METHODS AND APPARATUSES FOR OXIDANT CONCENTRATION CONTROL

Abstract

Methods and apparatus for controlling electrolysis in an electrolytic cell in order to maintain constant concentration of the disinfectant irrespective of the rate of electrolyte concentration or oxidant production in the electrolytic cell.

Claims

1. An apparatus for the production of disinfectant, comprising: (a) an electrolyte pump having an input port in fluid communication with a source of electrolyte and an output port; (b) an electrolytic cell having an input port in fluid communication with the output port of the electrolyte pump such that the flow rate of electrolyte into the electrolytic cell is determined by the flow rate of the electrolyte pump, and having an oxidant output port, and accepting electrical energy from a source of electrical energy; and (c) a control system, configured to control the electrolyte pump responsive to the amperage of electrical energy consumed by the electrolytic cell such that the oxidant concentration of the oxidant exiting the electrolytic cell is maintained between predetermined upper and lower bounds, wherein the control system controls the electrolyte pump to increase the flow rate of the electrolyte pump when the amperage of electrical energy consumed by the electrolytic cell increases.

2. The apparatus of claim 1, wherein the electrolyte pump comprises a positive displacement pump.

3. The apparatus of claim 1, wherein the electrolyte pump comprises a peristaltic pump.

4. The apparatus of claim 1, wherein the control system controls the electrolyte pump to decrease the flow rate of the electrolyte pump when the amperage of electrical energy consumed by the electrolytic cell decreases.

5. The apparatus of claim 1, wherein the control system comprises a programmed digital controller.

6. The apparatus of claim 1, wherein the control system comprises an electronic circuit.

7. The apparatus of claim 1, wherein the input port of the electrolytic cell is connected to the output port of the electrolyte pump without an intervening mixing cell.

8. The apparatus of claim 1, wherein the voltage across the electrolytic cell is constant.

9. An apparatus for the production of disinfectant, comprising (a) an electrolyte pump, having an input port and an output port; (b) an electrolyte reservoir, in fluid communication with the input port of the electrolyte pump; (c) an electrolytic cell, in fluid communication with the electrolyte pump such that the flow rate of electrolyte into the electrolytic cell is determined by the flow rate of the electrolyte pump, and having a disinfectant output port; (d) a disinfectant reservoir, in fluid communication with the disinfectant output port; (e) a power monitor that produces a signal representative of power consumed by the electrolytic cell; and (f) a control system that controls the flow rate of the electrolyte pump responsive to the signal, wherein the control system provides for an electrolyte pump flow rate that increases with increasing power consumed by the electrolytic cell.

10. The apparatus of claim 9, wherein the power monitor produces a signal representative of electrical current into the electrolytic cell.

11. The apparatus of claim 9, wherein the electrolytic cell is in fluid communication with the output port of the electrolyte pump.

12. The apparatus of claim 9, wherein the electrolytic cell is in fluid communication with the electrolyte reservoir and the electrolyte pump such that fluid from the electrolyte reservoir passes through the electrolytic cell before reaching the input port of the electrolyte pump.

13. The apparatus of claim 9, wherein the control system provides for an electrolyte pump flow rate that decreases with decreasing power consumed by the electrolytic cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. In the drawings:

[0015] FIG. 1 is a view of the flow diagram of the system.

[0016] FIG. 2 is a view of a chart that shows concentration over time at 12, 15, and 18 grams per liter brine concentrations.

DESCRIPTION OF EMBODIMENTS AND INDUSTRIAL APPLICABILITY

[0017] FIG. 1 is an example embodiment of a system according to the present invention. System 10 comprises electrolytic cell 12, electrolyte pump 16, power supply 14, control circuit 24, electrolyte tank 18 and oxidant tank 26. Electrolyte 20 comprises water and a halogen salt, commonly sodium chloride, dissolved in the water. In an example embodiment, the electrolyte concentration is approximately 15 grams per liter (g/l) of sodium chloride and is typically made manually by measuring a correct amount of salt (sodium chloride) in a known amount of water. However, the concentration of the electrolyte can vary widely from less than 10 g/l to greater than 22 g/l depending on how accurate the operator mixes the salt into the water. Power supply 20 can obtain its power from conventional line power such as 110/220 VAC single phase source of electricity, or from other power sources such as batteries, generators, and solar cells. Output power can be, as an example, nominally 12 volts direct current (VDC) and is supplied to control panel 24. Control panel 24 can also comprise direct current power terminals 30. To these power terminals 30 can be connected a direct current source of power such as a car battery, solar panel, or other source of direct current power. Control circuit 34 and power to electrolyte pump 16 can be provided within control panel 24. Control panel 24 can also incorporates a main power switch 32.

[0018] Upon activation of main power switch 32, electrolyte pump 16 can be activated by control circuit 34. Electrolyte pump 16 is, for example, a positive displacement pump such as a peristaltic pump with a variable speed motor which can be a DC motor or stepper motor or other type of variable speed motor. As electrolyte pump 16 begins to operate, electrolyte 20 is drawn through optional filter 22, which helps remove contaminants or undissolved salt and can help extend the life of electrolyte pump 16. Electrolyte 20 then proceeds through electrolyte pump 16 and enters electrolytic cell 12. Power from control circuit 34 within control panel 24 is applied to electrolytic cell 12. The electrolyte within cell 12 is converted to oxidant 28 which is transported to oxidant tank 26. The conversion of electrolyte 20 to oxidant 28 is a well-known chemical reaction that produces a strong disinfecting solution. Oxidant 28 can be used to disinfect contaminated sources of fresh water to make it potable for human consumption, can be used to disinfect surfaces in medical settings, or other applications where a strong disinfectant solution is needed. It is often important, however, that the concentration of the disinfectant be consistent and stable in order that the proper dose of disinfectant is applied to the application in question.

[0019] In an example embodiment of the present invention, control panel 24 comprises control circuit 34 that measures the electrical current that is applied to electrolytic cell 12. Current and flow rate of electrolyte solution 20 determine the concentration of disinfectant solution 28 flowing from electrolytic cell 12. In the case of positive displacement electrolyte pump 16 the flow rate is precisely controlled by the speed of electrolyte pump 16. In an example embodiment, the salinity, or brine concentration, of electrolyte solution 20 has already been determined by the operator when salt and water are mixed by the operator. Through the amperage applied to electrolytic cell 12 and the speed of electrolyte pump 16 the concentration of disinfecting solution 28 can be determined. An example of this data is presented in FIG. 2. FIG. 2 shows the concentration of oxidant 28 for three different brine concentrations where the speed of electrolyte pump 16 has been controlled by controller 34. As the data shows, the concentration of the oxidant is held in the 5,000 to 6,000 mg/l range irrespective of the saline concentration of the electrolyte. As the conductivity of the electrolyte goes up as measured by the amperage draw in cell 12, the speed of electrolyte pump 16 increases to increase the flow rate of the oxidant in the cell. As the amperage goes down, the flow rate is reduced by electrolyte pump 16 so that the final concentration remains fixed at approximately 5,000 mg/l. The resulting equation is:

Concentration, mg/l=(Production rate, mg/min)/(Flow rate, l/min)

[0020] From inspection of the above equation, in order to maintain the same oxidant concentration, the flow rate of the electrolyte must go up as the oxidant production rate goes up, and vice versa. The software logic in control board 34 is programmed to monitor the amperage in cell 12, and increase or decrease the electrolyte flow rate accordingly by controlling the speed of electrolyte pump 16.

[0021] Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover all such modifications and equivalents. The entire disclosures of all patents and publications cited above are hereby incorporated by reference.