to remove the silver. This may occur after between six months and a year. 

Figure 6 illustrates a combined system involving the use of both the electrolytic cell and the in situ ion-exchange unit. The combined system (Fig. 6) produces an excellent effluent with lower residual silver in comparison with the chemical recovery cartridge method (Fig. 2), electrolytic silver recovery method (Fig. 3), the conventional ion-exchange method (Fig. 4), and... 

The absorbent in the CANSOLV SO2 Scrubbing System accumulates nonregenera-ble salts [also called Heat Stable Salts (HSS)] and dust that are removed from the gas over time. These contaminants must be removed from the absorbent continuously to avoid excessive build-up. An APU incorporates both an ion exchange unit (IX) for the removal of HSS and a filtration unit for the removal of dust. 

Installing an Ion-Exchange unit in-process to recycle rinsewater. 

After totaling the scores you can see that implementing a first-in first-out material policy should be evaluated before an ion-exchange unit. The next step is to evaluate its economic feasibility and associated payback period. This can be done in the following section. 

The data herein presented were gathered with that purpose in mind, and answer the objective, at least in part. The influent and effluent stream volumes, specific gravities, and concentrations enable the preparation of materials balances around the ion exchange units. However, such material balances are no better than the data on which they are based. Therefore, it is advisable to consider the assets and liabilities of the data. 

This decision then led to another The saturated ammonium bicarbonate solution obtained from the various stills is a regenerating solution for the ion exchange units— the so-called fresh water regenerant of the laboratory work. 

Ion- Exchange Unit This unit would probably service all three plants (ammonia, nitric acid and ammonium nitrate) in the chemicals complex, and would consist of a series of packed beds containing various organic polymer resins for the removal of unwanted divalent and monovalent ions. 

The ion-exchange unit for treatment of scheme water to deionized water is outside the process flowsheet shown in Figure 4.1. The flowrate through this unit is 2338 kg, equal to the make-up water requirement. Also required is a fin/fan-type cooler for the circuit itself, so that the temperature of the return deionized-water stream can be lowered from 40°C to 20°C... 

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