JP4037202B2 - Gas processing tower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas processing tower such as a gas cooling tower for cooling a combustion exhaust gas generated by incineration of waste in a waste incineration facility, for example.
[0002]
[Prior art]
Recently, in such a waste incineration facility, exhaust gas treatment is performed after the combustion exhaust gas is rapidly cooled by a gas cooling tower due to a dioxin problem. That is, combustion exhaust gas generated by incineration of waste in an incinerator or the like of an incineration facility is first recovered by a waste heat boiler or the like, and then supplied to the gas cooling tower and sprayed with cooling water. It is cooled to below about 0 ° C., and after that, dust is removed by a bag filter and exhausted. Therefore, the dust before the dust removal remains in the combustion exhaust gas supplied to the gas cooling tower. In particular, when waste is incinerated until the incineration ash is melted, chlorine contained in the waste reacts with metals to produce low-boiling chlorides that are contained in large amounts in the exhaust gas. However, the presence of sulfur compounds in addition to such low boiling point chlorides may reduce the melting point of these substances. The combustion exhaust gas may be supplied to the gas cooling tower while containing the droplets of these low-boiling substances melted by the exhaust gas.
[0003]
[Problems to be solved by the invention]
Thus, when combustion exhaust gas containing dust and low-boiling-point droplets is supplied to the gas cooling tower, they adhere to the inner wall surface of the main body of the gas cooling tower and cause corrosion. There is a risk that the stable operation of the waste incineration facility may be hindered by increasing the pressure loss or causing a trouble in the discharge device that discharges the dust collected in the gas cooling tower. However, it is inevitable that such dust and low-boiling substance droplets are mixed in the combustion exhaust gas. Therefore, in order to prevent the above-mentioned problems from occurring, these dust and droplets are not attached to the inner wall of the gas cooling tower. It is necessary to suppress adhesion to the surface as much as possible. Such a problem is common to gas processing towers that perform various types of processing of gas mixed with dust, droplets, and the like other than the gas cooling tower of the waste incineration facility.
[0004]
Here, as one method for preventing dust and the like from adhering to the inner wall surface of the gas cooling tower, for example, when spraying the cooling water onto combustion exhaust gas, the cooling water sprayed using a two-fluid nozzle or the like is used. There is a method to prevent dry dust from adhering to the inner wall surface of the wet gas cooling tower by making the water droplets as small as possible and evaporating all the cooling water in the combustion exhaust gas so as not to wet the inner wall surface. This is not effective when the dust itself is sticky or when the low-boiling substance droplets adhere directly to the inner wall of the gas cooling tower. Particularly in this type of gas cooling tower, a swirling flow of combustion exhaust gas is formed by, for example, supplying combustion exhaust gas into the gas cooling tower in the tangential direction, and water droplets of cooling water are formed by the diffusion action of this swirling flow. Although it is attempted to improve the cooling effect by diffusing finely and over a wide range, in such a case, if the swirling speed of the swirling flow of the combustion exhaust gas is too fast, droplets of dust and low-boiling substances are caused by centrifugal force. Is strongly struck against the inner wall surface of the gas cooling tower, so that even if the inner wall surface is not wetted in this way, adhesion of droplets or sticky dust is inevitable.
[0005]
On the other hand, as another method for preventing dust or the like from adhering to the inner wall surface of the gas cooling tower as described above, a rectification mechanism or a guide vane is provided at the supply port of the combustion exhaust gas to the gas cooling tower. There is a method of making the flow of combustion exhaust gas to be a laminar flow with as little vortex as possible. For example, in Japanese Patent No. 3176864, a swirling flow of combustion exhaust gas is formed in the gas cooling tower as described above. Is proposed to form a swirling flow of combustion exhaust gas at a predetermined gas velocity and swirl speed by providing a swirl vane at the supply port of the combustion exhaust gas to the tower body. However, in such a method, by controlling the gas speed of the combustion exhaust gas and the swirling speed of the swirling flow in the tower body, dust and low-boiling substance droplets are strongly struck and adhered to the inner wall surface of the tower body. This can be prevented, but especially if the flue gas contains a lot of dust or low-boiling substance droplets, these are now rectifying mechanisms, guide vanes, swirl vanes, etc. There is a risk that it will adhere to the surface and hinder its stable operation. For this reason, in such a case, a straight pipe portion is ensured long in the gas supply duct for supplying the combustion exhaust gas to the gas cooling tower in front of the rectifying mechanism, the guide vane, and the swirl vane, and flows into the rectifying mechanism and the like. Adhesion must be prevented by rectifying the flow of the combustion exhaust gas, resulting in an increase in the installation area of the waste incineration equipment due to the extension of the duct length, and the construction cost of the duct and the mounting structure for the duct It will increase and the economy will be damaged.
