JPH04354517A - Method and equipment for treating exhaust gas - Google Patents

Abstract

PURPOSE:To continuously and effectively purify exhaust gas containing dust, nitrogen oxide and sulfur oxide and exhaust gas containing dust and hydrogen sulfide. CONSTITUTION:Exhasut gas passes through part of an outer dust removal particle layer 22 rotating and divided small compartments and part of an inner catalyst particle layer 20 divided into small compartments where both dust removal and desulfurization and/or denitration are performed. A dust separation means is installed adjacent to the other part of the particle layer to separate dust caught among particles and a catalyst regeneration gas feed means is installed adjacent to the other part of the particle layer to continuously regenerated catalyst. Dust removal particles are loosely packed and catalyst particles are densely packed.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention is directed to the treatment of dust, nitrogen oxides, etc., such as diesel engine exhaust gas and boiler exhaust gas.
exhaust gas containing NOx) and sulfur oxides (SOx),
Passing exhaust gas (e.g., coal gasification gas) containing dust and sulfur compounds such as hydrogen sulfide (H2S) through a rotating outer dust removal particle bed and an inner catalyst particle bed,
The present invention relates to an exhaust gas treatment method and apparatus that simultaneously and continuously perform dust collection and denitrification, dust collection and desulfurization, or dust collection, denitrification, and desulfurization simultaneously. [0002] Conventionally, as a method for removing dust from diesel engine exhaust gas, filtration and dust collection using a porous filter such as foamed ceramic has been the mainstream method. In this method, when the filter becomes clogged due to the dust trapped inside the filter and the ventilation resistance rises above a certain value, the filter is removed by switching the exhaust gas and incinerating and removing the collected dust. Reproduce. Furthermore, Japanese Patent Application Laid-Open No. 1-159034 discloses that ammonia gas is injected into the flue of diesel engine exhaust gas, and then γ-alumina or anatase titania powder carrying slaked lime and vanadium oxide is injected. Next, a method is described in which a ceramic filter is provided downstream of the exhaust gas to collect powder and combustion dust in the exhaust gas, and the exhaust gas is denitrated by passing through a layer of the collected ash. Also, JP-A-61-11
No. 1128 and No. 111129 disclose an incinerator exhaust gas treatment device containing ash, hydrogen chloride, nitrogen oxides, and sulfur oxides, in which a special reaction aid to prevent clogging is added to the exhaust gas inflow side of a porous ceramic material. A device is described in which a solid layer containing slaked lime or calcium carbonate and calcium chloride is formed via a precoat layer, and a catalyst layer for removing nitrogen oxides is provided on the exhaust gas outlet side. Also, Utsukai Showa 56-
In Japanese Patent No. 126237, exhaust gas is passed through a hollow cylindrical catalyst layer, and dust adhering to the catalyst layer is separated and removed by blowing air from the outside of the catalyst layer using a clean pipe having a nozzle. The equipment is described. [0004] The above-mentioned conventional method using a porous filter has the following problems. (1) The pressure loss of the filter increases continuously as dust accumulates. Although the pressure loss of the filter is recovered by intermittent regeneration, the engine back pressure does not reach a constant value, which adversely affects engine operation. (2) To regenerate the porous filter,
It is necessary to switch the exhaust gas, and it is also necessary to install multiple filters in parallel. (3) When incinerating dust to regenerate a porous filter, if the filter temperature rises too much, the filter may be damaged or the pores of the filter may be crushed as sintering progresses. For this reason, it is necessary to carry catalysts to burn at low temperatures and to perform delicate combustion control. (4) Since the combustion residue of dust remains in the pores, the pressure loss of the filter cannot be completely recovered. (5) Sulfur oxides and nitrogen oxides must be treated separately. Also, Unexamined Patent Publication No. 1-1
The method described in Publication No. 59034 also has the same problems as above. Also, JP-A-61-111128
No. 111129, from incinerator exhaust gas,
