JP3447152B2 - Low temperature gas cooling tower - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature range gas degassing tower for reducing the temperature of exhaust gas discharged from a municipal waste incinerator or the like to a low temperature range. 2. Description of the Related Art Conventionally, as shown in, for example, FIG.
(00 ° C.) 2 is led to a waste heat boiler 3 to extract residual heat in the form of steam, and is used as a heat source for a plant, hot water supply, or the like.
Further, after the exhaust gas 2 is led to the gas temperature-reducing tower 4 to reduce the temperature,
The dust is guided to a bag filter 5 or an electric dust collector to collect and remove fine dust, and then to a chimney 6. [0003] The operation of the gas cooling tower 4 is limited to a medium temperature range or a high temperature range.
The temperature of the exhaust gas at 500 ° C is reduced to 250 to 300 ° C, and the exhaust gas at 800 to 900 ° C is
The temperature has dropped to ~ 500 ° C. This is because in the gas cooling tower 4, the exhaust gas at 200 to 300 ° C. is discharged at 140 to 170 ° C.
This is because it is difficult to operate in a low-temperature region where the temperature decreases. [0004] In a gas cooling tower, cooling water is sprayed into exhaust gas flowing into the tower, and the cooling water takes off heat as latent heat from the exhaust gas to evaporate, thereby cooling the exhaust gas. For this reason, when the gas cooling tower is operated in a low temperature range, the temperature of the exhaust gas flowing into the tower is 200 to 3
Since it is in a low temperature range of 00 ° C, the evaporation rate of cooling water is slow,
Cooling water required to cool the exhaust gas to a predetermined temperature,
It was difficult to completely evaporate the exhaust gas in a limited time during which it passed through the tower. [0005] In recent years, as an effective method for removing harmful substances such as carcinogenic substances contained in exhaust gas,
It has been proposed to guide the exhaust gas at a low temperature to a bag filter for filtration. However, if the cooling water does not completely evaporate in the gas cooling tower, the unevaporated cooling water flows into the bag filter located downstream of the gas cooling tower, and the filter cloth of the bag filter gets wet and the wet filter becomes wet. There was a problem that dust was fixed on the cloth and clogged. Further, in the conventional gas cooling tower, since the cooling water is sprayed from a single spray nozzle at the center of the tower, the amount of water required to reduce the temperature of the exhaust gas to the set temperature can be reduced within a unit time. In order to spray, the particle size of the water droplet had to be large. The sprayed cooling water acts on the gas flow as a load, the rising force near the center of the gas flow is weakened, and the swirling force on the outer layer of the gas flow acts strongly. For this reason, a downward flow is generated at the center of the tower, and some of the sprayed water droplets fall to the bottom of the tower.The water droplets have a large particle size and are easily subjected to centrifugal force due to the swirling flow. , And there is a problem that dust may adhere to the wet wall surface and cause dust trouble. The present invention solves the above-mentioned problems, and
It is an object of the present invention to provide a low-temperature-area gas cooling tower in which cooling water completely evaporates without contacting the inner wall of the tower even during operation in a low-temperature area. [0008] In order to solve the above-mentioned problems, a low-temperature region gas cooling tower according to the present invention has an internal ventilation passage that forms a cooling space for a gas to be cooled, and the gas is cooled. An outer tower that circulates as a rising flow while circulating through the ventilation path is provided, the inner tower is arranged concentrically inside the lower part of the outer tower, and the upper end of an annular gap formed between the inner tower and the outer tower A gas supply port is formed between the outer tower and the inner tower, which is open toward the tangential direction of the tower wall, and a cooling water spray nozzle is provided inside the upper part of the inner tower. 0.55-0.
This is a configuration formed by 65 times. With the above structure, the gas to be cooled, which is tangentially jetted from the gas supply port into the gap between the outer tower and the inner tower, swirls along the inner peripheral surface of the outer tower and closes the gap at the lower end. It flows as a downward flow toward the opening. The gas flow that reaches the open port flows into the inside of the inner tower from the lower end opening of the inner tower, turns upward, and turns upward once while reducing the turning diameter and turning along the inner peripheral surface of the inner tower. The water flows from the upper end opening of the inner tower while swirling into the ventilation path of the outer tower. In the vicinity of the upper end opening of the inner tower, cooling water is sprayed from a cooling water spray nozzle against the swirling gas flow.
