JPH0610411B2 - Vehicle fuel reformer - Google Patents

Description

Description: TECHNICAL FIELD The present invention is applied to a diesel engine for a vehicle and is capable of removing nitrogen oxides in the engine exhaust and improving combustion efficiency. The present invention relates to a reformer.

[Conventional technology]

The diesel engine has better combustion efficiency than the gasoline engine, but the gasoline engine can remove nitrogen oxides in the exhaust gas with a catalyst, while the diesel engine has a large amount of oxygen in the exhaust gas and therefore has a catalyst. Since it cannot be used, it has the problem that it is difficult to reduce soot and nitrogen oxides.To reduce soot, it is necessary to burn at high temperature, whereas to reduce nitrogen oxide, burn at low temperature. Therefore, it is difficult to simultaneously reduce soot and nitrogen oxides only by improving combustion.

In order to solve this problem, the present applicant has filed Japanese Patent Application No. 63-1.
No. 42401 proposes a new combustion system for diesel engines.

This will be described with reference to FIG. Light oil from the light oil tank 2 which is the fuel of the diesel engine 1 is introduced into the fuel reforming device 4 provided with an appropriate heating means through the solenoid valve 3 and high pressure air is introduced from the brake compressor air tank 5 to 800 A partial oxidation reaction is carried out under conditions of ° C and 8 atm. A reaction product gas composed of carbon monoxide, hydrogen and nitrogen is introduced into the separation device composed of the hydrogen separation membrane 6 composed of aromatic polyimide in a pressurized state. Hydrogen and nitrogen that have passed through the hydrogen separation membrane are pressurized by the pressure pump 7 and introduced into the ammonia synthesis reactor 8. The ammonia synthesized by the ammonia synthesis reactor 8 is introduced into the ammonia separator 13, and the desorbed ammonia is stored in the ammonia tank 9. Unreacted nitrogen,
The hydrogen gas is supplied by the pump 14 to the ammonia synthesis reactor 8
To reflux.

Gases such as carbon monoxide and nitrogen that have not passed through the hydrogen separation membrane 6 are introduced into an engine and burned. On the other hand, the stored ammonia is the NOx amount generated according to the rotation speed and load of the engine 1, or the NO concentration sensor 10
A suitable amount is supplied into the exhaust gas by the control means (ECU) according to the signal from the. The exhaust gas mixed with ammonia is introduced into the NOx treatment catalyst bed 12, and NOx is reduced.

[Problems to be Solved by the Invention]

In short, the system described above reforms a part of the fuel in the fuel reformer 4 to generate a reformed gas containing hydrogen, and the reformed gas is used to improve the diesel combustion process. The purpose of the present invention is to synthesize ammonia from hydrogen and decompose NOx discharged from the engine by a reduction process, thereby significantly reducing NOx and soot discharged from the engine.

Conventionally, a steam reforming process has been known as a fuel reforming method for industrially obtaining hydrogen from petroleum fuel, but it requires water, the size of the apparatus is large, and the temperature, the amount of water, etc. Due to the complicated control, it was difficult to mount it on the vehicle.

The present invention solves the above problems, and an object of the present invention is to reduce the size of the apparatus and mount it on a vehicle while adopting a partial oxidation reaction as a fuel reforming method.

[Means for Solving the Problems]

Therefore, the vehicle-mounted fuel reforming apparatus of the present invention is provided with the glow plug 30 and the catalyst bed 2 arranged in the case 21.
2 and a heat exchanger 25 connected to one end of the case 21,
Air supply pipe 31 for connecting the case 21 and the heat exchanger 25
And a fuel vaporizer 26 connected to the other end of the case 21,
Fuel vaporization coil 27 provided around the catalyst bed 22
And the electric heaters 32 and 33 provided on the fuel vaporizer 26 and the air supply pipe 31, and at the time of start-up, the electric heaters 32 and 33 are energized to supply the fuel into the case 21 through the fuel vaporizer 26. It is characterized in that the fuel is switched to the fuel vaporization coil 27 and supplied into the case 21 due to the temperature rise of the catalyst bed.

It should be noted that the numbers added to the above configurations are for comparison with the drawings for easy understanding, and the configurations of the present invention are not limited thereby.

[Action]

In the present invention, the electric heaters 32, 33 are started at the time of starting.
The fuel is supplied to the fuel vaporizer 26, the vaporized fuel is supplied into the case 21, and the heated air is supplied from the air supply pipe 31. Here glow plug 30
Is started to start the reaction in the catalyst bed 22, and the reaction product gas is discharged through the heat exchanger 25. As the temperature of the catalyst bed 22 rises, the output signal of the temperature sensor 41 switches the fuel to the fuel vaporization coil 27, where the fuel vaporized by the heat of the catalyst bed 22 is supplied into the case 21 and the heat exchanger 25 When the outlet temperature of the electric power source becomes higher, the output signal of the temperature sensor 42 stops the energization of the electric heater 32 and the glow plug 30.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing one embodiment of a vehicle-mounted fuel reforming apparatus of the present invention.

