JP5972805B2 - Nitrogen deoxygenation equipment - Google Patents

Description

  The present invention relates to a nitrogen-type deoxygenation apparatus that removes dissolved oxygen in raw water supplied to a boiler or the like in advance by contact with nitrogen gas.

  In the field of water treatment such as boiler water supply, deoxygenation treatment is performed to prevent corrosion of boilers and piping caused by dissolved oxygen in water, and one method is nitrogen. As described in Patent Document 1, the nitrogen-type deoxygenation device removes dissolved oxygen in raw water by bringing the raw water into contact with nitrogen gas. There are various contact methods between raw water and nitrogen gas, and in Patent Document 1, a counter-flow type treatment tower in which a gas-liquid contact tube is connected to a water tank is used.

  A typical configuration of a conventional nitrogen-type deoxygenation apparatus using a counter-flow type treatment tower will be described with reference to FIG. 2 for a boiler water deoxygenation apparatus described in Patent Document 1. FIG. The deoxygenation apparatus shown in FIG. 2 has a two-column structure in which two counter-flow type treatment towers 1A and 1B are connected in parallel. In each treatment tower, the flowing raw water and rising nitrogen gas are in countercurrent contact. The counter-flow type gas-liquid contact cylinder 2 to be constructed is erected on the water tank 3.

  Raw water to be deoxidized flows from a raw water tank (not shown) through a boiler pump into the gas-liquid contact cylinder 2 of the first treatment tower 1A from the upper part, descends the inside thereof, and flows into the lower water tank 3. The raw water in the water tank 3 of the first treatment tower 1A flows from the upper part into the gas-liquid contact tube 2 of the second treatment tower 1B by the circulation pump 5, descends the inside thereof, and flows into the lower water tank 3. On the other hand, the nitrogen gas is operated in the water tank 3 of the second processing tower 1B by operating the rotary blade type self-priming diffuser 6 provided below the water surface in the water tank 3 of the first processing tower 1A. After being introduced into the space above the water surface and passing through the upper gas-liquid contact cylinder 2 from the bottom to the top, the self-priming diffuser 6 is passed through the raw water in the water tank 3 of the first treatment tower 1A. Diffusion injection is performed, and further, the raw water passes through the gas-liquid contact tube 2 of the first treatment tower 1A from the bottom to the top, and is discharged from the upper part of the gas-liquid contact tube 2 to the outside.

  Thus, the raw water is subjected to countercurrent contact with the nitrogen gas twice at two locations in the gas-liquid contact cylinder 2 of the first treatment tower 1A and in the gas-liquid contact cylinder 2 of the second treatment tower 1B. The amount of dissolved oxygen is effectively reduced and discharged as treated water from the water tank 3 of the second treatment tower 1B by the drainage pump 7. In the gas-liquid contact cylinders 2 of both towers, a filler 4 is loaded in order to increase the contact efficiency between raw water and nitrogen gas. Moreover, the self-priming diffuser 6 provided below the water surface in the water tank 3 of the first treatment tower 1A discharges nitrogen gas into the raw water in the water tank 3 in a fine bubble state and comes into contact with the raw water. In addition, the contact efficiency between the raw water and the nitrogen gas is increased by stirring the raw water.

  However, such a two-column nitrogen-type deoxygenation apparatus can obtain high deoxygenation performance by using a small amount of nitrogen gas, but requires a large apparatus and is expensive. On the other hand, a nitrogen-type deoxygenation apparatus having a single tower structure is simple in structure and low in cost, but is inferior in deoxidation performance. As means for enhancing the deoxygenation performance, a configuration in which the raw water in the water tank is circulated in the gas-liquid contact cylinder thereabove is generally adopted in order to obtain the same function as the two-column structure (see Patent Document 2). However, under the situation where the amount of nitrogen gas used is limited, it is not possible to expect a deoxygenation performance improvement effect that approaches a two-column structure.

