JP3257466B2 - Water spraying method of cooling tower and cooling tower equipped with water spraying device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a municipal solid waste incineration plant,
The present invention relates to a water spraying method and a water spraying method in a cooling tower that spray-cools exhaust gas discharged from an incinerator or the like in a combustible waste treatment facility by a spray nozzle without generating wastewater.

[0002]

2. Description of the Related Art High-temperature exhaust gas of 800 ° C. or higher discharged from an incinerator or the like is heated to 250 to 350 ° C. by a thermal energy recovery means such as a boiler or an economizer or a water injection type cooling tower utilizing latent heat of vaporization of water. The temperature was reduced to a certain extent, and it was introduced into a dust collector such as an electric dust collector at a later stage and was processed. However, it has become known in recent years that dioxins, which are highly toxic, are generated at temperatures around 300 ° C. in waste incineration, and dust collection at around 300 ° C. has been avoided.
Low-temperature dust collection using a pug filter at 200 ° C. or lower is becoming mainstream.

In order to reduce the temperature of exhaust gas to 200 ° C. or lower, a method of further reducing the temperature of exhaust gas of about 250 to 350 ° C. recovered by heat from a boiler or the like, for example, by spraying water using a spray nozzle is used. . That is, there is an increasing number of cases in which a cooling tower is installed between a boiler and a dust collector, and the temperature is reduced to 200 ° C. or less where generation of dioxins is small.

Conventionally, when exhaust gas is cooled using a spray nozzle in a cooling tower, as shown in FIG. 9, the spray nozzle is perpendicular to the flow of the exhaust gas (gas to be cooled) (FIG. 9 (a)).
(JP-A-61-107925) or parallel (FIG. 9)
(B)) It was installed on the side wall of the temperature-reducing tower so that it became (actually open 59-120333). Further, continuous spraying was performed while the spray nozzle was fixed without being driven.

[0005]

However, in the prior art in which the water spray by the spray nozzle is made perpendicular to the exhaust gas flow, the water spray flow by the spray nozzle is conveyed to the exhaust gas during the transportation to the exhaust gas. At this time, the non-evaporated water droplets of the water spray flow form a wet surface on the inner wall, which causes problems such as corrosion of the device, accumulation of wet dust, and difficulty in discharging the dust. At this time, if a spray nozzle is installed on the opposite side, the water spray flow is concentrated at the center of the tower cross section due to the interaction of the spray nozzles. The water spray stream is concentrated to form a region where the water vapor concentration is extremely high and the temperature is low. As described above, in a region where the water vapor concentration is extremely high and the temperature is low, the water vapor becomes supersaturated, and it becomes difficult for water droplets to evaporate effectively, leading to a large number of unevaporated water droplets. Similarly, problems such as corrosion of the device, accumulation of wet dust, etc. will occur.

Next, in the prior art in which water spray by the spray nozzle is performed in parallel with the flow of exhaust gas, the water spray flow by the spray nozzle is sprayed with a dispersion angle.
The end stream of the water spray flow reaches the inner wall in the process of being conveyed to the exhaust gas, and has caused the same problem as described above, in which the inner wall forms a wet surface due to unevaporated water droplets.

Further, in the prior art in which continuous spraying is performed without driving the spray nozzle while being fixed, evaporation is activated in the vicinity of spraying, and the evaporation area of sprayed water droplets in the tower is limited and fixed. . That is, the high-temperature region and the low-temperature region are divided and fixed in the tower, and as a result, the contact between the spray water droplets and the exhaust gas has not been effectively performed in the entire space in the tower. For this reason, in the low-temperature region near the water spray, the water vapor concentration is high and the temperature is low, so that water droplets in the spray and water in the exhaust gas are condensed, and the dust contained in the exhaust gas becomes wet as described above. It adheres and accumulates on walls, near spray nozzles, and dust discharge areas, causing problems such as corrosion of equipment due to acid gas induced by wetness, generation of scale due to dust accumulation in the tower, and difficulty in dust emission. Was.

[0008] These problems have become more prominent as the dust collection temperature has been lowered in recent years. The present invention provides a water spray method and apparatus in a cooling tower that can cope with a low dust collection temperature and can overcome the above problems.

