WO2015075793A1

WO2015075793A1 - Exhaust purification device and regeneration method therefor

Info

Publication number: WO2015075793A1
Application number: PCT/JP2013/081317
Authority: WO
Inventors: 茂樹大林
Original assignee: ボルボラストバグナーアクチエボラグ; 茂樹大林
Priority date: 2013-11-20
Filing date: 2013-11-20
Publication date: 2015-05-28

Abstract

An exhaust purification device wherein a DOC converter, which is housed in a casing capable of being attached in a detachable manner via a flange, and a DPF that removes particulate matter (PM) in the exhaust, are arranged in this order in an exhaust pipe of a diesel engine. When a regeneration process for the DOC converter is to be executed, the casing is detached from the exhaust pipe of the diesel engine, after which the casing is attached to the exhaust pipe of the diesel engine with the exhaust inflow side and the exhaust outflow side of the DOC converter reversed. Thus, the oxidation heat of the DOC converter is used to execute the regeneration process for the DOC converter.

Description

Exhaust gas purification device and regeneration method thereof

The present invention relates to an exhaust gas purification device for removing particulate matter (Particulate Matter, hereinafter referred to as “PM”) in exhaust gas and a method for regenerating the exhaust gas purification device.

As an exhaust gas purification device that removes PM in exhaust gas, as described in JP 2010-116913 A (Patent Document 1), a diesel oxidation catalyst (hereinafter referred to as “DOC”) is provided from upstream to downstream of the exhaust pipe. It is known that a converter and a diesel particulate filter (Diesel Particulate Filer, hereinafter referred to as “DPF”) are disposed. In this exhaust purification apparatus, the DOC converter oxidizes nitrogen monoxide (NO) in the exhaust to nitrogen dioxide (NO ₂ ) having excellent oxidation ability, and the DPF oxidizes (incinerates) PM using NO ₂ . Thus, the DPF is continuously regenerated. In addition, when the PM accumulated in the DPF exceeds an allowable value, the DOC converter oxidizes the fuel and raises the temperature of the exhaust gas so that the PM accumulated in the DPF is oxidized. Perform forced regeneration processing.

JP 2010-116913 A

By the way, the exhaust inflow side of the DOC converter is exposed to the PM in the exhaust and is also exposed to the fuel during the forced regeneration process of the DPF. For this reason, clogging due to PM or fuel can occur on the exhaust inflow side of the DOC converter where the temperature rise due to the oxidation reaction is small. When such clogging occurs, the oxidation performance of NO or fuel in the DOC converter is reduced, so that the DPF regeneration process may be insufficient. In order to regenerate the DOC converter, a method of periodically increasing the temperature of exhaust gas to eliminate clogging can be considered, but since fuel is consumed in excess, fuel consumption is reduced.

Therefore, an object of the present invention is to provide an exhaust purification device and a regeneration method thereof that can perform regeneration processing of a DOC converter without causing a reduction in fuel consumption.

In one aspect of the present embodiment, the exhaust purification device includes a DOC converter housed in a casing that is detachably attached to an exhaust pipe of a diesel engine via a flange, and a DPF that removes PM in the exhaust. Arranged in order. When the regeneration process of the DOC converter is executed, the casing is removed from the exhaust pipe of the diesel engine, and the casing is attached to the exhaust pipe of the diesel engine with the exhaust inflow side and the exhaust outflow side of the DOC converter reversed. And the regeneration process of a DOC converter is performed using the oxidation heat of a DOC converter.

In another aspect of the present embodiment, the exhaust emission control device has a casing that can be attached to and detached from the exhaust pipe of the diesel engine and can be switched between the exhaust inflow side and the exhaust outflow side. The exhaust emission control device further includes a DOC converter housed in the casing, and a DPF disposed in an exhaust pipe located downstream of the exhaust.

According to the present invention, the regeneration processing of the DOC converter can be executed without causing a reduction in fuel consumption.

It is a schematic diagram showing an example of an engine system provided with an exhaust purification device. It is a top view which shows the detail of an exhaust gas purification apparatus. It is a perspective view which shows the detail of an exhaust gas purification apparatus. It is internal explanatory drawing which shows the detail of an exhaust gas purification apparatus. It is explanatory drawing of the structure which makes a DOC converter removable. It is explanatory drawing of the method of performing the reproduction | regeneration processing of a DOC converter. It is explanatory drawing of the other structure which makes a DOC converter removable. It is explanatory drawing of the other method of performing the reproduction | regeneration processing of a DOC converter.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of an engine system including an exhaust purification device.

