JP5867279B2 - Burner device and exhaust temperature raising device - Google Patents

Description

  The present invention relates to a burner device and an exhaust temperature raising device for burning fuel.

  2. Description of the Related Art Conventionally, there is known a burner device in which liquid fuel is directly sprayed from an injector and burned onto an ignition part such as a glow plug that is heated by current. In the burner device, when the fuel is sprayed directly on the ignition part, droplets of unburned fuel may fall and the combustion efficiency may be reduced without contributing to combustion. In such a case, it is advisable to adopt a configuration in which the sprayed fuel is once attached to a carrier disposed in the vicinity of the igniting part to suppress the fall and then ignited.

  As a carrier to which such fuel is attached, a porous body having pores and high fuel retention is suitable. In the combustion apparatus described in Patent Document 1, examples of the porous body used as such a carrier include metal fibers and ceramic fibers.

JP 2006-57892 A

  In the configuration in which the liquid fuel sprayed from the injector is attached to the porous body and held as described above, if the cell density of the porous body is increased and the pores are reduced, the fuel is repelled without being absorbed by the pores. The ratio of falling will increase.

  On the other hand, a gas such as oxygen is introduced into the combustion chamber where the ignition part is arranged. However, if the cell density of the porous body is lowered and the pores are enlarged, the flow rate of the gas is increased and the ignition is performed. The ignitability at the part is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a burner device and an exhaust temperature raising device that can improve fuel retention and ignitability.

  In order to solve the above problems, a burner device according to the present invention is provided in a combustion chamber, a gas supply unit that supplies gas to the combustion chamber, a fuel supply unit that supplies fuel to the combustion chamber, and the combustion chamber. An ignition part for igniting the fuel, a fuel holding part that is arranged in the vicinity of the ignition part and that guides the gas supplied from the gas supply part and holds the fuel supplied from the fuel supply part, The fuel holding portion includes a first layer formed of a porous body and a second layer formed of a porous body having a cell density higher than that of the porous body forming the first layer. The first layer faces the fuel supply unit, and the second layer faces the gas supply unit side.

  The first layer may have a concave surface on the fuel supply unit side.

  An insertion hole may be provided in a stacked portion of the first layer and the second layer, and the ignition portion may be inserted in the insertion hole without being in contact with the first layer and the second layer. .

  In order to solve the above-mentioned problems, an exhaust gas temperature raising device of the present invention has a burner device that is disposed in a front stage of an exhaust gas aftertreatment device that purifies exhaust gas in an exhaust path of a diesel engine and raises the temperature of the exhaust gas. An exhaust gas temperature raising device, wherein the burner device includes a combustion chamber, a gas supply unit that supplies the exhaust gas or a gas different from the exhaust gas to the combustion chamber, and a fuel that supplies fuel to the combustion chamber A supply unit, an ignition unit provided in the combustion chamber, for igniting fuel, and disposed in the vicinity of the ignition unit, the gas supplied from the gas supply unit is guided and supplied from the fuel supply unit A fuel holding portion for holding fuel, wherein the fuel holding portion is formed of a first layer formed of a porous body and a porous body having a cell density higher than that of the porous body forming the first layer. The second layer to be laminated Cage, wherein the first layer faces the said fuel supply unit, the second layer is characterized in that facing the said gas supply unit side.

  The gas supply unit may include an air pump that sends out air.

  According to the present invention, it is possible to improve fuel retention and ignitability.

It is explanatory drawing for demonstrating the exhaust structure of a diesel engine. It is explanatory drawing for demonstrating the structure of an exhaust gas temperature rising apparatus. It is explanatory drawing for demonstrating the structure of an exhaust gas temperature rising apparatus. It is explanatory drawing for demonstrating a fuel holding | maintenance part. It is explanatory drawing for demonstrating a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  In the present embodiment, the exhaust temperature raising device is, for example, an exhaust post-treatment device that purifies exhaust gas in an exhaust path of a diesel engine, specifically, a device that is disposed in front of a diesel oxidation catalyst that oxidizes exhaust gas. Will be described as an example. However, the exhaust temperature raising device is not limited to such an application, but can be applied to various devices having a configuration in which fuel is injected and ignited by an ignition part such as a glow plug.

