JPH0785793B2 - Device for removing dissolved oxygen in liquid - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for removing oxygen dissolved in a liquid such as natural water or pure water by using nitrogen gas, and more particularly to a vacuum degassing apparatus. The present invention relates to a device for removing dissolved oxygen in a liquid by using a closed liquid storage tank which is capable of minimizing the consumption of nitrogen gas while eliminating the need for large-scale equipment such as a gas device. .

[Conventional technology]

Conventionally, a vacuum deaerator has been used as a method for removing dissolved oxygen gas in a liquid. The equipment is mainly composed of a vacuum degassing tower, a lower storage tank and a vacuum pump.The vacuum degassing tower has a sprinkling pipe arranged in the upper part of the tower and a filling provided below the sprinkling pipe. The stock solution, which is composed of layers, is dispersed by the sprinkling tube and the packing to enhance the gas-liquid contact effect, and the surface area is increased. Then, the gas in the tower is sucked and exhausted from the top of the vacuum degassing tower by a vacuum pump, and the inside of the aeration tower is in a vacuum state of about 10 to 60 Torr.

When the stock solution in the tower in a vacuum state is supplied, oxygen gas dissolved in the stock solution is separated from the stock solution together with nitrogen gas and carbon dioxide gas, and sucked by a vacuum pump from the top of the vacuum degassing tower, It is emitted into the atmosphere from the outlet of the vacuum pump.

On the other hand, the degassed liquid separated from the gas body flows down into a storage tank installed at the bottom of the vacuum degassing tower and is stored there. The degassed liquid stored in the storage tank is sent to another storage tank or various destinations by a liquid sending pump.

FIG. 2 is an explanatory diagram showing a flow of the conventional equipment,
The stock solution supplied from the inflow pipe 1 into the vacuum degassing tower 2 is dispersed in the sprinkling pipe 3, flows down the packed bed 4, and is stored in the lower storage tank 5.

At this time, since the inside of the degassing tower 2 has been evacuated to a vacuum state of 60 Torr or less by the vacuum pump 6, the undiluted solution that has entered the tower 2 is separated into oxygen gas and other gas bodies and the degassed solution. To be done. Then, the gas body is transferred from the gas suction pipe 7 to the vacuum pump 6
Is sucked into the atmosphere and diffused into the atmosphere through the gas discharge pipe 8.

The degassed liquid stored in the storage tank 5 enters the degassing liquid pump 10 through the degassing liquid pump inflow pipe 9, and is sent from the liquid sending pipe 11 to another storage tank or a destination.

Incidentally, recently, as a mechanical means for removing dissolved oxygen in the water, nitrogen gas is continuously supplied from the lower part of a large open storage tank that stores the water, and nitrogen gas bubbles are brought into contact with the water, A device for removing dissolved oxygen in water has been proposed.

[Problems to be solved by the invention]

The conventional vacuum deaerator is as described above, but a vacuum pump and its exhaust equipment are required to maintain a vacuum state of 60 Torr or less in the vacuum deaerator at the same time. Due to the internal structure of the tower, there is a problem that the tower height is considerably high, about 3 m. In addition, the storage tank must be at least 3m higher than the pump in order to obtain the required suction head of the degassed liquid pump. Therefore, the general vacuum degassing tower and the storage tank will be a plant of about 10 m above the ground due to the relationship with the piping, and the construction and equipment costs will increase, and maintenance and inspection will also require a great deal of trouble. there were.

In addition, in a device that removes dissolved oxygen in water by continuously supplying nitrogen gas from the bottom of a large open storage tank that stores water, nitrogen gas must always be released from the bottom of the tank. However, since nitrogen gas is continuously diffused into the atmosphere, there is a problem that the running cost is high, and since the storage tank in this device is a so-called batch type, it must be a large storage tank. However, there is a problem that the equipment cost increases and the installation place becomes difficult. Further, this conventional proposed device has a problem that the contact efficiency between nitrogen gas and water is poor and the time required for deaeration becomes considerably longer than that of the vacuum deaeration method.

The present invention solves the problems associated with the conventional device described above, enables efficient removal of dissolved oxygen without using large-scale equipment such as a vacuum degassing device, and oxygen gas is more nitrogen. It is an object of the present invention to provide a dissolved oxygen removing device capable of suppressing the consumption of nitrogen gas to a minimum by paying attention to the fact that the specific gravity is larger than that of gas.

[Means for solving problems]

To explain the present invention in detail, a liquid storage tank having a liquid inflow pipe and a liquid outflow pipe respectively attached thereto, a liquid level control device for controlling the liquid level of the deoxidizing liquid changing in the liquid storage tank, and the liquid A device for supplying nitrogen gas to the upper part of the storage tank, a sprinkler pipe arranged at an upper position in the liquid storage tank so as to communicate with the liquid inflow pipe, and a device below the mounting position of the sprinkler pipe. And an air collecting pipe disposed above the high level liquid level set by the liquid level control device, and a water sealer attached to the air collecting pipe via a gas discharge pipe. And a device for removing dissolved oxygen in a liquid.