  This is because when raw water is circulated in the gas-liquid contact cylinder, the amount of raw water in the gas-liquid contact cylinder increases and the gas-liquid ratio decreases. That is, in the gas-liquid contact cylinder, the deoxygenation performance tends to increase as the gas-liquid ratio, which is the volume ratio of the nitrogen gas amount to the raw water amount, increases, but under the situation where the amount of nitrogen gas used is limited, When raw water is circulated in the gas-liquid contact cylinder, the amount of raw water increases and the gas-liquid ratio decreases, so that the deoxygenation performance as expected cannot be obtained. Of course, if the amount of nitrogen gas used is increased, the deoxygenation performance will increase, but an increase in running cost due to an increase in the amount of nitrogen gas used cannot be avoided.

  In addition to the nitrogen gas type, there is a thin film type deoxygenation device. Thin film deoxygenation devices are small and inexpensive, but their deoxygenation performance is inherently low, making it difficult to meet recent high demand levels. Incidentally, the oxygen concentration in the treated water after deoxygenation treatment is expressed as an OD value, and the limit is 0.5 in the case of a thin film type, and in the case of a nitrogen type, the oxygen concentration decreases to 0.2 or less (water temperature) Is 20 ° C.).

JP 2005-95791 A JP 2006-263641 A

  The object of the present invention is a one-column structure, and even in a state where the amount of nitrogen gas used is limited, it is economical that it can surpass the thin film type and exhibit the deoxygenation performance approaching the two-column structure. The object is to provide a high-performance nitrogen deoxygenation device.

  In order to achieve the above object, the present inventor considers that a multi-faceted approach is necessary in order to improve the performance of a single-column nitrogen gas deoxygenation apparatus, and is diligent about various constituent requirements. Repeated examination. The first thing to focus on is the means for supplying nitrogen gas into the deoxidizer, and the second is the positional relationship between the gas-liquid contact cylinder and the water tank. The results of these studies are as follows.

  In a nitrogen gas deoxygenation device having a single-column structure that combines a gas-liquid contact cylinder and a water tank, raw water is introduced into the cylinder from the upper part of the gas-liquid contact cylinder, passes through the packing material in the tower, and enters the lower water tank. Inflow. On the other hand, nitrogen gas is injected into the water tank, ascends in the upper gas-liquid contact cylinder, makes countercurrent contact with the raw water flowing down the cylinder, and is discharged out of the cylinder from the upper part of the cylinder.

  The nitrogen gas here is effective to diffuse and mix nitrogen gas in the raw water in the water tank in a bubble state, and is a rotary blade type self-priming diffuser adopted in the deoxygenation device described in Patent Document 1. Is one of the effective means and has high performance. By diffusing and injecting nitrogen gas into the raw water in the water tank, the raw water introduced into the cylinder from the top of the gas-liquid contact cylinder is desorbed by making countercurrent contact with the nitrogen gas in the packing layer in the tower. The oxygen primary treatment is received, and in the water tank, a deoxygenation secondary treatment is performed by nitrogen gas injected into the raw water.

  However, this self-priming diffuser is expensive. Therefore, the present inventor paid attention to an ejector as an inexpensive means for injecting nitrogen gas. The ejector sucks the gas by the negative pressure generated when the liquid passes through the inside at high speed, and ejects the gas at high speed in a gas-liquid mixed state. Since the structure is simple and inexpensive, a large amount of gas can be sucked even at a low price. Capability can be secured.

More specifically, a gas suction amount of 100 L / min can be secured with a liquid flow rate of 10 tons / hour. When the raw water supply amount to the gas-liquid contact cylinder is 5 tons / hour (5 m ³ / hour), the ideal gas-liquid ratio in the gas-liquid contact cylinder is around 0.3, so the amount of fresh nitrogen gas Requires 1.5 m ³ / hour (25 L / min), resulting in a surplus capacity of 75 L / min. If the raw water in the water tank is circulated to the ejector and the used nitrogen gas in the water tank is reused by surplus capacity, a large amount of raw water of 10 tons / hour repeatedly contacts with a large amount of nitrogen gas of 100 L / min in the ejector. In addition to the primary deoxygenation treatment in the gas-liquid contact cylinder, the raw water undergoes an effective deoxygenation secondary treatment in the water tank.

