JPH10176527A - Denitration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the lowering of the denitration effect due to the unevenness of the gas density to be generated by irregular flow or turbulence of the exhaust gas, which flows into a reaction unit of a denitration system. SOLUTION: In this device, the NOx removing agent 2 having the honeycomb structure are laminated, and the exhaust gas G is made to flow into an upper space from a side of a reaction unit 1, and while the reducing agent is sprayed so as to eliminate the nitrogen oxide with a catalyst reducing method. In this case, a shield plate 11 is arranged in the upper space at a position opposite to the lead-in part of the exhaust gas, and when the exhaust gas collides with the shield plate 11, a backward spiral flow is generated for strengthening. Or, single or plural reflecting plates are fixed to corners of the upper space so that the exhaust gas is turned in a flat surface by the reflecting plates for even distribution and straightening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

Relates denitration apparatus for removing the invention the nitrogen oxides contained in the exhaust gas of an internal combustion engine or the like (NO _X) BACKGROUND OF THE INVENTION, in particular the reactor inwardly shield or reflector The present invention relates to a denitration device provided with:

[0002]

BACKGROUND ART NO _X processing technology has been required in various fields, for example, since the NO _X present in the exhaust gas such as a diesel engine is also a cause of acid rain be deleterious to the human body, technique that handles NO _X of the exhaust gas effectively is desired.

[0003] Generally, the above-mentioned NO _X treatment method is put to practical use as a flue gas denitration technique. This flue gas denitrification technique is roughly classified into a dry method and a wet method. At present, a selective catalytic reduction method, which is one of the dry methods, is technically advanced, and is attracting attention as an effective denitration method.

The main reaction of the above selective catalytic reduction method is as follows.

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O (1) In this reaction, ammonia, hydrocarbon, and carbon monoxide are used as a reducing agent. since oxygen is removed selectively NO _X even coexist, it is effectively used to remove of the NO _X contained in the exhaust gas such as a diesel engine.

As an example of the above-mentioned denitration apparatus, as shown in FIG. 7, a large number of denitration agents 2 and 2 made of a honeycomb-shaped catalyst are arranged and laminated inside a closed reactor 1.
At the same time as the exhaust gas G flows in from above the reactor 1, means for spraying the reducing agent stored in the tank 4 from the nozzle 3 to perform catalytic reduction based on the above formula (1) is often used. . As a catalyst constituting the denitration agent 2, a noble metal such as platinum or various metal oxides supported on alumina, titanium oxide (TiO ₂ ) or the like is used.

In the example of FIG. 7, a space portion 15 is formed above the denitration agents 2 and 2, and the space portion 15 enhances the mixing effect of the exhaust gas G and the reducing agent flowing into the space portion 15 and causes the exhaust gas G to drift. Or the effect of suppressing turbulence. Generally, the piping for sending the exhaust gas G into the reactor 1
Due to the surrounding space and layout, it is hardly formed into a straight tube because of the layout, and it is customary that the middle part of the pipe is usually bent, so that a drift or a turbulent flow may occur in the exhaust gas G. Inevitably, the space 15
Therefore, means for suppressing drift and turbulence is required.

FIG. 8 shows another example of a conventional denitration apparatus. In this example, a pipe 5 into which exhaust gas G flows is connected to the side of a closed-type reactor 1 and the inside of the reactor 1 is connected. The denitration agent 2 formed in a honeycomb shape is laminated, and a reducing agent is sprayed from a nozzle (not shown) arranged in a preceding stage of the pipe 5 to perform a catalytic reduction reaction based on the above formula (1).

[0009]

However, in such a conventional denitration apparatus, the exhaust gas G flowing into the reactor 1 is not uniform due to the uneven flow of the exhaust gas G or the uneven gas density due to the turbulent flow. There is a disadvantage that the diffusion state of G tends to be insufficient, and a uniform denitration effect based on the catalyst cannot be obtained for the entire exhaust gas in some cases.

In the configuration example of FIG. 7, the exhaust gas flowing into the reactor 1 often flows through a bent pipe due to the relationship with peripheral equipment such as a generator.
The effect of suppressing the drift or the turbulent flow is not sufficient if only the space 15 is formed in the inside, and the space 15 is extended up and down in order to enhance the suppression action and the mixing effect of the reducing agent. Therefore, there is a problem that the reactor 1 itself becomes large and a large installation space is required.

