JP2662911B2 - Exhaust gas purification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for reducing NOx emitted from a diesel vehicle, and more particularly to an exhaust gas purifying apparatus using a catalyst and a reducing agent.

[0002]

2. Description of the Related Art Exhaust gas purifying devices have been developed to reduce NOx emitted from diesel vehicles with a catalyst and a reducing agent. However, in a current catalyst, the conversion rate of NOx is high unless the concentration of the reducing agent is high. Because of this, a large amount of reducing agent had to be supplied. As a result, unreacted reducing agent,
That is, there was a problem that a large amount of hydrocarbons was discharged.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an exhaust gas purifying apparatus which suppresses discharge of unreacted reducing agent and reduces NOx discharged from a diesel engine at a high NOx conversion rate.

[0004]

Means corresponding to the object and the operation thereof
A reduction device having a reduction catalyst and disposed in the exhaust pipe of a diesel engine, a reducing agent supply device disposed in the exhaust pipe on the upstream side of the reduction device, and an adsorption zone and a regeneration zone inside. And a rotor filled with activated carbon in a gas-permeable state and rotated in the casing between the adsorption zone and the regeneration zone, and the exhaust pipe is provided in the exhaust pipe on the downstream side of the reduction device. An adsorption device for connecting the adsorption zones, an exhaust gas passage and an air passage which are separated from each other by a partition to exchange heat, the exhaust gas passage is provided in the exhaust pipe between the reduction device and the adsorption device, and the regeneration of the adsorption device A heat exchanger for connecting the outlet side of the air passage to the inlet side of the zone, and an air supply connected to the inlet side of the air passage for the heat exchanger And a recovery pipe at the outlet side of the regeneration zone of the adsorption device, which communicates with the inlet side of the reduction device, and supplies NOx contained in the exhaust gas of the diesel engine to the catalyst while supplying a reducing agent to the exhaust gas. And the exhaust gas containing the unreacted reducing agent is cooled with air.
In the adsorption zone, the unreacted reducing agent is adsorbed on the activated carbon, and in the regeneration zone, the unreacted reducing agent is desorbed and recovered from the activated carbon by the hot air used for cooling, and The recovered unreacted reducing agent is being returned to the catalyst.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the exhaust gas purifying apparatus of the present invention will be described below with reference to the drawings. FIGS. 1, 2, and 3 show a specific example 10 of the exhaust gas purifying apparatus of the present invention applied to a diesel vehicle.
The exhaust gas purifying apparatus 10 is applied to an exhaust system of a diesel engine 70 mounted on the diesel vehicle,
The reduction device 11, the reducing agent supply device 12, the adsorption device 13, the heat exchanger 14, the air supply device 15, the recovery pipe 16, the branch exhaust pipe 17, the exhaust gas switching device 18, and the rotation speed and load of the diesel engine 70. And the reducing agent supply device 12, the adsorption device 13,
The air supply device 15 and the computer 19 controlling the exhaust gas switching device 18 were assembled.

The reducing device 11 comprises a casing 20 having an inlet and an outlet with a flange, and a reducing catalyst 21 incorporated in the casing 20. The outlet and the outlet are flanged and arranged in the exhaust pipe 72. The reduction catalyst 21 also includes a carrier formed from a ceramic powder and manufactured in a honeycomb structure including a large number of cells with both ends opened through a drying and firing process. Of course, the catalyst supported on the carrier includes ,
Zeolite-based (Cu-ZsH5, Cu-mortenite,
Others) were used.

The reducing agent supply device 12 uses the fuel of the diesel vehicle because the exhaust gas purifying device 10 uses light oil as the reducing agent. That is, the reducing agent supply device 12 has an inlet and an outlet with a flange, and has an exhaust pipe 72 upstream of the reducing device 11.
The inlet and outlet of the chamber casing 22 are arranged in the exhaust pipe 72 by flanging the inlet and outlet.
An injection nozzle 23 disposed in the chamber casing 22, a fuel tank 73 connected to the injection nozzle 23 by a pipe 30, and an air tank 24 connected to the injection nozzle 23 by another pipe 31. And an electric reducing agent pump 25 and a flow control valve 26 disposed in the pipe 30.
And flow control valves 27 arranged in other pipes 31. The flow control valves 26, 27 are opened and closed by electric motors 28, 29, and electric valves whose opening degree is changed are used. Was.

