JP4018099B2 - Device for removing dissolved oxygen in liquid and method for removing dissolved oxygen - Google Patents

Description

  The present invention relates to a device for removing dissolved oxygen and a method for removing dissolved oxygen used in, for example, an air conditioning system, boiler water supply, drinking water production, food production, semiconductor ultrapure water production or various test research. .

  Water heat source air conditioning systems for air conditioning by supplying cold water or hot water in heat storage tanks to air conditioners (for example, fan coils) arranged at various locations in buildings are common in building air conditioning, etc., but dissolved in circulating liquids There is a problem that piping and coils are corroded by oxygen.

Therefore, by combining gas-liquid contact parts capable of gas-liquid contact with high efficiency in multiple stages and bringing the raw water and the inert gas into countercurrent contact, the gas partial pressure difference of the inert gas can be effectively used to make the inert gas A dissolved oxygen reduction device that reduces consumption is proposed (for example, see Patent Document 1 below). The apparatus shown in Patent Document 1 supplies raw water to an upper portion of a diffusion tower in which a plurality of gas-liquid contact portions and gas-liquid separation portions are arranged between the gas-liquid contact portions in a substantially vertical direction, Introducing an inert gas from the bottom of the tower, repeatedly bringing the raw water flowing down in the gas-liquid contact section into countercurrent contact with the rising inert gas, dissipating dissolved oxygen in the raw water to the inert gas side, and mass transfer It is supposed to let you.
JP 2004-141840 A

  However, in the apparatus as shown in Patent Document 1, since the gas-liquid contact portions (reactors) having a complicated structure are arranged in multiple stages in order to ensure the removal performance of dissolved oxygen, the internal structure is complicated. There is a lower limit on the size, so miniaturization is not possible. In addition, since the reactors are complicated and expensive and are arranged in multiple stages, the equipment cost increases. For this reason, for applications where the amount of raw water is small, there is too much equipment waste and it has been substantially difficult to apply. On the other hand, if the number of reactor stages is reduced in order to reduce the size, there is a problem that sufficient dissolved oxygen removal performance cannot be obtained.

  In addition, those that contact water and nitrogen by methods such as so-called static mixers and bubbling have poor contact efficiency, so they use a large amount of nitrogen, increase the size of the device, and limit the reduction in DO value (dissolved oxygen value). There are restrictions such as high. In the case of a system other than the nitrogen system such as a membrane deoxygenator, there are limitations on DO value, water quality, water temperature, and the like.

  This invention is made | formed in view of the above situations, and it aims at provision of the dissolved oxygen removal apparatus and dissolved oxygen removal method in a liquid which remove effectively the dissolved oxygen in a liquid.

In order to achieve the above object, a device for removing dissolved oxygen in a liquid according to the present invention has a gas-liquid contact portion that removes dissolved oxygen in the liquid by bringing the liquid to be treated and an inert gas into gas-liquid contact. An oxygen tower,
A liquid supply path for supplying the liquid above the gas-liquid contact portion of the deoxygenation tower;
An inert gas supply path for supplying the inert gas downward from the gas-liquid contact portion of the deoxygenation tower;
A storage tank for storing the liquid in gas-liquid contact with the inert gas by the gas-liquid contact portion of the deoxygenation tower;
A lead-out path for leading a part of the liquid stored in the storage tank to the outside as a processing liquid;
A reflux path for introducing a part of the liquid stored in the storage tank above the gas-liquid contact part of the deoxygenation tower to reflux ;
The ratio between the flow rate of the liquid introduced above the gas-liquid contact portion of the deoxygenation tower by the reflux path and the flow rate of the liquid led to the outside by the lead-out path or the flow rate of the liquid supplied by the liquid supply path The gist of the invention is that it includes a flow rate control means for controlling the amount of dissolved oxygen in the liquid led out by the lead-out pipe .

In order to achieve the above object, the method for removing dissolved oxygen in a liquid according to the present invention includes a gas-liquid contact portion that removes dissolved oxygen in the liquid by bringing the liquid to be treated and an inert gas into gas-liquid contact. Supplying the liquid from the liquid supply path above the gas-liquid contact portion of the deoxygenation tower,
Supply the inert gas below the gas-liquid contact portion of the deoxygenation tower,
The liquid in gas-liquid contact with the inert gas by the gas-liquid contact part of the deoxygenation tower is stored in a predetermined storage tank,
A part of the liquid stored in the storage tank is led out from the lead-out path as a processing liquid,
A part of the liquid stored in the storage tank is introduced above the gas-liquid contact part of the deoxidation tower to be refluxed ,
The ratio of the flow rate of the liquid introduced above the gas-liquid contact part of the deoxygenation tower by the reflux and the flow rate of the liquid led out to the outside by the lead-out path or the flow rate of the liquid supplied by the liquid feed path and gist that you controlled by flow control means in accordance with the amount of dissolved oxygen in the liquid derived by the derivation tube.

  That is, according to the present invention, a part of the liquid stored in the storage tank is introduced above the gas-liquid contact portion of the deoxygenation tower and refluxed.

