JPH09313880A - Flue gas desulfurizing treatment and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flue gas treating method by which flue gas desulfurization and dust removal are realized with a smaller equipment structure, at low cost and more effectively and a device therefor. SOLUTION: This device is constituted of a liquid absorbent feeding tank 1, an introducing side absorber 2 having the fixed sectional shape which is installed extended upward from one side thereof and in which slurry is jetted upward in liquid columns from plural places in the horizontal direction to bring untreated flue gas into gas-liquid contact with liquid absorbent in the tank, and a bring-out side absorber 3 having the fixed sectional shape which is installed extended upward from the other side and in which slurry is jetted upward in liquid columns from plural places in the horizontal direction to bring flue gas brought out from the introducing side absorber 2 into gasliquid contact again with the liquid absorbent in the tank. One of the introducing side and bring-out side absorbers 2, 3 is made a concurrent absorber in which flue gas descends, and the other of the introducing side and bring-out side absorbers 2, 3 is made a countercurrent absorber in which flue gas rises. The flow passage sectional area of the concurrent absorber is made smaller compared with that of the coutercurrent absorber so that high flue gas flow velocity desirable for dust collection and gaseous SO, absorption may be obtained. The flow passage sectional area of the coutercurrent absorber is made larger compared with that of the cocurrent absorber so that flue gas velocity preferable for gaseous SO2 absorption in the gas-liquid contact of countercurrent type may be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for flue gas treatment capable of efficiently desulfurizing and removing dust from flue gas at a low cost.

[0002]

2. Description of the Related Art Conventionally, as this type of flue gas treatment method or apparatus, a filling type absorption tower (gas-liquid contact tower) or a spray type or liquid column type absorption tower is used, and an absorbent such as limestone is used. It is known to remove dust such as sulfur oxides (mainly sulfurous acid gas) and fly ash in the flue gas by contacting the absorbing liquid in which the air is suspended with the flue gas.

Among them, the one using the filling type absorption tower is a so-called wet wall type gas-liquid contact device, and therefore the absorption tower body itself has a low dust removing performance. Further, even with a simple spray type absorption tower, it has been difficult to achieve high-performance desulfurization and to effectively generate collision dust removal described later to obtain high dust removal performance. For this reason, in such a filling type or mere spray type absorption tower, it is common practice to install a gas-liquid contact part for dust removal (for example, a Veturi scrubber) on the upstream side of the absorption tower. In recent years, it has been difficult to meet the demand for miniaturization and cost reduction while ensuring high performance that has been increasingly demanded in recent years.

On the other hand, in the case of using a liquid column type absorption tower, the absorption tower itself has high desulfurization performance as well as high dust removal performance as compared with the filling type and the like, so that it is small in size, low in cost and high in performance desulfurization and dust removal. Has been attracting attention as a means to realize.

A conventional liquid column type flue gas treatment apparatus is disclosed in, for example, Japanese Utility Model Laid-Open No. 59-53828, and a conventional spray type flue gas treatment apparatus is as follows.
For example, Japanese Patent Publication No. 59-38010 and Japanese Patent Laid-Open No. 7-11.
6457 or JP-A-8-19726.

However, even if the conventional filling type flue gas treatment apparatus or the conventional spray type or liquid column type flue gas treatment apparatus shown in the above-mentioned publication or the like, its basic constitution is one absorbing liquid. Even if one gas-liquid contact tower is installed for the tank or a gas-liquid contact tower for dust removal is provided separately, a separate circulating liquid tank is provided for that purpose, and desulfurization is performed. In addition to the high performance of dust removal, there was a limit to downsizing, cost reduction, and improvement of maintainability.

That is, in order to improve the performance, it is basically necessary to increase the number of spray nozzles installed in the spray type, and it is necessary to increase the height of the liquid column in the liquid column type. Further, in the filling type, it is necessary to increase the height of the filling portion. Furthermore, in the case of the filling type and spraying type, it is necessary to separately provide the gas-liquid contacting part for dust removal as described above together with the circulating liquid tank therefor, so the size of the entire device (particularly the absorption tower height and tank installation area) This is because the number and installation height of ducts and pipes connected to the equipment and the equipment are significantly increased, and the capacity and power of the pump for assembling the absorbing liquid are also considerably increased.

Further, since the entrained mist in the post-treatment flue gas discharged from the absorption tower contains a relatively high concentration of sulfite, the mist eliminator for recovering the entrained mist is apt to be clogged and the maintainability is improved. I had a problem with. Also,
In the case of a single tower type (method without a gas-liquid contact tower for dust removal), in order to efficiently cause the collision dust removal described later and obtain a high desulfurization rate and high dust removal performance in one absorption tower, It is necessary to increase the flow velocity of smoke, and in that case, the amount of the entrained mist (containing a relatively high concentration of sulfite) increases extremely, and it becomes necessary to provide a particularly large mist eliminator. In addition, the maintenance (frequent cleaning work for preventing the blockage) becomes extremely troublesome.

Even if a Bechery scrubber type device is provided as the dust-liquid contact portion for dust removal, such as the device disclosed in Japanese Patent Publication No. 59-38010, the gas-liquid contact portion for dust removal is not provided. The tank of the circulating liquid supplied to the part (cooling tower or first absorption tower) is the absorption tower main body (second
It is installed separately from the tank of the absorption liquid supplied to the absorption tower, and the circulating liquid has a desulfurization capacity that is significantly lower than that of the absorption liquid supplied to the main body of the absorption tower (it contains almost no unreacted limestone). Stuff). For this reason, most of the flue gas desulfurization is borne by the absorption tower body, and since the mist accompanying the flue gas discharged from the absorption tower body contains a relatively high concentration of sulfite salt, In addition to the problem of clogging of the eliminator, in addition, in order to obtain high desulfurization performance, the absorption tower body has to be large-sized (particularly the height is large).

In addition, the Bechery scrubber type gas-liquid contact part for dust removal significantly increases the flow rate of smoke (about 50 to 100 m / s) in the reduced diameter part called the throat part, and utilizes this high flow rate. Since the supplied circulating liquid is made into microdroplets to secure a considerable dust removal performance, as can be seen from the drawings of the above publication, the cross-sectional shape becomes a complicated tower shape, and a certain high dust removal rate. Although it can be achieved, the production cost will be much higher.

Therefore, the Applicant has proposed a device which realizes high performance and miniaturization over the limit of the conventional device as described in Japanese Patent Application No. 5-118171 (Japanese Patent Application Laid-Open No. 6-327927).
And so on.

