JPH076379B2 - Exhaust gas purification device for diesel engine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention continuously removes dust, dust and nitrogen oxides (NOx), dust and sulfur oxides (SOx), or dust, nitrogen oxides and sulfur oxides in diesel engine exhaust gas. The present invention relates to an exhaust gas purifying device for a diesel engine that removes it efficiently.

[0002]

2. Description of the Related Art Hitherto, as a method for removing dust from exhaust gas of a diesel engine, filtration and dust collection using a porous filter such as foam ceramic has been the mainstream. In this method, when the filter is clogged due to the dust collected in the filter and the ventilation resistance becomes higher than a certain value, the exhaust gas is switched to incinerate and remove the collected dust. Reproduce.

Further, in Japanese Patent Laid-Open No. 1-159034, an ammonia gas is injected into a flue of exhaust gas of a diesel engine, and then a powder of γ-alumina or anatase type titania carrying slaked lime and vanadium oxide is injected. Then, a method is described in which a ceramics filter is provided downstream of the exhaust gas to collect powder and combustion dust in the exhaust gas, and to denitrate the exhaust gas so that the exhaust gas passes through the layer. In addition, JP-A-55-7
Japanese Patent No. 2623 describes a diesel exhaust gas cleaning device in which a denitration device, a wet electrostatic precipitator, and a wet desulfurization device are arranged in series.

It has been well known in the prior art to use a dry denitration device to reduce NOx emissions in exhaust gas from diesel engines. This conventional denitration device is usually
Although it is installed after the supercharger, the exhaust gas temperature after leaving the supercharger may be 300 ° C or lower, which is considerably lower than the inlet temperature of the supercharger. However, in order to perform denitration efficiently, a temperature of 300 ° C. or higher is required. Therefore, the exhaust gas temperature is raised to a predetermined temperature by heating with an afterburner or the like. As a method that does not require an afterburner or the like, JP-A-58-5930.
As disclosed in Japanese Patent Publication No. 7, an exhaust denitration device has been proposed in which a denitration device is provided between an exhaust collecting pipe of a diesel engine and a supercharger turbine.

[0005]

The conventional method using the porous filter has the following problems. (1) The pressure loss of the filter continuously increases with dust accumulation. The pressure loss of the filter is recovered by the intermittent regeneration, but the engine back pressure does not become a constant value, which adversely affects the operation of the engine. (2) In order to regenerate the porous filter, it is necessary to switch the exhaust gas, and it is necessary to install a plurality of filters in parallel. (3) When dust is incinerated to regenerate the porous filter, the filter may be damaged if the filter temperature rises excessively, or the pores of the filter may collapse due to the progress of sintering. Therefore, it is necessary to carry a catalyst for burning at a low temperature and perform delicate combustion control. (4) The pressure loss of the filter is not completely recovered because the dust burning portion remains in the pores. (5) Sulfur oxides and nitrogen oxides need to be treated separately. Also, the method described in Japanese Patent Laid-Open No. 1-159034 has the same problem as above.

Further, in the device described in Japanese Patent Laid-Open No. 55-72623, the denitration device, the dust collector, and the desulfurization device are separate devices, and the afterburner is used for heating. Therefore, it occupies a large space in terms of space and the number of devices constituting the system increases. Further, in the system described in Japanese Patent Laid-Open No. 58-59307, a denitration device is separately installed, so that a space for installation is required. Further, this publication does not mention anything about simultaneous denitration and dedusting, and continuous regeneration of used particles. The present invention has been made in view of the above points, and in the case of denitration by installing a purification device that rotatably accommodates a particle packed layer in the exhaust gas collecting pipe between the engine exhaust outlet and the supercharger. Can effectively perform dedusting, dedusting and denitration, or dedusting and denitration and desulfurization without needing a heating means such as an afterburner, and also can regenerate particles at the same time. An object of the present invention is to provide an exhaust gas purifying apparatus for a diesel engine that can be used.

