JP3747761B2 - Fuel reformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a fuel reformer that generates a reformed gas containing hydrogen by reforming a reforming fuel containing a hydrocarbon.
[0002]
[Prior art]
Conventionally, this type of fuel reformer is composed of a reformer, a carbon monoxide removal device, an evaporator, and the like as described in Japanese Patent Application Laid-Open No. 2000-070243.
[0003]
Here, the carbon monoxide removing device is filled with an oxidation catalyst, and the carbon monoxide in the reformed gas is preferentially oxidized with an oxidant, and the carbon monoxide concentration in the reformed gas is determined as a fuel cell stack. The power generation efficiency can be reduced to a level that does not decrease. The reaction at this time can be expressed by the following formula.
[0004]
2CO + O₂→ 2CO₂              (1)
This reaction is an exothermic reaction, and the temperature of the catalyst increases as the reaction proceeds. However, the optimum active temperature range of the catalyst is limited. When the temperature exceeds the temperature range, the reaction selectivity is lowered and the side reaction as shown in the following formula becomes active.
[0005]
CO₂+ H₂→ CO + H₂O (2)
2H₂+ O₂→ 2H₂O (3)
The reaction of the formula (2) increases carbon monoxide in the reformed gas, and the formulas (2) and (3) consume hydrogen in the reformed gas. The power generation efficiency will be reduced.
[0006]
On the other hand, when the temperature of the catalyst is lower than the optimum activation temperature range, the reaction of the formula (1) is suppressed, and carbon monoxide in the reformed gas cannot be oxidized. The carbon oxide concentration cannot be reduced. For this reason, when the refrigerant that adjusts the temperature of the catalyst by exchanging heat with the catalyst has a temperature that is not more than the optimum activation temperature range of the catalyst, the flow rate of the refrigerant should be adjusted precisely according to the reaction rate of the equation (1) If not controlled, the catalyst may be at a temperature below the optimum activation temperature range.
[0007]
Thus, the exothermic reaction and the heat exchange proceed simultaneously in the catalyst, and the temperature inside the catalyst varies. That is, in the vicinity of the catalyst inlet, the oxidant concentration is high, the reaction rate of the formulas (1) and (3) is fast, the catalyst temperature rises and becomes high. When the temperature of the catalyst exceeds the optimum activation temperature range, the side reaction is activated to reduce the carbon monoxide removal ability. Further, the oxidant is consumed by the reaction, and the oxidant concentration tends to decrease near the outlet. Along with this, the temperature of the catalyst also tends to decrease as the temperature approaches the outlet. The variation (temperature difference between the catalyst at the inlet and the outlet) becomes more noticeable as the temperature of the reformed gas flowing into the catalyst becomes higher. To suppress this variation, the temperature of the reformed gas flowing into the catalyst is set to the optimum temperature. A control technique is described in Japanese Patent Laid-Open No. 2000-72403.
[0008]
This is equipped with a heat exchanger upstream of the carbon monoxide removal device, and the temperature of the reformed gas flowing into the catalyst is controlled by a refrigerant circulating in the heat exchanger. The reformed gas has a temperature within the optimum active temperature range. Is supplied to the catalyst at such a temperature. In order to simplify the refrigerant circulation device, the refrigerant circulating through the heat exchanger and the refrigerant circulating through the carbon monoxide removal device are shared.
[0009]
[Problems to be solved by the invention]
However, in this prior art, the temperature of the reformed gas is controlled to the optimum temperature at the time of flowing into the carbon monoxide removing device, the reaction of the formula (1) is promoted on the inlet side of the catalyst, and the temperature of the catalyst becomes the inlet temperature. It rises sharply on the side. The temperature of the refrigerant is set so that the temperature of the catalyst on the inlet side is maintained within a temperature range effective for catalyst activity.
[0010]
The refrigerant circulation device of the prior art shares the refrigerant circulating in the heat exchanger and the refrigerant circulating in the carbon monoxide removal device, and inevitably removes carbon monoxide when the temperature of the refrigerant circulating in the heat exchanger is lowered. The temperature of the refrigerant circulating through the device also decreases.
[0011]
Even if the temperature of the refrigerant circulating through the carbon monoxide removal device is set lower than the temperature at which the catalyst temperature falls within the optimum activation temperature range, the catalyst temperature is detected and the flow rate of the refrigerant is controlled precisely. It is possible to control the temperature within the optimum active temperature range. However, it is not easy to detect the catalyst temperature, and there is a problem that the flow rate of the refrigerant must be precisely controlled by a complicated control system.
[0012]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fuel reformer equipped with a carbon monoxide removal device that can maintain the catalyst at an optimum temperature without detecting the catalyst temperature and solves such a problem. To do.
[0013]
[Means for Solving the Problems]
  A first invention is a reformer that generates a reformed gas containing hydrogen;Equipped with a catalyst layer to remove carbon monoxide contained in the reformed gasIn a fuel reformer comprising: at least one carbon monoxide remover; and a heat exchanger interposed between the reformer and the carbon monoxide remover and introduced with reformed gas,SaidA first circulation device that circulates the first refrigerant in the heat exchanger and controls the temperature of the first refrigerant;In the carbon monoxide removal deviceA second circulation device that circulates the second refrigerant and controls the temperature of the second refrigerant, and sets the temperature of the first refrigerant to be lower than the temperature of the second refrigerant.
