JP2006110451A - Chemical washing method and chemical washing apparatus for diesel exhaust gas cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical washing method for an exhaust gas cleaning device of a diesel engine in which firstly washing is sufficiently, certainly and effectively performed, secondly it is excellent in a working environment aspect, thirdly chemical corrosion and damage are not generated, fourthly it is excellent in washing force of the inside and fifthly waste liquid treatment of a washing liquid after washing is easy, and a chemical washing apparatus. <P>SOLUTION: In the chemical washing method and the chemical washing apparatus 12, regarding the exhaust gas cleaning device of the diesel engine, a unit deposited with a granular substance PM, for example, a filter 3 is washed. Then, two kinds of chemical washing systems are combined/adopted in view of physical/chemical characteristic of the granular substance PM. Namely, degreasing and washing are performed by firstly immersing the filter 3 in an alkaline sodium silicate solution of a first immersion tank 13 and subsequently, washing is carried out by immersing a hydrogen peroxide solution of a second immersion tank 14 and by oxidation action of oxygen generated under an alkali condition and foaming action. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chemical cleaning method and a chemical cleaning apparatus for a diesel exhaust gas purification apparatus. That is, for example, an exhaust gas purifying device for a diesel engine mounted on a vehicle relates to a chemical cleaning method and a chemical cleaning device for cleaning and regenerating a unit to which particulate matter is attached, particularly a filter to which particulate matter is collected and attached. Is.

<Technical background>
The exhaust gas of a diesel engine contains particulate matter PM (Particulate Materials) and other harmful substances, and is harmful if discharged directly into the outside air. Therefore, an exhaust gas purification device is interposed in the exhaust pipe from the diesel engine, and this exhaust gas purification device includes a purification device that collects particulate matter PM and a purification device for other harmful substances. ing.
A purification device that collects the particulate matter PM is called a DPF (Diesel Particulate Filter), and various types have been developed and used. For example, a wire mesh filter type, a sintered metal filter type, a filter type combined with an electric heater, a porous ceramic filter type, and the like have been developed and used.
Each of these types of DPP, that is, the particulate matter PM purifying device, has an automatic, continuous or intermittent regeneration system. In other words, particulate matter PM collected, adhered, and accumulated in the filter is burned by some method based on each type of operation principle, and the filter itself is automatically or continuously regenerated by the device itself. And the use continues.

《Information on prior art documents》
Examples of such a particulate matter PM purification device include those shown in the following Patent Documents 1, 2, and 3.
JP 2002-336627 A JP 2003-254045 A Japanese Patent Laid-Open No. 2002-4835

Now, with regard to such a particulate matter PM purification device, there are limitations to its automatic, continuous or intermittent regeneration system. In practice, the filter is periodically or appropriately removed as necessary for cleaning. Therefore, maintenance work is being carried out to regenerate its functions and characteristics.
In other words, there is a limit to the regeneration method, and when it is used for a long time, the particulate matter PM collected and accumulated tends to be clogged or close to clogging, and the particulate matter purification performance of the filter is lowered. Or the pressure loss of the exhaust pipe becomes large, and there is a concern about engine trouble.
Therefore, in practice, for example, the particulate matter collected, adhered, and accumulated on the filter by removing the filter of the particulate matter PM purification device mounted on the vehicle periodically, for example, every 6 months or in a shorter period of time. Maintenance work is being carried out to remove PM.

《About conventional technology》
And the maintenance work of the filter of the purification apparatus removed in this way has been conventionally performed as follows. (Note that the technology related to exhaust gas purification devices for diesel engines is still short, and there are not many conventional technologies related to maintenance work yet.)
First, maintenance work was performed by a method using a steam washer. For example, the removed wire mesh structure filter is disassembled from the assembled state into unit elements, and then sprayed with steam to remove particulate matter PM collected, adhered, and accumulated on the filter. It was washed and regenerated.
Also, maintenance work has been performed by a method using an electric furnace. That is, the removed filter is placed in an electric furnace, and the particulate matter PM collected, adhered, and accumulated in the filter is burned, incinerated, and removed to clean and regenerate the filter. It was.
Furthermore, maintenance work by a method using an ultrasonic cleaner has been attempted. In other words, the removed filter is immersed in a surfactant solution, etc., and the particulate matter PM collected, adhered, and accumulated on the filter is washed out and removed by the action of ultrasonic waves, and the filter is washed and regenerated. It was also attempted to do.

By the way, in such a conventional example, the following problems have been pointed out.
<About the first problem>
First, the filter was unclearly and insufficiently cleaned, and effective and reliable cleaning and regeneration were desired.
That is, in this type of conventional particulate matter PM purification device filter maintenance work, that is, maintenance work using a steam cleaning machine, an electric furnace, an ultrasonic cleaning machine, etc., the particulate matter collected, adhered and accumulated on the filter It has been pointed out that the removal of the substance PM is uncertain, insufficient and inefficient.
In particular, when the degree of blockage of the filter is severe, particulate matter PM having a particularly strong oil content is adhered, and the lack of detergency has become prominent.

About the second problem
Secondly, a problem has been pointed out in terms of working environment, particularly with a system using a steam washer.
That is, when maintenance work is performed using a steam washer, the polycyclic aromatic compound PAH in the particulate matter PM collected, adhered, and accumulated in the filter is scattered in the sprayed steam. This polycyclic aromatic compound PAH has recently been regarded as a problem of adverse health effects, and it has been problematic for workers to perform maintenance work in an environment where such substances are scattered.

<< About the third problem >>
Thirdly, regarding the method using an electric furnace, the problem of metal erosion (carburization) of the filter has been pointed out.
That is, in maintenance work using an electric furnace, the filter is heated to a high temperature of about 600 ° C. to 800 ° C. in order to incinerate the collected particulate matter PM. And under such a high temperature, the metal material such as stainless steel alloy of the filter reacts with the carbon particles which are the main components of the particulate matter PM, and is thus chemically eroded (carburized) by carburizing action, There was a situation where it was damaged.
Therefore, for a filter using a wire mesh structure, a filter made of sintered metal, or a filter using all or part of a metal material, that is, for a purification device for many particulate matter PM, a method using this electric furnace is: It was difficult to apply and unusable.

About the fourth problem
Fourthly, the method using an ultrasonic cleaning machine has been pointed out as being inferior in cleaning power inside the filter.
That is, in the maintenance work using the ultrasonic cleaner, the particulate matter PM of the filter is washed out by the vibration action of the ultrasonic wave, but it is difficult for the ultrasonic wave to penetrate into the filter. On the other hand, in this type of filter, a larger amount of particulate matter PM tends to be collected, adhered, and accumulated toward the inside. Therefore, this method has been considered difficult and unusable for filters having a relatively large capacity, volume, mass and the like.
Furthermore, not only the method using this ultrasonic cleaner, but also the method using a steam cleaner and others, there is a problem of insufficient internal cleaning. Therefore, for example, this type of filter is removed in an assembled state, and further disassembled into unit elements, and then maintenance work is performed.

