JPH086579B2 - Diesel exhaust gas purification equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a diesel engine having a function of capturing particulate matter such as soot discharged from a diesel engine to purify exhaust gas, and oxidizing the filter to regenerate the filter. Regarding exhaust gas filters.

2. Description of the Related Art In recent years, the particulate matter emitted from a diesel engine is about to be regulated, and as a countermeasure against this, a method of mounting a heat resistant filter in the middle of an exhaust pipe is being studied. A feature of this method is that after depositing the particulates, the particulates are incinerated to regenerate the filter, and the filter is repeatedly used. As one of the regeneration methods, a burner is provided on the upstream side of the exhaust gas flow of the filter to increase the exhaust gas temperature to the ignition temperature of the particulate by the combustion heat. In this method, the temperature of a large amount of exhaust gas from the engine must be raised, and a huge amount of heat is required. In order to solve this, for example, in JP-A-56-118514, a bypass separate from the filter is provided by branching the exhaust gas path, and the exhaust gas from the engine is caused to flow into the bypass by a valve when the burner is operating, and a large amount of The thing which eliminated the need to heat exhaust gas is described.

Further, JP-A-61-244813 discloses a purifying device comprising a filter carrying a catalyst, a burner, and an air supply device, which is supplied to increase exhaust gas and oxygen concentration from an engine. This is a system in which the generated air is heated by a burner up to the ignition temperature of the catalyst for regeneration.

Problems to be Solved by the Invention In JP-A-56-118514, exhaust gas is exhausted to the atmosphere through a bypass at the time of regeneration, and the particulate emission suppression effect is halved.

Further, in the method described in JP-A-61-244813, even if the ignition temperature of the particulates is reduced by the effect of the catalyst carried on the filter, not only the exhaust gas but also the supplied air is not heated. However, as mentioned above, a large amount of combustion is required, which is not economical.

The present invention suppresses the combustion amount of the burner to a small amount without discharging particulates during regeneration,
It is an object of the present invention to provide an exhaust gas purification device that is highly economical.

Means for Solving Problems Platinum group metal catalyst in the form of corrugated honeycomb obtained by firing heat resistant inorganic fiber and ceramic raw material powder
Alternatively, a plurality of films carrying a base metal oxide catalyst are provided, and when the filter needs regeneration, the exhaust gas flow is blocked by a valve and the burner heats the filter, while the exhaust gas containing particulates is It is configured to flow through the filter.

Operation In the above configuration, the operation is as follows.

The exhaust gas flow from the engine flows evenly through the plurality of filters, is free of particulates, is purified and is released to the atmosphere. Next, in the filter where particulates were deposited and regeneration was necessary,
First, the exhaust gas flow is interrupted, and then the burner starts combustion to supply the heated gas set to the required temperature to the filter. A platinum group metal catalyst and a base metal group oxidation catalyst are supported on the filter to enable particulate oxidation at a low temperature. Therefore, the temperature of the heating gas can be set low and the combustion amount of the burner can be suppressed low, so that the regeneration can be economically performed.

Examples Examples of the present invention will be described below.

The accompanying drawings show an embodiment of the present invention, in which a burner
1 comprises a fuel atomizing nozzle 2, a stabilizer 3, a spark plug 4, and a fuel air supply port 5. Fuel atomizing nozzle 2
Has an atomizing air supply port 6 and a fuel supply port 7, which are connected to an air pump (not shown) and an oil pump (not shown), respectively. The combustion air sent from the combustion air supply port 5 surrounds the fuel atomizing nozzle 2 in a ring shape, and is arranged so that it can be ejected from the stabilizer 3 spreading in a funnel shape in front of it. Spark plug 4
Is exposed to the vicinity of the fuel atomizing nozzle 2 and is connected to a high pressure trunk (not shown).

In front of the burner 1 , an air introduction port 9 for ejecting the air supplied to dilute the temperature of the combustion gas from the addition air supply port 8 is provided, and a combustion chamber 10 is connected thereto. Combustion chamber
The other end of 10 facing the burner 1 is open to the four-way valve 11.