In the reducing agent supply device 12, the flow control valves 26 and 27 are opened and closed according to the rotation speed and load of the diesel engine 70 and the temperature of the exhaust gas, and the valve opening is operated. And light oil is supplied to the exhaust gas in the form of a mist in the chamber casing 22,
The flow rates of the light oil and air are adjusted.

As shown in FIG. 2, the suction device 13 is divided into a suction zone 34 and a regeneration zone 35 by a partition wall 33, and a suction inlet with a flange connected to the suction zone 34. 36 and exit 3
7, a casing 32 having a flanged regeneration side inlet 38 and an outlet 39 connected to the regeneration zone 35 thereof, and a drum-shaped frame 41 provided with countless paper-like activated carbons 4.
And a rotor 40 supported on the casing 32 by a rotating shaft 42 when the casing 3 is rotated between the adsorption zone 34 and the regeneration zone 35 in the casing 32, and a motor shaft 45 is assembled with an electric motor 44 gear-coupled, and
On the downstream side of the heat exchanger 14, the adsorption-side inlet 36 and the outlet 37 are flange-connected in the middle of the exhaust pipe 72, and the adsorption zone 34 is connected to the exhaust pipe 72.

In the adsorption device 13, the diesel
The rotor 40 is rotated and stopped by the electric motor 44 in accordance with the rotation speed and load of the engine 70 and the temperature of the exhaust gas, and light oil is injected as a reducing agent in the chamber casing 22 to be decomposed. Then, NOx is reduced on the reduction catalyst 21 of the reduction device 11, and at that time, since unreacted hydrocarbons are contained in the exhaust gas passing through the reduction device 11, the rotation speed is adjusted according to the supply amount of the light oil. The so-called adjustment of the ability to adsorb the unreacted hydrocarbon (unreacted reducing agent) is performed.

The heat exchanger 14 is a plate-type heat exchanger using a large number of thin flat plates 47 for partition walls. As shown in FIG. 3, the heat exchanger 14 is disposed at a predetermined interval in the casing 46. A large number of exhaust gas passages 48 and air passages 49 are formed in the casing 46 and are separated from each other by the large number of flat plates 47 to exchange heat. .
In the heat exchanger 14, a flanged exhaust gas inlet 50 and outlet 51 connected to the exhaust gas passage 48 and a flanged air inlet 52 and outlet 53 connected to the air passage 49 are formed in the casing 46. The exhaust gas inlet 50 and the exhaust gas outlet 50 are flange-connected midway along the exhaust pipe 72 between the reduction device 11 and the adsorption device 13, and the exhaust gas passage 48 is connected to the exhaust pipe 72.
On the other hand, while the regeneration side entrance 38 of the adsorption device 13
Is connected to the air outlet 53 by a heated air supply pipe 54,
When the air flows through the air passage 49, the air is heated by the exhaust gas flowing through the exhaust gas passage 48, and the heated air can be supplied to the regeneration zone 35 of the adsorption device 13.

The air supply device 15 shares the air tank 24 of the reducing agent supply device 12, is branched from the pipe 31 of the reducing agent supply device 12, and is flanged to the air inlet 52 of the heat exchanger 14. And an air flow control valve 56 disposed in the pipe 55, and an electric valve which is opened and closed by the air flow control valve 56 and the electric motor 57 and whose valve opening is changed is used. .

In the air supply device 15, the air flow regulating valve 56 is opened and closed according to the rotation speed and load of the diesel engine 70 and the temperature of the exhaust gas.
Then, the valve opening is operated to supply air to the heat exchanger 14, and the flow rate of the air is adjusted.

One end of the recovery pipe 16 is connected to the suction device 1.
3 is flanged to the regeneration side outlet 39, and the other end of the reduction device 11 is protruded into the inlet of the casing 20 and connected to the inlet of the casing 20. Then, the recovery pipe 16 returns the unreacted hydrocarbons desorbed in the regeneration zone 35 of the adsorption device 13 to the reduction device 11 and suppresses the unreacted hydrocarbons from being discharged into the atmosphere. In addition, it functions to make it available for reduction of NOx on the reduction catalyst 21 and to minimize the consumption of the light oil as the reducing agent.