About the fifth problem
Fifth, regarding the method using a steam washer, ultrasonic washer, and other washer, a problem has been pointed out in wastewater treatment after filter washing.
That is, after removing the particulate matter PM from the filter, it is not easy to treat the cleaning liquid containing the removed particulate matter PM. In other words, the detoxification treatment of the used cleaning liquid after maintenance work is very troublesome, requiring labor and man-hours.

<< About the present invention >>
The chemical cleaning method and chemical cleaning apparatus for a diesel exhaust gas purification apparatus according to the present invention have been made in order to solve the above-described problems of the conventional example in view of such a situation.
And in view of the physical and chemical characteristics of the particulate matter, a combination of two types of chemical cleaning methods is employed. That is, filters and other units with particulate matter attached are first immersed in an alkaline sodium silicate solution, degreased and washed, then immersed in a hydrogen peroxide solution, and cleaned by oxidation and foaming. It is characterized by.
Therefore, the present invention is firstly cleaned sufficiently, reliably and effectively, secondly excellent in working environment, thirdly free from chemical erosion and damage, and fourthly. In particular, an object of the present invention is to propose a chemical cleaning method and a chemical cleaning device for an exhaust gas purification device of a diesel engine, which are particularly excellent in internal cleaning power and can be easily treated with a cleaning liquid after cleaning.

<About Claim>
The technical means of the present invention for solving such a problem is as follows. First, claim 1 is as follows.
The method for chemically cleaning a diesel exhaust gas purification apparatus according to claim 1 relates to a method for cleaning a unit to which particulate matter is adhered in an exhaust gas purification apparatus for a diesel engine.
The unit is first immersed in an alkaline sodium silicate solution, degreased and washed, and then immersed in a hydrogen peroxide solution to be cleaned by the oxidizing action and foaming action of the generated oxygen. It is characterized by.
Claim 2 is as follows. A chemical cleaning method according to claim 2 relates to a method for cleaning and regenerating a filter in which particulate matter is collected and adhered in claim 1.
First, the filter is immersed in an alkaline sodium silicate solution to dissolve and degrease the particulate matter adhering to the filter. Exfoliate and remove significantly from the filter. Accordingly, the filter is washed.
Next, the filter is immersed in a hydrogen peroxide solution, and the carbon particles of the particulate matter adhering to the filter are oxidized with oxygen generated from hydrogen peroxide under alkaline conditions. Is removed from the filter. At the same time, particulate matter adhering to the filter is peeled and removed not only from the surface but also from the inside by the generated oxygen bubbles. Thus, the filter is washed.

Claim 3 is as follows. The chemical cleaning method according to claim 3 is characterized in that, in claim 2, the hydrogen peroxide solution contains a stabilizer that maintains the activity of hydrogen peroxide.
Claim 4 is as follows. The chemical cleaning method of claim 4 is characterized in that, in claim 3, the hydrogen peroxide solution has a hydrogen peroxide concentration of less than 6%, and sodium pyrophosphate is used as a stabilizer.
Claim 5 is as follows. The chemical cleaning method of claim 5 is characterized in that, in claim 2, the sodium silicate solution has a pH value of about 8.5 to 11.5.
Claim 6 is as follows. The chemical cleaning method according to claim 6 is neutralized by mixing the alkaline sodium silicate solution and the acidic hydrogen peroxide solution after use in claim 2. At the same time, the remaining hydrogen peroxide is decomposed by the contact and catalytic action of the carbon particles of the particulate matter removed from the filter. Thus, the waste liquid is rendered harmless.

Claim 7 is as follows. According to a seventh aspect of the present invention, there is provided a chemical cleaning apparatus for a diesel exhaust gas purification apparatus, comprising: a first immersion tank and a second immersion tank for cleaning a unit to which particulate matter is adhered. .
The first immersion tank is filled with an alkaline sodium silicate solution, and the unit is first immersed, degreased and cleaned. The second immersion tank is filled with a hydrogen peroxide solution, and the unit recovered from the first immersion tank is immersed and cleaned by oxidizing and foaming the generated oxygen. And
Claim 8 is as follows. A chemical cleaning apparatus according to an eighth aspect is the chemical cleaning apparatus according to the seventh aspect, wherein the filter on which the particulate matter is collected and adhered is cleaned and regenerated.
In the first immersion tank, the filter is immersed in an alkaline sodium silicate solution, and the particulate matter adhering to the filter is dissolved and degreased, whereby the particulate matter is considerably peeled and removed. The filter is washed.
In the second dip tank, the filter collected from the first dip tank is immersed in a hydrogen peroxide solution, and particles adhered to the filter with oxygen generated from hydrogen peroxide under alkaline conditions. The carbon particles of the particulate matter are oxidized, and the particulate matter is peeled and removed. At the same time, particulate matter adhering to the filter is peeled off and continuously discharged not only from the surface but also from the inside by the generated oxygen bubbles. Thus, the filter is washed.

<About action>
Since the chemical cleaning method and the chemical cleaning apparatus of the diesel exhaust gas purifying apparatus according to the present invention are as described above, they are as follows.
This chemical cleaning method and chemical cleaning device is a diesel engine exhaust gas purification device, in which a unit to which particulate matter has adhered, for example, a filter in which particulate matter has been collected, adhered and accumulated, is sequentially immersed in two types of cleaning liquids. And wash.
That is, a unit such as a filter is first immersed in an alkaline sodium silicate solution (pH value of about 8.5 to 11.5) in the first immersion tank, and then the oil of adhering particulate matter is degreased. Let the adhesiveness be lost. → Particulate matter is peeled and removed from the filter and washed.
→ Then, immerse the filter etc. in the hydrogen peroxide solution in the second immersion tank (hydrogen peroxide concentration is less than 6% and contains a stabilizer for maintaining activity such as sodium pyrophosphate) → under alkaline conditions The carbon particles of the particulate matter are oxidized with the oxygen generated from the hydrogen peroxide, and the particulate matter is peeled and removed from the inside with a bubble of oxygen and continuously discharged.

Now, according to the present invention, it is as follows. First, the particulate matter is made of fine particles in which carbon particles are covered with oil or the like, and is collected, adhered, and accumulated in a large amount in a unit such as a filter. Therefore, in the present invention, in view of the physicochemical characteristics of such particulate matter, a combination of two types of cleaning liquids is employed.
That is, for filters, etc., first, the oil of the particulate matter is alkaline degreased and washed with a sodium silicate solution, and then the carbon particles of the particulate matter are oxidized with the oxidizing action of the generated oxygen in a hydrogen peroxide solution. At the same time, the particulate matter is discharged with oxygen bubbles and washed. Thus, the particulate matter is sufficiently and reliably removed, and the filter and the like are efficiently cleaned and regenerated.

