JPH10259709A - Method for purifying exhaust gas and exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of a crack to a filter and dissolve melting loss so as to improve durability, by making air to serve as a heating medium, and blowing this heated air to the filter under the condition of a turbulent flow agitated. SOLUTION: To shut off an engine exhaust gas flow (y), and a channel is secured is for a secondary air flow (x) for refreshing combustion, and exhausts gas of the secondary air flow (x). After that, the refreshment of a filter 60 in which particulates are collected, is started. Firstly, the secondary air flow (x) for refreshing combustion, is introduced from a channel piping 62 on the downstream side of the secondary air flow (x) for refreshing combustion. The secondary air flow (x) is heated by a heating part 61 such as an electric heater so as to be hot air. This hot air is turned into a slewing flow when passed through an agitating part 4 so as to be agitated and mixed to have equal heat, and blown to the filter 60. The filter 60 is equally heated however, the hot air is supplied to the filter 60 so as to be equally heated under a condition that dispersion of temperature is corrected and controlled by passing the hot air through the agitating part 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying exhaust gas in which particulates (combustible fine particles such as soot) discharged from a diesel engine or the like are collected by a filter, and the collected matter is burned to regenerate the filter. Also, the present invention relates to an exhaust gas purifying apparatus equipped with a regenerating means mounted on a diesel engine exhaust gas purifying apparatus for efficiently regenerating a filter.

[0002]

2. Description of the Related Art In recent years, particulates (combustible fine particles such as soot) discharged from diesel engines and the like have been regulated for environmental protection and health reasons. As a method for removing the exhaust gas and purifying exhaust gas from a diesel engine, a method has been developed in which a filter of a heat-resistant ceramic honeycomb is provided in the middle of an exhaust pipe to filter particulates. The feature of this method is that when a certain amount of particulates accumulates, it can be ignited and burned, converted into carbon dioxide and released into the atmosphere, and the ceramic filter can be regenerated and used repeatedly. This operation is called combustion regeneration.
Generally, the exhaust gas of a diesel engine is lower than the ignition temperature of the particulates. Therefore, the particulates do not burn as they are, but only accumulate, causing the exhaust pressure to rise excessively and lowering the engine and emission performance. Therefore, for combustion regeneration, it is necessary to raise the exhaust gas temperature or the filter temperature by some method. Therefore, a method has been proposed in which two filters are provided in the exhaust system to purify the exhaust gas alternately. The combustion regeneration is performed not during the exhaust gas filtration but after the particulates are accumulated to some extent and when the exhaust gas purification is performed by the other filter. As the temperature raising means, regeneration is performed by heating the filter with an electric heater, a burner, a microwave, or the like, raising the temperature of the filter, and burning the particulates.

Hereinafter, a conventional exhaust gas purifying apparatus for a diesel engine will be described with reference to the drawings.

FIG. 9 is a schematic sectional view of a main part of a conventional exhaust gas purifying apparatus for a diesel engine. Reference numeral 51 denotes a conventional exhaust gas purifying apparatus for a diesel engine; 52, a diesel engine; 53, an exhaust manifold having respective upstream ends connected to exhaust holes of the diesel engine 52; and 54, a downstream end of the exhaust manifold 53. An upstream exhaust pipe having an upstream end connected to the upstream exhaust pipe 55a and 55b serves as an exhaust gas flow path of an engine exhaust gas branched from the downstream side of the upstream exhaust pipe 54 into two parts, and a regeneration gas flow during filter regeneration. The upstream-side flow path pipes 56 serving as paths are disposed at a branch point where the upstream-side exhaust pipe 54 branches into the respective upstream-side flow path pipes 55a and 55b.
Exhaust gas switching valves 57a and 57b for switching the flow path of the exhaust gas flow introduced into 5b,
a, 55b, which are disposed in the discharge valves 57a, 58b for releasing the regeneration gas to the atmosphere during filter regeneration.
A regeneration gas discharge pipe connected to 57b, 59a, 59b
Each upstream channel pipe 55a are each provided continuously by filter container at the downstream end of the 55b, 60a, 60b is a filter container 59a, 59b in the housing has been cordierite _{(2MgO · 5SiO 2 · 2Al 2} O ₃ ) A filter made of a ceramic honeycomb, such as a wall-flow type ceramic filter having a diameter (φ) of 5.66 inches × length (L4) of 6 inches, manufactured by extrusion molding;
61a and 61b are filter storage containers 59a and 59b, respectively.
Heating unit such as an electric heater attached to the
Reference numeral 2b denotes a downstream-side flow pipe for introducing a purified gas flow of purified engine exhaust gas and a secondary air flow x for combustion regeneration, which are provided downstream of each of the filter storage containers 59a and 59b.
a and 63b are secondary air supply pipes connected to the downstream side flow pipes 62a and 62b, 64 is a secondary air switching valve for switching the supply flow path of the secondary air flow x, 65 is a secondary air supply pipe, Reference numeral 66 denotes a secondary air supply unit such as an air blower which is disposed at an end of the secondary air supply pipe 65 and supplies a secondary air flow x to each of the filter housings 59a and 59b. 67 denotes a secondary air supply unit 66 and exhaust gas. Switching valve 56, secondary air switching valve 64, release valves 57a and 57b, heating unit 61
a, 61b.