[0014]
2nd invention is equipped with the heat exchanger common to a said 1st circulation apparatus and a said 2nd circulation apparatus in 1st invention.
[0015]
  According to a third invention, in the second invention, a flow rate adjusting means for adjusting a flow rate of the first refrigerant flowing into the heat exchanger;In the carbon monoxide removal deviceTemperature detection means for detecting the temperature of the inflowing reformed gas is provided, and the flow rate of the first refrigerant is adjusted so that the temperature of the reformed gas becomes a predetermined value.
[0016]
In a fourth aspect based on the first aspect, the first circulation device circulates the first refrigerant to the fuel cell stack.
[0017]
  5th invention is the reformer which produces | generates the reformed gas containing hydrogen, the at least 1 carbon monoxide removal apparatus provided with the catalyst layer which removes the carbon monoxide contained in reformed gas, and a reformer A heat exchanger that is interposed between the carbon monoxide removal device and the carbon monoxide removal device and into which the reformed gas is introduced, and a heat exchanger,For carbon monoxide removal equipmentThe fuel reformer is provided with a circulation device that circulates the refrigerant and controls the temperature of the refrigerant. The refrigerant is circulated through the heat exchanger and then to the carbon monoxide removing device and into the heat exchanger. The temperature of the refrigerant to be set is set lower than the temperature of the refrigerant flowing through the carbon monoxide removing device.
[0018]
  According to a sixth invention, in the fifth invention,The circulation device includes a bypass channel for the refrigerant to bypass the heat exchanger.
[0019]
According to a seventh invention, in the fifth or sixth invention, a refrigerant temperature calculating means for predicting an endothermic amount of the refrigerant in the heat exchanger and calculating a temperature of the refrigerant flowing into the carbon monoxide removing device based on the predicted endothermic amount. And the temperature of the refrigerant flowing into the heat exchanger is set so that the temperature of the refrigerant flowing into the carbon monoxide removing device becomes a predetermined value.
[0020]
In an eighth aspect based on the sixth aspect, the flow rate control means for controlling the flow rate of the refrigerant flowing into the heat exchanger, and the temperature detection means for detecting the temperature of the reformed gas flowing into the carbon monoxide removal device. The flow rate control means is controlled so that the temperature of the reformed gas becomes a predetermined temperature based on the detection value of the temperature detection means.
[0021]
According to a ninth invention, in the fifth or sixth invention, the fuel cell stack is provided with a circulation device for circulating the refrigerant in the fuel cell stack, and the refrigerant in the circulation device is radiated by heat exchange with the refrigerant for the fuel cell stack. .
[0022]
  The tenth invention is1st inventionThe temperature of the second refrigerant is set from the activation temperature of the catalyst layer of the carbon monoxide removing device.
  In an eleventh aspect based on any one of the fifth to eighth aspects, the temperature of the refrigerant is set from the activation temperature of the catalyst layer of the carbon monoxide removing device.
[0023]
【The invention's effect】
  In the first and tenth inventions, in the fuel reformer, a reformer that generates reformed gas, a heat exchanger,Equipped with a catalyst layer to remove carbon monoxide contained in the reformed gasAt least one carbon monoxide removing device, circulating a first refrigerant in the heat exchanger, controlling a temperature of the first refrigerant, circulating a second refrigerant in the carbon monoxide removing device, And a second circulation device for controlling the temperature of the second refrigerant, and the temperature of the first refrigerant is set lower than the temperature of the second refrigerant (for example, a temperature set from the activation temperature of the catalyst layer of the carbon monoxide removing device). Therefore, the reformed gas cooled by the first refrigerant is introduced into the carbon monoxide removal apparatus, the oxidation reaction rate in the vicinity of the reformed gas introduction port of the carbon monoxide removal apparatus is suppressed, and the reformed gas in the vicinity of the inlet is abrupt. An increase in catalyst temperature can be prevented. Further, since the second refrigerant is set from the activation temperature of the catalyst layer, it is possible to maintain an optimum activated state. In this way, the catalyst is brought to the active temperature with a simple configuration without measuring the temperature of the catalyst layer of the heat exchanger and the carbon monoxide removal device and without precisely controlling the flow rates of the first and second refrigerants. Can be maintained.
[0024]
In the second invention, since the heat exchanger common to the first circulation device and the second circulation device is provided, the high-temperature radiator does not exchange heat with the outside air, so the degree of freedom in layout is increased and the system is downsized. And cost reduction.
[0025]
  In the third invention, flow rate adjusting means for adjusting the flow rate of the first refrigerant flowing into the heat exchanger,For carbon monoxide removal equipmentA temperature detecting means for detecting the temperature of the reformed gas flowing in, and the flow rate of the first refrigerant is adjusted so that the temperature of the reformed gas becomes a predetermined value. It can be detected that the temperature of the reformed gas that has passed through the heat exchanger also falls below a predetermined target value. In such a case, by reducing the flow rate of the refrigerant circulating in the heat exchanger and raising the temperature of the reformed gas to the target value, the reaction of the formula (1) near the entrance of the carbon monoxide removing device is promoted. It is possible to prevent the concentration of carbon monoxide from being lowered sufficiently.
