JPH0713420U - Absorption tower - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to provide an absorption tower that can secure water for cleaning a demister. In the absorption tower for absorbing and removing the sulfur oxides in the gas, the absorption liquid in the lower liquid storage tank 7 is sprayed and dropped from the upper part and circulated to come into contact with the gas to be treated, In the above, a separation unit 20 is installed to stand up the absorption liquid from the lower part and to settle the solid content in the liquid.
A baffle 24 is provided in the lower part of the column to rectify the absorbing liquid flowing into the separation unit 20 and suppress the turbulence of the liquid in the separation unit 20.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an absorption tower of a flue gas desulfurization device for desulfurizing a gas to be treated such as exhaust gas containing sulfur oxides from a combustion device with an absorbing liquid.

[0002]

[Prior art]

 BACKGROUND ART A wet flue gas desulfurization device is known as a device for removing sulfur oxides contained in a gas to be treated such as exhaust gas from a combustion device.

As shown in FIG. 3, this flue gas desulfurization apparatus introduces a gas to be treated into an absorption tower 40 and contacts it with a slurry-like absorption liquid containing a calcium-based absorbent such as calcium carbonate. Then, the sulfur oxides in the gas are absorbed and removed to desulfurize the gas to be treated.

The absorption liquid that has absorbed the sulfur oxides is oxidized in the lower liquid storage tank 41 in the absorption tower 40, and a part of this is appropriately extracted and transferred to a concentration tank 42 such as thickener to be concentrated. Then, the concentrated liquid is sent to the dehydrator 43, where it is subjected to solid-liquid separation and gypsum is recovered. The supernatant of the concentration tank 42 is used for cleaning the demister 44 in the absorption tower 40 and the like. In addition, a part of it is applied to wastewater outside the system to reduce the load of SS treatment in the wastewater treatment equipment.

[0005]

[Problems to be solved by the device]

 By the way, in the above-mentioned flue gas desulfurization equipment, since the absorbing liquid is concentrated in the concentrating tank, the concentrating tank is large and the cost is relatively high, so a large installation space is required and there is a cost for equipment and operating costs. Get higher For this reason, it is proposed to eliminate the concentration tank, but if the concentration tank disappears, the supernatant liquid from the concentration tank cannot be obtained, so water for cleaning the demister must be supplied from other systems. Disappear.

Therefore, the present invention has been made in view of such circumstances, and an object thereof is to provide an absorption tower capable of securing water for cleaning a demister and the like.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention absorbs and removes sulfur oxides in the gas by contacting the gas to be treated while spraying and dropping the absorbent in the lower liquid storage tank from the top and circulating it. In the absorption tower, a separation section is provided upright in the liquid storage tank for allowing the absorption solution to flow in from below and settling the solid content in the solution, and a baffle is provided below this separation section.

[0008]

[Action]

 Since the separation part is installed upright in the liquid storage tank, part of the absorbing liquid in the liquid storage tank flows into the separation part. At this time, since the baffle is provided in the lower part of the separation part, the absorbing liquid flowing into the separation part is rectified by the baffle, so that the turbulence of the liquid in the separation part is suppressed and the solid content in the separation part is suppressed. The sedimentation is done smoothly. As a result, supernatant water that can be used as water for washing the demister in the separation section is obtained.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing an example in which the absorption tower according to the present invention is applied to a wet flue gas desulfurization apparatus. In FIG. 1, reference numeral 1 denotes desulfurization of a gas to be treated such as exhaust gas from a combustion device such as a boiler. An absorption tower is shown, and this absorption tower 1 is formed, for example, in a vertical cylindrical shape, and a gas introduction pipe 2 for the gas to be treated is connected to the lower part thereof, and a gas discharge of the gas after desulfurization treatment is provided at the upper part. The tube 3 is connected.

