JPH0754632A - Exhaust gas processing method - Google Patents

Abstract

PURPOSE:To enable minute particles to be disposed by a secondary collecting means after transferring minute particles included in exhaust gas to be discharged from an internal combustion engine to the secondary collecting means in the position separated from a primary collecting means. CONSTITUTION:Minute particles in exhaust gas is collected by a primary filters 2, 4, when switching valves 18, 20 are opened and also when switching valves 19, 21 are closed. Collected minute particles are disposed by a processing device 26 in the separated position through pipings 10, 12. In the case of reverse cleaning, for example, air is supplied from a primary pulse air supplying part 14 in the reverse direction to the exhaust gas flow direction of a primary filter 2 by closing the switching valve 18 and opening the switching valve 19, thereby collected minute particles on the primary filter 2 are blown away and supplied together with pulse air into a secondary filter 6 of the processing device 26 through the check valve 19 and the piping 10. Thus, minute particles are collected by the secondary filter 6. Minute particles collected by the secondary filter 6 are dropped into a container 27 by secondary air pulse, and burnt by a heater 50, and discharged as combustion gas from the air bleeder switching valve 60 to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas processing method and apparatus for capturing and processing fine particles containing carbon as a main component in exhaust gas discharged from an engine such as a diesel engine.

[0002]

2. Description of the Related Art Exhaust gas from a diesel engine causes pollution because it contains a high concentration of fine particles containing carbon as a main component. A method of capturing or removing such fine particles in exhaust gas by using a filter has been proposed. For example, Japanese Patent Laid-Open No. 1-1594
In the '08 publication, the carbonaceous fine particles captured by the filter body are separated from the filter body by a backwash airflow that is intermittently flowed in the opposite direction, and the separated fine particles are collected by a recollection unit provided below the filter. A method of burning is disclosed.

[0003]

However, according to this conventional method, since the recollection part is provided at the lower position of the filter or in the exhaust gas passage near the filter,
There is a fear that the fine particles separated by the backwash airflow will not be collected by the recollection unit and will be blown back to the filter body. The present invention is
In order to solve such a problem, the collected fine particles are transferred from the primary collecting means for collecting the fine particles contained in the exhaust gas to the secondary collecting means at a remote position. It is an object of the present invention to provide an exhaust gas treatment method and device which are treated and discharged by a secondary collection means.

[0004]

[Means for Solving the Problems]

(First invention) The present invention for solving the above-mentioned problems. An exhaust gas treatment method according to the first invention is an exhaust gas treatment method for collecting and treating fine particles in exhaust gas discharged from an internal combustion engine. First to collect fine particles in exhaust gas
And a second step of stopping the exhaust gas flow, causing the collected fine particles to flow in the reverse direction of the exhaust gas flow direction and conveying the fine particles to a remote position outside the exhaust system, and burning and treating the fine particles at the remote position. And a third step of discharging to the outside.

In this exhaust gas treatment method, when the internal combustion engine is operating, the second step and the third step can be carried out at regular or irregular intervals. (Second invention) Present invention An exhaust gas treatment method according to the second invention is an exhaust gas treatment method for collecting and treating fine particles in exhaust gas discharged from an internal combustion engine, wherein the exhaust gas is circulated through a filter. A collection step of collecting the fine particles, a regeneration step of removing air by flowing air in the filter in a direction opposite to the exhaust gas flow direction, and removing the collected fine particles of the filter, and the collected fine particles to a remote position outside the exhaust system. The present invention is characterized by comprising a transfer step of transporting by the pressure of the air and a processing step of burning and processing the particles at the remote position and discharging the particles to the outside.

(Third Invention) The present invention is an exhaust gas treatment apparatus for collecting and treating fine particles in exhaust gas discharged from an internal combustion engine, which is an exhaust gas treatment apparatus in which exhaust gas is circulated in the exhaust gas. A filter for collecting fine particles, a processing device for burning and processing the collected fine particles, an on-off valve provided on the exhaust gas inlet side of the filter, and one end connected to the inlet side of the on-off valve, A pipe whose other end is connected to the processing device, and when this on-off valve is closed, air is supplied in the reverse flow direction of the filter, and the fine particles are passed through the on-off valve and the pipe to the processing device. And an air supply means for supplying.

In the processing apparatus constituting the third invention, for example, a secondary filter for collecting fine particles in the primary pulse air, and a secondary filter in the secondary filter in the primary pulse air flow direction and the secondary flow direction are provided. Secondary pulse air supply means for flowing pulsed air to remove the collected particulates of the secondary filter, a container for containing the collected particulates removed from the secondary filter, and a container provided in this container for burning the collected particulates And a heating means for heating.

