JPS6317202A - Catalytic combustion heating apparatus - Google Patents

Abstract

PURPOSE:To provide the titled compact and high-performance apparatus enabling uniform combustion, by inserting a fuel supply pipe having plural multi-hole nozzles into a combustion catalyst layer and providing a number of protrusions to the outer surface of the tube at intervals narrower than the diameter of the surrounding filled particle. CONSTITUTION:A gaseous fuel containing plural combustible components is catalytically burnt in the presence of an oxidation catalyst. In the above apparatus, a fuel supply tube 4 having plural nozzle holes 16 is inserted in a combustion catalyst layer and a number of protrusions 17 are attached to the outer surface of the fuel supply tube 4 at intervals narrower than the diameter of the surrounding filled particles 2. A space having high void ratio is formed around the supply tube 4 corresponding to the height of the protrusion attached to the fuel supply tube and the fuel ejected from the nozzle hole 16 is spread in the space and then distributed into the surrounding combustion catalyst layer. Accordingly, the fuel dispersion can be uniformized, the influence of the configuration (pitch and diameter) of the nozzle holes 16 on the temperature distribution can be reduced and the blocking of the nozzle hole 16 can be prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel reformer that generates hydrogen by steam reforming alcohol or hydrocarbon fuel, and is particularly applicable to fuel cells and semiconductors. The present invention relates to a combustion heating device suitable for on-site pure hydrogen production equipment used in manufacturing and the like.

[Conventional technology]

Conventional fuel reformers, as typified by the example of JP-A-53-78983, fill a reaction tube with a reforming catalyst to form a reforming catalyst layer, and then burn the reaction tube from the surroundings. The main method was external heat heating using gas or heat medium. In this conventional method, the reaction section with a large number of reaction tubes and the combustion section for obtaining combustion gas to heat the reaction tubes and high-temperature heat medium are independent, so it is necessary to secure a flow path for the heating medium. there were. For this reason, the volume of the reformer becomes large, making it unsuitable for small-sized equipment. On the other hand, recent fuel reformers are small,
Higher performance is required. In order to meet this demand,
A reformer of a type that can heat adjacent to a reaction section using catalytic combustion has been devised, as exemplified in Japanese Patent Application Laid-Open No. 59-18102.

In such a catalytic combustion system, the combustion of the supplied fuel is carried out through contact with the combustion catalyst, so local heating is likely to occur.In order to eliminate this and obtain a uniform heating temperature, it is necessary to equalize the fuel supply. However, in the conventional example, the fuel distribution method and the structure of the fuel supply pipe have not been considered.

[Problem that the invention seeks to solve]

In the catalytic combustion type fuel reformer according to the prior art described above, a combustion section supporting a combustion catalyst adjacent to the reforming section is used as a flow path for the supplied fuel. Therefore, the fuel supplied from the inlet burns while contacting the combustion catalyst supported in the flow path, and the generated combustion gas is discharged from the outlet. However, most of the exothermic reaction due to combustion during this period is completed near the fuel inlet, resulting in a very high temperature near the inlet. As a result, thermal deterioration of the combustion catalyst is accelerated, and furthermore, the state of heat transfer to the reforming catalyst layer becomes non-uniform, making it impossible to sufficiently supply the heat necessary for the reforming reaction, leading to a reduction in the reaction rate.

In addition, in a reformer that uses methanol as a raw material, the temperature of the reforming catalyst layer is 250 to 300°C, which is lower than the temperature of the combustion section, so local combustion in the combustion section leads to local heating of the reforming reaction section. , promotes thermal deterioration of the reforming catalyst.

An object of the present invention is to provide a compact and high-performance catalytic combustion heating device that distributes the fuel supply during fuel supply and enables uniform combustion in order to uniformly heat the catalyst layer in a catalytic combustion reformer. It is about providing.

[Means for solving problems]

The above purpose is to distribute the fuel supplied to the combustion catalyst layer in a catalytic combustion heating device and to obtain a uniform combustion state, by inserting a fuel supply pipe with multiple porous nozzles into the catalytic combustion layer. on the outer surface of.

This is achieved by providing a large number of protrusions at a pitch smaller than the diameter of surrounding packed particles such as combustion catalysts. Further, this can be achieved by making the fuel supply pipe a seepage type having no nozzle holes and made of a porous material with air permeability.