[0006]
The present invention has been made under such a background, and particularly in the case where a swirling flow of the gas supplied into the tower body is formed in this way, the above-described rectifying mechanism, guide vanes, swirling vanes and the like are required. A gas that can be prevented from adhering to the inner wall of the tower body even if the gas contains dust or droplets by controlling so that the speed of the swirling flow does not become too high. The object is to provide a treatment tower.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve such an object, the present invention provides a duct extending in a tangential direction of a circle centering on the central axis of the tower main body at the connecting portion of the cylindrical tower main body. A gas supply duct having a center line is connected, and in the cross section along the duct center line of the connecting portion, the duct center line is decentered without intersecting the center axis, and the gas supply duct is connected to the duct. The center line is opened from the side decentered with respect to the center axis to the opposite side beyond a virtual straight line parallel to the duct center line and intersecting the center line. Therefore, in the gas processing tower having such a configuration, the gas supplied from the gas supply duct into the tower body is supplied from a portion eccentric from the central axis on the outer peripheral side in the tower body in the cross section. Although the gas forms a swirling flow around the center axis, the gas supplied from the inner peripheral side (center axis side) is supplied straight into the tower body along the virtual straight line, and the swirling flow is supplied. As a result, the strength and speed of the swirling flow are controlled and controlled, so that even if dust or droplets are contained in this gas, they are pressed against the inner wall of the tower body. Can be prevented.
[0008]
Here, the amount of eccentricity of the duct center line from the center axis in the cross section is in the range of 0.05 × D to 0.25 × D with respect to the inner diameter D of the connecting portion of the tower body. If the amount of eccentricity is larger than this and the duct center line is separated from the center axis of the tower body, the inner peripheral side of the gas supply duct in the transverse section crosses the imaginary straight line as described above. On the other hand, there is a possibility that the connection cannot be made so as to open to the opposite side. On the other hand, if the eccentric amount is smaller than this range and the duct center line is too close to the central axis, There is a possibility that the component that flows in becomes too large to form a necessary swirling flow. Further, the tower main body is formed in a multistage cylindrical shape in which the inner diameter D of the connecting portion is smaller than the inner diameter E of the other portion, and the inner diameter of the swirling flow formed in the tower main body at the connecting portion is increased. The gas may be efficiently processed by being guided to the other part having a large E. In such a case, the ratio E / D of the inner diameter E to the inner diameter D is 2 to 2.5. Desirably, the ratio E / D is too small. If the ratio E / D is too small, it becomes impossible to form a sufficiently strong swirling flow at the connection portion, or gas treatment at other portions may be insufficient. If the ratio E / D, on the contrary, is too large, the swirling diameter of the swirling flow cannot be sufficiently expanded, and there is a risk that a flow swirling in the vertical direction may occur.
