JPH0910546A - Wet type flue gas desulfurization device - Google Patents

Abstract

PURPOSE: To prevent a circulation pump on the sidewall of a tank from causing its performance deterioration and damage due to the generation of air bubbles and also its consequent noise and vibration by fitting an inclined plate obliquely downward from the inner surface of the sidewall of the tank in such a manner that the outlet opening of the pump is covered. CONSTITUTION: An inclined plate 102 is fitted extending downward from the inner surface of the sidewall of a tank 101 in such a manner that the upper side and the front of each outlet opening part 105 of pumps 114, 124 on the sidewall of the tank 101 are covered. Under this design, a main circulation flow N5 generated by a means 7 to supply air by arm rotation descends along the inner surface of the sidewall of the tank 101 near the inner surface, but is remote from the outlet opening 105 of the pump by the inclined plate 102, branching off as minor flows N6. Consequently, a large amount of air bubbles is prevented from entering into the pump, and thus the performance of the pump is prevented from deteriorating and the short pass is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank oxidization type wet flue gas desulfurization system in which bubbles blown into an absorption tower tank are entrained in a pump and a so-called short path of circulating slurry is reduced.

[0002]

2. Description of the Related Art In recent years, as a wet flue gas desulfurization apparatus, air is sent into a tank of an absorption tower, where it is oxidized by bringing it into contact with a slurry solution (containing calcium compounds such as limestone) that has absorbed sulfurous acid gas. The mainstream is the one that does not need an oxidation tower (so-called tank oxidation method). In this case, how much air and slurry solution are contacted in the tank depends on the amount of consumed air and power consumption. This is a problem in saving energy, improving the processing speed, and downsizing the tank. As a means for sending air into the tank and bringing it into contact with the slurry solution (that is, air supply means), there has been one in which a ventilation pipe is fixedly installed in the tank to simply perform bubbling. To obtain contact, the applicant has developed and puts into practical use a so-called arm-rotating air supply means for supplying air to the back surface of a stirring rod that rotates in a tank, and a wet desulfurization apparatus to which the air supply means is applied.

FIG. 6 is a diagram showing an example of a wet limestone gypsum desulfurization device to which the arm rotation type air supply means 7 is applied. This device uses a so-called filling type (grid type) gas-liquid contact device, and the main constituent is an absorbent slurry (calcium-containing slurry, in this case limestone slurry).
A tank 1 to which is supplied, an absorption tower 2 extending upward on one side of the tank 1, and a smoke exhaust lead-out portion 3 formed on the other side of the tank 1 so as to rise upward. And a circulation pump 4 that sucks up the absorbent slurry in the tank 2 and sends it to the tower upper part 2a of the absorption tower 2, and an absorbent slurry sent from the circulation pump 4 provided in the tower upper part 2a of the absorption tower 2. A header pipe 5 having a plurality of nozzles 5a for discharging water and an absorber 2 disposed below the tower upper portion 2a in the absorption tower 2 to hold the absorbent slurry flowing out of the nozzles 5a and flowing down, thereby forming a large gas-liquid contact area. And a filler 6 for ensuring that the sulfurous acid gas in the flue gas is brought into gas-liquid contact with the absorbent slurry to be absorbed, and then the absorbent slurry is entirely oxidized to obtain gypsum as a by-product. .

That is, in this apparatus, the untreated flue gas A is introduced to the tower upper part 2a of the absorption tower 2 and brought into gas-liquid contact with the absorbent slurry injected from the nozzle 5a of the header pipe 5 by the circulation pump 4 to obtain the untreated exhaust gas. Sulfurous acid gas in the smoke A is absorbed and removed, and is discharged as treated smoke B from the smoke exhausting section 3.
The absorbent slurry flowing out from the nozzle 5a and absorbing the sulfurous acid gas and flowing down via the filler 6 is oxidized by the air supplied by the air supply means 7 in the tank 1 and further causes a neutralization reaction. Becomes gypsum.

