JPH0889753A - Wet stack gas desulfurizing method and device therefor - Google Patents

Abstract

PURPOSE: To enable energy saving operation and low cost operation and to facilitate the starting of an oxidation agitator for an absorbing solution slurry in an absorption tower. CONSTITUTION: The oxidation agitator 7 is started after water 12 is poured into an oxidation agitator sleeve 101 and a solid matter stuck in the sleeve 101 is discharged out of the sleeve 101 by agitating in the sleeve 101 with the jet stream of the water 12 direct before the starting of the oxidation agitator 7. By starting the oxidation agitator 7 after that, a supplied air has no trouble and the main shaft 102 of the oxidation agitator 7 is not brought into contact with the solid matter to prevent the wear of the main shaft 102. And when the water 12 is poured in the sleeve 101 direct after the stop of the operation of the oxidation agitator 7, the discharge of the solid matter by pouring the water 12 just before the starting is easily executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-column oxidation type wet flue gas desulfurization method and apparatus.

[0002]

2. Description of the Related Art In recent thermal power plants, DSS (Daily Start Start) is reflected in view of the increasing difference in power consumption between summer and winter and daytime and nighttime.
p), WSS (Weekly Start Stop)
Intermediate load operation including operation is becoming more frequent. Along with this, even with the conventional wet flue gas desulfurization equipment, thorough energy-saving operation and rationalization of equipment are required, and a horizontal oxidation stirrer is installed on the side wall of the absorption tower.
An in-column oxidation system is adopted in which air is supplied from the vicinity of the stirrer into the absorbing liquid slurry in the absorbing tower to turn calcium sulfite in the slurry into gypsum. Here, a conventional technique will be described with reference to FIG. The slurry of limestone, which is the absorbent stored in the lower part of the absorption tower 1, is sprayed in the upper part of the absorption tower 1 by the circulation pump 5 and comes into gas-liquid contact with the boiler exhaust gas 3 introduced into the absorption tower 1, whereby the boiler exhaust gas 3 is Desulfurized. The desulfurized gas passes through the mist eliminator 2 and is discharged as a clean gas 4. On the other hand, the limestone slurry 9 supplied to the absorption tower 1 is circulated and sprayed to the upper part of the absorption tower 1 via the circulation pump 5, absorbs SO ₂ , and becomes an absorption liquid slurry containing calcium sulfite as a reaction product. Further, the absorption tower 1 is provided with an absorption tower stirrer 6 for preventing the accumulation of the absorption liquid slurry and an oxidation stirrer 7 for supplying air 10 to turn calcium sulfite in the absorption liquid slurry into gypsum.

FIG. 5 shows the structure of the agitator 7 for oxidation. A sleeve 101 for supplying air 10 is provided outside the main shaft 102. The air 10 passes through the sleeve 101 and is made into fine bubbles in the absorbent slurry by the propeller 103 in order to further improve the oxidation performance, and converts the calcium sulfite in the absorbent slurry into gypsum. On the other hand, as shown in FIG. 4, a part of the absorbent slurry in the absorption tower 1 is extracted into the gypsum separator 8 and dehydrated to be recovered as gypsum 11.
By the way, the oxidation stirrer 7 is basically operated continuously like the absorption tower stirrer 6 for preventing slurry sedimentation, and due to thorough energy saving operation associated with DSS and WSS, the inside of the absorption tower 1 is No consideration was given to stopping the operation of the absorption tower stirrer 6 and the oxidation stirrer 7 while the absorption liquid slurry was being stored therein.

[0004]

In the above-mentioned prior art, D
When the SS and WSS operations are stopped, etc., when the operation of the oxidizing agitator 7 is stopped while the absorption liquid slurry containing the limestone slurry 9 is stored in the absorption tower 1, and the supply of the air 10 is stopped, the operation is stopped. The absorbent slurry in the absorption tower 1 flows back into the sleeve 101 of the oxidizing agitator 7 from the air ejection port of the sleeve 101, and solid matter adheres to the inside of the sleeve 101. If the oxidizing stirrer 7 is restarted and operated while the solid matter remains attached to the sleeve 101, the air 10 to be supplied will be hindered, and in some cases, the solid matter and the main shaft 102 of the oxidizing stirrer 7 will come into contact with each other. However, there is a problem that the main shaft 102 is worn.