  Incidentally, although the used nitrogen gas in the water tank is used for the deoxygenation secondary treatment in the raw water in the water tank, the oxygen concentration is sufficiently low at about 0.2%. This nitrogen gas having a low oxygen concentration is naturally used for the primary deoxidation treatment in the gas-liquid contact cylinder. Even after being used for the primary deoxidation treatment in the gas-liquid contact cylinder, the oxygen concentration in the nitrogen gas is about 2%.

  Thus, by using an ejector as a means for mixing nitrogen gas into the raw water in the aquarium, a very high deoxygenation capacity is exhibited even in a situation where the amount of nitrogen gas is limited by a single-column deoxygenation device. Will be.

  Further, as described above, when the capacity of the ejector is larger than the supply amount of nitrogen gas, for example, when the former is 100 L / min and the latter is 25 L / min, the return path from the space above the raw water surface in the aquarium to the ejector is established. By providing, nitrogen gas of 75 L / min is returned from the water tank to the ejector, and the remaining 25 L / min flows into the gas-liquid contact cylinder. That is, in order to circulate and reuse the nitrogen gas corresponding to the surplus capacity of the ejector, it is effective to provide a nitrogen gas reflux path from the space above the raw water surface in the water tank to the ejector.

  Next, regarding the positional relationship between the gas-liquid contact cylinder and the water tank, when the lower end of the gas-liquid contact cylinder is connected to the top plate of the water tank, it is extended below the top plate and into the raw water in the tank. It may be immersed (see FIG. 2 of Patent Document 1 and part 3 of Patent Document 2). When immersing the lower end of the gas-liquid contact tube in the raw water in the water tank, in order to introduce nitrogen gas from the water tank into the gas-liquid contact cylinder, at a place in contact with the space above the raw water surface in the water tank A nitrogen gas inlet is provided.

  When the ejector is employed as a means for supplying nitrogen gas into the raw water in the water tank, as described above, the specific gravity that the deoxygenation secondary treatment in the raw water in the water tank is tightened increases. When the lower end of the gas-liquid contact cylinder is connected to the ceiling of the aquarium, the raw water that has flowed down the gas-liquid contact cylinder and finished the deoxidation primary treatment, i.e., the primary treated water, falls to the raw water surface in the aquarium. The tendency to be discharged out of the tank without receiving the deoxygenation secondary treatment in the raw water is increased. In particular, when the secondary treatment unit in the water tank is partitioned by a weir, the raw water in the secondary treatment unit that has finished the secondary treatment, that is, the treated water is overflowed from the weir, and when it is discharged outside the tank through the receiving part, Most of the primary treated water gets over the weir and cannot receive the secondary treatment, resulting in a significant reduction in treatment efficiency.

  For this reason, when an efficient deoxygenation secondary treatment is performed in the raw water in the aquarium by the ejector, the lower end of the gas-liquid contact tube is placed in the raw water in the aquarium in order to efficiently receive the secondary treatment. It is better to immerse deeply. If the lower end of the gas-liquid contact tube is immersed in the raw water in the water tank, there will be no jump from the surface of the raw water, and there is no risk of the raw water jumping up into the tube of the nitrogen gas reflux path described above. System function is stable.

  The nitrogen-type deoxygenation apparatus of the present invention has been completed on the basis of such knowledge, and a counterflow type gas-liquid contact cylinder in which counterflow contact is made between the raw water flowing down and the rising nitrogen gas is erected independently on the water tank. As a means for supplying nitrogen gas into the deoxygenation apparatus, a nitrogen-type deoxygenation apparatus having a single tower structure connected to the raw water in the water tank and sucking nitrogen gas by circulating the raw water Ejector is equipped.

  In the nitrogen-type deoxygenation apparatus of the present invention, raw water is introduced into the cylinder from the upper part of the gas-liquid contact cylinder, passes through the tower, and flows into the lower water tank. On the other hand, nitrogen gas is sucked by circulating the raw water to the ejector installed in the raw water in the tank and injected into the raw water in the tank. The inside of the contact cylinder rises and is discharged out of the cylinder from the top of the cylinder. Thus, the raw water introduced into the gas-liquid contact cylinder is subjected to deoxidation primary treatment by countercurrent contact with the nitrogen gas rising in the tower in the process of flowing down the cylinder, and the ejector in the water tank and its ejector It receives deoxidation secondary treatment by contacting with nitrogen gas in the vicinity. As described above, the deoxygenation secondary treatment by the ejector in the water tank effectively contributes to the reduction of the oxygen concentration in the treated water.

