JP2011194296A - Flue gas desulfurization equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide flue gas desulfurization equipment easily coping with an increase in the treatment amount, when the treatment amount of the flue gas desulfurization equipment is increased, with a simple equipment configuration.SOLUTION: The flue gas desulfurization equipment includes an absorption tower 1 which is configured to supply absorption liquid W of a liquid reservoir part 1a to the spray nozzle 2 of the upper part with a circulation pump 4, to spray the absorption liquid, bring the sprayed absorption liquid into contact with waste gas 9 introduced from the waste gas introduction port 8 of a spray nozzle 2 lower part and to remove sulfur oxides, and performs the treatment when the amount of sulfur oxides of the waste gas 9 introduced into the absorption tower 1 increases more than the planned treatment amount of the absorption tower 1. The flue gas desulfurization equipment includes an auxiliary tank 18 which communicates with the liquid reservoir part 1a of the absorption tower 1 by means of a communication pipe 17 and can store the absorption liquid W corresponding to the increase of the treatment amount and an auxiliary circulation pump 20 which supplies the absorption liquid W in the auxiliary tank 18 to the spray nozzle 2.

Description

  The present invention relates to a flue gas desulfurization apparatus that can easily cope with a case where the amount of sulfur oxide of exhaust gas introduced into an absorption tower is larger than the planned processing amount of the absorption tower and can perform stable desulfurization.

2. Description of the Related Art Conventionally, a flue gas desulfurization apparatus using calcium carbonate (CaCO ₃ ) as shown in FIG. 2 is known. The flue gas desulfurization apparatus of FIG. 2 includes an absorption tower 1 in which a liquid reservoir 1a for storing an absorption liquid W containing calcium carbonate is formed in the lower part and a multistage spray nozzle 2 is disposed in the upper part, and the absorption tower 1 A plurality of pumps (two shown by solid lines in the example of FIG. 2) for pumping up the absorbing liquid W from the liquid reservoir 1a and circulatingly supplying it to the spray nozzle 2 through the circulation flow path 3 for spraying; An oxidizing air blower 7 is provided in the absorbing liquid W of the reservoir 1a. The oxidizing air blower 7 supplies the oxidizing air 6 downward through the air nozzle 5. In FIG. 2, 8 is an exhaust gas introduction port for introducing exhaust gas 9 from a coal fired boiler or the like into the lower part of the spray nozzle 2, and 10 is an exhaust gas 9 derived through a mist eliminator 11 provided downstream of the spray nozzle 2. An exhaust gas outlet, 12 is an agitator of the absorbing liquid W provided in the liquid reservoir 1a, and 13 is an exhaust gas outlet 10 that evaporates when the absorbing liquid W contacts the exhaust gas 9 and is not recovered by the mist eliminator 11. A slurry pump for replenishing an absorbent slurry 14 in which water that is reduced by being discharged together with the exhaust gas 9 and calcium carbonate that is reduced by the reaction between sulfur and calcium carbonate is replenished, and 15 is absorption of the liquid reservoir 1a. This is a processing device for taking out a part of the liquid W and separating the gypsum.

In the flue gas desulfurization apparatus, the absorption liquid W in the liquid reservoir 1a is supplied and sprayed to the spray nozzle 2 by the operation of the circulation pump 4, and in this state, the exhaust gas 9 from a coal fired boiler or the like is introduced into the exhaust gas. When introduced into the absorption tower 1 through the port 8, the exhaust gas 9 comes into contact with the sprayed absorption liquid W to absorb and remove SO ₂ (sulfur oxide), and then the moisture is removed by the mist eliminator 11. It is discharged from the exhaust gas outlet 10 to the outside.

On the other hand, the absorbing liquid W that has absorbed SO ₂ in contact with the exhaust gas 9 falls into the liquid reservoir 1a and contacts the air 6 ejected from the air nozzle 5 to generate a gypsum slurry. A part of the absorbing liquid W including gypsum is extracted from the bottom of the liquid reservoir 1a of the absorption tower 1 and supplied to the processing device 15, where gypsum is recovered.

