JP2008137866A - Fuel processor and operation control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel processor capable of stably manufacturing an appropriate quality hydrogen-containing gas corresponding to the variation of reforming load, and its operation control method. <P>SOLUTION: By estimating the treatable amount A of a hydrocarbon raw material at the temperature of a reforming catalyst layer and the treatable amount B of the reforming gas at the temperature of a shift reaction catalyst layer, the supply amount of the hydrocarbon raw material to be supplied to a reformer is determined based on less treatable amount of the treatable amount A and the treatable amount B. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an operation control method for a fuel processor.

  In recent years, fuel cell systems that generate electricity by electrochemical reaction between hydrogen and oxygen have attracted attention as environmentally friendly energy sources. In this fuel cell system, a fuel processor that reforms a hydrocarbon raw material to produce a hydrogen-containing gas having a high hydrogen concentration is used to supply hydrogen to a fuel cell stack that generates power. The fuel processor includes a reformer, a shift reactor, and a carbon monoxide selective oxidation (PROX) reactor. The reformer is provided with a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water, and the shift reactor includes carbon monoxide and steam in the reformed gas. A shift catalyst layer for producing a shift gas in which hydrogen concentration is further increased is produced by generating a shift reaction with the hydrogen monoxide, and the carbon monoxide selective oxidation reactor selects the carbon monoxide present in the shift gas. A carbon monoxide selective oxidation catalyst layer for reducing the carbon monoxide concentration by a selective oxidation reaction is provided.

In this fuel processor, in order to produce a hydrogen-containing gas of an appropriate quality and stably supply it to the fuel cell stack, the catalyst layers provided in each of the reformer, the shift reactor and the PROX reactor are And a predetermined temperature suitable for the reaction by each catalyst. In particular, the supply amount of the hydrocarbon raw material that can be processed by the fuel processor, that is, the reforming load, strongly depends on the temperatures of the reforming catalyst layer and the shift catalyst layer. Since the reformer, the shift reactor, and the PROX reactor are distributed and processed in this order, the reforming load is out of the range that can be processed by the catalyst layer provided in each reactor constituting the fuel processor P1. Then, the quality of the hydrogen-containing gas supplied from the fuel processor P1 to the fuel cell stack deteriorates rapidly. For example, when the hydrogen concentration is low, the desired power generation amount cannot be obtained, and when the carbon monoxide concentration is high, it causes poisoning of the power generation cells of the fuel cell stack. Therefore, as the actual hydrogen production amount in the fuel processor increases with respect to the theoretical hydrogen production amount per unit amount of hydrocarbon feed supplied to the fuel processor (reformer), the efficiency as the fuel processor improves. In addition, the lower the carbon monoxide concentration of the hydrogen-containing gas, the lower the adverse effect on the fuel cell stack.
In addition, in the case where the hydrocarbon raw material is a heavy raw material, there is a possibility of fatal damage to each catalyst and fuel cell stack when the content of unreacted heavy hydrocarbon is high. .

  In the fuel processor, the reforming load is adjusted according to the amount of power generation required for the fuel cell stack. That is, in order to supply a required amount of hydrogen to the fuel cell stack according to the amount of power generation, the reforming load is increased or decreased, and the temperature of each catalyst layer is kept in an appropriate range according to the variation of the reforming load. It is necessary to control the operation.

  Therefore, Patent Document 1 discloses a hydrocarbon raw material, water based on the gas temperatures from the reforming unit (reformer), the shift unit (shift reactor), and the purification unit (carbon monoxide selective oxidation reactor). In addition, it is described that the supply of air is controlled so that the catalyst in each reaction section is effectively operated so that the hydrogen can be stably supplied.

In general, in order to appropriately control the temperature of the catalyst layer in accordance with the reforming load, the relationship between the reforming load and the temperature of the catalyst layer in each reactor is examined by an experiment using a microreactor. In experiments using this microreactor, data such as that the reaction vessel shape is simple (single cylinder, etc.) and that the catalyst layer temperature can be adjusted to a constant temperature (from the catalyst inlet to the outlet) by methods such as external heater heating. Since the collection conditions are simple, the relationship between the reaction performed in the catalyst layer and the reaction rate is also simple. Therefore, in the experiment using this microreactor, it becomes possible to control the supply amount of the hydrocarbon raw material and the temperature of the catalyst layer to an appropriate range corresponding to the supply amount with a considerable accuracy. Based on this experimental data, the control conditions of each reactor are predicted to some extent.
JP 2003-238112 A (paragraph numbers 0010, 0014, 0021, 0028)

  However, the actual reactor adopts a structure that exchanges heat internally so that there is no energy loss, and efficiently supplies the heat generated by the reaction to another necessary site. Depending on the location, there is actually a large or small heat dissipation (especially with a small amount of processing such as a domestic fuel cell reformer, the ratio of the reformer surface area (heat radiation area) to the heat related to the internal reaction is very high. Therefore, heat generation and heat absorption due to internal reactions do not dominate the thermal relationship of the system (equipment) as in large facilities such as chemical plants.) It is a very complicated system including the dead part in the structure of the mass organ). Therefore, at the initial stage of the reactor design, the catalyst layer temperature distribution is predicted and taken into account to some extent, but the relationship between the highly accurate feed rate of hydrocarbon feedstock and the catalyst layer temperature is predicted. Therefore, it is very difficult to properly control the fuel processor. For this reason, the actual fuel processor operates the actual machine, actually measures the catalyst layer temperature and the feed amount of the hydrocarbon raw material, and determines the operation control conditions from the results. However, even with such data, it has been difficult to stably produce a hydrogen-containing gas of appropriate quality in response to the change in the reforming load and supply it to the fuel cell stack.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an operation control method for a fuel processor that can solve the above-described problems and can stably produce a hydrogen-containing gas of appropriate quality in response to temperature fluctuations of the catalyst in each reactor. And

The invention described in claim 1 includes a reformer in which a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water, and carbon monoxide in the reformed gas. A shift reactor in which a shift catalyst layer for producing a shift gas with increased hydrogen concentration is produced by causing a shift reaction between water and water vapor, and a selective oxidation reaction of carbon monoxide present in the shift gas. And a carbon monoxide selective oxidation reactor in which a carbon monoxide selective oxidation catalyst layer for reducing the carbon monoxide concentration is provided, wherein the fuel processor operates at a temperature of the reforming catalyst layer. The processable amount A of the hydrocarbon raw material and the processable amount B of the reformed gas at the temperature of the shift catalyst layer are obtained, and the lesser of the processable amount A and the processable amount B Based on the processing amount of And determines the supply amount of the hydrocarbon feedstock supplied to Kiaratame reformer.
Here, in the present invention, the treatable amount refers to the supply amount of hydrocarbon raw material in which the catalytic reaction is completed by the catalyst loaded in the reactor, for example, the reformer loaded in the reformer in the reformer. The amount of the hydrocarbon raw material supplied when the reforming reaction of the hydrocarbon raw material is sufficiently performed at the temperature by the quality catalyst and the reaction equilibrium is reached.

  According to the operation control method of the fuel processor, the processable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer and the processable amount B of the reformed gas at the temperature of the shift catalyst layer are obtained, and the processable amount By determining the supply amount of hydrocarbon raw material to be supplied to the reformer based on the smaller processable amount of A and processable amount B, it is appropriate according to the temperature fluctuation of each catalyst layer. It is possible to control the fuel processor so that a proper amount of hydrocarbon raw material can be supplied and a hydrogen-containing gas of appropriate quality can be produced stably. Thus, the fuel processor can be operated while keeping the temperature of each catalyst layer in an appropriate range.

  According to a second aspect of the present invention, in the fuel processor operation control method according to the first aspect, the treatable amount A and the treatable amount B are different for each of the reforming catalyst and the shift catalyst. Is determined based on a linear relationship that approximates a nonlinear relationship obtained in advance with respect to the temperature of the catalyst and the amount of catalyst that can be processed.

