JPH07293225A - Exhaust gas purifying method and exhaust gas emission control device - Google Patents

Abstract

PURPOSE:To provide an exhaust gas purifying method and an exhaust gas emission control device without causing any crack, etc., to a trap. CONSTITUTION:When particulates, etc., which are stuck to a trap 5 stored in a trap container 4 are combusted by an electric heater 6, a controlling part 12 controls electric power to be inputted to the electric heater 6 based on the information of a temperature detecting sensor 11 to measure the combustion temperature of the trap 5 so as to satisfy such a condition that the temperature of the trap 5 becomes below 500 deg.C or a maximum temperature gradient in the radial direction of the trap 5 becomes below 10 deg.C/mm, or satisfy both conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying method and an exhaust gas purifying apparatus for purifying exhaust gas, particularly diesel exhaust gas.

[0002]

2. Description of the Related Art Most of unburned particulate matter in diesel engine exhaust gas, such as solid carbon particulates, liquid or solid high molecular weight hydrocarbon particulates (hereinafter abbreviated as particulates), It is less than 1 micron, and easily floats in the atmosphere and is easily taken into the human body by breathing. Moreover, since it contains carcinogenic substances, in recent years many problems have been taken up in Japan and overseas, and it is expected that emission regulations will be further tightened in the future.

This particulate is included in diesel exhaust gas.
NO, which is a toxic substance besides the rate _X Is included,
There are also regulations on this substance. NO_X And putty
The generation of iculate is in a trade-off relationship and NO_X 
Reduction measures will increase the emission of particulates.
Tend to Therefore, improving the engine operating system, etc.
NO only by_X And reduce both particulates
Is difficult and exhaust gas when it comes to particulates
Use a particulate trap installed in the line
The removal is done by collecting it physically. Only
If the trap is used for a long time, the trap will accumulate.
Generated particulates cause clogging and pressure loss.
In order to burn it, the collected particulates are burned regularly,
Examination is progressing as a promising method to regenerate the trap
It is

[0004]

The particulates contained in diesel exhaust gas are composed of liquid or solid high molecular weight hydrocarbon particles having a relatively low ignition temperature and solid carbon particles having a relatively high ignition temperature. And
The ratio is the emission condition (engine type, operation mode, etc.)
The ignition temperature of the particulates varies depending on the discharge conditions, and the ignition temperature of the solid carbon fine particles, liquid or solid high-molecular weight hydrocarbon fine particles themselves also varies depending on the discharge conditions, but in general, they are collected in the trap. In order to burn off the particulates and suppress the pressure loss of the exhaust gas line, it is necessary to heat the trap and the trapped particulates to a high temperature (600 to 700 ° C.), which causes the following problems. (1) At the time of regeneration, it is necessary to keep the trap at a high temperature in order to ignite the particulates, and this heat and the combustion heat of the particulates after the ignition raises the temperature of the trap portion and melts the trap material. (2) At the time of regeneration, the heat source is supplied from one side of the trap, but the ignition temperature is high as described above, and the combustion heat of the particulates is added to this, which causes a temperature difference between the ignited part and the unignited part. The thermal stress inside the trap increases and cracks occur.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a practically excellent exhaust gas purification method and exhaust gas purification apparatus in which the trap does not melt or break or crack.

[0006]

In order to achieve the above object, the temperature of the trap during combustion is set to 500 ° C. or lower, or the maximum radial temperature gradient is set to 10 ° C./mm or lower.

[0007]

The particulate matter collected according to the present invention can be burned while suppressing the temperature rise, so that the trap material is melted.
The generation of cracks can be prevented, and the trap can be regenerated without causing a significant decrease in the efficiency of the total system of the internal combustion engine using the diesel engine.

That is, the energy input for heating is controlled so that the trap material temperature is 500 ° C. or lower when the trap in which the particulates are collected is regenerated, and the trap is loaded with an oxidation catalyst effective for burning the particulates. As a result, it is possible to reduce the combustion temperature of the particulates, prevent the melting and cracking of the trap material, and suppress the decrease in the efficiency of the total system.