In the conventional flue gas desulfurization apparatus described above, the SO ₂ concentration of the exhaust gas 9 introduced into the exhaust gas inlet 8 of the absorption tower 1, the flow rate of the exhaust gas 9, and the pH of the absorbent W detected by a pH meter. On the basis of this, the number of circulating pumps 4 is adjusted so that the SO ₂ concentration of the exhaust gas 9 in the exhaust gas outlet 10 of the absorption tower 1 is less than the allowable value that complies with environmental regulations. It is set.

Therefore, even if the operating condition of the coal fired boiler changes or the sulfur content of the coal changes, the SO 9 of the exhaust gas 9 at the exhaust gas outlet 10 is increased or decreased by increasing or decreasing the number of circulating pumps 4 as described above. ₂ Concentration can be maintained within a predetermined value.

  However, in recent years, it has been demanded that coal having a sulfur content higher than that of normal coal be burned in a boiler, or that the load on the boiler be greatly (maximum) increased. In such a case, the total amount of sulfur oxides in the exhaust gas 9 introduced into the absorption tower 1 will be greatly increased. For this reason, the treatment amount of the absorption tower 1 may exceed the original planned treatment amount. .

  Thus, when the throughput of the absorption tower 1 exceeds the planned throughput, conventionally, as shown by the broken line in FIG. The required number of circulation pumps 16 corresponding to the above are additionally provided, and the discharge amount of the circulation pumps 4 and 16 is increased to increase the total discharge amount of the absorbing liquid W ejected from the spray nozzle 2, thereby reducing the processing amount. We are trying to cope with the increase.

  Patent Documents 1 and 2 and the like show general prior art of this type of conventional flue gas desulfurization apparatus.

Japanese Patent Laid-Open No. 10-192647 JP 2002-253925 A

  However, as shown by a broken line in FIG. 2, when a required number of circulation pumps 16 are additionally provided to the existing circulation pump 4 to increase the ejection amount of the absorbing liquid W from the spray nozzle 2. Had the following problems.

  Oxidizing air 6 is jetted downward by the air nozzle 5 to the absorbing liquid W in the liquid reservoir 1a, and the bubbles of the air 6 come into contact with the absorbing liquid W when rising in the absorbing liquid W. Oxidation reaction is performed to produce gypsum. As described above, when the absorption liquid W in the liquid reservoir 1a is sucked by the operation of the existing circulation pump 4 and the additional circulation pump 16, the liquid reservoir 1a. Since the descending speed of the absorbent liquid W becomes faster than the planned value, a part of the air 6 ejected from the air nozzle 5 is sucked into the circulation pumps 4 and 16 before ascending the absorbent liquid W. For this reason, there is a problem in that the oxidation reaction becomes insufficient and the generation of gypsum is not stably performed. Further, the circulation pumps 4 and 16 vibrate by sucking the air 6, and the circulation pumps 4 and 16 There is a problem that the lifetime is shortened.

  Therefore, when the additional circulation pump 16 is provided as described above, the arrangement position and configuration of the air nozzle 5 need to be changed accordingly.

  In order to prevent the above problem, as shown in FIG. 3, the capacity (diameter dimension) of the liquid reservoir 1a ′ of the absorption tower 1 is increased in order to cope with an increase in the amount of sulfur oxide in the exhaust gas 9. Thus, it is considered that even if the additional circulation pump 16 is provided, the descending speed of the absorbing liquid W is not increased. In this case, the absorption tower 1 needs to be significantly modified. Therefore, there is a problem that the cost increases.

  The present invention has been made in view of such circumstances, and a flue gas desulfurization apparatus that can easily cope with a simple apparatus configuration when the amount of sulfur oxide of exhaust gas increases from the planned throughput of the absorption tower. It is something to be offered.

