JP2006233011A - Fuel gas treating equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fuel gas treating equipment advantageous in the ignition capability and improvement of combustion in the catalytic combustion section. <P>SOLUTION: The fuel gas treating equipment is equipped with the gas supply section 2 which supplies the fuel gas which may contain carbon monoxide and the catalytic combustion section 5 which has the catalyst 5c and subjects the fuel gas to oxidation reaction by the catalyst 5c. The equipment is equipped with the carbon monoxide reduction section by which the carbon monoxide contained in the fuel gas before the supply for the catalytic combustion section 5 is reduced, the fuel gas is purified and the ignition capability in the catalytic combustion section 5 is enhanced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel gas processing apparatus including a catalytic combustion unit having a catalyst for oxidizing a fuel gas with a catalyst.

2. Description of the Related Art Conventionally, a fuel gas processing apparatus having a gas supply unit that supplies fuel gas and a catalyst combustion unit that has a catalyst and oxidizes the fuel gas with the catalyst is known. Patent Document 1 discloses a technique for reacting methanol with H ₂ O to generate a reformed gas containing hydrogen and carbon monoxide (hereinafter also referred to as CO). This discloses a technique for catalytically combusting a combustible gas containing CO with a catalyst component in a heat exchanger provided upstream of the reforming section. This document describes that PdO and Pt are effective as catalyst components.
Japanese Patent Laid-Open No. 2003-081687

  By the way, in the fuel gas processing apparatus described above, the fuel gas may contain CO gas. In this case, if the concentration of the CO gas is increased, CO is adsorbed on the catalyst in the catalytic combustion section, so that ignitability and combustibility are hindered. Even if the temperature of the catalytic combustion section is increased, the ignitability and combustibility of the catalytic combustion section are hindered. If fuel gas containing CO gas is supplied to the catalytic combustion section without igniting the catalytic combustion section, CO gas is excessively adsorbed to the catalytic combustion section, which makes the catalytic combustion section more difficult to ignite. .

  Moreover, the above-described Patent Document 1 discloses a reformer including a heat exchanger having a function as a catalytic combustion unit that performs catalytic combustion. However, although the above-mentioned Patent Document 1 describes that PdO and Pt are effective as catalyst components for a fuel gas containing CO gas, the ignitability in the catalytic combustion section is reduced by reducing CO gas. No mention is made of measures for improving the stability of combustion.

  This invention is made | formed in view of the above-mentioned actual condition, and makes it a subject to provide the fuel gas processing apparatus advantageous for the improvement of the ignitability of a catalyst combustion part, and combustibility by reducing CO gas.

  A fuel gas processing apparatus according to aspect 1 includes a gas supply unit that supplies a fuel gas that may contain carbon monoxide, and a catalyst combustion unit that has a catalyst and causes the fuel gas to undergo an oxidation reaction with the catalyst. The apparatus includes a carbon monoxide reduction unit that reduces carbon monoxide contained in the fuel gas before being supplied to the catalyst combustion unit and improves ignitability in the catalyst combustion unit. is there.

  According to the fuel gas processing apparatus of the present invention, the carbon monoxide contained in the fuel gas before being supplied to the catalytic combustion unit is reduced by the carbon monoxide reducing unit, and before being supplied to the catalytic combustion unit. Purify the fuel gas. For this reason, it is suppressed that carbon monoxide adsorb | sucks excessively to a catalyst combustion part, and the ignitability and combustibility in a catalyst combustion part can be improved.

  The fuel gas processing apparatus according to aspect 2 is characterized in that activation promoting means for accelerating the time required for the temperature of the carbon monoxide reducing unit to reach the activation temperature region at the time of startup is provided. . Even at the time of start-up, the time for the temperature of the carbon monoxide reducing portion to reach the activation temperature region can be promoted by the activation promoting means.

  According to the fuel gas processing apparatus of the present invention, the carbon monoxide contained in the fuel gas before being supplied to the catalytic combustion unit is reduced by the carbon monoxide reducing unit, and before being supplied to the catalytic combustion unit. Purify the fuel gas. For this reason, it is suppressed that carbon monoxide is adsorbed excessively on the catalyst in the catalytic combustion section, and the ignitability and combustibility in the catalytic combustion section can be improved even when the temperature of the catalytic combustion section is low.

  The fuel gas processing apparatus includes a gas supply unit that supplies a fuel gas that may contain carbon monoxide, a catalyst combustion unit that has a catalyst that causes the fuel gas to undergo an oxidation reaction with a catalyst, and a carbon monoxide reduction unit. The fuel gas can be exemplified by a form in which hydrogen is a main component (for example, 10 mol% or more) and a gas that can contain carbon monoxide. Hydrogen has the properties of low specific gravity and viscosity, high diffusion coefficient, excellent low temperature ignitability and low temperature flammability, high combustion speed, and generation of moisture by combustion. The carbon monoxide reduction unit purifies the fuel gas by reducing the carbon monoxide contained in the fuel gas before being supplied to the catalytic combustion unit. This enhances the ignitability in the catalytic combustion section.

As the carbon monoxide reduction unit, the concentration of CO in the fuel gas is reduced. The carbon monoxide reduction unit includes a CO first reduction unit that reduces the concentration of carbon monoxide contained in the fuel gas, and a CO second reduction unit that further reduces the concentration of carbon monoxide contained in the fuel gas. Can have. One of the CO first reduction unit and the CO second reduction unit can exemplify a method of reducing CO by reacting CO with H ₂ O. The other of the CO first reduction unit and the CO second reduction unit can exemplify a method of reducing CO by reacting CO and O ₂ .

  Examples of the catalytic combustion unit include a configuration in which the carbon monoxide reduction unit is disposed upstream of the carbon monoxide reduction unit so as to warm up. Since the carbon monoxide reduction part is warmed up at the time of start-up, it is advantageous for the carbon monoxide reduction part to reach the activation temperature region early. The catalytic combustion unit is disposed in communication with the gas supply unit, and carries a catalyst that oxidizes the fuel gas with the catalyst. Catalytic combustion is combustion in which a fuel gas component and oxygen are oxidized in the presence of a catalyst. In many cases, combustion is performed in a form of flameless combustion (in some cases, flammable combustion), and no catalyst is used. Compared to normal combustion, the combustion start temperature and the combustion temperature are low. Even when the gas composition varies, the ignitability and combustibility can be stabilized. Flameless combustion refers to a form of oxidation combustion in which the flame is not visually visible. Examples of the catalyst used include at least one of white metal metals such as platinum, rhodium, palladium, ruthenium, iridium and osmium, or metal oxides including nickel, cobalt, iron, manganese, chromium and silver. it can. The catalyst may be supported on a carrier. The carrier may be a pellet carrier or a monolith carrier. The catalytic combustion section may warm up the carbon monoxide reduction section.

  The gas supply unit described above may exemplify a form having a reforming unit body that reforms a reforming raw material to generate reformed gas as a fuel gas, and a combustion unit that heats the reforming unit body by combustion. it can. In this case, examples of the carbon monoxide reduction unit include a configuration in which heat transfer from the reforming unit main body and / or the combustion unit is transmitted to a position where heat can be transmitted. In this case, the carbon monoxide reduction unit can reach the activation temperature region at an early stage even at the time of start-up, which can contribute to reducing the CO concentration of the fuel gas.

  According to the present invention, it is possible to exemplify a form in which activation promoting means for accelerating the time for the temperature of the carbon monoxide reducing unit to reach the activation temperature region at the time of startup. As the activation promoting means, a form that is a heating unit such as an electric heater that directly or indirectly heats the carbon monoxide reduction unit can be adopted. If it is an electric heater, controllability is favorable.

  Further, the activation promoting means exemplifies a form having a combustion exhaust gas passage for supplying combustion exhaust gas from the combustion part of the reforming part to the carbon monoxide reduction part and heating the carbon monoxide reduction part by heat of the combustion exhaust gas. be able to. At startup, high-temperature combustion exhaust gas is discharged from the combustion part of the reforming part into the combustion exhaust gas passage, so that the carbon monoxide reduction part can be heated in a short time. In this case, since the carbon monoxide reduction unit can reach the activation temperature region at an early stage even at the start-up, it can contribute to reducing the CO concentration of the reformed gas. Further, the activation promoting means can be exemplified by a form in which oxygen is supplied to the carbon monoxide reduction unit at the time of activation. Thereby, carbon monoxide and oxygen can be reacted to contribute to reducing the CO concentration at the time of startup.