  According to this fuel processor operation control method, the treatable amount A and the treatable amount B are obtained in advance for the temperature of each catalyst and the treatable amount of the catalyst for each of the reforming catalyst and the shift catalyst. By deciding on the basis of the linear relationship that approximates the non-linear relationship, the hydrocarbon feedstock of the appropriate supply amount is supplied according to the temperature fluctuation of each catalyst layer, and the hydrogen of stable and appropriate quality is supplied. It becomes possible to control the fuel processor so that the contained gas can be produced.

  According to a third aspect of the present invention, in the fuel processor operation control method according to the first aspect, a shiftable amount C of the shift gas at a temperature of the carbon monoxide selective oxidation catalyst is obtained, and the treatable amount A And supply of the hydrocarbon raw material to be supplied to the reformer based on the smaller processable quantity of the processable quantity B and the processable quantity of the smallest processable quantity C. It is characterized by determining the quantity.

  According to this fuel processor operation control method, in addition to the treatable amount A and the treatable amount B, the shift gas treatable amount C at the temperature of the carbon monoxide selective oxidation catalyst is also considered. By determining the amount of hydrocarbon raw material to be supplied to the reformer, a more appropriate amount of hydrocarbon raw material is supplied according to the temperature fluctuation of each catalyst layer, and stable and appropriate quality hydrogen is supplied. It becomes possible to control the fuel processor so that the contained gas can be produced.

  According to a fourth aspect of the present invention, in the fuel processor operation control method according to the third aspect, the processable amount A, the processable amount B, and the processable amount C are the reforming catalyst and the shift catalyst. Each of the carbon monoxide selective oxidation catalysts is determined based on a linear relationship that approximates a nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst.

  According to this fuel processor operation control method, the treatable amount A, the treatable amount B, and the treatable amount C are determined for each of the reforming catalyst, the shift catalyst, and the carbon monoxide selective oxidation catalyst. By determining the temperature of each catalyst and the treatable amount of the catalyst based on a linear relationship that approximates a non-linear relationship obtained in advance, an appropriate amount of hydrocarbon is supplied according to the temperature variation of each catalyst layer. It is possible to control the fuel processor so that raw materials can be supplied and a hydrogen-containing gas of appropriate quality can be produced stably.

  The invention according to claim 5 is the operation control method for the fuel processor according to any one of claims 1 to 4, wherein the temperature of the reforming catalyst layer is a reformed gas outlet of the reformer. It is the temperature of the said reforming catalyst layer in the vicinity.

  According to this fuel processor operation control method, the temperature of the reforming catalyst layer in the vicinity of the reformed gas outlet of the reformer determines the composition of the reformed gas supplied from the reformer to the shift reactor. Therefore, it is effective to control the supply amount of the hydrocarbon raw material by determining the treatable amount A according to the temperature of the reforming catalyst layer in the vicinity of the reformed gas outlet of the reformer.

  The invention according to claim 6 is the fuel processor operation control method according to any one of claims 1 to 5, wherein the temperature of the shift catalyst layer is in the vicinity of the shift gas outlet of the shift reactor. It is the temperature of the shift catalyst layer.

  According to this fuel processor operation control method, the temperature of the shift catalyst layer in the vicinity of the shift gas outlet of the shift reactor determines the composition of the shift gas supplied from the shift reactor to the carbon monoxide selective oxidation reactor. It is effective to control the supply amount of the hydrocarbon raw material by determining the treatable amount B according to the temperature of the shift catalyst layer in the vicinity of the reformed gas outlet of the shift reactor.

  The invention according to claim 7 is the fuel processor operation control method according to any one of claims 3 to 6, wherein the temperature of the carbon monoxide selective oxidation catalyst layer is the carbon monoxide selective oxidation. It is the temperature of the carbon monoxide selective oxidation catalyst layer in the vicinity of the shift gas inlet of the reactor.

  According to this fuel processor operation control method, when the reaction rate in the carbon monoxide selective oxidation reactor is very slow, the carbon monoxide selective oxidation catalyst layer in the vicinity of the shift gas inlet of the carbon monoxide selective oxidation reactor. It is effective to control the supply amount of the hydrocarbon raw material by determining the treatable amount C according to the temperature of the gas.

  The invention according to claim 8 is the operation control method for the fuel processor according to any one of claims 1 to 7, wherein the processable amount B of the shift catalyst is a reformed gas of the shift reactor. Determined based on the hydrocarbon treatable amount B1 at the shift catalyst layer temperature near the inlet and the hydrocarbon feedstock treatable amount B2 at the shift catalyst layer temperature near the shift gas outlet of the shift reactor. It is characterized by being.

  According to this fuel processor operation control method, when the reaction in the shift reactor is relatively slow, the hydrocarbon treatable amount B1 at the temperature of the shift catalyst layer in the vicinity of the reformed gas inlet of the shift reactor. In addition, since it is necessary to ensure a wide temperature range in which the reaction can be performed, the processing is performed in consideration of the processable amount B2 of the hydrocarbon raw material at the temperature of the shift catalyst layer in the vicinity of the shift gas outlet of the shift reactor. It is effective to determine the possible amount B and control the supply amount of the hydrocarbon raw material.

  The invention according to claim 9 is a reformer in which a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water is provided, and carbon monoxide in the reformed gas. A shift reactor in which a shift reaction catalyst layer for producing a shift gas with increased hydrogen concentration is produced by causing a shift reaction between water and water vapor, and selective oxidation of carbon monoxide present in the shift gas. A carbon monoxide selective oxidation reactor having a carbon monoxide selective oxidation catalyst layer for reducing the carbon monoxide concentration by reacting, the reformer, the shift reactor, and the carbon monoxide selective oxidation reactor An operation control unit that controls the operation of the fuel processor, wherein the operation control unit detects a temperature of the reforming catalyst layer and a temperature of the shift reaction catalyst layer. Shift temperature detecting means to The reforming reaction calculating means for obtaining the treatable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer detected by the reforming temperature detecting means, and the shift reaction catalyst layer detected by the shift temperature detecting means Shift reaction calculating means for obtaining the processable amount B of the reformed gas at the temperature of the reformer, and the reformer based on the smaller processable amount of the processable amount A and the processable amount B. Reaction control means for controlling the supply amount of the hydrocarbon raw material to be supplied to.

  In this fuel processor, in the operation control unit, the reforming reaction calculation means obtains the treatable amount A of the hydrocarbon raw material according to the temperature of the reforming catalyst layer, and the shift reaction calculation means sets the temperature of the shift reaction catalyst layer to Accordingly, the processable amount B of the reformed gas is obtained, and the reaction control means supplies hydrocarbons to the reformer based on the smaller processable amount of the processable amount A and the processable amount B. By controlling the feed rate of the raw material, it is possible to supply a suitable feed amount of hydrocarbon raw material according to the temperature fluctuation of each catalyst layer, and to stably produce a hydrogen-containing gas of a proper quality. Become.

  A tenth aspect of the present invention is the fuel processor according to the ninth aspect, wherein the reforming reaction calculating means and the shift reaction calculating means include a catalyst for each of the reforming catalyst and the shift reaction catalyst. The processable amount A and the processable amount B are obtained based on a linear relationship that approximates a nonlinear relationship obtained in advance with respect to the temperature of the catalyst and the treatable amount of the catalyst.

  In this fuel processor, the reforming reaction calculating means and the shift reaction calculating means are a non-linearity determined in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst for each of the reforming catalyst and the shift reaction catalyst. By obtaining the treatable amount A and the treatable amount B on the basis of the relationship of the linear expression that approximates the relationship, an appropriate amount of hydrocarbon raw material is supplied according to the temperature fluctuation of each catalyst layer. Thus, it becomes possible to stably produce a hydrogen-containing gas of appropriate quality.

