JP2002058953A - Exhaust gas treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust gas treating device capable of sufficiently reducing the particulate concentration in exhaust gas by preventing releasing of a medium to the outside of fluid layers while suppressing a pressure loss due to clogging at the exhaust gas exist of the fluid layers where the medium such as carbonaceous adsorbent, etc., flows. SOLUTION: The exhaust gas treating device 100 is obtained by forming the fluid layers S1 to S3 for the carbonaceous adsorbent Pf to flow down between the exhaust gas feeding part 18 and an exhaust gas exhausting part 20. The layer S3 and the part 20 are partitioned by an exist porous plate 4 which is flat, has plural circular holes 4a and meets relation expressed by a formula (1) under this; 0.2<=Dp/Da<=0.55...(1) In this formula, Dp shows the minimum diameter of a circular hole 4a and Da shows the average diameter of the carbonaceous adsorbent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment device, and more particularly, to an exhaust gas treatment device for removing components to be removed contained in exhaust gas.

[0002]

2. Description of the Related Art As an exhaust gas treatment apparatus for removing harmful components to be removed such as SOx gas, NOx gas, HCl gas, or organic chlorine compound gas such as dioxins contained in the exhaust gas, for example, the present applicant has disclosed an exhaust gas treatment apparatus. Kaihei 7-
For example, a desulfurization / denitration tower device described in JP-A-136445 or the like can be used. In this conventional apparatus, activated carbon,
A medium such as activated char, activated coke or the like, a carbonaceous adsorbent (material), a catalyst or the like is brought into contact with the exhaust gas, and a medium in which components to be removed in the exhaust gas are adsorbed and held is regenerated in a regeneration tower. Further, the reaction tower has a moving bed defined by an inlet louver, a perforated plate, and an outlet perforated plate or an outlet louver and through which a medium flows, and the exhaust gas passes through the moving bed. Exhaust gas treatment is performed.

[0003]

The perforated plate used in the reaction tower of the conventional exhaust gas treatment apparatus has a pore diameter d.
Is larger than the diameter d ₀ of the activated carbon as the carbonaceous adsorbent. For example, the following equation (2): d = 2 × d ₀ to 4 × d ₀ (2) is satisfied. (See the above publication). Thereby, blockage (clogging) of the perforated plate by activated carbon is prevented, and increase in pressure loss is suppressed. On the other hand, the present inventor has found that when a perforated plate having such a hole diameter is used as the outlet perforated plate, the activated carbon is easily scattered to the outside from the outlet perforated plate, and the concentration of dust in the treated exhaust gas increases. Was found to tend to occur.

Accordingly, the present invention has been made in view of such circumstances, and while sufficiently suppressing an increase in pressure loss due to blockage at an exhaust gas outlet of a moving bed in which a medium such as a carbonaceous adsorbent flows. It is another object of the present invention to provide an exhaust gas treatment apparatus capable of sufficiently preventing the medium from being dissipated outside the moving bed and thereby sufficiently reducing the concentration of dust in the treated exhaust gas.

[0005]

In order to achieve the above-mentioned object, an exhaust gas treatment apparatus according to the present invention is for removing components to be removed contained in exhaust gas, and has a flat shape with an inlet louver. A moving bed formed between an outlet perforated plate having holes, and a medium having an adsorption capacity or a resolution for exhaust gas is supplied, and an exhaust gas supply unit provided in front of the moving bed and supplied with exhaust gas, A reaction tower is provided at the subsequent stage of the moving bed and has an exhaust gas discharge part from which exhaust gas flowing through the moving bed is discharged, and the outlet porous plate has the following formula (1): 0.2 ≦ Dp / Da ≦ 0.55 (1), preferably the following formula (3); 0.25 ≦ Dp / Da ≦ 0.55 (3), particularly preferably the following formula (4); 0.25 ≦ Dp / Da ≦ 0 .4 (4), formed so as to satisfy the relationship represented by Characterized in that the (provided) is intended. Where Dp
Indicates the minimum diameter of the holes in the exit porous plate, and Da indicates the average diameter of the medium.

In the exhaust gas treatment apparatus configured as described above, the exhaust gas supplied to the exhaust gas supply unit flows into the moving bed to which the medium is supplied through the inlet louver. The exhaust gas comes into contact with the medium while flowing through the moving bed, and the components to be removed are removed (sufficiently reduced). The exhaust gas thus treated is discharged to the exhaust gas discharge section through the outlet porous plate.

