Chlorine Generator Process
The chlorine generator is as simple as a
battery. There are no moving parts; however, the chlorine
generator does require operation and maintenance. This page is
intended to help you understand the simplicity of the chlorine
generator leaving you thinking... why hasn't
anyone thought of this before!
On this page you will
discover:
A detailed discussion of the scientific
analysis involved with this chlorine generator process is
provided in the .
Process
Components
The chlorine generator requires a
cell, DC power supply (battery charger, battery, solar power), power
controller, energy source (power outlet, generator), and a
pressurized water supply to operate the venturi
ejector.
Cell: The
cell includes the anode and cathode compartments that are
hydraulically isolated by an ion selective membrane located between
the two cell compartments. The anode compartment contains
the anode (electrode), salt, saltwater electrolyte, and
chlorine. Chlorine gas generated from the anode compartment is
swept under vacuum by the venturi ejector into the water
supply. The cathode compartment contains the cathode
(electrode), sodium hydroxide (caustic soda) electrolyte, and
hydrogen. The hydrogen produced from the cathode compartment
is vented to the outside atmosphere. The two cell compartments
are joined together by a union pipe fitting that also holds the ion
selective membrane between the union flanges. Please note that
the use of a union pipe fitting in the cell configuration is patented
and subject to royalty fees. Furthermore, this chlorinator
system in its entirety is currently under application for patent
issuance.
DC Power Supply:
The DC power supply can be any DC battery charger of adequate size
to handle the needed chlorine demand. See our power supply
sizing page for determining the size of power supply needed.
Power Controller:
The power controller is simply a common dimmer switch (used to dim
lights) that the power supply is plugged into to adjust the voltage
input to the power supply. Like dimming your lights, the power
controller will "dim" your chlorine production to the desired
chlorine level.
Energy Source: The
energy source is basically your 120 VAC power outlet you plug the
Power Controller into.
Pressurized Water
Supply: The water passes through a venturi
creating a vacuum that is applied to the anode compartment of the
cell. The venturi ejector also includes a flow switch
connected to a relay that operates the Power Controller. This
safety feature ensures that flow is going through the venturi
ejector before chlorine is generated. The discharge from the
vacuum ejectors is highly chlorinated water in the form of
hypochlorous acid and/or hypochlorite ion.
Process Installation
Provided the plumbing for the system is
complete (existing vacuum ejector, or simply using a garden hose
connected to the ejector) It should not take longer than 30 minutes
to an hour to have your chlorine generator completely
operational. The installation includes the
following steps:
- remove components from the box, check
contents for any missing or broken parts
- soak the membrane in warm water
- install the membrane on the cell
flange
- add salt and water to the anode
compartment
- add water and dry sodium hydroxide
(i.e. Draino) to the cathode compartment
- connect water supply to venturi
ejector
- connect the vacuum tubing from the
anode compartment to the venturi ejector
- clamp red (positive) power clamp from
power supply to anode
- clamp black (negative) power clamp
from power supply to cathode
- turn on power supply switch
- plug power supply into power
controller
- plug power controller into power
circuit
- operate venturi ejector and energize
power circuit, adjust power controller to desired chlorine
level.
System
Operation
The system operation includes the control
of the system, addition of salt and water to the anode compartment,
periodic dilution of the sodium hydroxide in the cathode
compartment, and occasional cleaning of the cell
membrane.
There are several ways the chlorine
generator can be operated. The simplest way is to plug the
power controller into a power outlet that is only energized at times
when the generator is needed for chlorine
production. This on/off operation procedure can be
accomplished by installing a power control relay on the power outlet
circuit. Nearly all municipal well installations include this
type of circuit typically used for a hypochlorination
pump.
The power controller includes a flow
switch that ensures operation of the chlorine generator only when
there is flow through the venturi ejector. Having the pool
filter and water supply fill line on the vacuum ejector will allow
the chlorine generator to operate at any moment when water is moving
into the pool.
At a booster pump station having multiple
pumps, a chlorine generator for each pump circuit will supply the
step chlorine dosage needed depending on the number of pumps
operating. This operational procedure eliminates the need for
an electronic logic controlled loop and/or pacing valve
systems.
