JPH0534457U - White smoke prevention device in cooling tower - Google Patents

Abstract

(57) [Summary] [Purpose] A wet heat exchanger is provided which supplies treated water to be cooled to a filler from above and allows external air to pass through in a perpendicular direction. [Structure] Wet heat exchangers 3 and 4 are provided for supplying treated water to be cooled from above to fillers 5 and 6 housed in a tower body and allowing external air to pass from the side in a direction orthogonal to each other. Filler 5,6
Dry heat exchangers 21 and 22 in which hot water to be cooled and external air are not in contact with each other are provided in the vicinity of the rear of the air circulation.
The dry heat exchangers 21 and 22 are provided with the moving device 41. Then, the air that has passed through the fillers 5 and 6 in the vicinity of the fillers 5 and 6 is circulated to enable the selective transfer to the white smoke generation preventing position and the retreat position of the central space portion of the cooling tower 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a white smoke prevention device in a cross flow type cooling tower equipped with a wet heat exchanger that supplies treated water to be cooled to a filler from above and allows external air to pass through at right angles.

[0002]

[Prior Art]

 Generally, in a cooling tower, a wet heat exchanger, in which the treated water and the outside air come into direct contact with each other on the surface of the filler, has a good heat exchange rate, but the exhaust gas discharged from the intake fan has high humidity and the outside air temperature is high during the summer. There is no problem, but when the outside air temperature is low such as in winter, the humidity reaches saturation and is emitted as white smoke, which is a problem. For this reason, various white smoke prevention means have been tried, one example of which is shown in FIGS. 8 and 9.

The cooling tower 50 includes wet heat exchangers 51a and 51b on the left and right, and dry heat exchangers 52a and 52b that do not directly contact the treated water and the cooling air above the heat exchangers 51a and 51b, respectively. Deploy. Reference numeral 53 is a switching valve for selecting treated water for the dry heat exchanger, and 54 is an exhaust fan. In this method, when the curve ψ is a saturation curve as shown in FIG. 9, the temperature and humidity of the outside air is a, and the temperature and humidity when passing through the lower filler is b (however, the humidity is in a saturated state, and therefore the saturation curve is (Above), 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 passing 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 the line segment bd. This is the upper point e 1, which causes the line segment ae to be located below the saturation curve ψ and prevents the generation of white smoke.

[0004]

[Problems to be solved by the device]

 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. In addition, the upper and lower heat exchangers are installed. The problem is that the height of the device becomes large.

The present invention has been made in view of the above points, and a dry heat exchanger having good heat exchange efficiency is used as a heat exchanger to uniformly heat air passing through a filler to generate white smoke. The purpose is to provide a cooling tower that prevents the generation of the heat and to move the dry heat exchanger from the air circulation passage to the retracted position when the outside air temperature is high and the humidity of the exhaust gas does not need to be adjusted, such as in summer.

[0006]

[Means for Solving the Problems]

 The present invention for achieving the above object is a cross flow type cooling tower equipped with a wet heat exchanger that supplies treated water to be cooled from above to a filler to be stored and allows external air to pass through in a perpendicular direction. A dry heat exchanger was installed near the back of the air flow of the packing material, having a cross-sectional area that was almost the same as this packing material and in which hot water to be cooled and cooling air were not in contact, and passed through the packing material. Air is discharged through the dry heat exchanger, and treated water is selectively supplied to the dry heat exchanger. The dry heat exchanger is equipped with a moving device and passes through the packing material in the vicinity of the packing material. It is possible to selectively move between the white smoke generation prevention position that circulates the generated air and the retracted position in the center of the cooling tower.

[0007]

[Action]

 When there is a risk that the outside air temperature will drop and white smoke will be generated, such as in winter, supply treated water to the dry heat exchanger. As a result, all the air that has passed through the filling material is evenly and uniformly heated through the dry heat exchanger, so that the humidity drops and falls below the saturation curve, which prevents the generation of white smoke. Further, when the outside air temperature is high and it is not necessary to adjust the humidity, such as in the summer, the dry heat exchanger can be retracted from the wet heat exchanger to prevent the back pressure from increasing due to the dry heat exchanger.

