JPH04284843A - Fuel modifying device - Google Patents

Abstract

PURPOSE:To preheat raw material gas without damaging regeneration function and to simplify a fuel battery power plant by providing a preheating pipe in the inner pipe of a fuel modifying device having inner and outer pipes, and further providing a regeneration pipe in the preheating pipe. CONSTITUTION:A preheating pipe 22 is provided in an inner pipe 8 and a regeneration pipe 21 is further provided in the preheating pipe 22 to provide a quadruplex pipe. A preheating path 19 is formed by the regeneration pipe 21 and the preheating pipe 22, and a return path 20 is formed by the inner pipe 8 and the preheating pipe 22, and a regeneration path 17 is formed inside the regeneration pipe 21. Fuel gas of 1000 deg.C or higher flows through a reaction tube 3 downward to be subjected to the heat exchange with raw material gas 15 and, thereafter, the raw material gas 15 flows through the preheating path 19 upward and is subjected to the heat exchange with modified gas 16 through the preheating pipe 22 to be heated to about 500 deg.C or higher. Next, the raw material gas 15 is reversed at the upper end of the preheating pipe 22 to flow through the return path 20 downward and subjected to the heat exchange with the raw material gas in the preheating path 19 through the preheating pipe 22 and the heat exchange with the raw material gas 15 in a modifying catalyst bed 9 through the inner pipe 18 to slightly drop in its temp.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

[Industrial Application Field] The present invention heats a gas (hereinafter referred to as raw material gas), which is a mixture of hydrocarbon gas and water vapor, with combustion gas, and performs a reforming reaction using a catalyst to produce a gas whose main component is hydrogen (hereinafter referred to as raw material gas). In particular, the fuel reformer is suitable for use in fuel cell power generation plants by combining the functions of the reforming reaction tubes (hereinafter referred to as reaction tubes) of fuel reformers that are suitable for use in fuel cell power plants. This invention relates to a fuel reformer that aims to simplify the process.

0002

2. Description of the Related Art A fuel cell power generation plant is generally a very complex system consisting of a fuel cell main body, a fuel reformer, a power converter, a control device, and many heat exchangers.

Regarding the fuel reformer that is the object of the present invention,
An example of a commonly used fuel reformer including a double-tube reaction tube is shown in FIG. The configuration and functions will be explained below using FIG. 3.

A reaction tube 3 is installed upright in a storage container 1 whose inner surface is covered with a heat insulating material 2 of appropriate thickness, and a burner air inlet 4 and a burner fuel inlet 5 are connected to the upper end of the storage container 1. 6 is provided. The reaction tube 3 has a double tube structure consisting of an outer tube 7 and an inner tube 8, and a granular reforming catalyst is filled between the outer tube 7 and the inner tube 8, and a reforming catalyst layer 9 is formed. This reforming catalyst layer 9 is held by a perforated plate 10.

Further, a raw material gas inlet 11, a reformed gas outlet 12, and an exhaust gas outlet 14 are provided at the lower end of the storage container 1 through the container wall, and on the upstream side of the system leading to the raw material gas inlet 11, , a raw material gas preheater 18 are provided.

Burner air inlet 4 and burner fuel inlet 5
The burner air and burner fuel supplied from burner 6
The gas is combusted to become a high-temperature combustion gas 13 of 1000° C. or higher, which is introduced into the storage container 1. Furthermore, the combustion gas 13 is
It flows downward around the reaction tube 3 along its length. At this time, the combustion gas 13 exchanges heat with the raw material gas 15 flowing inside the reaction tube 3, and its temperature gradually decreases. and,
The combustion gas 13 whose temperature has dropped to a predetermined temperature becomes exhaust gas and flows out of the device from the exhaust gas outlet 14. On the other hand, the raw material gas 15, which is a mixture of hydrocarbon gas and water vapor, is preheated to about 450°C by the raw material gas preheater 18, and the raw material gas inlet 1
1 and flows into the lower end of the reaction tube 3. Next, the raw material gas 15
flows upward in the reforming catalyst layer 9 along the length of the reaction tube 3.

At this time, the raw material gas 15 is heated by exchanging heat with the high-temperature combustion gas 13 flowing outside the reaction tube 3 via the outer tube 7, and as the temperature gradually rises, a reforming reaction occurs due to the catalytic action. occurs, and by the time it reaches the upper end of the reforming catalyst layer 9, it is converted to a reformed gas 16 whose main component is hydrogen at about 800°C.

