KR20100064138A - Catalytic combustor for molten carbonate fuel cell(mcfc) - Google Patents

Abstract

PURPOSE: A catalytic combustor for a molten carbonate fuel cell(MCFC) is provided to completely burn combustible gas inside blast furnace gas generating from the entrance of an anode of the MCFC, and to use the heat from the MCFC as a heating source of air. CONSTITUTION: A catalytic combustor(1) for a molten carbonate fuel cell(MCFC) combusting mixture gas containing air and blast furnace gas discharged from an anode of a fuel cell stack comprises the following: a gas supplying unit(2) including a pathway to separately supply the air and the blast furnace gas; a mixing unit(3) including a mixing divide with a venturi mixer function and a rob mixer function; a second mixing diffusion unit(4) including a diffusing pipe structure to supply the mixture gas to a flowing area; and a catalytic combustion unit(5) including a combustion catalyst layer(51). The catalytic combustion unit is installed on the entrance of the anode and a cathode.

Description

Stackable Direct Combustion Catalytic Combustion Device for MFC (CFC)

The present invention relates to a stack-type catalytic combustion device for MCFC, which will be described in detail. In the MCFC (molten carbonate fuel cell) system, a by-product gas such as hydrogen, carbon dioxide, carbon monoxide, water vapor, etc. off-gas) is generated. Among these by-product gases, hydrogen and carbon monoxide are high quality combustible gases that can be recovered and used as a heat source for the process. Therefore, a considerable amount of energy savings can be expected. Therefore, they occur at the anode exit side of molten carbonate fuel cell (MCFC). The present invention relates to a catalytic combustion device necessary for completely burning high quality combustible gases present in by-product gas, and recovering heat generated at this time, to be used as a heating heat source of air supplied to a cathode inlet side.

The catalytic combustion device technology for MCFC is already being developed in advanced countries such as Japan and the United States.

For example, Ishikawajima-Harima Heavy Industries Co. (IHI) in Japan is developing an externally modified MCFC with the support of NEDO. Catalytic combustor and mixer adopted by IHI are installed inside the vessel together with fuel cell stack, and heat generated from catalytic combustor is used as heat source of reformer.

Since IHI's catalytic combustor uses the hot gas obtained after catalytic combustion as a heat source of the reformer, the temperature of the catalytic combustion outlet gas must be maintained at or above the reforming temperature of the reformer to perform a smooth process. Therefore, in order to obtain an appropriate reforming conversion rate in the reformer of IHI, the temperature of the reforming catalyst bed should be 800 ° C. or higher, and the heat source at the outlet of the catalytic combustor should maintain a high temperature of 800 ° C. or higher. Accordingly, the catalyst in the catalytic combustor should use a catalyst having a durability at a high temperature of 800 ℃ or more. However, it is currently impossible to secure a product capable of safely operating for a long time to process the combustible gas containing a large amount of moisture at a high temperature of more than 800 ℃ among the combustion catalyst.

Next, FCE in the United States is developing an internally modified MCFC, and is commercializing a 250kW unit module and distributing it to the United States and other countries. FCE's catalytic combustor mixes the outlet gas at the anode side and the air required at the cathode side and supplies it to the catalyst layer, and as the combustible gas in the mixed gas is incinerated in the catalyst layer, the heat generated at this time is It is used to preheat the air. The outlet gas of the catalytic combustor is directly supplied to the inlet side of the cathode, and thus the combustion gas is adjusted to 550 to 600 ° C., which is the cathode inlet side temperature condition.

FCE has developed and used a venturi-type mixer to mix the by-product gas discharged from the anode side with external air in the patent US 6,902,840, and the air at the nozzle outlet where the air is ejected by using the venturi structure is used. The speed increases to the maximum and the pressure of the surroundings decreases, so that the by-product gas discharged from the anode side is naturally sucked. This has the advantage of minimizing the pressure difference between the anode side and the cathode side of the stack. However, the mixer still needs to be improved in the uniform mixing performance of anode side by-product gas and air by using a simple Venturi type.

