JPH08318126A - Method for removing nox and device therefor - Google Patents

Abstract

PURPOSE: To increase the contact efficiency with gas and the efficiency in removing NOx by depositing water on the surface of a glass fiber, bringing an NOx- contg. gas into contact with the fiber and absorbing the NOx in the water causing no trouble in handling. CONSTITUTION: A glass fiber 17 is laminated into a cylindrical element which is used as a filter 6. Water is ejected on the filter 6 surface from a nozzle 7 to wet the filter. A gas (g) contg. NOx is introduced into a reaction vessel 4 from a gas inlet 2, hence the gas (g) enters to the filter 6 from the periphery of the filter 6, passes through the opening of a partition plate 5 and is discharged from a gas outlet 3. Meanwhile, the gas is brought into contact with the water deposited on the fiber 17 surface, and NOx are absorbed. The NOx are efficiently removed in this way. Besides, the filter 6 is formed by laminating the glass fiber 17 having 12μm diameter into a cylindrical element having 280kg/m<3> packing density and 70mm thickness and putting 24 elements one on another.

Description

Detailed Description of the Invention

[0001]

The present invention relates to, for example, a plating process,
The present invention relates to a method and apparatus for removing nitrogen oxides for removing nitrogen oxides contained in gas (waste gas) generated in processes such as pickling process and dissolution process.

[0002]

2. Description of the Related Art Conventionally, in the surface treatment technology for metals and the like, it is known that a gas containing nitrogen oxides (waste gas) is generated in a plating process, a pickling process, a melting process and the like. As a method of removing nitrogen oxides contained in this waste gas, a liquid containing a hydrogen peroxide solution and caustic soda is formed into a mist and sprayed into the waste gas,
There is a method of removing the nitrogen oxides from the waste gas by reacting the liquid with nitrogen oxides in the waste gas, and an apparatus to which this method is applied has also been proposed and put into practical use.

[0003]

However, in the conventional removal method, since a liquid containing hydrogen peroxide solution and caustic soda is used, caustic soda is a strong alkali, so that it must be handled with caution. , There was a problem in handling. Further, since the waste gas is brought into contact with the mist-like hydrogen peroxide solution and the caustic soda, there is a problem that the contact efficiency between the mist and the waste gas is poor and the removal efficiency of nitrogen oxides is poor. Therefore, JP-A-6-11423
A device and method for removing nitrogen oxides, as shown in No. 7, have been proposed. In this device, a partition plate for partitioning the interior of the reaction container into two chambers, upper and lower, is provided in a reaction container having a waste gas inlet port formed in the lower part and a waste gas discharge port in the upper part, and glass fibers are laminated on the partition plate. A filter in which a plurality of wound cylindrical filter elements are stacked is provided, and a plurality of nozzles for injecting hydrogen peroxide solution are provided on the surface of the filter in the reaction vessel, and the waste gas is hydrogen peroxide. While passing between the glass fibers that are wet with water,
By contacting this hydrogen peroxide solution, nitrogen oxides in the waste gas are removed.

By the way, in this apparatus, the nitrogen oxides in the waste gas are oxidized by the hydrogen peroxide solution and dissolve into the hydrogen peroxide solution to form nitric acid. This nitric acid contains a large amount of hydrogen peroxide. Since it cannot be used as it is, it is necessary to separate hydrogen peroxide from nitric acid. However, since hydrogen peroxide is extremely difficult to separate, hydrogen peroxide inevitably remains in nitric acid, and it is impossible to obtain near-pure nitric acid. There was a problem that it was difficult to reuse.

The present invention has been made in view of the above circumstances, and the liquid to be used has no problem in handling, and the contact efficiency with gas can be improved. Therefore, the nitrogen oxide in the gas can be improved. An object of the present invention is to provide a nitrogen oxide removing method and a nitrogen oxide removing apparatus capable of increasing the removal efficiency of nitrogen.

[0006]

In order to solve the above problems, the following method and apparatus for removing nitrogen oxides were adopted. That is, in the method for removing nitrogen oxides according to claim 1 of the present invention, after adhering water to the surface of the glass fiber, a gas containing nitrogen oxide is brought into contact with the glass fiber to remove the nitrogen oxide. It is a method of removing the nitrogen oxides from the gas by absorbing with water.

