JP2005056636A - Burner for fuel reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a burner for a fuel reformer having improved combustibility. <P>SOLUTION: (1) The burner 10 of the fuel reformer includes an injector 14 for emitting a jet of a liquid fuel in its center, and a combustion air supply port 16 for supplying combustion air in a swirl state from its outer circumference. (2) A heater 26 is arranged downstream of the injector 14. Where a distance between the heater 26 and the injector 14 is L<SB>EH</SB>, the swirl length of combustion air is L<SB>SW</SB>, the swirl number is S<SB>N</SB>, L<SB>SW</SB>is set to be smaller than L<SB>EH</SB>, and S<SB>N</SB>is set to be not smaller than 0.6. (3) Additionally, a surplus hydrogen supply port 17 for supplying surplus reformed hydrogen in a swirl state is arranged on the outer circumference of the injector 14. (4) Combustion air and surplus hydrogen are supplied being offset from the center of the injector 14. (5) In front surface of the combustion air supply port 16, fixed turning blades 25 are arranged. (6) Surplus hydrogen is supplied from the outer circumference side than the combustion air supply port 16. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a combustor for heating a fuel of a reformer for reforming and preparing hydrogen from another fuel for a fuel cell.

Japanese Patent Laid-Open No. 2002-280042 discloses a combustor for a fuel reformer that mixes and burns fuel, combustion air, and anode offgas of a fuel cell.
However, since the supply fluid is supplied without swirling, the supply fluid is poorly mixed and the combustibility is poor. In addition, in order to sufficiently mix the supply fluids, it is necessary to take a sufficient distance in the combustor axial direction on the downstream side of the supply fluid supply port, and the size of the combustor increases in the axial direction. There was a problem that the mounting property to the vehicle deteriorated.
JP 2002-280042 A

  The problem to be solved by the present invention is a decrease in combustibility due to poor mixing of fluids in a combustor for a fuel reformer.

  An object of the present invention is to provide a combustor for a fuel reformer that improves the combustibility by improving the mixing of fluids.

The present invention for solving the above-mentioned problems and the present invention for achieving the above object are as follows.
(1) Combustor for fuel reformer, provided with an injector for injecting liquid fuel at the center, and combustion for fuel reformer provided with a combustion air supply port for supplying combustion air in a swirl shape on its outer periphery vessel.
(2) A heater is provided downstream of the injector. When the distance between the heater and the injector is L _EH , the swirl distance of the combustion air is L _SW , and the swirl number is S _N , L _SW the less than L _EH, it was the S _N 0.6 or more (1) fuel reformer combustor according.
(3) The combustor for a fuel reformer according to (1), wherein a surplus hydrogen supply port that supplies surplus hydrogen after reforming in a swirl shape is further provided on an outer periphery of an injector that injects liquid fuel provided in the center.
(4) The combustor for a fuel reformer as set forth in (3), wherein the combustion air and the reformed surplus hydrogen are supplied offset from the center of the injector.
(5) The combustor for a fuel reformer according to (3), wherein a fixed swirl blade is provided in front of the combustion air supply port in order to supply the combustion air and the surplus hydrogen after reforming in a swirl shape.
(6) The combustor for a fuel reformer according to (3), wherein surplus hydrogen after the reforming is supplied on an outer peripheral side from the combustion air supply port.

According to the combustor for the fuel reformer of (1) above, the injector for injecting liquid fuel is provided at the center, and the combustion air is supplied in the swirl shape on the outer periphery thereof, so that the heavy liquid fuel is lightened by the centrifugal force of the swirl When the combustion air and the inner and outer circumferences are interchanged, they are mixed and mixed with each other to improve the combustibility. Also, the distance required for mixing is shortened in the axial direction of the combustor by swirling, and the size of the combustor is reduced.
According to the fuel reformer burner of the above (2), the small the L _SW from L _EH, since the the S _N 0.6 or more, and flashback to the upstream side from the heater, the injector by flashback Damage can be prevented.
According to the combustor for the fuel reformer (3), an injector for injecting liquid fuel is provided at the center, and surplus hydrogen is supplied in a swirl shape to the outer periphery of the injector, so that heavy liquid fuel is lightened by the centrifugal force of swirling. When the surplus hydrogen and the inner and outer circumferences are interchanged, they are mixed and mixed with each other to improve the combustibility.
According to the combustor for the fuel reformer of the above (4), the combustion air and the surplus hydrogen after reforming are supplied offset with respect to the center of the injector. Surplus hydrogen swirls and the fluid mixes well without swirling blades. If there are swirl vanes, mix better.
According to the combustor for the fuel reformer of the above (5), since the fixed swirl vane is provided in front of the combustion air supply port, swirl can be generated in the combustion air, and the surplus hydrogen flows accordingly. Can also cause a turn. Since the swirl vane can be easily formed simply by forming a cut and raised on the plate with a press, it is advantageous in terms of cost.
According to the combustor for the fuel reformer of (6) above, surplus hydrogen is supplied from the combustion air supply port on the outer peripheral side. When they are changed, they are mixed and mixed with each other to improve the combustibility.