[Effect]

Dividing the fuel supplied to the combustion catalyst layer by multiple fuel supply pipes reduces the amount of heat generated per unit amount of catalyst when the supplied fuel contacts and reacts with the combustion catalyst, and moreover, the heat generation position is Since the fuel is dispersed in the catalyst layer for each divided fuel supply pipe, it has the effect of making the temperature of the combustion part, which is the heating side, uniform. Furthermore, since the amount of fuel to be supplied can be partially adjusted depending on the amount of heat absorbed by the reforming catalyst layer, temperature controllability for obtaining uniform temperature distribution is improved.

Further, the protrusions provided on the outer surface of each fuel supply pipe have the effect of creating a space near the fuel supply pipe that has larger voids than the filling layer formed by the surrounding combustion catalyst and the like. Due to this, the fuel ejected from the nozzle hole of the fuel supply pipe is dispersed in the gap around the supply pipe, and mixing between the fuels ejected from each nozzle is promoted. As a result, it is effective in suppressing local combustion occurring in the combustion catalyst layer near the nozzle hole and creating a uniform temperature distribution.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIG. 1. In this embodiment, a case where the present invention is applied to a reformer using methanol as a raw material will be described. A copper-zinc catalyst is used as the reforming catalyst 1, and a palladium catalyst is used as the combustion catalyst 2.

The catalyst layer formed by these catalysts is one in which the reforming catalyst layer and the combustion catalyst layer are arranged alternately through the partition wall 2, and the entire plate heat exchanger type reformer has a laminated structure. Assuming that the amount of hydrogen produced is approximately 8 ONm'/h, the required amount of reforming catalyst is approximately 6012 mm, and if the thickness of each layer is set to 40 m, the thickness of the catalyst layer including the combustion catalyst layer is Size 250+nw, width 600■, height 85
It becomes 0m. Furthermore, the entire casing 14 including the header section, heat insulating material 15, etc. is approximately 500X750X.
The size will be 1200+m. When a reformer of this scale is used for a fuel cell, it corresponds to a system of approximately 70 KW class. This is a compact device that is several minutes smaller than a conventional reaction tube type reformer.

The operation of this embodiment will be explained below. In this reformer, the reforming raw material 5 is converted into methanol and steam by S on the reforming section side.
/C (steam/carbon ratio)=1.5, and is supplied from the raw material supply header 10 in a vaporized state. The reforming raw material supplied to this header is formed into a honeycomb-shaped catalyst support plate 9.
and enters each reforming catalyst layer. In the reforming catalyst layer, the reforming reaction proceeds as the heat generated in the adjacent combustion catalyst layer is received.

This modification reaction takes place at about 300°C. Here, methanol, which is a raw material, becomes a reformed gas containing hydrogen as a main component, and the reformed gas is collected in the ladder 11, and the generated reformed gas is taken out from the reformed gas take-off pipe 13. This reformed gas is used as a fuel for a fuel mold section or as a raw material for a PSA' device to obtain high-purity hydrogen, depending on the purpose. On the other hand, on the combustion section side, heating fuel 7 is supplied to the combustion catalyst layer through each fuel supply pipe. Generally, a part of the reformed raw material is used as fuel, but off-gas etc. discharged from a device combined with a reformer can also be used as fuel. For example, in a system combined with a fuel cell, exhaust gas containing unreacted hydrogen discharged from the cell anode can be used as fuel. However, it is preferable for uniform combustion that the fuel used in catalytic combustion be used as a premixed fuel that has been mixed with combustion air in advance.In this embodiment, the fuel 7 is also supplied premixed with air. In particular, the fuel supplied to the combustion catalyst layer from the fuel supply pipe, which does not require an air supply system to the combustion section, undergoes a combustion reaction by contacting with the combustion catalyst filled around the supply pipe.

Since heat generation due to combustion occurs near each fuel supply pipe, in this embodiment, three locations per catalyst layer become heat generation sources. The flow of combustion gas flows upward from below the catalyst layer in the same manner as the flow of the raw material on the reforming side, and after leaving the catalyst layer, it is discharged from the combustion gas exhaust pipe 12 to the outside of the apparatus. A feature of the present invention is that in this combustion section, a large number of protrusions are provided on the fuel supply pipe inserted into the combustion catalyst layer. FIG. 2 shows the detailed structure of the fuel supply pipe shown in the embodiment shown in FIG. 1. The fuel supply pipe is provided with a plurality of nozzle holes 16 for ejecting fuel. Also.

A large number of needle-shaped protrusions 17 according to an embodiment of the present invention are provided on the outer surface of the supply pipe. This fuel supply pipe structure creates a space with a large gap around the supply pipe by the height of the protrusion.