[0005] The operation of the conventional diesel exhaust gas purifying apparatus configured as described above will be described below during regeneration.

While the filter 60a is purifying the exhaust gas, the start time of the regeneration is determined by a trapping amount detecting device such as a differential pressure sensor (not shown). Assuming that the exhaust gas flows from the upstream exhaust pipe 54 to the upstream flow pipe 55a,
The exhaust gas switching valve 56 and the secondary air switching valve 64 operate under the control of the controller 67, and the exhaust gas flows from the upstream exhaust pipe 54 to the upstream flow pipe 55b, is purified by passing through the filter 60b, and is purified. It flows out of the passage pipe 62b. On the other hand, the filter 60a, which is determined to be the regeneration start time, is supplied with electric power to the heating unit 61a and is heated. At the same time, the release valve 57a opens, and the secondary air supply unit 66 passes through the secondary air supply pipe 63a to the filter 60a. A secondary air flow x is provided. After a certain time, the temperature of the filter 60a reaches the ignition temperature of the particulates, and the particulates start burning. The combustion gas flows out of the downstream flow path piping 58a. After a lapse of a certain time, the power supply to the heating unit 61a ends, and the particulate combustion using only the secondary air flow x continues.
This combustion is achieved by the flame propagation of the particulates. After a certain period of time, it is determined that the combustion regeneration has been completed, and the secondary air supply unit 66 is stopped, and the discharge valve 5
7a is closed, the supply of the secondary air flow x is also terminated, and the filter 60a is in a state of waiting for exhaust gas purification.

Thereafter, when it is determined by the trapping amount detecting device such as a differential pressure sensor that the filter 60b has reached the regeneration start time, the filter 60b is regenerated by the same operation as described above.
Each of the filters 60a and 60b alternately repeats exhaust gas purification and combustion regeneration.

[0008]

However, in the above-mentioned conventional configuration, the heating by the electric heater is performed, and the burning of the particulates in the filter is the combustion by the flame propagation, so that the temperature gradient in the filter becomes very large. This is the cause of cracks in the filter. In addition, in order to achieve combustion continuation by flame propagation, depending on the collection state and collection amount of particulates, unburned particulates partially occur, and during repeated collection and regeneration, high temperatures occur due to abnormal combustion. This causes the filter to melt.

[0009] Cracks and erosion both greatly impair the function of the filter, and are major issues for practical use. As another heating method, there is a heating method using a burner in which light oil or the like is burned. However, it is necessary to ensure the safety of the burner because it emits a flame or a flame. The microwave heating method described in Japanese Patent Application Laid-Open No. 4-136409 has an advantage that the amount of trapped particulates can be detected. However, uniform heating in the filter, measures against microwave leakage, and safety by using high voltage There are issues such as ensuring the performance.

Further, Japanese Patent Publication No. 3-36133 discloses an exhaust gas purifying apparatus in which the temperature at the inlet of the filter is specified. This apparatus specifies the temperature required for completely burning the particulates. However, in this method, there is a problem that a rapid temperature rise occurs and the filter may be damaged.

Japanese Patent Laid-Open Publication No. 6-129 discloses a filter regeneration method called backwashing, in which particulates are removed with high-pressure air without heating the filter and heated and burned outside the filter, and an exhaust gas purifying apparatus using a swirling flow.
No. 230 is also known, but this is to reduce the clogging of the filter by reducing the particulates in the exhaust gas by incineration in advance using the exhaust gas itself as a swirling flow, but the filter life is long. Although the filter extends, the filter eventually becomes clogged, and in this case, there is a problem that the filter cannot be regenerated as it is.

The present invention solves the above-mentioned conventional problems. An exhaust gas purification method capable of suppressing cracks and erosion of a filter and improving durability, and a simple structure having high regenerating ability and high durability. It is an object of the present invention to provide an exhaust gas purifying apparatus having excellent performance.

[0013]

In order to solve the above-mentioned problems, the present invention does not use combustion regeneration by flame propagation, but uses air as a heating medium and filters the heated air in an agitated turbulent state. Or by rotating the filter itself without turning the heated air into a swirling flow, thereby blowing the heated air in a turbulent flow relative to the filter to uniformly heat and heat the entire filter. .

[0014] With this configuration, the entire filter is uniformly heated evenly without a temperature gradient, and the particulates are uniformly burned in the filter where the particulates are collected. This has the effect of preventing loss from occurring.

The filter for trapping particulates has a honeycomb structure of a wall-through type or a wall flow type, and an inorganic material such as cordierite or mullite is used as a material. Further, a metal material having excellent heat resistance and corrosion resistance may be used. Most of the shapes are cylindrical in cross section, but may be elliptic cylindrical or square. The size is 4-13 inches in diameter and 5-14 in length
In inches, the number of cells is preferably 50 to 400 cells per square inch. The amount of particulates collected by the filter is expressed in weight (gram) per unit volume (1 liter) of the filter, and is about 1 to 30 g / L.