Secondly, in the present invention, a filter or the like is sequentially immersed in a cleaning solution, and cleaned and regenerated by degreasing, oxidation, foaming, or the like. Therefore, the worker is engaged in the removal work of the filter etc., the immersion work in and out of the immersion tank, the installation work of the regenerated filter etc., and the work is not carried out in the environment where the particulate matter is scattered. Excellent environmental aspect.
Third, in the present invention, a filter or the like is immersed in two types of cleaning liquids. A sodium silicate solution has a pH value of about 8.5 to 11.5 and a low alkalinity. The acidity of hydrogen oxide is weak and the concentration is less than 6%. Therefore, a filter made of a metal material or the like is unlikely to be chemically eroded, corroded, or damaged.
Further, since the cleaning is not performed at a particularly high temperature, the filter made of a metallic material does not react with the carbon particles of the particulate matter, and is not chemically eroded or damaged.

Fourth, in the present invention, the particulate matter is degreased with a sodium silicate solution so as to lose its adhesiveness, and is oxidized with oxygen generated from a hydrogen peroxide solution while being oxidized by the force of oxygen bubbles. To drain. And, by such a combination of actions, the particulate matter that has been collected, adhered and accumulated in a large amount inside the filter or the like is surely peeled and removed.
As described above, since the cleaning power from the inside is particularly excellent, it is not necessary to disassemble the filter used in the assembled state to the unit element for cleaning.
Fifth, in the present invention, the alkaline sodium silicate solution and the acidic hydrogen peroxide solution after use are neutralized by mixing, and the remaining hydrogen peroxide is brought into contact with the carbon particles of the particulate matter and catalysis. It is decomposed by. Thus, the cleaning liquid after use is easily rendered harmless.

<Features of the present invention>
Thus, the chemical cleaning method and the chemical cleaning apparatus of the diesel exhaust gas purifying apparatus according to the present invention are characterized by adopting a combination of two types of chemical cleaning systems in view of the physical and chemical characteristics of the particulate matter. And
That is, filters and other units with particulate matter attached are first immersed in an alkaline sodium silicate solution, degreased and washed, then immersed in a hydrogen peroxide solution, and cleaned by oxidation and foaming. It is characterized by.
Therefore, the present invention exhibits the following effects.

<< First effect >>
First, the cleaning is performed sufficiently, reliably and effectively. That is, in the present invention, the filter of the particulate matter purification device or other exhaust gas purification device unit is immersed in a sodium silicate solution to be degreased and washed, and immersed in a hydrogen peroxide solution to be oxidized and foamed. Wash.
Therefore, in comparison with this type of conventional example described above, that is, in the form of particles that have been collected, adhered, and accumulated, as compared to the conventional example that was cleaned using a steam cleaning machine, an electric furnace, an ultrasonic cleaning machine, etc. Maintenance work to remove material is carried out sufficiently, reliably and efficiently. In particular, the detergency to oil is enhanced by employing a sodium silicate solution as a cleaning liquid.
As described above, according to the present invention, the filter and other units are restored to their original functions and characteristics by the removal of the particulate matter, and are reattached and continuously used.

<< Second effect >>
Second, it is excellent in terms of work environment. That is, in the present invention, the filter and other units of the exhaust gas purifier are cleaned by sequentially immersing them in two types of cleaning liquids.
Therefore, as in the case of this type of conventional example described above, that is, the conventional example in which the steam washer was used for cleaning, the worker maintained the environment in which the polycyclic aromatic compound in the particulate matter was scattered by the steam. There is no such thing as working. As described above, in the present invention, cleaning is performed by a method in consideration of the work environment.

《Third effect》
Third, chemical erosion and damage do not occur. That is, in the present invention, the filter and other units of the exhaust gas purification device are cleaned by immersing them in two types of cleaning liquids.
Therefore, as in the above-described conventional example, that is, a conventional example in which cleaning is performed using an electric furnace, a filter or unit made of a metal material reacts with carbon particles of particulate matter at a high temperature, thereby carburizing. Erosion (carburization) and damage due to action are avoided. Furthermore, the possibility of erosion and corrosion by the sodium silicate solution used as the cleaning liquid is low, and there is no possibility of erosion, corrosion and damage by the hydrogen peroxide solution.
Accordingly, the present invention relates to a particulate matter purification device such as a wire mesh filter, a sintered metal filter, a filter using all or part of a metal material, and other purification devices, that is, various exhaust gases. Applicable and usable for maintenance work of purification equipment.

<< 4th effect >>
Fourth, the internal cleaning power is particularly excellent. That is, in the present invention, the particulate matter adhering to the filter and other units of the exhaust gas purifying apparatus is peeled and removed from the inside by defoaming and oxidation together with the force of bubbles.
Therefore, the particulate matter that has been collected, adhered, and accumulated in large quantities inside the filter and unit is conventionally cleaned using this type of conventional example, that is, an ultrasonic cleaner, a steam cleaner, etc. Compared to examples, it can be removed more reliably and smoothly, and can be applied and used for maintenance work of large filters and units with large capacity, volume, mass, etc.
In addition, since the cleaning power from the inside is excellent as described above, it is not necessary to disassemble the filter or the like into unit elements during maintenance work.

《Fifth effect》
Fifth, it is easy to process the cleaning liquid after cleaning. That is, the two types of cleaning solutions used in the present invention, that is, sodium silicate solution and hydrogen peroxide are mixed and neutralized after use, and the remaining hydrogen peroxide is decomposed by carbon particles. As described above, the cleaning liquid after the maintenance work is easily rendered harmless, and, unlike the above-described conventional example, the harmless treatment is troublesome and requires labor and man-hours, and there is no problem with wastewater treatment. .
As described above, the effects exerted by the present invention are remarkably large, such as all the problems existing in this type of conventional example are solved.

《About drawing》
Hereinafter, a chemical cleaning method and a chemical cleaning apparatus for a diesel exhaust gas purification apparatus according to the present invention will be described in detail based on the best mode for carrying out the invention shown in the drawings. 1, 2 and 3 are used to explain the best mode for carrying out the present invention.
1 (1) is a front view of the chemical cleaning apparatus, (2) is a perspective view of the assembled filter, and (3) is a perspective view of the unit element of the filter. .
FIG. 2 is a front sectional view of the diesel exhaust gas purification device, and FIG. 3 is a system diagram of the diesel exhaust system.

