JPH1163469A - Desuperheating tower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively evaporate the spray waterdrop by a spray nozzle so that the problem of dust accumulation in a tower, etc., does not occur, by installing an exhaust gas introduction duct which covers, in donut shape, the opening, existing in the circumferential direction of the drum of a desuperheating tower, of the exhaust gas introduction duct. SOLUTION: The exhaust gas which is discharged from an incineration facility such as a garbage incineration facility, etc., and whose heat is recovered by a boiler or the like is introduced into a desuperheating tower 1 through an exhaust gas duct 2. The exhaust gas introduced from the exhaust gas introduction duct 2 is introduced into the tower with an induction fan or the like from the openings 7 provided in a plurality in the circumferential direction of the drum, and passes the drum 1 and is discharged while being cooled by the evaporation of the spray waterdrop of a spray nozzle. Since it is introduced from a plurality of openings, the flows of exhaust gas from adjacent openings collide against each other and are mixed, and at the same time, due to the plural openings, the exhaust gas introduction velocity becomes low flow velocity, and the flows turn into an upward flow equal in cross section of the drum. Since the gas current is equal, the spray waterdrop can be evaporated effectively when having sprayed water by the spray nozzle.

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 cooling tower for cooling exhaust gas discharged from an incinerator or the like of a combustible waste treatment facility 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 bag 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, as shown in FIG. 9 or FIG. 10, a cooling tower is provided with an exhaust gas introduction duct at a lower portion of a cylindrical body and an exhaust gas discharge duct at an upper portion thereof. The nozzle was installed above the exhaust gas introduction duct.

[0005]

However, in the cooling tower of the conventional shape, the flow of the exhaust gas to be introduced is uniformly distributed in the body of the body, which is a cooling zone for cooling the exhaust gas by the latent heat of evaporation of the spray water. Because it does not spread over the entire section, active and efficient evaporation of the sprayed water droplets is not performed, the wetted surface of the tower inner wall is formed by the non-evaporated water droplets, the non-evaporated water droplets flow out to the subsequent pug filter, wet dust The formation of dust causes problems such as sticking of dust and difficulty in discharging dust.

[0007] Explaining with reference to FIGS. 7 and 8, the exhaust gas introduced from the exhaust gas introduction duct 12 cannot be sufficiently diffused in the process of reaching the cooling tower body 11, and the exhaust gas discharge duct 1
Short circuit 9 is reached. That is, since the predetermined exhaust gas residence time cannot be obtained, sufficient evaporation time of the spray water droplets cannot be obtained, and since the exhaust gas flow is not uniform in the body section, the evaporation of the spray water droplets is uniformly and effectively performed. However, since the temperature distribution is biased, it is impossible to completely evaporate the spray water droplets, thereby causing the above problem.

[0007] As described above, these problems have become more prominent as the dust collection temperature has recently become lower. An object of the present invention is to provide a high-performance cooling tower which can cope with a low dust collection temperature and does not cause the above problems.

[0008]

Means for Solving the Problems In order to achieve effective complete evaporation of spray water droplets and to solve the above problems, aiming at rectification and uniformization of gas flow in the body of the cooling tower, We devised the means. First, a cooling tower that cools exhaust gas by water spray without generating wastewater. Regarding the shape of the exhaust gas introduction part, a) Along the circumference of the cooling tower body at the position where the exhaust gas introduction duct is installed A plurality of openings, and b) an exhaust gas introduction duct is provided so as to cover the openings in a donut shape.

By configuring the exhaust gas introduction section of the cooling tower as described above, the exhaust gas is relatively introduced into the tower from a plurality of openings provided in the circumferential direction of the cooling tower body by a gas suction action of an attraction fan or the like. It is introduced at a low flow rate and is discharged from the exhaust gas discharge section through the body while being cooled by the evaporation of the water droplets sprayed from the spray nozzle. Since the exhaust gas is guided from a plurality of openings into the tower, the exhaust gas flows from adjacent openings collide with each other and are mixed.At the same time, since the plurality of openings are used, the exhaust gas introduction speed is low and the body cross section is uniform. It becomes upward flow.

That is, since the flow of exhaust gas is uniform in the body of the cooling tower relating to the evaporation of the water droplets, the effect of effectively evaporating the water droplets when water spraying is performed by the spray nozzle is obtained. .