The fuel reformer combustor of the present invention will be described below with reference to FIGS. 1 to 9 (however, FIG. 9 is a comparative example and is not included in the present invention).
The combustor 10 for a fuel reformer of the present invention heats a fuel (for example, liquid fuel, methanol, etc.) of a reformer that is formed by reforming hydrogen from another fuel for a fuel cell (hereinafter also referred to as FC). It is a combustor (combustion vaporization part) for performing.
As shown in FIG. 1, a fuel reformer combustor 10 includes an injector 14 having a liquid fuel supply port 15 for spraying liquid fuel (for example, methanol) 11 at the center, and swirls combustion air 12 on the outer periphery thereof. It has the combustion air supply port 16 supplied in a shape.
The injector 14 is supported and fixed by an injector holder 18.

The liquid fuel 11 is supplied from the rear of the injector 14 and atomized and sprayed in front of the injector 14 (the side where the heater 26 is located). 27 is an atomization air supply pipe for supplying air for atomizing the liquid fuel.
The room-temperature combustion air 12 is supplied from the combustion air supply pipe 22 between the inner case 21 and the center case 20, and is discharged from there through the combustion air supply port 16 into the injector front space in a swirl shape. The swirl is generated, for example, by providing a fixed swirl vane 25 at the combustion air supply port 16. Combustion air 12 flowing in a swirl manner and atomized liquid fuel 11 are mixed in a space in front of the injector and flow to a heater (electric heater EH or catalyst-equipped electric heater EHC) 26 located downstream thereof. It is ignited and burns.

The fuel reformer combustor 10 may further include an excess hydrogen supply port 17 that supplies the reformed surplus hydrogen 13 (for example, FC anode off-gas) in a swirl shape on the outer periphery of the injector 14. However, the surplus hydrogen 13 may not be supplied. When the surplus hydrogen supply port 17 is provided, it is desirable to provide the surplus hydrogen supply port 17 on the outer peripheral side of the combustion air supply port 16 and supply the surplus hydrogen 13 on the outer peripheral side of the combustion air 12.
However, the surplus hydrogen 13 may be supplied on the inner peripheral side of the combustion air 12 as long as it is on the outer peripheral side of the injector 14, and such a case is also included in the present invention.

As shown in FIGS. 2 and 3, the distance between the heater 26 provided downstream of the injector 14 and the upstream side surface of the injector 14 is L _EH , the swirl distance of the combustion air 12 is L _SW , and the swirl number is _SN . Sometimes L _SW is smaller than _LE H and S _N is 0.6 or more. This is a condition for preventing backfire from the heater 26 to the injector 14.

When the swirl is generated using the swirl vanes 25, a reverse flow (flow from the heater to the injector side) is generated in the L direction (combustor 10 axial direction) in FIG. The swirl distance L _SW is from the point where the backflow occurs to the root surface of the wing. In the L direction, a reverse flow occurs at a swirl distance L _SW or less from the blade root surface, and a normal flow occurs at a swirl distance L _SW or more from the blade root surface. At this time, if the distance L _{EH to the} heater 26 as an ignition source is L _SW > L _EH , the central portion of the heater 26 becomes a reverse flow, and the ignition of the mixed gas and the combustion flame in the heater 26 are directed toward the injector 14. Since so-called backfire may occur, it is necessary to _satisfy L _SW < _LEH .
L _SW is determined by the swirl number S _N , the swirl diameter D _SW and the hub diameter D _hub ,
L _SW = (L _SW ² −D _hub ² ) ^0.5 /(0.35+1.4 S _N ) −eq.1
Here, the swirl number S _N is calculated using the swirl blade angle θ.
S _N = 1.5 · tan θ · {1- (D _hub / D _SW ) ³ } / {1- (D _hub / D _SW ) ² } −eq.2
It becomes. As the swirl blade angle θ increases, the swirl number _SN increases, and as a result, the swirl distance decreases. Experiments have confirmed that no reverse flow occurs when the swirl number is 0.4 or less, and ideally 0.6 or more is necessary. However, if the swirl number is too large, for example, if it is about 3 or more, the pressure loss in the swirl portion increases, so it is desirable to determine the swirl number in consideration of trade-off with the overall efficiency.

