JPH08266860A - Nitrogen oxide adsorbing and removing device - Google Patents

Abstract

PURPOSE: To prevent the divagation of a regenerating gas when the gas is passed through a reactor. CONSTITUTION: An adsorbent 12 is packed in a closes reactor 11 so that the reactor is divided into a diffusion zone 43 and a collection zone 44. A treated inlet 31 is formed to the reactor 11, communicates with the diffusion zone 43 and opposed to the adsorbent 12, and a treated gas outlet 32 communicated with the collection zone 44 and is opposed to the adsorbent 12. Further, a regenerating gas inlet 35 is formed to the reactor 11, communicates with the collection zone 44 and is set orthogonal to the treated gas outlet 32, and a regeneration gas outlet 36 communicates with the diffusion zone 43 and is set orthogonal to the treated gas inlet 31.

Description

Detailed Description of the Invention

[0001]

This invention relates to various road tunnels,
A large amount of ventilation gas (100,000 m3) in various tunnels such as mountain tunnels, subsea tunnels, underground roads, and roads with shelters.
/ h or more), and a NOx adsorption / removal device for adsorbing and removing a low concentration of NOx (nitrogen oxide).

[0002]

2. Description of the Related Art As this type of NOx adsorption / removal device,
The so-called cone type is a horizontal cylindrical closed reactor having tapered portions at both ends, and an adsorption filled in the reactor so as to divide it into a diffusion zone and a collection zone in the length direction. And a reactor,
A processing gas inlet communicating with the diffusion zone and facing the adsorbent and a processing gas outlet communicating with the collection zone and facing the adsorbent are provided, and an inlet pipe is provided at the processing gas inlet and an exhaust pipe is provided at the processing gas outlet. It is known that they are connected to each other, and a discharge gas is provided with a regeneration gas inlet and an introduction pipe is provided with a regeneration gas outlet.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the Ox adsorption removal device, if the size of the diffusion zone and the collection zone is set to be large enough to allow the regeneration gas to sufficiently diffuse in the diffusion zone and the collection zone in preparation for regeneration of the adsorbent, the adsorbent will pass through. However, if the size of the diffusion zone and the collection zone is small, the regeneration gas concentrates only in the portion of the entire adsorbent that faces the processing gas inlet and outlet. As a result, the deviation of the regeneration gas becomes large. Therefore, the diffusion zone and the collection zone tend to be set large, and then the entire reactor becomes large, and it is difficult to install the reactor in a limited space such as an underground space.

An object of the present invention is to provide a NOx adsorption / removal device which solves the above-mentioned problems, prevents regenerant gas from drifting when passing through a reactor, and saves space.

[0005]

A NOx adsorption / removal apparatus according to the present invention comprises a closed reactor and an adsorbent filled in the reactor so as to divide the reactor into a diffusion zone and a collection zone. In the NOx adsorption removal device in which the reactor is provided with a processing gas inlet communicating with the diffusion zone and facing the adsorbent and a processing gas outlet communicating with the collection zone and facing the adsorbent, the reactor is provided with: A regeneration gas inlet communicating with the collection zone and orthogonal to the processing gas outlet and a regeneration gas outlet communicating with the diffusion zone and orthogonal to the processing gas inlet are provided.

Further, it is preferable that the adsorbent is divided into a plurality of blocks arranged in the process gas flow direction, and a rectifying zone is formed between adjacent blocks.

Further, the cross-sectional area of the collection zone may be gradually narrowed away from the regeneration gas inlet.

Both the vertical cross section and the horizontal cross section of the reactor may be formed in a rectangular shape.

[0009]

In the NOx adsorption / removal device according to the present invention, the reactor is provided with a regeneration gas inlet which communicates with the collection zone and is orthogonal to the treatment gas outlet, and a regeneration gas which is communicated with the diffusion zone and orthogonal to the treatment gas inlet. Since the outlet is provided, the regenerated gas introduced into the collection zone from the inlet is
In the collection zone, it flows in such a direction to the surface of the adsorbent to be diffused, passes through the whole of the adsorbent, then flows along the surface of the adsorbent in the diffusion zone and exits from the outlet.

