JP2008081331A - Reformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reformer which is advantageous for regenerating a catalyst in a CO oxidation removal section. <P>SOLUTION: The reformer comprises a reforming apparatus 2 to produce a reformed gas, a CO oxidation removal section 37 having a catalyst 37e to remove carbon dioxide in the reformed gas by oxidizing it in a first temperature region and in an oxygen-containing atmosphere, an oxygen supplying section 75 to supply an oxygen component to the CO oxidation removal section 37, and a control system 500 to perform catalyst regeneration of the catalyst 37e. The catalyst regeneration comprises the operations of allowing the reformed gas to remain in the CO oxidation removal section 37, suspending supply of the oxygen component to the CO oxidation removal section 37, and maintaining the catalyst 37e in a catalyst regeneration temperature region for regenerating the catalyst 37e. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reformer that reacts a reforming fuel to generate a reformed gas containing hydrogen.

  In general, a reformer is configured by reacting a reforming water supply unit that supplies reforming water to an evaporation unit, a vapor or liquid phase water that has passed through the evaporation unit, and a reforming fuel. A reforming unit that generates reformed gas containing carbon oxide, a reforming fuel supply unit that supplies reforming fuel to the reforming unit, and monoxide contained in the reformed gas formed in the reforming unit A CO shift unit for reducing carbon, and a carbon shifter disposed downstream of the CO shift unit and remaining in the reformed gas by oxidizing the carbon monoxide and oxygen remaining in the reformed gas that has passed through the CO shift unit. A CO oxidation removing unit that further reduces carbon monoxide and an oxygen supply unit that supplies oxygen to the CO oxidation removing unit are provided.

  As described above, during the operation of the reformer, the CO oxidation removing unit oxidizes and removes carbon monoxide by causing an oxidation reaction between carbon monoxide remaining in the reformed gas and oxygen. The CO oxidation removing unit has a catalyst that promotes the oxidation reaction. However, as the reformer is used, the performance of the catalyst gradually decreases. Since the reformed gas containing reducible hydrogen is not generated during system shutdown, maintenance, etc., the catalyst in the CO oxidation removal unit may be in a condition to be oxidized by air intrusion or the like. In this case, the performance of the catalyst changes due to oxidation. Furthermore, the sulfur component may reduce the activity of the catalyst. If the operation of the reformer is resumed, a reformed gas containing hydrogen is generated. Therefore, if the catalyst is slightly oxidized, reduction regeneration of the catalyst proceeds. However, when the reforming section is used for a long time, the performance of the catalyst gradually changes.

  Patent Document 1 stops the operation of supplying oxygen to the CO oxidation removal unit by the oxygen supply unit while supplying the reforming fuel to the reforming unit and operating the reforming unit to generate reformed gas. And the technique which performs the high temperature process which maintains the temperature of the catalyst of a CO oxidation removal part in the area | region higher than an operating temperature, and regenerates the catalyst in a CO oxidation removal part is disclosed.

  Patent Document 2 is a mixture of a carbon monoxide removal catalyst (ruthenium, rhodium, platinum, etc.) for oxidizing and removing carbon monoxide contained in a fuel gas containing hydrogen as a main component, and a gas containing an inert gas such as nitrogen. Discloses a technique for activating the carbon monoxide removal catalyst.

  Patent Document 3 discloses a technique for reducing the catalyst filled in the reformer by adding an inert gas to the fuel and reformed water and supplying the fuel and reformed water to the reforming unit.

Patent Document 4 discloses a technology including a start-up combustor to which raw fuel and air are supplied, and catalyst regeneration means. The catalyst regeneration means reduces the catalyst by supplying a high-temperature reducing gas to the catalyst reaction section by the start-up combustor when the fuel cell system is started.
JP 2006-169013 A JP 2002-85983 A JP 2005-281090 A JP 2002-124286 A

  However, according to the above-described Patent Documents 1 to 4, it is not always sufficient to regenerate the catalyst in the CO oxidation removal section and to extend the life of the catalyst.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reformer that is advantageous for regenerating the catalyst in the CO oxidation removal unit and extending the life of the catalyst.

The reformer according to the present invention includes (a) a reforming unit that generates reformed gas containing hydrogen and carbon monoxide from reforming fuel, and (b) a reformer formed by the reforming unit. A CO oxidation removing section having a catalyst for reducing carbon monoxide from the reformed gas by oxidizing the carbon monoxide contained in the gas in the first temperature region and in the oxygen-containing atmosphere; and (c) An oxygen supply unit that supplies an oxygen component to the CO oxidation removal unit, and (d) a control device that performs a catalyst regeneration process for regenerating the catalyst of the CO oxidation removal unit,
The catalyst regeneration process
(I) a residual operation for leaving the reformed gas containing hydrogen in the CO oxidation removal unit;
(Ii) an oxygen supply stop operation for stopping supplying the oxygen component to the CO oxidation removing unit;
(Iii) A temperature maintaining operation for maintaining the catalyst in the CO oxidation removing unit in a catalyst regeneration temperature range for regenerating the catalyst in the CO oxidation removing unit.

According to the present invention, the control device performs a catalyst regeneration process that satisfies the conditions (i), (ii), and (iii).
(I) The control device causes the reformed gas containing hydrogen to remain in the CO oxidation removal unit. The reformed gas contains hydrogen having reducibility. Here, the reformed gas preferably contains hydrogen as a main component. The reformed gas preferably contains 10 mol% or more and 20 mol% or more of hydrogen. Thus, the reformed gas having reducibility is left in the CO oxidation removal section. As described above, the reformed gas remains in the CO oxidation removal portion, and therefore, even if the water vapor remaining during the stop operation is cooled and liquefied, the inside of the reformer is unlikely to become a negative pressure. This makes it difficult for air to enter the reformer. Even if air enters the reformer, oxygen in the air is consumed by hydrogen of the reformed gas remaining in the reformer, so that oxidation of the catalyst is suppressed. When air enters the reformer and oxygen in the air is consumed by the residual hydrogen in the reformer, there is also an effect that the negative pressure in the reformer is suppressed by the nitrogen in the air that has entered.
(Ii) The control device stops supplying the oxygen component to the CO oxidation removing unit. Therefore, the oxidation of the catalyst in the CO oxidation removing unit can be effectively suppressed. Therefore, the reduction of the oxidized portion of the catalyst easily proceeds.
(Iii) The control device maintains the catalyst of the CO oxidation removing unit in a catalyst regeneration temperature range in which the catalyst of the CO oxidation removing unit is regenerated. Since the catalyst is well maintained in the catalyst regeneration temperature region, the reduction of the oxidized portion of the catalyst proceeds. Therefore, the catalyst in the CO oxidation removing unit is regenerated.

  Here, the operations (i), (ii), and (iii) may be performed concurrently in time, or may be performed in parallel so as to be partially shifted in time, and may not overlap. The time may be shifted as described above. The operation (ii) may be performed after the operation (i). Alternatively, the operation (i) may be performed after the operation (ii).

  According to the reformer according to the present invention, the oxidized portion of the catalyst supported on the CO oxidation removing unit is reduced by the catalyst regeneration process, so that the catalyst is regenerated. Therefore, the life of the reformer can be extended.

  According to the present invention, during the operation of the reformer, the reformer generates reformed gas containing hydrogen and carbon monoxide from the reforming fuel. The CO oxidation removing unit has a catalyst. During the operation of the reformer, the CO oxidation removing unit is maintained in the first temperature range. The first temperature region means the temperature of the region where the catalyst is selectively oxidized in the state where the oxygen component is supplied. By oxidizing carbon monoxide contained in the reformed gas formed in the reforming section in the first temperature region, the carbon monoxide is oxidized and removed from the reformed gas as carbon dioxide. During operation of the reformer, the oxygen supply unit supplies an oxygen component to the CO oxidation removal unit to oxidize carbon monoxide.

The control device performs a catalyst regeneration process for regenerating the catalyst in the CO oxidation removing unit. The catalyst regeneration process is preferably performed during a stop operation for stopping the operation of the reformer. In some cases, the operation of the reformer may be performed during an interruption operation that temporarily interrupts the operation of the reformer. The catalyst regeneration treatment includes all the following operations (i) to (iii).
(I) A residual operation for leaving the reformed gas containing hydrogen in the CO oxidation removal section is performed. In this case, it is preferable to stop the generation of the reformed gas without supplying the reforming fuel to the reforming section. This is because if the extra fuel is added for the reduction operation, the total efficiency is lowered.
(Ii) An oxygen supply stop operation for stopping the supply of the oxygen component to the CO oxidation removal unit is performed.
(Iii) A temperature maintaining operation for maintaining the catalyst in the CO oxidation removing unit is performed in a catalyst regeneration temperature range in which the catalyst in the CO oxidation removing unit is regenerated.