As one of a plurality of methods for forming a swirl (swirl flow) in the space between the combustion air supply port 16 and the heater 26, as shown in FIGS. There is a method of supplying the surplus hydrogen 13 or the combustion air 12 with an offset from the center of the injector 14.
In FIG. 7, the combustion air supply pipe 22 and the off-gas supply pipe (surplus hydrogen supply pipe) 23 are offset with respect to the center of the injector 14 (S indicates an offset amount). A tangential direction is introduced into the annular space between the center case 20 and discharged in a swirl form from the combustion air supply port 16, and surplus hydrogen is tangentially introduced into the annular space between the outer case 19 and the center case 20. It is charged and discharged from the surplus hydrogen supply port 17 in a swirl shape.
This tangential direction injection of air and surplus hydrogen may be used in combination with swirl generation by the swirl blade 25 described below (the illustrated example shows the case where they are used together), or tangential direction input alone. When the tangential direction is used alone, the partial pressure loss without the pressure loss due to the swirl vanes 25 can be reduced.

  As shown in FIG. 9 (comparative example), when the gas is supplied from the pair of gas supply pipes opposed to each other without being offset with respect to the center of the injector 14, the input gas collides in the reverse direction in the annular space, and the pressure at the collision part C As the flow rate increases, the velocity distribution to the downstream side of the axial jet becomes non-uniform, the heat generation distribution in the heater section is disturbed, and the reforming performance is deteriorated. However, in the present invention, even if there are a plurality of gas supply pipes (combustion air supply pipe 22 and surplus hydrogen supply pipe 23), they are introduced in the same direction as the tangential direction of the annular space between the center case 20 and the inner case 21. Therefore, the collision part does not occur, the reforming performance is good and stable.

  Also, as shown in FIG. 8, by introducing the combustion air supply pipe 22 at an angle α with respect to the injector axial direction, as shown in FIG. Tests have confirmed that swirl can be generated. In this case, the axial insertion angle α is substantially equal to the swivel blade angle θ. The swirl distance can be controlled by changing the axial injection angle α of the combustion air supply pipe 22. The swirl distance increases as the axial insertion angle θ approaches the injector axial direction.

As another method of forming a swirl (swirl flow) in the space between the combustion air supply port 16 and the heater 26, as shown in FIGS. 1 to 6, combustion air and reforming are performed. There is a method of providing fixed swirl vanes 25 on the front surface of the combustion air supply port 16 or on both front surfaces of the combustion air supply port 16 and the surplus hydrogen supply port 17 in order to supply the surplus hydrogen later in a swirl shape. .
A plate 24 is provided on both gas discharge sides 17 and a fixed swirl blade 25 cut and raised in the circumferential direction is formed on the plate 24. The gas passes through a hole 28 formed by cutting and raising the swirl vane 25, is given a swirl component by the swirl vane 25 and is discharged, and swirls (swirling flow) into the space between the combustion air supply port 16 and the heater 26. ) Is generated. The swirl increases the contact distance between the atomized fuel and air, and the air and off-gas, and the flow is mixed when the heavy component and the light component are exchanged inside and outside by centrifugal force. Combustion is obtained.

As shown in FIG. 4, the swirl vanes 25 are cut up in the same direction. By cutting up with a press, all the swirl vanes 25 can be easily and efficiently formed with a single press stroke.
FIG. 5 shows the turning angle of the swirl vane 25 changed from that shown in FIG. The angle can be easily set by changing the angle of the wing forming portion of the press die.
FIG. 6 shows a configuration in which the shape of the swirl vane 25 is changed from that in FIGS. 4 and 5. In FIG. 6, the swirl vane 25 covers almost the entire area of the hole 28, so that the air blown without hitting the vane 25 is small, and a stronger swirl can be generated.

Next, functions and effects of the present invention will be described.
An injector 14 for spraying liquid fuel is provided at the center, and the combustion air 12 is supplied in a swirl shape on the outer periphery of the injector 14 to the space between the combustion air supply port 16 and the heater 26. When light combustion air and inner and outer circumferences are switched by the centrifugal force of swirl, the liquid fuel and the combustion air are mixed with each other, and the contact distance between the liquid fuel and the combustion air is also Compared to the case of the straight flow, it is elongated and mixing of the atomized liquid fuel and the combustion air is promoted, and the combustibility in the heater 26 is improved.
Also, since the streamline is extended by the swirl, the distance required for mixing the atomized liquid fuel and the combustion air is shortened in the combustor axial direction compared to the case where there is no swirl and flows straight in the axial direction. Is reduced in the axial direction. As a result, the cost of the combustor can be reduced, which is advantageous for mounting in a vehicle.

Also, as shown in FIGS. 2 and 3, the swirl of the combustion air 12 has L _SW smaller than _LE H and S _N is 0.6 or more, so that the heater 26 has a positive flow. Further, it is possible to prevent damage to the resin portion and the O-ring portion of the injector 14 due to the backfire from the heater 26 to the upstream side and the backfire.