The branch exhaust pipe 17 has one end connected to the exhaust pipe 72 between the adsorber 13 and the heat exchanger 14 and the other end connected to the exhaust pipe 72 downstream of the adsorber 13. When the exhaust gas of the diesel engine 70 is embodied as an exhaust bypass, the exhaust gas can bypass the adsorption device 13 when the exhaust gas is at a low temperature.

The exhaust gas switching device 18 employs butterfly valves 58, 59 which are opened and closed by electric motors 60, 61. The butterfly valve 58 is located upstream of the adsorber 13 and is connected to the exhaust bypass 17. Downstream of the connection point, it is arranged in the exhaust pipe 72, and the butterfly valve 59 is arranged in the exhaust bypass 17 and, depending on the temperature of the exhaust gas of the diesel engine 70,
The adsorber 13 is connected to the exhaust gas outlet 51 of the heat exchanger 14.
Of the suction side inlet 36 and the exhaust bypass 17 are connected.

In the exhaust gas switching device 18, when the exhaust gas has a low temperature, the butterfly valve 58 is closed,
On the other hand, when the butterfly valve 59 is opened and the exhaust gas flows through the exhaust bypass 17, the exhaust gas is discharged into the atmosphere through the exhaust pipe 72, and when the exhaust gas becomes high temperature, the butterfly valve 59 is released. Is closed, while the butterfly valve 58 is opened and the adsorption device 13 is closed.
When the exhaust gas passes through the adsorption zone 34, the unreacted hydrocarbons contained in the exhaust gas are adsorbed by the activated carbon 43 to purify the exhaust gas, and the exhaust pipe 72 Through which the purified exhaust gas is discharged into the atmosphere.

The computer 19 controls the reducing agent supply device 12 and the adsorption device 1 according to the rotational speed and load of the diesel engine 70 and the temperature of the exhaust gas.
3. Control the air supply device 15 and the exhaust gas switching device 18.

More specifically, the computer 19 electrically connects an engine rotation sensor 62, an engine load sensor 63, and an exhaust gas temperature sensor 64 to an input circuit, and supplies the reducing agent supply to an output circuit. Apparatus 1
2 electric reducing agent pump 25 and flow control valves 26, 2
7. Electric motor 44 of suction device 13, air supply device 15
Are electrically connected to the flow control valve 56 and the electric motors 60 and 61 of the exhaust gas switching device 18 and are controlled based on a control pattern previously input to the memory. Of course, the rotation sensor 62 and load sensor 63 are located on the diesel engine 70, and the temperature sensor 64 is connected to the air supply 1
The exhaust pipe 7 upstream of the chamber casing 22 of FIG.
2 placed.

Next, the exhaust gas purifying apparatus 10 described above is used.
Will be described in relation to the operation state of the diesel engine 70. If the diesel vehicle is running at a low speed and the diesel engine 70 is running at a low speed and a low load, the exhaust gas of the diesel engine 70 is at a low temperature. , A load sensor 63, and a signal from the temperature sensor 64, the signal is compared with the control pattern, and the reducing agent supply device 11, the adsorption device 13, the air supply device 15, The output current of the exhaust gas switching device 18 is read, and the read output current is
5 and electric motors 28, 29, 44, 57, 60, 6
Control 1

In this case, the diesel engine 70
Although the exhaust gas contains NOx but falls outside the active region of the catalyst, the electric reducing agent pump 25 is stopped, and the flow regulating valves 26, 27, 56 are closed by the electric motors 28, 29, 57. And its rotor 4
0 is stopped by the electric motor 44, while the butterfly valve 58 is closed by the electric motor 60 and the butterfly valve 59 is opened by the electric motor 61, so that the supply of light oil as the reducing agent Is stopped,
The supply of air is also stopped, and the exhaust gas sequentially passes through the chamber casing 22, the reducing device 11, and the heat exchanger 14 of the reducing agent supply device 12, and further, the exhaust bypass 17 and the exhaust pipe. It flows sequentially to 72 and is released to the atmosphere.

