JP3382837B2 - Air blower for flue gas desulfurization unit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air blowing device of a flue gas desulfurization device for wet desulfurization of SO ₂ in exhaust gas from a boiler or the like.

[0002]

2. Description of the Related Art When a fuel containing sulfur is burned, except for those fixed in ash, it is released into the atmosphere as sulfurous acid gas (SO ₂ ), and not only on humans and animals, but also on the ground as acid rain. As a result, it has a great adverse effect on the environment. For this reason, flue gas desulfurization devices are attached to large-scale combustion facilities and plants, and most of them are wet flue gas desulfurization devices. In such a wet desulfurization method, an aqueous solution and the exhaust gas containing an alkali lime and forces the gas-liquid contact, thereby absorbing and removing SO _2, by oxidizing sulfite produced in the absorbing solution by SO ₂ absorbed from the exhaust gas stably In order to obtain a proper sulfate, a method of blowing air into the absorbing solution to oxidize it is usually adopted.

Conventionally, various techniques have been developed as a means for blowing air into the absorbent. FIG. 5 shows a wet flue gas desulfurization apparatus (hereinafter referred to as a first conventional technique) having such an air blowing means. In FIG. 5, 1 is an absorption tower for performing wet desulfurization, and an alkali such as lime is provided under the absorption tower 1. A liquid reservoir 3 for storing an absorbent liquid b containing an absorbent d is arranged, and the absorbent liquid b in the liquid reservoir 3 is lifted up via a circulation pump 4 and a spray pipe 2 arranged in the lower part of the absorption tower 1. It is configured to be liquid sprayed.

In such an apparatus structure, the combustion exhaust gas a introduced into the absorption tower 1 from the upper part of the absorption tower 1 is brought into gas-liquid contact with the alkaline aqueous solution sprayed and sprayed through the spray pipe 2 to form a gas in the exhaust gas. After absorbing and removing SO ₂ , the cleaning exhaust gas c is discharged from the exhaust flue 13 to the outside. On the other hand, the absorbing liquid in which sulfite is generated by SO ₂ absorbed from the exhaust gas is returned to the liquid reservoir 3, and the sulfite is oxidized by the air e blown by the air blowing means described later to form the sulfate. After that, SO ₂ absorbed via the circulation pump 4 and the pipe 15 is discharged as a drainage f in a stoichiometrically equivalent amount of sulfate. Further, an alkali absorbent d such as lime is supplied into the liquid reservoir 3 through a pipe 14 into the liquid reservoir 3.

Now, the air blowing means is a liquid reservoir 3
A plurality of nozzle headers 120, each having a plurality of air supply nozzles 109 attached to almost the entire bottom surface, are extended obliquely downward from the side wall of the liquid reservoir 3, and air e from the blower 111 is passed through the pipe 112 and the nozzle header 120. The air supply nozzle injection hole 110 is injected into the absorbing liquid b to oxidize sulfite.

Further, as another structure of the wet flue gas desulfurization apparatus having air blowing means, as shown in FIG. 6, a tip end injection port 210 of a pipe 212 is arranged in front of an agitator 206 installed on the side wall of the liquid reservoir 3. , Blower 21 via pipe 212
A method of injecting air e from No. 1 into the absorbing liquid b from the injection port 210 and accelerating the dispersion of the air e by the jet flow from the agitator 206 and oxidizing it is also in practical use. (Hereinafter referred to as second conventional technology)

Further, as shown in FIG. 7, Japanese Utility Model Laid-Open No. 4-137731 has a plurality of jet nozzles 151 for blowing a jet at a predetermined angle with respect to the radial direction of the liquid storage tank 150. The jet nozzle 1 is arranged on the peripheral wall at a height position such that the jetting direction thereof is the peripheral direction of the peripheral wall.
An absorption liquid pipe 153, which is connected to the liquid storage tank 150 and has a jet pump 152 in the middle thereof, is provided at the base of 51, and the absorption liquid pipe 15 between the jet pump 152 and the jet nozzle 151 is provided.
3 is connected to the air pipe 154. (The third below
Prior art)

