JP2015042389A - Exhaust gas desulfurizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas desulfurizer capable of efficiently desulfurizing exhaust gas while suppressing equipment cost and operation cost as much as possible.SOLUTION: A multi-stage spray header (10) provided in an absorption tower (2) is configured so that first spray nozzles (21) spraying hollow conical spray downward in two directions are provided at a center of a first-stage spray header (11) located on an uppermost stage, second spray nozzles (22) vertically spraying hollow conical spray are provided at centers of second and third spray headers (12, 13), third spray nozzles (23) spraying solid conical spray downward or in two-way direction are provided near tower walls in the first spray header (11), fourth spray nozzles (24) vertically spraying solid conical spray are provided near the tower walls in the second-stage and third-stage spray headers (12, 13), and fifth spray nozzles (25) spraying hollow conical spray downward are provided in a fourth-stage spray header (14) to a sixth-stage spray header (16).

Description

  The present invention relates to a flue gas desulfurization device used to remove sulfur oxides in exhaust gas (fumes) generated by burning fossil fuel, for example.

In general, a thermal power generation facility or the like is provided with a flue gas desulfurization device in order to remove sulfur contained in exhaust gas generated by burning fossil fuel such as coal.
The types of flue gas desulfurization devices are roughly classified into wet, semi-dry, and dry types, and many efficient wet flue gas desulfurization devices are used. However, the wet type flue gas desulfurization apparatus has a problem that the equipment cost and the operation cost are high while it is highly efficient.

  A wet type flue gas desulfurization device has spray headers arranged in multiple stages in the flow direction of exhaust gas in an absorption tower in which exhaust gas circulates, and an absorption liquid that absorbs sulfur from a plurality of spray nozzles attached to the spray header is contained in the exhaust gas. Desulfurization is performed by injecting into the tank. Therefore, in order to improve the efficiency of desulfurization, it is necessary to disperse the absorption liquid finely and increase the gas-liquid contact area with the exhaust gas.

  Therefore, as the spray nozzle, a bidirectional spray nozzle capable of injecting the absorbing liquid in both upward and downward directions is used, and for the bidirectional spray nozzle in the lowermost stage or in the vicinity of the lowermost stage, the upward absorbing liquid injection amount and the downward absorbing liquid injection amount. The ratio (upward injection amount / downward injection amount) is in the range of 0.1 to 0.9, and for the other-stage bidirectional spray nozzles, the upward and downward absorbing liquid injection amounts are the same or substantially the same amount. A flue gas desulfurization apparatus having a configuration has been developed (see Patent Document 1).

JP 2004-237258 A

  In the above-mentioned Patent Document 1, all of the spray nozzles in the absorption tower are made up and down bidirectional nozzles, and the lowermost spray nozzle has a lower absorption liquid injection amount than a downward absorption liquid injection amount, thereby reducing desulfurization. Although efficiency and reduction of exhaust gas pressure loss are attempted, if all of the spray nozzles are upper and lower bidirectional spray nozzles, there is a problem that the equipment cost and operation cost of the flue gas desulfurization apparatus are further increased.

In addition, there are areas where gas-liquid contact is difficult to be performed effectively in the absorption tower, and areas where it is difficult to actively inject the absorbing liquid, and the efficiency of desulfurization is improved by uniformly injecting the absorbing liquid regardless of these areas. It is difficult to raise.
For example, when the absorbing liquid is injected upward in the uppermost spray nozzle as in Patent Document 1, the absorbing liquid scatters to the mist eliminator provided at the exhaust gas outlet portion of the absorption tower, and the performance of the mist eliminator decreases. Or the absorbent may be transported from the absorption tower to the equipment downstream of the exhaust gas.

Furthermore, in the vicinity of the tower wall of the absorption tower where the exhaust gas is easy to blow through and it is difficult to make gas-liquid contact, there is a problem in that the tower wall is worn if the gas-liquid contact is effectively performed by increasing the injection pressure of the absorbing liquid. is there.
The present invention has been made to solve such problems, and the object of the present invention is to keep equipment costs and operation costs as low as possible by arranging appropriate spray nozzles at appropriate positions inside the absorption tower. It is another object of the present invention to provide a flue gas desulfurization apparatus that can efficiently desulfurize exhaust gas.

