JP2013029102A - Methods for regeneration and inspection of diesel particulate filter, and device for regeneration of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods for regeneration and inspection of a diesel particulate filter, and a device for regeneration of the same, capable of easily reproducing a harsh environment similar to that when using an engine.SOLUTION: This method for regeneration of the diesel particulate filter includes: a first step of supplying to a diesel particulate filter a first gas wherein an inert gas and a first combustion exhaust gas obtained by combusting fuel in a burner are mixed, and igniting the soot deposited at the diesel particulate filter; and a second step of, after the first step, supplying to the diesel particulate filter a second gas having a lower flow rate and a higher oxygen concentration than the first gas, and further combusting the ignited soot.

Description

  The present invention relates to a regeneration method, an inspection method, and a regeneration device for a diesel particulate filter.

  A diesel particle filter is a ceramic filter that mainly collects soot contained in exhaust gas from a diesel engine.

  In order to regenerate a diesel particulate filter that has collected soot, it is necessary to burn the soot collected in the diesel particulate filter. In order to burn the soot, it is only necessary to supply a large amount of combustion exhaust gas at a high temperature to the filter, ignite the soot, and burn out the soot. Such combustion exhaust gas includes combustion exhaust gas from a diesel engine operating at a high speed.

  When regenerating a diesel particulate filter, the diesel particulate filter may be damaged by the combustion heat of soot. Therefore, it is important to evaluate the heat resistance performance of the filter by performing regeneration under various regeneration conditions.

  Although it is conceivable to perform evaluation by supplying exhaust gas from an actual engine to a diesel particle filter, it is not easy to control the output of the actual engine with good reproducibility. Therefore, it is conceivable to regenerate under various regeneration conditions with good reproducibility by adopting a burner that easily controls the output instead of the engine and controlling the amount of fuel supplied to the burner. As such a reproducing apparatus, for example, a reproducing apparatus described in Non-Patent Document 1 is known.

T. Hands, M. Twigg and M. Gallinge, "A new Instrument for DieselParticulate Filter Functional Testsin Development and Quality ControlApplications", SAE International, 2010-01-0809 (2010)

  By the way, as a result of studies by the present inventors, the following has been found. When exhaust gas from a diesel engine is actually supplied to the diesel particle filter instead of using a burner, the engine speed is high enough until the soot burns out after ignition of the soot by the exhaust gas If the condition continues, the flow rate of the combustion exhaust gas is large and the heat removal from the diesel particulate filter is suitably performed. Moreover, the oxygen concentration in the combustion exhaust gas is low, so the soot burning speed is not so high, and the regeneration is in progress. In particular, the temperature of the diesel particulate filter does not rise rapidly. However, after the ignition of the soot and before the soot burns out, if the rotational speed of the diesel engine returns to the idle state, the flow rate of the combustion exhaust gas becomes insufficient, the heat removal amount decreases, and the oxygen concentration in the combustion exhaust gas also increases. Since the burning rate of the soot increases, the burning temperature of the soot rapidly increases. For this reason, under such severe conditions, the temperature of the diesel particulate filter rises rapidly, and cracks are particularly likely to enter the diesel particulate filter due to thermal stress.

  And when the combustion gas from a burner was supplied to the diesel particle filter and the above-mentioned conditions were simulated, it turned out that severe conditions like the case where an engine was used are not fully reproduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a diesel particle filter regeneration method, inspection method, and regeneration device that can easily reproduce the same severe conditions as when an engine is used. And

The method for regenerating a diesel particle filter according to the present invention supplies a first gas obtained by mixing a first combustion exhaust gas obtained by burning fuel with a burner and an inert gas to the diesel particle filter, and the diesel particle filter A first step of igniting the soot accumulated on the filter;
After the first step, a second step of supplying a second gas having a lower flow rate and higher oxygen concentration than the first gas to the diesel particle filter and further burning the ignited soot.

