JPH0933031A - Temperature reducing tower for low temperature region gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature reducing tower low temperature region gas in which cooling water can be completely evaporated without being contacted with an inner wall of the tower even under an operation performed at a low temperature region. SOLUTION: An inner tower 15 is coaxially arranged in a lower inner side of an outer tower 11, and an upper end side of an annular clearance 16 formed between the inner tower 15 and the outer tower 11 is closed. A gas supplying port opened toward a direction of a tangential line of the tower wall is formed between the outer tower 11 and the inner tower 15. Cooling water atomizing nozzles 19 are arranged at the upper inner side of the inner tower 15, and an inner diameter ϕd of the inner tower 15 is formed to be 0.55 to 0.65 times the inner diameter ϕD of the outer tower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low temperature gas cooling tower for lowering the temperature of exhaust gas discharged from an incinerator of municipal solid waste to a low temperature range.

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG. 3, in an municipal waste incinerator, exhaust gas (800 to 9
(00 ° C.) 2 is guided to the exhaust heat boiler 3 to extract the residual heat in the form of steam, which is used as a heat source for a plant or hot water supply.
In addition, after the exhaust gas 2 is introduced into the gas temperature reduction tower 4 to reduce the temperature,
It guides to the bag filter 5 or an electric dust collector, collects and removes fine soot dust, and then guides it to the chimney 6.

The operation of the gas temperature reducing tower 4 is limited to a medium temperature range or a high temperature range.
The temperature of exhaust gas at 500 ° C is reduced to 250 to 300 ° C, and the exhaust gas at 800 to 900 ° C is reduced to 300 during operation in a high temperature range.
Temperature is reduced to ~ 500 ° C. This is because in the gas temperature reducing tower 4, the exhaust gas of 200 to 300 ° C. is heated to 140 to 170 ° C.
This was because it was difficult to operate in the low temperature range where the temperature decreased to zero.

In the gas cooling tower, cooling water is sprayed into the exhaust gas flowing into the tower, and the cooling water removes heat as latent heat from the exhaust gas and evaporates to cool the exhaust gas. Therefore, when the gas temperature reducing 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 the 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 the limited time when the exhaust gas passed through the tower.

[0005]

Recently, 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 to a bag filter in a low temperature state for filtration. However, when the cooling water does not completely evaporate in the gas temperature reducing tower, the non-evaporated cooling water flows into the bag filter located in the subsequent stage of the gas temperature reducing tower, the filter cloth of the bag filter gets wet, and the wet filter becomes wet. There was a problem that soot and dust stuck to the cloth and clogged.

Further, in the conventional gas cooling tower, since the cooling water is sprayed from the single spray nozzle at the central position of the tower, the amount of water required to cool the exhaust gas to the set temperature is set within the unit time. In order to spray, the particle size of the water drop had to be large. The sprayed cooling water acts as a load on the gas flow, the rising force near the center of the gas flow weakens, and the swirling force in the outer layer of the gas flow strongly acts. Therefore, a downward flow occurs in the center side of the tower and some of the sprayed water droplets drop to the bottom side of the tower, and because the water droplets have a large particle size and are easily subjected to centrifugal force due to the swirling flow, the water droplets There was a problem that it reached the inner peripheral surface of the and the soot dust adhered to the wet wall surface to 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 gas cooling tower in which cooling water is completely evaporated without touching the inner wall of the tower even in operation in the low temperature area.

[0008]

In order to solve the above-mentioned problems, in the low temperature gas reducing tower of the present invention, an internal ventilation passage constitutes a cooling space for the gas to be cooled, and the gas constitutes the ventilation passage. An outer tower that circulates in an upward flow while swirling is provided, the inner tower is concentrically arranged inside the outer tower, and the upper end side of the annular gap formed between the inner tower and the outer tower is closed. Then, a gas supply port that opens in the tangential direction of the tower wall is formed between the outer tower and the inner tower, a cooling water spray nozzle is provided inside the upper side of the inner tower, and the inner diameter φd of the inner tower is set to the inner diameter of the outer tower. φD 0.55 to 0.
It is configured to be formed 65 times.