An intake pipe 120 connected to the intake manifold 110 of the diesel engine 100 includes an air cleaner 130 that filters dust and the like in the intake air along a direction of intake air flow, a compressor 142 of the turbocharger 140 that supercharges intake air, and a compressor 142. An intercooler 150 that cools the intake air that has passed and an intake collector 160 that smoothes the intake pulsation are arranged in this order.

On the other hand, the exhaust pipe 180 connected to the exhaust manifold 170 of the diesel engine 100 is injected with a turbine 144 of the turbocharger 140, a continuously regenerating DPF device 190, and a urea aqueous solution as a reducing agent precursor along the exhaust flow direction. An injection nozzle 200 to be supplied, an SCR (Selective Catalytic Reduction) converter 210 for selectively reducing and purifying NOx upon receiving supply of ammonia generated from the urea aqueous solution, and an oxidation catalytic converter 220 for oxidizing the ammonia that has passed through the SCR converter 210 are in this order. Arranged. The continuous regeneration type DPF device 190 includes a DOC converter 192 that oxidizes NO and fuel, and a DPF 194 that removes PM. Instead of DPF 194, CSF (Catalyzed Soot Filter) having a catalyst (active component and additive component) supported on its surface can be used.

The aqueous urea solution stored in the reducing agent tank 230 is supplied to the injection nozzle 200 via a reducing agent addition unit 240 having a built-in pump and flow control valve. Here, the reducing agent addition unit 240 may be divided into a pump module with a built-in pump and a dosing module with a built-in flow control valve.

Also, a fuel addition nozzle 250 for adding fuel to the exhaust upstream of the DOC converter 192 is attached to the exhaust pipe 180 positioned upstream of the exhaust of the continuous regeneration type DPF device 190 when the DPF 194 is forcibly regenerated. The fuel addition nozzle 250 is supplied with fuel that has been regulated to a predetermined pressure by a supply pump (not shown). A flow rate control valve 270 that controls the flow rate of fuel added from the fuel addition nozzle 250 is disposed in the fuel pipe 260 that supplies fuel to the fuel addition nozzle 250. As the flow control valve 270, for example, an open / close valve that simply opens and closes the fuel pipe 260, a control valve that makes the fuel passage cross-sectional area of the fuel pipe 260 variable, or the like can be used.

A temperature sensor 280 for measuring the exhaust gas temperature (exhaust gas temperature) is attached to the exhaust pipe 180 located between the continuous regeneration type DPF device 190 and the injection nozzle 200 in order to grasp the active state of the SCR converter 210. The output signal of the temperature sensor 280 is input to a reducing agent addition control unit (DCU: Dosing Control Unit) 290 incorporating a computer. In addition, the DCU 290 electronically controls the diesel engine 100 via an in-vehicle network such as CAN (Controller Area Network) so that the rotation speed and load as an example of the engine operating state can be read at an arbitrary time. A unit (ECU: Engine Control Unit) 300 is communicably connected.

The DCU 290 executes a control program stored in a non-volatile memory such as a flash ROM (Read Only Memory), so that the reducing agent addition unit 240 and the flow control valve 270 are based on the exhaust temperature, the rotation speed, and the load. Each is electronically controlled.

Here, as the load of the diesel engine 100, for example, a state quantity closely related to the engine torque, such as a fuel injection amount, an intake air flow rate, an intake pressure, a supercharging pressure, and an accelerator opening degree can be used. Further, the rotational speed and load of the diesel engine 100 may be directly detected using a known sensor instead of reading from the ECU 300.

In such an exhaust purification device, exhaust from the diesel engine 100 is introduced into the DOC converter 192 of the continuous regeneration type DPF device 190 through the exhaust manifold 170 and the turbine 144 of the turbocharger 140. The exhaust gas introduced into the DOC converter 192 flows to the DPF 194 while NO is oxidized to NO ₂ . In the DPF 194, PM in the exhaust gas is removed, and PM is continuously oxidized (incinerated) using NO ₂ generated by the DOC converter 192.