[0008]

Embodiments FIGS. 1 to 5 show an embodiment in which a wet heat exchanger and a dry heat exchanger are provided side by side. In this cooling tower 1, wet heat exchangers 3 and 4 are arranged on the left and right inside a tower body 2. These heat exchangers 3 and 4 have fillers 5 and 6, and above them sprinkler gutters 7 and 8 having a large number of spray holes on the lower surface for uniformly spraying the treated water to the filler. An air intake 9 is provided on the side of the tower body 2, and a large number of loopers 10 are attached to this air intake. Reference numeral 11 is an exhaust passage formed in the upper center of the tower, 12 is an exhaust fan provided in the exhaust passage, and 13 is a water tank attached to the bottom of the tower 2.

Reference numeral 20 denotes a white smoke generation preventing device, which is provided behind the fillers 5 and 6, that is, near the rear side of the fillers 5 and 6 in the air flow, and the dry heat exchangers 21 and 22 and the eliminator. It consists of 40. However, both heat exchangers 21 and 22 have the same structure, and only one heat exchanger 21 will be described below. The heat exchanger 21 includes a heat exchange section 23 and a treated water supply trough 24 for supplying treated water to the heat exchange section 23. The heat exchanging portion 23 has a size substantially covering the entire width and height of the fillers 5 and 6, and is composed of a large number of partition plates 25 arranged in parallel with a minute interval. The partition plates 25 are arranged in parallel in parallel with the flow direction of the air passing through the packing material, and each partition plate 25 alternately closes the opposite upper and lower end faces and the front and rear end faces, and the front and rear direction openings serve as air flow passages 27, The opening in the direction serves as a passage 28 for the treated water, and each partition plate bends the vertical cross section in a wavy shape in order to resist the fall of the treated water and increase the contact area. The procedure is shown in FIGS.

That is, a pair of partition plates 25a and 25b is formed as a set, and the upper and lower ends of each partition plate 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 formed. Are joined surfaces p and q, respectively, and the front and rear end surfaces q and q of the opposing partition plates 25a and 25b are joined to form a flow passage 28 for the treated water. The upper and lower end surfaces p of the pair of partition plates are respectively joined to the upper and lower end surfaces of the partition plates adjacent to the pair of partition plates to form a gap therebetween as an air flow passage 27. As the dry heat exchanger of the above-mentioned embodiment, a large number of partition plates constituted by thin film plastic sheet materials are shown in parallel, but a conventionally known closed heat exchanger in which serpentine pipes are arranged in parallel is used. Of course, it is also good.

The treated water supply gutter 24 has a large number of water sprinkling holes formed on the lower surface like the sprinkling gutters 7 and 8 and is formed integrally with the sprinkling gutters 7 and 8 in the example shown in FIG. However, this may be provided separately. Further, when the supply gutter 24 moves along with the dry heat exchangers 41 and 42 as shown in FIG. 6, the flexible tubes 49 and 49 are used as a means for flowing the treated water into the supply gutter 24.

In FIGS. 6 and 7, the dry heat exchangers 21 and 22 are not necessary in seasons when the outside air temperature is high and white smoke is not likely to occur. Moreover, since the eliminator 40 is provided between the filling material and the dry heat exchanger, the air resistance, that is, the pressure loss increases and the air volume decreases. Therefore, it is necessary to improve the specifications of the blower in order to obtain the same performance (one that does not have a dry heat exchanger and an eliminator). The white smoke prevention device 20 of the cooling tower 1 in this embodiment is a movable type of the dry heat exchangers 21 and 22 and the eliminator 40, and a moving device 41 is provided above and below each of the dry heat exchangers 21 and 22. For example, casters 43 and 44 are attached, and white smoke prevention devices (see FIG. 1) near the fillers 5 and 6 along the upper and lower rails 45 and 46 provided in the tower body 2 and the outside air temperature such as summer It is freely movable to the retracted position (see Fig. 6) when the high white smoke prevention device is not required. Further, at each position, it may be fixed by a stop pin or the like (not shown). As a moving method, the driving motors 47 and 48 may be forcibly driven as shown in FIG. 7, or a manual moving method may be used as another method. The other parts have the same structure as the previous example, and the same parts are designated by the same reference numerals and the description thereof is omitted.

Reference numerals 30 and 31 denote electric on-off 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 13, and are provided as necessary. It is a thing. This is because the on-off valves 30 and 31 are normally closed, and when the temperature of the cooled liquid discharged from the water storage tank 13 falls below a predetermined temperature, that is, when it falls below the summer design ambient temperature, it is opened. However, water is supplied to the dry heat exchangers 21 and 22. An external air temperature measuring sensor (not shown) may be used instead of the water temperature measuring sensor. In this case, when the outside air temperature drops below a predetermined temperature, that is, the white smoke generation temperature, the electrically operated on-off valves 30 and 31 are operated. In the figure, reference numerals 34 and 35 are overflow pipes, which regulate the depth of the liquid in the supply trough 24 so as not to exceed a predetermined water load when supplying water to the dry heat exchanger so as to cause an overflow.

