JPH02223624A - Ammonia mixing device in denitration device - Google Patents

Abstract

PURPOSE:To provide uniform concentration distribution without reliquefying atomized aqueous ammonia by a cylindrical guide in an elbow of an ammonia mixing device so that it may enclose the outer periphery of a protruding atomizing nozzle. CONSTITUTION:A vaporizing acceleration guide 6 formed into a cylinder is provided so that it may be based on the inner wall of an elbow 4 and enclose a protrusion 5c in the elbow 4 of an aqueous ammonia atomizing nozzle 5 and have an excess length in the extension direction of the end of the protrusion 5c. As a result, the aqueous ammonia can be protected from being disturbed by exhaust gas at the stage of laminar conditions of large grains immediately after its jetting. Consequently, the aqueous ammonia is protected from being re-liquefied due to knocks on the inner wall of the elbow 4 by exhaust gas, and is protected by the guide 6 until atomization of the aqueous ammonia has been accelerated for uniform distribution of ammonia concentration when mixed with exhaust gas.

Description

[Detailed description of the invention] "Industrial application field" In engines that emit exhaust gas such as diesel engines, NO, (nitrogen oxides) in the exhaust gas is reduced to less than 1 as required by law. .

It is necessary to provide a denitrification device as shown in FIG.

In the figure, 1 is an engine such as a diesel engine,
2 is a catalytic reactor.

Elbow 4. An ammonia mixing device consisting of an ammonia water spray nozzle 5, 6 and 7 are supply pipes, and 8 is an exhaust pipe, the exhaust gas discharged from the engine 1 through the supply pipe 6 is mixed with ammonia water atomized in the mixing device. A gas mixed with ammonia gas is produced by the mixed koji, and is supplied to the catalytic reactor 2 through the supply pipe 7.
A considerable amount of NoX is reduced to nitrogen and water by the catalyst inside the engine, reducing the amount of NOx to an appropriate value and releasing it from the exhaust pipe.
I'm trying to drain it.

However, the ammonia mixing device in such a denitrification device has a problem in its construction as described below.

The present invention relates to an ammonia mixing device applied to a denitrification device that has been improved to solve these problems.

[Prior Art] As shown in FIG. 2, the conventional ammonia mixing device has a bend corresponding to approximately the center of the elbow 4 disposed in the middle of the supply pipe 6, 7 shown in FIG. The ammonia water spray nozzle 5 was connected to the ammonia water spray nozzle 5 provided vertically so that the tip of the ammonia water spray nozzle faced the upper space of the elbow 4.

Note that 5a is an ammonia water supply port, 5b is a compressed air supply port, and the compressed air is supplied under pressure from a compressor (not shown).

In the above configuration, when engine exhaust gas (high temperature) is supplied from the right end 4a side of the elbow 4, and ammonia water that has been sprayed upward is supplied from the ammonia water spray nozzle 5, this ammonia water is When it comes into contact with high-temperature exhaust gas, it is vaporized into ammonia gas, that is, the exhaust gas is mixed with ammonia gas in the elbow 4, and then passes through the upper port 4b to the catalytic reactor 2 (Fig. 3). Head to the side.

[Problems to be Solved by the Invention] By the way, the right end 4 of the elbow 4 of the ammonia mixing device 2
The exhaust gas supplied from a has a pressure inside the elbow 4 of approximately 3
In the case of 00 wAq, the flow velocity is about 20 m/see, so the ammonia water sprayed from the ammonia water spray nozzle 5 in the form of a spray is brought to the flow velocity of the exhaust gas and becomes liquid and adheres to the wall of the elbow 4. Resulting in.

That is, when ammonia water is injected from the spray nozzle 5, large droplets of so-called Illll in a liquid state are produced in a short distance section.
The farther the liquid particles go, the more they become atomized into atomized particles of about 5 μm in size.

However, as mentioned above, the ammonia water injected in the elbow 4 is hit by the wall of the elbow 4 due to the flow velocity of the exhaust gas in the section in the NJ flow state in the short distance after the injection, and is re-liquefied. Otherwise, it is fed into the catalytic reactor 2 as a large lump.

Therefore, the ammonia-laden exhaust gas passes through the catalytic reactor 2 in a mixture of areas with high ammonia concentration and areas with low ammonia concentration, and the denitrification effect is not performed uniformly. There was a drawback (problem) that NOx was not reduced to the desired value.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ammonia mixing device in a denitrification device that solves the problems of the conventional devices.

[Means for Solving the Problems] The present invention provides an elbow in which the right end of the elbow is arranged on the inlet side of the exhaust gas of the engine, and the upper end is arranged on the outlet side that supplies the catalytic reactor. An ammonia water spray nozzle having a tip protruding from the tip and arranged so that the direction of the ammonia water sprayed from the tip is the same direction as the flow of the exhaust gas, and the extension direction of the tip of the ammonia water spray nozzle. The present invention relates to an ammonia mixing device in a denitrification device, characterized in that the device includes a cylindrical vaporization promoting guide that has an extra length and surrounds an ammonia water spray nozzle.