Furthermore, the reformed gas 16 is reversed at the upper end of the reaction tube 3 and flows downward through a regeneration path 17 formed by the inner tube 8. Here, the high-temperature reformed gas 16 heats the raw material gas 15 flowing in the reforming catalyst layer 9 via the inner pipe 8 . Note that this action is called a regeneration function, and effectively utilizes the amount of heat of the high-temperature reformed gas 16.

Then, the reformed gas 16 whose temperature has dropped to about 550° C. is discharged from the reformed gas outlet 12 to the outside of the vessel, and after playing the role as the high temperature side gas of the raw material gas preheater 18, various gases (not shown) are used. The fuel is guided to the fuel cell body via the following equipment.

0010

[Problems to be Solved by the Invention] In a fuel cell power generation plant equipped with a conventional fuel reformer having the configuration and functions as described above, the fuel reformer is the largest piece of equipment among many pieces of equipment. Therefore, the proportion of space cost in the entire system is also increasing. For this reason, efforts have been made in the past to make the product as compact as possible through various structural innovations, improvements in reforming performance, and system improvements, but recently the demand for compactness has become even stronger. .

Another feature required of the fuel reformer is that the temperature of the raw material gas 15 must be preheated to about 450°C. Water vapor may be separated into water droplets in the low-temperature raw material gas 15, and if
When the raw material gas 15 is directly introduced into the reforming catalyst layer 9 and water droplets adhere to the catalyst and evaporate rapidly, the thermal shock causes destruction of the catalyst. Furthermore, since the activity of the catalyst is generally very low at low temperatures, the reforming reaction is difficult to occur, and therefore the reforming catalyst layer 9 in the low temperature region cannot serve its intended purpose. The raw material gas preheater 18 is provided to preheat the raw material gas 15 to an appropriate temperature for the above-mentioned reason, and is one of the essential devices.

[0012] However, the necessity of equipment such as the raw gas preheater 18 is one of the factors contributing to the complexity of fuel cell power generation plants, and is a cause of hindering system simplification and compactness. ing.

The present invention has been made to solve the above-mentioned problems, and its purpose is to combine the functions of a fuel reformer by improving the structure of the reaction tube. An object of the present invention is to provide a fuel reformer that contributes to the simplification of a fuel cell power generation plant. [Structure of the invention]

[0014]

[Means for Solving the Problems] In order to achieve the above object, the present invention takes the following measures.

[0015] A regeneration tube is provided inside the inner tube, and a preheating tube is further provided inside the inner tube to form a quadruple tube type reaction tube, forming a preheating path through which raw material gas flows, a return path, and a regeneration path through which reformed gas flows. do.

[0016]

[Action] The following effects can be obtained by the above means. Since the raw material gas is preheated in the preheating pass and the return pass to a temperature of about 450°C or higher at the inlet of the reforming catalyst layer, a raw gas preheater is not required or can be made very compact.

[0017]

Embodiment An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the parts indicated by the same reference numerals as those in FIG. 3 have the same configuration, and therefore the description thereof will be omitted.

A preheating tube 22 is provided inside the inner tube 8, and a regeneration tube 21 is further provided inside the inner tube 8 to form a quadruple tube.
A preheating path 19 is formed by the and preheating tube 22, and a return path 20 is formed by the inner tube 8 and the preheating tube 22, and
A regeneration path 17 is formed inside the regeneration tube 21 . The lower end of the preheating path 19 is connected to the raw material gas inlet 11, and the upper end is connected to the return path 20. Further, the lower end of the reforming catalyst layer 9 is connected to a return path 20, and the upper end thereof is connected to a regeneration path 17. Next, the operation of the embodiment of the present invention will be explained along the flow of gas. Note that the explanation of parts having the same functions as those of the conventional one will be omitted.

In FIG. 1, combustion gas 13 at a high temperature of 1000° C. or higher flows downward along the length of the reaction tube 3. At this time, the combustion gas 13 exchanges heat with the raw material gas 15 flowing inside the reaction tube 3 via the outer tube 7, and its temperature gradually decreases. On the other hand, water vapor was mixed with hydrocarbon gas. Raw material gas 15 at about 200 to 250° C. flows into the lower end of reaction tube 3 from raw material gas inlet 11 .

Next, the raw material gas 15 flows upward in the preheating path 19. At this time, the raw material gas 15 exchanges heat with the raw material gas 15 flowing through the return path 20 via the preheating tube 22 and the reformed gas 16 flowing through the regeneration path 17 via the regeneration tube 21, and the temperature gradually increases. By the time it reaches the upper end of the preheating tube 22, it is heated to 500°C or more. next,
The heated raw material gas 15 is reversed at the upper end of the preheating tube 22,
It flows downward in the return path 20. At this time, the raw material gas 15 exchanges heat with the raw material gas 15 flowing through the preheating path 19 via the preheating pipe 22 and with the raw material gas 15 flowing through the reforming catalyst layer 9 via the inner tube 8, and its temperature is slightly lowered. Approximately 450
℃.

[0021] Therefore, since the preheating of the raw material gas 15, which was conventionally performed in the raw material gas preheater 18, is performed inside the reaction tube 3, the raw material gas preheater 18 is not necessary or can be made very small. This has a great effect on simplifying and downsizing fuel cell power generation plants.

Next, the preheated raw material gas 15 flows upward through the reforming catalyst layer 9. At this time, the raw material gas 15 is a high-temperature combustion gas 1 flowing outside the reaction tube 3 via the outer tube 7.
As the temperature gradually rises, a reforming reaction occurs due to the catalytic action, and by the time it reaches the upper end of the reforming catalyst layer 9, it has been converted to a reformed gas 16 whose main component is hydrogen at about 800°C. do. Next, the reformed gas 16 is turned around again at the upper end of the reaction tube 3 and flows downward through the regeneration path 17 inside the regeneration tube 21 . At this time, the amount of heat held by the high temperature reformed gas 16 is transmitted to the raw material gas 15 flowing through the preheating path 19 via the regeneration pipe 21, and the reformed gas 16 is lowered to a predetermined temperature. In this way, the present invention also has a regeneration function similar to that of the conventional reformer, and is intended to effectively utilize the calorific value of the high-temperature reformed gas 16. Next, the reformed gas 16 is sent from the upper end of the reaction tube 3 through the reformed gas outlet 14 to the next device (not shown). As another embodiment, a heat transfer promoting member is provided in the preheating path 19 and the regeneration path 17.

FIG. 2 shows an embodiment in which a heat transfer promoting member is provided. As the heat transfer accelerating member, for example, heat transfer accelerating particles such as ceramic, heat transfer fins, etc. can be considered, but in this embodiment, ceramic heat transfer accelerating particles 23 are used. By providing the heat transfer promoting particles 23, the effect of preheating the raw material gas 15 and the effect of regenerating the reformed gas 16 are improved, and the reaction tube 3 can be made more compact. Note that the heat transfer promoting particles 23 can be provided only in either the preheating path 19 or the regeneration path 17 to obtain the same effect as described above.

[0024]

[Effects of the Invention] As explained above, according to the present invention,
Because it has a raw material gas preheating function without sacrificing the excellent regeneration function of conventional fuel reformers, it has the advantage of eliminating the need for a raw gas preheater or making it extremely compact. The present invention has excellent effects in providing a fuel reformer that contributes to the simplification of battery power generation plants.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a fuel reformer according to the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a configuration diagram showing an example of a conventional fuel reformer.

[Explanation of symbols]

3...Reaction tube
7...Outer tube 8...Inner tube
9...Reforming catalyst layer 1
5... Raw material gas
16...Reformed gas 17...Regeneration path
19...Preheating pass 20...Return pass
21... Regeneration tube 22... Preheating tube
23...Heat transfer accelerating particles

Claims (3)

[Claims] Claim 1: A fuel reformer equipped with a double-tube reaction tube consisting of an inner tube and an outer tube arranged concentrically, a preheating tube inside the inner tube, and a preheating tube inside the preheating tube. 1. A fuel reformer characterized in that a regeneration tube is provided and the fuel reformer is configured as a quadruple tube reaction tube. 2. The raw material gas introduced from the lower end of the reaction tube is preheated by passing it through a preheating path between the regeneration tube and the preheating tube, and is reversed at the upper end to pass between the inner tube and the preheating tube. The reformed gas is passed through the return path at the lower end, inverted again at the lower end, and guided to the reforming catalyst layer to undergo a reforming reaction to become a high-temperature reformed gas.The reformed gas is further inverted at the upper end and passed through the regeneration path inside the regeneration tube. 2. The fuel reformer according to claim 1, wherein the reformed gas is introduced into the reaction tube and flows out from the lower end of the reaction tube. 3. The fuel reformer according to claim 1, wherein a heat transfer promoting member is provided in a preheating path between a regeneration tube and a preheating tube of the reaction tube and/or a regeneration path inside the regeneration tube. A pawn.