Further, in the trap structure, a two-dimensional structure carrying a plurality of oxidation catalysts having different mesh sizes, which is installed before the three-dimensional structure for collecting particulates, is discharged from the engine. Among the particulates, it is possible to achieve disintegration (fine particle formation) and pre-oxidation of apparently large aggregated particles.

Further, since the trap material is insulated from the container and further from the outside of the container, heat retention during heating is improved.

By providing a heat-sensitive element, a pressure sensor and / or other sensor, it is possible to detect the timing of heating and regeneration and the trap temperature, and this can be connected to a heating device to perform regeneration under desired conditions.

[0012]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 is a schematic diagram showing an exhaust gas purifying apparatus according to an embodiment of the present invention. FIG. 1 shows an exhaust gas purifying apparatus for a diesel engine, for example.

In FIG. 1, 1 is a diesel engine main body, 2 is an exhaust manifold connected to the diesel engine main body 1, 3 is an exhaust pipe connected to the exhaust manifold 2, and 4 is a trap container connected to the exhaust pipe 3. The exhaust gas discharged from the diesel engine body 1 is guided from the exhaust manifold 2 through the exhaust pipe 3 to the trap container 4 made of a heat-resistant material.

In the trap container 4, a trap 5 for collecting particulates and a pair of electric heaters 6 are provided.
The two-dimensional structure 7 and the like, which are provided on the exhaust gas introduction side of the trap container 4 and are sandwiched between the pair of electric heaters 6, are housed. A heat insulating material 8 is provided on the outer peripheral portion of the trap 5. At times, a heat insulating material 9 is also provided on the outer peripheral portion of the trap container 4 as shown in FIG. The heat insulating materials 8 and 9 are made of, for example, ceramic fibers.

As the trap 5, for example, a heat-resistant ceramic fired body, a metal porous body, a cotton-like body, or the like can be used. Further, the trap container 4 is a granular body formed to have an appropriate size. You may use what was filled.
When a fire-resistant ceramic fired body is used, S in exhaust gas
It is excellent in that it has high durability against corrosive gas such as O _x , and is excellent in that it has high thermal conductivity when a metal cotton-like material is used.

Specific materials for the trap 5 include alumina, mullite, cordierite, silicon carbide,
Ceramics such as titanium oxide, SUS-42, SU
A metal material such as S-43, SUS-301S or Inconel is used.

Further, the trap 5 carries an oxidation catalyst such as particulates effective for combustion.

The trap 5 will be specifically described. For example, as shown in FIG. 2, a honeycomb structure 20 is provided which is made of ceramic or the like and has a plurality of through holes 21 extending in one direction. Exhaust gas inflow surface 20a
And the exhaust gas outflow surface 22 are alternately filled with plug members 23. Furthermore, the honeycomb structure 2
0, an oxidation catalyst 24 is provided. As the oxidation catalyst 24, noble metals such as Pt and Rh, which are effective for burning liquid or solid high-molecular weight hydrocarbon particles, and solid carbon particles are effective for burning. Metal oxides such as Cu and V, and La
A composite oxide in which a part of perovskite type oxide such as MnO ₃ or LaCrO ₃ is replaced with an alkali metal or alkaline earth metal such as Sr, K or Li is used. As the oxidation catalyst 24, the above-mentioned catalyst materials may be used one by one, or a plurality of catalyst materials may be mixed and used. In the trap 5 configured as above, when the exhaust gas enters from the exhaust gas inflow surface 20a, the exhaust gas passes through the wall surface of the honeycomb structure 20. Captured by 20.

The two-dimensional structure 7 atomizes (disaggregates) large particles (aggregated particles) in the exhaust gas. The two-dimensional structure 7 is, for example, a net-like plate-shaped structure or a plate-shaped structure having a plurality of through holes. Further, as the constituent material, alumina, mullite, cordierite, silicon carbide, lanthanum chromite composite oxide is used. Objects, ceramics such as titanium oxide, and Fe-Cr-Al alloys (for example, SUS-42, S
A metal material such as US-43, SUS-301S) or Inconel is used.

