JP2016159292A - Deoxygenation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deoxygenation device 1 which removes dissolved oxygen in treatment water by injecting nitrogen gas into the treatment water and has improved deoxygenation efficiency.SOLUTION: In a deoxygenation device 1, raw water containing dissolved oxygen is supplied from a raw water inlet 2 provided at one end of a passage and deoxygenated water from which dissolved oxygen has been removed is taken out from a deoxygenated water taking out port 3 at the other end of the passage. Nitrogen gas injection nozzles 5 for injecting nitrogen gas are installed in the middle of the passage of treatment water connecting the raw water inlet 2 and the deoxygenated water taking out port 3 to each other. The nitrogen gas is injected into the treatment water flowing through the deoxygenation device to remove dissolved oxygen in the treatment water. A plurality of passage expansion parts 7 having a large cross sectional area and a plurality of passage narrowing parts 8 having a small cross sectional area are alternately installed in a deoxygenation part 6 of the treatment water passage on the downstream side of the nitrogen gas injection nozzle.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a nitrogen substitution type deoxygenation apparatus in which nitrogen gas is injected into raw water in which oxygen is dissolved and dissolved oxygen is removed by replacing oxygen in the raw water with nitrogen.

As described in Japanese Patent Laid-Open No. 2001-129304, when raw water in which oxygen is dissolved is supplied as it is in boiler feed water or the like, corrosion with a metal material that comes into contact with water such as piping is promoted. A deoxygenation process in which water is supplied after removing dissolved oxygen is widely performed.

As one of the methods for deoxygenation, there is a method using a nitrogen substitution type deoxygenator. The partial pressure of the gas dissolved in the raw water varies depending on the partial pressure of the gas in contact with the raw water. When nitrogen gas is injected into water in which nitrogen and oxygen are dissolved to generate countless bubbles by nitrogen gas, the bubble portion by nitrogen gas and the liquid portion in which nitrogen and oxygen are dissolved at a certain ratio come into contact with each other. become. In this case, nitrogen is dissolved from the nitrogen bubbles into the treated water, and nitrogen and oxygen are released from the treated water into the bubbles, and finally the partial pressures of nitrogen and oxygen are the same. . That is, the amount of dissolved oxygen in the water is reduced by releasing oxygen from the raw water containing oxygen into the bubbles of nitrogen gas having a low oxygen partial pressure.

In a nitrogen substitution type deoxygenation device, it is important how nitrogen and oxygen are exchanged, that is, whether nitrogen is dissolved in the treated water and oxygen is released from the treated water. Even if nitrogen gas is injected, oxygen in the treated water remains if the amount of nitrogen gas dissolved in the treated water is small. In the invention described in Japanese Patent Laid-Open No. 2001-129304, mixing is performed by a static mixer that turbulently mixes treated water into which nitrogen gas has been injected. A static mixer is one that repeats dividing the water flow of the treated water by a mixer provided in the flow path and turbulently mixes the treated water. Become. By mixing nitrogen gas and treated water, the dissolution of nitrogen gas into the treated water can be promoted, but a sufficient deoxygenation effect cannot be obtained simply by installing a static mixer. In the invention of Kaikai 2001-129304, a plurality of static mixers are arranged in series, and gas-liquid separation means is further provided.

JP 2001-129304 A

  The problem to be solved by the present invention is to provide a deoxygenation device that improves the efficiency of deoxygenation in a deoxygenation device that removes dissolved oxygen in the treated water by injecting nitrogen gas into the treated water. .

According to the first aspect of the present invention, raw water containing dissolved oxygen is supplied from a raw water inlet provided at one end of the flow path, and deoxygenated water from which dissolved oxygen has been removed is taken out from a deoxygenated water outlet at the other end of the flow path. The deoxygenation device is configured to have a nitrogen gas injection nozzle for injecting nitrogen gas in the middle of the treated water flow path connecting between the raw water inlet and the deoxygenated water outlet, and flows in the deoxygenation device. In the deoxygenation apparatus in which nitrogen gas is injected into the treated water and the dissolved oxygen in the treated water is removed, in the deoxygenated portion downstream of the nitrogen gas injection nozzle of the treated water flow path, the flow path of the treated water flow path The present invention is characterized in that a plurality of channel expansion portions having a large cross-sectional area and a channel reduction portion having a small channel area are alternately provided.

The invention described in claim 2 is characterized in that, in the deoxygenation apparatus, the nitrogen gas injection nozzle is installed above the deoxygenation part, and the treated water flows downward in the deoxygenation part.

  According to a third aspect of the present invention, in the deoxygenation device, when the nitrogen gas injection nozzle is installed below the deoxygenation part and the treated water flows upward in the deoxygenation part, By forming the lower part into a shape projecting from the upper part of the flow path expanding part, a bubble pool is provided in the upper part of the flow path expanding part.