Second, a cooling tower for cooling the exhaust gas by water spray without generating wastewater. Regarding the shape of the exhaust gas introducing section, c) the circumferential direction of the temperature reducing tower body at the position where the exhaust gas introducing duct is installed. , A plurality of openings are installed along the line, and d) a plurality of branched exhaust gas introduction ducts are connected to the openings.

Also in this case, since the exhaust gas is introduced from the plurality of openings, the same operation as the first invention can be obtained. . Thirdly, in the cooling tower according to claim 1 or 2, the plurality of openings are installed such that the opening ratio is smaller on the side near the exhaust gas introduction duct.

When the opening ratio is set in this manner, the amount of exhaust gas discharged from the opening closer to the exhaust gas introduction portion is relatively reduced, and at the same time, the amount of exhaust gas discharged from the opening far from the exhaust gas introduction portion is relatively reduced. Increase. This is because the opening closer to the exhaust gas introduction duct has a smaller pressure loss, so that a more uniform amount of exhaust gas is introduced in consideration of the fact that more exhaust gas is likely to flow out. Therefore, the operation of the first or second invention can be more effectively obtained in the exhaust gas introduction section.

Fourthly, a cooling tower according to any one of claims 1 to 3, wherein the entire area of the opening is set so that the average gas flow velocity in the opening is 5 m / s or less. It is.

When the entire area of the opening is set as described above and the average gas flow velocity in the opening is reduced, the introduced exhaust gas is more uniformly distributed in the cross section of the body without the flow velocity in the central portion becoming extremely high. An upward exhaust gas flow at the body is obtained. When the speed is 5 m / s or more, the exhaust gas introduced into the body from the opening concentrates at the center of the tower section, and the upward flow of the exhaust gas is biased near the axial center, making it difficult to achieve a uniform exhaust gas flow. It is not preferable.

Fifthly, with regard to the shape of the exhaust gas discharge portion, the exhaust gas introduction duct according to any one of claims 1 to 4 is an exhaust gas discharge duct. Even if the shape of the exhaust gas introduction section described in the first to fourth inventions is used as it is as the shape of the exhaust gas discharge section, an effect of making the exhaust gas uniform can be obtained.

The uniformity of the gas in the cooling tower body is greatly affected by the shape of the exhaust gas introduction section. However, if the shape of the exhaust gas discharging section greatly deviates the gas flow, the uniformity of the gas in the cooling tower body is reduced. Also, the uniformity of the gas flow may be impaired. Therefore, by setting the shape of the exhaust gas discharge section in this way, the exhaust gas is exhausted through a plurality of outlets instead of the uneven exhaust gas discharge by the conventional two ducts installed on the side, so that the exhaust gas is uniformly distributed. Can be discharged.

Further, since the exhaust gas discharge duct is provided on the side of the exhaust gas discharge section, when installing the cooling tower, the length of the conventional exhaust gas discharge duct is unnecessarily lengthened in the vertical direction such that it is installed at the top of the tower. Thus, a compact vertical length cooling tower can be obtained without having to increase the size of the cooling tower.

Sixth, a cooling tower for cooling the exhaust gas by water spray without generating wastewater, wherein the exhaust gas introduction section has the shape of the exhaust gas introduction section according to claims 1 to 4, and the exhaust gas discharge section has a fifth aspect. The cooling tower is characterized by having a shape according to.

By having the shapes of the exhaust gas introduction portion shown in the first to fourth and the shape of the exhaust gas discharge portion shown in the sixth at the same time, the first to sixth effects are synergistically obtained. Can be

Seventh, the installation position of the spray nozzle for cooling the exhaust gas by water spray is installed on the downstream side of the gas flow in the tower with respect to the opening in claim 1, and the symmetry of the water spray flow in the cross section of the tower The temperature reduction tower according to any one of claims 1 to 6, wherein a plurality of spray nozzles are provided in a circumferential direction of the tower body so as to obtain the following.

By installing the spray nozzle for water spray in this way, the water spray of the spray nozzle does not collide with the facing inner wall, that is, the inner wall does not form a wet surface due to the water spray. A symmetrical water spray flow is obtained in the body section, and the uniformity of the water spray flow and
Complete evaporation in the column is effectively obtained.

[0023]

1 to 6 show one embodiment of a cooling tower according to the present invention. 7 and 8 are views showing a conventional cooling tower for comparison with the present invention. here,
1 is a cooling tower outer tower or main body, 2 is an exhaust gas introduction duct, 5 is a dust collection hopper, 6 is a dust discharge section, 7 is an opening in the exhaust gas introduction section, 8 is an opening in the exhaust gas discharge section, 9 is an exhaust gas discharge duct, 10 is a spray nozzle, 11 is a body of a cooling tower body, 12 is an exhaust gas introduction duct,
15 is a dust collecting hopper section, 16 is a dust discharging section, 19
Is an exhaust gas discharge duct.