Further, as shown in FIG.
Circulation liquid pipe 16 for penetrating 1 into the liquid storage tank 160 from the peripheral wall of the liquid storage tank 160 and sucking and circulating the absorption liquid of the liquid storage tank 160 to the discharge pipe 161 through the liquid pump 162.
3 is connected to the circulating liquid pipe 163, an air blowing pipe 164 is inserted in the middle of the circulating liquid pipe 163, and an outlet portion 164a thereof is connected to the liquid pipe 16
3 Bent at the center position, opened in the flow direction of the liquid, blow air fed from the blower 165 into the absorbing liquid pipe 163 from the air blowing pipe 164, and discharge the air together with the absorbing liquid from the discharge pipe 161. . (Hereinafter referred to as fourth conventional technology.)

[0009]

Although the above-mentioned air blowing means according to the prior art are all excellent oxidation methods, they have the following problems. For example, in the first conventional technique shown in FIG. 5, since a large number of air supply nozzles 109 are laid over substantially the entire floor upper portion of the bottom of the liquid reservoir 3, there is an inconvenience that becomes an obstacle to inspection work in the liquid reservoir 3. There is. In the second conventional technique shown in FIG. 6, the stirring blade 20 is caused by an ascending flow due to an air lift action accompanying the ejection of the air e from the ejection port 210.
In No. 7, the stirring efficiency is lowered due to the narrow area circulation that sucks in the liquid that has just been discharged again, and the reaching distance of the discharge flow of the liquid is shortened and the stirring performance is deteriorated. Therefore, the stirring power is strengthened to improve the stirring performance. It is necessary to maintain it.

The third and fourth prior arts shown in FIGS. 7 and 8 supply air from the middle of the absorption liquid pipes 153 and 163 connected to the jet nozzle 151 or the discharge pipe 161. In the process of air bubbles flowing with the liquid in the absorbing liquid pipe, some of the air bubbles coalesce and become coarse bubbles,
The jet nozzle 151 or the discharge pipe 1 is used for discharging in this state because the air and the absorbing liquid are separated into phases.
Even if bubbles are discharged from 61, air bubbles cannot be evenly dispersed, smooth oxidation becomes difficult, and erosion problems due to cavitation on the inner surface of the absorption tube easily occur.

The present invention has been made to solve such a problem, and is capable of significantly reducing the number of air supply nozzles and power, and also capable of significantly improving the stirring and dispersing capacity of the absorbing liquid, and a flue gas desulfurization apparatus. An object of the present invention is to provide an air blowing device.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a wet flue gas desulfurization apparatus that absorbs SO2 in combustion exhaust gas to perform wet desulfurization, and discharge port of a discharge pipe that discharges the absorption liquid during storage of the absorption liquid. The gist of the present invention is to provide an air supply nozzle for injecting air into the discharge flow region near the discharge port of the discharge pipe (immediately before or immediately before the discharge port is opened).

According to the present invention, since the absorbing liquid discharge jet flow from the discharge port at the tip of the absorbing liquid discharge pipe has a larger flow rate along with the wake and moves in the discharge direction, the air jetted from the air supply nozzle The air can be dispersed over a wide area as bubbles by overcoming the upward flow caused by the air lift.
Therefore, the number of air supply nozzles can be greatly reduced, and
Since the suction part and the discharge part of the absorption liquid by the pump can be installed separately from each other, the narrow castle circulation does not occur, and the discharge jet of the absorption liquid moves in the discharge direction with the wake and a larger flow rate. The efficiency of air bubble dispersion is high and no extra power is required.

Further, according to the present invention, unlike the third and fourth conventional techniques, air is not supplied into the liquid pipe on the upstream side of the discharge pipe, but the vicinity of the discharge port of the discharge pipe (the discharge port). (Before or just before opening) Air is injected into the discharge flow area, so only liquid is supplied to the discharge port, resulting in coalescence of air bubbles in the liquid pipe and separation of air and absorbing liquid, Further, problems such as poor dispersion of air bubbles after ejection and poor performance in the liquid pipe due to these are eliminated. Moreover, since the jet air collides at the discharge flow velocity of the strongest pressure immediately after or immediately before the opening of the discharge port, the jet air is atomized during the discharge and is smoothly dispersed, so that the sulfite can be smoothly oxidized in a wide area. Is possible.