The arm rotation type air supply means 7 is supported in the tank 1 by a hollow rotary shaft 8 and horizontally rotated by a motor (not shown), and an opening 10a extending from the hollow rotary shaft 8. Includes an air supply pipe 10 extending below the stirring rod 9 and a rotary joint 11 for connecting the proximal end side of the hollow rotary shaft 8 to an air source,
By rotating the hollow rotary shaft 8 while press-fitting the air C from the rotary joint 11, the air C is supplied from the air supply pipe 10 to the gas phase region generated on the rear side in the rotation direction of the stirring rod 9,
Due to the vortex force generated by the rotation of the stirring rod 9, the end edge of the gas phase region is torn off to generate a large number of substantially uniform fine bubbles, and the absorbent slurry solution absorbing sulfurous acid gas and the air are generated in the tank 1. To efficiently contact. Also,
The main reactions occurring during these processes are represented by the following reaction formulas (1) to (3).

[0006] (absorption _{tower) SO 2 + H 2 O →} H + + HSO 3 - (1) ( ^{_{Tank) H + + HSO 3 - +}} 1 / 2O 2 → 2H + + SO 4 2- (2) 2H + + SO 4 2- + CaCO ₃ + H ₂ O → CaSO ₄・ 2H ₂ O + CO ₂ (3)

Thus, in the tank 1, gypsum and a small amount of limestone, which is an absorbent, are suspended or dissolved, and these are sucked out by the extraction pump 12 and supplied to the solid-liquid separator 15 and filtered to reduce the water content. Extracted as gypsum E (usually, water content: about 10%). On the other hand, the filtrate from the solid-liquid separator 15 is sent to a filtrate tank 16, where limestone G is added and is supplied to the tank 1 again as an absorbent slurry by a slurry pump 17.

Incidentally, FIG. 6 shows a desulfurizer without a dust removing part. However, since the filling type gas-liquid contact device itself has almost no dust removing action, when high dust removing performance is required, the absorption tower A dust removing unit having a pipe formed with a plurality of nozzles for injecting water is provided on the upstream side of 2. Further, as a gas-liquid contact device conventionally used in this type of desulfurization device,
For example, there is a so-called liquid column type as shown in Japanese Utility Model Laid-Open No. 59-53828. This does not use a filler, but sprays absorbent slurry from a nozzle in a high liquid column manner to make gas-liquid contact.

The desulfurization apparatus shown in FIG. 6 is provided with a so-called co-current type absorption tower, but the Applicant has proposed that co-current flow is carried out on the flue gas introduction side and the discharge side of one tank. We have proposed a desulfurization device consisting of a hybrid type gas-liquid contactor, which is provided with a type absorption tower and a countercurrent type absorption tower, respectively. At the same time, the device can be downsized and the power consumption can be reduced.

[0010]

By the way, in the above-mentioned conventional desulfurization apparatus, a large flow containing bubbles as shown by an arrow N1 in FIG. 6 is generated in the tank 1 by the arm rotation type air supply means 7, The flow N2 branching from the outer peripheral portion of the flow N1 directly and smoothly flows into the circulation pump 4
It was sucked out from the outlet opening connected to the discharge pump 12. Therefore, a large amount of bubbles are contained in the flow N2 as they are, and flow into the circulation pump 4 and the extraction pump 12, resulting in performance deterioration and damage of each pump, and increase in noise and vibration. In addition, a large amount of flow N3 (that is, a short path) in which the slurry that has come into contact with the flue gas and that has fallen from the absorption tower 2 is directly sucked into the circulation pump 4 and the like without coming into contact with the air bubbles, is an obstacle to improving desulfurization performance. There was also a problem.

In the single tower desulfurization apparatus as shown in FIG. 6, the outlet opening of the pump is provided on the side opposite to the side where the absorption tower is provided, so that the outlet opening is kept away from the falling position of the slurry. You can avoid short passes,
In this case, there is a problem that the degree of freedom in design deteriorates. In any of the above-described hybrid type desulfurizers, whichever side has the outlet opening of the pump, the slurry coming into contact with the smoke exhaust falls on the upper side of the outlet opening.
Inevitably, a short path like this is unavoidable, which also hinders performance improvement.