Therefore, since the liquid can be circulated between the storage tank and the gas-liquid contact portion to improve the frequency of gas-liquid contact, the concentration of dissolved oxygen in the liquid can be efficiently reduced, and the concentration of dissolved oxygen Can be obtained as a treatment liquid. Moreover, even if the structure is simplified, for example, by reducing the number of reactor stages, sufficient dissolved oxygen removal performance can be ensured, so that the apparatus can be reduced in size, and the equipment cost and running cost of the apparatus can be reduced. Can be suppressed. Moreover, since this apparatus can be reduced in size, it can be applied to applications where the flow rate of the supplied stock solution is small.
Further, the flow rate of the liquid introduced above the gas-liquid contact portion of the deoxygenation tower by the reflux path and the flow rate of the liquid led out by the lead-out path or the flow rate of the liquid supplied by the liquid supply path Since the flow rate control means for controlling the ratio according to the dissolved oxygen amount of the liquid led out by the lead-out pipe is provided, the flow rate of the circulating fluid to be introduced and refluxed above the gas-liquid contact part of the deoxygenation tower is The flow rate of the processing liquid led out to the outside or the flow rate of the supplied stock solution can be increased. As a result, it is possible to circulate a liquid having a flow rate larger than the flow rate of the liquid led out as the treatment liquid between the storage tank and the gas-liquid contact portion as the treatment liquid, so that the treatment with a very low concentration of dissolved oxygen is performed. A liquid can be obtained easily. In addition, since the circulating liquid in the reflux path is introduced above the gas-liquid contact part of the deoxygenation tower, the stock solution is sufficiently diluted with the circulating liquid and supplied above the gas-liquid contact part of the deoxygenation tower. The concentration of dissolved oxygen in the liquid stored in the storage tank can be prevented from increasing, and a treatment liquid having a very low concentration of dissolved oxygen can be obtained. Moreover, when the dissolved oxygen value is high, the amount of circulating water to be circulated between the storage tank and the gas-liquid contact part is increased to improve the frequency of gas-liquid contact and further reduce the concentration of dissolved oxygen in the circulation. When the dissolved oxygen value is low, the concentration of dissolved oxygen can be reduced to some extent by reducing the amount of circulating water between the storage tank and the gas-liquid contact part to reduce the frequency of gas-liquid contact. And can automatically stabilize the quality of the treated water.

In the present invention, when the outlet channel and the reflux channel are branched downstream of the delivery pump for delivering the treated liquid from the storage tank, it is necessary to provide a water feed pump for each of the outlet tube and the reflux tube. In addition, it is possible to reduce equipment costs such as a water pump and a control device.

  In the present invention, a first ejector communicating with the liquid supply path is provided, and the first ejector includes a liquid supplied above the gas-liquid contact portion of the deoxygenation tower by the liquid supply path, and the inert gas. When the gas is brought into gas-liquid contact, the concentration of dissolved oxygen in the stock solution can be effectively reduced by the first ejector before removing the dissolved oxygen from the stock solution at the gas-liquid contact portion. Therefore, the concentration of dissolved oxygen is increased too much by mixing the stock solution supplied by the liquid supply path and the circulating liquid introduced by the reflux path above the gas-liquid contact portion of the deoxygenation tower. Can be prevented. Moreover, since the ejector is used, the concentration of dissolved oxygen in the stock solution can be effectively reduced even when the flow rate of the stock solution is small.

  In the present invention, a second ejector that communicates with the reflux path is provided, and the second ejector removes the liquid introduced above the gas-liquid contact portion of the deoxygenation tower and the inert gas through the reflux path. In the case of contact with the liquid, the concentration of dissolved oxygen in the circulating liquid introduced through the reflux path by the second ejector can be further reduced. Further, since the ejector is used, the concentration of dissolved oxygen in the circulating fluid can be effectively reduced even when the flow rate of the circulating fluid introduced through the reflux path is small.

  Next, the best mode for carrying out the present invention will be described.

  FIG. 1 is a diagram showing an embodiment of a dissolved oxygen removing apparatus according to the present invention.

  As shown in FIG. 1, in this embodiment, the dissolved oxygen removing device 1 is a water heat source that adjusts air by supplying circulating water such as cold water or hot water to an air conditioner 3 arranged at various locations in a building or the like. Used in air conditioning systems. Hereinafter, a case where cold water is supplied to the air conditioner 3 will be described as an example.

  The water heat source air conditioning system includes a gas pipe 11 that circulates refrigerant gas, a compressor 13 that compresses the refrigerant gas, and a heat exchanger that cools the refrigerant gas in the gas pipe 11 using cooling water cooled by a cooling tower 23 described later. 15. A gas circulation system including an expander 17 that expands refrigerant gas, a cooling water pipe 21 that circulates cooling water for cooling the refrigerant gas in the heat exchanger 15, and cooling the cooling water in contact with the atmosphere. A cooling tower (cooling tower) 23, a pipe opening / closing valve 25 for opening and closing the cooling water pipe 21, a cooling water circulation system including a cooling tower side circulation pump 27 for circulating the cooling water in the cooling water pipe 21, and the like. A heat exchanger 32 that cools water in an air-conditioner-side cold / hot water pipe 33 (described later) with the refrigerant gas expanded and cooled by the air conditioner 3 and the expander 17, and the cold water cooled by the heat exchanger 32 To supply From an air conditioner side cold / hot water pipe 33, an air conditioner side on / off valve 35 for opening / closing the air conditioner side cold / hot water pipe 33, an air conditioner side circulation pump 37 for circulating cold water in the air conditioner side cold / hot water pipe 33, etc. It consists of a cold water circulation system.

