Method and apparatus for oxidant concentration control

文档序号:1159945 发布日期:2020-09-15 浏览:14次 中文

阅读说明:本技术 用于氧化剂浓度控制的方法和设备 (Method and apparatus for oxidant concentration control ) 是由 罗德尼·E·赫林顿 于 2018-11-19 设计创作,主要内容包括:披露了用于控制电解池中的电解以便无论所述电解池中电解质浓度或氧化剂生产的速率如何都保持恒定的消毒剂浓度的方法和设备。(Methods and apparatus are disclosed for controlling electrolysis in an electrolytic cell so as to maintain a constant disinfectant concentration regardless of the electrolyte concentration or the rate of oxidant production in the electrolytic cell.)

1. An apparatus for producing a disinfectant, the apparatus comprising:

(a) an electrolyte pump having an input port and an output port in fluid communication with an electrolyte source;

(b) an electrolytic cell having an input port in fluid communication with the output port of the electrolyte pump, and having an oxidant output port, and receiving electrical energy from an electrical energy source;

(c) a control system configured to control the electrolyte pump in response to an amperage of electrical energy consumed by the electrolytic cell such that an oxidant concentration of an oxidant exiting the electrolytic cell is maintained between predetermined upper and lower limits.

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 increase the flow rate of the electrolyte pump when the amperage of the electrical energy consumed by the electrolysis cell increases.

5. 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 the electrical energy consumed by the electrolysis cell decreases.

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

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

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

9. An apparatus for producing a disinfectant, the apparatus comprising:

(a) an electrolyte pump having an input port and an output port;

(b) an electrolyte reservoir in fluid communication with an input port of the electrolyte pump;

(c) an electrolytic cell in fluid communication with the electrolyte pump such that a 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 generates a signal representative of power consumed by the electrolytic cell;

(f) a control system responsive to the signal to control a flow rate of the electrolyte pump.

10. The apparatus of claim 9, wherein the power monitor generates a signal representative of the current entering the electrolytic cell.

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

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

14. The apparatus of claim 9, wherein the control system provides a reduced electrolyte pump flow rate as the power consumed by the electrolytic cell decreases.

15. The apparatus of claim 13, wherein the control system provides a decreasing electrolyte pump flow rate as the power consumed by the electrolytic cell decreases.

Technical Field

The present invention relates to the control of oxidant concentration in a two-phase flow in an electrolytic cell for the production of oxidant.

Background

The following discussion is directed to a number of publications and references. The discussion of such publications herein is presented to facilitate an understanding of the background of the scientific principles related to the present invention and is not to be construed as an admission that such publications are prior art for patentability determination purposes. Each of these publications is incorporated herein by reference.

Electrolytic techniques using Dimensionally Stable Anodes (DSA) have been used for many years to produce chlorine and other mixed oxidant solutions. Dimensionally stable anodes are described in U.S. Pat. No. 3,234,110 to Beer entitled "Electrode and Method of Making the Same," wherein a noble metal coating is applied to a titanium substrate.

An example of an electrolytic Cell with a Membrane is described in U.S. patent RE 32,077 to deNora et al entitled "Electrode Cell with Membrane and Method for making Same" wherein a circular dimensionally stable anode (wherein a Membrane surrounds the anode) and a cathode concentrically positioned around the anode/Membrane assembly are used.

An Electrolytic Cell with a dimensionally stable anode without a membrane is described in U.S. patent No. 4,761,208 entitled "Electrolytic Method and Cell for sterilingwater" to Gram et al.

Commercial electrolysis cells conventionally used for oxidant production use a flow-through configuration, optionally at sufficient pressure to generate a flow through the electrolysis device. Examples of cells of this configuration are described in U.S. patent No. 6,309,523 entitled "Electrode and Electrolytic Cell Containing Same" to prasanikar et al and U.S. patent No. 5,385,711 entitled "Electrolytic Cell for Generating sterilizing solutions with Increased Ozone Content" to Baker et al.

Typically, one of two control schemes is used in commercial in situ chlorine generation systems that use a continuous flow-through system. These schemes are used in order to optimize the operating performance in terms of operating cost while maintaining a fixed oxidant production rate.

Process solutions, inc (PSI), of Campbell, CA, uses constant feed brine and fluid flow to make the electrolyte concentration into the cell constant, but controls the voltage to maintain the oxidant concentration. As the electrode becomes contaminated, the voltage is increased to overcome the increase in resistance in the system, primarily by forming calcium carbonate scale on the cathode electrode. In this way, electrolyte conversion efficiency is maintained at the expense of increased power consumption.