[0008]

[Operation] The exhaust gas emitted from the diesel engine
The primary collecting means, for example, enters the hole of the primary filter, passes through the porous wall defining the hole, and is discharged to the outside from the primary filter. At this time, the fine particles in the exhaust gas are collected on the inlet side of the porous wall body, and the amount of the fine particles deposited increases as the flow rate of the exhaust gas increases.

Then, the flow of the exhaust gas is stopped, and air, for example, pulsed air is supplied to the primary filter in the direction opposite to the flow direction of the exhaust gas up to that point. Then, the accumulated particulates up to that point are blown off toward the exhaust gas inlet side of the primary filter, and are further collected through the pipe to the secondary collection means, for example, the secondary filter. Then, the fine particles collected by this secondary filter are processed and discharged to the outside.

According to this exhaust gas treatment method, the fine particles collected by the primary filter are located at a remote position through the pipe.
1 because it is configured to be processed after being collected by the next filter
Since the particles collected by the secondary filter are reliably transferred to the remote position and processed at this remote position, the particles in the remote position are prevented from blowing back to the primary filter. This allows
The fine particle collecting function and the regenerating function of the primary filter are synergistically greatly improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. An exhaust gas treating apparatus according to the first embodiment of the present invention is shown in FIGS. As shown in FIG. 1, the exhaust gas treatment system 1 includes a primary filter 2, 4, a secondary filter 6,
Pipe part 8, primary air supply parts 14, 16, switching valve 1
8, 19, 20, 21, a secondary air supply unit 24, and a processing device 26.

As shown in FIG. 1, the primary filters 2 and 4 are configured to be driven so that exhaust gas from a diesel engine can flow selectively or both to the one primary filter 2 and the other primary filter 4. Has become. That is,
The primary filters 2 and 4 are provided at positions where the exhaust gas passes upward in FIG. 1 so that the exhaust gas from the engine passes through the switching valve 18 or the switching valve 20.

The schematic structure of the primary filters 2 and 4 is as shown in FIGS. The structure is such that the primary filters 2 and 4 are cylindrical honeycomb structures, and a large number of through holes 30 communicating with each other in the cylinder axis direction shown in FIGS. 3 and 4 are formed. This through hole 30 is formed so as to extend in the z-axis direction by intersecting a wall body 34 extending in the coordinate axis x direction and a wall body 36 extending in the y direction shown in FIG. One end of the through hole 30 is plugged with a plug member 38, and the through hole 3 adjacent to the through hole 30 and the wall 36 is provided.
The other end side of 0 is plugged with a plug member 39. In this case, as shown in FIG. 3, the stopper member 38 and the stopper member 3
9 are plugged so that the through holes 30 are arranged in parallel. Therefore, as shown in FIG. 4, the exhaust gas enters from the through holes 30 on the plug member 39 side of the primary filters 2 and 4, passes through the wall body 36 in the direction of the arrow as shown in FIG. It leaks to the outside. At this time, the fine particles in the exhaust gas are
It is collected at the entrance side of the arrow 6 in FIG. The collected fine particles are deposited in the through holes 30, and the amount of fine particles deposited gradually increases with the passage of time.

Here, as shown in FIGS. 3 and 4, each of the primary filters 2 and 4 has a through hole 301 for communicating the through hole 30 inside the plug member 38 with the outside. This through hole 301
Is a lateral hole formed on the side surface of the primary filters 2 and 4 in the vicinity of immediately below the plug member 38, and is a hole for supplying air from the outside for blowing away the particles accumulated inside the plug member 38. By blowing a primary sub-pulse air, which will be described later, into the through hole 301 from outside, the deposited fine particles can be effectively removed.

As shown in FIG. 1, the secondary filter 6 is a honeycomb-shaped structure in which one end of a large number of through holes 30 is plugged and the other end of the through hole which is not plugged is opposite. It is sealed. Similar to the above-described primary filters 2 and 4, the end portion on the other side of the through hole that is plugged on one side is an opening, and the other side of the through hole that is not plugged on one side is plugged. Has been done.