The four-way valve 11 has an elliptical vane 13 housed in a cylinder 12, and is rotated by a motor 14 attached to the outside to switch the flow path. Cylinder 12 has a vane
The heating gas inlet 15 for introducing the heating gas from the combustion chamber facing the 13, the exhaust gas inlet 16 for introducing the exhaust gas from the engine behind the vane 13, the exhaust gas and the heating gas facing the sliding surface of the vane 13 Outlet 17-a, which leads the
b is provided.

Connection pipes 18-a and b are attached to the outlets 17-a and b, and are connected to the cases 19-a and b.
Is connected so as to guide the exhaust gas or the heating gas onto the stored filters 21-a, b whose outer circumference is wrapped with the cushioning material 20-a, b that expands by heating, and the exhaust gas outlet of the case 19-a, b. On the side, an outlet cover 22 that collects both exhaust gases is provided.

On the other hand, the filters 21-a, b have a corrugated honeycomb structure having a fiber-ceramic skeleton made of a sintered body of aluminosilicate fibers and ceramic raw material powder as a honeycomb cell 23.
A filter obtained by alternately closing the plugs 24 with the openings is washed-coated with alumina whose part is Cu (AlO ₂ ) ₂ and then loaded with CuO and further loaded with platinum. By mixing 10 parts by weight of δ-alumina and 0.5 part by weight of CuO and heating at 850 ° C., a part of δ-alumina was converted to C
A washcoat material containing u (AlO ₂ ) ₂ was obtained. After 10.5 parts by weight of this wash coat material was wash-coated on a filter of 100 parts by weight, a slurry of 1.5 parts by weight of CuO suspended in 150 parts by weight of water was impregnated into the filter. Furthermore, 0.2 parts by weight of H ₂ [PtCl ₆ ] .6H ₂ O was added to ethyl alcohol.
The solution obtained by dissolving 70 parts by weight was impregnated in the filter obtained above, dried, and heat-treated at 800 ° C. to obtain filters 21-a and 21-b.

 Next, the operation of the configuration of this embodiment will be described.

During normal operation of the diesel engine, the line connecting the opposing outlets 17a, 17b and the elliptic single-diameter axis of the elliptical vane 13 are parallel, that is, the vane 13 is in the neutral position and the entire cylinder 12 is in the neutral position. The opening is in communication. At this time, the exhaust gas from the engine enters the cylinder 12 through the exhaust gas introduction port 16, is divided into two parts from the outflow ports 17-a, b, and reaches the filter 21-a, b through the connecting pipes 18-a, b, respectively. Here, the particulates contained in the exhaust gas are separated by the wall of the cell 23 opened on the inlet side and deposited. The filtered exhaust gas becomes clean gas and is discharged through the outlet cover 22.

Next, a case will be described in which particulate matter is deposited on the filters 21-a and 21-b and regeneration is necessary.

First, when the motor 14 is energized and the vane 13 rotates 90 degrees, the combustion chamber 10 communicates with the filter 21-a, and the other filter
21-b is cut off from the combustion chamber 10 and, at the same time, all the exhaust gas comes in. When a high voltage is applied to the spark plug 4 and electric discharge starts at the tip, fuel and atomizing air are supplied from the fuel supply port 7 and atomizing air supply port 6, respectively, and atomized by the atomizing nozzle 2 toward the combustion chamber 10. To be done. At this time, the atomized fuel is ignited by the spark plug 4 and mixed with the air supplied from the combustion air supply port 5 and passing through the stabilizer 3 to form a flame and burn. On the other hand, the air sent from the additive air supply port 8 to the combustion chamber 10 through the air introduction port 9 mixes with the high temperature combustion gas in the combustion chamber 10 and is rich in oxygen and passes through the four-way valve as a temperature-controlled heating gas. It is sent to the filter 21-a. Here, when the temperature and the temperature at which the catalyst and the filter 21-a are heated by the heated gas reaches 500 ° C., the particulate is oxidized and gradually decreases. The gas generated by the oxidation of the particulates is discharged from the outlet cover 22 together with other gases.