The
chlorine generator can be controlled in an automatic mode
associated with a chlorine demand change. The automatic mode requires
an electronic input signal (4-20 mA) associated with the demand
change that controls an optional EP1 Series - SCR Power Control
system. Consult Lemke Engineering Services for more
information.
The chlorine generator's small size
and portability allows the operator to use the chlorine
generator practically anywhere with multiple seasonal uses. In
the northern cold regions, use the chlorine generator to fill you
laundry tub when you are not needing the system on your frozen
swimming pool.
Dose Control
Chlorine output is
adjusted by the power input of the process. Every of direct current (DC)
provide a chlorine production rate of 1 pound per day (24
hours). The graph below
illustrates the equivalent chlorine production at the desired
amperage setting.
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Note: With time,
the membrane accumulates calcium and other mineral deposits
that increase the resistance between the electrodes.
The increased resistance causes a reduced amperage output
and a corresponding reduced chlorine output. The
system needs periodic membrane cleaning to recover the
desired amperage output. A water softener system can
be added to the system water supply to reduce the amount of
calcium, thus increasing the service life of the
membrane.
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Connecting your
power supply (battery charger) into the power controller will allow
you to manually adjust the voltage supply to your battery charger,
thus controlling the DC amperage output to the cell. The power controller provided with each
cell includes a switch to manually adjust the input
voltage to the battery charger.
Adjustment of the switch will increase or
decrease the voltage output of your battery charger to the
desired amperage setting. For example, a chlorine output
of 0.5 lbs per day is desired for a 50 gpm well. Based on amperage
conversions, approximately 8 amperes of DC power is needed for
the well. The operator
would adjust the switch to achieve a power output of 8 DC
amperes for the cell.
Salt
Addition
For every 50 lb bag of water softener
salt, approximately 30 lbs of chlorine is made. The amount of
salt that can be added to the cell depends on the shape of the salt
pellets; however, a typical amount of salt added in each cycle is
roughly 12 lbs. Twelve pounds of salt in the anode compartment
will generate 7 lbs of chlorine considering that not all the
salt is used in each cycle. The frequency of salt
addition depends on the operating cycle. For
example:
A 150
gpm municipal well operating a total of 6 hours per day (54,000
gpd) using a 1.5 lb/day
(22 amperes) chlorine dosage rate
(0.5 mg/l chlorine residual w/ a 0.35 mg/l chlorine demand) will
need to have salt added every 18 days (7 lbs/cell / [1.5
lb/day * 6 hr / 24
hr]).
Salt replenishment in the
anode compartment requires the drainage of the brine, flushing the
anode compartment with water, and addition of new salt and water to
the cell. Adding of salt to the cell without flushing and
cleaning is not recommended for several reasons. First,
the anode compartment contains residual chlorine gas that will be
displaced when salt is added. The amount of chlorine gas in
this space is small (0.02 lbs); however, this amount of chlorine gas
is irritating especially if in a confined space. Second, the
brine contains concentrated mineral impurities that will foul the
membrane at a more rapid rate if it is not removed.
Replenishing the salt consists
of:
- Turn off the power supply to the
cell.
- Add roughly 1 cup of sodium hydroxide
to the anode compartment. The sodium hydroxide will
neutralize the residual chlorine in the brine and make a salt
saturated hypochlorite solution.
- Drain the brine solution to waste and
flush out the cell removing all the residual matter in the bottom
of the cell.
- Add new salt and water to the anode
compartment (it is desirable to use softened water to reduce
the mineral fouling of the membrane).
- Place system back into
service.
Sodium Hydroxide
Dilution
SAFETY: Please note that sodium
hydroxide is corrosive and irritating to the skin. If sodium
hydroxide touches the skin, wash with water immediately to prevent
chemical burn. Wear protective clothing such as rubber gloves
and goggles when handling sodium hydroxide.
For every 50 lb bag of water softener salt, approximately 36
gallons of 18 percent sodium hydroxide solution is made.
The actual amount of sodium hydroxide produced is dependent upon the
level and frequency of dilution. Assuming a 7 lb chlorine cycle
per cell, the amount of sodium hydroxide produced from the cell is
approximately 8.5 gallons. Using the same 18-day
operational cycle as discussed above, approximately
one-half gallon of sodium hydroxide solution is produced every day
of operation.