In the present invention, it is also effective to dispose the tip end injection port of the air supply nozzle in the flow region of the discharge jet from the discharge pipe, and the air injected from the air supply nozzle is dispersed as fine bubbles. it can. Further, in the present invention, the upper surface of the discharge port at the tip of the discharge pipe is projected so as to be longer than the lower surface, and the air supply nozzle is attached by penetrating the upper surface projecting portion, thereby ejecting from the air supply nozzle. It is possible to prevent blow-through of air. Also, by tilting the discharge pipe downward in the liquid reservoir,
It is possible to prevent accumulation of solid matter and backflow in the discharge pipe when the absorption liquid circulation by the pump is stopped. In this case, the discharge pipe may be tilted to be vertical.

Further, by inserting the air supply nozzle into the discharge pipe at a position in front of the discharge port at the tip of the discharge pipe, it is possible to disperse air bubbles into finer bubbles. By minimizing the residence time in the above, it is possible to minimize the wear of the discharge pipe due to the gas-liquid multiphase flow while eliminating the disadvantages of the third and fourth conventional techniques.

Further, in the present invention, the discharge pipe is introduced from the side wall of the liquid reservoir, and the discharge pipe is directed tangentially to the radial direction so that the discharge flow from the discharge pipe is along the side wall of the liquid reservoir in the liquid reservoir. By arranging so that a swirl flow is generated in the liquid reservoir, the swirl flow can further prolong the gas contact time of the air flow with the absorbing liquid.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be exemplarily described in detail below with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the constituent parts described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Only.

(Embodiment 1) FIG. 1 and FIG. 2 show the configuration of the present invention.
This will be specifically described with reference to the embodiment. In FIG. 1, the parts designated by the same reference numerals as those in FIG. 5 have the same configurations as those in FIG. In FIG. 1, reference numeral 1 is an absorption tower for performing wet desulfurization, and a liquid reservoir 3 for storing an absorption liquid b containing an alkaline absorbent d such as lime is disposed below the absorption tower 1 and the liquid reservoir 3 is provided. The absorption liquid b therein is configured to be sprayed as a pumping liquid via the circulation pump 4 and the spray pipe 2 arranged in the lower part of the absorption tower 1.

In such an apparatus structure, the combustion exhaust gas a introduced from the upper part of the absorption tower 1 into the absorption tower 1 comes into gas-liquid contact with the alkaline aqueous solution sprayed and sprayed via the spray pipe 2, and the SO in the exhaust gas is discharged. _{After 2} is absorbed and removed, the cleaning exhaust gas c is discharged from the exhaust flue 13 to the outside. On the other hand, the absorption liquid b in which sulfite is generated by SO ₂ absorbed from the exhaust gas is returned into the liquid reservoir 3, and the sulfite is oxidized by the air e blown by the air blowing means described later to sulphate. After that, the drainage liquid f is discharged through the circulation pump 4 and the pipe 15. Further, an absorbent d such as lime is supplied into the liquid reservoir 3 through the pipe 14 into the liquid reservoir 3. Such a configuration is similar to that of the conventional technique shown in FIG.

The air blowing means of this embodiment is provided with a pipe 5 which opens near the bottom of the peripheral wall of the liquid reservoir 3 of the absorbing liquid b storage portion.
Is connected to the pump 6, and the pump 6 is connected to a discharge pipe 7 for returning the absorbed liquid b in the liquid reservoir 3 sucked by the pump 6 back into the liquid reservoir 3. The discharge pipe 7 is slanted downward in the liquid reservoir 3 from the peripheral wall of the liquid reservoir 3 so as to extend and enter, and the discharge pipe 7 penetrates the side wall of the liquid reservoir 3 as shown in FIG. 1 (B). Before this is done, it is branched into two and the discharge pipe is extended in the tangential direction with respect to the radial direction so that the discharge flow from the discharge pipe is along the side wall of the liquid reservoir 3 in the liquid reservoir 3. Also, the discharge pipe 7 that opens in the liquid reservoir 3
An air supply nozzle 9 for injecting air e from a blower 11 via a pipe 12 is arranged in front of the absorbent discharge port 8 at the tip.