  The above-mentioned catalyst regeneration temperature region is higher than the first temperature region, or is a temperature region corresponding to the first temperature region. Examples of the reforming unit include a reforming unit that generates reformed gas containing hydrogen and carbon monoxide from the reforming fuel, and a heating unit that heats the reforming unit.

  When the temperature of the CO oxidation removal unit is lower than the catalyst regeneration temperature region, the control device performs an increase operation for raising the temperature of the CO oxidation removal unit to the catalyst regeneration temperature region by the heating unit. As a result, the temperature of the CO oxidation removing unit is maintained in the catalyst regeneration temperature region.

  The control device may be configured to heat the CO oxidation removal unit in advance and / or during the catalyst regeneration process before the catalyst regeneration process. As a result, the temperature of the CO oxidation removing portion is easily maintained in the catalyst regeneration temperature region.

  The control device supplies combustion air to the combustion unit without supplying combustible fuel (combustion fuel) to the combustion unit, and warms the combustion air with the residual heat of the combustion unit and / or the residual heat of the reforming unit. The form which forms heated gas by is illustrated. The form with which the heat insulation part which covers a CO oxidation removal part is provided is illustrated. In this case, even when the operation of the reformer is stopped, the temperature reduction of the CO oxidation removal unit is suppressed, which is advantageous for maintaining the CO oxidation removal unit in the catalyst regeneration temperature region.

  The above-described heating unit is exemplified by a combustion unit that burns combustible fuel. The form which is any one of the combustible fuel supplied from the fuel supply source, the reformed gas produced | generated by the reforming part, and the off gas discharged | emitted from the fuel cell is illustrated.

  Examples of the control device include a mode in which the catalyst regeneration process is performed in at least one of stopping the reforming apparatus in operation, starting the reforming apparatus in stop, and operating the reforming apparatus. . In this case, the catalyst regeneration process may be performed every time the operation of the reformer is stopped or every time the operation of the reformer is started. For this reason, the purification performance of carbon monoxide is maintained over a long period of time. Immediately before the catalyst regeneration process, the S / C can be limited to 3.2 or less (2.5 or more) as the flow rate of reforming water per unit time supplied to the evaporation section. In particular, it can be limited to a range of 2.5 to 3.2, or a range of 2.8 to 3.2, or a range of 2.8 to 3.1. In this case, since the reforming water supplied to the evaporation section is limited, the latent heat of evaporation of the reforming water is suppressed, and the temperature of the CO oxidation removal section is easily maintained. S / C means the number of moles of reforming water charged into the reformer 2 / the number of moles of carbon components in the reforming fuel. If the S / C is less than 2.5, the amount of reforming water is too small, coking occurs in the catalyst in the reforming section, and carbonization may occur.

  An operation unit that is operated by an operator (for example, a user, a construction worker, or a maintenance operator) is provided, and the control device is exemplified by a mode in which the catalyst regeneration process is executed based on the operation of the operator to the operation unit. The The catalyst regeneration process is executed according to the operator's request. If the catalyst regeneration process is not sufficient once, it is possible to perform the catalyst regeneration process continuously or intermittently a plurality of times.

  An operation history storage element such as a memory for storing the operation history of the reformer is provided, and a mode in which the control device executes the catalyst regeneration process according to the operation history is exemplified. Examples of the operation history include at least one of the accumulated operation time, the number of activations, and the number of stops. Examples of the accumulated operation time include the accumulated operation time from the catalyst regeneration process executed last time, or the accumulated operation time from the time of installation of the reformer.

  An example is provided in which a reformed gas discharge path for discharging the reformed gas purified by the CO oxidation removal section to the reformed gas consumption section and an outlet valve provided in the reformed gas discharge path are exemplified. In this case, the control device does not discharge the entire amount of the reformed gas remaining in the CO oxidation removal section to the reformed gas discharge path by opening the outlet valve until the reformer is stopped or the next operation is started. In FIG. 5, the reformed gas is partially left in the CO oxidation removing section by closing the outlet valve. Examples of the reformed gas consuming section include a combustion section that heats the reformed section and a fuel cell.

  Examples of the catalyst supported on the CO oxidation removing unit include ruthenium, platinum, platinum-ruthenium and the like. A CO purification unit for reducing carbon monoxide in the reformed gas before the reaction in the CO oxidation removal unit is disposed upstream of the CO oxidation removal unit. A mode in which is left in the CO shift unit is exemplified. It is suppressed that the CO shift part becomes an excessive oxidizing atmosphere. Therefore, a change in the performance of the catalyst supported on the CO shift portion is suppressed.

  The CO shift part temperature detector which detects the temperature of a CO shift part is provided, and the form provided with the CO oxidation removal part temperature detector which detects the temperature of the said CO oxidation removal part is illustrated. During the operation of the reforming apparatus, the control device detects the oxygen in accordance with the temperature of the CO oxidation removal unit detected by the CO oxidation removal unit temperature detector or the temperature of the CO shift unit detected by the CO shift unit temperature detector. The form which controls the supply amount of the oxygen component supplied to a CO oxidation removal part from a supply part is illustrated.

  Embodiment 1 of the present invention will be specifically described below with reference to FIGS. The reformer according to the present embodiment is applied to a fuel cell system. As shown in FIG. 1, the fuel cell 1 is formed by assembling a plurality of membrane electrode assemblies 13 that sandwich a solid polymer membrane 10 having proton conductivity between a fuel electrode 11 and an oxidant electrode 12 in the thickness direction. Yes. Examples of the material of the solid polymer film 10 include a fluorocarbon resin (for example, perfluorosulfonic acid resin) or a hydrocarbon resin. The fuel cell 1 may be a system in which a plurality of sheet-like membrane electrode assemblies 13 are stacked in the thickness direction, or a system in which a plurality of tube-shaped membrane electrode assemblies 13 are arranged.

  As shown in FIG. 1, the reformer 2 includes a combustion unit 30 that functions as a heating unit formed by a combustion burner, and a reforming unit 34 that is heated by the combustion unit 30. The reforming unit 34 has a cylindrical shape having a central axis along the vertical direction, and reforms the reforming fuel to generate reformed gas. The reforming section 34 has a combustion passage 32 that faces the combustion section 30. A combustion passage 33 is formed coaxially so as to surround the reforming portion 34. A combustion passage 35 is coaxially formed outside the combustion passage 33 so as to communicate with the combustion passage 33. A cylindrical heat insulating portion 31 is formed coaxially between the combustion passage 33 and the combustion passage 35. Further, an evaporation portion 36 for evaporating the raw water is coaxially formed so as to surround the combustion passage 35. A CO oxidation removing unit 37 (also referred to as a CO selective oxidation unit) is coaxially formed around the evaporation unit 36.

  As shown in FIG. 1, the reformer 34 has an inner passage 34i, an outer passage 34p, and a turn-up portion 34m. The evaporation unit 36 is heated by the reforming unit 34 heated by the combustion unit 30. Since the cylindrical CO oxidation removal unit 37 is disposed so as to surround the evaporation unit 36, the evaporation unit 36 and the CO oxidation removal unit 37 exchange heat with each other. During operation of the reformer 2, since the temperature of the CO oxidation removing unit 37 is generally higher than the temperature of the evaporation unit 36 at which liquid phase water evaporates, the CO oxidation removing unit 37 is connected to the evaporation unit 36. Give heat. The outer peripheral portion of the CO oxidation removing portion 37 is covered with a cylindrical heat insulating material 39 (heat insulating portion) having a high heat insulating property in order to surround and retain the temperature. However, as shown in FIG. 2, the heat insulating material 39 is not provided in the vicinity of the inlet 37 i to which the reformed gas that has passed through the CO shift unit 5 is supplied in the CO oxidation removal unit 37. Therefore, the lower end 39u of the heat insulating material 39 does not reach the inlet 37i. The main reason is that the temperature of the reformed gas is slightly higher than the activation temperature of the catalyst 37e of the CO oxidation removing unit 37, and thus the reformed gas is cooled.

  The reforming unit 34 includes a carrier that supports a reforming catalyst 34e (for example, nickel-based or ruthenium-based) that promotes a reforming reaction. The active temperature range of the reforming catalyst 34e is generally 500 to 800 ° C., but is not limited thereto. If the temperature of the reforming unit 34 deviates greatly from the activation temperature range, the reforming reaction of the reforming unit 34 may be impaired. The reforming unit 34 performs steam reforming based on the reforming fuel and steam based on the following formula (1) to generate a reformed gas containing hydrogen. The reformed gas contains carbon monoxide. In the reforming section 34, the shift reaction of the following formula (2) also occurs.

  Furthermore, as shown in FIGS. 1 and 2, the reformer 2 functions as a heat exchange unit 4 disposed below the reforming unit 34 and a CO purification unit disposed below the heat exchange unit 4. A CO shift unit 5 and a warm-up unit 47 having an electric heater disposed between the CO shift unit 5 and the heat exchange unit 4 are provided. Here, the heat exchange unit 4 is provided downstream of the evaporation unit 36, and the CO shift unit 5 is provided downstream of the heat exchange unit 4.