  According to the present invention, the activation promoting means introduces the fuel gas containing hydrogen and carbon monoxide into the catalytic combustion section, and introduces the fuel gas containing hydrogen and carbon monoxide into the catalytic combustion section by the introducing means. Before starting, a mode including oxygen supply means for supplying a gas (generally air) containing oxygen as a main component to the catalytic combustion section can be exemplified. When the fuel gas containing hydrogen and carbon monoxide is supplied to the catalytic combustion unit in a state where the gas mainly containing oxygen is supplied to the catalytic combustion unit, the fuel gas contains carbon monoxide. Even if it exists, it is easy to ensure the ignitability of a catalyst combustion part. Carbon monoxide tends to be adsorbed by the catalyst in the catalytic combustion section and reduce the catalytic activity. However, if there is hydrogen that is easily combusted, the catalytic combustion part is easily ignited due to the ease of combustion of hydrogen. Here, hydrogen molecules are light and have a low viscosity, and the flow rate is faster than that of carbon monoxide molecules. Therefore, hydrogen molecules are more likely to reach the catalytic combustion part than carbon monoxide molecules, and a hydrogen-rich atmosphere is temporarily created. It is presumed that this is also attributed to the fact that it is easily generated in the catalytic combustion section.

  According to the present invention, it is possible to exemplify a form in which a catalytic combustion control unit that controls catalytic combustion of the catalytic combustion unit is provided. When the catalytic combustion unit is ignited, the catalytic combustion control unit ignites the catalytic combustion unit in a region outside the combustible range where the fuel gas and air burn while generating a flame, and after the ignition, the catalytic combustion unit It is possible to execute an increase operation for increasing the amount of air supplied per unit time per unit time compared to the ignition operation. Ignition refers to a phenomenon in which an oxidative combustion reaction starts and continues. About the presence or absence of ignition, it can determine with ignition, for example, when the temperature of a catalyst combustion part rises a certain temperature. Since the combustibility in the catalytic combustion is good, the catalytic combustion part can be ignited even in a region outside the combustible range. If the flow rate of air supplied to the catalytic combustion section is increased after ignition, the stability of the oxidation reaction in the catalytic combustion section is improved, and further, the amount of heat generated and the temperature rise in the catalytic combustion section are secured. Therefore, even when CO that inhibits combustibility is contained in the fuel gas, even when the air-fuel ratio, which is the ratio of the combustible component of the fuel gas to air, fluctuates, or the temperature of the catalyst Even when the fuel gas contains moisture such as water vapor or water droplets, it is easy to control the combustion in the catalytic combustion section.

  Embodiment 1 of the present invention will be specifically described below with reference to the drawings. The reformer according to the present embodiment is applied to a fuel cell power generation system. FIG. 1 is a system diagram of a reformer. FIG. 2 is a diagram schematically showing the main part of the reformer. 3 and 4 show the catalytic combustion section. As shown in FIG. 1, a fuel cell stack 1 is provided. The stack 1 is a stack of a plurality of cells of a fuel cell. The cell is sandwiched between a fuel electrode 10 to which a reformed gas (fuel gas) is supplied, an oxidant electrode 11 to which an oxygen-containing gas containing oxygen as an oxidant is supplied, and the fuel electrode 10 and the oxidant electrode 11. And an electrolyte membrane 12.

  The fuel gas processing apparatus is generated by a reforming unit (gas supply unit) 2 that generates reformed gas (fuel gas) containing hydrogen as a main component by steam reforming the reforming raw material, and the reforming unit 2. And a carbon monoxide reduction unit 3A for reducing carbon monoxide as an impurity contained in the reformed gas. The reforming material is a fuel material and an aqueous material. Examples of the fuel-based material include city gas, LPG, kerosene, diethyl ether, and other hydrocarbon fuels, methanol and other alcohol fuels, and the like.

  As shown in FIG. 2, the reforming unit 2 includes a reforming unit body 20 having a reforming catalyst 20c that promotes a reforming reaction, a burner 21 to which a fuel system material and air are supplied, and the fuel system material burns. A cylindrical combustion zone 22 having a ring-shaped cross section, and a cylindrical evaporation section 23 having a ring-shaped cross section for evaporating the water-based material by heat transferred from the combustion zone 22. The burner 21 and the combustion zone 20 form a combustion part 200. The heat in the combustion zone 22 is transmitted to the reforming unit main body 20 and the evaporation unit 23. The active temperature region of the reforming catalyst 20c provided in the reforming unit main body 20 is generally 500 to 800 ° C., but is not limited thereto.

  As shown in FIG. 2, an electric heater 59 (activation promoting means) that functions as a heating unit for heating the shift unit 3 is attached to the shift unit 3. In particular, the electric heater 59 is attached to the outer peripheral side of the shift portion 3 in a cylindrical shape having a ring-shaped cross section.

  As shown in FIG. 2, the fuel system material and combustion air are supplied to the burner 21, and the reforming unit body 20 is heated to a high temperature region by the combustion of the fuel system material. Based on the following formula (1), the reforming unit main body 20 reacts a reforming raw material (a fuel-based raw material and an aqueous raw material) to perform steam reforming, and fuels a reformed gas containing hydrogen as a main component. Produced as a gas. CO is generated as a by-product in the reformed gas generated in the reformer main body 20. In this case, the concentration of CO is generally 5 to 15%, but is not limited thereto. The CO concentration is based on mol%.

  As shown in FIG. 1, the carbon monoxide reduction unit 3A is disposed downstream of the reforming unit 2 so as to be able to transfer heat to a position where heat from the reforming unit 2 is transmitted. The shift part 3 as a part and the CO purification part 4 as a CO second reduction part are formed. The shift unit 3 includes a shift catalyst 3c that promotes the shift reaction based on the following formula (2). The active temperature region of the shift catalyst 3c is generally 200 to 300 ° C., but is not limited thereto. The shift catalyst 3c includes, for example, a copper-zinc catalyst as a main component, but is not limited thereto.

The CO purification unit 4 has a purification catalyst 4c (for example, ruthenium-based) that promotes a reaction that oxidizes and reduces CO to carbon dioxide based on the following formula (3), and further carries the purification catalyst 4c. And a ceramic carrier (for example, alumina). The activation temperature region of the purification catalyst 4c is generally 100 to 200 ° C., but is not limited thereto. The concentration of CO contained in the reformed gas purified by the shift unit 3 is generally 0.2 to 1%, but is not limited thereto. The concentration of CO contained in the reformed gas purified by the CO purification unit 4 is generally 10 ppm or less, but is not limited thereto.
Formula (1): CH ₄ + H ₂ O → 3H ₂ + CO
Formula (2): CO + H ₂ O → H ₂ + CO ₂
Formula (3): CO + 1 / 2O ₂ → CO ₂
As shown in FIG. 1, the catalytic combustion unit 5 that undergoes an oxidation reaction with a catalyst is interposed between the shift unit 3 and the reforming unit 2, and communicates with the inlet 5 s that communicates with the reforming unit 2 and the shift unit 3. And an outlet 5e. The catalytic combustion unit 5 is disposed downstream of the reforming unit 2 and upstream of the shift unit 3 so as to easily raise the temperature of the shift unit 3, and in particular, disposed adjacent to the shift unit 3. Yes. That is, in the flow path in which the reformed gas generated in the reforming unit 2 at the start flows toward the shift unit 3, the catalytic combustion unit main body of the catalytic combustion unit 5 downstream of the reforming unit 2 and upstream of the shift unit 3. 50 is arranged. This constitutes a catalyst combustion part main body temperature increase promotion means.

  At startup, the reformed gas (fuel gas) generated by the reforming unit 2 is introduced into the warm-up inlet 5i of the catalytic combustion unit main body 50 of the catalytic combustion unit 5. Therefore, the catalytic combustion unit body 50 burns the reformed gas and warms up the shift unit 3 (warm-up target) using the combustion heat when starting up. By the warm-up, the reaction for reducing the carbon monoxide in the reformed gas in the shift unit 3 is promoted.

  3 and 4 show the concept of the catalyst combustion unit 5 described above. The catalytic combustion unit 5 has a catalytic combustion function, and has a catalyst 5c (for example, Pt—Pd system) for catalytic combustion. Specifically, the catalyst combustion unit 5 includes a plurality of catalyst combustion unit main bodies 50 including a ceramic carrier (for example, alumina) carrying the catalyst 5c, a plurality of reformed gas passages 51, and a reformed gas passage 51. And a shielding part 52 that shields the light. The catalytic combustion unit main body 50 has air permeability and can permeate the reformed gas (reformed reflux gas) while burning it. The carrier supporting the catalyst 5c may be in the form of pellets or monolith. As described above, catalytic combustion is a catalyst that oxidizes fuel gas and oxygen, and is generally flameless combustion (in some cases, flammable combustion), compared to normal combustion that does not use a combustion catalyst. Combustion is stable and the combustion temperature is low.