Thereafter, when the diesel vehicle is shifted to high-speed running, the diesel engine 70 is operated at a high speed and a high load, so that combustion is performed at a high temperature in the diesel engine 70. Exhaust gas contains NOx. Then, the computer 19 inputs the engine speed, load and exhaust gas temperature in the operating state of the diesel engine 70 from the rotation sensor 62, the load sensor 63, and the temperature sensor 64 as electric signals, and The output currents of the reducing agent supply device 12, the adsorption device 13, the air supply device 15, and the exhaust gas switching device 18 are read from the control pattern in comparison with the control pattern. The agent pump 25 and the electric motors 28, 29, 44, 57, 60, 61 are controlled.

In this case, the diesel engine 70
Since the exhaust gas contains NOx and the exhaust gas becomes large at high temperatures, the flow control valves 26, 27, 56
Is opened by its electric motors 28, 29, 57 and light oil is supplied by its electric device reductant pump 25 and is sprayed with air into the chamber casing 22 in a mist, while air is 14 and its rotor 40 is rotated by its electric motor 44, while its butterfly valve 58 is opened by its electric motor 60 and its butterfly valve 59 is closed by its electric motor 61.

The exhaust gas of the diesel engine 70 flows upstream of the exhaust manifold 71 and the exhaust pipe 72 and flows into the chamber casing 22, where the light oil is mixed, and while the light oil is decomposed, Flows into the casing 20 and the reduction catalyst 21
Pass through. At that time, NOx contained in the exhaust gas is reduced on the reduction catalyst 21 by the hydrocarbons obtained by decomposing the light oil. The exhaust gas passing through the reduction catalyst 21 includes:
Since unreacted hydrocarbons are contained, the exhaust gas is passed to the heat exchanger 14, cooled to 100 ° C. or less by air sent from the air supply device 15, and adsorbed in the casing 32 of the adsorber 13. In the adsorption zone 34, the unreacted hydrocarbon is adsorbed on the activated carbon 43 filled in the rotor 40, purified, flows downstream of the exhaust pipe 72, and released into the atmosphere.

On the other hand, the adsorbed unreacted hydrocarbon is
When the rotor 40 is rotated by the electric motor 44 into the regeneration zone 35 in the casing 32, the exhaust gas is cooled by being sent from the air supply device 15 and passing through the heat exchanger 14. Desorbed from the activated carbon with heated air. The unreacted hydrocarbon thus desorbed is passed through the recovery pipe 16 to the reduction device 11.
Is returned to the inlet of the casing 20 and is used to reduce NOx contained in the exhaust gas. As a result, in addition to the NOx, the unreacted hydrocarbon, that is, the so-called unreacted reducing agent was also released to the atmosphere, and the consumption of the light oil, that is, the reducing agent, was reduced to a minimum.

In the exhaust gas purifying apparatus 10 described above, the reducing device 11, the reducing agent supply device 12, and the heat exchanger 14 have been described as being independent from each other. Although it is possible, and the heat exchanger 14 has been described as a plate structure, this can also be modified to an appropriate structure,
The exhaust gas switching device 18 includes two butterfly valves 5.
Although the description has been given of the use of the valves 8 and 59, it can be replaced with a single butterfly valve which is disposed at the connection point between the exhaust pipe 72 and the exhaust bypass 17 and is opened and closed by an electric motor.

[0027]

As will be understood from the above description, the exhaust gas purifying apparatus of the present invention includes a reducing device having a reducing catalyst and arranged in the exhaust pipe of a diesel engine, and an upstream side of the reducing device. , A reducing agent supply device arranged in the exhaust pipe, a casing dividing the inside into an adsorption zone and a regeneration zone, and filling the activated carbon into a gas permeable material, and in the casing, between the adsorption zone and the regeneration zone. Downstream of the reducing device, an adsorbing device that connects the adsorbing zone to the exhaust pipe, and an exhaust gas passage and an air passage that are separated from each other by a partition to exchange heat, and The exhaust pipe is connected to the exhaust pipe between the reduction unit and the adsorption unit, and the outlet side of the air passage is connected to the entrance side of the regeneration zone of the adsorption unit. A heat exchanger, an air supply device connected to the inlet side of the air passage of the heat exchanger, and a recovery pipe communicating the inlet side of the reduction device to the outlet side of the regeneration zone of the adsorption device; The branch exhaust pipe branched from the exhaust pipe between the adsorption device and the heat exchanger, and the adsorption zone of the adsorption device and the branch exhaust pipe connected to the outlet side of the exhaust gas passage of the heat exchanger. In the exhaust gas purifying apparatus of the present invention, NOx contained in the exhaust gas and discharged from the diesel engine is reduced on the catalyst by the reducing agent, The reactive reducing agent is recovered and made available to the NOx reduction process to minimize the consumption of the reducing agent, and thus the emission of the unreacted reducing agent is reduced to a high level. Exhaust gas of the diesel engine NOx in conversion rate enabled reduction enables clean, it is very useful and practical for diesel vehicles.