The two-dimensional structure 7 traps large particles in the exhaust gas in fine holes, and the captured large particles are generated by the pressure difference between the exhaust gas inflow surface and the exhaust gas outflow surface of the two-dimensional structure 7. It is finely broken down by force and becomes fine particles. Such fine particles are guided to the trap 5 from the two-dimensional structure 7 and are captured by the trap 5. In addition to the production of fine particles by physical destruction as described above, the oxidation catalyst is supported on the two-dimensional structure 7 and the captured large particles are burned to some extent to make the large particles fine and produce the fine particles. Further, the two-dimensional structure 7 may be formed by laminating a plurality of structures, and in this case, the mesh diameter and the like of each structure are different, and moreover, the exhaust gas inflow side goes to the outflow side. The mesh diameter of the structure is configured to be small. When the oxidation catalyst is supported on the two-dimensional structure 7, the two-dimensional structure 7 may be energized to generate heat in order to improve the activity of the supported oxidation catalyst.

In this embodiment, the electric heater 6 is provided on the exhaust gas inflow side, but the electric heater 6 may be wound around the side surface of the trap 5 or inserted into the trap 5.
Further, although the electric heater 6 is used as the heating means in this embodiment, a burner, a hot air generator, or the like may be used. As the electric heater 6, a sheath heater, a micro heater, or a ceramic heater (for example, one using silicon carbide or one using lanthanum chromite complex oxide) may be used.

Reference numeral 10 is a pressure detection sensor for detecting the pressure of the exhaust gas in the exhaust pipe 3. As the pressure detection sensor 10, for example, a sensor whose output level is high in proportion to the pressure is used. Reference numeral 11 denotes a temperature detection sensor that detects the temperature of the trap 5. As the temperature detection sensor 11, a sensor that increases the level of a signal output in proportion to the temperature is used.

Reference numeral 12 is a control unit, and the control unit 12 inputs the output levels of the pressure detection sensor 10 and the temperature detection sensor 11 and supplies electric power to the electric heater 6.

The operation of the control unit 12 will be described below with reference to FIG. FIG. 3 is a flowchart showing a part of the processing performed by the control unit 12.

The control section 12 first monitors the output level from the pressure detection sensor 10 in step (hereinafter abbreviated as S) 1. When the output level exceeds a predetermined value, the process proceeds to S2,
If it is below the predetermined level, the process returns to S1. At this time, since the predetermined value differs depending on the engine characteristics and the characteristics of the exhaust gas filter, it must be selected appropriately.

The above state will be specifically described. When particulates are trapped in the trap 5, the exhaust pipe 3
Focusing on the fact that the pressure of the exhaust gas inside increases, the clogging degree of the trap 5 is measured using the pressure of the exhaust gas inside the exhaust pipe 3.

Next, when it is detected that the pressure in the exhaust pipe 3 exceeds a predetermined value, the control unit 12 supplies electric power to the electric heater 6 to heat the two-dimensional structure 7 and the trap 5, etc. The particulates and the like accumulated in the body 7 and the trap 5 are burned (S2).

Next, in S3, the output level from the temperature detection sensor 11 is monitored, and if the output level is above a predetermined value, S
4, the process proceeds to S5 if it is less than or equal to the predetermined value. In this embodiment, the predetermined value indicates a value corresponding to 500 ° C. In S4, the electric power supplied to the electric heater 6 is saved (the electric power supplied to the electric heater 6 by the control unit 12 is reduced), and the process returns to S3. In S5, it is monitored whether the output level from the pressure detection sensor 10 is equal to or higher than a predetermined value.
If it is equal to or larger than the predetermined value, the process returns to S3.

In S6, the supply of electric power to the electric heater 6 is stopped and the process returns to S1. The above operation will be specifically described.

First, by supplying electric power to the electric heater 6, the particulates and the like adhering to the trap 5 are burned and the temperature of the trap 5 rises. The temperature of the trap 5 at the time of combustion is controlled so as not to exceed 500 ° C. That is, in the past, since the electric heater was simply supplied with a constant electric power to burn particulates and the like in the trap, the temperature of the trap may rise to 700 ° C. or higher, causing cracks and the like in the trap. In contrast to this, in the present embodiment, since the electric power supplied to the electric heater 6 is controlled so that the temperature of the trap 5 becomes 500 ° C. or less during the combustion of particulates, cracks or the like do not occur in the trap 5. . In this embodiment, the electric power supplied to the electric heater 6 is controlled so that the temperature of the trap 5 at the time of combustion is 500 ° C. or lower, but other methods such as using a cooling means may be used.