  The CO shift unit 5 promotes a shift reaction using water vapor based on the following formula (2), and reduces CO contained in the reformed gas. The CO shift unit 5 includes a carrier that supports a shift catalyst 5e (for example, a copper-zinc catalyst). The active temperature range of the shift catalyst 5e is generally 160 to 300 ° C., but is not limited thereto. If the temperature of the CO shift unit 5 greatly deviates from the activation temperature range, the shift reaction of the CO shift unit 5 may be impaired, and carbon monoxide may not be sufficiently purified. The concentration of CO contained in the reformed gas purified by the CO shift unit 5 is generally 0.2 to 1% in terms of molar ratio, although it depends on the reforming fuel. It is not something that can be done. The CO shift unit 5 has a passage 5i, a passage 5v, and a turning portion 5m. The outlet 5p of the CO shift unit 5 and the oxidation air passage 75 are connected by a purification passage 400 via the second merge region M2.

The CO oxidation removing unit 37 is arranged downstream of the CO shift unit 5 and oxidizes CO contained in the reformed gas purified by the CO shift unit 5 based on the following equation (3). It promotes the reducing oxidation reaction. The CO oxidation removing unit 37 has a ceramic (for example, alumina) carrier that supports a catalyst 37e (for example, a ruthenium-based, platinum-based, platinum-ruthenium-based noble metal-based catalyst). In an oxygen-containing atmosphere, the activation temperature range of the catalyst 37e is generally 100 to 200 ° C. However, it is not limited to this. If the temperature of the CO oxidation removing unit 37 greatly deviates from the activation temperature range in the oxygen-containing atmosphere, the selective oxidation reaction in the CO oxidation removing unit 37 may be impaired. The concentration of CO contained in the reformed gas purified by the CO oxidation removing unit 37 is generally 10 ppm or less. However, it is not limited to this.
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

  Since the CO shift unit 5 is disposed upstream of the CO oxidation removing unit 37, when the reforming apparatus 2 is operated, the CO shift unit 5 is executed in the order of Expression (2) → Expression (3).

  According to the present embodiment, the CO shift unit 5 becomes hydrogen-rich during the operation of the reformer 2 and becomes a reducing condition. For this reason, if the catalyst 5e of the CO shift unit 5 is only slightly oxidized, the catalyst 5e is easily reduced during operation of the reformer.

  However, the catalyst 37e of the CO oxidation removing unit 37 is not easily reduced only during operation of the reformer. In a state where oxygen is supplied to the CO oxidation removing unit 37, an active temperature range (for example, 100 to 200 ° C.) of the catalyst 37e of the CO oxidation removing unit 37 exists. When this temperature is exceeded, it is said that it is preferable not to exceed 200 ° C. because the deterioration of the catalyst 37e easily proceeds in an oxidizing atmosphere.

  On the other hand, in a condition where oxygen is not supplied, that is, in an oxygen-deficient atmosphere, even if the catalyst 37e is heated and held in a temperature range that exceeds the above-described active temperature range, not only the deterioration is suppressed, but the catalyst 37e Reduced and regenerated.

  In this way, even if the reformer 2 is normally operated while oxygen is supplied to the CO oxidation removing unit 37, the reduction of the catalyst 37e of the CO oxidation removing unit 37 does not readily proceed. .

  In the above regeneration process, the catalyst regeneration temperature region of the catalyst 37e of the CO oxidation removing unit 37 is generally 190 ° C. or higher and 200 ° C. or higher. 220 degreeC or more is further more preferable, and 250 degreeC or more is still more preferable. However, the temperature varies depending on the composition of the catalyst 37e and is not limited.

  Next, the passage system will be described. As shown in FIG. 1, a fuel passage 62 connected to the fuel supply source 61 through a valve 25a is provided. The fuel of the fuel supply source 61 may be gaseous fuel, liquid fuel, or pulverized fuel. Specifically, hydrocarbon fuel and alcohol fuel are exemplified. For example, city gas, LPG, kerosene, methanol, ethanol, dimethyl ether, gasoline, biogas and the like are exemplified. The fuel passage 62 includes a combustion fuel passage 62 connected to the combustion section 30 of the reforming section 34 via the valve 25a and the pump 27a, a pump 27b (reforming fuel transfer element) to the inlet 4i of the heat exchange section 4, and desulfurization. And a reforming fuel passage 62 (reforming fuel supply unit) connected via the valve 62x and the valve 25b. An air passage 72 (oxygen supply unit) connected to the air supply source 71 is provided. The air passage 72 is connected to the combustion air passage 73 connected to the combustion unit 30 of the reforming unit 34 via the pump 27c, and to the inlet 37i of the CO oxidation removal unit 37 via the air purification filter 72x, the pump 27d, and the valve 25d. It has an oxidation air passage 75 (oxygen supply part).

  As shown in FIGS. 1 and 2, a reforming water passage 82 (water supply unit) is provided that connects the water tank 81 and the inlet 36i of the evaporation unit 36 via a pump 27m and a valve 25m. An anode gas passage 100 (reformed gas discharge passage) that connects the outlet 37p of the CO oxidation removing unit 37 and the inlet 11i of the fuel electrode 11 of the fuel cell 1 via a valve 25e (outlet valve downstream of the reformer 2). Is provided. The outlet 37p of the CO oxidation removing unit 37 is formed on the upper side of the CO oxidation removing unit 37 in the height direction. An off-gas passage 110 is provided that connects the outlet 11p of the fuel electrode 11 of the fuel cell 1 and the combustion unit 30 via a valve 25f. The off gas passage 110 discharges the anode off gas after the power generation reaction. A bypass passage 150 that connects the off gas passage 110 and the anode gas passage 100 via a valve 25h (an outlet valve downstream of the reformer 2) is provided.

  As shown in FIG. 1, a cathode gas passage 200 communicating with the air supply source 71 and the inlet 12i of the oxidant electrode 12 of the fuel cell 1 through a pump 27k and a valve 25k is provided. As shown in FIG. 1, a combustion exhaust gas passage 250 is provided for releasing the combustion exhaust gas combusted in the reforming section 34 to the outside. A steam passage 300 is provided that connects the outlet 36p of the evaporating section 36 of the reformer 2 and the reforming fuel passage 62 via the first merge region M1. The upper end portion 300 e of the water vapor passage 300 is connected to the outlet 36 p of the evaporation portion 36. The lower end portion 300f of the water vapor passage 300 is connected to the merge area M1. The pumps 27a, 27b, 27c, 27d, 27k, and 27m function as fluid conveying elements.

  As shown in FIGS. 1 and 2, the outlet 5 p of the CO shift unit 5 and the inlet 37 i of the CO oxidation removing unit 37 are connected by a purification passage 400. The reformed gas (hydrogen is the main component and contains carbon monoxide) discharged from the outlet 5p of the CO shift unit 5 flows upward in the direction of the arrow W2 through the purification passage 400, and passes through the second merge region M2 for CO oxidation. It is supplied to the inlet 37 i of the removing unit 37. The inlet 37 i is formed on the lower side in the height direction of the CO oxidation removing unit 37.

  Next, when the reforming apparatus 2 is started will be described with reference to FIG. In this case, the combustion air is supplied to the combustion unit 30 of the reforming unit 34 by the pump 27 c through the combustion air passage 73. Further, gaseous combustion fuel (combustible fuel) is supplied to the combustion section 30 of the reforming section 34 through the combustion fuel passage 62 by the valve 25a and the pump 27a. As a result, the combustion section 30 is ignited and heated, and as a result, the reforming section 34 is heated so as to be suitable for the reforming reaction. The evaporating unit 36 and the CO oxidation removing unit 37 together with the reforming unit 34 and the outer unit 35 are also heated to a high temperature.

  Thereafter, the reforming water (water before the reforming reaction) is supplied from the water tank 81 and the reforming water passage 82 to the inlet 36i of the evaporator 36 through the pump 27m and the valve 25m. The reformed water is steamed in the high temperature evaporator 36 of the reformer 2. The generated water vapor reaches the first merge region M1 through the water vapor passage 300 from the outlet 36p of the evaporation section 36. The first merge region M1 is a region where the steam or condensed water flowing through the steam passage 300 and the reforming fuel flowing through the reforming fuel passage 62 merge. On the other hand, the reforming fuel is supplied to the inlet 4i of the heat exchanging unit 4 through the desulfurizer 62x, the reforming fuel passage 62, and the first merge region M1 by the valve 25a, the pump 27b, and the valve 25b. In the first merge region M1, the reforming fuel in the reforming fuel passage 62 and the steam in the steam passage 300 are merged and mixed. The merged mixed fluid is supplied to the inlet 4 i of the heat exchange unit 4.

