JPH06182145A - Exhaust gas desulfurization apparatus - Google Patents

Abstract

PURPOSE:To prevent dust from adhering to and growing in the circumference of a spray nozzle and at the tip part of an air pipeline and to provide a dry exhaust gas desulfurization apparatus equipped with a highly reliable spray nozzle which can keep a liquid drop spraying function stably. CONSTITUTION:Regarding the exhaust gas desulfurization apparatus to remove sulfur oxides by spraying a desulfurization agent to exhaust gas containing sulfur oxides and moreover spraying water to dampen the gas, the outer circumference of a spray nozzle 5 to spray water is covered with a sealing air supplying pipe 6 and sealing air 3 is supplied at 8m/s or higher flow rate through the outer circumference of the spray nozzle 5. The seal air supplying pipe 6 is made to have a taper shape toward the tip side of the spray nozzle 5 and the tip end 31 is made to have an edge shape and a a whirling vane 4 is provided, so that the sealing air 3 is blown as whirling current uniformly to the circumference of the tip end part of the spray nozzle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry type exhaust gas desulfurization apparatus, and more particularly to a water spray nozzle for spraying the desulfurizing agent,
The present invention relates to a nozzle structure suitable for preventing dust from adhering to the tip of the nozzle.

[0002]

2. Description of the Related Art Exhaust gas discharged from heavy oil-fired and coal-fired boilers at thermal power plants contains substances causing acid rain, such as sulfur oxides, and effective treatment means thereof are desired. . Currently, the mainstream of the treatment method is a wet method (limestone-gypsum method), but this wet method has a high removal efficiency, but on the other hand, it requires wastewater treatment and gas reheating, and has a drawback of high treatment cost.

Therefore, in recent years, development of a simple dry desulfurization apparatus has been activated, which can reduce the treatment cost even if the removal efficiency is low. A typical example thereof is shown in FIG. The exhaust gas from the furnace 11 is heat-exchanged with the air 13 introduced into the furnace 11 in the air preheater 12, and then introduced into the downstream desulfurization reactor 16 via the flue 14. Here, the desulfurizing agent 19 made of powder of an alkali or alkaline earth metal compound or the like is blown into the furnace 11 or the flue 14. Next, the desulfurizing agent 19
The exhaust gas containing the is subjected to humidification cooling in the desulfurization reactor 16 by fine spray of water 15, and the sulfur oxide in the exhaust gas which reacts with the desulfurization agent 19 is removed here. Desulfurization agent 18 that has reacted
Is collected by the dust collector 17, and the processing gas is discarded from the chimney 20.

In the above dry type exhaust gas desulfurization apparatus, a spray nozzle 5 for water 15 for cooling the exhaust gas containing the desulfurizing agent 19
As shown in FIG. 5, a spray nozzle 5 for two-fluid spray consisting of spray water 1 and spray air 2 is usually used.
Since the spray flow velocity is a high flow velocity of 100 m / s or more, a negative pressure is generated around the spray nozzle 5, and a vortex flow is generated. Therefore, a part of the sprayed droplets is caught in this vortex flow, and there is a problem that they adhere to the spray nozzle 5 along with the dust and grow on the powder adhering scale 8 as shown in FIG. When the powder adhesion scale 8 is formed, the water spray passage from the spray nozzle 5 is limited. Therefore, as shown in FIG. 6, a part of the sprayed water droplets collides with the powder adhesion scale 8 to form a wet surface, and the coarser droplet 10 is re-scattered from the surface of the adhered matter. When the droplet diameter becomes coarse, the droplet 10 does not evaporate sufficiently, so that the gas cooling efficiency decreases.

Further, the spray nozzle 5 is provided with a powder adhesion scale 8
In order to prevent the air from growing, a technique has conventionally been adopted in which a seal air supply pipe 9 is provided around the spray nozzle 5 to supply the seal air 3 as shown in FIG. However, even in this case, the air 3 is not jetted uniformly around the spray nozzle 5 due to a non-uniform flow in the seal air supply pipe 9, and the powder adhered scale 8 may grow at a portion where the jet flow velocity is slow, which may cause a long time. There was also a problem that the state of droplet spraying deteriorates after spraying with water. Further, when the powder adhesion scale 8 adheres and grows at the tip of the seal air supply pipe 9, a phenomenon in which a coarse droplet 10 is generated occurs as shown in FIG. There was also a problem that the cooling efficiency decreased. Further, when the tip diameter of the seal air supply pipe 9 is reduced as shown in FIG. 9 in order to reduce the flow rate of the seal air 3, if the tip has a flat structure, the powder adhering to the flat surface is peeled off. However, there is a problem that the powder adhered scale 8 is eventually formed and the spray droplets collide with the powder adhered scale 8 and normal spray cannot be maintained.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent dust from adhering and growing around the spray nozzle and the tip of the air pipe, and to maintain a stable droplet spray by using a dry spray nozzle having a high reliability. An object is to provide an exhaust gas desulfurization device.