[0026]
In the fourth invention, since the first circulation device circulates the first refrigerant to the fuel cell stack, it is possible to remove the reaction heat and prevent the temperature rise of the fuel cell stack. Further, since the refrigerant circulation device of the fuel cell stack can be shared with the refrigerant circulation device of the heat exchanger, the system can be reduced in size and cost.
[0027]
  In a fifth aspect of the present invention, in the fuel reformer, the reformer, the heat exchanger, and at least one carbon monoxide removal device are arranged from the upstream side, and the heat exchangerFor carbon monoxide removal equipmentA circulation device that circulates the refrigerant, and the refrigerant is circulated through the heat exchanger and then to the carbon monoxide removal device, and the temperature of the refrigerant flowing into the heat exchanger is the temperature of the refrigerant that circulates through the carbon monoxide removal device. Since the temperature is set lower than the temperature, it is possible to suppress the temperature of the catalyst from abruptly rising and to exceed the optimum activation temperature of the catalyst, and to suppress side reactions that reduce the carbon monoxide removal performance and efficiency.
[0028]
  In the sixth invention, the circulation device isSince the refrigerant includes a bypass flow path for bypassing the heat exchanger, an effect of improving the efficiency of the system is produced.
[0029]
In the seventh invention, the carbon monoxide removing device is provided with refrigerant temperature calculating means for predicting the heat absorption amount of the refrigerant in the heat exchanger and calculating the temperature of the refrigerant flowing into the carbon monoxide removing device based on the predicted heat absorption amount. Since the temperature of the refrigerant flowing into the heat exchanger is set so that the temperature of the refrigerant flowing into the heat exchanger becomes a predetermined value, the temperature of the refrigerant deviates from the predetermined value, and the reformed gas flowing into the carbon monoxide removing device due to this influence Even when the temperature deviates from the target value, the temperature of the reformed gas flowing into the carbon monoxide removing apparatus can be changed to the target temperature.
[0030]
According to an eighth aspect of the present invention, the apparatus includes a flow rate control unit that controls the flow rate of the refrigerant flowing into the heat exchanger, and a temperature detection unit that detects the temperature of the reformed gas flowing into the carbon monoxide removal apparatus,
Since the flow rate control means is controlled so that the temperature of the reformed gas becomes a predetermined temperature based on the detection value of the temperature detecting means, the refrigerant temperature deviates from the predetermined value, and the reforming that flows into the carbon monoxide removal device due to this influence Even when the gas temperature deviates from the target value, the temperature of the reformed gas flowing into the carbon monoxide removal apparatus can be changed to the target temperature.
[0031]
In the ninth invention, the fuel cell stack is provided with a circulation device for circulating the refrigerant in the fuel cell stack, and the heat of the circulation device is radiated by heat exchange with the refrigerant for the fuel cell stack. There is an effect of cost reduction.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows the configuration of an embodiment of the present invention.
[0033]
The fuel reformer of the present embodiment includes a reformer 1, a heat exchanger 2, carbon monoxide removing devices 3 and 4, a low temperature refrigerant pump 5, a low temperature refrigerant radiator 6, and a low temperature refrigerant. The thermostat 7 includes a high-temperature refrigerant pump 10, a high-temperature refrigerant radiator 11, and a high-temperature refrigerant thermostat 12.
[0034]
In order to distinguish the refrigerant used here, the refrigerant for exchanging heat with the heat exchanger 2 is refrigerant A, the refrigerant for exchanging heat with the carbon monoxide removing devices 3 and 4 is refrigerant B, and the heat exchanger and monoxide. Hereinafter, the refrigerant for exchanging heat with both of the carbon removing devices will be referred to as refrigerant A + B, and the refrigerant for exchanging heat only with the fuel cell stack will be referred to as refrigerant C.
[0035]
The reformer 1 is introduced with a mixed gas in which a hydrocarbon-based fuel vapor, water vapor, and oxidant are mixed. In the present embodiment, description will be made assuming that methanol is used as the hydrocarbon fuel and air is used as the oxidant.
[0036]
When the mixed gas is introduced into the reformer 1, it reacts with the catalyst a (for example, Cu / ZnO) filled in the reformer 1 to generate a reformed gas containing hydrogen. The generated reformed gas is a high-temperature gas of about 300 ° C. The reformed gas contains about 1.5 vol% carbon monoxide.
[0037]
The reformed gas that has flowed out of the reformer 1 flows into the heat exchanger 2 and undergoes heat exchange (receives a cooling action). The refrigerant A is supplied from the low-temperature refrigerant pump 5 to the heat exchanger 2, where the refrigerant A that exchanges heat with the reformed gas is maintained at about 85 ° C., and the reformed gas is exchanged with the refrigerant A by heat exchange. Cool to about 85 to 90 ° C. As the heat exchanger 2, a plate fin laminated heat exchanger is assumed, and as the refrigerant A, a mixed liquid of ethylene glycol and water is assumed.