A method for removing nitrogen oxides according to claim 2 is
The water having absorbed the nitrogen oxides is again adhered to the surface of the glass fiber to further absorb the nitrogen oxides in the water,
A method of removing nitrogen oxides from the gas.

The nitrogen oxide removing apparatus according to claim 3 is
A reaction container provided with a gas inlet for introducing a gas containing nitrogen oxides and a gas outlet for discharging a gas obtained by removing nitrogen oxides from the gas, and the gas introduction provided in the reaction container. A filter that is interposed between the mouth and the gas discharge port and is formed by laminating glass fibers, a nozzle that injects water onto the surface of this filter, and water that has absorbed nitrogen oxides discharged from the reaction vessel. A water tank for storing the water, and a supply unit provided between the water tank and the nozzle for supplying water having absorbed the nitrogen oxides stored in the water tank to the nozzle.

The nitrogen oxide removing apparatus according to claim 4 is
A plurality of nitrogen oxide removing parts are arranged in series, and the nitrogen oxide removing part is a gas introduction port into which a gas containing nitrogen oxides is introduced and a gas from which a gas obtained by removing nitrogen oxides from the gas is discharged. A reaction vessel having an outlet, a filter provided in the reaction vessel and interposed between the gas inlet and the gas outlet, and a glass fiber laminated filter, and nitrogen on the surface of the filter. It comprises a nozzle for injecting water that absorbs oxides, and a water tank that stores water that has absorbed nitrogen oxides discharged from the reaction vessel, and each of the nitrogen oxide removing units removes nitrogen oxides on the preceding stage side. And a gas inlet of the nitrogen oxide removing section on the subsequent stage side adjacent to the gas outlet of the above section are connected to each other to form a plurality of stages.

A device for removing nitrogen oxides according to claim 5 is
A supply means is provided between the nozzle of the nitrogen oxide removing section and the water tank to supply the nozzle with water having absorbed the nitrogen oxides stored in the water tank.

The nitrogen oxide removing apparatus according to claim 6 is
A transfer means is provided between the plurality of water tanks to transfer the water, which has absorbed the nitrogen oxides stored in the water tank on the rear stage side, to the water tank on the front stage side.

The nitrogen oxide removing apparatus according to claim 7 is
The water tank is provided with a cooling means for cooling the water that has absorbed the nitrogen oxides.

[0013]

In the method for removing nitrogen oxides according to the first aspect of the present invention, after water is attached to the surface of the glass fiber, a gas containing nitrogen oxide is brought into contact with the glass fiber to remove the nitrogen oxide. By absorbing with water, the nitrogen oxides in the gas come into contact with water adhering to the surface of the glass fiber, are efficiently absorbed, and are efficiently removed from the gas. It is speculated that the nitrogen oxides are considered to be oxidized by active oxygen existing on the surface of the glass fiber and absorbed by the water to form nitric acid. As a result, the nitrogen oxide is oxidized without using an oxidizing agent.

In the method for removing nitrogen oxides according to the second aspect, the water having absorbed the nitrogen oxides is adhered again to the surface of the glass fiber, and then a gas containing nitrogen oxide is contacted with the glass fiber. The water further absorbs nitrogen oxides. Since the water (nitric acid) that has absorbed the nitrogen oxides further absorbs the nitrogen oxides, the water that has absorbed the nitrogen oxides becomes a high concentration nitric acid and is recovered as a high concentration nitric acid.

In the device for removing nitrogen oxides according to claim 3, water for absorbing the nitrogen oxides is jetted from the nozzle toward the surface of the filter, and enters between the glass fibers constituting the filter, The glass fiber is put in a wet state. In this state, when a gas containing nitrogen oxides is introduced into the reaction container through the gas inlet, the gas passes through the filter and is discharged out of the reaction container through the gas outlet.
When passing through the filter, the water efficiently contacts the water adhering between the glass fibers, and the nitrogen oxide in the gas is absorbed by the water. It is presumed that, in the present apparatus, the nitrogen oxides are oxidized by the active oxygen existing on the surface of the glass fiber and absorbed by the water to become nitric acid. As a result, the nitrogen oxide is oxidized without using an oxidizing agent.