<< About the exhaust gas purification device 2 of the diesel engine 1 >>
The present invention relates to a chemical cleaning method and a chemical cleaning apparatus for cleaning a unit such as a filter 3 to which particulate matter PM adheres, with respect to the exhaust gas purification apparatus 2 of the diesel engine 1 shown in FIGS. First, the exhaust gas purifying device 2 as a premise will be described with reference to FIGS.
The diesel engine 1 is widely used as an internal combustion engine for automobiles such as buses and trucks, as well as power generation, ships, locomotives, aircraft, various machines, and others. The exhaust gas 4 exhausted from the diesel engine 1 contains carbon monoxide CO, hydrocarbon HC, nitrogen oxides NO _x , particulate matter PM, and the like. Since it is harmful to the environment, an exhaust gas purification device 2 is interposed and connected to the exhaust pipe 5.
That is, the diesel engine 1 is supplied with fuel from a fuel tank 6 and exhausts exhaust gas 4 to an exhaust pipe 5. The exhaust gas 4 passes through an exhaust gas purification device 2 interposed and connected to the exhaust pipe 5. Then, it is discharged into the outside air.

The exhaust gas purification device 2 includes an outer cylinder case 7 having a diameter larger than that of the exhaust pipe 5, so that the purification device 8 and the purification device 9 can be attached to and detached from the inner cylinder case 7 with a mutual interval therebetween. They are stored in order.
The purification device 8 oxidizes, burns, and reduces carbon monoxide CO, hydrocarbon HC, nitrogen oxide NO _{X, and the} like, which are harmful substances in the exhaust gas 4, using an oxidation catalyst. For example, platinum Pt, vanadium V, copper Cu, manganese Mn, and other oxidation catalysts are attached and coated on the outer surface of each cell wall of the honeycomb core that is a built-in unit.
The cleaning device 9 collects, adheres to, and accumulates particulate matter PM, which is a harmful substance in the exhaust gas 4, on the filter 3 that is a built-in unit, and burns and reduces the particulate matter PM.

The particulate matter PM purification device 9 is also referred to as a DPF, and various types have been developed and used. For example, a type using a wire mesh filter 3 (WMF), a type using a sintered metal filter 3, a type using a filter 3 combined with an electric heater, a type using a porous ceramic filter 3 Various other types of filters 3 have been developed and used.
The filter 3 in the illustrated example is made of the above-described wire mesh structure type (WMF), and has a structure in which wires made of ultrafine stainless steel alloy are densely knitted into a fibrous or mesh shape. Then, a short columnar shape / substantially donut shape having a vent hole 10 in the center is formed, and one unit element shown in FIG. 1 (3) is as shown in FIG. 1 (2) and FIG. Are assembled in multiple stages, such as four, further six, eight, etc. Further, the filter 3 in the illustrated example is disposed in the outer cylinder case 7 while being held by the front and rear shield plates 11 with holes, and the exhaust gas 4 passes as indicated by arrows.
In any case, the particulate matter PM purifying device 9, that is, the DPF, automatically burns, removes and collects the particulate matter PM collected, adhered and accumulated by some method by itself, and automatically and continuously. Or it is intermittently regenerated and used continuously.
However, there is a limit to such self-regeneration, and in practice, the filter 3 is removed periodically and appropriately as needed for cleaning and regeneration. That is, the maintenance work of removing the particulate matter PM by removing the filter 3 from the purification device 9 before the filter 3 is blocked by the collected, adhered and accumulated particulate matter PM due to long-term use. However, it is actually implemented.
The exhaust gas purification device 2 of the diesel engine 1 is as described above.

<< Outline of the Present Invention >>
Hereinafter, the present invention will be described with reference to FIG. The chemical cleaning method and the chemical cleaning apparatus 12 according to the present invention relate to a method and an apparatus for cleaning the unit to which the particulate matter PM adheres in the exhaust gas purification device 2 of the diesel engine 1 described above. In particular, the present invention relates to a method and an apparatus for cleaning and regenerating the filter 3 in which the particulate matter PM is collected, adhered, and accumulated with respect to the particulate matter PM purification device 9.
That is, as described above, the exhaust gas purification device 2 includes the purification device 8 covered with the oxidation catalyst for carbon monoxide CO, hydrocarbon HC, and nitrogen oxide NO _X and the purification device 9 for the particulate matter PM. DPF.
And the chemical cleaning method and the chemical cleaning apparatus 12 of this invention are used in order to remove the particulate matter PM adhering to those units, and to wash | clean a unit. In particular, the particulate matter PM purifier 9, that is, the filter 3 that is a DPF unit, is used to remove, clean, and regenerate the particulate matter PM collected, adhered, and accumulated.

In this chemical cleaning method, the filter 3 or other unit is first immersed in an alkaline sodium silicate solution, degreased and cleaned, and then immersed in a hydrogen peroxide solution to generate oxygen. Washing by oxidation and foaming action.
The chemical cleaning device 12 includes a first immersion tank 13 and a second immersion tank 14. The first immersion tank 13 is filled with an alkaline sodium silicate solution, and the filter 3 or other unit is first immersed, degreased and cleaned. The second immersion tank 14 is filled with a hydrogen peroxide solution, and the filter 3 or other unit recovered from the first immersion tank 13 is immersed therein and cleaned by oxidizing and foaming the generated oxygen. .

<About particulate matter PM>
Here, the particulate matter PM to be removed by the chemical cleaning method and the chemical cleaning apparatus 12 will be described.
Particulate materials PM (Particulate Materials) are contained in the exhaust gas 4 of the diesel engine 1, and are composed of carbon particles, that is, soot-like carbon C (Dry Soot), unburned hydrocarbon HC, and lubricating oil hydrocarbon HC. And polycyclic aromatic compound PAH, sulfate (Sulfate), and water H ₂ O as main components.
Black smoke that is carbon particles, that is, soot-like carbon C (Dry Soot) is generated by incomplete combustion of light oil, which is fuel, and is unburned by incomplete combustion of carbon C. The main component of particulate matter PM The core component.
Unburned hydrocarbon HC and lubricating oil hydrocarbon HC are components of light oil as fuel and leaked engine oil, and are composed of high-boiling hydrocarbons HC.
The polycyclic aromatic compound PAH (polyaromatic hydrocarbons) is a product obtained by thermally decomposing such high-boiling hydrocarbons HC.
Sulfate is a sulfide derived from the sulfur S content in light oil as a fuel, and is mainly composed of sulfur oxide SO ₄ ⁻ .