With the above structure, the gas to be cooled, which is jetted tangentially 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 the gas at the lower end It flows downwards toward the opening. The gas flow reaching the opening enters the inside of the inner tower from the lower end opening of the inner tower and turns upward, and once the diameter of swirl is reduced, it swirls along the inner peripheral surface of the inner tower and becomes an upward flow. Flows from the upper opening of the inner tower into the ventilation passage of the outer tower while swirling.

In the vicinity of the upper end opening of the inner tower, cooling water is sprayed from the cooling water spray nozzle to the swirling gas flow.
The particles of the cooling water are diffused by the swirling flow of the gas to become fine particles and diffuse in a wide range in the gas flow, and the fine particles ascend together with the gas flow toward the tower top through the ventilation passage of the outer tower. During this time, the cooling water takes away the amount of heat from the gas as latent heat and evaporates, cooling the gas to the set temperature range.

In the above operation, the flow state of the gas flow in the outer column changes depending on the size of the inner diameter of the inner column. When the inner diameter φd of the inner tower is too small with respect to the inner diameter φD of the outer tower,
The gas flow becomes a swirl flow in which the swirl axis is off the center of the tower, and the gas flow accompanied by particles of cooling water locally contacts the inner surface of the outer tower, causing dust trouble. On the contrary, when the inner diameter φd of the inner tower is too large with respect to the inner diameter φD of the outer tower, a downflow occurs at the center side of the inner tower, and the sprayed cooling water descends in the inner tower with the downflow.

Therefore, the inner diameter φd of the inner tower is equal to the inner diameter φ of the outer tower.
By forming the gas flow to be 0.55 to 0.65 times D, the flow state of the gas flow in the outer tower can be made a uniform swirl flow with the swirling axis aligned with the center line of the outer tower. Thereby, while the gas flow rises in the ventilation passage of the outer tower, the fine particles of the cooling water rise in 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 does not get wet due to the attachment of the cooling water, and it is possible to prevent dust trouble caused by the attachment of soot dust together with the cooling water.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. 1 to 2, the outer tower 11
Is a gas 1 whose internal ventilation passage 12 is a cooling target such as exhaust gas
3 forms a cooling space, and the gas 13 circulates in the ventilation path 12 as an upward flow while flowing. The top of the outer tower 11 communicates with a bag filter (not shown) at the latter stage, and a loader valve 14 is provided at the bottom of the tower.

An inner tower 15 is concentrically arranged inside 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
The inner diameter φd of 5 is 0.55 to 0.6 of the inner diameter φD of the outer tower 11.
It is formed so as to be 5 times. The upper end side of the inner tower 15 is provided with a guide portion 17 that widens 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 a gas 13 is connected to the outer tower 11, the gas supply pipe 18 communicates with a gap 16 between the outer tower 11 and the inner tower 15, and is directed in a tangential direction of a tower wall. The gas supply port is open at 18a.

A plurality of cooling water spray nozzles 19 project through the outer tower 11 and the inner tower 15 inside 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 equal intervals along the line. Each cooling water spray nozzle 1
The nozzle mouth 20 of 9 is located near the wall surface about 300 mm away from the inner surface of the inner tower 15, and is directed 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. As a cooling target, a low temperature gas of 200 to 300 ° C. 13
Is supplied through the supply pipe 18. The gas 13 is jetted from the gas supply port 18a into 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 end. It flows downward toward. The gas flow reaching the opening enters the inside of the inner tower 15 through the lower end opening of the inner tower 15, turns upward, and swirls along the inner peripheral surface of the inner tower 15 to become an upward flow. 1
It swirls and flows into the ventilation path 12 of the outer tower 11 from the upper opening of 5.

At this time, in the vicinity of the upper end opening of the inner tower 15, the outer layer of the gas flow swirling smaller than the inner diameter of the outer tower 11 is directed upward from the nozzle openings 20 of the plurality of cooling water spray nozzles 19. Then, the cooling water 21 is sprayed. Cooling water 2
The particles of No. 1 are subjected to the diffusion action by the swirling flow of the gas 13 to become fine particles and diffused in a wide range in the gas flow. To do. During this time, the fine particles of the cooling water 21 are
The heat amount is taken from the above as latent heat and evaporated, and the gas 13 is cooled to the set temperature range (140 to 170 ° C.).

