JP2001252525A - Reaction apparatus for discharged carbon dioxide absorbing reaction - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the blow-through of CO2-containing exhaust gas in a packed bed when CO2 in the CO2-containing exhaust gas is absorbed and fixed by solid particles containing non-carbonated Ca by introducing the CO2-containing exhaust gas into a reaction tank packed with an aggregate of solid particles containing non- carbonated Ca in a moisture-containing state. SOLUTION: In a reaction apparatus for discharged carbon dioxide absorbing reaction, having the reaction tank packed with the aggregate of the solid particles containing non-carbonated Ca, the reaction tank has at least one constitution selected from constitution (a) such that a vibrator is provided in the reaction tank to apply vibration to the side wall thereof, constitution (b) such that inclination reducing the horizontal cross-sectional area in the reaction tank downwardly is applied to the inner wall surface of the reaction tank, constitution (c) such that the horizontal cross section of the reaction tank is formed into a circular or oval shape or the inner corner part of the reaction tank is formed into an arcuate or oval arcuate shape and constitution (d) such that an exhaust gas introducing part is provided in the upper part of the reaction tank and an exhaust gas discharge part is provided in the bottom part thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention reduces CO ₂ concentration in CO ₂ -containing exhaust gas generated in an industrial process or the like,
The present invention relates to a reaction apparatus for an exhaust carbon dioxide absorption reaction for reducing the amount of CO ₂ emitted into the atmosphere.

[0002]

_2. Description of the Related Art Conventionally, a technique of removing CO ₂ contained in exhaust gas generated in an industrial process or the like from the exhaust gas by absorbing and fixing the same in CaO or Ca (OH) ₂ is disclosed in Japanese Patent Application Laid-Open No. 3-32721. It is proposed in Japanese Patent Application Laid-Open No. 7-88362. Of these, Japanese Patent Laid-Open No.
No. 1 discloses that Ca is provided downstream of an exhaust gas discharge system of a combustion device.
A carbon dioxide gas removal apparatus provided with a fluidized bed of a solid base powder such as O or Ca (OH) ₂ is disclosed in JP-A-7-883.
No. 62 discloses a powdery carbon dioxide adsorbent mainly composed of industrial waste consisting of coal ash and blast furnace slag and containing a hydrate of a calcium compound.

[0003]

However, in these prior arts, the fixation of CO ₂ by CaO or Ca (OH) ₂ does not proceed at a sufficient speed, which makes it difficult to put it to practical use on an industrial scale. Accordingly, the present inventors have conducted a detailed study on absorption method CO ₂ to find a method capable and efficient absorption and removal of CO ₂ in the exhaust gas on an industrial scale, as a result, the absorption of CO ₂ in the prior art the fixing may not proceed at a sufficient rate, it the solid particles comprising the CaO or Ca _{(OH) 2} is because it was brought into contact with CO ₂ containing exhaust gas directly, including CaO and Ca _{(OH) 2} contrast in the presence of a suitable moisture solid particles, more preferably by contacting the CO ₂ containing exhaust gas through the surface adhesion water (water film formed on the solid particle surface) of the solid particles, the CO ₂ in the exhaust gas It has been found that solid particles can be efficiently absorbed and fixed.

According to the present invention, a CO ₂ -containing exhaust gas is brought into contact with solid particles containing CaO or Ca (OH) ₂ in the presence of such appropriate water to absorb and fix CO ₂ in the exhaust gas to the solid particles. Based on the method, a reactor suitable for carrying out the method is provided.

[0005]

[Means for Solving the Problems] CaO or Ca (OH) ₂
By contacting the exhaust gas with the solid particles containing the gas in the presence of appropriate moisture (more preferably via the water adhering to the surface of the solid particles), as a reactor for absorbing and fixing CO ₂ in the exhaust gas to the solid particles The fluidized bed system, rotary kiln system, packed bed system and the like can be considered. Of these, the packed bed system is the most simple and practical as an apparatus. Thus, the present inventors conducted various experiments for absorbing and fixing CO ₂ to solid particles using the packed bed type reaction apparatus. In this experiment, a box-shaped reaction vessel was filled with solid particles (solid particles containing CaO or Ca (OH) ₂ ) to which an appropriate amount of water was added, and CO ₂ -containing exhaust gas was supplied from the bottom of the reaction vessel. Was. As a result of this experiment, the following facts were found.

[0006] The heat generated in the reaction between CaO or Ca (OH) ₂ contained in the solid particles filled in the reaction tank and CO ₂ in the exhaust gas partially evaporates water in the reaction tank,
In addition, the packed bed inside the tank was filled with solid particles and evenly distributed, and was not compacted by pressing, etc.,
The packed bed is tightened by the vibration of the solid particles caused by the ventilation of the exhaust gas, and the apparent volume is reduced. Due to the shrinkage of the packed bed, passages (voids) of the exhaust gas having a major axis of about 5 mm to several cm are formed in the layer, which rapidly grows in a short time to form a major axis of 5 mm.
10 cm or more, and gas blow-through as shown in FIG. 4 occurs. When such blow-through occurs, most of the solid particles in the packed bed remain in insufficient contact with the exhaust gas, and the absorption and fixation rate of CO ₂ is significantly reduced.

[0007] The above-described gas blowout occurs because, when an exhaust gas passage is generated in an initial stage due to shrinkage of the packed bed, the flow of the exhaust gas is concentrated on the passage due to a small pressure loss, so that a large gas is rapidly generated. This is because it becomes a flow path and this becomes a blow-by. Blow-through is likely to occur generally at a position along the inner wall surface of the reaction tank or at a corner (corner) of the reaction tank. this is,
Since deposits of water-containing solid particles are likely to be formed on the inner wall surface of the vessel, voids are likely to be formed along the wall surface (accurately, wall deposits) due to the decrease in the volume of the packed bed, and the corner of the reaction vessel This is considered to be due to the fact that the filling density is low from the beginning in the filling by simple charging, and a small passage for the exhaust gas, which is the starting point of the blow-through, is easily formed here.