  The cooling water circulation system is an open system that comes into contact with the atmosphere in the cooling tower 23, and the cold water circulation system is a closed system that does not come into contact with the atmosphere. The heat exchangers 15 and 32 are used for a cold / hot water generator, a boiler, etc., and respond | correspond to an air conditioning.

  In this example, two dissolved oxygen removal apparatuses 1 of the present invention are prepared, each of a cooling water pipe 21 of a cooling water circulation system that is an open system and an air conditioner side cold / hot water pipe 33 of a cold water circulation system that is a closed system. It is connected to the. These dissolved oxygen removal devices 1 remove dissolved oxygen in the cooling water of the cooling water circulation system and dissolved oxygen in the cold water of the cooling water circulation system, thereby preventing corrosion of each pipe caused by the dissolved oxygen. Yes.

  The dissolved oxygen removing apparatus 1 connected to the cooling water pipe 21 of the cooling water circulation system is connected to the downstream side of the cooling tower 23 in the cooling water pipe 21 and cools the cooling water (raw solution) after passing through the cooling tower 23. It takes in from the water pipe 21, removes dissolved oxygen in the taken-in cooling water (raw water), and returns it to the upstream side of the heat exchanger 15 in the cooling water pipe 21.

  The dissolved oxygen removing device 1 connected to the air conditioner side cold / hot water pipe 33 is used to compensate for water that has decreased when the cold water (raw solution) leaks from the air conditioner side cold / hot water pipe 33 or when water (cold water) is removed. The make-up water is taken in from the outside, dissolved oxygen in the taken-in make-up water (raw water) is removed, and supplied to the air conditioner side cold / hot water pipe 33. By doing in this way, the supplementary water from which dissolved oxygen was removed can be supplied to the air conditioner side cold / hot water pipe 33. In addition, cold water (raw solution) may be taken in from the air conditioner side cold / hot water pipe 33, and dissolved oxygen in the taken cold water (raw water) may be removed and returned to the air conditioner side cold / hot water pipe 33. By doing in this way, a dissolved oxygen removal process can be performed with respect to the whole quantity of the raw | natural water which distribute | circulates the inside of the air-conditioner side cold / hot water piping 33. FIG. Thereby, it can respond to the case where oxygen has melted into the cold water flowing through the air-conditioner side cold / hot water pipe 33.

  Since the two dissolved oxygen removing devices 1 are the same, the one connected to the cooling water pipe 21 will be described as an example.

  Next, the dissolved oxygen removing apparatus 1 will be described with reference to FIG.

The dissolved oxygen removing apparatus 1 has a gas-liquid contact portion 41 that removes dissolved oxygen in the raw water by bringing the raw water that is the liquid to be treated into contact with the nitrogen gas (N ₂ ) that is the inert gas. Deoxygenation tower 43, raw water supply pipe 45 that is a liquid supply path for supplying the raw water above gas-liquid contact portion 41 of deoxygenation tower 43, nitrogen gas supply device 46 for supplying nitrogen gas, and nitrogen gas supply An inert gas supply path (nitrogen gas supply pipe 47 and water space 49a in the storage tank 49 described later) for supplying nitrogen gas supplied from the apparatus 46 downward from the gas-liquid contact portion 41 of the deoxygenation tower 43; A storage tank 49 for storing raw water in gas-liquid contact with nitrogen gas by the gas-liquid contact section 41 of the deoxygenation tower 43, and a part of the raw water stored in the storage tank 49 as treated water (processed liquid) Derived to (specifically, cooling water piping 21) A part of the outlet water 51, the branch pipe 51a branched from the outlet pipe 51, and the stored water, which is the raw water stored in the storage tank 49, is part of the gas-liquid contact portion 41 of the deoxygenation tower 43. And a reflux pipe 53 which is a reflux path for introducing and refluxing further upward.

  The raw water supply pipe 45 is supplied from the cooling water pipe 21 by having one end connected to the cooling water pipe 21 (FIG. 1) and the other end connected above the gas-liquid contact portion 41 of the deoxygenation tower 43. The raw water is introduced above the gas-liquid contact part 41 in the deoxygenation tower 43.

  The nitrogen gas supply pipe 47 has one end connected to the nitrogen gas supply device 46 and the other end connected to the storage tank 49, thereby introducing nitrogen gas supplied from the nitrogen gas supply device 46 into the storage tank 49. It is supposed to be.

  One end of the lead-out pipe 51 is connected to the storage tank 49 and the other end is connected to the cooling water pipe 21, so that the raw water stored in the storage tank 49 is treated as external water (specifically, cooling water). It is led out to the piping 21).

  The reflux pipe 53 has one end connected to the outlet pipe 51 and the other end connected above the gas-liquid contact portion 41 of the deoxygenation tower 43 to deoxygenate the raw water stored in the storage tank 49. It is introduced above the gas-liquid contact portion 41 in the tower 43. That is, the reflux pipe 53 branches from the outlet pipe 51 and introduces a part of the treated water above the gas-liquid contact portion 41 in the deoxygenation tower 43.