  FIG. 1 is an explanatory diagram for explaining an exhaust structure of the diesel engine 1. As shown in FIG. 1 (a), a diesel engine 1 compresses air in a cylinder by a piston to increase the temperature and pressure, and uses fuel such as light oil and heavy oil stored in a fuel tank 2 as a fuel pump 3 and an injection pump. This is a reciprocating engine that boosts the pressure at 4 and injects it to cause an explosion and converts the energy generated by the explosion into power. The supercharger 5 is a device that improves the engine output by rotating the turbine with the energy of the exhaust gas of the diesel engine 1 and compressing the intake air to increase the intake pressure.

  The exhaust path 6 is formed by a pipe 7 for exhausting the exhaust gas discharged from the diesel engine 1 to the outside. One end of the pipe 7 is connected to the exhaust port of the diesel engine 1 and the other end is connected to the diesel oxidation catalyst 8. Connected. The particulate filter 9 is composed of a ceramic or metal filter that collects and removes particulate matter such as soot contained in the exhaust gas of the diesel engine 1 through holes of about 10 microns, for example. As shown in the cross-sectional view of FIG. 1B, the filter 9a of the particulate filter 9 causes clogging 11 when the particulate matter 10 is excessively deposited. The clogging 11 causes an increase in exhaust pressure, leading to a deterioration in fuel consumption and a decrease in output.

  The diesel oxidation catalyst 8 is an exhaust aftertreatment device that purifies exhaust gas, and is provided between the diesel engine 1 and the particulate filter 9 and is composed of a catalyst such as platinum or palladium. The exhaust gas is heated by catalytic combustion of unburned fuel using oxygen contained therein. The heated exhaust gas flows to the particulate filter 9 at the subsequent stage, burns the particulate matter 10 deposited on the particulate filter 9 and exhausts it as carbon dioxide, and eliminates clogging of the particulate filter 9 (filter regeneration processing). ).

  Such filter regeneration processing is batch processing that is executed when the particulate filter 9 is clogged, for example, until the clogging is eliminated. However, the diesel oxidation catalyst 8 cannot raise the temperature of the exhaust gas while the temperature of the exhaust gas is low and has not reached the activation temperature at which oxidation is promoted, such as when the diesel engine 1 is started or at a low load. The filter regeneration process cannot be performed in the particulate filter 9. Therefore, in the present embodiment, the exhaust gas in the exhaust path 6 is diverted to suppress the flow velocity, the fuel is burned by the exhaust temperature raising device 100 including the catalyst disposed in the exhaust gas with the reduced flow velocity, and the temperature is increased. The exhaust gas is returned to the exhaust path 6 to assist in raising the temperature of the diesel oxidation catalyst 8.

  In the following embodiment, for example, the exhaust gas temperature raising device 100 used for the purpose of raising the temperature of the exhaust gas in the exhaust path 6 described above will be described in detail.

  2 and 3 are explanatory diagrams for explaining the structure of the exhaust gas temperature raising device 100. FIG. FIG. 2 is a conceptual diagram of a cross section in which the exhaust temperature raising device 100 and a part of the pipe 7 before and after the exhaust temperature raising device 100 are cut by a plane parallel to the exhaust path 6 and including the center of the exhaust temperature raising device 100. 3A shows a cross section taken along line III (a) -III (a) in FIG. 2, and FIG. 3B shows a cross section taken along line III (b) -III (b) in FIG.

  As shown in FIGS. 3A and 3B, the outer wall 110 has, for example, a cylindrical shape and has a bottom surface at the upper end shown in FIG. 2, and the lower end communicates with the exhaust path 6 in the pipe 7. Yes. A first partition member 112 that partitions the inside of the outer wall 110 is disposed inside the outer wall 110. The first partition member 112 is made of, for example, a plate material. The upper end shown in FIG. 2 is fixed to the bottom surface of the cylinder, and the lower end protrudes to the inside of the pipe 7.

  The inflow path 114 is a space located on the upstream side in the flow direction of exhaust gas (Exhaust Gas: indicated as Exh.Gas in the drawing) among the spaces partitioned by the first partition member 112 inside the outer wall 110. For example, about 20% of the flow rate of the exhaust gas flowing through the exhaust path 6 flows into the inflow path 114 from the exhaust path 6.

  Of the space partitioned by the first partition member 112 inside the outer wall 110, the space located on the downstream side in the exhaust gas flow direction is further partitioned by the second partition member 116. The second partition member 116 is made of, for example, a plate material, and the outer peripheral surface is fixed to the outer wall 110 and the first partition member 112, and partitions the space between the upper surface side and the lower surface side of the second partition member 116 shown in FIG. . The space on the upper surface side partitioned by the second partition member 116 is a flame combustion chamber 118 (combustion chamber) for generating a flame (see FIG. 3A), and the space on the lower surface side is for developing combustion. This is the secondary combustion chamber 120 (see FIG. 3B).