[0009]

Means for Solving the Problems In order to prevent the formation of a biased low-temperature region in a cooling tower and to achieve effective complete evaporation of spray water droplets, the following means have been invented. First, in a cooling tower in which exhaust gas is cooled by water spray without generating wastewater, a) using a spray nozzle in which a dispersion angle α of a water droplet spray flow by a spray nozzle is 90 ° or less in a specific cross section, b) A plurality of spray nozzles are installed along the circumferential direction of the cross section of the tower so as to be horizontal to the specific cross section and the flow direction of the exhaust gas to be cooled. Angle of elevation β from α / 2 to (90−α / 2) degrees, -α
/ 2--(90-α / 2) degrees, the spray nozzle is installed with the same elevation angle β, d) the spray nozzle tip protrudes from the inner wall by a predetermined length, and e) A water spray method for a cooling tower, wherein water spray is performed by the spray nozzle.

As described above, when the exhaust gas flow to be cooled is an upward flow, an elevation angle β (α / 2 <β <(9
0-α / 2)), it is possible to prevent the water spray flow from being excessively concentrated at the center of the cross section and to form a low-temperature region having a high water vapor density. Both effects are obtained which can prevent the flow from reaching the inner wall and forming a wetted surface.

When the elevation angle β, which is the installation angle of the spray nozzle, is set to α / 2 or less, the lower stream of the water spray stream collides head-on with the lower stream of the water spray stream of another spray nozzle, and a low-temperature region having a high water vapor density is formed. It is not preferable because it causes problems such as condensation of unevaporated water droplets in a low-temperature region, corrosion of equipment, and accumulation of wet dust.

When the elevation angle β is (90−α / 2) or more, the end stream of the water spray flow reaches the inner wall on the side where the spray nozzle is installed, and a wet surface is formed. It is not preferable because it causes problems such as corrosion of water and accumulation of wet dust.

When the exhaust gas to be cooled is a downward flow, only the elevation angle β becomes negative, and the relative positional relationship between the exhaust gas flow and the water spray flow is the same as that in the case of the upward flow. Obviously, it is possible to obtain

A second aspect of the present invention is the water spraying method for a cooling tower, wherein the elevation angle β of the spray nozzle is obtained by bending the tip of the spray nozzle. Since the spray nozzle is bent and the elevation angle β of the water spray is obtained in the same manner, the same operation as in the first invention is obtained.

A third aspect of the present invention is a water spraying method for a cooling tower, wherein the plurality of spray nozzles are arranged at positions where two or more axes of linear symmetry exist in the same cross section. is there.

As described above, when a plurality of spray nozzles are arranged at positions where two or more line symmetry axes exist in one cross section, the symmetry of the water spray flow is obtained, and the water spray flow is opposed to the inner wall of the tower. Can be prevented from forming a wet surface on the inner wall due to collision with the inner wall. In such an arrangement, if the installation angle (elevation angle β) of the spray nozzle is set or the tip is bent, the effects of the first and second inventions can be obtained effectively.
The arrangement in which two or more line symmetry axes exist is, for example, to arrange two spray nozzles at opposing positions or to arrange three spray nozzles at equal intervals in the circumferential direction. This will be described in an embodiment of the invention.

A fourth aspect of the present invention is the water spraying method for a cooling tower according to any one of the first to third aspects, wherein the tip of the spray nozzle is projected more than 30 cm from the inner wall. As described above, by setting the projecting length of the tip portion of the spray nozzle to 30 cm or more, it is possible to prevent the end flow of the water spray flow from reaching the inner wall on the side where the spray nozzle is installed. If the diameter is 30 cm or less, the possibility that a part of the water spray flow reaches the inner wall to form a wet surface due to fluctuation or deviation of the flow of the exhaust gas to be cooled in the tower is not preferable. However, in the case where the exhaust gas flow does not fluctuate and is well rectified, the operation of the first invention can be obtained similarly if the protrusion length is 30 cm or less and some protrusion length is secured. . .

Fifth, in one of the first to fourth aspects, water spraying is performed while at least one of the plurality of spray nozzles is reciprocally driven toward the center of the tower section. It is a water spray method for a hot tower.