  As shown in FIG. 3, the inlet 5 s on one end side of the reformed gas passage 51 of the catalytic combustion unit 5 communicates with the reforming unit main body 20. The outlet 5 e on the other end side of the reformed gas passage 51 communicates with the shift unit 3. Therefore, the reformed gas generated in the reforming unit main body 20 passes through the inlet 5 s → the reformed gas passage 51 → the outlet 5 e in the catalytic combustion unit 5 and heads toward the shift unit 3. As shown in FIG. 4, in the catalytic combustion unit 5, the catalytic combustion unit main body 50 and the reformed gas passage 51 face each other. Thereby, the temperature increase rate of the catalytic combustion unit main body 50 at the time of start-up is increased by the high-temperature reformed gas passing through the reformed gas passage 51.

  According to the present embodiment, as shown in FIG. 1, the cooling unit 6 is provided between the reforming unit 2 and the catalytic combustion unit 5. The cooling unit 6 is for cooling the high-temperature reformed gas before the reformed gas reformed in the reforming unit 2 is supplied to the catalytic combustion unit 5. Here, as shown in FIG. 2, the cooling unit 6 includes a gas passage 60 that supplies the reformed gas reformed by the reforming unit body 20 toward the reformed gas passage 51 of the catalytic combustion unit 5, and a modified gas passage 60. It has a raw material passage 61 through which the reformed raw material (fuel-based raw material and aqueous-based raw material) before being supplied to the mass body 20 is passed. As a result, the reformed gas passing through the gas passage 60 is cooled and the reformed raw material passing through the raw material passage 61 is heated. For this reason, the cooling unit 6 includes a reforming material having a relatively low temperature before being supplied to the reforming unit 2 and a reformed gas having a relatively high temperature after being discharged from the reforming unit 2. It can function as a heat exchanging part for exchanging heat.

  The piping system will be further described with reference to FIG. A first passage 71 is provided for supplying the fuel-based material to the burner 21 or the reforming unit body 20 as a reforming material. The first passage 71 is provided with transport elements 71m and 71n such as a pump for transporting the fuel-based material. Furthermore, the 2nd channel | path 72 which supplies a water-system raw material to the reforming part main body 20 as a reforming raw material is provided. The second passage 72 is provided with a transport element 72m such as a pump for transporting the aqueous raw material to the reforming unit 2. A third passage 73 is provided for supplying air (oxygen-containing gas) to the warm-up inlet 5i side of the catalytic combustion unit 5 via the first valve 81 (first opening / closing means). The third passage 73 is provided with a transport element 73m such as a fan, a compressor, a blower, or a pump that transports air. Further, an air passage 76 for supplying air to the burner 21 is provided so as to communicate with the third passage 73. The air passage 76 is provided with a conveying element 73x. An oxidant passage 11 k for supplying air to the oxidant electrode 11 of the stack 1 is provided so as to communicate with the third passage 73. A transport element 73w is provided in the oxidant passage 11k.

  As shown in FIG. 1, the 4th channel | path 74 which supplies the air for CO purification | cleaning to the CO purification | cleaning part 4 via the 2nd valve | bulb 82 (2nd opening-closing means) is provided. A connection passage 77 that connects the shift unit 3 and the CO purification unit 4 is provided. A fifth passage 75 is provided that connects the outlet 4p side of the CO purification unit 4 and the inlet 10i side of the fuel electrode 10 of the stack 1 via a third valve 83 (third opening / closing means) and a condenser 87 '. A first return passage 78 that connects the outlet 10p side of the fuel electrode 10 of the stack 1 of the fuel cell and the burner 21 of the reforming unit 2 is provided. In the first return passage 78, a fourth valve 84 (fourth opening / closing means), a condenser 87, and a fifth valve 85 (fifth opening / closing means) are provided in order from the stack 1 to the burner 21 in series.

  As shown in FIG. 1, a first bypass passage 79 is provided to connect the outlet 4p side of the CO purification unit 4 and the inlet 87i side of the condenser 87 via a bypass valve 79v so as to bypass the stack 1. ing. Furthermore, a second bypass passage 80 is provided that connects the outlet 87p side of the condenser 87 and the warm-up inlet 5i side of the catalytic combustion unit 5 via a sixth valve 86 (sixth opening / closing means). The second detour passage 80 through which the reformed gas flows joins the third passage 73 through which air flows, at the junction 80x. A second return passage 70 is provided to connect the warm-up outlet 5p side of the catalyst combustion unit 5 and the burner 21.

  Further, a description will be added with reference to FIG. As shown in FIG. 2, the reforming part main body 20 has an inner part 20i, an outer part 20p, and a folded part 20m. When the fuel cell system is activated, that is, when the reforming unit 2 is activated, the burner 21 is ignited while supplying the fuel system material and combustion air to the burner 21, and the fuel system material is combusted in the reforming unit 2. Let As a result, the reforming unit main body 20 and the evaporation unit 23 are gradually heated. Since heat of the reforming unit 2 is slowly transferred to the shift unit 3 and the CO purification unit 4, at the time of start-up, the shift unit 3 and the CO purification unit 4 are in the respective active temperature regions for a long time (for example, 30 to 90 minutes). Take it and get there. In addition, as shown in FIG. 2, the evaporation part 23 which produces | generates water vapor | steam is interposed between the CO purification | cleaning part 4 and the combustion zone 22, and the evaporation part 23 consumes a lot of heat for steaming. Further, overheating of the CO purification unit 4 and the catalyst 4c is suppressed.

  Thus, the fuel-based material and the water-based material are supplied to the reforming unit main body 20 in a state where the reforming unit 2 is at a high temperature. In this case, the water-based raw material is steamed when passing through the evaporator 23. The steam and the fuel-based raw material are merged in the merge area 71 s, flow in the directions of arrows B 2 and B 3 through the raw material passage 61 of the cooling unit 6, and are supplied to the outer portion 20 p of the reforming unit main body 20. In this way, the reforming raw material is preheated when passing through the raw material passage 61 of the cooling unit 6.

  In FIG. 2, the above-described reforming raw material flows into the outer portion 20p of the reforming portion main body 20, proceeds in the direction of arrow B4 at the outer portion 20p, and further in the direction of arrow B5 at the folded portion 20m of the reforming portion main body 20. Furthermore, the inner part 20i of the reforming part main body 20 is advanced in the direction of arrow B6. Thus, when the reforming raw material passes through the interior of the reforming unit main body 20, steam reforming is performed, and reformed gas is generated. The generated reformed gas travels in the direction of the arrow C <b> 1 through the gas passage 60 of the cooling unit 6, and reaches the shift unit 3 through the reformed gas passage 51 of the catalytic combustion unit 5.

  Here, according to the present embodiment, steam reforming is performed based on the above-described formula (1), and hydrogen-rich reformed gas containing CO is generated. In the shift unit 3, CO in the reformed gas is reduced based on the shift reaction of the above formula (2). In the CO purification unit 4, CO in the reformed gas is further reduced based on the above equation (3). Thereby, CO in the reformed gas is reduced so as to be suitable for the power generation reaction in the stack 1.

  By the way, at the time of startup, the temperature of the reforming unit main body 20 is low, the CO concentration of the reformed gas generated in the reforming unit main body 20 is high, and the temperature of the shift unit 3 is low. Has not reached. Therefore, the CO reduction effect by the shift unit 3 is limited, and it is not always sufficient to use the reformed gas for power generation in the stack 1. Therefore, according to this embodiment, at the time of start-up, the reformed gas is not supplied to the stack 1, but the stack 1 is bypassed, returned to the burner 21, and burned by the burner 21. That is, as shown in FIG. 1, the reformed gas that has passed through the CO purification unit 4 is supplied to the inlet 87i of the condenser 87 through the bypass valve 79v and the first bypass passage 79, and the reformed gas is supplied to the condenser 87. And the moisture contained in the reformed gas is condensed to reduce the moisture contained in the reformed gas. Thereafter, the gas is returned to the burner 21 through the opened fifth valve 85 and the first return passage 78.

  Now, according to the present embodiment, since the electric heater 59 generates heat at the time of startup, the shift unit 3 is heated early, and the time for the shift catalyst 3c of the shift unit 3 to reach its active temperature region is shortened. . The electric heater 59 can be turned off by shifting to the steady operation from the startup.

  As described above, since the time for the shift catalyst 3c of the shift unit 3 to reach the active temperature region thereof becomes early, the reformed gas is purified by the shift unit 3 at the time of start-up, and the CO concentration is reduced early. After the reforming of the reformed gas progresses in this way and the CO concentration of the reformed gas is reduced (for example, 0.01 to 0.1% or less in mol%), the sixth valve 86 is opened. In this case, the fifth valve 85 is closed.