An object of the present invention for solving the above problems is a new concept of a mixer structure to compensate for the technical problems of the structural problems of the mixer in the conventional MCFC catalyst combustion apparatus and the long-term performance improvement of the catalyst under high temperature by-product combustion The present invention provides a catalytic combustion device optimized for internal reforming of MCFC.

It is an object of the present invention to provide a catalytic combustion device for MCFC comprising a mixing device in which the supplied mixed gas and air mixed a venturi mixer function and a lobe mixer function.

The present invention, which achieves the object as described above and removes the drawbacks of the prior art, is a catalyst for MCFC that mixes and combusts by-product gas discharged from the anode side of the fuel cell stack and air supplied from the outside. In the combustion device,

 A gas supply section having a flow path through which the mixed gas and air at the anode side outlet are separately supplied;

A mixing section configured to provide a mixing device having a form in which the supplied mixed gas and air are mixed with a venturi mixer function and a lobe mixer function to uniformly mix;

A second mixed diffusion section formed in a tubular shape of a diffusion structure to supply the mixed gas and air primarily mixed in the mixing section to the catalyst layer in a completely uniform flow field;

It is composed of a catalytic combustion section which is equipped with a combustion catalyst layer for completely burning the mixed gas having a uniform concentration and uniform flow distribution after the secondary mixed diffusion section. It is composed of a direct connection between an anode outlet and a cathode inlet. It is achieved by providing a stack direct-type catalytic combustion device for MCFC, characterized in that installed in a mold manner.

The mixing device is characterized in that the center portion is formed in a gear-like structure in which a plurality of gear mountains are arranged so that the mixed gas passes through and the outside passes through the air.

The angle of the gear mountain is characterized in that it is configured to add a turn to a greater than minimum 0 degrees and a maximum 15 degrees in the rotation direction in the fluid flow direction (axial direction).

The catalyst layer installed in the catalytic combustion section is made of a honeycomb or a foam structure having a porous structure of ceramic or metal material, the outer shape is characterized in that installed in a square or circular frame.

The catalyst coated on the honeycomb or the foam structure having the porous structure of the ceramic or metal material is based on platinum (Pt), which is a precious metal catalyst, and palladium is added to the platinum (Pd) according to the type of mixed gas. It is used, characterized in that the coating amount is 0,5-2.0 wt%.

The composition ratio between the ion catalysts is characterized in that the component of palladium to platinum is 10 to 50wt%.

 The angle α of the diffusion structure of the diffusion section 4 is characterized in that 10 to 30 degrees.

The present invention solves the catalytic combustion technology of by-product gas at the anode side outlet, which is the core peripheral technology (BOP) of MCFC, and secures the unique technology of the catalytic combustion device of MCFC for internal reforming, It is believed that it is possible to secure an advantage in the export competitiveness, in particular, the mixing device, which is the core technology presented in the present invention, has a unique structure and excellent mixing, and thus is a useful invention that can be applied to other fields to obtain a uniform mixed gas. As such, the invention is expected to be greatly utilized in the industry.

In the present invention, a mixer (Mixer) for the catalytic combustion by uniformly mixing the by-product gas and air discharged from the anode (anode) side was developed. The mixer has a venturi mixer function that allows the inlet gas discharged from the anode to be sucked into the catalytic combustor without applying pressure, and a lobe mixer function that allows the byproduct gas and air to be effectively mixed in the shortest time. We developed a mixer with a unique structure that combines. The optimum design and performance evaluation of the mixer with the Venturi mixer and the lobe mixer were first obtained through the numerical analysis of the speed, mixing and temperature distribution. Subsequently, the mixer was manufactured and verified through measurement of pressure loss and concentration distribution of the mixed gas. Finally, a catalytic combustion experiment was developed for the MCFC through catalytic combustion experiments under normal operating conditions.