[0008] Furthermore, supplying exhaust gas from the bottom of the reaction tank into the tank is also one of the causes of blow-by. In other words, when the exhaust gas is supplied from the bottom of the reaction tank into the tank, the effect of lifting the packed bed by the exhaust gas flow hinders the tightness of the packed bed itself due to its own weight, and this action also creates a passage for the exhaust gas that becomes the starting point of blow-through. This leads to the occurrence of blow-by in the above process. In addition, blow-through due to such a main cause is likely to occur generally along the inner wall surface of the reaction tank. This is considered to be because a gap is generated between the inner wall surface due to the decrease in the volume of the filler and the passage of the initial exhaust gas as described above easily occurs.

As a result of examining measures for preventing the occurrence of blow-by of exhaust gas generated by the above mechanism, the following means are effective, and by appropriately combining them, the occurrence of blow-through can be more effectively reduced. It turned out that it could be prevented. (1) A vibration device for applying vibration to the side wall of the reaction tank is provided. By vibrating the side wall of the reaction tank with such a vibration device, the solid particles are prevented from adhering to the inner wall surface of the tank, and the packed bed is promoted to be tightened by its own weight. The generation of small passages of exhaust gas can be suppressed.

(2) The inner wall surface of the reaction tank is provided with an inclination toward the bottom of the tank so as to reduce the horizontal sectional area inside the tank. Such a reduction in the horizontal cross-sectional area inside the tank due to the inclination offsets the volume reduction due to the compaction of the packed bed caused by the exhaust gas ventilation, and as a result, it is possible to suppress the generation of small exhaust gas passages that serve as starting points for blow-through. . (3) The horizontal cross-sectional shape inside the reaction tank is configured to be circular, elliptical, or a shape in which a corner is an arc or an elliptical arc.
As described above, in the filling by simple charging into the reaction tank, the packing density of the solid particles at the corner of the reaction tank is reduced, and when the volume of the packed bed is reduced as described above, the corner of the reaction tank is blown through. It is easy to create a path for the exhaust gas, which is the starting point of the exhaust gas. On the other hand, the horizontal cross-sectional shape of the reaction tank is made circular or elliptical to eliminate corners, or the horizontal cross-sectional shape of the corner is made circular or elliptical to eliminate corners where the packing density becomes low. This prevents a portion having a low filling density from being formed in the reaction tank, thereby suppressing the generation of a small passage of the exhaust gas serving as a starting point of the blow-through.

(4) An exhaust gas introduction section is provided at the top of the reaction tank, and an exhaust gas discharge section is provided at the bottom of the reaction tank. As a result, the effect of lifting the packed bed by the exhaust gas flow is eliminated, and the generation of a small passage for the exhaust gas, which is a starting point of the blow-through, can be suppressed. (5) In the structure of the above (1) to (3), the exhaust gas introduction part of the reaction tank is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate, and exhaust gas is supplied to the exhaust gas chamber. By adopting a structure in which the pipes are connected, exhaust gas can flow through the entire packed bed, thereby preventing a packed bed portion where the reaction with CO ₂ is insufficient.

(6) In the structure of the above (4), the exhaust gas discharging section is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate, and an exhaust gas discharging pipe is connected to the exhaust gas chamber. By doing so, the exhaust gas can flow through the entire packed bed, and the formation of the packed bed portion where the reaction with CO ₂ is insufficient is prevented. In addition, since the perforated plate has a structure having gas holes only in a region other than the outer edge near the tank side wall, the flow of exhaust gas is guided toward the center of the bottom of the tank. The formation of a gas flow in the vicinity of the airflow is appropriately suppressed, and the generation of a small passage of exhaust gas serving as a starting point of blow-through can be suppressed. (7) By combining two or more structures selected from the above (1) to (4), blow-through can be more effectively prevented. Further, by combining the above configurations (1) to (3), and more preferably combining all of (1) to (4), blow-through can be most effectively prevented.

The present invention has been made based on the above findings, and the features are as follows. [1] There is a reaction tank in which an aggregate of solid particles containing CaO and / or Ca (OH) ₂ as a composition is filled in a state containing water, and a CO ₂ -containing exhaust gas is introduced into the reaction tank. A reactor for absorbing and fixing CO ₂ in a CO ₂ -containing exhaust gas to the solid particles, wherein a vibrating device for applying vibration to a side wall of the reactor is provided in the reactor. A reactor for the reaction.

[2] CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reactor for absorbing and fixing O ₂ , wherein an inner wall surface of the reaction tank is inclined downward toward the tank so as to reduce the horizontal cross-sectional area inside the tank. A reactor for the reaction.

[3] CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reactor for absorbing and fixing O ₂ , wherein the horizontal cross-sectional shape inside the reaction tank is formed in a circular shape, an elliptical shape, or a shape in which a corner is an arc or an elliptical arc. Reactor for gas absorption reaction. [4] In the reactor according to any one of the above [1] to [3], the exhaust gas introduction section of the reaction tank is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate. A reaction apparatus for an exhaust carbon dioxide absorption reaction, characterized in that an exhaust gas supply pipe is connected to the chamber.

[5] The composition is CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reaction apparatus for absorbing and fixing O ₂ , wherein an exhaust gas introduction part is provided at an upper part of the reaction tank, and an exhaust gas discharge part is provided at a bottom part of the reaction tank. Reactor.

[6] In the reactor according to the above [5], the exhaust gas discharge section is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate, and an exhaust gas discharge pipe is connected to the exhaust gas chamber. A reaction device for an exhaust carbon dioxide absorption reaction characterized by the following. [7] The reactor according to the above [6], wherein the perforated plate has a gas passage only in a region other than an outer edge portion near the side wall of the tank, the reactor for an exhaust carbon dioxide absorption reaction.