In the nitrogen oxide removing apparatus according to the present invention, a plurality of nitrogen oxide removing sections are arranged in series, and each of the nitrogen oxide removing sections is provided with a gas outlet of the nitrogen oxide removing section on the preceding stage side. It is possible to more efficiently remove the nitrogen oxides in the gas with a simple device configuration by connecting the gas introduction port of the nitrogen oxide removal section on the subsequent stage side adjacent to become. In addition, since the device configuration is simple, the cost of the device is reduced and maintenance management is facilitated.

According to a fifth aspect of the present invention, there is provided a device for removing nitrogen oxides, wherein water having absorbed nitrogen oxides stored in the water tank is supplied to the nozzle between the nozzle of the nitrogen oxide removing section and the water tank. By providing the supply means, the water once absorbing the nitrogen oxides is again jetted from the nozzle toward the surface of the filter by the supply means to wet the glass fibers and absorb the nitrogen oxides in the gas again. To do. As described above, by circulating the water that has absorbed the nitrogen oxides, it is possible to reduce the processing cost.

In the apparatus for removing nitrogen oxides according to the sixth aspect of the present invention, a transfer means for transferring the water containing nitrogen oxides stored in the water tank on the rear stage side to the water tank on the front stage side is provided between the plurality of water tanks. As a result, the water that has absorbed the nitrogen oxides discharged from the rear side is transferred to the front side and further absorbs the nitrogen oxides, the nitric acid concentration in the water is increased, and the nitrogen oxides of higher concentration are obtained. Recovered as high nitric acid.

In the apparatus for removing nitrogen oxides according to claim 7, the water tank is provided with a cooling means for cooling the water having absorbed the nitrogen oxides, thereby suppressing a temperature rise due to the reaction heat of the water, Keep the vapor pressure of nitric acid low. This allows
It is possible to keep the concentration of nitric acid higher.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and apparatus for removing nitrogen oxides according to each embodiment of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a schematic configuration diagram of a nitrogen oxide removing apparatus according to Embodiment 1 of the present invention. This nitrogen oxide removing device 1 is provided with a gas inlet 2 into which a gas g containing NO _x (nitrogen oxide) is introduced, and above which a gas from which NO _x has been removed is discharged. A reaction container 4 provided with a gas outlet 3, a partition plate 5 provided in the reaction container 4 for partitioning the reaction container 4 into upper and lower chambers, and a central opening of the partition plate 5. a cylindrical filter 6 bottom formed by laminating the shielding glass fiber, a nozzle 7 for injecting tap water to absorb NO _x in the surface of the filter 6, provided at the bottom of the reaction vessel 4, NO _x A drain 8 that discharges tap water that has absorbed water, and a water tank 9 that stores tap water that has absorbed NO _x discharged from the drain 8;
A pipe (10) provided between the nozzle (7) and the water tank (9) to connect them and a tap water (NOx) stored in the water tank (9) and absorbing the NO _x and supplied to the nozzle (7) again ( Supply means) 11.

The pipe 12 connected to the gas inlet 2
And the pipe 13 respectively connected to the gas outlet 3, NO _x
A sensor 14 for detecting the is provided. Further, the water tank 9 is provided with a water supply pipe 15 for supplying tap water and a drain 16 for discharging tap water containing NO _x .

As shown in FIG. 2, the filter 6 has glass fibers 17 having a wire diameter of 12 μm and a packing density of 280.
Twenty-four cylindrical filter elements formed by laminating and winding to a thickness of 70 mm so as to be kg / m ³ are stacked and configured. The packing density is the same as the filter 6
Is set in the range of 250 to 300 kg / m ³ in consideration of the size, the flow rate of passing gas, the amount of tap water to be injected, and the like. Further, the filter 6 may be used by mixing glass fibers 17 having a wire diameter of 12 μm with glass fibers having a wire diameter of 8 μm by about 30% by weight. In this case, since the contact area of tap water is increased, the NO _x recovery efficiency is improved.