In this system, two liquid column type absorption towers (parallel flow type and countercurrent type) are installed side by side on the upper part of one tank for storing the absorbing liquid, and the flue gas is sequentially guided to each absorption tower. Each absorption tower has a structure in which exhaust gas and gas-liquid contact with the absorbing liquid in the same tank are performed, which results in overall downsizing (mainly reduction of absorption tower height) and low cost. Achievement of high desulfurization performance and dust removal performance as well as reduction of both equipment cost and operating cost, and further reduction of sulfite concentration in the entrained mist to improve maintainability of the mist eliminator. .

[0013]

However, in order to realize desulfurization and dust removal more efficiently with a small apparatus configuration and low cost, the following apparatus is disclosed by the applicant in Japanese Patent Laid-Open No. 6-327927. There was a problem to be improved.

(1) In the apparatus disclosed in Japanese Patent Laid-Open No. 6-327927, both have a structure in which both desulfurization and dust removal are achieved with a predetermined target performance in one absorption tower. That is, the burdens of desulfurization and dust removal are simply divided into two in each of the two absorption towers of approximately the same size, and each of the absorption towers achieves both the desulfurization rate and the dust removal rate that are shared. There is a need to.

However, the gas-liquid contact condition which is originally preferable for dust removal and the gas-liquid contact condition which is preferable for desulfurization are not necessarily the same. That is, first, the minimum required supply flow rate (or liquid column height) of the absorbing solution is not equal between dust removal and desulfurization, and it is unavoidable to set the supply flow rate and the like corresponding to the larger one. Further, in order to efficiently remove dust in a small space while suppressing the supply flow rate of the absorbing liquid and the like, it is important to collect dust by collision between dust particles and droplets of absorbing liquid, which is so-called collision dust removal. In order to effectively cause the collision dust removal, it is necessary to increase the flow velocity of smoke exhaust to increase the collision energy.

On the other hand, in order to perform desulfurization efficiently in a small absorption tower having a shorter tower length, the flow rate of flue gas is set relatively low by increasing the cross-sectional area of the flue gas in order to increase the gas-liquid contact area. Will be required. In particular, in a countercurrent absorption tower in which flue gas rises with respect to the absorbing liquid that falls due to gravity, an increase in entrained mist that is carried away by flue gas becomes a problem. In order to achieve the above, it is necessary to set a low flow velocity at which dust removal performance cannot be expected.

For this reason, in the above-mentioned device, which is intended to achieve desulfurization and dust removal with desired performance simply at a plurality of divided gas-liquid contact towers, the flow rate of flue gas, the size of the gas-liquid contact portion, or the absorption liquid It was not possible to optimize the setting and control of various conditions such as the supply flow rate (circulation flow rate). In other words, if priority is given to efficient dust removal, it will be a wasteful condition for desulfurization, and if priority is given to efficient desulfurization, it will be an inefficient condition for dust removal. Also, in a counter-current absorption tower, in a configuration where dust removal and desulfurization are performed at a high flow rate that takes dust removal efficiency into consideration, entrained mist carried away by smoke emissions significantly increases, and these entrained mists are collected to obtain a desired desulfurization rate and dust removal. There was also a problem that a large mist eliminator had to be provided in order to achieve the rate.

(2) Further, for the same reason, when the amount of dust in the flue gas or the concentration of sulfur oxides fluctuates, both desulfurization and dust removal can be efficiently realized in accordance with these fluctuations. It was impossible. For example, the flue gas of a coal-fired boiler usually has a sulfur dioxide gas concentration of 200 ppm to 10 ppm.
Since it fluctuates in the range of about 00 ppm, if only the efficiency of desulfurization is taken into consideration, it is preferable to carry out an operation of changing the supply flow rate of the supply liquid of the absorption liquid in proportion to the fluctuation of the sulfurous acid gas concentration. Such an operation is not always possible to achieve the above dust removal rate, and as a result, excessive pump power may be consumed by injecting an excessive amount of absorbing liquid.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a flue gas treatment method and a flue gas treatment apparatus capable of more efficiently realizing desulfurization and dust removal of flue gas at a smaller device configuration and at low cost. And

[0020]

According to a first aspect of the present invention, in a flue gas treatment method for removing at least sulfurous acid gas and dust in flue gas by contacting the absorbent with gas-liquid, the absorbent is supplied. One tank and one tank is extended upward from one side, and the slurry is jetted upward in a liquid column from multiple horizontal positions, and the untreated smoke is brought into gas-liquid contact with the absorbing liquid in the tank. The inlet side absorption tower having a constant cross-sectional shape and extending upward from the other side portion of the tank, the slurry is jetted upward from a plurality of horizontal positions in a liquid column shape, and is led out from the inlet side absorption tower. Using a gas-liquid contactor having a derivation-side absorption tower having a constant cross-sectional shape for causing exhaust gas to come into gas-liquid contact with the absorption liquid in the tank again, one of the introduction-side absorption tower and the derivation-side absorption tower, Along with the parallel flow type absorption tower where smoke emission descends, The flow rate of flue gas in a flow-type absorption tower is set to a high flow rate that is preferable for collecting dust and absorbing sulfurous acid gas, and flue gas rises in the other of the introduction-side absorption tower and the derivation-side absorption tower. With a countercurrent type absorption tower, the flow rate of the flue gas in this countercurrent type absorption tower is set to a low flow rate that is preferable for the absorption of sulfurous acid gas in the countercurrent gas-liquid contact, and the one side cocurrent type The supply flow rate of the absorption liquid to the absorption tower is controlled so that the dust in the post-treatment smoke becomes a desired value, and the supply flow rate of the absorption liquid to the other countercurrent type absorption tower is changed to the post-treatment exhaust gas. A method for treating flue gas, which comprises operating so that at least the concentration of sulfurous acid gas in smoke reaches a desired value.

A second aspect of the present invention is a flue gas treatment apparatus for removing at least sulfurous acid gas and dust in flue gas by contacting the absorbing liquid with gas and liquid, and a tank to which the absorbing liquid is supplied, and a tank of this tank. An inlet side absorption that extends upward from one side and sprays the slurry upward from a plurality of horizontal positions in a liquid column shape to bring the untreated smoke and the absorbing liquid in the tank into gas-liquid contact The tower and the other side of the tank are extended upward, and the slurry is sprayed upward from a plurality of horizontal positions in a liquid column shape, and the flue gas derived from the introduction side absorption tower is absorbed by the absorption liquid in the tank. And a discharge side absorption tower having a constant cross-sectional shape for making gas-liquid contact again, and one of the introduction side absorption tower and the discharge side absorption tower is a co-current absorption tower in which flue gas descends, and the introduction side The other side of the absorption tower and the extraction side absorption tower is a countercurrent type in which smoke emission rises. With the absorption tower, the flow path cross-sectional area of the one co-current absorption tower, the countercurrent of the other so that a high flue gas flow rate preferable for dust collection and sulfur dioxide absorption can be obtained. It is set smaller than that of the absorption tower, and the flow passage cross-sectional area of the other countercurrent absorption tower is set so as to obtain a preferable flue gas flow rate for absorption of sulfurous acid gas in countercurrent gas-liquid contact. The flue gas treatment device is characterized in that it is set larger than one of the parallel flow type absorption towers.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) First, a first example of a smoke treatment apparatus to which the present invention is applied will be described with reference to FIG. FIG. 1 shows a main configuration of the device.