Although it is described that nitrogen oxides are removed along with dust, this also uses a porous ceramic filter and has the same problems as above. In addition, in the apparatus described in Japanese Utility Model Application Publication No. 56-126237, the dust separated by blowing air flows into the treated gas, so there is a problem that the treated gas becomes a dust-containing gas. There is. Furthermore, this publication does not describe anything about partitioning the catalyst layer into small sections. The present invention has been made in view of the above-mentioned points, and includes a part of the rotating dust removal particle layer divided into small sections and a part of the catalyst particle layer divided into small sections that contain exhaust gas. to perform desulfurization and/or denitrification at the same time as dust removal, and provide a dust separation means adjacent to another part of the particle layer to separate dust trapped between the particles,
An exhaust gas treatment method and an exhaust gas treatment method capable of continuously and efficiently performing dust collection and denitrification, dust collection and desulfurization, or dust collection, denitrification, and desulfurization at the same time by configuring the separated dust to be extracted separately from the processing gas. The purpose is to provide a device. Means for Solving the Problems In order to achieve the above object, the exhaust gas treatment method of claim 1 includes the following (a) and (b) as shown in FIGS. 1 and 4. The process, i.e. (
a) Part of the inner catalyst particle layer 20, which is a hollow cylinder that rotates continuously or intermittently and is partitioned into small sections, and the outer dust removal particle layer 22, which is partitioned into small sections, from the outside to the inside. Step of passing exhaust gas to collect dust in the exhaust gas and removing nitrogen oxides and/or sulfur oxides in the exhaust gas, (b) inner catalyst particle layer 20
A dust separation gas is continuously or intermittently blown onto a part of the outer dust removing particle layer 22 from the inside to the outside, or continuously or intermittently from outside the outer dust removing particle layer 22. The method is characterized by including a step of separating the dust by suctioning the dust. The method according to claim 2 is the method according to claim 1, as shown in FIG. It is characterized by regenerating the catalyst. [0007] In the above exhaust gas treatment method, at least a part of the catalyst particles are made to have desulfurization activity to remove sulfur oxides as well as dust, or at least part of the catalyst particles are made to have denitrification activity. A reducing agent is added to the exhaust gas to remove nitrogen oxides as well as dust, or at least some of the catalyst particles are particles with desulfurization activity and particles with denitrification activity, and a reducing agent is added to the exhaust gas to remove nitrogen oxides as well as dust. A reducing agent is added to the exhaust gas to remove sulfur oxides and nitrogen oxides as well as dust, or at least some of the catalyst particles have simultaneous desulfurization and denitrification activities, and a reducing agent is added to the exhaust gas. In this way, sulfur oxides and nitrogen oxides can be removed along with dust. Note that ammonia, hydrocarbons, etc. are used as the reducing agent. Furthermore, instead of removing sulfur oxides, hydrogen sulfide may be removed. As shown in FIGS. 1 and 4, the exhaust gas treatment device of claim 8 divides the voids of the three breathable supporting plates 12, 14, and 16 arranged in a concentric cylindrical shape into a large number of small sections. A large number of partition plates 18 provided radially for partitioning, a catalyst particle layer 20 formed by densely filling catalyst particles in each small section of the inner void, and each small section of the outer void. A device main body 10 rotatably houses a dust removal particle layer 22 formed by roughly filling dust removal particles therein, a catalyst particle layer and a dust removal particle layer, and a catalyst particle layer 20 and A rotating means for rotating the dust removal particle layer 22 as one unit, and an exhaust gas inlet 24 provided in the main body of the device.
It is characterized by including a processing gas outlet 26 and a dust separation means provided inside the catalyst particle layer 20 or outside the dust removal particle layer 22. The apparatus according to claim 9 is characterized in that, in the apparatus according to claim 8, catalyst regeneration gas supply means is provided inside the catalyst particle layer 20, as shown in FIG. Furthermore, as shown in FIG. 2, there are cases in which there are four air permeable support plates, two catalyst particle layers, and each layer is made up of catalyst particle layers 48 and 50 filled with different catalyst particles. . In this case, for example, one layer is a catalyst particle layer filled with particles having desulfurization activity, and the other layer is a catalyst particle layer filled with particles having denitrification activity. Furthermore, as shown in FIG.