And as said ejector , select the thing of the capacity | capacitance by which the nitrogen gas inhalable amount by this becomes more than the nitrogen gas required quantity in a gas-liquid contact cylinder, Preferably the thing of about 3 to 10 times the capacity is selected, and surplus capacity As a result, nitrogen gas staying in the space above the raw water surface in the water tank is sucked. For this purpose, a nitrogen gas recirculation path from the space above the raw water surface in the water tank to the ejector is provided. This structure further improves the efficiency of secondary oxygen removal treatment by the ejector in the water tank.

  About a gas-liquid contact cylinder, it is desirable to connect with a water tank so that the lower part may be immersed in the raw water in a water tank. This further improves the efficiency of the secondary oxygen removal treatment by the ejector in the water tank, as described above. In this case, it is desirable to adopt a configuration in which the inside of the water tank is divided into a secondary treatment part and a receiving part by a weir, and the secondary treated water overflowing from the weir is discharged outside the tank through the receiving part. As raw water to be circulated to the ejector, it is desirable to use the secondary treated water in the receiving part or the final treated water discharged from the receiving part.

The nitrogen-type deoxygenation apparatus of the present invention is a one-column structure deoxygenation apparatus in which a counter-flow type gas-liquid contact cylinder in which counterflowing raw water and rising nitrogen gas are in countercurrent contact is singly installed on a water tank. As a means for supplying nitrogen gas into the deoxygenation device, an ejector that sucks nitrogen gas by circulating raw water in the water tank , in particular, the amount of nitrogen gas that can be sucked by this is larger than the required amount of nitrogen gas in the gas-liquid contact cylinder By using an ejector with the ability to be used, even in a state where the amount of nitrogen gas used is limited, it can surpass the thin film type and exhibit the deoxygenation performance constrained by the two-column deoxygenation device, It is very effective in reducing the size and cost of the deoxygenation device.

It is a block diagram of the nitrogen-type deoxygenation apparatus which shows one Embodiment of this invention. It is a block diagram of the deoxygenation apparatus of the 2 tower structure which is the conventional high performance nitrogen type deoxygenation apparatus.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  When supplying raw water in a raw water tank to a boiler that is a raw water consuming unit, the nitrogen type deoxygenation apparatus of this embodiment desorbs the raw water by mixing with nitrogen gas from a nitrogen source for the purpose of preventing the corrosion of the boiler. For this purpose, oxygen treatment is carried out, and the water supply system from the raw water tank to the boiler is interposed.

  As shown in FIG. 1, the nitrogen-type deoxygenation apparatus has a configuration in which a cylindrical counter-current contact type gas-liquid contact cylinder 10 is vertically installed on a water tank 20. By bringing the raw water flowing down into the water tank 20 into contact with the nitrogen gas injected into the raw water 30 in the water tank 20 and rising in the gas-liquid contact cylinder 10 in the gas-liquid contact cylinder 10 and the water tank 20. Then, a two-stage deoxidation treatment of the raw water 30 is performed.

  For this deoxygenation two-stage treatment, a dispersion plate 11 and a filler 12 are loaded in two stages inside the gas-liquid contact cylinder 10 which is a primary treatment section. The filler 12 increases the contact efficiency between the nitrogen gas that is a gas and the raw water that is a liquid, and is composed of an assembly of line structure pieces called Raschig super rings, and the piece is above the middle part in the cylinder, By filling over a predetermined height, the contact area of nitrogen gas and raw water is increased.

  The upper end surface of the gas-liquid contact cylinder 10 is closed leaving a used nitrogen gas outlet. A raw water introduction system 90 for introducing raw water into the cylinder is connected to the upper peripheral surface of the gas-liquid contact cylinder 10 so as to be positioned above the dispersion plate 11. A flow rate control valve 91 is interposed in the raw water introduction system 90.