Next, the method for removing NO _{x according to} the present embodiment will be described with reference to the above removing device 1. Here, the surface of the filter 6 is always in a wet state by being sprayed with tap water from the nozzle 7. When a gas g containing NO _x is introduced into the reaction container 4 through the gas inlet 2, the gas g enters the filter 6 from the outer peripheral surface of the filter 6, passes through the filter 6, and passes through the inner peripheral surface thereof. Flows upward from, passes through the opening of the partition plate 5, and is discharged from the gas discharge port 3. The gas g comes into contact with tap water adhering to the surface of the glass fiber 17 of the filter 6 while passing through the filter 6, and NO _x is absorbed to be removed gas g ′.

The tap water that has absorbed the NO _x discharged from the reaction container 4 is stored in the water tank 9 and is again supplied to the nozzle 7 by the pump 11 for circulation. The tap water that has absorbed this NO _x is further recycled into the gas g while it is being circulated.
It will absorb O _x . NO absorbed in tap water
_It is assumed that _x is oxidized by oxygen existing on the surface of the glass fiber 17 and converted into nitric acid while being absorbed in contact with tap water. Therefore, the tap water that has absorbed NO _x is changed to nitric acid. Further, while tap water that has absorbed this NO _x , that is, nitric acid is circulated and used, the absorbed NO _x is oxidized and converted to nitric acid, so that the tap water that has absorbed NO _x eventually changes to high-concentration nitric acid. It will be. A part of this high-concentration nitric acid is discharged from the drain 16 to the outside and collected. On the other hand, new tap water corresponding to the reduced amount of tap water is replenished in the water tank 9 by the water supply pipe 15.

[0025] Thus, according to this embodiment, the glass fibers 17 are deposited tap water, since contacting the gas g containing NO _x in the tap water, the NO _x in the gas the surface of the glass fiber 17 It is efficiently absorbed by contacting tap water adhering to and is removed from the gas g. Further, the absorbed NO _x is oxidized and converted into 5% to 25% nitric acid, and thus is recovered and reused as concentrated nitric acid.

Table 1 shows the results of experiments carried out to confirm the effect of this embodiment. Here, the processing gas amount is two kinds of 0.4 m ³ / min and 0.8 m ³ / min. ,
The average removal rate of NO _x was compared when flowing for 2 hours. In addition, the processing gas amount of 0.8 m ³ / min of NO _x
A conventional example is a method of injecting tap water into a gas containing mist to remove NO _x in the gas. Also in this case, the average removal rate of NO _x for 2 hours was obtained and compared with the above.

[0027]

[Table 1]

According to Table 1, in this example, the average removal rate of NO _{x in} the waste gas after the treatment was 0.
92.6% at 4 m ³ / min, 0.8 m ³ / min
79.8% in the case of the conventional example and 29.8% in the conventional example, which is 2.7 to 3.1 times that of the conventional example, and NO.
It turns out that _x is removed. As a result, it is clear that the average removal rate of NO _x is significantly improved.

As described above, according to the method for removing nitrogen oxides of this embodiment, after tap water is attached to the surface of the glass fiber 10, the gas g containing NO _x is brought into contact with the glass fiber 10. since allowed to absorb NO _x in the tap water is, it is possible to efficiently absorb and remove NO _x in the gas g.

According to the nitrogen oxide removing apparatus of this embodiment, the reaction container 4 having the gas inlet 2 and the gas outlet 3 is provided.
A partition plate 5 provided in the reaction container 4, a bottomed cylindrical filter 6 provided at the opening of the partition plate 5, a nozzle 7 for injecting tap water into the filter 6, and the reaction Since the water tank 9 for storing tap water containing NO _x discharged from the container 4 is provided, NO in the gas g can be obtained with a simple device configuration.
_x can be removed efficiently. Further, since the device configuration is simple, the cost of the device can be reduced and maintenance management is easy.

Further, a pipe 10 is provided between the nozzle 7 and the water tank 9 for connecting them, and a pump for supplying the nozzle 7 with tap water which has absorbed NO _x stored in the water tank 9 again. Since No. 11 is provided, the water that has absorbed the nitrogen oxides can be reused, and the water that has absorbed the nitrogen oxides can be recovered and reused as concentrated nitric acid. In addition, since the water is circulated, the processing cost can be reduced.