As described above, the water spray is performed while the spray nozzle is reciprocated toward the center of the tower cross section while having the elevation angle β, so that the spray flow of the water droplets by the spray nozzle is forcibly moved, and It is possible to prevent a low temperature region from being formed for a long time. That is, since it is possible to prevent the low-temperature region from being formed for a long time, the spray water is effectively evaporated, and problems such as corrosion of the device and accumulation of wet dust caused by condensation of moisture in the low-temperature region can be solved. Therefore, the effects of the first to fourth inventions can be obtained more effectively.

Sixth, when driving the spray nozzle, the time when the projection length of the spray nozzle is from the minimum to the maximum, or half the time of the reciprocating drive cycle, is set in the cooling tower. A water spray method for a cooling tower, wherein the average residence time of exhaust gas is 1 to 10 times.

As described above, in the fifth aspect, the time when the projection length of the spray nozzle is from the minimum to the maximum, or the half of the reciprocating drive cycle is set to one to one of the residence time of the exhaust gas.
Since it is 10 times, the gas flow in the cooling tower can be effectively changed, and the formation time of the temporary low-temperature region does not occur due to the condensation of water and the accumulation of wet dust associated therewith. It is possible to suppress in the range.

If the residence time of the exhaust gas is within one time, the residence time in the tower is usually about 2 to 10 seconds. Therefore, the spray nozzle must be frequently driven, and mechanical energy is wastefully consumed. That is, the convection time of the exhaust gas, that is, the time from the time when the exhaust gas is introduced into the cooling tower to the time when it is discharged from the outlet, is changed even if the projection length of the spray nozzle is changed. This is not preferable because the effect of offsetting the low-temperature region due to the exchange of the high-temperature region and the high-temperature region does not particularly increase.

On the other hand, if it is 10 times or more, the operation of changing the protruding length of the spray nozzle is performed at a sufficient time interval, so that a low-temperature region in the tower is formed for a long time, and the It is not preferable because a sufficient amount of time elapses to cause a problem of condensation and the accompanying accumulation of wet dust. However, the effect is relatively small even outside this range, but it is clear that the effect of the fifth invention of driving the spray nozzle can be obtained.

Seventh, in a cooling tower for cooling exhaust gas by water spray without generating wastewater, a spray nozzle according to any one of claims 1 to 6, and the spray nozzle is driven in the direction of the center of the cross section of the tower. And a driving device for causing the temperature to be reduced.

As described above, by equipping the cooling tower with the spray nozzle and the spray nozzle driving device that satisfies one of the first to sixth requirements, it is possible to cope with the low dust collection temperature and trouble. An excellent temperature-reducing tower free of generation of water is easily obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 8 are views showing an embodiment relating to a water spraying method and apparatus according to the present invention. Here, 1 is a cooling tower (body part), 2 is an exhaust gas introduction duct,
3 is an exhaust gas discharge duct, 4 is a dust collecting hopper, 5 is a dust discharge unit, 6 is a spray nozzle, 7 is a driving device, 8
Is a water spray flow, 9 is a water supply pipe, and 10 is an air supply pipe.

An embodiment of the present invention will be described below with reference to FIGS. Exhaust gas having a temperature of 200 ° C. or higher after being discharged from an incinerator or the like and recovered by a boiler or the like is introduced into the cooling tower 1 through an exhaust gas introduction duct 2 installed at the top of the cooling tower, and spray nozzles 6 are provided. As a result of the water spray, the exhaust gas is cooled by the latent heat of evaporation of the water droplets,
It is discharged from an exhaust gas discharge duct 3 installed at the lower part of the cooling tower. The discharged exhaust gas is introduced into a subsequent dust collector. However, the incinerator, boiler, and dust collector described here are not shown.

The temperature of the exhaust gas cooled in the cooling tower varies depending on the conditions of the dust collector at the subsequent stage and other conditions relating to the operation. For example, in the case of the cooling tower installed in a refuse incineration facility, 150 to 200 ° C. In recent years, it has been greatly desired to reduce the temperature to a temperature at which generation of dioxins is extremely small.
The temperature drop in the cooling tower, that is, the difference between the inlet temperature and the outlet temperature, depends on the size of the cooling tower and the spray performance of the spray nozzle, but is usually about 30 to 200 ° C.

FIG. 1 shows a cooling tower in which four spray nozzles 6 are provided at an elevation angle β, and four spray nozzles are provided in the circumferential direction of the tower cross section. In this case, the flow of the exhaust gas to be cooled is an upward flow. The water spray flow of the spray nozzle 6 is usually a three-dimensional cone type, but the cross section of the water spray flow is not limited to a circle but may be an ellipse as shown in FIG.

