WO2008032946A1

WO2008032946A1 - Apparatus for producing sodium hypochlorite

Info

Publication number: WO2008032946A1
Application number: PCT/KR2007/004234
Authority: WO
Inventors: Soo-Kil Pyo
Original assignee: Soo-Kil Pyo
Priority date: 2006-09-13
Filing date: 2007-09-03
Publication date: 2008-03-20
Also published as: KR100736155B1

Abstract

Disclosed is an apparatus for producing sodium hypochlorite, suitable for the production of sodium hypochlorite through electrolysis of dilute salt water obtained by mixing feed water with saturated salt water at a predetermined ratio, wherein a feed water supply tank having a float valve is mounted between the raw water pipe and the supply pipe connected to the dilute salt water inlet hole in the electrolytic tank, to be higher than the electrolytic tank by at least a pre¬ determined height, and wherein a solenoid valve, which is opened in the presence of electric power and is automatically closed in the absence of electric power, is mounted between the water outlet hole in the feed water supply tank and the flow meter of the supply pipe. The output and concentration of sodium hypochlorite may be maintained constant, regardless of the amount and pressure of raw water, and it is possible to minimize interruptions in the production of sodium hypochlorite attributable to the operation of a protection apparatus additionally included in the apparatus for producing sodium hypochlorite in response to changes in the amount and pressure of feed water, greatly increasing product reliability. Problems in which the concentration of sodium hypochlorite, previously produced and stored in a tank, is decreased, or the tank overflows, may be prevented.

Description

APPARATUS FOR PRODUCING SODIUM HYPOCHLORITE

Technical Field

[1] The present invention relates to an apparatus for producing sodium hypochlorite, and more particularly, to an apparatus for producing sodium hypochlorite, in which an open-topped type feed water supply tank, which has a float valve and functions to discharge water by natural flow, is mounted between a salt water tank and an electrolytic tank to dilute salt water so that the flow rate and pressure (i.e., water pressure) of feed water that is supplied into the electrolytic tank are maintained constant, thereby maintaining the output and concentration of sodium hypochlorite constant, and furthermore, the supply of feed water and salt water from the feed water supply tank and the salt water tank, respectively, is automatically stopped in the event of a power failure, thus minimizing damage including a decrease in the concentration of previously produced sodium hypochlorite.

[2] Generally, sodium hypochlorite (NaOCl) is a colorless transparent liquid type chlorine-based disinfectant having a strong chlorine odor, for use in water purification plants, disinfectors for sewage treatment plants, cooling water boilers for general chemical plants, water treatment for desalting processes, cooling water treatment in plants, treatment of drinking water, processing of plants, vegetables and meats, washing of swimming pools, and bleaching agents for pulping and domestic use.

[3] For the production of sodium hypochlorite, useful is a non-membrane apparatus for producing sodium hypochlorite, in which a predetermined amount of saturated salt water having a predetermined pressure, obtained by placing a large amount of salt in a predetermined amount of feed water having a predetermined pressure for 8-24 hours to thus dissolve and saturate 26-28% salt, is mixed with feed water through a pump line to form dilute salt water having a salt concentration of 2.8-3.0%, which is then passed through an electrolytic tank having electrodes (positive electrode, negative electrode) without a membrane (an ion exchange membrane), such that salt in the dilute salt water is electrolyzed by direct-current voltage applied to both sides of the electrodes.

[4] Within the electrolyzer, the diluted brine solution- which is a good conductor of electricity-supports a current applied between the positive and negative electrodes, thus electrolyzing the sodium chloride solution. This results in chlorine(Cl ) gas being produced at the positive electrode (anode), while sodium hydroxide (NaOH) and hydrogen(H ) gas are produced at the negative electrode (cathode). The chlorine further reacts with the hydroxide to form sodium hypochlorite (NaOCl). This reaction can be simplified as follows: [5] NaCl + H O + Electricity → NaOCl + H

[6] Salt Water Sodium Hypochlorite Hydrogen

[7]

[8] The sodium hypochlorite thus produced, which is in a stable form of salt water, is used for chlorine disinfection or as an oxidant at sites requiring disinfection or oxidation. The output and concentration of sodium hypochlorite follow Faraday's law, and are determined by the condition of dilute salt water, which is a mixture of salt water and feed water.