Dilution of sodium hydroxide in the
cathode compartment requires the removal of approximately one-half
gallon of sodium hydroxide and the addition of dilution
water to 4-inches from the top of the cathode compartment
(Note: more sodium hydroxide is produced that water added for
dilution). It is desirable to use softened water for the
dilution to reduce the mineral fouling of the membrane.
Maintenance of the sodium hydroxide
solution within the optimum range (10-18 percent) provides extended
life of the membrane. Daily testing of the sodium hydroxide
solution with a typical battery hydrometer will verify the need to
dilute the sodium hydroxide. The following table
illustrates the specific gravity and concentration of sodium
hydroxide at a temperature of 60 degrees F (15.5 degrees
C):
|
% NaOH |
Specific Gravity |
|
2 |
1.023 |
|
4 |
1.045 |
|
6 |
1.067 |
|
10 |
1.090 |
|
12 |
1.112 |
|
14 |
1.134 |
|
16 |
1.156 |
|
18 |
1.178 |
|
20 |
1.201 |
|
22 |
1.223 |
Dilution of the sodium hydroxide consists
of:
- Turn off the power supply to the
cell.
- Removal of 1/2 gallon of solution (or
more if operating the cell at higher rates or longer periods of
time), and dispose/store as desired (this could be disposal down a
sanitary drain if solution is not needed; however, sodium
hydroxide is needed for pH adjustment in the pool, CIP cleaning
for diaries, lift station cleaning in sewer systems, and/or
pH adjustment of water for lead and copper corrosion control
in municipal drinking water).
- Add dilution water (preferably
softened water) to a level of 4-inches from the top of the cathode
compartment.
- place system back into service.
- check small amount of solution daily with a hydrometer.
System Maintenance
The chlorine generator has no moving
parts and requires minimal maintenance. The system maintenance
involves the periodic cleaning of the membrane. The salt and
water added to the chlorine generator contain calcium and other
minerals that accumulate on the surface of the membrane. These
mineral deposits increase the electrical resistance across the
membrane eventually reducing the amperage to the cell thus reducing
the chlorine production. Using the same 18-day operational
cycle as discussed above, you may achieve
two to four months of cell operation before needing to clean the
cell membrane (depends on the dilution water quality)
Operating the cell at 1 lb/day for 24 hours/day may require
membrane cleaning every month (again, depending on the dilution
water quality).
Cleaning the membrane involves the
following:
- Turn off the power supply to the
cell.
- Remove brine and salt from anode
compartment as described above.
- Draining and storage of sodium
hydroxide fro the cathode compartment.
- Flushing the interior of both
compartments with water to remove all loose
deposits.
- Encrusted mineral deposits on the
membrane can be removed by one of two methods.
- The membrane removal and replacement
method requires the removal of the membrane from the union
fitting and replacement with a cleaned membrane. The
membrane removed from the cell is then cleaned in a weak
hydrochloric acid solution (muriatic or pool acid) to dissolve
the mineral deposits. After cleaning, observe the
condition of the membrane and discard if pin-holes are observed
in the membrane. Otherwise, store membrane in a water
solution for the next cleaning cycle.
- The insitu cleaning method involves
the addition of water to top of the horizontal pipe connecting
the anode and cathode compartments. Addition of 1 cup of
muriatic acid to each cell compartment and agitate cell.
After five minutes, drain the cell and flush with
water.
- Restore sodium hydroxide to the
cathode chamber and salt and water to the anode chamber.
- Reconnect power to cell and resume
operation.
Items that wear and need eventual
replacement include the vacuum tubing, rubber gasket/o-ring,
membrane, and the anode. The anode has an expected life of five
years based on a chlorine rate of 1 lb/day under moderate
usage. The membrane has an anticipated life of one year
depending on the frequency and dilution of the sodium hydroxide (see
above). The rubber gasket in the cathode compartment may also need
to be replaced every few years as needed. The vacuum tubing
should be check annually and replace when cracks are observed.
Use chlorine compatible tubing such as polyethylene tubing when
replacing.
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