  According to an eleventh aspect of the present invention, there is provided a reformer in which a reforming catalyst layer for producing a reformed gas by causing a reforming reaction between a hydrocarbon raw material and water, and carbon monoxide in the reformed gas. A shift reactor in which a shift reaction catalyst layer for producing a shift gas with increased hydrogen concentration is produced by causing a shift reaction between water and water vapor, and selective oxidation of carbon monoxide present in the shift gas. A carbon monoxide selective oxidation reactor having a carbon monoxide selective oxidation catalyst layer for reducing the carbon monoxide concentration by reacting, the reformer, the shift reactor, and the carbon monoxide selective oxidation reactor An operation control unit that controls the operation of the fuel processor, wherein the operation control unit detects a temperature of the reforming catalyst layer and a temperature of the shift reaction catalyst layer. Shift temperature detecting means to A carbon monoxide selective oxidation temperature detection means for detecting the temperature of the carbon monoxide selective oxidation catalyst layer, and a processable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer detected by the reforming temperature detection means Reforming reaction calculating means for obtaining the shift reaction calculating means for obtaining the processable amount B of the reformed gas at the temperature of the shift reaction catalyst layer detected by the shift temperature detecting means, and the carbon monoxide selective oxidation temperature A carbon monoxide selective oxidation reaction calculating means for obtaining a processable amount C of the shift gas at the temperature of the carbon monoxide selective oxidation catalyst layer detected by the detecting means, the processable amount A, the processable amount B, and the Reaction control means for controlling the supply amount of hydrocarbon raw material to be supplied to the reformer based on the smaller processable amount of the processable amount C; Characterized in that it has.

  In this fuel processor, in the operation control unit, the reforming reaction calculation means obtains the treatable amount A of the hydrocarbon raw material according to the temperature of the reforming catalyst layer, and the shift reaction calculation means sets the temperature of the shift reaction catalyst layer to In response, the processable amount B of the reformed gas is obtained, the carbon monoxide selective oxidation reaction calculation means obtains the processable amount C of the shift gas according to the temperature of the carbon monoxide selective oxidation catalyst layer, and the reaction control means Each catalyst layer is controlled by controlling the amount of hydrocarbon raw material supplied to the reformer based on the smaller of the possible amount A, the treatable amount B, and the treatable amount C. According to the temperature fluctuation, it is possible to supply an appropriate amount of hydrocarbon raw material and stably produce a hydrogen-containing gas having an appropriate quality.

  The invention according to claim 12 is the fuel processor according to claim 11, wherein the reforming reaction calculation means, the shift reaction calculation means, and the carbon monoxide selective oxidation reaction calculation means are the reforming catalyst, the For each of the shift reaction catalyst and the carbon monoxide selective oxidation catalyst, the treatable amount A, based on the relationship of a linear expression that approximates a nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst, The processable amount B and the processable amount C are obtained.

  In this fuel processor, the treatable amount A, the treatable amount B, and the treatable amount C are determined with respect to the temperature of each catalyst and the treatable amount of the catalyst for each of the reforming catalyst, the shift catalyst, and the carbon monoxide selective oxidation catalyst. By deciding based on a linear relationship that approximates the nonlinear relationship obtained in advance, an appropriate amount of hydrocarbon raw material is supplied according to the temperature fluctuation of each catalyst layer, and stable and appropriate quality It becomes possible to produce the hydrogen-containing gas.

  According to the fuel processor operation control method of the present invention, in order to change the supply amount of the hydrocarbon raw material, that is, the reforming load, according to the processable amount in the catalyst layer of each reactor constituting the fuel processor, The quality of the hydrogen-containing gas supplied from the fuel processor to the fuel cell stack is maintained in an appropriate range. Since the actual hydrogen generation amount in the fuel processor can be increased with respect to the theoretical hydrogen generation amount per unit amount of the hydrocarbon raw material supplied to the fuel processor (reformer), as a fuel processor In addition, since the carbon monoxide concentration of the hydrogen-containing gas can be lowered, adverse effects on the fuel cell stack can be reduced.

  Further, since the processable amount is determined according to the temperature of the catalyst layer of each reactor, it is possible to realize an increase in the reforming load according to the performance of each reactor and to appropriately control the operation. In particular, in the inventions according to claims 2 and 4, the treatable amount is determined based on a linear relationship that approximates a nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst. It is possible to control with simple calculation.

  According to the fuel processor of the present invention, it is possible to stably supply a hydrogen-containing gas of an appropriate quality by supplying an appropriate amount of hydrocarbon raw material according to the temperature fluctuation of the catalyst layer in each reactor. Become.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 1 is a block diagram showing the main configuration of a fuel cell system according to the present invention.
The fuel cell system 1 includes a desulfurization device 2, a reformer 3, a shift reactor 4, a PROX (carbon monoxide (CO) selective oxidation) reactor 5, and a fuel cell stack 6. . In this fuel cell system 1, the desulfurization device 2, the reformer 3, the shift reactor 4, the PROX reactor 5, and the operation control unit 20 are connected to the anode electrode of the fuel cell stack 6 with a hydrogen-containing gas (hydrogen The fuel processor P1 is configured to supply a reformed gas whose concentration is increased and whose carbon monoxide concentration is reduced.

As a specific example of the fuel processor P1, a fuel processor P12 shown in FIG. 2 will be described.
The fuel processor P12 includes a desulfurization device 2, a reformer 3, a shift reactor 4, a PROX reactor 5, and an operation control unit 20 that controls the operation of each reactor.

  The desulfurization apparatus 2 is an apparatus for desulfurizing a hydrocarbon raw material to be supplied to the reformer 3 in order to remove sulfur components that hinder the function of the reforming catalyst in the reformer 3. The desulfurization apparatus 2 is not particularly limited, and is appropriately selected according to the properties of the hydrocarbon raw material, the sulfur content, the desulfurization load, the processing amount, and the like. As the desulfurization catalyst, for example, nickel-molybdenum and chromium-molybdenum desulfurization catalysts are used.

  The hydrocarbon raw material supplied to the reformer 3 after being desulfurized by the desulfurizer 2 is not particularly limited as long as hydrogen can be produced by the reforming reaction in the reformer 3. Examples include kerosene, light oil, heavy oil, asphaltene, oil sand oil, methanol, naphtha, coal liquefied oil, coal heavy oil, liquid hydrocarbon mixtures such as gasoline, gaseous hydrocarbon mixtures such as city gas and LPG, etc. Can be used. The liquid hydrocarbon raw material may be heated and vaporized before being supplied to the desulfurization apparatus 2 and supplied to the desulfurization apparatus. Among these, kerosene has a very high energy density as a hydrogen source, and is highly portable and storable. Therefore, kerosene is suitable as a hydrocarbon raw material for a small stationary fuel cell system for home use. If the hydrocarbon raw material used is low in sulfur content and can be supplied to the reforming reaction in the reformer 3, the desulfurization device 2 is omitted and the reformer 3 is directly in the form of gaseous carbonization. Hydrogen raw material and water can be supplied.

For example, the reformer 3 reacts with hydrogen in the presence of a reforming reaction catalyst by a reaction between a hydrocarbon component contained in the hydrocarbon raw material and steam at a reforming treatment temperature in the range of 550 to 750 ° C., for example. It is an apparatus for generating a gas containing carbon oxide (hereinafter referred to as “reformed gas”). The reformer 3 includes a hydrocarbon raw material supply channel 21a for supplying a hydrocarbon raw material to a reformer body in which a reaction between a hydrocarbon component and water vapor is performed, and a water supply channel for supplying water vapor. 21b. A raw material supply valve 22 is disposed in the hydrocarbon raw material supply passage 21a, and supply or stop of the hydrocarbon raw material supplied to the reformer 3 or adjustment of the supply amount is performed.
Examples of the reforming reaction catalyst used include noble metal catalysts such as platinum (Pt), palladium (Pd), and ruthenium (Ru), and these catalysts are supported on a porous porous body made of ceramic. The vessel 3 is filled with the porous granular material to form a reforming catalyst layer.

