JP3198614B2 - Degassing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for dissolving CO in water.
_2, O ₂ relates degasser to remove efficiently, or to remove the CO _2, O ₂ of the city water to produce treated ultrapure water RO system before and after the two-stage (the membrane separator) At this time, an object is to remove CO ₂ and O ₂ in the raw water supplied to the RO device and improve the quality of ultrapure water treated by the RO device.

[0002]

Conventionally, the CO 2 removal unit for removing the water of dissolved gas CO _2, for the removal of O ₂ N ₂ degassing device is generally used. The decarbonation device sprays water to be treated from above on the packing layer provided in the treatment tower, and blows air from below to this layer with a blower to bring counter-current contact between the water to be treated and air in the packing layer. And remove the CO ₂ in the water by air.
In addition, the N ₂ degassing device sprays the water to be treated from the top onto the filler layer provided in the treatment tower, and supplies high-purity N ₂ from the bottom to the bed.
The gas is supplied, the water to be treated and the N ₂ gas are brought into countercurrent contact in the filler layer, and mainly O ₂ in the water is removed by the N ₂ gas.

[0003]

In the above-described conventional decarbonation apparatus, air of 15 times or more of the supply flow rate of the water to be treated is blown to remove CO ₂ , but CO ₂ existing in the blown air is removed. _{Due to} the effect of _2, there is a limit to the CO ₂ concentration that can be reached in the treated water. In particular, CO ₂ has a low diffusion rate from water,
With the current equipment, the CO ₂ concentration of the treated water is ₂ to 8 ppmas
It is limited to CO ₂ , and it cannot be made lower. Further, since air is blown, O ₂ dissolved in the water to be treated cannot be removed. Since N ₂ degassing equipment uses high-purity N ₂ gas, it is possible to simultaneously remove O ₂ and CO ₂ in water, but the diffusion rate of CO ₂ from water is lower than that of O _2. very low, because it is about 1/27, the CO ₂ concentration in the treated water to the same level as the case of the CO 2 removal unit is required a large amount of N ₂ gas, since the increase running costs, N ₂ gas It is used mainly for removing O ₂ . Therefore, in order to remove CO ₂ and O ₂ dissolved in water, at present, a
A N ₂ degassing device is also used.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been developed to efficiently remove CO ₂ and O _{2 in} water with a single processing tower. In a degassing device provided with a water supply device for spraying water to be treated from above on the filler layer and a nitrogen gas supply device for supplying nitrogen gas from below, a blower for blowing air in the middle of the filler layer Is provided.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the illustrated embodiment, 1 is a vertical treatment tower,
2 is a filler layer provided in the tower, 3 is a water supply device for spraying water to be treated on the filler layer from above, and 4 is an air supply device for supplying nitrogen gas to the filler layer from below. Is set up on a treated water tank 5 for receiving treated water flowing downward in the filler layer.

In the embodiment shown in FIG. 1, the top of the processing tower 1 and a blower 6 outside the tower, for example, an intake port of a blower 6 are connected to an extraction pipe 7.
, And the exhaust port of the blower and the middle of the height of the processing tower are connected by an air supply pipe 8. Therefore, when the blower 6 is operated, the gas containing nitrogen gas blown from the bottom into the top of the filler layer 2 is sucked into the blower by the extraction pipe 7, and the blower sends the gas to the filler layer 2 through the air supply pipe 8. Blowing in the middle of the height, thus circulating the gas. still,
An exhaust port 9 is provided in the blower air supply port or in the middle of the air supply pipe 8, and the same amount of nitrogen gas supplied into the processing tower is discharged out of the system through the exhaust port to reduce the amount of circulating gas.保 つ Keep constant.

When the water to be treated is sprayed on the filler layer 2 from above with the water supply device 3 and the nitrogen gas is supplied from below with the air supply device 4 while operating the blower 6, In the lower portion 2a of the lower filler layer 2, the water to be treated flowing downward in the filler layer and the nitrogen gas flowing upward in the layer come into countercurrent contact with each other, and O ₂ and CO _{2 in the} water to be treated become countercurrent. , Mainly O ₂
Is removed. In the upper part 2b of the filler layer above the connection position of the air supply pipe 8, the nitrogen gas blown up from the lower part 2a of the layer and the gas supplied from the air supply pipe 8 by the blower flow upward together. The gas-liquid contacting efficiency is improved by the amount of the gas flowing upward, which is in countercurrent contact with the water to be treated, which is countercurrent.
O ₂ and O ₂ (mainly CO ₂ ) are removed well.

In the embodiment shown in FIG. 2, the exhaust port of the blower 6 provided outside the processing tower and the middle of the height of the processing tower are connected by an air supply pipe 8, and the air outside the tower is connected to the blower 6 and the air supply pipe 8. As a result, the gas blown in the middle of the height of the filler layer 2 and the gas blown through the filler layer 2 from below to above is discharged to the atmosphere through an exhaust pipe 10 provided at the top of the tower. In this embodiment, mainly O ₂ in the water to be treated is efficiently removed in the lower portion 2b of the filler layer below the connection position of the air supply pipe, and mainly CO ₂ in the water to be treated is efficiently removed in the upper portion 2a of the layer. To be removed.

