JPH05272331A - Exhaust emission control device and reducing agent supply method and device used therein - Google Patents

Abstract

PURPOSE:To decrease NOx contained in exhaust gas of a diesel engine by using solid urea in a reducing agent of NOx reducing catalyst, and making the NOX reducing catalyst exhibit a high NOX removing ability in a wide temperature range. CONSTITUTION:An exhaust emission control device is provided with NOx reducing catalyst 12 arranged in the middle of an air exhaust pipe 52 of a diesel engine 50, a reducing agent feed nozzle 23 arranged in the air exhaust pipe 52 on the upstream side of the NOx reducing catalyst 12, a reducing gas generator 24 connected to the reducing agent feed nozzle 23 by means of a pipeline 25, a urea supply device 26 to supply solid urea 17 to the reducing gas generator 24 and an air supply device 27 to supply air to the reducing gas generator 24. Reducing gas is generated by thermally decomposing the solid urea 17 under supply of the air, and the reducing gas is supplied to exhaust gas upstream of the NOX reducing catalyst 12.

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 NO _x contained in exhaust gas of a diesel engine, and a reducing agent supply method and apparatus used in the exhaust gas purifying apparatus.

[0002]

BACKGROUND ART In an apparatus that treats NO _X with a combination of a catalyst and urea, since the urea is usually injected in the state of an aqueous solution to the catalyst, a large-capacity tank for storing the aqueous urea solution is required. As a result, it becomes difficult to mount it on a vehicle, and such a device has not been used to process NO _X contained in the exhaust gas of a diesel engine.

Further, in recent years, a zeolite-based catalyst has been developed which is used in combination with a hydrocarbon-based reducing agent such as light oil, propane and propylene for treating NO _X contained in exhaust gas of a diesel engine. However, the present situation is that it has not reached a practical level of NO _X removal capability.

[0004]

[Problem of the invention is an object of the present invention, the solid urea is available to the reducing agent of the NO _X reduction catalyst over a wide temperature range, the diesel engines by exhibit high NO _X removal ability to that NO _X reduction catalyst An object of the present invention is to provide an exhaust gas purifying apparatus that reduces NO _X contained in exhaust gas, suppresses environmental pollution, and also enables reduction in size and weight so that the apparatus can be mounted on a vehicle.

[0005] Another object of the present invention, the solid urea is available to the reducing agent of the NO _X reduction catalyst, wide in the temperature range of diesel engines by exhibit high NO _X removal ability to that NO _X reduction catalyst It is an object of the present invention to provide a reducing agent supply method and device used in an exhaust gas purifying apparatus that can reduce NO _X contained in exhaust gas and can be mounted on a vehicle in addition to being reduced in size and weight.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to NO _X disposed midway in the exhaust pipe of a diesel engine.
A reducing catalyst, a reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reducing catalyst, and a reducing gas generator connected to the reducing agent feed nozzle by a pipe,
A urea supply device for supplying urea to the reducing gas generator,
An air supply device for supplying air to the reducing gas generator, and thermally decomposing solid urea into a reducing gas under air supply, supplying the reducing gas to the NO _x reduction catalyst, and in a wide temperature range, to obtain a high NO _X removal ability to the NO _X reduction catalyst is where that enables reduction processing NO _X contained in the exhaust gas of diesel engines.

The present invention also relates to a NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine and its N
An oxidation catalyst arranged in the exhaust pipe downstream of the O _x reduction catalyst, a reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reduction catalyst, and a reducing agent feed nozzle in the pipe A reducing gas generator, a urea supply device for supplying urea to the reducing gas generator, and an air supply device for supplying air to the reducing gas generator,
Thermally decomposing the reducing gas solid urea under air supply, and supplies the reducing gas to the NO _X reduction catalyst over a wide temperature range, the diesel engine to obtain a high NO _X removal ability to that NO _X reduction catalyst The NO _x contained in the exhaust gas can be reduced, and the carbon monoxide CO excessively contained in the exhaust gas after the NO _x treatment can be reduced.