Further, if the adsorbent is divided into a plurality of blocks arranged in the process gas flow direction and a rectifying zone is formed between adjacent blocks, the regenerated gas that has passed through the upstream block is generated. It is rectified by the time it passes through the wake block.

Further, if the cross-sectional area of the collection zone is gradually narrowed as it goes away from the regeneration gas inlet, the regeneration gas flowing into the collection zone from the regeneration gas inlet is prevented from going straight, and the regeneration gas in the collection zone is blocked. The flow is directed towards the adsorbent.

Further, when the vertical cross section and the horizontal cross section of the reactor are both formed in a rectangular shape, the maximum gas passage area is secured in the minimum space.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

Referring to FIGS. 1 to 3, the NOx adsorption / removal apparatus comprises a reactor 11 and an adsorbent 12 filled in the reactor 11.

The reactor 11 is a box-shaped hermetically-closed reactor having a vertical cross section and a horizontal cross section.
22 and left and right side walls 23 and 24 and top and bottom walls 25 and 26. A heat insulating material 27 is lined on the inner surface of the reactor 11.

The front end wall 21 has a forwardly projecting rectangular tubular processing gas inlet.
The rear end wall 22 is provided with a rearward projecting rectangular tubular processing gas outlet 32. Dampers 33 and 34 are provided at the open ends of the inlet 31 and the outlet 32, respectively. An upper protruding rectangular tubular regeneration gas inlet 35 is provided at the rear end of the top wall 25, and an upward protruding rectangular tubular regeneration gas outlet 36 is provided at the front end thereof. Dampers 37 and 38 are also provided at the open ends of the inlet 35 and the outlet 36, respectively.

The adsorbent 12 is divided into front and rear blocks 41 and 42. These two blocks 41, 42 are arranged at a predetermined interval in the front-rear center of the reactor 11. As a result, in the reactor 11, a diffusion zone 43 in communication with the processing gas inlet 31 and the regeneration gas outlet 36, a collection zone 44 in communication with the processing gas outlet 32 and the regeneration gas inlet 35, and the front and rear 2 A straightening zone 45 sandwiched between two blocks 41 and 42 is formed.

The adsorbent depends on the components and concentration in the processing gas.
Twelve types and the number of blocks 41 and 42 are set appropriately. Further, depending on the case, the type of the adsorbent 12 forming the two blocks 41 and 42 may be changed for each block.

The processing gas is supplied from the processing gas inlet 31 to the reactor 11
While passing through the adsorbent 12, the target components such as nitrogen oxides contained in the processing gas are adsorbed and removed, and then discharged from the processing gas outlet 32 to the outside of the reactor 11.

When the concentration of the treated gas component exceeds the reference value or when the gas passage time reaches the reference time, the adsorbent 12 is regenerated.

Regeneration of the adsorbent 12 is carried out by introducing a regeneration gas into the reactor 11 through the regeneration gas inlet 35. Hot air at 200 to 350 ° C. is used as the regeneration gas. The regeneration gas introduced into the reactor 11 passes through the adsorbent 12 in the direction opposite to the flow of the processing gas, and during this time, the adsorbent 12
The adsorbent 12 is regenerated by desorbing the target component adsorbed on the. The regeneration gas that has passed through the adsorbent 12 is discharged from the regeneration gas outlet 36 to the outside of the reactor 11. The discharged regenerated gas is passed through an ammonia-added SCR denitration catalyst (not shown) to remove the target component, and then introduced into the reactor 11 through the regenerated gas inlet 35 and circulated and reused.

In order to effectively regenerate the adsorbent 12, it is necessary to minimize the nonuniform flow of the regeneration gas when passing through the adsorbent 12 so that the regenerant gas flows uniformly. If the uneven flow is large, the temperature rise of the adsorbent 12 may fluctuate, and the regenerated residue may occur, so that the regeneration may not be performed uniformly.To avoid this, it is necessary to use more regeneration gas than necessary. It is uneconomical. In addition, when the regenerated gas is turbulent due to the uneven flow, the pressure loss is increased, and the operating cost of the regenerated gas blower is also increased.