[0009]
On the other hand, the gas treatment tower of the present invention can be applied to various gas treatment towers that dislike adhesion of dust and the like to the inner wall surface of the tower body. As in the case of a gas cooling tower for combustion exhaust gas from an incinerator, it may be applied to one provided with cooling means for cooling the gas supplied from the gas supply duct by spraying cooling water on the tower body. It is effective. Similarly, in the present invention, the gas supplied from the gas supply duct is a gas having a dust concentration of 5 g / m ³ N or more, such as combustion exhaust gas from the incinerator. In some cases, it is more effective when the gas contains a low-boiling substance having a melting point of 300 ° C. to 650 ° C.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a case where the present invention is applied to a gas cooling tower that cools a combustion exhaust gas G discharged from an incinerator of a waste incineration facility as described above after recovering waste heat with a waste heat boiler or the like. 1 illustrates one embodiment. In the present embodiment, the tower main body 1 is directed from the upper part toward the lower part in order, as shown in FIG. 1, and the connecting part 2 having a cylindrical shape with an inner diameter D with the upper end closed, and the lower end of the connecting part 2 going downward. Accordingly, a frustoconical shoulder portion 3 whose inner diameter gradually increases, and a cylindrical body portion 4 having a long length with an inner diameter E larger than the inner diameter D of the connecting portion 2 extending from the lower end of the shoulder portion 3; The bottom 5 having an inverted truncated cone shape whose inner diameter gradually decreases from the lower end of the body 4 toward the lower side is closed, and the center line of the cylinder or the truncated cone is defined as the central axis O of the tower body 1. The exhaust gas G discharged from the waste heat boiler or the like is supplied into the tower main body 1 from the gas supply duct 6 connected to the connecting portion 2. Is done.
[0011]
Here, the gas supply duct 6 is formed in a cylindrical shape in the present embodiment, and the center line of the cylinder, that is, the duct center line C is a plane perpendicular to the central axis O in the connecting portion 2 of the tower body 1. As shown in FIG. 2 in a cross-section along the plane P, and decentered from the central axis O to the outer peripheral side (upper side in FIG. 2) so as to be located on P. Therefore, the duct center line C extends in the tangential direction of the circle Q centering on the center axis O in the transverse section. Further, in the present embodiment, the portion 6A on the side (upper side in FIG. 2) where the duct center line C is eccentric from the center axis O on the inner peripheral surface of the gas supply duct 6 is smoothly formed on the inner wall surface of the connecting portion 2. That is, in the cross section, the portion 6A draws a tangent line of a circle formed by the inner wall surface of the connecting portion 2 as shown in FIG. Therefore, when the eccentric amount (radius of the circle Q) of the duct center line C of the gas supply duct 6 thus decentered from the center axis O of the tower body 1 from the center axis O in the cross section is R, this gas. The inner diameter of the supply duct 6 is given by (0.5 × D−R) × 2 = D−2 × R.
[0012]
On the other hand, on the inner peripheral surface of the gas supply duct 6, the side opposite to the side where the duct center line C opposite to the portion 6A is eccentric with respect to the center axis O (the lower side in FIG. 2). 6B is connected to the opposite side of the connecting portion 6 across the virtual straight line L passing through the central axis O of the tower body 1 in parallel with the duct center line C from the eccentric side in the cross section. The gas supply duct 6 is opened on the inner wall surface of the connection portion 2 so as to spread to the side opposite to the side where the duct center line C is eccentric. The over amount S from the imaginary straight line L in the cross section of the portion 6B opposite to the eccentric side of the inner peripheral surface of the gas supply duct 6 is the gas supply duct in the present embodiment as described above. 6 is D-2 × R, and the distance from the imaginary straight line L to the eccentric portion 6A is 0.5 × D. Therefore, the difference is given by 0.5 × D-2 × R.
[0013]
The gas processing tower of the present embodiment is a gas cooling tower that cools the combustion exhaust gas G as described above, and the tower body 1 cools the gas (combustion exhaust gas G) supplied from the gas supply duct 6. Cooling means 7 is provided. In the present embodiment, the cooling means 7 is a spray nozzle 8 for cooling water W provided obliquely downward in the tower body 1 of the shoulder portion 3, and the cooling water W supplied to the spray nozzle 8 is the same. Sprayed into the tower body 1 by the compressed air F supplied to the spray nozzle 8 and evaporated by the high-temperature combustion exhaust gas G, instead, the combustion exhaust gas G is taken away from the combustion exhaust gas G to cool the combustion exhaust gas G. ing. Further, a gas exhaust pipe 9 is inserted obliquely downward into the tower body 1 below the body portion 4 of the tower body 1, and the combustion exhaust gas G supplied to the gas cooling tower and subjected to a cooling process is inserted. Is discharged from the gas discharge pipe 9. Furthermore, a dust scraping device 10 that can rotate around the central axis O is provided at the closed lower end of the bottom 5 in the tower body 1, and a dust discharge port is provided on the outer periphery of the lower end of the bottom 5. 11 is provided. Dust that has settled in the tower body 1 or dust that has adhered to the inner wall surface of the tower body 1 and separated and dropped is collected on the bottom 5 and scraped by the dust scraping device 10 to remove the dust. It is discharged from the outlet 11.