[9]

Background Art

[10] Conventionally, an apparatus for producing sodium hypochlorite is constructed in a manner such that, as a means for continuously supplying a predetermined amount of feed water, a pump is used, and the flow rate and pressure of the feed water itself, which is supplied through the pump, are controlled using a pressure reducing valve or a flow rate control valve. Further, the supply of feed water and the stoppage of supply thereof are determined by the on/off mode of the pump.

[11] However, the above apparatus construction is disadvantageous because the discharge pressure and flow rate of the pump are forcibly controlled depending on need, and thus the pump is subjected to a load, undesirably decreasing the lifetime of the pump. Further, as the usage time of the pump increases, the pressure and flow rate are decreased due to physical wear or adhesion of sludge, and undesirably the discharge pressure and flow rate should be periodically adjusted.

[12] In addition, as an alternative means, an electromotive on/off valve and a pressure reducing valve or a flow rate control valve are mounted to a pipe which branches from a faucet or a pipe line, typically having a predetermined water pressure, and is connected to an electrolytic apparatus, thus controlling the flow rate and pressure of feed water. In this case, when the internal pressure of the pipe line changes, the flow rate and pressure of feed water flowing into the electrolytic apparatus are changed, and consequently the concentration and output of sodium hypochlorite produced using the electrolytic apparatus vary. In the case where the amount of water is drastically decreased, the electrolytic apparatus heats up and is damaged due to overheating. Moreover, when a power failure occurs during the operation of the electrolytic apparatus, the electromotive on/off valve, which is in an opened state, is not closed, and thus feed water is continuously supplied into the electrolytic apparatus, which is not operating, thereby decreasing the concentration of sodium hypochlorite, which was previously produced and stored in a tank, or causing the tank to overflow.

[13] In order to solve the above problems, there is proposed a conventional construction including a circuit for automatically closing the electromotive on/off valve in the event of a power failure. In this case, however, an electric charger (UPS) must be additionally provided, undesirably complicating the apparatus and increasing the cost.

[14]

Disclosure of Invention Technical Problem

[15] Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide an apparatus for producing sodium hypochlorite, in which an open-topped type feed water supply tank, which has a float valve and functions to discharge water by natural flow, is mounted between a salt water tank and an electrolytic tank so that the amount and water pressure of feed water that is supplied into the electrolytic tank for use in the production of sodium hypochlorite are maintained at predetermined levels, regardless of changes in the pressure of feed water supplied through the raw water pipe, thereby maintaining the output and concentration of sodium hypochlorite constant regardless of the amount and pressure of raw water, and furthermore, it is possible to minimize interruptions in the production of sodium hypochlorite attributable to the operation of a protection apparatus additionally included in the apparatus for producing sodium hypochlorite in response to changes in the amount and pressure of feed water, resulting in greatly increased product reliability.

[16] Another object of the present invention is to provide an apparatus for producing sodium hypochlorite, in which a solenoid valve and a check valve, respectively mounted between the feed water supply tank and the electrolytic tank and between the salt water tank and the electrolytic tank, are responsible for automatically stopping the inflow of feed water and salt water into the electrolytic tank in the event of a power failure, thereby preventing the generation of problems in which the concentration of sodium hypochlorite, which was previously produced and stored in a tank, is decreased or the tank overflows.

[17]

Technical Solution

[18] In order to accomplish the above objects, the present invention provides an apparatus for producing sodium hypochlorite, suitable for the production of sodium hypochlorite by supplying feed water into a supply pipe from a raw water pipe using a flow meter and a flow rate control valve and supplying saturated salt water into the supply pipe from a salt water tank through a pump so that the feed water and the saturated salt water are mixed at a predetermined ratio in the supply pipe to obtain dilute salt water, which is then supplied into an electrolytic tank to thus be electrolyzed, wherein a feed water supply tank having a float valve is mounted between the raw water pipe and the supply pipe, connected to the dilute salt water inlet hole in the electrolytic tank, so that the feed water supply tank is located higher than the electrolytic tank by at least a predetermined height.