Further, the urea aqueous solution supplied (added) from the injection nozzle 200 according to the engine operating state is hydrolyzed using exhaust heat and water vapor in the exhaust, and converted into ammonia that functions as a reducing agent. It is known that this ammonia is selectively reduced with NOx in the exhaust gas in the SCR converter 210 and purified to harmless H ₂ O (water) and N ₂ (nitrogen). At this time, NO is oxidized to NO ₂ by the DOC converter 192, and the ratio of NO to NO ₂ in the exhaust gas is improved to be suitable for the selective reduction reaction, so that the NOx purification rate in the SCR converter 210 is improved. be able to. On the other hand, the ammonia that has passed through the SCR converter 210 is oxidized by the oxidation catalyst converter 220 disposed downstream of the exhaust gas, so that it is possible to suppress the ammonia from being released into the atmosphere as it is.

When clogging occurs in the DPF 194 of the continuous regeneration type DPF device 190, fuel is added from the fuel addition nozzle 250 to the exhaust upstream of the DOC 192. Here, whether or not clogging has occurred in the DPF 194 can be determined based on, for example, whether or not the differential pressure between the exhaust upstream of the DPF 194 and the exhaust downstream has become a predetermined value or more. Then, the fuel added from the fuel addition nozzle 250 is oxidized in the DOC converter 192 to raise the exhaust gas temperature. When exhaust gas whose exhaust temperature has risen is introduced into the DPF 194, the PM accumulated in the DPF 194 is oxidized, so that forced regeneration processing is performed.

Next, the details of the exhaust emission control device will be described with reference to FIGS.
The exhaust emission control device communicates the first casing 400 having a cylindrical shape, the second casing 420 having the same cylindrical shape, and the distal ends of the first casing 400 and the second casing 420 with each other. And a communication pipe 440 to be made. The first casing 400 and the second casing 420 are arranged in close proximity to each other so that the axis 400A and the axis 420A are substantially parallel (they may be just parallel in appearance, and so on). . The communication pipe 440 is also piped such that its axis 440A is substantially parallel to the axis 400A of the first casing 400 and the axis 420A of the second casing 420. Here, the first casing 400, the second casing 420, and the communication pipe 440 correspond to a part of the exhaust pipe 180 of the diesel engine 100.

In the first casing 400, an inlet 402 is formed at the exhaust upstream end, and an outlet 404 is formed at the exhaust downstream end. In the case of the present embodiment, the inlet 402 is formed on the end surface of the exhaust upstream end, and the outlet 404 is formed on the side surface of the exhaust downstream end. The DOC converter 192 and the DPF 194 are accommodated in the first casing 400 positioned between the inlet 402 and the outlet 404, respectively.

In the second casing 420, an inlet 422 is formed at the exhaust upstream end, and an outlet 424 is formed at the exhaust downstream end. In the case of this embodiment, both the inflow port 422 and the discharge port 424 are respectively formed on the side surfaces of the end portions. The SCR converter 210 and the oxidation catalyst converter 220 are accommodated in the second casing 420 located between the inlet 422 and the outlet 424, respectively.

The communication pipe 440 is the exhaust downstream downstream end of the first casing 400, which is the far ends of the first casing 400 and the second casing 420, in other words, the far ends positioned on opposite sides of each other. And the inflow port 422 at the exhaust upstream end of the second housing 420 are in communication with each other. Therefore, the exhaust from the diesel engine 100 flows into the first housing 400 from the inlet 402, passes through the DOC converter 192 and the DPF 194, and enters the communication pipe 440 from the outlet 404. Then, the exhaust gas that has entered the communication pipe 440 flows into the second casing 420 from the inlet 422 through the communication pipe 440, passes through the SCR converter 210 and the oxidation catalyst converter 220, and is discharged from the outlet 424. The That is, the exhaust passage from the first housing 400 to the second housing 420 via the communication pipe 440 is folded once by the communication pipe 440.

The communication pipe 440 is a straight straight pipe having bent portions formed at both ends for connection between the discharge port 404 of the first housing 400 and the inlet 422 of the second housing 420. Then, the injection nozzle 200 is attached to a bent portion with respect to the discharge port 404, and the urea aqueous solution is injected and supplied from the injection nozzle 200 into the linear pipe. Thereby, the linear length required for the uniform diffusion of the urea aqueous solution into the exhaust gas is secured. In order to promote uniform diffusion of the urea aqueous solution, for example, a mesh-like diffusion member can be installed in the communication pipe 440.

