JP2015022863A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system that can keep a hydrodesulfurizer at a proper temperature even when the power generation amount of the fuel cell system is small.SOLUTION: An air supply device 9 supplies air to a combustion air supply passage 10 so that an air flow rate measured by a combustion air meter 18 does not fall below an air flow rate required to maintain stable combustion of a burner 7 which is matched with a power generation amount of a fuel cell 8. When the temperature of a hydrodesulfurizer 3 which is detected by a desulfurization temperature detector 21 exceeds a first temperature threshold value, a cooling air amount adjusting mechanism 16 of a cooling air supply passage 15 which is branched from some middle point of the combustion air supply passage 10 and has a hydrodesulfurization cooler 14 is opened, and the hydrodesulfurization cooler 14 cools the hydrodesulfurizer 3. When the flow rate of air supplied to the burner 7 which is measured by the combustion air meter 18 exceeds the air flow rate required to maintain the stable combustion of the burner 7 which is matched with the power generation amount of the fuel cell 8, an exhaust air amount adjusting mechanism 20 exhausts excess air from an exhaust passage 19.

Description

  The present invention relates to a fuel cell system that generates power using a hydrogen-containing gas obtained by desulfurizing a raw material and then reforming the raw material.

  The fuel cell system includes a hydrogen generator that reforms a hydrocarbon-based raw material to generate hydrogen, a fuel cell that generates power using hydrogen supplied from the hydrogen generator, and direct-current power generated by the fuel cell. It is configured by an inverter circuit for converting into electric power and a control device for controlling them.

  There are various types of fuel cells depending on the type of electrolyte used. Currently, polymer electrolyte fuel cells are in widespread use.

  As a reforming method of the hydrogen generator, a steam reforming method in which hydrogen is obtained by catalytic reaction of a hydrocarbon-based raw material and steam at a high temperature is the mainstream.

  In addition, natural gas city gas, LP gas, kerosene, biogas, etc. are used as raw materials. These include sulfur added as an odorant or originally contained in the raw materials. The sulfur content was mixed.

  These sulfur components poison the catalyst used for steam reforming of the hydrogen generator and deprive its activity. Therefore, the sulfur content in the raw material needs to be desulfurized before being supplied to the hydrogen generator.

  Currently, the desulfurization method is an adsorption desulfurization method that removes sulfur by passing it through a desulfurizer filled with an adsorbent that adsorbs at room temperature. There are two methods of hydrodesulfurization, which are converted into an adsorbent and then removed.

  The adsorptive desulfurization method is very easy to handle, but because the adsorption capacity is relatively small, the desulfurizer replacement frequency increases when the sulfur content in the raw material is high, and the overall price also increases. is there.

  On the other hand, the hydrodesulfurization method has a relatively large adsorption capacity, but the unsaturated hydrocarbon or oxygen contained in the raw material reacts with hydrogen for hydrodesulfurization and generates heat. If the raw material contains unsaturated hydrocarbons or oxygen enough to cause a temperature rise that deviates from the temperature range suitable for the hydrodesulfurization reaction and adsorption reaction, the hydrodesulfurization catalyst loses its desulfurization performance due to thermal degradation. There is a disadvantage that it ends up.

  Therefore, a temperature sensor is provided to detect the temperature in the hydrodesulfurizer vessel or the outlet of the hydrodesulfurizer, and a cooling heat exchanger is provided on the outer surface of the hydrodesulfurizer vessel. When a rise in the temperature of the desulfurizer is detected, a part of the air supplied from the air supply device to the fuel cell system is bypassed and passed through the cooling heat exchanger, thereby suppressing the temperature rise of the hydrodesulfurizer. A configuration has been proposed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-214632

  However, in the conventional configuration disclosed in Patent Document 1, the amount of air flowing through the cooling heat exchanger that cools the hydrodesulfurizer may exceed the amount of air supplied from the air supply device to the fuel cell system. Therefore, when the amount of air used in the operation of the fuel cell system is small, that is, when the power generation amount of the fuel cell system is relatively small, the amount of air that cools the hydrodesulfurizer with the cooling heat exchanger However, there was a problem that the hydrodesulfurizer could not be sufficiently cooled by the cooling heat exchanger.

  Therefore, in view of the above-described conventional problems, the present invention provides a fuel cell that can maintain a hydrodesulfurizer at an appropriate temperature using air supplied from an air supply device of a fuel cell system even when the amount of power generation is small. The purpose is to provide a system.

  In order to achieve the above object, a fuel cell system of the present invention is a combustion that burns using anode off-gas containing combustible components discharged from a fuel cell and air supplied from an air supply device via a combustion air supply path. And a reformer that steam-reforms the hydrocarbon-based raw material heated by the combustion of the combustor and whose flow rate is adjusted by the raw material flow rate regulator to generate a hydrogen-containing gas used for power generation of the fuel cell, , Located in the flow path of the raw material between the raw material flow controller and the reformer, and in the vicinity of the reformer so as to be heated to a predetermined temperature under the influence of heat of the reformer A hydrodesulfurizer which is supplied with a part of the hydrogen-containing gas generated by the reformer and the raw material from the raw material flow controller to remove sulfur in the raw material by hydrodesulfurization; Combustion air supply from the air supply device The combustion air is branched from a first branch point in the middle of the combustion air supply path so that at least part of the air supplied to the passage flows, and at the first junction point downstream from the first branch point. A cooling air supply path that merges with the supply path, and air that is provided in the middle of the cooling air supply path so as to be able to exchange heat with the hydrodesulfurizer, flows through the cooling air supply path and flows through the interior. A hydrodesulfurization cooler that cools the desulfurizer; and an air supply path between the outlet of the hydrodesulfurization cooler in the cooling air supply path and the first junction or the combustion air supply path Air that is branched from one of the air supply paths between the first junction and the air inlet of the combustor and that is supplied to the combustor is necessary for maintaining stable combustion. Excess so as not to exceed the flow rate A discharge path for discharging air halfway, and a combustion air supply path between a second branch point serving as a branch point from the combustion air supply path to the discharge path and an air inlet of the combustor. A combustion air flow meter that measures the flow rate of air flowing through, a desulfurization temperature detector that detects the temperature of the hydrodesulfurizer, and a branch amount of air that branches from the first branch point to the cooling air supply path are adjusted. A cooling air amount adjusting mechanism, and a discharge air amount adjusting mechanism for adjusting a branch amount of air branched from the second branch point to the discharge path. The cooling air amount adjusting mechanism is controlled by the desulfurization temperature detector. When the temperature of the hydrodesulfurizer to be detected rises to a temperature exceeding a first temperature threshold set so as not to exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer, from the first branch point Branch to the cooling air supply path The amount of air branching is increased, and the exhaust air amount adjusting mechanism is configured such that the air flow rate measured by the combustion air flow meter is in accordance with either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. When the air flow rate necessary for maintaining stable combustion of the combustor is exceeded, the amount of air branching from the second branch point to the discharge path is increased so that excess air is discharged from the discharge path, The air supply device has an air flow measured by the combustion air flow meter, and the air required for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. Air is supplied to the combustion air supply path so as not to fall below the flow rate.

In the above configuration, when the fuel cell system is operated (power generation), the hydrodesulfurizer reacts with hydrogen for hydrodesulfurization so that unsaturated hydrocarbons and oxygen contained in the raw material exceed the upper limit temperature of the hydrodesulfurizer. Except in special cases where heat is generated at a high temperature, it is configured to be heated to a predetermined temperature (substantially appropriate temperature that is higher than the lower limit temperature of the hydrodesulfurizer and lower than the upper limit temperature) under the influence of the heat of the reformer. Yes.

  In addition, the air supply device is configured such that the air flow rate measured by the combustion air flow meter is an air flow rate necessary for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. Air is supplied to the combustion air supply path so as not to fall below.

  If the unsaturated hydrocarbon or oxygen contained in the raw material reacts with hydrogen for hydrodesulfurization, it generates heat, changes in environmental temperature, disturbances such as deterioration of reformer catalyst performance over time, and changes over time When the temperature of the hydrodesulfurizer detected by the desulfurization temperature detector rises to a temperature exceeding the first temperature threshold set so as not to exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer, the cooling air The amount adjusting mechanism increases the amount of air branched from the first branch point to the cooling air supply path.

  As the amount of air branching from the first branch point to the cooling air supply path increases, the flow rate of air flowing through the hydrodesulfurization cooler increases, so that the air flowing through the hydrodesulfurization cooler and hydrogenation flow. Since the amount of heat exchange with the desulfurizer increases, the hydrodesulfurization cooler increases the ability to cool the hydrodesulfurizer, and the temperature rise of the hydrodesulfurizer is suppressed, so the cooling air increased by the cooling air amount adjustment mechanism If the air flow rate in the supply path is set appropriately, the temperature of the hydrodesulfurizer can be prevented from exceeding the upper limit temperature.