Next, the positional relationship between the discharge pipe 7 and the air supply nozzle 9 will be described with reference to FIGS. The first embodiment is shown in FIG. In FIG. 2, the air supply nozzle 9
Is installed vertically downward in front of the absorbent discharge port 8 at the tip of the discharge pipe 7, and its tip injection port 10 is arranged in the flow area of the discharge jet immediately after discharge from the discharge port.
The position of the tip end injection port 10 is located between the lower end extension line of the discharge port 8 of the discharge pipe 7 and the center line.

In the experiment conducted by using the air blowing means having the arrangement shown in FIG. 2 in the apparatus having the form shown in FIG. 1, the absorption tower 1 shown in FIG. 1 is supplied with the combustion exhaust gas a containing about 1,000 ppm of SO _2. 10,000 m ³ N per hour is introduced, 200 m ³ per hour of absorption liquid b is drawn up from the liquid reservoir 3 by the circulation pump 4 and sprayed into the absorption tower 1 through the spray pipe 2 to wash the exhaust gas a. It was desulfurized and discharged as exhaust gas c from the exhaust flue 13. Desulfurized SO ₂ is stored in the liquid reservoir 3.
While the amount of limestone that is stoichiometrically approximately equal to that of the above is supplied from the pipe 14 as the absorbent d, the amount of gypsum that is stoichiometrically equivalent to that of the desulfurized SO ₂ is withdrawn as the drainage liquid f from the pipe 15. The absorbing liquid b is stored in the liquid reservoir 3 until the liquid surface g becomes about 2 m,
The side wall of the liquid reservoir 3 1.5 m below the liquid level g is connected to the pump 6 by the pipe 5, and the discharge pipe 7 of the pump 6 is 1.3 from the liquid level g.
lm inside the liquid reservoir 3 by penetrating the side wall of the liquid reservoir 3 below
The absorbent discharge port 8 was closed by inserting.

As shown in FIG. 1B, the discharge pipe 7 is branched into two before the side wall of the liquid reservoir 3 is penetrated, and the discharge flow from the discharge pipe 7 is stored in the liquid reservoir 3. 3 The discharge pipe 7 is provided so as to be deflected in the tangential direction with respect to the radial direction along the side wall. And from the pump 2 1 per hour
Absorption liquid b of 00 m ³ was sucked and jetted into the absorption liquid b from each absorption liquid discharge port 8 of the discharge pipe 7 branched into two. On the other hand, the pipe 12 was also branched into two pipes corresponding to the discharge pipe 7, and 100 m ³ N of air e per hour was jetted into the absorbing liquid b by the blower 11 from the air supply nozzle 9 at the tip of the pipe 12. The specifications of each part of the equipment used in this experiment are as follows.

1) The absorption tower 1 has a cross-sectional area of 1 m ² and the height above the spray pipe 2 is 12 m. 2) The cross-sectional size of the liquid reservoir 3 is 2 m × 3.2 m, and the height from the bottom is 3.5 m. 3) The spray pipe 2 had a nominal diameter of 100 A, and four nozzles having a nominal diameter of 40 A and a length of 100 mm were attached upward. 4) The nominal diameter of the pipe 5 is 125A. 5) The nominal diameter of the discharge pipe 7 is 100 A, the nominal diameter is 65 A after branching, and 3.2 m of the liquid reservoir 3 (see 2 above)).
Insert 1m from the side wall in the direction and 0.7 from the floor
After being inserted at the position of m, the absorbing solution discharge port 8 was opened by inclining downward by about 20 ° toward the inside. The distance between the two discharge pipes 7 was set to 1 m. 6) The nominal diameter of the air supply pipe 12 is 25 A, and the nominal diameter is 20 A after branching into two pipes.
After being lifted up to the upper 3 m, it was inserted into the liquid reservoir 3. 7) The nominal diameter of the two air supply nozzles 2 is 20A. 8) The tip injection port 10 of the air supply nozzle 9 was positioned 2 cm above the extension line of the lower end of the absorbent discharge port 8. In the experiment conducted under the above conditions, the liquid level g increased by about 10 cm when the supply of the air e was started, and the complete oxidation of sulfite was achieved.