  The mixed fluid passes through the first passage 4 a on the low temperature side of the heat exchange unit 4. At this time, heat exchange is performed with the high-temperature reformed gas flowing through the second passage 4c on the high temperature side of the heat exchange unit 4. For this reason, the mixed fluid before the reforming reaction is heated. The mixed fluid flows into the outer passage 34p of the reforming portion 34, flows in the direction of arrow A1, flows into the inner passage 34i through the turn-up portion 34m, and flows in the direction of arrow A2. At this time, the mixed fluid in which the steam (or condensed water) and the reforming fuel are mixed becomes a hydrogen-rich reformed gas by the reforming reaction shown in (1). This reformed gas contains carbon monoxide.

  Further, the high-temperature reformed gas that has undergone the reforming reaction flows from the reforming section 34 into the heat exchanging section 4. That is, the high-temperature reformed gas passes through the second passage 4c on the high temperature side of the heat exchange unit 4 from the reforming unit 34, thereby heating the mixed fluid in the first passage 4a on the low temperature side. Further, the reformed gas flows into the CO shift unit 5 from the inlet 5 i of the CO shift unit 5 through the warm-up unit 47. In the CO shift unit 5, a shift reaction using water vapor is performed as shown in the above formula (2). As a result, carbon monoxide contained in the reformed gas is reduced, and the reformed gas is purified.

Further, the reformed gas purified in the CO shift unit 5 flows from the outlet 5p of the CO shift unit 5 through the purification passage 400 in the direction of the arrow W2 and reaches the second merge region M2. Further, the reformed gas merges with the oxidizing air (oxygen component, selective oxidizing air used for the selective reaction in the CO oxidation removing unit 37) in the oxidizing air passage 75 (oxygen supply unit) in the second merge region M2. . The second merge region M2 is a region where the reformed gas flowing through the purification passage 400 and the oxidation air (oxygen component) flowing through the oxidation air passage 75 merge. Then, the merged reformed gas flows into the CO oxidation removing unit 37 from an inlet 37 i formed at the lower part of the CO oxidation removing unit 37. In the CO oxidation removing unit 37, an oxidation reaction (CO + 1 / 2O ₂ → CO ₂ ) using oxygen is performed as shown in the above formula (3). As a result, CO contained in the reformed gas is purified and further reduced. The oxidation reaction is exothermic.

  The reformed gas thus purified is supplied as an anode gas from the outlet 37p of the CO oxidation removing section 37 to the inlet 11i of the fuel electrode 11 of the fuel cell 1 through the anode gas passage 100 and the valve 25e. The air functioning as the cathode gas is supplied to the inlet 12i of the oxidant electrode 12 of the fuel cell 1 through the cathode gas passage 200 by the pump 27k and the valve 25k. As a result, a power generation reaction occurs in the fuel cell 1 and electric energy is generated. The off gas after the power generation reaction of the anode gas (the gas discharged from the fuel cell 1) may contain hydrogen that has not undergone the power generation reaction. For this reason, the off gas is supplied to the combustion unit 30 of the reforming unit 34 through the off gas passage 110 and burned, and becomes a heat source of the combustion unit 30.

  In addition, at the time of starting the reforming apparatus 2, the stability of the reformed gas composition may not always be sufficient. For this reason, the valve 25e and the valve 25f are closed at the start of activation. In this state, the reformed gas discharged from the outlet 37p of the CO oxidation removal unit 37 passes through the valve 25h and is sent to the combustion unit 30 via the bypass passage 150 and the off-gas passage 110, and becomes a heat source for the combustion unit 30. . As time elapses from the start of the reforming device 2, the composition of the reformed gas becomes stable. In this case, the valve 25h is closed and the valves 25e and 25h are opened. For this reason, the reformed gas discharged from the outlet 37p of the CO oxidation removing unit 37 is supplied as an anode gas to the inlet 11i of the fuel electrode 11 of the fuel cell 1 through the anode gas passage 100 and the valve 25e to generate a power generation reaction. used.

  As shown in FIG. 1, a CO shift unit temperature detector 55 that detects a temperature T11 on the upstream side (inlet side of the passage 5i) of the CO shift unit 5 is provided. A CO shift portion temperature detector 39 for detecting a temperature T31 in the vicinity of the turning portion 5m of the CO shift portion 5 is provided. A CO oxidation removal unit temperature detector 38 for detecting the upstream temperature T12 of the CO oxidation removal unit 37 is provided. Further, a reforming unit temperature detector 31t for detecting the temperature T1 on the outlet side of the reforming unit 34 is provided. A temperature detector 65 that detects the temperature T2 of the first merge region M1 where the steam and the reforming fuel merge is provided.

  Now, according to the present embodiment, the reformed gas mainly containing hydrogen containing carbon monoxide is generated during operation of the reformer. When the temperature T11 of the CO shift unit 5 is low and lower than the activation temperature range, the CO removal performance is not sufficient. Therefore, the control device 500 raises the temperature of the CO shift unit 5 by the heater of the warm-up unit 47. . Thereby, the CO shift part 5 is maintained in an active temperature range.

  The signals of the temperatures T11 and T31 of the CO shift unit 5 detected by the CO shift unit temperature detectors 55 and 39, the signal of the temperature T12 of the CO oxidation removal unit 37 detected by the CO oxidation removal unit temperature detector 38, and the reforming The signal of the temperature T1 of the reforming unit 34 detected by the part temperature detector 31t and the signal of the temperature T2 of the first joining region M1 detected by the temperature detector 65 are input to the control device 500, respectively. The control device 500 controls the flow rate of air (oxygen-containing gas, oxygen component) supplied from the oxidation air passage 75 (oxygen supply unit) to the CO oxidation removal unit 37. Thereby, the temperature of the CO shift part 5 arrange | positioned upstream of the CO oxidation removal part 37 is controlled.

(CO purification in the CO oxidation removing unit 37)
(A) Specifically, during operation of the reformer, when the temperature T11 of the CO shift unit 5 is low and lower than its activation temperature range, the control device 500 transmits the CO from the oxidation air passage 75 to the CO. Control is performed to increase the flow rate of the air (oxygen-containing gas) supplied to the oxidation removing unit 37. Thereby, the reaction in the CO oxidation removing unit 37 is promoted. Since this reaction is an oxidation reaction and is a reaction accompanied by heat generation, the amount of heat generated in the CO oxidation removal unit 37 increases. Accordingly, the amount of heat transferred from the relatively high temperature CO oxidation removing unit 37 to the relatively low temperature evaporation unit 36 is increased. This is because the CO oxidation removal unit 37 and the evaporation unit 36 are adjacent to each other so that the CO oxidation removal unit 37 is positioned outside the evaporation unit 36 as shown in FIG.

  During the operation of the reformer, the evaporating unit 36 evaporates the reformed water. Therefore, the evaporating unit 36 is generally maintained in a temperature range of about 100 ° C. due to the influence of latent heat of evaporation of the reformed water. And since the high temperature reformed gas which passed through the CO shift part 5 is supplied to the CO oxidation removal part 37 from the inlet 37i, the temperature of the CO oxidation removal part 37 becomes high. For this reason, the CO oxidation removal unit 37 is on the relatively high temperature side, and the evaporation unit 36 is on the relatively low temperature side. Therefore, the amount of heat that the CO oxidation removing unit 37 gives to the evaporation unit 36 increases. As a result, the amount of heat given to the reforming water in the evaporation section 36 increases. Therefore, vaporization is promoted in the evaporation section 36, the liquid phase moisture ratio is relatively decreased, and the gas phase moisture ratio is relatively increased.

  Here, in the heat exchanging section 4, the high-temperature reformed gas flowing through the second passage 4c and the mixed fluid flowing through the first passage 4a exchange heat with each other as described above. When the ratio of gas-phase moisture contained in the mixed fluid is relatively increased, the amount of latent heat of vaporization for vaporizing liquid-phase moisture is reduced, and the low-temperature gas is reduced from the reformed gas on the high temperature side. The amount of heat transferred to the mixed fluid on the side is reduced, and as a result, the temperature of the heat exchange unit 4 is relatively increased. Therefore, the temperature of the reformed gas heading toward the CO shift unit 5 through the second passage 4c of the heat exchange unit 4 relatively increases. Accordingly, the temperatures T11 and T31 of the CO shift unit 5 are relatively increased.

  On the other hand, when the ratio of the liquid phase moisture contained in the mixed fluid is relatively increased, the amount of latent heat of vaporization for vaporizing the liquid phase moisture increases, and the heat exchange unit 4 , The amount of heat transferred from the reformed gas on the high temperature side to the mixed fluid on the low temperature side increases, and as a result, the temperature of the heat exchange unit 4 relatively decreases. Therefore, the temperature of the reformed gas toward the CO shift unit 5 through the second passage 4c of the heat exchange unit 4 relatively decreases. Accordingly, the temperature T11 of the CO shift unit 5 relatively decreases.