Hereinafter, a specific configuration of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory view showing an example of an embodiment of the device of the present invention, in which 20 denotes a liquid storage tank provided with a liquid inflow pipe 21 and a liquid outflow pipe 22, respectively.

Reference numeral 23 is a liquid level control device that electrically controls the change in the liquid level that moves up and down as the deoxidizing liquid stored in the liquid storage tank 20 is repeatedly consumed and replenished. It is preset so that the flow rate of the stock solution flowing from the liquid inflow pipe 21 is larger than the flow rate of the liquid. For example, when the liquid level is lowered to the low level H shown in the figure, replenishment is started, Replenishment is automatically stopped at the high level HH.

Further, LL shown in the figure indicates a pull-out prevention point of the deoxygenating liquid pump 32, which will be described later, and L indicates a starting return point of the pump 32.

Reference numeral 24 denotes a nitrogen gas supply device, which supplies nitrogen gas from the nitrogen gas source 25 to the upper inside of the storage tank 20 via the nitrogen gas supply pipe 26, and the nitrogen gas supply pipe 26 has a pressure reducing valve. I have inserted 27.

The liquid storage tank 20 is connected to the liquid inflow pipe 21.
29 is a sprinkling pipe installed in the upper position of the inside.
The air collecting pipe is arranged below the pipe position 28 and above the liquid level of the high level HH set by the liquid level control device 23. It is preferable that a large number of air collection holes are formed in the air collection pipe 29 so as to face downward, that is, to face the liquid surface side.

Reference numeral 30 denotes a water sealer attached to the air collection pipe 29 via a gas discharge pipe 31 on the outside of the liquid storage tank 20, and 32 denotes a deoxidizer pump inserted in the liquid outflow pipe 22.

[Work]

The nitrogen gas sent from the nitrogen gas supply device 24 is filled in the liquid storage tank 20 in a state where the pressure is controlled by the pressure reducing valve 27 and the water sealer 30.

The undiluted solution sent from the liquid inflow pipe 21 into the liquid storage tank 20 is
Dispersed by the sprinkling pipe 28, the contact surface area with the nitrogen gas becomes large, and the oxygen gas in the stock solution and the nitrogen gas in the liquid storage tank 20 can be efficiently exchanged. The supply pressure of the nitrogen gas into the liquid storage tank 20 is determined by the relationship with the pressure strength of the liquid storage tank 20 and therefore need not be particularly limited, but is usually the liquid storage tank 20.
Since the withstand pressure of ± 500 mmAq is used, the pressure is set to 500 mmAq or less, but since there is a pressure control relationship with the water sealer 30, it is preferable to set it to about 150 to 200 mmAq.

The liquid level of the deoxidized liquid falling into the storage tank 20 while being dispersed by the sprinkling pipe 28 rises in proportion to the supply amount, but the pressure in the liquid storage tank 20 also rises as the liquid level rises. When the pressure in the storage tank is equal to or higher than the preset pressure, the oxygen gas exchanged with the nitrogen gas enters the air collection pipe 29 through the air collection hole formed in the collector pipe 29, and the gas discharge pipe 31 Through the water sealer 30 into the atmosphere.

Since nitrogen gas and oxygen gas have a larger specific gravity, oxygen gas mainly enters from the air collection pipe 29 and overcomes the head pressure of the water sealing water in the water sealing device 30 to release the oxygen gas atmosphere. The inside of the liquid storage tank 20 is constantly evacuated and is kept in a nitrogen atmosphere.

On the other hand, when the deoxidizing liquid pump 32 is operated, the deoxidizing liquid in the liquid storage tank 20 is sent from the liquid outflow pipe 22 to each destination.
The liquid level in the liquid storage tank 20 decreases. The nitrogen gas whose pressure is reduced to about 150 mmAq as the liquid level is lowered is sent from the supply device 24 into the liquid storage tank 20.

When the liquid level is lowered and reaches the set position of the undiluted liquid supply, for example, the position of the low level H shown in the figure, the liquid level control device 23 is activated and the undiluted liquid starts to be supplied from the liquid inflow pipe 21 into the liquid storage tank 20. It gradually rises.

Since the gas portion in the liquid storage tank 20 is almost 100% nitrogen gas, the partial pressure of the nitrogen is also 100%.
The dissolved oxygen gas in the stock solution dispersed from is efficiently replaced with nitrogen gas in the liquid storage tank 20, and exists in the gas portion above the liquid surface in the liquid storage tank 20. Then, when the pressure in the liquid storage tank 20 becomes higher than the water head set in the water sealer 30 with the rise of the liquid level, the gas mainly containing oxygen gas flows through the collector pipe 29 and the gas discharge pipe 31 as described above. It is emitted to the atmosphere from the water sealer 30 via.