In the above operation, the flow state of the gas flow in the outer column 11 changes depending on the inner diameter φd of the inner column 15. The inner diameter φd of the inner tower 15 is 0.
If it is less than 55 times too small, the swirl axis of the gas flow will be 11
It becomes a swirl flow that is off the center, and the gas flow accompanied by particles of cooling water locally contacts the inner surface of the outer tower, causing dust trouble. On the other hand, if the inner diameter φd of the inner tower is 0.65 times or more larger than the inner diameter φD of the outer tower, a downflow occurs at the center side of the inner tower 15, and the sprayed cooling water 21 is accompanied by the downflow. Lower the inner tower 15.

Therefore, the inner diameter φd of the inner tower 15 is set to the outer tower 11
By forming the inner diameter φD of the outer column 11 to be 0.55 to 0.65 times, the gas flow in the outer column 11 can have a uniform swirl flow with the swirling axis aligned with the center line of the outer column 11. While the gas flow rises in the air passage 12 of the outer tower 11, the fine particles of the cooling water 21 rise in 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 the cooling water 2
It is possible to prevent dust trouble caused by soot dust adhering to the cooling water 21 without being wetted by the adherence of 1.

Further, the particles of the cooling water 13 sprayed to 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 in the outer layer of the gas flow. Therefore, the gas flow in the air passage 12 of the outer tower 11 has a weak swirling force in the outer layer and a strong ascending force in the inner layer on the tower center side. According to the Lagrange's equation, the particles of the cooling water 21 deprive the swirling force from the gas flow as the spraying point of the cooling water 21 is outside the swirling flow.

For this reason, the gas flow is in the vent passage 1 of the outer tower 11.
While rising 2, the fine particles of the cooling water 21 swirl somewhat in the first half and rise in the center side of the outer tower 11 while expanding the swirling diameter, and in the latter half, lose the swirling force and go straight up. The tower top is reached without reaching the inner surface of the tower 11.

Therefore, the inner diameter φd of the inner tower 15 is set to the outer tower 1
It is formed to be 0.55 to 0.65 times the inner diameter φD of 1 and further, by spraying the cooling water 21 to the outer layer of the gas flow, the gas flow reliably rises on the center side of the outer tower 11. In addition, the inner surface of the outer tower 11 is not wetted by the adhesion of the cooling water 21, and it is possible to prevent dust trouble caused by soot dust adhering to the cooling water 21.

Further, since the cooling water 21 disperses the amount of water required to cool the gas 13 to the set temperature range from the nozzle openings 20 of the plurality of cooling water spray nozzles 19 and sprays it evenly, one cooling The amount of spray water per unit time in the water spray nozzle 19 decreases. Therefore, the number of nozzle holes in the nozzle mouth portion 20 of the cooling water spray nozzle 19 can be increased and the diameter can be formed to be 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. Becomes larger, the heat absorption efficiency can be improved and the cooling water 21 can be completely evaporated even in the low temperature range.

[0024]

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 flow state of the gas flow in the outer tower can be improved. Can be a uniform swirl flow whose swirl axis coincides with the center line of the outer tower, and fine particles of cooling water accompanying the gas flow rise on the center side of the outer tower while expanding the swirl diameter, The inner surface of the outer tower does not reach the inner surface of the outer 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.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a low temperature gas cooling tower according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a cross section of a low temperature region gas temperature reducing tower in the same embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional incineration facility.

[Explanation of symbols]

 11 Outer Tower 12 Ventilation Channel 13 Gas 15 Inner Tower 18 Gas Supply Pipe 18a Gas Supply Port 19 Cooling Water Spray Nozzle 20 Nozzle Portion φd Inner Diameter of Inner Tower φD Inner Diameter of Outer Tower

Claims (1)

[Claims] 1. An inner tower forms a cooling space for a gas to be cooled, and an outer tower is provided through which the gas flows as an upward flow while swirling through the air passage, and the inner tower is provided below the outer tower. Are concentrically arranged, and the upper end of the annular gap formed between the inner tower and the outer tower is closed, and a gas supply port that opens in the tangential direction of the tower wall is provided between the outer tower and the inner tower. And a cooling water spray nozzle provided inside the upper side of the inner tower, and the inner diameter φd of the inner tower is 0.55 to 0.65 times the inner diameter φD of the outer tower. .