  The reformer 3 is provided with a burner 7 for supplying heat for the occurrence of a reaction between hydrocarbon and steam, which is an endothermic reaction. The burner 7 is supplied with off-gas containing unreacted hydrogen discharged from the anode electrode of the fuel cell stack 6 and hydrocarbon raw material as fuel, and with air for burning these fuels. The The reaction temperature in the reformer 3 is determined by the reforming temperature sensor 23 provided at the reformed gas outlet 3a of the reformer 3 at the temperature of the reforming catalyst layer (reformed gas outlet) near the reformed gas outlet 3a. The temperature of the reformed gas in 3a) is detected, and based on the detected temperature, the supply amount of the hydrocarbon raw material used as fuel and the supply amount of air are controlled. The reformed gas generated in the reformer 3 is supplied to the shift reactor 4 through the reformed gas channel 21c.

The shift reactor 4 has a shift catalyst layer filled with a shift catalyst such as iron oxide, copper-zinc system, or copper-chromium system. In this shift reactor 4, in the presence of the shift catalyst, for example, at a temperature of 120 to 300 ° C., it is generated in the reformer 3 and included in the reformed gas introduced from the reformed gas inlet 4a. The carbon monoxide is transformed into carbon dioxide by the exothermic reaction of carbon monoxide and water vapor (CO + H ₂ O → CO ₂ + H ₂ ), thereby reducing the carbon monoxide concentration and reforming with a higher hydrogen concentration. It is an apparatus that generates gas (hereinafter referred to as “shift gas”). As a result, the hydrocarbon raw material supplied to the fuel cell system 1 and the hydrogen contained in the water vapor are effectively utilized as a power generation hydrogen resource supplied to the anode of the fuel cell stack 6. The shift gas is supplied from the shift gas outlet 4b provided in the shift reactor 4 to the PROX reactor 5 through the shift gas channel 21d.

  The shift reactor 4 is provided with a shift inlet temperature sensor 24a in the vicinity of the reformed gas inlet 4a, and the temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet 4a (the temperature of the reformed gas at the reformed gas inlet 4a). Is detected. A shift outlet temperature sensor 24b is provided in the vicinity of the shift gas outlet 4b of the shift reactor 4, and the temperature of the shift reaction catalyst layer in the vicinity of the shift gas outlet (the temperature of the shift gas at the shift outlet 4b) is detected.

  The PROX reactor 5 oxidizes carbon monoxide present in a minute amount in the shift gas supplied from the shift reactor 4 in the presence of the PROX catalyst in order to avoid the problem of electrode poisoning of the fuel cell stack 6. Thus, the reformed gas (hereinafter referred to as “hydrogen-containing gas”) in which the carbon monoxide concentration of the shift gas is further reduced is supplied to the fuel cell stack 6. Usually, in this PROX reactor 5, the carbon monoxide concentration in the shift gas is reduced to 10 ppm or less. The reaction in the PROX reactor 5 is performed at a temperature in the range of 80 to 250 ° C. in the presence of a noble metal-based PROX catalyst such as platinum, ruthenium, or rhodium. The hydrogen-containing gas generated in the PROX reactor 5 is supplied from the hydrogen-containing gas outlet 5a to the fuel cell stack 6 (see FIG. 1) through the hydrogen-containing gas passage 21e.

  The PROX reactor 5 is provided with a PROX temperature sensor 25 in the vicinity of the hydrogen-containing gas outlet 5a, and detects the temperature of the PROX catalyst layer in the vicinity of the hydrogen-containing gas outlet 5a (the temperature of the hydrogen-containing gas at the hydrogen-containing gas outlet 5a). Is done.

  The fuel cell stack 6 introduces hydrogen-containing gas supplied from the PROX reactor 5 into the anode, introduces air humidified by a humidifier (not shown) into the cathode, and performs electrochemical reaction between hydrogen and oxygen. Electricity is generated by reaction. This fuel cell stack 6 has an electrolyte membrane such as a solid polymer electrolyte membrane sandwiched between an anode containing a catalyst and a cathode, hydrogen in a hydrogen-containing gas supplied to the anode, and in the air supplied to the cathode Electricity is generated by a reaction that produces water by reaction with oxygen.

  In addition, since the electrochemical reaction between hydrogen and oxygen in the fuel cell stack 6 is usually performed at a reaction efficiency of about 80% from the viewpoint of power generation efficiency, the off-gas discharged from the anode of the fuel cell stack 6 is not yet present. Reaction hydrogen is included. Therefore, by supplying off gas to the burner 7, it is possible to effectively use the contained hydrogen as a fuel and improve the thermal efficiency of the entire fuel cell system.

  The operation control unit 20 includes a reforming temperature detecting means 26, a shift temperature detecting means 27, a PROX (carbon monoxide selective oxidation) temperature detecting means 28, a reforming reaction calculating means 29, a shift reaction calculating means 30, PROX (carbon monoxide selective oxidation) reaction calculation means 31 and reaction control means 32 are provided.

  The reforming temperature detection means 26 receives the temperature of the reforming catalyst layer in the vicinity of the reforming gas outlet 3a (at the reforming gas outlet 3a) from the reforming temperature sensor 23 provided at the reforming gas outlet 3a of the reformer 3. The temperature of the reforming catalyst layer is detected by receiving a signal relating to the temperature of the reforming gas. Information regarding the detected temperature of the reforming catalyst layer is transmitted to the reforming reaction calculating means 29.

  The shift temperature detecting means 27 receives the temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet 4a (reforming at the reformed gas inlet 4a) from the shift inlet temperature sensor 24a provided at the reformed gas inlet 4a of the shift reactor 4. The temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet 4a is detected. Furthermore, the shift temperature detection means 27 relates to the temperature of the shift reaction catalyst layer in the vicinity of the shift gas outlet 4b (the temperature of the shift gas at the shift gas outlet 4b) from the shift outlet temperature sensor 24b provided in the vicinity of the shift gas outlet 4b of the shift reactor 4. A signal is received, and the temperature of the shift reaction catalyst layer in the vicinity of the shift gas outlet 4b is detected. The detected information regarding the temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet 4 a and the temperature of the shift reaction catalyst layer in the vicinity of the shift gas outlet 4 b are transmitted to the shift reaction calculating means 30.

  The PROX temperature detection means 28 detects the temperature of the PROX catalyst layer in the vicinity of the hydrogen-containing gas outlet 5a (the hydrogen-containing gas at the hydrogen-containing gas outlet 5a) from the PROX temperature sensor 25 provided in the vicinity of the hydrogen-containing gas outlet 5a of the PROX reactor 5. The temperature of the PROX catalyst layer in the vicinity of the hydrogen-containing gas outlet 5a is detected. Information about the detected temperature of the PROX catalyst layer in the vicinity of the hydrogen-containing gas outlet 5 a is transmitted to the PROX reaction calculation unit 31.

  The reforming reaction calculation means 29 is carbonized according to the temperature of the reforming catalyst layer in the vicinity of the reformed gas outlet 3a detected by the reforming temperature detecting means 26 (the temperature of the reformed gas at the reformed gas outlet 3a). A processable amount A of the hydrogen raw material is obtained.

In the reforming reaction calculation unit 29, the processable amount A of the hydrocarbon raw material in the reformer 3 is obtained as follows.
Generally, in a reformer, when a reforming reaction is performed by supplying a mixed gas of a hydrocarbon raw material and water to a reforming catalyst layer at the same space velocity (SV), the reaction temperature (the temperature of the reforming catalyst layer) is The higher the amount, the more hydrogen is produced. However, even when the temperature of the reforming catalyst layer is low and the amount of hydrogen obtained is small, if the reforming reaction is completed, the reformed gas is supplied to the next shift reactor 4 to perform the shift reaction. However, it is considered that the shift catalyst layer is not adversely affected.