In such a case, the dispersion angle α is as shown in FIG.
As shown in (c), the dispersion angle α is different between the AA section and the BB section. In the present invention, a specific cross section having a dispersion angle of 90 degrees or less is required, and this cross section needs to be installed horizontally in the flow direction of the exhaust gas to be cooled.

The elevation angle β when installing the spray nozzle is
The angle between the tower section and the spray nozzle or the tip of the spray nozzle, that is, the angle formed by the center line of the water spray flow and the tower section, as shown in FIGS. 1, 3, and 4.

FIG. 4 shows an example in which the tip of the spray nozzle is bent so that the angle formed between the center of the water spray and the cross section is an elevation angle β. The elevation angle β is calculated from α / 2 shown in FIG.
(C) is an angle in a range up to (90−α / 2). In the embodiment shown in FIG. 1, the spray nozzle is provided so as to satisfy these conditions.

As described above, when the flow of the exhaust gas to be cooled is an upward flow, the elevation angle β (α / 2 <β <(9
0-α / 2)), it is possible to prevent the water spray flow from being excessively concentrated at the center of the cross section and to form a low-temperature region having a high water vapor density. Both effects are obtained which can prevent the flow from reaching the inner wall and forming a wetted surface.

When the elevation angle β, which is the installation angle of the spray nozzle, is set to α / 2 or less, the lower stream of the water spray stream collides head-on with the lower stream of the water spray stream of another spray nozzle, and a low-temperature region having a high water vapor density is formed. It is not preferable because it causes problems such as condensation of unevaporated water droplets in a low-temperature region, corrosion of equipment, and accumulation of wet dust.

When the elevation angle β is (90−α / 2) or more, the end stream of the water spray flow reaches the inner wall on the side where the spray nozzle is installed, and a wet surface is formed. It is not preferable because it causes problems such as corrosion of water and accumulation of wet dust.

When the exhaust gas to be cooled is a downward flow (not shown), only the elevation angle β becomes negative, and the elevation angle is set so that the relative positional relationship between the exhaust gas flow and the water spray flow becomes the same as in the upward flow. β may be in the range of -α / 2 to-(90-α / 2) degrees, and it is clear that the above-described action can be obtained in the same manner.

Next, as shown in FIG. 5, the spray nozzle 6, which is installed with an elevation angle β, should be installed at a position where two or more axes of symmetry exist along the circumferential direction of the same cross section. Good. However, in FIG. 5, the spray nozzle driving device 7 is omitted for simplicity.

For example, FIG. 5A shows two spray nozzles installed in the opposite direction, and there are two axisymmetric axes (a, b). FIG. 5 (b) shows three of them installed at equal intervals, and there are three (a, b, c) axes of line symmetry. FIG. 5 (c) shows a case in which four opposing lines are installed so that the distance between them is the same, and there are two (a, b) axis of symmetry. Fig. 5 (d) shows two cables installed at 90 degree intervals.
There is only one axis of symmetry (a). Among these, FIGS. 5A, 5B, and 5C are preferable because the symmetry of the water spray flow is obtained because there are two or more axes of line symmetry.
In (d), since there is only one axis of symmetry, the symmetry of the water spray flow cannot be obtained, which is not preferable.

As described above, when a plurality of spray nozzles 6 are arranged at positions where two or more linear symmetry axes exist in the same cross section, the symmetry of the water spray flow is obtained, and the water spray flow is opposed to the inner wall of the tower. The inner wall can be prevented from forming a wet surface due to collision with the inner wall, and the effects of the first and second inventions can be obtained more effectively.

Next, FIG. 6 shows that the spray nozzle 6 installed with an elevation angle β is
And a cooling tower according to the present invention installed on the side of the cooling tower.

The spray nozzle 6 is, as shown in FIG.
The reciprocating drive is performed toward the center of the cross section of the tower while performing water spraying by the driving device 7. As described above, water spray is performed while the spray nozzle is reciprocatingly driven toward the center of the tower cross section while having an elevation angle β, so that the spray flow of the water droplets by the spray nozzle is forcibly moved, and the temperature in the tower is low. The region can be prevented from being formed for a long time. That is, since it is possible to prevent the low-temperature region from being formed for a long time, the spray water is effectively evaporated, and problems such as corrosion of the device and accumulation of wet dust caused by condensation of moisture in the low-temperature region can be solved. Therefore, the effects of the first to third inventions can be obtained more effectively. Needless to say, as shown in FIG. 4, the tip of the spray nozzle may be bent to have an elevation angle β, and the spray nozzle may be driven to reciprocate by the driving equipment 7, and the effect is the same.