Therefore, the fuel ejected from the nozzle hole fills the void formed by the protrusion around the supply pipe, and then disperses into the surrounding combustion catalyst layer. As a result, when using conventional fuel supply pipes without protrusions, it was difficult to supply fuel between the nozzle holes, resulting in localized combustion where only the vicinity of the nozzle holes became hot. According to the invention, fuel can be uniformly distributed from the fuel supply pipe to the combustion catalyst layer, and the influence of nozzle hole arrangement (pitch, hole diameter) on temperature distribution can be reduced. In addition, since the fuel supply pipe is provided with a protrusion, particles around the fuel supply pipe may cause damage to the fuel supply pipe. 1O17[□I, 7. . 6. Providing the protrusion prevents surrounding particles from coming into direct contact with the fuel supply pipe, thereby eliminating the possibility of clogging the nozzle hole. As described above, as another example of a protrusion structure that enhances the function of distributing the a-material in a fuel supply pipe having a nozzle hole, a plate-shaped protrusion 1 shown in FIG.
A structure with 8 is considered. This is a fuel supply pipe in which a disk-shaped plate is attached perpendicularly to the axial direction of the supply pipe. However, in this case, the intervals between the attached plates must be smaller than the diameter of the surrounding particles. In addition, a perforated plate with a large number of holes is used for the plate used to improve the flow of fuel between the nozzle holes. The larger the aperture ratio of this plate, the better the fuel dispersibility. The strength of the protrusion provided on the fuel supply pipe may be such that it will not be crushed by the pressure due to the weight of the surrounding filling particles. For this reason, it is usually made of a metal material such as stainless steel, like the supply pipe. Figure 4 shows an example in which the fuel supply pipe is made into a thin plate in the reformer of the example shown in Figure 1, focusing on one combustion catalyst layer. 6 Features of this Example The thickness of the fuel supply pipe is 1/4 to 115 compared to the thickness of the combustion catalyst layer.
The reason is that it has a thin plate-like thickness. The details are shown in FIG. The cross section is rectangular, and a baffle plate 19 is arranged inside. The nozzle hole is attached to the lower surface of the supply pipe, and the protrusion according to the invention is also attached only to the lower surface. Fuel is supplied as shown by the arrow, flows along the baffle plate, is folded back at the tip of the supply pipe, and is ejected from each nozzle hole below.In the fuel supply pipe of this embodiment, while the supplied fuel flows inside the pipe, Easy to preheat. This is because the fuel flow path is long due to the baffle plate, and because it has a thin rectangular structure, it has a large unit cross-sectional area and a large circumferential surface area, making it easy to transfer heat from the surroundings. For this reason, since fuel that is not preheated is supplied to the combustion catalyst layer from the conventional fuel supply pipe, the combustion temperature rises slowly after the fuel is supplied. Further, near the fuel supply pipes in the second and subsequent stages, it acts to temporarily cool the high-temperature gas generated in the first stage upstream.

For this reason, as shown in the temperature distribution in FIG. 4, in the conventional system supply pipe, the temperature nonuniformity on the outer surface of the combustion catalyst layer is large. However, the reformer using the thin plate-shaped fuel supply pipe according to the present invention Now we have an improved, more even temperature distribution. Note that the fuel dispersion effect by the protrusions is the same as in the previous embodiment. FIG. 6 shows an embodiment in which a thin plate fuel supply pipe is provided with an edge.

The internal structure of the fuel supply pipe is of the type provided with a baffle plate, similar to the embodiment shown in FIG. The nozzle holes are provided on both sides of the edge portion, and the protrusions are also provided on the edge surface where the nozzle holes are located. Therefore, the fuel is evenly distributed to the left and right sides of the supply pipe, and the combustion temperature distribution can also be made uniform by supplying a uniform amount of fuel to the left and right sides.

Furthermore, in this embodiment, since the downstream side of the nozzle (the upper part of FIG. 6) also has an edge-shaped cross-sectional structure, the fuel ejected left and right from the nozzle flows along the supply pipe.

They merge smoothly at the edge of the wake. Therefore, even in the combustion catalyst layer located immediately downstream of the supply pipe, there is no stagnation of the supplied fuel and there is sufficient contact, so that a good combustion state can be obtained.