Further, the present invention comprises a NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine, and a reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reduction catalyst. A reducing gas generator connected by piping to the reducing agent feed nozzle, a urea supply device that supplies urea to the reducing gas generator, an air supply device that supplies air to the reducing gas generator, and the reduction thereof. An electromagnetic shutoff valve arranged in the pipe connecting the gas generator to the reducing agent feed nozzle, an electromagnetic flow control valve arranged in the pipe between the reducing agent feed nozzle and the electromagnetic shutoff valve, and an engine A controller that controls the reducing gas generator, the urea supply device, the air supply device, the electromagnetic cutoff valve, and the electromagnetic flow rate adjustment valve according to the rotation speed, the engine load, and the exhaust gas temperature on the catalyst inlet side. A roller, which thermally decomposes solid urea into a reducing gas under air supply and adjusts the reducing gas to the N by adjusting the amount of exhaust gas discharged from a diesel engine.
It is supplied to the O _x reduction catalyst and its N
O _X reduction catalyst to obtain a high NO _X removal capability is where to the NO _X can be reduced processing included in the exhaust gas of the diesel engine.

Furthermore, the present invention is directed to a NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine,
An oxidation catalyst disposed in an exhaust pipe on the downstream side of the NO _X reduction catalyst, a reducing agent feed nozzle disposed on the exhaust pipe upstream of the NO _X reduction catalyst, the reducing agent feed in the pipe A reducing gas generator connected to the nozzle,
A urea supply device for supplying urea to the reducing gas generator,
An air supply device for supplying air to the reducing gas generator,
An electromagnetic shutoff valve arranged in the pipe connecting the reducing gas generator to the reducing agent feed nozzle, and an electromagnetic flow control valve arranged in the pipe between the reducing agent feed nozzle and the electromagnetic shutoff valve. A controller for controlling the reducing gas generator, the urea supply device, the air supply device, the electromagnetic shutoff valve, and the electromagnetic flow rate adjustment valve according to the engine speed, the engine load, and the exhaust gas temperature on the catalyst inlet side,
Thermally decomposing the reducing gas solid urea under air supply, be adapted to the amount of exhaust gas discharged from a diesel engine by supplying the reducing gas into the NO _X reduction catalyst in a wide temperature range, the NO _X reduction catalyst to obtain a high NO _X removal capability NO _X contained in the exhaust gas of the diesel engines
Of the carbon monoxide CO contained in the exhaust gas after the NO _X treatment is reduced.

Further, the present invention heats urea to generate a reducing gas under an air supply, and
The reducing gas is supplied to the exhaust gas on the upstream side of the NO _x reduction catalyst through which the exhaust gas of the engine passes, and the NO _x reduction catalyst exhibits a high NO _x removal ability in a wide temperature range.

Furthermore, the present invention is a diesel engine.
A reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reduction catalyst arranged in the middle of the exhaust pipe of the engine, and a reducing gas generator connected to the reducing agent feed nozzle by pipes, A urea supply device that supplies urea to the reducing gas generator and an air supply device that supplies air to the reducing gas generator are included, and solid urea is thermally decomposed into a reducing gas under the air supply, and the reducing gas is reduced. is supplied to the NO _X reduction catalyst in a wide temperature range, it is where to exhibit a high NO _X removal ability to that NO _X reduction catalyst.

