JP2003239721A - Method for regenerating exhaust gas particulate filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a thermal load of a filter material and an influence of a hot spot to the filter material even if biased deposition of a captured flammable substance exists when a filter function is regenerated by burning soot and SOF captured in an exhaust gas particulate filter for capturing a floating granular substance of a diesel engine, to outstandingly improve durability of the filter material such that the whole area of the filter material is not accompanied with outstanding temperature rise propagated from a burning starting temperature area, and to remove an inflammable substance such as a burned residue and a rust. <P>SOLUTION: In the state where the engine is stopped, separately from a usual exhaust gas route from the engine to DPF, a release route for hot air containing burned gas enabling hot air containing the burned gas generated by burning/treating the captured flammable substance to be released to an atmosphere not through the engine is provided at an upstream of the DPF. The hot air having sufficient temperature required for burning the captured flammable substance is circulated from the downstream toward the upstream side against the DPF. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to DP soot and SO which are harmful components in exhaust gas of a diesel engine.
It relates to regenerating the clogged state of the filter material in the DPF used for capturing F to the original state without clogging.

[0002]

2. Description of the Related Art A DPF filter material is formed by forming a fibrous ceramic sheet into a bellows shape, or is made of porous ceramic and has a checkerboard pattern on the exhaust gas outlet side and the inlet side of each cell forming an exhaust gas passage. A wall flow structure in which the cell ends are alternately plugged in is generally used, and basically, the DP is captured by a filter material to filter the exhaust gas.

Regarding the DPF used for capturing soot and SOF which are harmful components in the exhaust gas of a diesel engine, when the regenerator is not used together, that is, when only the DPF is used alone, the operating time or running distance of the engine When the filter portion gradually becomes clogged by the captured DP due to the increase of, the engine output is decreased due to the increase of the pressure loss of the filter portion, and the fuel consumption of the engine is increased, which is uneconomical. . Further, if the clogging is extremely advanced, the engine itself cannot be operated.

Since most of the components of DP captured by the filter material are combustible substances (hereinafter referred to as captured combustible substances), the DP is heated by an electric heater incorporated in the DPF filter material itself. Alternatively, the temperature of the engine exhaust gas itself is raised to the combustion temperature of the combustible substance by the burner device, and the exhaust gas is passed through the DPF.
Various methods have been considered for incinerating the DP captured by the filter to regenerate the filter portion.

However, in the conventional regeneration method, the temperature rise due to the heat accompanying the combustion of the trapped combustible substance not only causes the filter material to be exposed to a temperature considerably higher than the combustion starting temperature range of the trapped combustible substance. Depending on the accumulation distribution state of the captured combustibles, a so-called hot spot portion where the filter material locally becomes abnormally high temperature is generated, and a filter material generally made of porous ceramic or ceramic fiber is used. It was difficult to maintain the function of the DPF for a long period of time because it burned out or cracked the filter material.

In addition, combustion residues made of ash and the like in fuel oil for driving the engine and rust and the like generated in the exhaust pipe are accumulated in non-combustible substances (hereinafter referred to as trapped non-combustible substances) captured by the filter material. The problem of going forward could not be addressed by the conventional method.

FIG. 17 shows a conventional example of an electric heater system in which an electric heater is built into the filter material of the DPF itself and the DPF is regenerated by energizing the electric heater while the engine is stopped.

FIG. 18 shows an example of a conventional after-burner system in which the exhaust gas of an engine itself is heated to a combustion start temperature of a combustible substance captured by the DPF by a burner device to regenerate the DPF.

FIG. 5 shows a hot air temperature change (26) associated with the combustion of the trapped DP (23) during regeneration of the filter material in the prior art of FIG. The heat of combustion of the collected DP (23) inevitably exposes the filter material (5) to a high temperature.

In the prior art of FIG. 17, the collection DP
The stagnation of the combustion heat of (23) exposes the filter material (5) to a higher temperature. Moreover, it collects locally D
Needless to say, the combustion of the portion where P (23) is heavily deposited becomes extreme and hot spots are generated, and the heat load on the filter material (5) becomes more severe.

[0011]

The heat load on the filter material at the time of burning the trapped combustible substance is reduced, and even if the trapped combustible substance is unevenly deposited, hot spots are formed on the filter material. The effect of the above can be reduced and the temperature of the entire filter material does not rise significantly above the combustion starting temperature range, so that the durability of the filter material is significantly improved and the removal of incombustible substances such as combustion residues and rust is possible. With the goal.

