JPH0587468A - White smoke pre ventive device and heat exchanger in cooling tower - Google Patents

Abstract

PURPOSE:To prevent the white smoke generated from a cooling tower. CONSTITUTION:Processed water that is to be cooled is poured from above to the filling materials 3 and 4 received in the tower body and the outside air is made to go through sideways and perpendicularly to the water. And dry type heat exchangers 13, 14 near the inside of the filling materials 3, 4 that are behind the air flow are provided, keeping the warm water to be cooled and the outside air from making contact mutually. The processed water is supplied to the dry type heat exchangers 13, 14 when the outside temperature falls below the temperature at which the white smoke is generated and the air that passes through the filling materials 3, 4 is heated. All the air passing through the filling materials 3, 4 goes through the dry type heat exchangers 13, 14 and they can heat the air uniformly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white smoke prevention device and heat exchange in a cross-flow type cooling tower in which treated water to be cooled is supplied from above to a packing material contained in a tower body and external air is allowed to pass through at right angles. It is related to vessels.

[0002]

2. Description of the Related Art Generally, in a cooling tower, a wet heat exchanger in which treated water and external air are in direct contact with each other on the surface of a filler has a good heat exchange rate, but the exhaust gas discharged from an intake fan has a high humidity and the outside air There is no problem in the summer when the temperature is high, but when the outside temperature is low such as in winter, the humidity reaches a saturated state and is emitted as white smoke, which is a problem.
For this reason, various white smoke preventing means have been tried, and one example thereof is shown in FIG.

In this cooling tower 50, left and right heat exchangers 51 and 52 are divided into upper and lower parts, respectively, and an upper heat exchanger 5 is provided.
1a, 52a, lower heat exchangers 51b, 52b, the upper heat exchanger is a pipe type closed heat exchanger in which treated water does not come into direct contact with the outside air, and the lower heat exchanger is filled with a good heat exchange rate. A wet heat exchanger in which the treated water from the material and the external air come into direct contact. In winter, the treated water opens the on-off valve 53 and is supplied to both upper and lower fillers to be cooled.

In the case of this system, when the curve ψ is a saturation curve as shown in FIG. 8, the temperature and humidity of the outside air are a, and the temperature and humidity when passing through the lower filler are b (however, the humidity is in a saturated state. (Above the saturation curve), the line segment ab is located above the saturation curve ψ, and this portion becomes white smoke. At this time, if the temperature and humidity of the air that has passed through the upper dry heat exchanger is d at the same time, this air humidity is low in the outside air humidity, and therefore the temperature and humidity of the exhaust gas mixed and discharged from the exhaust fan 54 is on the line segment bd. The line segment ae is located below the saturation curve ψ, and the generation of white smoke is prevented.

[0005]

However, with this method, it is difficult to sufficiently mix the air that has passed through the upper and lower heat exchangers, and it is not possible to reliably prevent the generation of white smoke. Providing the two-stage heat exchanger has a problem that the height of the apparatus becomes large.

The present invention has been made in view of the above points, and a cooling tower which uses a filler having a good heat exchange rate as a heat exchanger and which does not divide into upper and lower parts to prevent generation of white smoke even in winter. The purpose is to provide. Another invention has a large heat transfer area as a heat exchanger,
An object of the present invention is to provide a heat exchanger that uses a film-like sheet that can be made thin and does not bring treated water into contact with external air and has a good heat exchange rate.

[0007]

According to the present invention for achieving the above object, in the cross flow type cooling tower, the hot water and the external air to be cooled are provided in the vicinity of the inner side of the air circulation rear side of the filler. A dry heat exchanger in contact is provided, and treated water is selectively supplied to the dry heat exchanger.

According to a second aspect of the invention, an on-off valve is provided in the water supply circuit to the dry heat exchanger, and the on-off valve of the on-off valve is controlled according to the temperature measured by the temperature measuring sensor for the treated liquid in the cooling tower or the ambient temperature / humidity sensor. By opening and closing, the treated water is selected and supplied to the dry heat exchanger.

According to a third invention, the dry heat exchanger is
A large number of partition plates are arranged vertically with a minute gap, and the gaps are alternately closed by closing the upper and lower ends and the front and rear stages, and the gap with the front and rear ends opened is the air circulation passage, and the gap with the upper and lower ends opened. The treated water flow passage is used, and each partition plate is made of a thin film plastic material.

[0010]

[Function] When there is a possibility that white smoke is generated due to a decrease in outside air temperature such as in winter, treated water is supplied to the dry heat exchanger. As a result, all the air that has passed through the filler passes through the dry heat exchanger and is uniformly and uniformly heated. Therefore, the humidity is lowered and becomes lower than the saturation curve, so that the generation of white smoke can be prevented. The dry heat exchanger is designed to cool the treated water without directly contacting the cooling air, and the cooling air is orthogonal to the treated water and flows through the back side of the partition wall to cool the partition wall. That is, the treated water is cooled via the partition wall. At this time, since the partition wall is made of a thin film plastic material, the heat conduction efficiency is good.

