JP2539105B2 - How to play soot removal filter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention captures fine particles containing carbon as a main component in exhaust gas and burns and removes soot composed of deposited fine particles to regenerate the filter. The present invention relates to a method for regenerating a ceramic honeycomb filter that removes soot.

[0002]

2. Description of the Related Art Conventionally, as a diesel particulate filter comprising a ceramic honeycomb filter, a diesel particulate filter having a structure in which one end of a ceramic filter is alternately sealed is known in, for example, Japanese Patent Laid-Open No. 56-129020. . In such a diesel particulate filter, the pressure loss of the filter increases significantly as particulates accumulate on the filter,
As a result, the performance of the engine deteriorates, so it was necessary to burn and remove the accumulated particulates to regenerate the filter. As a combustion regeneration method of soot composed of deposited fine particles, a regeneration method using an electric heater having a simple, low cost and high reliability is widely known.

[0003]

However, in the above-described conventional regeneration method, it is necessary to perform regeneration by burning and removing soot at a stage of a small amount of accumulated soot in order to prevent damage to the filter. However, in order to regenerate it, there is a problem that a large amount of combustion air must be supplied to the filter and heated by an electric heater to regenerate it. Therefore, there is also a problem that a slight variation in the amount of soot accumulated causes a rapid rise in temperature due to the heat of combustion, which causes damage or melting of the filter due to thermal shock. Further, there is a problem that the reproduction must be performed frequently because the reproduction is performed at a small soot amount stage.

The object of the present invention is to solve the above problems,
An object of the present invention is to provide a method for regenerating a soot removal filter that requires a small amount of air supply and requires a small number of regenerations.

[0005]

The method for regenerating a soot removing filter according to the present invention is a method for regenerating a soot removing filter which burns and removes soot mainly composed of carbon fine particles, and the accumulated soot amount is 10 g or more per liter of the filter. In the presence of, a small amount of air in the range of 2 l / min to 15 l / min is fed to the filter,
It is characterized by removing soot while controlling its combustion.

[0006]

The fine particles deposited on the filter are mainly composed of carbon, and the following reactions occur during the regeneration. C + O ₂ → CO ₂ + Q Q: Combustion energy Here, C is soot and O ₂ is oxygen for combustion. As can be seen from the above equation, an oxygen amount proportional to the accumulated soot amount is required. Then, by increasing the oxygen amount in proportion to the accumulated soot amount, the combustion energy also increases in proportion. Here, the combustion energy is normally used for combustion propagation of soot and is necessary energy, but if it is too large, the filter will be melted and damaged. In the present invention, attention is paid to oxygen for combustion in the above formula, that is, air, and combustion is performed stably (stable combustion propagation) by supplying a minute amount of air with respect to the soot accumulation amount, and the unit time of combustion energy is By preventing a significant increase in hits, the filter is prevented from being melted or damaged. That is, according to the present invention, under the condition that the deposition amount is 10 g or more per liter of the filter, and the conventional technique causes excessive combustion energy, the filter is eroded from one end on the exhaust gas inlet side. Ignite the soot accumulated by the source,
By supplying minute air in the range of 2 liters / minute to 15 liters / minute to the filter and gradually continuing combustion to the other end of the filter, the combustion energy generated per unit time is suppressed and a stable filter is provided. Can be regenerated (combustion propagation). The stable regeneration of the filter corresponds to maintaining the temperature of the filter at 1000 ° C. or lower at which the filter is not melted and 600 ° C. or higher at which the soot completely burns. Also, when regenerating, to collect a larger amount of soot than usual, it is possible to extend the regeneration interval of the filter,
The number of playbacks can be reduced.

That is, according to the present invention, since the soot amount is extremely increased, the combustion propagation of the soot is improved, and even if the combustion air flow rate is extremely small, the combustion is stably propagated. Regeneration of the ceramic honeycomb filter can be performed by good combustion removal of soot. Further, since the air flow rate is extremely low, soot combustion proceeds extremely slowly, and thus an excessive temperature rise is not observed. Therefore, in the present invention, the conventional limit soot amount is about 4 g /
Even at 30 g / l, which is 7 times as much as about 1 liter, regeneration can be safely performed without causing filter damage.

In the present invention, the soot accumulation amount for regenerating is specified to be 10 g / l or more. When the soot accumulation amount is less than 10 g / 1 in the air flow rate of the present invention, soot residue may occur. Because there is. Further, the air flow rate is defined as 2 to 15 liters / minute because the filter may be damaged when the air flow rate exceeds 15 liters / minute in the soot accumulation amount of the present invention, and the air flow rate is 2 liters / minute. This is because if it is less than the range, combustion of soot may disappear in the middle of the process and regeneration may become impossible.

