JPS61251501A - Reformer - Google Patents

Abstract

PURPOSE:A mixture of exhaust gas from fuel cells and combustible gas is used and a reformer is composed of a high-temperature combustion catalyst bed, a low-temperature combustion catalyst bed and a heat-transfer packed bed, whereby the volume of the combustion catalysts are reduced to lower the costs, and the formation of hot spots is prevented. CONSTITUTION:The feedstock gas 5 is converted into reformed gas by passing through an inert thermoconductive packed bed 3 and the reformation catalyst bed 2 and the reformed gas is outlet as reformed gas 7 after passing through the inner tube 6. In the meantime, a gas mixture 4 for heating the reforming reactions, which is composed of exhaust air and combustible gas, is passed through the high-temperature combustion catalyst bed 10, the thermoconductive packed bed 9 and the low-temperature combustion catalyst bed 11 and let out as an exhaust gas. Thus, most part of the combustible gas is burnt in the high- temperature combustion catalyst layer 10 and the combustion is completed in the low- temperature combustion catalyst bed 11 which is provided on the place where the combustion gas becomes relatively low in its temperature. Thus, the amount of the catalysts necessary for combustion is saved by an amount corresponding to the thermoconductive packed bed 9. Moreover, since oxidative combustion does not occur in the packed bed 9, hot spots, namely local heating in the reforming tube are not formed by uneven packing of the catalyst.

Description

Detailed Description of the Invention (Technical Field of the Invention) The present invention provides air with a lower oxygen concentration than normal air (hereinafter referred to as
This invention relates to an improvement in a reformer that performs a reforming reaction by burning combustible gas in the presence of a combustion catalyst using exhaust air (referred to as exhaust air) and supplying the combustion heat as the reaction heat necessary for the reforming reaction.

[Technical background of the invention]

In recent years, research into the development and practical application of fuel cells has attracted much attention and interest.By oxidizing the chemical energy of fuel through an electrochemical process, the energy released during the oxidation reaction can be directly converted into electricity. It is a device that converts energy into energy.

A power generation system using this fuel cell has a thermal efficiency of 40 to 50% even on a relatively small scale, and is expected to far exceed new thermal power generation. In addition, sulfur oxides, which are a major social problem in recent years,
Emissions of nitrogen oxides are extremely low, and since the power generation system does not include a combustion cycle, it does not require large amounts of cooling water, generates low vibration noise, and can be expected to have high energy conversion efficiency in principle. It has the characteristics of less environmental problems such as noise and exhaust gas, and also has good responsiveness to load fluctuations. In power generation systems using such fuel cells, as a way to increase the overall efficiency of the system, exhaust air that is exhausted after being used for the electrochemical reaction in the fuel cell is used as fuel for the fuel cell. It has been proposed to use air as a heating source for a reforming reaction in a reformer for producing hydrogen (Japanese Patent Laid-Open No. 57-36784).

By the way, in a reformer that uses ordinary air as the heating source air for the reforming reaction, combustible gas such as CH4, 82 is combusted using ordinary air in the presence of a combustion catalyst, and the combustion heat is A structure has been adopted in which the reforming reaction is carried out by supplying the reaction heat necessary for the reforming reaction (Japanese Patent Laid-Open No. 56-90892). In other words, this type of reformer has at least one reforming reaction tube with an annular cross section that is sealed at one end and is provided with a reforming reaction catalyst layer inside the reformer container, and A combustion catalyst is filled on the outside of this reforming reaction tube so as to cover the entire reforming reaction catalyst layer to form a combustion catalyst layer, and a mixed gas of exhaust air and combustible gas is further supplied to one end of the reforming reaction tube. At the same time, raw material gas for reforming mixed with water vapor is introduced from the other end of the reforming reaction tube and is reformed through the reforming reaction catalyst layer. It is configured to reform into a gas, which is passed through an inner tube from one end of the tube and flows out from the other end.

[Problems in the Background Art] However, in a reformer with such a conventional configuration, the combustion catalyst needs to be filled so as to cover the entire reforming reaction catalyst layer inside the reforming reaction tube. The amount of combustion catalyst used increases accordingly, resulting in high costs. In addition, when an oxidation reaction is caused by this type of combustion catalyst, the oxidation reaction occurs locally due to the non-uniformity of the packing density of the combustion catalyst, which tends to generate hot spots and makes the reforming reaction less effective. The problem is that it is not done. In particular, if such a hot spot occurs around the reforming reaction tube, the wall of the reforming reaction tube will be heated to a higher temperature than other parts, causing trouble.

[Object of the Invention] The present invention was made in order to solve the above-mentioned problems, and its purpose is to reduce the amount of combustion catalyst used to reduce costs, and to solve the problem of non-uniformity in the filling of the combustion catalyst. It is an object of the present invention to provide a highly reliable reforming device that can reliably prevent the formation of hot spots caused by hot spots and carry out the reforming reaction effectively.

[Summary of the invention]

In order to achieve the above object, the present invention disposes at least one reforming reaction tube inside a reformer container, one end of which is sealed and a reforming reaction catalyst layer is provided inside, and A mixed gas of air with an oxygen concentration lower than that of air and a combustible gas is introduced from one end of the reforming reaction tube and flows out from the other end through the outside of the tube, and the raw material gas for reforming is introduced into the reforming reaction tube. The structure is such that the gas flows in from the other end of the reaction tube, passes through the reforming reaction catalyst layer, passes through the inner tube from one end, and flows out from the other end. Furthermore, a heat transfer filling is provided on the mixed gas introduction side outside the reforming reaction tube. A high-temperature combustion catalyst layer is formed through the layers, and a low-temperature combustion catalyst layer is formed on the mixed gas outflow side outside the reforming reaction tube.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. FIG. 1 shows an example of the configuration of a reforming apparatus according to the present invention, and the figure shows a case where the present invention is applied to a single reforming reaction tube with a double-tube structure.

In the figure, reference numeral 1 denotes a reforming reaction tube that is sealed at one end and is provided with a reforming reaction catalyst layer 2 and an inert heat transfer filler 3 inside, and is arranged inside a reformer container (not shown). ing. Further, 4 is a mixed gas of exhaust air and combustible gas necessary for the reforming reaction, and this mixed gas 4 is transferred to the reforming reaction tube 1.
It is introduced from one end, passes through the outside, and flows out from the other end. Zarani, 5 is CH4.

This raw material gas is made by mixing water vapor with hydrocarbon such as LPG or alcohol, and is used for a reforming reaction, and this raw material gas 5 is introduced from the other end of the reforming reaction tube 1,
The reformed gas is reformed in the reforming reaction catalyst layer 2 via the inert heat transfer filler 3, and the reformed gas is passed through the inner pipe 6 from one end thereof and flows out from the other end as reformed gas 7. I have to. In the above, the inner pipe 6 is used to take out the reformed gas obtained by the reforming reaction, and usually a plug pipe is inserted inside it to reduce the distance between the inner pipe 6 and the reformed gas. Heat transfer from the gas 7 to the reforming reaction catalyst layer 2 and the inert heat transfer filler 3 is promoted, an example of which is shown in FIG. In FIG. 2, 8 is a plug pipe, and by increasing the flow rate of the reformed gas 7 flowing between the inner pipe 6 and the wall of the plug pipe 8, the sensible heat of the reformed gas 7 is transferred to the reforming reaction catalyst layer.
．． It is applied to the raw material gas 5 flowing through the inert heat transfer filler 3 to promote the reforming reaction.

On the other hand, on the mixed gas 4 introduction side outside the reforming reaction tube 1,
A high-temperature combustion catalyst layer 10 is formed from the end of the reforming reaction tube 1 to a part of the outside thereof through a heat transfer packed layer 9 filled with a heat transfer promoting material. The mixed gas 4 outflow side, that is, the mixed gas 4 opposite introduction side of the heat transfer packed bed 9,
A low-temperature combustion catalyst layer 1 is located at a position that does not cover the reforming reaction catalyst layer 2 (a position corresponding to the filling position of the inert heat transfer filler 3).
1 is formed. Here, as the combustion catalyst of the high-temperature combustion catalyst layer 10, a catalyst that can withstand relatively high temperatures is used, and one type or several types of catalysts may be mixed or stacked in layers as necessary. Thereby, the mixed gas 4 is combusted in the presence of the high-temperature combustion catalyst layer 1o and the low-temperature combustion catalyst layer 11, and is allowed to flow out as combustion exhaust gas 12 to the outside. In the above, the inert heat transfer filler 3 gives the heat of the combustion exhaust gas 12 combusted in the low temperature combustion catalyst layer 11 to the raw material gas 5 introduced into the reforming reaction tube 1, heats it, and converts it into a reforming reaction catalyst. It has the role of increasing the temperature when introduced into layer 2.

In the reformer having such a configuration, a mixed gas 4 of exhaust air and flammable gas is introduced into the high-temperature combustion catalyst layer 10 from one end of the reforming reaction tube 1, and in the presence of this catalyst, the exhaust air converts combustible gas. Burn most of it. This combustion gas is introduced into the low-temperature combustion catalyst layer 11 through the heat transfer packed bed 9, and after completely burning the unburned portion of the combustible gas in the presence of this catalyst, it is discharged to the outside as combustion exhaust gas 12. Ru. On the other hand, the raw material gas 5, which is a mixture of hydrocarbons such as CH4, LPG, or alcohol, and water vapor, is supplied to the reforming reaction tube 1.
It is introduced from the other end, preheated by the combustion heat of the combustion gas with the inert heat transfer filler 3, and introduced into the reforming reaction catalyst layer 2. At this time, the combustion heat in the high-temperature combustion catalyst layer 10 passes through the heat transfer packed bed 9 and is supplied to the reforming reaction catalyst layer 2 as reaction heat necessary for the reforming reaction, so that the raw material gas 5 is reformed into reformed gas by a reforming reaction, and this reformed gas 7 is discharged from the other end through the inner tube 6 inside the reforming reaction tube 1.

In this case, the mixed gas 4 introduction side outside the reforming reaction tube 1 is provided with a heat transfer packed layer 9 filled with a heat transfer accelerator from the end of the reforming reaction tube 1 to a part of the outside thereof. to form a high-temperature combustion catalyst layer 10, and in a position that does not cover the reforming reaction catalyst layer 2 on the mixed gas 4 outflow side of the reforming reaction tube 1, that is, on the mixed gas 4 inlet side of the heat transfer packed bed 9. Low temperature combustion catalyst 1
111, most of the combustible gas is combusted in the high temperature combustion catalyst layer 10, and the low temperature combustion catalyst layer is formed at a location where the combustion gas is at a relatively low temperature (about 500 to 600 degrees Celsius). At step 11, the combustion reaction of the combustible gas can be completed. Thereby, the amount of combustion catalyst required for the reforming reaction can be omitted by the amount corresponding to the heat transfer packed bed 9. In addition, since oxidative combustion is not performed in the heat transfer packed bed 9, it is possible to eliminate local heating of the reforming reaction tube 1, that is, the formation of hot spots, due to non-uniformity in the charging of the combustion catalyst as in the conventional case. It becomes possible to carry out an extremely effective reforming reaction.

Furthermore, even if the high-temperature combustion catalyst layer 10 loses its activity over time due to the progress of the reforming reaction, the low-temperature combustion catalyst layer 11 can cause catalytic combustion, and the unburned matter will remain in the combustion exhaust gas 12. It is possible to reliably prevent this from remaining.

As described above, according to the reforming apparatus configured in this embodiment, the following effects can be obtained.

(a) Since the combustion catalyst is formed in two regions, the high temperature side 10 and the low temperature side 11, with the heat transfer packed bed 9 in between, the combustion catalyst is formed in two regions, the high temperature side 10 and the low temperature side 11. There is no need to form the catalyst layer 2 so as to cover the reaction catalyst layer 2, and the amount of combustion catalyst used can be reduced accordingly, making it possible to reduce costs.

