JP2005170742A - Fuel reforming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel reforming system in which the temperature control is easily carried out. <P>SOLUTION: The fuel reforming system is provided with a reforming reactor 2 for reforming hydrocarbon based fuel and a high temperature shift reactor 3, a low temperature shift reactor 4 and a selective oxidation reactor 5 which are for decreasing carbon monoxide in the reformed gas. A combustor 21 is provided between the reforming reactor 2 and the high temperature shift reactor 3 and a combustor 22 is provided between the high temperature reactor 3 and the low temperature shift rector 4. Temperature sensors 17-20 for detecting the temperature of a combustor 1 and each reactor are provided. The raw material or the reforming gas is burned in the combustors 1, 21 and 22 based on the temperature of the temperature sensor 17-20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to temperature adjustment of a reformer and a carbon monoxide reduction device.

  In the conventional system, a combustion burner for starting is provided upstream of the reforming system, and at the time of starting, reformed fuel and air are directly supplied to the burner, and the combustion gas is ignited by a glow plug disposed in the combustion section. By supplying to the reforming system, each element of the reforming system is warmed up to a predetermined temperature, and when the reforming catalyst system reaches the predetermined temperature, the reforming fuel gas (hydrocarbon fuel + water mixture) ) And air are supplied to Patent Document 1 to shift to a normal reforming operation.

In this case, the combustion gas temperature from the startup combustor is determined in consideration of the warm-up performance, heat resistance and exhaust performance of each part, so avoid combustion near the stoichiometric air-fuel ratio where the combustion temperature is high, Let the lean burn.
JP 2000-63104 A

 However, according to the conventional start-up method, for example, when the fuel is lean-burned in the combustor and each element of the reforming system is warmed up by the combustion gas, the remaining heat given to the upstream element is provided. When the temperature of the element located in the most downstream reaches the target temperature because the element on the downstream side is warmed up, the temperature of the element located upstream becomes too high, that is, the excess element heats There is a possibility that problems such as an increase in energy (fuel) consumed at startup and a delay in startup time may occur.

  The present invention has been invented to solve such problems, and aims to achieve warm-up of each element of the fuel reforming system with a minimum amount of fuel and shorten the start-up time.

  In the present invention, a reformer that reforms a hydrocarbon-based raw material into a hydrogen-rich reformed gas, and a plurality of serially arranged units that reduce carbon monoxide in the reformed gas reformed by the reformer. In the fuel reforming system comprising the carbon monoxide reduction device, at least one first heating means for heating the reformer and at least one provided between the reformer and the plurality of carbon monoxide reduction devices. Two heating means are provided. Further, based on the activity detected by the reformer, the activity detection means for detecting the activity of the plurality of carbon monoxide reduction devices, and the activity detected by the activity detection means, at least one downstream of the second heating means. Heating control means is provided for controlling the heating amount of the second heating means so that the activity of the carbon oxide reduction device becomes the target activity.

  According to the present invention, for example, based on the temperature of the reformer and the carbon monoxide reduction device, the heating amount of the first and second heating means provided upstream of the reformer or the carbon monoxide reduction device is controlled, By warming up the reformer or the carbon monoxide reduction device to the target temperature, it is possible to prevent an increase in fuel consumption and an increase in startup time without overheating each reactor.

  The configuration of the first embodiment of the present invention will be described with reference to the configuration diagram of FIG.