The spray nozzle 6 to be driven (driving device 7
The number of spray nozzles 6 that are not driven is not particularly limited, but it is preferable that a plurality of spray nozzles 6 be driven. If the number of driven spray nozzles is one, the symmetry in the cross section of the water spray flow is slightly impaired, which is relatively undesirable. When water spray is performed while the spray nozzle is driven with an elevation angle β, the spray nozzle 6 to be driven is preferably arranged at a position where two or more axes of linear symmetry exist as in the third invention. .

FIG. 8 shows that while having an elevation angle β,
It is an example showing the operation of the projection length l of the tip of the spray nozzle from the inner wall when the spray nozzle 6 is driven to reciprocate. If periodic reciprocating drive is achieved without being limited to FIG.
Operation such as a sine curve may be used.

At this time, the time required for the projection length l of the spray nozzle 6 driven from the inner wall of the cooling tower 1 to be driven while having the elevation angle β from the minimum to the maximum, or the half of the reciprocating driving cycle is: It is desirably 1 to 10 times the average residence time of the exhaust gas in the cooling tower 1.

By setting in this manner, the gas flow in the cooling tower can be effectively changed, and the formation time of the temporary low-temperature region can be reduced by the condensation of water or the wet dust associated therewith. Can be suppressed within a range in which the accumulation of slag does not occur.

If the residence time of the exhaust gas is within one time, the residence time in the tower is usually about 2 to 10 seconds. Therefore, the spray nozzle must be frequently driven, and mechanical energy is wastefully consumed. That is, the convection time of the exhaust gas, that is, the time from the time when the exhaust gas is introduced into the cooling tower to the time when it is discharged from the outlet, is changed even if the projection length of the spray nozzle is changed. This is not preferable because the effect of offsetting the low-temperature region due to the exchange of the high-temperature region and the high-temperature region does not particularly increase.

On the other hand, if it is 10 times or more, the operation of changing the projection length of the spray nozzle is performed at a sufficiently long time interval, so that a low-temperature region in the tower is formed for a long time, and the water content is reduced. It is not preferable because a sufficient amount of time elapses to cause a problem of condensation and the accompanying accumulation of wet dust. However, the effect is relatively small even outside this range, but it is clear that the effect of the fifth invention of driving the spray nozzle while maintaining the elevation angle β can be obtained.

The minimum projecting length, the maximum projecting length, and the driving width when driving the spray nozzle 6 are not particularly limited. However, the drive width or the maximum protrusion length is set to 0.
It is not preferred that the ratio be 5 times or more, because the operation becomes mechanically inconvenient and the function of eliminating the low temperature region in the tower does not particularly increase. According to the investigation by the present inventors, even with a short drive width of about several tens of cm (about 0.1 times the inner diameter of the tower),
It has been found that the effect of eliminating the low temperature region of the gas flow in the column was sufficiently obtained.

Next, the spray nozzle driving device 7 drives the spray nozzle 6 to reciprocate in the center of the cross section.
It is a mechanical drive device composed of members such as a motor, a gear, a bearing, a bearing, and a rotation speed control device. However, these members are not shown. In addition, a known drive device using hydraulic pressure, air pressure, or the like may be used, and a drive device capable of easily adjusting the drive width and the reciprocating drive cycle is desirable.

The spray nozzle 6 varies depending on the operating condition of the cooling tower. For example, in the case of a cooling tower for cooling at a low temperature of 200 ° C. or less, water and air from which finer spray water droplets can be obtained are used. It is preferable to use a two-fluid nozzle, but it is not particularly limited. Further, an acidic component in the exhaust gas may be removed by using an alkaline absorbing liquid such as slaked lime slurry as the spray water, and any method may be used as long as the exhaust gas can be cooled using the latent heat of water.

