JP2700248B2 - Heating device for fuel reformer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heating apparatus for a fuel reforming apparatus that generates hydrogen by reacting a fuel containing hydrocarbons or alcohols as a main component with steam.

(Prior Art) Conventionally, there is known a fuel reformer that generates hydrogen by reacting a fuel containing hydrocarbons or alcohols as a main component with steam.

In this type of fuel reforming apparatus, a reforming catalyst is used to react natural gas with steam to obtain a hydrogen-rich reformed gas, but a combustion unit is used as a heating unit for heating the reforming catalyst. A method using a burner and a method using a combustion catalyst are known.

FIG. 3 to FIG. 5 show an example of a fuel reformer using a conventionally known combustion burner. In FIG. 3, 1 is a reforming furnace body, 2 is a plurality of reaction tubes disposed in the body 1, 3 is a reforming catalyst held in the reaction tube 2, and 4 is a mixture of natural gas and steam. A raw material gas inlet for introducing a gas (raw material gas) into the body 1, a reformed gas outlet 5 for taking out a generated reformed gas (hydrogen-containing gas), and 6 a reaction gas tube 2 arranged at a lower portion of the body 1. A heating device for heating, 7 is a fuel supply pipe for supplying fuel to the heating device 6, 8 is an air supply tube for supplying combustion air to the heating device 6, and 9 is a combustion exhaust gas outlet after heating the reaction tube 2. .

FIG. 4 and FIG. 5, which is a sectional view taken along the line BB, show details of the heating device 6; 6A is a main body of the heating device made of a refractory material; A plurality of fuel nozzles 11 arranged are air nozzles arranged in each fuel nozzle 10 portion, and the air nozzle 11 and the fuel nozzle 10 are arranged.
And a combustion burner.

Numeral 12 indicates the fuel supplied from the fuel supply pipe 7 to each fuel nozzle.
A fuel header for distributing the air supplied from the air supply pipe 8 to each air nozzle 11; a fuel flow control valve 14 for controlling the fuel flow rate of the fuel supply pipe 7;
Is an air flow control valve for controlling the air flow of the air supply pipe 8,
16 is a pilot burner that ignites the combustion burner and keeps burning, 17 is an ignition rod for igniting the pilot burner 16, 18 is an ignition device that generates a spark on the ignition rod 17, and 19 is a fuel for the pilot burner 16. This is a pilot gas solenoid valve for shutting off.

In this fuel reforming apparatus, when the raw material gas is fed into the body 1 from the raw material gas inlet 4 in a state where the reaction tube 2 is heated by the combustion burner of the heating device 6, the natural gas of the raw material gas and the steam are converted into the reaction tube. The reaction is carried out by the action of the reforming catalyst 3 in 2 to obtain a hydrogen-rich reformed gas. This reformed gas is taken out from the reformed gas outlet 5 through the inner tube 20 in the reaction tube 2.

In FIG. 3, reference numeral 21 denotes a heat insulating material stretched inside the body 1.

On the other hand, FIG. 6 shows an example of a fuel reforming apparatus using a combustion catalyst for heating the reforming catalyst (for example, JP-A-61-11134). Since the reforming section of this reforming apparatus is the same as the apparatus shown in FIG. 3, the corresponding parts are denoted by the same reference numerals and description thereof is omitted, and only the heating section is described. A case 23 accommodating the combustion catalyst 22 is arranged at the center of the combustion catalyst, a combustion catalyst supply pipe 24 is in contact with the upper part thereof, and a combustion catalyst discharge pipe 25 is connected to the lower part thereof.
Can be supplied and discharged.

The combustion catalyst supply pipe 24 is provided with a catalyst supply valve 24a and a catalyst inlet valve 24b, and the combustion catalyst discharge pipe 25 is provided with a catalyst discharge valve 25a.
Is provided. The lower part of the combustion catalyst supply pipe 24 is formed of a conical porous member.