This flue gas treatment apparatus is provided with a tank 1 to which an absorbing liquid (hereinafter referred to as an absorbent slurry) in which an absorbent made of, for example, limestone is suspended is supplied, and is installed upward from one side of the tank 1. And a liquid column type introduction side absorption tower 2 (one absorption tower) for bringing the untreated flue gas A and the absorbent slurry in the tank 1 into gas-liquid contact, and extending upward from the other side part of the tank 1. And a gas-liquid contactor comprising a liquid column type outlet side absorption tower 3 (the other absorption tower) for bringing the exhaust gas discharged from the introduction side absorption tower 2 into gas-liquid contact with the absorbent slurry in the tank 1 again. Four
And

Here, the introduction-side absorption tower 2 has a constant flow passage cross-sectional shape at least in the gas-liquid contact portion, and a flue gas introduction portion (not shown) for introducing untreated flue gas A Is a so-called parallel flow type absorption tower which is formed at the upper end thereof and in which the flue gas flows downward. Further, in the outlet side absorption tower 3, at least the gas-liquid contact portion has a constant flow passage cross-sectional shape, and a smoke exhaust guide portion 5 for discharging the treated smoke exhaust B is formed at the upper end portion thereof. The introduction side absorption tower 2
It is a countercurrent type absorption tower in which the smoke exhausted through the upper part of the tank 1 flows upward.

In addition, the flow path cross-sectional area of the introduction side absorption tower 2 is such that the other side is absorbed so as to obtain a high flue gas flow rate (8 m / s to 12 m / s) which is preferable for collecting dust and absorbing sulfur dioxide gas. The flow rate of the flue gas (4 m / s to 6 m / s) is set to be smaller than that of the tower 3, and the flow passage cross-sectional area of the outlet side absorption tower 3 is low for absorption of sulfur dioxide in countercurrent gas-liquid contact. Is set to be larger than that of the introduction-side absorption tower 2. For example, flue gas from a 1000 MW coal-fired boiler (flow rate 3
000000 m ³ / h), the depth dimension is 21.4 m for both the introducing side and the conducting side, and the width dimension is L ₁ = 4.9 m for the introducing side and the conducting side for the introducing side as shown in FIG. 1. L
₂ = 10.4 m. In this case, the average flow rate of smoke exhaust in the introduction side absorption tower 2 is 10 m / s, and the average flow rate of smoke exhaust in the discharge side absorption tower 3 is 4.5 m / s.
m / s.

Further, a plurality of spray pipes 6 and 7 are provided in parallel in each of the absorption towers 2 and 3, and the absorbent slurry is sprayed upward to these spray pipes 6 and 7 in a liquid column type. A plurality of nozzles (not shown) are formed in the longitudinal direction (horizontal direction in FIG. 1). A large number of spray pipes 6, 7 and nozzles are provided at an arrangement interval of, for example, about 500 mm.

Further, on both sides of the tank 1, the tank 1
Circulation pumps 8 and 9 for sucking up the absorbent slurry inside are provided, and the absorbent slurry is sent to each spray pipe 6 and 7 through the circulation lines 10 and 11 and is jetted upward from each nozzle. Has been done.

Further, in this case, the flue gas discharge section 5 of the discharge side absorption tower 3 is provided with a mist eliminator 5a for collecting and removing entrained mist. In addition, the mist collected by the mist eliminator 5a is the lower hopper 5b.
Are collected into the tank 1 and returned to the inside of the tank 1 through a drainage pipe at the bottom of the hopper.

This apparatus is provided with a so-called arm rotating type air sparger 12 which blows the oxidizing air as fine bubbles while stirring the slurry in the tank 1, and absorbs sulfur dioxide gas in the tank 1. The agent slurry and air are efficiently contacted to oxidize the whole amount to obtain gypsum.

That is, in this device, the absorption tower 2 (or 3)
The absorbent slurry, which is sprayed from the spray pipe 6 (or 7) and contacts with the flue gas in gas-liquid contact and absorbs sulfur dioxide and dust while sulfiding, is agitated by the air sparger 12 in the tank 1 and is blown. It is oxidized by contact with many bubbles and undergoes a neutralization reaction to form gypsum. The main reaction that occurs during these treatments is the following reaction formula (1)
Through (3).

[0031] (absorption tower flue gas inlet _{section) SO 3 + H 2 O →} H + + HSO 3 - ... (1) ( ^{_{Tank) H + + HSO 3 - +}} (1/2) O 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, a small amount of limestone and dust, which are the gypsum and the absorbent, are constantly added. It is supposed to be suspended,
In this case, the slurry in the tank 1 is supplied to the solid-liquid separator 14 by the slurry pump 13, filtered, and taken out as gypsum C having a low water content (usually, the water content is about 10%). On the other hand, the filtrate from the solid-liquid separator 14 is supplied to the slurry adjusting tank 15 as water constituting the absorbent slurry.

The slurry adjusting tank 15 has a stirrer 16 and is charged with limestone (absorbent) from a limestone silo (not shown).
And the water sent from the solid-liquid separator 14 are stirred and mixed to generate an absorbent slurry, and the slurry slurry inside is appropriately supplied to the tank 1 by the slurry pump 17.

During operation, in the slurry adjusting tank 15,
For example, by a controller and a flow control valve not shown,
By adjusting the input amount and controlling the operation of a limestone silo, such as a rotary valve (not shown), limestone is appropriately supplied according to the amount of water to be input, and a predetermined concentration (for example, about 20% by weight) is supplied. ) Absorbent slurry is always kept within a certain range of levels.

Further, for example, make-up water (industrial water or the like) is appropriately supplied to the slurry adjusting tank 15 to compensate for water which is gradually reduced due to evaporation or the like in the gas-liquid contact device 4. Further, during operation, in order to maintain the desulfurization rate and the gypsum purity at a high level, the sulfurous acid gas concentration in the untreated flue gas A, the pH in the tank, the limestone concentration, etc. are detected by the sensor, and the slurry is controlled by a controller (not shown). The amount of limestone supplied to the adjusting tank 15 and the amount of absorbent slurry supplied to the tank 1 are appropriately adjusted.