[0007]

The above object of the present invention can be achieved by the following constitutions. That is, in an exhaust gas desulfurization device for removing sulfur oxides by spraying a desulfurizing agent containing an alkali metal or alkaline earth metal compound in the exhaust gas containing sulfur oxides, and further spraying water to humidify An exhaust gas desulfurization apparatus equipped with a spray nozzle that covers the outer periphery of a spray nozzle to be sprayed with a seal air supply pipe, and sprays water from the outer periphery of the spray nozzle at a flow velocity of a predetermined flow velocity (for example, 8 m / s) or more. is there. Here, the seal air supply pipe is tapered toward the tip side of the spray nozzle, and the tip of the seal air supply pipe is formed into an edge shape, so that the scale is less likely to adhere to the tip portion. Furthermore, by providing a swirl vane in the seal air supply pipe near the tip of the spray nozzle, the seal air is blown evenly around the tip of the spray nozzle as a swirl flow.

[0008]

[Function] Since air having a predetermined flow velocity or more is blown as a sealing fluid from the outer periphery of the spray nozzle for spraying water,
A steady flow rate can be secured as compared with the case where the gas to be treated (exhaust gas) is used as the sealing fluid, and formation of powder adhesion scale at the tip of the spray nozzle can be prevented. At this time, it is possible to reliably prevent the dust from being entrapped in the spray nozzle by supplying the sealing air at a predetermined flow velocity or more. Further, in order to prevent the uneven flow of the seal air at the tip portion, by providing the swirl vane, the seal air is uniformly supplied to the periphery of the spray nozzle at the predetermined flow rate, and the generation of the powder adhered scale can be reliably prevented. As for dust adhesion to the tip of the seal air supply pipe, as shown in FIG. 1, the seal air supply pipe has a tapered shape and the tip of the seal air supply pipe has an edge structure so that the dust adheres to the tip. Since the scale thickness becomes thin due to the powder, the powder adhesion strength decreases. Therefore, the adhered powder repeats growth and peeling, and as a result, the adhered growth of the powder does not proceed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The dry exhaust gas desulfurization apparatus of this embodiment is as shown in FIG. In the process in which the exhaust gas from the furnace 11 is guided to the desulfurization reactor 16, it is desulfurized by a desulfurization agent 19 made of powder of alkali or alkaline earth metal compound or the like. At this time, the exhaust gas containing the desulfurizing agent 19 is humidified and cooled in the desulfurization reactor 16 by fine spray of water 15, and the desulfurizing agent 19
Sulfur oxides in the exhaust gas that react with are removed.

In the above-mentioned dry type exhaust gas desulfurization apparatus, a spray nozzle 5 for water 15 for cooling exhaust gas containing a desulfurizing agent 19
As shown in FIG. 1, a two-fluid spray nozzle composed of spray water 1 and spray air 2 is used. The seal air supply pipe 6 is provided around the pipe for supplying the two-fluid spray nozzle 5.
Is provided and the seal air 3 is supplied into the seal air supply pipe 6 at a flow rate of 8 m / s. Here, a swirl vane 4 that gives a swirl flow to the seal air 3 is provided at the tip of the seal air supply pipe 6. FIG. 2 shows a top view of the two-fluid spray nozzle 5. As a result, the sealing air 3 is blown out at a substantially uniform flow velocity around the spray nozzle 5.

The adhesion of dust around the spray nozzle 5 can be prevented by supplying the seal air 3 at a predetermined flow velocity or higher to prevent the dust from being caught in the spray nozzle 5. FIG. 4 shows the relationship between the flow velocity of the seal air 3 and the tip diameter of the seal air supply pipe 6 after the water spray test is completed.
The tip diameter before the test is 22 mm, and when the sealing effect is not sufficient, the tip diameter after the test becomes 22 mm or less due to the growth of the deposit. As shown in FIG. 4, if the flow velocity of the seal air 3 is 8 m / s or more, the spray nozzle 5
It is clear that the effect of preventing powder adhesion to the surface is high. Further, in order to prevent eddy flow and uneven flow of the seal air 3 at the tip of the spray nozzle 5, it is found that the swirl vane 4 is provided so that the seal air 3 can be uniformly supplied to the periphery of the spray nozzle 5 at a flow rate of 8 m / s. did. Further, the seal air supply pipe 6 is tapered toward the tip side,
In addition, since the tip 31 of the seal air supply pipe 6 has an edge structure, even if dust adheres to the pipe 6, the adhesion strength is weak and it becomes difficult to grow as a powder adhesion scale.