A typical control scheme used in the MIOX electrolytic in-situ Generator is described in US 7,922,890 entitled "Low Maintenance On-Site Generator" to Sanchez et al. This control scheme uses a method of maintaining a precise and stable water flow rate into the electrolytic cell. The voltage on the system is fixed. Fully saturated brine from the variable speed brine pump enters the aqueous fluid stream and thus the electrolyte (into the battery). A fixed amperage in the cell generates the oxidant at a fixed concentration. If the amperage on the battery is low, the control system commands the brine pump to accelerate, which increases the brine concentration of the electrolyte entering the battery and thus increases the conductivity of the electrolyte and the amperage drawn from the power supply to the battery. In this scenario, the electrolyte concentration can be varied in order to maintain the correct amperage in the cell. The oxidant concentration can be kept constant if the amperage is kept constant with the flow and the applied voltage. The electrolyte conversion efficiency can be varied while maintaining the power conversion efficiency. A similar product is the so-called brine pump system or BPS. The BPS is encased in a hard plastic shell and includes a brine pump, power supply, and an electrolytic cell. However, this system uses a constant rate electrolyte pump. This system requires the operator to properly mix the salt and water in order to make the electrolyte so that the oxidant concentration is properly achieved. There is no control scheme to maintain a constant oxidant concentration.

Disclosure of Invention

Embodiments of the present invention may control the concentration of disinfectant produced in an electrolytic system used to produce the disinfectant. Oxidant production rate and operating efficiency are not critical parameters compared to other control schemes. Embodiments of the present invention control the concentration of oxidant produced in the cell. By controlling the correct oxidant concentration, the user dosing is consistent. In low input environments, the salt and water that are mixed to make the electrolyte may be mixed manually, and thus may not be mixed precisely. Embodiments of the present invention can compensate for human error when manufacturing an electrolyte solution by mixing salt and water together. In some embodiments of the invention, neither electrolyte conversion efficiency nor power conversion efficiency is a critical parameter. At low electrolyte brine concentrations, the oxidant production rate is low. This is because the conductivity of the solution is low and therefore lower amperages will be obtained from the power supply. Embodiments of the invention reduce the electrolyte flow rate by increasing the residence time of the electrolyte in the cell to maintain the oxidant concentration, thereby converting more brine to oxidant and increasing the concentration of oxidant. Conversely, if the electrolyte concentration is high, the oxidant production rate is high, and the control scheme increases the electrolyte flow rate to maintain the correct oxidant concentration (nominal 5,000mg/l concentration).

Advantages of the present invention include improved disinfectant concentration stability (regardless of electrolyte feed concentration, applied voltage, or flow rate through the electrolytic cell), making the system simpler to operate in: operator training is inadequate and environments that can compensate for inaccuracies (by the military), disaster relief environments, and other applications where operational simplicity and fault tolerance are important in systems used in low education environments. In this configuration, operational efficiency is balanced against fault tolerance. In these applications, consistent oxidant concentration is important to ensure consistent oxidant dosing by untrained operators. Suitable doses for cleaning medical surfaces are 5,000 milligrams per liter (mg/l) or parts per million (ppm), depending on the centers for Disease Control and Prevention (CDC) and World Health Organization (WHO). By way of example, this is the recommended dose for disinfecting medical areas and surfaces, body debris, and other surfaces actively exposed to ebola virus at outbreaks (such as those occurring in africa around 2015). The control scheme described herein produces a disinfectant having this nominal concentration. The control scheme can be configured to produce a consistent oxidizing agent at any practical concentration, typically less than 10,000 mg/l.

A concentration of 500ppm is typically recommended for cleaning the hands of people in a domestic environment and other applications for normal disinfection when threats like active ebola virus are present in the environment. At 500ppm, the user is easily instructed to add 10 parts of water to a pure disinfectant (at 5,000 ppm) to obtain a disinfectant concentration of about 500 ppm. For treated water intended for human consumption (i.e., drinking water), the user is easily instructed to add a dose of disinfectant through a measuring device (such as a teaspoon or other measuring vessel) to add a dose of pure disinfectant (at 5,000 mg/l) to 1000 parts of water. In this case, one milliliter (ml) of disinfectant is added per liter of water to be treated. The result was an addition of 5mg/l disinfectant to the water. This is the typical dosage used by the U.S. military for field treatment of water. In normal surface or ground water to be treated as drinking water, a 5mg/l dose will make most water safe to drink. The maximum recommended residual value of the U.S. Environmental Protection Agency (US Environmental Protection Agency, USEPA) in municipal treatment water is 4.0 mg/l. In disaster relief situations or low input environments where water safety is critical, a dosage of 5mg/l will typically result in a chlorine residual value of less than 4.0mg/l due to the species in the raw water that require the oxidant. At a 5.0mg/l dose, most of the water will have a residual value of n-chlorine that helps ensure the water is safe to drink.