Therefore, a control diagram in the reformer 3 is created in the following steps (A) and (B).
(A) By a catalytic reaction test using a microreactor, as shown in FIG. 3 (A), as shown in FIG. 3 (A), the treatable amount of the reforming catalyst used (the supply ratio of hydrocarbon raw material (the supply amount of hydrocarbon raw material / hydrocarbon during rated operation) The relationship between the required supply amount of the raw material) and the reforming catalyst temperature is obtained, which is a non-linear relationship shown in FIG.
In FIG. 3A, the “reformation completion region” indicates a region where the gas composition and gas flow rate are the reaction equilibrium calculated values at the temperature = actual measurement value, and the “reformation incomplete region” indicates the gas composition and gas flow rate. Indicates a region where reaction equilibrium calculated value ≠ actual measurement value, that is, a region where raw gas is considered to be included in the reformed gas.

(B) Next, for the following reasons (1) to (4), as shown in FIG. 3B, the temperature of the reforming catalyst layer at the reforming gas outlet of the reformer (the reforming catalyst layer outlet temperature). ), The controllable diagram of the processable amount A of the reformer 3 and the operation of the reformer 3 is created.
(1) Since it is not necessary to supply a hydrocarbon raw material that exceeds the rating, the supply ratio of the hydrocarbon raw material that is 1.0 or higher (the supply amount of hydrocarbon raw material / the required supply amount of hydrocarbon raw material during rated operation) The operation of the mass device 3 is not performed.
(2) In the test result by the above microreactor, the control is given with a cutting edge multiplied by a safety factor considering the pulsation of the mixed gas of hydrocarbon raw material and water supplied to the reformer 3 and catalyst deterioration. For the sake of simplicity, this slope is assumed to be a linear form of linear expression. From this primary equation, the supply amount of the hydrocarbon raw material with respect to the temperature of the reforming catalyst layer, that is, the treatable amount A can be obtained.

This linear expression can be obtained as follows.
First, as shown in FIG. 4, from the test result by the microreactor, Y: the treatable amount in the reforming catalyst to be used (the supply ratio of the hydrocarbon raw material (the supply amount of the hydrocarbon raw material / the required supply amount of the hydrocarbon raw material during rated operation) )) And X: a tangent is obtained for a curve (experimental line) showing a non-linear relationship between the reforming catalyst temperature. Then, a linear expression representing this tangent: Y = aX + b (a> 0, b <0) is obtained. This tangent is the lower limit temperature of the catalyst activation temperature of the reforming catalyst, for example, the middle of the section between the intersection X1 with the line X = T and the intersection Y2 with the line Y = 1.0 in the experimental line. It can be obtained as a tangent at the point.
Next, an upper limit line: Y = aX + b · z1 is obtained in consideration of a safety factor z1 in consideration of pulsation of a mixed gas of hydrocarbon raw material and water supplied to the reformer 3, catalyst deterioration, and the like. Further, Z2 of the lower limit line: Y = aX + b · z2 is determined so that the lower limit temperature of the catalyst activation temperature, for example, Y at T is 0 or more (Z1 <Z2, Z1, Z2> 0).
The upper limit line: Y = aX + b · z1, the lower limit line: Y = aX + b · z2, the region surrounded by the line X = T, and the line Y = 1.0 (in FIG. 4, hatched lines are attached) The linear equation Y = cX + d representing a straight line passing between point 2 and point 3 when X = T and passing between point 1 and point 4 when Y = 1.0. It is assumed that
The processable amount A can be determined based on the linear expression thus determined.

  Here, as an example, when an experimental line is obtained by an experiment using a microreactor and a tangential line is actually obtained, Y = 0.016X-8.3 is obtained, and the lower limit temperature of the catalyst activation temperature of the reforming catalyst is, for example, When T = 550 ° C., it has been found that it is effective to set the safety factors Z1 and Z2 to about 1 to 1.2, respectively.

(3) In order to protect (durability) the reforming catalyst and the reactor, the reformer 3 is not operated at 750 ° C. or higher.
(4) To avoid the reaction at a low temperature for protecting the reforming catalyst, the reformer 3 is not operated at 550 ° C. or lower.

  The shift reaction calculation means 30 detects the temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet 4a (the temperature of the reformed gas at the reformed gas inlet 4a) detected by the shift temperature detecting means 27 and in the vicinity of the shift gas outlet 4b. The processable amount B of the hydrocarbon raw material is determined according to the temperature of the shift reaction catalyst layer (the temperature of the shift gas at the shift gas outlet 4b).

In this shift reaction calculation means 30, the processable amount B of the reformed gas is obtained as follows.
Generally, in the shift reaction in the shift reactor 4, the higher the reaction temperature (the temperature of the shift catalyst), the higher the reaction rate can be. As a result, the required amount of catalyst relative to the processing amount can be reduced, but produced. The carbon monoxide concentration in the shift gas increases. For this reason, it is necessary for the reaction in the shift reactor 4 to be completed (the reaction reaches equilibrium) in order to shift to the carbon monoxide selective oxidation reaction in the PROX reactor 5 in the next stage. When introduced into the next-stage PROX reactor 5, the carbon monoxide concentration is high, so that the necessary processing amount in the PROX reactor 5 increases. Therefore, it is necessary to set the maximum temperature of the shift catalyst layer at the shift gas outlet of the shift reactor 4 and to control the temperature below that in consideration of the balance with the processable amount C in the PROX reactor 5. . Furthermore, the shift reaction is characterized by the fact that the reaction temperature of the shift reaction (the temperature of the shift catalyst) is lower than the temperature of the reforming catalyst, so that the reaction is slower than the reforming reaction. It is necessary to control the temperature of the catalyst layer.

Therefore, a control diagram of the shift reactor 4 is created in the following steps (A) and (B).
(A) By a catalytic reaction test using a microreactor, as shown in FIG. 5 (A), as shown in FIG. 5 (A), the processable amount in the shift catalyst used (the supply ratio of hydrocarbon raw material (the supply amount of hydrocarbon raw material / the hydrocarbon raw material during rated operation) Required relationship) and the shift catalyst temperature, which is a non-linear relationship as shown in FIG.
In FIG. 5A, “shift complete region” indicates a region where the gas composition and gas flow rate are the reaction equilibrium calculated values at the temperature = actually measured value, and “shift incomplete region” indicates the gas composition and gas flow rate reacting. This is a region where the equilibrium calculation value is not equal to the actual measurement value, that is, a region where the raw material gas is included in the reformed gas and the decrease in the carbon monoxide concentration is considered insufficient.

(B) Next, for the following reasons (1) to (4), as shown in FIG. 5B, the temperature of the shift catalyst layer at the reformed gas inlet of the shift reactor 4 (shift catalyst layer inlet temperature) Accordingly, a control diagram of the shift amount 4 of the shift reactor 4 and the operation of the shift reactor 4 is created.
(1) Since it is not necessary to supply a hydrocarbon raw material exceeding the rating, a shift in the supply ratio of the hydrocarbon raw material of 1.0 or more (the supply amount of the hydrocarbon raw material / the required supply amount of the hydrocarbon raw material during the rated operation) The reactor 4 is not operated.
(2) In the test result by the microreactor, the control is simplified after giving a safety margin considering the pulsation of the mixed gas of hydrocarbon raw material and water supplied to the shift reactor 4 and catalyst deterioration. Therefore, this slope is set to a linear form of linear expression. From this linear equation, the supply amount of the hydrocarbon raw material with respect to the temperature of the shift catalyst layer, that is, the treatable amount B1 can be obtained.