As shown in FIG. 3, the tap water in which the stored NO _x is absorbed is stored in the water tank 9 at a predetermined temperature (for example,
5 ° C. to keep the temperature below 30 ° C., preferably below 25 ° C.
Coil-shaped cooling pipe 18 that circulates cooling water of approximately 7 ° C
A cooling device (cooling means) including a thermometer 19 and a controller (not shown) may be provided. In this case, since the temperature rise due to the reaction heat of the tap water that has absorbed NO _x is suppressed,
The vapor pressure of nitric acid can be kept low and the concentration of nitric acid can be kept high.

(Embodiment 2) FIG. 4 is a schematic diagram of a nitrogen oxide removing apparatus according to Embodiment 2 of the present invention. The nitrogen oxide removing device 21 includes nitrogen oxide removing units 22a and 22b.
Is connected in series to remove NO _x in two steps.
The configuration of each of the nitrogen oxide removing sections 22a and 22b is exactly the same as that of the removing apparatus 1 of the above-described first embodiment, and regarding each component, after the arithmetic numeral representing each component in the above-mentioned first embodiment, The first stage is represented by a and the second stage is represented by adding subscripts a and b such as b, and the description of each component is omitted.

Then, the nitrogen oxide removing portions 22a,
The gas discharge port 3a and the gas introduction port 2b of the pipe 22b are provided in the pipe 23.
The pipe 23 is provided with a sensor 14 that detects NO _x . Also, the water tank 9a,
9b each other are communicated by a pipe 24, to the tube 24, a pump (transfer means) 25 for sending the tap water containing NO _x, which is stored in the water tank 9b to the aquarium 9a is provided.

Next, the NO _x removing method of this embodiment will be described using the removing device 21. Here, the nitrogen oxide removal unit 22a as nitric collecting concentrator, also using nitrogen oxide removal unit 22b as NO _x removal apparatus. In addition, the surface of the filter 6a (6b) is
Tap water is sprayed by a (7b), and it is always in a wet state.

When the gas g containing NO _x is introduced into the reaction vessel 4a of the nitrogen oxide removing section 22a in the preceding stage through the gas introduction port 2a, the gas g enters the filter 6a from the outer peripheral surface of the filter 6a. , Passes through the filter 6a and flows upward from the inner peripheral surface thereof, passes through the opening of the partition plate 5a, and passes from the gas discharge port 3a to the nitrogen oxide removing unit 22b in the subsequent stage via the pipe 23. be introduced. The gas g is the gas g 'which NO _x in contact with tap water adhering to the surface of the glass fiber 17 of the filter 6a is absorbed is removed while passing through the filter 6a.

The gas g ′ still contains a considerable amount of NO _x.
Remains, the gas g ′ is introduced into the reaction vessel 4b of the nitrogen oxide removing section 22b, and the gas g ′ is filtered by the filter 6b.
Enters the filter 6b from the outer peripheral surface of the
After passing through b, it flows upward from its inner peripheral surface, passes through the opening of the partition plate 5b, and is discharged from the gas discharge port 3b. Then, NO _x in contact with tap water adhering to the surface of the glass fiber 17 of the filter 6b is further absorbed and removed while passing through the filter 6b, the gas g "containing little NO _x.

On the other hand, NO _x discharged from the reaction vessel 4a
The tap water that has absorbed the water is stored in the water tank 9a, and the pump 11
It is supplied to the nozzle 7a again by a, and is recycled.
Further, the tap water that has absorbed the NO _x discharged from the reaction container 4b is stored in the water tank 9b, is supplied again to the nozzle 7b by the pump 11b, and the water tank 15 is replenished with tap water by the water supply pipe 15. some of tap water that has absorbed NO _x in the 9b is transferred to the water tank 9a by a pump 25, a portion of tap water that has absorbed NO _x in the aquarium 9a is discharged by the drain 16, is recovered.

NO _x absorbed in tap water is oxidized by oxygen existing on the surface of the glass fiber 17 and converted into nitric acid while being contacted with tap water and absorbed, as in the case of Example 2 above. Therefore, the tap water that has absorbed NO _x is changed to nitric acid. Also, tap water that has absorbed this NO _x ,
That is, during the circulation and use of nitric acid, the absorbed NO _x is oxidized and converted into nitric acid, so that the tap water that has absorbed NO _x will eventually be converted into high-concentration nitric acid.