  This fuel reforming system includes a combustor 1 as a first heating means, a reforming reactor 2, a combustor 21, a high temperature shift reactor 3, a combustor 22, and a low temperature shift reactor from the upstream side. 4 and a selective oxidation reactor 5 (the combustor 21 and the combustor 22 are the second heating means, the reforming reactor 2 is the reformer, the high temperature shift reactor 3 and the low temperature shift reactor 4 The selective oxidation reactor 5 is a carbon monoxide reduction device). Further, a fuel injection valve 7 for supplying hydrocarbon fuel to the combustor 1 and a fuel injection valve 8 for supplying hydrocarbon fuel to the reforming reactor 2 are provided. Also, a flow rate control valve 9 that controls the air flow rate to the combustor 1, a flow rate control valve 10 that controls the air flow rate to the reforming reactor 2, and the air flow rate to the combustor 21 or the high temperature shift reactor 3. A flow rate control valve 11 for controlling the flow rate, a flow rate control valve 12 for controlling the air flow rate to the combustor 22 or the low temperature shift reactor 4, and a flow rate control valve 13 for controlling the air flow rate to the selective oxidation reactor 5. . The flow rate control valves 9 to 13 are provided at the respective branch portions from the air supply path 40 (the flow rate control valves 9 to 13 are an oxidant supply unit and an oxidant flow rate control unit). Further, a flow rate control valve 14 for controlling the water flow rate to the reforming reactor 2, a flow rate control valve 15 for controlling the water flow rate to the high temperature shift reactor 3, and a water flow rate to the low temperature shift reactor 4 are controlled. A flow control valve 16 is provided. Each flow control valve 14-16 is provided in each branch part from the water supply path 41 (the flow control valves 14-16 are water supply means, and are water flow control means).

  The combustor 1 burns hydrocarbon-based fuel injected from the fuel injection valve 7 with air whose flow rate is controlled by the flow control valve 9 to generate high-temperature combustion gas, and downstream reforming by the combustion gas. Warm up reactor 2 and the like.

  The reforming reactor 2 is a hydrogen-rich reformed gas from the fuel injected from the fuel injection valve 8, the air supplied through the flow control valve 10, and the water supplied through the flow control valve 14. Is generated. The reforming reactor 2 includes a temperature sensor 17, and the temperature sensor 17 detects the temperature of the reforming reactor 2.

  The combustor 21 burns the reformed gas reformed by the reforming reactor 2 with the air supplied through the flow control valve 11, and each reactor downstream from the combustor 21 by the generated combustion gas. Warm up. In addition, a spark plug 23 is provided to burn the reformed gas.

  The high temperature shift reactor 3 reforms the carbon monoxide in the reformed gas generated in the reforming reactor 2 by a shift reaction at a relatively high temperature with water supplied via the flow control valve 15. Reduce carbon monoxide contained in the gas. The high temperature shift reactor 3 includes a temperature sensor 18, and the temperature sensor 18 detects the temperature of the high temperature shift reactor 3.

  The combustor 22 burns the reformed gas in which carbon monoxide is reduced by the high-temperature shift reactor 3 with the air supplied through the flow control valve 12, and is downstream from the low-temperature shift reactor 4 by the generated combustion gas. Warm up each of the reactors. In addition, a spark plug 24 is provided to burn the reformed gas.

  The low temperature shift reactor 4 shifts carbon monoxide in the reformed gas whose carbon monoxide has been reduced by the high temperature shift reactor 3 with water supplied through the flow control valve 16 in a relatively low temperature state. Further reduction. The low temperature shift reactor 4 includes a temperature sensor 18, and the temperature sensor 18 detects the temperature of the low temperature shift reactor 4.

  The selective oxidation reactor 5 converts the carbon monoxide in the reformed gas from which the carbon monoxide has been further reduced by the low temperature shift reactor 4 to the monoxide in the reformed gas by the air supplied through the flow control valve 13. For example, the carbon concentration is reduced to such an extent that the electrode of the polymer electrolyte fuel cell is not poisoned. Further, the amount of air is adjusted by the flow control valve 13 to oxidize the reformed gas. The selective oxidation reactor 5 includes a temperature sensor 18 and detects the temperature of the selective oxidation reactor 5 by the temperature sensor 18 (temperature sensors 17 to 20 are activity detection means).

  Moreover, the controller unit 6 which controls the fuel injection valves 7 and 8, the flow control valves 9-16, etc. from the temperature etc. which were detected by the temperature sensors 17-20 is provided.