In this type of tank oxidation type desulfurization apparatus, as a technique for preventing gas from being sucked into the pump, a partition wall is provided at the bottom of the tank as disclosed in Japanese Patent Publication No. 5-26525. A technique has been proposed in which a liquid reservoir is formed upright and a pump outlet is provided in the liquid reservoir. This is to prevent the suction of air bubbles by setting the cross-sectional area of the liquid storage portion so that the flow-down speed generated in the liquid storage portion according to the amount of withdrawal of the pump is lower than the rising speed of the bubbles, If the air supply means is, for example, simply bubbling (a so-called fixed air sparger or the like), it is considered to be effective in reducing air bubble suction. However, with this configuration, it is not possible to suppress the flow in which the slurry that has dropped near the upper portion of the liquid reservoir is directly sucked into the pump, that is, the short path. Further, like the above-mentioned arm rotation type air supply means,
When a large flow N1 that rises at the center of the tank and descends at the side wall of the tank is generated, it may be impossible in practice to adjust the downflow speed of the liquid reservoir by only its step area. However, the air bubble suction cannot be effectively reduced.

Therefore, according to the present invention, even when the air supply means (or the agitator) for generating the flow containing the bubbles descending along the side wall of the tank is adopted, the slurry is prevented from dropping near the upper part of the outlet opening of the pump. An object of the present invention is to provide a wet flue gas desulfurization apparatus in which mixing of bubbles into the pump and a short path are suppressed even in the case of a different absorption tower configuration (or a configuration in which a pump outlet opening is arranged).

[0014]

In order to achieve the above object, a wet flue gas desulfurization apparatus according to claim 1 comprises an absorption tower in which a calcium compound-containing slurry is supplied to a bottom tank,
A circulation pump for sending the slurry in the tank to the upper part of the absorption tower to make contact with the exhaust gas, an air supply means for supplying air for oxidation into the tank, and an extraction pump for extracting the slurry in the tank. In a tank oxidation type wet flue gas desulfurization apparatus comprising: a tank side wall of the tank, at least obliquely downward from the inner surface of the side wall of the tank so as to cover at least the upper side of the outlet opening for the circulation pump or the extraction pump. It is characterized in that an inclined plate extending in the direction of is provided.

Further, in the wet flue gas desulfurization apparatus according to claim 2, a perforated plate is erected on the bottom surface of the tank so as to partition the lower end of the inclined plate and the bottom surface of the tank. And

[0016]

According to the present invention, even if there is a flow descending along the inner surface of the side wall of the tank, this flow is guided by the inclined plate in the direction away from the outlet opening of the pump, and the flow is branched off directly and directly. Generation of a flow that smoothly flows into the outlet opening is prevented, and bubble separation is realized. Further, the slurry falling above the outlet opening of the pump also flows along the inclined plate toward the center of the tank, so that the slurry passes through at least the region where a large amount of bubbles are present, and the short path is reduced.

Further, when a perforated plate which divides the tip of the inclined plate and the bottom surface of the tank is erected, the flow flowing into the outlet opening is further promoted by the action of the perforated plate to separate bubbles. It

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The same elements as those of the conventional wet flue gas desulfurization apparatus shown in FIG. 6 are designated by the same reference numerals and the description thereof will be omitted. As shown in FIG. 1, the wet flue gas desulfurization apparatus of this embodiment is a gas-liquid contactor for bringing the absorbent slurry into gas-liquid contact with flue gas, and further in contact with air for oxidation.
A hybrid type gas-liquid contactor 1 as shown in FIG.
00. This gas-liquid contact device 100 is provided with a tank 101 to which an absorbent slurry (calcium-containing slurry, in this case, limestone slurry) is supplied, and is extended upward from one side portion (left side in the figure) of this tank 101 to provide an untreated exhaust gas. A flue gas introduction part 111 for introducing the smoke A is formed at the upper end of the flue gas, and the introduction side absorption tower 110 in which the flue gas flows downward and the other side part of the tank 101 (right side in the figure) extends upward. A flue gas outlet portion 121 for evacuating the treated flue gas is formed at the upper end portion thereof, and the flue gas passing through the introduction-side absorption tower 110 and passing through the upper part of the tank 101 flows upward. And a side absorption tower 120.