[8] The composition is CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reaction device for absorbing and fixing O ₂ , wherein the reaction tank has two or more components selected from the following (a) to (d): For reactors. (a) The reaction tank is provided with a vibration device for applying vibration to the side wall of the tank. (b) The inner wall surface of the reaction tank is inclined downward to reduce the horizontal cross-sectional area inside the reaction tank. (c) The horizontal cross-sectional shape inside the reaction tank is formed into a circular shape, an elliptical shape, or a shape in which a corner is a circular arc or an elliptical arc. (d) An exhaust gas introduction section is provided at the top of the reaction tank, and an exhaust gas discharge section is provided at the bottom of the reaction tank.

[9] The reaction apparatus according to the above [8], wherein the reaction tank has the configuration of (a) to (c). [10] In the reactor according to the above [8] or [9], the reaction vessel is (a)
To two or more selected from (c), and the exhaust gas introduction part of the reaction tank is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate, A reaction device for an exhaust carbon dioxide absorption reaction, characterized in that an exhaust gas supply pipe is connected to the reactor. [11] The reactor according to the above [8], wherein the reaction vessel has the configuration of (a) to (d), wherein the reactor is used for an exhaust carbon dioxide absorption reaction.

[12] In the reactor according to the above [8] or [11], the reaction tank is selected from the configuration of (d) and one of (a) to (c).
The exhaust gas discharge section is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed thereunder, and an exhaust gas discharge pipe is connected to the exhaust gas chamber. Reactor for carbon dioxide absorption reaction. [13] The reactor for exhaust carbon dioxide absorption reaction according to the above [12], wherein the perforated plate has gas holes only in a region other than the outer edge near the tank side wall.

[0021]

1 and 2 show an embodiment of a reaction apparatus according to the present invention. FIG. 1 is a schematic longitudinal sectional view of the apparatus.
FIG. 2 is a schematic cross-sectional view of the same. In FIG, 1 is a reactor of the closed type (or semi-closed type) for forming a packed bed of aggregate of solid particles, on the bottom side of the reaction vessel 1 supplies the exhaust gas (CO ₂ containing exhaust gas) And an exhaust gas discharge unit 3 for discharging exhaust gas supplied into the tank is provided at the upper end side, respectively.
An exhaust gas supply pipe 4 and an exhaust gas discharge pipe 5 are connected to the exhaust gas introduction section 2 and the exhaust gas discharge section 3, respectively. The reaction vessel 1 has a packing inlet / outlet (or a charging / discharging section and a discharging section) (not shown), through which the aggregate of solid particles (filling) enters / reacts into / from the reaction tank 1. I do.

In the present embodiment, the inside of the reaction tank 1 is partitioned by a perforated plate 6 provided near the bottom thereof, and an exhaust gas chamber 7a having the function of a wind box is formed below the perforated plate 4, and this exhaust gas is formed. The exhaust gas supply pipe 4 for the chamber 7a
Is connected. The perforated plate 6 has a large number of small-diameter gas through holes 60 penetrating the entire surface thereof. Therefore, in this embodiment, the perforated plate 6 and the exhaust gas chamber 7a constitute the gas introducing section 2, and the space above the perforated plate 6 constitutes a reaction chamber 7b for filling solid particles. The perforated plate 6
The diameter of the gas through hole 60 is appropriately selected according to the particle size of the solid particles constituting the packed layer in order to prevent the solid particles from falling and clogging with the solid particles.

The inside of the reaction tank 1 has a rectangular horizontal cross section, and a corner 8 (corner) is rounded to form an arc. This corner 8
The size of the radius may be appropriately selected. However, if the radius is too small, the packing density of the filler (solid particles) at the corner 8 cannot be sufficiently ensured, and the exhaust gas serving as the starting point of blow-through in this portion is small. A path is formed. Therefore, the radius of the corner 8 is preferably 50 mm or more, more preferably 100 mm or more. Note that the horizontal cross-sectional shape inside the reaction tank may be any shape that does not have angular corners. Therefore, in addition to the shape of the present embodiment, the corners may be formed into elliptical arcs or the horizontal inside the reaction tank. The cross-sectional shape may be circular or elliptical.

Further, the inner wall surface 9 of the reaction tank 1 is provided with an inclination toward the lower part of the tank so as to reduce the horizontal sectional area inside the tank. The degree of inclination of the inner wall surface 9 may be appropriately selected as long as the effective volume in the tank does not become excessively small, but it is generally effective to set the inclination to 1/10 or more with respect to the vertical direction. Further, outside the side wall of the reaction tank 1,
A vibration device 10 for applying vibration to the tank side wall is provided. The type of the vibration device 10 is not limited as long as it can vibrate the side wall of the tank to prevent the packing (solid particles) from adhering to the inner wall surface of the tank. For example, an eccentric mass type vibration device can be used.

In the apparatus of this embodiment, a plurality of reaction tanks 1 are provided as shown by phantom lines in FIG. 1, and exhaust gas supply pipes are connected in series to these reaction tanks 1, 1a, 1b,. It can also be structured. According to such a device, a plurality of serially connected exhaust gas discharged from the reaction tank 1 is supplied to the reaction tank 1a, and the exhaust gas discharged from the reaction tank 1a is supplied to the reaction tank 1b. By sequentially treating the exhaust gas in the reaction tank, CO ₂ in the exhaust gas can be effectively reduced.