As described above, according to the present embodiment, the NO _x is removed in two steps, so that the NO _{x in} the gas is efficiently absorbed in the two steps, removed from the gas g, and absorbed. The NO _x thus generated is oxidized and converted into 25% to 30% nitric acid in the same manner as in Example 1, so that it is recovered as concentrated nitric acid and reused.

Table 2 shows the results of experiments conducted to confirm the effect of the two-step removal of this embodiment.
In order to compare the stepwise removal and the one-step removal, the example B of the above-mentioned example 1 was referred to as a comparative example A, and the operation of the conventional example in Table 1 was performed in two steps as a comparative example B.

[0042]

[Table 2]

According to Table 2, according to the method of this embodiment, the average removal rate of NO _{x in} the waste gas after the treatment in the latter stage is improved by about 15% as compared with the comparative example A, and the second stage is shown. It can be seen that in the removal, the average concentration of NO _{x in} the gas is reduced by one digit as compared with the one-step removal. Therefore, it is clear that the NO _x removal rate is significantly improved. It is also apparent from Comparative Example B that repeating the conventional method in two steps is far from the present Example.

As described above, according to the method for removing nitrogen oxides of this embodiment, after tap water is attached to the surface of the glass fiber 17, the gas g containing NO _x is brought into contact with the glass fiber 17. Since the step of adsorbing NO _x into the tap water is performed in two steps, NO _x in the gas can be absorbed and removed more efficiently.

Further, the nitrogen oxide removing apparatus 2 of this embodiment
According to 1, the nitrogen oxide removing portions 22a and 22b are arranged in two stages, and the gas outlet 3a of the nitrogen oxide removing portion 22a and the gas inlet 2b of the nitrogen oxide removing portion 22b are connected by the pipe 23. , The water tanks 9a, 9b are communicated with each other by a pipe 24,
Since tap water containing NO _x, which is stored in the water tank 9b to the tube 24 provided with a pump 25 to be sent to the water tank 9a, it is possible to efficiently remove NO _x in the gas g in a simple device configuration. Further, since the device configuration is simple, the cost of the device can be reduced and maintenance management is easy. Further, since tap water may be circulated, the running cost of the device can be reduced and it is safe.

(Embodiment 3) FIG. 5 is a schematic diagram of a nitrogen oxide removing apparatus according to Embodiment 3 of the present invention. In this nitrogen oxide removing device 31, three nitrogen oxide removing devices 1 of the above-described first embodiment are connected in series and are connected in the same manner as in the above-mentioned second embodiment.
It is a removal device that removes O _x in three stages.
It is completely the same as the second embodiment that the first stage is represented by adding a suffixes such as a, the second stage is represented by b, and the third stage is represented by adding subscripts a to c after the arithmetic numerals representing the respective components. It is the same.

In this removing device, the gas g containing NO _x
And by sequentially introduced in a nitrogen-oxide removal unit 22a~22c plurality of stages, the step of contacting a gas containing NO _x into tap water was attached to the glass fibers 17 performs three steps, NO in the gas g _x is sequentially absorbed and removed, so gas g
The NO _x therein is absorbed more efficiently and removed from the gas g. The absorbed NO _x is oxidized and converted to 25% or more nitric acid in the same manner as in Examples 1 and 2 above, and thus is recovered and reused as concentrated nitric acid.

Table 3 shows the results of an experiment conducted to confirm the effect of the removing method according to this embodiment. Here,
In order to make a comparison between the three-step removal and the two-step removal, the example of the above-mentioned Example 2 was designated as Comparative Example C, and the operation of the conventional example in Table 1 was conducted in three stages as Comparative Example D.

[0049]

[Table 3]

According to Table 3, in the method of this example, the average removal rate of NO _{x in} the waste gas after the treatment in the final stage was improved by about 4.3% as compared with Comparative example C. It can be seen that the average concentration of NO _{x in} the gas is reduced by one digit or more in the three-step removal compared to the two-step removal. Therefore, it is clear that the NO _x removal rate is significantly improved and almost no NO _x remains. In addition, it is apparent from Comparative Example D that even if the conventional method is repeated in a plurality of stages, it is far from the present embodiment.