[0012]

DESCRIPTION OF SPECIFIC EXAMPLES Hereinafter, specific examples of the exhaust gas purifying apparatus of the present invention and the reducing agent supply method and apparatus used in the exhaust gas purifying apparatus will be described with reference to the drawings. FIG. 1 shows a specific example 10 of the exhaust gas purifying apparatus of the present invention using a specific example 13 of the reducing agent supply method and apparatus of the present invention. The exhaust gas purifying apparatus 10 is applied to a diesel engine 50 mounted on a truck (not shown), and is equipped with a gas inlet 18 and a gas outlet 19 and an exhaust pipe 52 of the diesel engine 50.
Including a catalyst casing 11 arranged in the middle of the process, a NO _x reduction catalyst 12 incorporated in the catalyst casing 11, a reducing agent supply device 13, an electromagnetic shutoff valve 14, an electromagnetic flow rate adjusting valve 15 and a controller 16. Assembled

The NO _x reduction catalyst 12 is a honeycomb carrier used as a secondary carrier and the honeycomb carrier.
Composed of a titanium oxide catalyst coated on a carrier, the honeycomb carrier is manufactured by molding a ceramic powder into a flow-through honeycomb structure consisting of many cells with open ends, drying and firing. And the titanium oxide based catalyst is a catalyst coated on a carrier. Of course, the titanium oxide-based catalyst can be replaced with a zeolite-based catalyst.

The reducing agent supply device 13 heats the solid urea 17 under air supply to decompose it into a reducing gas such as ammonia or carbon monoxide, and the reducing gas generated by the decomposition. The diesel engine 5
Where the reducing agent supply method for supplying 0 exhaust gas upstream of the NO _x reduction catalyst 12 is specifically performed, the catalyst casing 1 is provided with a gas inlet 21 and a gas outlet 22.
1, a mixing casing 20 arranged in the exhaust pipe 52 on the upstream side, a reducing agent feed nozzle 23 arranged in the mixing casing 20, and a reducing gas connected to the reducing agent feed nozzle 23 by a pipe 25. It was assembled by the generator 24, the urea supply device 26 that supplies the solid urea 17 to the reducing gas generator 24, and the air supply device 27 that supplies air to the reducing gas generator 24.

The reducing gas generator 24 is provided with an outer casing 28, a furnace tube 29 having an air inlet 30 and a reducing gas outlet 31 and arranged concentrically in the outer casing 28, and the outer casing thereof. 28 and the furnace tube 29 and assembled with an electric heater 32 arranged around the furnace tube 29, and the solid urea 17 supplied into the furnace tube 29 is heated by the electric heater 32 under air supply. And is thermally decomposed into a reducing gas at a temperature of 150 to 250 ° C.

The urea supply device 26 is composed of a tank 33 and a screw feeder 34, and the tank 33 is manufactured as a popper type having an inlet 35 at the upper end and an outlet 36 at the lower end, and is preliminarily ground. The solid urea 17 was charged. On the other hand, the screw feeder 34 includes a screw case 37 arranged between the outlet 36 of the tank 33 and the furnace tube 29 of the reducing gas generator 24, a screw 38 arranged in the screw case 37, and The powdery solid urea 17 is supplied from the tank 33 into the furnace tube 29 by being assembled with the electric motor 39 with a reduction gear that rotates the screw 38.

The air supply device 27 includes an air tank 40 connected to the air inlet 30 of the furnace tube 29 by a pipe 42.
And an electromagnetic air flow rate adjusting valve 41 arranged in the pipe 42.
And an air compressor (not shown) connected to a pipe (not shown) to supply air into the furnace tube 29.

The electromagnetic shut-off valve 14 is arranged in the pipe 25 connecting the furnace tube 29 of the reducing gas generator 24 to the reducing agent feed nozzle 23, while the electromagnetic flow control valve 15 is arranged to reduce the reducing flow. It was placed in the pipe 25 between the agent feed nozzle 23 and the electromagnetic shut-off valve 14.

The controller 16 controls the reducing gas generator 24, the urea supply device 26, the air supply device 27, the electromagnetic cutoff valve 14, and the electromagnetic cutoff valve 14 in accordance with the engine speed, the engine load, and the exhaust gas temperature on the catalyst inlet side. The electromagnetic flow rate control valve 15 is controlled, and the amount of reducing gas mixed with the exhaust gas in the mixing casing 20 is adapted to the operating state of the diesel engine 50, and NO _X contained in the exhaust gas is the NO _X reduction catalyst. 12 and operates as reduced.