The pipe portion 8 connects the inlet sides of the primary filters 2 and 4 and the inlet side of the secondary filter 6 with pipes 10 and 12. These pipes 10 and 12 allow the secondary filter 6 located at a remote position outside the exhaust system from the primary filters 2 and 4.
It is possible to convey fine particles to. The primary air supply units 14 and 16 are connected to the primary filters 2 and 4, respectively.
It is provided on the exhaust gas outflow side of the plug member 38 side. The primary air supply units 14 and 16 are composed of a primary main pulse supply unit 40 and a primary sub pulse supply unit 42 as shown in FIG. The primary main pulse and the primary sub-pulse consist of a pulsed air stream, and the generation source thereof is, for example, a compressor or the like. The primary main pulse is the primary filter 2, 4
It is introduced from the exhaust gas outflow side of the through hole 30 in the direction opposite to the exhaust gas flow direction. The primary sub-pulse is introduced from the primary sub-pulse supply unit 42 into the through hole 30 from the pipe 302 through the through hole 301. As a result, as shown in FIG. 5, the main pulse flows from the through hole 30 through the wall body 36 to the adjacent through hole 30 in the direction of the arrow indicated by the solid line, and flows out from the through hole 30 on the side. The sub-pulse is introduced in the direction of the dotted arrow shown in FIG. 6 so as to blow away the fine particles that accumulate near the side that is plugged by the plug member 38 on the exhaust gas outflow side. As a result, the fine particles deposited in the through holes 30 are blown off toward the exhaust gas inflow side at a time in the exhaust gas reverse flow direction. That is, the fine particles are blown off in the downward direction shown in FIG.

The switching valves 18, 19, 20, 21 are open / close valves and can be selectively switched between an exhaust gas circulation mode (collection mode) and a pulse air circulation mode (backwash mode).
In the state shown in FIG. 1, the switching valves 20 and 21 are in the exhaust gas circulation mode, and the switching valves 18 and 19 are in the pulse air circulation mode. The on-off valve of the present invention may use a three-way valve or other types of valves instead of the butterfly valve.

In the state shown in FIG. 1, the switching valve 18 on the right side,
In No. 19, the exhaust gas inlet 51 is closed and the exhaust gas outlet 53 is open. Further, in the switching valves 20 and 21 on the left side, the exhaust gas introduction port 51 is open and the exhaust gas discharge port 53 is closed.
In the state shown in FIG. 1, the exhaust gas is discharged to the outside through the exhaust gas introduction port 51 of the switching valve 20 and the primary filter 4. The primary main pulse and the primary sub-pulse are supplied from the primary main pulse supply source 40 and the primary sub-pulse supply source 42, respectively, and the pulsed air passes through the primary filter 2 and the pulsed air outlet 53 to the processing device 26 from the pipe 10. be introduced.

By switching the switching valves 18, 19, 20, and 21, the pipe 10 or the pipe 12 becomes the flow of the pulse air, and the pulse air and the particles are introduced into the processing device 26. The secondary air supply unit 24 is composed of a compressor or the like.
The secondary air supply unit 24 can supply pulsed air to the secondary filter 6 by a compressor (not shown). When the pulse flow is supplied from the secondary air supply unit 24 when the air bleeding switching valve 60 is closed, the collected fine particles of the secondary filter 6 are blown out from the holes 30 and the container 27 of the processing device 26 is discharged.
To fall.

The processing device 26 is provided at a remote position outside the exhaust system, and is a device that burns and processes the fine particles collected by the secondary filter 6 and blown off by the electric heater 50. The combusted combustion gas is discharged to the outside through the secondary filter 6 and the air vent switching valve 60. Next, the valve switching operation and ON / OFF of pulse air in the collection mode and the backwash mode will be described with reference to FIGS. 7 and 8.

At the time of collection, in FIG. 1, the switching valves 18, 20
Is opened and the switching valves 19 and 21 are closed, and the exhaust gas discharged from the diesel engine is collected by the primary filters 2 and 4. Then, the primary filters 2 and 4 are backwashed regularly. As shown in FIG. 7, for example, a backwash process of 6 seconds and 2
Repeat the collection process for minutes 54 seconds. In this backwash process, the operations of the switching valve 18, the switching valve 20, and the air bleeding switching valve 60 are as shown in FIG. This backwash process consists of (A) regeneration process, (B) transfer process, and (C) treatment process.

(A) Regeneration Process In the regeneration process, the switching valve 18 is closed and the switching valve 19 is switched to open, and the duration of this state is 1 second. Simultaneously with this switching, the primary pulse air is turned on for 0.1 second.
When the reproduction of the primary filter 2 (# 1) is completed, the same operation is then performed to reproduce the primary filter 4 (# 2). That is, the switching valve 20 of the primary filter # 2 is closed and the switching valve 21 is switched to open, and this state continues for 1 second. Simultaneously with this switching, the primary pulse air switches from off to on,
This on-time is 0.1 second. This completes the regeneration process of the primary filter 2 (# 1) and the primary filter 4 (# 2). After that, the primary filters 2 (# 1) and 4
For (# 2), the operation of collecting fine particles in the exhaust gas is executed.