The particulate matter PM is composed of a mixture of these components, and is composed of an aggregate in which solid carbon particles having a main component of 20 nm to 30 nm are covered with the remaining components. In the primary particle state, it has a size of about several hundreds of nanometers (several μm), but is usually mutually coupled to a secondary particle state having a size of about several hundreds of μm.
In addition, unburned hydrocarbon HC, lubricating oil hydrocarbon HC, and polycyclic aromatic compound PAH are soluble in organic solvents and are highly sticky oils, and are also referred to as soluble organic components SOF (Soluble Organic Fraction). And account for about 40% of the particulate matter PM.
On the other hand, carbon particles and sulfate are also referred to as a component ISF (In Soluble Fraction) that is insoluble in organic solvents, and occupy about 60% of the particulate matter PM.
The particulate matter PM is like this.

<About immersion in sodium silicate solution>
In the chemical cleaning method and the chemical cleaning apparatus 12 of the present invention, the filter 3 or other unit is immersed in the alkaline sodium silicate solution in the first immersion tank 13.
Then, by dissolving and degreasing the oil content of the particulate matter PM attached to the filter 3 or the like, the adhesiveness of the particulate matter PM is lost, and the particulate matter PM is peeled off from the filter 3 or the like. Thus, the filter 3 and the like are washed.

These will be further described in detail. The pH of the sodium silicate solution is about 8.5 to 11.5, preferably about 9.0 to 11.0. That is, the optimal concentration of sodium silicate is about 2% to 10%.
When the pH value of the aqueous solution is less than 8.5, the function cannot be expected to be exhibited. When the pH value exceeds 11.5, there is a risk of eroding the filter 3 made of metal material and other units. Normally, the pH value rarely exceeds 11.5.
The sodium silicate solution is prepared at a temperature of about 35 ° C. to 60 ° C. If the temperature is lower than 35 ° C, the reaction becomes dull and the function is not sufficiently exhibited, so that the dissolving power and the degreasing power are insufficient. There is a risk of eroding the unit.
Sodium silicate is made by melting and solidifying a mixture of NaOH and SiO ₂ and is soluble in water. The composition ratio of SiO ₂ : Na ₂ O is 1.6: 1 in terms of molar ratio. About 4: 1 is used. For example, JIS 1 2: 1, JIS 2 2.5: 1, JIS 3 3: 1, JIS 4 4: 1 or a commercial product 1.72: 1 are used.
By soaking in the sodium silicate solution, the particulate matter PM adhering to the filter 3 or the like is dissolved and degreased in its oil component (soluble organic component SOF), so that the particulate matter PM is transferred to the filter 3 or the like by the oil content of the particulate matter PM. Thus, the filter 3 and the like are washed.

In addition, about such a degreasing method, as a result of various examination, it came to select sodium silicate. First, organic solvents such as acetone, ethanol and methanol have poor oil solubility and degreasing power, and the filter 3 and the like could not be washed. The hot water has insufficient oil dissolving power and degreasing power, and the filter 3 and the like have not been sufficiently washed (see also examples described later).
Furthermore, although sodium percarbonate PC, that is, an adduct of sodium carbonate and hydrogen peroxide, is excellent in oil dissolving power and degreasing power, it is in the form of powder, so it is difficult to enter the inside of the filter 3 and the like for cleaning the filter 3 and the like. It was difficult to use.
In contrast, sodium silicate has a lower alkalinity than a strong alkali such as caustic soda having a pH value of 12 or more, and is usually easily maintained at a pH value of about 11 and is kept at a temperature of 60 ° C. or less. The chemical filter 3 and other units made by the company have little chemical erosion, and the oil has high solubility and degreasing power and is soluble in water.
Soaking in the sodium silicate solution is like this.

<Immersion in hydrogen peroxide solution>
Next, in the chemical cleaning method and the chemical cleaning apparatus 12 of the present invention, the filter 3 and other units are immersed in the hydrogen peroxide solution in the second immersion tank 14.
Then, the carbon particles of the particulate matter PM adhering to the filter 3 or the like are oxidized by oxygen generated from the hydrogen peroxide H ₂ O ₂ under alkaline conditions, and the particulate matter PM is separated from the filter 3 or the like. Further, the particulate matter PM adhering to the filter 3 or the like is peeled and removed not only from the surface but also from the inside by the generated oxygen bubbles. Thus, the filter 3 and the like are washed.

These will be further described in detail. Hydrogen peroxide H ₂ O ₂ is a very weak acidic liquid with a dissociation index of about 11.6 and is soluble in water. In an acidic solution, it remains practically unchanged even when left at 100 ° C. for several hours. However, when the filter 3 or the like recovered from the sodium silicate solution as described above is immersed and placed under alkaline conditions, hydrogen peroxide H ₂ O ₂ is decomposed and water, oxygen, hydroperoxy anion is used as an oxygen-based oxidizing agent. HOO ^- such as to generate.
In this way, the hydrogen peroxide solution generates oxygen bubbles from the inside of the immersed filter 3, etc., and oxidizes the carbon particles of the particulate matter PM adhering to the filter 3, etc., thereby having a fine particulate matter. PM is peeled off from the filter 3 or the like. At the same time, the particulate matter PM is continuously discharged not only from the surface of the filter 3 and the like but also from the inside by the foaming action of oxygen.
The concentration of hydrogen peroxide H ₂ O _{2 in} the hydrogen peroxide solution is as follows. First of all, a product having a concentration of 35% is supplied and can be used as it is, but there is a problem that the reaction becomes too intense. In addition, those with a concentration of 6% or more are subject to the regulation of non-medical deleterious poisons. Even when the concentration was less than 6%, the above-described oxidizing action and foaming action were sufficiently obtained.
Therefore, it is appropriate from a practical viewpoint that the hydrogen peroxide H ₂ O ₂ concentration of the hydrogen peroxide solution is less than 6%. Note that the hydrogen peroxide solution is gradually heated by the reaction during cleaning, and therefore it is not necessary to prepare it by heating in advance.
By the way, the hydroperoxy anion HOO ⁻ is generated according to the following chemical formula 1 by making hydrogen peroxide H ₂ O ₂ alkaline as described above.

The generated hydroperoxyanion HOO ⁻ maintains the activity of hydrogen peroxide H ₂ O ₂ and becomes an active species for the oxidation reaction of the carbon particles of the particulate matter PM described above.
However, this hydroperoxy anion HOO ⁻ is easily self-decomposed by the reaction of the following chemical formula (2).

Therefore, in order to prevent such self-decomposition, a stabilizer is added in advance to the hydrogen peroxide solution, and sodium pyrophosphate is effective as this stabilizer.
The amount of sodium pyrophosphate to be added is about 500 ppm to 5,000 ppm for the hydrogen peroxide solution having a hydrogen peroxide H ₂ O ₂ concentration of 35% or less, and about 1,000 ppm is economical for its function. It is the most effective from the standpoint.
The immersion in the hydrogen peroxide solution is performed in this way.