Further, on the upstream side of the liquid column type gas-liquid contactor 4, a dry type electrostatic precipitator is usually provided to remove dust in the flue gas to some extent in advance. In the gas-liquid contactor 4 of the flue gas treatment device, since two liquid column type absorption towers are provided on the introduction side and the discharge side, the device configuration is smaller than the one-column type and the consumption power is low and the efficiency is high. In the introduction side absorption tower 2 in which good desulfurization and dust removal are possible, and the flow passage cross-sectional area is optimized especially for dust removal, dust absorption is efficiently performed along with the absorption of sulfurous acid gas, and the flow passage cross-sectional area is Outflow side absorption tower 3 optimized for desulfurization in countercurrent gas-liquid contact
In particular, the sulfurous acid gas is efficiently absorbed without increasing the entrained mist, and the above-mentioned JP-A-6-3279 is used.
The device disclosed by the applicant by No. 27, etc. (simple two-tower type)
In comparison, it is possible to achieve high-performance desulfurization and dust removal with a smaller device configuration and at a lower operating cost.

That is, the absorbent slurry in the tank 1 is supplied to the spray pipes 6 and 7 through the circulation pipes 10 and 11 by the circulation pumps 8 and 9, respectively. On the other hand, the flue gas is first introduced into the introduction absorption tower 2 and descends.

The absorbent slurry supplied to the spray pipe 6 is sprayed upward from each nozzle of the spray pipe 6, and the absorbent slurry sprayed downward is dispersed at the top and then descends, and the slurry that descends and sprays up. Slurry collides with each other and becomes fine particles. Further, the jet flow of the absorbent slurry blown up at a large number of locations forms a large number of reduced-diameter portions of the smoke exhaust flow passage in each gap between the streamlined outer extending portions of the adjacent tops, and overall a plurality of small-sized A large number of Bencherry scrubbers are formed in parallel in the absorption tower in the horizontal direction, and the large number of Bencherry effects also promotes atomization of the slurry.

In this way, fine particle-like slurries are generated one after another, and the flue gas containing sulfurous acid gas flows down in the tower in which the particulate slurries are dispersed, so that the gas-liquid volume per volume is increased. The contact area becomes large. In addition, since the flue gas is effectively entrained in the jet flow of the slurry in the vicinity of the nozzle, the slurry and the flue gas are effectively mixed, and a considerable amount of sulfurous acid gas is first mixed in the co-current type introduction side absorption tower 2. Are removed. For example, even if the circulation flow rate of the absorption tower slurry and the liquid column height in the introduction side absorption tower 2 are set lower than those of the conventional one-column type, the sulfur dioxide gas is absorbed and removed at a desulfurization rate of about 60 to 80%. It is possible (the conventional single column type achieves a desulfurization rate of 90 to 95% in one column).

Moreover, in the introduction side absorption tower 2, since the flow passage cross-sectional area is optimized especially for dust removal and the flow velocity of the exhaust gas is favorable for dust removal, so-called diffuse dust removal and the above-mentioned collision dust removal are effectively realized. Thus, the desired dust removal rate can be substantially achieved only by the introduction side absorption tower 2.

Next, the flue gas flowing down the introduction side absorption tower 2 is
After flowing laterally in the upper part of the tank 1, in this case, the derivation side absorption tower 3 enters from the lower part, and the derivation side absorption tower 3 rises. Also in the discharge side absorption tower 3, the absorbent slurry is jetted upward from each nozzle of the spray pipe 7 and, like the introduction side wave absorption tower 2, drops into fine particles and flows face to face. Contact with smoke emissions. Further, since the flue gas is effectively entrained in the jet flow of the slurry in the vicinity of the nozzle, the slurry and the flue gas are effectively mixed, and most of the remaining sulfurous acid gas in the countercurrent type outlet side absorption tower 3 is mixed. Are removed.

In this case, a considerable amount of sulfurous acid gas is removed by the introduction side absorption tower 2, and the flow passage cross-sectional area of the discharge side absorption tower 3 is set as described above, so that the flow rate of flue gas is countercurrent type. Since it is optimal for desulfurization in gas-liquid contact, for example, as shown in the data described below, at a liquid column height of about 2 to 3 m and at a circulating flow rate of the absorbent slurry of about 29400 m ³ / h. Finally, sulfur dioxide is absorbed and removed at a desulfurization rate of 95% or more.

That is, in the gas-liquid contactor 4 of the smoke treatment apparatus, the flow rate of the smoke in the introduction-side absorption tower 2 is set to a relatively high speed that is suitable for dust removal and desulfurization (particularly dust removal), and the discharge-side absorption tower 2 Since the flow rate of the flue gas in 3 is set to a relatively low speed that is preferable for desulfurization in countercurrent gas-liquid contact,
The dust removal is efficiently performed mainly in the introduction side absorption tower 2 with a smaller supply flow rate of the absorbent slurry (circulation flow rate by the circulation pump 8) and in a small space. On the other hand, the desulfurization is to increase the entrained mist mainly in the discharge side absorption tower 3 with a smaller supply flow rate of the absorbent slurry (circulation flow rate by the circulation pump 9) and a small space (especially low tower length). Done efficiently without. Moreover, in the introduction side absorption tower 2 which is the upstream side, as a result, a considerable amount of desulfurization is realized together with the dust removal, and the desulfurization burden in the extraction side absorption tower 3 is significantly reduced, and conversely, in the downstream side. In some discharge side absorption tower 3, as a result, some dust removal is realized together with desulfurization, and the load of dust removal in the introduction side absorption tower 2 is reduced. From this point as well, the absorption in each absorption tower 2, 3 is reduced. The circulation flow rate of the agent slurry and the height of the liquid column can be reduced.

Further, the flow rate of the exhaust gas in the introduction side absorption tower 2 is set to a relatively high speed which is particularly suitable for dust removal, and the flow rate of the exhaust gas in the discharge side absorption tower 3 is preferable for the desulfurization in the countercurrent gas-liquid contact. Since it is set to a relatively low speed, the circulating flow rate of the absorbent slurry in the introduction side absorption tower 2 is dominant as the operation amount that affects the overall dust removal performance, and is derived as the operation amount that affects the overall desulfurization performance. The circulation flow rate of the absorbent slurry in the side absorption tower 3 becomes dominant. Therefore, even if the sulfurous acid gas concentration and the dust concentration in the untreated flue gas fluctuate during operation, the circulation flow rate of each absorption tower can be operated separately as in the flue gas treatment method of the present invention described later. As a whole, desired dust removal and desulfurization can be performed with the minimum required pump power.