  On the other hand, below the middle part of the gas-liquid contact cylinder 10, it penetrates the top plate of the water tank 20 and is inserted deeply into the vicinity of the bottom surface in the tank, and is fixed to the top plate of the water tank 20 in this state. Is fixed to the tank bottom by a support member (not shown). Thereby, the lower part of the gas-liquid contact cylinder 10 is deeply immersed in the raw water 30 in the water tank 20.

  The lower end surface of the gas-liquid contact cylinder 10 is fully opened for discharging the raw water 30. Further, in order to introduce the nitrogen gas injected into the raw water 30 in the water tank 20 into the gas-liquid contact cylinder 10, the gas-liquid contact cylinder 10 is in contact with the space above the water surface in the water tank 20 and nitrogen. A gas inlet 13 is provided.

  On the other hand, the inside of the water tank 20 is partitioned by a secondary processing unit 21 that is located immediately below the gas-liquid contact tube 10 and collects raw water flowing from the gas-liquid contact tube 10 and a weir-shaped partition wall 22 on the side thereof. It consists of the receiving part 23 formed. The receiving part 23 temporarily stores the treated water that has finished the secondary treatment in the secondary treatment part 21 and overflowed the partition wall 22. A water supply system 40 including a water supply pump 41 and a flow rate control valve 42 is connected to the receiving portion 23 in order to take the treated water out of the tank and send it to the boiler.

  An ejector 50 is installed in the secondary processing unit 21 in the water tank 20 for the purpose of injecting nitrogen gas into the raw water 30 in the secondary processing unit 21. The ejector 50 is connected to a raw water circulation system 60 branched from between a water supply pump 41 and a flow rate control valve 42 of the water supply system 40 and a nitrogen gas introduction system 70. A nitrogen gas recirculation system 80 is installed between the water tank 20 and the nitrogen gas introduction system 70 in order to recirculate nitrogen gas from the space above the water surface in the water tank 20 to the ejector 50.

  Then, by driving the water pump 41 that also serves as a circulation pump, the raw water that has undergone the deoxygenation secondary treatment in the water tank 20, that is, the treated water is supplied to and passed through the ejector 50, and nitrogen gas is introduced accordingly. Nitrogen gas is drawn into the ejector 50 from the system 70 and the nitrogen gas reflux system 80. As a result, from the ejector 50, nitrogen gas becomes fine bubbles and is jetted into the raw water 30 in the secondary processing unit 21 at a high speed together with the treated water.

  In order to control the flow rates of the raw water 30 and the nitrogen gas, flow control valves 61, 71 and 81 are provided in the raw water circulation system 60, the nitrogen gas introduction system 70 and the nitrogen gas recirculation system 80, respectively. In addition, a level meter 24 is provided in the receiving portion 23 in the water tank 20 for water level management.

  Next, operation | movement, a function, and effect of the nitrogen type deoxygenation apparatus of this embodiment are demonstrated. The preconditions are as follows.

The amount of raw water that must be treated is 5 tons / hour. Therefore, 5 tons / hour of raw water 30 is injected from the raw water introduction system 90 into the gas-liquid contact cylinder 10 from the top. The gas-liquid ratio in the gas-liquid contact cylinder 10 is set to an ideal 0.3. As a result, the supply amount of fresh nitrogen gas is required to be 1.5 m ³ / hour (25 L / min). Here, the gas suction capacity of the ejector 50 is set to 100 L / min, which is four times the required amount in the gas-liquid contact cylinder 10, and the necessary circulating amount of the raw water 30 to the ejector 50 is 10 tons / hour. .

  First, the flow of the raw water 30 will be described. The raw water 30 to be processed is injected from the raw water introduction system 90 into the gas-liquid contact cylinder 10 from the top. The raw water 30 injected into the uppermost part in the cylinder flows down in the cylinder, passes through the dispersion plate 11 and the filler 12 in the cylinder, and flows into and accumulates in the secondary treatment unit 21 in the water tank 10. When the secondary processing unit 21 is filled with the raw water 30, the secondary processing unit 21 flows over the weir-shaped partition wall 22 into the adjacent receiving unit 23. The raw water 30 in the receiving portion 23 is discharged outside the tank by the water supply system 40, and a part of the raw water 30 is sent to the boiler, and the rest is returned from the middle of the water supply system 40 to the water tank 20 through the raw water circulation system 60. More specifically, it is sent to the ejector 50 in the receiving portion 23.