[0038]
Although the temperature of the refrigerant A is 85 ° C. in this embodiment, the temperature of the refrigerant A is controlled to be lower than the temperature of the refrigerant B, and the catalyst b (for example, carbon monoxide) used in the carbon monoxide removal apparatuses 3 and 4 is used. Ru / Al for selective oxidation₂O_ThreeIt is determined by the activation temperature of the catalyst.
[0039]
The refrigerant A that has received heat that has passed through the heat exchanger 2 passes through the main flow path 8 and is introduced into the radiator 6 for low-temperature refrigerant to release heat. However, at the time of partial load operation with a small amount of reformed gas, the heat dissipation amount of the refrigerant A in the low-temperature refrigerant radiator 6 exceeds the heat absorption amount of the refrigerant in the heat exchanger 2, and the temperature of the refrigerant A falls below a predetermined value. It is possible that Therefore, a flow path 9 that bypasses the low-temperature refrigerant radiator 6 and is connected to the suction side of the low-temperature refrigerant pump 5 is provided, and when the amount of heat absorption is small, the refrigerant A is also introduced into the bypass flow path 9. Control to a predetermined temperature so that the temperature of A does not drop too much. In order to control the temperature of the refrigerant A, a thermostat 7 is installed at the junction of the main flow path 8 and the bypass flow path 9, the opening degree is controlled according to the temperature of the refrigerant A, and the bypass flow rate of the refrigerant A is controlled. The temperature of the refrigerant A is controlled.
[0040]
These constitute the first circulation device for the refrigerant A.
[0041]
The reformed gas that has passed through the heat exchanger 2 is again added with an oxidizing agent (air) and is introduced into the carbon monoxide carbon removing device 3. In the carbon monoxide removing device 3, the carbon monoxide concentration in the reformed gas is reduced to about 3000 ppm by the action of the catalyst b.
[0042]
The reformed gas further added with the oxidizing agent is introduced into the carbon monoxide removing device 4 provided downstream of the carbon monoxide carbon removing device 3. The carbon monoxide removal device 4 further reduces carbon monoxide in the reformed gas and supplies it to the fuel cell stack at a concentration of 40 ppm or less.
[0043]
In this embodiment, the two carbon monoxide removal devices 3 and 4 are arranged in series. However, the number of carbon monoxide removal devices is not limited to this, and the required performance of carbon monoxide removal and the fuel reforming device What is necessary is just to determine with an operating condition.
[0044]
In the carbon monoxide carbon removing devices 3 and 4, when the reformed gas is introduced by the filled catalyst b, the reactions shown in the equations (1) to (3) occur on the catalyst.
[0045]
The reactions of the formulas (1) and (3) are reactions accompanied by heat generation, and the temperature of the catalyst b increases with the progress of the reaction. Therefore, in order to maintain the temperature of the catalyst b at an appropriate temperature for a good catalytic reaction, it is necessary to circulate a refrigerant B, for example, oil, in the carbon monoxide removing devices 3 and 4 to remove reaction heat. .
[0046]
Two carbon monoxide carbon removal devices 3 and 4 arranged in series are provided with heat exchangers 3a and 4a, respectively. The heat exchangers 3a and 4a have, for example, a plate fin stacked structure, and include a flow path through which the reformed gas for heat exchange passes and a flow path through which the refrigerant B circulates. The catalyst b is coated on the flow path through which the reformed gas passes.
[0047]
Here, the temperature of the refrigerant B is controlled so as to maintain the temperature of the catalyst b in the optimum activation temperature range, and the optimum activation temperature range of the catalyst b of this embodiment is 100 to 200 ° C. Therefore, the temperature of the refrigerant B is one. It controls so that it may become 100 degreeC at the inlet_port | entrance of a carbon oxide removal apparatus.
[0048]
By maintaining the temperature of the refrigerant B at the optimum activation temperature of the catalyst b in this way, the temperature of the catalyst b can always be set to the optimum activation temperature, and occurs when the temperature of the catalyst b does not reach the activation temperature ( 1) The reaction rate of formula (1) is suppressed from slowing down, and as a result, the problem that the concentration of carbon monoxide in the reformed gas is not reduced is prevented.
[0049]
The refrigerant B is discharged from the pump 10 and supplied to the heat exchanger 3a of the carbon monoxide removing device 3, and exchanges heat with the catalyst b to absorb reaction heat. Subsequently, the refrigerant B is introduced into the heat exchanger 4a of the downstream carbon monoxide removing device 4 and similarly absorbs the reaction heat. The refrigerant B rises in temperature by heat exchange with the catalyst b, passes through the main flow path 13, is introduced into the high-temperature refrigerant radiator 11, and releases heat to the outside.
[0050]
Thus, the 2nd circulation device of refrigerant B is constituted.
