JP2001098927A - Device for removing particulate from exhaust gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for removing particulates from exhaust gas, which restrain the exhaust resistance from increasing so as to prevent the output power from lowering, and to efficiently process trapped micro-particulates so as to simplify the device. SOLUTION: A device 200 for removing particulates from exhaust gas, which provided in an exhaust passage of a Diesel engine 100, is formed therein with a plurality of passages 34 which are therefore extended in the flowing direction of exhaust gas, and is composed of a filter 3 for trapping micro-particulates contained in exhaust gas, onto a partition wall 35, and a combustion chamber located on the gas introduction side of the filter 3, for burning trapped micro- particulates. The combustion chamber 4 comprises a combustion pipe 41, a mixing chamber 50 for uniformly distributing heat obtained by combustion in the pipe 41 over a zone of the input end face of the filter 30 through the agitation of exhaust gas, and a partition wall 45 for introducing the introduced exhaust gas into the mixing chamber 50, bypassing the combustion chamber 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing black smoke particles contained in exhaust gas discharged from a diesel engine, various boilers and the like.

[0002]

2. Description of the Related Art Exhaust gas from a diesel engine contains nitrogen oxides and black smoke particles (particulates) harmful to the human body. Among them, the black smoke particles are mainly composed of carbon, and various types of fine particle removing devices for removing the carbon particles have already been proposed. For example, Japanese Patent Application Laid-Open No. 1-77715 discloses a device using a cross-flow type ceramic filter. This device is
The introduction passage and the discharge passage of the exhaust gas are arranged so as to be orthogonal to each other via the partition wall of the gas-permeable porous solid (ceramic). The introduced exhaust gas passes through the partition,
Black smoke particles are captured by the partition walls.

[0003] For example, Japanese Patent Application Laid-Open No. 1-159408 discloses an apparatus for removing fine particles using a ceramic filter having a honeycomb structure. In this device, a partition wall forming each cell of the honeycomb structure is made of a gas-permeable porous solid, one end of the first group of cells is closed, and the other end of the second group of cells is closed. Exhaust gas is guided from the first group of cells to the second group of cells through each partition, and each partition captures black smoke particles.

[0004]

However, all of the above-mentioned conventional devices for removing particulates in exhaust gas are of a type in which black smoke particles are filtered by passing through a partition wall of a porous body. Therefore, there is a problem that the resistance of the exhaust gas flow increases and the output of the diesel engine decreases. In addition, the black smoke particles trapped by the partition walls are eventually incinerated and disposed of, but the ash remaining after the incineration remains on the ceramic partition wall surface and gradually becomes clogged, and finally the filter function is terminated. As the engine power decreases, the exhaust resistance further increases, causing a problem that the engine output decreases. For this reason, conventionally, a method has been adopted in which black smoke particles captured on the surface of the ceramic partition wall are backwashed, moved to another place, and then incinerated. Therefore, there is a problem that the device becomes large.

The present invention provides an apparatus for removing particulates in exhaust gas, which suppresses an increase in exhaust resistance to prevent a decrease in output, and efficiently processes captured particulates to simplify the apparatus. The purpose is to:

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a particulate removing device connected to an exhaust path of exhaust gas discharged from a combustion engine to remove particulates contained in the exhaust gas.
A plurality of passages defined by the partition walls are formed to extend in the flow direction of the exhaust gas, and the exhaust gas is included in the exhaust gas while being introduced from one end of the plurality of passages and discharged from the other end. A combustion chamber provided with a filter for trapping fine particles to be trapped on the partition wall, and a fuel spraying means and an ignition means disposed on the exhaust gas introduction end side of the filter for burning the fine particles trapped by the filter. A combustion tube disposed in parallel with the input end face of the filter, and a range of the input end face of the filter by stirring exhaust gas into which heat obtained by combustion in the combustion pipe is introduced. Having a mixing chamber for uniformly dispersing the exhaust gas into the input end face of the filter, and a barrier for guiding the introduced exhaust gas to the mixing chamber by bypassing the combustion chamber. That.