An embodiment of the present invention will be described below with reference to FIGS. Exhaust gas 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 introducing duct 2 installed at a lower part of the cooling tower, and spray nozzles 10 ( However, for the sake of simplicity, the spray nozzle is not shown in FIGS. 1 to 4. As shown in FIG. 5, the exhaust gas is cooled by the latent heat of vaporization of the water droplet and installed at the upper part of the cooling tower. From the exhaust gas discharge duct 9. The discharged exhaust gas is introduced into a dust collector installed at a later stage. However, the incinerator, boiler, and dust collector described here are not shown.

The temperature of the exhaust gas whose temperature has been reduced by the cooling tower varies depending on the conditions of the subsequent dust collector and other conditions relating to the operation. For example, in the case of a cooling tower installed in a refuse incineration facility, the temperature is 150 to 200. In recent years, there has been a great demand for cooling to a low temperature at which the generation of dioxins at a temperature of ° C. is very 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 that a plurality of openings 7 are provided along the circumferential direction of the temperature-reducing tower body 1 at the position where the exhaust gas introduction duct 2 is installed, and the openings are covered in a donut shape. This is the shape of the exhaust gas introduction section when the exhaust gas introduction duct 2 is installed.

Exhaust gas introduced from the exhaust gas introduction duct 2 is introduced into the tower at a relatively low flow rate through a plurality of openings 7 provided in the circumferential direction of the body 1 by a gas suction action such as an induced fan. The water passes through the body 1 while being cooled by the evaporation of the water droplets sprayed from the nozzle, and is discharged from an exhaust gas discharge unit (not shown).

Since the exhaust gas flows from adjacent openings collide with each other and are mixed because they are guided into the tower from the plurality of openings, the exhaust gas introduction speed becomes low at the same time due to the plurality of openings, and the body section And a uniform upward flow. That is, since the flow of exhaust gas is uniform in the body of the cooling tower related to the evaporation of the spray water droplets, the spray water droplets are effectively evaporated when water spray is performed by the spray nozzle.

FIG. 2 shows that a plurality of openings 7 are provided along the circumferential direction of the temperature-reducing tower body 1 at the position where the exhaust gas introduction duct 2 is installed, and the exhaust gas introduction duct 2 branched into a plurality of sections is provided. This is the shape of the exhaust gas introduction section connected to the opening 7.

Also in this case, the exhaust gas is introduced from a plurality of openings as in FIG. 1, so that the same effect as in the first invention can be obtained. It is desirable to set the entire area of the opening so that the average gas flow velocity in the opening 7 is 5 m / s or less. When the average gas flow velocity in the opening is reduced in this way, the exhaust gas introduced can have a more uniform upward flow of exhaust gas in the body without the flow velocity in the center part being extremely increased in the body section. When the speed is 5 m / s or more, the exhaust gas introduced into the body from the opening concentrates at the center of the tower section, and the upward flow of the exhaust gas is biased near the axial center, making it difficult to achieve a uniform exhaust gas flow. It is not preferable.

Further, as shown in FIG. 3, the opening 7 of the exhaust gas introduction section may be installed such that the opening ratio on the side close to the exhaust gas introduction port becomes small. With this arrangement, the amount of exhaust gas introduced from the opening closer to the exhaust gas introduction portion relatively decreases, and the amount of exhaust gas introduced from the opening farther from the exhaust gas introduction portion relatively increases.

The reason for this is that a more uniform amount of exhaust gas is discharged in consideration of the fact that the opening near the exhaust gas introduction duct has a smaller pressure loss, so that more exhaust gas is likely to flow out. Therefore, in the exhaust gas introduction section,
The effect shown in FIG. 1 or FIG. 2 can be obtained more reliably.

FIG. 4 is a diagram showing a case where the shape of the exhaust gas introduction section of the present invention is used for an exhaust gas discharge section. Even when the shape of the exhaust gas introduction section is used for the exhaust gas discharge section, the effect of uniformly equalizing the gas flow can be obtained. Further, the opening ratio may be reduced on the side close to the exhaust gas discharge port.