About the method of calculating | requiring this primary formula, it can carry out similarly to the determination method of the primary formula in the said reforming catalyst.
As an example, when an experimental line is obtained by an experiment using a microreactor and a tangential line is actually obtained, Y = 0.016X-1.9 is obtained, and the lower limit temperature of the catalytic activity temperature of the shift catalyst is, for example, T = It was found that it was effective to set the safety factors Z1 and Z2 to about 1 to 1.6 at 150 ° C., respectively.

(3) For the protection (durability) of the shift catalyst, the shift reactor 4 is not operated at 280 ° C. or higher.
(4) Since reaction may not occur in a reaction system that is too cold, the shift reactor 4 is not operated at 180 ° C. or lower.

  (C) Next, the processable amount B2 of the shift reactor 4 and the conditions for controlling the operation of the shift reactor 4 according to the temperature of the shift catalyst layer at the shift gas outlet of the shift reactor 4 will be examined. At this time, when the equilibrium temperature of the shift catalyst and the carbon monoxide (CO) concentration in the shift gas of the shift reactor 4 are obtained from the equilibrium calculation values, they are as shown in FIG. This relationship is a non-linear relationship as shown in FIG. At this time, SR (water / hydrocarbon raw material: S / C) = 3, 700 ° C., reaction equilibrium gas under normal pressure is assumed as the mixed raw material gas.

(D) For the following reasons (1) to (4), as shown in FIG. 7, the processable amount of the shift reactor 4 (hydrocarbon feedstock) according to the temperature of the shift catalyst layer at the shift gas outlet of the shift reactor 4 The control diagram of the operation of the shift reactor 4 indicated by B2 is prepared (supply rate of hydrocarbon raw material / required supply amount of hydrocarbon raw material during rated operation).

(1) Since it is not necessary to supply a hydrocarbon raw material exceeding the rating, a shift in the supply ratio of the hydrocarbon raw material of 1.0 or more (the supply amount of the hydrocarbon raw material / the required supply amount of the hydrocarbon raw material during the rated operation) The reactor 4 is not operated.
(2) In the actual shift reactor, the shift reaction is carried out by changing the feed ratio of hydrocarbon feedstock as a mixed feedstock gas (feed rate of hydrocarbon feed / necessary feed rate of hydrocarbon feed during rated operation). The relationship between the temperature of the shift catalyst layer at the reformed gas inlet (shift catalyst layer inlet temperature) and the temperature of the shift catalyst layer at the shift gas outlet (shift catalyst layer outlet temperature) was investigated. Then, the composition of the shift gas derived from the shift reactor (shift gas outlet) is examined to show an appropriate gas composition, that is, the shift catalyst layer inlet when the reaction in the shift catalyst layer is in a reaction equilibrium state. The relationship between the temperature and the shift catalyst layer outlet temperature, that is, the case where the temperature distribution of the shift catalyst layer in the shift reactor is appropriate was examined. As a result, as shown in FIG. 6B, when the shift catalyst layer outlet temperature is 180 ° C. and the shift catalyst layer outlet temperature is 110 ° C. (the supply ratio of the hydrocarbon raw material at this time is shown in FIG. ) To 0.4.) Further, when the shift catalyst layer inlet temperature is 210 ° C. and the shift catalyst layer outlet temperature is 135 ° C. (the supply ratio of the hydrocarbon raw material at this time is shown in FIG. ) To 1.0)), each of the shift gases derived from the shift reactor (shift gas outlet) showed an appropriate gas composition. Points when the shift catalyst layer outlet temperature is 110 ° C. when the shift catalyst layer inlet temperature is 180 ° C. (X = shift catalyst layer outlet temperature: 110 ° C., Y = hydrocarbon feed ratio: 0.4) When the shift catalyst layer inlet temperature is 210 ° C. and the shift catalyst layer outlet temperature is 135 ° C. (X = shift catalyst layer outlet temperature: 135 ° C., Y = hydrocarbon feed ratio: 1.0 ) Was created. The upper side of the straight line L is a region where the gas composition and the gas flow rate are the reaction equilibrium calculated values at the temperature = actual measurement value (shift complete region), and the lower side is the gas composition and the gas flow rate are the reaction equilibrium calculated values ≠ the actual measurement value. That is, a region where the raw material gas is contained in the reformed gas and the carbon monoxide concentration is considered not to be sufficiently lowered (shift incomplete region), and a straight line L represents a shift complete region and a shift incomplete region. Means the boundary. This straight line L has a point (X = shift catalyst layer outlet temperature: 110 ° C., Y = hydrocarbon feed ratio: 0.4) and a point (X = shift catalyst layer outlet temperature: 135 ° C., Y = hydrocarbon). Therefore, Y = 0.833X-39.9 is obtained. Then, an equation obtained by multiplying the intercept of this primary expression: Y = 0.833X-39.9 by a safety factor, for example, a safety factor Z = 0.25, and a formula obtained by multiplying the safety factor: Y = 0.833- Obtain 9.98. By this primary expression: Y = 0.833-9.98, the supply amount of the hydrocarbon raw material with respect to the temperature of the shift catalyst layer at the shift gas outlet (shift catalyst layer outlet temperature), that is, the processable amount B2 can be obtained.

(3) The shift reactor 4 is not operated at 200 ° C. or higher so that the carbon monoxide concentration in the shift gas supplied to the PROX reactor 5 does not exceed the upper limit. Here, the temperature of the shift catalyst layer at the shift gas outlet of the shift reactor determines the composition of the shift gas supplied from the shift reactor to the carbon monoxide selective oxidation reactor. It is effective to control the supply amount of the hydrocarbon raw material by determining the treatable amount B based on the temperature of the shift catalyst layer at the outlet (shift catalyst layer outlet temperature). This is because when high-temperature shift gas is introduced into the next-stage PROX reactor 5, the carbon monoxide concentration is high, so that the required amount of processing in the PROX reactor 5 increases, so that processing in the PROX reactor 5 is possible. This is because the temperature of the shift catalyst layer at the shift gas outlet of the shift reactor 4 needs to be set to the maximum temperature and controlled to be equal to or lower than the temperature in consideration of the balance with the amount C.
(4) In a reaction system that is too low in temperature, the shift reactor 4 is not operated at 140 ° C. or lower because there is a possibility that a shift gas having a high carbon monoxide concentration may be supplied to the PROX reactor 5 without completing the reaction. And

  The PROX reaction calculation means 31 detects the hydrocarbon raw material according to the temperature of the PROX catalyst layer in the vicinity of the hydrogen-containing gas outlet 5a (the temperature of the hydrogen-containing gas at the hydrogen-containing gas outlet 5a) detected by the PROX temperature detection means 28. A processable amount C is obtained.

In this PROX reaction calculation means 31, the processable amount C of the hydrocarbon raw material is obtained as follows.
First, a control diagram of operation in the PROX reactor 5 is created in the following steps (A) and (B).
(A) By a catalytic reaction test using a microreactor, as shown in FIG. 8A, the temperature of the PROX catalyst and the carbon monoxide (CO) concentration in the hydrogen-containing gas discharged from the microreactor as a result of the PROX reaction ( ppm). This relationship is a non-linear relationship as shown in FIG. The test results in this microreactor are based on certain assumed conditions (SV, SR of the mixed gas of hydrocarbon raw material and water, reaction conditions in the shift reactor 4, oxygen in the shift gas, and carbon monoxide in the actual apparatus of the PROX reactor 5. Therefore, it varies depending on these reaction conditions, the performance of the PROX catalyst used, and the like.

In FIG. 8A, the increase in the carbon monoxide concentration of 190 ° C. or lower is considered to be a result of the unreacted carbon monoxide remaining without being reacted under the assumed conditions.
In addition, the increase in the carbon monoxide concentration of 190 ° C. or higher resulted from a decrease in the total amount of gas in the hydrogen-containing gas as a result of the promotion of methanation and a decrease in the selective oxidation of carbon monoxide on the high temperature side. It is thought that.