In the configuration example of FIG. 8, since the pipe 5 through which the exhaust gas G flows is connected to the side of the reactor 1, the pipe 5
However, when the exhaust gas G is caused to flow from the side of the reactor 1, the space 15 is simply provided near the inlet of the exhaust gas G. Cannot prevent the drift of the exhaust gas G,
In addition, there is a disadvantage that the mixing space between the exhaust gas G and the reducing agent is insufficient. Therefore, as in the example of FIG.
5 has to be extended up and down, and there is a problem that the reactor 1 itself becomes large.

The denitration agents 2 and 2 filled in the reactor 1
It is desirable to flow the exhaust gas G into the inside at a uniform flow rate. However, as shown in the honeycomb flow velocity distribution diagram in FIG. The flow velocity is large, the flow velocity in the peripheral part tends to be small,
This is a factor that hinders the uniformity of the denitration effect.

Accordingly, the present invention solves the above-mentioned problems of the conventional denitration apparatus, and reduces the denitration effect caused by unevenness of the gas density due to drift or turbulence of the exhaust gas flowing into the reactor. It is an object of the present invention to provide a denitration apparatus capable of preventing the deterioration.

[0014]

According to the present invention, in order to solve the above-mentioned problems, a denitration agent comprising a catalyst formed in a honeycomb shape is laminated and arranged inside a closed type reactor, and the denitration agent is arranged from the side of the reactor. At the same time as the exhaust gas of the internal combustion engine flows into the upper space in the reactor, a reducing agent is sprayed into the exhaust gas to remove nitrogen oxides in the exhaust gas based on the catalytic reduction method. In a denitration apparatus configured to discharge the gas, a claim 1 is provided.
By disposing a shielding plate in a portion of the upper space in the reactor opposite to the exhaust gas introduction portion, and when a flowing exhaust gas collides with the shielding plate, a wake vortex is generated. It has a configuration of a denitration device that performs rectification.

According to a second aspect of the present invention, one or more reflectors are fixed to the corners in the upper space, and the exhaust gas flowing in is uniformly distributed by swirling the space in the space by the reflectors. The denitration device is configured to perform rectification. The shape of the shielding plate or the reflecting plate is either a disk shape or a square disk shape.

According to the denitration apparatus of the first aspect,
When the exhaust gas is fed into the reactor as a non-uniform drift or turbulent gas density, this exhaust gas collides with the shielding plate, generates a wake vortex and is rectified before passing through the denitration agent and, nitrogen oxides (NO _X) is removed by uniform denitration reaction based on the main reaction of selective catalytic reduction. Therefore, the bias of the pressure distribution is reduced by the rectifying action of the shielding plate, and the action of averaging the gas density is obtained.

According to the second aspect of the present invention, similarly to the above, after the exhaust gas that has flowed in a non-uniform or turbulent state having a non-uniform gas density collides with the reflector, it turns in a plane in the space. As a result, the fluid is evenly distributed, the bias in the pressure distribution is reduced, the gas density is averaged, and then the gas passes through the denitration agent, and the nitrogen oxides are removed by a uniform denitration reaction.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of a denitration apparatus according to the present invention will be described below in detail with reference to the drawings, in which the same reference numerals are given to the same components as the above-mentioned conventional components. FIG. 1 is a vertical sectional view showing a configuration of a denitration apparatus 10 according to a first embodiment of the present invention. In this embodiment, a pipe 5 into which exhaust gas G flows is connected to a side of the reactor 1. It has a basic structure. Inside the reactor 1, a honeycomb-shaped denitration agent 2 is laminated, and a reducing agent is sprayed into the exhaust gas G from a nozzle (not shown) arranged in a preceding stage of the pipe 5 to perform a catalytic reduction reaction. Is done. Reference numeral 15 denotes a space in the reactor 1, and reference numeral 6 denotes a discharge part of the exhaust gas G.