  (B) On the contrary, during operation of the reformer, even when the temperature T11 of the CO shift unit 5 is excessively high and exceeds the activation temperature range, the control device is configured to relatively lower the temperature T11. 500 works. That is, when the temperature T11 of the CO shift unit 5 is excessively high, the control device 500 decreases the flow rate of the air supplied from the oxidation air passage 75 to the CO oxidation removal unit 37. For this reason, the oxidation reaction in the CO oxidation removing unit 37 is suppressed, and the heat generation amount is suppressed. Accordingly, the amount of heat given to the evaporation unit 36 by the CO oxidation removing unit 37 is reduced. As a result, the amount of heat given to the reforming water in the evaporation section 36 is reduced. Therefore, in the evaporation part 36, the liquid-phase water ratio increases relatively, and the vapor-phase water ratio decreases relatively. In this case, in the heat exchanging unit 4, the amount of heat transferred from the high temperature side reformed gas flowing through the second passage 4c to the low temperature side mixed fluid flowing through the first passage 4a increases. As a result, the temperature of the heat exchange unit 4 is relatively lowered. Therefore, the temperature of the reformed gas that goes to the CO shift unit 5 via the heat exchange unit 4 is relatively lowered, and the temperature T11 of the CO shift unit 5 is relatively lowered.

  According to the above-described embodiment, when the temperature T11 of the CO shift unit 5 is low, the control device 500 increases the flow rate of the air (oxygen-containing gas) supplied from the oxidation air passage 75 to the CO oxidation removal unit 37. Let As a result, the temperature T11 of the CO shift unit 5 rises, and the CO shift unit 5 is well maintained at a temperature suitable for the activation temperature range. When the temperature T11 of the CO shift unit 5 is high, the control device 500 decreases the flow rate of the air (oxygen-containing gas) supplied from the oxidation air passage 75 to the CO oxidation removal unit 37. As a result, the temperature T11 of the CO shift unit 5 decreases, and the CO shift unit 5 is well maintained at a temperature suitable for the activation temperature range. In controlling the air flow rate, the conveying capacity of the pump 27d and / or the opening of the valve 25d in the oxidizing air passage 75 are controlled.

(About catalyst regeneration treatment)
The control device 500 described above also functions as a means for regenerating the catalyst 37e of the CO oxidation removing unit 37. A control device 500 shown in FIG. 1 has a start switch 504 for starting the reformer, a stop switch 505 for stopping the operation of the reformer, and a regeneration switch 506 for starting the catalyst regeneration process at an arbitrary time. .

If the reforming apparatus 2 is used for a long period of time, the catalyst 37e of the CO oxidation removing unit 37 may be gradually oxidized, and the performance may be deteriorated. Therefore, every time the operation of the reformer is stopped, the control device 500 reduces and regenerates the catalyst 37e of the CO oxidation removing unit 37, so that the following conditions (i), (ii), and (iii) are satisfied. Perform catalyst regeneration. In this case, (i), (ii), and (iii) may be performed concurrently, or may be performed while being partially shifted in time, or may be performed separately in time. May be. (Iii) (iii) may be executed after executing (ii). (Iii) (iii) may be executed after executing (i).
(I) The control device 500 stops supplying reforming fuel to the reforming device 2 and stops supplying reforming water to the evaporation section 36, thereby stopping the reforming operation. The control device 500 opens the valve 25h (outlet valve of the reformer) for a predetermined time. After a predetermined time has elapsed, the valve 25h is closed while the valves 25e and 25f are closed. Thereby, the reformed gas existing in the reformer 2 is not completely discharged. As a result, a certain amount of the reformed gas remains in the reformer 2, particularly in the CO oxidation removal unit 37. In this way, the reforming reaction is stopped. Thus, since the reformed gas remains in the CO oxidation removing unit 37, even if the reformer 2 is cooled, the negative pressure of the reformer 2 is suppressed. Therefore, it becomes difficult for air (oxygen component) to enter the reformer 2, and the oxidation of the catalyst 37e is suppressed.
(Ii) The control device 500 closes the valve 25d and turns off the pump 27d. As a result, the control device 500 stops supplying the oxidizing air (oxygen component) to the CO oxidation removing unit 37. In this case, the oxidation of the catalyst 37e in the CO oxidation removing unit 37 is suppressed. For this reason, the reduction of the oxidized portion of the catalyst 37e easily proceeds.
(Iii) The control device 500 increases the CO to a minimum temperature Tx or higher (for example, 200 ° C. or higher, preferably 220 ° C. or higher, more preferably 250 ° C. or higher) in the catalyst regeneration temperature region for regenerating the catalyst 37e of the CO oxidation removing unit 37. The catalyst 37e of the oxidation removing unit 37 is maintained. Here, if the temperature T12 of the CO oxidation removal unit 37 is less than the catalyst regeneration temperature region, the control device 500 forcibly supplies the combustion unit 30 with combustion fuel and combustion air for combustion. Thereby, the reforming unit 34 and the CO oxidation removing unit 37 are forcibly heated. As a result, the temperature T12 of the CO oxidation removing unit 37 is maintained for a predetermined time tx in the catalyst regeneration temperature region (temperature Tx or higher).

  Thus, according to this embodiment, even when the operation of the reformer is stopped, the temperature drop of the catalyst 37e is suppressed, and the catalyst 37e is maintained in the catalyst regeneration temperature region. For this reason, the reduction of the oxidized portion of the catalyst 37e proceeds and the catalyst 37e is regenerated. Furthermore, since the CO oxidation removing unit 37 is surrounded by the heat insulating material 39, it is advantageous to maintain the temperature T12 of the CO oxidation removing unit 37 in the catalyst regeneration temperature region (temperature Tx or higher). Moreover, the reforming water is not supplied to the evaporation section 36 when the reformer 2 is stopped. For this reason, although the evaporation unit 36 and the CO oxidation removal unit 37 are adjacent to each other, the evaporation unit 36 is prevented from excessively cooling the CO oxidation removal unit 37. Therefore, it is advantageous to maintain the temperature T12 of the CO oxidation removing unit 37 in the catalyst regeneration temperature region, which is advantageous for regeneration of the catalyst 37e. Furthermore, the evaporation part 36 becomes high temperature by combustion in the combustion part, and the heat is given to the CO oxidation removing part 37. Therefore, the CO oxidation removing unit 37 has a high temperature that is more advantageous for the regeneration process.

  FIG. 3 shows a second embodiment. The present embodiment basically has the same configuration and operational effects as the first embodiment. According to the present embodiment, as in the first embodiment, the control device 500 performs the catalyst regeneration process in the operation of stopping the reforming device 2.

  FIG. 3 shows a flowchart executed by the control device 500 when the operation of the reformer is finished. The flowchart is an example, and the present invention is not limited to this. As shown in FIG. 3, the control device 500 reads the status of the stop switch 505 (reformer operation stop element, fuel cell system operation stop element) on the operation panel (step S102). If stop switch 505 is operated (YES in step S104), control device 500 outputs a stop command for reforming device 2 (step S106). After waiting for a predetermined time ta (step S108), the control device 500 performs a minimum load power generation process as a final operation (step S110). After a predetermined time tb has elapsed (step S112), the control device 500 supplies air to the combustion unit 30 from the combustion air passage 73, closes the valve 25a, turns off the pump 27a, and supplies combustion fuel to the combustion unit 30. Is stopped (step S114). Thereby, the combustion part 30 is extinguished. In this case, the control device 500 turns off the pump 27m and closes the valve 25m. Therefore, the reforming water is not supplied from the reforming water passage 82 to the evaporation unit 36, so that the excessively low temperature of the evaporation unit 36 is suppressed, and consequently heat transfer from the CO oxidation removing unit 37 to the evaporation unit 36 is suppressed. . For this reason, the temperature T12 of the CO oxidation removing unit 37 is easily maintained at a high temperature (catalyst regeneration temperature region), which is advantageous for reducing the catalyst 37e. Furthermore, since the supply of the reforming water to the evaporation unit 36 is stopped, the liquid-phase water supplied from the inlet 4i to the first passage 4a of the heat exchange unit 4 is reduced, so that the temperature of the heat exchange unit 4 is reduced. Also, the temperature T11 of the CO shift unit 5 is maintained at a high temperature, and the temperature T12 of the CO oxidation removing unit 37 is maintained at a high temperature.

  Here, in step S <b> 114, the control device 500 continues to drive the pump 27 c of the combustion air passage 73 and continues to supply air from the combustion air passage 73 to the combustion unit 30. At this point, the combustion unit 30 is extinguished. The air supplied to the combustion unit 30 is warmed by the residual heat of the combustion unit 30 and the residual heat of the reforming unit 34. Heated heated air (heated gas) is discharged from the combustion exhaust gas passage 250 through the combustion passages 32 and 33. In this case, the CO selective oxidation unit 37 is warmed by the heated air, and the temperature drop is suppressed. Therefore, it is advantageous to maintain the CO selective oxidation unit 37 in the catalyst regeneration temperature region and reduce the catalyst 37e. In step S114, the valves 25e and 25f (closing valves for closing the inlet and outlet of the fuel electrode of the fuel cell) are closed. Thereafter, after waiting for a predetermined time tc (step S116), the control device 500 closes the valve 25h (outlet valve) (step S118). As a result, the reformed gas existing in the reformer 2 remains in the reformer 2 (including the CO oxidation removing unit 37).