As described above, according to the method for removing nitrogen oxides of this embodiment, after tap water is adhered to the surface of the glass fiber 17, the gas g containing NO _x is brought into contact with the glass fiber 17. Since the step of adsorbing NO _x into the tap water is performed in three steps, NO _x in the gas g can be efficiently absorbed and removed to the extent that it hardly remains.

According to the nitrogen oxide removing apparatus of this embodiment, since the nitrogen oxide removing sections 22a to 22c are arranged and connected in three stages, the NO _x in the gas g can be more efficiently provided with a simple apparatus configuration. Can be removed. Further, since the device configuration is simple, maintenance management can be easily performed, and the cost of the device can be reduced.

[0053]

As described above, according to the first aspect of the present invention.
According to the method for removing nitrogen oxides described above, after adhering water to the surface of the glass fibers, a gas containing nitrogen oxides is brought into contact with the glass fibers to absorb the nitrogen oxides into the water, The nitrogen oxide in the gas can be efficiently absorbed by being brought into contact with water adhering to the surface of the glass fiber, and can be efficiently removed from the gas.

According to the method for removing nitrogen oxides of the second aspect, the water having absorbed the nitrogen oxides is again adhered to the surface of the glass fiber so that the water further absorbs the nitrogen oxides, and the gas is removed. Since the nitrogen oxides are removed from the water, the water (nitric acid) that has absorbed the nitrogen oxides further absorbs the nitrogen oxides, and the water that has absorbed the nitrogen oxides can be recovered as high-concentration nitric acid.

According to the nitrogen oxide removing apparatus of the third aspect, the gas inlet for introducing the gas containing the nitrogen oxide and the gas outlet for discharging the gas obtained by removing the nitrogen oxide from the gas. A reaction container provided with, and provided between the gas inlet and the gas outlet provided in the reaction container,
A filter formed by laminating glass fibers, a nozzle for injecting water on the surface of the filter, a water tank for storing water that has absorbed nitrogen oxides discharged from the reaction vessel, and between the water tank and the nozzle. Since it is provided with a supply means for supplying water having absorbed nitrogen oxides stored in the water tank to the nozzle, it is possible to efficiently remove the nitrogen oxides from the gas, The absorbed water can be recovered as nitric acid.

According to the nitrogen oxide removing apparatus of the fourth aspect, a plurality of nitrogen oxide removing sections are arranged in series, and the nitrogen oxide removing section is a gas into which a gas containing nitrogen oxides is introduced. A reaction vessel having an inlet and a gas outlet for discharging a gas obtained by removing nitrogen oxides from the gas, and an interposing between the gas inlet and the gas outlet provided in the reaction vessel. A filter formed by laminating glass fibers, a nozzle for injecting water absorbing nitrogen oxides on the surface of the filter, and a water tank for storing water absorbing nitrogen oxides discharged from the reaction vessel. Since each of the nitrogen oxide removing parts is in a plurality of stages by communicating the gas outlet of the nitrogen oxide removing part on the upstream side and the gas inlet of the nitrogen oxide removing part on the adjacent downstream side, The nitrogen oxide in the gas can be removed with a simple device configuration. It can be rate removed. Further, since the device configuration is simple, the cost of the device can be reduced, and maintenance management can be easily performed.

According to the nitrogen oxide removing apparatus of the fifth aspect, between the nozzle of the nitrogen oxide removing section and the water tank,
Since the supply means for supplying the water absorbing the nitrogen oxides stored in the water tank to the nozzle is provided, the water absorbing the nitrogen oxides can be circulated and used, and the treatment cost can be reduced.

According to the sixth aspect of the present invention, there is provided a transfer device for transferring water having absorbed nitrogen oxides stored in the water tank at the rear stage to the water tank at the front stage between the plurality of water tanks. Since the means is provided, it is possible to further absorb the nitrogen oxides by transferring the water, which has absorbed the nitrogen oxides discharged from the latter stage side, to the former stage side, and it is possible to increase the nitric acid concentration in the water. The oxide can be recovered as a more concentrated nitric acid.