That is, for example, when only the sulfur dioxide gas concentration in the untreated flue gas decreases, the circulating flow rate of the absorbent slurry in the outlet side absorption tower 3 is reduced to reduce the sulfur dioxide gas concentration in the treated flue gas. While maintaining the desired value, the pump power is saved to the minimum necessary in response to the fluctuation of the sulfurous acid gas concentration,
On the other hand, by securing the necessary circulation flow rate in the introduction side absorption tower 2, it is possible to easily maintain the dust concentration in the flue gas after treatment at a desired value. Therefore, the pump power can be optimized to the required minimum while maintaining the minimum required desulfurization and dust removal performance by finely responding to each change in the sulfur dioxide gas concentration or the dust concentration in the flue gas.

Therefore, as compared with the device (simple two-column type) disclosed by the applicant in Japanese Patent Laid-Open No. 6-327927, the size of the device 4 is reduced as a whole (especially, the height of the column is reduced) and the equipment cost is reduced. Can be realized, and the operating cost can be reduced by optimizing the pump power.

Further, the gas-liquid contact device 4 of the above-mentioned flue gas treatment device
Then, the parallel flow type introduction side absorption tower 2 is used as the one side absorption tower of the present invention for the purpose of particularly high dust removal and desulfurization, and the flow passage cross-sectional area of the introduction side absorption tower 2 is reduced to reduce the flow rate of smoke. Since the speed is high, it is possible to significantly reduce the amount of mist that accompanies the exhaust gas and flows out, and it is possible to avoid the increase in the capacity of the mist eliminator described above.

That is, tentatively, the outlet side absorption tower (countercurrent absorption tower)
If the flow path cross-sectional area is reduced and the flow velocity is set to a high speed that is also preferable for dust removal, the mist that is entrained in the flue gas and flows out significantly increases, and if left unattended, the dust removal and desulfurization performance will decrease. Therefore, it is necessary to return the mist to the tank by increasing the capacity of the mist eliminator 5a described above. However, in the gas-liquid contactor 4, the flow speed of the exhaust gas of the introduction side absorption tower 2 (parallel flow type absorption tower) is made high while the flow speed of the exhaust gas of the discharge side absorption tower 3 (countercurrent type absorption tower) is made high. Since the smoke is flowing downward in the introduction side absorption tower 2, most of the mist generated in the introduction side absorption tower 2 falls into the tank 1 before entering the discharge side absorption tower 3, Further, in the discharge side absorption tower 3, the amount of mist entrained in the flue gas decreases as much as the flow rate of the flue gas decreases.
As a result, the increase of spilled mist is avoided. Therefore, it is possible to prevent an increase in the capacity of the mist eliminator 5a, and also from this point, downsizing of the device and reduction of equipment cost can be realized.

Further, since the flue gas introduced into the discharge side absorption tower 3 has already absorbed and removed a considerable amount of sulfurous acid gas in the discharge side absorption tower 2, it is finally discharged from the discharge side absorption tower 3. The entrained mist in the post-treatment flue gas B has an extremely low sulfite concentration, and the clogging of the mist eliminator is less likely to occur, and maintenance work thereof is significantly facilitated.

Next, the flue gas treatment method of the present invention carried out in the flue gas treatment apparatus described above will be explained. In the present method, in the apparatus configuration as described above, the flow rate of the exhaust gas in the introduction side absorption tower 2 is set to a relatively high speed that is preferable for dust removal and desulfurization as described above, and the flow rate of the smoke exhaust in the discharge side absorption tower 3 is set. Is set to a relatively low speed suitable for desulfurization in countercurrent gas-liquid contact, and the sulfurous acid gas concentration or dust concentration in the flue gas B after treatment is appropriately or continuously detected during operation to detect the concentration in the introduction side absorption tower. The circulating flow rate of the absorbing liquid of No. 2 is manipulated so that the dust concentration in the post-treatment flue gas B becomes a desired value, and the circulating flow rate of the absorbent slurry in the outlet side absorption tower 3 is set to that of the post-treatment flue gas B. Operate so that the concentration of sulfurous acid gas reaches the desired value.

That is, for example, when the sulfurous acid gas concentration in the post-treatment flue gas B increases above the upper limit value (for example, 50 ppm) of the desired range, the circulation flow rate of the outlet side absorption tower 3 is proportional to the degree of increase, for example. By increasing the so-called L / G (ratio of the circulation flow rate to the exhaust gas flow rate) and the liquid column height in the outlet side absorption tower 3 to increase the gas-liquid contact area, and the sulfur dioxide gas in the post-treatment exhaust gas B is increased. Suppress the increase in concentration. On the contrary, when the sulfurous acid gas concentration in the post-treatment flue gas B is lower than the lower limit value (for example, 40 ppm) of the desired range, the circulation flow rate of the absorbent slurry in the outlet side absorption tower 3 is reduced, for example, to the extent of the reduction. To reduce the so-called L / G (ratio of the absorbed liquid flow rate to the flue gas flow rate) and the liquid column height in the outlet side absorption tower 3 to reduce the gas-liquid contact area and to reduce unnecessary pump power. save. This makes it possible to maintain the sulfur dioxide gas concentration in the post-treatment flue gas B at a desired value (for example, 40 to 50 ppm) and maintain the pump power at the minimum required value in response to the variation in the sulfur dioxide gas concentration.

At this time, if the dust concentration in the treated flue gas slightly fluctuates due to fluctuations in the dust removal performance of the discharge side absorption tower 3, the circulating flow rate of the introduction side absorption tower 2 is finely adjusted. Therefore, the dust concentration in the post-treatment flue gas may be maintained at a desired value, but since gas-liquid contact of the introduction side absorption tower 2 is dominant for dust removal as described above, this introduction side absorption tower 2 There is almost no need to adjust the circulating flow rate of, and even if it is necessary, a small amount of operation is required.

If, for example, the dust concentration in the post-treatment flue gas B exceeds the upper limit of the desired range (for example, 5 mg / m ³ N), the so-called L / G in the introduction side absorption tower 2 is used.
(Ratio of absorption liquid flow rate to flue gas flow rate) and liquid column height are increased to increase gas-liquid contact area, and increase in dust concentration in post-treatment flue gas B is suppressed. On the contrary, the dust concentration in the post-treatment flue gas B is the lower limit of the desired range (for example, 4 mg / m ³ N).
If it is lower than the above, the circulation flow rate of the absorbent slurry in the introduction-side absorption tower 2 is reduced, for example, in proportion to the degree of the reduction, and so-called L / G (absorption liquid with respect to flue gas flow rate in the introduction-side absorption tower 2 is reduced. The ratio of the flow rate) and the height of the liquid column are reduced to reduce the gas-liquid contact area and save unnecessary pump power. As a result, while maintaining the dust concentration in the post-treatment flue gas B at a desired value (for example, 4 to 5 mg / m ³ N), the pump power is adjusted to the minimum required amount in response to fluctuations in the dust concentration in the untreated flue gas. Can be maintained at the value of.