According to such an exhaust purification device, the first casing 400 and the second casing 420 are arranged close to each other in parallel, so that the silhouette has a compact size similar to a square muffler. Further, since the far ends of the first casing 400 and the second casing 420 are communicated with each other by the communication pipe 440, the first casing 400 and the first casing 400 and the second casing 420 are secured while ensuring the tube length necessary for the uniform diffusion of the urea aqueous solution. The communication pipe 440 can be accommodated in the silhouette of the second housing 420. For this reason, it has succeeded in reducing the size of the length direction from exhaust upstream to downstream.

In addition, as shown in FIG. 5, the first casing 400 houses a first casing 406 having an inlet 402 formed on an end surface, a second casing 408 that houses a DOC converter 192, and a DPF 194. The third casing 410 can be divided into three parts. The first casing 406 has a substantially bottomed cylindrical shape, and a substantially annular flange 406A is formed at the open end. The second casing 408 has a substantially cylindrical shape, and substantially annular flanges 408A are formed at both ends in the axial direction. The third casing 410 has a substantially bottomed cylindrical shape. A substantially annular flange 410A is formed at the opening end of the third casing 410, and a discharge port 404 is formed on the side surface of the end located on the opposite side of the flange 410A. The Here, the 2nd casing 408 is mentioned as an example of the casing removably attached to an exhaust pipe via a flange.

The DOC converter 192 includes a substantially cylindrical carrier 192A having a diameter slightly smaller than the inner diameter of the second casing 408, and a substantially annular flange 192B formed at one end of the carrier 192A in the axial direction. That is, the DOC converter 192 is formed into a cartridge so as to be detachably inserted into the second casing 408. The carrier 192A carries a catalyst (active component and additive component) that exhibits an oxidation function.

The flange 406A of the first casing 406, the pair of flanges 408A of the second casing 408, the flange 410A of the third casing 410, and the flange 192B of the DOC converter 192 include a bolt shaft portion of the fastener 500 including bolts and nuts. A plurality of insertion holes through which are inserted. Accordingly, as shown in FIG. 5, the DOC converter 192 is accommodated in the second casing 408, and the flanges 408A at both ends thereof are brought into contact with the flange 406A of the first casing 406 and the flange 410A of the third casing 410. The first housing 400 can be assembled by contacting the bolt shaft portion through the insertion hole and screwing the nut.

In this state, the DOC converter 192 is fixed to the first casing 400 by the flange 192B being sandwiched between the flange 406A of the first casing 406 and one flange 408A of the second casing 408. Yes. At this time, since the flange 192B of the DOC converter 192 is fastened together by the fastener 500 that fastens the flange 406A of the first casing 406 and the flange 408A of the second casing 408, the fastening operation is facilitated. Can do. In addition, in order to improve airtightness in the joint surface of each flange, for example, a gasket 510 having a substantially annular shape may be sandwiched.

In the exhaust purification device, the exhaust inflow side of the carrier 192A of the DOC converter 192 is exposed to the PM in the exhaust and to the fuel during the forced regeneration process of the DPF 194. For this reason, when the exhaust purification device is used for a long time, PM or fuel accumulates on the exhaust inflow side of the DOC converter 192, and clogging may occur when this exceeds the allowable value.

Therefore, for example, the reproduction process of the DOC converter 192 can be executed by performing the following work every time a predetermined period elapses.
That is, an operator such as a service factory removes the fastener 500 from the first casing 400, and makes the first casing 406, the second casing 408, the third casing 410, and the DOC converter 192 separable. Then, the operator removes the second casing 408 in which the DOC converter 192 is accommodated from the first casing 400, and reverses the exhaust inflow side and the exhaust outflow side of the DOC converter 192 as shown in FIG. In this state, the first housing 400 is assembled by the fastener 500.

Here, when the exhaust inflow side and the exhaust outflow side of the DOC converter 192 are reversed, the insertion direction of the DOC converter 192 with respect to the second casing 408 is changed, or the second casing 408 in which the DOC converter 192 is accommodated. There are two ways to turn it over.

In this way, in the DOC converter 192, the portion where PM or fuel is deposited comes to be located on the exhaust gas outlet side. When exhaust gas flows into the DOC converter 192 and NO is oxidized to NO ₂ and the temperature of the exhaust gas rises, the portion where PM or fuel is deposited is exposed to high-temperature exhaust gas. For this reason, since PM or fuel deposited on the DOC converter 192 is incinerated and removed using oxidation heat, the regeneration process of the DOC converter 192 can be executed. The same applies when the DOC converter 192 oxidizes fuel during forced regeneration of the DPF 194.