  Then, the reformed gas whose moisture has been reduced by the condenser 87 is introduced into the warm-up inlet 5i of the catalytic combustion section 5 through the outlet 87p of the condenser 87, the sixth valve 86, and the second bypass passage 80. . At this time, the first valve 81 is opened, and air for catalytic combustion is introduced into the warm-up inlet 5 i of the catalytic combustion unit 5 through the first valve 81. The reformed gas introduced into the warm-up inlet 5i of the catalyst combustion unit 5 (mainly hydrogen having excellent low-temperature combustibility) is combined with the air introduced into the warm-up inlet 5i of the catalyst combustion unit 5. Then, it passes through the inside of the catalytic combustion section main body 50 in the direction of arrow E1 (see FIG. 4), and is catalytically burned by the catalyst 5c in the catalytic combustion section main body 50. For this reason, the temperature of the shift unit 3 can be raised by the catalytic combustion unit 5 during startup. If the temperature of the shift unit 3 rises, or after the ignition of the catalytic combustion unit 5 is confirmed, the electric heater 59 can be turned off.

  The off-gas after catalytic combustion in the catalytic combustion unit 5 reaches the downstream from the warm-up outlet 5p of the catalytic combustion unit 5 and returns to the burner 21 through the second return passage 70 and the first return passage 78. This off-gas may contain hydrogen as a combustion component, but this combustion component is burned by the burner 21 and then exhausted.

  As described above, during the warm-up operation in which the catalytic combustion unit 5 is heated by catalytic combustion, the third valve 83 and the fourth valve 84 are closed, but the bypass valve 79v, the first valve 81, and the sixth valve 86 are closed. Is open. As described above, during the warm-up operation, the second valve 82 is generally closed, but the second valve 82 may be opened and air may be supplied to the CO purification unit 4 as necessary. .

  When the predetermined time has elapsed since the start-up, the reforming unit main body 20 is heated, and at least a part of the shift unit 3 is heated, and the CO reduction effect in the shift unit 3 is considerably improved. Can be migrated. In the steady operation, the third valve 83, the fourth valve 84, the fifth valve 85, and the second valve 82 are opened, and the bypass valve 79v, the sixth valve 86, and the first valve 81 are closed. As a result, the first bypass passage 79 and the second bypass passage 80 are blocked. Therefore, during steady operation, the reformed gas steam-reformed by the reforming unit main body 20 is supplied to the cooling unit 6, the reformed gas passage 51 of the catalytic combustion unit 5, the shift unit 3, the connection passage 77, and the CO purification unit. 4, the third valve 83, and the fifth passage 75 in order, and supplied to the inlet 10 i of the fuel electrode 10 of the stack 1. Furthermore, in steady operation, air, which is an oxidant gas, is supplied to the oxidant electrode 11 of the stack 1 via the valve 11v of the oxidant passage 11k. As a result, a power generation reaction occurs in the stack 1 and electric energy is generated. The off-gas of the reformed gas used for power generation is supplied from the outlet 10p side of the fuel electrode 10 of the stack 1 to the burner 21 through the first return passage 78, the condenser 87, and the fifth valve 85. Since the off-gas of the reformed gas used for power generation can contain hydrogen as a combustion component, the combustion component is burned by the burner 21 and then exhausted.

  According to the present embodiment, the heated heat of the catalytic combustion unit 5 can be effectively transmitted to the shift unit 3 and the CO purification unit 4 located downstream of the catalytic combustion unit 5. As a result, even at the time of start-up, the temperature increase rate of the shift unit 3 and the CO purification unit 4 can be increased, and the shift unit 3 and the CO purification unit 4 can reach the active temperature region of these catalysts 3c and 4c at an early stage. The purification efficiency of the reformed gas can be increased early.

  In addition, when the temperature of the catalytic combustion unit 5 is raised as described above, the reformed gas supplied to the warm-up inlet 5i of the catalytic combustion unit 5 often has moisture. This is because the reformed gas has undergone steam reforming. For this reason, the reformed gas may have moisture equivalent to the saturated vapor pressure. Further, since the reformed gas is cooled in the second bypass passage 80 from the condenser 87 toward the catalyst combustion unit 5, the reformed gas supplied to the warm-up inlet 5 i of the catalyst combustion unit 5 has moisture. May be included as water droplets.

  Therefore, according to the present embodiment, as shown in FIGS. 3 and 4, the first gas contact member 9 is provided on the warm-up inlet 5 i side of the catalytic combustion unit main body 50 in the catalytic combustion unit 5. . Here, the warm-up inlet 5i of the catalytic combustion unit main body 50 includes the catalytic combustion unit main body 50 among the flow paths through which the reformed gas flows through the first gas contact member 9 (moisture reduction means) during startup. It is located upstream. Further, the warm-up outlet 5p of the catalyst combustion unit main body 50 is more than the catalyst combustion unit main body 50 in the flow path in which the reformed gas flows through the first gas contact member 9 (moisture reduction means) at the time of startup. Located downstream.

  As shown in FIGS. 3 and 4, the first gas contact member 9 has a contact portion 90 that contacts with the reformed gas supplied to the catalytic combustion portion main body 50 of the catalytic combustion portion 5 during the warm-up operation. It has a plate shape so as to perform a baffle plate function. The first gas contact member 9 faces the passage portion 80a through which the reformed gas supplied from the outlet 87p of the condenser 87 via the second bypass passage 80 flows. Specifically, as shown in FIG. 4, the first gas contact member 9 intersects the axis P <b> 1 of the passage portion 80 a connected to the warm-up introduction port 5 i of the catalytic combustion unit 5 in the second bypass passage 80. Oriented to the direction. That is, the first gas contact member 9 is oriented in the direction orthogonal to the axis P1 of the passage portion 80a connected to the catalytic combustion unit 5 in the second bypass passage 80.

  Therefore, when the reformed gas is introduced into the warm-up inlet 5i of the catalyst combustion unit 5 at the time of starting the reformer, that is, during the warm-up operation for raising the temperature of the catalyst combustion unit 5 as described above, The reformed gas collides with the contact portion 90 of the first gas contact member 9. Therefore, moisture (water vapor, water droplets, etc.) contained in the reformed gas is captured by the contact portion 90 of the first gas contact member 9 and removed from the reformed gas. In particular, according to the present embodiment, the collision angles θ1 and θ2 at which the reformed gas collides with the contact portion 90 of the first gas contact member 9 are close to 90 degrees or 90 degrees, so that the collision property is high and It is advantageous for capturing the contained water droplets. When the reformed gas contains saturated water vapor, liquefaction tends to proceed due to impact during collision. In the present embodiment, the first gas contact member 9 can function as a moisture suppression unit that suppresses the moisture of the reformed gas from adhering to the catalytic combustion unit body 50 of the catalytic combustion unit 5 at the time of startup. .

  According to the present embodiment, moisture (steam, water droplets, etc.) contained in the reformed gas at the time of start-up causes the catalytic combustion unit main body 50 of the catalytic combustion unit 5, particularly the catalytic combustion unit main body 50. Adhesion to the reaction site of the catalyst 5c as a constituent element is suppressed. Therefore, at the time of start-up, the ignitability, the combustibility, and the temperature rise in the catalytic combustion unit body 50 that performs catalytic combustion can be further enhanced. That is, the catalyst combustion by the catalyst combustion part main body 50 can be started up early, and the catalyst combustion part main body 50 can be heated up early. As a result, the shift part 3 can be raised by raising the temperature early. Further, the first gas contact member 9 also has a function of dispersing the reformed gas in the plurality of reformed gas passages 51 in the catalytic combustion unit 5.

  Furthermore, according to the present embodiment, as shown in FIG. 3, an upstream moisture storage portion 53 is provided on the warm-up inlet 5 i side upstream of the catalytic combustion portion main body 50 of the catalytic combustion portion 5. Yes. The upstream moisture storage unit 53 has a space 53r that stores moisture captured from the reformed gas supplied to the catalytic combustion unit main body 50. A first gas contact member 9 is erected on the bottom surface 53 d of the upstream moisture storage portion 53. The bottom surface 53 d of the upstream moisture storage unit 53 is set at a position lower than the bottom surface 50 d of the catalytic combustion unit main body 50. Therefore, even if the moisture adhering to the contact portion 90 of the first gas contact member 9 flows down as water droplets, the moisture stays on the bottom surface 53d of the upstream moisture storage portion 53, but does not enter the catalytic combustion portion main body 50. It is done. Also in this sense, it is possible to quickly raise the temperature of the catalytic combustion unit main body 50 to quickly start up the warming-up action by the catalytic combustion unit main body 50, and to raise the temperature of the shift unit 3 early to start up. it can.

  In addition, water droplets condensed in the second return passage 70 may flow down and enter the downstream side of the catalytic combustion unit 5. In this regard, according to the present embodiment, as shown in FIG. 3, a space 55 r for storing moisture is provided on the warm-up outlet 5 p side, which is the downstream side of the catalytic combustion unit main body 50 of the catalytic combustion unit 5. A downstream moisture reservoir 55 is provided. The bottom surface 55 d of the downstream moisture storage unit 55 is set at a position lower than the bottom surface 50 d of the catalytic combustion unit main body 50. For this reason, even if moisture is stored as a liquid in the downstream moisture storage section 55, it is possible to prevent the moisture from entering the catalytic combustion section main body 50. Also in this sense, it is possible to quickly raise the temperature of the catalytic combustion unit main body 50 to quickly start up the warming-up action by the catalytic combustion unit main body 50, and to raise the temperature of the shift unit 3 early to start up. it can.