《Action etc.》
The chemical cleaning method and the chemical cleaning device 12 of the exhaust gas purification device 2 of the diesel engine 1 according to the present invention are configured as described above. Therefore, it becomes as follows.
This chemical cleaning method and chemical cleaning device 12 cleans the filter 3 and other units of the purification devices 8 and 9 to which the particulate matter PM has adhered in the exhaust gas purification device 2 of the diesel engine 1 (FIGS. 2 and 3). See).
For example, the purification device 9 in which the particulate matter PM is collected, adhered, and accumulated, that is, the DPF filter 3 is subjected to maintenance work for cleaning and regenerating. Furthermore, the cleaning device 9 in which the particulate matter PM has adhered and accumulated, that is, the unit covered with the oxidation catalyst, is also used for maintenance work for cleaning and regenerating.
Then, the unit such as the filter 3 is sequentially immersed in two types of cleaning liquids. First, it is immersed in an alkaline sodium silicate solution in the first immersion tank 13 and degreased and washed, and then immersed in a hydrogen peroxide solution in the second immersion tank 14 to oxidize the generated oxygen. Cleaning is performed by a foaming action (see FIG. 1 (1)).

That is, in this chemical cleaning method and chemical cleaning device 12, the filter 3 and other units removed from the purification device 9 and the purification device 8 of the exhaust gas purification device 2 mounted on the vehicle, for example, It is immersed in 13 alkaline sodium silicate solution (pH value is about 8.5 to 11.5). → Thus, the oil of the particulate matter PM adhering to the filter 3 or the like is dissolved and degreased. → The adhesiveness of the particulate matter PM is lost. → The particulate matter PM adhering to a large amount is removed from the filter 3. It peels and removes from etc. considerably. → In this way, the filter 3 and the like are washed.
Then, this filter 3 or the like is used as an acidic hydrogen peroxide solution (hydrogen peroxide H ₂ O ₂ concentration of less than 6%) in the second immersion tank 14 (as a stabilizer for maintaining its activity, for example, pyrophosphoric acid Soaked in soda). Therefore, oxygen is generated from hydrogen peroxide H ₂ O ₂ under alkaline conditions by the alkaline sodium silicate solution slightly contained in the filter 3.
→ The oxygen thus generated oxidizes the carbon particles of the particulate matter PM adhering to the filter 3, and the particulate matter PM is peeled off from the filter 3 and the like. → Together with this, the particulate matter PM adhering to the filter 3 or the like is peeled and removed from the inside of the filter 3 or the like and continuously discharged by the generated oxygen bubbles. → In this way, the filter 3 and the like are washed.

Now, according to the chemical cleaning method and the chemical cleaning device 12 of the exhaust gas purification device 2 of the diesel engine 1 according to the present invention, the following first, second, third, fourth and fifth are obtained.
First, the particulate matter PM is composed of fine particles in which carbon particles are covered with oil or the like. And it collects, adheres, and accumulates so that it may be clogged up in a large amount with respect to units, such as filter 3. Therefore, in the present invention, in view of the physical and chemical characteristics of such particulate matter PM, a combination of two types of cleaning liquids and chemical cleaning methods is employed based on a new cleaning principle corresponding to this.
That is, as a first step, the filter 3 or the like is immersed in a sodium silicate solution, and the oil content outside the particulate matter PM is alkali degreased to wash while eliminating the stickiness of the particulate matter PM. Then, as the next step, the carbon particles, which are the core of the particulate matter PM, are oxidized by the oxidation action of the generated oxygen by dipping in a hydrogen peroxide solution, and the particulate matter PM is Drain from filter 3 etc. and wash.
In the present invention, by following such steps, the particulate matter PM collected, adhered, and accumulated in the filter 3 and the like is sufficiently and reliably removed, and the filter 3 and the like are efficiently cleaned and regenerated. The For example, when the filter 3 is attached to the original purification device 9, the collection rate of the particulate matter PM is restored to the initial characteristics.

Secondly, in the present invention, the unit such as the filter 3 is soaked in two kinds of cleaning liquids sequentially and cleaned and regenerated by degreasing, oxidation, foaming, and the like.
Therefore, an operator who performs such maintenance work of the filter 3 and the like removes the filter 3 and other units from the purification devices 8 and 9, and the first and second immersion tanks 13 such as the removed filter 3 and the like. , 14, and the work of attaching the regenerated filter 3 and the like to the purification devices 8, 9 are engaged.
Thus, in the present invention, the worker is not engaged in work in an environment where the particulate matter is scattered, and the work environment is excellent.

Third, as described above, in the present invention, the unit such as the filter 3 is sequentially immersed in two kinds of cleaning liquids for cleaning and regeneration.
The sodium silicate solution used as the cleaning liquid has a sodium silicate concentration of about 10% to 20%, that is, a pH value of about 8.5 to 11.5, and has a low alkalinity. Therefore, there is almost no possibility that the filter 3 made of a metal material or the like or the other filter 3 or unit is chemically eroded, corroded or damaged.
Further, the hydrogen peroxide solution used as the cleaning liquid has a weak acidity of hydrogen peroxide H ₂ O ₂ and its concentration is less than 6%. Therefore, there is no possibility that the filter 3 made of a metal material or the like or the other filter 3 or unit is chemically eroded, corroded or damaged.
Further, such cleaning of the filter 3 and the like is not particularly performed at a high temperature. Therefore, the filter 3 made of a metal material reacts with the carbon particles of the particulate matter PM, and is not chemically eroded (carburized) or damaged.

Fourth, as described above, in the present invention, the cleaning of the unit such as the filter 3 is sequentially performed by combining degreasing and cleaning with a sodium silicate solution and cleaning with an oxidizing action and a foaming action with a hydrogen peroxide solution. . That is, the particulate matter PM adhering to the filter 3 or the like is degreased to lose its adhesiveness and is oxidized while being discharged from the inside by the force of oxygen bubbles.
Particulate matter PM tends to be collected, adhered, and accumulated in a large amount inside the filter 3 and the like, but the particulate matter PM inside is peeled and removed reliably and smoothly, and all of it is washed out. .
Thus, the present invention is particularly excellent in the cleaning power from the inside of the filter 3 and the like. Therefore, the filter 3 or the like that is used in a vehicle in a multi-stage assembled state (see FIGS. 1 (2) and 2) is disassembled into a single unit element for cleaning (FIG. 1). (See (3) in Fig. 3). The filter 3 and the like are cleaned in a multi-stage assembled state.