[0051]
Further, during partial load operation or the like, the heat release amount of the refrigerant B in the high-temperature refrigerant radiator 11 exceeds the heat absorption amount of the refrigerant B in the carbon monoxide removing devices 3 and 4, and the temperature of the refrigerant B decreases below a predetermined value. It can be considered. Thus, as in the case of the low-temperature refrigerant radiator 6, a flow path 14 that bypasses the high-temperature refrigerant radiator 11 is provided, and when the amount of heat absorption is small, the refrigerant B is also introduced into the bypass flow path 14, The temperature of B is controlled to a predetermined temperature. In order to control the temperature of the refrigerant B, the thermostat 12 is installed at the junction of the main flow path 13 and the bypass flow path 14, and the flow rate of the refrigerant B is controlled by controlling the opening thereof. To control.
[0052]
As described above, in the present embodiment, the refrigerant circulating apparatus is separated into the refrigerant circulation apparatus 2 for the heat exchanger 2 and the carbon monoxide removing apparatuses 3 and 4 and is circulated through the heat exchanger. By setting the temperature of the refrigerant to be lower than that of the refrigerant B circulated through the carbon monoxide removal device, the flow rates of the refrigerants A and B can be made dense without measuring the temperature of the heat exchanger and the catalyst of the carbon monoxide removal device. It is possible to maintain the catalyst at the activation temperature with a simple structure without controlling the temperature.
[0053]
In the catalyst b, most of the generated reaction heat is transferred to the refrigerant B by heat exchange, but part of the heat is consumed to heat the catalyst b, and the catalyst b is heated. Therefore, when the temperature of the catalyst b exceeds the optimum activation temperature range and the reaction selectivity is lowered, the side reactions shown in the formulas (2) and (3) are actively generated, and these side reactions are performed as described above. This is not preferable because the power generation amount of the stack is reduced.
[0054]
It has already been mentioned that the reaction rate of the oxidation reaction depends on the temperature of the catalyst and the concentration of the oxidant. That is, the catalyst temperature near the inlet of the carbon monoxide removing devices 3 and 4 is in the optimum active temperature range because it is immediately after the refrigerant B having a temperature that takes into account the activation temperature of the catalyst b, and is simultaneously oxidized. Since the agent concentration is also high, the oxidation reaction proceeds rapidly and the temperature of the catalyst b increases rapidly.
[0055]
However, in this embodiment, the temperature of the refrigerant A introduced into the heat exchanger 2 is controlled to about 85 ° C., which is lower than the activation temperature of the catalyst b, and the temperature of the reformed gas flowing into the carbon monoxide removing device 3 is controlled. Since it is 85-90 degreeC, the speed | rate of the oxidation reaction in the inlet_port | entrance vicinity of the carbon monoxide removal apparatus 3 becomes slow, and the rapid raise of the temperature of the catalyst b can be suppressed. FIG. 2 shows the relationship between the position in the flow direction of the reformed gas in the carbon monoxide removal apparatus and the catalyst temperature in the present embodiment. Thus, in this embodiment, the side reaction in the carbon monoxide removal apparatus is suppressed, and the carbon monoxide removal performance and efficiency are improved. Further, by setting the temperature of the refrigerant B within the optimum activation temperature range of the catalyst b, the temperature of the catalyst b can always be set to the optimum activation temperature, and occurs when the temperature of the catalyst b does not reach the activation temperature (1). Slowing down the reaction rate of the formula is prevented, and as a result, the problem that the concentration of carbon monoxide in the reformed gas is not reduced is prevented.
[0056]
Needless to say, the temperature conditions of the reformed gas and the refrigerant are not limited to the numerical values of the present embodiment, but should be changed depending on the type and concentration of the catalyst and the refrigerant.
[0057]
FIG. 3 shows a second embodiment. In this embodiment, the heat dissipation means from the high-temperature refrigerant radiator 11 in the first embodiment is connected not to heat exchange with the outside air but to the heat exchange with the refrigerant A circulating in the heat exchanger 2. .
[0058]
The refrigerant A flowing out of the heat exchanger 2 is introduced into the high-temperature refrigerant radiator 11 to exchange heat with the refrigerant B, and then passes through the main flow path 8 connected to the low-temperature refrigerant radiator 6 and the low-temperature refrigerant radiator 6. 9 will be introduced.
[0059]
By setting it as such a structure, the ventilation fan installed in order to accelerate | stimulate the heat exchange with the radiator 11 for high temperature refrigerant | coolants and external air can be abolished, or it is necessary to install the radiator 11 for high temperature refrigerant | coolants near the external air introduction part. In addition, the degree of freedom in layout is increased, and the system can be reduced in size and cost.
[0060]
FIG. 4 shows a third embodiment, which is a temperature detection means 15 (for example, a thermistor thermometer) that measures the temperature of the reformed gas in the configuration of the second embodiment, and a refrigerant A that circulates in the heat exchanger 2. A flow rate adjusting means 16 for adjusting the flow rate of the refrigerant (for example, a flow rate adjusting valve), a temperature signal output from the temperature detecting means 15, and a signal for instructing the flow rate to the flow rate adjusting means (in the case of a flow rate adjusting valve, a valve And a controller 17 for outputting a signal for controlling the opening degree of the.