Further, as shown in FIG. 5, the shape of the exhaust gas introduction portion and the shape of the exhaust gas discharge portion may be used in combination at the same time, and it goes without saying that the above-mentioned effects are more remarkably obtained.

Next, a spray nozzle 10 for spraying water is used.
It is desirable to install a plurality of gas turbines above the double tower portion of the exhaust gas introduction part, and to install a plurality of them in the circumferential direction of the tower body so as to obtain symmetry of the water spray flow in the tower cross section.

FIG. 6 is a sectional view of FIG. 5B.
This is an embodiment in which the spray nozzles are arranged so as to obtain the symmetry of the water spray flow. FIG. 6A shows a case where four nozzles are installed at the same interval in the same cross section, FIG. 6B shows a case where three nozzles are installed at the same interval, and FIG. It is a figure each showing the case where two sets and a total of four are installed. It is clear that in each case the symmetry of the water spray flow is obtained.

By installing the spray nozzle for water spray in this way, the water spray of the spray nozzle does not collide with the facing inner wall, that is, the inner wall does not form a wet surface due to the water spray. A symmetrical water spray flow is obtained in one body section, and uniformity of the water spray flow and complete evaporation in the tower are effectively obtained.

In FIG. 6, a plurality of spray nozzles are installed on the same cross section, but it is needless to say that the installation cross section may be two or more. The spray nozzle 10 varies depending on the operating conditions. For example, in the case of a low-temperature cooling tower that cools to 200 ° C. or lower, a two-fluid nozzle using water and air that can obtain finer spray droplets is used. However, there is no particular limitation. 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.

When the spray nozzle 10 is installed in the cooling tower, for example, several 10 cm from the inner wall is used.
It may or may not protrude. In order to ensure the durability of the nozzle, a protection tube may be attached to the outer periphery of the nozzle, or purge air or the like may be used between the nozzle and the protection tube. Further, the nozzle may be installed with an elevation angle with respect to the cross section, or the nozzle tip may be bent in the gas flow direction. It is clear that the effects of the present invention can be similarly obtained in any case.

In the present invention, for convenience of explanation, the case where the exhaust gas is introduced from the lower part of the cooling tower and discharged from the upper part has been described. Of course, the exhaust gas is introduced from the upper part of the cooling tower and discharged from the lower part ( Obviously, the same effect can be obtained by applying the present invention to the black thick arrow in FIG. 5).

"Example" FIGS. 9 and 10 show test results obtained by implementing the present invention in a cooling tower attached to a refuse incineration plant, together with a conventional comparative example.

FIG. 9 is a diagram showing test results when the present invention is implemented. FIG. 10 is a diagram illustrating a conventional comparative example of test results when the present invention is not performed. Here, reference numeral 20 denotes accumulated dust.

The embodiment is a cooling tower shown in FIG. 5 in which the shape of the exhaust gas introduction section shown in FIG. 1 is adopted also for the exhaust gas discharge section.
The total area of the opening was set such that the average exhaust gas flow rate at the opening was 4 m / s.

In the comparative example, a cooling tower having the shape shown in FIG. 7 was used. As a common condition, the external shape of the cooling tower is the same size,
Exhaust gas throughput 40000 Nm ³ / h, degassing tower exhaust gas residence time 4 seconds (calculated by volume and exhaust gas amount), degassing tower inlet exhaust gas temperature about 200 ° C, outlet exhaust gas temperature (constant by adjusting water spray amount To 150 ° C. Four spray nozzles were installed at equal intervals on the same section, and a two-fluid nozzle was used.

The test was performed by first measuring the gas flow velocity distribution in the cross section of the tower before spraying water, then performing water mist operation for one month continuously, and checking the dust accumulation state in the tower one month later. confirmed.

As a result, in the gas velocity distribution before water spraying, in the conventional comparative example, the gas flow was short-circuited from the exhaust gas introduction duct to the exhaust duct and did not disperse, so that the result that the flow velocity distribution was extremely biased was obtained. However, in the example of the present invention, a substantially uniform flow velocity distribution was obtained.

Next, when the dust accumulation in the tower after one month is observed, in the comparative example, wet dust due to incomplete evaporation of the sprayed water droplets is deposited to a thickness of 10 cm or more over a wide range of the inner wall of the tower, and a part of the dust is deposited. While it was fixed by exhaust gas detection,
In the example of the present invention, no accumulation of dust in the tower was observed, and the dust was slightly attached to the inner wall.