More specifically, the controller 16 is a microcomputer, and the input circuit includes a rotation sensor 46, a load sensor 47, and a temperature sensor 48.
Is electrically connected to the electric heater 32 of the reducing gas generator 24, the electric motor 39 of the urea supply device 26, the solenoid coil 45 of the electromagnetic air flow rate adjusting valve 41 of the air supply device 27, and the electromagnetic circuit. The solenoid coil 43 of the shutoff valve 14 and the solenoid coil 44 of the electromagnetic flow rate adjusting valve 15 are electrically connected, and the electric heater 32 is turned on and off based on the control pattern previously input to the memory. Then, the electric motor 39 is operated and stopped, the electromagnetic air flow rate adjusting valve 41 is throttle-adjusted, the electromagnetic shutoff valve 14 is opened and closed, and the electromagnetic flow rate adjusting valve 15 is throttle-adjusted. Of course, the control pattern, the speed and load of the diesel engine 50, and are determined by the emission of the NO _X contained in exhaust gas according to the temperature.

The rotation sensor 46 is the diesel engine.
The load sensor 47 is arranged on the crank shaft of the engine 50, and the load sensor 47 is arranged on the control rack of the fuel injection pump of the diesel engine 50.
The temperature sensor 48 is arranged upstream of the NO _X reduction catalyst 12 and at the gas inlet 18 of the catalyst casing 11.

Next, the reducing agent supply method and apparatus 13
The operation of the exhaust gas purifying apparatus 10 using the above will be described. Now, when the diesel engine 50 is driven and the truck is running, the exhaust gas of the diesel engine 50 is discharged from the exhaust manifold 51.
Through the exhaust pipe 52 to the upstream side of the exhaust pipe 52 to flow into the mixing casing 20, and then to the middle of the exhaust pipe 52 to flow into the catalyst casing 11, the NO _x reduction in the catalyst casing 11. Since it flows on the catalyst 12 and further on the downstream side of the exhaust pipe 52 and is released into the atmosphere, the controller 16 outputs electric signals from the rotation sensor 46, the load sensor 47, and the temperature sensor 48. The electric heater 32 and the electric motor 3 are input by comparing the input signal with the control pattern.
9, the output current for the electromagnetic air flow rate adjusting valve 41, the electromagnetic shutoff valve 14, and the electromagnetic flow rate adjusting valve 15 is read from the control pattern, and the read output current is output to the electric heater 32 and the electric motor. 39 and solenoid coils 43, 44, 45.

As such, the output current varies by its electric heater 32, electric motor 39, and solenoid coil 4.
3, 44, 45, so that the electric heater 32
Generates heat, its electric motor 39 is operated, its electromagnetic shutoff valve 14 is opened, and at the same time, its electromagnetic air flow control valve 41 and electromagnetic flow control valve 15 are adapted to the operating conditions of its diesel engine 50. Since the valve opening is adjusted by adjusting the screw opening,
9, the powdery solid urea 17 in the tank 33 is supplied into the furnace tube 29, and at the same time, air is supplied to the air.
It is supplied from the tank 40 into the furnace tube 29, and in the furnace tube 29, the powdery solid urea 17 is supplied to the electric heater 32 at 150 ° to 250 ° under the air supply.
It is thermally decomposed into a reducing gas at a temperature of ℃. Then, the reducing gas generated by being thermally decomposed in the furnace tube 29 flows to the reducing agent feed nozzle 23 through the pipe 25, and at that time, the flow rate is adjusted by the electromagnetic flow rate adjusting valve 15. It

The reducing gas is injected from the reducing agent feed nozzle 23 into the mixing casing 20, and is uniformly mixed with the exhaust gas flowing into the mixing casing 20. In this way, the exhaust gas mixed with the reducing gas also flows in the exhaust pipe 52 and flows into the catalyst casing 11 and is contained in the exhaust gas when passing through the NO _x reduction catalyst 12. NO _x is
On the NO _x reduction catalyst 12, the reducing gas produces N ₂
Was reduced to. As a result, the exhaust gas was purified by reducing NO _X , flowed to the downstream side of the exhaust pipe 52, and was released into the atmosphere.