[0061]
The temperature detecting means 15 is installed between the heat exchanger 2 and the carbon monoxide removing device 3, and the refrigerant flow rate adjusting means 16 is installed upstream of the heat exchanger 2 in the main flow path 8 of the refrigerant A. The
[0062]
FIG. 5 shows a flowchart relating to the control contents performed by the controller 17.
[0063]
According to this, first, the temperature of the reformed gas is measured by the temperature detecting means 15 in step S1.
[0064]
In step S2, the reformed gas temperature is compared with the target temperature. When the reformed gas temperature has not reached the target temperature, the process proceeds to step S3. When the reformed gas temperature is equal to the target temperature, the control is terminated. When is higher than the target temperature, the process proceeds to step S4.
[0065]
In step S3, in order to reduce the flow rate of the refrigerant A so as to increase the temperature of the reformed gas, for example, the flow rate adjustment valve is controlled to narrow the opening.
[0066]
In step S4, in order to increase the flow rate of the refrigerant A so as to lower the temperature of the reformed gas, for example, the flow rate adjustment valve is controlled to increase the opening.
[0067]
By adopting such a configuration, when the temperature of the refrigerant A circulating in the heat exchanger 2 such as immediately after starting is lower than a predetermined value, the temperature of the reformed gas that has passed through the heat exchanger 2 is also a predetermined target value. It can be detected that the value will fall below. In such a case, by reducing the flow rate of the refrigerant A circulating in the heat exchanger 2 and raising the temperature of the reformed gas to the target value, the reaction of the formula (1) near the inlet of the carbon monoxide removal device Is not promoted, and the carbon monoxide concentration can be prevented from sufficiently decreasing.
[0068]
Next, FIG. 6 shows a fourth embodiment. In the configuration of the first embodiment, a fuel cell stack 18 is installed between the low-temperature refrigerant pump 19 and the heat exchanger 2 so that air can be introduced into the fuel cell stack 18.
[0069]
The reformed gas that has passed through the carbon monoxide removal device 4 and whose carbon monoxide concentration has been reduced to 40 ppm or less is introduced to the anode side of the fuel cell stack 18. At the same time, air is introduced. In the fuel cell stack 18, the introduction of the reformed gas and air causes a reaction of the formula (3) to generate electricity and heat of reaction.
[0070]
Since the fuel cell stack 18 is heated by this reaction heat and the optimum operating temperature may not be maintained, it is necessary to remove the reaction heat. Therefore, by introducing the refrigerant A discharged from the low temperature catalyst pump 5 into the fuel cell stack 18, the reaction heat can be removed and the temperature rise of the fuel cell stack 18 can be prevented.
[0071]
Moreover, since the refrigerant circulation device of the fuel cell stack 18 can be shared with the refrigerant circulation device of the heat exchanger 2, the system can be reduced in size and cost.
[0072]
Next, a fifth embodiment shown in FIG. 7 will be described. In this embodiment, the refrigerant circulation devices separately configured by the heat exchanger 2 and the carbon monoxide removing devices 3 and 4 in the first embodiment are combined into one.
[0073]
That is, the refrigerant A + B performs heat exchange in the order of the heat exchanger 2 and the carbon monoxide removing devices 3 and 4, and the refrigerant A + B is heated. The heated refrigerant A + B is introduced into the refrigerant radiator 25 through the main flow path 27, dissipates heat to the outside, and lowers the temperature. The refrigerant A + B whose temperature has decreased returns to the heat exchanger 2 again.
[0074]
However, during partial load operation or the like, the heat release amount of the refrigerant A + B in the refrigerant radiator 25 exceeds the heat absorption amount of the refrigerant A + B in the carbon monoxide removal device, and the temperature of the refrigerant A + B may be lower than a predetermined value. Conceivable. Accordingly, a flow path 28 that bypasses the refrigerant radiator 25 is provided, and when the amount of heat absorption is small, the refrigerant A + B is also introduced into the bypass flow path 28, and the temperature of the refrigerant A + B is controlled to a predetermined temperature. In order to control the temperature of the refrigerant A + B, a thermostat 26 is installed at the junction of the main flow path 27 and the bypass flow path 28, and the flow rate of the refrigerant A + B is controlled by controlling the opening thereof. To control.
[0075]
The temperature control content of the refrigerant A + B in this embodiment is controlled to be 100 ° C. which is the lower limit temperature of the optimum activation temperature of the catalyst b at the inlet of the carbon monoxide removing device 3 (Ru / Al₂O_ThreeIn the case of a catalyst).
[0076]
That is, the temperature rise of the refrigerant A + B in the heat exchanger 2 is estimated from the prediction of the heat absorption amount of the refrigerant in the heat exchanger 2 (this estimation is performed by a refrigerant temperature calculation means not shown). For example, when the temperature rise of the refrigerant A + B in the heat exchanger 2 is estimated to be 10 ° C., the temperature of the refrigerant A + B introduced into the heat exchanger 2 is controlled to be 90 ° C. The estimation of the heat absorption amount of the refrigerant A + B may be obtained by measuring the temperature rise of the refrigerant A + B with a thermometer, or may be calculated from the flow rates and inflow temperatures of the reformed gas and the refrigerant A + B and the performance of the heat exchanger 2. By introducing 90 ° C. refrigerant A + B into the heat exchanger 2, the reformed gas is cooled to 90 to 95 ° C., an oxidant is added, and the carbon monoxide removing device 3 is introduced.