According to the present invention, the filter has a system in which fine particles of exhaust gas are trapped (adsorbed) by the partition walls that partition a plurality of passages formed in the direction of the flow of the exhaust gas, and the fine particles trapped by the filter are burned. Let it be incinerated. Ash generated by the combustion is discharged to the outside together with the exhaust gas. Therefore, unlike the conventional method in which the exhaust gas is removed by permeating the partition wall of the porous body,
There is no increase in exhaust resistance due to clogging of the filter. Further, in the present invention, the combustion chamber provided at the input end of the filter is provided with a barrier so that the exhaust gas does not directly hit the combustion pipe, whereby the ignition of the fuel in the combustion chamber is reliably performed. Like that. Furthermore, the mixing chamber is provided between the combustion pipe and the filter input end face, so that the exhaust gas guided around the combustion pipe can stir the heat generated by the combustion and uniformly blow the heat to the filter input end face. . Thereby, it is possible to efficiently burn the fine particles captured in the filter as a whole.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration in which a particulate removal device 200 for removing particulates is attached to an exhaust gas path of a diesel engine 100 provided with an exhaust gas recirculation device (EGR device) and a catalyst device. Particle removal device 200
Has a filter 3 housed in a rear portion 2b of the substantially cylindrical container 2, and a combustion chamber 4 formed in a front portion 2a of the container 2 for burning fine particles captured by the filter 3. The gas introduction pipe 5 of the particulate removal device 200 is connected to the exhaust pipe 7 of the diesel engine 100 via a bellows-type gas pipe 6. The exhaust pipe 8 of the particulate removal device 200 is connected to the muffler 16 via a bellows type gas pipe 9 and a catalyst device 10 for removing harmful gas. The catalyst device 10 is specifically configured using a catalyst capable of removing CO, HC, NOx, and the like.

As shown in FIG. 2, the filter 3 of this embodiment has a plurality of filter units 31 (31a, 31b,...) Stacked in the filter container 2 in the direction of the flow of the exhaust gas. Are sandwiched from above and below by the bands 32 and 33, and are integrally assembled. FIG.
A cross-sectional structure viewed from above by cutting along a horizontal plane in a state where two-stage filter units 31a and 31b are stacked is shown. Each filter unit 31 is composed of an integrally formed elliptic cylindrical porous ceramic block 30 and is divided by ceramic partition walls 35a and 35b whose outer peripheral portions are connected to each other. Is formed. Each filter unit 31 has a two-stage structure in which the upstream partition wall 35a and the downstream partition wall 35b are shifted by a half pitch. In other words, in each filter unit 31, a plurality of passages 34a on the upstream side and a plurality of passages 34b on the downstream side are formed with a shift of a half pitch, and a connection space 34c connecting all the passages 34a, 34b is formed in the middle thereof. And a zigzag passage is formed. By stacking such filter units 31 in a plurality of stages, fine particles can be effectively captured by the partition walls 35a and 45b without increasing the resistance of the exhaust gas.

The combustion chamber 4 formed in the container front part 2a includes:
A semi-cylindrical combustion tube 41 for reburning the exhaust gas is disposed in parallel with the gas input end face of the filter 3, and fuel spray nozzles 42a and 42b are disposed at both ends thereof. , Main glows 43a and 43b for ignition and sub-glows 44a and 44
b is provided. The main glows 43a and 43b are for atomizing the fuel supplied to the combustion tube 41, and the sub-glows 44a and 44b are for igniting the atomized fuel. These parts are covered by a ceramic tube 46. Thus, the fuel supplied to the combustion tube 41 can be retained. Then, when the switches of the main glows 43a and 43b are turned on and the ceramic tube 46 is heated, the fuel permeating the ceramic tube 46 evaporates and can be ignited by switching on the sub-glows 44a and 44b.
The main glows 43a and 43b and the bulges 44a and 44
b is controlled on and off by the relay circuit 26 under the control of the control box 18.

The specific configuration of the combustion chamber 4 is shown in FIG.
FIG. 3 shows a cross-sectional structure of the main part. On the upstream side of the combustion chamber 41, the exhaust gas to be introduced is directly
A barrier 45 is set up so as not to hit 1. Accordingly, the exhaust gas introduced from the introduction pipe 5 is diverted as indicated by the arrow in FIG. However, a plurality of small holes 47 are formed in the barrier 45 at upper and lower portions, and a part of the exhaust gas is supplied directly to the upper and lower portions of the combustion pipe 41 through the holes 47.

The downstream side of the combustion tube 41 is notched, and a pair of plate blades 51 for stirring are formed along the longitudinal direction of the combustion tube 41. A plurality of holes 52 for enhancing the stirring effect are formed along the center of the pair of plate blades 51. The flame generated by the combustion in the combustion pipe 41 is extruded into the mixing chamber 50 from above and below the plate blade 51 and from the hole 52 by the exhaust gas passing through the hole 47 of the barrier 45.
In the mixing chamber 50, as a result of the exhaust gas being stirred by the plate blades 51 and the holes 52, the heat generated by the extruded flame is almost evenly distributed in the range of the input end face of the filter 3, and the heat is averaged on the input end face of the filter 3. Is supplied with hot air. Thereby, the fine particles captured by the partition walls in the filter 3 can be evenly reburned.