When the regeneration gas is introduced into the reactor 11, the regeneration gas is rapidly diffused in the collecting zone 44 and the flow is disturbed.
At 45, the turbulence of the regenerated gas is alleviated. After this, the regeneration gas passes through the front block 41, so that the diffusion zone
The regenerated gas flows in a rectified state at 43, and is finally discharged from the reactor 11 through the regenerated gas outlet 36.

Here, an experiment for measuring the flow velocity of the regenerated gas when passing through the adsorbent 12 was carried out using a model machine of the NOx adsorption / removal device shown in FIG. 4, which will be described.
4, parts corresponding to those of the device shown in FIG. 1 are designated by the same reference numerals.

The length × width × height of the reactor 11 is 4200 × 1600
× 4600 mm. Regeneration gas inlet 35 and outlet 36 are 750
It is × 1600 mm. The flow velocity was measured with a hot wire anemometer.

The measurement results are shown in FIG. FIG. 5A shows the flow velocity distribution in the rear block 42, and FIG. 5B shows the flow velocity distribution in the front block 41. Referring to FIG. 5 (a), the flow velocity of the regeneration gas when passing through the rear block 42 is 1.0 at the upper side.
It is m / s and 2.0 m / s on the lower side, and gradually increases from the upper side to the lower side. On the other hand, referring to FIG. 5 (b), the flow velocity is almost 1.5 m / s as a whole, which shows that the turbulence of the regenerated gas is alleviated in the rectification zone 45.

Next, referring to FIG. 6, NO shown in FIG.
A modified example of the model machine of the x adsorption removal device will be described.

In the apparatus shown in FIG. 6, the cross-sectional area of the collecting zone 44 of the reactor 11 is narrowed as it goes away from the regeneration gas inlet 35. At the upper end of the collection zone 44, the length in the front-back direction was 750 mm.
At the lower end of the, the length in the front-rear direction is almost zero.

In this modification, the regenerated gas flowing into the reactor 11 through the regenerated gas inlet 35 collides with the rear end wall 22 of the reactor 11 before reaching the bottom wall 26 of the reactor 11 to generate the regenerated gas. Is directed toward the adsorbent 12, so that the flow velocity in the portion far from the regeneration gas inlet is weakened. Therefore, further drift is alleviated.

Next, as a comparative example, NOx shown in FIG.
A similar measurement experiment was carried out using a model machine of the adsorption / removal device, which will be described below. In the apparatus shown in FIG. 7, the regeneration gas inlet 35 is directed rearward toward the upper end of the rear end wall of the reactor 11,
Regeneration gas outlets 36 are provided forward at the lower end of the front end wall of the reactor 11.

Referring to FIG. 8 showing the measurement results, FIG.
In (a), the fast part with a flow velocity of 2.5 m / s is concentrated in the upper part of the rear block 42.
It is considered that this is because the regeneration gas flowing in from the chamber directly collides with the adsorbent. On the other hand, in FIG. 8 (b), the bias of the flow velocity distribution shown in FIG. 8 (a) is eliminated, but the upper and lower portions of the front block 41 have a high velocity of 2.0 m / s before. It is considered that the high flow velocity in the upper part is due to the regeneration gas flowing from the regeneration gas inlet 35 passing straight through the rear block 42, and the high velocity in the lower part is due to the regeneration gas being collected at the regeneration gas outlet 36. it is conceivable that.

Further, for comparison, the same measurement experiment was conducted by using a model machine of the NOx adsorption / removal device shown in FIG. The apparatus shown in FIG. 9 is a combination of the apparatus shown in FIG. 4 and the apparatus shown in FIG. 7, with the regeneration gas inlet 35 facing upward to the rear end of the top wall 25 of the reactor 11, and the regeneration gas outlet 36. Are provided at the lower end of the front end wall 21 of the reactor 11 so as to face forward.