To the absorption tower 1, a calcium-based absorbent (limestone, slaked lime or quick lime) that absorbs the sulfur content in the gas to be treated is slurried by the slurry manufacturing device 4 and supplied as an absorption liquid. An absorbent pipe 6 having a slurry pump 5 is connected, and a liquid storage tank 7 for storing an absorbing liquid is provided below the inside thereof. A stirrer 8 is provided in the lower part of the liquid storage tank 7, and in order to transfer the absorbing liquid to the spray nozzle 9 in the upper part of the absorption tower 1 except for the mounting part of the stirrer 8 (for example, on the opposite side). A circulation pipe 11 having a circulation pump 10 of is connected. The absorption liquid transferred to the spray nozzle 9 is sprayed into the tower 1 and comes into countercurrent contact with the gas to be treated, so that the sulfur content in the gas is absorbed and the desulfurization treatment of the gas to be treated is performed. Therefore, the desulfurized gas flows into the gas discharge pipe 3 after the mist is removed via the demister 12. On the other hand, the absorption liquid after desulfurization treatment is subjected to aeration treatment (oxidation treatment) by the oxidizing air from the air pipe 13.

An absorption liquid extraction pipe 14 for extracting a part of the absorption liquid is connected to the circulation pipe 11, and the absorption liquid extraction pipe 14 is connected to a dehydrator 15 for separating and recovering solid content (gypsum) in the liquid. It is connected. A filtrate tank 17 is connected to the liquid recovery pipe 16 of the dehydrator 15, and a filtrate tank 17 is provided with a pump 18 for returning a part of the liquid in the tank 17 to the absorption tower 1 and sending the rest to a drainage treatment system. The drain pipe 19 has is connected.

In the liquid storage tank 7 of the absorption tower 1, as shown in FIGS. 1 and 2, a separation unit 20 for standing up the solid content in the liquid is set up. Specifically, a plate-shaped partition wall 21 is erected in the height direction in the liquid storage tank 7 at a predetermined distance from the bottom, and the tank 7 is provided between the stirrer 8 and the circulation pipe connecting portion. The partition part 20 is divided into two parts, the upper part on the circulation pipe side is covered with a roof 22, and the partition part 21, the roof 22, and the inner wall of the absorption tower 1 define a separation part 20. The portion where the roof 22 is not provided substantially becomes the liquid storage tank 7, and the liquid storage tank 7 and the separation section 20 communicate with each other at the lower part. A gas vent pipe 23 for venting the gas in the separation portion 20 is connected to the roof 22.

A baffle 24 that rectifies the absorbing liquid that flows into the separation unit 20 is provided below the separation unit 20. The baffle 24 is formed by arranging plates having a predetermined height in a grid pattern, and suppresses the turbulence of the liquid in the separation section 20 so that the solid content can be smoothly settled in the separation section 20. It has become. The baffle may be formed in any way as long as it can rectify the absorbing liquid flowing into the separation part and suppress the turbulence of the liquid in the separation part. Also, the volume of the separation part is less than half of the volume of the liquid storage tank depending on the volume of the absorption tower, and if the rising speed of the liquid in the separation part can secure 1.5 m / h, it is optional. Is decided.

A supernatant water pipe 26 having a water pump 25 for extracting the supernatant water is connected to the upper portion of the separation section 20. The supernatant water pipe 26 has a cleaning water pipe 28 having a solenoid valve 27 for supplying water for cleaning the demister 12, and a control valve 29 for supplying water for dissolving the absorbent to the slurry manufacturing apparatus 4. It is connected to the water supply pipe 30 and the supernatant water is used for cleaning the demister 12 and dissolving the absorbent.

Next, the operation of this embodiment will be described.