In the apparatus of the embodiment shown in FIGS. 1 and 2,
Collection of solid particles in a reaction chamber 7b of the reactor 1 is charged has been packed layer A is formed, CO ₂ containing exhaust gas is supplied to the packed bed A. After the exhaust gas is supplied from the exhaust gas supply pipe 4 to the exhaust gas chamber 7a at the bottom of the tank, the exhaust gas is supplied to the packed bed A through a number of gas holes 60 of the perforated plate 6, and the packed bed A
CO ₂ in the exhaust gas is converted into solid particles of CaO,
Reacts with Ca (OH) _2, and CO ₂ becomes CaCO ₂ into solid particles.
Fixed as ₃ . After the reaction, the exhaust gas is discharged out of the tank from the exhaust gas discharge section 3 and the exhaust gas discharge pipe 5 in the upper part of the tank. Then, the vibrating device 10 is operated continuously or at an arbitrary timing during the operation of such a device to vibrate the side wall of the reaction tank 1, whereby the packing (solid particles) adheres to the inner wall surface of the tank. Is prevented, and tightening of the packed bed A by its own weight is promoted, thereby suppressing the generation of a small passage of exhaust gas, which is a starting point of blow-through.

The packed bed A caused by exhaust gas ventilation due to the reduction of the inner cross-sectional area of the reactor due to the inclination of the inner wall surface 9 of the reactor 1
The volume reduction due to the tightness of the gas is offset, the generation of small passages of exhaust gas that will be the starting point of the blow-through is suppressed,
Since the corners 8 of the reaction tank 1 are arc-shaped, the packing density of the packing material at the corners 8 is ensured, thereby suppressing the generation of small passages of exhaust gas that serve as starting points of blow-through at the corners 8. Further, in the present embodiment, the exhaust gas introduction section 2 is constituted by a perforated plate 6 provided at the bottom of the reaction tank 1 and an exhaust gas chamber 7a formed below the porous plate 6, and the exhaust gas supply pipe 4 is connected to the exhaust gas chamber 7a. Due to the structure, the exhaust gas can flow through the entire packed bed, and the formation of the packed bed portion in which the reaction with CO ₂ is insufficient is prevented.

FIG. 3 is a schematic longitudinal sectional view showing another embodiment of the reactor of the present invention. In the figure, 11 is a reaction vessel of the closed type (or semi-closed type) for forming a packed bed of aggregate of solid particles, the upper end of the reactor 11 supplies the exhaust gas (CO ₂ containing exhaust gas) And an exhaust gas discharge unit 13 for discharging exhaust gas supplied into the tank is provided on the bottom side, respectively. The exhaust gas introduction unit 12 and the exhaust gas discharge unit 13 have An exhaust gas supply pipe 14 and an exhaust gas discharge pipe 15 are connected. The reaction tank 11 has a filling inlet / outlet (or a charging / discharging part and a discharging part) (not shown), through which the aggregate of solid particles (filling) enters and leaves the reaction tank 11 through the filling inlet / outlet. I do.

In the present embodiment, the inside of the reaction tank 11 is partitioned by a perforated plate 16 provided near the bottom thereof, and an exhaust gas chamber 17a for discharging gas is formed below the perforated plate 16; Is connected to the exhaust gas discharge pipe 14. The perforated plate 16 has a large number of small-diameter gas through holes 160 penetrating therethrough. Therefore, in this embodiment, the perforated plate 16 and the exhaust gas chamber 17a constitute the exhaust gas discharge section 12, and the space above the perforated plate 16 constitutes the reaction chamber 17b for filling solid particles.

Gas through holes 16 penetrating through the perforated plate 16
The pore size of 0 is appropriately selected according to the particle size of the solid particles constituting the packed layer in order to prevent the solid particles from scattering through the gas through holes 160 and preventing the solid particles from clogging. Since water is added to the filler (solid particles) in the reaction vessel 11, even if the gas passage hole 160 has a certain size larger than the size of the solid particles, the scattering of the solid particles is not a problem. However, in the experimental results, for example, 6
In the case of using solid particles having a diameter of under mm (such as steel slag), scattering of the solid particles was almost negligible if the diameter of the gas through hole 160 was 4 mm or less. On the other hand, regarding the lower limit of the hole diameter of the gas through hole 160, for example, when solid particles having the above-mentioned particle diameter are used, if the hole diameter is less than 1 mm, the clogging by the solid particles tends to be remarkable. However, the scattering of solid particles through the gas holes 160 and the tendency of clogging of the gas holes 160 by the solid particles depend not only on the undersize of the solid particles used but also on the particle size distribution. Is appropriately selected according to the conditions.

In general, the flow velocity of the cylinder in the reaction tank 11 is set to 0.1.
There is no need to consider dynamic pressure because it is extremely slow, 15 to 0.01 m / s. For this reason, the gas introduction unit 12 does not necessarily need to be provided on the ceiling of the reaction tank 11,
May be provided on the upper part of the side wall. In installing the gas introduction unit 12 and the gas supply pipe 14, the gas supply pipe 1
It is preferable to take measures such as installing an appropriate drain vent so that the drain in 4 does not flow into the packed bed.

The blow-through of the exhaust gas is easily formed along the inner wall surface of the reaction vessel 11. To prevent this, the exhaust gas flow flowing from the upper surface of the packed bed toward the bottom thereof is directed toward the center of the bottom of the reaction vessel 11. Preferably, it is induced. For this reason, in the present embodiment, the gas through-holes 160 of the perforated plate 16 are not formed at the outer edge near the tank side wall, but are provided only in the region excluding the outer edge. Normally, gas through hole 1
The range of the outer edge portion of the perforated plate 16 where no 60 is provided (ie,
When the horizontal cross-sectional shape of the bottom of the reactor is a polygonal shape such as a rectangular shape, the width of the outer edge in the direction from the side wall to the center of the perforated plate is 10% or more of the length of each side. If the horizontal cross-sectional shape of the circle is a circle,
% Or more, and when the horizontal cross-sectional shape of the bottom of the reaction vessel is an elliptical shape, it is preferable to be 10% or more of the minor axis of the ellipse.
On the other hand, if the range of the outer edge portion where the gas through hole 160 is not provided is too large, the exhaust gas flow is concentrated on the bottom center side of the reaction tank 11, so that the packing near the tank side wall (particularly, the packing near the tank bottom) is removed. The supply amount of the exhaust gas is reduced, and the packing in this portion remains unreacted. Therefore, in each case described above, the range (width) of the outer edge portion where the gas through hole 160 is not provided is preferably 20% or less.