  The residual heat of the reformer 2 may vaporize the water remaining in the reformer 2 and increase the pressure. Therefore, the control device 500 reads the output value of the pressure sensor 100x that measures the internal pressure of the reformer 2, and determines whether the internal pressure of the reformer 2 exceeds a predetermined pressure Pd (for example, Pd = 5 kPa) (step S120). . Until the internal pressure of the reformer 2 decreases to the predetermined pressure Pd, the control device 500 opens the valve 25h and closes the valve 25h and the off-gas passage 110 through the valve 25h while the valve 25e is closed. After that, it is supplied to the combustion unit 30. The combustion unit 30 is connected to the outside from the combustion exhaust gas passage 250. In this way, steps S118 and S120 are repeated, and the internal pressure of the reformer 2 is reduced to a predetermined pressure. The pressure sensor 100x that measures the internal pressure of the reformer 2 is provided on the downstream side of the reformer 2, that is, in a branch region between the anode gas passage 100 and the bypass passage 150. The pressure sensor 100x may be closer to the reformer 2 than the valves 25f and 25e.

  If the internal pressure of the reformer 2 reaches the predetermined pressure Pd or less due to the opening of the valve 25h (NO in step S120), the process proceeds to step S124 because an appropriate amount of reformed gas remains in the reformer 2. Then, it is determined whether or not the temperature T12 of the CO oxidation removing unit 37 is in the catalyst regeneration temperature region and a predetermined time tx (5 minutes) corresponding to the catalyst regeneration time has elapsed. Specifically, the temperature T12 of the CO oxidation removing unit 37 exceeds the minimum threshold temperature Tx (for example, Tx = 200 ° C., preferably 220 ° C., more preferably 250 ° C.) in the catalyst regeneration temperature region, The control device 500 determines whether or not a regeneration condition that the state continues continuously for a predetermined time tx (for example, tx = 5 minutes) or longer is satisfied.

  When the above regeneration conditions are not satisfied (NO in step S124), the control device 500 performs an ignition operation for forcibly reigniting the combustion unit 30 (step S126). As a result, the temperature T12 of the CO oxidation removing unit 37 is forcibly increased. In the ignition operation, the flow rate per unit time of the combustion air supplied to the combustion unit 30 is changed to the flow rate during ignition. Further, the valve 25 a is opened, the pump 27 a is driven, and the combustion fuel is supplied from the combustion fuel passage 62 to the combustion unit 30. Control device 500 determines whether or not combustion unit 30 has ignited (step S128).

  If the combustion unit 30 has not ignited (NO in step S128), the process returns to step S126. If combustion unit 30 is ignited (YES in step S128), control device 500 turns off the igniter (step S130). Next, the control device 500 controls the flow rate per unit time of the combustion air supplied to the combustion unit 30 so as to be suitable for the combustion of the combustion unit 30. The flow rate per unit time of the fuel for combustion supplied to the combustion unit 30 is controlled (step S132). Then, the controller 500 determines whether or not the temperature T1 of the reforming unit 34 exceeds a predetermined temperature Tw (for example, Tw = 500 ° C.) (step S134). If the temperature T1 of the reforming unit 34 exceeds a predetermined temperature Tw (eg, Tw = 500 ° C.) (YES in step S134), the control device 500 is supplied to the combustion unit 30 to cool the reforming unit 34. The supply of combustion fuel is stopped and the combustion unit 30 is extinguished. Further, the flow rate per unit time of the combustion air supplied to the combustion unit 30 is increased to promote the cooling of the reformer 2 (step S136). At this time, the combustion section 30 is extinguished, but the air is warmed by the residual heat of the combustion section 30 and the residual heat of the reforming section 34. Heated heated air (heated gas) is discharged from the combustion exhaust gas passage 250 through the combustion passages 32, 33, and 35. The warmed air (heated gas) suppresses the temperature decrease of the CO selective oxidation unit 37, which is advantageous for maintaining the CO selective oxidation unit 37 in the catalyst regeneration temperature region. After the predetermined time td has elapsed, the process returns to step S124. By the ignition operation shown in step S126 described above, the temperature T12 of the catalyst 37e of the CO selective oxidation unit 37 becomes the catalyst regeneration temperature region and is maintained for a predetermined time tx or more.

  When the temperature T12 of the CO oxidation removing unit 37 exists in the catalyst regeneration temperature region for a predetermined time tx (YES in step S124), it can be considered that regeneration of the catalyst 37e has been completed, so the temperature T1 of the reforming unit 34 is Tx. The controller waits until it is cooled below (for example, Tx = 200 ° C.) (step S140). If the temperature T1 of the reforming unit 34 is cooled below Tx (YES in step S140), it is determined whether the internal pressure of the reformer 2 is less than a predetermined pressure Pc (for example, Pc = 4 kPa) (step S142). If the pressure is equal to or higher than a predetermined pressure Pc (for example, Pc = 4 kPa) (NO in step S142), the internal pressure is good and the negative pressure of the reforming unit 34 is prevented, so the control device 500 is in the standby mode (step S148). Migrate to

  If the internal pressure of the reformer 2 is less than a predetermined pressure Pc (for example, Pc = 4 kPa) (YES in step S142), the internal pressure is too low, so the reforming fuel before the reforming reaction that has passed through the desulfurizer 62x is reformed. To the unit 34 (step S144). If the internal pressure of reforming device 2 exceeds a predetermined pressure Pd (for example, Pd = 5 kPa) (YES in step S146), control device 500 shifts to a standby mode (step S148).

  Therefore, when the inside of the reformer 2 becomes negative pressure, the outside air may enter the interior of the reformer 2 and cause the oxidation of the catalyst to proceed. However, since the reforming fuel (13A) is sealed inside the reforming device 2, even if the reforming device 2 is cooled to the normal temperature range after the operation of the reforming device, the inside of the reforming device 2 remains. Negative pressure is suppressed, entry of outside air into the reformer 2 is suppressed, and oxidation of the catalyst is suppressed.

  According to the flowchart shown in FIG. 3, since the reforming water is not supplied to the evaporation unit 36 of the reformer 2 from step S114 to step S148, the evaporation unit 36 is in a dry state, and the CO oxidation removal unit 37 Contributes to maintaining temperature.

  As described above, according to the present embodiment, the control device 500 performs the catalyst regeneration process for reducing and regenerating the catalyst 37e of the CO oxidation removing unit 37. In particular, every time the operation of the reformer is stopped, the control device 500 performs the catalyst regeneration process. For this reason, even if the use period of the reformer is extended, deterioration of the catalyst 37e of the CO oxidation removing unit 37 is suppressed. Therefore, in the reforming operation of the reformer, the catalyst 37e of the CO oxidation removing unit 37 functions well, and the concentration of carbon monoxide remaining in the reformed gas is reduced.

  Furthermore, according to the present embodiment, the control device 500 continues to drive the pump 27c of the combustion air passage 73 even though the combustion unit 30 is extinguished and the operation of the reformer is stopped. Air is supplied to the combustion unit 30 from the combustion air passage 73. At this time, although the combustion unit 30 is extinguished, the air supplied to the combustion unit 30 is warmed by the residual heat of the combustion unit 30 and the residual heat of the reforming unit 34. In this case, temperature reduction of the CO selective oxidation unit 37 is suppressed, and an advantage that is advantageous for maintaining the CO selective oxidation unit 37 in the catalyst regeneration temperature region is obtained, which is advantageous for regeneration of the catalyst 37e.

  According to the present embodiment, the memory 502 that functions as an operation history storage element that stores the operation history of the reformer 2 is mounted on the control device 500. In accordance with the operation history of the reforming apparatus 2 stored in the memory 502, the control apparatus 500 performs a catalyst regeneration process. As the operation history, the accumulated operation time is exemplified, and specifically, the accumulated operation time from the regeneration of the catalyst regeneration process executed last time or the accumulated operation time from the time when the reformer 2 is installed is used. When the cumulative operation time is short, control device 500 sets predetermined time tx in step S124 to be short. When the cumulative operation time is long, the control device 500 performs the catalyst regeneration process for a long time in order to set the predetermined time tx in step S124 to be long. In this case, the catalyst 37e of the CO selective oxidation unit 37 is well reduced and regenerated.

  The catalyst 5e in the CO shift unit 5 may be oxidized in an oxygen atmosphere even at room temperature. In this respect, according to the present embodiment, when the operation of the reformer is stopped as described above, the reformed gas (hydrogen) remains in the CO shift unit 5 and the inside of the CO shift unit 5 An oxidizing atmosphere is avoided. Therefore, it is advantageous to suppress the deterioration of the catalyst 5e in the CO shift unit 5.