[19] As such, the feed water supply tank may be formed in an open-topped type so that the feed water is discharged by natural flow under atmospheric pressure that is applied to a water surface.

[20] The feed water supply tank may be located so that the water surface thereof is

0.3-1.5 m higher than the electrolytic thank.

[21] The apparatus of the present invention may further include a solenoid valve, which is opened in the presence of electric power and is automatically closed in the absence of electric power, mounted between the water outlet hole in the feed water supply tank and the flow meter of the supply pipe.

[22] As well, a check valve may be additionally mounted between the pump of the salt water tank and the supply pipe connected to the dilute salt water inlet hole in the electrolytic tank to prevent the backflow of water when the operation of the pump is stopped.

[23] As described above, according to the apparatus for producing sodium hypochlorite of the present invention, first, an open-topped type feed water supply tank, which has a float valve and functions to discharge water by natural flow, is mounted between a salt water tank and an electrolytic tank so that the amount and water pressure of feed water that is supplied into the electrolytic tank for use in the production of sodium hypochlorite are maintained at predetermined levels, regardless of changes in the pressure of feed water supplied through the raw water pipe, thereby maintaining the output and concentration of sodium hypochlorite constant regardless of the amount and pressure of raw water, and furthermore, it is possible to minimize interruptions in the production of sodium hypochlorite attributable to the operation of a protection apparatus additionally included in the apparatus for producing sodium hypochlorite in response to changes in the amount and pressure of feed water, resulting in greatly increased product reliability.

[24] Second, a solenoid valve and a check valve, respectively mounted between the feed water supply tank and the electrolytic tank and between the salt water tank and the electrolytic tank, function to automatically stop the inflow of feed water and salt water into the electrolytic tank in the event of a power failure, thereby preventing the generation of problems in which the concentration of sodium hypochlorite, which was previously produced and stored in a tank, is decreased, or the tank overflows.

[25] Brief Description of the Drawings

[26] FIG. 1 is a schematic view illustrating the apparatus of the present invention; and

[27] FIG. 2 is a sectional view illustrating the electrolytic tank used in the apparatus for producing sodium hypochlorite.

[28] * Description of the Reference Numerals in the Drawings *

[29] 1: raw water pipe 2: flow meter

[30] 3: flow rate control valve 4: supply pipe

[31] 5: salt water tank 6: pump

[32] 7: electrolytic tank

[33] 8: feed water supply tank 9: float valve

[34] 10: solenoid valve 11: check valve

[35] 71 : dilute salt water inlet hole

[36] 72: case 73: electrode

[37] 74: electrode separator plate 75: electrode chamber

[38] 76: sodium hypochlorite outlet hole

[39] 81 : water outlet hole 91 : valve

[40] 92: operation rod 93: floating ball

[41]

Best Mode for Carrying Out the Invention

[42] Hereinafter, a detailed description will be given of the preferred embodiment of the present invention with reference to the appended drawings.

[43] FIG. 1 is a schematic view illustrating the apparatus of the present invention, and

FIG. 2 is a sectional view illustrating the electrolytic tank used in the apparatus for producing sodium hypochlorite.

[44] According to the present invention, the apparatus for producing sodium hypochlorite, suitable for production of sodium hypochlorite by supplying feed water into a supply pipe 4 from a raw water pipe 1, governed by a flow meter 2 and a flow rate control valve 3 and supplying saturated salt water into the supply pipe 4 from a salt water tank 5 through a pump 6 so that the feed water and the saturated salt water are mixed at a predetermined ratio in the supply pipe to obtain dilute salt water, which is then supplied into an electrolytic tank 7 to thus be electrolyzed, is characterized in that a feed water supply tank 8 having a float valve 9 is mounted between the raw water pipe 1 and the supply pipe 4 connected to the dilute salt water inlet hole 71 in the electrolytic tank 7, so that the feed water supply tank 8 is located higher than the electrolytic tank 7 by at least a predetermined height (h).