Further, in this embodiment, the particulates and the like adhering to the trap 5 were simultaneously burned during the operation of the engine. However, as shown in FIG. Although not shown in the drawing, the same thing as the exhaust gas purifying device provided at the end of the passage 102 is provided at the tip of the passage). Passage 10
When the passage selector selects the passage so as to flow through the passage 2, when the trap 5 is clogged and the pressure of the exhaust pipe 3 increases, the passage selector operates so that the exhaust gas flows into the passage 100. Then, the exhaust gas flows into the exhaust gas purifying device provided at the end of the passage 100 to remove particulates and the like. Further, the exhaust gas purifying device provided at the end of the passage 102 controls the combustion temperature of the trap 5 so as not to exceed 500 ° C. to remove particulates and the like adhering to the trap 5. Similarly, when the exhaust gas is being passed through the passage 100 and the trap 5 is clogged and the pressure of the exhaust pipe 3 is increased, the passage selector operates so that the exhaust gas flows into the passage 102.

By alternately regenerating the trap 5 and burning the trap 5 as described above, it is possible to continuously purify the exhaust gas.

By adjusting the electric power supplied to the electric heater 6 in this way, the temperature of the trap 5 is kept at 500 when burning the particulates and the like adhering to the trap 5.
Since the temperature did not exceed 0 ° C., the probability that the trap 5 was cracked or chipped was extremely reduced.

A specific experimental example will be described below.
First, each member was manufactured as follows.

The honeycomb structure 20 is an alumina-silica system.
Ceramic fiber (Al₂ O₃ / SiO₂ = 47.3 / 5
2.3) and sericite clay (K₂ O / Al₂ O₃ / S
iO ₂ = 1/5/18) as a raw material
And then laminated to form a corrugated honeycomb structure
It was produced by firing in air at 1250 ° C. for 2 hours.

The catalyst supported on the honeycomb structure 20 is A
(Pt / γ-Al ₂ O ₃ ), B (LaSrCoO ₃ ),
Three types of C (LaCrLiO ₃ ) were used.

As the catalyst A, commercially available γ-Al ₂ O ₃ (specific surface area 120 m ² / g) is wet granulated to form a slurry, and the honeycomb structure 20 is dipped to remove excess slurry, dried and fired, An alumina-coated three-dimensional construct is obtained. Hexachloroplatinate was dissolved in distilled water so as to be 0.6 wt% with respect to γ-Al ₂ O ₃ , and the alumina-coated three-dimensional construct was immersed in the alumina-coated layer by ion exchange. After chemisorption, dry the solvent,
Next, a trap 5 was prepared by firing in hydrogen at 550 ° C. for 1 hour.

As catalyst B, lanthanum acetate, strontium acetate and chromium nitrate were used, and the molar ratio of each metal was 0.8:
Weighed so as to be 0.2: 1.0 and dissolved in warm water of about 60 ° C. to prepare an aqueous solution. Next, the water content of this aqueous solution was evaporated by a rotary evaporator to concentrate the metal salt and then dried and solidified on a hot plate to prepare a catalyst precursor. Further, this is calcined at 400 ° C to 500 ° C for 2 hours, and is pulverized by mixing with a ball mill for 4 hours by dry rotation to pulverize and mix the aggregates, and then calcined in air at 900 ° C for 5 hours to obtain the target composite oxidation. A fine powder was prepared. Next, 30 wt% of the synthesized complex oxide was added to an aqueous solution in which 0.4 wt% of the complex oxide was dissolved using ammonium polycarboxylic acid salt as a dispersant, and mixed and dispersed by a ball mill for 15 hours. A complex oxide fine powder slurry was prepared. An aqueous solution in which a polycarboxylic acid ammonium salt was separately dissolved so as to have the same concentration as this slurry was prepared, and the slurry was diluted with this aqueous solution. After the honeycomb structure 20 was impregnated therein, the honeycomb structure 20 was dried at 120 ° C. for a whole day and night, and further baked at 800 ° C. for 20 minutes in the air to prepare a trap 5.