[0014]
Thus, in the gas processing tower (gas cooling tower) configured as described above, the combustion exhaust gas G supplied from the gas supply duct 6 to the connecting portion 2 in the tower body 1 is the center of the gas supply duct 6. The component flowing from the axis O through the eccentric portion 6A side forms a swirling flow around the central axis O along the concave cylindrical surface formed by the inner wall surface of the connecting portion 2 as indicated by reference numeral A in FIG. The swirl flow is guided from the shoulder 3 to the body 4 and the swirl force increases the swirl diameter as shown in FIG. 1. In the body 4, the spray nozzle 8 of the cooling means 7. Is cooled as described above by the cooling water W sprayed from the gas and discharged from the gas discharge pipe 9.
[0015]
However, the component passing through the portion 6B on the opposite side to the eccentric portion 6A in the connecting portion 2 is a straight tower so as to follow the virtual straight line L parallel to the duct center line C as indicated by reference numeral B in FIG. It will flow into the main body 1 and act to block the swirling flow due to the component A, thereby controlling the strength and speed of the swirling flow without using a rectifying mechanism, guide vanes, swirling vanes, etc. It becomes possible to do. For this reason, according to the gas processing tower having the above-described configuration, even if the combustion exhaust gas G contains dust or low boiling point liquid droplets resulting from incineration of waste, the combustion exhaust gas G is cooled. It can be prevented from being strongly pressed and attached to the inner wall surface of the body 4 of the tower body 1, and adhesion of such dust and low-boiling substance droplets may cause corrosion or increase in pressure loss, or the dust scraping. It is possible to reliably prevent a situation that hinders the operation of the discharge device such as the device 10.
[0016]
In particular, the gas processing tower of the present embodiment is a gas cooling tower that cools the combustion exhaust gas G with the cooling water W sprayed from the spray nozzle 8 of the cooling means 7 as described above. If the flow is too strong, water droplets of the sprayed cooling water W are blown off on the inner wall surface of the body portion 4 to wet the inner wall surface and adhere to the dust even if the dust in the combustion exhaust gas G is not sticky. However, in the gas processing tower (gas cooling tower) of the present embodiment, the strength and speed of the swirling flow itself can be controlled, and water droplets of the cooling water W are repelled on the inner wall surface of the trunk portion 4. This is effective because it can also be prevented from being blown, and it is possible to prevent the dust from adhering to the inner wall surface by being wetted by the cooling water W. Moreover, the combustion exhaust gas G generated in the incinerator of the waste incineration facility has a large content of dust due to the waste, and may contain droplets of low boiling point substances as described above. Since there is a particular concern about adhesion to the inner wall surface of the tower main body 1, it is more effective to use the gas processing tower having the above-described configuration for such gas processing.
[0017]
However, even when the gas containing dust is treated by the gas treatment tower as described above, if the concentration of dust contained in the gas is too low, corrosion of the tower body 1 due to adhesion of dust and increase in pressure loss are caused. In addition, there is little risk of the failure of the dust discharge device. On the other hand, if the strength of the swirl flow is suppressed as described above, the dispersion effect of the cooling water W is also suppressed and the cooling efficiency may be lowered. Therefore, the gas processing tower having the above configuration is more effective when the gas supplied from the gas supply duct 6 is a gas having a dust concentration of 5 g / m ³ N or more contained in the gas. It is. Note that if the dust concentration is too high, no matter how the swirl flow is controlled by the above configuration, adhesion to the inner wall surface of the tower body 1 is inevitable, so the dust is removed to about 20 g / m ³ N or less before treatment. It is desirable to start processing after that. Further, a low-boiling substance in a gas is also easily melted into droplets when the melting point of the substance is 300 ° C. to 650 ° C., particularly when the gas to be treated is a high-temperature combustion exhaust gas G. Therefore, the gas processing tower having the above-described configuration is more effective when used for gas processing when such a low-boiling substance having a melting point is contained in the gas.