At this time, if the sulfurous acid gas concentration in the treated flue gas slightly fluctuates due to the fluctuation of the desulfurization performance of the introduction side absorption tower 2, the circulation flow rate of the discharge side absorption tower 3 is finely adjusted. By doing so, the concentration of sulfurous acid gas in the flue gas after treatment may be maintained at a desired value. However, as described above, since gas-liquid contact of the outlet side absorption tower 3 is dominant in desulfurization, this outlet side absorption It is almost unnecessary to adjust the circulation flow rate of the tower 3, and even if it is necessary, a small amount of operation is required.

Therefore, the concentration of sulfurous acid gas in the untreated flue gas is lowered, and the circulation flow rate can be reduced for desulfurization to save a considerable amount of pump power, but an operation for reducing the circulation flow rate in order to maintain the dust removal performance. Not enough, or conversely, the dust concentration in the untreated flue gas decreases and the dust removal reduces the circulation flow rate and saves a considerable amount of pump power, but reduces the circulation flow rate to maintain desulfurization performance. There is no problem that the operation is not sufficient, and the operation can be continued while maintaining the desired desulfurization rate and dust removal rate with the minimum required pump power as a whole.

Further, regarding the overall dust removal performance, only the circulation flow rate of the introduction side absorption tower 2 is operated, and regarding the overall desulfurization performance, only the circulation flow rate of the delivery side absorption tower 3 is operated. Therefore, there is also an effect that the driving operation by a human or the driving by the automatic control becomes extremely easy.

The sulfurous acid gas concentration and the dust concentration in the post-treatment flue gas B may be detected continuously by, for example, providing a sensor in the flue gas discharge section 5, or by manual analysis, for example, periodically. You may make it detect. Further, the operation of each circulation flow rate based on this detection may be automatically performed by the functions of the flow rate control valves provided in the circulation lines 10 and 11 and the controller that controls the flow rate control valves, or manually operated by the operator. You may go by.

(Embodiment 2) Next, an example of a flue gas treatment apparatus to which the present invention is applied will be described. FIG. 2 is a diagram showing a main part configuration of the smoke exhaust processing apparatus of this example. The same components as those of the device of the first example shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

This flue gas treatment device is provided with a tank 31 to which the absorbent slurry is supplied in this case, and is extended upward from one side of this tank 31 to provide untreated flue gas A and the absorbent slurry in the tank 31. And a liquid column type introduction side absorption tower 32 (the other absorption tower) for making gas and liquid contact with each other, and extended upward from the other side part of the tank 31,
A gas-liquid contactor 34 comprising a liquid column type discharge side absorption tower 33 (one absorption tower) for causing the exhaust gas discharged from the introduction side absorption tower 32 to come into gas-liquid contact with the absorbent slurry in the tank 31 again. Prepare

Here, the inlet side absorption tower 32 and the outlet side absorption tower
33 has a constant flow passage cross-sectional shape at least in the gas-liquid contact portion, and is formed on both sides of a partition wall 35 arranged upright so as to partition the space above the tank 31. The introduction side absorption tower 32 is a so-called countercurrent absorption tower in which a smoke exhaust introduction portion 36 for introducing the untreated smoke A is formed at the lower end portion thereof and the smoke exhaust flows upward. The discharge side absorption tower 33 has a smoke discharge leading portion 37 for discharging the treated smoke B at its lower end, passes through the introduction side absorption tower 32, and passes through the connection space above the partition wall 35. Is a so-called co-current absorption tower that flows downward.

A mist eliminator 37a for collecting and removing the entrained mist is provided in the smoke exhaust leading section 37 of the lead-out side absorption tower 33, as in the first embodiment. The mist collected by the mist eliminator 37a is collected in the lower hopper 37b and returned to the inside of the tank 31 through the drain pipe at the bottom of the hopper.

Further, in this case, the flow passage cross-sectional area of the outlet side absorption tower 33 is set smaller than that of the other absorption tower so that a high flue gas flow rate suitable for dust collection and desulfurization can be obtained. The flow passage cross-sectional area of the introduction-side absorption tower 32 is set larger than that of the discharge-side absorption tower 33 so that a low flue gas flow rate that is preferable for absorption of sulfurous acid gas in countercurrent gas-liquid contact can be obtained.

In this case, the oxidizing air is supplied into the tank 31 by an air supply pipe or the like (not shown), the slurry in the tank 31 is stirred by the stirrer 38, and the oxidizing air becomes fine. It is configured to be air bubbles,
Similar to the first embodiment, the absorbent slurry that has absorbed the sulfurous acid gas in the tank 31 and the air efficiently come into contact with each other to oxidize the entire amount to generate gypsum.

In the apparatus of the second embodiment, the sulfur dioxide gas is mainly absorbed in the introduction side absorption tower 32, and the dust is mainly collected in the discharge side absorption tower 33. Similarly, by implementing the flue gas treatment method of the present invention, it becomes possible to perform predetermined desulfurization and dust removal with a smaller configuration and with less pump power, and efficiently respond to fluctuations in flue gas properties. Therefore, the installation space can be reduced and the equipment cost and the operation cost can be reduced.

Moreover, according to the apparatus of the second embodiment, since the smoke exhaust introducing section 36 and the smoke exhaust introducing section 37 are arranged at the lower end of the absorption tower, the installation height of the duct connecting them is small. There is a peculiar effect that the cost can be significantly reduced and the installation cost of the duct can be significantly reduced.

(Demonstration Data) Next, data of calculation results conducted by the inventors in order to demonstrate the action and effect of the present invention will be described.

First, an apparatus (i) comprising a conventional co-current liquid column type absorption tower (for example, the one-column type disclosed in the above-mentioned Japanese Utility Model Publication No. 59-53828) and a conventional co-current / direction. Apparatus composed of a liquid-column type absorption tower (for example, a simple two-column type disclosed in the above-mentioned JP-A-6-327927) (ii)
And the specifications and performance of the device (iii) comprising the co-current / counter-current liquid column type absorption tower (the gas-liquid contactor 4 of Example 1) to which the present invention is applied under the same conditions are shown below. .