  In addition, even if moisture accumulates as a liquid in the bottom face 53d of the upstream moisture storage part 53 and the bottom face 55d of the downstream moisture storage part 55, it is not a lot. If the fuel cell power generation system is shifted from the start-up to the steady operation, the upstream moisture storage unit 53 and the downstream moisture storage unit 55 of the catalyst combustion unit 5 are considerably heated. For example, the temperature is raised to about 100 to 300 ° C. For this reason, even if moisture accumulates on the bottom surface 53d of the upstream moisture storage unit 53 and the bottom surface 55d of the downstream moisture storage unit 55 at the time of activation, the moisture is vaporized and disappears during steady operation. Therefore, it becomes more advantageous to suppress moisture from entering the catalytic combustion unit main body 50.

  As shown in FIGS. 3 and 4, a plate-like second gas contact member 95 is erected in the downstream moisture reservoir 55 provided downstream of the catalytic combustion unit main body 50. The second gas contact member 95 suppresses the water flowing down from the second return passage 70 from entering the catalytic combustion unit main body 50.

  FIG. 5 is a graph showing the relationship between the flammability limit and the adiabatic flame temperature. The adiabatic flame temperature is the theoretical temperature of the flame when the reformed gas, which is a fuel gas, is completely burned in an adiabatic state. The horizontal axis of FIG. 5 shows the flow rate at which the raw material gas (natural gas 13A) as the reforming raw material is supplied to the reforming unit 2 per unit time. One vertical axis in FIG. 5 represents the adiabatic flame temperature of the reformed gas. The other vertical axis | shaft of FIG. 5 shows the air flow rate supplied per unit time in a combustible limit. Here, the flammable range refers to a range of conditions in which a flame due to oxidation combustion can propagate and be sustained. The flammable limit is the limit of the flammable range. A characteristic line W1 in FIG. 5 indicates the flow rate of air supplied per unit time at the flammability limit. In FIG. 5, the region above the characteristic line W1 corresponds to a combustible range in which the flame propagation continues. The region below the characteristic line W1 corresponds to outside the combustible range. Characteristic lines S <b> 1 to S <b> 6 indicate the air flow rate (saturated steam) corresponding to the temperature introduced into the catalytic combustion unit 5. Further, TC indicates the heat resistant temperature of the catalyst 5c of the catalytic combustion unit main body 50, and is set to 750 ° C. in this embodiment. In addition, the heat-resistant temperature of a catalyst means the upper limit of the temperature normally used, suppressing deterioration of a catalyst.

  In this embodiment, a catalytic combustion control unit 100 that controls catalytic combustion in the catalytic combustion unit 5 is provided. The catalyst combustion control unit 100 performs ignition control on the catalyst combustion main body 50 of the catalyst combustion unit 5. According to the ignition control, at the start of combustion of the catalytic combustion unit 5, the air is released from the first valve 81 in the open state so that the fuel gas and the air are out of the combustible range where the combustion occurs while generating the flame. The reformed gas is introduced from the opened sixth valve 86 into the warm-up inlet 5i of the catalytic combustion unit 5, and as a result, the catalytic combustion unit main body 50 is ignited under the conditions in the region K1. Here, the region K1 corresponds to a flameless region where no flame is generated even when the reformed gas burns, and corresponds to a region below the characteristic line W1 indicating the heat resistant temperature of the catalyst 5c. The region K1 is partitioned by lines K2 to K6. Since the combustibility of the catalytic combustion is good, the catalytic combustion part main body 50 of the catalytic combustion part 5 can be ignited even in the region K1 outside the combustible range.

  According to this embodiment, after it is determined that the catalytic combustion unit main body 50 has ignited, the catalytic combustion control unit 100 determines the amount of air per unit time supplied to the warm-up inlet 5i of the catalytic combustion unit 5 as follows: An increase operation is performed to increase the ignition operation. In this case, the air amount may or may not be within the combustible range beyond the characteristic line W1 indicating the combustible range limit. Here, as the determination of the ignition of the catalytic combustion unit main body 50, when the temperature of the catalytic combustion unit main body 50 is increased by ΔTa (for example, 80 ° C.) or more than the temperature T1 before the ignition operation, the catalytic combustion unit main body 50 is ignited. Can be determined. ΔTa can be appropriately set according to the basic composition of the reformed gas, the type of the catalyst 5c, and the like.

  During the increase operation described above, the opening degree of the sixth valve 86 is constant, and the flow rate per unit time of the fuel gas supplied to the warm-up inlet 5i of the catalytic combustion unit 5 does not basically change. For example, ignition is performed at the site R1 in FIG. 5, and the amount of air is increased in the direction of the arrow M1 in FIG. Further, ignition is performed at the site R3 in FIG. 5, and the amount of air is increased in the direction of the arrow M2 in FIG.

  In the above increase operation, the temperature of the catalyst combustion unit body 50 of the catalyst combustion unit 5 does not exceed the heat resistance temperature TC of the catalyst 5c carried on the catalyst combustion unit body 50, or the heat resistance temperature of the catalyst 5c. Even if the TC may be temporarily exceeded, the frequency of the TC is set not to be excessive. As a result, the thermal deterioration of the catalyst 5c carried on the catalytic combustion unit main body 50 is suppressed, which is advantageous for extending the life of the catalyst 5c.

  As described above, according to this embodiment, even when the air-fuel ratio, which is the ratio between the combustible component contained in the reformed gas and air, fluctuates, or when the temperature of the catalyst 5c is low, the fuel gas Even when CO gas is present in the gas, and even when moisture such as water vapor and water droplets is present, the catalytic combustion unit body 50 can be ignited satisfactorily. Therefore, at the time of ignition, it is possible to avoid the occurrence of a flame in the downstream pipe from the catalyst combustion unit 5, and it becomes easy to control the combustion of the catalyst combustion unit main body 50 of the catalyst combustion unit 5. Furthermore, after ignition, the air can be increased and combustion of the catalytic combustion unit body 50 of the catalytic combustion unit 5 can be performed satisfactorily, which is advantageous in securing the amount of heat generated in the catalytic combustion unit 5.

  FIG. 6 shows an example of a flowchart of control executed by the catalytic combustion control unit 100. Control is not limited to this flowchart. First, a fuel-based material and a water-based material that are reforming materials are carried into the reforming unit 2 (step S102). Thereby, reformed gas is generated by the reforming unit 2. Further, the electric heater 59 is turned on for a predetermined time to heat the shift unit 3 (step S103). Thereby, at least a part of the shift unit 3 can reach the activation temperature region at an early stage, the CO purification ability of the shift unit 3 can be increased, and the CO concentration of the reformed gas is reduced. Thus, the reformed gas having a reduced CO concentration passes through the reformed gas passage 51 of the catalyst combustion unit 5, so that the adsorption of CO to the reaction site of the catalyst 5 c is suppressed. The electric heater 59 is turned off when a predetermined time has elapsed.

  Next, it is determined whether or not the temperature of the catalyst 5c of the catalytic combustion unit body 50 is equal to or higher than a first set temperature T1 (T1: for example, 90 ° C.) (step S104). When the catalyst 5c is too low, ignition of the combustion catalyst hardly occurs even though the CO concentration of the reformed gas is reduced. For this reason, if the temperature of the catalyst 5c of the catalytic combustion unit main body 50 has not reached the first set temperature T1, the temperature is too low, and the apparatus waits until it reaches the first set temperature T1 (step S104). Accordingly, step S104 constitutes an appropriate ignition temperature determining means for determining whether or not the temperature of the catalyst 5c of the catalytic combustion unit body 50 is an appropriate temperature for ignition.

  If the temperature of the catalyst 5c of the catalytic combustion unit body 50 is equal to or higher than the first set temperature T1, the sixth valve 86 is opened, and the reformed gas is introduced into the catalytic combustion unit 5 for warm-up via the second bypass passage 80. Supply to the mouth 5i (step S106). After a predetermined time has elapsed (step S108), the first valve 81 is opened, air is supplied to the warm-up inlet 5i of the catalytic combustion unit 5 (step S110), and an ignition operation for igniting the catalytic combustion unit 5 is performed. . Thus, at the time of ignition, the amount of air is less than the normal combustible range, but as described above, at least a part of the shift unit 3 is heated by the electric heater 59 and activated early, and the reforming is performed. Since the CO concentration of the quality gas is considerably reduced and the reformed gas is mainly composed of hydrogen, the ignitability in the catalytic combustion section 5 is ensured.

  The reason why the air is supplied to the warm-up inlet 5i after the reformed gas is supplied to the warm-up inlet 5i is to prevent unnecessary ignition. Accordingly, steps 106, S108, and S110 constitute fuel gas priority means for supplying fuel gas to the catalytic combustion unit 5 with priority over air.