If there is no barrier 45, the combustion tube 41
As soon as the fuel is ignited, the flame is blown out by the exhaust gas, making it impossible to reliably re-burn the exhaust gas.
In this embodiment, by arranging the barrier 45 in front of the combustion tube 41, ignition and combustion in the combustion tube 41 are ensured, and the heat is agitated in the mixing chamber to ensure reburning of exhaust gas. It is possible. In this embodiment, as shown in FIG. 2, an air hole 53 is opened in the gas introduction pipe 5 to the filter so that air can be supplied therefrom. By slightly mixing air in advance with the exhaust gas introduced by opening the electromagnetic valve 28 at the time of ignition, it becomes possible to more reliably re-burn the exhaust gas.

In this embodiment, the fine particle removing device 2
00 exhaust pipe 8 and diesel engine 100 intake pipe 1
1, a circulation path 13 for recirculating exhaust gas is provided. An exhaust gas recirculation control device (EGR device) 14 for controlling the amount of recirculated exhaust gas to reduce NOx is inserted into the circulation path 13. The ceramic temperature of the filter 3 of the particulate removal device 200 is
Is detected by the control box 1
8 The fuel such as light oil stored in the fuel tank 19 is throttled by the needle controller 27 during idling, and when the engine 100 exceeds a predetermined frequency, the fuel spray nozzles via the pump 22 and the solenoid valves 25a and 25b. The flow rate is increased stepwise and supplied to 42a and 42b. The air pump 23 includes the spray nozzles 42a,
Air is supplied to 42b.

In this embodiment, a normal exhaust system is not provided in the exhaust pipe 7 of the diesel engine 100 in addition to the exhaust system including the particle removing device 200. If the particulate removal device 200 fails, all functions are stopped under the control of the control box 18, and at this time, exhaust gas is discharged through the filter of the particulate removal device 200.

In this embodiment, a fine particle removing apparatus 200 is used.
Is controlled by the control signal from the control box 18 as follows. When the diesel engine 100 is started, the needle controller 2
A small amount of fuel is supplied from the nozzles 42a and 42b via the nozzle 7, and after a predetermined time, the main glows 43a and 43b are turned on, and subsequently the sub-glows 44a and 44b are turned on.
The air-fuel mixture supplied to the combustion chamber 4 is atomized and heated by the main glows 43a and 43b, and at the same time, air is introduced into the combustion chamber 4 by the solenoid valve 28 to prepare an ignition environment. As a result, the air-fuel mixture is ignited and the combustion operation starts. After ignition, the solenoid valve 28 is turned off, and all air is supplied to the nozzles 42a and 42b.

When the number of revolutions of the engine 100 reaches 1000 revolutions (rpm), the solenoid valve 25a is opened to increase the fuel supply. When the number of revolutions of the engine 100 reaches 2000, the solenoid valve 25b is opened to further increase the fuel supply amount. However, the engine speed for controlling the fuel supply amount can be appropriately changed according to the engine specifications. When the temperature inside the filter 3 increases due to the combustion in the combustion chamber 4, the graphite trapped on the surface of the filter partition wall is burned and removed. If the temperature exceeds 1000 ° C., NOx in the exhaust gas increases. Therefore, when the temperature sensor 21 detects that the ceramic temperature of the filter 3 has reached about 950 ° C., the solenoid valve 25b is turned off. Solenoid valve 25a
And the air pump 23 keeps the ON state. Thereby, the combustion in the filter 3 is continued. However, due to the decrease in fuel supply, the temperature of the filter 3 gradually decreases due to the exhaust gas. And the temperature of the filter ceramic is 7
When the temperature sensor 21 detects that the temperature has dropped to 50 ° C. or less, the solenoid valve 25b is turned on again, and the amount of fuel supplied to the combustion chamber 4 is increased. Hereinafter, the same operation is repeated.

According to this embodiment, the recirculation of graphite to the intake side, which is a problem in the EGR device, is suppressed by the filter 3, and the EGR device 14 can operate efficiently.
This makes it possible to effectively reduce black smoke and NOx in the exhaust gas. Further, the catalyst device 10 is connected to the fine particle removal device 2.
By arranging after 00, CO, NOx, etc. can be reduced.