As apparent from the embodiments of the present invention described above with reference to the drawings, the contents of the present invention will be explained to those skilled in the art to which the present invention belongs. It is derived from the technical essence of the invention, which is essential for the achievement of the invention and is the nature of the invention in order to achieve the object of the invention, and is easily realized in an aspect which is objectively recognized as being inherent. Embodied in

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a specific example of an exhaust gas purifying apparatus of the present invention applied to a diesel engine in a diesel vehicle.

FIG. 2 is a cross-sectional perspective view showing an adsorption device of the exhaust gas purification device shown in FIG.

FIG. 3 is a perspective view showing a heat exchanger of the exhaust gas purifying apparatus shown in FIG. 1 with a part cut away.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Reduction apparatus 12 Reducing agent supply apparatus 13 Adsorption apparatus 14 Heat exchanger 15 Air supply apparatus 16 Recovery pipe 17 Branch exhaust pipe 18 Exhaust gas switching apparatus 21 Reduction catalyst 23 Injection nozzle 34 Adsorption zone 35 Regeneration zone 40 Rotor

Claims (4)

(57) [Claims] 1. A reducing device having a reducing catalyst and disposed in the exhaust pipe of a diesel engine, a reducing agent supply device disposed in the exhaust pipe upstream of the reducing device, A casing partitioned into an adsorption zone and a regeneration zone, and a rotor which is filled with activated carbon in a gas-permeable state and is rotated between the adsorption zone and the regeneration zone in the casing, and on the downstream side of the reduction device, An adsorption device that connects the adsorption zone to the exhaust pipe, an exhaust gas passage and an air passage that are separated from each other by a partition and exchange heat are provided, and the exhaust pipe is connected to the exhaust pipe between the reduction device and the adsorption device. A heat exchanger for connecting the outlet side of the air passage to the inlet side of the regeneration zone of the adsorption device; and a heat exchanger for connecting the inlet side of the air passage of the heat exchanger. An exhaust gas purifying apparatus, comprising: an air supply device to be used; and a recovery pipe connecting an outlet side of a regeneration zone of the adsorption device and an inlet side of the reduction device. 2. A reducing device having a reducing catalyst and disposed in the exhaust pipe of a diesel engine, a reducing agent supply device disposed in the exhaust pipe upstream of the reducing device, and A casing partitioned into an adsorption zone and a regeneration zone, and a rotor which is filled with activated carbon in a gas-permeable state and is rotated between the adsorption zone and the regeneration zone in the casing, and on the downstream side of the reduction device, An adsorption device that connects the adsorption zone to the exhaust pipe, an exhaust gas passage and an air passage that are separated from each other by a partition and exchange heat are provided, and the exhaust pipe is connected to the exhaust pipe between the reduction device and the adsorption device. A heat exchanger for connecting the outlet side of the air passage to the inlet side of the regeneration zone of the adsorption device; and a heat exchanger for connecting the inlet side of the air passage of the heat exchanger. An air supply device, a recovery pipe connecting the inlet side of the reduction device to the outlet side of the regeneration zone of the adsorption device, and a branch exhaust pipe branched from the exhaust pipe between the adsorption device and the heat exchanger. And an exhaust gas switching device for switching and connecting an adsorption zone of the adsorption device and a branch exhaust pipe thereof at an outlet side of an exhaust gas passage of the heat exchanger. 3. The exhaust gas purification according to claim 2, wherein the branch exhaust pipe is an exhaust bypass connected to the exhaust pipe downstream of the heat exchanger and upstream and downstream of the adsorption device. apparatus. 4. The exhaust gas switching device according to claim 2, wherein the exhaust gas switching device is a shutoff valve disposed on the exhaust pipe downstream of a branch point of the branch exhaust pipe and another shutoff valve disposed on the branch exhaust pipe. An exhaust gas purifying apparatus as described in the above.