Hereinafter, the configuration and the operation of the embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a schematic view of the catalytic combustion device for MCFC according to the present invention and the structure of the catalyst layer mounted, Figure 2 is a perspective view showing a detailed view of the mixing device and the actual production of the mixing device of the catalytic combustion device for MCFC according to the present invention 3 is an overall process diagram of a catalytic combustion test apparatus for a catalytic combustion device for MCFC manufactured according to the present invention, and FIG. 4 is a catalytic combustion test result for each catalytic combustion device for MCFC manufactured according to the present invention. Figure 5 is a graph showing the temperature distribution, Figure 5 is a photograph showing the actual foreground of the catalytic combustion according to the amount of hydrogen supplied as a result of the catalytic combustion test for the catalytic combustion device for MCFC produced according to the present invention.

First, Figure 1 is a schematic diagram of the catalytic combustion device for MCFC according to the present invention is a structural diagram of the mounted catalyst layer, as shown in the present invention uniformly complete by-product gas discharged from the anode (anode) and air supplied from the outside It is a catalytic combustion device (1) for an internal reforming MCFC accompanied by a mixing device of an original structure that can be mixed. To this end, the internal combustion type MCFC catalytic combustion device 1 of the present invention is largely provided with a gas supply section 2, a mixing section 3, a secondary mixed diffusion section 4, and a catalytic combustion section ( The catalytic combustion device 1 for MCFC divided into 5) was comprised.

Specifically, the configuration of the present invention is connected to the anode (anode) side gas supply section (2) which is connected to the mixed gas 22 and the air 21 supplied through a separate blower is supplied to each flow path Wow; Mixing section 3 formed so that the supplied mixed gas 22 and air 21 have a unique mixing device 31 formed to combine the functions of the venturi mixer and the lobe mixer to be completely and uniformly mixed. Wow; A secondary mixed diffusion section 4 made of a pipe having a diffusion structure to supply the first mixed gas 22 and the air 21 to the catalyst layer in a completely uniform flow field; A catalyst combustion section 5 composed of a catalyst layer 51 designed to completely burn a mixed gas having a uniform mixed gas concentration and a uniform flow distribution. The mixed gas which has been burned in the catalyst layer is a cathode of the stack ( cathode) so that it flows directly to the inlet side.

The connection between the gas supply section (2), mixing section (3), secondary mixed diffusion section (4), catalytic combustion section (5) is to form a body by the usual connection, including the welding method Configure.

The reason why the mixing device has a venturi mixer function is that the flow direction is on the same axis, and the area ratio is different so that there is a pressure difference, and thus the venturi mixer structure has a lobe mixer function. Because.

 The angle α of the diffusion structure of the diffusion section 4 is between 10 and 30 degrees. The reason for the numerical limitation is that the reaction is fed to the catalyst bed in a completely uniform flow field at this angle.

Hereinafter, the configuration of the present invention in more detail.

In the mixing method by the mixing device 31 of the present invention, the mixing device 31 has a central portion penetrated therein, and the outer portion is processed into a gear shape and passes through the outside of the by-product gas and gear shape passing through the central portion. The air is configured to generate suction pressure on the anode side by the venturi mixer function and the lobe mixer function, and to simultaneously mix the by-product gas and air in the shortest time. The mixed gas 22 into which the gas is introduced passes through the center of the mixing device 31, and the air 21 supplied from the outside is primarily mixed while flowing out of the gear shape, and is secondary in a flow path having a diffusion structure. It is characterized by a principle of complete mixing. At this time, the gear-shaped front end portion is closed so that air passes through the valley between the gear mountain and the gear mountain.

In the gas supply section 2, the mixed gas 22 discharged from the anode side and the air 21 supplied from the outside are supplied by separating the flow paths until they reach the mixing device 31. In this case, the by-product gas discharged from the anode side of the MCFC stack is supplied through the internal flow path, and the air 21 is quantitatively supplied by the blower 61 (see FIG. 3) installed outside.