  In order to manage the water surface level in the receiving part 23 to an appropriate value, the water level in the receiving part 23 is measured by the level meter 24, and the flow control valve 42 in the water supply system 40 is adjusted so that it becomes an appropriate level. The opening degree is controlled.

  On the other hand, the nitrogen gas is sucked into the ejector 50 by the negative pressure accompanying the flow of the raw water 30 to the ejector 50, and is mixed with the raw water 30, that is, becomes fine bubbles in the secondary treatment unit 21 in the water tank 20. It is ejected into the raw water 30. A part of the nitrogen gas ejected into the raw water 30 in the secondary treatment unit 21 is used for the deoxygenation treatment of the raw water 30, and the rest is nitrogen in the gas-liquid contact cylinder 10 through the space above the water surface of the water tank 20. The gas flows from the gas inlet 13 into the cylinder, passes through the filler 12 and the dispersion plate 11 in the cylinder, and is discharged out of the cylinder from the discharge port on the upper end surface.

  As a result, the raw water 30 introduced from the upper end into the gas-liquid contact tube 10 is subjected to the following deoxygenation treatment in the gas-liquid contact tube 10 and the water tank 20.

  In the process of passing through the gas-liquid contact cylinder 10, particularly in the process of passing through the filler 12, the dissolved oxygen is dissolved along with the dissolution of the nitrogen gas by making countercurrent contact with the rising nitrogen gas in the gas-liquid contact cylinder 10. Is subjected to deoxygenation treatment. This is the deoxidation primary treatment. The nitrogen gas used for this deoxygenation primary treatment is after being used for the deoxygenation treatment in the secondary treatment section 21 of the water tank 20, but the oxygen content is as low as about 0.2%. . The amount of nitrogen gas discharged from the gas-liquid contact cylinder 10 is the amount (25 L / min) newly supplied from the nitrogen gas introduction system 70 to the ejector 50, and the raw water 30 to the gas-liquid contact cylinder 10 is supplied. Therefore, the gas-liquid ratio in the gas-liquid contact cylinder 10 is maintained at an ideal 0.3.

  The raw water 30 that has undergone the primary deoxygenation treatment in the gas-liquid contact cylinder 10 flows into a deep position of the secondary treatment section 21 of the water tank 20 and undergoes deoxygenation treatment with nitrogen gas ejected from the ejector 50. In particular, since this nitrogen gas is ejected from the ejector 50 at a high speed together with the raw water stream, the raw water 30 is strongly stirred. Moreover, the amount of nitrogen gas is 100 L / min, four times the amount of nitrogen gas newly introduced into the system (25 L / min). Of this, 25 L / min flows into the gas-liquid contact cylinder 10, but the remaining 75 L / min is returned to the nitrogen gas introduction system 70 via the nitrogen gas recirculation system 80.

  In this way, the raw water 30 that has undergone multiple deoxygenation treatments in the secondary treatment unit 21 of the water tank 20, that is, the treated water, flows over the weir-shaped partition wall 22 into the adjacent receiving part 23, and outside the tank in the water supply system 40. To be discharged. At this time, 10 tons / hour of treated water corresponding to twice the amount of raw water introduced into the system (5 tons / hour) passes between the feed pump 41 and the flow control valve 42 through the raw water circulation system 60. And sent to the ejector 50. That is, the amount of raw water introduced into the system is 5 tons / hour, but the treated water discharged from the secondary treatment section 21 through the receiving section 23 to the outside of the water tank 10 is 15 tons / hour. 10 ton / hour is circulated to the ejector 50.

  As a result, the raw water 30 that has been subjected to the primary deoxidation treatment in the gas-liquid contact cylinder 10 is repeatedly received by the secondary treatment unit 21 of the water tank 20 and subjected to the deoxidation secondary treatment using nitrogen gas from the ejector 50. Moreover, the raw water 30 is subjected to a strong mixing action with stirring with nitrogen gas even in the ejector 50.