  And it is determined whether the temperature measurement place of the shift part 3 is below 2nd setting temperature T2 (T2: 170 degreeC, for example) (step S112). If the temperature is equal to or higher than the second set temperature T2, it is determined that the shift unit 3 is sufficiently activated and the shift unit 3 does not need to be warmed up, and the process returns to the main routine. If the temperature measurement location of the shift unit 3 is lower than the second set temperature T2, the shift unit 3 is not sufficiently activated, and the shift unit 3 needs to be warmed up, and consequently the catalyst combustion unit 5 needs to be heated. It is determined that Therefore, step S112 constitutes a warm-up necessity determination unit that determines whether or not there is a need to warm up the shift unit 3 by raising the temperature of the catalytic combustion unit 5.

  Then, it is determined whether or not the temperature of the catalyst 5c of the catalyst combustion unit main body 50 of the catalyst combustion unit 5 has increased by ΔTa (ΔTa: for example, 80 ° C.) from the first set temperature T1 (step S114). If ΔTa is higher than the first set temperature T1, it is determined that the catalyst 5c of the catalytic combustion unit body 50 of the catalytic combustion unit 5 has ignited, and an ignition determination signal is output (step S116). Accordingly, step S114 constitutes an ignition determination means for determining whether or not the catalyst combustion unit body 50 of the catalyst combustion unit 5 is ignited. Thereafter, by increasing the degree of opening of the first valve 81 or increasing the amount of air transported by the transport element 73m, the flow rate of air per unit time supplied to the warm-up inlet 5i of the catalytic combustion unit 5 is increased. (Step S118) and an increase operation is performed. As a result, the catalytic combustibility in the catalytic combustion section 5 is advanced, a calorific value is ensured, and a warm-up performance in which the catalytic combustion section 5 warms up the shift section 3 is ensured.

  Next, it is determined whether or not the temperature of the catalyst combustion unit 5 is equal to or lower than the heat-resistant temperature TC of the catalyst 5c of the catalyst combustion unit body 50 by the temperature sensor 50x (temperature detection means) provided in the catalyst combustion unit 5 ( Step S120). If the temperature of the catalytic combustion unit 5 exceeds the heat-resistant temperature TC of the catalyst 5c of the catalytic combustion unit main body 50, air is supplied to the warm-up inlet 5i of the catalytic combustion unit 5 in order to protect the catalyst 5c from overheating. Is stopped (step S126), and the warm-up operation by the catalytic combustion unit 5 is stopped. Therefore, steps S120 and S126 constitute a catalyst protection means for thermally protecting the catalyst 5c of the catalytic combustion unit 5.

  Further, it is determined whether or not the warm-up of the shift unit 3 has been completed (step S124). That is, it is determined whether or not the temperature measurement place of the shift unit 3 is equal to or higher than the second set temperature T2. If it is equal to or higher than the second set temperature T2 (YES), it is determined that the warm-up of the shift unit 3 has been completed, so the supply of air to the warm-up inlet 5i is stopped (step S126), and the catalytic combustion unit 5 is stopped, and the process returns to the main routine. If the temperature measurement location of the shift unit 3 is less than the second set temperature T2 (NO), the warming-up of the shift unit 3 has not been completed yet, so the process returns to step S120, and the air to the warm-up inlet 5i The supply operation is continued and the increase operation is continued. Accordingly, step S124 constitutes a warm-up end determination unit that determines the timing for ending the warm-up operation by the catalytic combustion unit 5.

  In step S114, when the temperature of the catalyst 5c of the catalyst combustion unit body 50 of the catalyst combustion unit 5 is not increased by ΔTa from the first set temperature T1, it is estimated that the catalyst combustion unit body 50 is not ignited. It is determined whether a certain time has elapsed since the ignition operation described above (step S130). If the certain time has not elapsed, the process returns to step S114, and the determination of the presence or absence of ignition is continued. If the fuel cell power generation system does not ignite even after a certain period of time, it is determined that the fuel cell power generation system is abnormal (step S132), and the system is stopped (step S134). Therefore, steps S114 and S130 constitute ignition failure determination means for determining the ignition failure of the catalytic combustion unit 5.

  FIG. 7 shows a second embodiment. The present embodiment basically has the same configuration and the same function and effect as the first embodiment. Accordingly, FIGS. 1, 3, 4, and 5 can be applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. In the present embodiment, as shown in FIG. 7, the shift unit 3 that functions as a part of the carbon monoxide reduction unit has a combustion exhaust gas passage 200 serving as an activation promoting unit by promoting the temperature rise of the shift unit 3. Is provided. The combustion exhaust gas passage 200 is attached to the shift portion 3 on the outer peripheral side thereof, and has a ring-shaped heating passage 201 having an inlet 201i and an outlet 201p, an inlet 201i of the heating passage 201, and an outlet 22p of the combustion zone 22 of the reformer 2. A heating passage 203, a switching valve 204 as a flow switching means, and a bypass exhaust passage 205 that bypasses the heating passage 201.

  During the operation of the reforming unit 2, the combustion exhaust gas discharged from the outlet 22 p of the combustion zone 22 of the reforming unit 2 flows through the passage 203 and the heating passage 201 to heat the shift unit 3. For this reason, even at the time of starting, the shift catalyst 3c of the shift unit 3 can reach its activation temperature region in a short time. As a result, the CO concentration of the reformed gas can be reduced even at startup. Since the reformed gas thus purified is introduced into the inlet 5 i of the catalytic combustion unit 5, the adsorption of CO to the catalyst 5 c of the catalytic combustion unit 5 is suppressed. Therefore, the ignitability and combustibility in the catalytic combustion unit 5 can be improved even at the time of startup. After ignition, the flow rate of air supplied to the catalytic combustion unit 5 can be increased as in the first embodiment.

  If the temperature of the shift unit 3 becomes too high during steady operation or the like, the switching valve 204 reduces or sets the flow rate of the combustion exhaust gas toward the heating passage 201 to 0 and exhausts the combustion exhaust gas from the bypass exhaust passage 205. . Thereby, the overheating of the shift part 3 is suppressed and the protective property of the shift catalyst 3c can be improved. The switching valve 204 and the bypass exhaust passage 205 can function as catalyst protection means for protecting the shift unit 3 shift catalyst 3c.

  8 and 9 show a third embodiment. The present embodiment basically has the same configuration and the same function and effect as the first embodiment. Accordingly, FIGS. 1, 3, 4, and 5 can be applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. Also in the present embodiment, as shown in FIG. 8, the CO purification unit 4 is provided so as to be able to transfer heat to a position where heat from the reforming unit 2 is transmitted. The part is provided in an integral cylindrical shape having a ring-shaped cross section. Since the reforming unit 2 quickly reaches a high temperature at the time of start-up, the CO purification unit 4 can reach the activation temperature region in a short time. Adsorption to the catalyst 5c is suppressed, which is advantageous for improving the ignitability and combustibility in the catalytic combustion section 5.

  Further, at the time of startup, the catalytic combustion control unit 100 opens the second valve 82 and introduces air (oxygen) into the CO purification unit 4 via the second valve 82 and the fourth passage 74. Thereby, based on the reaction formula of the above-described formula (3), the CO gas of the reformed gas and oxygen are reacted to generate carbon dioxide, and the concentration of the CO gas of the reformed gas is reduced. This reaction is an exothermic reaction, is effective for raising the temperature and activating the CO purification unit 4, and is more advantageous for improving the ignitability and combustibility in the catalytic combustion unit 5.

  FIG. 9 shows an example of a flowchart of control executed by the catalytic combustion control unit 100. Control is not limited to this flowchart. First, the fuel-based material and the water-based material that are the reforming materials are carried into the reforming unit 2 (step S202). Thereby, reformed gas is generated by the reforming unit 2. It is determined whether the CO purification unit 4 is heated and exceeds a set temperature TE (for example, 80 ° C.) (step S204). The set temperature TE corresponds to a temperature slightly lower than the activation temperature region of the CO purification unit 4. If the CO purification unit 4 does not exceed the set temperature TE, it waits until it exceeds (step S204). If the CO purification unit 4 exceeds the set temperature TE, the second valve 82 (second opening / closing means) is opened, and purification air (oxygen) is supplied to the CO purification unit 4 via the fourth passage 74. (Step S206), CO gas of reformed gas and oxygen are reacted to generate carbon dioxide, purifying reaction is advanced in the CO purifying unit 4, and the CO concentration of the reformed gas is reduced. Further, it waits for a certain time (step S208). During this time, the temperature of the catalytic combustion unit main body 50 and the CO purification unit 4 is gradually increased. Step S206 can function as an activation promoting means for supplying oxygen to the CO purification unit 4 that is the carbon monoxide reduction unit at the time of startup. In steps S206, S208, and S210, at the time of start-up, oxygen is supplied to the CO purification unit 4 that is a carbon monoxide reduction unit to activate the CO purification unit 4, and then the fuel gas with reduced CO concentration is catalytically combusted. It can function as an activation promoting means to be supplied to the unit 5.