  Next, the fuel reforming of the first embodiment will be described using the time chart of FIG.

  When the fuel cell system is started, hydrocarbon fuel is injected into the combustor 1 by the fuel injection valve 7 at t0, and the air is adjusted by the flow rate adjusting valve 9 so that combustion is performed on the lean side of the theoretical mixture ratio. Adjust the amount and let it burn. And the high temperature combustion gas which generate | occur | produced by combustion is supplied to each reactor, and each reactor is warmed up. Thus, each reactor, particularly the reforming reactor 2 can be warmed up immediately after the start of the fuel reforming system.

  When the temperature of the reforming reactor 2 detected by the temperature sensor 17 at t1 exceeds the warm-up end temperature T1, which is the target activity, the fuel supply from the fuel injection valve 7 and the air supply are stopped by the flow control valve 9 Then, combustion in the combustor 1 is stopped. Further, the fuel is supplied to the reforming reactor 2 by the fuel injection valve 8, the air whose flow rate is controlled by the flow control valve 10, the water whose flow rate is controlled by the flow control valve 14 is supplied, and the reforming reaction is performed. In the vessel 2, a reforming reaction for generating a hydrogen-rich reformed gas is performed. Then, air whose flow rate is controlled by the flow rate control valve 11 is supplied to the combustor 21, the reformed gas reformed by the reforming reactor 2 is combusted by the spark plug 23, and the combusted gas is used by the combustor 21. Warm down the downstream reactor. At this time, the mixing ratio of the reformed gas and air in the combustor 21 is set in consideration of the heat resistance of the downstream reactor, particularly the high temperature shift reactor 3, and is leaner than the theoretical mixing ratio with a high combustion temperature. Or set it to the over-dark side. Further, by adjusting the flow control valve 11 or the flow control valve 15, air or water may be supplied to adjust the temperature of the combustion gas. In addition, the amount of heat for vaporizing the fuel and water supplied to the reforming reactor 2 may be generated without stopping the combustor 1.

  At t2, when the temperature of the high temperature shift reactor 3 detected by the temperature sensor 18 reaches the warm-up end temperature T2 that is the target activity, the combustion in the combustor 21 is terminated, and the high temperature shift reactor 3 is warmed up. finish. Then, the flow control valve 15 supplies the amount of water corresponding to the reformed gas amount to the high temperature shift reactor 3 to perform a shift reaction that reduces carbon monoxide in the reformed gas. Further, air whose flow rate is controlled by the flow control valve 12 is supplied to the combustor 22, and the reformed gas whose carbon monoxide has been reduced is burned by the high temperature shift reactor 3 by the spark plug 24, and combustion is performed by the combustion gas. Warm the reactor downstream of the reactor 22. At this time, the mixing ratio of the reformed gas and air in the combustor 22 is set in consideration of the heat resistance of the downstream reactor, in particular, the low temperature shift reactor 4, and is leaner than the theoretical mixing ratio with a high combustion temperature. Or set it to the over-dark side. Further, the temperature of the combustion gas may be adjusted by supplying air or water by adjusting the flow control valve 12 or the flow control valve 16. Thereby, the temperatures of the reforming reactor 2 and the high temperature shift reactor 3 can be controlled independently.

  At t3, the temperature of the low temperature shift reactor 4 detected by the temperature sensor 19 becomes the warm-up end temperature T3, which is the target activity, and the temperature of the selective oxidation reactor 5 is the warm-up end temperature T4, which is the target activity. Then, the combustion in the combustor 22 is finished, and the warm-up of the low temperature shift reactor 4 and the selective oxidation reactor 5 is finished. Then, the flow control valve 15 supplies the amount of water corresponding to the reformed gas amount to the high temperature shift reactor 3 to perform a shift reaction that reduces carbon monoxide in the reformed gas. Further, the flow control valve 13 supplies an air amount corresponding to the reformed gas amount to the selective oxidation reactor 5, and further reduces the carbon monoxide in the reformed gas whose carbon monoxide has been reduced by the low temperature shift reactor 4. To do. As a result, the temperatures of the reforming reactor 2, the high temperature shift reactor 3, the low temperature shift reactor 4, and the selective oxidation reactor 5 can be controlled independently.