[0025] In this case, since ammonia was generated by pyrolysis of solid urea under supply of air, the reducing gas consisting of carbon monoxide was used as the reducing agent, the NO _X reduction catalyst 12 Is the low temperature range (200
(-400 ° C) to a high temperature range, it is activated in a wide temperature range and a high NO _x removal capacity is obtained, and NO contained in exhaust gas is
_X was efficiently reduced to N ₂ .

FIG. 2 shows the exhaust gas purifying apparatus of the present invention which is applied to the exhaust system of the diesel engine 50 mounted on the aforementioned truck and which uses the aforementioned reducing agent supply method and apparatus 13. Other specific example 60
Is shown. This exhaust gas purifying apparatus 60 is assembled by adding another catalyst casing 61 and an oxidation catalyst 62 incorporated in the catalyst casing 61 to the exhaust gas purifying apparatus 10, and first, in the exhaust gas of the diesel engine 50. Process the contained NO _x , the N
After the _Ox treatment, carbon monoxide CO contained in the exhaust gas in excess is being treated.

The exhaust gas purifying device 60 includes the catalyst casing 11, the NO _x reduction catalyst 12, and the reducing agent supply device 1.
3, electromagnetic shutoff valve 14, electromagnetic flow rate adjusting valve 15, controller 16, other catalyst casing 61, and oxidation catalyst 6
2, and the other catalyst casing 61 is arranged in the exhaust pipe 52 downstream of the catalyst casing 11 having the gas inlet 63 and the gas outlet 64 and incorporating the NO _x reduction catalyst 12. Further, the oxidation catalyst 62 was incorporated in the other catalyst casing 61. Of course, the oxidation catalyst 62 is obtained by coating a ceramic carrier manufactured in a flow-through honeycomb structure with alumina and carrying Pt, Pd, Rh, Ce, or the like.

The exhaust gas purifying apparatus 60 described above operates in the same manner as the exhaust gas purifying apparatus 10 described above, and in this exhaust gas purifying apparatus 60, the reducing gas has an optimum amount adapted to the operating condition of the diesel engine 50. The NO _x contained in the exhaust gas supplied to the exhaust gas is subjected to reduction treatment on the reduction catalyst 12 and is excessively contained in the exhaust gas passing through the reduction catalyst 12 after the NO _x treatment. Carbon oxide CO was oxidized on the oxidation catalyst 62.

As is apparent from the embodiments of the present invention described above with reference to the drawings, those having ordinary knowledge in the technical field to which the present invention pertains,
The content of this invention is derived from the technical essence of the invention, which is essential to the formation of the invention and is the nature of the invention in order to achieve the object of the invention, and is objective when it is incorporated. Can be easily embodied in the form recognized in.

[0030]

Benefits of the Invention As will be understood from the above, the exhaust gas purifying apparatus of the present invention is provided with a NO _x reduction catalyst arranged in the middle of the exhaust pipe of a diesel engine and the exhaust gas on the upstream side of the NO _x reduction catalyst. A reducing agent feed nozzle arranged in the pipe, a reducing gas generator connected to the reducing agent feed nozzle by a pipe, a urea supply device for supplying urea to the reducing gas generator, and air for the reducing gas. Since it includes an air supply device for supplying to the generator, in the exhaust gas purifying device of the present invention, solid urea can be thermally decomposed, ammonia,
A reducing gas such as carbon monoxide is generated by the thermal decomposition of solid urea under the supply of air, and the solid urea can be used as a reducing agent, and the NO _x reducing catalyst is reduced by the reducing gas to a high temperature range. exhibit high NO _X removal performance up to, concomitantly, the NO _X is a wide temperature range contained in the exhaust gas of the diesel engine, allowing reduction, environmental pollution is suppressed, also, as a solid as such a reducing agent By using urea, the entire device is compact and
It is lightweight and easy to mount on a vehicle, and as a result, is very useful and practical for the vehicle.