In some cases, a space 52 for rectifying gas may be formed between the dust removal particle layer 22 and the dust removal particle layer 22. As the dust separation gas, air, an oxygen-containing gas such as treated exhaust gas, or oxygen is used. Also, an inert gas may be used. Further, as the catalyst regeneration gas, steam, high temperature gas (such as combustion gas), air, oxygen, etc. are used. Generally, SOx and NOx in the same exhaust gas
However, the coexistence of H2S and NOx is highly unlikely. Therefore, in this specification, "desulfurization" has two meanings: SOx removal and H2S removal, and "desulfurization" has two meanings: SOx removal and H2S removal.
When we say "simultaneous desulfurization and denitrification," we mean the removal of SOx and NOx, and when we say "simultaneous desulfurization and dedusting," we mean the removal of SOx and NOx.
The term "desulfurization" refers to the removal of SOx or H2S and the removal of dust. [Operation] In FIGS. 1 and 4, the hollow cylindrical dust removal particle layer 22 and the catalyst particle layer 20 rotate together in the direction of arrow A. Exhaust gas is introduced from the outside of the dust removal particle layer 22, and the dust in the exhaust gas is collected, and NOx or/and SOx or H2 in the exhaust gas is
S is removed in the catalyst particle layer 20. The dust removal particle layer 22 that has collected dust is further rotated to continuously or intermittently blow dust separation gas from inside the catalyst particle layer 20, or continuously or from the outside of the dust removal particle layer 22. Dust is separated by targeted or intermittent suction. In addition, when desulfurization is performed, as shown in Figure 1,
Catalyst regeneration gas is supplied from inside the catalyst particle layer 20,
Regenerate the catalyst. Here, by using part or all of the catalyst particles as particles having desulfurization activity, SOx or H2S can be removed at the same time as the dust. In addition, by using part or all of the catalyst particles as particles having denitrification activity,
NOx is also removed at the same time as dust. In addition, by using some or all of the catalyst particles as particles having desulfurization activity and particles having denitration activity, or particles having simultaneous desulfurization and denitration activities, it is possible to simultaneously remove SOx (or H2).
S), NOx is also removed. Note that when denitration is performed, a reducing agent is added to the exhaust gas. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the drawings. However, unless there is a specific description, the shapes of the components described in this embodiment, their relative positions, etc. are not intended to limit the scope of the present invention to these, but are merely illustrative examples. It's nothing more than that. Embodiment 1 In FIG. 1, three breathable support plates 12, 14, and 16 are rotatably housed in a concentric cylindrical shape in an apparatus main body 10. The breathable support plate is made of wire mesh, punched metal,
It consists of a perforated plate. A large number of partition plates 18 are radially provided in the spaces between the breathable support plates to partition the space into a large number of small sections. Each small section of the inner cavity is densely packed with catalyst particles to form a catalyst particle layer 20, and each small section of the outer space is loosely filled with dust removal particles. A dust removal particle layer 22 is formed. That is,
Each particle layer 20, 22 is composed of a breathable support plate, a partition plate, and particles. Catalyst particle layer 20 and dust removal particle layer 2
2 are configured to rotate continuously or intermittently as a unit. Although not shown as this rotation means,
A structure in which a gear, belt groove, or sprocket part is provided at the end of a cylindrical breathable support plate to engage a gear, belt, or chain driven by a motor, or a rotating shaft in the center of the cylindrical breathable support plate. The structure shall be such that a The apparatus main body 10 is provided with an exhaust gas inlet 24 and a processing gas outlet 26. The exhaust gas inlet 24 and the processing gas outlet 26 are provided along the axial direction of the hollow cylindrical dust removal particle layer 22. Further, a dust separation means is provided inside the catalyst particle layer 20 or outside the dust removal particle layer 22. FIG. 1 shows an example in which the dust separation means is provided inside the catalyst particle layer 20. 28 is a gas inlet for dust separation;