  A water feed pump 54 for feeding the raw water in the storage tank 49 is provided on the upstream side of the portion where the reflux pipe 53 branches in the outlet pipe 51. Thus, by branching the return pipe 53 from the outlet pipe 51 on the downstream side of the water pump 54, there is no need to provide a water pump in each of the outlet pipe 51 and the reflux pipe 53, and facilities such as a water pump and a control device are provided. Cost can be saved.

  An exhaust pipe 55 for exhausting nitrogen gas is connected to the top of the deoxygenation tower 43.

  The storage tank 49 is connected to the lower part of the deoxygenation tower 43 and stores raw water flowing down in the deoxygenation tower 43. The nitrogen gas introduced from the nitrogen gas supply pipe 47 is filled in the water surface space 49 a in the storage tank 49 and rises, and is supplied to the gas-liquid contact portion 41 of the deoxygenation tower 43. That is, the water surface space 49 a in the nitrogen gas supply pipe 47 and the storage tank 49 supplies an inert gas that supplies the nitrogen gas supplied from the nitrogen gas supply device 46 downward from the gas-liquid contact portion 41 of the deoxygenation tower 43. Act as a road.

  A drain pipe 67 for draining raw water in the storage tank 49 to the outside is connected to the bottom of the storage tank 49. The drain pipe 67 is provided with a drain pipe opening / closing valve 69 that opens and closes the drain pipe 67 and controls the drainage of raw water to the outside.

  The raw water supply pipe 45 is connected to a ball tap that opens and closes the raw water supply pipe 45 in accordance with the level of the raw water stored in the storage tank 49 and controls the opening and closing of the introduction of the raw water into the deoxygenation tower 43. An on-off valve 71 is provided. For example, when the liquid level of the raw water stored in the storage tank 49 is lowered, the supply pipe opening / closing valve 71 is opened by the ball tap, and the raw water is introduced from the raw water supply pipe 45 into the deoxygenation tower 43, Is raised, the supply pipe on-off valve 71 is closed by the ball tap, and the introduction of the raw water from the raw water supply pipe 45 into the deoxygenation tower 43 is stopped. For this reason, the raw water is supplied from the raw water supply pipe 45 in substantially the same amount as the derived treated water.

  The nitrogen gas supply pipe 47 includes a gas pipe opening / closing valve 73 for opening / closing the nitrogen gas supply pipe 47 and controlling the opening / closing of the introduction of nitrogen gas from the nitrogen gas supply device 46 into the storage tank 49, and the nitrogen gas supply pipe 47. And a nitrogen gas flow meter 75 for measuring the flow rate of the nitrogen gas.

  The outlet pipe 51 includes a outlet pipe opening / closing valve 76 that opens and closes the outlet pipe 51 and controls the opening and closing of the outlet of the treated water to the cooling water pipe 21, and a treated water flow meter that measures the flow rate of the treated water in the outlet pipe 51. 77 and a check valve 78 that restricts the flow in the reverse direction (in the direction of the storage tank 49). The check valve 78 is provided in the vicinity of the outlet of the outlet pipe 51.

  The reflux pipe 53 includes a reflux pipe on / off valve 79 that opens and closes the reflux pipe 53 and controls the opening and closing of the introduction of raw water (here, circulating water) into the deoxygenation tower 43, and the circulating water in the reflux pipe 53. A circulating water flow meter 81 for measuring the flow rate is provided.

  The branch pipe 51a branched from the outlet pipe 51 has a branch pipe on-off valve 83 that opens and closes the branch pipe 51a and controls the opening and closing of water into the outlet pipe 51, and the dissolved oxygen concentration value in the raw water of the branch pipe 51a. A DO sensor 85 that measures (DO value) is provided. The branch pipe 51 a branched from the outlet pipe 51 is connected to the downstream side of the treated water flow meter 77 in the outlet pipe 51.

  In the present embodiment, the flow rate of circulating water introduced above the gas-liquid contact portion 41 of the deoxygenation tower 43 by the reflux pipe 53 and the flow rate of treated water led out by the lead-out pipe 51 or the raw water supply pipe The ratio with the flow rate of the raw water supplied by 45 is controlled by flow control means such as the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83.

  Specifically, the degree of opening and closing of the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83 is set in advance, so that the gas-liquid contact portion of the deoxygenation tower 43 is connected to the reflux pipe 53. The ratio of the flow rate of circulating water (circulated liquid) introduced above 41 and the flow rate of treated water led out to the outside by the outlet pipe 51, the flow rate of the circulating water and the raw water flow rate supplied by the raw water supply pipe 45 The ratio is controlled.

  By doing in this way, the flow volume of the said circulating water can be made larger than the flow volume of the said treated water or the said supplied liquid. As a result, since a liquid having a flow rate larger than the flow rate of the treated water led out to the outside can be circulated between the storage tank 49 and the gas-liquid contact portion 41 as the circulating water, the treatment with a very low concentration of dissolved oxygen is performed. Water can be easily obtained. In addition, since the circulating water from the reflux pipe 53 is introduced above the gas-liquid contact portion 41 of the deoxygenation tower 43, the circulating water is sufficient for the raw water above the gas-liquid contact portion 41 of the deoxygenation tower 43. The raw water (reserved water) stored in the storage tank 49 can be prevented from increasing the concentration of dissolved oxygen, and treated water having a very low dissolved oxygen concentration can be obtained.