[0077]
In the vicinity of the inlet of the carbon monoxide removing device 3, the temperature of the reformed gas is at the optimum temperature and the oxidant concentration is also high, so that the oxidation reaction proceeds rapidly and the temperature of the catalyst b rapidly increases. It can happen. However, in this embodiment, since the temperature of the reformed gas introduced into the carbon monoxide carbon removing device 3 is controlled to 90 to 95 ° C., the above-described oxidation reaction can be suppressed. Therefore, it is possible to suppress the temperature of the catalyst b from abruptly rising and to exceed the optimum activation temperature of the catalyst b, and to suppress side reactions that reduce the carbon monoxide removal performance and efficiency.
[0078]
FIG. 8 shows a sixth embodiment, which is different from the fifth embodiment in that a bypass channel 30 is provided so that the refrigerant A + B does not pass through the heat exchanger 2. Note that the flow path through which the refrigerant A + B flows to the heat exchanger 2 is a main flow path 29, and the main flow path 29 and the bypass flow path 30 merge downstream of the heat exchanger 2.
[0079]
Usually, the endothermic amount of the refrigerant A + B is larger in the carbon monoxide removing devices 3 and 4 than in the heat exchanger 2, and when the whole amount of the refrigerant A + B is circulated through the heat exchanger 2, the flow rate with respect to the heat exchanger 2 is reduced. An excess occurs. The heat exchanger 2 is structurally large in friction loss, and excessively distributes the refrigerant A + B. As a result, the friction loss increases, and an extra driving force of the refrigerant pump 24 is required.
[0080]
In the present embodiment, only the refrigerant A + B having a flow rate required by the heat exchanger 2 is supplied to the main flow path 29, and the other refrigerants A + B are passed through the bypass flow path 30 to the carbon monoxide removing device. Since the direct supply is performed, the friction loss in the heat exchanger 2 can be reduced and the necessary driving force of the refrigerant pump 24 can be reduced while maintaining the effects of the fifth embodiment. Therefore, the system efficiency is improved.
[0081]
The seventh embodiment shown in FIG. 9 is different from the sixth embodiment in that a flow rate adjusting means 31 that controls the flow rate of the refrigerant A + B flowing through the heat exchanger 2 is provided upstream of the heat exchanger 2. The temperature detection means 15 for measuring the temperature of the reformed gas discharged from 2 is installed, and the controller 17 for controlling the opening degree of the flow rate adjustment means 31, for example, the flow rate adjustment valve, based on the temperature detected by the temperature detection means 15 is provided. It is provided.
[0082]
The contents of control performed by the controller 17 are the same as those in the flowchart shown in FIG. 5, and since the flowchart has already been described, description thereof is omitted here.
[0083]
By adopting such a configuration, the refrigerant temperature deviates from a predetermined value, and even if the temperature of the reformed gas flowing into the carbon monoxide removal apparatus deviates from the target value due to this influence, it flows into the carbon monoxide removal apparatus. The temperature of the reformed gas can be changed to the target temperature.
[0084]
In the eighth embodiment shown in FIG. 10, the fuel cell stack 18 in the configuration of the fifth embodiment has a refrigerant (hereinafter referred to as a refrigerant C, which exchanges heat with the heat exchanger 2 and the carbon monoxide removing devices 3 and 4). A circulation device that circulates A + B) is added.
[0085]
The refrigerant C discharged from the refrigerant pump 19 flows into the fuel cell stack 18, cools the fuel cell stack 18, and flows into the refrigerant radiator 25. In the refrigerant radiator 25, the refrigerant C exchanges heat with the refrigerant flowing into the refrigerant radiator 25 from the carbon monoxide removing device 4, and cools the refrigerant. The refrigerant C whose temperature has been raised by heat exchange with the refrigerant flows into the refrigerant A radiator 20 and radiates heat to the outside.
[0086]
However, during partial load operation or the like, the amount of heat released from the refrigerant in the refrigerant radiator 20 exceeds the amount of heat absorbed by the refrigerant in the fuel cell stack 18 and the refrigerant radiator 25, and the temperature of the refrigerant C falls below a predetermined value. It is possible. Therefore, a flow path 23 that bypasses the refrigerant radiator 20 is provided, and when the amount of heat absorption is small, the refrigerant A is also introduced into the bypass flow path 23 and the temperature of the refrigerant C is controlled to a predetermined temperature. In order to control the temperature of the refrigerant, a thermostat 21 is installed at the junction of the main flow path 27 and the bypass flow path 28, and the opening of the thermostat 21 is controlled to control the flow path of the refrigerant C, thereby controlling the temperature of the refrigerant. To do.