In both of the embodiments shown in FIGS. 1 and 2, the height of the upper layer 2a of the filler layer is about 1.5 to 2 m, and the height of the lower layer 2b is about 3 to 3 depending on the guaranteed value of O ₂ removal. 8m.

City water of city A [25 ° C., pH = 4.0 (H ₂
SO ₄ added) at a rate of 1 m ³ / hour as water to be treated,
The results obtained in the case where the treatment is performed sequentially with the conventional decarbonation device and the N ₂ degassing device and in the case where the treatment is performed with the device in FIG. 1 are shown below. Conventional method (Decarbonation equipment → N ₂ degassing equipment) Operating condition of decarbonating equipment: Air flow rate = 15 Nm ³ / hour Operating condition of N ₂ degassing apparatus: N ₂ gas amount = 1 Nm ³ / hour Treated water CO ₂ concentration = 2 0.0 ppmasCO ₂ O ₂ concentration = 5 ppmasO Device of the present invention Operating conditions: Air flow rate = 15 Nm ³ / hour N gas amount = 1 Nm ³ / hour Treated water CO ₂ concentration = 0.1 ppmasCO ₂ O ₂ concentration = 1 ppmasO By using the same energy for blowing and using the same amount of N ₂ gas, the present invention was able to reduce the CO ₂ concentration of the treated water to 1/20 and the O ₂ concentration to 1/5. .

Further, when ultrapure water is processed by a two-stage RO apparatus to produce CO2, CO ₂ has been conventionally removed from the raw water by a decarbonation apparatus. However, CO2 cannot be removed by a decarbonation apparatus. Step R
The specific resistance of the water quality of the water produced by the O device is 0.5 MΩ · Cm
On the order, principal of CO ₂ remaining in the ultrapure water produced, but must kicked such removed by regenerative ion exchanger, the regenerative ion exchanger is a resin separation, complicated operations such as reproduction Then, trouble occurred. However, when the degassing apparatus of the present invention is used, the C in the raw water to be treated by the two-stage RO apparatus is reduced.
Since O ₂ can be removed 20 times as much as a decarbonation device, the specific resistance of the water quality of the ultrapure water produced by the two-stage RO device is 5.5 MΩ · Cm.
By using a non-regenerative non-regenerative ion exchange apparatus that is not a regenerative type, ultrapure water having a TOC of 10 ppb or less can be stably obtained (see FIG. 3).

[0012]

The factors for efficiently removing O ₂ and CO ₂ dissolved in water are a reduction in the partial pressure difference in the gas phase and an improvement in the gas-liquid contact efficiency. In the present invention, pure nitrogen gas is supplied from below to the lower portion 2a of the filler layer to allow O ₂ and C from the liquid phase.
O ₂ is removed, and in the upper part 2a of the filler layer, the lower part 2b
The gas and liquid contact efficiency is increased by flowing upward a large amount of a mixed gas in which the nitrogen gas blown from the gas and the circulating gas blown from the middle of the height of the filler layer or the air are mixed, and the water to be treated is It mainly removes CO ₂ . In particular, in the upper part 2a of the filler layer, the (≒ O) N ₂ gas having a low CO ₂ partial pressure is mixed with the circulating gas to lower the CO ₂ partial pressure in the circulating gas and to improve the gas-liquid contact efficiency. Thereby, CO ₂ is sufficiently removed from the liquid. In the lower portion 2b, CO2 removed in the upper portion is used.
₂ is removed (polished) by being brought into contact with N ₂ gas having a lower partial pressure, and CO ₂ and O ₂ can be removed below.

For this reason, when the conventional decarbonation apparatus and the N ₂ deaerator are used in combination, when the operation is performed with the same amount of blowing air and the same amount of N ₂ gas used as described above, the CO ₂ removal amount becomes 20 as described above. And the amount of O ₂ removal increases by a factor of five, and the removal efficiency is significantly improved. Also, if the CO ₂ concentration and the O ₂ concentration of the treated water are set to the same level as when the conventional decarbonation device and the N ₂ degassing device are used in combination, the energy consumption for blowing air and the N ₂ gas The running cost can be reduced to about half since the amount of used is small.

Furthermore, when used together, _two towers, a processing tower for a decarbonation apparatus and a processing tower for an N ₂ degassing apparatus, were required. However, in the present invention, only one processing tower is required, so that the equipment cost is reduced by half. I do.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a flow sheet in which the degassing apparatus of the present invention is incorporated in an ultrapure water production apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Treatment tower 2 Packing material layer 3 Water supply device of treated water 4 Nitrogen gas supply device 5 Treatment water tank 6 Blower 8 Blower tube

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1/20 B01D 19/00

Claims (1)

(57) [Claims] 1. A degassing system comprising a water supply device for spraying water to be treated from above on a filler layer and a nitrogen gas supply device for supplying nitrogen gas from below in a treatment tower containing a filler layer. What is claimed is: 1. A degassing device, comprising: a gas device provided with a blowing device for blowing air in the middle of the filler layer.