  In the present invention, the absorbing liquid in the liquid reservoir is supplied to the upper spray nozzle by a circulation pump and sprayed, and the sulfur oxide is removed by contacting with the exhaust gas introduced from the exhaust gas inlet at the lower part of the spray nozzle. A flue gas desulfurization apparatus comprising an absorption tower and configured to be able to perform treatment when the amount of sulfur oxides of exhaust gas introduced into the absorption tower is greater than the planned treatment amount of the absorption tower. And an auxiliary tank capable of storing the absorbing liquid corresponding to the increase in the processing amount by communicating with the communication pipe, and an auxiliary circulation pump for supplying the absorbing liquid in the auxiliary tank to the spray nozzle. This relates to a flue gas desulfurization apparatus.

  In the above flue gas desulfurization apparatus, it is preferable that a strainer is provided in the opening in the absorption tower of the communication pipe.

  According to the flue gas desulfurization device of the present invention, the auxiliary tank communicating with the liquid reservoir of the absorption tower is provided to increase the substantial capacity of the liquid reservoir, and the absorbent in the auxiliary tank is sprayed by the auxiliary circulation pump. Since it is supplied to the nozzle, when the amount of sulfur oxides in the exhaust gas increases from the planned throughput of the absorption tower, it can be easily handled without changing the configuration of the existing absorption tower. An excellent effect can be obtained that the problem that the descending speed of the absorption liquid is prevented and the problem that the circulation pump sucks air can be prevented.

1 is a schematic side sectional view showing an example of a flue gas desulfurization apparatus that is an embodiment of the present invention. It is a side cross-sectional schematic diagram which shows an example of the conventional flue gas desulfurization apparatus. It is the side cross-sectional schematic which shows the example of a modification for the throughput increase of the conventional flue gas desulfurization apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic side sectional view showing an example of a flue gas desulfurization apparatus according to an embodiment of the present invention. In FIG. 1, portions denoted by the same reference numerals as those in FIG.

  As shown in FIG. 1, the absorption liquid W in the liquid reservoir 1 a of the absorption tower 1 is supplied by the circulation pump 4 to the spray nozzle 2 provided in the upper part of the absorption tower 1 and injected, and the exhaust gas inlet 8 at the lower part of the spray nozzle 2 is injected. In the flue gas desulfurization apparatus in which the sulfur oxide is removed by contacting with the exhaust gas 9 introduced from the exhaust gas 9, the amount of sulfur oxide of the exhaust gas 9 introduced into the absorption tower 1 is greater than the planned throughput of the absorption tower 1. In order to cope with the case, the absorption tower 1 is provided with an auxiliary tank 18 that communicates with the liquid reservoir 1 a of the absorption tower 1 through a communication pipe 17. The auxiliary tank 18 is provided so as to maintain the same liquid level as the absorption liquid W of the absorption tower 1, and the auxiliary tank 18 has a capacity corresponding to an increase in the amount of sulfur oxide in the exhaust gas 9. .

  Further, an auxiliary circulation channel 19 for guiding the absorbing liquid W in the auxiliary tank 18 to the circulation channel 3 is provided, and the auxiliary circulation channel 19 includes a required number of auxiliary circulation pumps 20 (see FIG. 1 shows a case where one auxiliary circulation pump 20 is provided), so that the absorption liquid W in the auxiliary tank 18 can be supplied to the spray nozzle 2 by the auxiliary circulation pump 20. In FIG. 1, reference numeral 21 denotes a stirrer provided in the auxiliary tank 18.

  In addition, a strainer 23 is provided at the opening 22 in the absorption tower 1 in the communication pipe 17 to prevent solids from being sucked from the opening 22. The gypsum does not solidify in the liquid reservoir 1a of the absorption tower 1 to produce solid matter, and the absorption liquid W constantly flows inside the communication pipe 17 by the operation of the auxiliary circulation pump 20. Since the solid matter does not stay in the communication pipe 17, the installation of the strainer 23 can be omitted, but it is preferable to install it in consideration of an unexpected situation where the solid matter is mixed.

  Next, the operation of the above embodiment will be described.