[0007]

In order to achieve the above-mentioned object, an exhaust gas purifying apparatus for a diesel engine according to claim 1,
As shown in FIG. 1 and FIG. 2, the two porous supports 16, 16 provided in the exhaust collecting pipe 14 between the exhaust pipe 26 of the diesel engine and the supercharger 12 are rotated to be opposed to each other. A disk-shaped body 18 formed as possible, a particle-packed layer 20 formed by packing particles in the disk-shaped body 18, and a regeneration gas conduit 22 provided in the vicinity of the particle-packed layer 20. , Is included. In addition, as shown in FIGS. 3 and 4, the purifying apparatus according to claim 2 includes a porous support 16 provided in the exhaust collecting pipe 14 between the exhaust conduit 26 of the diesel engine and the supercharger 12. Rotating outer cylinder 30 and rotating inner cylinder 32 consisting of the porous support 16, and rotating outer cylinder 3
0 and the rotating inner cylinder 32, a particle packing layer 34 formed by packing particles, and a regeneration gas conduit 22 provided in the vicinity of the particle packing layer 34 are included. There is.

Further, in order to add a reducing agent to the exhaust gas, at least a part of the particles is made to have a denitration activity,
A reducing agent conduit 28 is connected to the exhaust conduit 26 so as to remove the nitrogen oxides along with the removal of dust, or at least a part of the particles is made into particles having a desulfurization activity to remove the sulfur oxides together with the removal of dust. Alternatively, at least a part of the particles is made into particles having desulfurization activity and particles having denitration activity, and a reducing agent conduit 28 is connected to the exhaust conduit 26 to add a reducing agent to the exhaust gas to remove dust. At the same time, sulfur oxides and nitrogen oxides are removed, or at least a part of the particles is made into particles having simultaneous desulfurization / denitration activity, and a reducing agent conduit 28 is added to the exhaust conduit 26 in order to add a reducing agent to the exhaust gas. Can be connected so that sulfur oxides and nitrogen oxides are removed together with the removal of dust. As the reducing agent, ammonia, hydrocarbon or the like is used.

[0009]

The particle packed bed 20 rotates continuously or intermittently,
Engine exhaust gas is introduced into the rotating particle packed bed,
Dust in the exhaust gas is collected. The particle-packed bed in which the dust is collected is further rotated, and a regenerated gas, which is an oxygen-containing gas such as air, oxygen, and treated exhaust gas, is introduced, and the collected dust is burned and regenerated. In addition, when dust does not burn only by introducing the oxygen-containing gas, the oxygen-containing gas and the fuel are simultaneously introduced. Here, by making a part or all of the particles into particles having a denitration activity, NOx is removed at the same time as the dust. Further, by making a part or all of the particles into particles having a desulfurization activity, SOx is removed at the same time as dust. Further, SOx and NOx are removed at the same time as dust by making a part or all of the particles into particles having desulfurization activity and particles having denitration activity, or particles having simultaneous desulfurization / denitration activity. When performing denitration, a reducing agent is added to the exhaust gas.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, the shape of the constituent devices described in this embodiment, the relative arrangement thereof, and the like, unless otherwise specified, are not intended to limit the scope of the present invention only to them, but merely illustrative examples. Nothing more. Embodiment 1 In FIGS. 1 and 2, 10 is a diesel engine, 1
2 is a supercharger, and 14 is an exhaust collecting pipe. Reference numeral 16 denotes a porous support, which is composed of a wire mesh, punching metal, a porous plate, and the like. Disk-shaped body 1 in which two porous supports 16 and 16 are provided in pairs.
8 is formed, and the disc-shaped body 18 is rotatably housed in the exhaust collecting pipe 14. Particles are packed in the disk-shaped body 18 to form a particle packing layer 20. A regeneration gas conduit 22 is provided near the particle packed bed 20. 24
Is a rotating shaft and is connected to a drive source (not shown). Two
Reference numeral 6 is an exhaust conduit, and 28 is a reducing agent conduit. The reducing agent conduit 28 is used only when performing denitration. The particle packing layer 20 is usually provided only in two layers in the central portion before the inlet of the supercharger 12. In this case, the pressure loss with respect to each engine back pressure becomes the same, so that there is no variation in engine back pressure. However, as shown by the chain double-dashed line in FIG. 1, when further purifying the exhaust gas, three or more particle-packed layers may be provided.