[0011]

1 to 6 show an embodiment of the present invention. This cooling tower 1 is provided with fillers 3 and 4 on the left and right sides in a tower body 2, and above the sprinkler gutter having a large number of sprinkling holes on its lower surface for uniformly spraying the treated water to the filler. 5,
6, an exhaust passage 7 is formed in the upper center of the tower body, and an exhaust fan 8 is arranged in the exhaust passage 7. Reference numeral 9 denotes an air intake port opened on the side of the tower body, to which a large number of loopers 10 are attached as is well known. Reference numeral 11 is a water storage tank provided at the bottom of the tower.

Numeral 12 is a white smoke prevention device, which is provided behind the fillers 3 and 4, that is, on the rear side of the filler in the air flow direction, and dry heat exchangers 13 and 14, and above the respective heat exchangers. The treated water sprinkling gutters 15 and 16 are provided.

The dry heat exchangers 13 and 14 are designed to cool the treated water without directly contacting the outside air. The left and right heat exchangers 13 and 14 have the same structure. The exchanger 13 will be described. This heat exchanger 1
Numeral 3 is a pair of two partition plates 20 that face each other with a minute gap.
a, 20b (hereinafter, simply referred to as 20 when collectively referred to) are provided in parallel, and each partition plate 20 is made of a thin film plastic material and is parallel to the air flow direction. Then, the upper and lower ends of each partition plate 20 are expanded outward, and the front and rear ends are bent inward in the opposite direction over the entire length, and the upper and lower end faces and the front and rear end faces are joined faces a and b, respectively.
The front and rear end faces b, b of the two partition plates 20a, 20b are joined to form a flow passage 22 for the treated water.

Between adjacent unit elements 3a, upper and lower joint surfaces a, a are joined to form a gap between the unit elements 3a, 3a as an air passage 21, and each partition plate 20 drops treated water. In order to increase the contact area and the resistance to, the bent portion 23 in which the vertical cross section is bent in a wave shape is formed, and the zigzag portion 24 having a fine pattern in the horizontal direction is formed in the horizontal direction so that the treated water extends in the horizontal direction. Improves distribution and retention.

In the above structure, the humidified treated water W supplied from the sprinkling gutters 15 and 16 is the heat exchangers 13 and 14.
6 through the corrugated bent portions 23 and the chevron-shaped zigzag portions 24 formed in each partition plate 20.
At the point of, the arrow moves to the opposing partition plate side as indicated by the arrow P, and falls along the surface of the partition plate. On the other hand, the cooling air is sucked into the cooling tower through the air passage 22 at right angles to the processing liquid. Thereby, the partition plate 20 heated by the processing liquid is cooled by the cooling air. That is, the treatment liquid is cooled by the cooling air through the partition plate. In this case, since the partition plate 20 is made of a thin film plastic material,
Since the heat transfer sheet can be made thicker in the form of a film, it is possible to increase the heat transfer area and improve heat exchange efficiency.

The water sprinkling gutters 15 and 16 have a plurality of water sprinkling holes formed on the lower surface similarly to the well-known structure. In the illustrated example, the water spouting gutters 5 and 6 for the fillers 3 and 4 are integrally formed with the partition wall 25. , 26 is shown as an example of partitioning, but this may be provided separately.

Further, reference numerals 30 and 31 designate electric open / close valves provided in the treated water supply circuit 32, which are operated by a temperature sensor 33 for measuring the water temperature of the cooling liquid discharged from the water storage tank 11, and are also provided if necessary. It may be operated by an external air temperature / humidity sensor provided. The on-off valves 30 and 31 are normally closed, and when the temperature of the cooled liquid discharged from the water storage tank 11 or the outside air temperature / humidity drops below a predetermined temperature in winter, that is, below the summer design outside air temperature. This is opened to supply water to the dry heat exchangers 13 and 14. In the figure, reference numerals 34 and 35 are overflow pipes which, when supplying water to the dry heat exchanger, regulate the depth of the liquid in the sprinkler tank so that the water does not exceed a predetermined water load and overflow.

In the above structure, the outside air temperature is lowered in a severe cold, the outside air temperature humidity is set to point a in FIG. 5, and the temperature of the air passing through the filler is increased by heat exchange, but a large amount of water is contained. The point b is the temperature and humidity of the air that has passed through the filler. This point is on the saturation curve ψ when the water content is saturated as described above, and therefore the line segment ab exceeds the saturation curve ψ to generate white smoke. At this time, by supplying treated water to the dry heat exchangers 13 and 14, the temperature of the air passing through the heat exchangers is raised but the humidity thereof is lowered. If this point is set as point c, the line segment bc becomes equal to or less than the saturation curve ψ, and white smoke can be prevented from being generated.