[45] The feed water supply tank 8 is characterized in that it is formed in an open-topped type to discharge feed water by natural flow under atmospheric pressure that is applied to the water surface.

[46] Further, the feed water supply tank 8 is located so that the water surface thereof is

0.3-1.5 m higher than the electrolytic tank 7.

[47] Also, the solenoid valve 10, which is opened in the presence of electric power and is automatically closed in the absence of electric power, is additionally mounted between the water outlet hole 81 in the feed water supply tank 8 and the flow meter 2 of the supply pipe 4.

[48] As well, the check valve 11, for preventing the backflow of water when the operation of the pump 6 is stopped, is additionally mounted between the pump 6 of the salt water tank 5 and the supply pipe 4, mounted to the dilute salt water inlet hole 71 in the electrolytic tank 7.

[49] The effect of operation of the apparatus of the present invention thus constructed follows.

[50] The main technical characteristic of the apparatus of the present invention, suitable for the production of sodium hypochlorite through electrolysis, in the electrolytic tank 7, of the dilute salt water obtained by mixing the feed water supplied through the raw water pipe 1 with the saturated salt water supplied through the pump 6 from the salt water tank 5 at a predetermined ratio, is that the feed water supply tank 8 having the float valve 9 is mounted between the raw water pipe 1 and the supply pipe 4 connected to the electrolytic tank 7.

[51] As such, the feed water supply tank 8 is preferably located higher than the electrolytic tank 7 by at least a predetermined height (h), so that the water in the feed water supply tank 8 can have a water pressure equal to or greater than a predetermined pressure. More preferably, the feed water supply tank 8 is located so that the water surface thereof is 0.3-1.5 m higher than the electrolytic tank 7.

[52] In the present invention, the feed water supply tank 8 is mounted, instead of a conventional pump. The feed water supply tank 8 is formed in an open-topped type to discharge the feed water by natural flow under atmospheric pressure applied to the water surface, so that the feed water supplied through the feed water supply tank 8 should have a constant pressure (which is atmospheric pressure in the present invention).

[53] The float valve 9, which consists of a valve 91, a floating ball 93, and an operation rod 92, and is mounted to the feed water supply tank 8, is automatically opened and closed depending on the change in the water level. Depending on variations in the water level with the amount of water discharged through the water outlet hole 81 formed in the bottom of the feed water supply tank 8, the position of the floating ball 93 changes. Further, the angle of the operation rod 92, mounted between the floating ball 93 and the valve 91, changes depending on the position of the floating ball 93, to thus automatically control the opening and closing of the valve 91. Accordingly, raw water is supplied and replenished in the feed water supply tank 8 through the float valve 9 connected to the raw water pipe 1, depending on the amount of water that is discharged through the water outlet hole 81 formed in the bottom of the feed water supply tank 8. Consequently, the water level of the feed water supply tank 8 is maintained constant all the time.

[54] Therefore, the water pressure of feed water, which is discharged into the electrolytic tank 7 through the water outlet hole 81 in the feed water supply tank 8 connected to the supply pipe 4, is maintained constant.

[55] Specifically, the pressure (or water pressure) of feed water, which is supplied into the electrolytic tank 7 from the feed water supply tank 8 to which the same magnitude of atmospheric pressure is applied to maintain the water level constant all the time, is in a constant state.

[56] As seen in FIG. 2, the electrolytic tank 7 includes electrode separator plates 74 for defining electrode chambers 75, each having a positive electrode and a negative electrode for applying electric power, and a case 72 containing the electrodes 73 and the electrode separator plates 74.

[57] The dilute salt water inlet hole 71, which is connected with the supply pipe 4, is formed in the bottom of the electrolytic tank 7, while a sodium hypochlorite outlet hole 76 for discharging sodium hypochlorite, produced through electrolysis, into a sodium hypochlorite tank, which is not shown in the drawing, is formed in the top thereof.