A diesel particulate filter regenerating apparatus according to the present invention comprises:
A burner, an air supply device for supplying air to the burner, a fuel supply device for supplying fuel to the burner, a main supply passage for supplying combustion exhaust gas from the burner to a diesel particulate filter, and the main supply passage An inert gas supply path for supplying an inert gas.

  As a result of studies by the present inventors, when a burner is used instead of the engine, the oxygen concentration in the combustion exhaust gas is used in the first step, that is, in the step of simulating high-speed operation of the engine. Therefore, it was found that the difference from the oxygen concentration in the subsequent second step, that is, the step of simulating idle operation, is difficult to occur, and a harsh state cannot be reproduced.

  According to the method of the present invention, in the first step, the oxygen concentration in the first gas supplied to the diesel particulate filter can be sufficiently lowered by the inert gas as compared with the second gas. The same severe conditions as when using an engine can be easily reproduced.

  Since the apparatus according to the present invention has the inert gas supply path, the first process and the second process described above can be easily performed.

  Here, it is preferable that the volume fraction of oxygen in the first gas is 1 to 15%, and the volume fraction of oxygen in the second gas is 10 to 21%.

  Moreover, it is preferable that the flow rate of said 1st gas is 100-300 kg / h, and the flow rate of said 2nd gas is 10-90 kg / h.

  Moreover, it is preferable that the temperature of said 1st gas and 2nd gas is 200-800 degreeC.

The second gas includes a second combustion exhaust gas obtained by burning fuel with a burner,
The fuel supply rate for obtaining the second combustion exhaust gas is preferably lower than the fuel supply rate for obtaining the first combustion exhaust gas.
According to this, it is easy to make the second gas have the same temperature, flow rate, and oxygen concentration as when the engine is idling.

  Moreover, it is preferable to preheat the inert gas before mixing with the first gas. Moreover, it is preferable to further include a heater for preheating the inert gas flowing through the inert gas supply path. Thereby, temperature control of the first gas is facilitated.

  In the method for inspecting a diesel particulate filter according to the present invention, any of the methods described above, and in the middle of the first step and the second step, or after the second step, cracks occurred in the diesel particulate filter. And inspecting whether or not.

In the apparatus according to the present invention, the air supply unit has a valve for adjusting the supply amount of the air, and a valve for adjusting the supply amount of the inert gas is connected to the inert gas supply path.
A gas having a lower flow rate and a higher oxygen concentration than the mixed gas in the first state from the first state in which the mixed gas of the first combustion gas obtained from the burner and the inert gas is supplied to the diesel particle filter It is preferable to further include a control unit that controls the two valves so that the transition to the second state supplied to the diesel particulate filter.

  ADVANTAGE OF THE INVENTION According to this invention, the reproduction | regeneration method of a diesel particulate filter, the inspection method, and the reproduction | regeneration apparatus which can reproduce easily the severe conditions similar to the case where an engine is used are provided.

FIG. 1A is a perspective view of a diesel particle filter 100 to be regenerated, and FIG. 1B is a view taken in the direction of arrows Ib-Ib in FIG. FIG. 2 is a flowchart of the regenerator 400 of the diesel particle filter 100 according to the embodiment of the present invention. FIG. 3 is a conceptual diagram of the change over time in the gas amount, oxygen concentration, inlet side temperature and outlet side temperature of the diesel particulate filter.

An embodiment of the invention will be described with reference to the drawings.
(Diesel particle filter)
First, an example of a diesel particle filter (DPF) 100 to be regenerated in this embodiment will be described. The diesel particle filter 100 mainly collects soot particles discharged from a diesel engine, for example.

  As shown in FIGS. 1A and 1B, the diesel particle filter 100 includes partition walls 112 that form a plurality of flow paths 110 that extend in parallel to each other, and some of the plurality of flow paths 110. It is a cylindrical body having a sealing portion 114 that closes one end (the left end of FIG. 1B) and the other end of the remaining part of the plurality of flow paths 110 (the right end of FIG. 1B). It has a surface 100in and an exit surface 100out.