  That is, the deoxygenation secondary treatment in the secondary treatment unit 21 of the water tank 20 includes deoxygenation treatment by fine bubbles of nitrogen gas from the ejector 50 and high-speed water flow, and mixing of nitrogen gas and raw water 30 in the ejector 50. This is a triple multi-process comprising a deoxygenation process by stirring and a repetition of these by circulating the raw water 30 to the ejector 50. Therefore, even though this deoxygenation apparatus has a single-column structure, it exhibits excellent deoxygenation performance that is tight to a two-column structure deoxygenation apparatus.

  In numerical terms, when the temperature of the raw water 30 introduced into the gas-liquid contact cylinder 10 of this deoxygenation device is 20 ° C. and the amount of oxygen in the raw water is 8.8 in OD value, the gas-liquid contact cylinder 10 to the water tank It is about 1.1 at the stage of flowing into the 20 secondary processing units 21, and is about 0.3 at the stage of being discharged from the deoxygenation apparatus. The oxygen concentration in the nitrogen gas is 0.2% in the process of finishing the deoxygenation process in the secondary treatment unit 21 of the water tank 10 and introducing it into the gas-liquid contact cylinder 10, and the upper end of the gas-liquid contact cylinder 10. Is about 2% at the stage of being discharged out of the cylinder.

  This is a performance close to the two-column nitrogen gas deoxygenation apparatus shown in FIG. Incidentally, in the case of the nitrogen gas type deoxygenation device having a two-column structure shown in FIG. 2, if the specifications and conditions such as the scale of the gas-liquid contact cylinder, the raw water treatment amount, the nitrogen gas usage amount, etc. are the same, The density is about 0.2 in terms of OD value. However, the equipment cost is about twice that of the present deoxygenation device. In the case of a thin film type deoxygenator, the oxygen concentration of treated water is limited to 0.5 in terms of OD value. The equipment cost of this deoxygenation apparatus with respect to this is almost the same.

DESCRIPTION OF SYMBOLS 10 Gas-liquid contact cylinder 11 Dispersing plate 12 Filler 13 Nitrogen gas inlet 20 Water tank 21 Secondary processing part 22 Weir-shaped partition (weir)
23 Receiver 24 Level meter 30 Raw water 40 Water supply system 41 Water supply pump 42 Flow control valve 50 Ejector 60 Raw water circulation system (raw water circulation path)
61 Flow control valve 70 Nitrogen gas introduction system 71 Flow control valve 80 Nitrogen gas recirculation system (nitrogen gas circulation path)
81 Flow control valve 90 Raw water introduction system 91 Flow control valve

Claims (5)

A one-column nitrogen-type deoxygenation device in which a counter-flow type gas-liquid contact tube in which counterflowing raw water and rising nitrogen gas are in countercurrent contact with each other is erected on a water tank, and nitrogen is introduced into the deoxygenation device As a means for supplying gas, an ejector for sucking nitrogen gas by circulating the raw water in the raw water in the water tank is provided, and the ejector has an amount of nitrogen gas that can be sucked in the gas-liquid contact cylinder. Nitrogen deoxygenation device that is larger than the nitrogen gas requirement . The nitrogen type deoxygenation apparatus according to claim 1 , comprising a nitrogen gas recirculation path for recirculating nitrogen gas from a space above the raw water surface in the water tank to the ejector. The nitrogen-type deoxygenation apparatus according to claim 1 or 2 , wherein the gas-liquid contact cylinder is connected to the water tank so that a lower part thereof is immersed in the raw water in the water tank. 4. The nitrogen-type deoxygenation apparatus according to claim 3 , wherein the water tank is divided by a weir into a secondary treatment part immediately below the gas-liquid contact cylinder and a receiving part into which the secondary treated water overflowing the weir flows. Type oxygen absorber. The nitrogen-type deoxygenation device according to claim 4 , wherein the raw water circulation path to the ejector is configured to circulate secondary treated water in the receiving part or treated water discharged from the receiving part to the ejector. Type oxygen absorber.

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