The mixed gas 22 on the anode side is composed mainly of hydrogen, carbon dioxide, water vapor, and carbon monoxide, of which hydrogen and carbon monoxide can be used again as a combustible fuel of good quality. The mixed gas 22 and the air 21 thus supplied flow independently without being mixed until just before the initial inflow into the secondary diffusion section 4 through the mixing device 31.

The mixing device 31 has a center portion penetrated, and the outer portion is processed into a gear shape so that the gas passing through the center portion and the gas passing through the outside portion of the gear form a combination of a venturi mixer function and a lobe mixer function. In the present invention, the mixed gas 22 supplied from the anode passes through the center of the mixing device 31, and the air 21 flows into the outside of the gear shape to be primarily mixed. It was designed to be.

Figure 2 shows a detailed view of the mixing device 31 of the catalytic combustion device for MCFC according to the present invention having the principle as described above and the foreground of the actual production of the mixing device.

As shown, the mixing device 31 can be seen that the outside is processed into a gear shape, the height and number of the gears to the mixed gas 22 line by the high-speed flow of air 21 in accordance with the Venturi mixer function The suction pressure is generated and at the same time, the mixed gas 22 and the air 21 are selected to be effectively mixed in accordance with the lobe mixer function.

The shape of the gear mountain 32 also allows the angle β in the axial direction to be greater than minimum 0 degrees and eccentric to a maximum of 15 degrees to add a turning function during the flow of the mixing device. That is, it has a spiral cylindrical gear like a helical gear. The reason for limiting the upper limit to 15 degrees is that if the angle is too large, the linear velocity direction of the mixed gas flow may fluctuate too much to the left and right to form a flow field unsuitable for catalytic combustion.

As the mixed gas 22 and the air 21 passing through the mixing device 31 enter the secondary mixing diffusion section 4, the initial primary mixing proceeds. Therefore, the degree of mixing at the end of the mixing device 31 where the primary mixing starts is difficult to expect a satisfactory uniform mixing, the concentration of the mixed gas 22 to the air 21 is the largest in the center, the most outside the tube It has a small distribution. However, as the secondary mixing diffusion section 4 proceeds, the mixing degree gradually improves, and as the closer to the catalytic combustion section 5, the uniform mixing degree is maintained.

While the mixed gas 22 and the air 21 pass through the secondary mixed diffusion section 4, the degree of mixing is greatly improved. The uniformly mixed gas includes the catalyst burner section equipped with the catalyst layer 51 ( While passing through 5), combustible gases (hydrogen, carbon monoxide) contained in the mixed gas 22 are completely burned.

The shape of the catalyst layer 51 used in the present invention is such that the porous catalyst layer having a honeycomb structure or a foam structure as shown in FIG. 1 is installed in a frame having a square or circular shape, and the material is made of both metal and ceramic materials. It can be used.

The catalyst used in the catalyst layer is based on a platinum (Pt) catalyst, a noble metal catalyst that exhibits excellent performance in the oxidation reaction between hydrogen and carbon monoxide, and is based on a binary catalyst in which palladium (Pd) is partially added depending on the components of by-product gas. It can be used. In the case of binary catalysts, the palladium content in platinum is 10 to 50wt%. The reason for the numerical limitation is that if it is less than 10, the effect is insignificant and there is no added meaning, and if it is larger than 50, the performance of the platinum catalyst is degraded.

 The amount of the catalyst supported on the ceramic honeycomb or the metal support was 0.5 to 2 wt%. The reason for the numerical limitation is that if the amount of the catalyst is too large, the unit price increases not only, but also the reactivity is too good, and thus adversely affects. On the contrary, if the amount of the catalyst is too small, the activity may be so bad that unburned phenomenon may occur. Because. Therefore, the above range is most suitable in the present invention.

Figure 3 shows an overall process diagram for the apparatus produced for the catalytic combustion test as an embodiment of the catalytic combustion device for MCFC manufactured according to the present invention.