Fifth, in the present invention, the waste liquid of the alkaline sodium silicate solution and the acidic hydrogen peroxide solution after use is neutralized by mixing after the fact. At the same time, the remaining hydrogen peroxide H ₂ O ₂ is decomposed into water and oxygen by contact and catalytic action of carbon particles of the particulate matter PM removed from the filter 3 and the like.
In the present invention, the cleaning liquid after use becomes waste liquid that is easily detoxified in this way, and its processing is simple.

Here, each Example of the chemical cleaning method and the chemical cleaning apparatus 12 of the present invention will be described.
First, Example 1 will be described. In Example 1, the cleaning device 9 for the particulate matter PM, that is, the DPF filter 3 was subjected to a cleaning test, and the cleaning effect was grasped by gloss.
The filter 3 has a wire mesh structure made of WMF, that is, stainless alloy steel.
The unit element has a substantially donut shape with an outer diameter of 250 mm and an inner diameter of 85 mm, a mass of 3.5 kg, and a volume of 0.7 L (see FIG. 1 (3)). Then, the filter 3 (see FIG. 1 (2)) assembled with the unit elements in four layers is used for several months in a vehicle (see FIGS. 2 and 3), and the pressure loss is increased. Remove from the purification device 9 and use.
-The filter 3 before washing had black particulate matter PM as a whole attached, and there was no metallic luster of stainless steel.

First, such a filter 3 was immersed in the sodium silicate solution of the 1st immersion tank 13 (refer the figure (1) of FIG. 1).
・ Sodium silicate solution is sodium silicate equivalent to JIS 1 with 2: 1 of SiO ₂ : Na ₂ O, prepared by adding 12 kg of water to 1.2 kg with a solid content of 32%, and heated to 40 ° C. did.
-And the filter 3 was immersed in such a sodium silicate solution of the 1st immersion tank 13, repeated up and down several times, and wash | cleaned for 10 minutes, circulating a liquid. Then, the filter 3 was lifted from the first immersion tank 13 and then suspended for several minutes to drain the liquid.

Next, the filter 3 was immersed in a hydrogen peroxide solution in the second immersion tank 14 (see FIG. 1 (1)).
-Hydrogen peroxide solution prepared 12 kg by diluting 35% hydrogen peroxide H ₂ O ₂ containing 5,000 ppm sodium pyrophosphate to a concentration of 6%.
-And the filter 3 was immersed in the 2nd immersion tank 14 about 25 degreeC after having pulled up from the 1st immersion tank 13 mentioned above. In about 1 to 2 minutes after the filter 3 is immersed in the second immersion tank 14, oxygen bubbles are generated from the hydrogen peroxide solution, and many particulate substances PM are black from the immersed filter 3. The liquid was discharged.
-Then, the filter 3 was lifted from the second immersion tank and then suspended for several minutes to drain the liquid. As a finish, the filter 3 was dipped in 12 kg of an oxalic acid aqueous solution, which is a surface finish, for about 10 minutes, and then pulled up, washed with water and drained.

In Example 1, the filter 3 was subjected to a cleaning test by sequentially immersing in two types of cleaning liquids.
As a result, the effect of the present invention was demonstrated. That is, the particulate matter PM adhering to the filter 3 was sufficiently and reliably removed, and the metallic luster of the stainless steel was recovered. The filter 3 assembled in four layers was disassembled into one unit element and the inside was inspected, but no black residue of particulate matter PM was found.
About Example 1, it is as above.

Next, Example 2 will be described. In Example 2, the particulate matter PM purification device 9, that is, the DPF filter 3 (WMF) was disassembled into one unit element and subjected to a cleaning test, and in particular, the degreasing performance of the sodium silicate solution was grasped. .
Test conditions such as filter 3, sodium silicate solution, hydrogen peroxide solution, etc. and test steps are almost the same as those described in Example 1.
-However, the filter 3 assembled in a four-layered structure was disassembled into one unit element and used. Also, the sodium silicate _solution, SiO 2: _Na 2 O is 1.72: 1 was used in commercial products.
The filter 3 is immersed in a sodium silicate solution that is a cleaning liquid in the first immersion tank 13, and the recovered amount of the particulate matter PM washed out and a hydrogen peroxide solution that is a cleaning liquid in the second immersion tank 14. The recovered amount of particulate matter PM immersed and washed out was measured.
-Moreover, as a comparative example, about the washing | cleaning liquid of the 1st immersion tank 13, the water washing test was carried out by putting water instead of a sodium silicate solution. About the washing | cleaning liquid of the 2nd immersion tank 14, it was set as the hydrogen peroxide solution without a change.
-And the particulate matter PM collected for each was dried after filtration and weighed.

The test results of the second example are as shown in Table 1 above, and the degreasing performance of the sodium silicate solution was demonstrated.
That is, in the Example of this invention, 53.5g of particulate matter PM was collect | recovered and removed by the washing | cleaning of the sodium silicate solution of the 1st immersion tank 13 first. In the water washing of the comparative example, it was only 39.1 g.
Further, in the embodiment of the present invention, 1. While 42.7 g was recovered with the hydrogen peroxide solution in the second immersion tank 14, it was only 18.1 g in the comparative example, and the total was 57.2 g of the comparative example with respect to 96.2 g of the example. A synergistic effect of acid soda solution cleaning on hydrogen peroxide solution cleaning was also demonstrated.
About Example 2, it is as above.

Next, Example 3 will be described. In the third embodiment, the particulate matter PM purification device 9, that is, the DPF filter 3 (WMF) is disassembled into one unit element and subjected to a cleaning test. did.
Test conditions such as filter 3, sodium silicate solution, hydrogen peroxide solution, etc. and test steps are almost the same as those described in Example 1.
However, the filter 3 was used after being disassembled into one unit element as in Example 2 described above. Also, the sodium silicate _solution, SiO 2: _Na 2 O is 1.72: 1 using the commercially available products, were prepared water 10kg added to the 1 kg.
In addition, as Comparative Example A, the washing solution of the first immersion tank 13 was subjected to a washing test by adding water instead of the sodium silicate solution. About the washing | cleaning liquid of the 2nd immersion tank 14, it was set as the hydrogen peroxide solution without a change.
-Further, as Comparative Example B, only warm water at 60 ° C was used as a cleaning solution, and a warm water cleaning test was performed.
・ A reflection color difference meter (MINOLTA CR-300) was used to measure the brightness. Then, the lightness L of the outer surface of the filter 3 (specifically, the outer peripheral surface of the filter 3 having a substantially donut shape) was measured. The higher the value of the lightness L, the higher the light reflectance and the brighter.
First, the used filter 3 before cleaning had black particulate matter PM as a whole attached thereto, and had no metallic luster of stainless steel, and its lightness L was 4.7L. (The filter 3 has a lightness of about 30L to 40L before use, that is, in a new state.)