  Also, if the air flow rate measured by the combustion air flow meter does not fall below the air flow rate necessary to maintain stable combustion in the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell As described above, the air supply device supplies air to the combustion air supply path, the cooling air amount adjustment mechanism increases the amount of air branching from the first branch point to the cooling air supply path, The air flow rate supplied to the combustor measured by the combustion air flow meter is either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell due to at least one of the fact that the amount has become relatively small. When the air flow rate necessary for maintaining stable combustion of the combustor according to the air flow exceeds the exhaust air amount adjustment mechanism, the excess air is discharged from the discharge path branched from the middle of the combustion air supply path. The combustion can be stabilized.

  Therefore, the flow rate of air flowing to the hydrodesulfurization cooler for cooling the hydrodesulfurizer is limited so that the air flow rate supplied to the combustor is the upper limit so that the temperature of the hydrodesulfurizer does not exceed the upper limit temperature. Therefore, even when the power generation amount is small, the hydrodesulfurizer can be maintained at an appropriate temperature by using the air supplied from the air supply device of the fuel cell system to the combustor.

  According to the present invention, even when the power generation amount is small, the hydrodesulfurizer can be maintained at an appropriate temperature using the air supplied from the air supply device of the fuel cell system to the combustor. High performance can be maintained without degrading performance.

1 is a schematic configuration diagram of a fuel cell system according to Embodiment 1 of the present invention. The characteristic view for demonstrating the relationship between the air flow rate of each part of the fuel cell system by Embodiment 1 of this invention, and electric power generation amount The characteristic view for demonstrating the relationship between the air flow rate of each part of the fuel cell system by Embodiment 2 of this invention, and electric power generation amount Schematic configuration diagram of a fuel cell system according to Embodiment 3 of the present invention Schematic configuration diagram of a fuel cell system according to Embodiment 4 of the present invention Schematic configuration diagram of a modification of the fuel cell system according to Embodiment 4 of the present invention.

  According to a first aspect of the present invention, there is provided a combustor that burns using an anode off gas containing a combustible component discharged from a fuel cell and air supplied from an air supply device via a combustion air supply path, and combustion of the combustor. A reformer that generates a hydrogen-containing gas to be used for power generation of the fuel cell by steam-reforming a hydrocarbon-based raw material that has been heated and whose flow rate has been adjusted by the raw material flow rate regulator, the raw material flow rate regulator, and the modified Located in the flow path of the raw material between the reformer and disposed near the reformer so as to be heated to a predetermined temperature under the influence of the heat of the reformer and generated by the reformer A hydrodesulfurizer that supplies a part of the hydrogen-containing gas and the raw material from the raw material flow controller to remove sulfur content in the raw material by a hydrodesulfurization method, and supplies the combustion air from the air supply device At least of the air supplied to the path A cooling air supply path that branches from a first branch point in the middle of the combustion air supply path so as to flow through and joins the combustion air supply path at a first junction downstream from the first branch point; A hydrodesulfurization cooler that is provided in the middle of the cooling air supply path so as to be capable of exchanging heat with the hydrodesulfurization apparatus, and in which air flowing through the cooling air supply path flows inside to cool the hydrodesulfurization apparatus; , An air supply path between the air outlet of the hydrodesulfurization cooler in the cooling air supply path and the first confluence, or the first confluence in the combustion air supply path and the air of the combustor Excess air so that the flow rate of air supplied to the combustor by branching from any one of the air supply routes to the inlet of the engine does not exceed the air flow required for maintaining stable combustion Discharge route for discharging The flow rate of combustion air for measuring the flow rate of air flowing through the combustion air supply path between the second branch point, which is a branch point from the combustion air supply path to the discharge path, and the air inlet of the combustor A desulfurization temperature detector for detecting the temperature of the hydrodesulfurizer, a cooling air amount adjusting mechanism for adjusting a branch amount of air branched from the first branch point to the cooling air supply path, and the second A fuel cell system including a discharge air amount adjustment mechanism for adjusting a branch amount of air branched from the branch point to the discharge path, wherein the cooling air amount adjustment mechanism detects the water detected by the desulfurization temperature detector. When the temperature of the hydrodesulfurizer rises to a temperature exceeding a first temperature threshold set so as not to exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer, the cooling air supply from the first branch point Of air branching into the path The amount of branching is increased, and the exhaust air amount adjustment mechanism is configured such that the air flow rate measured by the combustion air flow meter is equal to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. When the air flow rate necessary for maintaining stable combustion is exceeded, the amount of air branched from the second branch point to the discharge path is increased so that excess air is discharged from the discharge path, and the air supply device The air flow rate measured by the combustion air flow meter is lower than the air flow rate necessary for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. Air is supplied to the combustion air supply path so as not to rotate.

  In the above configuration, when the fuel cell system is operated (power generation), the hydrodesulfurizer reacts with hydrogen for hydrodesulfurization so that unsaturated hydrocarbons and oxygen contained in the raw material exceed the upper limit temperature of the hydrodesulfurizer. Except in special cases where heat is generated at a high temperature, it is configured to be heated to a predetermined temperature (substantially appropriate temperature that is higher than the lower limit temperature of the hydrodesulfurizer and lower than the upper limit temperature) under the influence of the heat of the reformer. Yes.

  In addition, the air supply device is configured such that the air flow rate measured by the combustion air flow meter is an air flow rate necessary for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. Air is supplied to the combustion air supply path so as not to fall below.

  By the way, in this type of general fuel cell system, in order to stabilize the combustion characteristics of the combustor (burner), the combustion air ratio (actually supplied) is the ratio of the fuel combusted by the combustor (burner) to the combustion air. Combustion air supplied to the combustor (burner) so that the ratio A / Ao) between the air amount A and the theoretical air amount (the minimum air amount Ao required for complete combustion of the combustible gas) Ao) The amount is adjusted.

  Further, the amount of hydrogen consumed by the fuel cell is an amount corresponding to the electric power to be generated when the same fuel cell is used. However, fuel cells cannot consume all of the supplied hydrogen for power generation due to problems such as flooding. Therefore, the hydrogen generator is operated by controlling with a controller so that the proportion of the amount of hydrogen used for power generation out of the amount of hydrogen supplied to the fuel cell, that is, the hydrogen utilization rate, is approximately constant.

  The anode off-gas discharged from the fuel cell is mainly composed of unused hydrogen that has been supplied to the fuel cell but not used for power generation.

  Therefore, the raw material flow rate of the raw material flow rate controller, the power generation amount of the fuel cell, and the amount of combustion air supplied to the combustor (burner) are in correlation with each other.

  If the unsaturated hydrocarbon or oxygen contained in the raw material reacts with hydrogen for hydrodesulfurization, it generates heat, changes in environmental temperature, disturbances such as deterioration of reformer catalyst performance over time, and changes over time When the temperature of the hydrodesulfurizer detected by the desulfurization temperature detector rises to a temperature exceeding the first temperature threshold set so as not to exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer, the cooling air The amount adjusting mechanism increases the amount of air branched from the first branch point to the cooling air supply path.

  As the amount of air branching from the first branch point to the cooling air supply path increases, the flow rate of air flowing through the hydrodesulfurization cooler increases, so that the air flowing through the hydrodesulfurization cooler and hydrogenation flow. Since the amount of heat exchange with the desulfurizer increases, the hydrodesulfurization cooler increases the ability to cool the hydrodesulfurizer, and the temperature rise of the hydrodesulfurizer is suppressed, so the cooling air increased by the cooling air amount adjustment mechanism If the air flow rate in the supply path is set appropriately, the temperature of the hydrodesulfurizer can be prevented from exceeding the upper limit temperature.

  Also, if the air flow rate measured by the combustion air flow meter does not fall below the air flow rate necessary to maintain stable combustion in the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell As described above, the air supply device supplies air to the combustion air supply path, the cooling air amount adjustment mechanism increases the amount of air branching from the first branch point to the cooling air supply path, The air flow rate supplied to the combustor measured by the combustion air flow meter is either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell due to at least one of the fact that the amount has become relatively small. When the air flow rate necessary for maintaining stable combustion of the combustor according to the air flow exceeds the exhaust air amount adjustment mechanism, the excess air is discharged from the discharge path branched from the middle of the combustion air supply path. The combustion can be stabilized.