[Example] The present invention will be specifically described below with reference to an example shown in FIG.

In this figure, parts equivalent to those in FIG. 2 are designated by the same reference numerals.

6 is a cylindrical guide for promoting vaporization.

Place the base on the inner wall of the elbow 4 as shown.

Spray ejected from the ammonia water spray nozzle 2, which surrounds the protrusion 5c in the elbow 4 of the ammonia water spray nozzle 5, and has an extra length in the direction of extension of the tip of the protrusion 5c, and surrounds the ammonia water spray nozzle. This is to protect the heated ammonia water from being disturbed by the exhaust gas immediately after it is injected into a large R-flow state.

For this reason, the inner diameter of the guide 6 is calculated, the distance between the tip of the guide 6 and the tip of the ammonia water spray nozzle 5 is S, the spray angle of the nozzle 5 is θ, and the envelope formed by ammonia water when sprayed from the nozzle. Let d be the diameter of the intersecting surface when it crosses the tip surface of the guide 6, and set the injection angle θ to, for example, 15~
It is desirable that the configuration is such that when the value is set to 20 degrees, the relationship D≧d S>2D holds true.

That is, the ammonia mixing device 2 of the present invention is characterized by being equipped with the guide 6 for promoting vaporization described above.

Note that it is desirable that the guide 6 has a cylindrical cross section;
Not limited to this, in short, the spray nozzle 6 has a cylindrical shape in a broad sense.
All you have to do is surround it.

Further, other structures such as the catalytic reactor constituting the denitrification apparatus may be the same as the conventional structure shown in FIG. 3, and therefore their explanation will be omitted.

[Function] Also in the denitrification device to which the ammonia mixing device of the present invention is applied, as shown in FIG. Ammonia water and compressed air are similarly supplied to each supply port 5a, 5b of the ammonia mixing device 2, and atomized ammonia water is injected into the first elbow 4.

By the way, in the case of the ammonia mixing device 2 of the present invention,
A guide 6 is provided, and the vicinity A of the tip of the spray nozzle 5 surrounded by the guide 6 is in a negative pressure state due to the ejector effect.

In other words, this part is completely protected from the exhaust gas pressure and is under a negative pressure lower than the surrounding exhaust gas wind pressure, so the ammonia water in the laminar flow immediately after being injected from the spray nozzle 5 is absorbed by the exhaust gas. It travels straight forward without being affected by the flow velocity, becomes atomized, and at that point merges with the exhaust gas, promoting vaporization into ammonia gas.Furthermore, the exhaust gas flowing through the small diameter side and large diameter side of the elbow is The turbulent flow generated in the B portion due to the difference in flow velocity V, V2 also causes a -like mixing.

Therefore, the concentration of ammonia, which comes into contact with the hot exhaust gas and becomes ammonia gas and is mixed into the exhaust gas, becomes uniform.

[Effects of the Invention] As described above, the present invention is an ammonia mixing device for a denitrification device in which a cylindrical guide is provided to surround the outer periphery of the spray nozzle protruding into the elbow of the ammonia mixing device. It has the following excellent effects.

■The atomized ammonia water injected from the ammonia water spray nozzle is blocked from the exhaust gas by the guide, so it cannot be re-liquefied by being hit against the wall of the supply pipe by the exhaust gas in the laminar flow section. do not have.

■In other words, the ammonia water injected from the ammonia water spray nozzle is protected by the guide until the atomization is promoted to a mist state, so when this ammonia water spray is mixed with the exhaust gas, the ammonia concentration is is uniformly distributed, the concentration of ammonia gas supplied to the catalytic reactor is uniform, and the reduction action is effectively performed.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional front view showing one embodiment of the ammonia mixing device of the present invention, Fig. 2 is a longitudinal sectional front view showing a conventional one, and Fig. 3 shows the configuration of a denitrification device to which these ammonia mixing devices are applied. FIG. 2. Ammonia mixing device 4; Elbow 5: Ammonia water spray nozzle 6: Guide for promoting vaporization D = Ni guide inner diameter d; Intersection diameter S Distance between the tip of the guide and the tip of the ammonia water spray nozzle θ: Spray angle of the nozzle Applicant Shinko Electric Co., Ltd. Agent Patent attorney Haruya Saito Two fools Figure 2 Mh Figure

Claims (1)

[Claims] The right end of the elbow is placed on the inlet side of the engine exhaust gas, and the upper end is placed on the outlet side that supplies the catalyst reactor. The ammonia water spray nozzle is arranged so that the direction of the ammonia water to be sprayed is the same as the flow of the exhaust gas, and the ammonia water spray nozzle has an extra length in the extending direction of the tip, 1. An ammonia mixing device in a denitrification device, comprising a cylindrical guide for promoting vaporization surrounding a nozzle.