30 is a gas flow path for dust separation, and 31 is a partition for forming the flow path 30, which allows gas supplied from the dust separation gas inlet 28 to be passed through a gas flow path provided in the axial direction of the cylindrical catalyst particle layer 20. The dust trapped between the dust removal particles is separated from the particles by passing through the dust separation gas flow path 30 and blowing it from the porous plate 32 on the lower surface of the dust removal particle layer 22 through the catalyst particle layer 20. , and is configured to be discharged from the dust discharge port 34. The gas may be sprayed continuously or intermittently in a pulsed manner. When the exhaust gas contains combustible substances, the dust can also be incinerated by using an oxygen-containing gas such as air or oxygen as the dust separation gas. Further, although not shown, instead of blowing the dust separation gas onto the particle layer, the structure may be such that the gas is sucked from the dust outlet 34 side. Gas suction may be continuous or intermittent (pulsed). Further, catalyst regeneration gas supply means is provided inside a part of the catalyst particle layer 20. For example, as shown in FIG. 1, this catalyst regeneration gas supply means includes a regeneration gas flow path 36, a partition portion 38 for forming this flow path 36, and a regeneration gas inlet 40 connected to the flow path 36. and the flow path 36
The perforated plate 42 is provided in a portion close to the catalyst particle layer. 44 is a regeneration off-gas outlet. The exhaust gas introduced from the exhaust gas inlet 24 is
First, dust is collected in the dust removal particle layer 22, and NOx or/and SOx (or H2S
) is removed, it flows into the catalyst particle layer 20 again as shown by the arrow. In this way, the gas passes through the catalyst particle layer twice, and the second time passes through the regenerated catalyst particle layer, so that the gas is purified with a high degree of purification. Also, at this time,
Since the dust removal particle layer is loosely filled, voids are formed. Therefore, the gas passes through the voids rather than through the particle layer, and the pressure loss does not increase. Further, since the particles for dust removal are loosely packed, the particles move due to the rotation of the particle layer, making it easier to separate the trapped dust. Furthermore, since the catalyst particles are densely packed, there is almost no friction between the particles, so high strength is not required. As the particles for removing dust, ceramic granules such as alumina, mullite, and silica, which are thermally stable and have high strength, are suitable. The particle diameter is preferably about 1 to 5 mm. Furthermore, in the case of SOx removal, it is desirable to use Cu-Al or Cu-Al-Ti particles as the particles having desulfurization activity. In that case, the following reaction proceeds. (Desulfurization reaction) CuO+SO2 +1/2O
2 →CuSO4 (regeneration reaction) CuSO4 →CuO+SO2 +1
/2O2 The desulfurization agent regeneration reaction in the lower stage is a thermal decomposition reaction, and by simultaneously regenerating the desulfurization agent particles and burning the dust collected in the particle layer, the dust combustion heat is used for thermal decomposition, and the carbon The regeneration reaction can be promoted by the reducing effect of . In addition, as particles having denitrification activity, V
Particles carrying 2 O5, WO3, CuO, etc. on the surface, or V2 O5 -TiO2, V2 O
5-WO3-TiO2, CuO-Al2O3
Using the particles of the system, a necessary equivalent amount of a reducing agent such as ammonia is added to the exhaust gas and the mixture is supplied to the particle bed. Further, when desulfurization and denitration are performed simultaneously, the particles having desulfurization activity and the particles having denitration activity are used as a mixture, or they are used as separate particle layers, and a reducing agent is added to the exhaust gas. Furthermore, by filling particles with simultaneous desulfurization and denitrification activities such as V2 O5 type and Cr2 O3 type, and adding the required reaction equivalent amount of reducing agent to the exhaust gas and supplying it to the particle bed, dust removal, desulfurization, and denitrification can be achieved. can be done at the same time. In addition, as a catalyst with denitrification and desulfurization functions, for example, CuO
-Al2O3-TiO2, CuO-SiO2-
TiO2, CuO-Cr2 O3 -TiO2, etc. are known, and among these catalyst components, NOx removal using CuSO4, which is produced in addition to the desulfurization reaction according to the following formula due to the sulfation reaction between CuO and SOx in exhaust gas, is known. A reduction reaction using ammonia is carried out at the same time. SO2 +1/2O2 →SO3 (Catalyst: CuO)S