(B) Transfer Process In the transfer process, after the regeneration process is completed, the operation in which the particles carried on the primary pulse air are transferred to the container 27 of the processing device 26 via the pipes 10 and 12 is completed. Say. In the present embodiment, the particles are conveyed all at once by the supply pressure from the primary air pulse supply source to the container 27 at a remote position via the pipes 10 and 12. The means for transporting particles is
Air pulse only, no other means of transfer. Here, as the air pulse, high-speed air, high-pressure air, or the like is used, and, for example, the air flow rate at the honeycomb filter outlet, the air pressure, etc. are set appropriately.

(C) Process When the secondary filter 6 collects fine particles, the air bleeding switching valve 60 switches from the open state to the closed state. At the same time, secondary pulse air is blown in the opposite direction from the secondary filter 6,
The particles collected by the secondary filter 6 are stored in the container 27 of the processing device 26
Fall inside. The on-time of the secondary pulse air is 0.1 second. The closed state time of the air bleeding switching valve 60 is about 3 seconds. Then, the fine particles that have dropped to the bottom of the container 27 are burned by the electric heater 50 and incinerated. The combustion gas is discharged from the container 27 to the outside through the secondary filter 6 and the air bleeding switching valve 60. This completes the processing removal of the fine particles.

The backwash process consisting of the regeneration process, the transfer process and the treatment process is completed in about 6 seconds in this case, and the backwash process is performed by the primary filter 2 (#
1) and the collection operation of the primary filter 4 (# 2) are periodically performed at intervals of 3 minutes. In addition, the primary filters 2 and 4 and the switching valves 18 and 19 in the first embodiment.
Although a time difference of about 1 second is provided for the switching operation of the switching valves 20 and 21, the present invention is not limited to this, and is reproduced by one secondary pulse air each time one primary filter is reproduced. It may be processed. The backwashing process may be performed irregularly.

Next, the results of experiments comparing the pressure loss of the exhaust gas treatment system between the first embodiment and the conventional comparative example will be described. (Experiment 1) Here, Comparative Example 1 in comparison with the first embodiment is an example in which a secondary filter (re-collection unit) is provided immediately below the primary filter.

In Experiment 1, the pressure loss of the exhaust gas treatment system was tested. Comparative example 1 was tested under the same conditions as in the first example except for the position of the secondary filter. The experimental results are shown in FIG. As shown in FIG. 10, Comparative Example 1
In comparison with the first embodiment, the pressure loss is relatively small in the first embodiment. This is considered to be because, in the case of Comparative Example 1, the backwash process of the primary filter shifts to the trapping process before the backwashing process of the primary filter is sufficiently completed due to soaring of fine particles such as soot. In the case of the first embodiment, since the secondary filter is installed outside the exhaust system, the backwashing process is surely completed and then the collection process is started.

(Experiment 2) Comparative Example 2 is an example in which zigzag sealing is used in place of conventional sealing of through holes. On the other hand, the first embodiment is an example in which row holes are sealed and a lateral hole is provided on the side surface, and a sub-pulse is blown from the lateral hole. In Experiment 2, the pressure loss of the exhaust gas treatment system was tested. Comparative example 2
Was tested under the same conditions as in the first embodiment except the structure of the primary filter and the sub-pulse supply. The experimental results are shown in FIG. As shown in FIG. 11, in Comparative Example 2,
The pressure loss increases with the passage of time of the exhaust gas treatment system. It is speculated that this is because in the case of Comparative Example 2, the degree of clogging of fine particles such as soot gradually increases. On the other hand, it is considered that in the first embodiment, the secondary filter is installed outside the exhaust system and the primary filter is sufficiently regenerated by the backwashing process by the sub-pulse.

Next, a second embodiment of the present invention is shown in FIG. The second embodiment is an example in which the collecting process and the backwashing process are performed with only one primary filter. That is, this is an example in which a bypass passage 74 that bypasses the passage 72 that circulates the switching valves 18 and 19 and the primary filter 2 is provided. That is, at the time of collection, the exhaust gas passes through the passage 72, and during the regeneration process of the backwash process, the exhaust gas flows through the bypass passage 74. This switching operation is performed by switching the switching valves 88 and 90.