  The gas supply unit 122 is constituted by, for example, an air pump or the like, and supplies gas to the flame combustion chamber 118, in the present embodiment, air, and assists the generation of flame in the flame combustion chamber 118. The gas supply unit 122 is not limited to an air pump, and may be configured with a fan, a compressor, or the like.

  The first partition member 112 is provided with a hole 112 a penetrating from the inflow path 114 to the flame combustion chamber 118. The first partition member 112 and the hole 112a limit the flow rates of exhaust gas and air flowing into the flame combustion chamber 118.

  Further, the first partition member 112 is provided with a hole 112 b that penetrates from the inflow passage 114 to the secondary combustion chamber 120. The flow rate of the exhaust gas flowing into the secondary combustion chamber 120 is limited by the first partition member 112 and the hole 112b.

  Further, the second partition member 116 is provided with a hole 116 a penetrating from the flame combustion chamber 118 to the secondary combustion chamber 120. The flow rate of the exhaust gas flowing out from the flame combustion chamber 118 is limited by the second partition member 116 and the hole 116a. In this way, the exhaust gas and air flow rates in the flame combustion chamber 118 and the secondary combustion chamber 120 are suppressed, the ignitability and flame holding performance in the flame combustion chamber 118 are improved, and flame combustion continues in the secondary combustion chamber 120. The possible temperature range and oxygen concentration range can be expanded.

  The flame fuel supply unit 124 (fuel supply unit) is constituted by a fuel injection device such as an injector having a nozzle, for example, and supplies the fuel to the flame combustion chamber 118 in a mist form.

  The ignition unit 126 is composed of an ignition device such as a glow plug, for example, and is heated to a temperature equal to or higher than the fuel ignition temperature to ignite a mixture of fuel, exhaust gas, and air vaporized by the heat of the ignition unit 126.

  The baffle plate 128 is made of, for example, a plate material, and one end is fixed to the bottom surface of the outer wall 110 and the other end side is disposed at a position facing the hole 112a. The baffle plate 128 prevents the exhaust gas and air flowing into the flame combustion chamber 118 through the holes 112 a from directly colliding with the ignition unit 126. With such a configuration, the flow rates of the exhaust gas, air, and air-fuel mixture in the vicinity of the ignition unit 126 can be suppressed, and the ignitability is improved.

  Similar to the flame fuel supply unit 124, the secondary fuel supply unit 130 is configured by a fuel injection device such as an injector, for example, and supplies the fuel into the secondary combustion chamber 120 by spraying in a mist form.

  In the secondary combustion chamber 120, in order to develop the seed fire generated in the flame combustion chamber 118, fuel is further injected by the secondary fuel supply unit 130, and combustion of the air-fuel mixture is promoted while entraining exhaust gas.

  Then, the hot exhaust gas after the temperature rises flows into the exhaust path 6 and raises the temperature of the exhaust gas passing through the exhaust path 6. As described above, the exhaust gas passing through the exhaust path 6 is regarded as “Heated Exh. As indicated by Gas, the temperature is raised by the exhaust temperature raising device 100 and guided downstream.

  By the way, when the flame fuel supply unit 124 sprays fuel directly onto the ignition unit 126, there is a possibility that unburned fuel droplets may drop and the combustion efficiency may decrease. Therefore, the exhaust gas temperature raising device 100 includes a fuel holding unit 134 as a carrier for holding fuel.

  The flame combustion chamber 118, the gas supply unit 122, the flame fuel supply unit 124, the ignition unit 126, and the fuel holding unit 134 described above constitute a burner device 100a that generates a flame.

  The fuel holding unit 134 is disposed in the vicinity of the ignition unit 126, for example, at a position covering one end of the ignition unit 126. The gas is formed of a material and supplied from the gas supply unit 122, and the fuel is temporarily held until the fuel supplied from the flame fuel supply unit 124 is combusted. The fuel holding part 134 may be a catalyst formed as a porous body.

  FIG. 4 is an explanatory diagram for explaining the fuel holding portion 134. 4A is a partially enlarged view of the vicinity of the fuel holding portion 134 in FIG. 2, and FIG. 4B is a sectional view taken along line IV (b) -IV (b) in FIG. 4A. FIG. 4 (c) shows an exploded perspective view of the fuel holding part 134.