The particles of the cooling water are diffused by the swirling flow of the gas into fine particles and diffused widely in the gas flow, and the fine particles rise along with the gas flow toward the top of the ventilation path of the outer tower. During this time, the cooling water evaporates by removing heat as latent heat from the gas and cools the gas to a set temperature range. In the above operation, the flow state of the gas flow in the outer tower changes depending on the inner diameter of the inner tower. If the inner diameter φd of the inner tower is too small relative to the inner diameter φD of the outer tower,
The gas flow becomes a swirl flow with the swirl axis deviating from the center of the tower, and the gas flow accompanying the particles of cooling water locally contacts the inner surface of the outer tower, causing dust trouble. Conversely, if the inner diameter φd of the inner tower is too large relative to the inner diameter φD of the outer tower, a downward flow is generated on the center side of the inner tower, and the sprayed cooling water descends the inner tower with the downward flow. For this reason, the inner diameter φd of the inner tower is changed to the inner diameter φ of the outer tower.
By forming the gas flow rate to be 0.55 to 0.65 times D, the flow state of the gas flow in the outer tower can be a uniform swirl flow whose swirl axis coincides with the center line of the outer tower. As a result, while the gas flow rises up the ventilation path of the outer tower, fine particles of the cooling water ascend the center side of the outer tower while expanding the swirling diameter,
It reaches the top of the tower without reaching the inner surface of the outer tower. Therefore, the inner surface of the outer tower is not wetted by the adhesion of the cooling water, and dust trouble caused by the adhesion of dust and the cooling water can be prevented. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 and FIG.
Is the gas 1 whose internal ventilation path 12 is to be cooled, such as exhaust gas.
The gas 13 forms an ascending flow while circulating in the ventilation path 12 and circulates. The outer tower 11 has a top part in communication with a bag filter (not shown) at a later stage, and a loader valve 14 is provided at the bottom part. An inner tower 15 is arranged concentrically below the outer tower 11, and an annular gap 16 is provided between the inner tower 15 and the outer tower 11. The outer tower 11 and the inner tower 15 are the inner tower 1
5 is 0.55 to 0.6 of the inner diameter φD of the outer tower 11.
It is formed so as to be five times. The upper end side of the inner tower 15 is provided with a guide portion 17 whose diameter is widened upward and the upper end edge of the guide portion 17 is joined to the inner peripheral surface of the outer tower 11 to close the upper end side of the gap 16. The lower end of the gap 16 forms an opening. A gas supply pipe 18 for introducing the gas 13 is connected to the outer tower 11, and the gas supply pipe 18 communicates with a gap 16 between the outer tower 11 and the inner tower 15, and extends in a tangential direction of the tower wall. The gas supply port 18a is open. A plurality of cooling water spray nozzles 19 project through the outer tower 11 and the inner tower 15 in the uppermost part of the inner tower 15, and each cooling water spray nozzle 19 extends in the circumferential direction of the inner tower 15. They are provided at regular intervals along. Each cooling water spray nozzle 1
The nozzle opening 20 of 9 is located near the wall surface about 300 mm away from the inner surface of the inner tower 15 and faces obliquely upward so that the spray direction of the cooling water 21 has an elevation angle of about 60 ° with respect to the horizontal. The nozzle opening 20 is provided with a plurality of fine nozzle holes. The operation of the above configuration will be described below. Low-temperature gas 13 of 200 to 300 ° C. as a cooling target 13
Is supplied through a supply pipe 18. The gas 13 is jetted from the gas supply port 18a to the gap 16 between the outer tower 11 and the inner tower 15 in a tangential direction, and swirls along the inner peripheral surface of the outer tower 11 to open the gap 16 at the lower opening. It flows as a downward flow toward. The gas flow that has reached the open port flows into the inside of the inner tower 15 from the lower end opening of the inner tower 15, turns upward, and swirls along the inner peripheral surface of the inner tower 15 to flow as an ascending flow. 1
5 flows into the ventilation path 12 of the outer tower 11 while turning. At this time, the outer layer of the gas flow swirling smaller than the inner diameter of the outer tower 11 near the upper end opening of the inner tower 15 is directed upward from the nozzle openings 20 of the plurality of cooling water spray nozzles 19. To spray the cooling water 21. Cooling water 2
The particles 1 are dispersed by the swirling flow of the gas 13 into fine particles and diffuse widely in the gas flow, and the fine particles rise together with the gas flow in the ventilation passage 12 of the outer tower 11 toward the top of the tower. I do. During this time, the fine particles of the cooling water 21
The gas 13 evaporates by depriving it of heat as latent heat and cools the gas 13 to a set temperature range (140 to 170 ° C.). In the above operation, the flow state of the gas flow in the outer tower 11 changes depending on the size of the inner diameter φd of the inner tower 15. The inner diameter φd of the inner tower 15 is 0.