A portion close to the pipe 5 in the reactor 1,
If reduced, the shielding plate 11 is disposed in the space 15 corresponding to a portion facing the direction of introduction of the exhaust gas G.
As shown in FIGS. 2A and 2B, the shielding plate 11 is formed of a disc-shaped member having a mounting hole 11a opened in the center.

As the means for fixing the shielding plate 11, the mounting hole 11a may be fixed to the tip of a support rod (not shown) provided through the wall from the outside of the reactor 1. . The shape of the shielding plate 11 is not limited to a disk shape,
Other shapes that generate wake vortices may be used. In the first embodiment, the volume of the space 15 in the reactor 1 is smaller than the volume of the space 15 of the conventional example (FIG. 7).

The operation of the first embodiment will be described below. That is, the exhaust gas G generated from the internal combustion engine is introduced into the reactor 1 through the pipe 5 together with the reducing agent, and the gas density of the exhaust gas G is changed into an uneven drift or turbulent state. When it is sent to the exhaust gas G, it collides with a shielding plate 11 disposed at a portion opposite to the introduction direction of the exhaust gas G, and generates a wake vortex by the shielding plate 11 to be rectified. Pass through 2. Then, based on the main reaction of the selective catalytic reduction method (see the above formula 1), nitrogen oxides (NO _x ) contained in the exhaust gas G are removed by a uniform denitration reaction and released from the discharge unit 6. Is done.

Therefore, even if there is a drift or turbulence in the exhaust gas G flowing into the reactor 1, the bias of the pressure distribution is reduced by the rectifying action of the shielding plate 11, and the honeycomb body constituting the denitration agent 2 Since the rectifying action is generated even by the uniform pressure resistance, the effect of rectifying the turbulent flow or the turbulent flow is large, and an operation mode in which the gas density is averaged is obtained.

FIG. 5 is a diagram showing the flow velocity distribution in the honeycomb in the first embodiment. In comparison with the conventional example shown in FIG. , Because the flow velocity distribution is flat overall,
It is understood that the effect of the drift of the exhaust gas G is eliminated and the denitration effect is made uniform.

FIG. 3 is a longitudinal sectional view of a main part showing a second embodiment of the present invention, and FIG. 4 is a plan sectional view of the same. The basic structure of the device is the same as that of the first embodiment. For this reason, the same reference numerals are attached and displayed. In the second embodiment, one or a plurality of reflectors 12 are fixed to a corner in the upper space 15 in the reactor 1. The shape of the reflection plate 12 may be any of a disk shape or a square shape, and at least one reflector is disposed at a corner in the space 15, preferably a total of four reflectors are disposed at each corner, and fixed.

In the second embodiment, the volume of the space 15 is smaller than in the first embodiment. Note that FIG.
As shown in the figure, the radial dimension L of the reflection plate 12 is
Is formed so as to be larger than the inner diameter length l. Other components are the same as those of the first embodiment.

According to the second embodiment based on such a configuration,
Exhaust gas G generated from the internal combustion engine is introduced into the reactor 1 together with the reducing agent through the pipe 5 as a non-uniform drift or turbulent gas density. After that, as shown by the arrow C in FIG.
The fluid is uniformly distributed on the surface of the honeycomb body constituting the exhaust gas G, and accordingly, the exhaust gas G is rectified.

Thereafter, the exhaust gas G passes through the denitration agents 2 and 2, and the nitrogen oxides (NO _x ) contained in the exhaust gas G are uniformed based on the main reaction of the selective catalytic reduction method described above. It is removed by an appropriate denitration reaction and is discharged from the discharge unit 6.

Therefore, even if the exhaust gas G flowing into the reactor 1 has a drift or a turbulent flow, the space 1
The bias of the pressure distribution is reduced by the rectifying action accompanying the turning in the inside 5, and the rectifying action occurs even by the uniform pressure resistance of the honeycomb body constituting the denitration agent 2.
An operation mode in which the drift or the turbulent flow of the gas is eliminated and the gas density is averaged is obtained.

FIG. 6 is a diagram showing the flow velocity distribution in the honeycomb according to the second embodiment. In the same manner as in the first embodiment, the flow velocity protruding portion disappears with the presence of the reflection plate 12, and the flow velocity distribution becomes flat. As a result, the uniformity of the denitration effect can be measured.