The absorption towers 110 and 120 are provided with spray pipes 112 and 122, respectively, and the spray pipes 112 and 122 are provided with a plurality of nozzles 113 and 123 for ejecting the absorbent spray upward in a liquid column shape. Has been formed. In addition, on both sides of the tank 101, a circulation pump 11 that sucks up the absorbent slurry in the tank 101.
4, 124 are provided, and the absorbent slurry is sent to the spray pipes 112, 122 via the circulation pipes 115, 125 and jetted from the nozzles 113, 123. Further, in this case, the desorption side absorption tower 12
A mist eliminator 130 for collecting and removing entrained mist is provided at the upper end of 0. The mist collected by the mist eliminator 130 is directly added to the tank 1 by dropping the mist inside the outlet side absorption tower 120, for example.
It is configured to return to 01. In FIG. 2, reference numeral 11 a is an air blower that supplies air to the air supply means 7 via the rotary joint 11.

The reference numeral 102 indicates the inner surface of the side wall of the tank 101 so as to cover the upper side and the front side of the outlet openings 105 (shown in FIG. 3) of the pumps 114 and 124 in the side wall of the tank 101. Is an inclined plate provided so as to extend obliquely downward from. In this case, as shown in FIG. 2, the inclined plate 102 is arranged over the entire length in the depth direction of the tank 101 and is collectively provided to the outlet opening of each pump. Between this and the bottom of the tank 101, a perforated plate 103 (most of which is not shown) is erected so as to divide this portion over the entire length in the depth direction. The perforated plate 103 is specifically, for example, punching metal having an opening ratio of 50%.
By providing such inclined plate 102 and perforated plate 103, suction of air bubbles into each pump and so-called short pass are suppressed as described later. 2 shows the state in which the partition wall 104 is provided, this is not necessary in this embodiment, and a mode in which this partition wall 104 is provided will be described later.

Next, the operation of the desulfurization apparatus constructed as above will be described. The absorbent slurry in the tank 101 is circulated by the circulation pumps 114 and 124, respectively.
It is supplied to the spray pipes 112 and 122 through 5,125. On the other hand, the flue gas is first introduced into the introduction side absorption tower 110 through the flue gas introduction section 111 and descends. The absorbent slurry supplied to the spray pipe 112 is the spray pipe 11
The absorbent slurry jetted upward from the second nozzle 113 and jetted upward is dispersed at the top and then descends, and the descending slurry and the jetted slurry collide with each other to form fine particles, and Particle-like slurries are generated one after another, and the particle-like slurries are dispersed and present in the tower, and eventually fall slowly. In this way, the flue gas containing the sulfurous acid gas flows down in the tower where the particulate slurry exists, so that the gas-liquid contact area per volume becomes large. Further, since the flue gas is effectively entrained in the jet flow of the slurry in the vicinity of the nozzle 113, the slurry and the flue gas are effectively mixed, and first, in the co-current absorption tower 110, a considerable amount of sulfurous acid gas is generated. To be removed. For example, even if the circulating flow rate of the absorbent slurry and the liquid column height in the introduction-side absorption tower 110 are set lower than in the conventional case, it is possible to absorb and remove the sulfurous acid gas at a desulfurization rate of about 60 to 70%. (In the past, one tower has 90 ~
Achieved a desulfurization rate of 95%).

Next, the flue gas flowing down the absorption tower 110 flows laterally in the upper part of the tank 101, and then from the lower part to the absorption tower 1
20 and the absorption tower 120 rises. In the absorption tower 120, the absorbent slurry is the nozzle 123 of the spray pipe 122.
Is sprayed upward from the above, becomes fine particles like the absorption tower 110 and slowly falls, and comes into contact with the flue gas flowing in the opposite direction. Further, since the flue gas is effectively entrained in the jet flow of the slurry near the nozzle 123, the slurry and the flue gas are effectively mixed, and the countercurrent absorption tower 120 is further mixed.
Finally, most of the remaining sulfurous acid gas is removed at. For example, sulfur dioxide is finally absorbed and removed at a desulfurization rate of 90 to 95% or more.