Further, FIG. 6 shows a device of the present applicant (actual fairness 2
No. 39544), in order to prevent solids from adhering to the jet 105 of the oxidizing air 10 provided near the oxidizing stirrer 7, along the central axis of the oxidizing air jet 105. There is disclosed a configuration in which a spray nozzle 104 for spraying cleaning water extending in the outlet direction is provided and water is constantly supplied to the spray nozzle 104. However, in this method, it is necessary to constantly spray water from the spray nozzle 104, and furthermore, the sleeve 107 forming the jet outlet 105 of the oxidizing air 10 is provided at a location different from the main shaft 108 of the oxidizing stirrer 7. It is necessary to provide it, which is disadvantageous in cost. An object of the present invention is to provide a wet flue gas desulfurization apparatus that enables energy saving operation and low cost operation. Another object of the present invention is to provide a wet flue gas desulfurization device in which an agitator for oxidizing the absorbent slurry in an absorption tower can be easily started. It is an object of the present invention to provide a wet flue gas desulfurization device in which abrasion of an agitator main shaft for oxidizing an absorbent slurry in an absorption tower is prevented.

[0006]

The above object of the present invention can be achieved by the following constitutions. That is, after the exhaust gas introduced into the absorption tower and the absorbent slurry are brought into gas-liquid contact, air is supplied to the oxidizing air section of the absorbent slurry storage section provided in the lower part of the absorption tower to oxidize the absorbent slurry. In the wet flue gas desulfurization method, immediately before or immediately after starting the stirrer for stirring the oxidizing air in the storage part of the absorbing liquid slurry,
A wet flue gas desulfurization method of injecting water into the oxidizing air supply part of the storage part, or an exhaust gas introduction part and an absorption liquid slurry spraying part provided in the upper part of the absorption tower, and the absorption liquid slurry storage part in the lower part of the absorption tower. In a wet flue gas desulfurization apparatus provided with an absorbent liquid circulation supply unit and an oxidizing air supply unit to a slurry spray unit, an oxidizing air stirrer is provided in an absorbent slurry storage unit at the bottom of an absorption tower to agitate the oxidizing air. A wet flue gas desulfurization apparatus in which a sleeve constituting the air supply unit is provided near the machine, and a water injection unit for cleaning the inner wall of the sleeve is further provided in the sleeve, or
A wet exhaust system in which an exhaust gas introduction part and an absorbing liquid slurry spraying part are provided in the upper part of the absorption tower, and an absorbing liquid slurry circulation path to the absorbing liquid slurry spraying part and an oxidizing air supply part are provided in the absorbing liquid slurry storage part in the lower part of the absorption tower. In the smoke desulfurization device, an oxidizing air agitator is provided in the absorbent slurry storage section at the lower part of the absorption tower, a sleeve constituting the air supply section is provided in the vicinity of the oxidizing air agitator, and the sleeve is for supplying water. The wet flue gas desulfurization apparatus is provided with a water injection part having an on-off valve, and a control device for opening the water supply on-off valve immediately before starting or immediately after stopping the oxidizing air agitator in the water injection part. In the wet flue gas desulfurization apparatus of the present invention, the sleeve forming the air supply unit can be provided around the main shaft of the oxidizing air agitator.

[0007]

Function: Water is injected into the sleeve of the oxidizing stirrer immediately before starting the oxidizing stirrer. As a result, the inside of the sleeve is agitated by the jet of water, and while the oxidizing agitator is stopped, the solid matter deposited and accumulated inside the sleeve due to the reverse flow of the absorbing liquid slurry is discharged to the outside of the sleeve. If the oxidizing agitator is started after discharging the adhered / accumulated solids to the outside of the sleeve, the supply air will not be obstructed, and the solids will not contact the spindle of the oxidizing agitator. Wear can be eliminated. In addition, once water is injected into the sleeve immediately after the operation of the agitation stirrer is stopped, the solid matter can be easily discharged by the water injection immediately before starting.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are schematic configuration diagrams of an apparatus showing an embodiment of the present invention. Components of the apparatus shown in FIGS. 1 and 2 having the same functions as those shown in FIG. 4 are designated by the same reference numerals and their description is omitted, but the apparatus shown in FIGS. 1 and 2 is shown in FIG. In addition to the apparatus, the water 12 can be injected into the portion of the oxidation stirrer 7. FIG. 2 shows a configuration diagram of the oxidizing stirrer 7 for executing the starting method of the oxidizing stirrer 7 according to the present embodiment. A sleeve 101 for supplying air 10 into the absorption tower 1 is provided outside the main shaft 102 of the oxidizing stirrer 7, and water 12 can be injected into the sleeve 101. During the operation of the oxidizing agitator 7, the air 10 is supplied into the absorption tower 1 through the sleeve 101 to convert the calcium sulfite in the absorbent slurry into gypsum. On the other hand, the water 12 is stopped by an opening / closing valve of a water pipe (not shown) and is not supplied into the sleeve 101.

