JP2000051650A - Ammonia injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably maintain injection of an ammonia by conforming to a distribution state of a SOx amount by a method wherein an injection tube is made of a duplex tube wherein an air passage is formed by sectioning between an outer tube and an inner tube, a tapered cylindrical part is arranged to duct jet opening side of a nozzle, and ammonia and compressed air are circulated. SOLUTION: Ammonia 30 passes through an ammonia passage 18 in an inner tube 11 of a nozzle 7 wherein many nozzles are disposed in a row per each injection tube, and flows into an inner channel 17 of a cylindrical part 13. Besides, compressed air flows into an air passage 12 of the nozzle 7, stored in an air room 16 through an air hole of a partition wall 21 and thereafter, ejected into an ammonia flow at an inlet end of the inner channel 17 from a ring-like slit 15. Then, an outer layer of the ammonia flow 30 becomes a whirling flow of little turbulence and ejected into an exhaust gas from a jet opening 13a. Since a jet of the ammonia 30 and the air forms a stable jet stream therefore, the ammonia 30 can be avoided from being reacted by direct contact with SO3 in the exhaust gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ammonia injection apparatus for injecting reducing ammonia into a dry flue gas desulfurization apparatus or the like.

[0002]

2. Description of the Related Art In a catalytic flue gas desulfurization system using ammonia, the distribution of SOx (sulfur oxide) in a duct at a portion where ammonia is usually injected is not uniform, and the distribution in the horizontal or vertical direction is not uniform. The SOx distribution exists. In such a catalytic-reduction-type dry flue gas desulfurization apparatus, various ammonia injection apparatuses have been proposed with a primary focus on leveling the distribution of SOx as described above.

FIGS. 3 to 5 show an ammonia injection apparatus proposed in Japanese Patent Publication No. 4-40056, FIG. 3 is an overall configuration diagram, and FIGS. 4 and 5 are detailed views of an injection pipe and a nozzle portion (operation). FIG.

In FIGS. 3 to 5, reference numeral 01 denotes a duct,
Reference numeral 05 denotes a header, and reference numeral 05 denotes a plurality of ammonia injection pipes arranged (standing) in the duct 01 in parallel. A plurality of nozzles 06 are fixed to each injection pipe 05 at regular intervals in the longitudinal direction and parallel to the gas flow Z. 03 is a valve provided at the base of each injection pipe 05 (near the outlet of duct 02) to adjust the opening degree (passage area) of each injection pipe 05, and 09 measures the flow rate of ammonia in each injection pipe 05. An orifice 04 is provided at the outlet of each nozzle 06.

[0005] In such an ammonia injection apparatus, the SOx distribution in the horizontal direction in the duct 01 is adjusted by changing the opening of the valve 03 provided in each injection pipe 05, and the vertical direction in the duct 01 is adjusted. SOx
The distribution is adjusted according to the hole diameter of the orifice 04 (see FIG. 5) provided at the tip of each nozzle 06, and ammonia corresponding to the distribution is injected. At this time, the amount of ammonia is measured by the orifice 09 for measuring the flow rate.

[0006]

Among the ammonia injection devices as shown in FIGS. 3 to 5, the so-called dirty gas, which is the combustion exhaust gas from a coal-fired boiler with a high dust concentration or a heavy oil-fired boiler with a high sulfur concentration, is used. In the ammonia injection device attached to the flue gas desulfurization device to be treated, as shown in FIG. 4, a turbulence 011 is generated in the exhaust gas flow by the injection pipe 05, and the turbulence 011 causes dust in the exhaust gas to flow toward the injection pipe 05. There is a risk that the dust will be trapped and deposited. In addition, ammonia is blown out from the injection nozzle 06 and also entrains ammonia, and this ammonia reacts with SO ₃ in the exhaust gas to generate acidic ammonium sulfate, thereby solidifying and growing the deposited dust. Due to such an action and the generation of the vortex 011 at the nozzle 06 ejection portion due to the turbulence of the exhaust gas, the dust is more easily deposited.

As a result, in the prior art, as shown in FIG. 5, the dust accumulates and grows on the nozzle 06 and the cap 012 at the tip, and the accumulated dust 010 becomes 1
As a result, the nozzles are formed into two nozzles, and the direction in which ammonia is ejected is changed. This makes it difficult to uniformly distribute ammonia.

In view of the above-mentioned problems of the prior art, the present invention makes it possible to inject ammonia for a long time and stably by using an appropriate amount of ammonia and an appropriate injection direction in accordance with the distribution state of the amount of SOx in the horizontal and vertical directions in the duct. It is an object of the present invention to provide an ammonia injection device which can be maintained in a stable manner.