As catalyst C, lanthanum acetate, chromium nitrate and lithium acetate were used, and the molar ratio of each metal was 1.0: 0.
It was weighed so as to be 6: 0.4, and prepared by the same method as the catalyst B below to prepare a trap 5.

The two-dimensional structure 7 is a reticulated Fe-Cr-Al.
The alloy was made as the main material. An ordinary sheathed heater was used as the electric heater 6, and the electric heater 6 was placed at a distance of 5 mm from the end surface of the trap 5.

A commercially available heat-expandable ceramic (for example, Sumitomo 3M Interlamt) made of ceramic fibers and a heat-expanding agent (such as vermiculite) is used as the heat-insulating material 8, and a general heat-insulating material 9 is used. A ceramic heat insulating material was used.

The trap container 4 contains a heat-resistant metal (SUS-3
01S) was used. As described above, the trap 5 supporting the catalysts A, B, C and the trap 5 not supporting the catalyst were prepared, and the temperature at which the particulates ignite were measured in the device equipped with them, and further The control temperature of the trap 5 was set respectively. Then, with respect to each sample, it was examined whether the trap 5 was broken and whether particles such as particulates remained.

The ignition temperature of the particles during regeneration was examined by collecting the gas in the downstream of the trap 5 and using a gas analyzer (oxygen, carbon monoxide, carbon dioxide sensor).

The presence or absence of particles was examined by the change in weight before and after collection and the amount of oxygen consumed and the amount of carbon monoxide and carbon dioxide produced by the gas analyzer.

The diesel engine was operated for 30 minutes at 3000 cc, a rotation speed of 1200 rpm and a torque of 20 kgm, and was collected until the back pressure reached 400 mmaq.

The presence or absence of cracks in the trap 5 was determined by installing a smoke meter in the downstream of the trap 5 and examining the presence or absence of particulates flowing out from the trap 5.

The above results are shown in (Table 1).

[0049]

[Table 1]

As can be seen from Table 1, the control temperature is 50
It was found that no crack was generated in the trap 5 when the temperature was 0 ° C or lower. Further, it was found that particulates did not remain in the trap 5 when B and C were used as the catalyst.

Also, in this experiment, the power consumption at the time of reproduction of each of the heat insulating materials 8 and 9 provided and the heat insulating material not provided was measured to be 0.16.
The value is kWh and the heat insulating materials 8 and 9 are not provided.
It was 20 kWh. That is, by providing the heat insulating material, the heat retaining effect is improved and the power consumption can be reduced.

As described above, when burning the particulates adhering to the trap 5, the combustion temperature is set to 500 ° C.
By the following, the probability that the trap 5 will be melt-damaged, cracked or chipped will be extremely reduced. That is, even if the temperature exceeds 500 ° C., the trap 5 may not be cracked or chipped, but if the temperature is controlled to 500 ° C. or less, the trap 5 will not be cracked or chipped.

Another embodiment will be described below. The above-described embodiment reduces the probability of chipping of the trap 5 by controlling the temperature of the trap 5 itself not to exceed 500 ° C. when burning the particulates and the like adhering to the trap 5. However, in other embodiments,
By regulating the temperature gradient of the trap 5 in the radial direction, chipping of the trap 5 and the like are prevented. Ie 5
Even when the trap 5 is regenerated at a temperature of 00 ° C or lower, cracks or cracks may occur if the temperature gradient is large (probability is low), and if the temperature gradient is small even at 500 ° C or higher, cracks or cracks may not occur. (Probability is low).

More specifically, when burning the particulates adhering to the trap 5, it is necessary to set the temperature gradient in the radial direction to 10 ° C./mm or less. As means for achieving this temperature gradient, for example, heaters may be arranged outside and inside the trap 5, and a combustion system using hot air may be used.

FIG. 4 is an experimental conceptual diagram when the temperature gradient of the trap is measured. 5 is a trap, 22 is an exhaust gas outflow surface, and 20a is an exhaust gas inflow surface. As shown in FIG. 4, three thermocouples (T1, T2, T3) were linearly arranged at intervals of 22 mm in the radial direction on the side of the exhaust gas inflow surface 20a, and further separated by 65 mm in the length direction. In the same way, in the radial direction, thermocouples in the radial direction at intervals of 22 mm 3
The points (T4, T5, T6) are arranged linearly. At this time, (T4, T5, T6) is arranged on an inclined line inclined by 120 degrees with respect to (T1, T2, T3). Furthermore, three points (T4, T5, T6) at a distance of 22 mm in the radial direction at a position 65 mm away from the length direction (T
7, T8, T9) are arranged linearly. At this time (T7,
(T8, T9) are arranged on an inclined line inclined by 120 degrees with respect to (T4, T5, T6).