Additional advantages and novel features of the invention, as well as further areas of applicability, will be set forth in part in the detailed description which follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Drawings

The accompanying drawings, which are incorporated in and form a part of this 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 preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:

fig. 1 is a view of a flow chart of a system.

Fig. 2 is a graph showing concentration over time at saline concentrations of 12, 15 and 18 grams/liter.

Detailed description of the invention and Industrial Applicability

Fig. 1 is an exemplary embodiment of a system according to the present invention. The system 10 includes an electrolytic cell 12, an electrolyte pump 16, a power supply 14, a control circuit 24, an electrolyte tank 18, and an oxidant tank 26. The electrolyte 20 comprises water and a halogen salt (typically sodium chloride) dissolved in the water. In an exemplary embodiment, the electrolyte concentration is about 15 grams per liter (g/l) of sodium chloride, and is typically made manually by measuring the correct amount of salt (sodium chloride) in a known amount of water. However, depending on the accuracy with which the operator mixes the salt into the water, the concentration of the electrolyte may vary widely from less than 10g/l to greater than 22 g/l. The power supply 20 may derive its power from conventional line power (e.g., 110/220VAC single phase power) or from other sources (e.g., batteries, generators, and solar cells). As an example, the output power may be nominally 12 Volts Direct Current (VDC) and supplied to the control panel 24. The control panel 24 may also include dc power terminals 30. A dc power source such as an automobile battery, solar panel, or other dc power source may be connected to the power terminals 30. The control circuitry 34 and power to the electrolyte pump 16 may be provided within the control panel 24. The control panel 24 may also incorporate a main power switch 32.

Upon activation of the main power switch 32, the electrolyte pump 16 may be activated by the control circuit 34. The electrolyte pump 16 is, for example, a positive displacement pump, such as a peristaltic pump having a variable speed motor, which may be a DC motor or a stepper motor or other type of variable speed motor. As the electrolyte pump 16 begins to operate, the electrolyte 20 is drawn through the optional filter 22, which helps remove contaminants or undissolved salts and may help extend the life of the electrolyte pump 16. The electrolyte 20 then travels through the electrolyte pump 16 and into the electrolytic cell 12. Power from the control circuit 34 within the control panel 24 is applied to the electrolytic cell 12. The electrolyte within the electrolytic cell 12 is converted to an oxidant 28, which is delivered to an oxidant tank 26. The conversion of the electrolyte 20 to the oxidant 28 is a well known chemical reaction that produces a strong disinfectant solution. The oxidizing agent 28 may be used to disinfect a contaminated fresh water source so that it may be used for human consumption, for disinfecting surfaces in a medical environment or other applications requiring a strong disinfectant solution. However, it is often important that the concentration of disinfectant is consistent and stable in order to apply the proper dose of disinfectant to the application in question.

In an exemplary embodiment of the invention, the control panel 24 includes a control circuit 34 that measures the current applied to the electrolytic cell 12. The current and the flow rate of electrolyte solution 20 determine the concentration of disinfectant solution 28 flowing from cell 12. In the case of a positive displacement electrolyte pump 16, the flow rate is precisely controlled by the speed of the electrolyte pump 16. In the exemplary embodiment, the operator has determined the salinity or brine concentration of electrolyte solution 20 as the salt and water are mixed by the operator. The concentration of the sanitizing solution 28 can be determined by the amperage applied to the electrolytic cell 12 and the speed of the electrolyte pump 16. An example of this data is presented in fig. 2. Fig. 2 shows the concentration of the oxidizer 28 for three different brine concentrations, where the speed of the electrolyte pump 16 has been controlled by the controller 34. As the data show, the concentration of the oxidizing agent was maintained in the range of 5,000 to 6,000mg/l regardless of the salt solution concentration of the electrolyte. As the electrolyte conductivity increases, as measured by the amperage introduced into the electrolytic cell 12, the speed of the electrolyte pump 16 is increased to increase the flow rate of the oxidant in the electrolytic cell. As the amperage was decreased, the flow rate was decreased by the electrolyte pump 16 so that the final concentration remained fixed at about 5,000 mg/l. The resulting equation is:

concentration, mg/l ═ (production rate, mg/min)/(flow rate, l/min)

By examining the above equation, in order to maintain the same oxidant concentration, the flow rate of the electrolyte must increase as the oxidant production rate increases, and vice versa. The software logic in the control board 34 is programmed to monitor the amperage in the electrolytic cell 12 and to increase or decrease the electrolyte flow rate accordingly by controlling the speed of the electrolyte pump 16.

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.

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