[0009]

EXAMPLE FIG. 1 is a diagram showing the cross-sectional structure of a diesel particulate filter comprising a ceramic honeycomb filter to which the regeneration method of the present invention is applied. In FIG. 1, 1 is a partition wall of a ceramic honeycomb filter made of, for example, cordierite, 2 is an inlet side closed portion that closes one end of a cell,
3 is an outlet-side closed portion that closes the other end of the cell, and 4 is a through hole. In the diesel particulate filter having the above-mentioned configuration, the exhaust gas containing the particulates mainly made of carbon is introduced into the filter from the inlet side, the particulates are captured when passing through the partition wall 1, and discharged to the outlet side. Fine particles are removed. As a result, soot is deposited on the partition wall 1.

FIG. 2 is a diagram showing the construction of an electric heater system incorporating a ceramic honeycomb filter having the structure shown in FIG. 1. The regeneration of the present invention is carried out in the state shown in FIG. Of course, even when actually mounted on the vehicle, it can be mounted in the state shown in FIG. In FIG.
11 is an electric heater, 12 is a ceramic honeycomb filter, and 13 is a holder. A ceramic honeycomb filter to be regenerated with a predetermined soot amount is set in the state shown in FIG. 2, heated to a predetermined ignition temperature by the electric heater 11, and a predetermined flow rate of air is supplied from the inlet side to carry out the operation described later. As is clear from the example, the soot is satisfactorily burned off and the filter is regenerated. The electric heater may have a conventionally known constitution, for example, the electric heater disclosed in Japanese Utility Model Publication No. 63-6605 can be used.

Hereinafter, an actual example will be described. Example A ceramic honeycomb filter having the filter volume and the accumulated soot amount shown in Table 1 below was prepared, incorporated into the holder 13 in the state shown in FIG. 2, and the combustion air having the flow rate shown in Table 1 was made to flow from the inlet side. Regeneration was carried out. In addition,
Table 1 also shows the capacity of the heater used. Then, the maximum temperature inside the filter and the damage state of each filter during regeneration were examined. The results are shown in Table 1. Also,
The results of Table 1 are summarized in FIG. 3 for easy viewing. In FIG. 3, the shaded portions indicate unfavorable portions. That is, in FIG. 3, the maximum temperature reached in the filter is 6
A temperature below 00 ° C indicates a soot incombustible region where combustion of soot disappears in the middle of which regeneration is not possible, and a maximum temperature reached within the filter of 1000 ° C or higher indicates a filter damage region where the filter becomes too hot and is damaged. .

[0012]

[Table 1]

From the results shown in Table 1 and FIG. 3, the range where the soot does not burn and the soot does not remain unburned, that is, the temperature of the filter is 1000 ° C. or less at which the filter does not melt and 600 ° C. or more at which the soot completely burns. It can be seen that the range that can be maintained at the temperature is when the amount of deposited soot is 10 g or more per liter of the filter, and when a very small amount of air of 2 to 15 liters / minute is fed to the filter.

The present invention is not limited to the above-mentioned embodiments, but various modifications and changes can be made. For example, in the above-described embodiment, an example in which the regeneration is performed in the state shown in FIG. 2 is shown, but it is said that the regeneration can be performed in other states as long as the soot amount and the supply air amount of the present invention are satisfied. There is no end. Further, the material is not limited to ceramic, and any heat resistant material such as metal can be used. Further, the filter shape is not limited to the honeycomb type, and can be changed to a plate-like tubular shape or the like.

[0015]

As is apparent from the above description, according to the present invention, the soot amount is preferably 1 per liter of the filter in the presence of the soot amount to the extent that combustion is stably propagated.
Due to the synergistic effect of performing regeneration in a large amount of 0 g or more and reducing the air flow rate at that time to preferably 2 to 15 liters / minute, there is no damage to the filter and no unburned soot. The honeycomb filter can be regenerated.

[Brief description of drawings]

FIG. 1 is a view showing a cross-sectional structure of a diesel particulate filter including a ceramic honeycomb filter to which the regeneration method of the present invention is applied.

FIG. 2 is a diagram showing a configuration of an example of an electric heater system incorporating a ceramic honeycomb filter.

FIG. 3 is a diagram showing a result of an example in the present invention.

[Explanation of symbols]

 11 Electric Heater 12 Ceramic Honeycomb Filter 13 Holder

Claims (2)

(57) [Claims] 1. A method of regenerating a soot removing filter, which burns and removes soot mainly composed of carbon fine particles, so as to extend the regeneration interval by collecting the soot per liter of filter until the soot is accumulated up to 10 g or more. Ignites the soot accumulated by the ignition source from one end on the exhaust gas inlet side of the filter, supplies minute air in the range of 2 liters / minute to 15 liters / minute to the filter, and gradually burns it to the other end of the filter. A method for regenerating a soot removing filter, which is characterized in that the heat generation amount per unit time of soot combustion is reduced and the temperature of the filter is maintained at a temperature of 1000 ° C or lower and 600 ° C or higher. 2. The soot removing filter according to claim 1, wherein the soot removing filter is a ceramic honeycomb filter.