Regarding the number of gas through holes 160,
In order to prevent scattering of solid particles through the gas through holes 160 and clogging of the gas through holes by the solid particles, the exhaust gas flow rate is determined by summing the cross-sectional area of all the gas through holes. The number is preferably such that the average passage velocity divided by (the cross-sectional area of the through-holes × the number of gas through-holes) is 10 m / s or less, preferably about 1 to 3 m / s.

In the apparatus of this embodiment, a plurality of reaction tanks 11 are provided as shown by phantom lines in FIG. 3, and exhaust gas supply pipes are connected in series to these reaction tanks 11, 11a, 11b. It can also be structured. According to such an apparatus, the exhaust gas discharged from the reaction tank 11 is
1a, the exhaust gas discharged from the reaction tank 11a is supplied to the reaction tank 11b, and the exhaust gas is sequentially processed in a plurality of serial reaction tanks, thereby effectively reducing CO ₂ in the exhaust gas. Can be reduced.

In the apparatus of the embodiment shown in FIG.
Collection of solid particles in the first reaction chamber 17b is charged has been packed layer A is formed, CO ₂ containing exhaust gas is supplied to the packed bed A. After the exhaust gas is supplied from the exhaust gas supply pipe 14 into the tank interior space above the packed bed, the exhaust gas flows from the top to the bottom inside the packed bed A. In the course of flowing through the packed bed A, CO ₂ in the exhaust gas is converted into solid particles. CaO, reacts with Ca _{(OH) 2,} CO ₂ is fixed as CaCO ₃ to the solid particles.
After the reaction, the exhaust gas is supplied to the gas passage 160 of the perforated plate 16.
The exhaust gas is collected in the exhaust gas chamber 17a and discharged out of the tank from the exhaust gas discharge section 13 and the exhaust gas discharge conduit 15 at the bottom of the tank.

Since the exhaust gas flows from the top to the bottom in the packed bed A as described above, the effect of lifting the packed bed A by the exhaust gas flow is lost, and the generation of a small passage of the exhaust gas serving as a starting point of blow-through is suppressed. . Furthermore, in the present embodiment, the exhaust gas discharge unit 13 is provided with a perforated plate 16 provided at the bottom of the reaction tank 11 and the exhaust gas chamber 1 formed thereunder.
7a, the exhaust gas exhaust pipe 15 is connected to the exhaust gas chamber 17a, and the perforated plate 16 has a gas through hole 160 only in a region other than the outer edge portion near the tank side wall. Exhaust gas can flow through the whole,
The formation of a packed bed portion where the reaction with CO ₂ is insufficient is prevented, and the formation of a gas flow in the vicinity of the inner wall surface of the tank, in which blow-through tends to occur, is appropriately suppressed, and the exhaust gas serving as the starting point of blow-through is suppressed. The occurrence of small passages can be suppressed.

Of the above two embodiments, the embodiment shown in FIGS. 1 and 2 has a structure having the following constitutions (a) to (c) of the following constitutions (a) to (d). The embodiment shown in FIG. 3 has a structure having the configuration of (d), but the device of the present invention has at least one of the following (a) to (d): By providing the configuration, a desired blow-through prevention effect can be obtained. On the other hand, by providing two or more of the following configurations (a) to (d), and preferably also including the configurations (a) to (c) as in the embodiment of FIGS. Thereby, more preferably, all of the configurations (a) to (d) are provided, whereby a more excellent blow-through prevention effect can be obtained. When two of the following configurations (a) to (d) are combined, a combination of (a)-(b) is particularly preferable.

(A) The reaction tank is provided with a vibration device for applying vibration to the side wall of the reaction tank. (b) The inner wall surface of the reaction tank is inclined downward to reduce the horizontal cross-sectional area inside the reaction tank. (c) The horizontal cross-sectional shape inside the reaction tank is formed into a circular shape, an elliptical shape, or a shape in which a corner is a circular arc or an elliptical arc. (d) An exhaust gas introduction section is provided at the top of the reaction tank, and an exhaust gas discharge section is provided at the bottom of the reaction tank.

Next, the immobilizing action of CO ₂ in the apparatus of the present invention, the conditions of solid particles and exhaust gas to be used, the conditions for charging solid particles into the reaction tank, and the like will be described. The packed layer A formed in the apparatus of the present invention is made of, for example, CaO and / or Ca such as slag or concrete.
(OH) ₂ (Hereinafter, CaO will be described as an example). The aggregate of the solid particles is brought into contact with a CO ₂ -containing exhaust gas in the presence of water, and the CO in the exhaust gas is reacted by the following reaction. ₂ is fixed to solid particles as CaCO ₃ , and CO ₂ in the exhaust gas is absorbed and removed. CaO (solid particles) + CO ₂ (exhaust gas) → CaCO
₃ (solid particles)

When an aggregate of solid particles containing CaO is used and a CO ₂ -containing exhaust gas is brought into contact with the aggregate of the solid particles to fix CO ₂ in the exhaust gas to the solid particles as CaCO ₃ , the exhaust gas is solidified. The solid particles are brought into contact with the solid particles through appropriate moisture contained in the particles, and more preferably by contacting the exhaust gas with water attached to the surface of the solid particles (water film on the surface of the solid particles). Can effectively increase the absorption rate of CO ₂ in exhaust gas. Therefore, it is preferable that the aggregate of the solid particles constituting the filling layer A contains water, and more desirably has surface-adhered water. The water attached to the surface refers to water (water film) other than the water contained inside the particles, that is, water (water film) existing on the outer surface of the solid particles among the water present together with the solid particles. Further, from the same viewpoint, the water content of the aggregate of the solid particles is preferably 3 to 20%. Therefore, in order to ensure the water content of such solid particles and the aggregate thereof, it is preferable to add water to the aggregate of the solid particles in advance as necessary.