(Embodiment 2) The overall construction of this embodiment is shown in FIG.
The air blowing means shown in FIG. In the configuration of FIG. 3, the parts denoted by the same reference numerals as those in FIGS. 1 and 2 perform the same functions.
In this embodiment, as shown in FIG. 3, the tip of the absorbing liquid discharge pipe 7 extending obliquely downward is cut substantially horizontally, in other words, the discharge port 8 at the tip of the discharge pipe 7 and the top end 7a of the tip end 7a.
The protrusion 7c is extended to be longer than b.
The air supply nozzle 9 is attached by penetrating it downwardly from above. The tip injection port 10 of the air supply nozzle 9 is positioned in the extended line flow region of the discharge pipe 7 that is cut horizontally. As a result, the air supply nozzle 9
The tip injection port 10 is located in the flow area of the discharge jet immediately after the discharge from the discharge port 8.

As a result of a test conducted under the same experimental conditions as in Example 1 using the air blowing means of this Example, complete oxidation of sulfite was achieved and the liquid level g was reduced by starting the supply of air e. A result of 12 cm increase was obtained.

(Embodiment 3) The overall construction of this embodiment is shown in FIG.
The air blowing means shown in FIG. 4 was used by using the equipment almost similar to that of FIG. In the embodiment of FIG. 4, the parts denoted by the same reference numerals as those in FIGS. 1 and 2 perform the same functions.
In the present embodiment, as shown in FIG. 4, the absorbent liquid discharge pipe 7 extending obliquely downward is cut in a direction orthogonal to the axis, and the air supply nozzle 9 is positioned immediately above the discharge pipe 7 front end opening. Is vertically inserted into the discharge pipe 7 from above, and the air e is injected from the injection port 10 to a position immediately before the opening of the discharge pipe 7.

As a result of a test using the experimental apparatus according to this example under the same experimental conditions as in Example 1, complete oxidation of sulfite was achieved and the liquid level g was about 15 cm when the supply of air e was started. A rising result was obtained.

Therefore, according to each of the above-described embodiments, since the air supply nozzle is provided immediately after or immediately before the outlet of the absorbent outlet, the absorption liquid jetted from the outlet is ejected from the rear of the air supply nozzle. A vortex is formed according to the flow rate, and the air jetted from the air supply nozzle is sheared into fine bubbles by the vortex and the air is made into fine bubbles to improve the gas-liquid contact area and improve the oxidation performance.

Further, as shown in FIG. 4, when the air supply nozzle penetrates into the discharge pipe immediately before the outlet opening,
The cross-sectional area of the discharge pipe is narrowed by the cross-sectional integration of the penetrating portion of the air supply nozzle, and the flow velocity of the absorbing liquid flowing in the discharge pipe rises. When air is blown into the liquid supply nozzle from the air supply nozzle, the air becomes fine bubbles due to this vortex, and is discharged and dispersed as a gas-liquid mixed phase jet into the liquid reservoir 3 from the tip of the absorbing liquid discharge pipe.

[0032]

Therefore, according to the present invention, an air supply nozzle for injecting air is provided in the discharge flow region near the discharge port of the absorbent discharge pipe, and the tip injection port is further discharged immediately after the discharge from the discharge port. By arranging the sulphite in the jet flow area, the sulphite generated in the absorption liquid by SO ₂ taken from the exhaust gas by the exhaust gas cleaning is injected from the air supply nozzle, and the air is injected from the absorption liquid discharge port into fine bubbles. In addition to being able to shear and completely oxidize, the jet of absorbing liquid atomizes the air and disperses it in the liquid reservoir, which significantly reduces the number of air supply nozzles that hinder the inspection and cleaning of the liquid reservoir.

Further, since the injection position of air can be set at a free position inside the liquid reservoir, no bubbles are entrained in the pump, so that the pump does not need extra power and is sufficiently located at a desired place. It is possible to supply a sufficient amount of air, and the amount of jet liquid is increased due to the wake of the jet for jetting the absorbing liquid, so that the effect of stirring the absorbing liquid can be obtained.