  Next, the sixth valve 86 is opened, and the reformed gas with reduced CO concentration is supplied to the warm-up inlet 5i of the catalytic combustion section 5 via the condenser 87, the sixth valve 86, and the second bypass passage 80. Supply (step S210). Then, it waits for a certain time (step S212). During this time, the reformed gas is charged into the catalytic combustion unit 5. Thereafter, a valve flow path change command is output (step S214), the first valve 81 is opened, air is supplied to the warm-up inlet 5i of the catalytic combustion unit 5 (step S216), and the catalytic combustion unit 5 is ignited. Perform the ignition operation. In this case, the opening amount of the second valve 82 may be reduced or closed. The reason why the air is supplied to the warm-up inlet 5i after supplying the reformed gas to the warm-up inlet 5i as described above is to prevent unnecessary ignition. Steps 210, S212, S214, and S216 constitute fuel gas priority means for supplying fuel gas to the catalytic combustion unit 5 with priority over air.

  And it is determined whether the temperature measurement place of the shift part 3 is below 2nd setting temperature T2 (T2: 170 degreeC, for example) (step S218). If it is above, since it is determined that the activation of the shift unit 3 is sufficient and the shift unit 3 does not need to be warmed up, the supply of air is stopped (step S230), and the process returns to the main routine. On the other hand, if the temperature measurement location of the shift unit 3 is lower than the second set temperature T2, the shift unit 3 is not sufficiently activated, and the shift unit 3 needs to be warmed up. It is determined that further temperature increase is required. Therefore, step S218 constitutes a warm-up necessity determination unit that determines whether or not it is necessary to warm up the shift unit 3 by raising the temperature of the catalytic combustion unit 5.

  And it is determined whether the catalyst 5c of the catalyst combustion part main body 50 of the catalyst combustion part 5 ignited (step S220). That is, it is determined whether or not the temperature of the catalytic combustion unit 5 has increased by ΔTa (ΔTa: for example, 80 ° C.) higher than the first set temperature T1, which is the initial temperature. If the temperature of the catalyst combustion unit 5 is higher by ΔTa than the first set temperature T1, it is determined that the catalyst 5c of the catalyst combustion unit body 50 of the catalyst combustion unit 5 has ignited, and an ignition determination signal is output (step S220). ). Therefore, step S220 constitutes an ignition determination means for determining whether or not the catalyst combustion unit body 50 of the catalyst combustion unit 5 is ignited.

  Thereafter, by increasing the degree of opening of the first valve 81 or increasing the amount of air transported by the transport element 73m, the flow rate of air per unit time supplied to the warm-up inlet 5i of the catalytic combustion unit 5 is increased. (Step S224), and an oxygen increasing operation is performed. Thereby, the catalyst combustibility in the catalyst combustion part 5 further progresses, and the calorific value and warm-up performance of the catalyst combustion part 5 are ensured.

  Next, it is determined whether or not the temperature of the catalyst combustion unit 5 is equal to or lower than the heat-resistant temperature TC of the catalyst 5c of the catalyst combustion unit body 50 by the temperature sensor 50x (temperature detection means) provided in the catalyst combustion unit 5 ( Step S226). If the temperature of the catalytic combustion unit 5 exceeds the heat-resistant temperature TC of the catalyst 5c of the catalytic combustion unit main body 50, air is supplied to the warm-up inlet 5i of the catalytic combustion unit 5 in order to protect the catalyst 5c from overheating. Is stopped (step S230), and the warm-up operation by the catalytic combustion unit 5 is stopped. Accordingly, steps S226 and S230 constitute a catalyst protection means for thermally protecting the catalyst 5c of the catalytic combustion unit 5.

  Further, it is determined whether or not the warm-up of the shift unit 3 has been completed (step S228). That is, it is determined whether or not the temperature measurement place of the shift unit 3 is equal to or higher than the second set temperature T2. If it is equal to or higher than the second set temperature T2 (YES), it is determined that the warming-up of the shift unit 3 has been completed, so the supply of air to the warming-up inlet 5i is stopped (step S230), and the catalytic combustion unit 5 is stopped, and the process returns to the main routine. If the temperature measurement location of the shift unit 3 is lower than the second set temperature T2, the warm-up of the shift unit 3 has not been completed yet (NO), so the process returns to step S226 and the air to the warm-up inlet 5i. The supply operation is continued and the increase operation is continued. Therefore, step S228 constitutes a warm-up end determination means for determining the timing for ending the warm-up operation by the catalyst combustion unit 5.

  In step S220, when the temperature of the catalyst 5c of the catalyst combustion unit body 50 of the catalyst combustion unit 5 has not risen by ΔTa from the first set temperature T1, which is the initial temperature, it is estimated that the catalyst combustion unit body 50 has not ignited. Therefore, it is determined whether a certain time has elapsed since the above-described ignition operation (step S234). If the certain time has not elapsed, the process returns to step S220, and the determination of the presence or absence of ignition is continued. If the fuel cell power generation system does not ignite even after a certain period of time, it is determined that the fuel cell power generation system is abnormal (step S236), and the system is stopped (step S238). Therefore, steps S220 and S234 constitute ignition failure determination means for determining the ignition failure of the catalytic combustion unit 5.

  FIG. 10 is a flowchart according to the fourth embodiment. The present embodiment basically has the same configuration and the same function and effect as the first embodiment. Accordingly, FIGS. 1, 2, 3, 4, and 5 can be applied mutatis mutandis. Hereinafter, a description will be given centering on differences from the first embodiment. In the present embodiment, the activation promoting means introduces the fuel gas containing hydrogen and carbon monoxide into the catalytic combustion section, and introduces the fuel gas containing hydrogen and carbon monoxide into the catalytic combustion section by the introducing means. Before starting, oxygen supply means for supplying air (oxygen) to the catalytic combustion unit 5 is provided.

  FIG. 10 shows an example of a flowchart of control executed by the catalytic combustion control unit 100. Control is not limited to this flowchart. First, the fuel-based material and the water-based material that are reforming materials are carried into the reforming unit 2 (step S302). Thereby, reformed gas is generated by the reforming unit 2. Wait for a certain period of time (step S304). When a certain time has elapsed, the CO purification unit 4 is heated. Next, the first valve 81 is opened with the sixth valve 86 closed, and air is supplied to the warm-up inlet 5 i of the catalytic combustion unit 5. Further, it waits for a certain time (step S308). As a result, air flows into the catalyst combustion section 5. Next, the sixth valve 86 is opened, and the reformed gas is supplied to the warm-up inlet 5i of the catalytic combustion unit 5 via the sixth valve 86 and the second bypass passage 80 (step S310). Thereby, an ignition operation for igniting the catalytic combustion unit 5 is performed. In this case, the second valve 82 may be opened or closed.

  As described above, when the reformed gas containing hydrogen and carbon monoxide is supplied to the catalytic combustion unit 5 in a state where air is supplied to the catalytic combustion unit 5, the reformed gas contains carbon monoxide. However, the ignitability of the catalytic combustion unit 5 is easily secured. Here, the carbon monoxide has a tendency to be adsorbed by the catalyst 5c of the catalytic combustion section 5 and reduce the catalytic activity. However, even if CO molecules are present, the catalyst 5c of the catalytic combustion unit 5 is easily ignited if hydrogen that is easily combusted is present. This is presumably due to the ease of hydrogen combustion. Furthermore, since hydrogen molecules are lightweight and have low viscosity, it is presumed that this is also due to high diffusivity and faster migration speed than carbon monoxide molecules.

  Here, when the closed sixth valve 86 is opened, hydrogen molecules and CO molecules contained in the reformed gas travel from the sixth valve 86 to the catalytic combustion unit 5 through the warm-up inlet 5i. In this case, even if the position of the sixth valve 86 is close to the warm-up introduction port 5i, hydrogen has easy ignition and low temperature ignition, so that the ignition in the catalytic combustion unit 5 can be ensured. In addition, when the distance between the sixth valve 86 (fuel gas supply valve) and the warm-up introduction port 5i is long, hydrogen molecules having ease of ignition advance faster than CO molecules having ignition inhibition properties. It can be considered that the degree can be increased, and consequently, the state of being rich in hydrogen and having a low CO concentration can be temporarily formed in the vicinity of the catalytic combustion unit 5 and the ignitability and combustibility in the catalytic combustion unit 5 can be improved. Therefore, the distance between the sixth valve 86 and the warm-up introduction port 5i can be set to some extent. However, if the distance is long, the size increases. Therefore, although the distance depends on the size of the fuel cell power generation system, it can be set to about 3 to 100 centimeters, for example, but is not limited thereto. Therefore, Steps 306, S308, and S310 constitute an accelerating unit that prioritizes hydrogen over CO to reach the catalytic combustion unit 5 to promote the ignitability of the catalytic combustion unit 5. Here, since hydrogen is excellent in low-temperature flammability that can be burned even at low temperatures, once the catalytic combustion section 5 is ignited, the CO concentration of the reformed gas is temporarily high (for example, about 10 to 15%). Even in this case, the combustibility in the catalytic combustion unit 5 is maintained.