Fuel air inlet pipe 26 extending to the center of case 23
When air and fuel gas are supplied from the fuel gas introduction pipe 27 and the fuel gas introduction pipe 27, respectively, the fuel and gas are burned in the fuel catalyst 22, and the high-temperature combustion gas obtained by the combustion is supplied from the conical porous member below the combustion catalyst supply pipe 24. The fuel flows out into the combustion chamber 28 and heats the reforming catalyst 3 to enable a reforming reaction.

(Problems to be Solved by the Invention) In the above reformer in which the heating device of the fuel reformer is constituted by a combustion burner as shown in FIG. 3, for example, an on-site type fuel cell system or a hydrogen production device When the system is used in a system with a large load fluctuation as described above, the supply pressure of fuel or air fluctuates due to a sudden change in the load, and unstable combustion and misfire (extinguishment of a fire) easily occur. In particular, when operating at a partial load, the flow rate of fuel supplied to the fuel nozzle 10 and the flow rate of air supplied to the air nozzle 11 decrease. Is likely to occur.

On the other hand, in a fuel reformer using a catalytic combustion type heating device that is not significantly affected by fluctuations in the supply amount or pressure of fuel or air, unstable combustion and misfire during sudden load changes or partial load operation are prevented. However, the following problems arise when the catalytic combustion method is used in an on-site type fuel cell system or a fuel reformer of a hydrogen production apparatus which requires high efficiency, small size, and compact size.

(B) Due to the heat resistance (lifetime) of the combustion catalyst, the combustion temperature cannot be set too high (800 to 1000 ° C or lower). For this reason, it is necessary to increase the excess air ratio (the ratio between the theoretically required air amount and the combustion air amount) and lower the combustion temperature, so that the efficiency of the system is reduced.

(B) By lowering the combustion temperature, the average temperature difference in the heat exchange section of the reaction tube becomes smaller. For this reason, in order to obtain the same heat exchange quantity (assuming that the heat transfer coefficient does not change much), the required heat transfer area of the reaction tube becomes large, and the reformer itself becomes large. Further, the method of flowing out high-temperature combustion gas from a conical porous member is not sufficient in terms of uniform combustion and thinning.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heating device that solves the above-mentioned disadvantages of the prior art, obtains stable combustion performance even with load fluctuations and partial load operation, and obtains a compact and compact fuel reformer. To provide.

(Means for Solving the Problems) A heating device for a fuel reformer according to the present invention comprises an annular fuel-air header, a combustion catalyst inside the header and communicating with the header all around. And characterized in that: Further, a gas-phase combustion device is provided at a lower center portion of the annular heating device including the combustion catalyst.

(Operation) By arranging the combustion catalysts in an annular shape, the combustion is made uniform, and the horizontal cross-sectional area can be increased for the same amount of combustion catalyst, so that the combustion portion can be made thinner.

In addition, a catalytic combustion portion that is not significantly affected by changes in the supply amount or pressure of fuel or air is arranged in an annular shape, and a gas phase combustion portion is arranged in the center of the annular shape of the catalytic combustion portion to reduce the combustion temperature to a required temperature. By increasing the value, stable combustion can be obtained even for load fluctuations and partial load operation without increasing the size of the fuel reformer.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 and 2 are elevational sectional views of one embodiment of a heating device for a fuel reformer according to the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 shows a horizontal sectional view along the line. In these figures, parts corresponding to those in FIGS. 3, 4 and 5 are denoted by the same reference numerals.

The heating device 6 includes an annular catalytic combustion unit 30 arranged in an annular shape, and a gas-phase combustion unit 40 arranged in the lower center of the annular catalytic combustion unit 30.
It is composed of The catalytic combustion section 30 allows a mixed gas of fuel and air (or oxygen) to pass therethrough and performs combustion by the action of the combustion catalyst 22.

The combustion catalyst 22 is disposed between the annular outer honeycomb 30c and the inner honeycomb 30d held up and down by the header member 30b forming the annular header 30a for the mixed gas, and extends over the entire circumference of the header 30a. Communicating. Also the header member 30b
Has a fuel supply pipe 7A for supplying fuel and air to the combustion catalyst 22.
And the air supply pipe 8A are connected. The fuel and air supplied from the outside enter the annular header 30a, are burned by the catalyst 22 through the outer honeycomb 30c over the entire circumference, and the combustion gas is discharged to the center through the inner honeycomb 30d.

On the other hand, the gas-phase combustion section 40 is disposed at the lower center of the catalyst combustion section 30, and a fuel supply pipe 7B and an air supply pipe 8B for supplying fuel and air are connected thereto.

The combustion gas generated in the gas phase combustion section 40 is an annular catalytic combustion section.
Flows through the center of 30.

In the above configuration, the heating unit of the heating device 6 is heated by catalytic combustion having a wide flammable limit (a combustible range of the mixture ratio of fuel and air) and a high blow-off limit (gas flow rate at which blow-off occurs). Since it is composed of the unit 30 and the gas phase combustion unit 40 for heating the temperature of the combustion gas generated by the catalytic combustion to a predetermined temperature, the variation in the load is changed by the heating unit 30 by the catalytic combustion. By allowing the gas phase combustion unit 40 to handle the non-fluctuation component, even if the combustion or air flow rate or pressure fluctuates due to load fluctuation, and even in partial load operation, the annular catalytic combustion unit 30 can be used. By heating the combustion gas to a predetermined temperature by the gaseous phase combustion section 40 at the lower center of the ring, stable combustion can be obtained without increasing the heat transfer area of the reaction tube of the fuel reformer. Combustion temperature of 30 Allowable temperature of the medium 22 or less (800-1
000 ° C.), so that high-temperature deterioration of the combustion catalyst 22 can be prevented.

In addition, by making the combustion catalyst section 30 annular, uniform heating can be achieved, and the horizontal cross-sectional area can be increased for the same amount of combustion catalyst, so that the combustion portion can be made thinner and the overall size of the heating device can be reduced. Can be achieved.

(Effects of the Invention) As described above, the present invention has the following effects.

(A) Stable combustion performance is obtained even with load fluctuations and partial load operation.

(B) The combustion temperature of the catalytic combustion section can be lowered to prevent high-temperature deterioration of the combustion catalyst.

(C) Even if the temperature of the catalytic combustion section is lowered, it is not necessary to increase the heat transfer area of the reaction section by raising the temperature of the combustion gas to a required temperature by the gas phase combustion section below the center.

(D) The entire heating device can be downsized.

(E) Uniform heating can be achieved.

[Brief description of the drawings]

1 and 2 show an embodiment of a heating device for a fuel reformer according to the present invention, FIG. 1 is a sectional view of the heating device, FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a sectional view of a conventional fuel reformer of a combustion burner type, FIG. 4 is a sectional view of a heating device of the fuel reformer shown in FIG. 3, and FIG. FIG. 6 is a sectional view of a conventional fuel reformer having a combustion catalyst type heating device as a heating source. 1. Reforming furnace body, 2. Reactor tube, 3. Reforming catalyst, 6
…… Heating device, 30… Catalyst combustion part, 22 …… Combustion catalyst, 40
…… gas phase combustion part,

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hideo Otaniuchi 4087 Kandate-cho, Tsuchiura-shi, Ibaraki Pref.Hitachi Techno Engineering Co., Ltd. Tsuchiura Office (72) Inventor Yoshiaki Amano 603, Kandamachi, Tsuchiura-shi, Ibaraki Stock Hitachi, Ltd. Tsuchiura Plant (72) Inventor, Akio Hanzawa 603, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture, Tsuchiura Plant, Hitachi, Ltd.

Claims (2)

(57) [Claims] 1. A reaction tube containing a catalyst and a heating device for heating the reaction tube are provided in a body, and a fuel containing hydrocarbons or alcohols as a main component and steam are passed through the reaction tube to contain hydrogen. A heating device for a fuel reformer for producing gas, comprising an annular fuel-air header, and an annularly arranged combustion catalyst inside the header and communicating with the header all around. A heating device for a fuel reformer, comprising: 2. A heating device for a fuel reformer according to claim 1, wherein a gas-phase combustion device is provided at a lower central portion of said annular heating device containing said combustion catalyst.