[0087]
With such a configuration, it is not necessary to install a blower fan for heat exchange or to install a radiator near the outside air introduction unit as compared with the case where heat is exchanged with the outside air using the refrigerant radiator 25. There is an effect of downsizing and cost reduction.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration at the time of startup of a fuel reformer in a first embodiment.
FIG. 2 is a view showing the relationship between the catalyst temperature and the position in the carbon monoxide removing device.
FIG. 3 is a diagram showing a configuration at the time of startup of a fuel reformer in a second embodiment.
FIG. 4 is a diagram showing a configuration at the time of startup of a fuel reformer in a third embodiment.
FIG. 5 is a flowchart for explaining control contents of a controller according to a third embodiment.
FIG. 6 is a diagram showing a configuration at the time of startup of a fuel reformer in a fourth embodiment.
FIG. 7 is a diagram showing a configuration at the start of a fuel reformer in a fifth embodiment.
FIG. 8 is a diagram showing a configuration at the start of a fuel reformer in a sixth embodiment.
FIG. 9 is a diagram showing a configuration at the start of a fuel reformer in a seventh embodiment.
FIG. 10 is a diagram showing a configuration at the start of a fuel reformer in an eighth embodiment.
[Explanation of symbols]
A Heat exchanger refrigerant
B Refrigerant for carbon monoxide removal device
C Refrigerant for fuel cell stack
Common refrigerant for A + B heat exchanger and carbon monoxide remover
1 Reformer
2 Heat exchanger
3 Carbon monoxide removal equipment
4 Carbon monoxide removal equipment
5 Low temperature refrigerant pump
6 Low temperature radiator
10 High-temperature refrigerant pump
11 Radiator for high temperature
18 Fuel cell stack

Claims (11)

A reformer that produces reformed gas containing hydrogen;
At least one carbon monoxide removing device including a catalyst layer for removing carbon monoxide contained in the reformed gas;
A heat exchanger that is interposed between the reformer and the carbon monoxide removal device and into which the reformed gas is introduced;
In a fuel reformer equipped with
A first circulation device for circulating a first refrigerant in the heat exchanger and controlling a temperature of the first refrigerant;
A second circulating device for circulating a second refrigerant in the carbon monoxide removing device and controlling a temperature of the second refrigerant;
The fuel reformer characterized in that the temperature of the first refrigerant is set lower than the temperature of the second refrigerant.   The fuel reformer according to claim 1, further comprising a heat exchanger common to the first circulation device and the second circulation device. Flow rate adjusting means for adjusting the flow rate of the first refrigerant flowing into the heat exchanger;
Temperature detecting means for detecting the temperature of the reformed gas flowing into the carbon monoxide removing device,
The fuel reformer according to claim 2, wherein the flow rate of the first refrigerant is adjusted so that the temperature of the reformed gas becomes a predetermined value.   The fuel reformer according to claim 1, wherein the first circulation device circulates the first refrigerant to the fuel cell stack. A reformer that produces reformed gas containing hydrogen;
At least one carbon monoxide removing device including a catalyst layer for removing carbon monoxide contained in the reformed gas;
A heat exchanger that is interposed between the reformer and the carbon monoxide removal device and into which the reformed gas is introduced;
In the fuel reformer, comprising a circulation device that circulates the refrigerant to the heat exchanger and the carbon monoxide removal device and controls the temperature of the refrigerant,
The refrigerant flows through the heat exchanger and then flows through the carbon monoxide removing device, and the temperature of the refrigerant flowing into the heat exchanger is set lower than the temperature of the refrigerant flowing through the carbon monoxide removing device. The fuel reformer characterized by the above-mentioned.   The fuel reformer according to claim 5, wherein the circulation device includes a bypass passage for allowing the refrigerant to bypass the heat exchanger. Refrigerant temperature calculation means for predicting the heat absorption amount of the refrigerant in the heat exchanger, and calculating the temperature of the refrigerant flowing into the carbon monoxide removal device based on the predicted heat absorption amount,
The fuel reformer according to claim 5 or 6, wherein the temperature of the refrigerant flowing into the heat exchanger is set so that the temperature of the refrigerant flowing into the carbon monoxide removing device becomes a predetermined value. Flow rate control means for controlling the flow rate of the refrigerant flowing into the heat exchanger;
Temperature detecting means for detecting the temperature of the reformed gas flowing into the carbon monoxide removing device,
The fuel reformer according to claim 6, wherein the flow rate control means is controlled so that the temperature of the reformed gas becomes a predetermined temperature based on a detection value of the temperature detection means. A fuel cell stack circulating device for circulating a refrigerant in the fuel cell stack is provided.
The fuel reformer according to claim 5 or 6, wherein the heat dissipation of the refrigerant in the circulation device is performed by heat exchange with the refrigerant for the fuel cell stack. The fuel reformer according to claim 1, wherein the temperature of the second refrigerant is set from the activation temperature of the catalyst layer of the carbon monoxide removing device. The fuel reformer according to any one of claims 5 to 8, wherein the temperature of the refrigerant is set from an activation temperature of a catalyst layer of the carbon monoxide removing device.

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