  In addition, as described above, the same amount of raw water as the derived amount of treated water is circulated, and the deoxygenation treatment in the reactor is repeated, so that the same treatment as that of the apparatus having a plurality of reactors can be performed efficiently at low cost. Can do. In this embodiment, the degree of opening / closing of the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83 is set in advance, but may be controlled based on the measurement result of the DO sensor 85. Good. That is, the DO sensor 85 also functions as a flow control means, and the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83 control the degree of opening and closing based on the measurement result of the DO sensor 85, respectively. It may be. For example, when the DO value is high as a measurement result of the DO sensor 85, the degree of opening / closing of the reflux pipe on / off valve 79 is increased or / and the degree of opening / closing of the outlet pipe on / off valve 76 or the branch pipe on / off valve 83 is decreased. You may do it. On the other hand, when the DO value is low as a measurement result of the DO sensor 85, the degree of opening / closing of the reflux pipe on / off valve 79 is decreased, and / or the degree of opening / closing of the outlet pipe on / off valve 76 or the branch pipe on / off valve 83 is increased. You may do it. The determination of whether the DO value is high or low may be made based on whether the DO value is higher or lower than a predetermined threshold value. In this case, when the DO value is higher than a predetermined threshold as a measurement result of the DO sensor 85, the degree of opening / closing of the reflux pipe on / off valve 79 is increased or / and the outlet pipe on / off valve 76 and the branch pipe on / off valve 83 are increased. The degree of opening and closing may be reduced. On the other hand, when the DO value is lower than a predetermined threshold as a measurement result of the DO sensor 85, the degree of opening / closing of the reflux pipe on / off valve 79 is reduced, and / or the opening / closing of the outlet pipe on / off valve 76 or the branch pipe on / off valve 83 is opened / closed. The degree may be increased. Control of the degree of opening / closing of the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83 is carried out by the DO sensor 85 measuring the reflux pipe on / off valve 79, the outlet pipe on / off valve 76, and the branch pipe on / off valve 83 itself. It may be performed based on the result, or may be performed by the DO sensor 85 having a function of controlling the degree of opening and closing. By doing so, when the DO value is high, the amount of circulating water circulated between the reservoir 49 and the gas-liquid contact part 41 is increased, the frequency of gas-liquid contact is improved, and the dissolved oxygen in circulation is increased. The concentration can be further reduced. On the other hand, when the DO value is low, the amount of circulating water circulated between the storage tank 49 and the gas-liquid contact portion 41 can be reduced, the frequency of gas-liquid contact can be reduced, and the concentration of dissolved oxygen can be lowered to some extent. it can. Thereby, the quality of treated water can be automatically stabilized.

  Now, the nitrogen gas supply device 46 will be described with reference to FIG.

  The nitrogen gas supply device 46 uses a PSA (Pressure Swing Adsorption) method to extract nitrogen gas from a predetermined amount of raw material air with a predetermined nitrogen yield, and into the storage tank 49 via a nitrogen gas supply pipe 47. A predetermined amount of nitrogen gas is supplied. The nitrogen gas supply device 46 has two adsorption towers, a first adsorption tower 101 and a second adsorption tower 103, having a predetermined capacity (PSA capacity) in order to continuously supply nitrogen gas. Switch to drive.

  An adsorbent that mainly adsorbs oxygen is sealed in the first adsorption tower 101 and the second adsorption tower 103 of the nitrogen gas supply device 46. The adsorbent adsorbs oxygen when the pressure in the adsorption tower is increased, and releases the adsorbed oxygen when the pressure is decreased.

  3A shows a nitrogen gas supply device 46 that supplies a predetermined amount of nitrogen gas from the first adsorption tower 101 and exhausts a predetermined amount of oxygen gas from the second adsorption tower 103. FIG. B) shows a nitrogen gas supply device 46 that supplies a predetermined amount of nitrogen gas from the second adsorption tower 103 and discharges a predetermined amount of oxygen gas from the first adsorption tower 101.

  A nitrogen gas supply device 46 shown in FIG. 3A introduces a predetermined amount of raw material air into the high-pressure first adsorption tower 101 and extracts nitrogen gas by adsorbing oxygen from the raw material air in the first adsorption tower 101. The nitrogen gas is supplied from the supply port into the storage tank 49 through the nitrogen gas supply pipe 47. During this time, a predetermined amount of the extracted nitrogen gas is introduced into the low-pressure second adsorption tower 103, and oxygen gas containing a predetermined amount of oxygen is discharged from the second adsorption tower 103 through the discharge port (reverse flow purge). ). As shown in the figure, the nitrogen gas supply device 46 has a flow passage through which the raw air, nitrogen gas, and oxygen gas flow, and a plurality of on-off valves that control these flow passages, each switching the flow direction as necessary. The flow passage is opened and closed.