Further, in order to avoid poisoning by the carbon monoxide of the fuel cell stack 6, the carbon monoxide content in the supplied hydrogen-containing gas is set to 10 ppm or less. Furthermore, taking into account the effects of variable factors of carbon monoxide content such as safety factor and pulsation, the quality of the hydrogen-containing gas at the outlet of the fuel processor P1 (PROX reactor 5) is 5 ppm or less. To do. While satisfying this condition, the temperature of the PROX catalyst layer (PROX catalyst layer temperature) at the hydrogen-containing gas outlet of the PROX reactor 5 as shown in FIG. 8 (B) by the following (1) to (3). Accordingly, the processable amount of the PROX reactor 5 (the supply ratio of the hydrocarbon raw material (the supply amount of the hydrocarbon raw material / the required supply amount of the hydrocarbon raw material at the rated operation)) C and the conditions for controlling the operation of the PROX reactor 5 To consider.
(1), (2) Based on the performance of the PROX catalyst, the PROX reactor 5 is not operated under high carbon monoxide concentration conditions (140 ° C. or lower, 230 ° C. or higher).
(3) PROX at a feed ratio of hydrocarbon feed of 1.0 or more (supply amount of hydrocarbon feed / necessary feed rate of hydrocarbon feed during rated operation) is not necessary because supply of hydrocarbon feed above the rating is not necessary The reactor 5 is not operated.

As described above, the reforming reaction calculation means 29, the shift reaction calculation means 30 and the PROX reaction calculation means 31 use the following control diagrams created for each, and can process the amounts A, B (B1, B1, B2) and C are obtained and transmitted to the reaction control means 32.
(1) Control diagram of reforming gas outlet temperature of reformer 3 and supply amount of hydrocarbon raw material (FIG. 3B)
(2) Control diagram of reformed gas inlet temperature of shift reactor 4 and supply amount of hydrocarbon raw material (FIG. 5B)
(3) Control diagram of shift gas outlet temperature of shift reactor 4 and supply amount of hydrocarbon raw material (FIG. 7)
(4) Control diagram of shift gas inlet temperature of PROX reactor 5 and supply amount of hydrocarbon raw material (FIG. 8B)

  The reaction control unit 32 calculates the processable amount A obtained by the reforming reaction calculation unit 29, the processable amount B obtained by the shift reaction calculation unit 30, and the processable amount C obtained by the PROX reaction calculation unit 31. The amount of hydrocarbon raw material supplied to the reformer 3 is controlled on the basis of the smaller processable amount transmitted from each calculation means. As a result, the operation of the fuel processor P1 is controlled as follows.

  First, after the operation of the fuel processor P1 is started, the reforming temperature detecting means 26 connected to the reforming temperature sensor 23, the shift inlet temperature sensor 24a, the shift outlet temperature sensor 24b, and the PROX temperature sensor 25, the shift temperature, respectively. The temperature of the reforming catalyst layer at the reformed gas outlet 3a of the reformer 3 and the reformed gas inlet of the shift reactor 4 are detected at regular intervals by the detecting means 27 and the PROX (carbon monoxide selective oxidation) temperature detecting means 28. The temperature of the shift catalyst layer at 4a and the shift gas outlet 4b and the temperature of the PROX catalyst layer at the hydrogen-containing gas outlet 5a of the PROX reactor 5 are detected. Reforming reaction calculating means 29, shift reaction calculating means 30, and the temperature of each catalyst layer transmitted from reforming temperature detecting means 26, shift temperature detecting means 27 and PROX (carbon monoxide selective oxidation) temperature detecting means 28, respectively. The PROX (carbon monoxide selective oxidation) reaction calculation means 31 is based on the control diagram, in particular, the processable amounts A, B (B1, B2), C is calculated, and the processable amounts A, B (B1, B2), and C obtained are transmitted to the reaction control means 32. The reaction control means 32 uses the smallest value of the processable amounts A, B (B1, B2), C as the supply amount of the hydrocarbon raw material as the entire fuel processor P1, and supplies it to the hydrocarbon raw material supply passage 21a. Operation control of the fuel processor P1 is performed by controlling the raw material supply valve 22 provided to supply or stop the hydrocarbon raw material supplied to the reformer 3, or to adjust the supply amount. Accordingly, when changing the supply amount of the hydrocarbon raw material, that is, the reforming load, according to the processable amount in the catalyst layer of each reactor constituting the fuel processor, it is supplied from the fuel processor to the fuel cell stack. The actual hydrogen production in the fuel processor is compared to the theoretical hydrogen production per unit amount of hydrocarbon feed that is supplied to the fuel processor (reformer) while maintaining the quality of the hydrogen-containing gas within the proper range. Since the amount can be increased, the efficiency as a fuel processor is improved, and the carbon monoxide concentration of the hydrogen-containing gas can be lowered, so that the adverse effect on the fuel cell stack can be reduced. Further, when the hydrocarbon raw material to be used is a heavy raw material that is liquid at normal temperature and normal pressure, there is little risk that unreacted heavy hydrocarbon is supplied to each catalyst or fuel cell stack. Further, since the processable amount is determined according to the temperature of the catalyst layer of each reactor, it is possible to realize an increase in the reforming load according to the performance of each reactor and to appropriately control the operation. In particular, in the inventions according to claims 2 and 4, the treatable amount is determined based on a linear relationship that approximates a nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst. It is possible to control with simple calculation.

By controlling the fuel processor P1 in this manner, in the rated load operation of the fuel cell system 1 according to the embodiment of the present invention shown in FIG. 1, the hydrocarbon raw material is desulfurized by the desulfurization device 2 and then modified. It is supplied to the mass device 3. In the reformer 3, in the presence of the reforming catalyst, for example, at a reforming treatment temperature in the range of 550 to 750 ° C., the reaction between the hydrocarbon content of the hydrocarbon raw material and water vapor (hydrocarbon + H ₂ O → 3H ₂ + CO) generates a gas containing hydrogen and carbon monoxide (hereinafter referred to as “reformed gas”). The reformed gas generated in the reformer 3 is supplied to the shift reactor 4 and carbon monoxide is converted into carbon dioxide by an exothermic reaction between carbon monoxide and water vapor (CO + H ₂ O → CO ₂ + H ₂ ). In addition to reducing the carbon monoxide concentration, a shift gas with an increased hydrogen concentration is generated. The shift gas generated in the shift reactor 4 is supplied to the PROX reactor 5 to oxidize a small amount of carbon monoxide present in the shift gas to generate a hydrogen-containing gas that further reduces the carbon monoxide concentration of the shift gas. The Then, the hydrogen-containing gas is introduced into the anode (not shown) of the fuel cell stack 6, and the air humidified by the humidifier (not shown) is introduced into the cathode (not shown). Electricity is generated by the electrochemical reaction of oxygen.

  In the above description, the temperature conditions of the reforming catalyst, the shift reaction catalyst, or the PROX catalyst have been described with specific numerical values. These numerical values are the performance of the reforming catalyst, the shift catalyst, and the PROX catalyst to be used. , Properties, the amount of catalyst charged in each reactor, the type and scale of the reactor, and the like, and are not particularly limited.