As means for heating air, there is air heating by fuel combustion such as an electric heater for air heating or a burner. In the case of an electric heater for air heating, the heating element has a structure in which the heating element comes into contact with air, and as the heating element, a nichrome wire,
There are Kanthal wires, ceramic heaters and the like. For example, Fe
-A heating element made of a Cr-Al system is wound in a coil shape, the winding is covered with an insulator or the like, and the heating element is inserted into a metal protection tube such as stainless steel or the heating element is placed in a ceramic support portion. It is preferable to store what is wound by a winding method having good thermal efficiency. Note that a sheath-type heating element in which the heating element is housed for improving corrosion resistance may be used.

As the container for accommodating the filter, a heat-resistant and corrosion-resistant metal container is suitably used, and a sealing material made of a material containing vermiculite and expanding by heat is used between the filter and the filter. Effectively, leakage of particulates can be prevented. In addition, since the heat radiation of the container causes a temperature difference between the inner and outer circumferences of the filter, it is preferable to cover with a heat insulating material such as ceramic wool and insulate to improve the durability.

Means for blowing air include air blowers, air pumps, compressors and the like. The air blower has a large flow but small static pressure, and the air pump and compressor have a large static pressure but small flow. It is appropriately determined according to the use conditions of the exhaust gas purifying device.

The flow rate of air is 0.1 to 2.0 m ³
The more it is, the better, but 1 m ³ or less is appropriate from the capacity of the blowing means. In addition, since a large amount of electric power is required to heat air of about 1 m ³ , it is preferable to provide means for reducing electric power such as circulation of heated air and use of engine exhaust gas.

Further, one of the components of the particulate matter is soluble organic matter (SOF), which is not burned during regeneration, but is released to the atmosphere by evaporation without being burned even when collected by a filter. It is preferable to provide an SOF oxidation catalyst supporting a noble metal or the like before or after the filter used for the above.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the exhaust gas purifying method according to the first aspect of the present invention, the temperature of a filter that passes through the exhaust gas and collects particulates and the like in the exhaust gas is increased by a heating fluid and adheres to the filter. An exhaust gas purifying method for burning and purifying the particulates and the like, wherein the method includes a step of stirring the heating fluid and blowing the filter in a turbulent state such as a swirling flow to raise the temperature of the filter. Here, air is used as the heating fluid.

With this configuration, instead of regenerating the combustion by flame propagation, the air is used as a heating medium, and the heated fluid is stirred and mixed as a swirling flow, and air having a uniform temperature is blown to uniformly heat the entire filter. By suppressing the amount of heat generated per unit time due to the combustion reaction of the curate and making it smaller than the amount of heat released per unit time, there is no occurrence of a sharp temperature rise called so-called ignition, reducing the temperature gradient in the filter, and Extremely high temperatures can also be prevented. This has the effect that cracks and erosion of the filter can be completely prevented.

According to a second aspect of the present invention, there is provided an exhaust gas purifying method, wherein a filter for passing the exhaust gas and collecting the particulates in the exhaust gas is heated with a heating fluid to burn the particulates and the like attached to the filter. An exhaust gas purification method, wherein the heating fluid is sprayed while rotating the filter to raise the temperature of the filter. With this configuration, instead of burning and regenerating by flame propagation, this heating fluid is sprayed while rotating the filter itself using air as a heating medium, and the heating fluid and the filter are relatively rotated to make the entire filter uniform. By heating, the calorific value per unit time due to the burning reaction of particulates is suppressed, and by making it smaller than the amount of heat released per unit time, there is no sudden rise in temperature called so-called ignition, and the temperature gradient inside the filter is reduced. The size can be reduced and abnormally high temperatures can be prevented. This has the effect that cracks and erosion of the filter can be completely prevented.

An exhaust gas purifying apparatus according to a third aspect of the present invention includes a filter for removing particulates and the like in the exhaust gas, a heating means for heating a fluid blown to the filter,
A blower that blows a fluid to the filter, and a control unit that controls the blower and the heating unit when a predetermined amount of particulates and the like are collected in the filter. A static mixer disposed between the heating means and the filter, or a fixed blade having a shaft fixed to a front portion of a heating fluid outlet, a blade rotated by a heating fluid, or a blade forcibly rotated. Equipped with a stirring unit. Here, as the filter, a honeycomb structure made of a corrosion-resistant material such as cordierite or mullite and having a small pressure loss is preferable. Note that an oxidation catalyst may be provided on at least one of the filters. Each pipe is preferably made of corrosion-resistant stainless steel or the like.

As the heating means, an electric heater or the like is preferably used. For example, it is preferable to store a heating element such as a nichrome wire or a Kanthal wire wound in a highly efficient winding manner in a ceramic support portion. In addition, a sheath-type heating element in which a heating element is housed for improving corrosion resistance may be used.

