PURGE® DEIONIZATION SYSTEMS
HIGH EFFICIENCY DI
economical PLC automated systems for deionized water with Power
Purge. Remco Engineering designs automated deionization systems
to provide the most economical operating cost and lowest maintenance
costs of any system available. Remco Engineering's Power Purge
deionizing systems minimizes regenerant use and rinse water requirements
by using regenerant and rinse water efficiently. Our systems can
save up to 50% of the rinse water used during the ion exchange
regeneration cycle when compared to other systems.
Click her for more than you ever wanted to know
is Deionization? The deionization process removes all ions from
a solution. Cation exchangers remove all cations (positively
charged ions such as Sodium, Calcium, and Magnesium) and anion
exchanger remove all anions (negatively charged ions such as
sulfate, bicarbonate, and chloride). The cation exchanger is
operated in front of the anion exchanger and converts the salts
CaSO4 + 2R-H CaR2 + H2SO4
NaCl + R-H R-Na + HCl
The anion exchanger removes the acid from solution:
H2SO4 + 2R-OH R2SO4 + H2O
HCl + R-OH RCl +H2O
The result is water without ions. Some Sodium will leak from
the Cation exchanger and this is what determines the purity
of the water leaving the system. One ppm Sodium is equal to
5 micromhos conductance (or 0.2 megohms resistance).
systems can be either continuous or batch mode operations. In
a continuous system, there are duplicate sets of columns When
one set has expired, the system switches to the other set and
regenerates the first. In a batch system, there is only one
column pair and the system is off-line for several hours when
regenerating. Batch mode systems are less expensive but require
larger tanks for storage if you plan to continue supplying deionized
water while regenerating. A batch system is sized larger to
make up for the time lost during regeneration.
Counter current regeneration -
current regeneration maximizes regenerant contact efficiency
and results in high water quality. Older style, less sophisticated
systems use co-current regeneration where the regenerant flow
is in the same direction as the normal water flow. This results
in overall low water quality because the bottom part of the
bed is only partially regenerated. Countercurrent systems pass
the regenerant in the direction opposite the normal water flow,
fully regenerating the bottom of the beds which minimizes leakage
resulting in very high water quality.
Power Purge regeneration
is a 3 step process for Deionizing systems:
- Rinse, to remove
sediment, undersize resin particles, and reclassify the bed;
- Regenerate with
acid or caustic (depending on resin type);
- Rinse again
to remove excess regenerant.
run all three cycles sequentially, using the second to push out
the first and the third to push out the second. If you think about
it, you will see that you will get dilution of the regenerant
and no clear break between the regenerant and the rinse water.
Our Power Purge ion exchange regeneration system isolates
the regenerant by removing all (over 98%) of the water from the
column before adding the regenerant to the system. After regeneration,
we purge the remaining regenerant from the system before adding
any rinse water. This reduces the overall rinse water requirements
dramatically. Final rinsing is a rinse-leach-purge step rinse
operation that efficiently uses a minimal amount of water. Each
time the column fills with rinse water, the system waits until
the water and resin reach an equilibrium condition (concentration
inside the bead = concentration in the water) then we purge the
water and refill. This allows us extensive control over the process
and, in some cases, even allows us to mix anion and cation bed
rinse water to achieve mutual neutralization.
sells fully automated systems using microprocessor based programmable
logic controllers to control the regeneration process. We find
that manual deionization systems are very uneconomical to operate
when viewed from both your costs to operate and the costs to support
continuous personnel training and retraining. We put our expertise
in a box inside the control panel so you don't have to call us
every time you regenerate to figure out which valves to open and
close. Because we sell automated systems that are computer ready,
we can integrate pump and level controls, alarms, conductivity
and other process sensors, and remote interfaces. We offer the
most sophisticated deionization systems available.
Sizing a system based on water use.Two requirements determine
the size of a system:
- Maximum demand
- Average demand
(gpm average per day).
first governs the amount of storage you will need, the second
sizes the flow rate.
If you need 200 gallons to fill a tank 3 times per day and 2 gpm
continuously for rinsing, then over an 8 hour day, you would need
a total of 1560 gallons (8 x 120 gal/hr + 600) or about 3.25 gallons
per minute. A 5 gpm system would be large enough with a 300 gallon
storage tank for tank fills. If the tank fills were all at once,
you would need enough storage to cover all of them.
2. Ten(10) gpm required continuously with tank fills of 85 gallons
each every hour. The total requirement would be about 11.5 gpm.
We would recommend a 12-15 gpm system with about 200 gallons of
storage as a minimum.
Column Sizing a 5 gpm system. (calculations)The actual physical
size of system you will need will vary depending on the quality
of the water you wish to deionize. Deionization systems use a
resin that has a certain capacity given as kilograins of calcium
carbonate per cubic foot. A grain is 17.1 ppm. The actual operating
capacity is less than 100% and is based on the amount of regenerant
(acid or caustic) added during regeneration. Doing a complete
regeneration wastes a lot of regenerant so systems are regenerated
to an economical range of 60-70 percent of theoretical capacity.
There are a lot of calculations to determine actual capacity of
a specific resin with a specific water chemistry so we have a
quick formula to do a rough 80% estimate of capacity.
- Take your water
TDS (total dissolved solids) analysis.
- Look at Calcium,
Magnesium and Sodium concentrations in ppm.
- Add up the total
ppm and divide by 17.1 (i.e., 250 ppm/17.1 = 14.6 grains/gal).
- Assuming a conservative
16 kilograin/cu. ft. capacity with an economical regeneration,
now divide 16,000 by 14.6 (16000/14.6 = 1095).
- You will get
over a thousand gallons of decationized water per cubic foot
- Next add up
the anions, they should be equal to the cations plus silica
(SiO2) and dissolved CO2 .
- Add up the anions
plus silica and carbon dioxide in ppm. Lets say total carbonate
and silica is 20 ppm.
- Take the total
anion ppm and divide by 17.1 (270 (250+20)ppm /17.1 = 15.8 gr/gal..).
- Divide 14 kilograin/cu.ft
by your answer (14,000/15.8 =886 gallons per cubic foot).
- A 5 gpm system
would require about 2.5 cu.ft. of cation resin and about 3 cubic
feet of anion resin, resulting in about 2500 gallons of DI water
you need more than 2500 gallons between regenerations such as
5 gpm for 16 hours then regenerate at night, you would have to
double the resin capacity of the system to 5000 gallons.
Factors effecting the capacity of the system are the relative
amount of Sodium, Chloride, and weak acids in the water. These
can change the capacity by 20 to 30% as can the regenerant loading
Fax us your water analysis and flow requirements and we will fax
you your systems parameters.
Engineering System Features:
Engineering System Benefits:
corrode, low maintenance
"purge" of resin columns
regenerant and water usage
based PLC control
automation, computer ready
operator knowledge required