Further, the exhaust gas purifying apparatus of the present invention comprises a NO _x reduction catalyst arranged in the exhaust pipe of a diesel engine, and an oxidation catalyst arranged in the exhaust pipe downstream of the NO _x reduction catalyst. , A reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reduction catalyst, a reducing gas generator connected to the reducing agent feed nozzle by piping, and urea to the reducing gas generator. Since it includes a urea supply device for supplying and an air supply device for supplying air to the reducing gas generator, the exhaust gas purifying device of the present invention,
Solid urea becomes thermally decomposable, reducing gas consisting of ammonia, carbon monoxide, etc. is generated by thermal decomposition of solid urea under the supply of air, solid urea becomes usable as a reducing agent, and NO _x reduction Due to the reducing gas, the catalyst exerts a high NO _X removal ability from a low temperature region to a high temperature region, and accordingly, NO _X contained in the exhaust gas of a diesel engine can be reduced in a wide temperature range. After the NO _x treatment, carbon monoxide excessively contained in the exhaust gas can be treated by oxidation to suppress environmental pollution,
Further, by using the solid urea as the reducing agent, the size and weight of the entire device can be reduced and the device can be easily mounted on a vehicle. As a result, it is very useful and practical for the vehicle.

Furthermore, the exhaust gas purifying apparatus of the present invention is a NO _X disposed in the middle of the exhaust pipe of a diesel engine.
A reducing catalyst, a reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reducing catalyst, and a reducing gas generator connected to the reducing agent feed nozzle by a pipe,
A urea supply device for supplying urea to the reducing gas generator,
An air supply device for supplying air to the reducing gas generator,
An electromagnetic shutoff valve arranged in the pipe connecting the reducing gas generator to the reducing agent feed nozzle, and an electromagnetic flow control valve arranged in the pipe between the reducing agent feed nozzle and the electromagnetic shutoff valve. , A reducing gas generator, a urea supply device, an air supply device, an electromagnetic cutoff valve, and a controller for controlling the electromagnetic flow rate adjustment valve, according to the engine speed, the engine load, and the exhaust gas temperature on the catalyst inlet side. In the exhaust gas purifying apparatus of the present invention, solid urea can be thermally decomposed, and a reducing gas composed of ammonia, carbon monoxide, etc. is generated by thermal decomposition of solid urea under the supply of air, and solid urea can be used as a reducing agent. And then
The NO _x reduction catalyst exerts a high NO _x removal ability from the low temperature region to the high temperature region by the reducing gas, and accordingly, the NO _x contained in the exhaust gas of the diesel engine can be reduced in a wide temperature range, and the environment can be reduced. Pollution is suppressed,
In particular, the reducing gas is generated and adapted to the operating conditions of the diesel engine, and the diesel engine
Since it can be supplied to the exhaust gas of the engine, the NO _x reduction process becomes efficient and economical, and by using solid urea as such a reducing agent, the entire device can be made smaller and lighter and mounted on the vehicle. It is easy to do so that it is very useful and practical for the vehicle.