In the tank 101, as described in the conventional example, the air C flows from the air blower 11a through the rotary joint 11, the hollow rotary shaft 8 and the open end 10a of the air supply pipe 10 to the stirring rod 9. It is supplied to the above-mentioned gas phase region on the back surface side, and the vortex force generated by the rotation of the stirring rod 9 causes the phenomenon of the end of the gas phase region to be broken, and a large number of substantially uniform fine bubbles are generated. In the towers 110 and 120, the absorbent slurry that has absorbed the sulfurous acid gas and flows down is contacted with these air and oxidized, and gypsum is obtained as in the conventional case.

At this time, a large circulating flow is generated in the tank 101 by the operation of the arm rotation type air supply means 7, as shown by an arrow N5 in FIG. 3, and in the vicinity of the inner surface of the side wall of the tank 101. A downward flow is constantly occurring. However, even if there is such a downward flow along the inner surface of the side wall of the tank, this flow N5 is caused by the inclined plate 102 as shown in FIG.
The generation of a flow that is guided in a direction away from 05 and that branches from this flow and directly and smoothly flows into the outlet opening 105 is prevented. That is, the flow N6 that branches into the flow opening N5 and flows into the outlet opening 105 is a flow that bypasses the tip side of the inclined plate 102.
Further, the flow N6 is blocked below the tip of the inclined plate 102 by the perforated plate 103 so that the flow N6 is further twisted and bent while disturbing the flow direction. Therefore, the bubbles in the tank 101 (the bubbles contained in the flow N5 in a large amount) are separated from the flow N6 at this bypass portion on the tip side of the inclined plate 102, and further in front of the perforated plate 103. Almost no flow into the side space (ie the outlet opening).

On the other hand, the absorbent slurry falling above the pump outlet opening 105 is dragged by the large flow N5 by the air supply means 7 of the arm rotating type, and descends as a flow N7 along the side wall of the tank 101. To do. However, this flow N7 is also guided by the inclined plate 102 in a direction away from the outlet opening 105 of the pump as shown in FIG.
Is prevented from directly and smoothly flowing into the outlet opening 105 (that is, a short path). That is,
The flow N7 containing the dropped absorbent flows toward the center of the tank along the inclined plate 102 and flows into the space below the inclined plate 102 while disturbing the flow direction by the perforated plate 103, so that at least air bubbles are generated. Exit opening 1 after passing through a large amount of area, most of which has reacted with air bubbles (air)
It is sucked in 05.

As described above, according to the desulfurization apparatus having the gas-liquid contactor 100 of the above-mentioned embodiment, gas-liquid contact (absorption of sulfurous acid gas) can be performed in two stages in one tank. Therefore, even if the horizontal dimension of the device (mainly the area occupied by the tank 101) is maintained at the same level as the conventional one, and the height of each absorption tower and the circulation flow rate of the slurry are the same as or smaller than those of the conventional one, they are equal to or less than the conventional one. A higher gas-liquid contact efficiency (desulfurization rate) can be obtained. Then, the inclined plate 102 described above
By the action of the perforated plate 103 and each of the pumps 114, 12
The inflow of bubbles to 4, 12 is significantly reduced compared to the conventional one,
This has the effect of reliably avoiding performance deterioration or damage of the pump, or noise and vibration. Further, even if the hybrid type gas-liquid contact device 100 is adopted as in the above embodiment and the pump outlet opening 105 cannot be kept away from the position where the absorbent slurry falls, the inclined plate 1 described above is used.
Since the short path can be almost avoided by the action of 02 and the perforated plate 103, it is possible to further improve the desulfurization rate and the purity of gypsum as a by-product while achieving downsizing of the device.