  The temperature change of the reactor when the present invention is used is shown in FIG. Moreover, the temperature change of the reactor when not using this invention is shown in FIG. When the present invention is not used, combustion gas is generated by the combustor, and each reactor is sequentially warmed up by the heat. For example, the temperature of the selective oxidation reactor provided at the most downstream is suitable for the reaction. When the temperature is warmed up to a high temperature, the temperature of the reforming reactor, the high temperature shift reactor, and the low temperature shift reactor located upstream thereof becomes higher than the temperature suitable for the reaction of each reactor. On the other hand, since the temperature of each reactor when using the present invention can be controlled independently, it can be set to a temperature suitable for the reaction of each reactor.

  The effect of 1st Embodiment of this invention is demonstrated.

  The temperatures of the reforming reactor 2, the high temperature shift reactor 3, the low temperature shift reactor 4, and the selective oxidation reactor 5 provided downstream of each of the combustors 1, 2, 22 are controlled by the combustors 1, 2, 22, respectively. In addition, since the reformer gas is burned in the combustors 21 and 22, each reactor can be warmed up with less fuel without overheating, and each reactor can be warmed up quickly. be able to.

  Immediately after the start of the fuel reforming system, the reforming reactor 2 is warmed up by the combustor 1, so that it can be warmed up quickly.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  The second embodiment will be described with respect to parts different from FIG.

  In this embodiment, instead of the combustors 21 and 22, electric heating catalysts (hereinafter referred to as EHC) 31 and 32 are provided as second heating means. This warms up the high temperature shift reactor 3, the low temperature shift reactor 4, and the selective oxidation reactor 5. About another structure, it is the same structure as 1st Embodiment.

  Next, fuel reforming according to the second embodiment will be described with reference to the time chart of FIG.

  When the fuel cell system is started, hydrocarbon fuel is injected into the combustor 1 by the fuel injection valve 7 at t0, and the air is adjusted by the flow rate adjusting valve 9 so that combustion is performed on the lean side of the theoretical mixture ratio. Adjust the amount and burn. And the high temperature combustion gas which generate | occur | produced by combustion is supplied to each reactor, and each reactor is warmed up. Thus, each reactor, particularly the reforming reactor 2 can be warmed up immediately after the start of the fuel reforming system.

  When the temperature of the reforming reactor 2 detected by the temperature sensor 17 at t1 exceeds the warm-up end temperature T1, which is the target activity, the fuel supply from the fuel injection valve 7 and the air supply are stopped by the flow control valve 9 Then, combustion in the combustor 1 is stopped. Further, the fuel is supplied to the reforming reactor 2 by the fuel injection valve 8, the air whose flow rate is controlled by the flow control valve 10, the water whose flow rate is controlled by the flow control valve 14 is supplied, and the reforming reaction is performed. In the vessel 2, a reforming reaction for generating a hydrogen-rich reformed gas is performed. Then, the air whose flow rate is controlled by the flow rate control valve 11 is supplied to the EHC 31, and the reformed gas reformed in the reforming reactor 2 is oxidized by energizing the EHC 31. The reactors downstream of the EHC 31 are warmed up by the heat generated by this oxidation reaction. At this time, the mixing ratio of the reformed gas and air in the EHC 31 is set in consideration of the heat resistance of the downstream reactor, particularly the high temperature shift reactor 3, and is leaner than the theoretical mixing ratio with a high combustion temperature, or Set to the dark side. Further, by adjusting the flow control valve 11 or the flow control valve 15, air or water may be supplied to adjust the temperature of the combustion gas.