  Therefore, the flow rate of air flowing to the hydrodesulfurization cooler for cooling the hydrodesulfurizer is limited so that the air flow rate supplied to the combustor is the upper limit so that the temperature of the hydrodesulfurizer does not exceed the upper limit temperature. Therefore, even when the amount of power generation is small, the hydrodesulfurizer can be maintained at an appropriate temperature by using the air supplied from the air supply device of the fuel cell system to the combustor, and the performance of the hydrodesulfurizer is reduced. High performance can be maintained without causing

  The first invention can be configured such that the controller controls the cooling air amount adjusting mechanism, the exhaust air amount adjusting mechanism, and the air supply device. In that case, it is as follows.

  When the temperature of the hydrodesulfurizer detected by the desulfurization temperature detector rises to a temperature exceeding a first temperature threshold set so as not to exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer, Under the control of the controller, the cooling air amount adjusting mechanism increases the amount of air branched from the first branch point to the cooling air supply path.

  Further, the air flow rate measured by the combustion air flow meter exceeds the air flow rate necessary for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. Then, under the control of the controller, the exhaust air amount adjustment mechanism increases the amount of air that branches from the second branch point to the discharge path so that excess air is discharged from the discharge path.

  In addition, the air flow rate measured by the combustion air flow meter is lower than the air flow rate necessary for maintaining stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. The air supply device supplies air to the combustion air supply path by the control of the controller so as not to rotate.

  In the second invention, the cooling air amount adjusting mechanism in the first invention is provided in the middle of the cooling air supply path to open and close the air flow path, and is provided in the middle of the cooling air supply path. A controllable on-off valve (for example, an electromagnetic valve or an on-off valve capable of adjusting the opening of the valve) can be used as the cooling air amount adjusting mechanism.

  Here, when the temperature of the hydrodesulfurizer is equal to or lower than the first temperature threshold, the on-off valve is in a fully closed state so that air does not flow into the cooling air supply path (hydrodesulfurization cooler). And those having two states of open state.

  The on-off valve also cools the hydrodesulfurizer with the hydrodesulfurization cooler even in normal times, so that the cooling air supply path (hydrodesulfurization cooler) is used even when the temperature of the hydrodesulfurizer is lower than the first temperature threshold. If the air is allowed to flow in (2), the one having two states of a finely opened state and a fully opened state is used.

  In addition, when using an on-off valve that can adjust the opening of the valve, the flow rate of air flowing through the cooling air supply path (hydrodesulfurization cooler) is changed in multiple stages according to the temperature of the hydrodesulfurization unit. Alternatively, the valve can be further opened when the temperature of the hydrodesulfurizer does not drop sufficiently even after a predetermined time has passed since the valve was opened.

  According to a third aspect of the present invention, in the second aspect of the present invention, the flow path resistor includes a flow path resistor capable of adjusting a flow path resistance between the first branch point and the first merge point in the combustion air supply path. When the cooling air amount adjusting mechanism increases the amount of air branched from the first branch point to the cooling air supply path, the resistor has the first branch point and the first junction point in the combustion air supply path. The flow resistance between the first branch point and the first junction point in the combustion air supply path is increased so that the air flow rate between the first and second merging points decreases in the cooling air supply path. When the cooling air amount adjusting mechanism reduces the amount of air branching from the first branch point to the cooling air supply path, the first branch point and the first junction point in the combustion air supply path The air flow rate between It is intended to reduce the flow resistance between the first branching point in the combustion air supply path as increased by decrease amount of the air flow rate and the first junction of the feed path.

  In the above configuration, even if the amount of air branched into the cooling air supply path is increased or decreased by the cooling air amount adjusting mechanism that is provided in the middle of the cooling air supply path and opens and closes the air flow path, it merges at the first junction. Since the air flow rate in the subsequent combustion air supply path does not fluctuate, the operation of the cooling air amount adjustment mechanism does not affect the air flow rate supplied to the combustor, the operation of the exhaust air amount adjustment mechanism, and the operation of the air supply device. Therefore, when the controller controls the cooling air amount adjusting mechanism, the flow path resistor, the discharged air amount adjusting mechanism, and the air supply device, the control of the controller can be simplified.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the fuel cell generates power less than the predetermined power generation amount so that air is discharged from the discharge path only when the fuel cell generates power with a power generation amount smaller than the predetermined power generation amount. In the case where the amount of power is generated, the air supply device has approximately the same air flow rate required for maintaining stable combustion of the combustor at a predetermined power generation amount regardless of the power generation amount of the fuel cell in the combustion air supply path. In the case where the air is supplied at a constant air flow rate, and the controller controls the cooling air amount adjusting mechanism, the flow path resistor, the exhaust air amount adjusting mechanism, and the air supply device, from the third invention Can also simplify the control of the controller.

  In a fifth aspect based on the third aspect, when the air supply device supplies air to the combustion air supply path, the air is always discharged from the discharge path regardless of the power generation amount of the fuel cell. The air supply device supplies air to the combustion air supply path at a constant air flow rate exceeding the air flow rate necessary for maintaining stable combustion of the combustor at the time of maximum power generation regardless of the power generation amount of the fuel cell. When the controller controls the cooling air amount adjusting mechanism, the flow path resistor, the discharged air amount adjusting mechanism, and the air supply device, the control of the controller can be made simpler than the fourth invention. The air supply device having a fixed air supply capability can be used.

  According to a sixth invention, in the first or second invention, a combustion exhaust gas path for discharging the combustion exhaust gas from the combustor, and a heat recovery heat exchange disposed in the combustion exhaust gas path for recovering heat of the combustion exhaust gas The cooling air supply path at the second branch point between the air outlet of the hydrodesulfurization cooler and the first junction in the cooling air supply path. And the exhaust air amount adjusting mechanism is configured such that the cooling air amount adjusting mechanism is the same as the cooling air amount adjusting mechanism. When the amount of air branching from the first branch point to the cooling air supply path is increased, the amount of air branching from the second branch point to the discharge path is increased, and the air supply device Volume Mechanism when the increase branching amount of air branches to the cooling air supply path from the first branching point, is to increase the air flow rate of air supplied to the combustion air supply path.

  As a result, the air that has passed through the hydrodesulfurization cooler joins the combustion exhaust gas path via the exhaust path, and the air discharged from the exhaust path is a heat recovery heat exchanger for recovering the heat of the combustion exhaust gas. Therefore, the heat of the air heated by the hydrodesulfurization cooler can be efficiently recovered.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, Embodiment 1 of the fuel cell system according to the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a schematic configuration diagram showing a hydrogen generator of a fuel cell system and its peripheral part in Embodiment 1 of the present invention.

  In FIG. 1, a hydrocarbon-based raw material such as city gas is flow-controlled by a raw material flow controller 2, then generated in a reforming reaction unit 6 (reformer) described later, and supplied to a fuel cell 8. Then, it is mixed with a part of the reformed gas mainly composed of hydrogen and supplied to a cylindrical hydrodesulfurizer 3 heated to a temperature range of 200 ° C. to 300 ° C.

The hydrodesulfurizer 3 is filled with a hydrodesulfurization catalyst comprising copper and zinc oxides, and the sulfur content contained in the raw material is converted to hydrogen sulfide by reacting with hydrogen on this catalyst. It is later taken into the adsorbent.

  The raw material desulfurized by the hydrodesulfurizer 3 is mixed with the water supplied from the water supply device 5 through the pipe 4 and is heated by the combustion gas flowing through the combustion gas passage 11 described later. To a cylindrical evaporation section (not shown). The water sent to the evaporation unit together with the raw material is heated in the evaporation unit to become water vapor, and the mixed gas of the raw material and water vapor is sent to the reforming reaction unit 6 (reformer) filled with the ruthenium catalyst.

  A burner 7 as a combustor disposed at the center of the hydrogen generator 1 burns anode off-gas containing combustible components discharged from the fuel cell 8 as combustion gas, generates high-temperature combustion gas, and evaporates And the reforming reaction section 6 is heated. At this time, air necessary for combustion is supplied from the air supply device 9 to the burner 7 via the combustion air supply path 10.

  The high-temperature combustion gas generated by the burner 7 passes through the combustion gas passage 11 and is discharged from the combustion exhaust gas passage 12.

  The reforming reaction section 6 is heated from 500 ° C. to 600 ° C. by the combustion gas passing through the combustion gas flow path 11 to cause a steam reforming reaction, and consists of hydrogen, carbon dioxide, and carbon monoxide from the raw material and steam. Generate reformed gas.

  The reformed gas is supplied to the fuel cell 8 through a carbon monoxide reduction unit (not shown) that reduces carbon monoxide, which is a poisoning substance of the fuel cell 8.

  Further, the hydrodesulfurizer 3 is disposed in the vicinity of the reforming reaction section 6 via the heat insulating material 13 so as to be heated to a predetermined temperature of 200 ° C. to 300 ° C.