When the solid particles have moisture, especially water attached to the surface
If present, CO in exhaust gas₂The reaction between
Ca component eluted (diffused) from body particles into surface-attached water
(Ca ions) and dissolved in the water adhering to the surface from the exhaust gas
It reacts with carbon dioxide gas components,
CO through surface attached water₂Reacts with CO in the exhaust gas.
₂It is particularly effective in efficiently absorbing and fixing the.

That is, according to the initial expectation of the present inventors, CO ₂ in the exhaust gas is reacted with Ca in the solid particles,
In the method of fixing to solid particles as CaCO ₃ ,
As the reaction proceeds, CaCO ₃ precipitates on the entire surface of the solid particles, and the diffusion of Ca ions from the solid particles is prevented. As a result, a high level of CO that can be practically used on an industrial scale is obtained.
₂ It was thought that absorption efficiency could not be expected. But,
Contrary to such expectation, it has been found that CO ₂ can be absorbed with extremely high efficiency by reacting the solid particles with CO ₂ in the presence of water, particularly water adhering to the surface.

The reason for this is not necessarily clear, but the following may be considered. In other words, in the state where water adhered to the surface is present on the surface of the solid particles containing CaO, Ca ions are dissolved from the solid particle side and CO ₂ (carbonate ion) is dissolved from the exhaust gas side in the surface adhered water. It reacts in the water attached to the surface and mainly produces CaC on the surface of the solid particles.
O ₃ precipitates, but during this precipitation, CaCO ₃ precipitation nuclei are not generated uniformly in water, but are generated as heterogeneous nuclei that are likely to be generated on the surface of solid particles.
The precipitation and subsequent growth of ₃ occur only in certain areas of the solid particle surface. As a result, precipitation of CaCO _3, the surface area of the solid particles growth does not occur can be present in substantial proportions, it is possible to maintain the supply of Ca ions into the surface adhesion water from this region (elution), CO ₂ Can be efficiently absorbed and fixed in a short time.

Aggregation of solid particles used in the apparatus of the present invention
The body is composed of CaO and / or Ca (OH)₂
Is an aggregate of solid particles containing: Contained in solid particles
Ca (OH)₂Also, like CaO, CO₂Reacts with
This is CaCO₃Solid particles can be fixed as
Ca (OH)₂May be included. In solid particles
, Ca (OH) contained in₂Is at least solid
It only needs to be included as part of the particle composition,
Therefore, CaO and Ca (OH) as minerals ₂Other
2CaO.SiO₂、 3CaO ・ SiO₂, Glass
Such as those present in solid particles as part of the composition
Is also included.

There is no particular limitation on the kind of such solid particles. However, in particular, the content of CaO (and / or Ca (OH) ₂ ) is high and resources can be recycled. Slag generated in the process,
Concrete (eg, waste concrete) is preferred.
Further, in addition to the slag and concrete, mortar, glass, alumina cement, CaO-containing refractories, MgO-containing refractories, and the like, and one or more of these aggregates of solid particles may be used alone or in combination, or It can be used in combination with slag and / or concrete. These materials are optionally crushed into powder or granules, and used as an aggregate of solid particles.

In general, the slag generated in the steelmaking process has a CaO concentration of about 13 to 55% by weight, and the concrete (eg, waste concrete) has a CaO concentration of about 5 to 55%.
15wt% (CaO concentration in cement: 50-60wt%
%), And since these are very easily available, it can be said that these are extremely suitable materials as solid particles to be a CO ₂ absorbent.

The slag generated in the steelmaking process includes blast furnace slag such as blast furnace slow cooling slag and blast furnace granulated slag, decarburized slag, dephosphorized slag, and desulfurization generated in the steps of pretreatment, converter and casting. Examples include slag, desiliconized slag, steelmaking slag such as cast slag, ore reduction slag, electric furnace slag, and the like, but are not limited thereto, and a mixture of two or more slags is used. You can also. Further, as the concrete, for example, waste concrete generated by demolishing a building or civil engineering structure or the like can be used. Although the particle size of the solid particles is not particularly limited, it is preferable that the particle size be as small as possible in order to secure the contact area with the exhaust gas and enhance the reactivity, and specifically, it is substantially (ie, unavoidably included). A particle size of 5 mm or less, particularly preferably 1 mm or less, is preferred (except for solid particles having a large particle size).

The CO to be processed by the apparatus of the present invention₂Including
Exhaust gas refers to CO emitted from various facilities and equipment.₂To
Gas, which has special restrictions on such exhaust gas sources.
It goes without saying that there is no limit. Relatively CO₂High concentration
The exhaust gas is CaCO ₃Exhaust gas from sintering furnace, hot blast furnace
Gas, boiler exhaust gas, coke oven exhaust gas, sintering furnace exhaust gas
Slab heating furnace exhaust gas, annealing furnace exhaust gas, etc.
You. Also, whether this exhaust gas is a combustion exhaust gas,
Can be used as fuel or not, for example, iron
Generated in the steel manufacturing process and used as fuel gas
So-called by-product gas (eg, blast furnace gas, converter gas, coke
Furnace gas, etc.)₂
Contained in contained exhaust gas.