O3 +CuO→CuSO4 NO+NH3 +1/4O2 →N2 +3/2H2
O (catalyst: CuSO4) NO2 +4/3NH3 →7/6N2 +2H2 O
(Catalyst: CuSO4) The used desulfurization/denitrification agent particles from the above reaction are treated with a reducing agent (
It is regenerated and reused through reduction and oxidation reactions in an air system in the coexistence of NH3, H2, etc.). For example, when using NH3 as a reducing agent, CuSO4 → Cu3 N (NH3 added) Cu3 N
→Regenerated by the reaction of CuO (addition of O2). It is desirable that all of the above particles be made into dense sintered bodies, and in this case, there is an advantage that damage and sintering due to dust combustion heat is difficult to occur, unlike in conventional porous filters. Furthermore, various metal oxides, hydroxides, and the like are used as particles having desulfurization activity for removing hydrogen sulfide. For example, iron oxides such as iron ore,
Copper oxide, dolomite, calcined dolomite, limestone, etc. may be mentioned. The desulfurization reaction and regeneration reaction are as follows when iron oxide is used. (Desulfurization reaction) 3F
e2 O3 +H2 →2Fe3 O4 +H2 O(
Desulfurization reaction) Fe3 O4 +3H2 S+H2 →
3FeS+4H2O (regeneration reaction) 2FeS+7/2O2 →Fe2O
Example 2 As shown in FIG. 2, in this example, a cylindrical air permeable support plate 46 was added to make four air permeable support plates, and two catalyst particle layers were used. The catalyst particle layers 48 and 50 are layers filled with different catalyst particles. In this case, as an example, one layer is a catalyst particle layer filled with particles having desulfurization activity, and the other layer is a catalyst particle layer filled with particles having denitrification activity. Other configurations and operations are the same as in the first embodiment. Example 3 In this example, as shown in FIG. 3, a cylindrical air permeable support plate 46 is added to make the number of air permeable support plates four, and the catalyst particle layer 20 and the dust removal particle layer 22 are A space 52 is formed between the two. This space 52 can provide a gas rectification effect. Other configurations and operations are the same as in the first embodiment. Example 4 In this example, as shown in FIG.
The structure is such that no catalyst regeneration gas supply means is provided. When performing dust removal and denitration, the apparatus of this embodiment is used because catalyst regeneration is not required. Other configurations and operations are the same as in the first embodiment. Furthermore, the fourth embodiment can also be configured as in the second and third embodiments. [0019] Since the present invention is constructed as described above, it produces the following effects. (1) The dust removal particle layer and catalyst particle layer rotate as one,
Exhaust gas purification and dust separation, or exhaust gas purification, dust separation, and catalyst regeneration can be performed simultaneously and continuously. Moreover, there is almost no change in pressure loss. (2) Dust removal and desulfurization, dust removal and denitrification, or dust removal, desulfurization, and denitrification can be performed simultaneously. (3) Since the dust removal particles are loosely packed, the rotation of the cylinder moves the particles, making it easier to separate the trapped dust. (4)
The exhaust gas passes through the dust removal particle layer, the catalyst particle layer, enters the cylinder, passes through the catalyst particle layer (regenerated) again, and becomes the process gas, so a high degree of purification can be obtained. Furthermore, since the processing gas passes through the voids in the particle layer, pressure loss is reduced. (5) Since the catalyst particles are densely packed, there is almost no friction between the particles, so high strength is not required. Incidentally, the particles for removing dust are required to have strength, but particles with high strength can be obtained relatively easily. (6) Since a large number of partition plates are provided, it is possible to fill the dust removal particles roughly, and also has the effect of reinforcing the particle layer. Furthermore, it is possible to prevent the exhaust gas from mixing with the regenerated off-gas containing SO2 and the like.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of an exhaust gas treatment device of the present invention.

FIG. 2 is an explanatory cross-sectional view showing another embodiment of the exhaust gas treatment device of the present invention.

FIG. 3 is an explanatory cross-sectional view showing another embodiment of the exhaust gas treatment device of the present invention.