(A) Calculation conditions Inlet gas amount 3000000m ³ N / h Inlet sulfur dioxide gas concentration 900ppm Inlet dust concentration 30mg / m ³ N Outlet sulfurous acid gas concentration (target value) 36ppm or less (desulfurization rate about 95% or more) Outlet dust concentration (Target value) 5 mg / m ³ N or less (b) Equipment specifications Absorption tower height (i) 24 m (ii) 18 m (introduction side), 17 m (outgoing side) (iii) 18 m (introduction side), 18 m (outgoing side) ) Liquid column height (i) 10.6m (ii) 11.4m (inlet side), 1.8m (outlet side) (iii) 4.4m (inlet side), 2.6m (outlet side) Absorption tower width Dimensions (i) 9.4m (ii) 9.5m (inlet side), 10.4m (outlet side) (iii) 4.7m (inlet side), 10.4m (outlet side) Absorption tower depth dimension (i) 22.4m (ii) 21.4m (introduction side), 21.4m (outgoing side) (iii) 21.4m (introduction side), 21.4m (Left side) Tank size (i) 21m (width) x 22.4m (depth) (ii) 23.9m (width) x 21.4m (depth) (iii) 19.3m (width) x 21.4m ( Depth) Circulation pump specifications (i) 9300m ³ / h × 22mH × 6 units (ii) 8600m ³ / h × 15mH × 4 units (introduction side) 8000m ³ / h × 13mH × 3 units (outgoing side) (iii) 9000m ³ / h × 15 mH × 2 units (introduction side) 9800 m ³ /h×13.6 mH × ³ units (outlet side) (c) Equipment performance Absorption tower outlet sulfur dioxide concentration (i) 36 ppm (ii) 230 ppm (introduction side) , 36 ppm (outgoing side) (iii) 360 ppm (introducing side), 36 ppm (outgoing side) Absorption tower outlet dust concentration (i) 4.4 mg / m ³ N (ii) 6.6 mg / m ³ N (introducing side), 3.2 mg / m
³ N (outgoing side) (iii) 4.0 mg / m ³ N (introducing side) 2.4 mg / m
³ N (outlet side) tower pressure loss (i) 93 mmH ₂ O, (ii) 106 mmH ₂ O, (iii) 1
43 mmH ₂ O absorption tower circulation flow rate (during steady operation) (i) 56000 m ³ / h (ii) 34200 m ³ / h (introduction side), 24300 m ³
/ H (outgoing side) (iii) 18000m ³ / h (introducing side), 29400m ³
/ H (Derived side) Power consumption comparison (during steady operation) (i) 100%, (ii) 85%, (iii) 84% Absorption tower final outlet entrained mist concentration (position immediately before mist eliminator) (i) 1-2 g / M ³ N (ii) 100 to 200 g / m ³ N (iii) 100 to 200 g / m ³ N Further, during the operation of the above devices (i), (ii) and (iii) under the condition (a), Inlet sulfur dioxide gas concentration is 900pp
The possible operating conditions and the device performance in that case are as follows.

(D) Operating conditions (inlet sulfur dioxide gas concentration 200
Absorption tower circulation flow rate (i) 56000 m ³ / h (ii) 34200 m ³ / h (introduction side), 18000 m ³
/ H (outgoing side) (iii) 18000m ³ / h (introducing side), 18000m ³
/ H (outgoing side) absorption tower liquid column height (i) 4.4m (ii) 4.4m (introducing side), 1.0m (outgoing side) (iii) 4.4m (introducing side), 1.0m (Derivation side) (e) Device performance (when changing to an inlet sulfur dioxide concentration of 200 ppm) Absorption tower outlet sulfur dioxide gas concentration (i) 2 ppm (ii) 30 ppm (introduction side), 30 ppm (outlet side) (iii) 55 ppm (introduction side) ), 11 ppm (outlet side) Absorption tower outlet dust concentration (i) 4.4 mg / m ³ N (ii) 6.6 mg / m ³ N (inlet side) 3.7 mg / m
³ N (outgoing side) (iii) 4.0 mg / m ³ N (introducing side) 2.9 mg / m
³ N (outlet side) tower pressure loss (i) 50 mmH ₂ O, (ii) 57 mmH ₂ O, (iii) 10
₂ mmH ₂ O consumption power comparison (during steady operation) (i) 100%, (ii) 77%, (iii) 69% Absorption tower final outlet entrained mist concentration (position immediately before mist eliminator) (i) 1-2 g / m ³ N (ii) 100 to 200 g / m ³ N (iii) 100 to 200 g / m ³ N According to the data of the above calculation results, an apparatus composed of a conventional co-current liquid column type absorption column (one column type) (i), a conventional cocurrent / countercurrent liquid column type absorption tower (simply two tower type) (ii), and a cocurrent / countercurrent liquid column type absorption tower to which the present invention is applied (Device (iii) comprising the gas-liquid contact device 4 of Example 1)
Of these, the device (iii) is the smallest and consumes the least power in any case. The amount of entrained mist in the devices (ii) and (iii) is much lower than that in the device (i) because the concentration of sulfite, which causes clogging of the mist eliminator, is extremely low.
In addition, since the amount of entrained mist mainly depends on the smoke exhaust flow velocity of the outlet side absorption tower, there is no change in the devices (ii) and (iii), and the device (i
In ii) extreme increases are avoided.

[0069]

According to the flue gas treatment method or flue gas treatment apparatus of the present invention, the flow rate of flue gas in the parallel flow type absorption tower of one of the introduction side absorption tower and the discharge side absorption tower is used for dust removal and desulfurization. The flow velocity of the flue gas in the other countercurrent type absorption tower of the introduction side absorption tower and the discharge side absorption tower is preferably a relatively low speed which is preferable for desulfurization in the countercurrent gas-liquid contact. Has become. Therefore, the dust removal is mainly performed efficiently in the one parallel-flow absorption tower with a smaller absorption liquid supply flow rate and in a small space, while the desulfurization is mainly performed in the other counter-current absorption tower. In the second aspect, it is also possible to efficiently perform the operation with a small supply flow rate of the absorbing solution and in a small space (especially, a low tower length).

Moreover, in the one absorption tower, as a result, a considerable amount of desulfurization is realized together with the dust removal, and the desulfurization load in the other absorption tower is significantly reduced, and conversely, in the other absorption tower. As a result, some dust removal is achieved together with desulfurization, and the burden of dust removal on the one absorption tower is reduced.From this point as well, the supply flow rate of the absorption liquid to each absorption tower and the size of the gas-liquid contact part are increased. The space (particularly the space in the tower height direction) can be reduced.

Further, the operation amount that affects the overall dust removal performance is dominated by the supply flow rate of the absorption liquid to the one parallel flow absorption tower, and the operation amount that affects the overall desulfurization performance is the other operation amount. The flow rate of the absorption liquid supplied to the countercurrent absorption tower becomes dominant.

Therefore, the supply flow rate of the absorption liquid to the one absorption tower is manipulated so that the dust in the treated flue gas reaches a desired value, and the supply flow rate of the absorption liquid to the other absorption tower is treated. If the flue gas treatment method of the present invention is operated so that at least the sulfur dioxide gas concentration in the post-flue gas becomes a desired value, even if there is a change in the untreated sulfur dioxide gas concentration or dust concentration during operation, By individually operating the absorption liquid supply flow rate of each absorption tower, desired dust removal and desulfurization can be achieved with the minimum required pump power as a whole.