With this configuration, the heating fluid is sprayed as a swirling flow using air as a heating medium and the filter is rotated relatively to the heating fluid, so that the filter as a whole is made uniform, instead of combustion regeneration by flame propagation. By heating, the calorific value per unit time due to the burning reaction of particulates is suppressed, and by making it smaller than the amount of heat released per unit time, there is no sudden rise in temperature called so-called ignition, and the temperature gradient inside the filter is reduced. The size can be reduced and abnormally high temperatures can be prevented. This has the effect that cracks and erosion of the filter can be completely prevented.

An exhaust gas purifying apparatus according to a fourth aspect of the present invention includes a filter for removing particulates and the like in the exhaust gas, a heating means for heating a fluid blown to the filter,
A blower that blows a fluid to the filter, and a control unit that controls the blower and the heating unit when a predetermined amount of particulates and the like are collected in the filter. It has the structure provided with the filter storage part which stores the said filter, and the stirring part formed with the rotation mechanism which rotates the said filter storage part. With this configuration, instead of burning and regenerating by flame propagation, this heating fluid is sprayed while rotating the filter itself using air as a heating medium, and the heating fluid and the filter are relatively rotated to make the entire filter uniform. By heating, the calorific value per unit time due to the burning reaction of particulates is suppressed, and by making it smaller than the amount of heat released per unit time, there is no sudden rise in temperature called so-called ignition, and the temperature gradient inside the filter is reduced. The size can be reduced and abnormally high temperatures can be prevented. This has the effect that cracks and erosion of the filter can be completely prevented.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1A is a schematic cross-sectional view of a main part of an exhaust gas purifying apparatus according to Embodiment 1 of the present invention.
FIG. 2B is a cross-sectional view taken along line AA of FIG.

In the figure, 55 is an upstream passage pipe, 60 is a filter made of ceramic honeycomb, 62 is a downstream passage pipe, x is a secondary air flow, and y is an engine exhaust gas flow. Since they are substantially the same, the same reference numerals are given and the description is omitted.

1 is an exhaust gas purifying apparatus according to the first embodiment, 2 is a filter container containing a filter 60,
Is a heating element made of an Fe-Cr-Al-based material, wound in a coil shape, and the wound material is covered with an insulator or the like, and further inserted into a metal protection tube such as stainless steel or a heating element in a ceramic support portion. The heating section 4 is disposed between the filter 60 and the heating section 3 and is composed of a sheath-type heating element in which the heating element is housed in a winding manner having good thermal efficiency, and the heating element is housed in a sheath for improving corrosion resistance. This is a stirrer that stirs and mixes the hot air fixed to the heating unit 3 and the like as a swirling flow. As shown in FIG. 1 (B), the stirring unit 4 fixes the guide blade 6 formed at a predetermined angle to a disk-shaped base 5 attached across the filter container 2 that stores the filter 60. Or rotatably or rotatably mounted via a rotating machine. The base 5 and the guide blades 6 are preferably made of corrosion-resistant and heat-resistant stainless steel.

The operation of the exhaust gas purifying apparatus configured as described above will be described below. First, after the engine exhaust gas stream y passes through the filter 60 and a predetermined amount of particulates are collected by the filter 60, the engine exhaust gas stream y is shut off by switching a valve (not shown) and the secondary combustion regeneration is performed. A flow path for the air flow x and its exhaust is secured. Thereafter, the regeneration of the filter 60 in which the particulates have been collected is started. First, the secondary air flow x for combustion regeneration is introduced from the downstream flow pipe 62 of the secondary air flow x for combustion regeneration. The secondary air flow x is heated by a heating unit 61 such as an electric heater to become hot air. This hot air is supplied to the stirring section 4
When passing through the filter 60, a swirling flow is formed and the mixture is stirred and mixed, and is blown to the filter 60 with uniform heat.
Heat. The secondary air flow x which is heated by the heating unit 61 such as an electric heater and becomes hot air has a non-uniform flow velocity distribution due to a pressure loss element such as a heating element at a secondary air passage portion in the heating unit 61 such as an electric heater. If the filter is blown onto the filter 60 in this state, the amount of hot air supplied according to the flow velocity distribution and the temperature of the hot air itself vary, so that the filter
Is heated non-uniformly, but as it passes through the stirring section 4, the hot air flow is stirred and mixed by the guide blades 6, and is supplied to the filter 60 in a controlled state with the temperature variation corrected and uniformly heated. As a result, the particulates collected by the filter 60 are uniformly burned in each part and can be regenerated without damaging the filter 60.

(Embodiment 2) FIG. 2 is a sectional view of a main part of an exhaust gas purifying apparatus according to Embodiment 2 of the present invention. FIG.
In the above, 55 is an upstream flow path pipe, 60 is a filter,
62 is a downstream flow pipe, x is a secondary air flow, y is an engine exhaust gas flow, these are substantially the same as those in the related art, and 3 is a heating unit similar to the first embodiment. Therefore, the same reference numerals are given and the description is omitted.