[0012] Incidentally, Japanese Utility Model Laid-Open No. 20919/1990 discloses a structure of a slaked lime slurry spray nozzle of a reaction tower applied to a waste incineration plant exhaust gas treatment apparatus and the like, and this nozzle is located above the center of the throat. And a stop ring surrounding the nozzle and a plurality of blades inclined to the exhaust gas flow on the outer periphery of the ring. There is. The plurality of blades have a structure similar to that of the vane of the present embodiment in that it gives a swirling flow to the fluid, but the swirling flow of the exhaust gas by the plurality of blades is from the slaked lime slurry spray nozzle. Only in the outer peripheral portion with a space, in the vicinity of the nozzle, the exhaust gas flows as it is in the inner peripheral side of the stop ring. The device described in the above publication constantly collects the main flow of the exhaust gas flowing into the throat at the center of the reaction tower by means of a plurality of blades and stop rings, so that even if the exhaust gas flow rate fluctuates, That is, it will not fall and the adhered scale will not grow.

On the other hand, in this embodiment, a sealing gas (air) different from the gas to be treated is used as a swirling flow generated on the outer circumference of the nozzle in order to prevent the adhered scale from being formed on the nozzle for water spray of the exhaust gas desulfurization apparatus. It is used, and unlike the gas to be treated, there is no risk of fluctuations in its flow rate. Further, the swirling flow of air generated in the present example is different from the exhaust gas swirling flow described in the above publication, and is not limited to the outer peripheral portion spaced from the nozzle, and causes the generation of the powder adhesion scale in the vicinity of the nozzle tip. It is possible to prevent the generation of a vortex flow and to prevent a drift at the tip of the nozzle.

[0014]

According to the present invention, the seal air can be supplied evenly around the spray nozzle, dust adhesion and growth around the spray nozzle and the tip of the seal air supply pipe can be prevented, and highly reliable water spray can be achieved. . Therefore, the cooling efficiency of the exhaust gas does not decrease.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a spray nozzle according to an embodiment of the present invention.

FIG. 2 is a top view of FIG.

FIG. 3 is a diagram showing an exhaust gas desulfurization apparatus according to an embodiment of the present invention.

FIG. 4 is a graph showing the influence of the sealing air flow rate on the sealing effect according to the embodiment of the present invention.

FIG. 5 is a diagram showing the structure of a conventional water spray nozzle.

6 is a diagram showing the behavior of droplets in the water spray nozzle shown in FIG.

FIG. 7 is a diagram showing the structure of a water spray nozzle of the prior art.

8 is a diagram showing the behavior of droplets in the water spray nozzle shown in FIG.

FIG. 9 is a diagram showing the structure of a water spray nozzle of the prior art.

[Explanation of symbols]

1 ... Spray water, 2 ... Spray air, 3 ... Seal air, 4 ... Swirling vanes 5 ... Spray nozzles, 6, 9 ... Seal air supply piping, 8 ...
Powder adhesion scale, 10 ... Coarse droplets, 31 ... Tip of seal air supply pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Nishimura 6-9 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Ltd. Kure Factory

Claims (3)

[Claims] 1. An exhaust gas desulfurization apparatus for removing sulfur oxides by spraying a desulfurizing agent containing an alkali metal or alkaline earth metal compound into exhaust gas containing sulfur oxides, and further spraying water to humidify the sulfur oxides. An exhaust gas desulfurization device comprising a water spray nozzle structure in which the outer periphery of a spray nozzle for spraying water is covered with a seal air supply pipe, and the seal air is blown out from the outer periphery of the spray nozzle at a flow velocity higher than a predetermined flow velocity. 2. The exhaust gas desulfurization apparatus according to claim 1, wherein the seal air supply pipe is tapered toward the tip side of the spray nozzle, and the tip of the seal air supply pipe is edge-shaped. 3. A swirl vane is provided in the seal air supply pipe near the tip of the spray nozzle.
Exhaust gas desulfurization device described.