The test results of Example 3 are as shown in Table 2 above, and the effect of the present invention was demonstrated.
That is, the L value was highest in the example of the present invention in which sodium silicate solution and hydrogen peroxide solution were sequentially used in combination and washed. Comparative Example A washed with water and hydrogen peroxide solution and Comparative Example B washed only with 60 ° C. warm water had low L values. Thereby, according to the Example of this invention, the particulate matter PM of the filter 3 was fully and reliably removed, and it was proved that Comparative Examples A and B are insufficient.
In addition, about the filter 3 cleaned in the embodiment of the present invention, the lightness L at the internal position was measured by cutting and disassembling not the lightness L of the surface as described above, but the internal lightness L was 36.1. And 28.4. That is, it was proved that the inside of the filter 3 that is considered to be relatively difficult to clean is also cleaned fairly well.
About Example 3, it is as above.

Finally, Example 4 will be described. In Example 4, the cleaning device 9 for the particulate matter PM, that is, the DPF filter (WMF) was subjected to a cleaning test, and the waste liquid treatment of the cleaning liquid after cleaning was grasped.
Test conditions and test steps such as filter 3, sodium silicate solution, hydrogen peroxide solution, etc. are the same as those described in Example 1.
-The pH value of the sodium silicate solution in the first immersion tank 13 after washing and after use was about 11. Moreover, the pH value of the hydrogen peroxide solution in the second immersion tank 14 was about 3 to 4.

And in this Example 4, the sodium silicate solution and hydrogen peroxide solution which are the waste liquid after such washing | cleaning were mixed and left to stand for 1-2 days. Then, the mixed solution was neutralized and detoxified with a pH value of about 7-8. The concentration of hydrogen peroxide H ₂ O ₂ remaining in the liquid was 1% or less.
Note that the particulate matter PM floating in the liquid, that is, the particulate matter PM removed from the filter 3, naturally settled after the fact. Furthermore, when 20 ppm to 1,000 ppm of polyaluminum chloride as a flocculant (coagulant, coagulant) was added, the particulate matter PM was agglomerated and precipitated, and separated from the transparent supernatant.
About Example 4, it is as above.

The chemical cleaning method and the chemical cleaning apparatus of the diesel exhaust gas purification apparatus according to the present invention will be described for the best mode for carrying out the invention. (1) FIG. 1 is a front explanatory view of the chemical cleaning apparatus. 2) is a perspective view of the assembled filter, and (3) is a perspective view of a unit element of the filter. FIG. 3 is a front sectional view of a diesel exhaust gas purification device for explaining the best mode for carrying out the invention. FIG. 3 is a system diagram of a diesel exhaust system for explaining the best mode for carrying out the invention.

Explanation of symbols

1 Diesel Engine 2 Exhaust Gas Purifier 3 Filter (Unit)
DESCRIPTION OF SYMBOLS 4 Exhaust gas 5 Exhaust pipe 6 Fuel tank 7 Outer cylinder case 8 Purifier 9 Purifier 10 Ventilation hole 11 Shielding plate 12 Chemical cleaning apparatus 13 1st immersion tank 14 2nd immersion tank PM Particulate matter

Claims (8)

About a diesel engine exhaust gas purification device, a method for cleaning a unit to which particulate matter has adhered,
The unit is first immersed in an alkaline sodium silicate solution, degreased and washed, and then immersed in a hydrogen peroxide solution to be cleaned by oxidizing and foaming the generated oxygen. A method for chemically cleaning a diesel exhaust gas purification device. A method for cleaning and regenerating a filter on which particulate matter has been collected and adhered in the chemical cleaning method for a diesel exhaust gas purification device according to claim 1,
First, the filter is immersed in an alkaline sodium silicate solution to dissolve and degrease the oil content of the particulate matter adhering to the filter. After quite peeling off the filter and washing the filter,
Next, the filter is immersed in a hydrogen peroxide solution, and the carbon particles of the particulate matter adhering to the filter are oxidized with oxygen generated from hydrogen peroxide under alkaline conditions. And removing the particulate matter adhering to the filter not only from the surface but also from the inside and continuously discharging it with the generated oxygen bubbles, and washing the filter. A method for chemically cleaning a diesel exhaust gas purification device.   3. The method for chemical cleaning of a diesel exhaust gas purification device according to claim 2, wherein the hydrogen peroxide solution contains a stabilizer that maintains the activity of hydrogen peroxide. Chemical cleaning method.   4. The method for chemical cleaning of a diesel exhaust gas purification device according to claim 3, wherein the hydrogen peroxide solution has a hydrogen peroxide concentration of less than 6% and sodium pyrophosphate is used as a stabilizer. And a chemical cleaning method for a diesel exhaust gas purification device.   3. The chemical cleaning method for a diesel exhaust gas purifier according to claim 2, wherein the sodium silicate solution has a pH value of about 8.5 to 11.5. Cleaning method.   3. The chemical cleaning method for a diesel exhaust gas purification apparatus according to claim 2, wherein the alkaline sodium silicate solution and the acidic hydrogen peroxide solution after use are neutralized by mixing, and residual hydrogen peroxide. A chemical cleaning method for a diesel exhaust gas purification device, characterized in that the waste liquid is decomposed by contact and catalytic action of the carbon particles of the particulate matter removed from the filter, thereby detoxifying. About the exhaust gas purification device of a diesel engine, it is a chemical cleaning device for cleaning a unit to which particulate matter has adhered, and has a first immersion tank and a second immersion tank,
The first immersion tank is filled with an alkaline sodium silicate solution, and the unit is first immersed, degreased and cleaned,
The second immersion tank is filled with a hydrogen peroxide solution, and the unit recovered from the first immersion tank is immersed and cleaned by oxidizing and foaming the generated oxygen. Chemical cleaning equipment for diesel exhaust gas purification equipment. A chemical cleaning device for a diesel exhaust gas purification device according to claim 7, wherein the filter on which particulate matter has been collected and adhered is cleaned and regenerated,
In the first immersion tank, the filter is immersed in an alkaline sodium silicate solution, and the oil of the particulate matter adhering to the filter is dissolved and degreased, so that the particulate matter is considerably peeled and removed. The filter is washed,
In the second dip tank, the filter collected from the first dip tank is immersed in a hydrogen peroxide solution, and particles adhered to the filter with oxygen generated from hydrogen peroxide under alkaline conditions. The carbon particles of the particulate matter are oxidized, and the particulate matter is peeled and removed. Further, the generated oxygen bubbles cause the particulate matter attached to the filter to be peeled and removed not only from the surface but also from inside. Thus, the chemical cleaning device of the diesel exhaust gas purification device, wherein the filter is cleaned.

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