  As shown in FIG. 3B, before the adsorbent of the first adsorption tower 101 is saturated with oxygen, the nitrogen gas supply device 46 switches the inside of the second adsorption tower 103 to a high pressure, and at the same time, the first adsorption tower 101. Switch to low pressure inside. Then, a predetermined amount of raw material air is introduced into the high-pressure second adsorption tower 103, nitrogen gas is extracted by adsorbing oxygen from the raw material air by the second adsorption tower 103, and the nitrogen gas is supplied from the supply port. It is supplied into the storage tank 49 through the pipe 47. During this time, a predetermined amount of the extracted nitrogen gas is introduced into the low-pressure first adsorption tower 101, and oxygen gas containing a predetermined amount of oxygen is discharged from the first adsorption tower 101 through the discharge port.

  Thus, the nitrogen gas supply device 46 continuously supplies a predetermined amount of nitrogen gas into the storage tank 49 via the nitrogen gas supply pipe 47.

  In the above embodiment, the PSA-type nitrogen gas supply device 46 is adopted as the nitrogen gas supply device, but the present invention is not limited to this, and for example, a membrane separation type nitrogen gas supply device is adopted. May be.

  The membrane separation type nitrogen gas supply apparatus separates and generates nitrogen gas in the raw material air by utilizing the difference in gas membrane permeation speed. Since the speed at which the gas permeates the membrane is determined by the solubility and diffusibility of the gas molecules in the membrane, oxygen with a fast permeation rate is discharged outside the membrane, and nitrogen with a slow permeation rate is supplied. .

  By adopting the above membrane separation type nitrogen gas supply device, stable supply of nitrogen gas, easy operation, no vibration part and less noise vibration, simple device configuration, small installation space, maintenance free, It has the effect of not being restricted by the High Pressure Gas Safety Law.

  A nitrogen gas cylinder that stores nitrogen gas may be employed as the nitrogen gas supply device 46.

  Next, the gas-liquid contact portion 41 will be described with reference to FIG.

  As shown in the figure, the gas-liquid contact portion 41 of this embodiment is provided with a mixing element 115 (FIG. 4A) having a plurality of right twist blades 113 provided with a large number of holes 111 and a large number of holes 111. A static mixer (reactor) in which mixing elements 119 (FIG. 4B) having a plurality of left twist blades 117 are alternately arranged up and down is used. The mixing elements 115 and 119 are a combination of a plurality of (for example, six) right-handed blades 113 or left-handed blades 117 each having a large number of holes 111 and partitioned into six raw water passages. While the raw water and nitrogen gas pass through the plurality of mixing elements 115 and 119, the right and left rotations and divisions, merging, reversing, and shearing are continuously performed by the right twist blade 113 and the left twist blade 117. Repetitively, the dissolved oxygen in the raw water is transferred into the nitrogen gas by contacting, stirring and mixing with the nitrogen gas which passes through the holes 111 perforated through the blades 113 and 117 and becomes fine bubbles and rises in the raw water. Further, the raw water becomes fine water droplets by the large number of holes 111, the right twist blade 113, and the left twist blade 117, so that the contact area with the nitrogen gas is remarkably increased. Moreover, the movement distance of oxygen in water becomes short because a water droplet becomes small. Thereby, deoxygenation can be performed in a short time with a small amount of nitrogen gas.

  Moreover, since the said reactor can be selected according to the amount of circulating water instead of the amount of treated water, the thing of the existing existing size can be used.

  Note that the gas-liquid contact portion 41 is not limited to a static mixer in which two mixing elements 115 and 119 are arranged, and an arbitrary number of one, three, four, and the like are arranged. It may be a structure.

  As shown in FIG. 5, in the upper part of the deoxygenation tower 43, a first ejector 121 communicating with the raw water supply pipe 45, an overflow tank 123 for receiving raw water supplied via the first ejector 121, and the gas-liquid A gas-liquid separation plate 125 provided in a floating floor shape with a predetermined buffer space 124 from the upper surface of the contact portion 41 is provided.

  The first ejector 121 communicates with the raw water supply port of the raw water supply pipe 45, and removes the raw water and the nitrogen gas supplied from the raw water supply pipe 45 above the gas-liquid contact portion 41 of the deoxygenation tower 43. It comes to be in liquid contact.

  More specifically, the first ejector 121 has a thin raw water flow path formed therein, and the raw water flow path increases the flow rate of the raw water from the raw water supply pipe 45 to depressurize the internal space and fill the surroundings. Nitrogen gas is sucked. As a result, the raw water from the raw water supply pipe 45 and nitrogen gas are brought into gas-liquid contact for deoxidation treatment.

  By doing in this way, before removing the dissolved oxygen from the raw water by the gas-liquid contact part 41, the concentration of the dissolved oxygen of the raw water can be effectively reduced by the first ejector 121. Therefore, when the raw water supplied by the raw water supply pipe 45 and the raw water introduced by the reflux pipe 53 are mixed above the gas-liquid contact portion 41 of the deoxygenation tower 43, the concentration of dissolved oxygen is excessively increased. Can be prevented. Moreover, since the ejector is used, the concentration of dissolved oxygen in the raw water can be effectively reduced even when the flow rate of the raw water is small.

  The overflow tank 123 is disposed on the gas-liquid separation plate 125 and receives raw water sprayed from the first ejector 121. As described above, the overflow tank 123 is provided, and the raw water sprayed from the first ejector 121 is received and temporarily stored, so that the raw water is temporarily mixed from the temporarily stored raw water by the first ejector 121. Nitrogen gas in fine bubbles combined with dissolved oxygen can be extracted. In this manner, in the overflow tank 123, fine bubble nitrogen gas (including oxygen) can be separated from the raw water.