  The hydrodesulfurizer 3 is provided with a hydrodesulfurization cooler 14 at a position where heat exchange with the hydrodesulfurizer 3 is possible. This hydrodesulfurization cooler 14 branches from the first branch point A in the middle of the combustion air supply path 10 and is combusted air so as to form a detour that merges at the first junction B in the middle of the combustion air supply path 10. Arranged in the middle of the cooling air supply path 15 connected to the supply path 10, the air supplied from the air supply device 9 passes through the inside as a cooling medium.

  The reforming reaction section 6 (reformer) of the hydrogen generator 1 has a cylindrical shape, a burner 7 is disposed at the central shaft portion thereof, and the hydrodesulfurizer 3 is connected to the reforming reaction section 6 (reformer). ), And the hydrodesulfurization cooler 14 has an annular shape for cooling the hydrodesulfurizer 3.

  In order to adjust the amount of air flowing through the flow path of the cooling air supply path 15, a cooling air amount adjusting mechanism 16 is disposed in the cooling air supply path 15, and the first branch point A and the first branch point A of the combustion air supply path 10 are arranged. Between one junction point B, a flow path resistor 17 capable of adjusting the flow path resistance is disposed.

  Further, a combustion air flow meter 18 is provided immediately before the burner 7 in the combustion air supply path 10 to constantly measure the amount of combustion air supplied to the burner 7.

  In addition, in order to discharge a part of the air that flows from the second branch point C between the combustion air flow meter 18 and the first junction B to the combustion air supply path 10 and circulates in the combustion air supply path 10. The discharge path 19 is connected, and the discharge path 19 is provided with a discharge air amount adjusting mechanism 20 that adjusts the amount of air branched from the second branch point C to the discharge path 19.

  Further, the hydrodesulfurizer 3 is provided with a desulfurization temperature detector 21 using a thermocouple inserted into the hydrodesulfurizer 3 as means for measuring the temperature of the hydrodesulfurizer 3.

  Further, based on the power generation amount of the fuel cell 8, the temperature of the desulfurization temperature detector 21, and the combustion air flow rate of the combustion air flow meter 18, the air supply device 9, the cooling air amount adjustment mechanism 16, the exhaust air amount adjustment mechanism 20, A controller 22 for controlling the flow path resistor 17 is provided.

  These operations will be briefly described. It is necessary to control the temperature of the hydrodesulfurizer 3 to be 300 ° C. or less, which is the upper limit temperature of the desulfurization catalyst. Therefore, in this embodiment, the high temperature side control temperature is set to 290 ° C.

  When the temperature measured by the desulfurization temperature detector 21 is 290 ° C. or less, the cooling air amount adjusting mechanism 16 is closed, and the air from the air supply device 9 is not allowed to flow through the hydrodesulfurization cooler 14. In this case, the hydrodesulfurizer 3 is not cooled by the hydrodesulfurization cooler 14.

  When the temperature measured by the desulfurization temperature detector 21 exceeds 290 ° C., the controller 22 opens the cooling air amount adjusting mechanism 16 that is normally closed. When the cooling air amount adjusting mechanism 16 is opened, part of the air from the air supply device 9 is sent to the hydrodesulfurization cooler 14 via the cooling air supply path 15, and the hydrodesulfurization cooler 14 is hydrogenated. The desulfurizer 3 is cooled. Thereafter, when the temperature of the desulfurization temperature detector 21 is lowered to a temperature lower than 290 ° C. (for example, 270 ° C.), the cooling air amount adjusting mechanism 16 is closed.

  In this way, by controlling the amount of air supplied to the hydrodesulfurization cooler 14, the excessive temperature rise of the hydrodesulfurization unit 3 is suppressed and controlled to be equal to or lower than the upper limit temperature (300 ° C.).

  If the air supply amount of the air supply device 9 and the flow passage resistance of the flow passage resistor 17 are constant, the flow passage resistance from the air supply device 9 to the burner 7 is changed by opening and closing the cooling air amount adjusting mechanism 16. Therefore, the amount of air supplied to the burner 7 changes due to the opening and closing of the cooling air amount adjusting mechanism 16, but in this embodiment, the combustion of the burner 7 is stabilized before and after the cooling air amount adjusting mechanism 16 is opened. In order to maintain the controller, the controller 22 links the cooling air amount adjusting mechanism 16 with the opening / closing operation so that the amount of combustion air supplied to the burner 7 does not change even when the cooling air amount adjusting mechanism 16 is opened / closed. The flow path resistance of the flow path resistor 17 is controlled.

  The operation of the fuel cell system of the present embodiment configured as described above will be described with reference to FIG.

  FIG. 2 shows the power generation amount of the fuel cell 8, the amount of combustion air supplied to the burner 7 (thick line), the required amount of cooling air supplied to the hydrodesulfurization cooler 14 (thin line), and the total amount of air combining them. The relationship with (broken line) is shown.

  Here, in order to make the drawing easy to see, the total air amount shown by the broken line is drawn slightly shifted upward. Α represents the minimum power generation amount, and β represents the maximum power generation amount.

  As an example, the amount of combustion air indicated by a thick line is about 5 L / min for the minimum power generation amount and about 20 L / min for the maximum power generation amount. On the other hand, the required amount of cooling air indicated by a thin line supplied to the hydrodesulfurization cooler 14 for cooling the hydrodesulfurizer 3 is about 8 L / min regardless of the amount of power generation.

  Therefore, the amount of combustion air shown by the thick line and the required amount of cooling air shown by the thin line intersect as shown in the figure. This intersecting power generation amount is indicated by γ.

When the power generation amount is between γ and β, the amount of combustion air is larger than the required amount of cooling air. Therefore, the air supplied to the hydrodesulfurization cooler 14 by opening and closing the cooling air amount adjusting mechanism 16 as described above. Can cover the amount.

  In the case of the above-described operation, the flow path resistor 17 is in a state of closing the flow path at the power generation amount of γ. However, when the power generation amount is between α and γ, the required amount of cooling air is larger than the amount of combustion air, so the amount of air supplied to the burner 7 becomes excessive.

  Therefore, the fuel cell system according to Embodiment 1 is configured to exhaust this excess air from the discharge path 19.

  The amount of air to be exhausted controls the opening degree of the exhaust air amount adjusting mechanism 20 so that the amount of air flowing through the combustion air flow meter 18 becomes a predetermined amount of air with respect to the power generation amount. The amount of air to be exhausted is larger as the amount of power generated is lower.

  In the first embodiment, the cooling air amount adjusting mechanism 16 is described as opening and closing. However, in order to adjust the temperature of the hydrodesulfurizer 3 more precisely, the cooling air amount adjusting mechanism 16 is opened and closed. Instead, the flow rate of air introduced into the hydrodesulfurization cooler 14 may be precisely adjusted by adjusting the opening degree stepwise or continuously.

  Further, the power generation amount of γ is determined by characteristics unique to the hydrogen generator such as the heating amount of the hydrodesulfurizer 3 and the cooling performance of the hydrodesulfurization cooler 14, and is smaller than the maximum power generation amount and arbitrarily larger than the minimum power generation amount. The amount of power generation is sufficient.

  In the first embodiment, the second branch point C is provided between the combustion air flow meter 18 and the first junction B. However, the second branch point C is provided between the hydrodesulfurization cooler 14 and the first junction B. Also good.

  Further, in the first embodiment, a thermocouple directly inserted into the hydrodesulfurizer 3 is used as the desulfurization temperature detector 21 for measuring the temperature of the hydrodesulfurizer 3. However, the desulfurization temperature detector 21 is not limited to a thermocouple as long as it can measure the temperature of the hydrodesulfurizer 3, and is not limited to being inserted into the hydrodesulfurizer 3. .

  More specifically, since the hydrodesulfurizer 3 is arranged to be heated by the reforming reaction unit 6, the temperature of the hydrodesulfurization unit 3 naturally has a correlation with the temperature of the reforming reaction unit 6. . Further, the temperature is not limited to the temperature of the reforming reaction unit 6 and is omitted in FIG. 1, but there is a correlation with the temperature of the carbon monoxide reduction unit that reduces carbon monoxide. And since the temperature of these locations is an important value for operation control of the hydrogen generator 1, each temperature is measured by installing a thermocouple.

  Therefore, instead of directly measuring the temperature of the hydrodesulfurizer 3, the temperature of the hydrodesulfurizer 3 may be obtained from the correlation with the temperature of the reforming reaction unit 6 and the carbon monoxide reducing unit.

  Although it has been described that the hydrodesulfurizer 3 is heated by the heat of the reforming reaction section 6, strictly speaking, it is heated by the heat of the entire hydrogen generator 1 such as a carbon monoxide reduction section to maintain the temperature. It is what.

  In the present embodiment, the combustion air flow meter 18 is provided immediately upstream of the burner 7 in order to measure the amount of combustion air supplied to the burner 7. However, the present invention is directed to the amount of air supplied to the burner 7. There is no limitation on the means for measuring.

For example, an air flow meter may be installed in the discharge path 19 without using the combustion air flow meter 18. In this case, using a positive displacement pump as the air supply device 9, the supply air amount is obtained from the rotational speed, and the flow amount value of the air flow meter installed in the discharge path 19 is subtracted to calculate the air amount supplied to the burner 7. You may do it.

  According to this embodiment, the temperature of the hydrodesulfurizer 3 can always be maintained at a predetermined temperature even if the power generation amount changes, so that the hydrodesulfurizer should be used with high performance without degrading the performance. Can do.

  As described above, the fuel cell system according to the present embodiment uses the anode off-gas containing combustible components discharged from the fuel cell 8 and the air supplied from the air supply device 9 via the combustion air supply path 10. Combustion burner 7 (combustor) and hydrogen-containing gas used for power generation of the fuel cell 8 by steam reforming the hydrocarbon-based raw material heated by the combustion of the burner 7 and adjusted in flow rate by the raw material flow rate regulator 2 Is located in the reforming reaction section 6 (reformer) for generating the raw material flow path between the raw material flow rate controller 2 and the reforming reaction section 6 and is affected by the heat of the reforming reaction section 6 A part of the reformed gas (hydrogen-containing gas) generated in the reforming reaction section 6 disposed in the vicinity of the reforming reaction section 6 so as to be heated to a predetermined temperature (for example, 200 ° C. to 300 ° C.) and the raw material flow rate The raw material from the controller 2 is supplied and the sulfur in the raw material is supplied. In the middle of the combustion air supply path 10 so that at least a part of the hydrodesulfurizer 3 for removing the components by the hydrodesulfurization system and the air supplied from the air supply device 9 to the combustion air supply path 10 flows. The cooling air supply path 15 branches from the first branch point A and joins the combustion air supply path 10 at the first junction B downstream of the first branch point A, and the hydrodesulfurizer 3 is cooled so that heat can be exchanged. A hydrodesulfurization cooler 14 that is provided in the middle of the air supply path 15 and flows through the cooling air supply path 15 flows inside to cool the hydrodesulfurizer 3, and hydrodesulfurization in the cooling air supply path 15. An air supply path between the air outlet of the cooler 14 and the first confluence B, or an air supply path between the first confluence B in the combustion air supply path 10 and the air inlet of the burner 7. A bar branched from one of the air supply paths -Exhaust path 19 for discharging excess air halfway so that the air flow rate supplied to -7 does not exceed the air flow rate necessary for maintaining stable combustion, and from the combustion air supply path 10 to the exhaust path 19 The temperature of the combustion air flow meter 18 that measures the flow rate of air flowing through the combustion air supply path 10 between the second branch point C, which is a branch point, and the air inlet of the burner 7, and the temperature of the hydrodesulfurizer 3. A desulfurization temperature detector 21 to detect, a cooling air amount adjusting mechanism 16 for adjusting the amount of air branched from the first branch point A to the cooling air supply path 15, and a branch from the second branch point C to the discharge path 19. And an exhaust air amount adjusting mechanism 20 that adjusts the amount of air branching.

  The cooling air amount adjusting mechanism 16 prevents the temperature of the hydrodesulfurizer 3 detected by the desulfurization temperature detector 21 from exceeding the upper limit temperature based on the upper limit temperature (for example, 300 ° C.) of the hydrodesulfurizer 3. When the temperature rises to a temperature exceeding a first temperature threshold (for example, 290 ° C.) set to, the amount of air branched from the first branch point A to the cooling air supply path 15 is increased. If the air flow rate measured by the combustion air flow meter 18 exceeds the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate regulator 2 or the power generation amount of the fuel cell 8, it will be exceeded. The amount of air branched from the second branch point C to the discharge path 19 is increased so that the minute air is discharged from the discharge path 19, and the air supply device 9 has an air flow rate measured by the combustion air flow meter 18, material Since air is supplied to the combustion air supply path 10 so as not to fall below the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the quantity regulator 2 or the power generation amount of the fuel cell 8. is there.

  The fuel cell system of the present embodiment has a combustion air ratio, which is the ratio of the fuel burned by the burner 7 and the combustion air, in order to stabilize the combustion characteristics of the burner 7 as in this type of general fuel cell system. The amount of combustion air supplied to the burner 7 is adjusted so as to be approximately constant.

Further, the amount of hydrogen consumed by the fuel cell 8 is an amount corresponding to the electric power to be generated when the same fuel cell 8 is used. However, the fuel cell 8 cannot consume all the supplied hydrogen for power generation due to problems such as flooding. Therefore, the hydrogen generator 1 is operated by being controlled by the controller 22 so that the ratio of the amount of hydrogen used for power generation out of the amount of hydrogen supplied to the fuel cell 8, that is, the hydrogen utilization rate is approximately constant. .

  The anode off-gas discharged from the fuel cell 8 is mainly composed of unused hydrogen that has been supplied to the fuel cell 8 but not used for power generation.

  Therefore, the raw material flow rate of the raw material flow rate controller 2, the power generation amount of the fuel cell 8, and the amount of combustion air supplied to the burner 7 are in correlation with each other.

  If the unsaturated hydrocarbon or oxygen contained in the raw material reacts with hydrogen for hydrodesulfurization, it generates heat, changes in ambient temperature, disturbances such as deterioration of catalyst performance of the reforming reaction section 6 over time, The first temperature is set so that the temperature of the hydrodesulfurizer 3 detected by the desulfurization temperature detector 21 does not exceed the upper limit temperature based on the upper limit temperature (for example, 300 ° C.) of the hydrodesulfurizer 3. When the temperature rises to a temperature exceeding a temperature threshold (for example, 290 ° C.), the cooling air amount adjusting mechanism 16 increases the amount of air branched from the first branch point A to the cooling air supply path 15.

  When the amount of air branching from the first branch point A to the cooling air supply path 15 increases, the flow rate of air flowing through the hydrodesulfurization cooler 14 increases, thereby flowing through the hydrodesulfurization cooler 14. Since the amount of heat exchange between the air and the hydrodesulfurizer 3 increases, the ability of the hydrodesulfurization cooler 14 to cool the hydrodesulfurizer 3 increases, and the temperature rise of the hydrodesulfurizer 3 can be suppressed. If the air flow rate of the cooling air supply path 15 to be increased by the amount adjusting mechanism 16 is appropriately set, the temperature of the hydrodesulfurizer 3 can be prevented from exceeding the upper limit temperature.

  Also, if the air flow rate measured by the combustion air flow meter 18 is lower than the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The air supply device 9 supplies air to the combustion air supply path 10 so that the air does not rotate, and the amount of air branched by the cooling air amount adjusting mechanism 16 from the first branch point A to the cooling air supply path 15 is increased. The flow rate of air supplied to the burner 7 measured by the combustion air flow meter 18 is caused by the flow rate of the raw material flow controller 2 due to at least one of the fact that the amount of power generated by the fuel cell 8 is relatively small. When the air flow rate necessary for maintaining stable combustion of the burner 7 corresponding to either the raw material flow rate or the power generation amount of the fuel cell 8 is exceeded, the exhaust air amount adjustment mechanism 20 sends the excess air to the combustion air supply path. Since discharged from the discharge path 19 which is branched from the middle of 0, the combustion of the burner 7 can be stabilized.

  Therefore, the air flow rate that flows through the hydrodesulfurization cooler 14 for cooling the hydrodesulfurization device 3 so that the temperature of the hydrodesulfurization device 3 does not exceed the upper limit temperature is the upper limit of the air flow rate supplied to the burner 7. Thus, even when the power generation amount of the fuel cell 8 is small, the hydrodesulfurizer 3 can be maintained at an appropriate temperature by using the air supplied to the burner 7 from the air supply device 9 of the fuel cell system. Further, the performance of the hydrodesulfurizer 3 can be maintained as it is without reducing the performance.

  In the present embodiment, the controller 22 controls the cooling air amount adjusting mechanism 16, the discharged air amount adjusting mechanism 20, and the air supply device 9.

  That is, the first temperature threshold value set so that the temperature of the hydrodesulfurizer 3 detected by the desulfurization temperature detector 21 does not exceed the upper limit temperature based on the upper limit temperature (for example, 300 ° C.) of the hydrodesulfurizer 3. When the temperature rises above (for example, 290 ° C.), the cooling air amount adjusting mechanism 16 increases the amount of air branched from the first branch point A to the cooling air supply path 15 by the control of the controller 22.