When the outside air temperature is relatively high and white smoke is not likely to occur, the water supply to the dry heat exchanger may be continued, but it is performed on the filler side having a good heat exchange rate. Is preferred and usually stopped. When the outside air temperature drops at night and in winter, the temperature of the drainage water from the water storage tank 11 drops. The temperature sensor 33 or the outside air temperature / humidity sensor detects this, and when the temperature falls below a predetermined temperature, the electrically operated on-off valve 3
0, 31 is operated and the valve is opened to dry heat exchangers 13, 14
To supply water to. This can prevent the generation of white smoke.

[0020]

As described above, according to the first aspect of the present invention,
Since the dry heat exchanger is placed close to the rear of the wet heat exchanger with the filler having a high heat exchange rate, all the air that has passed through the filler passes through the dry heat exchanger, so the temperature rises uniformly. be able to. Therefore, the exhaust humidity becomes equal to or lower than the saturation humidity, and the generation of white smoke can be reliably prevented. At this time, since the treated water is supplied to the dry heat exchanger, it is effective that the temperature of the treated water can be lowered also by the dry heat exchanger. Further, since the dry heat exchanger is provided inside the wet heat exchanger, the tower body can have the same height as the conventional one.

According to the second aspect of the invention, an on-off valve is provided in the water supply circuit of the dry heat exchanger to measure the temperature of the treated liquid from the water storage tank or when the outside air temperature / humidity falls below a set value. Since the on-off valve is opened to supply the high-temperature treated water to the dry heat exchanger, white smoke can be automatically prevented.

According to the third aspect of the invention, in the dry heat exchanger, a large number of partition plates are arranged vertically with a minute gap, and the gap is alternately used as an air passage and a treated water passage, In addition, since each partition plate has a vertical cross section bent in a wavy shape, the structure is simple and the heat exchange rate can be improved. Further, since the partition plate is made of a thin film material, the heat conduction is good, and the heat exchanger is composed of a large number of plate-shaped partition plates arranged in parallel with each other at a minute interval. Since a large number of partition plates can be accommodated in the mounting space, the heat transfer area can be increased and the heat exchange efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross sectional explanatory view of a first embodiment.

FIG. 2 is an explanatory diagram of a method of assembling a partition plate in a dry heat exchanger.

FIG. 3 is a vertical cross-sectional view of a dry heat exchanger.

FIG. 4 is a plan view of a dry heat exchanger.

FIG. 5 is an explanatory view of the operation of the present invention.

FIG. 6 is a front view of a unit element of a dry heat exchanger.

FIG. 7 is a vertical cross-sectional explanatory view of a cooling tower of a conventional example.

FIG. 8 is an operation explanatory view of a conventional example.

[Explanation of symbols]

 1 Cooling Tower 3 Filling Material 4 Filling Material 12 White Smoke Prevention Device 13 Dry Heat Exchanger 14 Dry Heat Exchanger 20 Separator 21 Air Flow Gap 22 Treated Water Flow Gap 23 Bent Part 24 Zig Zag 30 Open / Close Valve 31 Open / Close Valve 32 Treated Water Circuit 33 Temperature sensor

Claims (3)

[Claims] 1. A cross-flow type cooling tower in which treated water to be cooled is supplied from above to a packing material contained in a tower body and external air is allowed to pass from the side in a direction orthogonal to the inside of the packing material in the air circulation rear side. A white smoke prevention device in a cooling tower, characterized in that a dry heat exchanger in which hot water to be cooled and external air are not in contact with each other is provided, and treated water is selectively supplied to the dry heat exchanger. 2. A water supply circuit to the dry heat exchanger is provided with an on-off valve, and the opening degree of the on-off valve is controlled by a temperature measuring sensor for the treated liquid in the cooling tower or a temperature measured by an outside air temperature / humidity sensor. The white smoke prevention device in the cooling tower according to claim 1. 3. A heat exchanger of a cross-flow type cooling tower in which treated water to be cooled is supplied from above to a packing material contained in a tower body, and external air is allowed to pass through from a lateral direction so that a large number of partition plates are provided. It is arranged vertically with a minute gap and parallel to the external air circulation direction. Each gap is alternately closed at the upper and lower ends and front and rear ends, and the gap with the front and rear ends opened is the air circulation passage and the upper and lower ends. A heat exchanger in a cooling tower, wherein the open space is used as a treated water flow passage, the partition plate is made of a thin film plastic material, and the vertical cross section is bent in a wave shape.