In the second embodiment, since it is sufficient to provide a single primary filter, the structure is simplified and the manufacturing cost can be reduced. During regeneration, the exhaust gas is discharged to the outside through the bypass passage 74, so that the fine particles in the exhaust gas are not collected. However, since the regeneration period of the backwash process is extremely shorter than the collection period of fine particles of exhaust gas, there is almost no problem due to the inability to collect fine particles in exhaust gas.

[0031]

As described above, according to the exhaust gas treatment method and the exhaust gas treatment apparatus of the present invention, the fine particles collected by the primary filter are transferred from the primary filter to the treatment apparatus located at a remote position and then treated. There is an effect that clogging of the primary filter due to reverse blowback is prevented, proper regeneration of the primary filter is performed, and a treatment and removal effect of fine particles in the exhaust gas becomes large.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an exhaust gas treatment system according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an exhaust gas passage and a pulse passage according to the first embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a primary filter of the first embodiment of the present invention.

FIG. 4 is a schematic vertical sectional view of the primary filter shown in FIG.

FIG. 5 is a schematic perspective view of the primary filter showing the flow directions of the primary main pulse air and the primary sub-pulse air during reproduction according to the first embodiment of the present invention.

6 is a schematic vertical cross-sectional view of the primary filter shown in FIG.

FIG. 7 is a time chart showing a collection process and a backwash process according to the first embodiment of the present invention.

FIG. 8: 1 in the backwash process according to the first embodiment of the present invention
It is a time chart figure which shows the switching valve of a secondary filter, the switching valve of a secondary filter, and ON / OFF of each pulsed air.

FIG. 9 is a circuit diagram showing the flow of exhaust gas and pulsed air according to the second embodiment of the present invention.

FIG. 10 is a diagram showing the relationship between pressure loss and time for the first example of the present invention and comparative example 1.

FIG. 11 is a diagram showing the relationship between pressure loss and time for the first example of the present invention and comparative example 2.

[Explanation of symbols]

 1 Exhaust Gas Treatment System 2 Primary Filter (Filter) 4 Primary Filter (Filter) 6 Secondary Filter 8 Piping Section 10 Piping 12 Piping 14 Primary Pulse Air Supply Section (Air Supply Means) 16 Primary Pulse Air Supply Section (Air Supply Means) ) 18, 19 Switching valve 20, 21 Switching valve 24 Secondary air supply unit 26 Processing device 27 Processing container

Claims (5)

[Claims] 1. An exhaust gas treatment method for collecting and treating fine particles in exhaust gas discharged from an internal combustion engine by a honeycomb structured filter, the method comprising: a first step of circulating the exhaust gas and collecting fine particles in the exhaust gas. A second step of stopping the exhaust gas flow and causing the collected fine particles to flow in a direction opposite to the exhaust gas flow direction and transporting the fine particles to a remote position outside the exhaust system; and burning and processing the remote particles to discharge them to the outside. And a third step of performing an exhaust gas treatment method. 2. The exhaust gas treatment method according to claim 1, wherein the second step and the third step are performed at regular or irregular intervals during operation of the internal combustion engine. 3. An exhaust gas treatment method for collecting and treating fine particles in exhaust gas discharged from an internal combustion engine, comprising a collecting step of circulating the exhaust gas through a filter to collect fine particles in the exhaust gas. A regeneration step of flowing air in the direction opposite to the exhaust gas flow direction to remove trapped particulates of the filter, a transfer step of transporting the trapped particulates to a remote position outside the exhaust system by the pressure of the air, and the remote An exhaust gas treatment method, comprising: a treatment step of burning and treating fine particles at a position and discharging the fine particles to the outside. 4. An exhaust gas treatment device for collecting and processing fine particles in exhaust gas discharged from an internal combustion engine, comprising a filter for circulating exhaust gas and collecting fine particles in exhaust gas, and burning the collected fine particles. A processing device for processing, an opening / closing valve provided on the exhaust gas inlet side of the filter, a pipe having one end connected to the inlet side of the opening / closing valve and the other end connected to the processing device, When the on-off valve is closed, air is supplied in the reverse flow direction of the filter, and the air supply means for supplying the fine particles to the processing device via the on-off valve and the pipe is provided. Processing equipment. 5. The processing device comprises: a secondary filter for collecting fine particles in the primary pulse air; and secondary pulse air in the secondary filter in a flow direction opposite to the primary pulse air flow direction and in the secondary filter. Secondary air supply means for removing the collected particulates, a container for containing the collected particulates removed from the secondary filter, and a heating means provided in the container for burning the collected particulates. An exhaust gas treatment device characterized by the above.