Further, in the particulate removing apparatus 200 of this embodiment, the combustion chamber 4 provided integrally with the filter 3 at the preceding stage is devised so that the exhaust gas does not directly hit the combustion pipe 41, and the fuel ignition can be reliably performed. And combustion is possible. Further, a mixing chamber 50 is provided at the rear of the combustion pipe 41, and heat obtained as a result of combustion in the combustion chamber 41 is agitated by exhaust gas supplied thereto so that heat is uniformly supplied to the filter 3. I have to. As described above, the reburning of the fine particles in the filter 3 is efficiently performed.

In this embodiment, it is conceivable that the heat obtained in the exhaust pipe 8 by the combustion in the particulate removal device 200 is effectively used for cooling and heating the automobile. For this purpose, a heat exchanger 61 is attached to the exhaust pipe 8 as shown in FIG. When it is desired to lower the heat obtained by the heat exchanger 61 to some extent and use it for heating, a cooling condenser 62 is used as shown in the figure, or the heat exchanger 61 is connected to the exhaust pipe 8 behind a muffler (not shown). It should be attached to.

[0021]

As described above, according to the present invention, the filter has a system in which fine particles of exhaust gas are trapped (adsorbed) by the partition walls that partition a plurality of passages formed in the flow direction of the exhaust gas. The fine particles trapped in the filter are burned and ashed. Ash generated by the combustion is discharged to the outside together with the exhaust gas. Therefore, unlike the conventional method in which the exhaust gas is removed by allowing the exhaust gas to pass through the partition wall of the porous body, there is no increase in exhaust resistance due to clogging of the filter. Further, in the present invention, the combustion chamber provided at the input end of the filter is provided with a barrier so that the exhaust gas does not directly hit the combustion pipe, whereby the ignition of the fuel in the combustion chamber is reliably performed. Like that.
Furthermore, the mixing chamber is provided between the combustion pipe and the filter input end face, so that the exhaust gas guided around the combustion pipe can stir the heat generated by the combustion and uniformly blow the heat to the filter input end face. . Thereby, it is possible to efficiently burn the fine particles captured in the filter as a whole.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration in which a particulate removal device is incorporated in an exhaust system of a diesel engine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of the particle removing device of the embodiment.

FIG. 3 is a diagram showing a configuration of a combustion chamber in the particulate removal device.

FIG. 4 is a cross-sectional view showing a specific configuration of a filter of the particulate removal device.

FIG. 5 is a diagram showing a state in which a heat exchanger is attached to an exhaust pipe of the particulate removal device.

[Explanation of symbols]

100: Diesel engine, 200: Particle removing device, 3: Filter, 31 (31a, 31b, ...) ... Filter unit, 34a, 34b ... Passage, 35a, 35b
... partition wall, 4 ... combustion chamber, 41 ... combustion tube, 45 ... barrier, 50
... mixing room.

Claims (4)

[Claims] 1. A fine particle removing device connected to an exhaust path of exhaust gas discharged from a combustion engine to remove fine particles contained in the exhaust gas, wherein a plurality of passages defined by partition walls are used to control the flow of the exhaust gas. A filter formed so as to extend in the direction, and for trapping fine particles contained in the exhaust gas on the partition while the exhaust gas is introduced from one end of the plurality of passages and discharged from the other end; A combustion chamber having a fuel spraying means and an ignition means for burning the particulates trapped by the filter disposed on the exhaust gas introduction end side of the filter, wherein the combustion chamber is arranged in parallel with the input end face of the filter. A combustion tube disposed therein, and heat obtained by combustion in the combustion tube is uniformly dispersed within a range of an input end face of the filter by stirring of the introduced exhaust gas. A mixing chamber for supplying the surface, particulate filters in the exhaust gas and having a barrier for guiding exhaust gas into the mixing chamber by bypassing the combustion chamber to be introduced. 2. The apparatus for removing particulates in exhaust gas according to claim 1, wherein the filter is formed such that the plurality of passages zigzag from one end to the other end of the filter. . 3. The exhaust gas according to claim 2, wherein the filter is formed by stacking a plurality of filter units each formed by integrally molding a porous ceramic in a flow direction of the exhaust gas. Particle removal device. 4. In each of the filter units, a plurality of first passages opening at one end thereof and a plurality of second passages opening at the other end thereof are shifted from each other by a half pitch. The two passages are integrally formed so as to have a connection space for connecting all the passages to the connection portion. 4. The apparatus for removing particulates in exhaust gas according to claim 3, wherein: