JPH05147901A - Fuel reformer - Google Patents

Abstract

PURPOSE:To enhance efficiency of heat transfer at the time of warming-up operation, to prevent local overheat and to shorten start-up time by uniformly heating the whole reforming pipe by combustion gas of a start burner. CONSTITUTION:A fuel reformer is equipped with the group of reforming pipes 3 provided with a reforming catalyst layer 11 in the inside, a pilot burner 4 provided in the upper part of the reforming pipe group, start burners 5, main burners 6 and a main fuel distribution duct 11 and an air distribution duct 12 for burners provided in the lower step thereof. In this fuel reformer, a fuel distribution duct 21 for start is arranged in parallel in the upper step of the main fuel distribution duct.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to heating a gas (hereinafter referred to as a raw material gas) obtained by mixing a hydrocarbon gas with water vapor by a combustion gas, and a gas containing hydrogen as a main component (hereinafter referred to as a gas) by a reforming reaction using a catalyst. , Reformed gas), a reformer of a combustion burner suitable for use in a fuel cell power generation system to achieve uniform combustion and internal structure. The present invention relates to a fuel reformer capable of preventing the above-mentioned overheating phenomenon and improving the reliability of a fuel cell power generation system.

[0002]

2. Description of the Related Art A fuel cell power generation system generally comprises a fuel cell main body, the reformer, a power converter, a controller and many heat exchangers, and is a very complicated system. The reformer burner that is the subject of the present invention is usually attached to the reformer in many cases. An example of a commonly used reformer will be described with reference to FIGS. 3 and 4.

First, the configuration will be described. A large number of regularly arranged reforming tubes 3 are erected in a storage container 1 having an inner surface provided with a heat insulating material 2 having an appropriate thickness, and a pilot burner 4 and a start burner are provided above the storage container 1. 5 and main burner 6 are included.

The pilot burner 4 has a pilot fuel inlet 7 and a pilot air inlet 8, and the main burner 6 has a main fuel inlet 9 and a burner air inlet 10, as well as a main fuel distribution duct 11 and a burner air distribution duct. Equipped with 12. The start burner 5 is composed of a pipe penetrating the main fuel distribution duct 11 and the burner air distribution duct 12, and a nozzle tip 13 at the tip thereof. Further, a raw material gas inlet 14, a reformed gas outlet 15 and an exhaust gas outlet 16 are provided at the lower part of the storage container 1 so as to penetrate the container wall. In addition, the main burner 6 in the storage container 1
A slightly wider space called a burner cavity 17 is provided between and the reforming tube 3.

Next, the function of the reformer having the above structure will be described. The pilot air and the pilot fuel supplied from the pilot air inlet 8 and the pilot fuel inlet 7 are ignited and burned in the pilot burner 4, and the flame thereof reaches near the center of the burner cavity 17. This completes the preparation for starting the reformer.

The start fuel supplied to the start burner 5 is jetted into the burner cavity 17 from the nozzle tip 13 attached to the tip. On the other hand, the burner air supplied from the burner air inlet 10 flows into the burner air distribution duct 12 and is ejected into the burner cavity 17 from a large number of burner air nozzles 18 arranged. Here, the burner air is mixed with the above-mentioned start fuel, and is ignited by the flame of the pilot burner 4 and burned. The combustion heat of the start burner 5 is used not only for raising the temperature of the reformer main body but also as a heat source for warming up the entire fuel cell power plant.

The reformer, which has been heated to a prescribed temperature by the start burner 5 and has completed the load transfer preparation, is switched to the combustion of the main burner 6 as follows. The burner air is burner air nozzle 18 as in the case of combustion of the start burner 5.
The main fuel is continuously supplied, and the main fuel is the main fuel inlet 9
From the tip of a large number of main burners 6 introduced through the main fuel distribution duct 11 to the burner cavity 17
Gushes into. Here, the burner air and the main fuel are mixed, ignited by the flame of the start burner 5 and burned,
It becomes a combustion gas with a high temperature of 1000 ° C or higher and flows into the reforming pipe group provided below.

Further, the combustion gas exchanges heat with the fluid flowing inside the reforming pipe 3 and flows down around the reforming pipe 3 while lowering its temperature, and gathers in the lower part of the storage container 1 to collect the exhaust gas outlet 16
Is discharged from the device.

On the other hand, a gas (hereinafter, referred to as a raw material gas) obtained by mixing a hydrocarbon-based raw material gas and steam flows into the container through a raw material gas inlet 14 at the lower part of the container 1 and reforms from the lower end of the reforming pipe 3. It is guided to the catalyst layer 19 provided inside the tube 3. Next, the catalyst layer 19 flows upward along the length direction of the reforming tube 3,
At that time, the raw material gas is heated by the combustion gas flowing outside and the temperature gradually rises, and the reforming reaction occurs by the action of the catalyst and the reforming gas containing hydrogen as the main component at about 750 ° C reaches the upper end. Changes to.

Further, the reformed gas makes a U-turn at the upper end of the reforming tube 3, flows downward, drops in temperature to about 550 ° C., and is discharged from the reformed gas outlet 15 to the outside of the apparatus. Through the fuel cell body.

At the time of startup, nitrogen gas is normally introduced instead of the raw material gas. Then, the nitrogen gas heated by the combustion gas of the start burner 5 circulates through other devices and pipes (not shown) and is used as a heat source of warm air.

[0012]

In the fuel cell power generation system equipped with the reformer having the above-mentioned structure and function, the start burner 5 of the reformer used when starting the plant is the starter of the plant. It has an important role in controlling the characteristics.

That is, in order to sufficiently warm the equipment and piping of the entire system and to introduce the raw material gas into the reformer and shift to the stage of starting the reforming reaction, the catalyst layer 19 inside the reformer is It is necessary to preheat the temperature to about 400 ° C or higher due to chemical reaction requirements. How smoothly this temperature rising process can be achieved in a short time is one of the important factors that determine the superiority or inferiority of the system.

Generally, natural gas is used as the fuel for the start burner 5, and the temperature of the combustion gas is 50.
It is often a very high temperature gas of 0 ° C to 1500 ° C, and efficient use of this high temperature combustion gas as a heat source for preheating is required as a function of the reformer.

In order to meet this requirement, it is important to heat many reforming tubes 3 evenly. This maximizes the heat transfer efficiency between the nitrogen gas flowing through the inside of the reforming pipe 3 and the combustion gas, thereby effectively raising the temperature of the nitrogen gas as the heat source of the warm air of the plant and increasing the temperature of the catalyst layer 19. Can be leveled.

If the above uniform heating is insufficient,
For example, when the combustion gas of the start burner 5 flows unevenly only around a part of the reforming pipes 3, only the nitrogen gas flowing through the reforming pipes 3 is heated, and the temperature of the nitrogen gas as a whole is not increased. Since the amount becomes small, the heat transfer efficiency is significantly reduced. Therefore, it takes a long time to complete the preheating of the catalyst layers 19 of all the reforming tubes 3, which is a direct cause of deterioration of plant starting characteristics.

Furthermore, some of the above-mentioned reforming tubes 3 are exposed to transient combustion gas, which causes an unnecessary temperature rise, which causes a decrease in the life of the metal material.
And if this local overheating is continued for a long time, in extreme cases,
The reforming pipe 3 may be damaged. The above technical problems are not limited to the start burner 5 and the main burner 6.
The same applies to the configuration of.

Turning to the reformer having the structure shown in FIGS. 3 and 4, the main burners 6 are arranged in a dispersed manner, and it is considered that the combustion gas flows into all the reforming tubes 3 evenly. Has been done. On the other hand, in the start burner 5, the angle of the fuel injection port 20 of the nozzle tip 13 is inclined so that the combustion gas is scattered as much as possible in the surroundings. But,
It can be said that it is extremely difficult to evenly inject the combustion gas into all the reforming pipes 3 only by adjusting the angle of the fuel injection port 20 in the configuration in which only one start burner 5 is arranged in the center. ..

The present invention was devised to solve the above problems, and its purpose is to evenly heat all of the reforming tubes 3 by the combustion gas of the start burner 5 and thereby warm the air. It is an object of the present invention to provide a reformer capable of improving heat transfer efficiency during operation, preventing partial overheating, improving reliability, and shortening start-up time.

[0020]

Means for Solving the Problems The present invention achieves the above object, and includes a reforming tube group composed of a large number of reforming tubes having a reforming catalyst layer provided therein, and a reforming tube group. A storage container for storing the pipe group, a pilot burner, a start burner, a main burner, and a main fuel distribution duct disposed above the reforming pipe group in the storage container, and a lower stage of the main fuel distribution duct. In a fuel reformer having a burner air distribution duct, a start fuel distribution duct is provided in parallel with an upper stage of a main fuel distribution duct.

[0021]

By the above means, the reforming tube can be uniformly heated during the warm-up operation by the start burner, so that the heat transfer efficiency is improved, the starting time is shortened, and partial overheating can be prevented.

[0022]

Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 shows a front view of the overall configuration of a reformer to which the start burner 5 of the present invention is applied, and FIG. 2 shows its detailed view. 1 and 2, the parts denoted by the same reference numerals as those in FIG. 3 and FIG.

The conventional start burner 5 is removed, and a start fuel distribution duct 21 having a start fuel inlet 22 is additionally provided above the burner air distribution duct 12. The partition plate 23 of the start fuel distribution duct 21 has a number of holes concentric with the main burner 6, and the start burner 5 having one end in contact with the holes penetrates the main fuel distribution duct 11 and the burner air duct 12. The start burner 5 is included inside the main burner 6 and has a double pipe structure.

Naturally, the start burners 5 are taken into consideration in terms of shape and dimensions so that the combustion performance of all the start burners 5 is equal to or higher than that of the conventional single burner. Next, the operation of the embodiment of the present invention will be described along the flow of gas. The description of the parts having the same functions as the conventional ones will be omitted.

With the pilot burner 4 ignited and the preparation for starting the reformer completed, the start fuel such as natural gas supplied from the start fuel inlet 22 flows into the start fuel distribution duct 21 and enters the duct. Fill up. And
The starting fuel is the partition plate 23 of the starting fuel distribution duct 21.
It is distributed and flows into the start burner 5 through a large number of holes drilled in, and is ejected from the nozzle tip 13 at the tip of the burner into the burner cavity 17.

Further, the burner air flowing in from the burner air inlet 10 flows into the burner air distribution duct 12 and is filled therewith, and is jetted into the burner cavity 17 from a plurality of burner air nozzles 18 arranged. Then, the burner air is mixed with the above-mentioned start fuel, ignited by the flame of the pilot burner 4 described above, and burned to form a high temperature combustion gas of 500 ° C to 1500 ° C.

Next, the combustion gas flows into a reforming pipe group provided below as a heat source for heating nitrogen gas or the like flowing inside the reforming pipe 3, and the temperature around the reforming pipe 3 is lowered while lowering the temperature. Flow down.

At this time, since the start burners 5 are dispersedly provided on the upper portion of the reforming pipe group, the flame thereof is uniformly supplied to all the reforming pipes 3, and only some of the reforming pipes 3 are provided. There are no problems such as intensive heating. Therefore, the concern of local overheating that causes a reduction in the life of the metal material of the reforming tube 3 is eliminated.

The start burner 5 of the present invention has a smaller flame since it is smaller than the conventional one, and therefore the reforming pipe 3 is less directly exposed to the flame. Further, there is a secondary effect that the combustion gas is almost mixed in the burner cavity 17.

With the above operation, the start burner 5 of the present invention heats all the reforming tubes 3 uniformly, so that the nitrogen gas flowing inside can be heated most efficiently and the temperature of the catalyst layer 19 can be increased. The temperature can be evenly increased in all reforming tubes 3. Therefore, it becomes possible to shorten the warm-up time of the plant as compared with the conventional case.

FIG. 5 shows another embodiment of the present invention. The start fuel distribution duct is located in the upper stage, the burner air distribution duct is located in the middle stage, and the main fuel distribution duct is located in the lower stage. It is ejected from the fuel nozzle 24 into the burner cavity 17. Other configurations are the same as those in the above-described embodiment.

In this structure, since the burner air is ejected in the form of being sandwiched between the start fuel and the main fuel, there is an advantage that the fuel and the air are smoothly mixed, and the nozzle tip is also provided.
Since 13 and the main fuel nozzle 24 are always cooled by the burner air, it is effective in preventing overheating. Other functions and effects are the same as those in the above-described embodiment.

[0033]

As described above, according to the present invention,
Since a large number of small start burners are provided, it is possible to heat all the reforming tubes evenly. Therefore, the nitrogen gas and the catalyst layer are heated evenly and efficiently, and local overheating is prevented. The present invention has an advantage that the start-up time can be effectively shortened, and has an excellent effect in providing a reformer that contributes to improvement in reliability and performance of a fuel cell power generation system.

[Brief description of drawings]

FIG. 1 is an overall vertical cross-sectional view of a fuel reformer according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of FIG.

FIG. 3 is an overall vertical sectional view of a conventional reformer.

FIG. 4 is an enlarged cross-sectional view of a main part of FIG.

FIG. 5 is an overall vertical cross-sectional view of another example of the fuel reformer according to the present invention.

[Explanation of symbols]

1 ... Storage container, 2 ... Insulation material, 3 ... Reforming tube, 4 ... Pilot burner, 5 ... Start burner, 6 ... Main burner, 7
… Pilot fuel inlet, 8… Pilot air inlet, 9…
Main fuel inlet, 10 ... Burner air inlet, 11 ... Main fuel distribution duct, 12 ... Burner air distribution duct, 13 ... Nozzle tip, 14 ... Raw material gas inlet, 15 ... Reformed gas outlet, 16 ... Exhaust gas outlet, 17 ... Burner Cavity, 18 ... Burner air nozzle, 19 ... Catalyst layer, 20 ... Fuel jet, 21 ... Start fuel distribution duct, 23 ... Partition plate, 24 ... Main fuel nozzle.

Claims (4)

[Claims] 1. A reforming tube group composed of a large number of reforming tubes having a reforming catalyst layer provided therein, a container for accommodating the reforming tube group, and a reforming tube group with this container. In a fuel reformer comprising a pilot burner, a start burner, a main burner, and a main fuel distribution duct disposed above the main fuel distribution duct, and a burner air distribution duct disposed below the main fuel distribution duct. A fuel reformer comprising a start fuel distribution duct which is arranged in parallel on an upper stage of the distribution duct. 2. A large number of holes are bored in the partition plate of the start fuel distribution duct, and a large number of start burners having one ends in contact with the holes are vertically provided through the burner air distribution duct and the main fuel distribution duct. The fuel reformer according to claim 1, wherein 3. The fuel reformer according to claim 1, wherein the start burner is contained inside the main burner and has a double pipe structure. 4. The fuel reformer according to claim 1, wherein a start fuel distribution duct is provided in an upper stage, a burner air distribution duct is provided in a middle stage, and a main fuel distribution duct is provided in a lower stage.