Reference numeral 10 denotes an exhaust gas purifying apparatus according to the second embodiment, 11 denotes a filter storage section divided into a filter storage container and a heating section storage section, and 12 denotes a rotatable support member (not shown) such as a roller. The supported rotary filter storage container, 13 is a heating unit storage device in which the heating unit 3 is stored, and 14 is a bearing and the like disposed between the rotary filter storage container 12 and the heating unit storage device 13. A rotary support portion, 15 is a seal portion for preventing gas or the like from leaking from the rotary support portion, 16 is a motor, 17 is a rotary force transmitting the rotary force of the motor 16 to the rotary filter container 12, and a filter 6.
This is a rotation transmission unit that rotates 0.

The rotation support portion 14 and the seal portion 15 are made of corrosion-resistant and heat-resistant stainless steel or ceramics, and the rotation conduction portion 17 is made of a heat-resistant stainless steel or other metal belt or gear. Is desirable. This is to enhance durability.

The operation of the exhaust gas purifying apparatus configured as described above will be described below. First, after the engine exhaust gas stream y passes through the filter 60 and a predetermined amount of particulates are collected by the filter 60, the engine exhaust gas stream y is shut off by switching a valve (not shown), and the secondary air for combustion regeneration is switched off. A flow path for the flow x and its exhaust is secured. Thereafter, the regeneration of the filter 60 in which the particulates have been collected is started. First, the secondary air flow x for combustion regeneration is introduced from the downstream flow pipe 62 of the secondary air flow x for combustion regeneration. The secondary air flow x is heated by the heating unit 3 such as an electric heater and becomes hot air, which is blown to the filter 60 to heat the filter 60. The secondary air flow x heated by the heating unit 3 such as an electric heater and turned into hot air has a non-uniform flow velocity distribution due to a pressure loss element such as a heating element at a secondary air passage portion in the heating unit 3 such as an electric heater. However, when the filter 60 is sprayed in this state, the amount of hot air supplied according to the flow velocity distribution and the temperature of the hot air itself tend to vary, so that the filter 60 is heated unevenly.
Since the filter 60 is rotated by the motor 16, the hot air flow is relatively turbulent, such as a swirling flow, and the rotation also induces the rotation of the hot air itself. Supplied. Further, since the variation of the temperature of the hot air is corrected by the stirring and mixing of the hot air due to the rotation of the hot air itself, the filter 60 is uniformly heated. As a result, the particulates collected by the filter 60 are uniformly burned in each part and can be regenerated without damaging the filter 60.

(Embodiment 3) FIG. 3 is a schematic sectional view showing an exhaust gas purifying apparatus for a diesel engine according to Embodiment 3 of the present invention.

In the drawing, 52 is a diesel engine, 53 is an exhaust manifold, 54 is an upstream exhaust pipe, 55a and 55
b is an upstream side flow pipe, 56 is an exhaust gas switching valve, 5
7a and 57b are discharge valves, 60a and 60b are filters,
62a and 62b are downstream flow pipes, 63a and 63b are secondary air supply pipes, 64 is a secondary air switching valve, 65
Is a secondary air supply pipe, and 66 is a secondary air supply section such as an air blower. These are substantially the same as those in the prior art, and are denoted by the same reference numerals and description thereof is omitted.

Reference numeral 20 denotes an exhaust gas purifying apparatus according to Embodiment 3 of the present invention, and reference numerals 21a and 21b denote respective upstream side flow path pipes 55.
The exhaust gas purifying devices according to the first embodiment, each of which is connected to the downstream end portion of each of the exhaust gas purifiers a and 55b, 22a and 22b are Fe-Cr-
A heating element made of an Al-based material is wound into a coil, and the wound material is covered with an insulator or the like, and further inserted into a metal protection tube such as stainless steel or a heating element having a high heat efficiency is wound inside a ceramic support portion. The heating units 23a and 23b are stirrers, and the heating units 23a and 23b are stirring units.
a and 24b are temperature sensors; 25a and 25b are differential pressure sensors measuring the pressure difference before and after the filters 60a and 60b, respectively; 26 are heating units 22a and 22b, switching valves 56 and 64, and a secondary air supply unit 66; The controller is electrically connected and controls the entire exhaust gas purification device 20.

As the temperature sensors 24a and 24b, those which can detect a relatively high temperature, such as a sheath type thermocouple and a platinum resistor, are used, and those having good corrosion resistance are used because they are exposed to exhaust gas. In addition, each sensor is arranged to prevent a decrease in the indicated temperature due to radiant heat transfer.

It is preferable to use a semiconductor pressure sensor or the like for the portion of the differential pressure sensors 25a and 25b arranged in the filter container, but it is preferable to arrange a mist filter or the like around the sensors so that the exhaust gas does not come into direct contact.