  Although the length of the direction in which the flow path 110 of the diesel particulate filter 100 extends is not particularly limited, it can be set to 40 to 350 mm, for example. Moreover, although the outer diameter of the diesel particle filter 100 is not specifically limited, For example, it can be set as 100-320 mm. The size of the cross section of the flow path 110 can be set to 0.8 to 2.5 mm on a side in the case of a square, for example. The thickness of the partition 112 can be 0.05-0.5 mm. The apparent capacity of the diesel particle filter 100 can be set to 2 to 4 L, for example.

  The material of the partition 112 of the diesel particle filter 100 is porous ceramics (fired body). The ceramic is not particularly limited, and examples thereof include alumina, silica, mullite, cordierite, glass, oxides such as aluminum titanate, silicon carbide, silicon nitride, and metal. The aluminum titanate can further contain magnesium and / or silicon.

  As described above, the left end of a part of the plurality of flow paths 110 of the diesel particle filter 100 is sealed by the sealing portion 114, and the remaining right end of the plurality of the flow paths 110 of the diesel particle filter 100 is the sealing portion 114. Is sealed. As the material of the sealing portion 114, the same ceramic material as that of the diesel particle filter 100 can be used. The “part of the plurality of flow paths 110” and the “remaining part of the plurality of flow paths 110” described above are preferably arranged in a matrix when viewed from the end face side as shown in FIG. Of the plurality of flow paths arranged in the vertical direction and the horizontal direction in the horizontal direction.

  The diesel particle filter 100 has a porous partition wall 112. Although the pore diameter of a partition is not specifically limited, For example, it can be set as about 11-30 micrometers. In FIG. 1B, the gas supplied from the left end of the flow path 110 passes through the partition wall 112, reaches the adjacent flow path 110, and is discharged from the right end of the flow path 110. At this time, particles in the inflowing gas are removed by the partition 112, and the diesel particle filter 100 functions as a filter.

  Such a diesel particle filter 100 can be manufactured as follows, for example.

  First, an inorganic compound source powder, an organic binder, a solvent, and additives to be added as necessary are prepared. These are mixed by a kneader or the like to obtain a raw material mixture. The obtained raw material mixture is extruded from an extruder having an outlet opening corresponding to the shape of the partition wall, cut to a desired length, and then dried by a known method. By doing so, a green honeycomb molded body is obtained. Then, the end of the flow path of the green honeycomb molded body is sealed with a sealing material by a known method and fired, or the green honeycomb molded body is fired and the end of the flow path is sealed by a known method. That's fine.

(Diesel particle filter regeneration device)
Then, with reference to FIG. 2, the regeneration apparatus 400 of the diesel particle filter 100 concerning one Embodiment of this invention is demonstrated.

  The diesel particulate filter regeneration device 400 according to this embodiment includes a burner 10, a fuel supply unit 15 that supplies fuel to the burner 10, an air supply unit 25 that supplies air to the burner 10, and combustion exhaust gas from the burner 10. Is mainly provided with a main supply passage 55 for supplying the diesel particulate filter and an inert gas supply passage L2 for supplying an inert gas to the main supply passage 55.

  The fuel supply unit 15 includes a line L3 that supplies the fuel supplied from the fuel supply source S1 to the burner 10, and a valve 12 that is connected to the line L3 and controls the fuel supply amount. Although a fuel is not specifically limited, The fuel used for a diesel engine is preferable, for example, light oil is mentioned.

  The air supply unit 25 includes an air compressor 20 that compresses air, a line L4 that supplies air from the air compressor 20 to the burner 10, and a valve 22 that controls the flow rate of gas flowing through the line L4.

  The burner 10 burns the fuel supplied from the fuel supply unit 15 with the air supplied from the air supply unit 25. The type of the burner 10 is not particularly limited, and for example, the fuel may be sprayed into the air, or the fuel may be sprayed together with the air. Combustion gas from the burner 10 is supplied to the diesel particle filter 100 via the main supply path 55.

  The main supply path 55 has a line L1 connected to the discharge port of the burner 10 and a filter fixture 50 connected to the downstream end of the line L1.

  The filter fixture 50 includes a cylindrical member 51 that houses the diesel particle filter 100 and a seal member that surrounds the outer peripheral surface of the diesel particle filter 100 in an annular shape and seals between the outer peripheral surface and the inner surface of the cylindrical member 51. 52. The combustion exhaust gas supplied from the line L1 into the filter fixture 50 is supplied from the inlet surface 100in to the diesel particle filter 100 and discharged from the outlet surface 100out.

  Temperature sensors T1 and T2 for measuring respective temperatures are provided on the inlet side and the outlet side of the diesel particle filter 100.

  An inert gas supply source S2 is connected to the line L1 via an inert gas supply path L2. The inert gas is not particularly limited as long as it is a gas that does not participate in soot combustion, and examples thereof include nitrogen, argon, and helium, and nitrogen is particularly preferable. Connected to the inert gas supply path L2 are a valve 32 for controlling the supply amount of the inert gas and a heater 34 for preheating the inert gas supplied to the line L1.

  Furthermore, the line L1 is provided with a soot supply device 40 that supplies pre-stored soot to the main supply path L1.

  The controller 90 controls the gas supply amounts of the valves 12 and 32. The control unit 90 starts from the first state (first step) in which the mixed gas of the first combustion gas obtained from the burner 10 and the inert gas is supplied to the diesel particle filter 100, and then the mixed gas in the first step. The supply amount of the fuel and the inert gas is controlled so as to shift to a second state (second step) in which a gas having a lower flow rate and a higher oxygen concentration is supplied to the diesel particle filter 100. The control unit 90 can also change the supply amount of the valve 22, that is, the air in accordance with the transition from the first body to the state.

(Diesel particle filter regeneration method)
Next, a reproduction method using such a reproduction apparatus 400 will be described.
(Fixing the filter)
First, the diesel particle filter 100 is fixed to the filter fixture 50.

(Pile accumulation)
Subsequently, soot is deposited in the diesel particle filter 100. The deposition method is not particularly limited, and the soot supply device 40 can be used. Specifically, the soot stored in the soot supply device 40 in advance may be supplied and deposited on the diesel particle filter 100 with a carrier gas such as nitrogen. Further, soot may be deposited by burning the fuel with the burner 10 and supplying the combustion exhaust gas to the diesel particle filter 100 via the main supply path 55. The amount of soot to be deposited on the diesel particle filter 100 is not particularly limited. For example, the weight per apparent volume of the diesel particle filter 100 can be 2 to 20 g / L.

(First step (ignition))
Subsequently, the deposited soot is ignited. Specifically, first, fuel is supplied from the fuel supply source S1 to the burner 10, and air is supplied from the air compressor 20 to the burner 10, and the fuel is burned by the burner 10 to obtain first combustion exhaust gas. The obtained first combustion exhaust gas is supplied to the main supply passage 55. At the same time, an inert gas is further supplied from the inert gas supply source S2 to the main supply passage 55 and mixed with the first combustion exhaust gas. Thereby, the first gas obtained by mixing the first combustion exhaust gas obtained from the burner 10 and the inert gas supplied from the inert gas supply source S <b> 2 is supplied to the diesel particle filter 100.

  From the viewpoint of igniting the soot of the diesel particle filter 100, the temperature of the first gas supplied to the diesel particle filter 100 is preferably 200 to 800 ° C, and more preferably 200 to 750 ° C. In addition, it is also preferable to preheat the inert gas with the heater 34 from the viewpoint of maintaining the temperature of the first gas at a high temperature. Note that the present invention can be implemented without preheating with the heater 34.

  The addition amount of the inert gas is not particularly limited, but is preferably added so that the volume fraction of oxygen in the first gas is 1 to 15%, and is added so as to be 3 to 15%. It is more preferable.

  Moreover, it is preferable that the supply amount with respect to the diesel particle filter 100 of 1st gas is 100-300 kg / h.