The spray nozzle 6 installed with an elevation angle β may be provided with a protective tube around the nozzle in order to ensure the durability of the nozzle, or a purge air may be provided between the nozzle and the protective tube. Etc. may be used. When driving the spray nozzle 6, the spray nozzle 6 may be driven together with the protective tube, or only the spray nozzle may be driven. The water spray by the spray nozzle is preferably a substantially constant amount spray, but the water spray amount may be controlled by feedback control or the like so as to reach a predetermined exhaust gas temperature, and the water spray amount is changed according to the driving of the spray nozzle. And so on.

The present invention has been described mainly on the case where the exhaust gas is introduced from the lower part of the cooling tower and discharged from the upper part in the cylindrical cooling tower. The present invention can be applied even in the case of not being a cylindrical type, and the same effect can be obtained.

Example a FIGS. 10 and 11 show the results obtained by carrying out the water spraying method of the cooling tower according to the present invention in comparison with the conventional method.

FIG. 10 is a view showing an example of test results when the water spraying method of the present invention is performed. FIG. 11 is a diagram illustrating test results in a conventional case where the present invention is not performed. Here, reference numeral 11 denotes accumulated dust.

In Example 1, using the cooling tower shown in FIG. 1, the dispersion angle α of the water spray flow of the spray nozzle was 60 °, the elevation angle β from the tower cross section was 45 °, and the projection length 1 was 40 cm. Four spray nozzles were installed at equal intervals in the circumferential direction of the same cross section. However, the spray nozzle was fixed without being driven. The comparative example is a cooling tower of the same type as that of Example 1, and four spray nozzles are installed at equal intervals in the circumferential direction of the same cross section with an elevation angle β = 0 °.

As a common test condition, a maximum water droplet diameter of about 15
A two-fluid spray nozzle of 0 μm is adopted, and the processing gas amount is 4
0000 Nm ³ / h, inlet exhaust gas temperature about 220 ° C., outlet exhaust gas temperature 150 ° C. (constant by controlling the amount of water spray), and the test period was one month.

As a result, the embodiment of the present invention is
At the end of the test after 5 months, little accumulation of dust in the tower was observed, and the dust was slightly attached to the inner wall. In the comparative example, as shown in FIG.
The accumulation of wet dust having a thickness of 10 cm or more was observed on the entire inner wall of the tower, and a part of the dust was fixed by sensible heat of the exhaust gas.

Since the accumulation of dust is generated because unevaporated water droplets adhere to the inner wall of the tower or promote the effect of agglomeration of the dust, an index for determining whether the water droplets have completely evaporated and stable operation has been performed. Become.

From the test results, it can be seen that the water spray method of the present invention achieves complete evaporation of water droplets by preventing the formation of a low-temperature region in the tower, and thus does not cause trapping due to accumulation of wet dust in the tower. It was confirmed that this was an excellent water spray method for a cooling tower.

Example b Next, in order to examine the effect of the spray nozzle reciprocating drive of the present invention, an additional test was performed under the following conditions.

The test conditions in Example 2 were the same as in Example 1 except that the outlet exhaust gas temperature was 140 ° C.
The test conditions of Example 3 were the same as those of Example 2,
The spray nozzle was driven back and forth by the driving device. The two reciprocatingly driven spray nozzles are at only two opposing positions and have a minimum protrusion length of 30 cm and a maximum protrusion length of 80 cm (drive width of 50 cm), and half the drive cycle is five times the average residence time of exhaust gas of 4 seconds. 20 seconds.

As a result, in Example 3 in which the spray nozzle was driven while maintaining the elevation angle even at a very low temperature of 140 ° C., which was severe for evaporation, no wet dust accumulation was observed. In Example 2 in which no driving was performed,
Wet dust deposition occurred partially.

From these results, it can be confirmed that, when the fifth invention for driving the spray nozzle is implemented in addition to the first invention in which the spray is performed with the elevation angle β, the cooling can be stably performed to a lower temperature. Was.

[0064]

According to the water spray method of the present invention, a predetermined elevation angle and a predetermined angle in the downstream direction of the exhaust gas flow from the cross section of the cooling tower using the spray nozzle having a dispersion angle of the water spray flow of 90 degrees or less. By performing water spraying with a protruding length, it is possible to prevent the formation of a low-temperature region having an extremely high water vapor density, so that the generation of dioxins is as low as about 150 ° C. Even so, it is possible to effectively evaporate the water droplets sprayed by the spray nozzle, thereby enabling excellent exhaust gas cooling without causing problems such as accumulation of wet dust in the tower due to incomplete evaporation.