[58] The supply pipe 4, which is disposed between the water outlet hole 81 in the feed water supply tank 8 and the dilute salt water inlet hole 71 in the electrolytic tank 7, typically includes the flow meter 2 for showing the amount of feed water that is discharged from the feed water supply tank 8 to dilute the salt water, and the flow rate control valve 3 for selectively controlling the amount of feed water by a user to dilute the salt water to thus obtain salt water of a desired concentration.

[59] Further, in the present invention, the solenoid valve 10 is additionally mounted between the water outlet hole 81 in the feed water supply tank 8 and the flow meter 2 of the supply pipe 4. When electric power is normally supplied or the user turns on a power switch to operate the apparatus of the present invention, the solenoid valve 10 is opened to thus normally supply the feed water in the feed water supply tank 8. When a power failure occurs or the power switch is turned "off, the solenoid valve is automatically closed.

[60] Thus, it is possible to prevent the generation of problems in which the concentration of sodium hypochlorite, which was previously produced and stored in the sodium hypochlorite tank, is decreased, attributable to the continuous supply of feed water even when the electrolytic tank 7 does not operate due to a power failure or the like, or in which the sodium hypochlorite tank overflows due to the supply of feed water.

[61] Typically, the pump 6 for supplying 26-28% saturated salt water of the salt water tank 5 into feed water is mounted to the supply pipe 4 disposed between the salt water tank 5 and the dilute salt water inlet hole 71 in the electrolytic tank 7. In the present invention, the check valve 11 is additionally mounted to the supply pipe 4 between the pump 6 and the electrolytic tank 7, so that the backflow of water is prevented through the check valve 11 when the operation of the pump 6 is stopped due to the stoppage of supply of electric power.

[62] Thereby, the problem in which the concentration of salt water is decreased due to the backflow of feed water into the salt water tank 5 when the operation of the pump 6 is stopped may be prevented. Accordingly, the problem in which the salt water having a low concentration is diluted with feed water and supplied into the electrolytic tank 7 when the pump 6 and the electrolytic tank 7 operate normally may be prevented.

[63] As the pump, useful is a quantitative pump having a structure able to continuously supply a predetermined amount of water, for example, a diaphragm pump or a solenoid pump.

[64] When the power switch is turned "on" to produce sodium hypochlorite using the apparatus of the present invention thus constructed, the pump and the solenoid valve 10 are operated, and the electrolytic tank 7 is operated by constant direct current. As such, the user appropriately controls the flow rate control valve 3 while monitoring the flow meter 2, so that the salt water component of the dilute salt water that is supplied into the electrolytic tank 7 has 2.8-3.0%.

[65] When electric power begins to be supplied, 28-30% saturated salt water in the salt water tank 5, previously prepared by placing salt in water for 8-24 hours, is supplied toward the supply pipe 4 through the check valve 11 with the operation of the pump 6, and simultaneously, feed water in the feed water supply tank 8, having a predetermined water level due to the supply of raw water through the raw water pipe 1 with the operation of the float valve 9, is discharged at a predetermined water pressure through the water outlet hole 81, and flows into the supply pipe 4 through the solenoid valve 10, which is in an opened state in the presence of electric power with the use of the flow meter 2 and the flow rate control valve 3 to thus be mixed with the saturated salt water, thus forming 2.8-3.0% dilute salt water, which is then supplied into the electrolytic tank 7.

[66] Into the feed water supply tank 8, raw water is continuously supplied in an amount equal to the amount of feed water discharged from the feed water supply tank, using the float valve 9, to thus maintain the water level in the feed water supply tank 8 constant and keep the supply of feed water at constant pressure and flow rate all the time. [67] Specifically, as the feed water is discharged through the supply pipe 4, the floating ball 93 of the float valve 9, which is connected to the raw water pipe 1 and is mounted to the feed water supply tank 8, is operated downward depending on changes in the water level. Further, the operation rod 92 is swung downward around the valve 91 depending on the operation of the floating ball 93. Accordingly, the valve 91 is opened depending on the change in the angle of the operation rod 92, so that the water channel is opened to thus supply raw water from the raw water pipe 1 into the feed water supply tank 8. Then, when the level of feed water is increased and reaches a predetermined value due to the supply of raw water, the floating ball 93 is operated upward and the valve 91 is closed again, thus closing the water channel. Thereby, the water level in the feed water supply tank 8 is always maintained constant.