  The fuel supply rate and the air supply rate can be appropriately set so that the temperature, supply amount, and oxygen concentration of the mixed gas satisfy the above-mentioned requirements.

  The time for which the first gas is continuously supplied to the diesel particle filter 100 is not particularly limited as long as it is longer than the time necessary for the soot to ignite, and can be set to 1 to 240 seconds, for example.

  By this first step, the soot collected in the diesel particle filter 100 is ignited, and soot combustion starts. This process corresponds to a state where the high speed state continues in the engine.

(Second process (lean combustion))
Subsequently, the flow rate of the gas (second gas) supplied to the diesel particle filter 100 via the main supply path L1 is decreased, and the oxygen concentration is increased. Specifically, for example, the amount of fuel supplied from the fuel supply source S1 is reduced from the first step, and the addition amount of the inert gas is further reduced from the first step. Preferably, the amount of inert gas added is zero. The flow rate mentioned here is the mass of gas supplied to one filter per unit time.

  The temperature of the second gas supplied to the diesel particle filter 100 is preferably 200 to 800 ° C, and preferably 200 to 750 ° C.

  The oxygen concentration of the second gas only needs to be higher than the oxygen concentration of the first gas. Specifically, the oxygen volume fraction is preferably 10 to 21%, and preferably 16 to 21%. More preferred. If the supply amount of air is the same as that in the first step and the supply amount of fuel is lowered, the oxygen concentration usually increases.

  The supply amount of the second gas to the diesel particle filter 100 may be lower than the supply amount of the first gas, but is preferably 10 to 90 kg / h.

  Further, an inert gas may be mixed with the second combustion exhaust gas, but it is preferable not to mix the inert gas from the viewpoint of increasing the oxygen concentration of the second gas and obtaining harsh conditions.

  The fuel supply speed and the air supply speed in the second step can be appropriately set so that the temperature, supply amount, and oxygen concentration of the mixed gas satisfy the above-described requirements. Although air at room temperature may be used as it is as the second gas without supplying fuel, since the gas higher than normal temperature is supplied when the engine is idle, it is preferable that the fuel is not zero to reproduce the idle state. It is preferable to supply a fuel capable of setting the temperature of the second combustion exhaust gas within the above range.

  In the second step, the gas flow rate is lower than that in the first step and the oxygen concentration is increased, so that the combustion temperature of the soot is increased and the diesel particulate filter 100 is heated rapidly.

Although the time which continues supplying this 2nd gas to the diesel particulate filter 100 is not specifically limited, It is preferable to perform a 2nd process until the combustion temperature of soot exceeds a peak. For example, it may be 1 to 240 seconds. Preferably, the second step is preferably continued until the removal rate by burning soot is 50% or more.
The transition from the first step (first state) to the second step (second state) may be automatically performed by the control unit 90, or an operator manually adjusts the various valves described above. Can also be executed.

(Inspection for crack occurrence)
After the second step, the diesel particle filter 100 is tested for cracks. The method for detecting the occurrence of cracks is not particularly limited. For example, the pressure loss when gas flows through the diesel particle filter 100 under the same conditions before and after the first step is measured. If the value decreases rapidly, it can be determined that a crack has occurred. Further, when performing the first step and the second step, the presence or absence of cracks may be confirmed by detecting the sound generated from the diesel particle filter 100. Of course, it is also possible to visually check for cracks after the second step.

  The conceptual diagram of the time change of the gas amount by this embodiment, oxygen concentration, the inlet side temperature of a diesel particulate filter, and outlet side temperature is shown in FIG. According to the present embodiment, the first gas obtained by mixing the first combustion exhaust gas with the inert gas is supplied to the diesel particle filter 100 in the first step S1. Thereby, oxygen concentration O1 in the mixed gas in 1st process S1 can be made low enough. Therefore, since the difference in oxygen concentration from the oxygen concentration O2 of the second gas supplied in the subsequent second step S2 can be increased, the soot combustion rate can be sufficiently increased in the second step S2. Therefore, by switching from the first step S1 to the second step S2, a rapid heat load can be applied to the diesel particle filter 100, and the heat resistance is easily evaluated. In particular, the temperature on the outlet side of the diesel particle filter 100 rises sharply.