As described above, according to the device of the present invention, the dissolved oxygen in the undiluted solution is continuously removed to the outside of the storage tank efficiently in response to the change of the liquid level in the liquid storage tank. It can be applied to all uses requiring removal of oxygen gas other than pure water.

[Effect]

As described above, according to the device of the present invention, oxygen dissolved in the liquid can be efficiently and continuously removed without using large-scale equipment such as a vacuum degassing device.

Further, since the piping position of the air collecting pipe is below the mounting position of the sprinkling pipe and above the high level liquid level set by the liquid level control device, the nitrogen gas is discharged as oxygen gas is discharged. The amount of gas discharged from the liquid storage tank is extremely small,
It has a great effect that the consumption of nitrogen gas can be greatly reduced.

Examples will be described below in order to clarify the effects of the present invention.

〔Example〕

The present invention was carried out on pure water based on the flow shown in FIG.

Liquid storage tank: Diameter 1200mm Vertical body height 2120mm Water seal: Water head 300mm Nitrogen gas pressure reducing valve: Reduce pressure from 2kgf / cm ² to 150mmAq Nitrogen supply capacity: 1.5m ³ / h Deoxidizing liquid pump capacity: 1m ³ / h liquid Control range of surface controller: The position 100 mm below the bottom of the air collection tube is set to a high level (HH), and the pure water supply is stopped at HH.

The low level (H) that starts the supply of pure water is set 300 mm below the high level (HH).

Sprinkler / Air collector: Both are 20A PVC pipes with small holes.

Using the above apparatus, pure water at 20 ° C. was supplied from the pure water inflow pipe to the storage tank at a rate of 1.2 m ³ per hour. At this time, the dissolved oxygen concentration in pure water was 8 mgO /.

In the pure water supply, the inside of the storage tank was in a nitrogen atmosphere by sending nitrogen gas from a nitrogen gas supply device.
The pure water was finely dispersed by the sprinkling pipe, and the gas mainly composed of oxygen gas in the storage tank continued to be diffused into the atmosphere from the water sealer through the air collecting pipe and the gas discharging pipe due to the rise of the water level.

The water level rises further and the high level HH set by the liquid level controller
When the position was reached, the supply of pure water was stopped and the discharge of gas from the water sealer was stopped at the same time.

Next, the deoxygenated water pump was operated to send pure water out of the pure water outflow pipe at a rate of 1 m ³ per hour to lower the water level in the storage tank. As the water level decreased, the nitrogen gas reduced in pressure from the nitrogen gas supply device to 150 mmAq by the pressure reducing valve flowed into the storage tank.

When the water level drops to the low level H set by the liquid level control device, the electric signal at this time causes pure water to be supplied again from the inflow pipe into the storage tank, and the water level rises, and at the same time, the gas in the storage tank, that is, nitrogen. Oxygen gas released from the gas and pure water began to be discharged into the atmosphere from the water sealer via the air collection pipe and the gas discharge pipe.

The dissolved oxygen concentration in pure water in the storage tank, that is, in the pure water from the deoxygenated water outflow pipe, was 0.3 mgO /, which was obtained by repeatedly raising and lowering the water level and supplying and stopping pure water. From this,
It has become clear how effective the deoxidizing gas capacity of the device of the present invention is.

The analysis of dissolved oxygen used in this example was based on JIS K0101.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a flow showing an example of an embodiment of the device of the present invention, and FIG. 2 is an explanatory diagram of the flow of a conventional device. 20: Liquid storage tank, 21: Liquid inflow pipe 22: Liquid outflow pipe, 23: Liquid level control device 24: Nitrogen gas supply device, 25: Nitrogen gas source 26: Nitrogen gas supply pipe, 27: Pressure reducing valve 28: Dispersion pipe , 29: Air collection pipe 30: Water seal device, 31: Gas discharge pipe

Claims (1)

[Claims] 1. A sealed liquid storage tank provided with a liquid inflow pipe and a liquid outflow pipe respectively, a liquid level control device for controlling the liquid level of the deoxidizing liquid changing in the liquid storage tank, and a liquid storage device in the liquid storage tank. A device for supplying nitrogen gas to the upper part, a sprinkling pipe arranged at an upper position in the liquid storage tank so as to communicate with the liquid inflow pipe, and a position below the mounting position of the sprinkling pipe and A liquid comprising an air collecting pipe arranged above a high level liquid level set by a liquid level control device, and a water sealer attached to the air collecting pipe via a gas discharge pipe. Device for removing dissolved oxygen in the inside.