Referring to FIG. 1, a vehicle-mounted fuel reformer 4 of the present invention.
Is a case 21 formed of alumina cement, a catalyst bed 22 arranged in the case 21, a heat exchanger 25 connected to one end of the case 21 and covered with a heat insulating material 23, and the other end of the case 21. And a fuel carburetor 26 connected to the. The catalyst in the catalyst bed 22 is in the form of nickel-based cylindrical pellets.

A fuel vaporizing coil 27 is provided in a coil shape around the catalyst bed 22 on the inner peripheral surface of the case 21, and one end of the coil 27 is connected to the upstream side of the case 21 by a first fuel supply pipe 29. There is. Further, a glow plug 30 for fueling is provided in the case 21. Further, the air in the air tank 5 passes through the heat exchanger 25 and is supplied from the air supply pipe 31 to the upstream side of the case 21. This air supply pipe 31
An electric heater 32 is provided in the.

An electric heater 33 is provided in the fuel vaporizer 26, and the vaporized fuel is supplied into the case 21 through the second fuel supply pipe 35. The fuel in the fuel tank 2 is supplied to the fuel vaporizer 26 via the solenoid valve 37 by the plunger pump 36, and is also supplied to the fuel vaporization coil 27 via the solenoid valve 39. In addition, the outlet of the catalyst bed 22 and the heat exchanger 25
Temperature sensors 41 and 42 are provided at the outlet of the.

The operation of the present invention having the above configuration will be described.

At the time of starting, the electric heaters 32 and 33 are energized to raise the temperature of the air in the air supply pipe to about 300 ° C.
Heat to about 50 ° C. Then, the plunger pump 36
The solenoid valve 39 is closed and the solenoid valve 37 is opened. The fuel is supplied to the fuel vaporizer 26 through the solenoid valve 37 by the plunger pump 36, and the fuel vaporized here is supplied into the case 21 by the second fuel supply pipe 35 and heated by the air supply pipe 31. Air is supplied.
In the case 21, the air-fuel ratio (A / F) is adjusted to 15. Here, the glow plug 30 is activated to start the reaction in the catalyst bed 22, and the reaction product gas is discharged through the heat exchanger 25.

When the outlet temperature reaches about 600 ° C. due to the temperature rise of the catalyst bed 22, the plunger pump 36 increases the fuel supply amount by the output signal of the temperature sensor 41, and at the same time closes the solenoid valve 37 and opens the solenoid valve 39. The fuel is the fuel vaporization coil 2
7, the fuel vaporized by the heat of the catalyst bed 22 is supplied into the case 21. When the outlet temperature of the heat exchanger 25 reaches about 400 ° C., the output signal of the temperature sensor 42 stops the energization of the electric heater 32 and the glow plug 30.

Table 1 shows the results of gas chromatograph analysis of the concentrations of the reformed gas components when the vehicle-mounted fuel reforming apparatus of the present invention was used with various fuels.

Here, the target value is an expected gas concentration when the fuel having an H / C ratio of 1.9 is completely decomposed by the partial oxidation reaction formula. The partial oxidation reaction formula is CnH2n + (n / 2) O2 = nCO + nH2.

As shown in Table 1, even kerosene and gas oil can be decomposed, but there is a tendency for the yields of hydrogen and carbon monoxide to decrease as the fuel becomes heavier. Further, the increase in the nitrogen content in the gas component indicates that the amount of liquid discharge such as water and undecomposed hydrocarbon is considerably large. Furthermore, each fuel had soot formation and catalyst pulverization / deterioration, which was particularly noticeable under pressure. It is considered that catalyst pulverization is a thermal deterioration due to carbon depositing on the catalyst surface and burning.

In order to deal with these problems and suppress soot generation,
As shown in the figure, a small amount of water was added to the fuel vaporizer 26 and the fuel vaporization coil 27 by the plunger pump 40. As a result, it was found that the addition of a small amount of water has a great effect on the suppression of soot formation and the prevention of pulverization and deterioration of the catalyst.

〔The invention's effect〕

As described above, according to the present invention, the device can be made compact while adopting the partial oxidation reaction as a fuel reforming method, and can be mounted on a vehicle.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a vehicle-mounted fuel reforming apparatus of the present invention, and FIG. 2 is a configuration diagram showing a conventional diesel engine combustion system. 21 ... Case, 22 ... Catalyst bed, 25 ... Heat exchanger, 26 ...
Fuel vaporizer, 27 ... Fuel vaporization coil, 30 ... Glow plug, 31 ... Air supply pipe, 32, 33 ... Electric heater.

Claims (1)

[Claims] 1. A glow plug and a catalyst bed arranged in a case, a heat exchanger connected to one end of the case, an air supply pipe connecting the case and the heat exchanger, and another end of the case. A fuel vaporizer, a fuel vaporization coil provided around the catalyst bed, and electric heaters provided in the fuel vaporizer and the air supply pipe. A fuel reformer for mounting on a vehicle, which is supplied into a case through a fuel vaporizer and supplies fuel into the case by switching fuel to the fuel vaporization coil due to a temperature rise of the catalyst bed.