A few examples of plate heat exchange type reformers have been described above, in which a protrusion is provided on a fuel supply pipe having a nozzle hole to achieve uniform combustion. Furthermore, considering that the nozzle hole is small and the fuel supply pipe is installed in countless numbers, the influence of clogging of the nozzle hole by surrounding particles is small. This is an example in which the material is made of porous material. In this case, the fuel is ejected from the entire surface of the supply pipe and is supplied to the combustion catalyst layer. Therefore, unlike conventional fuel supply pipes with nozzle holes, the nozzle position does not affect unevenness during fuel dispersion, and a uniform temperature distribution in the heated portion without local heating can be obtained.

FIG. 7 shows an embodiment of the fuel reformer in which a static mixer 20 is arranged downstream of the fuel supply pipe provided with a protrusion in the fuel reformer of the embodiment shown in FIG. One such static mixer is shown in FIG. 8, for example. This mixer is made up of a circular pipe 21 in which several stages of deflection plates 22 with different twist directions are attached in alternating directions, which are bundled and arranged along the length of the fuel supply pipe. . This static mixer can obtain a mixing state according to the number of drift plates just by passing the gas.
For example, in the example shown in FIG. 8, five drift plates are used, and the gas that has passed through the mixer is theoretically divided into 12 parts and mixed.

By arranging such a mixer downstream of the fuel supply pipe as shown in Fig. 7, a portion of the fuel ejected from the fuel supply pipe enters the mixer with the combustion gas and excess air generated upstream. While passing through, the mixture is mixed and supplied to the combustion catalyst layer. Therefore, in the downstream of the combustion catalyst layer, the concentration of the supplied fuel is mixed with non-flammable gas before it comes into contact with the catalyst layer, and the calorific value of the fuel per unit volume is reduced, making it possible to suppress the degree of heating caused by local combustion. . Furthermore, since this embodiment has a fuel mixing section within the combustion catalyst layer, even if non-premixed fuel is supplied from the supply pipe and combustion air is supplied by another supply system, the premixed fuel is not mixed in the combustion catalyst layer. It will be similar to combustion.

Furthermore, the present invention is not limited to a heating device for a fuel reformer as in the embodiments, but can also be used as a home heater or a catalytic combustor such as a gas turbine combustor. .

〔Effect of the invention〕

According to the present invention, it is possible to improve the distribution and dispersibility of fuel supplied from the fuel supply pipe to the combustion catalyst layer.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is a sectional view of the fuel supply pipe in Fig. 1, Fig. 3 is a sectional view of the fuel supply pipe, and Fig. 4 is a combustion catalyst layer of the present invention. FIG. 5 and FIG. 6 are cross-sectional views of the fuel supply pipe according to the present invention, FIG. 7 is a cross-sectional view of the present invention, and FIG. 8 is a static view of the embodiment shown in FIG. 7. FIG. 3 is a cross-sectional structural diagram of a mold mixer. Figure 2 (α) No. 30 B-1 (ku) No. S opening (cL)

Claims (1)

[Claims] 1. In a combustion device that catalytically combusts a gaseous fuel containing a plurality of combustible components in the presence of an oxidation catalyst containing an oxidation active component, a combustion catalyst layer filled with the oxidation catalyst, In order to supply the gaseous fuel, a plurality of fuel supply pipes each having a porous nozzle are arranged in the combustion catalyst layer, and a large number of protrusions are arranged on the outer surface of the fuel supply pipe at intervals smaller than the diameter of the surrounding packed particles. A catalytic combustion heating device characterized by being provided with. 2. In claim 1, a needle-like protrusion is provided on the outer surface of the fuel supply pipe by welding a wire rod or machining the fuel supply pipe. Catalytic combustion heating device. 3. The catalytic combustion according to claim 1, characterized in that the outer surface of the fuel supply pipe is provided with a plate-like protrusion in which a porous flat plate or a net-like flat plate is attached in the shape of a fin. heating device. 4. The catalytic combustion heating device according to claim 1, wherein the fuel supply pipe is made of a breathable material. 5. The catalytic combustion heating device according to claim 1 or 4, characterized in that a static mixer is disposed downstream of the fuel supply pipe. 6. Two layers consisting of a reforming catalyst layer filled with a catalyst for reacting hydrocarbon fuel with water vapor and a combustion catalyst layer filled with a combustion catalyst for heating the reforming catalyst layer by catalytic combustion. Claim 1 or 5 is characterized in that the fuel reformer is used as a heating part in a plate heat exchange type fuel reformer in which a plurality of stages are arranged alternately through partition walls.
The catalytic combustion heating device described in .