  Further, when the air flow rate measured by the combustion air flow meter 18 exceeds the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. Under the control of the controller 22, the discharge air amount adjustment mechanism 20 increases the amount of air branched from the second branch point C to the discharge path 19 so that excess air is discharged from the discharge path 19.

  Further, the air flow rate measured by the combustion air flow meter 18 is lower than the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The air supply device 9 supplies air to the combustion air supply path 10 by the control of the controller 22 so as not to change.

  In the present embodiment, the cooling air amount adjusting mechanism 16 is provided in the middle of the cooling air supply path 15 to open and close the air flow path, and can be controlled to be opened and closed in the middle of the cooling air supply path 15. A simple on-off valve (for example, an electromagnetic valve or an on-off valve capable of adjusting the opening of the valve) can be used as the cooling air amount adjusting mechanism 16.

  Here, the on-off valve as the cooling air amount adjusting mechanism 16 does not flow air into the cooling air supply path 15 (hydrodesulfurization cooler 14) when the temperature of the hydrodesulfurizer 3 is equal to or lower than the first temperature threshold. If so, one having two states, a fully closed state and an open state, is used.

  The on-off valve as the cooling air amount adjusting mechanism 16 is a water-cooling device for cooling the hydrodesulfurizer 3 by the hydrodesulfurization cooler 14 even under normal conditions due to factors such as the installation environment of the fuel cell system and aging deterioration. Even if the temperature of the hydrodesulfurizer 3 is equal to or lower than a first temperature threshold (for example, 290 ° C.), if air is allowed to flow through the cooling air supply passage 15 (hydrodesulfurization cooler 14), the state is slightly opened. A thing having two states of a fully open state is used.

  When an on-off valve capable of adjusting the opening of the valve is used as the cooling air amount adjusting mechanism 16, it flows through the cooling air supply path 15 (hydrodesulfurization cooler 14) according to the temperature of the hydrodesulfurizer 3. The air flow rate can be changed in multiple stages, or the valve can be further opened when the temperature of the hydrodesulfurizer 3 does not drop sufficiently even after a predetermined time has elapsed since the valve was opened. .

  In the present embodiment, the flow path resistor 17 capable of adjusting the flow path resistance is provided between the first branch point A and the first junction B in the combustion air supply path 10.

  The flow path resistor 17 is connected to the first branch point A and the first branch point A in the combustion air supply path 10 when the cooling air amount adjusting mechanism 16 increases the amount of air branching from the first branch point A to the cooling air supply path 15. The flow path between the first junction point A and the first junction point B in the combustion air supply path 10 so that the air flow rate between the first junction point B is reduced by the increase in the air flow rate in the cooling air supply path 15. The resistance is increased, and when the cooling air amount adjusting mechanism 16 reduces the amount of air branched from the first branch point A to the cooling air supply path 15, the first branch point A in the combustion air supply path 10 is reduced. Between the first junction point B and the first junction point B in the combustion air supply path 10 so that the air flow rate between the first junction point B and the first junction point B increases by the amount of decrease in the air flow rate in the cooling air supply path 15. This is to reduce the flow path resistance.

In the above configuration, even if the amount of air branched to the cooling air supply path 15 is increased or decreased by the cooling air amount adjusting mechanism 16 provided in the middle of the cooling air supply path 15 to open and close the air flow path, Since the air flow rate of the combustion air supply path 10 after merging does not change at the point B, the operation of the cooling air amount adjusting mechanism 16 is the operation of the air flow rate supplied to the burner 7, the operation of the discharged air amount adjusting mechanism 20, and the air supply device. 9 does not affect the operation of the cooling air amount adjusting mechanism 1.
6, the flow path resistor 17, the discharged air amount adjusting mechanism 20, and the air supply device 9 can be controlled easily.

  Further, in the present embodiment, the fuel cell 8 has a power generation amount smaller than the predetermined power generation amount γ so that air is discharged from the discharge path 19 only when the fuel cell 8 generates power with a power generation amount smaller than the predetermined power generation amount γ. When power is being generated, the controller 22 controls the air supply device 9 to maintain stable combustion of the burner 7 at a predetermined power generation amount γ regardless of the power generation amount of the fuel cell 8 in the combustion air supply path 10. When air is supplied at a constant air flow rate substantially equal to the air flow rate (for example, about 8 L / min) and the fuel cell 8 is generating power with a power generation amount equal to or greater than a predetermined power generation amount γ, the control of the controller 22 is performed. Thus, the air supply device 9 supplies air to the combustion air supply path 10 at an air flow rate necessary for maintaining stable combustion of the burner 7 according to the amount of power generated by the fuel cell 8, and the control of the controller 22 is simplified. Can be.

  In the present embodiment, when the fuel cell 8 generates power with a power generation amount equal to or greater than the predetermined power generation amount γ, the air supply device 9 is connected to the combustion air supply path 10 by the control of the controller 22. Since air is supplied at an air flow rate necessary for maintaining stable combustion of the burner 7 according to the amount of power generation, the opening degree of the valve when the on-off valve constituting the cooling air amount adjusting mechanism 16 is open is determined by the fuel cell 8. If the power generation amount of the fuel cell 8 is larger, the flow rate of air supplied to the hydrodesulfurization cooler 14 when the on-off valve constituting the cooling air amount adjusting mechanism 16 is opened is larger. The capacity for cooling the hydrodesulfurizer 3 is increased.

(Embodiment 2)
Hereinafter, a fuel cell system according to a second embodiment of the present invention will be described. The same components as those of the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

  The configuration of the hydrogen generator of the fuel cell system and its peripheral part in the second embodiment is the same as that of the first embodiment shown in FIG.

  The fuel cell system according to the first embodiment generates power less than the predetermined power generation amount γ so that the fuel cell 8 discharges air from the discharge path 19 only when the power generation amount is smaller than the predetermined power generation amount γ. When the amount of power is generated, the controller 22 controls the air supply device 9 to maintain stable combustion of the burner 7 at the predetermined power generation amount γ regardless of the power generation amount of the fuel cell 8 in the combustion air supply path 10. When air is supplied at a constant air flow rate that is substantially the same amount as the required air flow rate (for example, about 8 L / min), and the fuel cell 8 is generating power with a power generation amount equal to or greater than a predetermined power generation amount γ, the controller 22 With this control, the air supply device 9 supplies air to the combustion air supply path 10 at an air flow rate necessary for maintaining stable combustion of the burner 7 according to the power generation amount of the fuel cell 8.

  In contrast, in the fuel cell system of Embodiment 2, when the air supply device 9 supplies air to the combustion air supply path 10, air is always discharged from the discharge path 19 regardless of the amount of power generated by the fuel cell 8. As described above, the air supply device 9 supplies the combustion air supply path 10 with an air flow rate (for example, about 20 L / min) necessary for maintaining stable combustion of the burner 7 at the maximum power generation β regardless of the power generation amount of the fuel cell 8. Air is supplied at a constant air flow rate exceeding.

  FIG. 3 shows the power generation amount of the fuel cell 8 of the fuel cell system of the present embodiment, the amount of combustion air supplied to the burner 7 (thick line), and the required amount of cooling air supplied to the hydrodesulfurization cooler 14 (thin line). , And the total air amount (broken line) combined with them.

  In the present embodiment, the opening degree of the valve when the on-off valve constituting the cooling air amount adjusting mechanism 16 is open is constant regardless of the power generation amount of the fuel cell 8.

  Since the temperature of the hydrodesulfurizer 3 is not so much related to the power generation amount of the fuel cell 8, when cooling the hydrodesulfurizer 3 with the hydrodesulfurization cooler 14, the required amount of cooling air to be supplied to the hydrodesulfurization cooler 14 Is substantially constant regardless of the amount of power generated by the fuel cell 8. Therefore, the air supply device 9 needs to supply a constant amount of air regardless of the amount of power generation.

  Therefore, in the present embodiment, an air flow rate that is slightly higher than the combustion air flow rate (for example, about 20 L / min) required at the time of maximum power generation is supplied from the air supply device 9, and the air is more than the air amount supplied to the burner 7. Is always discharged from the discharge path 19.

  Also in the present embodiment, the cooling air amount adjustment mechanism 16 opens and closes the cooling air supply path 15 according to the temperature of the desulfurization temperature detector 21 as in the first embodiment.