[0030]

As described above in detail, according to the denitration apparatus according to the first embodiment of the present invention, even if the exhaust gas flowing into the reactor has a drift or a turbulent flow, it flows into the reactor. At the same time, it collides with the shielding plate arranged at the part opposite to the introduction part to generate wake vortices, so that the flow is rectified and the gas flow rate and density are almost uniform, and then the gas passes through the denitration agent. In addition, nitrogen oxides (NO _x ) contained in exhaust gas can be removed based on the uniform main reaction of the selective catalytic reduction method.

Further, according to the second embodiment of the present invention, after the inflowing exhaust gas collides with the reflector, the fluid is uniformly distributed by swirling in the space partly in a plane, whereby the exhaust gas is distributed. After the rectification, the denitration agent can be passed to perform effective denitration.

Therefore, due to the surrounding space and the layout, it is possible to accurately cope with the state of the drift or turbulence of the exhaust gas which is likely to occur when the pipe for feeding the exhaust gas into the reactor is bent. The state does not remain up to the outlet of the reactor, and the exhaust gas is sufficiently mixed with the reducing agent and passes through the denitration agent, so that the concentration of the reducing agent becomes uniform and the denitration efficiency can be improved. or,
Since there is no need to provide a wide space in the reactor as in the related art, there is an effect that the size of the reactor itself can be reduced and a large installation space is not required.

Therefore, according to the present invention, a uniform denitration effect based on the catalyst can be obtained for the entire exhaust gas by adjusting the diffusion state of the exhaust gas caused by uneven gas density due to drift or turbulence. A denitration device can be provided.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a main part showing a configuration of a denitration apparatus to which a first embodiment of the present invention is applied.

2A is a side sectional view showing the shielding plate of FIG. 1, and FIG.
Plan view.

FIG. 3 is a vertical sectional view of a main part showing a configuration of a denitration apparatus to which a second embodiment of the present invention is applied.

FIG. 4 is a plan sectional view of FIG. 3;

FIG. 5 is a view showing a flow velocity distribution in a honeycomb in the first embodiment.

FIG. 6 is a view showing a flow velocity distribution in a honeycomb in the second embodiment.

FIG. 7 is a schematic diagram showing a configuration of a conventional denitration apparatus.

FIG. 8 is a schematic diagram showing the configuration of another conventional denitration apparatus.

FIG. 9 is a diagram showing a flow velocity distribution in a honeycomb in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reactor 2 ... Denitration agent 5 ... Piping 6 ... Discharge part 10 ... Denitration device 11 ... Shielding plate 11a ... Hole 12 ... Reflection plate 15 ... Space

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F01N 3/28 301 B01D 53/36 102A

Claims (3)

[Claims] 1. A denitration agent comprising a catalyst formed in a honeycomb shape is laminated and disposed inside a closed-type reactor, and exhaust gas of an internal combustion engine is supplied from a side of the reactor to an upper space in the reactor. At the same time as the inflow, the reducing agent is sprayed into the exhaust gas to remove the nitrogen oxides in the exhaust gas based on the catalytic reduction method, and is discharged from the discharge portion. A denitration characterized by disposing a shielding plate in a space portion facing an exhaust gas introduction portion, and generating and rectifying a wake vortex when inflowing exhaust gas collides with the shielding plate. apparatus. 2. A denitration agent comprising a catalyst formed in a honeycomb shape is laminated and arranged inside a closed type reactor, and exhaust gas of an internal combustion engine is fed from a side of the reactor into an upper space inside the reactor. A denitration apparatus in which a reducing agent is sprayed into the exhaust gas at the same time as it flows in to remove nitrogen oxides in the exhaust gas based on a catalytic reduction method and discharge the exhaust gas from an exhaust portion. A denitration apparatus characterized in that one or a plurality of reflectors are fixed to a portion, and the exhaust gas flowing in is swirled in a space by the reflectors in a plane so as to be uniformly distributed and rectified. 3. The denitration apparatus according to claim 1, wherein the shape of each of the shielding plate and the reflecting plate is one of a disk shape and a square shape.