JPH0422830Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a catalytic combustion reformer, and is particularly useful for preventing dew condensation in the raw material supply section and for making the temperature inside the reformer uniform. The present invention relates to a suitable catalytic combustion reformer.

[Prior art]

Recently, molten carbonate fuel cells using reformers have been considered for use in future alternative thermal power plants, and large-scale ones with a capacity of 1 MW or more are becoming mainstream.

Figure 5 shows liquid natural gas (hereinafter referred to as LNG)
FIG. 2 is an explanatory diagram showing the flow of a molten carbonate fuel cell system using carbonate as a raw material. Raw material LNG30
After passing through the fuel supply compressor 31 and the denitrification device 32, it is mixed with steam produced by recovering exhaust air heat from the battery cathode 36, and is hardly preheated, with a steam/carbon ratio of about 3 (normal in industrial plants), pressure 4
Kg/cm ² G and a temperature of 150 to 170° C. are introduced into the reformer 33, where a decomposition reaction is performed. The reformed gas generated in the reformer 33 is supplied to the battery anode 35 at 3.5 kg/cm ² G and approximately 650°C. The above-mentioned reforming reaction is an endothermic reaction, and the necessary amount of heat is transferred to the battery anode 35 in the combustor 34 which is integrated with the reformer 33.
is obtained by burning the exhaust gas with compressed air created by the exhaust air of the battery cathode 36. The properties of the fuel gas at this time are, for example, the calorific value of approximately 750 Kcal/
m ³ N, pressure approximately 3 Kg/cm ² G, temperature approximately 650°C,
The combustion air has, for example, a pressure of about 3 kg/cm ² G and a temperature of about 200°C.

By the way, a two-stage catalytic combustion system is currently proposed as a reformer for fuel cells. this is,
By using a combustion catalyst in the combustion section and supplying fuel in two stages, the maximum combustion temperature is suppressed, and the life span and reliability of the reaction catalyst and equipment are increased.

FIG. 7 is an axial cross-sectional view showing the structure of such a conventional two-stage combustion reformer.

This device includes a main body casing 7 constituting a combustion section, a plurality of reaction tube outer tubes 2 provided in the combustion section, reaction tube inner tubes 4 inserted into the reaction tube outer tubes 2, and an inner reaction tube. It mainly consists of a reformed gas outlet nozzle 5 where the pipes 4 are collected, and a head shell 6 that supports the reformed gas outlet nozzle 5 and has a raw material inlet nozzle 1. A lower fuel inlet nozzle 8 and a combustion air inlet nozzle 9 are provided on the middle side, an upper fuel inlet nozzle 12 is provided on the middle side, and a combustion gas outlet nozzle 19 is provided on the upper side. In addition, 3 is a reforming catalyst filled between the reaction tube outer tube 2 and the reaction tube inner tube 4, 10 is a lower combustion catalyst layer, 11a and 11b are a lower heat transfer promoting particle layer and an upper heat transfer promoting particle layer, respectively. , 17 is an upper combustion catalyst layer, and 18 is a heat insulating material disposed on the inner surface of the main casing 7. The fuel supplied from the lower stage fuel inlet nozzle 8 merges with the air supplied from the combustion air inlet nozzle 9, and then flows into the lower stage combustion catalyst layer 1.
0 and is combusted within the lower combustion catalyst layer 10. The combustion gas combusted with a large excess of air enters the lower heat transfer promoting particle layer 11a of the upper stage and gives heat to the lower part of the reaction tube outer tube 2. The combustion gas whose temperature has been lowered by applying heat to the lower part of the reaction tube outer tube 2 joins with the fuel introduced from the upper stage fuel inlet nozzle 12, and then enters the upper stage combustion catalyst layer 17, where this fuel is combusted. The temperature is raised again by this, and after heating the upper part of the reaction tube outer tube 2, the combustion gas is discharged to the outside from the combustion gas outlet nozzle 19.

FIG. 6 is a diagram showing a comparison of temperatures in the combustion section and reforming section of a one-stage combustion type reformer and a two-stage combustion type reformer. In the figure, although the maximum temperature of the combustion section is lower in the two-stage combustion reformer, the overall temperature of the reforming section is higher than that of the one-stage combustion reformer, indicating that it has better thermal efficiency. I understand.

[Problem that the invention attempts to solve]

However, in the above conventional technology, when used for a molten carbonate fuel cell, for example, when a large-sized reformer is used, the number of tube rows increases due to the increase in the number of reaction tubes. is not uniformly dispersed, and the temperature in the planar direction of the reformer becomes non-uniform. Furthermore, since the temperature of the supplied upper stage fuel is as high as about 650°C, there is a problem in that a large thermal stress is applied to the inlet nozzle portion of the upper stage fuel. Furthermore, since the raw material to be reformed is supplied at a temperature close to the boiling point of water, if the temperature drops due to factors such as load fluctuations or operational errors, the steam supplied together with the raw material will condense, causing the steam/ There is a problem that the reaction catalyst is damaged due to a decrease in the carbon ratio.

The purpose of the present invention is to solve the above-mentioned problems of the prior art, to make the temperature inside the reformer uniform, and to prevent the condensation of steam supplied together with the raw material. An object of the present invention is to provide a catalytic combustion reformer that can also be used in battery systems.

[Means for solving problems]

In order to achieve the above object, the present invention consists of a two-stage combustion type catalytic combustion section having two stages of packed beds separated by a space, and a plurality of reaction tubes provided integrally with the catalytic combustion section. In a catalytic combustion reformer having a catalytic combustion reformer, an upper stage fuel supply pipe for supplying fuel into the space of the catalytic combustion part from a direction opposite to the combustion gas flow is provided parallel to the reaction tube of the reforming part; The present invention is characterized in that an upper stage fuel inlet pipe communicating with the upper stage fuel supply pipe and a raw material inlet pipe communicating with the reaction tube of the reforming section are adjacent to each other via a heat transfer surface.

[Effect]

By providing a large number of upper stage fuel supply pipes between the reaction tubes that open in the space directly below the combustion catalyst layer, the upper stage fuel is uniformly supplied to the space and combusted. The temperature in the planar direction becomes uniform, and the reforming reaction in each reaction tube is uniformly performed. In addition, by placing the upper stage fuel inlet pipe and the raw material inlet pipe adjacent to each other via a heat transfer surface, the raw material supplied at a relatively low temperature is heated by the fuel supplied at a relatively high temperature. Therefore, damage to the reaction catalyst due to condensation of steam supplied together with raw materials can be avoided. On the other hand, since the fuel in the upper fuel inlet pipe is cooled at this time, the thermal stress in the vicinity of the fuel inlet nozzle is reduced. By preheating the raw material, the cooled fuel flows in the upper stage fuel supply pipe installed parallel to the reaction tube in opposition to the combustion gas flow, and receives the heat of the combustion gas, causing its temperature to rise again. and become easily combusted.

In the present invention, it is preferable to provide one upper stage fuel supply pipe between each reaction tube, so that the upper stage fuel can be supplied more uniformly.
The temperature of the reformer becomes uniform, and the reforming reaction in each reaction tube can be performed uniformly. Further, in order to protect the portion where the upper stage fuel supply pipe comes into contact with the filler of the catalytic combustion section, it is preferable to cover the upper stage fuel supply pipe with a protective cover.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples.

FIG. 1 is an axial cross-sectional view showing the structure of a catalytic combustion reformer that is an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of the reaction tube and upper stage fuel guide pipe in FIG. 1, FIG. 3 is a diagram showing the fuel blowing direction of the upper part of FIG. 1.

The apparatus shown in FIG. 1 includes a main body casing 7 forming a combustion section, a plurality of reaction tube outer tubes 2 provided in the combustion section, and reaction tube inner tubes 4 each inserted into the reaction tube outer tube 2. , an upper reformed gas outlet nozzle 5 where the reaction tube inner tubes 4 gather, a head part shell 6 that supports the reformed gas outlet nozzle 5, and a plurality of reaction tube outer tubes 2 that pass through the tube plate 21. It is mainly composed of an upper stage fuel guide pipe 15 disposed between the upper stage fuel guide pipe 15 and A lower stage fuel inlet nozzle 8 and a combustion air inlet nozzle 9 are provided on the bottom side surface of the main body casing 7, and a lower stage combustion catalyst layer 10 is provided downstream of the confluence point thereof. The inside of the main body casing 7 is covered with a heat insulating material 18, and the catalytic combustion section includes a lower combustion catalyst layer, a bottom space, a lower heat transfer promoting particle layer 11a directly above the bottom space, and a lower heat transfer promoting particle layer 11a directly above the bottom space. It is divided into a space 23 directly above the space 23, an upper combustion catalyst layer 17 above the space 23, an upper heat transfer promoting particle layer 11b following this, and a space directly above the space leading to the combustion gas outlet 19. The head shell 6 is provided with a raw material inlet nozzle 1 and an upper stage fuel inlet nozzle 12, which are adjacent to each other in the heat transfer section 22 with a heat transfer surface interposed therebetween. The upper fuel inlet nozzle 12 is connected to the upper fuel guide pipe 15 via a fuel header 13 and a pigtail 14 . This upper stage fuel guide pipe 15 opens in a space 23 directly below the upper stage combustion catalyst layer 17, and a nozzle tip 16 is provided at its tip. The reaction tube outer tube 2 is
It is long enough to reach the space at the bottom of the main casing 7, and the inner reaction tube 4 inserted therein is slightly shorter than that, and there is a gap between the outer reaction tube 2 and the inner tube 4. A reforming catalyst 3 is filled. 20, the upper stage fuel guide pipe 15 is connected to the upper stage heat transfer promoting particle layer 11b and the upper stage combustion catalyst layer 17.
This is a protective cover that protects the surface that comes into contact with the

In such a configuration, the fuel introduced from the lower stage fuel inlet nozzle 8 is mixed with the combustion air introduced from the combustion air inlet nozzle 9, and is combusted in the lower stage combustion catalyst layer 10. This combustion gas gives heat to the tip of the reaction tube outer tube 2, rises inside the lower heat transfer promoting particle layer 11a, and reaches the lower portion of the reaction tube outer tube 2 via the lower heat transfer promoting particle layer 11a. give heat. Further, the fuel supplied from the upper stage fuel inlet nozzle 12 gives heat to the raw material introduced from the raw material inlet nozzle in the heat transfer section 22, passes through the upper stage fuel header 13, the pigtail 14 and the upper stage fuel guide pipe 15, and then passes through the upper stage fuel header 13, the pigtail 14 and the upper stage fuel guide pipe 15, and then passes through the upper stage fuel header 13, the pigtail 14 and the upper stage fuel guide pipe 15, After being preheated by the combustion gas of the combustion section, it is supplied radially to the space 23 between the upper combustion catalyst layer 17 and the lower heat transfer promoting particle layer 11a, and merges with the combustion gas of the lower fuel containing the excess air. , enters the upper combustion catalyst layer 17 and burns there. The combustion gas whose temperature has been raised again by this combustion rises in the upper heat transfer promoting particle layer 11b and heats the upper part of the reaction tube outer tube 2, and then is discharged from the combustion gas outlet nozzle 19.

According to this embodiment, the upper stage fuel guide pipe 15
are arranged uniformly between the outer tubes 2 of each reaction tube, and the upper stage fuel is uniformly supplied in the plane direction of the reformer, so that the temperature in the plane direction of the reformer becomes uniform and the temperature in each reaction tube is uniform. The reforming reaction takes place uniformly. In addition, the raw material supplied from the raw material inlet nozzle 1 is preheated in the heat transfer section 22 by the fuel in the upper stage, so thermal efficiency is improved and damage to the reaction catalyst due to condensation of steam supplied together with the raw material is eliminated. Furthermore, at this time, the fuel in the upper stage is cooled by the raw material, so the thermal stress acting near the upper stage fuel inlet nozzle is reduced. In addition, since the fuel in the upper stage once cooled has a lower temperature than the combustion gas in the early combustion part, the upper stage fuel guide pipe 15
While passing through the upper heat transfer promoting particle layer 11b, the heat is preheated and the heat is effectively utilized.

FIG. 4 is an explanatory diagram showing another embodiment of the present invention. In this device, a heat exchanger 24 is provided between the fuel line in the upper stage before entering the reformer and the raw material line instead of the heat transfer section 22 in FIG. 1.

According to this example, thermal efficiency is improved more than in the previous example, so steam in the raw material does not condense, damage to the reaction catalyst due to a decrease in the steam/carbon ratio is eliminated, and the upper stage fuel inlet nozzle Thermal stress to nearby areas is reduced. Further, as in the embodiments described above, combustion and heat transfer in the combustion section become uniform, making it possible to perform a stable reforming reaction.

[Effect of idea]

According to the present invention, the temperature in the planar direction of the reformer becomes uniform and the thermal efficiency is improved, so the reforming efficiency is improved and it can be used as a reformer for molten carbonate fuel cells, for example. .

[Brief explanation of drawings]

FIG. 1 is an axial cross-sectional view of a catalytic combustion reformer showing an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of the reaction tubes and upper stage fuel guide pipes of FIG. 1, and FIG. , FIG. 1 is a diagram showing the fuel blowing direction in the upper section, FIG. 4 is an explanatory diagram showing another embodiment of the present invention, and FIG. 5 is a diagram showing the flow of a general molten carbonate fuel cell system. Figure 6 is a diagram comparing the temperature inside the reaction tube of a single-stage combustion reformer and a two-stage combustion reformer, and Figure 7 is a diagram showing a conventional two-stage combustion reformer. FIG. 1... Raw material inlet nozzle, 2... Reaction tube outer tube, 4
... Reaction tube inner tube, 8 ... Lower stage fuel inlet nozzle, 9
... Combustion air inlet nozzle, 12 ... Upper stage fuel inlet nozzle, 15 ... Upper stage fuel guide pipe, 23
...Space department.

Claims (1)

[Claims for Utility Model Registration] (1) An improvement consisting of a two-stage combustion type catalytic combustion section having two stages of packed beds separated by a space, and a plurality of reaction tubes provided integrally with the catalytic combustion section. In a catalytic combustion reformer having a mass part, an upper stage fuel supply pipe is provided in parallel with a reaction tube of the reforming part to supply fuel to the space part of the catalytic combustion part from a direction opposite to the combustion gas flow, and A catalytic combustion reformer characterized in that an upper stage fuel inlet pipe communicating with the upper stage fuel supply pipe and a raw material inlet pipe communicating with the reaction tube of the reforming section are adjacent to each other via a heat transfer surface. (2) The catalytic combustion reformer according to claim 1, characterized in that one upper stage fuel supply pipe is disposed between each of the reaction tubes of the reforming section. (3) The catalytic combustion type claimed in claim 1 or 2, wherein the upper stage fuel supply pipe is covered with a protective cover at a portion of the upper stage fuel supply pipe that comes into contact with a filling section of a catalytic combustion section. reformer.