  As shown in FIGS. 4A and 4B, the fuel holding portion 134 includes a first layer 134a and a second layer 134b which are stacked and inserted into a housing (not shown), for example. The first layer 134a is formed of a porous body having pores approximately larger than the particle size of the fuel sprayed from the flame fuel supply unit 124. The second layer 134b is formed of a porous body having a cell density higher than that of the porous body forming the first layer 134a. Here, the cell density refers to the number of cells (holes) per unit volume, for example.

  Further, the casing is formed of a net-like member such as a metal net, for example, and does not prevent the exhaust gas, air, and fuel from flowing into and out of the fuel holding portion 134.

  The first layer 134a is disposed to face the flame fuel supply unit 124, and the second layer 134b is disposed to face the gas supply unit 122 side.

  The fuel holding unit 134 of the present embodiment receives the fuel injected from the flame fuel supply unit 124 with the first layer 134a having a low cell density. Since the first layer 134a has large holes, it is difficult to play the fuel. In addition, a second layer 134b having a high cell density is stacked on the first layer 134a. When the fuel reaches the second layer 134b, it is held by the second layer 134b where the pores are fine and the surface tension is increased, so that the amount of fuel falling from the first layer 134a can be suppressed.

  In addition, since the second layer 134b faces the gas supply unit 122, the flow rate of the gas flowing from the gas supply unit 122 to the ignition unit 126 decreases when passing through the porous body having a high cell density. . Therefore, the flow velocity in the vicinity of the ignition part 126 is suppressed, and the ignitability in the ignition part 126 is improved.

  As shown in FIG. 4C, the surface of the first layer 134a on the flame fuel supply unit 124 side is recessed (having a recess 134c). With such a configuration, even if a part of the fuel injected from the flame fuel supply unit 124 is bounced, the possibility that it will adhere again to the other part of the dent after being bounced increases. Therefore, the fuel holding part 134 improves the fuel holding property.

  Further, an insertion hole 134d is provided in the laminated portion of the first layer 134a and the second layer 134b, and the ignition part 126 is inserted in the insertion hole 134d in a non-contact manner with the first layer 134a and the second layer 134b. Yes.

  The porous body is generally difficult to process such as cutting. However, for example, as shown in FIG. 4 (c), if the insertion hole 134d is provided in half in each of the first layer 134a and the second layer 134b, for example, it is simply deformed by pressing a jig or the like. Thus, it is possible to provide the insertion hole 134d. In addition, the configuration in which the ignition unit 126 is not in contact with the first layer 134a and the second layer 134b allows heat dissipation due to heat transfer from the ignition unit 126 to the first layer 134a and the second layer 134b. Since it becomes difficult, it becomes possible to raise the temperature of the ignition part 126 efficiently.

  Even if the exhaust gas temperature raising device 100 is an exhaust gas having a low oxygen concentration, since the burner device 100a has high ignitability, the temperature of the exhaust gas can be raised stably. Further, since the exhaust temperature raising device 100 has a high fuel holding property of the fuel holding unit 134, it is unlikely that unburned fuel will flow into the exhaust gas unintentionally. For example, the diesel engine 1 is mounted. It is easy to adapt to strict environmental regulations such as automobile exhaust gas regulations.

  Further, as described above, the gas supply unit 122 is constituted by, for example, an air pump that sends out air. With such a configuration, even if the flow rate of the air sent from the gas supply unit 122 is high, the second layer 134b can reduce the flow rate. Therefore, the exhaust gas temperature raising device 100 supplies sufficient oxygen to the gas supply unit 122. By supplying the fuel, the ignitability and flame holding properties are improved, and the temperature of the exhaust gas can be raised stably.

(Modification)
In the above-described embodiment, the configuration of the exhaust gas temperature raising device 100 in which flame combustion is performed in the secondary combustion chamber 120 has been described. In the modified example, an exhaust gas temperature raising device 200 that can maintain combustion in the secondary combustion chamber 120 more stably will be described. In addition, about the structure which is substantially the same function as embodiment mentioned above, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIG. 5 is an explanatory diagram for explaining a modified example, and shows a cross-section at a position corresponding to the conceptual diagram of FIG.

  As shown in FIG. 5, in the exhaust gas temperature raising device 200 of the modified example, in addition to the configuration of the exhaust gas temperature raising device 100, a burner catalyst 232 is arranged in the secondary combustion chamber 120.