  As described above, in the present embodiment, when the air supply device 9 supplies air to the combustion air supply path 10, the air is always discharged from the discharge path 19 regardless of the power generation amount of the fuel cell 8. Regardless of the power generation amount of the fuel cell 8, the air supply device 9 has a constant flow rate exceeding the air flow rate (for example, about 20 L / min) necessary for maintaining stable combustion of the burner 7 at the maximum power generation β regardless of the power generation amount of the fuel cell 8 If air is supplied at an air flow rate and the flow rate of the exhaust air amount adjusting mechanism 20 is adjusted so that the air flow rate passing through the combustion air flow meter 18 becomes a predetermined value corresponding to the power generation amount of the fuel cell 8. Since it is good, the control of the controller 22 is very simple.

(Embodiment 3)
Hereinafter, Embodiment 3 of the fuel cell system of the present invention will be described with reference to FIG. 4, but the same components as those in Embodiment 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  FIG. 4 is a schematic configuration diagram showing a hydrogen generator of a fuel cell system and its peripheral part in Embodiment 3 of the present invention.

  In this embodiment, instead of the channel resistor 17 capable of adjusting the channel resistance in the first or second embodiment, a channel resistor 17 ′ having a constant (fixed) channel resistance is used. Other configurations are the same as those in the first or second embodiment.

  In the present embodiment, instead of the channel resistor 17 capable of adjusting the channel resistance in the first or second embodiment, the channel resistor 17 ′ having a constant (fixed) channel resistance is used. The flow path resistance from the air supply device 9 to the burner 7 is changed by opening and closing the air amount adjusting mechanism 16.

  Therefore, the controller 22 opens and closes the cooling air amount adjusting mechanism 16 so that the flow rate of air supplied to the burner 7 (the air flow rate measured by the combustion air flow meter 18) hardly changes by opening and closing the cooling air amount adjusting mechanism 16. At the time of operation, at least one of the air flow rate from the air supply device 9 and the exhaust air amount adjusting mechanism 20 is controlled in accordance with the opening / closing operation of the cooling air amount adjusting mechanism 16.

  For example, when the cooling air amount adjusting mechanism 16 is opened, the exhaust air amount adjusting mechanism 20 is configured such that the air flow rate measured by the combustion air flow meter 18 is the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. When the air flow rate necessary for maintaining stable combustion of the burner 7 according to any of the above is exceeded, the excess air is discharged from the discharge path 19 so that the air branched from the second branch point C to the discharge path 19 Increase the amount of branching.

When the cooling air amount adjusting mechanism 16 is closed when the excess air is being discharged from the discharge path 19 by the exhaust air amount adjusting mechanism 20, the exhaust air amount adjusting mechanism 20 is controlled by the combustion air flow meter 18. From the second branch point C, the measured air flow rate becomes an air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The amount of air branching into the discharge path 19 is reduced.

  Alternatively, when the cooling air amount adjusting mechanism 16 is opened, the air supply device 9 determines whether the air flow rate measured by the combustion air flow meter 18 is the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. When the air flow rate necessary for maintaining stable combustion of the burner 7 corresponding to the above is exceeded, the air flow rate measured by the combustion air flow meter 18 is either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The air supply capacity is lowered so that the air flow rate necessary for maintaining stable combustion of the burner 7 according to

  When the cooling air amount adjusting mechanism 16 is closed, the air supply device 9 determines whether the air flow rate measured by the combustion air flow meter 18 is the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. When the air flow rate required for maintaining stable combustion of the burner 7 according to the above becomes lower, the air flow rate measured by the combustion air flow meter 18 is either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The air supply capacity is increased so as to obtain an air flow rate necessary for maintaining stable combustion of the burner 7 according to the above.

  If the cooling air amount adjusting mechanism 16 is opened / closed, the air flow rate measured by the combustion air flow meter 18 can be obtained only by the independent operation of the exhaust air amount adjusting mechanism 20 in accordance with the opening / closing operation of the cooling air amount adjusting mechanism 16. If the air flow rate required for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8 cannot be achieved, The air flow rate measured by the combustion air flow meter 18 is an air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the raw material flow rate controller 2 or the power generation amount of the fuel cell 8. The air supply capacity of the air supply device 9 is adjusted.

(Embodiment 4)
Hereinafter, Embodiment 4 of the fuel cell system of the present invention will be described with reference to FIG. 5. The same components as those in Embodiments 1 to 3 described above are denoted by the same reference numerals and detailed description thereof will be made. Description is omitted.

  FIG. 5 is a schematic configuration diagram showing a hydrogen generator of a fuel cell system and its peripheral part in Embodiment 4 of the present invention.

  In the present embodiment, the combustion exhaust gas from the burner 7 is recovered in the configuration of the third embodiment so that the heat obtained by the hydrodesulfurization cooler 14 can be recovered together with the heat held in the combustion exhaust gas from the burner 7. A heat recovery heat exchanger 23 that recovers the heat of the combustion exhaust gas is further provided in the middle of the exhaust combustion gas path 12 to be discharged, and the exhaust path 19 is connected to the air outlet portion of the hydrodesulfurization cooler 14 in the cooling air supply path 15. The cooling air supply path 15 is changed so as to branch from the cooling air supply path 15 at the second branch point C between the first confluence B and the combustion exhaust gas than the heat recovery heat exchanger 23 in the combustion exhaust gas path 12 on the outlet side of the discharge path 19. It is comprised so that it may join to the 2nd junction point D of upstream.

  The exhaust air amount adjusting mechanism 20 branches from the second branch point C to the discharge path 19 when the cooling air amount adjusting mechanism 16 increases the amount of air branching from the first branch point A to the cooling air supply path 15. The air supply device 9 supplies the combustion air supply path 10 with the air supply device 9 when the cooling air quantity adjustment mechanism 16 increases the amount of air branching from the first branch point A to the cooling air supply path 15. The air flow rate of the air to be increased is increased.

  Furthermore, in the present embodiment, the heat recovered by the heat recovery heat exchanger 23 is used for preheating reformed water supplied to the water supplier 5 through the reformed water supply pipe 24.

  If the structure of this Embodiment is used, the heat | fever of the air warmed by the hydrodesulfurization cooler 14 and discharged | emitted from the discharge path 19 can be collect | recovered, and a heat loss can be reduced. In addition, this Embodiment does not limit utilization of the collect | recovered heat to preheating of reformed water.

  The present embodiment includes a flue gas path 12 that discharges flue gas from the burner 7, and a heat recovery heat exchanger 23 that is disposed in the flue gas path 12 and collects the heat of the flue gas from the burner 7. The discharge path 19 branches from the cooling air supply path 15 at a second branch point C between the air outlet of the hydrodesulfurization cooler 14 in the cooling air supply path 15 and the first confluence B, and the combustion exhaust gas The exhaust air amount adjusting mechanism 20 is cooled from the first branch point A by the cooling air amount adjusting mechanism 20 so as to join the second confluence point D upstream of the combustion exhaust gas from the heat recovery heat exchanger 23 in the path 12. When the amount of air branching to the air supply path 15 is increased, the amount of air branching from the second branch point C to the discharge path 19 is increased, and the air supply device 9 is configured so that the cooling air amount adjusting mechanism 16 is the first branch. Cooling from point A When increasing the amount of air branched into the air supply path 15, the air flow rate of the air supplied to the combustion air supply path 10 is increased, and the air that has passed through the hydrodesulfurization cooler 14 passes through the discharge path 19. The heat recovery heat exchanger 23 for recovering the heat of the combustion exhaust gas by joining the combustion exhaust gas path 12 can recover the heat of the air exhausted from the exhaust path 19 and is therefore warmed by the hydrodesulfurization cooler 14. The heat of the generated air can be recovered efficiently.

  In the modification of the fourth embodiment shown in FIG. 6, the cooling air supply path 15 having the hydrodesulfurization cooler 14 in the middle does not join the combustion air supply path 10, and the air is supplied more than the hydrodesulfurization cooler 14. The downstream cooling air supply path 15 also serves as the discharge path 19, and the discharge air amount adjustment mechanism 20 is eliminated from the discharge path 19.

