DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

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Dealkalization: Salt Splitting Process 3. Calculate the capacity required to handle the TEA content of the feed for the desired feed rate and cycle length. gallons minutes grains × × minute cycle gallon kilograin × 1000 ft 3 grains 3 cycle ft = = grains cycle 3 ft 4. Size the bed to this volume, keeping bed depths ≥36 inches (0.91 m). 5. Calculate the flow rate per unit volume. If this number is outside the range of 0.5–3.0 gpm/ft 3 (4.0– 24.0 (m 3 /h)/m 3 ), modify the cycle length and resin volume to bring it within this range. Note: These calculations can also be done via CADIX. 5.4 General Advantages This is the simplest of the dealkalizing processes, and it is especially good for smaller installations and other places where it is desirable to avoid the handling of acid. While it is initially a larger investment than the hydrogen cycle weak acid cation resin process, it is more easily handled by unskilled operators. The procedure lends itself to automated operation with very simple controls. 5.5 Precautions Water must be clean and free of iron to avoid fouling of the resin and equipment. Operation on hard water can give only marginal results and should be avoided when NaOH is used with NaCl for regeneration (Table 7). See handling precautions relating to NaOH (Section 12.7). 5.6 Reference Documents Table 7. Regenerant concentration and flow rate NaCl 5% at 0.5 gpm/ft 3 (4.0 (m 3 /h)/m 3 ) DOWEX MARATHON A2 Product Information (177-01594) DOWEX MARATHON A2 Engineering Information (177-01693) DOWEX Ion Exchange Resins 32 Water Conditioning Manual
Dealkalization: Weak Acid Cation Resin Process 6 DEALKALIZATION: WEAK ACID CATION RESIN PROCESS 6.1 Ion Exchange Resin Specified DOWEX MAC-3 weak acid cation (WAC) exchange resin is recommended. This resin removes cations and associated alkalinity from water by converting alkaline salts of calcium and magnesium to the corresponding weak acid (dissolved CO2) and subsequently removing the CO2 by degasification. 6.2 Typical Reactions and Chemicals Used 2 H + R – + Ca(HCO3)2 Ca 2+ R − 2 + H2CO3 2H2CO3 2H2O + 2CO2↑ where R = DOWEX MAC-3 resin Mineral acids are used to regenerate DOWEX MAC-3 resin. HCI is preferred over H2SO4, due to the precipitation problems that can occur with H2SO4 and calcium that have concentrated on the resin. If H2SO4 is used as the regenerant, flow rates during regeneration must be high enough to prevent this precipitation. 6.3 Equipment Required Equipment includes a vessel to accommodate DOWEX MAC-3 resin, with piping, valves, chemical tanks and accessories properly engineered for economical balance of resin capacity and hydraulic properties. This unit is usually followed by a degasifier unless the subsequent use of the product water does not require CO2 removal (e.g., a cooling tower). This operation is often used in conjunction with a strong acid cation exchange resin as a chemically efficient hydrogen cycle process. Data presented here and in Section 7 can be used together to design such a system. Figure 16 shows the general flow diagrams for these systems. DOWEX MAC-3 resin followed by degasifier. Degasifier can often be eliminated in cooling tower applications. DOWEX MAC-3 Resin Figure 16. Dealkalization by the weak acid cation resin process. Degasifier DOWEX MAC-3 resin followed by degasifier, causing dosing, and polishing softener for low-pressure boiler feed make-up. DOWEX MAC-3 Resin Degasifier NaOH DOWEX SAC Softening Resin DOWEX Ion Exchange Resins 33 Water Conditioning Manual
Page 1 and 2: Dow Liquid Separations DOWEX Ion Ex
Page 3 and 4: TABLE OF CONTENTS 1 Introduction to
Page 5 and 6: TABLE OF TABLES Table 1. Terms comm
Page 7 and 8: Introduction to Ion Exchange 1 INTR
Page 9 and 10: Terms, Acronyms, And Abbreviations
Page 19 and 20: Sodium Cycle Ion Exchange Process (
Page 27 and 28: Brackish Water Softening Using H2SO
Page 29 and 30: Brackish Water Softening Resin oper
Page 31: Dealkalization: Salt Splitting Proc
Page 35 and 36: Dealkalization: Weak Acid Cation Re
Page 37 and 38: Demineralization (Deionization) Pro
Page 39 and 40: Demineralization (Deionization) Pro
Page 41 and 42: The UPCORE Counter-Current Regenera
Page 47 and 48: Ion Exchange Resin Operational Info
Page 57 and 58: Ion Exchange Cleaning Procedures 10
Page 59 and 60: Ion Exchange Cleaning Procedures Re
Page 61 and 62: Ion Exchange Cleaning Procedures 10
Page 63 and 64: Ion Exchange Cleaning Procedures Ta
Page 65 and 66: Designing an Ion Exchange system fr
Page 67 and 68: Designing an Ion Exchange system As
Page 69 and 70: Designing an Ion Exchange system 11
Page 71 and 72: Useful Graphs, Tables, and Other In
Page 83 and 84:
Useful Graphs, Tables, and Other In
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Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Index 14 INDEX A Abbreviations · 9
Page 93:
Dow Liquid Separations Offices. For
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