  When the temperature of the high-temperature shift reactor 3 detected by the temperature sensor 18 at t2 exceeds the warm-up end temperature T2 that is the target activity, the air supply by the flow control valve 11 is stopped, the energization to the EHC 31 is stopped, Warm-up of the high temperature shift reactor 3 is completed. Further, the flow control valve 15 supplies a water amount corresponding to the reformed gas amount to the high temperature shift reactor 3 to perform a shift reaction for reducing carbon monoxide in the reformed gas. Then, air whose flow rate is controlled by the flow rate control valve 12 is supplied to the EHC 32, and the reformed gas with reduced carbon monoxide is oxidized by the high temperature shift reactor 3 by energizing the EHC 32. The low temperature shift reactor 4 and the selective oxidation reactor 5 are warmed up by heat generated by the oxidation reaction. At this time, the mixing ratio of the reformed gas and air in the EHC 32 is set in consideration of the heat resistance of the downstream reactor, and is set to a leaner side or a richer side than a theoretical mixing ratio having a high combustion temperature. Further, by adjusting the flow rate control valves 12, 13 or the flow rate control valve 16, air or water may be supplied to adjust the temperature of the combustion gas. Thereby, the temperatures of the reforming reactor 2 and the high temperature shift reactor 3 can be controlled independently.

  At t3, the temperature of the low temperature shift reactor 4 detected by the temperature sensor 19 exceeds the warm-up end temperature T3 that is the target activity, and the temperature of the selective oxidation reactor 5 detected by the temperature sensor 20 is the target activity. When the warm-up end temperature T4 is reached, the supply of air by the flow rate control valve 12 is stopped, the energization to the EHC 32 is stopped, and the warm-up of the low temperature shift reactor 4 and the selective oxidation reactor 5 is ended. Water whose flow rate is controlled by the flow rate control valve 16 is supplied to the low temperature shift reactor 4 to perform a shift reaction in which carbon monoxide in the reformed gas is reduced. Further, the air whose flow rate is controlled by the flow rate control valve 13 is supplied to the selective oxidation reactor 5, and the reformed gas carbon monoxide is further reduced by the low temperature shift reactor 4. As a result, the temperatures of the reforming reactor 2, the high temperature shift reactor 3, the low temperature shift reactor 4, and the selective oxidation reactor 5 can be controlled independently.

  Although a temperature sensor is used as the activity detection means, the outside air temperature is detected by an unillustrated temperature sensor (outside air temperature detection means), and the time after starting is detected by a timer or the like (time detection) Means) Further, the heat capacity may be calculated from the material and size of each reactor, and the activity of each reactor may be estimated from the outside air temperature, the time from the start of startup, and the heat capacity of each reactor. According to this, since the temperature of each reactor is detected based on the temperature of the outside air, the time from the start of the start of the fuel reforming system, and the heat capacity of each reactor, the fuel reforming can be performed without using a temperature sensor for each reactor. The system can be controlled.

  Note that an EHC may be provided upstream of the selective oxidation reactor 5 to control the temperature of the selective oxidation reactor 5. Further, the EHC may be energized immediately after startup and preheated.

  Further, an electric heating catalyst may be used instead of the combustor 1. Further, the second heating means located upstream of each reactor may be used in combination with a combustor and an electric heating catalyst.

  The effect of 2nd Embodiment of this invention is demonstrated.

  Since the reforming reactor 2 is warmed up by the electrothermal catalyst 22 immediately after the start of the fuel reforming system, the reforming reactor 2 can be warmed up quickly.

  It goes without saying that the present invention is not limited to the above-described embodiments, and includes various modifications and improvements that can be made within the scope of the technical idea.

  INDUSTRIAL APPLICABILITY The present invention can be used in the field where hydrocarbon-based raw materials are reformed and used, and in particular, used in the field where solid polymer fuel cells where the carbon monoxide concentration must be reduced are used. Can do.