Further, when the spray nozzle is reciprocated along the center of the cross section of the tower while maintaining a predetermined elevation angle,
Since the formation of the low-temperature region for a long time in the tower can be prevented, the above-mentioned effects can be obtained more reliably.

Further, by providing a spray nozzle having a predetermined elevation angle so as to obtain symmetry of the water spray flow, and a simple driving device for the spray nozzle,
An excellent cooling tower having the above effects can be easily obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of an embodiment of a cooling tower according to the present invention.

FIG. 2 is an explanatory diagram illustrating a dispersion angle of a water spray flow according to the present invention.

FIG. 3 is an explanatory diagram of an elevation angle and the like of a spray nozzle according to the present invention with respect to a tower cross section.

FIG. 4 is an explanatory view when the tip of a spray nozzle according to the present invention is bent.

FIG. 5 is an explanatory diagram of an installation state when a plurality of spray nozzles according to the present invention are installed.

FIG. 6 is a perspective view around a spray nozzle driving device according to the present invention.

FIG. 7 is an explanatory diagram of a spray nozzle driving state according to the present invention.

FIG. 8 is an explanatory diagram of a reciprocating driving state of the spray nozzle according to the present invention.

FIG. 9 is an explanatory view showing an example of a conventional method of installing a spray nozzle.

FIG. 10 is an explanatory diagram showing an operation result of the water spray method of the present invention.

FIG. 11 is an explanatory diagram showing an operation result of a conventional water spray method.

[Explanation of symbols]

1 ... cooling tower (body part) 2 ... exhaust gas introduction duct 3 ...
Exhaust gas exhaust duct, 4 ... Dust collecting hopper, 5 ... Dust exhaust, 6 ... Spray nozzle, 7 ... Driver, 8 ... Water spray, 9 ... Water supply pipe, 10 ... Air supply pipe, 11 ... Deposited dust .

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masato Kato 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (72) Inventor Kazutoshi 1-1-2, Marunouchi, Chiyoda-ku, Tokyo Japan Inside Kokan Co., Ltd. (72) Inventor Takehiko Inada 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Japan Kokan Co., Ltd. (56) References JP-A-61-107925 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) F28C 3/08 F23J 13/00-15/08

Claims (7)

(57) [Claims] 1. A cooling tower for cooling exhaust gas by water spraying without generating wastewater, comprising: a) using a spray nozzle in which a dispersion angle α of a water droplet spray flow by a spray nozzle is 90 ° or less in a specific cross section; ) A plurality of spray nozzles are installed along the circumferential direction of the tower section so that the spray nozzle is horizontal with the specific cross section and the flow direction of the exhaust gas to be cooled. When the elevation angle β from the tower cross section is α / 2 to (90−α / 2) degrees,
/ 2--(90-α / 2) degrees, the spray nozzle is installed with the same elevation angle β, d) the spray nozzle tip protrudes from the inner wall by a predetermined length, and e) A water spray method for a cooling tower, wherein water spray is performed by the spray nozzle. 2. The method according to claim 1, wherein the elevation angle β of the spray nozzle is obtained by bending the tip of the spray nozzle. 3. The water spraying method for a cooling tower according to claim 1, wherein the plurality of spray nozzles are arranged at positions where two or more axes of linear symmetry exist in the same cross section. 4. The water spray method for a cooling tower according to claim 1, wherein the tip of the spray nozzle projects from the inner wall by 30 cm or more. 5. The cooling tower according to claim 1, wherein at least one of the plurality of spray nozzles is sprayed while being reciprocated toward a center of the cross section of the tower. Water spray method. 6. The method according to claim 5, wherein, when the spray nozzle is driven, a time when the projection length of the spray nozzle is from a minimum to a maximum, or a half of a reciprocating drive cycle is:
A water spray method for a cooling tower, wherein the average residence time of the exhaust gas in the cooling tower is 1 to 10 times. 7. A cooling tower for cooling exhaust gas by spraying water without generating wastewater, and a spray nozzle according to claim 1 and a drive for driving the spray nozzle in the direction of the center of the cross section of the tower. A cooling tower equipped with a device.