By the thermocouple arranged as described above,
T1 and T2, T2 and T3, T4 and T5, T5 and T6, T
The temperature difference between 7 and T8 and T8 and T9 was measured, and the maximum temperature difference was measured in each of the following samples, and the maximum temperature difference was divided by 22 mm to obtain the temperature gradient. For example, when the temperature difference between T7 and T8 is the largest among the measured temperature differences and is 220 ° C., the maximum temperature difference is 220 ° C./22 mm = 10 ° C./mm.

Furthermore, the degree of damage of the trap 5 is
The rate of decrease in natural frequency is shown. The larger the rate of decrease in natural frequency is, the more cracks and chips are generated.

As a result of the experiment, the maximum temperature gradient is 30 ° C./mm
In the case of, the natural frequency decrease rate was reduced by 40%, and the trap 5 almost no longer functions. Similarly, when the maximum temperature gradient is 15 ° C./mm to 20 ° C./mm, the natural frequency decrease rate is reduced by 10% to 20%, and the characteristics of the trap 5 are deteriorated. Furthermore, when the maximum temperature gradient was 10 ° C./mm or less, the natural frequency decrease rate did not change.

As described above, the maximum temperature gradient is 10 ° C./mm
The following will prevent the trap 5 from cracking.

In the most preferred embodiment, the trap 5
The temperature at the time of burning the particulates adhering to is set to 500 ° C. or less, and the combustion is controlled so that the maximum temperature gradient becomes 10 ° C./mm or less, so that the trap 5 is hardly cracked. .

[0061]

As described above, according to the present invention, the trap can be regenerated after the particulates are collected without being damaged by cracking, melting, and the like, and the energy required for regeneration can be minimized. Therefore, it is possible to obtain a practically extremely effective effect for trap regeneration after trapping, which has been a problem in the past, such as improvement in system efficiency.

[Brief description of drawings]

FIG. 1 is a schematic view showing an exhaust gas purifying apparatus according to an embodiment of the present invention.

FIG. 2 is a side sectional view showing a trap of an exhaust gas purifying apparatus according to an embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the control unit of the exhaust gas purification device in one embodiment of the present invention.

FIG. 4 is an experimental conceptual diagram when measuring the temperature gradient of the trap.

[Explanation of symbols]

 4 Trap Container 5 Trap 6 Electric Heater 8, 9 Thermal Insulation Material 11 Temperature Detection Sensor 12 Control Section 20 Honeycomb Structure 24 Oxidation Catalyst

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shoji Kuroda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (24)