If it is too small, 55 times or less, the gas flow is
And the gas flow with the particles of cooling water locally contacts the inner surface of the outer tower, causing dust trouble. Conversely, if the inner diameter φd of the inner tower is too large at least 0.65 times the inner diameter φD of the outer tower, a downward flow is generated on the center side of the inner tower 15, and the sprayed cooling water 21 is accompanied by the downward flow. The inner tower 15 descends. For this reason, the inner diameter φd of the inner tower 15 is
By 0.55 to 0.65 times the inner diameter φD of the outer tower 11, it is possible to make the flow state of the gas flow in the outer tower 11 a uniform swirling flow whose swirling axis coincides with the center line of the outer tower 11. While the gas flow rises up the ventilation path 12 of the outer tower 11, the fine particles of the cooling water 21 rise on the center side of the outer tower 11 while expanding the swirling diameter, and do not reach the inner surface of the outer tower 11. Reach the top. Therefore, the inner surface of the outer tower 11 is
1 does not get wet, and dust trouble caused by dust adhering together with the cooling water 21 can be prevented. The particles of the cooling water 13 sprayed on the outer layer of the gas flow near the upper end opening of the inner tower 15 act as a load on the gas flow of the outer layer, and reduce the swirling force of the outer layer of the gas flow. Therefore, the gas flow in the ventilation path 12 of the outer tower 11 has a weak swirling force in the outer layer and a strong upward force in the inner layer near the center of the tower. According to Lagrange's equation, the particles of the cooling water 21 deprive the gas flow of the swirling force as the point where the cooling water 21 is sprayed is located outside the swirling flow. For this purpose, the gas flow is controlled by the ventilation passage 1 of the outer tower 11.
During the ascent, the fine particles of the cooling water 21 slightly swirl in the first half, ascend the center of the outer tower 11 while widening the swirling diameter, and in the second half, lose their swirling force and rise straight up. It reaches the top of the tower without reaching the inner surface of the tower 11. Therefore, the inner diameter φd of the inner tower 15 is
1 is formed to be 0.55 to 0.65 times the inner diameter φD, and further, by spraying the cooling water 21 on the outer layer of the gas flow, the gas flow surely rises on the center side of the outer tower 11. In addition, the inner surface of the outer tower 11 does not get wet due to the adhesion of the cooling water 21, and it is possible to prevent dust trouble caused by dust adhering together with the cooling water 21. Further, since the cooling water 21 is sprayed uniformly from the nozzle openings 20 of the plurality of cooling water spray nozzles 19, the amount of water required to cool the gas 13 to the set temperature range is sprayed uniformly. The amount of water sprayed in the water spray nozzle 19 per unit time is reduced. For this reason, the number of nozzle holes in the nozzle opening 20 of the cooling water spray nozzle 19 is increased and the diameter thereof is formed small, so that the cooling water 21 can be sprayed as small particles, and the total surface of the cooling water 21 can be sprayed. Is increased, the heat absorption efficiency is enhanced, and the cooling water 21 can be completely evaporated even in a low temperature range. As described above, according to the present invention, by forming the inner diameter φd of the inner tower to be 0.55 to 0.65 times the inner diameter φD of the outer tower, the gas flow in the outer tower can be improved. Can be a uniform swirl flow with the swirl axis coinciding with the center line of the outer tower, and the fine particles of cooling water accompanying the gas flow keep the center side of the outer tower while expanding the swirl diameter. It rises and reaches the top of the tower without reaching the inner surface of the outer tower, and the inner surface of the outer tower does not get wet due to the adhesion of the cooling water, thereby preventing dust trouble caused by dust adhering together with the cooling water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing a low-temperature region gas cooling tower according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a cross section of a low-temperature region gas cooling tower according to the embodiment. FIG. 3 is a block diagram showing a configuration of a conventional incineration facility. [Description of Signs] 11 Outer tower 12 Ventilation passage 13 Gas 15 Inner tower 18 Gas supply pipe 18a Gas supply port 19 Cooling water spray nozzle 20 Nozzle port φd Inner tower inner diameter φD Outer tower inner diameter

Continuation of the front page (72) Inventor Shiro Nakai 2-47, Shikitsuhigashi, Namiwa-ku, Osaka-shi, Osaka Kubota Co., Ltd. (56) References JP-A-6-63351 (JP, A) Japanese Patent Publication Sho44 −20718 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23J 15/00-15/08 B01D 53/34 F28C 3/08

Claims (1)

(57) [Claims 1] An outer tower in which an internal ventilation path forms a cooling space for a gas to be cooled, and the gas flows upwards while circulating in the ventilation path, The inner tower is arranged concentrically inside the lower part of the outer tower, the upper end side of the annular gap formed between the inner tower and the outer tower is closed, and the tangential direction of the tower wall between the outer tower and the inner tower Forming a gas supply port opening toward the inner tower, providing a cooling water spray nozzle inside the upper part of the inner tower, and forming the inner diameter φd of the inner tower to be 0.55 to 0.65 times the inner diameter φD of the outer tower. Low-temperature gas cooling tower.