Two Bed Systems
Improves conductance levels
A two-bed system works well for most applications even though demineralizers can vary greatly depending on the particular application. For a very high proportion of raw-water contamination levels, the first bed involves the removal of calcium, magnesium, and sodium using a cation exchanger with cocurrent acid regeneration. The second bed uses an anion exchanger with cocurrent caustic regeneration to remove alkalies, chlorides, sulfates, silica, and carbon dioxide. Engineering systems using this basic design typically achieve conductance levels of 5 to 10 μS/cm.
Countercurrent Regeneration Systems
For demineralization applications
If higher-quality water is essential, it is usually appropriate to use a countercurrent regeneration system to achieve conductance levels of less that 2 μS/cm. Hungerford & Terry is an industry leader in the design of countercurrent systems and is among the few companies supplying them in demineralization applications.
High-rate, deep-bed polishers remove residue material
Boilers are protected by Hungerford & Terry’s condensate polishers. Our high-rate, deep-bed polishers remove suspended and dissolved material from returned condensate water through the use of mixed-bed demineralizers. These high-pressure demineralizers operate at a flow rate of 25 to 50 GPM per square foot of bed surface area. The boiler is further protected by the external regeneration of the bed, which prevents the intrusion of harmful acid and alkali into the return condensate. These polishers can operate beyond the ammonia break in high-pressure utility applications.
Address those special demineralization problems
Additional and special demineralization problems can be addressed by the application of other supporting technologies.
- Very high alkalinity levels can be handled through the addition of a forced-draft aerator or decarbonator. Such approaches provide the economical reduction of CO2 load on the anion unit.
- When a reduction in dissolved gases is also required, a vacuum degasifier can be added.
- Still further demineralization is available with the addition of mixed-bed demineralizers in series with a basic two-bed installation. Such systems yield conductance levels of less than 1 μS/cm.
- Some large installations may require the use of multiple-train systems to achieve the desired capacity. Counter-current regeneration in both cation and anion exchangers is frequently combined with high-capacity weak-acid cation or weak-base anion units to improve chemical efficiency and reduce waste acid and caustic. Such systems have the additional benefit of permitting the reclaiming of regenerant waste from one unit for use in other units.
- Hungerford & Terry, Inc. is also a licensee of the Dowex Upcore packed-bed ion exchange system. This technology offers all of the advantages of a countercurrent regeneration system plus offers greater capacity and reduced waste volumes by making the most efficient use of the vessel size. This system also lends itself to retrofitting existing systems so that old, inefficient demineralizers can benefit from this technology at a fraction of the cost of a new system of equal performance.