The operation of the exhaust gas purifying apparatus configured as described above will be described below with reference to the drawings.
FIG. 4 is a flowchart showing an operation of the combustion regeneration of the exhaust gas purifying apparatus for the diesel engine according to the third embodiment of the present invention. Now, the exhaust gas purifying apparatus 20 according to the third embodiment includes:
It is assumed that the exhaust gas discharged from the diesel engine 52 is purified by one filter 60a. First, the controller 26 refers to the output of the differential pressure sensor 25a to determine whether it is the combustion regeneration time. That is, a differential pressure signal is generated based on the output of the differential pressure sensor 25a, and based on the differential pressure signal, the controller 26 determines whether it is the combustion regeneration time. In the case of the present embodiment, the larger the difference between the pressure on the exhaust gas inflow side and the pressure on the exhaust gas outflow side of the exhaust gas purification device 21a, the more particulates and the like are collected in the filter 60a.
The controller 26 determines that the filter 60a is at the combustion regeneration time. Next, in order to purify the exhaust gas with the other filter 60b, the controller 26 inclines the exhaust gas switching valve 56 toward the upstream flow pipe 55a so as to close the upstream flow pipe 55a, and at the same time switches the switching valve. The valve 64 is inclined so as to close the secondary air supply pipe 63b, and the discharge valve 57a is opened (S1).

The exhaust gas discharged from the diesel engine is introduced into the filter vessel 21b from the exhaust manifold and the upstream exhaust pipe 54 via the upstream flow pipes 55b in sequence, and the particulates in the exhaust gas are filtered by the filter 60b. After the collected gas and the like are collected, the purified gas from which the particulates and the like have been removed is discharged into the atmosphere from the flow path pipe 62b. Further, the secondary air flow x that has passed through the filter 60a during the combustion regeneration is discharged from the upstream-side flow path pipe 55a to the discharge valve 57a.
The gas is exhausted from the discharge pipe 58a through the a. Next, the controller 26 calculates the trapped amount of particulates from the traveling distance, the differential pressure of S1, and the like (S2). Next, the controller 26 sets the air volume of the secondary air supply unit 66 to be constant according to the calculated trapped amount of the particulates.
A combustion regeneration program for controlling the current / voltage applied to a is determined (S3). Next, the controller 26
According to the combustion regeneration program of No. 3, the secondary air supply unit 66
Is turned on and the current / voltage applied to the heating unit 22a is controlled with reference to the signal from the temperature sensor 5a to start the combustion regeneration step (S4). Next, after the time set on the combustion regeneration program in S4 has elapsed, the controller 26 measures the differential pressure across the filter 60a in the exhaust gas flow direction with the differential pressure sensor 25a (S5).
Here, if the differential pressure is higher than the set value, S6
Jump to and continue the combustion regeneration program (S6)
At the same time, the determination at S5 is repeated. If the value is low, the process jumps to S7. Here, controller 2
6 is a heating unit 22a in which the air volume of the secondary air supply unit 66 is constant.
A predetermined temperature lowering step obtained by controlling the current / voltage applied to is started (S7). Next, the controller 26
When a predetermined time has elapsed in S8, the current / voltage applied to the heating unit 22a is stopped, the secondary air supply unit 66 is turned off (S8), and the regeneration process of the filter 60a is completed.

(Embodiment 4) FIG. 5 is a schematic sectional view showing an exhaust gas purifying apparatus for a diesel engine according to Embodiment 4 of the present invention.

In the figure, 52 is a diesel engine, 53 is an exhaust manifold, 54 is an upstream exhaust pipe, 55a and 55
b is an upstream channel exhaust pipe, 56 is an exhaust gas switching valve, 5
7a and 57b are discharge valves, 60a and 60b are filters,
62a and 62b are downstream flow pipes, 63a and 63b are secondary air supply pipes, 64 is a secondary air switching valve, 65
Is a secondary air supply pipe, and 66 is a secondary air supply section such as an air blower, which are substantially the same as those in the prior art.
Reference numerals 22a and 22b denote heating units, reference numerals 24a and 24b denote temperature sensors, and reference numerals 25a and 25b denote differential pressure sensors, which are the same as those in the third embodiment, and are denoted by the same reference numerals and description thereof is omitted.

Numeral 30 denotes an exhaust gas purifying apparatus for a diesel engine according to Embodiment 4 of the present invention, 31a and 31b denote a filter storage portion divided into a filter storage container and a heating portion storage device, and 32a and 32b rotatable rollers and the like. The rotary filter storage container 33a, 33b supported by a rotary support (not shown) has heating units 22a, 22b inside.
Are housed in the heating unit, and 34a and 34b are rotatable filter housings 32a and 32b and the heating unit housing 33.
a and a seal portion for preventing leakage of gas or the like from a rotary support portion having a built-in rotary support portion provided with a bearing and the like disposed between 33a and 33b; motors 35a and 35b;
6b transmits the rotational force of the motors 35a and 35b to the rotary filter containers 32a and 32b and filters 60a and 60b.
The rotation transmitting portions 37a and 37b rotatably connect the fluid circulation portions of the rotary filter storage containers 32a and 32b to the upstream pipes 55a and 55b, and allow the fluid to flow in the same manner as the seal portions 34a and 34b. The joint part 38 which is sealed so as not to leak is the switching valve 5
6, 64, the secondary air supply unit 66 and the heating units 22a, 22
The controller is electrically connected to the controller b and controls the entire exhaust gas purifying apparatus 30.