The present invention is not limited to the above-described embodiment, and various modifications can be made.
For example, the aspect of the filter fixing part 50 of the main supply part 55 is not particularly limited as long as it can supply gas to the filter. Further, the present invention can be implemented even if the line L2 and the basket supply device 40 are connected to the filter fixing unit 50.

  Moreover, in the said embodiment, although the cross-sectional shape of the flow path 110 of the diesel particle filter 100 is substantially square, it is not limited to this, It is set as a rectangle, a circle, an ellipse, a triangle, a hexagon, an octagon, etc. Can do. Moreover, in the flow path 110, those with different diameters and those with different cross-sectional shapes may be mixed. Further, the arrangement of the flow paths is also a square arrangement in FIG. 1, but is not limited to this, and an equilateral triangle arrangement in which the central axis of the flow path is arranged at the apex of the equilateral triangle in the cross section, and the cross section of the flow path is a square or In the case of a rectangle, a staggered arrangement or the like can be used. Further, the outer shape of the honeycomb filter is not limited to a cylinder, and may be, for example, a triangular column, a quadrangular column, a hexagonal column, an octagonal column, or the like.

  DESCRIPTION OF SYMBOLS 10 ... Burner, 15 ... Fuel supply part, 25 ... Air supply part, 34 ... Heater, 55 ... Main supply path, L2 ... Inert gas supply path, 90 ... Control part, 100 ... Diesel particle filter, 400 ... Diesel particle filter Playback device.

Claims (10)

A first step of supplying a first gas mixed with a first combustion exhaust gas obtained by burning fuel with a burner and an inert gas to a diesel particle filter, and igniting the soot deposited on the diesel particle filter; ,
After the first step, a second step of supplying a second gas having a lower flow rate and higher oxygen concentration than the first gas to the diesel particle filter, and further burning the ignited soot,
A method for regenerating a diesel particulate filter.   The method according to claim 1, wherein the volume fraction of oxygen in the first gas is 1 to 15%, and the volume fraction of oxygen in the second gas is 10 to 21%.   The method according to claim 1 or 2, wherein the flow rate of the first gas is 100 to 300 kg / h, and the flow rate of the second gas is 10 to 90 kg / h.   The method according to any one of claims 1 to 3, wherein the temperatures of the first gas and the second gas are 200 to 800 ° C. The second gas includes a second combustion exhaust gas obtained by burning fuel with a burner,
The method according to claim 1, wherein a supply rate of the fuel for obtaining the second combustion exhaust gas is lower than a supply rate of the fuel for obtaining the first combustion exhaust gas.   The method according to claim 1, wherein the inert gas is preheated before being mixed with the first gas. The method according to any one of claims 1 to 6,
A method for inspecting a diesel particle filter, comprising: inspecting whether or not a crack has occurred in the diesel particle filter during the first step and the second step or after the second step. With a burner,
An air supply unit for supplying air to the burner;
A fuel supply section for supplying fuel to the burner;
A main supply path for supplying combustion exhaust gas from the burner to the diesel particle filter;
An inert gas supply path for supplying an inert gas to the main supply path;
An apparatus for regenerating a diesel particulate filter.   The apparatus according to claim 8, further comprising a heater for preheating the inert gas flowing through the inert gas supply path. The air supply unit has a valve for adjusting the supply amount of the air,
A valve for adjusting the supply amount of the inert gas is connected to the inert gas supply path,
A gas having a lower flow rate and a higher oxygen concentration than the mixed gas in the first state from the first state in which the mixed gas of the first combustion gas obtained from the burner and the inert gas is supplied to the diesel particle filter The apparatus of Claim 8 or 9 further equipped with the control part which controls these two valves so that may change to the 2nd state supplied to the said diesel particulate filter.

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