  According to the present embodiment, step S310 can function as introduction means for introducing a fuel gas containing hydrogen and carbon monoxide into the catalytic combustion unit 5. Step S306 can function as an oxygen supply unit that supplies oxygen (air) to the catalytic combustion unit 5 before introducing the fuel gas containing hydrogen and carbon monoxide into the catalytic combustion unit 5 by the introducing unit.

And the temperature measurement place of the shift part 3 is 2nd setting temperature T2 (T2: 170 degreeC, for example)
It is determined whether the following is true (step S312). If it is above, since it is determined that the shift unit 3 is sufficiently activated and the shift unit 3 does not need to be warmed up, the supply of air is stopped (step S324), and the process returns to the main routine. If the temperature measurement location of the shift unit 3 is lower than the second set temperature T2, the shift unit 3 is not sufficiently activated, and the shift unit 3 needs to be warmed up. As a result, the catalyst combustion unit 5 is further heated. Is determined to be necessary. Therefore, step S312 constitutes a warm-up necessity determining unit that determines whether or not there is a need to warm up the shift unit 3 by raising the temperature of the catalytic combustion unit 5.

  Then, whether or not the temperature of the catalyst 5c of the catalyst combustion unit main body 50 of the catalyst combustion unit 5 has increased by ΔTa (ΔTa: for example, 80 ° C.) from the first set temperature T1, that is, whether or not the catalyst combustion unit 5 has ignited. Is determined (step S314). If ΔTa is higher than the first set temperature T1, it is determined that the catalyst 5c of the catalytic combustion unit body 50 of the catalytic combustion unit 5 has ignited, and an ignition determination signal is output (step S316). Therefore, step S314 constitutes an ignition determination means for determining whether or not the catalyst combustion unit body 50 of the catalyst combustion unit 5 is ignited. Thereafter, by increasing the degree of opening of the first valve 81 or increasing the amount of air transported by the transport element 73m, the flow rate of air per unit time supplied to the warm-up inlet 5i of the catalytic combustion unit 5 is increased. (Step S318) and an increase operation is performed. As a result, the catalytic combustibility in the catalytic combustion section 5 further proceeds, a calorific value is ensured, and a warm-up performance in which the catalytic combustion section 5 warms up the shift section 3 is ensured.

  Next, it is determined whether or not the temperature of the catalyst combustion unit 5 is equal to or lower than the heat-resistant temperature TC of the catalyst 5c of the catalyst combustion unit body 50 by the temperature sensor 50x (temperature detection means) provided in the catalyst combustion unit 5 ( Step S320). If the temperature of the catalytic combustion unit 5 exceeds the heat-resistant temperature TC of the catalyst 5c of the catalytic combustion unit main body 50, the supply of air to the warm-up inlet 5i of the catalytic combustion unit 5 is stopped to protect the catalyst 5c. (Step S324), and the warm-up operation by the catalyst combustion unit 5 is stopped. Therefore, steps S320 and S324 constitute a catalyst protection means for thermally protecting the catalyst 5c of the catalytic combustion unit 5.

  Further, it is determined whether or not the warm-up of the shift unit 3 has been completed (step S322). That is, it is determined whether or not the temperature measurement place of the shift unit 3 is equal to or higher than the second set temperature T2. If it is determined that the warm-up of the shift unit 3 has been completed (YES), the first valve 81 is closed to stop the supply of air to the warm-up inlet 5i (step S324), and the catalytic combustion unit 5 Stop warm-up operation and return to the main routine. If the temperature measurement location of the shift unit 3 is lower than the second set temperature T2 (NO), the warming-up of the shift unit 3 has not been completed yet, so the process returns to step S320, and the air to the warm-up inlet 5i The supply operation is continued and the increase operation is continued. Accordingly, step S322 constitutes a warm-up end determination means for determining the timing for ending the warm-up operation by the catalyst combustion unit 5.

  In step S314, when the temperature of the catalyst 5c of the catalyst combustion unit body 50 of the catalyst combustion unit 5 is not increased by ΔTa from the first set temperature T1, it is estimated that the catalyst combustion unit body 50 is not ignited. It is determined whether a certain time has elapsed since the ignition operation described above (step S330). If the certain time has not elapsed, the process returns to step S314, and the determination of the presence or absence of ignition is continued. If the fuel cell power generation system does not ignite even after a certain period of time, it is determined that the fuel cell power generation system is abnormal (step S332), and the system is stopped (step S334). Therefore, steps S314 and S330 constitute an ignition failure determination means for determining an ignition failure of the catalyst combustion unit 5.

(Other)
The fuel cell power generation system described above may be stationary, in-vehicle, or used for other purposes. In the above-described embodiment, the reformer is applied to a fuel cell power generation system. However, the present invention is not limited to this and may be applied to other systems such as a hydrogen production system.

  The present invention can be used in a fuel gas processing apparatus. For example, it can be used for a hydrogen production system having a fuel gas processing device and a fuel cell power generation system having a fuel gas processing device.

It is a conceptual diagram which shows a fuel cell power generation system. It is a block diagram which shows typically the reformer vicinity. It is a block diagram which shows a catalyst combustion part typically. It is a block diagram which shows a catalyst combustion part typically from a different direction. It is a graph which shows the form of making it transfer to ignition operation from ignition operation while showing the relationship between a combustible range and adiabatic combustion temperature. It is an example of the flowchart which a catalyst combustion control part performs. FIG. 6 is a configuration diagram schematically showing the vicinity of a reformer according to a second embodiment. FIG. 6 is a configuration diagram schematically showing the vicinity of a reformer according to a second embodiment. 12 is an example of a flowchart executed by the catalytic combustion control unit according to the third embodiment. 12 is an example of a flowchart executed by the catalytic combustion control unit according to the fourth embodiment.

Explanation of symbols

  1 is a stack, 10 is a fuel electrode, 11 is an oxidizer electrode, 2 is a reforming unit (gas supply unit), 20 is a reforming unit body, 3 is a shift unit (carbon monoxide reduction unit), and 4 is a CO purification unit. (Carbon monoxide reduction part), 5 is a catalyst combustion part, 5c is a catalyst, 50 is a catalyst combustion part main body, 59 is an electric heater (activation promoting means), 87 is a condenser, 100 is a catalyst combustion control part, 200 is A combustion exhaust gas passage (activation promoting means) is shown.

Claims (8)

A gas supply for supplying a fuel gas that may contain carbon monoxide;
In a fuel gas processing apparatus having a catalyst and a catalytic combustion section that oxidizes the fuel gas with the catalyst,
A fuel gas treatment comprising a carbon monoxide reduction unit that reduces carbon monoxide contained in the fuel gas before being supplied to the catalyst combustion unit, thereby improving ignitability in the catalyst combustion unit. apparatus.   2. The fuel gas processing apparatus according to claim 1, further comprising an activation promoting means for accelerating a time for the temperature of the carbon monoxide reducing unit to reach an activation temperature region at the time of startup. 3. The gas supply unit according to claim 1, wherein the gas supply unit includes a reforming unit body that reforms a reforming raw material to generate a reformed gas as a fuel gas, and a combustion unit that heats the reforming unit body by combustion. Have and
The fuel gas processing apparatus, wherein the carbon monoxide reduction unit is arranged to be capable of transferring heat to a position where heat from the reforming unit main body and / or the combustion unit is transmitted.   4. The combustion according to claim 2, wherein the activation promoting means supplies combustion exhaust gas from the combustion section of the reforming section to the carbon monoxide reduction section and heats the carbon monoxide reduction section with heat of the combustion exhaust gas. A fuel gas processing apparatus having an exhaust gas passage.   5. The fuel gas processing apparatus according to claim 2, wherein the activation promoting unit is a heating unit that heats the carbon monoxide reduction unit. 6.   6. The fuel gas processing apparatus according to claim 2, wherein the activation promoting unit supplies oxygen to the carbon monoxide reduction unit at the time of startup.   In any one of Claims 2-6, the said activation promotion means is the introduction means which introduce | transduces the fuel gas containing hydrogen and carbon monoxide into the said catalyst combustion part, Hydrogen and carbon monoxide. A fuel gas treatment comprising oxygen supply means for supplying a gas containing oxygen as a main component to the catalyst combustion section before introducing the fuel gas into the catalyst combustion section by the introduction means. apparatus.   The fuel gas processing apparatus according to any one of claims 1 to 7, wherein the fuel gas contains hydrogen.

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