Further, in order to increase the processing efficiency, it is preferable that the exhaust gas supplied into the reaction tank is pressurized. Although the gas pressure is not particularly limited, the higher the partial pressure of CO ₂ , the higher the dissolution rate of CO _{2 in the} water adhering to the surface of the solid particles. The processing efficiency can be effectively improved as compared with the contact at atmospheric pressure. By increasing the temperature of the exhaust gas to some extent, the reactivity with solid particles increases,
When the temperature of the exhaust gas introduced into the reaction tank exceeds the boiling point of water in the reaction tank, water attached to the solid particles is evaporated, and the reactivity is rather inhibited. For this reason, it is preferable that the exhaust gas temperature be equal to or lower than the boiling point of water in the reaction tank.

For the same reason, it is preferable that the temperature in the reaction vessel is kept below the boiling point of water, and the temperature of the aggregate of solid particles is kept below the boiling point of water in the reaction vessel.
In addition, from the same viewpoint, it is preferable that the concentration of water vapor in the exhaust gas is higher. Therefore, it is preferable that the exhaust gas be passed through water in advance to saturate H ₂ O and then be supplied to the reaction tank. In addition, when the filling rate of the aggregate of solid particles in the reaction tank is small, the chance of contact of the exhaust gas with the solid particles decreases, which affects the processing efficiency. Therefore, the filling rate of the aggregate of solid particles is 40 to 80 volumes. % Or more, preferably 50 to 70% by volume.

[0051]

[Embodiment 1] Length x width x height are each 1m x
A 1 m × 3 m rectangular parallelepiped reaction tank (an exhaust gas introduction section is provided at the bottom of the reaction tank, an exhaust gas discharge section is provided at the top of the reaction tank, and the exhaust gas introduction section is formed below the porous plate provided at the bottom of the reaction tank. An exhaust gas chamber is provided, and an exhaust gas introduction pipe is connected to the exhaust gas chamber, and the perforated plate has a reaction vessel provided with gas holes uniformly on the entire surface thereof. Stairwell improvement measures 1-3
Was used alone or in combination of two or more, and the occurrence of blow-through of the packed bed when each device was used was examined.

Remedy 1: Two eccentric mass vibrators (output 1) are provided outside the side walls of the reaction tank (intermediate position in the tank height direction).
KW), the vibration device was operated from the initial stage of exhaust gas ventilation, and vibration was continuously applied to the side wall of the reaction tank. Remedy 2: 1/5 and 1/1 in the height direction of the inner wall of the reactor
A two-level slope of 0 was assigned. Remedy 3: A 100 mm radius was attached to the four corners of the reaction tank.

Table 1 shows the results of Test Examples 2 to 5 in which the above-mentioned improvement measures 1 to 3 were used alone or in combination of two or more, and Test Example 1 in which the above-mentioned improvement measures were not applied at all. In Test Examples 1 to 5, steelmaking slag having a particle size of 5 mm or less was charged into the reaction tank to form a packed bed, and CO ₂ was discharged from the exhaust gas introduction section by 25% CO ₂ .
%, And the others were supplied with an exhaust gas of approximately N2, and the treatment was carried out for 48 hours. In Tests 1 to 5, the conditions such as the flow rate of exhaust gas to be supplied into the tank and the packing were all the same. The CO ₂ absorption fixed rate in Test Example 1 and Test Example 5 was determined by the chemical analysis method after the test and in the stored slag in the slag before the test.
The O ₂ content (CO ₂ content converted from the amount of CaCO ₃ ) was measured and determined by comparing the two.

According to Table 1, although the results of Test Examples 2 to 5 are somewhat different, the effect of improving the occurrence of blow-through is obtained. Test example 2 in which “Improvement 1” was implemented alone
Test examples 3 and 4 in which "Improvement measure 1" and "Improvement measure 2" are combined have a higher effect of improving the occurrence of blow-through, and test examples in which "Improvement measure 1" to "Improvement measure 3" are combined. 5
Has the highest improvement effect. In Test Example 5, the CO ₂ absorption fixed rate increased by about 20% as compared with Test Example 1.

[0055]

[Table 1]

[Embodiment 2] Each of length × width × height is 1 m
It has a rectangular parallelepiped reaction tank of × 1m × 3m, and
Using a reactor having a structure (Test Examples 1 to 3),
CO in equipment ₂The absorption fixation rate was examined.

Test Example 1: An exhaust gas introduction part was provided at the bottom of the reaction tank, and an exhaust gas discharge part was provided at the top of the reaction tank.
The exhaust gas introduction section was constituted by a perforated plate provided at the bottom of the reaction tank and an exhaust gas chamber formed below the porous plate, and an exhaust gas introduction pipe was connected to the exhaust gas chamber. Gas perforations were provided on the entire surface of the perforated plate at equal intervals. Test Example 2: An exhaust gas introduction section was provided at the top of the reaction tank, and an exhaust gas discharge section was provided at the bottom of the reaction tank. The exhaust gas discharge section was provided at the bottom of the reaction tank with a perforated plate and an exhaust gas chamber formed therebelow. And an exhaust gas discharge pipe was connected to the exhaust gas chamber. Gas perforations were provided on the entire surface of the perforated plate at equal intervals. Test Example 3: Although the basic structure of the device is the same as Test Example 2,
Regarding the perforated plate, gas holes were provided at equal intervals in a portion other than a portion having a width of 120 mm at the outer edge.

In Test Examples 1 to 3, the particle size of 5
A steelmaking slag of not more than 1 mm was charged to form a packed bed, and an exhaust gas consisting of 25% of CO ₂ and the other approximately N ₂ was supplied from an exhaust gas introduction portion, and the treatment was performed for 48 hours. Test example 1
In Nos. 1 to 3, the conditions such as the flow rate of the exhaust gas supplied into the tank and the packing were all the same. The CO ₂ absorption fixed rate was determined by measuring the CO 2 in the slag after the test and before storage by the chemical analysis method.
₂ content (CO ₂ content converted from CaCO ₃ amount)
Was measured, and both were determined. According to these test results, the CO ₂ absorption fixed rate of Test Example 2 was
And the CO ₂ absorption fixed rate of Test Example 3 was increased by about 18% as compared with Test Example 1.