When the operation of the oxidation agitator 7 is stopped, such as when the DSS or WSS operation is stopped, the air 10
Nor is water 12 supplied. Therefore, when the operation of the oxidation agitator 7 is stopped, the absorbing liquid slurry in the absorption tower 1 flows from the air ejection port of the sleeve 101 to the sleeve 10
As a result, the solid matter in the absorbent slurry adheres and deposits in the sleeve 101. The solid matter adhered and accumulated in the sleeve 101, when the oxidation agitator 7 is restarted,
The jet of water 12 injected into the sleeve 101 is agitated in the sleeve 101, and together with the water 12, the sleeve 101
To the outside (inside the absorption tower). As shown in FIG. 3, the oxidation stirrer 7 is started up first as shown in FIG.
When the start command is issued, the water 12 is injected into the sleeve 101, the solid matter adhering to the inside of the sleeve 101 is agitated by a jet flow, and is discharged to the outside of the sleeve 101. Next, the air 10 is supplied from the sleeve 101 into the absorption tower 1, and finally, the oxidation agitator 7 is activated and the activation is completed. Even when the operation of the oxidation agitator 7 is stopped, if the water 12 is once injected into the sleeve 101 immediately after the operation is stopped, the solid matter can be easily discharged by the injection of the water 12 immediately before the start. Also,
The water 12 may be injected through the air supply pipe.

[0010]

EFFECTS OF THE INVENTION According to the present invention, the solid matter in the absorbing liquid slurry that flows back in the sleeve while the oxidizing agitator is stopped can be discharged to the outside of the sleeve immediately before restarting the oxidizing agitator. In addition, there is an effect that the air to be supplied is not hindered and the solid matter does not come into contact with the main shaft of the stirring machine for oxidation, and the main shaft is not worn. In addition, once water is injected into the sleeve immediately after the operation of the agitation stirrer is stopped, the solid matter can be easily discharged by the water injection immediately before starting.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a wet flue gas desulfurization apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an oxidation stirrer that performs a method of starting the oxidation stirrer of FIG. 1.

FIG. 3 is an explanatory diagram of a starting sequence of the oxidation stirrer of FIG. 1.

FIG. 4 is a schematic configuration diagram of a conventional wet flue gas desulfurization apparatus.

FIG. 5 is a configuration diagram showing a conventional oxidation stirrer.

FIG. 6 is a configuration diagram showing a conventional oxidation stirrer.

[Explanation of Codes] 1 ... Absorption tower, 2 ... Mist eliminator, 3 ... Boiler exhaust gas, 4 ... Clean gas, 5 ... Absorption tower circulation pump, 6 ... Absorption tower stirrer, 7 ... Oxidation stirrer, 8 ... Gypsum separation Machine, 9 ... Limestone slurry, 10 ... Air, 11 ... Gypsum, 12 ... Water, 101
… Sleeve, 102… Spindle, 103… Propeller

Claims (4)

[Claims] 1. An absorption liquid slurry is produced by gas-liquid contacting an exhaust gas introduced into an absorption tower with an absorption liquid slurry, and then supplying air to an oxidizing air portion of an absorption liquid slurry storage portion provided at a lower portion of the absorption tower. In the wet flue gas desulfurization method that oxidizes the water, inject water into the oxidizing air supply section of the storage section immediately before or after starting the stirrer for stirring the oxidizing air in the storage section of the absorbent slurry. Wet flue gas desulfurization method characterized by. 2. An exhaust gas introducing part and an absorbing liquid slurry spraying part are provided in an upper part of the absorbing tower, and an absorbing liquid slurry circulating supply part and an oxidizing air supply to the absorbing liquid slurry spraying part are provided in an absorbing liquid slurry storage part in the lower part of the absorbing tower. In the wet flue gas desulfurization apparatus having a section, an oxidizing air agitator is provided in the absorbent slurry storage section at the lower part of the absorption tower, and a sleeve constituting the air supply section is provided in the vicinity of the oxidizing air agitator. A wet flue gas desulfurization device, wherein the sleeve is provided with a water injection portion for cleaning the inner wall of the sleeve. 3. An exhaust gas introducing part and an absorbing liquid slurry spraying part are provided in an upper part of the absorbing tower, and an absorbing liquid slurry circulation path to the absorbing liquid slurry spraying part and an oxidizing air supplying part are provided in an absorbing liquid slurry storage part in the lower part of the absorbing tower. In the wet flue gas desulfurization apparatus provided with, an oxidizing air agitator is provided in the absorbent slurry storage section in the lower part of the absorption tower, a sleeve constituting the air supply section is provided in the vicinity of the oxidizing air agitator, and the sleeve is further provided. Is provided with a water injection part having a water supply on-off valve, and the water injection part is provided with a control device for opening the water supply on-off valve immediately before starting or immediately after stopping the oxidation air agitator. Wet flue gas desulfurization equipment. 4. The wet flue gas desulfurization apparatus according to claim 2, wherein the sleeve forming the air supply portion is provided around the main shaft of the oxidizing air agitator.