Referring to FIG. 10 showing the measurement results, FIG.
The velocity distribution shown in 0 (a) is very similar to the velocity distribution of FIG. 5 described above, but the velocity distribution shown in FIG.
The flow velocity distribution is significantly different from that shown in (b), and the flow velocity becomes faster toward the lower side.

[0034]

According to the invention described in claim 1, the regeneration gas introduced from the inlet into the collecting zone flows toward the surface of the adsorbent in the collecting zone in such a direction to be diffused, and passes through the entire adsorbent. After that, since it flows along the surface of the adsorbent in the diffusion zone and exits from the outlet, it is possible to prevent a nonuniform flow of the regeneration gas when passing through the adsorbent.

According to the second aspect of the present invention, the regeneration gas that has passed through the upstream block is rectified by the time that it passes through the downstream block, so a further effect of preventing drift can be expected.

According to the third aspect of the present invention, the regeneration gas flowing from the regeneration gas inlet into the collection zone is prevented from going straight, and the flow of the regeneration gas in the collection zone is directed toward the adsorbent. It can be expected to prevent the uneven flow of water.

According to the invention described in claim 4, since the maximum gas passage area is secured in the minimum space, the reactor can be made compact, and installation in a narrow limited space is possible. .

[Brief description of drawings]

1 is a vertical cross-sectional view of a device according to the present invention.

FIG. 2 is a view taken along the line II-II of FIG.

3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a cross-sectional view of a model machine for flow velocity experiment of the same apparatus, which is equivalent to FIG. 1.

5 is a flow velocity distribution chart showing the experimental results of the model machine of FIG.

FIG. 6 is a sectional view corresponding to FIG. 4, showing a modified example of the device according to the present invention.

7 is a cross-sectional view of a model machine for flow velocity experiment showing a comparative example corresponding to FIG.

FIG. 8 is a flow velocity distribution chart showing an experimental result of the model machine of FIG. 7.

FIG. 9 is a cross-sectional view of a model machine for flow velocity experiment corresponding to FIG. 4, showing a further comparative example.

FIG. 10 is a flow velocity distribution chart showing an experimental result of the model machine of FIG.

[Explanation of symbols]

 11 Reactor 12 Adsorbent 31 Processing gas inlet 32 Processing gas outlet 35 Regeneration gas inlet 36 Regeneration gas outlet 43 Diffusion zone 44 Collection zone 45 Rectification zone

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shiro Koga 5-3-8, Nishikujo, Konohana-ku, Osaka City Hitachi Shipbuilding Co., Ltd.

Claims (4)

[Claims] 1. The reactor 11 is provided with a sealed reactor 11 and an adsorbent 12 which is filled in the reactor 11 so as to divide the reactor 11 into a diffusion zone 43 and a collection zone 44. Process gas inlet communicating with zone 43 and facing adsorbent 12
In the NOx adsorption / removal device, which is provided with a processing gas outlet 32 that communicates with 31 and the collection zone 44 and faces the adsorbent 12, the reactor 11 communicates with the collection zone 44 and the processing gas outlet 32.
An NOx adsorption / removal device which is provided with a regeneration gas inlet 35 and a regeneration gas outlet 36 which communicate with the diffusion zone 43 and are orthogonal to the processing gas inlet 31. 2. The adsorbent 12 is divided into a plurality of blocks 41, 42 arranged in the process gas flow direction, and a rectifying zone 45 is formed between adjacent blocks 41, 42. NOx adsorption removal device described. 3. The cross-sectional area of the collection zone 44 is such that the regeneration gas inlet
The NOx adsorption / removal device according to claim 1 or 2, wherein the NOx adsorption / removal device is gradually narrowed away from 35. 4. The vertical and horizontal cross sections of the reactor 11 are:
The NOx adsorption / removal device according to any one of claims 1 to 3, which is formed in a rectangular shape.