The present invention is not limited to the above embodiment, but may have various modes. For example, as shown in FIG. 4, a configuration without the porous plate 103 may be used. Further, as shown in FIG. 5, a configuration may be employed in which an inclined plate 102a whose tip is bent downward is provided. Further, in the above embodiment, the outlet openings 105 of the pumps are arranged side by side in the depth direction of the tank 101, but the inclined plate 102 and the perforated plate 103 are provided.
A plurality of partition walls 104 as shown in FIG. 2 may be provided upright on the lower side of the inclined plate 102 so that the horizontally long space defined by 1 is partitioned by each of these outlet openings.
By doing so, the action of the partition wall 104 causes the absorbent slurry containing a large amount of unreacted limestone to circulate.
It is sucked up by 24. That is, the slurry pump 17
The discharge side of the circulation pumps 114 and 124 is connected to the space partitioned by the partition wall 104 so as to correspond to the outlet openings of the circulation pumps 114 and 124. If a new absorbent slurry is supplied, the absorbent slurry containing a large amount of unreacted limestone is sucked up by the circulation pumps 114 and 124. Further, in this case, the outlet opening for sucking the slurry in the tank 101 to produce gypsum as the by-product (the outlet opening for connecting the suction side of the extraction pump 12) is the same as the outlet opening of each circulation pump 114, 124. Is separated by the partition 104, so that a slurry containing a large amount of gypsum is efficiently derived by absorbing the sulfurous acid gas, flowing down, and being oxidized.

Further, the introduction side absorption tower 2 in the above embodiment
The 0 and outlet side absorption towers 30 are liquid column type, but may be grid type absorption towers (contact treatment towers). However, in the case of the grid type, it is preferable to provide a dust removing part because the dust removing action is small, and a pump and piping for this are also required. Therefore, the liquid column type which does not need these is superior. Further, the desulfurization apparatus of the present invention is not limited to the system employing the hybrid type gas-liquid contactor as in the above embodiment, and it goes without saying that it may have a conventional one-column structure.

[0029]

According to the present invention, even if there is a flow descending along the inner surface of the tank side wall, this flow is guided by the inclined plate in the direction away from the outlet opening of the pump and branched from this flow. The generation of a flow that directly and smoothly flows into the outlet opening is prevented. Further, the slurry that drops above the outlet opening of the pump also flows through the inclined plate toward the center of the tank, so that it passes through at least the region where a large amount of bubbles are present. Therefore, it is possible to prevent a large amount of bubbles from flowing into the outlet opening of the pump, reduce performance or damage of the pump, reduce noise and vibration, and reduce short paths.

When a perforated plate for closing the cold is erected between the tip of the inclined plate and the bottom surface of the tank, the flow flowing into the outlet opening should be further twisted before and after the perforated plate. become. Therefore, it is almost avoided that air bubbles flow into the outlet opening of the pump, resulting in deterioration of the performance of the pump.
Alternatively, damage, noise, etc. are significantly reduced, and short paths are further reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a wet flue gas desulfurization apparatus that is an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of a wet flue gas desulfurization apparatus that is an embodiment of the present invention.

FIG. 3 is a side view of a main part of a wet flue gas desulfurization apparatus that is an embodiment of the present invention.

FIG. 4 is a side view of a main part of a wet flue gas desulfurization apparatus according to another embodiment of the present invention.

FIG. 5 is a side view of a main part of a wet flue gas desulfurization apparatus according to an embodiment of the present invention.

FIG. 6 is an overall configuration diagram of a conventional wet flue gas desulfurization apparatus.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Noboru Ishii No. 2-5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. No.22 Mitsubishi Heavy Industries Ltd. Hiroshima Research Laboratory

Claims (2)

[Claims] 1. An absorption tower in which a calcium compound-containing slurry is supplied to a bottom tank, a circulation pump for sending the slurry in the tank to the upper part of the absorption tower to make contact with flue gas, and an oxidation tower in the tank. A wet oxidation flue gas desulfurization apparatus of a tank oxidation type, which is provided with an air supply means for supplying air for discharging and a withdrawal pump for withdrawing slurry in the tank, The wet flue gas desulfurization apparatus, wherein an inclined plate extending obliquely downward from the inner surface of the side wall of the tank is provided so as to cover at least the upper side of the outlet opening of the tank. 2. The wet flue gas desulfurization apparatus according to claim 1, wherein a perforated plate is erected on the bottom surface of the tank so as to separate the lower end of the inclined plate from the bottom surface of the tank. .