[0018]
The optimum values of the strength and speed of the swirling flow controlled in this way are the supply amount and dust concentration of the combustion exhaust gas G supplied to the tower body 1, or the properties of dust and the amount of droplets of the low-boiling substances. The speed (rotational speed) of the swirling flow is preferably within the range of 1 rad / s to 20 rad / s. If the speed is faster than this, dust may adhere to the inner wall surface by centrifugal force. On the other hand, if it is slower than this, the diameter of the swirling flow in the body part 4 is not sufficiently expanded, and a flow that swirls in the up and down direction is generated in the body part 4 and sprayed water droplets of the cooling water W are sprayed. There is a risk of winding and wetting the inner wall surface to cause dust adhesion. Therefore, in the waste incineration facility in which the gas treatment tower of the present embodiment is used as a cooling tower, the supply amount of the combustion exhaust gas G, the dust concentration, the properties of dust, the amount of low-boiling substance droplets, and the like are substantially omitted. Since the inner diameters D and E of the tower body 1, the inner diameter of the gas supply duct 6, the eccentric amount R, and the over amount S are set accordingly, a swirling flow having an optimum speed is formed. What should I do?
[0019]
By the way, in the present embodiment, in the cross section along the duct center line C, the portion 6A on the side where the gas supply duct 6 is eccentric extends in the tangential direction of the circle formed by the connecting portion 2, and thus In this case, in order for the portion 6B opposite to the portion 6A to be located on the side opposite to the side where the gas supply duct 6 is eccentric beyond the imaginary straight line L, the eccentric amount R of the duct center line C with respect to the center axis O Must be less than 0.25 × D with respect to the inner diameter D of the connection 2. That is, when the amount of eccentricity R is 0.25 × D or more, the portion 6B on the opposite side of the gas supply duct 6 in the cross section coincides with the imaginary straight line L, or is located on the eccentric side from this Therefore, the above-described component B that suppresses the swirling flow is not generated. However, for example, when the gas supply duct 6 is connected to the connection portion 2 with a step so that the eccentric side portion 6A of the gas supply duct 6 is located on the outer periphery of the connection portion 2, the eccentric amount R is Even if it is 0.25 × D or more, it is possible to open the portion 6B on the opposite side to a position beyond the imaginary straight line L. In such a case, the gas flow is disturbed at the step portion. Therefore, the eccentric amount R is preferably 0.25 × D or less.
[0020]
On the other hand, if the eccentric amount R is too small, the duct center line C is too close to the central axis O of the connecting portion 2 and the virtual straight line L, and the component B that suppresses the swirling flow becomes too strong and the swirling flow Since the formation itself may be impossible, it is desirable that the amount of eccentricity R is 0.05 × D or more. Incidentally, in the case where the portion 6A on the side where the gas supply duct 6 is eccentric in the cross section along the duct center line C extends in the tangential direction of the circle formed by the connecting portion 2 as in the present embodiment, the eccentricity occurs. If the amount R is 0.05 × D, the over amount S of the portion 6B on the opposite side is 0.4 × D. Therefore, the over amount S is desirably 0.4 × D or less. The Rukoto.
[0021]
In the present embodiment, the inner diameter D of the connecting portion 2 of the tower body 1 to which the gas supply duct 6 is connected is made smaller than the inner diameter E of the trunk section 4 that is the other part of the tower body 1. The main body 1 is formed so as to form a multi-stage cylindrical shape, and the swirl flow formed by the connection portion 2 as described above is introduced into the body portion 4 while expanding the swirl diameter, thereby smoothly and efficiently performing the cooling process. It is made to be done. However, in the case of adopting such a configuration, the ratio E / D of the inner diameter E of the body portion 4 which is another portion with respect to the inner diameter D of the connection portion 2 is set in the range of 2 to 2.5. Desirably, when the ratio E / D is smaller than this and the difference between the inner diameter D of the connecting portion 2 and the inner diameter E of the trunk portion 4 is small, a sufficiently strong swirling flow can be formed at the connecting portion 2. While there is a risk that the gas in the body part 4 will be lost or the processing of the gas in the body part 4 will be insufficient, if this reverse ratio E / D is larger than this, the swirl flow formed in the connecting part 2 will be As the swirl flow velocity is low, the flow cannot be sufficiently expanded, and there is a possibility that a flow that vortexes in the vertical direction is generated in the body portion 4 and the processing is hindered.