[0009]

In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a plurality of injection pipes for injecting ammonia in a duct through which exhaust gas flows, and to inject ammonia into the pipe. In an ammonia injection device configured to inject into the exhaust gas in the duct through a plurality of nozzles fixed along the longitudinal direction of the pipe and the injection pipe,
The injection pipe is configured as a double pipe in which an air passage is formed between an outer pipe and an inner pipe, and the nozzle includes a cylindrical part having a tapered outlet on the side of the duct to the duct. The ammonia injection device is characterized in that the inlet end of the internal flow path through which ammonia flows is communicated with the air passage of the injection pipe so that ammonia and compressed air can flow. suggest.

According to a second aspect of the present invention, in the first aspect, the nozzle has an ammonia flow passage formed inside the inner cylinder, the ammonia flow passage communicating with the internal flow passage of the cylindrical portion. An annular air passage communicating with the air passage of the injection pipe is formed between the outer periphery and the inner periphery of the outer cylinder, and compressed air is supplied from the annular air passage to an inlet end of the internal flow passage of the cylindrical portion. An air jet port for jetting is provided.

According to this invention, ammonia flowing from the inner pipe of the double injection pipe through the ammonia passage inside the inner cylinder of each nozzle flows into the conical cylindrical part of the nozzle. At this time, the compressed air that has passed through the air passage between the outer tube and the inner tube of the injection tube and reached the air passage of the nozzle is jetted toward the ammonia flow at the inlet of the cylindrical portion. When the ammonia and the air flow through the tapered cylindrical portion, the outer layer of the ammonia flow becomes a turbulent spiral flow (wrapping flow) wrapped by the air layer and is ejected into the exhaust gas.

Therefore, the jet of ammonia and air jetted from the nozzle forms a jet which has a long potential core and is stable over time, and the ammonia and SO ₃ in the exhaust gas come into direct contact in the vicinity of the nozzle. And reacting is avoided. As a result, solidification and growth of dust due to the production of acidic ammonium sulfate are prevented, and the dust is prevented from adhering to the nozzle orifice of the nozzle and closing it.

Further, since the jet ejected from the nozzle has a swirling flow, the jet is diffused in a right angle direction at a position downstream from the nozzle orifice by a predetermined distance and is disturbed by the exhaust gas, so that good mixing can be achieved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

FIG. 1 is a main part configuration diagram of an ammonia injection device for a flue gas desulfurization device according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a nozzle portion. In FIG. 1, reference numeral 5 denotes an injection pipe, and a number of them are juxtaposed (standing) in a duct 01 as shown in FIG. The injection pipe 5 is a double pipe of an outer pipe 5a and an inner pipe 5b, and an air passage 5c through which compressed air flows between the inner circumference of the outer pipe 5a and the outer circumference of the inner pipe 5b. Are formed. The inside of the inner pipe 5b is an ammonia passage 5d. Reference numeral 7 denotes a spiral flow type nozzle fixed at a predetermined gap (which may be an equal interval or an irregular interval) along the longitudinal direction of the injection pipe 5.

The spiral flow type, that is, the low turbulence and stable swirling flow type nozzle 7 is configured as shown in FIG. 2, in which 10 is an outer cylinder, 11 is an inner cylinder, and 10 is an inner cylinder. An air passage 1 is provided between the inner circumference of the
2 are formed. The air passage 12 communicates with the air passage 5c of the injection pipe 5, and the ammonia passage 18 formed inside the inner cylinder 11 communicates with the ammonia passage 5d inside the inner pipe 5b of the injection pipe 5.

Reference numeral 13 denotes a cylindrical portion, and the end of the duct 01
(See FIG. 3) A jet port 13a is provided which opens into the inside, and the inlet end of the internal flow path 17 is connected to the ammonia passage 18 in the inner cylinder 11, and from the inlet end toward the jet port 13a. It is formed in a tapered conical shape. 16
Is an annular air chamber formed at an end portion of the outer cylinder 10. The air chamber 16 and the air passage 12 inside the outer cylinder 10 are partitioned by a partition wall 21. Are provided with a plurality of air holes 14 at predetermined intervals along the circumferential direction. Reference numeral 15 denotes an annular slit formed inside the air chamber 16 and communicates the air chamber 16 with an inlet end of a flow path 17 in the cylindrical portion 13.

In the ammonia injection apparatus for a flue gas desulfurization apparatus having such a configuration, as shown in FIG.
As will be described later, ammonia 30 is mixed with compressed air and ejected from a number of nozzles 7 into the exhaust gas Z in the exhaust gas Z.
Ox is reduced and purified.