The absorption liquid containing the absorbent such as calcium carbonate in the liquid storage tank 7 of the absorption tower 1 is transferred by the circulation pump 10 to the spray nozzle 9 in the upper part of the tower 1 through the circulation pipe 11, and from the spray nozzle 9. It is sprayed into the tower 1. The atomized absorption liquid and the gas to be treated introduced into the tower 1 from the gas introduction pipe 2 come into countercurrent contact with each other, and the sulfur oxide in the gas is absorbed by the absorption liquid. The gas from which the sulfur oxides have been removed has the mist component removed via the demister 12, and then flows into the gas exhaust pipe 3 and is guided to the outside of the system.

The desulfurized absorption liquid flows down in the tower 1 and collects in the liquid storage tank 7, where it is oxidized by the air from the air blowing pipe 13, and the calcium compound in the liquid is converted into gypsum. .. This series of reaction formulas is SO ₂ + CaCO ₃ + 1 / 2O ₂ + 2H ₂ O → CaSO ₄ · 2H ₂ O + CO ₂ .

A part of the absorption liquid is guided to the dehydrator 15 through the circulation pipe 11 and the absorption liquid discharge pipe 14, and solid components such as gypsum in the liquid are separated and collected therein.

A part of the liquid in which the solid content is collected by the dehydrator 15 is sent to the wastewater treatment system, and the rest is returned to the absorption tower 1.

Part of the absorption liquid in the liquid storage tank 7 of the absorption tower 1 flows into the separation section 20. At this time, since the lattice-shaped baffle 24 is provided at the liquid inlet which is the lower part of the separation unit 20, the turbulence of the liquid in the separation unit 20 is suppressed. That is, when the baffle 24 is not provided in the lower part of the separation unit 20, the stirring flow by the stirrer 8 or the flow due to the withdrawal of the absorbing liquid affects the inside of the separation unit 20 to cause the turbulence of the liquid flow. It becomes difficult for the solid content to settle in the portion 20. Therefore, by providing the baffle 24, the absorbing liquid flowing into the separation unit 20 is rectified by the baffle 24, so that the turbulence of the liquid in the separation unit 20 is suppressed and the solid content in the separation unit 20 is suppressed. The sedimentation will be carried out smoothly. As a result, a liquid fraction containing a small amount of solids is accumulated in the separation section 20, and clear water having a degree of clarity equivalent to that of a conventional thickener such as a thickener can be obtained.

As a result, the liquid (supernatant water) in the upper part of the separation unit 20 can be used for cleaning the demister 12 and dissolving the absorbent, and this liquid is supplied by the water pump 25 to the supernatant water pipe 26 and the cleaning water pipe. It is used for cleaning the demister 12 via 28 and for dissolving the absorbent via the water supply pipe 30.

As described above, since water for cleaning the demister 12 and the like can be collected, by appropriately setting the volume of the separation section 20, the slurry concentration of the absorption liquid in the absorption tower 1 can be, for example, 10% as in the conventional case. % To more than 15%. This eliminates the need for a separate thickener such as a thickener. Therefore, it is possible to reduce equipment costs, operating costs, etc., and reduce the installation space.

Further, since the absorbing liquid is extracted from the lower portion of the liquid storage tank 7, it is possible to prevent scaling of the lower portion of the liquid storage tank 7, especially the lower portion of the separation section 20.

[0025]

[Effects of the Invention] In summary, according to the present invention, the excellent effect of being able to secure water for cleaning the demister in the absorption tower is demonstrated.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example in which the absorption tower of the present invention is applied to a wet flue gas desulfurization apparatus.

FIG. 2 is a schematic perspective view showing an example of a separation unit of the absorption tower of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional wet flue gas desulfurization apparatus.

[Explanation of symbols]

 7 Liquid storage tank 20 Separation part 24 Baffle

Claims (1)

[Scope of utility model registration request] 1. An absorption tower which absorbs and removes sulfur oxides in a gas by contacting with a gas to be treated while spraying and dropping the absorbent in the lower liquid tank from the upper part and circulating it An absorption tower characterized in that a separating part for allowing the absorbing liquid to flow from the lower part to settle out the solid content in the liquid is provided upright, and a baffle is provided at the lower part of the separating part.