By carrying out the present invention, in addition to the stirring and mixing effect of nitrogen gas and treated water, the dissolution and separation of the gas are repeatedly performed by increasing and decreasing the gas solubility due to the change in water pressure. Dissolution and separation of the oxygen content from the treated water are promoted, and the release efficiency of dissolved oxygen from the treated water is improved.

Sectional drawing in the first embodiment of the present invention 1 is an enlarged cross-sectional view of a part of FIG. Sectional drawing in the second embodiment of the present invention 2 is an enlarged cross-sectional view of a part of FIG. Sectional drawing in the third embodiment of the present invention

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view for explaining the configuration of a deoxygenation apparatus in a first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of a part of FIG. In the deoxygenating apparatus 1 of FIG. 1, raw water is supplied from one end and deoxygenated water is taken out from the other end. A continuous flow is provided between the raw water inlet 2 and the deoxygenated water outlet 3. Connected by road. The raw water inlet 2 is the upper part of the apparatus, and the deoxygenated water outlet 3 is the lower part of the apparatus. The deoxygenation apparatus is small and compact, but the flow path of the treated water is long. , Meandering in the order of the downward flow path. In the embodiment of FIG. 1, the downward flow path portion becomes the deoxygenation unit 6. Nitrogen gas injection nozzles 5 are respectively installed in portions close to the upper ends of the two downward flow paths installed, and nitrogen gas is injected from the nitrogen gas injection nozzles 5 provided at the upper ends of the downward flow paths. Do. In the downward flow path portion, a plurality of flow path reduction sections 8 having a reduced tube diameter and a plurality of flow path expansion sections 7 having a large pipe diameter are alternately provided. The expansion and contraction of the flow path can be made by using a reducer in which one end of the tube is drawn, a different diameter socket having a different diameter, or the like.

When nitrogen gas is injected into the treated water from the two nitrogen gas injection nozzles 5, numerous bubbles are generated by nitrogen in the treated water, and the treated water flows downward in the deoxidation section 6. Bubbles also flow downward on the treated water flow. Even if the treated water and the bubbles are in contact with each other, dissolution of the gas component from the bubbles to the treated water and release of the gaseous component from the treated water to the bubbles are performed. In this case, the gas component dissolved from the bubbles into the treated water is substantially nitrogen, and the gas components released from the treated water into the bubbles are mainly nitrogen and oxygen. For this reason, the amount of oxygen in the treated water of the gas component decreases between the treated water and the bubbles. However, if the bubbles just flow with the treated water, the dissolved and released rates of the gas components are low, so that the dissolved oxygen cannot be sufficiently removed.

Therefore, in the present invention, the flow path in the deoxygenation section is alternately provided with the flow path reduction section 8 having a small pipe diameter and the flow path expansion section 7 having a large pipe diameter. In such a case, the treated water flowing through the deoxygenation unit repeats a decrease in the flow rate at the flow channel expansion unit 7 and an increase in the flow rate at the flow channel reduction unit 8. When the flow rate of the treated water is reduced at the flow path enlargement unit 7, the action of pushing down the bubbles is reduced. Since the bubbles themselves have a specific gravity lighter than that of water, a floating force is exerted in the water. Therefore, bubbles accumulate in the portion of the flow path expanding portion 7 where the force of pushing down the bubbles is weakened due to a decrease in the flow rate of the treated water.

This air bubble pool stops while repeating merging and splitting at the flow path expansion part, and the treated water flowing in contact with the stopped air bubbles comes into contact one after another, so the exchange of gas between the air bubbles and the treated water Efficiency is improved.

Further, when the flow path area in the deoxygenation section changes and the flow rate of the treated water flowing therethrough changes, stirring is performed each time, and this also improves the efficiency of oxygen removal.

Furthermore, the efficiency of the treated water flowing in the deoxidation part can also be improved by repeatedly increasing the pressure at the flow path reduction part 8 and decreasing the pressure at the flow path expansion part 7. In the portion where the pressure of the treated water is increased, the volume of bubbles due to the nitrogen gas is reduced, and the solubility is increased, so that the amount of nitrogen gas dissolved in the treated water is increased. On the contrary, in the part where the pressure of the treated water is reduced, the gas dissolved in the treated water is easily released from the treated water.

For this reason, when the flow path expanding section 7 and the flow path reducing section 8 are alternately installed, the gas component dissolves into the treated water and the gas component is released from the treated water more. Nitrogen and oxygen are dissolved in the treated water, and when nitrogen gas is blown into the treated water, the gaseous components released from the treated water into the bubbles are nitrogen and oxygen, but from the bubbles into the treated water. The gas component that enters is mainly nitrogen. Therefore, nitrogen, which is an inert gas, enters the treated water, and oxygen that causes corrosion is released from the treated water to the outside. In the deoxygenation part, the dissolution of nitrogen into the treated water and the release of oxygen from the treated water are repeated, and the amount of oxygen in the treated water decreases.