In the catalytic combustion test apparatus, hydrogen 74, carbon monoxide 75, and carbon dioxide 76 gas are supplied under the same conditions as by-product gas discharged from the anode side of the MCFC system which is actually operated. Designed to be controlled by flowmeters 77-79. In this case, the carbon dioxide 76 is vaporized by the heated vaporizer 80 using the liquid carbon dioxide 76 is adopted. The gas supplied as above is completely mixed by the static mixer 67 and finally controlled by the flowmeter 65. The mixed gas 22 thus supplied is heated to a maximum temperature of 600 degrees by the first heat exchanger 84 and supplied to the final catalytic combustion device 1. The heat necessary for heat exchange of the first heat exchanger 84 is generated by the burner 83, and the burner 83 uses a burner that uses LPG 81, which is automatically supplied with air, as a fuel. In addition, the water vapor component in the anode side mixed gas was separately supplied using a superheated steam boiler (89). Air is supplied by the air blower 61 and controlled by the flow meter 64, in which a second heat exchanger 85 is installed to maintain the temperature conditions of the air finally supplied to the catalytic combustion device 1. The heat required for the second heat exchanger 85 was supplied by the amount of heat bypassed in the burner 83 and the amount of heat remaining in the first heat exchanger 84.

Each of the gas and air supplied as described above is finally controlled by the valves 68, and the situation in which the combustion in the catalyst layer 51 of the catalytic combustion device 1 is carried out in the observation window 86 installed in parallel with the catalyst layer. Was observed.

In Fig. 3, reference numeral 66 is a pressure gauge, 69 is a sampling hole, 87 is LPG for a boiler, 88 is a LPG flow meter for a boiler, 90 is a water flow meter, and 91 is a thermocouple. Many)

Figure 4 is an embodiment of the catalytic combustion device for MCFC manufactured according to the present invention, the results of catalytic combustion test, shows the temperature distribution for each part of the system.

In the figure, the "1" step on the X-axis shows the temperature distribution when the carbon dioxide was operated while supplying only 18 m ³ / h. In this state, steam was not supplied yet, so it was measured at room temperature. The temperature at the air inlet side (the second heat exchanger outlet) was about 150 degrees, the temperature at the anode by-product gas inlet side (the first heat exchanger outlet) was around 550 degrees, and the temperatures at the front and rear stages of the catalyst bed were 270 degrees and 250 degrees, respectively.

When the burner burner 89 was operated in this state, it was confirmed that the temperature of the steam boiler side showed a temperature close to 600 degrees in the "2" stage.

When 3.8 m ³ / h and 1.8 m ³ / h of the combustible gases hydrogen and carbon monoxide were supplied in the step “3”, respectively, the temperature of the rear end of the catalyst layer increased rapidly than the shear temperature, indicating a temperature distribution close to 550 degrees. This temperature is comparable to the temperature of the mixed gas 22 supplied from the anode side.

When only the amount of hydrogen again increased to 4.0 ~ 4.5 m ³ / h as a "4" step, the temperature of the rear end of the catalyst layer was further increased to show 650 degrees.

 FIG. 5 is an embodiment of a catalytic combustion device for MCFC manufactured according to the present invention, and shows an actual foreground of catalytic combustion according to the amount of hydrogen supplied as a result of catalytic combustion test.

(A) and (b) in FIG. 5 are results for the case where the amount of hydrogen is 2.0 and 3.8 m ³ / h, respectively, and the amounts of carbon dioxide, carbon monoxide, water vapor and air, which are the remaining gases on the anode side, are respectively 18 equal to m ³ / h, 1.8 m ³ / h, 1.6 m ³ / h, 100 m ³ / h. In the figure, it was confirmed that the catalytic combustion of the combustible gas occurred uniformly under both conditions.