  In order to achieve the above-described object, a flue gas desulfurization apparatus according to the present invention includes an absorption tower in which exhaust gas flows in the vertical direction, a spray header arranged in multiple stages in the flow direction of the exhaust gas, and an absorbent attached to the spray header. A spray flue gas desulfurization device having a spray nozzle for spraying, wherein the first exhaust sprayer is attached to the spray header located at the top of the multi-stage spray header, and sprays a hollow cone-shaped spray downward and in at least two directions. A spray nozzle and a second spray nozzle that is attached to the two or more successive spray headers excluding the spray header located at the uppermost stage among the multi-stage spray headers, and injects a hollow conical spray upward and downward; It is characterized by having.

  Further, a third spray nozzle that is attached near the tower wall of the absorption tower in the spray header located at the uppermost stage and injects a solid conical spray downward and at least bifurcated, and the two or more continuous spray headers A fourth spray nozzle that is attached in the vicinity of the tower wall of the absorption tower and injects a solid conical spray upward and downward, and the first spray nozzle is disposed in the spray header located at the uppermost stage. Preferably, the second spray nozzle is attached to the inner side of the fourth spray nozzle in the two or more continuous spray headers.

Moreover, it is preferable that the 5th spray nozzle which injects spraying downward is attached to the spray headers other than the spray header located in the uppermost stage and the two or more continuous spray headers.
In particular, the two or more continuous spray headers are preferably two-stage spray headers located immediately below the uppermost spray header.

  According to the present invention using the above means, by disposing different types of spray nozzles in the optimum regions according to the flow of exhaust gas in the absorption tower, respectively, while minimizing equipment costs and operating costs, Sufficient desulfurization efficiency can be secured and the desulfurization efficiency of the absorption tower as a whole can be improved.

It is a schematic block diagram of the flue gas desulfurization apparatus which concerns on one Embodiment of this invention. It is the principal part enlarged view to which the upper four-stage spray header in FIG. 1 was expanded. It is sectional drawing which follows the AA line of FIG. It is sectional drawing which follows the BB line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a flue gas desulfurization apparatus according to an embodiment of the present invention.
A flue gas desulfurization apparatus 1 shown in FIG. 1 is provided as a part of an exhaust gas treatment system of a thermal power generation facility. For example, in a flue from a coal-fired boiler to a chimney, a denitration unit, an air heater, a dedusting unit, and It is arranged following the heat exchanger.

  As shown in FIG. 1, the flue gas desulfurization apparatus 1 has a cylindrical absorption tower 2 in which exhaust gas flows in a vertical direction from a gas introduction part 2 a on the lower side surface toward a gas discharge part 2 b on the upper side. In the lower part of the absorption tower 2, an absorption liquid storage section 3 is formed for storing an absorption liquid containing limestone as an absorbent.

One end of an absorption liquid circulation pipe 4 is connected to the absorption liquid storage section 3, and a circulation pump 5 is interposed in the absorption liquid circulation pipe 4.
A spray header 10 is arranged in multiple stages in the exhaust gas flow direction at the central portion in the height direction in the absorption tower 2, and the other end side of the absorbent circulation pipe 4 is branched into a large number and connected to the multi-stage spray header 10. . In the present embodiment, six-stage spray headers 10 from the first-stage spray header 11 to the sixth-stage spray header 16 are arranged in order from the top. Each spray header 10 is provided with a plurality of spray nozzles 20 for injecting absorbing liquid.

And in the absorption tower 2, the mist eliminator 6 which removes the mist accompanying in the exhaust gas after desulfurization is provided above each spray header 10.
Here, the spray nozzle 20 provided in each spray header 10 will be described in detail. 2 is an enlarged view of an essential part of the upper four-stage spray header in FIG. 1, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is taken along line BB in FIG. A sectional view along each is shown.