The operation of the exhaust gas purifying apparatus configured as described above will be described below with reference to the drawings.
FIG. 6 is a flowchart showing an operation of the combustion regeneration of the exhaust gas purifying apparatus for the diesel engine according to the fourth embodiment of the present invention. Now, the exhaust gas purifying apparatus 30 according to the fourth embodiment includes:
It is assumed that the exhaust gas discharged from the diesel engine 52 is purified by one filter 60a. First, the controller 38 refers to the output of the differential pressure sensor 25a to determine whether it is the combustion regeneration time. That is, a differential pressure signal is generated based on the output of the differential pressure sensor 25a, and the controller 38 determines whether it is the combustion regeneration time based on the differential pressure signal. In the case of the present embodiment, as the pressure difference between the exhaust gas inflow side and the exhaust gas outflow side of the rotary filter storage container 32a increases, the filter 60
Since a large amount of particulates and the like are collected in a, the controller 38 determines that the filter 60a is in the combustion regeneration time. Next, controller 3
8, in order to purify the exhaust gas with the other filter 60b, the switching valve 56 is inclined toward the upstream flow pipe 55a so as to close the upstream flow pipe 55a, and at the same time, the switching valve 64 is set to the secondary air. The supply pipe 63b is inclined so as to be closed, and the discharge valve 57a is opened (S1). As a result, the exhaust gas discharged from the diesel engine 52 is introduced into the rotary filter storage container 32b from the exhaust manifold 53 and the upstream exhaust pipe 54 through the upstream flow pipes 55b sequentially, and the filter 60b removes the exhaust gas from the exhaust gas. After the particulates and the like have been collected, the purified gas from which the particulates and the like have been removed is discharged into the atmosphere from the downstream flow path pipe 62b. The secondary air flow x that has passed through the filter 60a during the combustion regeneration is discharged from the upstream flow path pipe 55a through the discharge valve 57a to the discharge pipe 58a.
More exhausted. Next, the controller 38 calculates the trapped amount of particulates from the traveling distance, the differential pressure of S1, and the like (S2). Next, the controller 38 controls the current / voltage applied to the heating unit 22a while keeping the air volume of the secondary air supply unit 66 and the rotation speed of the motor 35a constant according to the calculated trapped amount of particulates. A reproduction program is determined (S3). Next, the controller 38
Controls the current / voltage applied to the secondary air supply unit 66, the motor 35a "ON" and the heating unit 22a with reference to the signal from the temperature sensor 24a in accordance with the combustion regeneration program in S3, and starts the combustion regeneration process. Is performed (S4).
Next, when the time set on the combustion regeneration program in S4 elapses, the controller 38 sets the filter 60a.
Is measured by the differential pressure sensor 25a before and after the exhaust gas flow direction (S5). If the differential pressure is higher than the set value, the process jumps to S6, continues the combustion regeneration program (S6), and repeats the determination in S5. If the value is low, the process jumps to S7. Here, the controller 38 starts a predetermined temperature lowering step obtained by controlling the current / voltage applied to the heating unit 22a while keeping the air volume of the secondary air supply unit 66 and the rotation speed of the motor 35a constant (S7). Next, the controller 38
After a predetermined time elapses, the current / voltage applied to the heating unit 22a is stopped, and the secondary air supply unit 66 and the motor 35a are turned off (S8), and the filter 60
The regeneration step of a is completed.

[0047]

Next, embodiments of the present invention will be described.

(Embodiment 1) After collecting particulates in exhaust gas using the exhaust gas purifying apparatus for a diesel engine according to the third embodiment of the present invention, a combustion regeneration program according to the amount of collected particulates is performed. Was set, and a total of nine temperature sensors were arranged in the filter as shown in FIG. 7 for the experiment, and the temperature in the regeneration step was measured. FIG. 8A shows the measurement results. For comparison, FIG. 8B shows a measurement result obtained by measuring the temperature in the regeneration step using the exhaust gas purifying apparatus for a diesel engine in the conventional example.

Table 1 shows the temperature variations at the nine points in the filter at each time in the respective measurement results.

[0050]

[Table 1]

As is clear from the experimental results shown in FIGS. 8B and 8 (Table 1), in the conventional example, the temperature variation at each time is very large due to the combustion regeneration accompanied by the flame propagation. Since no flame propagation is involved, the temperature variation at each time is small and it can be seen that uniform heating of the filter can be realized.

[0052]

As described above, according to the exhaust gas purifying method of the present invention, the filter that passes the exhaust gas and collects particulates and the like in the exhaust gas is not used for combustion regeneration by flame propagation, but uses air as a heating medium. This heating fluid is stirred and mixed with indoor blades or the like, or is sprayed while rotating the filter itself, thereby heating the entire filter in a state where the heating fluid and the filter are relatively rotated. The amount of heat generated per unit time can be suppressed to be smaller than the amount of heat released per unit time, so that there is no sudden rise in temperature called so-called ignition, the temperature gradient in the filter can be reduced, and abnormally high temperatures can be prevented. Therefore, an advantageous effect that cracks and erosion of the filter can be completely prevented can be obtained.