FIG. 4 is an explanatory cross-sectional view showing still another embodiment of the exhaust gas treatment device of the present invention.

[Explanation of symbols]

10　Device body 12. Breathable support plate 14 Breathable support plate 16 Breathable support plate 18 Partition plate 20 Catalyst particle layer 22 Particle layer for dust removal 24 Exhaust gas inlet 26 Processing gas outlet 48 Catalyst particle layer 50 Catalyst particle layer 52 Space part

Claims (12)

[Claims] [Claim 1] The following steps (a) and (b), namely, (a) an inner catalyst particle layer (20) that is continuously or intermittently rotated and has a hollow cylindrical shape and is divided into small sections; The exhaust gas is passed from the outside to the inside through a part of the outer dust removal particle layer (22) which is partitioned into a part to collect the dust in the exhaust gas and also to remove nitrogen oxides and/or sulfur from the exhaust gas. Step of removing oxides, (b) inner catalyst particle layer (20) and outer dust removal particle layer (22)
), by continuously or intermittently blowing a dust separation gas from the inside to the outside, or by continuously or intermittently suctioning it from the outside of the outer dust removal particle layer (22). An exhaust gas treatment method characterized by including the step of separating. 2. A claim characterized in that the catalyst is regenerated by flowing catalyst regeneration gas from the inside to the outside through a part of the inner catalyst particle layer (20) and the outer dust removal particle layer (22). 1. The exhaust gas treatment method according to 1. 3. The exhaust gas treatment method according to claim 1, wherein at least some of the catalyst particles are particles having desulfurization activity to remove sulfur oxides as well as dust. 4. The exhaust gas according to claim 1, wherein at least some of the catalyst particles are particles having denitrification activity, and a reducing agent is added to the exhaust gas to remove nitrogen oxides as well as dust. Processing method. 5. At least some of the catalyst particles are particles having desulfurization activity and particles having denitrification activity, and a reducing agent is added to the exhaust gas to remove sulfur oxides and nitrogen oxides as well as dust. The exhaust gas treatment method according to claim 1 or 2, characterized in that: 6. At least a part of the catalyst particles are particles having simultaneous desulfurization and denitrification activity, and a reducing agent is added to the exhaust gas to remove dust and sulfur oxides and nitrogen oxides. The exhaust gas treatment method according to claim 1 or 2. 7. The exhaust gas treatment method according to claim 1, wherein hydrogen sulfide is removed instead of removing sulfur oxides. 8. A large number of partitions provided radially to partition the voids of the three air permeable support plates (12), (14), and (16) arranged in a concentric cylindrical shape into a large number of small sections. A plate (18), a catalyst particle layer (20) formed by densely filling catalyst particles in each small section of the inner cavity, and dust removal particles in each small section of the outer cavity. A dust removal particle layer (22) formed by coarsely filling, a device main body (10) that rotatably houses the catalyst particle layer and the dust removal particle layer as one body, and the catalyst particle layer (20) and the dust removal particle layer. A rotating means for rotating the removal particle layer (22) as one unit, an exhaust gas inlet (24) and a processing gas outlet (26) provided in the device body, and the inside of the catalyst particle layer (20) or the dust removal particle layer. (22) Dust separation means provided outside the exhaust gas treatment device. 9. The exhaust gas treatment method according to claim 8, further comprising catalyst regeneration gas supply means provided inside the catalyst particle layer (20). 10. A claim characterized in that the number of breathable support plates is four, the number of catalyst particle layers is two, and each layer is a catalyst particle layer (48), (50) filled with different catalyst particles. Item 8 or 9. The exhaust gas treatment device according to item 8 or 9. 11. The exhaust gas according to claim 10, wherein one layer is a catalyst particle layer filled with particles having desulfurization activity, and the other layer is a catalyst particle layer filled with particles having denitrification activity. Processing equipment. 12. Four air permeable support plates are provided between the catalyst particle layer (20) and the dust removal particle layer (22),
The exhaust gas treatment device according to claim 8 or 9, further comprising a space (52) for rectifying gas.