As shown by a one-dot chain line in FIGS. 1 and 2, five regions S <b> 1 to S <b> 5 including a group of five types of spray nozzles 21 to 25 are formed in the absorption tower 2.
Specifically, the first spray region S1 is formed on the center side (inside) of the first stage spray header 11 located at the uppermost stage, and the second stage spray header 12 and the third stage spray header 13 (hereinafter also referred to as the second stage / third stage). The second spray region S2 is located at the center (inside) of the stage spray headers 12 and 13, the third spray region S 3 is located near the tower wall of the first stage spray header 11, and the second and third stage spray headers 12. The fourth spray region S4 is formed in the vicinity of the tower wall of 13, and the fifth spray region S5 is formed from the fourth stage spray header 14 to the sixth stage spray header 16, respectively.

In the first spray region S1, a plurality of first spray nozzles 21 are attached to the first stage spray header 11 to inject a hollow cone-shaped (so-called holocone-shaped) spray downward and in two different directions.
In the second spray region S2, a plurality of second spray nozzles 22 for injecting a hollow conical spray downward and upward are attached to the second and third stage spray headers 12 and 13, respectively.

In the third spray region S3, a plurality of third spray nozzles 23 for injecting a solid conical (so-called full cone) spray downward and bifurcated onto the first stage spray header 11 are attached.
In the fourth spray region S4, a plurality of fourth spray nozzles 24 for injecting a solid conical spray downward and upward are attached to the second and third stage spray headers 12 and 13, respectively.

In the fifth spray region S5, a plurality of fifth spray nozzles 25 for injecting a hollow conical spray downward are attached from the fourth stage spray header 14 to the sixth stage spray header 16.
Each of these spray nozzles 21 to 25 is configured such that the conical spray rotates around the axis in the respective injection direction to form a spiral shape.

  Specifically, as shown in FIG. 3, the first stage spray header 11 has a plurality of sub-headers 11b bifurcated symmetrically from one main header 11a extending in the radial direction of the absorption tower 2, and the sub-headers 11b Various spray nozzles 21 and 23 are attached. Specifically, the third spray nozzle 23 is attached to the subheader 11b extending from the tip and root of the main header 11a and the tip of the other subheader 11b. Thereby, in the 1st stage spray header 11, 3rd spray area | region S3 which consists of a group of the 3rd spray nozzle 23 is formed in the tower wall vicinity.

  In the first stage spray header 11, the first spray nozzle 21 is attached to the sub header 11b extending from the central side excluding the sub header 11b extending from the tip and root of the main header 11a except for the tip. Thereby, in the 1st stage spray header 11, 1st spray area | region S1 which consists of a group of the 1st spray nozzle 21 is formed.

  Further, as shown in FIG. 4, the second stage spray header 12 is composed of a main header 12a and a sub-header 12b as in the case of the first stage spray header 11, but the main header 12a is in top view with the main header 11a in the uppermost stage. At about 30 degrees and extends in the radial direction of the absorption tower 2.

  And in the 2nd stage spray header 12, the 4th spray nozzle 24 is attached to the subheader 12b extended from the front-end | tip part and root part of the main header 12a, and the front-end | tip of the other subheader 12b. Thereby, in the 2nd stage spray header 12, 4th spray area | region S4 which consists of a group of the 4th spray nozzle 24 is formed in the tower wall vicinity.

  Moreover, the 2nd spray nozzle 22 is attached to the subheader 12b extended from the center side except the subheader 12b extended from the front-end | tip part and root part of the main header 12a except for a front-end | tip. Thereby, in the second stage spray header 12, a fourth spray region S2 composed of a group of second spray nozzles 22 is formed.

  Although the third stage spray header 13 is not shown, the second spray nozzle 22 and the fourth spray nozzle 24 are attached in the same configuration as the second stage spray header 12. The fourth-stage spray header 14 to the sixth-stage spray header 16 are not shown, but are composed of a main header and a sub-header, and a fifth spray nozzle 25 is attached to each sub-header. Note that the main header at each stage is arranged so as to be shifted from the main header at the upper stage by about 30 degrees in a top view.

Hereinafter, the operation and effect of the flue gas desulfurization apparatus 1 configured as described above will be described.
Exhaust gas generated in a coal-fired boiler (not shown) flows into the absorption tower 2 from the gas introduction section 2a through the denitration section, the air heater, the dust removal section, and the heat exchanger, and goes up in the absorption tower 2.
At this time, by driving the circulation pump 5, the absorbent is sent from the absorbent reservoir 3 to the spray header 10 of each stage via the absorbent circulation pipe 4, and the absorbent is ejected from each spray nozzle 20.

  In the fifth spray region S5 corresponding to the range of the lower three-stage fourth-stage spray header 14 to the sixth-stage spray header 16, a hollow conical shape is formed downward from the fifth spray nozzle 25 over the entire cross section of the absorption tower 2. Absorbing liquid is injected. In the second-stage and third-stage spray headers 12 and 13, the absorbing liquid is ejected in the vertical direction by the second spray nozzle 22 in the second spray area S2 and the fourth spray nozzle 24 in the fourth spray area S4. Is done. In the uppermost first-stage spray header 11, the absorbing liquid is jetted in two downward directions by the first spray nozzle 21 in the first spray area S1, and downward in two directions by the third spray nozzle 23 in the third spray area S3. Is done.

  In the fifth spray region S5, an increase in equipment cost is suppressed by using the fifth spray nozzle 25, which is a simple structure that injects the absorbing liquid only downward and is inexpensive. On the other hand, in the fifth spray region S5, since the absorbing liquid sprayed from above falls, a large amount of absorbing liquid exists over the entire area, and the fifth spray region S5 The exhaust gas passing therethrough can be sufficiently desulfurized.

  Next, in the second spray region S2 and the fourth spray region S4 through which the exhaust gas passes, the absorbing liquid sprayed in the vertical direction collides with the absorbing liquid sprayed in the vertical direction, and the absorbing liquid is fine. Is promoted. As the absorption liquid is further miniaturized in this way, the specific surface area of the droplet is increased and the efficiency of gas-liquid contact is improved, and the exhaust gas is desulfurized also in the second spray area S2 and the fourth spray area S4. Well done.

  In the first spray region S1 and the third spray region S3 located at the uppermost stage, it is possible to prevent the absorption liquid from scattering to the downstream side by spraying the absorption liquid only downward. On the other hand, since the absorbing liquid is jetted in two directions or bifurcated from one spray nozzle 21, 23, the density of the absorbing liquid increases and the absorbing liquid collides in the lateral direction to make the absorbing liquid finer. Is promoted. Further, since each spray from each spray nozzle 20 is rotating, the exhaust gas passing through the vicinity of the spray is brought into a turbulent state, and the gas-liquid contact is further promoted.

  Furthermore, in the 3rd spray area | region S3 and 4th spray area | region S4 located in the tower wall vicinity, by injecting a solid cone-shaped spray, rather than the hollow cone-shaped spray with which the pressure with respect to a tower wall concentrates The load applied to the tower wall can be reduced and the wear of the tower wall can be suppressed. In addition, by injecting a solid conical spray, the density of the absorbing liquid in the vicinity of the tower wall increases, and the exhaust gas can be guided to the center side, thereby preventing the exhaust gas from being blown through the tower wall. it can.

  As described above, in the flue gas desulfurization apparatus 1 according to the present embodiment, as many as five types of spray nozzles 20 are arranged in the optimum regions according to the flow of exhaust gas in the absorption tower 2, and the use of expensive spray nozzles is reduced. And equipment costs can be minimized. In addition, since the nozzle arrangement is appropriate, the efficiency can be increased and the operation cost can be reduced. And the desulfurization efficiency as the whole of the absorption tower 2 can be improved by ensuring sufficient desulfurization efficiency in each area | region.

Although the description about the embodiment of the flue gas desulfurization apparatus according to the present invention is finished above, the embodiment is not limited to the above embodiment.
In the above embodiment, the absorption tower 2 has a cylindrical shape, and each stage of the spray header 10 is composed of a main header and a sub header. However, the structure of the absorption tower and the spray header is not limited to this, for example, the absorption tower has a rectangular cross section. It is good also as a structure of the spray header matched to the said square absorption tower.