At the time of the injection of ammonia, a large number of ammonia 30 guided from the header 02 (see FIG. 3) to the ammonia passage 5d in the inner pipe 5b of each injection pipe 5 are arranged for each injection pipe 5. It enters the ammonia passage 18 in the inner cylinder 11 of the nozzle 7, flows therethrough, and enters the internal flow path 17 of the cylindrical portion 13.

On the other hand, the compressed air enters the air passage 12 of each nozzle 7 through the air passage 5c of the injection pipe 5, is stored in the air chamber 16 through the air hole 14 of the partition wall 21, and its static pressure is reduced. After being raised, it is ejected from the annular slit 15 into the ammonia flow at the inlet end of the internal flow path 17.

As a result, the ammonia and the compressed air flow through the tapered cylindrical portion 13, so that the outer layer of the ammonia flow 30 becomes a turbulent swirling flow wrapped by the air layer 20, and the exhaust gas is discharged from the outlet 13a. Squirted inside.

The jet of ammonia 30 and air jetted from the nozzle 7 forms a temporally stable jet with a long potential core, so that the ammonia 30 and the SO _{3 in the} exhaust gas near the nozzle 7. Is prevented from directly contacting and reacting. As a result, solidification and growth of dust due to generation of acidic ammonium sulfate can be prevented, and such dust can be prevented from adhering to the ejection port 13a of the nozzle 7 and closing the ejection port 13a. Further, since the jet ejected from the nozzle 7 has a swirling flow,
20 to 30 times downstream of the diameter of the jet port 13a, it rapidly diffuses in a direction perpendicular to the jet and mixes well with the exhaust gas, whereby good mixing is achieved.

[0023]

As described above, according to the present invention, ammonia and air flow through the tapered cylindrical portion, so that the outer layer of the ammonia flow becomes a turbulent spiral flow that is wrapped in the air layer and the exhaust gas is discharged. By being ejected inside, a long-time stable jet of the potential core can be formed.

Thus, ammonia and SO in the exhaust gas
Solidification growth of dust due to direct contact with ₃ is prevented,
The nozzle can be prevented from being clogged due to the adhesion of the dust, and the clogging can prevent a decrease in the amount of injected ammonia and a decrease in desulfurization performance.

Further, since the jet of ammonia ejected from the nozzle has a spiral flow as described above, the diffusion of ammonia is improved, and the uneven distribution of ammonia is eliminated, and the distribution of the ammonia in accordance with the SOx amount distribution is reduced. In addition, it is possible to appropriately inject ammonia, thereby improving desulfurization performance and reducing ammonia consumption.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an ammonia injection device for a flue gas desulfurization device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a nozzle section in the embodiment.

FIG. 3 is a schematic configuration diagram of an ammonia injection device for a flue gas desulfurization device according to the related art.

FIG. 4 is an operation explanatory view (No. 1) of the vicinity of a nozzle portion in the above-mentioned conventional technology.

FIG. 5 is an operation explanatory view (part 2) in the above-described conventional technique.
It is.

[Explanation of symbols]

 01 Duct 5 Injection pipe 5a Outer pipe 5b Inner pipe 5c Air passage 5d Ammonia passage (injection pipe) 7 Nozzle 10 Outer cylinder 11 Inner cylinder 12 Air passage 13 Cylindrical part 13a Spout port 14 Air hole 15 Slit 16 Air chamber 17 Internal flow Road 18 Ammonia passage (nozzle) 20 Air layer 21 Partition wall 30 Ammonia

Claims (2)

[Claims] 1. A plurality of injection pipes for injecting ammonia are arranged in a duct through which exhaust gas flows, and ammonia is passed through the injection pipe and a plurality of nozzles fixed along a longitudinal direction of the injection pipe. In an ammonia injection device configured to inject into exhaust gas in a duct, the injection pipe is configured as a double pipe having an air passage formed between an outer pipe and an inner pipe, and the nozzle is connected to the duct. The jet outlet side has a tapered cylindrical portion and is formed in the cylindrical portion, and the inlet end of the internal flow path through which the ammonia flows is communicated with the air passage of the injection pipe, and the ammonia and the compressed air are communicated with each other. An ammonia injection device characterized by being configured to be able to flow. 2. The nozzle has an ammonia flow passage formed inside the inner cylinder and communicated with an internal flow passage of the cylindrical portion, and a nozzle is provided between an outer periphery of the inner cylinder and an inner periphery of the outer cylinder. An annular air passage communicating with the air passage of the injection pipe is formed, and an air injection port for ejecting compressed air from the annular air passage to an inlet end of an internal flow path of the cylindrical portion is provided. 1
The ammonia injection device as described.