(b) Since the outer position of the reforming reaction catalyst layer 2 of the reforming reaction tube 1 is removed to perform oxidative combustion using the combustion catalyst, the cause is non-uniformity in the packing density of the combustion catalyst as in the conventional case. This prevents the oxidation reaction from occurring locally, making it possible to reliably prevent the formation of hot spots and carry out the reforming reaction effectively.

(C) Since the raw material gas 5 introduced into the reforming reaction catalyst layer 2 inside the reforming reaction tube 1 is preheated by the inert heat transfer filler 3, the reforming reaction is carried out even more effectively. becomes possible.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be similarly implemented in the following manner.

(a) In the above embodiment, a case is described in which one reforming reaction tube is arranged inside the reformer container, but the invention is not limited to this, and multiple reforming reaction tubes are arranged inside the reformer container. It goes without saying that the present invention can be similarly applied to such cases.

(b) In the above embodiment, the exhaust air and flammable gas were mixed in advance and introduced into the reforming reaction tube 1.
The exhaust air and the combustible gas may be introduced separately into the reforming reaction tube 1 and mixed immediately before or inside the high-temperature combustion catalyst layer 10.

(C) In the above embodiment, the raw material gas 5 to be introduced into the reforming reaction catalyst 112 is preheated by being filled with the inert heat transfer filler 3, but the inert heat transfer filler 3 is omitted. It may be done as follows.

In addition, the present invention can be modified and implemented in various ways without changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, at least one reforming reaction tube, one end of which is sealed and a reforming reaction catalyst layer provided therein, is disposed inside the reformer container. A mixed gas of air with an oxygen concentration lower than that of air and a combustible gas is introduced from one end of the reforming reaction tube and flows out from the other end through the outside of the tube, and the raw material gas for reforming is introduced into the reforming reaction tube. The structure is such that the gas flows in from the other end of the reaction tube, passes through the reforming reaction catalyst layer, passes through the inner tube from one end, and flows out from the other end. Furthermore, a heat transfer filling is provided on the mixed gas introduction side outside the reforming reaction tube. A high-temperature combustion catalyst layer is formed through the layers, and a low-temperature combustion catalyst layer is formed on the mixed gas outflow side outside the reforming reaction tube, reducing the amount of combustion catalyst used and reducing costs. At the same time, it is possible to provide an extremely reliable reforming device that can reliably prevent the formation of hot spots due to non-uniformity in the charging of the combustion catalyst and effectively carry out the reforming reaction.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the reforming apparatus of the present invention, and FIG. 2 is a block diagram showing details of a reforming reaction tube in the same embodiment. 1... Reforming reaction tube, 2... Reforming reaction catalyst layer, 3...
- Inert heat transfer filler, 4... Mixed gas of exhaust air and combustible gas, 5... Raw material gas, 6... Inner tube, 7.
...Reformed gas, 8.. Plug pipe, 9.. Heat transfer packed bed, 10.. High temperature combustion catalyst layer, 11.. Low temperature combustion catalyst layer, 12.. Combustion exhaust gas.

Claims (1)

[Claims] At least one reforming reaction tube, one end of which is sealed and a reforming reaction catalyst layer provided inside, is disposed inside the reformer container, and air with a lower oxygen concentration than normal air and flammable A mixture of gases is introduced from one end of the reforming reaction tube and flows out from the other end through the outside thereof, and a raw material gas for reforming is introduced from the other end of the reforming reaction tube for reforming. The mixture gas is introduced from one end of the reaction catalyst layer through an inner tube and flows out from the other end thereof, and a high-temperature combustion catalyst layer is formed on the mixed gas introduction side outside the reforming reaction tube via a heat transfer packed bed. , and a low-temperature combustion catalyst layer is formed on the mixed gas outflow side outside the reforming reaction tube.