[68] Hence, the output and concentration of sodium hypochlorite may be maintained constant, regardless of the amount and pressure of raw water. Further, it is possible to minimize interruptions in the production of sodium hypochlorite attributable to the operation of the protection apparatus additionally included in the apparatus for producing sodium hypochlorite in response to changes in the amount and pressure of feed water, greatly increasing product reliability.

[69] Then, the dilute salt water is supplied into the electrolytic tank 7 via the supply pipe

4 and is then subjected to electrolysis, after which sodium hypochlorite, produced by electrolysis of the dilute salt water, is discharged through the outlet hole 76, formed in the top of the electrolytic tank 7, and is stored in the sodium hypochlorite tank, which is not shown in the drawing.

[70] As for the electrolytic tank 7, the dilute salt water is supplied into the electrolytic tank 7 through the dilute salt water inlet hole 71 formed in the bottom of the electrolytic tank 7, and is introduced into respective electrode chambers 75 through lower holes in the electrode separator plates 74 and is thus electrolyzed while flowing upward, thereby producing sodium hypochlorite. Sodium hypochlorite thus produced is discharged through the sodium hypochlorite outlet hole 76 via upper holes in the electrode separator plates 74, along with hydrogen gas produced in the course of electrolysis, and is then stored in the sodium hypochlorite tank.

[71] The electrode separator plates 74 in the electrolytic tank 7 thus constructed have upper and lower holes through them, and respective electrode chambers 75 are connected by such holes, so that the dilute salt water flows into the electrode chambers 75 through the hole in the bottom of the electrolytic tank, and is passed through the upper electrode and thus electrolyzed.

[72] Sodium hypochlorite and hydrogen gas thus generated are discharged from the electrode chambers 75 through the upper holes in the electrode separator plates 74 and then through the outlet hole 76. [73] When the supply of electric power is stopped due to a power failure or the like in the course of electrolyzing the dilute salt water having a salt concentration of 2.8-3.0% using the electrolytic tank 7, the solenoid valve 10 is automatically closed, as mentioned above, to thus automatically stop the supply of feed water from the feed water supply tank 8. As well, the backflow of the dilute salt water, containing the feed water, toward the salt water tank 5 may be blocked by the check valve 11. Thereby, it is possible to prevent the problems in which the concentration of sodium hypochlorite, which was previously produced and stored in the tank, is decreased or the sodium hypochlorite tank overflows due to the continuous supply of feed water.

[74] Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

[75]

Claims

[1] An apparatus for producing sodium hypochlorite, suitable for production of sodium hypochlorite by supplying feed water into a supply pipe from a raw water pipe using a flow meter and a flow rate control valve and supplying saturated salt water into the supply pipe from a salt water tank through a pump so that the feed water and the saturated salt water are mixed in the supply pipe to obtain dilute salt water, which is then supplied into an electrolytic tank to thus be electrolyzed, the apparatus comprising: a feed water supply tank having a float valve, mounted between the raw water pipe and the supply pipe connected to a dilute salt water inlet hole in the electrolytic tank, so that the feed water supply tank is located higher than the electrolytic tank by at least a predetermined height.

[2] The apparatus according to claim 1, wherein the feed water supply tank is formed in an open-topped type so that the feed water is discharged by natural flow under atmospheric pressure that is applied to a water surface.

[3] The apparatus according to claim 2, wherein the feed water supply tank is located so that a water surface thereof is 0.3-1.5 m higher than the electrolytic thank.

[4] The apparatus according to claim 1, further comprising a solenoid valve, which is opened in presence of electric power and is automatically closed in absence of electric power, mounted between a water outlet hole in the feed water supply tank and the flow meter of the supply pipe.