It is a block diagram which shows the structure of 1st Embodiment of this invention. It is a figure which shows the time chart of the temperature change of 1st Embodiment of this invention, and the state of each reactor. It is a figure which shows the temperature change of each reactor of 1st Embodiment of this invention. It is a figure which shows the temperature change of each reactor when not using this invention. It is a block diagram which shows the structure of 2nd Embodiment of this invention. It is a figure which shows the time chart of the temperature change of 2nd Embodiment of this invention, and the state of each reactor.

Explanation of symbols

1 Combustor (first heating means)
2 Reforming reactor (reformer)
3 High temperature shift reactor (carbon monoxide reduction device)
4 Low temperature shift reactor (carbon monoxide reduction device)
5 Selective oxidation reactor (carbon monoxide reduction device)
6 Controller unit 9-13 Flow control valve (Oxidant supply amount control means)
14-16 Flow rate adjustment valve (water supply control means)
17-20 Temperature sensor (temperature detection means)
21, 22 Combustor (second heating means)
31, 32 Electric heating catalyst (second heating means)

Claims (9)

A reformer for reforming a hydrocarbon-based raw material into a hydrogen-rich reformed gas;
In a fuel reforming system comprising a plurality of carbon monoxide reduction devices arranged in series to reduce carbon monoxide in the reformed gas reformed by the reformer,
First heating means for heating the reformer;
At least one second heating means provided between the reformer and the plurality of carbon monoxide reduction devices;
An activity detection means for detecting the activity of the reformer and the plurality of carbon monoxide reduction devices;
Based on the activity detected by the activity detection means, the heating of the second heating means is controlled so that the activity of the carbon monoxide reduction device at least immediately downstream of the second heating means becomes the target activity. And a heating control means. An oxidant supply means for supplying an oxidant to the reformer, the plurality of carbon monoxide reduction devices, the first heating means, and the second heating means,
Based on the activity detected by the activity detection means, the reformer, the plurality of carbon monoxide reduction devices, the first heating means, and the oxidant supplied to the second heating means. An oxidant flow rate control means for controlling the flow rate,
The second heating unit is configured to flow the reformed gas discharged from the reformer provided upstream of the second heating unit or the plurality of carbon monoxide reduction devices by the oxidant flow rate control unit. The carbon monoxide reduction device located at least immediately downstream of the second heating means is heated to the degree of activity by the heat generated by the combustion by the controlled oxidant. The fuel reforming system described. Water supply means for respectively supplying water to the reformer, the plurality of carbon monoxide reduction devices, and the second heating means;
Based on the activity detected by the activity detection means, the reformer and water flow control means for controlling the flow rate of the water supplied to the plurality of carbon monoxide reduction devices, respectively,
The plurality of carbon monoxide reduction devices are heated to the target activity by the second heating unit, and then the oxidant whose flow rate is controlled by the oxidant flow rate supply unit or the water flow rate supply unit, or The fuel reforming system according to claim 2, wherein the water is supplied to reduce carbon monoxide in the reformed gas.   4. The apparatus according to claim 1, wherein the activity detection unit includes a temperature sensor in the reformer or the plurality of carbon monoxide reduction devices, and detects a target activity by the temperature sensor. 5. The fuel reforming system according to one. An outside air temperature detecting means for detecting the outside air temperature;
A time detecting means for detecting a time from the start of starting the fuel reforming system,
The activity detection means is configured to calculate the activity from the outside air temperature detected by the outside air temperature detection means, the time detected by the time detection means, and the heat capacity of the reformer and the plurality of carbon monoxide reduction devices. The fuel reforming system according to any one of claims 1 to 4, wherein the degree is detected.   6. The fuel reforming system according to claim 1, wherein the first heating unit is a combustor that burns the raw material and the oxidant.   6. The fuel reforming system according to claim 1, wherein the first heating means is an electric heating catalyst.   The at least one of the second heating means is a combustor that burns the reformed gas and the oxidant discharged from the reformer or the plurality of carbon monoxide reduction devices. 8. The fuel reforming system according to any one of 7 above.   The fuel reforming system according to any one of claims 1 to 8, wherein at least one of the second heating means is an electric heating catalyst.

Images