As shown in FIG. 7, the DOC converter 192 may be integrated with the second casing 408, for example, may be fixed to the second casing 408 via a holder 520. In this case, when the regeneration process of the DOC converter 192 is executed, the upstream side and the downstream side of the second casing 408 may be turned over as shown in FIG. In addition, since the effect | action and effect by this structure are the same as the previous thing, the description is abbreviate | omitted. Please refer to the previous explanation if necessary.

In the exhaust purification apparatus described above, the continuous regeneration type DPF device 190, the SCR converter 210, and the oxidation catalyst converter 220 are disposed in the exhaust pipe 180, but at least the continuous regeneration type DPF device 190 is disposed in the exhaust pipe 180. It only has to be. In this exhaust purification apparatus, the first casing 400 and the second casing 420 are arranged in parallel, but the first casing 400 and the second casing 420 are arranged in series. It may be.

100 Diesel engine 180 Exhaust pipe 190 Continuous regeneration type DPF device 192 DOC converter 192A Carrier 192B Flange 194 DPF
210 SCR Converter 220 Oxidation Catalytic Converter 400 First Housing 406 First Casing 406A Flange 408 Second Casing 408A Flange 410 Third Casing 410A Flange 500 Fastener 510 Gasket 520 Holder

Claims

A diesel oxidation catalytic converter housed in a casing that is detachably attached to the exhaust pipe of a diesel engine via a flange, and a diesel particulate filter that removes particulate matter in the exhaust gas are arranged in this order. In the exhaust purification device,
Removing the casing from the exhaust pipe of the diesel engine;
With the exhaust inflow side and the exhaust outflow side of the diesel oxidation catalytic converter reversed, the casing is attached to the exhaust pipe of the diesel engine,
Utilizing the oxidation heat of the diesel oxidation catalyst, the regeneration process of the diesel oxidation catalyst is executed,
A method for regenerating an exhaust emission control device.
The diesel oxidation catalytic converter has a carrier detachable from the casing, and a flange formed at one end of the carrier in the axial direction.
The method for regenerating an exhaust emission control device according to claim 1.
The flange of the diesel oxidation catalytic converter was sandwiched between the flange of the exhaust pipe and the flange of the casing.
The method for regenerating an exhaust emission control device according to claim 2.
The flange of the diesel oxidation catalytic converter was fastened together with a fastener for fastening the flange of the exhaust pipe and the flange of the casing.
The method for regenerating an exhaust emission control device according to claim 3.
A gasket is sandwiched between each joint surface of the flange of the exhaust pipe, the flange of the casing, and the flange of the diesel oxidation catalyst.
The method for regenerating an exhaust emission control device according to any one of claims 1 to 4, characterized in that:
The exhaust pipe located downstream of the exhaust gas from the diesel particulate filter is provided with a selective catalytic reduction converter that receives a reducing agent and selectively reduces and purifies nitrogen oxides in the exhaust gas.
The method for regenerating an exhaust emission control device according to any one of claims 1 to 5, wherein:
An oxidation catalytic converter that oxidizes the reducing agent that has passed through the selective reduction catalytic converter is disposed in the exhaust pipe located downstream of the exhaust of the selective reduction catalytic converter.
The method for regenerating an exhaust purification device according to claim 6.
The diesel oxidation catalytic converter is fixed to the casing via a holder.
The method for regenerating an exhaust emission control device according to claim 1.
A gasket was sandwiched between each joint surface of the flange of the exhaust pipe and the flange of the casing,
A method for regenerating an exhaust emission control device according to claim 6.
The exhaust pipe located downstream of the exhaust gas from the diesel particulate filter is provided with a selective catalytic reduction converter that receives a reducing agent and selectively reduces and purifies nitrogen oxides in the exhaust gas.
The method for regenerating an exhaust emission control device according to claim 8 or 9, wherein
An oxidation catalytic converter that oxidizes the reducing agent that has passed through the selective reduction catalytic converter is disposed in the exhaust pipe located downstream of the exhaust of the selective reduction catalytic converter.
The method for regenerating an exhaust emission control device according to claim 10.
A casing that is detachably attached to the exhaust pipe of the diesel engine and that can be exchanged between the exhaust inflow side and the exhaust outflow side;
A diesel oxidation catalyst housed in the casing;
A diesel particulate filter disposed in an exhaust pipe located downstream of the exhaust of the diesel oxidation catalyst;
An exhaust emission control device comprising: