JPH06211501A - Reformer - Google Patents

Abstract

PURPOSE:To provide a reformer capable of being miniaturized and improving the heat efficiency. CONSTITUTION:A concentric double inner tube 40 contg. a catalyst bed is provided in the space in a reforming tube 3, a catalyst-packed bed 4 is formed in the spaces of the inner tube and reforming tube, a cylindrical partition is furnished in the internal space of the inner tube, and a returning path 10 is formed for the generated gas so as to pass the inside and outside of the partition. A high-temp. gas passes through a heat-transfer packed bed 7, and the waste gas is discharged from a discharge passage 5. A raw gas passes through the catalyst-packed bed between the innertube 35 of the reforming tube and the inner tube 40 and then passes through the catalyst-packed bed between the the outer tube 34 of the reforming tube and the catalyst-bed inner tube, hence the raw gas is reformed, and the reformed gas passes through the returning path and then is discharged outside the reformer vessel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reformer for producing a hydrogen-rich hydrogen gas by putting a hydrocarbon fuel and steam into a reforming pipe and heating the reforming pipe from the outside.

[0002]

2. Description of the Related Art Heretofore, as one example of this type of reforming apparatus, it is known that a large number of reforming tubes each having a small diameter are provided in a reforming vessel (Japanese Patent Publication No. 24533/1990). In the method, relatively large nonuniformity is observed when measuring the wall temperature of a large number of reforming tubes due to nonuniform flow distribution among the respective reforming tubes and nonuniformity in manufacturing.

This temperature nonuniformity is further increased by increasing the operating load of the reformer. And since the maximum temperature is limited by the allowable temperature of the metal material of the reforming pipe wall,
If the amount of heated combustion gas is limited and the temperature nonuniformity width of a large number of reforming tubes is large, the reforming reaction performance of the reforming tubes having a low temperature becomes worse as the temperature is increased. In other words, the amount of reforming reaction to hydrogen gas decreases, and the conversion rate due to the overall reaction deteriorates.

Conventionally, in order to solve such a problem,
Instead of the large number of small-diameter reforming tubes of the above-mentioned conventional example, it is known to use a reforming tube having a concentric double structure with a large diameter and a small number thereof (Japanese Patent Laid-Open No. 320201/1989). ), Which is configured as in FIG. The reformer main body 1 is a reformer container 2 made of a heat insulating material, and a concentric double-tube configuration (a modified U-shaped cross section) that is housed and fixed in the reformer container 2 and has a bottom surface to close the lower end side. (Cylindrical structure)
Of the reforming pipe 3, a partition cylinder 22 disposed inside the reforming pipe 3 and partitioning the reforming pipe 3 into an inner reforming chamber 31 and an outer reforming chamber 32,
Reforming catalyst 2 filled in the respective reforming chambers 31 and 32
5, 26, a burner 20 disposed on the upper side of a combustion chamber 21 formed in the inner space of the reforming pipe 3, and a combustion formed in the reformer vessel 2 and burned by the burner 20. It is composed of a gas passage 23 and an exhaust pipe 24 which is disposed in a part of the reformer container 2 and discharges combustion exhaust gas to the outside.

In such a structure, the burner 2
When the combustion is performed at 0, the combustion gas flows in the combustion chamber 21 and the combustion gas passage 23 as shown by the arrows, the reforming catalysts 25 and 26 in the reforming pipe 3 are sequentially heated, and the reforming pipe 24 reforms. It is discharged to the outside of the quality container 2. Then, when natural methane gas as the reforming raw material gas is introduced from above the inner reforming chamber 31 of the reforming pipe 3, the natural gas flows from the heated reforming catalyst 25 to the reforming catalyst 26, and the reforming catalyst By the action of 25 and 26, it is steam-reformed and reformed into a gas rich in hydrogen, and this reformed gas is sent from the upper end side of the outer reforming chamber 32 to the outside, for example, a fuel cell.

[0006]

In the conventional example of FIG. 3 described above, the outside reforming chamber (heated chamber) 32 of the reforming pipe 1 is simply filled with the reforming catalyst 26, and the return path Since the gas is not formed, the generated gas that has undergone the reforming reaction in the reforming catalyst 26 layer is discharged to the outside of the reformer main body 1 at a high temperature, so that the thermal efficiency of the reforming device is poor. Further, since the burner 20 is disposed inside the reforming pipe 3, the heat of the burner 20 is transferred from the reforming catalysts 31 to 32, so that the temperature distribution of the reforming catalysts 31 and 32 in the radial direction. The size of the reformer body increases, and the volume of the reformer body increases. It is an object of the present invention to provide a reforming device that has improved thermal efficiency and can be downsized.

[0007]

In order to achieve the above-mentioned object, the present invention has a concentric double-tube structure consisting of an inner tube and an outer tube in a reformer container, and one end of the inner tube and the outer tube. Is provided in the closed reforming pipe, to form a heated chamber in the center of the reformer container, and to form a heating chamber around the heated chamber,
A hot gas passage is formed in the heating chamber, an exhaust passage for exhausting used exhaust gas of the high temperature gas is formed in the heated chamber, and a heat transfer packed layer is formed between the exhaust passage and the reforming pipe. A catalyst layer inner tube having a concentric double tube structure is disposed in the internal space of the reforming tube, and a catalyst packed layer is formed in the space between the catalyst layer inner tube and the reforming tube, and A cylindrical partition is disposed in the inner space of the catalyst layer inner tube, and a return path is formed on each of the inner peripheral side and the outer peripheral side so that the generated gas passes therethrough,
The exhaust gas after passing the high-temperature gas through the heat transfer packed bed is discharged from the exhaust passage, and the raw material gas is passed from the catalyst packed bed side between the inner tube of the reforming tube and the catalyst bed inner tube. In addition, the raw material gas is reformed when the raw material gas is passed through to the catalyst packed bed side between the outer pipe of the reforming pipe and the catalyst layer inner pipe, and the reformed product gas After passing through all of the return paths, it can be taken out of the reformer container.

[0008]

According to the present invention, the high-temperature gas obtained on the outer peripheral side inside the reforming container causes the product gas generated when the raw material gas passes through the catalyst-packed bed to undergo reforming after passing through the return path. Since it can be taken out of the container, the thermal efficiency is improved and the size can be reduced.

[0009]

Embodiments of the reforming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention. A reformer container 1 is provided with a heat insulating layer 2 made of, for example, ceramic wool or glass wool, and the inside of the reformer container 1 has a cylindrical shape on the bottom side. There is provided a perforated plate 6 having a hole through which combustion gas can pass, and a reforming tube 3 having a concentric double tube structure is provided above the perforated plate 6, whereby a heating chamber R
It is divided into 1 and the room to be heated R2.

In the reforming pipe 3, a large-diameter outer pipe 34 and a small-diameter inner pipe 35 are concentrically arranged, and one ends of the outer pipe 34 and the small-diameter inner pipe 35 are closed by a bottom plate 34. Keeps airtightness. Further, in the internal space of the reforming pipe 3, a catalyst layer inner pipe 40 having a concentric double pipe structure having the same structure as the reforming pipe 3 and having a closed bottom is arranged. The space between the catalyst layer inner pipe 40 and the reforming pipe 3 is a heated region, and the reforming catalyst is filled therein so as to form a reciprocating flow path, and thus the catalyst filling layer 4 is formed.

Above the inner tube 35 of the reforming tube 3 and the catalyst layer inner tube 40, a raw material gas inflow pipe 13 and a raw material gas header 17 for allowing the raw material gas to flow into the catalyst packed bed 4 are provided, and the reforming is performed. Above the outer pipe 34 of the pipe 3 and the catalyst layer inner pipe 40, a reformed gas outflow pipe 14 for taking out reformed gas to the outside of the reformer container 1 and a produced gas header 18 are arranged.

At the center of the heated chamber R2, the reformer container 1
An exhaust gas outflow pipe 5 for taking out the exhaust gas after being used for heating is planted outside, and the inside and outside of the reformer container 1 are communicated with each other. The heat transfer filling particles 71 are filled between the exhaust gas outflow pipe 5 and the reforming pipe 3, whereby the heat transfer filling layer 7 is formed.

A cylindrical partition plate 8 is provided inside the inner tube of the reforming tube 3, and spacers 9 are provided on the inner and outer peripheral surfaces thereof.
Are formed in a spiral shape, thereby forming a return path 10 for the generated gas, in which the generated gas described later spirally flows down or flows up between the spacers 9.

A ring-shaped combustion burner 12 is arranged in the heating chamber R1 and has an outer air pipe 122 and an inner fuel pipe 121, and the pipe walls under the respective pipes 121, 122 are arranged. Are provided with burner nozzles 151 and 152. The combustion burner 12 has an air inflow pipe 41 for introducing combustion air and a fuel gas inflow pipe 1 for introducing fuel gas.
1 is connected. The flow passage area of the plate 6 provided at the inlet of the heat transfer filling layer is formed to be larger than the flow passage area of the heat transfer filling layer 7 on the inside.

Next, the operation of this embodiment configured as described above will be described. The fuel gas introduced from the heating fuel gas inflow pipe 11 and the combustion air introduced from the air inflow pipe 41 are ejected from the burner nozzles 151 and 152 provided in the combustion burner 12 into the heating chamber R1.
Burned in the combustion chamber. As a result, the obtained combustion hot gas heats the wall of the outer pipe 34 of the reforming pipe 3. In this case, since the heat insulating layer 2 is formed on the opposite side of the outer tube 34, most of the heat quantity is reflected to the outer tube 34 side.

Then, the combustion hot gas is transferred to the outer reforming pipe 34.
While flowing into the heat transfer filling layer 7 through the holes formed in the bottom plate 6 disposed therein, and the inside of the heat transfer filling layer 7 is raised to heat the inner reforming pipe 35. Then, it is inverted at the upper part, flows down the central exhaust gas outflow pipe 5, and is discharged to the outside of the reformer container 1.

The raw material gas enters the header 17 through the raw material gas inflow pipe 13, enters the inside of the catalyst packed bed 4, flows down, rises at the lower end and exits the catalyst bed upper exit 19, and enters the outer return path 10. After entering, flowing down and inverting at the lower part, it rises inside the return path 10 to exit to the produced gas header 18, and exits to the reformed gas outflow pipe 14. During this, heating is performed from the wall of the outer pipe 34 and the inner pipe 35, a chemical reaction is performed in the catalyst packed bed 4, and the raw material gas composed of, for example, methane gas and steam is reformed and converted into hydrogen and carbon monoxide, The temperature is sufficiently lowered in the return path 10 and flows out from the reformed gas outflow pipe 14.

As a result, the thermal efficiency is improved and the size can be reduced. This is also clear from the following experimental results. That is, FIG. 2 is for explaining this, and shows a comparison of the temperature distributions of the conventional reformer of FIG. 3 and the reformer of the embodiment of FIG. The horizontal axis of FIG. 2 is the distance along the flow path inside the catalyst layer, and the vertical axis is the temperature. Curves 60 and 61 show the temperature of the gas on the combustion heating side and the temperature distribution of the gas in the catalyst layer on the heated side of this example. Both enter from the top, reach the bottom at the midpoint, and flow out again. The arrow 62 attached to each curve indicates the direction of flow.

On the other hand, in the temperature distribution of the conventional reformer shown in FIG. 3, the temperatures at the inflow points are the same as shown by the curves 63 and 64, but the temperature is the same as that of the reformer of this embodiment. Comparing the temperature distributions of the conventional reformer, there is a big difference. In the conventional reforming apparatus, the temperature of the heating-side fluid reaches a midpoint with a gradual temperature decrease, as shown by a curve 63, and enters the heat transfer packed bed to rapidly decrease. Under this influence, as a result of comparing the temperature distribution of the heated catalyst layer with respect to the inflow catalyst layer inlet temperatures at the same temperature, a difference between the curves 61 and 64 was found. While the conventional reformer does not easily increase the temperature as shown by the curve 64, the curve 61 of the reformer of the present embodiment rises rapidly until it reaches the middle point of the first half. This is because the heat is absorbed by the reforming reaction and the temperature rises. Then, after the midpoint, the heat absorption and the heat input are balanced, and the temperature distribution is almost flat.

In the lower half of the outer heating layer of the conventional apparatus, only the inlet of the heat transfer packed layer has good heat transfer and the temperature becomes high, but a flat and uniform temperature cannot be maintained. On the other hand, in the case of the present embodiment, even if a heat transfer filling layer having the same width as the outer side and the inner side is used, the inner side has the effect of reducing the flow passage cross-sectional area, so that the temperature distribution inside the outlet side It becomes possible to raise. Therefore,
When comparing the apparatus of this example with the apparatus of the same heat transfer area as compared with the conventional apparatus, the reforming reaction from methane gas to hydrogen proceeds due to the larger heat input of the apparatus of this example, and the conversion rate Is considered to indicate a high value. In addition, in order to create a device that achieves the same conversion rate, the heat transfer area is 7
5% is good. In this case, the volume of the reformer vessel 1 of the reformer that obtains the same performance is about 50% of that of the conventional reformer.
It turned out that it can be reduced to.

In the conventional reforming apparatus, when the heat transfer packed bed is not provided over the entire length of the reforming tube, that is, when the heat transfer packed bed starts halfway, the heat transfer efficiency is improved at the heat transfer packed bed inlet. Therefore, the temperature of the wall of the reforming tube rises sharply. Therefore, the flow passage area of the lower heat transfer packed bed inlet plate 6 is larger than the flow passage area in the middle of the heat transfer filled layer 4, and the flow passage area is gradually reduced. By heating the inner wall of the quality tube 35, a rapid temperature rise can be avoided.

In the reforming apparatus of this embodiment, the closed end of the reforming tube 3 is arranged at the lower end side, so that an example of a conventional apparatus is upside down. Comparing the heat transfer catalyst layers, there is no problem because the catalyst is filled at the lower end and the film heat transfer coefficient inside the reforming tube is large. However, in the case where the conventional closed end of the reforming pipe is at the upper end, the inner wall of the reforming pipe cannot always be filled with the catalyst particles, and expansion of the reforming pipe creates a space during operation. Since the temperature of the reforming tube will rise,
You need to cover it with insulation.

Further, the reformer of this embodiment requires the spacer 9 in order to maintain the gap in the return path 10 for the reformed product gas. The spacer 9 is arranged in a spiral shape. Therefore, the heat transfer characteristics are improved.

The present invention is not limited to the above-mentioned embodiments, but may be modified as follows, for example. In the embodiment of FIG. 1, the exhaust gas outflow pipe 5 is shown to have a small diameter, but it is also possible to combine these pipe diameters with a large pipe diameter and a small pipe diameter. In this case, the exhaust gas outflow pipe has an annular shape between the multiple pipes, and an inner burner and a combustion chamber are provided inside the exhaust gas outflow pipe via a heat insulating layer. Further, not only one set of reforming pipes having a double pipe structure but also a plurality of sets of reforming pipes having a double pipe structure may be installed in parallel in the reformer. Further, the structure of the embodiment of FIG. 1 may be turned upside down.

[0025]

According to the present invention described above, it is possible to provide a reforming apparatus which has improved thermal efficiency and can be miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of a reforming apparatus of the present invention.

FIG. 2 is a diagram for explaining the operation and effect of the embodiment of FIG.

FIG. 3 is a schematic sectional view showing an example of a conventional reformer.

[Explanation of symbols]

1 ... Reformer container, 3 ... Double reforming tube, 4 ... Reforming catalyst layer, 5
... Exhaust gas outflow pipe, 6 ... Perforated plate, 7 ... Heat transfer packed layer, 8 ... Partition plate, 9 ... Spacer, 10 ... Return path, 11 ... Fuel gas inflow pipe, 12 ... Burner, 13 ... Raw material gas inflow pipe, 14
... reformed gas outlet pipe, 15 ... air inlet pipe, R1 ... heating chamber,
R2 ... Heated room.

Claims (1)

[Claims] 1. A reformer vessel having a concentric double-tube structure consisting of an inner tube and an outer tube, wherein the inner tube and the outer tube are closed at one end, and the reformer is provided in the reformer container. A heated chamber is formed in the center of the container, and a heated chamber is formed around this heated chamber, a high temperature gas flow path is formed in the heated chamber, and a high temperature gas used in the heated chamber is used. A discharge passage for discharging exhaust gas is formed, and a heat transfer filling layer is formed between the discharge passage and the reforming pipe, and a catalyst layer inner pipe having a concentric double pipe structure is arranged in the internal space of the reforming pipe. A catalyst filling layer is formed in the space between the catalyst layer inner pipe and the reforming pipe, and a cylindrical partition is arranged in the inner space of the catalyst layer inner pipe. A return path is formed on each side so that the generated gas passes therethrough, and the exhaust gas after passing the high temperature gas through the heat transfer packed bed is discharged from the discharge passage. The raw material gas is passed from the catalyst packed bed side between the inner tube of the reforming tube and the catalyst layer inner tube, and then between the outer tube of the reforming tube and the catalyst layer inner tube. When the raw material gas is passed to a certain catalyst packed bed side, the raw material gas is reformed, and after the reformed product gas passes through all the return paths, it can be taken out of the reformer container. Reformer.