Further, in the invention according to claim 1, by mounting the air supply nozzle by penetrating the upper surface of the discharge port at the tip of the discharge pipe from the upper surface protruding portion which is protruded so as to be longer than the lower surface, It is possible to prevent blowout of jet air from the air supply nozzle.

Further, by tilting the discharge pipe downward in the liquid reservoir as described in claim 2 , solid deposits in the discharge pipe are reduced when the operation is stopped, and solid substances are discharged at the time of restart. And the discharge flow from the discharge pipe in the liquid reservoir is arranged so that a swirl flow is generated in the liquid reservoir, thereby increasing the gas contact time with the absorbing liquid of the air flow. You can

Further, as described in claim 3 , air bubbles can be dispersed into finer bubbles by penetrating the air supply nozzle into the discharge pipe at a position before the tip discharge port of the discharge pipe.

[Brief description of drawings]

FIG. 1A is a schematic front view showing an example of the overall configuration of a gas-liquid contact device according to the present invention, and FIG. 1B is a top view showing an arrangement example of a discharge pipe in a liquid reservoir.

FIG. 2 is a partially enlarged view of an absorbent discharge section of an air blowing unit used in the apparatus of FIG. 1 according to the first embodiment of the present invention.

FIG. 3 is a partially enlarged view of an absorbent discharge section of an air blowing unit used in the apparatus of FIG. 1 according to the second embodiment of the present invention.

FIG. 4 is a partially enlarged view of an absorbent discharge section of an air blowing unit used in the apparatus of FIG. 1 according to the third embodiment of the present invention.

FIG. 5 is a schematic front view showing an example of the overall configuration of a gas-liquid contactor according to a first conventional technique.

FIG. 6 is a schematic front view showing an example of the overall configuration of a gas-liquid contactor according to a second conventional technique.

FIG. 7 is a top view showing an arrangement example of air blowing means in a liquid reservoir according to a third conventional technique.

FIG. 8 is a schematic front view showing a configuration example of a main part of an air blowing means portion of a gas-liquid contact device according to a fourth conventional technique.

[Explanation of symbols]

1 absorption tower 2 spray pipe 3 liquid reservoir 4 circulation pumps 5 piping 6 pumps 7 Discharge pipe 8 outlets 9 Air supply nozzle 10 injection ports 11 Blower 12 piping 13 exhaust flue 14, 15 piping

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-11-128671 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 53/34 B01F 3/04

Claims (3)

(57) [Claims] 1. Wet desorption by absorbing SO _{2 in} combustion exhaust gas.
In a wet flue gas desulfurization device for sulfurization, the discharge pipe of the discharge pipe that discharges the absorbing liquid during the absorption liquid storage
The outlet is opened and the discharge pipe near the discharge port is discharged.
With an air supply nozzle that injects air into the outflow area,
In particular, the upper surface of the discharge port tip of the discharge pipe is projected so as to be longer than the lower surface, and the air supply nozzle is attached through the projecting portion. Including device. 2. Wet desorption by absorbing SO _{2 in} combustion exhaust gas
In a wet flue gas desulfurization device for sulfurization, the discharge pipe of the discharge pipe that discharges the absorbing liquid during the absorption liquid storage
The outlet is opened and the discharge pipe near the discharge port is discharged.
With an air supply nozzle that injects air into the outflow area,
In addition, the discharge pipe is introduced from the side wall of the liquid reservoir, and the discharge pipe is horizontally deflected in the tangential direction with respect to the radial direction so that the discharge flow from the discharge pipe is along the side wall of the liquid reservoir in the liquid reservoir. An air blowing device for a flue gas desulfurization device, characterized in that it is slanted and extended downward in the liquid reservoir. 3. Wet desorption by absorbing SO _{2 in} combustion exhaust gas
In a wet flue gas desulfurization device for sulfurization, the discharge pipe of the discharge pipe that discharges the absorbing liquid during the absorption liquid storage
The outlet is opened and the discharge pipe near the discharge port is discharged.
With an air supply nozzle that injects air into the outflow area,
An air blowing device for a flue gas desulfurization device, characterized in that the air supply nozzle is inserted into the discharge pipe at a position in front of the discharge port at the tip of the discharge pipe.