For the purpose of collecting dust only, generally, thermally stable ceramic granules such as alumina, mullite and silica are suitable as particles. Particle diameter is 1-5
mm is preferable. In addition, when dust collection and denitration are performed simultaneously, V ₂ O ₅ -TiO ₂ , V ₂ O ₅ -WO ₃ -TiO
It is desirable to use particles such as ₂ , CuO-Al ₂ O ₃ . In this case, the reducing agent is added to the exhaust gas in the required reaction equivalent amount. When performing dust collection and desulfurization at the same time, C
It is desirable to use u-Al or Cu-Al-Ti based particles. In that case, the following reaction proceeds. (Desulfurization reaction) CuO + SO ₂ + 1 / 2O ₂ → CuSO ₄ (regeneration reaction) CuSO ₄ → CuO + SO ₂ + 1 / 2O _{2 The} lower desulfurization agent regeneration reaction is a thermal decomposition reaction, and the desulfurization agent particles are regenerated and trapped in the particle packed bed. By performing the combustion of the collected dust at the same time, the heat of dust combustion can be utilized for thermal decomposition and the regeneration reaction can be promoted by the reducing effect of carbon. Furthermore, when desulfurization and denitration are performed simultaneously in addition to dust collection, in addition to the above desulfurizing agent, V
Particles having ₂ O ₅ , WO ₃ , CuO or the like supported on the surface, or V ₂ O ₅ -TiO ₂ , V ₂ O ₅ -WO ₃ -TiO ₂ , C
DeNOx catalyst particles such as uO-Al ₂ O ₃ are mixed, a reducing agent is added to the exhaust gas in the required reaction equivalent amount, and the particles are supplied to the particle packed bed. In addition, by using particles having simultaneous desulfurization / denitration activity such as V ₂ O ₅ system and Cr ₂ O ₃ system, the reducing agent is added to the exhaust gas in the required reaction equivalent amount and supplied to the particle packed bed, the same as above. , It is possible to perform denitration simultaneously with desulfurization on dust collection. It is desirable that all of the above-mentioned particles be a dense sintered body, and in this case, there is an advantage that breakage / sintering due to dust combustion heat is unlikely to occur unlike the conventional porous filter.

Embodiment 2 In this embodiment, the rotary outer cylinder 30 made of the porous support 16 and the rotary inner cylinder 32 made of the porous support 16 are connected to the exhaust collecting pipe 14.
The particles are concentrically provided inside, and the space between the rotating outer cylinder 30 and the rotating inner cylinder 32 is filled with particles to form a particle packed layer 34, and the regeneration gas conduit 22 is provided close to the particle packed layer 34. It is provided. Reference numeral 36 is a regeneration gas ejection pipe, and 38 is a bearing. Other configurations and operations are similar to those of the first embodiment.

[0013]