In the above-mentioned configuration, the outside air temperature is lowered at the time of severe cold, and the outside air temperature is humidity a point in FIG. 5, and the air passing through the filler rises in temperature due to heat exchange but contains a large amount of moisture. 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 and produces white smoke. At this time, by supplying the treated water to the dry heat exchangers 21 and 22, the temperature of the air passing through the heat exchangers is raised but the humidity is lowered. If this point is designated as point c, the line segment ca becomes the saturation curve ψ or less, 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, it is safe to continue supplying water to the dry heat exchanger, but only on the filler side with a good heat exchange rate. Is preferred and usually stopped. At this time, when the outside air temperature decreases during the night and winter, the temperature of the drainage water from the water storage tank 13 decreases. The temperature sensor 33 detects this, and when the temperature falls below a predetermined temperature, the motor-operated on-off valves 30 and 31 are operated to open the valves and start supplying water to the dry heat exchangers 21 and 22. This can prevent the generation of white smoke.

[0016]

[Effect of the device]

 As described above, according to the present invention, a wet heat exchanger having a high heat exchange rate is used as a cooling tower, and a dry heat exchanger having substantially the same cross-sectional area as that of the filling material is provided in the vicinity of the rear of the filling material and the filling is performed. Since all the air that has passed through the material passes through the dry heat exchanger, it is possible to raise the temperature uniformly without causing uneven mixing of the humidified air and the warmed air as in the conventional case. Therefore, the exhaust humidity becomes less than the saturation humidity, and the generation of white smoke can be reliably prevented. At this time, it is effective that the temperature of the treated water can be lowered by using a dry heat exchanger. Moreover, since the dry heat exchanger is provided inside the wet heat exchanger, the height of the tower can be made the same as the conventional one. Furthermore, since the dry heat exchanger is made movable, it is possible to select and move to a white smoke generation prevention position that raises the temperature of the circulating air that is close to the packing material and a retracted position that is separated from the cooling air flow passage. When the dry heat exchanger is not used, it is possible to prevent the back pressure from increasing due to the dry heat exchanger, and it is not necessary to improve the specifications of the blower in order to solve the decrease in air volume due to the increase in back pressure. It has also become possible to facilitate maintenance and inspection of wet heat exchangers and dry heat exchangers.

[Brief description of drawings]

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

FIG. 2 is a front view of a heat exchange section of a dry heat exchanger.

FIG. 3 is a plan view of a dry heat exchanger.

FIG. 4 is an explanatory view of the procedure for assembling the partition plate of the dry heat exchanger.

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

FIG. 6 is a vertical cross sectional view of the second embodiment.

7 is a sectional view taken along line XX in FIG.

FIG. 8 is a vertical cross-sectional explanatory view of a cooling tower of a conventional example.

FIG. 9 is a diagram for explaining the operation of the conventional example.

[Explanation of symbols]

 1 Cooling Tower 3 Wet Heat Exchanger 4 Wet Heat Exchanger 5 Filler 6 Filler 20 White Smoke Prevention Device 21 Dry Heat Exchanger 22 Dry Heat Exchanger 25 Separator 27 Air Flow Passage 28 Treated Water Flow Passage 30 Open / Close Valve 31 Open / Close Valve 32 Water supply circuit 33 Temperature sensor 40 Eliminator 41 Moving device 43 Castor 44 Castor 45 Rail 46 Rail

Claims (1)

[Scope of utility model registration request] 1. A cross-flow type cooling tower equipped with a wet heat exchanger for supplying treated water to be cooled from above to a packing material housed in a tower body and allowing external air to pass from the side in a direction orthogonal to the packing material. A dry heat exchanger in which hot water to be cooled and external air are not in contact with each other is provided near the rear of the air flow of the material, and the dry heat exchanger is provided with a moving device and is close to the packing material. An apparatus for preventing white smoke in a cooling tower, characterized in that the air that has passed through is circulated to enable selective transfer between a white smoke generation preventing position and a retracting position in the central space of the cooling tower.