1 is a block diagram showing a schematic configuration of a fuel cell system according to an embodiment of the present invention. It is a block diagram which shows the structure of a fuel processor. (A) is the result of the reaction test of the reforming catalyst using a microreactor, and (B) is a control diagram of the operation of the reformer. It is a figure explaining the method of calculating | requiring a primary expression from a nonlinear relationship. (A) is a result of a shift catalyst reaction test using a microreactor, and (B) is a control diagram of operation of the shift reactor according to the temperature of the shift catalyst layer at the reformed gas inlet. (A) is a figure which shows the relationship between the equilibrium temperature of a shift catalyst, and the equilibrium calculation value of the carbon monoxide density | concentration in the shift gas of the shift reactor 4, (B) is the state in which the reaction in a shift catalyst layer is reaction equilibrium It is a figure which shows the relationship between the shift catalyst layer entrance temperature and shift catalyst layer exit temperature in this case. FIG. 3 is a control diagram of operation of the shift reactor according to the temperature of the shift catalyst layer at the shift gas outlet. (A) is a result of a reaction test of a PROX catalyst using a microreactor, and (B) is a control diagram of operation in the PROX reactor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell system 2 Desulfurizer 3 Reformer 4 Shift reactor 5 PROX (carbon monoxide selective oxidation) reactor 6 Fuel cell stack P1 Fuel processor 20 Operation control part 23 Reforming temperature sensor 24a Shift inlet temperature sensor 24b Shift outlet Temperature sensor 25 PROX temperature sensor 26 Reforming temperature detecting means 27 Shift temperature detecting means 28 PROX (carbon monoxide selective oxidation) temperature detecting means 29 Reforming reaction calculating means 30 Shift reaction calculating means 31 PROX (carbon monoxide selective oxidation) reaction Calculation means 32 Reaction control means

Claims (12)

A reformer having a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water, and a shift reaction between carbon monoxide and steam in the reformed gas to generate hydrogen And a shift reactor in which a shift reaction catalyst layer for producing a shift gas with an increased hydrogen concentration is provided, and a carbon monoxide existing in the shift gas is selectively oxidized to reduce the carbon monoxide concentration. A fuel processor operation control method comprising a carbon monoxide selective oxidation reactor in which a carbon monoxide selective oxidation catalyst layer to be reduced is provided,
A processable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer;
A processable amount B of the reformed gas at the temperature of the shift reaction catalyst layer;
And determining the supply amount of the hydrocarbon raw material to be supplied to the reformer based on the smaller one of the treatable amount A and the treatable amount B. Fuel processor operation control method.   The treatable amount A and the treatable amount B are linear equations that approximate a nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of the catalyst for each of the reforming catalyst and the shift reaction catalyst. 2. The fuel processor operation control method according to claim 1, wherein the fuel processor operation control method is determined based on a relationship.   Furthermore, the processable amount C of the shift gas at the temperature of the carbon monoxide selective oxidation catalyst is obtained, and the processable amount, whichever is smaller of the processable amount A and the processable amount B, and the processable amount 2. The operation control method for a fuel processor according to claim 1, wherein a supply amount of a hydrocarbon raw material to be supplied to the reformer is determined on the basis of the smallest processable amount of C. 3.   The treatable amount A, the treatable amount B, and the treatable amount C are the temperature of each catalyst and the treatability of the catalyst for each of the reforming catalyst, the shift reaction catalyst, and the carbon monoxide selective oxidation catalyst. 4. The operation control method for a fuel processor according to claim 3, wherein the operation control method is determined based on a linear relationship that approximates a non-linear relationship obtained in advance with respect to the quantity.   The fuel according to any one of claims 1 to 4, wherein the temperature of the reforming catalyst layer is a temperature of the reforming catalyst layer in the vicinity of a reformed gas outlet of the reformer. Processor operation control method.   6. The fuel processor according to claim 1, wherein a temperature of the shift reaction catalyst layer is a temperature of the shift reaction catalyst layer in the vicinity of a shift gas outlet of the shift reactor. 7. Operation control method.   The temperature of the carbon monoxide selective oxidation catalyst layer is a temperature of the carbon monoxide selective oxidation catalyst layer in the vicinity of a shift gas inlet of the carbon monoxide selective oxidation reactor, according to claim 3 to 6. The fuel processor operation control method according to any one of the preceding claims.   The processable amount B of the shift reaction catalyst is equal to the hydrocarbon processable amount B1 at the temperature of the shift reaction catalyst layer in the vicinity of the reformed gas inlet of the shift reactor, and the shift gas outlet in the vicinity of the shift gas outlet of the shift reactor. The fuel processor operation control method according to any one of claims 1 to 7, wherein the fuel processor operation control method is determined based on a processable amount B2 of the hydrocarbon raw material at a temperature of the shift reaction catalyst layer. A reformer having a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water, and a shift reaction between carbon monoxide and steam in the reformed gas to generate hydrogen And a shift reactor in which a shift reaction catalyst layer for producing a shift gas with an increased hydrogen concentration is provided, and a carbon monoxide existing in the shift gas is selectively oxidized to reduce the carbon monoxide concentration. A carbon monoxide selective oxidation reactor having a carbon monoxide selective oxidation catalyst layer to be reduced, and an operation control unit for controlling operations of the reformer, the shift reactor, and the carbon monoxide selective oxidation reactor; A fuel processor comprising:
The operation control unit is
A reforming temperature detecting means for detecting the temperature of the reforming catalyst layer;
Shift temperature detection means for detecting the temperature of the shift reaction catalyst layer;
A reforming reaction calculating means for obtaining a processable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer detected by the reforming temperature detecting means;
Shift reaction calculation means for obtaining a processable amount B of the reformed gas at the temperature of the shift reaction catalyst layer detected by the shift temperature detection means;
Reaction control means for controlling the supply amount of the hydrocarbon raw material to be supplied to the reformer, based on the smaller processable amount of the processable amount A and the processable amount B;
A fuel processor characterized by comprising:   The reforming reaction calculating means and the shift reaction calculating means approximate the nonlinear relationship obtained in advance with respect to the temperature of each catalyst and the treatable amount of each of the reforming catalyst and the shift reaction catalyst. The fuel processor according to claim 9, wherein the processable amount A and the processable amount B are obtained based on a linear relationship. A reformer having a reforming catalyst layer for producing a reformed gas by reforming a hydrocarbon raw material and water, and a shift reaction between carbon monoxide and steam in the reformed gas to generate hydrogen And a shift reactor in which a shift reaction catalyst layer for producing a shift gas with an increased hydrogen concentration is provided, and a carbon monoxide existing in the shift gas is selectively oxidized to reduce the carbon monoxide concentration. A carbon monoxide selective oxidation reactor having a carbon monoxide selective oxidation catalyst layer to be reduced, and an operation control unit for controlling operations of the reformer, the shift reactor, and the carbon monoxide selective oxidation reactor; A fuel processor comprising:
The operation control unit is
A reforming temperature detecting means for detecting the temperature of the reforming catalyst layer;
Shift temperature detection means for detecting the temperature of the shift reaction catalyst layer;
A carbon monoxide selective oxidation temperature detecting means for detecting the temperature of the carbon monoxide selective oxidation catalyst layer;
A reforming reaction calculating means for obtaining a processable amount A of the hydrocarbon raw material at the temperature of the reforming catalyst layer detected by the reforming temperature detecting means;
Shift reaction calculation means for obtaining a processable amount B of the reformed gas at the temperature of the shift reaction catalyst layer detected by the shift temperature detection means;
A carbon monoxide selective oxidation reaction calculating means for obtaining a processable amount C of the shift gas at the temperature of the carbon monoxide selective oxidation catalyst layer detected by the carbon monoxide selective oxidation temperature detecting means;
A reaction for controlling the supply amount of the hydrocarbon raw material to be supplied to the reformer based on the smaller one of the treatable amount A, the treatable amount B, and the treatable amount C. Control means;
A fuel processor characterized by comprising:   The reforming reaction calculating means, the shift reaction calculating means, and the carbon monoxide selective oxidation reaction calculating means are configured so that each of the reforming catalyst, the shift reaction catalyst, and the carbon monoxide selective oxidation catalyst has a temperature of each catalyst. The processable amount A, the processable amount B, and the processable amount C are obtained based on a relationship of a linear expression that approximates a nonlinear relationship that is determined in advance with respect to the processable amount of the catalyst. Item 12. The fuel processor according to Item 11.

Images