[0012]

In order to achieve the above object, in the regeneration method of the present invention, first, a device for supplying hot air by heating air with an electric heater or a fuel gas or fuel oil is provided. Not only is it easy to set the hot air temperature to the combustion start temperature of the captured combustible substance because the temperature can be accurately controlled by a device that supplies hot air by burning only with air, but the oxygen concentration Since high hot air can be used, the combustion temperature of the captured combustible substance can be set to a low level, so that the absolute value of the hot air temperature can be basically lowered to reduce the heat load on the filter material.

Secondly, when the engine is stopped, hot air containing incineration gas obtained by incineration of the captured combustible substances is allowed to pass through the engine upstream of the DPF, apart from the normal exhaust gas path from the engine to the DPF. A hot air release path containing incineration gas that can be released into the atmosphere is provided, and hot air having a temperature necessary and sufficient for burning the trapped combustible substance is directed from the downstream side to the upstream side with respect to the DPF. Circulating and absorbing the amount of radiant heat that the filter material receives with the combustion of the trapped combustible substance by the hot air passing through the filter material, and excessively raising the temperature of the filter material itself by heat transfer by the flow of hot air. Instead, the combustible substance captured on the surface of the filter material is burned and removed, and at the same time, the captured incombustible substance is desorbed and removed.

During regeneration of the DPF, it is desirable to shut off the exhaust gas path from the engine to the DPF so that the incineration gas and the incombustibles flow back to the engine due to the hot air and do not hinder the engine body.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings. The following description of the flow direction is based on the exhaust gas flow direction during engine operation.

In FIG. 1 and FIG. 2, a closed-state sluice valve (19) for shutting off the exhaust gas flow of an ordinary exhaust gas pipe (3) from the engine to the DPF upstream of the DPF is provided, and the trapped gas is upstream of the DPF. A hot air discharge pipe (16) is provided to allow hot air (15) containing incineration gas obtained by incinerating burnable materials to be released to the atmosphere without passing through the engine, and
An electrothermal air heater (10) or burner (11) for supplying hot air (13) having a temperature and oxygen concentration necessary and sufficient to burn the trapped combustible material is connected downstream of the DPF, and the hot air is fed into the DPF. Circulates from downstream to upstream.

FIG. 3 shows a hot air temperature change (26) associated with the combustion of the collection DP (23) of the combustible substances captured by the filter material.

The combustion start temperature of the trapped combustible substance depends on the properties of the combustible substance and the oxygen concentration in the hot air, but is usually 450 to 550 ° C., and therefore the hot air (13) having the above combustion start temperature is used. Is heated from the downstream of the DPF to burn the trapped combustible substance, but the hot air is heated and heated, but since it is the combustion after passing through the filter material, the filter material is not exposed to an unnecessarily high temperature.

Therefore, it is possible to prevent the filter material temperature from excessively rising due to the combustion of the trapped combustible material, prevent the filter material from being burnt or cracked, and reasonably burn and remove the combustible material trapped in the filter material. You can do it.

FIG. 4 is a schematic view of a situation in which the incombustible substance (27) trapped in the exhaust gas flow during engine operation is separated from the surface of the filter material (5) by the backwashing action by the reverse flow of the hot air (13). The figure is shown.

Small particles of the incombustible material (27) captured by the filter material are conveyed to the atmosphere by the hot air flow, and relatively large particles fall and accumulate on the upstream side of the DPF. Here, it is desirable to provide means for preventing the non-combustible substances that have fallen and accumulated from being scattered by the exhaust gas flow during the subsequent engine operation and captured again on the surface of the filter material.

FIG. 8 shows a hot air generator (7) when the DPF is not regenerated in FIGS. 1 and 2, that is, when the engine is operating normally.
14 to 14) and the hot air discharge pipe (16) are removed.

[0023]

EXAMPLE FIG. 14 shows an example in which the regeneration state and the non-regeneration state of the DPF, that is, the normal operation state of the engine can be easily dealt with. Even in this case, the hot air generators (7 to 14) and the hot air discharge pipe (16) may be always installed or may be installed at any time. This is shown in Figure 1.
It goes without saying that the same applies to the item 1.

FIG. 15 shows soot and S in the middle of the hot air discharge pipe.
An example in which an incinerator gas purification device (28) for removing harmful components generated by the combustion of OF is installed will be shown.

FIG. 16 shows a DPF structure having a non-combustible substance reservoir (29) and a non-combustible substance discharge port (30) of the non-combustible substance desorbed from the filter for collecting the non-combustible substance having relatively large particles. An example of is shown.