Since the accumulation of dust occurs because unevaporated water droplets adhere to the tower wall and promotes the dust coagulation effect, an indicator for determining whether the water droplets have completely evaporated and stable operation has been performed. Becomes

That is, in the cooling tower of the present invention, a uniform exhaust gas flow can be obtained in the tower, and even at a low temperature of 150 ° C., the sprayed water droplets can be effectively evaporated, thereby preventing dust accumulation due to incomplete evaporation. It was confirmed that it was an excellent cooling tower without any problem.

[0050]

According to the temperature reducing tower of the present invention, the exhaust gas is effectively rectified in the exhaust gas introduction part, and a uniform gas flow is obtained in the body part, so that the generation of dioxins is very small at about 150 ° C. Even at a low temperature, the spray water droplets from the spray nozzle are effectively evaporated, thereby enabling excellent exhaust gas cooling without causing problems such as dust accumulation in the tower due to incomplete evaporation.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of a shape of an exhaust gas introduction portion of a cooling tower according to the present invention.

FIG. 2 is a view showing another example of the embodiment of the shape of the exhaust gas introduction portion of the cooling tower according to the present invention.

FIG. 3 is a diagram showing another example of the embodiment of the shape of the exhaust gas introduction portion of the cooling tower according to the present invention.

FIG. 4 is a view showing an example of an embodiment of an exhaust gas discharge part shape of a cooling tower according to the present invention.

FIG. 5 is a diagram showing an example of an embodiment of a cooling tower according to the present invention.

FIG. 6 is a diagram showing an example of an embodiment of installation of a spray nozzle of a cooling tower according to the present invention.

FIG. 7 is a diagram showing an example of a conventional cooling tower.

FIG. 8 is a diagram showing another example of a conventional cooling tower.

FIG. 9 is a view showing an operation result of the cooling tower according to the present invention.

FIG. 10 is a view showing an operation result of a conventional cooling tower.

[Explanation of symbols]

1 ... cooling tower outer tower or main body, 2 ... exhaust gas introduction duct, 5 ... dust collection hopper section, 6 ... dust discharge section, 7 ...
Opening in the exhaust gas introduction section, 8 ... Opening in the exhaust gas discharge section, 9 ... Doughnut type exhaust gas discharge duct, 10 ...
Spray nozzle, 11: body of cooling tower body, 12: exhaust gas introduction duct, 15: dust collecting hopper, 16: dust discharge part, 19: exhaust gas discharge duct, 20: accumulated dust.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takehiko Inada, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Katsuki Sonoda 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan (72) Inventor Shuichi Hirata 1-1-2 Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Inventor Masato Kato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Inside the corporation

Claims (7)

[Claims] 1. A cooling tower for cooling exhaust gas by spraying water without generating wastewater, wherein the shape of the exhaust gas introduction section is as follows: a) Along the circumference of the cooling tower body at a position where an exhaust gas introduction duct is installed. B) a plurality of openings, and b) an exhaust gas introduction duct installed so as to cover the openings in a donut shape. 2. A cooling tower for cooling exhaust gas by spraying water without generating wastewater, wherein the shape of the exhaust gas introduction portion is c) along the circumferential direction of the temperature reduction tower body at the position where the exhaust gas introduction duct is installed. And a plurality of openings, and d) connecting a plurality of branched exhaust gas introduction ducts to the openings. 3. The cooling tower according to claim 1, wherein the plurality of openings are installed such that a portion near the exhaust gas introduction duct has a small opening ratio. 4. The method according to claim 1, wherein
A cooling tower, wherein the entire area of the opening is set such that the average gas flow velocity in the opening is 5 m / s or less. 5. The exhaust gas discharge section according to claim 1, wherein:
A cooling tower according to any one of (1) to (4), wherein the exhaust gas introduction duct is an exhaust gas discharge duct. 6. A cooling tower for cooling exhaust gas by spraying water without generating wastewater, wherein the exhaust gas introduction section is provided.
6. A cooling tower according to any one of claims 1 to 4, wherein the exhaust gas introduction part has a shape according to claim 4, and the exhaust gas discharge part has a shape according to claim 5. 7. The installation position of the spray nozzle for cooling the exhaust gas by water spray is installed on the downstream side of the gas flow in the tower with respect to the opening in claim 1, so that the symmetry of the water spray flow can be obtained in the cross section of the tower. A plurality of spray nozzles are installed in the circumferential direction of the tower body so as to be able to be used.
The cooling tower according to any one of the above.