[Claims] 1. A method for purifying exhaust gas, wherein particulates, etc. in exhaust gas are collected by a trap, and when a predetermined amount of particulates, etc. are collected by the trap, the particulates, etc. adhering to the trap are burned. An exhaust gas purification method, characterized in that the trap temperature at the time of burning particulates or the like attached to the trap is set to 500 ° C. or lower. 2. A method for purifying exhaust gas according to claim 1, wherein a ceramic honeycomb structure is used as the trap. 3. The exhaust gas purification method according to claim 1, wherein the trap carries an oxidation catalyst. 4. A particulate matter or the like in the exhaust gas is collected by a trap, and when a predetermined amount of particulate matter or the like is collected in the trap, the trap is heated by a heating means to adhere to the trap. An exhaust gas purification method for burning particulates and the like, in which the energy input to the heating means is controlled so that the temperature of the trap when burning particulates and the like adhering to the trap does not exceed 500 ° C. A characteristic exhaust gas purification method. 5. The exhaust gas purification method according to claim 4, wherein a ceramic honeycomb structure is used as the trap. 6. The exhaust gas purification method according to claim 4, wherein the trap carries an oxidation catalyst. 7. The exhaust gas purifying method according to claim 4, wherein the heating means is a means for directly heating with an electric heater or a means for blowing hot air heated by the electric heater onto the trap. 8. An exhaust gas purification method in which particulates and the like in exhaust gas are collected by a trap, and when a predetermined amount of particulates and the like are collected in the trap, the particulates and the like adhering to the trap are burned. The exhaust gas purification method is characterized in that the maximum temperature gradient in the radial direction of the trap when burning particulates or the like attached to the trap is 10 ° C./mm or less. 9. The exhaust gas purification method according to claim 8, wherein a ceramic honeycomb structure is used as the trap. 10. The exhaust gas purification method according to claim 8, wherein the trap carries an oxidation catalyst. 11. A trap collects particulates and the like in the exhaust gas, and when a predetermined amount of particulates and the like is trapped in the trap, the trap is heated using a heating means and adheres to the trap. An exhaust gas purification method for burning particulates and the like, wherein the maximum temperature gradient in the radial direction of the trap when burning particulates and the like adhering to the trap does not exceed 10 ° C / mm An exhaust gas purification method characterized by controlling input energy. 12. The exhaust gas purifying method according to claim 11, wherein a ceramic honeycomb structure is used as the trap. 13. The exhaust gas purification method according to claim 11, wherein the trap carries an oxidation catalyst. 14. A heating means for directly heating with an electric heater, or a means for blowing hot air heated by the electric heater to a trap is used.
Exhaust gas purification method described. 15. An exhaust gas purification method in which particulates and the like in exhaust gas are collected by a trap, and when a predetermined amount of particulates and the like are collected in the trap, the particulates and the like adhering to the trap are burned. And
An exhaust gas purification method characterized in that the trap temperature when burning particulates adhering to the trap is set to 500 ° C. or lower and the maximum temperature gradient in the radial direction of the trap is set to 10 ° C./mm or lower. 16. The exhaust gas purification method according to claim 15, wherein a ceramic honeycomb structure is used as the trap. 17. The exhaust gas purification method according to claim 15, wherein the trap carries an oxidation catalyst. 18. A trap for collecting particulates and the like in exhaust gas, a trap container for housing the trap, and a case for burning the particulates and the like contained in the trap container and adhering to the trap. When heating the trap, the temperature measuring means for measuring the temperature of the trap, and the burning of the trap based on the information from the temperature measuring means when burning the particulates adhering to the trap by the heating means. An exhaust gas purifying device, characterized in that a control means for controlling the energy input to the heating means is used so that the temperature of the above does not exceed 500 ° C. 19. The exhaust gas purifying apparatus according to claim 18, wherein an electric heater is used as the heating means, and the controller controls the electric power supplied to the electric heater. 20. The exhaust gas purifying apparatus according to claim 18, wherein a heat insulating material is provided on either the side surface of the trap or the side surface of the trap container. 21. A trap for collecting particulates and the like in exhaust gas, a trap container for housing the trap, and a case for burning particulates and the like housed in the trap container and adhering to the trap. When heating the trap, the temperature measuring means for measuring the temperature of the trap, and the burning of the trap based on the information from the temperature measuring means when burning the particulates adhering to the trap by the heating means. 2. An exhaust gas purifying apparatus using control means for controlling the energy input to the heating means so that the maximum temperature gradient of the trap in the radial direction is 10 ° C./mm or less. 22. The exhaust gas purifying apparatus according to claim 21, wherein an electric heater is used as the heating means, and the controller controls the electric power supplied to the electric heater. 23. The exhaust gas purifying apparatus according to claim 21, wherein a heat insulating material is provided on either the side surface of the trap or the side surface of the trap container. 24. A trap for collecting particulates and the like in exhaust gas, a trap container for housing the trap, and a case for burning particulates and the like housed in the trap container and adhering to the trap. When heating the trap, the temperature measuring means for measuring the temperature of the trap, and the burning of the trap based on the information from the temperature measuring means when burning the particulates adhering to the trap by the heating means. The exhaust gas is characterized in that the control means for controlling the energy input to the heating means is used so that the temperature of the trap does not exceed 500 ° C and the maximum temperature gradient in the radial direction of the trap is 10 ° C / mm or less. Purification device.