FIG. 3 is a cross-sectional view for explaining the configuration of the deoxygenation apparatus in the second embodiment of the present invention, and FIG. 4 is an enlarged cross-sectional view of a part of FIG. In the case of the second embodiment, raw water is supplied from one end and deoxygenated water is taken out from the other end, and a continuous flow path is provided between the raw water inlet 2 and the deoxygenated water outlet 3. The connection point is the same as in the first embodiment. However, the raw water inlet 2 is the lower part of the apparatus, the deoxygenated water outlet 4 is the upper part of the apparatus, and the first is that the flow path is meandering so as to be an upward flow path, a downward flow path, and an upward flow path. This example is different. In the second embodiment, the upward flow path portion becomes the deoxygenation unit 6.

In the case of the first embodiment, in the deoxygenation unit 6, the nitrogen gas bubbles are lighter in specific gravity than the treated water, so an upward force is exerted. However, since the flow of the treated water is downward, it is pushed to the treated water. Therefore, a downward force is also applied, and for this reason, the bubbles of nitrogen gas are supposed to stop at the flow path enlarged portion. However, when the treated water is flowed upward in the deoxygenation section, only the upward force is applied to the bubbles, so if the shape is the same as in the first embodiment, the nitrogen bubbles will flow immediately. In that case, the effect of deoxidation cannot be obtained so much. Therefore, in the second embodiment, the lower part of the flow path reducing part 8 is shaped so as to protrude above the flow path expanding part 7, and a bubble pool is provided on the upper part of the flow path expanding part 7.

Also in the second embodiment, since the treated water that is flowing in contact with the stationary bubbles is in contact with each other, the efficiency of gas exchange between the bubbles and the treated water is improved. And since the flow path in the deoxygenation part alternately installs the flow path reduction part 8 with a small pipe diameter and the flow path enlargement part 7 with a large pipe diameter, the treated water flowing through the deoxygenation part 6 Since the flow velocity decrease in the flow channel expansion unit 7 and the flow velocity increase in the flow channel reduction unit 8 are repeated and stirring is performed each time, the efficiency of oxygen removal is improved.

Furthermore, by repeatedly expanding and reducing the cross-sectional area of the treated water flow path, the amount of nitrogen gas dissolved in the treated water and the release of oxygen from the treated water are increased. This also promotes the replacement of gas between the treated water and the bubbles, and increases the effect of reducing the amount of oxygen in the treated water.

FIG. 5 is a cross-sectional view for explaining the structure of a deoxygenation apparatus in the third embodiment of the present invention. FIG. 5 shows a combination of the first embodiment and the second embodiment. In the downward flow path, the flow path enlargement portion 7 and the flow path reduction portion 8 in the structure described in the first embodiment are provided. In the upward channel portion, the channel expanding portion 7 and the channel reducing portion 8 having the structure described in the second embodiment are provided. In this case, deoxidation is performed in both the downward flow path and the upward flow path.

The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

1 Deoxygenation device
2 Raw water entrance
3 Deoxygenated water outlet 4 Processed water flow channel 5 Nitrogen gas injection nozzle 6 Deoxygenated portion 7 Flow channel enlarged portion 8 Flow channel reduced portion 9 Bubble pool

Claims (3)

A deoxygenation device that supplies raw water containing dissolved oxygen from a raw water inlet provided at one end of a flow path and takes out deoxygenated water from which dissolved oxygen has been removed from a deoxygenated water outlet at the other end of the flow path. Install a nitrogen gas injection nozzle that injects nitrogen gas in the middle of the treated water flow path connecting the raw water inlet and the deoxygenated water outlet, and injects nitrogen gas into the treated water flowing in the deoxidizer. In the deoxygenation apparatus configured to remove dissolved oxygen in the treated water, the deoxidized portion on the downstream side of the nitrogen gas injection nozzle of the treated water flow path includes a flow path expanding section having a large flow path cross-sectional area of the treated water flow path. A deoxygenation apparatus, wherein a plurality of flow path reduction portions having a small flow path area are alternately installed.   2. The deoxygenation apparatus according to claim 1, wherein the nitrogen gas injection nozzle is installed above the deoxygenation unit, and the treated water flows downward in the deoxygenation unit. 3. 2. The deoxygenation apparatus according to claim 1, wherein the nitrogen gas injection nozzle is installed below the deoxygenation part, and in the deoxygenation part, when the treated water flows upward, the lower part of the flow path reduction part is expanded in the flow path. The deoxygenation device is characterized in that a bubble pool is provided at the upper part of the flow path expanding part by projecting the upper part of the part.

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