[0026]

As described above, it is possible to prevent the filter material temperature from excessively rising due to the combustion of the trapped combustible substance, so that it is possible to prevent the filter material from being burnt or cracked. Further, the trapped non-combustible substance can be removed by removing the non-combustible substance from the trapping surface of the filter material by the backwashing action by the flow of hot air.

With the above effects, it is possible to provide an inexpensive and highly reliable method of regenerating the DPF function for recovering the clogging state of the filter material to the non-clogging state. At the same time, it becomes unnecessary to use a high-grade filter material having high heat resistance, and an inexpensive DPF can be applied. Therefore, it can contribute to the spread of DPF application to diesel engines.

[Brief description of drawings]

FIG. 1 shows an entire system according to a first embodiment of the present invention.

FIG. 2 shows an entire system according to a second embodiment of the present invention.

FIG. 3 shows the hot air temperature change (26) associated with the combustion of the collected DP (23) in the upstream and downstream of the filter material (5) in the present invention.

FIG. 4 is a schematic view showing the state of desorption of the incombustible substance (27) from the filter material (5) in the present invention.

FIG. 5 shows a situation of a hot air temperature change (26) associated with the combustion of the collecting DP (23) in the upstream and the downstream of the filter material (5) in the prior art.

FIG. 6 shows a state during regeneration of the DPF (4) in FIGS. 1 and 2.

FIG. 7 shows a view on arrow A in FIG.

FIG. 8 is a non-regenerating state of the DPF (4) in FIGS.
That is, the state during normal operation of the engine is shown.

9 shows a view on arrow B in FIG.

FIG. 10 shows a third embodiment.

FIG. 11 shows a fourth embodiment.

FIG. 12 shows a state during non-regeneration of the DPF (4) in FIG. 11, that is, a state during normal engine operation.

FIG. 13 shows a fifth embodiment.

FIG. 14 shows a sixth embodiment.

FIG. 15 shows a seventh embodiment.

FIG. 16 shows an eighth embodiment.

FIG. 17 shows an explanatory diagram of a conventional technique.

FIG. 18 shows an explanatory diagram of another conventional technique.

[Explanation of symbols]

1 diesel engine 2 exhaust gas 3 exhaust gas pipe 4 DPF 5 Filter material 6 Electric heater built-in filter material 7 power cord 8 air fans 9 air tubes 10 Electric heating air heater 11 burners 12 Fuel 13 hot air 14 Hot air supply pipe 15 Hot air containing incineration gas 16 Hot air discharge tube 17 Flange 18 blind flange 19 Closed gate valve 20 open state sluice valve 21 Closed damper 22 Open damper 23 Collection DP 24 Hot air temperature 25 Hot air temperature including incineration gas 26 Hot air temperature change 27 Incombustible substances 28 Incineration gas purification device 29 Non-combustible substance reservoir 30 Non-combustible substance outlet

Claims (5)