  The gas-liquid separation plate 125 is formed with a through hole 125 a through which raw water overflowing from the upper opening edge of the overflow tank 123 flows down to the gas-liquid contact portion 41 below. Further, the gas-liquid separation plate 125 is provided with a nitrogen gas flow channel pipe 125b which is a flow channel of nitrogen gas rising from below. The nitrogen gas passage pipe 125b extends from the upper opening edge of the overflow tank 123 to a position higher than the upper opening edge of the overflow tank 123 so that the overflowing raw water does not pass.

  The raw water supplied from the raw water supply pipe 45 is deoxygenated by the first ejector 121, and once gas-liquid separated by the gas-liquid separation plate 125, and then circulated between the storage tank 49 and the gas-liquid contact part 41. Merge with water. More specifically, the gas-liquid separation plate 125 is formed in a disk shape having the same diameter as the inner diameter of the deoxygenation tower 43. The diameter of the through-hole 125a is adjusted around the nitrogen gas passage pipe 125b so that water is temporarily stored on the gas-liquid separation plate 125 at a predetermined depth, for example, 50 mm, according to the amount of raw water. In addition, a predetermined number (two in the drawing) is provided, and a temporary storage portion 126 for temporarily storing water is formed on the gas-liquid separation plate 125. That is, the temporary storage unit 126 includes a gas-liquid separation plate 125, a through hole 125a, an inner surface of the deoxygenation tower 43, and the like. Then, after further separating the fine bubble nitrogen gas mixed in the raw water and combined with the dissolved oxygen in the raw water, the raw water from which the nitrogen gas has been released is sequentially flowed down to the lower buffer space 124 through the through hole 125a. It has a structure. As a result, the raw water whose fine bubble nitrogen gas (including oxygen) is separated and the dissolved oxygen concentration is reduced to some extent can be supplied to the gas-liquid contact portion 41 in the buffer space 124.

  FIG. 6 shows experimental data after a lapse of 5 minutes from the start of flowing raw water and nitrogen gas through the apparatus simultaneously.

In the figure, a measurement result of the process water flow meter 77 of the treated water flow rate (m 3 ^{/ h)} "processing water" indicating a measurement result of the circulating water flow meter 81 of the circulating water flow rate (m 3 ^{/ h)} “Circulation water amount” indicating the nitrogen gas flow meter 75, “nitrogen flow rate” indicating the nitrogen gas flow rate (m ³ / h), “water temperature” indicating the raw water temperature (° C.), DO value of the raw water "Before treatment" indicating (mg / l), "After treatment" indicating the DO value (mg / l) of treated water, "Gas-liquid ratio" indicating the amount of nitrogen relative to the amount of treated water, "Ejector" indicating presence or absence of an ejector “Presence / absence” and “gas-liquid separation presence / absence” indicating the presence / absence of the gas-liquid separation plate 125 are shown.

In the figure, the data when the “treatment water amount” is 0.3 (m ³ / h) and the data when it is 0.5 (m ³ / h) are roughly shown.

  From the experimental data, it was found that the removal rate of dissolved oxygen increases when the flow rate of circulating water is increased. Also, the removal rate of dissolved oxygen is higher when the first ejector 121 and the gas-liquid separation plate 125 are provided, and the ratio of treated water / circulated water (circulation ratio) is about 0.1 (1:10). It was found that the DO value of treated water can be reduced to about 0.5.

  In this way, a part of the raw water stored in the storage tank 49 is introduced and refluxed above the gas-liquid contact portion 41 of the deoxygenation tower 43, so that the raw water is recirculated from the storage tank 49 and the gas. Since it can be circulated between the liquid contact parts 41 and the frequency of gas-liquid contact can be improved, the concentration of dissolved oxygen in the raw water can be efficiently reduced, and raw water with a very low concentration of dissolved oxygen can be treated. Can be obtained as Moreover, even if the structure is simplified, for example, by reducing the number of reactor stages, sufficient dissolved oxygen removal performance can be ensured, so that the apparatus can be reduced in size, and the equipment cost and running cost of the apparatus can be reduced. Can be suppressed. Moreover, since this apparatus can be reduced in size, it can be applied to applications where the flow rate of supplied raw water is small.

  In this way, in the water heat source air conditioning system, dissolved oxygen in the cooling water of the cooling water circulation system that is an open system and dissolved oxygen in the cold water of the cooling water circulation system that is a closed system can be effectively removed. Corrosion of piping is prevented.

  In addition, a second ejector having the same configuration as the first ejector 121 is provided in the deoxygenation tower 43 so as to communicate with the inlet of the reflux pipe 53, and the gas-liquid contact of the deoxygenation tower 43 is performed by the reflux pipe 53. The reflux water introduced above the portion 41 may be brought into gas-liquid contact with the nitrogen gas. By doing in this way, the density | concentration of the dissolved oxygen in the liquid introduce | transduced by the above-mentioned reflux path with the said 2nd ejector can further be reduced. Further, since the ejector is used, the concentration of dissolved oxygen in the liquid can be effectively reduced even when the flow rate of the liquid introduced through the reflux path is small.