Since the present invention is configured as described above, it has the following effects. (1) Both the engine exhaust gas purification and the particle regeneration can be continuously performed by one rotating particle packed bed. Moreover, since the particle-filled layer is rotating, clogging can be prevented. (2) Since the purifying device is housed and installed in the exhaust collecting pipe, the entire device can be downsized, and when performing denitration simultaneously with dedusting, it is not necessary to heat the exhaust gas. (3) Since the purification device is installed on the upstream side of the supercharger,
It is possible to prevent the supercharger from being contaminated by dust. (4) When the denitration agent particles are used as a part or all of the particles, dust and NOx in the exhaust gas can be simultaneously removed by adding a small amount of the reducing agent to the exhaust gas. (5) When the desulfurizing agent particles are used as a part or all of the particles, the dust and SOx in the exhaust gas can be removed at the same time. (6) When desulfurizing agent particles and particles having a denitrification activity are used as a part or all of the particles, dust and SOx in the exhaust gas can be added by adding a small amount of a reducing agent to the exhaust gas.
And NOx can be removed at the same time. (7) When using particles having simultaneous desulfurization / denitration activity as part or all of the particles, dust, SOx and NOx in the exhaust gas can be removed simultaneously by adding a small amount of a reducing agent to the exhaust gas. it can.

[Brief description of drawings]

FIG. 1 is an explanatory plan view showing an embodiment of an exhaust gas purifying apparatus for a diesel engine of the present invention. Although the supercharger is usually located above the exhaust collecting pipe as shown in FIG. 2, it is drawn so as to be located on the side of the exhaust collecting pipe for ease of explanation.

FIG. 2 is a side sectional view of the device shown in FIG.

FIG. 3 is an explanatory plan view showing another embodiment of the device of the present invention.

FIG. 4 is a side sectional view of the device shown in FIG.

[Explanation of symbols]

 10 Diesel Engine 12 Supercharger 14 Exhaust Collecting Pipe 16 Porous Support 18 Discoid 20 Particle Packing Layer 22 Regenerating Gas Pipe 24 Rotating Shaft 26 Exhaust Pipe 28 Reducing Agent Pipe 30 Rotating Outer Cylinder 32 Rotating Inner Cylinder 34 Particle Packing Bed

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliography Sho 63-170510 (JP, U) Rikai Hei 3-38126 (JP, U) Rikai Hei 3-52321 (JP, U) Rikai Sho 56- 11316 (JP, U) Actually open Sho 51-122209 (JP, U)

Claims (6)

[Claims] 1. Two porous supports (16), (16) provided in an exhaust collecting pipe (14) between an exhaust pipe (26) of a diesel engine and a supercharger (12). A disk-shaped body (18) formed oppositely and rotatably, and a particle-filled layer (2) formed by packing particles into the disk-shaped body (18).
0) and a regeneration gas conduit (22) provided in the vicinity of the particle packed bed (20), an exhaust gas purification apparatus for a diesel engine. 2. A rotating outer cylinder (30) comprising a porous support (16) provided in an exhaust collecting pipe (14) between an exhaust pipe (26) of a diesel engine and a supercharger (12). And a rotating inner cylinder (32) composed of the porous support (16), and a particle packing layer (34) formed by packing particles between the rotating outer cylinder (30) and the rotating inner cylinder (32), Regeneration gas conduit (22) provided close to the particle packed bed (34)
An exhaust gas purifying apparatus for a diesel engine, which includes: 3. At least a part of the particles are particles having denitration activity, and a reducing agent conduit (28) is connected to the exhaust conduit (26) to remove dust and nitrogen oxides. An exhaust gas purifying apparatus for a diesel engine according to claim 1 or 2. 4. The exhaust gas purifying apparatus for a diesel engine according to claim 1, wherein at least a part of the particles are particles having a desulfurization activity, and sulfur oxides are removed together with the removal of dust. 5. An exhaust pipe (2) comprising at least a part of the particles which are particles having desulfurization activity and particles having denitration activity.
The exhaust gas purifying apparatus for a diesel engine according to claim 1 or 2, wherein a reducing agent conduit (28) is connected to 6) to remove dusts such as sulfur oxides and nitrogen oxides. 6. At least a part of the particles are particles having simultaneous desulfurization / denitration activity, and a reducing agent conduit (28) is connected to the exhaust conduit (26) to remove dust and sulfur oxides and nitrogen oxides. The exhaust gas purifying apparatus for a diesel engine according to claim 1 or 2, wherein the exhaust gas purifying apparatus is removed.