  As shown in FIG. 1, in the absorption tower 1 provided with the auxiliary tank 18, the amount of sulfur oxides in the exhaust gas 9 introduced into the absorption tower 1 when coal having a high sulfur content is supplied to the boiler. When the amount exceeds the planned throughput, or when the load on the boiler is significantly increased (to the maximum), the total sulfur oxide content of the exhaust gas 9 introduced into the absorption tower 1 is the planned throughput of the absorption tower 1. If the circulation pump 4 is increased, the circulating pump 4 is operated to supply the absorbing liquid W in the liquid reservoir 1a of the absorption tower 1 to the spray nozzle 2 and the required number of auxiliary circulating pumps 20 provided in the auxiliary tank 18 Is operated to supply the absorbing liquid W in the auxiliary tank 18 to the spray nozzle 2. At this time, the number of operating auxiliary circulation pumps 20 is set according to the increase in the amount of sulfur oxides in the exhaust gas 9. Thereby, the injection amount of the absorbing liquid W injected from the spray nozzle 2 is increased according to the increase in the amount of sulfur oxide in the exhaust gas 9.

  At this time, when the auxiliary circulation pump 20 is operated and the absorbing liquid W in the auxiliary tank 18 is supplied to the spray nozzle 2, the absorbing liquid W in the auxiliary tank 18 is reduced. Since the liquid is supplied from 1a through the communication pipe 17, the liquid level of the absorption liquid W in the auxiliary tank 18 and the liquid reservoir 1a is always kept the same. At this time, the liquid level of the absorption liquid W in the auxiliary tank 18 and the liquid reservoir 1a is maintained at the same level as in the conventional case including only the absorption tower 1, and therefore the entire absorption liquid W The amount increases by the amount stored in the auxiliary tank 18.

According to the above, the sulfur oxide of the exhaust gas 9 introduced into the absorption tower 1 with an increased amount of sulfur oxide is successfully removed by the increased absorption liquid W injected from the spray nozzle 2, The SO ₂ concentration of the exhaust gas 9 at the exhaust gas outlet 10 of the absorption tower 1 is kept below an allowable value that complies with environmental regulations.

  At this time, by providing the auxiliary tank 18 that communicates with the liquid reservoir 1a of the absorption tower 1 as described above, the volume of the liquid reservoir 1a of the absorption tower 1 is substantially the same, and accordingly, As the absorption liquid W in the liquid reservoir 1a is sucked by the circulation pump 4, the lowering speed of the absorption liquid W in the liquid reservoir 1a is not increased, and the lowering is equivalent to that in the design with the absorption tower 1 alone. Since the speed is maintained, it is possible to prevent the problem that the bubbles of the air 6 ejected from the air nozzle 5 are sucked into the circulation pump 4, and to stabilize the oxidation reaction.

  As described above, the provision of the auxiliary tank 18 communicating with the liquid reservoir 1a of the absorption tower 1 makes it easy to increase the amount of sulfur oxide in the exhaust gas 9 without changing the configuration of the existing absorption tower 1. It becomes possible to cope with.

  In addition, the flue gas desulfurization apparatus of the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Absorption tower 1a Liquid storage part 2 Spray nozzle 4 Circulation pump 8 Exhaust gas inlet 9 Exhaust gas 10 Exhaust gas outlet 17 Communication pipe 18 Auxiliary tank 20 Auxiliary circulation pump 22 Opening 23 Strainer W Absorption liquid

Claims (2)

  It has an absorption tower that removes the sulfur oxide by supplying the liquid in the liquid reservoir to the upper spray nozzle by a circulation pump and spraying it, and contacting with the exhaust gas introduced from the exhaust gas inlet at the lower part of the spray nozzle. A flue gas desulfurization apparatus capable of performing treatment when the amount of sulfur oxides in the exhaust gas introduced into the absorption tower is greater than the planned treatment amount of the absorption tower, wherein the flue gas desulfurization apparatus communicates with the liquid reservoir of the absorption tower An exhaust gas desulfurization apparatus comprising an auxiliary tank capable of storing an absorbing liquid that communicates with an increase in the amount of processing, and an auxiliary circulation pump that supplies the absorbing liquid in the auxiliary tank to the spray nozzle .   The flue gas desulfurization apparatus according to claim 1, wherein a strainer is provided at an opening in the absorption tower of the communication pipe.

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