[Claims] 1. An exhaust gas particulate filter (hereinafter referred to as "filter" used to capture soot and soluble organic matter (hereinafter referred to as "SOF"), which are suspended particulate matter (hereinafter referred to as "DP"), which are harmful components in exhaust gas of a diesel engine. , DPF) provided in the exhaust gas treatment device, the device for supplying hot air by heating the air with an electric heater to burn the trapped soot and SOF, or the hot air by burning the fuel gas or fuel oil with the air. Hot air having a temperature and oxygen concentration necessary for burning soot and SOF obtained from a device for supplying DPF
The hot air including the incineration gas obtained by incineration of soot and SOF can be discharged to the atmosphere through the route provided separately from the normal exhaust gas route connected to the engine main body on the upstream side of the DPF while supplying air from the downstream side. As a route configuration, DPF
The soot and SOF trapped in the filter material are incinerated and the combustion residue consisting of ash in the fuel oil for engine drive trapped in the filter material and the non-combustible substance such as rust generated inside the exhaust gas pipe are reversed. A DPF characterized by recovering the clogging state of the filter material and regenerating the filter function by removing it from the filter material by a washing action.
How to play. 2. An exhaust gas particulate filter (hereinafter referred to as "filter" used to capture soot and soluble organic matter (hereinafter referred to as "SOF"), which are suspended particulate matter (hereinafter referred to as "DP"), which are harmful components in exhaust gas of a diesel engine. , DPF) provided in the exhaust gas treatment device, the device for supplying hot air by heating the air with an electric heater to burn the trapped soot and SOF, or the hot air by burning the fuel gas or fuel oil with the air. Hot air having a temperature and oxygen concentration necessary for burning soot and SOF obtained from a device for supplying DPF
An incinerator gas purification device that removes harmful components generated by combustion of SOF and soot in a route provided on the upstream side of the DPF and provided separately from the normal exhaust gas route connected from the engine body, while supplying air from the downstream side. As a path configuration capable of discharging the hot air containing the incineration gas in which the soot purified by the incinerator gas purification device and the SOF is incinerated to the atmosphere,
The soot and SOF trapped in the filter material of the DPF are incinerated, and the combustion residues made of ash in the fuel oil for engine driving trapped in the filter material and the non-combustible substances such as rust generated inside the exhaust gas pipe are removed. A DPF regeneration method characterized by recovering the clogging state of the filter material and regenerating the filter function by removing it from the filter material by backwashing. 3. An exhaust gas particulate filter (hereinafter referred to as "filter" used to capture soot and soluble organic matter (hereinafter referred to as "SOF"), which are suspended particulate matter (hereinafter referred to as "DP"), which are harmful components in exhaust gas of a diesel engine. , DPF) provided in the exhaust gas treatment device, the device for supplying hot air by heating the air with an electric heater to burn the trapped soot and SOF, or the hot air by burning the fuel gas or fuel oil with the air. Hot air having a temperature and oxygen concentration necessary for burning soot and SOF obtained from a device for supplying DPF
The hot air including the incineration gas obtained by incineration of soot and SOF can be discharged to the atmosphere through the route provided separately from the normal exhaust gas route connected to the engine main body on the upstream side of the DPF while supplying air from the downstream side. As a route configuration, and D
An incombustible substance reservoir is provided on the exhaust gas upstream side of the filter material in the PF to incinerate the soot and SOF captured by the filter material of the DPF, and the ash content in the fuel oil for engine drive captured by the filter material. It is characterized by recovering the clogging state of the filter material and regenerating the filter function by removing and collecting non-combustible substances such as rust and other non-combustible substances generated inside the exhaust gas pipe from the filter material by backwashing action. How to regenerate DPF. 4. An exhaust gas particulate filter (hereinafter referred to as "filter" used to capture soot and soluble organic matter (hereinafter referred to as "SOF"), which are suspended particulate matter (hereinafter referred to as "DP"), which are harmful components in the exhaust gas of a diesel engine. , DPF) provided in the exhaust gas treatment device, the device for supplying hot air by heating the air with an electric heater to burn the trapped soot and SOF, or the hot air by burning the fuel gas or fuel oil with the air. Hot air having a temperature of 450 ° C. or higher and an oxygen concentration of 1% by volume or higher, which is obtained from a device for supplying air, is supplied from the downstream side of the DPF, and a normal exhaust gas path connected to the engine body on the upstream side of the DPF. The hot air containing incineration gas obtained by incineration of soot and SOF is discharged to the atmosphere through a route separately provided. As an effective path configuration, soot and SOF captured in the filter material of the DPF are incinerated, and combustion residues composed of ash in the fuel oil for engine driving captured in the filter material and generated in the exhaust gas pipe are also generated. A DPF regeneration method characterized by recovering the clogging state of the filter material and regenerating the filter function by removing non-combustible substances such as rust from the filter material by backwashing. 5. An exhaust gas particulate filter (hereinafter referred to as "filter" used to capture soot and soluble organic matter (hereinafter referred to as "SOF"), which are suspended particulate matter (hereinafter referred to as "DP"), which are harmful components in exhaust gas of a diesel engine. , DPF) provided in the exhaust gas treatment device, the device for supplying hot air by heating the air with an electric heater to burn the trapped soot and SOF, or the hot air by burning the fuel gas or fuel oil with the air. Hot air having a temperature of 450 ° C. or higher and an oxygen concentration of 1% by volume or higher, which is obtained from a device for supplying air, is supplied from the downstream side of the DPF, and a normal exhaust gas path connected to the engine body on the upstream side of the DPF. Incinerator gas purification that removes harmful components generated by soot and SOF combustion in a separate path The hot air containing the incineration was incinerated gas soot and SOF, which has been purified in the incineration gas purification device provided with a location as drainable route composition to the atmosphere, DPF
The soot and SOF trapped in the filter material are incinerated and the combustion residue consisting of ash in the fuel oil for engine drive trapped in the filter material and the non-combustible substance such as rust generated inside the exhaust gas pipe are reversed. A DPF characterized by recovering the clogging state of the filter material and regenerating the filter function by removing it from the filter material by a washing action.
How to play.