  Since this embodiment has basically the same configuration and operation effects as the first and second embodiments, FIGS. 1 to 3 are applied mutatis mutandis. According to the present embodiment, the catalyst regeneration process is performed in the stop operation for stopping the operation of the reformer 2, as in the first and second embodiments. Further, when the regeneration switch 506 functioning as the catalyst regeneration processing start means is operated by the operator, even if the fuel cell 1 is in the power generation operation, the control device 500 uses this as a trigger based on the above-described flowchart. The reforming operation is stopped, and a catalyst regeneration process for reducing and regenerating the catalyst 37e is performed.

  For example, when the voltage tends to decrease during power generation, the regeneration switch 506 is operated by the operator during maintenance such as replacement of parts of the fuel cell system or during periodic maintenance. Further, since the oxidation of the catalyst 37e proceeds when the reformer is not used for a long period of time, the controller 500 regenerates the catalyst 37e of the CO oxidation removing unit 37 in accordance with the operation of the start switch 504 that starts the reformer. The catalyst regeneration treatment to be performed may be performed.

  FIG. 4 shows a fourth embodiment. The present embodiment basically has the same configuration and operational effects as the first embodiment. According to the present embodiment, as in the first embodiment, the control device 500 performs the catalyst regeneration process when the operation of the reformer 2 is stopped. Further, when the voltage of the fuel cell 1 is lowered (for example, when the voltage of all the cells is lowered) even though the reformer is in operation (operating of the fuel cell system), this is the case. Using the signal as a trigger signal, the control device 500 performs the catalyst regeneration process. Further, the controller 500 performs the catalyst regeneration process when the reformer is started.

  FIG. 4 shows a flowchart of the catalyst regeneration process executed when the reformer 2 is started. The flowchart is not limited to this. As shown in FIG. 4, the control device 500 reads the start switch 504 for starting the reforming device 2 (step SB102). When start switch 504 is operated to the start side (step SB104), control device 500 outputs a start command (step SB106). The control device 500 determines whether or not the warm-up by the heater of the warm-up unit 47 can be started (step SB108). When the warm-up may be started, the heating control by the heater of the warm-up unit 47 is started (step SB110). Next, a small amount of reforming water is introduced into the evaporation section 36 to start generation of water vapor (step SB112). While supplying combustion air to the combustion part 30, the fuel for combustion is controlled and the combustion part 30 is burned (step SB114). Since the reforming unit 34 is gradually warmed, the amount of reforming water supplied to the evaporation unit 36 is increased and the reforming fuel is controlled (step SB116). The oxidizing air is not input to the CO oxidation removing unit 37 (step SB118). Steps SB102 to 118 are the same as the normal activation operation.

  In this case, S / C = 3 is set as a target value, and the flow rate of the reforming water supplied to the evaporation unit 36 is limited to a small amount (step SB118). Since the target value is S / C = 3, the flow rate of the reforming water introduced into the evaporation section 36 is limited to the minimum necessary for preventing coking, and is small. In this case, since coking is suppressed and the reforming water is small, the latent heat of evaporation is small, the temperature of the CO selective oxidation unit 37 is suppressed, and the regeneration of the catalyst 37e is advantageous. Further, the oxidizing air is not input to the CO selective oxidation unit 37 (step SB118). This is because the catalyst 37e of the CO selective oxidation unit 37 is reduced. In the flowchart shown in FIG. 4, from step SB118 to step SB130, with S / C = 3 as a target value, the reformed water supplied to the reformer 2 to maintain the temperature of the CO selective oxidation unit 37 in the high temperature range. The reforming water and the reforming fuel are supplied to the reforming apparatus 2 while minimizing the required amount. The S / C target value is set to S / C = 3, but may be changed within the range of 2.5 to 3.2 and within the range of 2.5 to 3.0 as necessary. it can.

  Further, it waits until the CO shift unit 5 reaches the appropriate temperature range (step SB120). The appropriate temperature region is a region where the temperature T11> TK1 (for example, 250 ° C.) and the temperature condition of T31> TK2 (for example, 200 ° C.) are satisfied. When this temperature condition is satisfied, the heater of the warm-up unit 47 is turned off (step SB122).

  Next, the control device 500 stands by until the temperature condition of the reformer 2 reaches the catalyst regeneration temperature region (step SB124). The catalyst regeneration temperature region is a region where the conditions of temperature T11> TK3 (for example, 180 ° C.), temperature T31> TK4 (for example, 210 ° C.), and temperature T12> TK5 (for example, 250 ° C.) are satisfied. When this catalyst regeneration temperature condition is satisfied (YES in step SB124), timer 1 is started (step SB126). The controller 500 determines whether or not the timer 1 has passed a predetermined reproduction processing time tk1 (for example, 30 minutes) (step SB128). Steps SB126 and SB128 function as measuring means for measuring the elapsed time in the catalyst regeneration temperature region.

  If the regeneration processing time tk1 has not elapsed, the controller 500 determines again whether or not the above-described catalyst regeneration temperature condition is satisfied (step SB130). If the catalyst regeneration temperature condition is not satisfied, the control device 500 starts heating control by the heater of the warm-up unit 47 (step SB132). This forcibly raises the temperature of the CO shift unit 5 and the CO selective oxidation unit 37 to the catalyst regeneration temperature region. When the regeneration processing time tk1 (for example, 30 minutes) has elapsed, the control device 500 outputs an end signal indicating that the reduction of the catalysts 37e and 5e has ended (step SB134), and returns to the main routine. In this case, the fuel cell 1 may or may not proceed to the power generation operation mode.

  Summarizing the above, according to this embodiment, as can be understood from the flowchart of FIG. 5, the start operation of the start switch 504 → the catalyst regeneration temperature region where the temperature T12 of the CO selective oxidation unit 37 exceeds TK5 (for example, 200 ° C.). Start of regeneration process of the catalyst 37e of the CO selective oxidation unit 37 (required minimum amount of reforming water to be supplied to the evaporation unit 36) → elapse of a predetermined time → end of regeneration process of the catalyst 37e → improvement of supply to the evaporation unit 36 The quality water is increased little by little. The temperature T12 of the CO selective oxidation unit 37 is lowered below TK6 (for example, 200 ° C.) which is the upper limit of the active temperature range in the oxidizing atmosphere. → Oxidation air is supplied to the CO selective oxidation unit 37. → The order of operation is to start and end.

  FIG. 5 shows a fifth embodiment. The present embodiment basically has the same configuration and operational effects as the first embodiment. According to the present embodiment, as in the first embodiment, the control device 500 performs the catalyst regeneration process when the operation of the reformer is stopped. Further, the catalyst regeneration process is performed even when the reformer is started.

  FIG. 5 shows a flowchart for performing the catalyst regeneration process when the reformer is started. The first half of FIG. 5 is common to the flowchart shown in FIG. Description of common parts is omitted. In step SB128, control device 500 determines whether or not timer 1 has passed a predetermined reproduction processing time tk1 (for example, 30 minutes) (step SB128). If the regeneration processing time tk1 has elapsed, since the reduction of the touch 37e of the CO selective oxidation unit 37 has been completed, the process proceeds to step SB140, and the control device 500 supplies a small amount of reforming water to be supplied to the evaporation unit 36. Increase it step by step. Each time through step SB140, the reforming water is increased by a small amount. The control device 500 determines whether or not the shift unit 5 is in the proper temperature region and the CO selective oxidation unit 37 is in the proper temperature region (step SB142). Specifically, temperature T11> TK3 (for example, 180 ° C.), temperature T31> TK3 (for example, 180 ° C.), temperature T12 <TK6 (for example, 200 ° C.), and temperature T2 <TK7 (for example, 105 ° C.). The controller 500 determines whether or not the temperature condition (CO oxidation removal temperature condition) is satisfied (step SB142).

  If this temperature condition is satisfied (YES in step SB142), the temperature T12 of the CO selective oxidation unit 37 is lower than the temperature TK6 (for example, 200 ° C.). For this reason, the control device 500 inputs the oxidizing air into the CO selective oxidation unit 37, and performs oxidation removal of oxygen monoxide contained in the reformed gas in the CO selective oxidation unit 37 (step SB144).

  When this temperature condition is satisfied, the timer 2 starts (step SB146). Control device 500 determines whether or not timer 2 has passed a predetermined time tk2 (for example, 90 seconds) (step SB148). If the predetermined time tk2 has not elapsed, temperature T11> TK3 (for example, 180 ° C.), temperature T31> TK3 (for example, 180 ° C.), temperature T12 <TK6 (for example, 200 ° C.), and temperature T2 <TK7 The controller 500 determines whether or not the temperature condition (for example, 105 ° C.) is satisfied (step SB150). When time tk2 has elapsed (step SB148), an activation end signal is output (step SB152), and the process returns to the main routine.