  Further, as in the above embodiment, it is costly to form the second spray area S2 and the fourth spray area S4 in the second and third stage spray headers 12 and 13 immediately below the first stage spray header 11 which is the uppermost stage. Although most effective in terms of desulfurization efficiency, the second spray region and the fourth spray region can be formed in two or more continuous spray headers to obtain a certain effect. Therefore, for example, the second spray region and the fourth spray region may be formed not only in the second and third spray headers but also in the fourth spray header and the fifth spray header. Alternatively, instead of directly below the first stage spray header, the spray nozzle of the second stage spray header may be the fifth spray nozzle only facing downward, and the second spray header and the fourth spray header may be attached to the third spray header and the fourth spray header. Good.

  Furthermore, the third spray nozzle 23 and the fourth spray nozzle 24 are not provided, the first spray nozzle 21 is attached to the entire area of the first stage spray header 11, and the second spray nozzle 22 is attached to the entire area of the second stage spray header 12, You may comprise only 1st spray area | region S1, 2nd spray area | region S2, and 5th spray area | region S5. Even in this case, at least the effect of miniaturization of the absorbing solution can be obtained.

  Further, the first spray nozzle in the above embodiment is a spray nozzle that injects spray in two downward directions. If the first spray nozzle is in the downward direction, spray can be sprayed in multiple directions such as three directions and four directions. A spray nozzle may be used. The third spray nozzle may also be a spray nozzle capable of spraying a three-way spray.

  Moreover, in the said embodiment, although the 5th spray nozzle 25 is a spray nozzle which injects a hollow cone-shaped spray downward, the spray shape of the said 5th spray nozzle is not restricted to this. For example, the fifth spray nozzle may be a spray nozzle that sprays a solid conical spray downward. Further, a spiral nozzle that is a low power spray nozzle may be used as the fifth spray nozzle, thereby reducing the operating cost of the flue gas desulfurization apparatus.

  Further, the flue gas desulfurization apparatus 1 in the above embodiment is disposed in the flue of the coal fired boiler following the denitration part, the air heater, the dedusting part, and the heat exchanger, but the flue gas desulfurization apparatus according to the present invention is The present invention can also be applied to other configurations of thermal power generation facilities.

DESCRIPTION OF SYMBOLS 1 Flue gas desulfurization apparatus 2 Absorption tower 10 Spray header 11 1st stage spray header 12 2nd stage spray header 13 3rd stage spray header 14 4th stage spray header 15 5th stage spray header 16 6th stage spray header 20 6th stage spray header 21 1st spray nozzle 22 2nd Spray nozzle 23 third spray nozzle 24 fourth spray nozzle 25 fifth spray nozzle S1 first spray area S2 second spray area S3 third spray area S4 fourth spray area S5 fifth spray area

Claims (4)

A flue gas desulfurization device having an absorption tower in which exhaust gas flows in the vertical direction, spray headers arranged in multiple stages in the flow direction of the exhaust gas, and spray nozzles attached to the spray header and injecting absorbent.
A first spray nozzle that is attached to the spray header located at the top of the multi-stage spray header and injects a hollow conical spray downward and in at least two directions;
A second spray nozzle that is attached to the two or more successive spray headers excluding the spray header located at the uppermost stage among the multi-stage spray headers, and injects a hollow conical spray upward and downward;
A flue gas desulfurization apparatus comprising: A third spray nozzle that is attached in the vicinity of the tower wall of the absorption tower in the spray header located at the uppermost stage, and injects a solid conical spray downward and at least bifurcated;
A fourth spray nozzle that is attached near the tower wall of the absorption tower in the two or more continuous spray headers and that injects a solid conical spray upward and downward;
The first spray nozzle is attached to the inner side of the third spray nozzle in the spray header located at the uppermost stage,
2. The flue gas desulfurization apparatus according to claim 1, wherein the second spray nozzle is attached to the inner side of the fourth spray nozzle in the two or more continuous spray headers.   5. The exhaust nozzle according to claim 1, wherein a spray header other than the spray header located at the uppermost stage and the two or more continuous spray headers is attached with a fifth spray nozzle that sprays spray downward. Smoke desulfurization equipment.   The flue gas desulfurization apparatus according to any one of claims 1 to 3, wherein the two or more continuous spray headers are two-stage spray headers located immediately below the uppermost spray header.

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