At this time, if the ratio (Dp / Da) of the minimum diameter of the pores of the exit porous plate to the average diameter of the medium is less than 0.2, the ratio of the diameter of the exit porous plate at the boundary between the moving bed and the exhaust gas discharge portion is reduced. The clogging becomes remarkable, and the pressure loss at the exhaust gas outlet in the moving bed tends to undesirably increase. On the other hand, if Dp / Da exceeds 0.55, there is a possibility that the amount of medium that escapes or leaks from the moving bed to the exhaust gas discharge portion through the outlet porous plate may significantly increase.

It is preferable that the exhaust gas discharging portion has a lower convex portion having an opening formed at the lower end of the outlet porous plate so as to communicate with the moving bed. In this way, a small amount of medium that has escaped or leaked from the moving bed to the exhaust gas discharge portion through the outlet porous plate falls into the lower region of the lower convex portion provided in the exhaust gas discharge portion. The medium that has fallen can be recovered by returning to the moving bed through an opening formed to communicate with the moving bed at the lower end of the outlet perforated plate.

[0009] The "medium" used in the present invention is:
A substance having an adsorption capacity or a resolution with respect to the component to be removed contained in the exhaust gas is shown, and the form is not particularly limited. For example, a plurality of powdery or granular solid particles (specifically, carbon Adsorbent (material) particles, catalyst particles, etc.), and may be an aggregate or an aggregate of those solid particles, and the geometric or three-dimensional shape is not particularly limited. , Spherical, cylindrical, cylindrical, and the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. Note that the same components are denoted by the same reference numerals, and redundant description will be omitted. Unless otherwise specified, the positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawings.

FIG. 1 is a schematic diagram showing a preferred embodiment of an exhaust gas treatment apparatus according to the present invention. The exhaust gas treatment apparatus 100 includes a reaction tower 110 and a regeneration tower 120, and a transfer machine 1 such as a conveyor is provided between the reaction tower 110 and the regeneration tower 120.
31 and 132 are installed. Transfer machines 131, 132
Are arranged such that one end of each is located below and above the reaction tower 110, and the other end is located above and below the regeneration tower 120, respectively. These transfer devices 131 and 132 are for circulating and transferring a carbonaceous adsorbent (material) described later between the reaction tower 110 and the regeneration tower 120. In the reaction tower 110 and the regeneration tower 120, the carbonaceous adsorbent is supplied from the upper end thereof, flows down the inside of each, and is discharged from the lower end to the outside.

The reaction tower 110 has an exhaust gas supply section 18 on the side wall of which the exhaust gas W is supplied and an exhaust gas discharge section 20 for discharging the treated exhaust gas. The exhaust gas W is desulfurized by the carbonaceous adsorbent (SOx gas such as SO ₂ gas) while flowing across the inside of the reaction tower 110.
Gas adsorption), dust removal, and the like are performed, and the exhaust gas is sent from the exhaust gas discharge unit 20 to the stack (chimney) 140 as the treated exhaust gas Ws and exhausted. When reducing nitrogen N such as ammonia is supplied to the reaction tower 110 together with the exhaust gas W, the exhaust gas W can be denitrated (decomposition of NOx components).

[0013] carbonaceous adsorbent having adsorbed the removal components in the exhaust gas W in the regeneration tower 120. is the transferors 131 is sent to the regenerator 120, SO ₂ by heating in the regeneration tower 120.
Components to be removed such as gas are desorbed, or dioxins are decomposed. Thereby, the regeneration of the carbonaceous adsorbent is performed. The gas component desorbed from the carbonaceous adsorbent is discharged from the regeneration tower 120 as a desorbed gas, and is collected in the recovery unit 150 by an absorbent such as an alkali agent. After absorbing the desorbed gas component, the absorbent is neutralized and oxidized and then sent to a recovery system (not shown) using, for example, gypsum or magnesium sulfate.

FIG. 2 is a schematic sectional view (partially omitted) showing the reaction tower 110 in FIG. The reaction tower 110 has a plurality of moving beds S1 to S3 in which a carbonaceous adsorbent Pf (medium) having a predetermined particle size distribution flows between an exhaust gas supply unit 18 and an exhaust gas discharge unit 20. .