  In this modification, the burner 7 that burns using the anode off-gas containing combustible components discharged from the fuel cell 8 and the air supplied from the air supply device 9 via the combustion air supply path 10, A reforming reaction unit 6 that steam-reforms a hydrocarbon-based raw material heated by combustion and whose flow rate is adjusted by the raw material flow rate regulator 2 to generate a hydrogen-containing gas used for power generation of the fuel cell 8, and a raw material Located in the raw material flow path between the flow rate controller 2 and the reforming reaction unit 6 and in the vicinity of the reforming reaction unit 6 so as to be heated to a predetermined temperature under the influence of heat of the reforming reaction unit 6 The hydrodesulfurization is arranged such that a part of the hydrogen-containing gas produced in the reforming reaction section 6 and the raw material from the raw material flow rate controller 2 are supplied and the sulfur content in the raw material is removed by the hydrodesulfurization method. Supplied to the combustion air supply path 10 from the vessel 3 and the air supply device 9. The cooling air supply path 15 branched from the first branch point A in the middle of the combustion air supply path 10 and the hydrodesulfurizer 3 so as to allow heat exchange so that at least a part of the air that flows is supplied. The hydrodesulfurization cooler 14 is provided in the middle of the path 15, and the air flowing through the cooling air supply path 15 flows inside to cool the hydrodesulfurizer 3, and the air at the first branch point A and the burner 7. A combustion air flow meter 18 for measuring the flow rate of the air flowing through the combustion air supply path 10 between the inlet portion and the desulfurization temperature detector 21 for detecting the temperature of the hydrodesulfurizer 3, and a first branch point A A cooling air amount adjusting mechanism 16 that adjusts the amount of air branched from the air to the cooling air supply path 15.

  The cooling air amount adjusting mechanism 16 is set so that the temperature of the hydrodesulfurizer 3 detected by the desulfurization temperature detector 21 does not exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer 3. When the temperature rises above the temperature threshold, the amount of air branched from the first branch point A to the cooling air supply path 15 is increased, and the air supply device 9 determines that the air flow rate measured by the combustion air flow meter 18 is the raw material flow rate. Air is supplied to the combustion air supply path 10 so as not to fall below the air flow rate necessary for maintaining stable combustion of the burner 7 according to either the raw material flow rate of the regulator 2 or the power generation amount of the fuel cell 8.

Even in the above configuration, the flow rate of air flowing to the hydrodesulfurization cooler 14 for cooling the hydrodesulfurizer 3 so that the temperature of the hydrodesulfurizer 3 does not exceed the upper limit temperature is the upper limit of the air flow rate supplied to the burner 7. Therefore, even when the power generation amount of the fuel cell 8 is small, the hydrodesulfurizer 3 is maintained at an appropriate temperature by using the air supplied from the air supply device 9 of the fuel cell system to the burner 7. Can do.

  The present invention can maintain the hydrodesulfurizer at an appropriate temperature using air supplied from the air supply device of the fuel cell system to the combustor even when the power generation amount is small. It can be applied to a domestic fuel cell system that includes a combustor that burns using the anode off-gas and a hydrodesulfurizer and that varies in power generation.

DESCRIPTION OF SYMBOLS 1 Hydrogen generator 2 Raw material flow controller 3 Hydrodesulfurizer 6 Reforming reaction part 7 Burner 8 Fuel cell 9 Air supply apparatus 10 Combustion air supply path 12 Combustion exhaust gas path 14 Hydrodesulfurization cooler 15 Cooling air supply path 16 Cooling Air flow rate adjustment mechanism 17 Flow path resistor 17 'Flow path resistor 18 Combustion air flow meter 19 Discharge path 20 Exhaust air amount adjustment mechanism 21 Desulfurization temperature detector 22 Controller 23 Heat recovery heat exchanger

Claims (6)

A combustor that burns using an anode off-gas containing a combustible component discharged from the fuel cell, and air supplied from an air supply device via a combustion air supply path;
A reformer that generates a hydrogen-containing gas to be used for power generation of the fuel cell by steam reforming a hydrocarbon-based raw material heated by combustion of the combustor and flow-regulated by a raw material flow regulator;
Located in the flow path of the raw material between the raw material flow controller and the reformer, in the vicinity of the reformer so as to be heated to a predetermined temperature under the influence of the heat of the reformer A hydrodesulfurizer that is disposed and is supplied with a part of the hydrogen-containing gas generated in the reformer and the raw material from the raw material flow controller, and removes sulfur in the raw material by a hydrodesulfurization method When,
Branching from a first branch point in the middle of the combustion air supply path and downstream from the first branch point so that at least a part of the air supplied from the air supply device to the combustion air supply path flows. A cooling air supply path that merges with the combustion air supply path at a first merging point of
A hydrodesulfurization cooler that is provided in the middle of the cooling air supply path so as to be able to exchange heat with the hydrodesulfurization apparatus, and in which air flowing through the cooling air supply path flows through the interior to cool the hydrodesulfurization apparatus When,
The air supply path between the air outlet of the hydrodesulfurization cooler in the cooling air supply path and the first confluence, or the first confluence in the combustion air supply path and the air inlet of the combustor Branch from any one of the air supply paths between the air flow path and the excess air flow so that the air flow rate supplied to the combustor does not exceed the air flow rate required to maintain stable combustion. A discharge route for discharging along the way,
Combustion air flow meter for measuring the flow rate of air flowing through the combustion air supply path between the second branch point serving as a branch point from the combustion air supply path to the discharge path and the air inlet of the combustor When,
A desulfurization temperature detector for detecting the temperature of the hydrodesulfurizer;
A cooling air amount adjusting mechanism that adjusts the amount of air branched from the first branch point to the cooling air supply path;
A discharge air amount adjusting mechanism for adjusting a branch amount of air branched from the second branch point to the discharge path;
With
The cooling air amount adjusting mechanism has a first temperature set so that the temperature of the hydrodesulfurizer detected by the desulfurization temperature detector does not exceed the upper limit temperature based on the upper limit temperature of the hydrodesulfurizer. When the temperature rises above the threshold, the amount of air branching from the first branch point to the cooling air supply path is increased,
The exhaust air amount adjusting mechanism is for maintaining stable combustion of the combustor according to whether the air flow rate measured by the combustion air flow meter is either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell. When the required air flow rate is exceeded, the amount of air branching from the second branch point to the discharge path is increased so that excess air is discharged from the discharge path,
The air supply device is required to maintain stable combustion of the combustor according to either the raw material flow rate of the raw material flow rate controller or the power generation amount of the fuel cell, as measured by the combustion air flow meter. Supplying air to the combustion air supply path so as not to fall below the air flow rate;
Fuel cell system.   The fuel cell system according to claim 1, wherein the cooling air amount adjusting mechanism is provided in the middle of the cooling air supply path to open and close an air flow path. A flow path resistor capable of adjusting a flow path resistance between the first branch point and the first merge point in the combustion air supply path;
The flow path resistor includes the first branch point and the first branch point in the combustion air supply path when the cooling air amount adjusting mechanism increases the amount of air branching from the first branch point to the cooling air supply path. Flow path resistance between the first branch point and the first junction point in the combustion air supply path so that the air flow rate between the first junction point and the air flow quantity in the cooling air supply path is reduced by an increase in the air flow rate. When the cooling air amount adjusting mechanism reduces the amount of air branching from the first branch point to the cooling air supply path, the first branch point and the first junction point in the combustion air supply path The flow resistance between the first branch point and the first junction point in the combustion air supply path is reduced so that the air flow rate between the first and second merging points increases by the amount of decrease in the air flow rate in the cooling air supply path. Of claim 2 Charge the battery system.   When the fuel cell is generating power with a power generation amount smaller than the predetermined power generation amount so that air is discharged from the discharge path only when the fuel cell is generating power with a power generation amount smaller than the predetermined power generation amount, the air supply The apparatus supplies air to the combustion air supply path at a constant air flow rate that is substantially the same as the air flow rate required to maintain stable combustion of the combustor at a predetermined power generation amount regardless of the power generation amount of the fuel cell. The fuel cell system according to claim 3.   When the air supply apparatus supplies air to the combustion air supply path, the air supply apparatus is connected to the combustion air supply path so that air is always discharged from the discharge path regardless of the power generation amount of the fuel cell. The fuel cell system according to claim 3, wherein air is supplied at a constant air flow rate that exceeds an air flow rate necessary for maintaining stable combustion of the combustor at the time of maximum power generation regardless of the power generation amount of the fuel cell. A combustion exhaust gas path for discharging the combustion exhaust gas from the combustor; and a heat recovery heat exchanger disposed in the combustion exhaust gas path for recovering the heat of the combustion exhaust gas,
The discharge path branches from the cooling air supply path at the second branch point between the air outlet of the hydrodesulfurization cooler in the cooling air supply path and the first confluence, and the combustion The heat recovery heat exchanger in the exhaust gas path is configured to join a second junction point upstream of the combustion exhaust gas,
The exhaust air amount adjustment mechanism is configured to air that branches from the second branch point to the discharge path when the cooling air amount adjustment mechanism increases a branch amount of air that branches from the first branch point to the cooling air supply path. Increase the amount of branching
The air supply device increases an air flow rate of air supplied to the combustion air supply path when the cooling air amount adjusting mechanism increases an amount of air branching from the first branch point to the cooling air supply path. The fuel cell system according to claim 1 or 2.

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