According to the exhaust gas purifying apparatus of the present invention,
Since the heating fluid is configured to be agitated and mixed, an advantageous effect that a thermal gradient is hardly generated in the filter, thermal distortion is prevented, and durability can be significantly improved can be obtained.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional view of a main part of an exhaust gas purifying apparatus according to Embodiment 1 of the present invention. FIG. 1B is a cross-sectional view taken along line AA in FIG.

FIG. 2 is a schematic sectional view of a main part of an exhaust gas purifying apparatus according to Embodiment 2 of the present invention.

FIG. 3 is a schematic sectional view showing an exhaust gas purifying apparatus for a diesel engine according to a third embodiment of the present invention.

FIG. 4 is a flowchart showing a combustion regeneration operation of an exhaust gas purification device for a diesel engine according to Embodiment 3 of the present invention.

FIG. 5 is a schematic sectional view showing an exhaust gas purifying apparatus for a diesel engine according to a fourth embodiment of the present invention.

FIG. 6 is a flowchart showing an operation of a combustion regeneration of an exhaust gas purifying apparatus for a diesel engine according to a fourth embodiment of the present invention.

FIG. 7 is a measurement point diagram of the temperature in the filter according to the embodiment of the present invention.

FIG. 8 (a) A time-dependent change diagram of the temperature in the filter in the example (b) A time-dependent change diagram of the temperature in the filter in the comparative example

FIG. 9 is a schematic cross-sectional view of a main part of a conventional exhaust gas purifying apparatus for a diesel engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus of Embodiment 1 2 Filter container 3 Heating unit 4 Stirring unit 5 Base 6 Guide vane 10 Exhaust gas purification device of Embodiment 2 11 Filter storage unit 12 Rotary filter storage container 13 Heating unit storage 14 Rotation support Unit 15 Sealing unit 16 Motor 17 Rotation conducting unit 20 Exhaust gas purifying device of Embodiment 3 21 Exhaust gas purifying device 22a, 22b Heating unit 23a, 23b Stirring unit 24a, 24b Temperature sensor 25a, 25b Differential pressure sensor 26 Controller 30 Embodiment Exhaust gas purifying apparatus 31a, 31b Filter storage section 32a, 32b Rotary filter storage container 33a, 33b Heating section storage section 34a, 34b Seal section 35a, 35b Motor 36a, 36b Rotation conduction section 37a, 37b Joint section 38 Controller DESCRIPTION OF SYMBOLS 1 Conventional exhaust gas purification apparatus 52 Diesel engine 53 Exhaust manifold 54 Upstream exhaust pipe 55a, 55b Upstream flow path piping 56 Exhaust gas switching valve 57a, 57b Release valve 58a, 58b Release pipe 59a, 59b Filter storage container 60a, 60b Filter 61a , 61b Heating parts 62a, 62b Downstream flow path piping 63a, 63b Secondary air supply piping 64 Secondary air switching valve 65 Secondary air supply piping 66 Secondary air supply part 67 Controller 5a, 5b Temperature sensor 57a, 57b Release valve 58a, 58b Release pipe x Secondary air flow y Engine exhaust gas 15 Seal part 16 Motor 17 Rotation transmission part

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F01N 3/02 341 F01N 3/02 341R 341Z

Claims (4)

[Claims] 1. A method for purifying an exhaust gas, comprising: raising a temperature of a filter for collecting particulates and the like in the exhaust gas by passing the exhaust gas with a heating fluid, and burning and purifying the particulates and the like attached to the filter; A method for purifying exhaust gas, comprising a step of stirring the heating fluid and spraying the filter in a turbulent state such as a swirling flow to raise the temperature of the filter. 2. A method for purifying exhaust gas, wherein a temperature of a filter for collecting particulates and the like in the exhaust gas by passing the exhaust gas is increased by a heating fluid and burning the particulates and the like attached to the filter. An exhaust gas purifying method, which comprises a step of blowing the heating fluid while rotating the filter to raise the temperature of the filter. 3. A filter for removing particulates and the like in exhaust gas, heating means for heating a fluid to be blown to the filter, blowing means for blowing a fluid to the filter, and a predetermined amount of particulates and the like trapped in the filter. When collected, a control means for controlling the blowing means and the heating means, an exhaust gas purification device comprising:
A static mixer disposed between the heating means and the filter, or a fixed blade having a shaft fixed to the front of the heating fluid outlet, a blade rotated by a heating fluid, a blade forcedly rotated, or the like. An exhaust gas purifying apparatus comprising the formed stirring section. 4. A filter for removing particulates and the like in exhaust gas, heating means for heating a fluid to be blown to the filter, blowing means for blowing a fluid to the filter, and a predetermined amount of particulates and the like trapped in the filter. When collected, a control means for controlling the blowing means and the heating means, an exhaust gas purification device comprising:
An exhaust gas purifying apparatus comprising: a filter storage unit that stores the filter; and a stirring unit formed by a rotation mechanism that rotates the filter storage unit.