According to the apparatus for removing nitrogen oxides of claim 7, since the water tank is provided with a cooling means for cooling the water having absorbed the nitrogen oxides, the temperature rise due to the reaction heat of the water is suppressed. The vapor pressure of nitric acid can be kept low. Therefore, the concentration of nitric acid can be kept higher and can be recovered as high-concentration nitric acid.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a nitrogen oxide removing device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a filter of a nitrogen oxide removing device according to a first embodiment of the present invention.

FIG. 3 is a partial configuration diagram showing a modified example of the nitrogen oxide removing apparatus according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a nitrogen oxide removing device according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a nitrogen oxide removing device according to a third embodiment of the present invention.

[Explanation of symbols]

1 nitrogen oxide removal device 2 gas inlet 3 gas outlet 4 reaction vessels 6 filter 7 nozzles 8 Drain 9 water tank 10 tube 11 pump 12 pipe 14 for detecting the NO _x sensor 15 water supply pipe 16 drain 17 glass fibers 18 cooling Tube 19 Thermometer 21,31 Nitrogen oxide removing device 22a-22c Nitrogen oxide removing section 2a-2c Gas inlet 3a-3c Gas outlet 4a-4c Reaction vessel 6a-6c Filter 7a-7c Nozzle 8a-8c Drain 9a ~9c aquarium 10a~10c tube 11a~11c pump 23 pipe 25 pump g, g ', a gas containing g "NO _x

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Asano 8-3, Ishizuminami-cho, Neyagawa City, Osaka Prefecture

Claims (7)

[Claims] 1. After attaching water to the surface of the glass fiber,
A method for removing nitrogen oxides, which comprises contacting a gas containing nitrogen oxides with the glass fiber to allow the water to absorb the nitrogen oxides, and removing the nitrogen oxides from the gas. 2. The nitrogen oxide is removed from the gas by adhering the water having absorbed the nitrogen oxide to the surface of the glass fiber again to further absorb the nitrogen oxide in the water. Item 2. A method for removing nitrogen oxides according to Item 1. 3. A reaction container having a gas inlet for introducing a gas containing nitrogen oxides and a gas outlet for discharging a gas obtained by removing nitrogen oxides from the gas, and a reaction container provided in the reaction container. And a filter that is interposed between the gas inlet and the gas outlet and is formed by laminating glass fibers, a nozzle that sprays water on the surface of the filter, and a nitrogen oxide that is discharged from the reaction vessel. A water tank that stores water that has absorbed water, and a supply unit that is provided between the water tank and the nozzle and that supplies to the nozzle water that has absorbed the nitrogen oxides stored in the water tank. Nitrogen oxide removing device. 4. A plurality of nitrogen oxide removing parts are arranged in series, and the nitrogen oxide removing part is a gas inlet for introducing a gas containing nitrogen oxide and a gas obtained by removing the nitrogen oxide from the gas. A reaction container having a gas discharge port for discharging the gas, a filter provided in the reaction container and interposed between the gas introduction port and the gas discharge port, and comprising a glass fiber laminated, A nozzle for injecting water that absorbs nitrogen oxides onto the surface of the filter, and a water tank that stores water that has absorbed nitrogen oxides discharged from the reaction vessel, each of the nitrogen oxide removing units is a front stage side. 2. The nitrogen oxide removing device according to claim 1, wherein the gas outlet of the nitrogen oxide removing section and the gas inlet of the nitrogen oxide removing section adjacent to the subsequent stage are connected to each other to form a plurality of stages. 5. A supply means is provided between the nozzle of the nitrogen oxide removing section and the water tank to supply water having absorbed the nitrogen oxide stored in the water tank to the nozzle. Item 4. A nitrogen oxide removing device according to item 4. 6. A transfer means for transferring water having absorbed nitrogen oxides stored in a water tank on the rear stage side to the water tank on the front stage side, between the plurality of water tanks. 5. The nitrogen oxide removing device according to any one of 5 above. 7. The water tank is provided with cooling means for cooling the water that has absorbed the nitrogen oxides.
The nitrogen oxide removing device according to any one of 4, 5, and 6.