In addition, as a result of analyzing the mixed gas combusted through the catalytic combustion, the hydrogen and carbon monoxide components were completely incinerated and thus were not detected at all. It was completely incinerated and confirmed that the heat was used to raise the temperature of the air supplied at room temperature.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a schematic diagram of a catalytic combustion device for MCFC according to the present invention is a structural diagram of the catalyst layer mounted,

Figure 2 is a perspective view showing a detailed view of the mixing device and the actual production of the mixing device of the catalytic combustion device for MCFC according to the present invention,

3 is an overall process diagram of a catalytic combustion test apparatus for a catalytic combustion device for MCFC manufactured according to the present invention,

Figure 4 is a graph showing the temperature distribution of each part of the catalytic combustion test results for the catalytic combustion device for MCFC produced according to the present invention,

Figure 5 is a photograph showing the actual foreground of the catalytic combustion according to the amount of hydrogen supplied as a result of the catalytic combustion test for the catalytic combustion device for MCFC produced in accordance with the present invention.

<Description of the symbols for the main parts of the drawings>

(1): Catalytic combustion device for MCFC (2): Gas supply section

(3): Mixing section (4): Secondary mixing diffusion section

(5): catalytic combustion section 21: air

(22): mixed gas (31): mixing device

32: gear mountain 52: frame

(61): Blower for air supply 64: Flow meter for air supply

65: flow meter for mixed gas supply 66 pressure gauge

(67): static mixer

68: valve 69: sampling hole

(74): hydrogen gas (75): carbon monoxide gas

(76): carbon dioxide gas

(77, 78, 79): Mixed gas flow meter (hydrogen, carbon monoxide, carbon dioxide)

(80): Taso dioxide vaporizer (81): LPG for burner

(82): LPG flowmeter for burner (83): Burner

(84): first heat exchanger (85): second heat exchanger

(86): Catalytic combustion observation window (87): LPG for boiler

(88): LPG flow meter for boiler (89): steam boiler

90: water flow meter 91: thermocouple

Claims (7)

In the catalytic combustion device for MCFC for mixing and burning by-product gas discharged from the anode side of the fuel cell stack and air supplied from the outside,  A gas supply section having a flow path through which the mixed gas and air at the anode side outlet are separately supplied; A mixing section configured to provide a mixing device having a form in which the supplied mixed gas and air are mixed with a venturi mixer function and a lobe mixer function to uniformly mix; A secondary mixed diffusion section formed in a tubular shape of a diffusion structure to supply the mixed gas and air primarily mixed in the mixing section to the catalyst layer in a completely uniform flow field; It is composed of a catalytic combustion section which is equipped with a combustion catalyst layer for completely burning the mixed gas having a uniform concentration and uniform flow distribution after the secondary mixed diffusion section. It is composed of a direct connection between an anode outlet and a cathode inlet. Stack direct-attached catalytic combustion device for MCFC, characterized in that installed in the type system. In claim 1, Wherein the mixing device is a stack direct connection type catalytic combustion device for MCFC, characterized in that the center is formed of a gear-like structure in which a plurality of gear mountains are arranged so that the mixed gas passes through the outside. In claim 2, The angle of the gear peak is larger than the minimum 0 degrees in the direction of rotation in the fluid flow direction (axial direction) and the stack direct connection type catalytic combustion device for MCFC, characterized in that configured to add a maximum of 15 degrees. In claim 1, The catalyst layer installed in the catalytic combustion section is made of a honeycomb or a foam structure having a porous structure of ceramic or metal material, the appearance is a direct stack type catalytic combustion device for MCFC, characterized in that installed in a square or circular frame. In claim 4, The catalyst coated on the honeycomb or the foam structure having the porous structure of the ceramic or metal material is based on platinum (Pt), which is a precious metal catalyst, and palladium is added to the platinum (Pd) according to the type of mixed gas. And a coating amount of 0,5-2.0 wt%. In claim 5, The composition ratio between the ionic catalyst is a stack direct connection type catalytic combustion device for MCFC, characterized in that the component of palladium to platinum 10 to 50wt%. In claim 1,  Stack direct connection type catalytic combustion device for MCFC, characterized in that the angle (α) of the diffusion structure of the diffusion section (4) is 10 to 30 degrees.

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