  The burner catalyst 232 is formed of a base material and a coating material of a catalyst such as platinum or palladium that covers the base material, and promotes combustion of an air / fuel mixture in the secondary combustion chamber 120. Here, the burner catalyst 232 is doubled to promote catalytic combustion, but it may be single or triple or more.

  When ignition is successful in the ignition unit 126, the exhaust gas that has flowed from the flame combustion chamber 118 through the hole 116 a into the catalytic combustion chamber 120 heats the burner catalyst 232. The flame generated in the flame combustion chamber 118 also heats the burner catalyst 232 through the holes 116a.

  The burner catalyst 232 is heated to an activation temperature or higher, and catalytically burns an air-fuel mixture in which the fuel supplied from the secondary fuel supply unit 130 and the exhaust gas flowing in from the holes 112b and 116a are mixed. The high-temperature exhaust gas after combustion flows into the exhaust path 6 and increases the temperature of the exhaust gas passing through the exhaust path 6.

  As described above, the exhaust temperature raising device 200 can stably maintain the combustion of fuel in the secondary combustion chamber 120 by the configuration including the burner catalyst 232 in the secondary combustion chamber 120.

  In the above-described embodiment, the burner device 100a is used for raising the temperature of the exhaust gas for activating the diesel oxidation catalyst 8. However, the present invention is not limited to this, and the burner device 100a supplies gas to the combustion chamber. It can be applied to various devices that ignite by supplying fuel to an ignition part such as a glow plug.

  In the above-described embodiment, the case where both the air supplied by the gas supply unit 122 and the exhaust gas are guided to the flame combustion chamber 118 has been described. However, the gas supplied to the flame combustion chamber 118 includes air and exhaust gas. Either one is acceptable. In particular, when only the exhaust gas is supplied to the flame combustion chamber 118, the hole 112 a functions as a gas supply unit, and exhaust gas that is a gas is supplied to the flame combustion chamber 118.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  INDUSTRIAL APPLICABILITY The present invention can be used for a burner device for burning fuel and an exhaust temperature raising device.

DESCRIPTION OF SYMBOLS 100 ... Exhaust temperature raising apparatus 100a ... Burner apparatus 118 ... Flame combustion chamber (combustion chamber)
122 ... Gas supply part 124 ... Flame fuel supply part (fuel supply part)
126 ... ignition part 128 ... temperature measurement part 134 ... fuel holding part 134a ... first layer 134b ... second layer 134d ... insertion hole 1 ... diesel engine 6 ... exhaust path 8 ... diesel oxidation catalyst

Claims (5)

A combustion chamber;
A gas supply unit for supplying gas to the combustion chamber;
A fuel supply section for supplying fuel to the combustion chamber;
An ignition part provided in the combustion chamber for igniting fuel;
A fuel holding unit that is disposed in the vicinity of the ignition unit, guides the gas supplied from the gas supply unit, and holds the fuel supplied from the fuel supply unit;
The fuel holding part is
A first layer formed of a porous body and a second layer formed of a porous body having a cell density higher than that of the porous body forming the first layer;
The first layer faces the fuel supply unit,
The burner apparatus characterized by the said 2nd layer facing the said gas supply part side.   The burner device according to claim 1, wherein the first layer has a concave surface on the fuel supply unit side. An insertion hole is provided in the laminated portion of the first layer and the second layer,
3. The burner device according to claim 1, wherein the ignition portion is inserted into the insertion hole without contacting the first layer and the second layer. 4. In an exhaust path of a diesel engine, an exhaust temperature raising device that is disposed in a front stage of an exhaust aftertreatment device that purifies exhaust gas and has a burner device that raises the temperature of the exhaust gas,
The burner device
A combustion chamber;
A gas supply unit for supplying the exhaust gas or a gas different from the exhaust gas to the combustion chamber;
A fuel supply section for supplying fuel to the combustion chamber;
An ignition part provided in the combustion chamber for igniting fuel;
A fuel holding unit that is disposed in the vicinity of the ignition unit, guides the gas supplied from the gas supply unit, and holds the fuel supplied from the fuel supply unit;
The fuel holding part is
A first layer formed of a porous body and a second layer formed of a porous body having a cell density higher than that of the porous body forming the first layer are laminated, and the first layer includes: The exhaust gas temperature raising device facing the fuel supply unit, wherein the second layer faces the gas supply unit side.   The exhaust gas temperature raising device according to claim 4, wherein the gas supply unit includes an air pump that sends out air.