  Further, a shower nozzle or the like may be employed instead of the above-described ejector. Even if the supply amount of the raw water is smaller than the circulation amount of the circulating water, the gas-liquid ratio can be as high as about 0.5 to 1 in the raw water treatment unit. Even regular packing with high pressure loss can be used. Furthermore, dissolved oxygen can be removed even with a simple gas-liquid contact system such as an injector or Raschig ring.

  The present invention can be used for, for example, boiler water supply, drinking water production, food production, semiconductor ultrapure water production or various test research applications for removing dissolved oxygen in a liquid, and a large-scale system. The present invention can be suitably applied not only to the case of use in a small system but also to the case of use in a small system.

It is a figure which shows one Example of the dissolved oxygen removal apparatus of this invention. It is a figure which shows the structure of a dissolved oxygen removal apparatus. It is a figure which shows a nitrogen gas supply apparatus. It is a figure which shows a mixing element. It is a figure which shows the upper part of a deoxygenation tower. It is a figure which shows experimental data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dissolved oxygen removal apparatus 3 Air conditioner 11 Gas pipe 13 Compressor 15 Heat exchanger 17 Expander 21 Cooling water piping 23 Cooling tower 25 Piping on-off valve 27 Cooling tower side circulation pump 33 Air conditioning machine side cold / hot water piping 35 Air conditioning side open / close Valve 37 Air-conditioner side circulation pump 41 Gas-liquid contact part 43 Deoxygenation tower 45 Raw water supply pipe 46 Nitrogen gas supply device 47 Nitrogen gas supply pipe 49 Reservoir 49a Water surface space 51 Outlet pipe 51a Branch pipe 53 Reflux pipe 54 Water feed pump 55 Exhaust pipe 67 Drain pipe 69 Drain pipe on / off valve 71 Supply pipe on / off valve 73 Gas pipe on / off valve 75 Nitrogen gas flow meter 76 Outlet pipe on / off valve 77 Treated water flow meter 78 Check valve 79 Recirculation pipe on / off valve 81 Circulating water flow meter 83 Branch pipe opening / closing valve 85 DO sensor 101 First adsorption tower 103 Second adsorption tower 111 Hole 113 Right twist blade 115 Mixing element 117 left twisting vanes 119 mixing element 121 first ejector 123 overflow tank 124 buffer space 125 gas-liquid separator plate 125a through hole 125b of nitrogen gas passage pipes 126 temporary storage unit

Claims (5)

A deoxygenation tower having a gas-liquid contact portion for removing the dissolved oxygen in the liquid by bringing the liquid to be treated and an inert gas into gas-liquid contact;
A liquid supply path for supplying the liquid above the gas-liquid contact portion of the deoxygenation tower;
An inert gas supply path for supplying the inert gas downward from the gas-liquid contact portion of the deoxygenation tower;
A storage tank for storing the liquid in gas-liquid contact with the inert gas by the gas-liquid contact portion of the deoxygenation tower;
A lead-out path for leading a part of the liquid stored in the storage tank to the outside as a processing liquid;
A reflux path for introducing a part of the liquid stored in the storage tank above the gas-liquid contact part of the deoxygenation tower to reflux ;
The ratio between the flow rate of the liquid introduced above the gas-liquid contact portion of the deoxygenation tower by the reflux path and the flow rate of the liquid led to the outside by the lead-out path or the flow rate of the liquid supplied by the liquid supply path A device for removing dissolved oxygen in a liquid, comprising: a flow rate control unit that controls the amount of dissolved oxygen in the liquid led out by the lead-out pipe . The device for removing dissolved oxygen in a liquid according to claim 1, wherein the lead-out path and the reflux path are branched downstream of a delivery pump for delivering the treated liquid from the storage tank . A first ejector communicating with the liquid supply path;
3. The dissolved oxygen in the liquid according to claim 1, wherein the first ejector causes the liquid supplied above the gas-liquid contact portion of the deoxygenation tower to gas-liquid contact with the inert gas through the liquid supply path. Removal device. A second ejector communicating with the reflux path;
The said 2nd ejector makes the liquid introduced above the gas-liquid contact part of the said deoxidation tower by the said reflux path, and the said inert gas, and gas-liquid contact as described in any one of Claims 1-3 Equipment for removing dissolved oxygen in liquids. The liquid is supplied from the liquid supply path above the gas-liquid contact part of the deoxygenation tower having a gas-liquid contact part that removes dissolved oxygen in the liquid by bringing the liquid to be treated and the inert gas into gas-liquid contact. ,
Supply the inert gas below the gas-liquid contact portion of the deoxygenation tower,
The liquid in gas-liquid contact with the inert gas by the gas-liquid contact part of the deoxygenation tower is stored in a predetermined storage tank,
A part of the liquid stored in the storage tank is led out from the lead-out path as a processing liquid,
A part of the liquid stored in the storage tank is introduced above the gas-liquid contact part of the deoxidation tower to be refluxed ,
The ratio of the flow rate of the liquid introduced above the gas-liquid contact part of the deoxygenation tower by the reflux and the flow rate of the liquid led out to the outside by the lead-out path or the flow rate of the liquid supplied by the liquid feed path, dissolved oxygen removal method in a liquid, characterized that you controlled by flow control means in accordance with the amount of dissolved oxygen in the liquid derived by the derivation tube.

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