During this period, the exhaust gas from the engine is passing through the filter 21-b, and the particulates are continuously filtered.
When the regeneration is completed by the filter 21-a, the vane 13 is rotated 180 degrees to connect the combustion chamber 10 to the filter 21-b and the exhaust gas from the engine is filtered by the filter 21-a.
Introduce it to a and have it pass through the particulates. In the filter 21-b, as in the case of the filter 21-a described above, the regeneration proceeds, and when the regeneration is completed, the combustion of the burner 1 is stopped and the vane 13 is returned to the original neutral position by rotating the vane 90 by 90 degrees. Becomes

As described above, the diesel engine exhaust gas filter according to the present embodiment normally operates two filters at the same time, so that the diesel engine exhaust gas filter can be operated with a very low back pressure without burdening the engine. On the other hand, at the time of regeneration, one is regenerated and all the exhaust gas is made to flow to the other to act as a filter, so the exhaust gas from the engine always passes through the filter and is filtered through particulates.

When using a filter that does not support a catalyst, at least 600 ° C or higher, usually 700 ° C, during regeneration.
It had to be heated to a degree. However, Cu as a catalyst
In the filters 21-a, b supporting (AlO ₂ ) ₂ , CuO, and Pt, oxidation of particulates is promoted and at least 470
Regeneration proceeds by heating to ℃, usually 500 ℃, so the amount of heat of the heating gas may be extremely small. In addition, in this embodiment, the temperature is controlled by mixing air into the combustion gas of the burner from the air inlet 9, and stable regeneration can be performed. Furthermore, the skeleton of the filter supporting the catalyst is made of fiber ceramic,
Since the porosity of the cell wall is 80%, the heat quantity of the heating gas, that is, the burner combustion quantity can be further reduced.

The above embodiment is composed of a burner, two catalyst-carrying filters, and a four-way valve. During normal operation and regeneration, the exhaust gas from the engine and the heating gas obtained by combustion of the burner and the four-way valve are used for switching. The thing that makes the operation of is shown. However, even if two or more filters are used, the effect of the present invention will not be impaired as long as the flow paths are sequentially switched by valves.

In the embodiment, both the two filters are used during normal operation, and the engine can be operated at a very low back pressure, so that the engine efficiency can be maintained high, and the unpurified exhaust gas cannot be released to the atmosphere during regeneration. It is a device. Also, during regeneration, the exhaust gas from the engine and combustion gas from the burner are shut off by the four-way valve, so the exhaust gas is not heated, and the catalyst is supported by a filter with a smaller heat capacity, and the oxidation temperature of the particulates is low. Therefore, the burner can be remarkably downsized, and a large amount of fuel can be saved. The filter supports Cu (AlO ₂ ) ₂ , CuO, and Pt as catalysts, and the temperature required for the oxidation of the particulates can be 500 ° C, so there is no need to expose the filter to high temperatures, and the filter is not damaged or melted. It does not cause damage, is durable and safe.

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide an exhaust gas purifying apparatus that suppresses the burner combustion amount to a small amount without discharging particulates during regeneration and is excellent in economic efficiency.

[Brief description of drawings]

FIG. 1 is a cross sectional view of a diesel exhaust gas purifying apparatus according to an embodiment of the present invention. 1 ... Burner, 8 ... Addition air inlet, 9 ... Air inlet, 10 ... Combustion chamber, 11 ... Four-way valve, 13 ... Vane, 18-a, b ... Connecting pipe, 19- a, b …… Case, 21−a, b
…… Filter, 22 …… Outlet cover.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masudao Takigawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Toshihiro Mihara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-57-79209 (JP, A) JP-A-60-184917 (JP, A) JP-A-61-57223 (JP, A)

Claims (3)

[Claims] 1. A plurality of filters installed in an exhaust gas path of a diesel engine for collecting particulates in exhaust gas, and a heating gas for oxidizing and removing the collected particulates to regenerate the filter. Shut off the burner and the regenerating filter from the exhaust gas flow, and
A diesel exhaust gas purifying apparatus comprising a valve for guiding an exhaust gas flow to another filter, wherein the filter is a corrugated honeycomb filter obtained by sintering aluminosilicate heat-resistant fiber and ceramic raw material powder, and oxidizing the particulates. Cu, a platinum group metal that reduces temperature
A diesel exhaust gas purification apparatus, characterized in that a catalyst composed of a base metal oxide such as CuO containing (AlO ₂ ) ₂ is carried. 2. The diesel exhaust gas purifying apparatus according to claim 1, wherein the platinum group metal of the catalyst is platinum. 3. A washcoat of alumina, a part of which is Cu (AlO ₂ ) _2, is applied.
The diesel exhaust gas purification apparatus according to the item.