That is, for example, when only the sulfur dioxide gas concentration in the untreated flue gas decreases, the concentration of the sulfur dioxide gas in the treated flue gas is reduced to a desired value by reducing the absorption liquid supply flow rate of the other absorption tower. The pump power is saved to the necessary minimum in response to the change in the sulfurous acid gas concentration while maintaining the above value, and on the other hand, by securing the required amount of the absorption liquid supply flow of the one absorption tower, the dust in the flue gas after treatment is reduced. The concentration can be easily maintained at a desired value.

Therefore, the concentration of sulfurous acid gas in the untreated flue gas decreases, and the supply flow rate for desulfurization can be reduced to save a considerable amount of pump power, but the absorption liquid supply flow rate can be reduced to maintain the dust removal performance. However, the dust concentration in the untreated flue gas decreases and the dust removal reduces the supply flow rate to save a considerable amount of pump power. The problem that the operation for reducing the liquid supply flow rate cannot be performed sufficiently does not occur, and the operation can be continued while always maintaining the desired desulfurization rate and dust removal rate with the minimum required pump power as a whole.

Therefore, as compared with the device (simple two-column type) disclosed by the applicant in Japanese Patent Application Laid-Open No. 6-327927, the overall size of the device can be reduced (particularly, the height of the column can be reduced) and the equipment cost can be reduced. It can be realized and the operating cost can be reduced by optimizing the pump power.

Further, according to the flue gas treatment method of the present invention, only the absorption liquid supply flow rate of one of the absorption towers is operated for the overall dust removal performance, and the overall desulfurization performance of the other absorption tower is controlled. Since this is a simple process of operating only the absorption liquid supply flow rate, there is also an effect that the driving operation by hand or the operation by automatic control becomes extremely easy.

Further, in the present invention, the absorption tower for the purpose of particularly high dust removal and desulfurization is a parallel flow type absorption tower, and the flow passage cross section area of this parallel flow type absorption tower is made small so that the flow rate of flue gas is increased. However, in the counter-current absorption tower, the flow velocity of the flue gas is set to a low speed, so that the amount of mist that is accompanied by the flue gas and flows out can be significantly reduced, and an increase in the capacity of the mist eliminator can be avoided. In addition, the flue gas introduced into the discharge side absorption tower has already been treated with a considerable amount of sulfurous acid gas in the flue gas after being processed in the introduction side absorption tower, and the entrained mist in the flue gas has an extremely low sulfite concentration, and the mist eliminator is blocked It will not happen easily and the maintenance work will be much easier.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a main part of a smoke exhaust processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of main parts of a smoke exhaust processing apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 1, 31 ... Tank, 2, 32 ... Introduction side absorption tower, 3, 33 ... Derivation side absorption tower. 4, 34 ... Gas-liquid contact device, 5 ... Smoke exhaust lead-out section, 5a, 37a ... Mist eliminator, 5b, 37b ... Lower hopper, 6, 7 ... Spray pipe, 8, 9 ... Circulation pump, 10, 11 ... Circulation line , 14 ... Solid-liquid separator, 15 ... Slurry adjusting tank, 16 ... Stirrer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Okazoe 5-1, Marunouchi, Chiyoda-ku, Tokyo Sanryo Heavy Industries Co., Ltd. No. Mitsubishi Heavy Industries, Ltd. Hiroshima Research Institute

Claims (2)

[Claims] 1. A flue gas treatment method for removing at least sulfurous acid gas and dust in flue gas by bringing the absorbent into gas-liquid contact to remove one tank to which the absorbent is supplied and one side portion of the tank. From above, the slurry is sprayed upward from a plurality of horizontal positions in a liquid column shape, and the untreated smoke and the absorption liquid in the tank are brought into gas-liquid contact with an inlet side absorption tower of a constant cross-sectional shape, Extending upward from the other side of the tank,
A discharge side absorption tower having a constant cross-sectional shape is provided for injecting the slurry upward in a liquid column shape from a plurality of positions in the horizontal direction to bring the smoke exhausted from the introduction side absorption tower into gas-liquid contact with the absorption liquid in the tank again. The gas-liquid contactor is used, and one of the introduction-side absorption tower and the derivation-side absorption tower is used as a co-current type absorption tower in which the flue gas descends, and the flue gas in this co-current type absorption tower is used. Is set to a high flow rate that is preferable for collecting dust and absorbing sulfurous acid gas, and the other of the introduction side absorption tower and the discharge side absorption tower is a countercurrent absorption tower in which the flue gas rises. Together with this, the flow rate of the flue gas in this countercurrent absorption tower is set to a low flow rate that is preferable for the absorption of sulfurous acid gas in the countercurrent gas-liquid contact, and the absorption liquid of the one cocurrent absorption tower is absorbed. Operate the supply flow rate so that the dust in the flue gas after treatment reaches the desired value , Flue gas treatment method of the supply flow rate of the absorbent liquid to the absorption tower of the other counter-current, at least sulfur dioxide concentration in the processed flue gas, characterized in that the operation to a desired value. 2. A flue gas treatment apparatus for removing at least sulfurous acid gas and dust in flue gas by bringing the absorbent into gas-liquid contact to remove it, and a tank to which the absorbent is supplied and an upper side from one side of the tank. An inlet side absorption tower having a constant cross-sectional shape for injecting the slurry upward in a liquid column shape from a plurality of horizontal positions in a liquid column direction to bring the untreated smoke and the absorbing liquid in the tank into gas-liquid contact, and the tank. Extending upward from the other side part, the slurry is sprayed upward from a plurality of horizontal positions in a liquid column shape, and the flue gas drawn out from the introduction side absorption tower is again brought into gas-liquid contact with the absorption liquid in the tank. And a discharge side absorption tower having a constant cross-sectional shape, one of the introduction side absorption tower and the discharge side absorption tower is a co-current absorption tower in which the smoke is lowered, and the introduction side absorption tower and the discharge side If the other side of the absorption tower is a countercurrent type absorption tower in which smoke emission rises In fact, the flow passage cross-sectional area of the one co-current absorption tower, the countercurrent absorption tower of the other so as to obtain a high flue gas flow rate preferred for dust collection and sulfur dioxide absorption. The flow passage cross-sectional area of the other countercurrent absorption tower is set to be smaller than that of the other countercurrent absorption tower so that a preferable flue gas flow rate for absorption of sulfurous acid gas in countercurrent gas-liquid contact can be obtained. A flue gas treatment device characterized by being set larger than a flow-type absorption tower.