  Summarizing the above, according to this embodiment, as can be understood from the flowchart of FIG. 5, the start operation of the start switch 504 → the catalyst regeneration temperature region where the temperature T12 of the CO selective oxidation unit 37 exceeds TK5 (for example, 200 ° C.). Start of regeneration process of the catalyst 37e of the CO selective oxidation unit 37 (required minimum amount of reforming water to be supplied to the evaporation unit 36) → elapse of a predetermined time → end of regeneration process of the catalyst 37e → improvement of supply to the evaporation unit 36 The quality water is increased little by little. The temperature T12 of the CO selective oxidation unit 37 is lowered below TK6 (for example, 200 ° C.) which is the upper limit of the active temperature range in the oxidizing atmosphere. → Oxidation air is supplied to the CO selective oxidation unit 37. → The order of starting and finishing.

  (Others) The above-described fuel cell system may be used in a vehicle or stationary. The above reformer is an example applied to a fuel cell system, but is not limited to this, and may be applied to other systems such as a hydrogen production system. The following technical idea can also be grasped from the above description.

  (Additional Item 1) It is contained in a reformer that contains hydrogen as a main component and also contains a reformed gas containing carbon monoxide from reforming fuel, and a reformed gas formed by the reformer. A CO oxidation removal unit having a catalyst for reducing carbon monoxide from the reformed gas by oxidizing carbon monoxide in the first temperature region and in an oxygen-containing atmosphere, and oxygen for supplying an oxygen component to the CO oxidation removal unit A reformer comprising: a supply unit; and a control device that performs a catalyst regeneration process for regenerating the catalyst in the CO oxidation removing unit. In this case, the temperature range of the catalyst regeneration process is relatively higher than the first temperature range or the first temperature range, and the catalyst of the CO oxidation removal unit is regenerated.

  (Additional Item 2) The reformer according to Additional Item 1, wherein an operation history storage element for storing the operation history of the reformer is provided, and the control device executes a catalyst regeneration process according to the operation history. When it is estimated from the operation history that the catalyst change is severe, the catalyst regeneration processing time is lengthened. When it is estimated from the operation history that there is little catalyst change, the time for the catalyst regeneration process is shortened. There may be provided means for instructing or warning the execution of the catalyst regeneration process according to the operation history.

  (Additional Item 3) A reformer for generating reformed gas containing hydrogen monoxide and containing carbon monoxide from the reforming fuel, and a reformed gas formed by the reformer. A CO oxidation removal unit having a catalyst for reducing carbon monoxide from the reformed gas by oxidizing carbon oxide in the first temperature region and in an oxygen-containing atmosphere, and an oxygen supply for supplying an oxygen component to the CO oxidation removal unit And a control device for performing a catalyst regeneration process for regenerating the catalyst of the CO oxidation removing unit, and carbon monoxide is reduced in the CO oxidation removing unit and the reformed gas is supplied as the anode gas and the cathode gas is supplied. A fuel cell system comprising a fuel cell for generating power.

  The present invention can be used for a reformer used in a fuel cell system, a hydrogen generation system, or the like.

1 is a system diagram of a reformer according to Embodiment 1. FIG. 1 is a system diagram of a main part of a reforming apparatus according to Embodiment 1. FIG. 7 is a flowchart of a catalyst regeneration process that is executed by the control device when the operation of the reformer is stopped, according to the second embodiment. FIG. 9 is a flowchart of a catalyst regeneration process executed by the control device during operation of the reformer according to the fourth embodiment. 10 is a flowchart of a catalyst regeneration process that is executed by the control device during operation of the reformer according to the fifth embodiment.

Explanation of symbols

  1 is a fuel cell, 2 is a reformer, 25e and 25f are valves (outlet valves) 3 is a reformer, 30 is a combustion section (heating section), 31 is a reforming section, 36 is an evaporation section, and 37 is CO oxidation Removal part, 39 is a heat insulating material (heat insulating part), 4 is a heat exchange part, 5 is a CO shift part (CO purification part), 62 is a fuel passage, 72 is an air passage (oxygen supply part), 81 is a water tank, 82 Is a reforming water passage (reforming water supply unit), 100 is an anode gas passage (reforming gas discharge passage), 200 is a cathode gas passage, 400 is a purification passage, 500 is a control device, and 31t is a reforming unit temperature detector. , 38 denotes a CO oxidation removal part temperature detector, 55 denotes a CO shift part temperature detector, and 65 denotes a temperature detector.

Claims (14)

(A) a reforming unit that generates reformed gas containing hydrogen and carbon monoxide from the reforming fuel;
(B) Carbon monoxide is reduced from the reformed gas by oxidizing the carbon monoxide contained in the reformed gas formed in the reforming section in a first temperature region and in an oxygen-containing atmosphere. A CO oxidation removing unit having a catalyst to be reacted;
(C) an oxygen supply unit that supplies an oxygen component to the CO oxidation removal unit;
(D) comprising a control device for performing a catalyst regeneration process for regenerating the catalyst in the CO oxidation removal unit,
The catalyst regeneration treatment is
(I) a residual operation in which a reformed gas containing hydrogen is left in the CO oxidation removal unit;
(Ii) an oxygen supply stop operation for stopping supplying the oxygen component to the CO oxidation removal unit;
(Iii) A reforming apparatus including a temperature maintaining operation for maintaining the catalyst of the CO oxidation removing unit in a catalyst regeneration temperature range for regenerating the catalyst of the CO oxidation removing unit.   2. The reformer according to claim 1, wherein the catalyst regeneration temperature region is higher than the first temperature region or a temperature region corresponding to the first temperature region.   3. The reformer according to claim 1, wherein the control device performs the catalyst regeneration process when the operation of the reformer is stopped and / or when the operation of the reformer is started. 4. The reformer according to claim 1, wherein the reformer includes a reforming unit that generates the reformed gas containing hydrogen and carbon monoxide from the reforming fuel. With a heating part that heats the part,
When the temperature of the CO oxidation removal unit is lower than the catalyst regeneration temperature region, the control device performs a temperature raising operation for increasing the temperature of the CO oxidation removal unit to the catalyst regeneration temperature region by the heating unit. Quality equipment.   In Claim 4, the said heating part is a combustion part which burns a combustible fuel, The said combustible fuel is the combustible fuel supplied from a fuel supply source, the reformed gas produced | generated by the said reformer, A reformer that is one of the off-gases discharged from the fuel cell.   6. The control device according to claim 1, wherein the control device heats the catalyst in the CO oxidation removal unit with a heating gas in advance and / or during the catalyst regeneration process before the catalyst regeneration process. Reforming equipment.   7. The control device according to claim 6, wherein the control device supplies combustion air to the combustion unit in a state where the combustible fuel is not supplied to the combustion unit, and the combustion air is supplied to the remaining heat of the combustion unit and / or the reforming unit. A reformer that forms the heated gas by heating with residual heat of the mass part.   The reformer according to claim 1, further comprising a heat insulating part that covers the CO oxidation removing part.   The operation part operated by an operator is provided in one of Claims 1-8, and the control device performs the catalyst regeneration processing based on the operation of the operator to the operation part. Reformer.   The operation history storage element for storing an operation history of the reformer is provided in one of claims 1 to 9, and the control device performs a modification to execute the catalyst regeneration process according to the operation history. Quality equipment. 11. The reformed gas discharge path for discharging the reformed gas purified by the CO oxidation removing unit to the reformed gas consuming unit, and the reformed gas discharge path according to claim 1. And an outlet valve
The controller is configured to discharge the entire amount of the reformed gas remaining in the CO oxidation removing unit to the reformed gas discharge path by opening the outlet valve when the reformer is stopped or started. A reformer that closes the outlet valve to leave a part of the reformed gas in the CO oxidation removal section.   12. The CO purification unit according to claim 1, wherein the CO purification unit that reduces carbon monoxide in the reformed gas before the oxidation reaction in the CO oxidation removal unit is disposed upstream of the CO oxidation removal unit. The control device is a reforming device that causes the reformed gas to remain in the CO shift unit in the operation of stopping the reforming device.   13. The control device according to claim 1, wherein immediately before the catalyst regeneration process, the control device sets the flow rate of reforming water per unit time supplied to the reforming device to 3 in S / C. .Reforming equipment limited to 2 or less. 14. The CO oxidation removal unit temperature detector according to claim 1, wherein a CO shift unit temperature detector for detecting the temperature of the CO shift unit is provided, and the temperature of the CO oxidation removal unit is detected. Is provided,
During the operation of the reformer, the control device detects the temperature of the CO oxidation removal unit detected by the CO oxidation removal unit temperature detector or the temperature of the CO shift unit detected by the CO shift unit temperature detector. A reformer that controls the supply amount of the oxygen component supplied from the oxygen supply unit to the CO oxidation removal unit according to temperature.

Images