Furthermore, the exhaust gas purifying apparatus of the present invention includes a NO _x reduction catalyst arranged in the exhaust pipe of a diesel engine and an oxidation catalyst arranged in the exhaust pipe downstream of the NO _x reduction catalyst. And a reducing agent feed nozzle disposed in the exhaust pipe upstream of the NO _x reduction catalyst, a reducing gas generator connected to the reducing agent feed nozzle by piping, and urea reducing gas generator To the reducing gas generator, an air supply device for supplying air to the reducing gas generator, an electromagnetic cutoff valve arranged in the pipe connecting the reducing gas generator to the reducing agent feed nozzle, and An electromagnetic flow rate adjustment valve that is arranged in the pipe between the reducing agent feed nozzle and the electromagnetic cutoff valve, and its reducing gas generation according to the engine speed, engine load, and catalyst inlet side exhaust gas temperature. , The urea supply device, the air supply device, the electromagnetic shutoff valve, and the controller that controls the electromagnetic flow rate adjusting valve. Therefore, in the exhaust gas purifying device of the present invention, solid urea can be thermally decomposed, and ammonia and carbon monoxide can be decomposed. reducing gas made of is generated by the thermal decomposition of the solid urea under supply of air, the solid urea is available as a reducing agent, and a high from the NO _X reduction catalyst is a low temperature region by the reducing gas to a high temperature zone NO Exhibits the ability to remove _X , and accordingly, NO _X contained in the exhaust gas of a diesel engine can be reduced over a wide temperature range, and in addition, carbon monoxide excessively contained in the exhaust gas after the NO _X treatment. Can be oxidatively treated to reduce environmental pollution, in particular, the reducing gas can be generated in conformity with the operating conditions of the diesel engine, and It becomes possible to supply to the exhaust gas of the diesel engine, the NO _x reduction process becomes efficient and economical, and by using solid urea as such a reducing agent, the overall size and weight of the device can be reduced. Easy to install in
As a result, it is very useful and practical for vehicles.

The method for supplying a reducing agent used in the exhaust gas purifying apparatus of the present invention heats urea under the supply of air to generate a reducing gas, and the exhaust gas of the diesel engine is passed through the NO _x reduction catalyst. Since the reducing gas is supplied to the exhaust gas on the upstream side, in the reducing agent supply method used in the exhaust gas purifying apparatus of the present invention, the reducing gas is obtained from solid urea by thermal decomposition, and the NO _x reduction catalyst is the reducing gas. exhibit high NO _X removal capability from the low range to the high temperature region by, in a wide temperature range, the NO _X reduction catalyst can be used to reduce processing NO _X contained in the exhaust gas of diesel engines, also solid urea As exhaust gas can be used as a reducing agent, the exhaust gas purification device has been made smaller and lighter, and as a result, the exhaust gas purification device used in a vehicle can also be used in a vehicle. But it is very useful and practical.

The reducing agent supply system used in the exhaust gas purifying apparatus of the present invention is a reducing agent feed system arranged in the exhaust pipe of the diesel engine upstream of the NO _x reduction catalyst. A nozzle, a reducing gas generator connected by piping to the reducing agent feed nozzle, a urea supply device for supplying urea to the reducing gas generator, and an air supply device for supplying air to the reducing gas generator. because they contain, in the reducing agent supply device for use in an exhaust gas purifying apparatus of the present invention, the reducing gas is obtained from solid urea by pyrolysis, NO _X reduction catalyst is high to a high temperature range from a low temperature region by the reducing gas NO _X Exhibits the ability to remove N in the exhaust gas of diesel engines over a wide temperature range
NO _X reduction catalyst can be used to reduce O _X, and solid urea can be used as a reducing agent.
The entire device has been made smaller and lighter, and with it,
Since the exhaust gas purification device is made smaller and lighter, it becomes extremely easy to mount the exhaust gas purification device on the vehicle, and as a result, it is very useful and practical for the exhaust gas purification device used for the vehicle and also for the vehicle. Target.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an exhaust gas purifying apparatus of the present invention applied to an exhaust system of a diesel engine mounted on a truck and using an embodiment of the reducing agent supply method and apparatus of the present invention. Is.

FIG. 2 shows another embodiment of the exhaust gas purifying apparatus of the present invention applied to the exhaust system of a diesel engine mounted on a truck and using the embodiment of the reducing agent supply method and apparatus of the present invention. FIG.