An inlet louver 2 in which a plurality of louvers through which the exhaust gas W can flow is provided at the most downstream side in the flow direction of the exhaust gas W in the exhaust gas supply section 18. Also,
An outlet perforated plate 4 having a flat shape and having a plurality of holes is provided on the most upstream side in the exhaust gas discharge unit 20.
That is, the moving bed S <b> 3 and the exhaust gas discharge unit 20 are separated by the outlet porous plate 4. Further, between the inlet louver 2 and the outlet perforated plate 4, perforated plates 6, 8 are provided. As described above, the moving beds S1 to S3 are sequentially defined by the inlet louver 2, the perforated plates 6, 8 and the outlet perforated plate 4 along the flow direction of the exhaust gas W. In addition, as the pore diameter of the perforated plates 6 and 8, the values described in the above-mentioned JP-A-7-136445 can be preferably applied.

The exhaust gas supply section 18 has a projection 18a projecting downward near the moving layer S1. An opening 18b is formed at a lower portion of the protrusion 18a, and the protrusion 18a communicates with the moving layer S1 also at the lower end of the entrance louver 2. Further, the exhaust gas discharging unit 20
It has a convex portion 20a (a downward convex portion) protruding downward near the moving layer S3. An opening 20b is formed below the projection 20a, and the projection 20a is
At the lower end thereof communicates with the moving layer S3.

A hopper (not shown) is connected above the moving beds S1 to S3 via a supply pipe for the carbonaceous adsorbent Pf provided with a seal valve. Further, the lower ends of the moving layers S1 to S3 are formed as hollow discharge sections 11 to 13 each having a wedge-shaped cross section, so that a so-called "single throttle" structure gradually narrowed downward is formed. . These discharge units 11 to 13 have internal spaces communicating with the upper spaces of the moving beds S1 to S3, respectively.
And the carbonaceous adsorbent Pf that has flowed down each of the moving beds S1 to S3 in contact therewith temporarily stays there.

At the lower end of each of the discharge units 11 to 13, a rod-shaped roll feeder 2 connected to a drive unit (not shown) is provided.
Cutting devices such as 1 to 23 are provided rotatably. By the rotation of the roll feeders 21 to 23, the carbonaceous adsorbent Pf retained in the discharge units 11 to 13 is discharged to the outside of the moving beds S1 to S3. Further, the discharge unit 1
A recovery hopper 9 for the carbonaceous adsorbent Pf is provided so as to cover the periphery of 1 to 13. A collecting pipe for the carbonaceous adsorbent Pf having an open / close valve is connected to a lower end of the collecting hopper 9.

FIG. 3 is a perspective view (partially omitted) showing the outlet porous plate 4 in FIG. The outlet porous plate 4 is formed by forming a plurality of circular holes 4a (holes) in a plate-like member, and has a substantially flat shape with almost no projections or protrusions on the plate surface.
In addition, the outlet porous plate 4 has the following formula (1): 0.2 ≦ Dp / Da ≦ 0.55 (1), preferably the following formula (3): 0.25 ≦ Dp / Da ≦ 0.55 .. (3), particularly preferably the following formula (4): 0.25 ≦ Dp / Da ≦ 0.4 (4). Here, in the formula, Dp indicates the minimum diameter of the circular hole 4a, and Da indicates the average diameter of the carbonaceous adsorbent Pf used.

Specifically, the carbonaceous adsorbent Pf has a particle size of 1
If it has a particle size distribution of 9 mm and its average diameter is about 7.5 mm, the diameter of the circular hole 4a is 1.5 to 4.1 mm, preferably 1.9 to 4.1 mm, particularly preferably 1.9. ~ 3m
m. Alternatively, the carbonaceous adsorbent Pf has a particle size of 1 to 5 m.
m with a particle size distribution of about 4 mm,
The diameter of the circular hole 4a is 0.8 to 2.2 mm, preferably 1 to
It is 2.2 mm, particularly preferably 1 to 1.6 mm.
In addition, the particle size when the carbonaceous adsorbent is in the shape of a column indicates the outer diameter of the cross section of the column.

The aperture ratio of the entire exit porous plate 4 is not particularly limited, and is preferably as large as possible from the viewpoint of reducing the pressure loss in the exit porous plate 4 described later. It can be set appropriately in consideration of the mechanical strength and the like of the exit porous plate. As a specific aperture ratio, for example, a value of 50% or more can be exemplified.