[0059]

According to the apparatus of the present invention described above, Ca
By introducing a CO ₂ -containing exhaust gas into the packed bed of solid particles containing O and Ca (OH) ₂ in the presence of appropriate moisture,
CO ₂ in the exhaust gas can be absorbed and fixed to the solid particles. At that time, gas blow-through in the packed bed can be appropriately prevented, and CO ₂ can be efficiently absorbed and fixed.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing an embodiment of the reaction apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a schematic longitudinal sectional view showing another embodiment of the reaction apparatus of the present invention.

FIG. 4 is an explanatory diagram showing the occurrence of blow-by in a reaction tank.

[Explanation of symbols]

1, 1a, 1b ... reaction tank, 2 ... exhaust gas introduction part, 3 ... exhaust gas discharge part, 4 ... exhaust gas supply pipe, 5 ... exhaust gas discharge pipe, 6 ...
Perforated plate, 7a: exhaust gas chamber, 7b: reaction chamber, 8: corner, 9
... inner wall surface, 10 ... vibration device, 11, 11a, 11b ... reaction tank, 12 ... exhaust gas introduction part, 13 ... exhaust gas discharge part, 14
... exhaust gas supply pipe, 15 ... exhaust gas discharge pipe, 16 ... perforated plate,
17a: Exhaust gas chamber, 17b: Reaction chamber, 60, 160: Gas through hole

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuto Takahashi 1-2-1 Marunouchi, Chiyoda-ku, Tokyo F-term in Nihon Kokan Co., Ltd. 4D002 AA09 BA03 CA07 DA05 DA11 DA12 DA35 FA02 GA03 GB03 GB04 GB20 HA10 4D020 AA03 BA02 BA08 BB03 CB08 CC30 DA03 DB01 4G066 AA14D AA17B BA09 CA35 DA02

Claims (13)

[Claims] 1. A composition comprising CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reactor for absorbing and fixing O ₂ , wherein a vibrator for imparting vibration to a side wall of the reactor is attached to the reactor, and a reactor for absorbing carbon dioxide gas discharged. 2. A composition comprising CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reactor for absorbing and fixing O ₂ , wherein an inner wall surface of the reaction tank is inclined downward to reduce a horizontal cross-sectional area of the inside of the tank. A reactor for the reaction. 3. A composition comprising CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reactor for absorbing and fixing O ₂ , wherein the horizontal cross-sectional shape of the inside of the reaction tank is configured to have a circular shape, an elliptical shape, or a shape in which a corner is a circular arc or an elliptical arc. Reactor for gas absorption reaction. 4. The exhaust gas introduction section of the reaction tank is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate, and an exhaust gas supply pipe is connected to the exhaust gas chamber. 4. The reaction apparatus for an exhaust carbon dioxide absorption reaction according to 1, 2, or 3. 5. A composition comprising CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reaction device for absorbing and fixing O ₂ , wherein an exhaust gas introduction portion is provided at an upper portion of the reaction tank, and an exhaust gas discharge portion is provided at a bottom portion of the reaction tank. Reactor. 6. An exhaust gas discharge part comprises a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the perforated plate,
6. The reaction apparatus for an exhaust carbon dioxide absorption reaction according to claim 5, wherein an exhaust gas discharge pipe is connected to the exhaust gas chamber. 7. The perforated plate has gas holes only in a region except for an outer edge portion near a tank side wall.
The reactor for exhaust carbon dioxide absorption reaction according to 1. 8. A composition comprising CaO and / or Ca
A reaction vessel in which an aggregate of solid particles containing (OH) ₂ is filled in a state containing water; a CO ₂ -containing exhaust gas is introduced into the reaction vessel to allow the solid particles to contain the CO ₂ -containing exhaust gas; C
A reaction apparatus for absorbing and fixing O ₂ , wherein the reaction tank has two or more components selected from the following (a) to (d): For reactors. (a) The reaction tank is provided with a vibration device for applying vibration to the side wall of the tank. (b) The inner wall surface of the reaction tank is inclined downward to reduce the horizontal cross-sectional area inside the reaction tank. (c) The horizontal cross-sectional shape inside the reaction tank is formed into a circular shape, an elliptical shape, or a shape in which a corner is a circular arc or an elliptical arc. (d) An exhaust gas introduction section is provided at the top of the reaction tank, and an exhaust gas discharge section is provided at the bottom of the reaction tank. 9. The reaction apparatus for an exhaust carbon dioxide absorption reaction according to claim 8, wherein the reaction tank has the configuration of (a) to (c). 10. The reaction tank is selected from the group consisting of (a) to (c).
The exhaust gas introduction part of the reaction tank is constituted by a perforated plate provided at the bottom of the tank and an exhaust gas chamber formed below the exhaust gas chamber, and an exhaust gas supply pipe is connected to the exhaust gas chamber. The reaction apparatus for an exhaust carbon dioxide absorption reaction according to claim 8 or 9, wherein: 11. The reactor according to claim 8, wherein the reaction tank has a configuration of (a) to (d). 12. The reaction tank has the configuration of (d) and at least one configuration selected from (a) to (c), and the exhaust gas discharge unit is provided with a perforated plate provided at the bottom of the tank. 12. The reaction apparatus for an exhaust carbon dioxide absorption reaction according to claim 8 or 11, comprising an exhaust gas chamber formed below, and an exhaust gas discharge pipe connected to the exhaust gas chamber. 13. The reactor according to claim 12, wherein the perforated plate has gas holes only in a region except an outer edge portion near the tank side wall.