  In addition, an injector 14 for spraying liquid fuel is provided at the center, and surplus hydrogen 13 is supplied in a swirl shape on the outer peripheral side of the injector 14 into the space between the combustion air supply port 16 and the heater 26, so that a heavy liquid The fuel is mixed with each other when the light surplus hydrogen and the inner and outer peripheries are switched by the centrifugal force of swirling, and the combustibility is improved.

  When the combustion air 12 and the surplus hydrogen 13 after reforming are offset in the radial direction with respect to the center of the injector 14 and supplied in the tangential direction, the combustion air 12 and the reformed surplus hydrogen 13 are replaced with the combustion air without the swirl vanes 25. The surplus hydrogen after the swirl swirls and mixes well. If the swirl vane 25 is used in combination, the swirl effect by the swirl vane 25 is added and the mixing is further improved.

  When a fixed swirl vane 25 is provided in front of the combustion air supply port 16, the swirl vane 25 can cause the combustion air 12 to swirl, and accordingly the surplus hydrogen 13 flow swirls. Can be made. The swirl vanes 25 can be easily produced simply by forming a cut and raised on the plate 24 by pressing, which is advantageous in terms of cost. In the case of swirl generation by the swirl vane 25, the swirl distance can be changed by changing the cut and raised angle, so that the backfire prevention control is easy.

When surplus hydrogen 13 is supplied and surplus hydrogen 13 is supplied on the outer peripheral side from the combustion air supply port, the surplus hydrogen is lighter by the centrifugal force of the swirling combustion air 12 heavier than hydrogen. When the inner and outer peripheries 13 and 13 are interchanged with each other, mixing is promoted and the combustibility in the heater 26 is improved.
As can be seen from the above, the formation of the swirl facilitates mixing and makes the device more compact, and the swirl can be easily obtained by offsetting the gas and forming the swirl vane, and can prevent backfire. The invention can be used in a combustor for a fuel reformer.

It is sectional drawing of the combustor for fuel reformers of this invention. It is sectional drawing which also showed the heater of the combustor for fuel reformers of this invention. FIG. 3 is a cross-sectional view showing parameters such as a swirl blade angle θ of the combustor for the fuel reformer of FIG. 2. It is a perspective view of the plate which formed the swirl | wing blade of the combustor for fuel reformers of this invention. FIG. 5 is a perspective view of a plate formed with swirl vanes (with different angles from the swirl vanes of FIG. 4) of the combustor for the fuel reformer of the present invention. FIG. 5 is a perspective view of a plate formed with swirl vanes (having a shape different from that of the swirl vanes of FIG. 4) of the combustor for the fuel reformer of the present invention. It is a front view in case the combustion air supply pipe and the surplus hydrogen supply pipe are offset with respect to the center of the injector in the combustor for the fuel reformer of the present invention. FIG. 4 is a cross-sectional view of the combustor for the fuel reformer according to the present invention when the combustion air supply pipe is inclined in the injector axial direction and there are no swirl vanes. FIG. 6 is a front view of an annular space when a pair of combustion air supply pipes are provided toward the center of an injector in a combustor for a fuel reformer of a comparative example.

Explanation of symbols

10 Fuel Reformer Combustor 11 Liquid Fuel 12 Combustion Air 13 Surplus Hydrogen 14 Injector 15 Liquid Fuel Supply Port 16 Combustion Air Supply Port 17 Surplus Hydrogen Supply Port 18 Injector Holder 19 Outer Case 20 Center Case 21 Inner Case 22 For Combustion Air supply pipe 23 Surplus hydrogen supply pipe 24 Plate 25 Swivel blade 26 Heater 27 Atomization air supply pipe 28 Hole

Claims (6)

  A combustor for a fuel reformer, wherein an injector for injecting liquid fuel is provided at the center, and a combustion air supply port for supplying combustion air in a swirl shape is provided on the outer periphery thereof. A heater is provided downstream of the injector, where L _SW is L _EH when the distance between the heater and the injector is L _EH , the swirl distance of the combustion air is L _SW , and the swirl number is S _N. The combustor for a fuel reformer according to claim 1, wherein the combustor is smaller and the _SN is 0.6 or more.   The combustor for a fuel reformer according to claim 1, further comprising a surplus hydrogen supply port for supplying surplus hydrogen after reforming in a swirl shape on an outer periphery of an injector for injecting liquid fuel provided in the center.   The combustor for a fuel reformer according to claim 3, wherein the combustion air and the reformed surplus hydrogen are supplied with an offset from a center of the injector.   The combustor for a fuel reformer according to claim 3, wherein a fixed swirl vane is provided in front of the combustion air supply port to supply the combustion air and the reformed surplus hydrogen in a swirl shape.   The combustor for a fuel reformer according to claim 3, wherein surplus hydrogen after the reforming is supplied on an outer peripheral side from the combustion air supply port.

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