The exhaust gas treatment apparatus 10 constructed as described above
0, the exhaust gas W supplied to the exhaust gas supply section 18 of the reaction tower 110 passes through the inlet louver 2 and the carbonaceous adsorbent P
f flows into the moving bed S1 flowing down. The exhaust gas W
Is the carbonaceous adsorbent Pf while flowing through the moving beds S1 to S3.
And the component to be removed is removed. The exhaust gas W thus treated is discharged to the exhaust gas discharge section 20 through the outlet porous plate 4.

Here, the present inventor changes the hole diameter (minimum diameter) Dp of the circular hole 4a provided in the outlet porous plate 4 variously, and actually measures the pressure difference between the exhaust gas supply unit 18 and the exhaust gas discharge unit 20. The pressure loss at the boundary between the moving bed S3 and the exhaust gas discharge unit 20, that is, at the outlet porous plate 4, was evaluated. At this time, the exhaust gas discharge unit 20 is passed through the outlet porous plate 4.
The amount (weight) of the carbonaceous adsorbent Pf dissipated into the carbon material was measured.
The carbonaceous adsorbent Pf has (1) a particle size distribution of 1 to 9 mm, an average particle size Da of about 7.5 mm, and (2) 1
Two types having a particle size distribution of about 5 mm and an average particle diameter Da of about 4 mm were used. Further, the aperture ratio of the outlet porous plate 4 was kept constant at approximately 50%.

FIG. 4 shows the result.
Loss and carbonaceous adsorbent Pf with respect to the value of the ratio
6 is a graph showing a change in the amount of dissipation of the radiated light. In the figure, curve L1,
L2 indicates the results of the pressure loss and the amount of dissipation, respectively. The straight line Lav indicates the effective average range of the Dp / Da ratio based on the result of comparison between the pressure loss and the amount of dissipation.

As shown in the figure, the ratio (Dp / Da) of the minimum diameter Dp of the circular hole 4a of the outlet porous plate 4 to the average diameter Da of the carbonaceous adsorbent Pf is equal to the lower limit of the equation (1), that is, 0.2. If it is less than 3, the obstruction in the outlet porous plate 4 which is the boundary between the moving bed and the exhaust gas discharge portion becomes remarkable, and the pressure loss at the exhaust gas outlet in the moving bed S3 tends to increase unfavorably. On the other hand, when Dp / Da exceeds the upper limit of the expression (1), that is, 0.55, the carbonaceous adsorbent Pf that escapes or leaks from the moving bed S3 to the exhaust gas discharge unit 20 through the outlet porous plate 4 significantly. It may increase.

Here, the detailed reason why such a tendency occurs when the value deviates from the range of the equation (1) is not yet clear, but it is probably probabilistic that the carbonaceous adsorbent Pf has a particle size distribution. The effect is presumed to be one of the factors.

Generally, when a medium having a particle size distribution falls freely, it accumulates or accumulates so as to form a free surface having a repose angle depending on the particle size distribution, material, shape, and the like. At this time, those having a large particle size tend to gather at the peripheral portion, while those having a small particle size tend to gather at the central portion. Therefore, FIG.
As shown in Fig. 7, the carbonaceous adsorbent Pf having a particle size distribution supplied above the moving layers S1 to S3 forms a so-called pile that is deposited in a mountain shape. The carbonaceous adsorbent Pf flowing down the moving bed S1 near the entrance louver and the moving bed S3 near the outlet porous plate 4 tends to have a larger particle size than that flowing down other parts. Such uneven distribution of the grain size is also considered to be one of the factors or triggers that cause the significant tendency described above when the value is out of the range of Expression (1).

Therefore, the exhaust gas treatment apparatus 10 according to the present invention
At 0, the ratio (Dp / Da) of the minimum diameter Dp of the circular hole 4a of the outlet porous plate 4 to the average diameter Da of the carbonaceous adsorbent Pf is set to a value within the range represented by the formula (1). , Exit perforated plate 4 which is a boundary between moving bed S3 and exhaust gas discharge section 20
Can be prevented from being blocked. Therefore, an increase in pressure loss due to blockage at the exhaust gas outlets of the moving beds S1 to S3 in which the carbonaceous adsorbent Pf flows down can be sufficiently prevented. In addition, the amount of the carbonaceous adsorbent Pf that escapes or leaks from the moving bed S3 to the exhaust gas discharge section 20 through the outlet porous plate 4 can be sufficiently reduced. As a result, the dust concentration in the treated exhaust gas W can be sufficiently reduced.