[Explanation of symbols]

11 Catalyst Casing 12 NO _X Reduction Catalyst 13 Reducing Agent Supply Device 14 Electromagnetic Shut-off Valve 15 Electromagnetic Flow Control Valve 16 Controller 17 Solid Urea 20 Mixing Casing 23 Reducing Agent Feed Nozzle 24 Reducing Gas Generator 26 Urea Supply Device 27 Air Supply Device 61 Other catalyst casings 62 Oxidation catalysts

Claims (6)

[Claims] 1. A NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine, a reducing agent feed nozzle arranged in the exhaust pipe upstream of the NO _x reduction catalyst, and a pipe for the reduction. An exhaust gas purification apparatus including a reducing gas generator connected to a chemical agent feed nozzle, a urea supply device for supplying urea to the reducing gas generator, and an air supply device for supplying air to the reducing gas generator. 2. A NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine, an oxidation catalyst arranged in the exhaust pipe downstream of the NO _x reduction catalyst, and its NO _x.
A reducing agent feed nozzle arranged in the exhaust pipe upstream of the reduction catalyst, a reducing gas generator connected to the reducing agent feed nozzle by piping, and a urea supply for supplying urea to the reducing gas generator An exhaust gas purifying apparatus including an apparatus and an air supply apparatus for supplying air to the reducing gas generator. 3. A NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine, a reducing agent feed nozzle arranged in the exhaust pipe on the upstream side of the NO _x reduction catalyst, and the reduction by piping. A reducing gas generator connected to the agent feed nozzle, a urea supply device for supplying urea to the reducing gas generator, an air supply device for supplying air to the reducing gas generator, and the reducing gas generator. An electromagnetic cutoff valve arranged in the pipe connected to the reducing agent feed nozzle, an electromagnetic flow rate adjusting valve arranged in the pipe between the reducing agent feed nozzle and the electromagnetic cutoff valve, engine speed, engine An exhaust gas including a reducing gas generator, a urea supply device, an air supply device, an electromagnetic cutoff valve, and a controller for controlling the electromagnetic flow rate adjusting valve according to the load and the exhaust gas temperature on the catalyst inlet side. Purifying device. 4. A NO _x reduction catalyst arranged in the middle of an exhaust pipe of a diesel engine, an oxidation catalyst arranged in the exhaust pipe downstream of the NO _x reduction catalyst, and its NO _x.
A reducing agent feed nozzle arranged in the exhaust pipe upstream of the reduction catalyst, a reducing gas generator connected to the reducing agent feed nozzle by piping, and a urea supply for supplying urea to the reducing gas generator Device, an air supply device for supplying air to the reducing gas generator, an electromagnetic shutoff valve arranged in the pipe connecting the reducing gas generator to the reducing agent feed nozzle, and the reducing agent feed nozzle And an electromagnetic flow rate adjusting valve arranged in the pipe between the electromagnetic shutoff valve and the reducing gas generator, urea supply device, air supply device, electromagnetic device according to the engine speed, engine load, catalyst inlet side exhaust gas temperature. An exhaust gas purification apparatus including a shutoff valve and a controller that controls an electromagnetic flow rate adjustment valve. 5. Heating urea under air supply to generate a reducing gas, and supplying the reducing gas to the exhaust gas upstream of a NO _x reduction catalyst through which the exhaust gas of a diesel engine passes. A method for supplying a reducing agent used in an exhaust gas purifying apparatus. 6. A reducing agent feed nozzle arranged in the exhaust pipe upstream of a NO _x reduction catalyst arranged in the middle of the exhaust pipe of a diesel engine, and connected by a pipe to the reducing agent feed nozzle. A reducing agent supply device used for an exhaust gas purifying device, comprising a reducing gas generator, a urea supply device for supplying urea to the reducing gas generator, and an air supply device for supplying air to the reducing gas generator.