[0022]
In the present embodiment, the connection part 2 to which the gas supply duct 6 is connected is arranged at the upper part of the tower body 1, but this connection part 2 is provided at the lower part of the tower body 1 to raise the swirl flow. In this way, whether the connection part 2 is provided at the upper part or the lower part of the tower body 1 is determined by the position of the exhaust gas outlet of the apparatus for discharging the gas supplied to the gas processing tower. do it. That is, in the case where the present invention is applied to the gas cooling tower of the waste incineration facility as in the present embodiment, if the exhaust gas outlet in the waste heat recovery facility such as the previous waste heat boiler is above, the connecting portion 2 is also Since the gas supply duct 6 can be shortened by providing the connection part 2 at the lower part of the tower body 1 if it is provided at the upper part of the tower body 1 and the exhaust gas outlet in the waste heat recovery equipment is lower, it is economical. It is. Moreover, in this embodiment, although the tower main body 1 and the gas supply duct 6 are made into the cylindrical shape, especially about the gas supply duct 6, you may be formed in the cross-sectional square shape.
[0023]
【The invention's effect】
As described above, according to the present invention, the gas supply duct connected to the connecting portion of the tower main body is preferably connected to the duct center line from the central axis in the cross section along the duct center line. Eccentric with respect to the inner diameter D by an eccentric amount of 0.05 × D to 0.25 × D, and beyond the imaginary straight line that intersects the central axis parallel to the duct central line from the side where the duct central line is eccentric The swirl flow formed by the gas supplied from the eccentric duct portion is suppressed by the gas supplied from the duct portion on the opposite side, thereby opening the rectifying mechanism. The strength and speed of this swirling flow can be controlled without using a gas, etc., and even if dust or liquid droplets of low-boiling substances are contained in the gas, they adhere to the inner wall of the tower body and cause corrosion and pressure loss. Increase, dust emission It is possible to prevent a failure of the apparatus.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.
2 is a ZZ cross-sectional view in FIG. 1. FIG.
[Explanation of symbols]
1 tower body 2 connection part 4 trunk (other part of tower body 1)
6 Gas supply duct 7 Cooling means O Center axis C of the tower body 1 Duct center line L Virtual straight line D parallel to the duct center line C and passing through the center axis O The inner diameter R of the connecting portion 2 The eccentric amount S of the duct center line C Gas supply Over amount E exceeding imaginary straight line L of duct 6 Inner diameter of body 4

Claims (4)

  A gas supply duct having a duct center line extending in a tangential direction of a circle centering on the central axis of the tower body is connected to the connection portion of the cylindrical tower body, and the duct center line in the connection portion The duct supply line is decentered without intersecting the central axis, and the gas supply duct is arranged from the side where the duct central line is eccentric with respect to the central axis. A gas processing tower characterized by being opened to the opposite side beyond a virtual straight line that is parallel to the line and intersects the center line.   The amount of eccentricity of the duct center line from the center axis in the transverse section is within a range of 0.05 × D to 0.25 × D with respect to the inner diameter D of the tower body at the connection portion. The gas processing tower according to claim 1, wherein   The tower body has a multistage cylindrical shape in which the inner diameter D of the connecting portion is smaller than the inner diameter E of the other portion, and the ratio E / D of these inner diameter E and inner diameter D is 2 to 2.5. The gas processing tower according to claim 1 or 2, wherein the gas processing tower is within the range of (2).   The gas processing tower according to any one of claims 1 to 3, wherein the tower body is provided with a cooling means for cooling the gas supplied from the gas supply duct.

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