The exhaust gas discharge section 20 is provided with the outlet porous plate 4.
Has a projection 20a having an opening 20b formed at the lower end thereof so as to communicate with the moving bed S3, so that a small amount of the gas that escapes or leaks from the moving bed S3 to the exhaust gas discharge section 20 through the outlet porous plate 4 is formed. The carbonaceous adsorbent Pf is collected in a region below the protrusion 20a. This carbonaceous adsorbent P
f is returned to the moving bed S3 through the opening 20b and collected, merges with the carbonaceous adsorbent Pf flowing down the moving bed S3, and is discharged from the discharge unit 13. Therefore, since a small amount of the carbonaceous adsorbent Pf scattered or leaked from the moving bed S3 to the exhaust gas discharge portion 20 through the outlet porous plate 4 is not discharged together with the exhaust gas W, the concentration of dust in the treated exhaust gas W is further reduced. it can.

Further, since the circular hole 4a provided in the outlet porous plate 4 has a circular cross section and does not have a top such as a square hole, it is smaller than a case where a hole having a top such as a square hole is provided. And it is difficult for cracks and the like to enter. Accordingly, there is an advantage that the strength retention of the outlet porous plate 4 can be improved.

In the above-described embodiment, the cross-sectional shape of the circular hole 4a provided in the outlet porous plate 4 is not limited to a perfect round or a substantially perfect circle, but may be, for example, an ellipse. It may be a hole. In addition, the exhaust gas treatment device 1
The particle size of the medium such as the carbonaceous adsorbent Pf used in 00 is
The thickness is not limited to 1 to 9 mm and 1 to 5 mm.

[0032]

As described above, according to the exhaust gas treatment apparatus of the present invention, the ratio (Dp / Da) of the minimum diameter of the holes of the outlet porous plate to the average diameter of the medium such as the carbonaceous adsorbent is 0.1. 2
Since it is set to a value within the range of 0.55, an increase in pressure loss due to blockage at the exhaust gas outlet of the moving bed through which the medium flows can be sufficiently suppressed. In addition, it is possible to sufficiently prevent the medium from being dissipated outside the moving bed, whereby the concentration of dust in the treated exhaust gas can be sufficiently reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a preferred embodiment of an exhaust gas treatment apparatus according to the present invention.

FIG. 2 is a schematic cross-sectional view (partially omitted) showing the reaction tower in FIG.

FIG. 3 is a perspective view (partially omitted) showing an outlet perforated plate in FIG. 2;

FIG. 4 is a graph showing a change in pressure loss and a dissipation amount of a carbonaceous adsorbent with respect to a value of a ratio of Dp / Da.

[Explanation of symbols]

2 ... Inlet louver, 4a ... Circular hole (hole), 4 ... Outlet perforated plate, 18 ... Exhaust gas supply unit, 20 ... Exhaust gas discharge unit, 20a
... convex part (lower convex part), 20b ... opening part, 100 ... exhaust gas treatment device, 110 ... reaction tower, Dp ... pore size, Pf ... carbonaceous adsorbent (medium), S1, S2, S3 ... moving bed, W ... Exhaust gas.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 53/70 B01J 8/12 331

Claims (2)

[Claims] 1. An exhaust gas treatment device for removing components to be removed contained in exhaust gas, which is formed between an inlet louver and an outlet porous plate having a flat shape and a plurality of holes, and adsorbing the exhaust gas. A moving layer to which a medium having a resolution or a resolution is supplied; an exhaust gas supply unit provided before the moving layer, to which the exhaust gas is supplied; An exhaust gas discharge section from which exhaust gas is discharged, wherein the outlet porous plate has the following formula (1); 0.2 ≦ Dp / Da ≦ 0.55 (1), Dp: the outlet An exhaust gas treatment apparatus characterized by being formed so as to satisfy a relationship represented by a minimum diameter of a hole provided in a perforated plate, and Da: an average diameter of the medium. 2. The exhaust gas discharge section according to claim 1, wherein the exhaust gas discharge section has a lower convex portion having an opening formed at a lower end portion of the outlet porous plate so as to communicate with the moving layer. Exhaust gas treatment equipment.