JP2005190917A - Controlling raw fuel control device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a raw fuel control device 40 and a raw fuel control method for a reformer capable of appropriately controlling a raw fuel flow rate control valve 5 even below 30% of the measuring upper limit or less than the measuring lower limit of a raw fuel flowmeter 6, and capable of appropriately continuing an operation of the reformer 1 even in a comparatively unstable range in measurment of the raw fuel flowmeter 6. <P>SOLUTION: On the basis of a raw fuel flow rate measurement value PV1 measured by the raw fuel flowmeter 6 and a raw fuel flow rate set value SV1, and a reformer temperature measurement value PV2 measured with a thermometer 9 provided in the reformer 1 and a reformer temperature set value SV2, the opening of the raw fuel flow rate control valve 5 is controlled to increase or decrease according to the temperature of the reformer 1 prior to the indicated value of the raw fuel flowmeter 6. According to the indicated value PV5 of a pressure gauge 42 disposed on the downstream side of the reformer 1, a function for controlling the opening of the raw fuel flow rate control valve 5 to increase or decrease can be added. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a raw fuel control apparatus and a raw fuel control method for controlling raw fuel supplied to a reformer that reforms raw fuel into a hydrogen-rich gas.

  In recent years, fuel cells have been developed. There are various types of fuel cells depending on the type of electrolyte to be used. Usually, air is used as an oxidizing gas, and gas containing hydrogen produced by steam reforming a hydrocarbon-based raw fuel such as natural gas is used. Used as fuel gas. For this reason, the fuel cell power generation apparatus provided with the fuel cell as described above is provided with a reformer that reforms the raw fuel and generates fuel gas. For example, the reforming reaction of methane (steam reforming reaction) in the reformer when methane is used as the fuel is an endothermic reaction, so the fuel off-gas from the fuel cell is supplied to the burner and burned in the furnace. By raising the temperature of the catalyst layer, a reformed gas rich in hydrogen (hydrogen-rich) is generated.

  FIG. 5 shows a fuel cell control device described in Patent Document 1. In FIG. 5, reference numeral 1 is a reformer (hydrogen generator), 1a is a reformer reaction tube of the reformer 1, 1b is a furnace body of the reformer 1, and 2 is attached to the reformer 1 for reforming. A burner for heating the reactor reaction tube 1a, 3 is a combustion air flow rate control valve for controlling the combustion air flow rate for burning the battery exhaust gas (off gas) in the burner 2, and 4 is a combustion air flow rate control valve 3 A combustion air flow meter for measuring the flow rate of combustion air to be controlled, 5 is a raw fuel flow rate control valve for controlling raw fuel, and 6 is a flow rate of raw fuel flowing into the reformer 1. A raw fuel flow meter, 7 is a valve for mixing raw fuel and steam and sending them to the reformer 1, 8A and 8B are raw material steam control valves and flow meters, and 9 is the temperature of the reformer reaction tube 1a. A thermometer for measuring the temperature of the reformer 1, 30 is for correcting a reference flow rate (described later) of the raw fuel flow rate. A corrected raw fuel flow rate calculating device 31 for calculating a correction amount, 31 is a raw fuel flow rate control valve drive for driving the raw fuel flow rate control valve 5 to correct the raw fuel flow rate from the reference flow rate and the correction amount of the raw fuel flow rate Device.

  FIG. 6 is a block diagram of the correction air flow rate calculation device 10A and the air regulating valve driving device 11A in FIG. As shown in FIG. 6, the corrected air flow rate calculation device 10 </ b> A includes a function unit (FX) 12 </ b> A that determines the set temperature of the reformer 1 from the power generation output of the fuel cell, and a set temperature determined by the function unit 12 </ b> A A subtractor 13A that subtracts the measured temperature of the mass device 1, that is, the output value of the thermometer 9, and a correction amount calculator 14A that calculates a correction amount (corrected air flow rate) for temperature control from the output of the subtractor 13A. Has been. As the correction amount calculator 14A, a proportional position / integral action (PID) controller is used. The air control valve driving device 11A includes a function unit (FX) 15A for setting an excess ratio of combustion air based on the power generation output of the fuel cell, a battery current and the flow rate of the raw fuel as the output of the raw fuel flow meter 6, and the function unit 15A. The reference flow rate calculator 16A that calculates the reference flow rate of the combustion air flow rate from the excess combustion air ratio that is the output, and the corrected air flow rate obtained by the corrected air flow rate calculation device 10A to the reference flow rate calculated by the reference flow rate calculator 16A An adder 17A that adds the flow rate to obtain the combustion air flow rate, and a measured value of the flow rate of combustion air that is the output of the combustion air flow meter 4 from the combustion air flow rate obtained by the adder 17A (combustion air flow rate) Subtractor 18A for subtracting the flow rate) to obtain the final combustion air flow rate, and drive signal calculator 19A for calculating the control valve drive signal in accordance with the final combustion air flow rate obtained by subtractor 18A. It is constructed from.

  The above-described conventional fuel cell control apparatus heats and reforms the inflowing raw fuel to obtain hydrogen fuel gas (offgas) used in the fuel cell or the like, and also converts offgas by the inflowing combustion air. In a control device having a reformer 1 that burns and heats the raw fuel, in order to heat the raw fuel while maintaining the measured temperature of the reformer 1 at a set temperature, the power generation output and reforming of the fuel cell Combustion air flow rate control means for controlling the combustion air flow rate based on the measured temperature of the reactor 1, and the flow rate of the raw fuel based on the power generation output of the fuel cell and the measured temperature of the reformer 1 And raw fuel control means. Therefore, there is an effect that the temperature of the reformer 1 can be maintained at the set temperature even when the composition change of the raw fuel or the change of the reforming reaction occurs.

JP-A-8-45521

  As described above, in the conventional fuel cell control apparatus, the temperature of the reformer 1 is maintained at the set temperature by controlling the flow rate of the raw fuel based on the measured temperature of the reformer 1 and the like. However, since the flow rate of the raw fuel is obtained from the indicated value of the raw fuel flow meter 6, if there is a difference between the indicated value of the raw fuel flow meter 6 and the true value of the flow rate of the raw fuel, the reforming is performed. There was a problem that it was difficult to maintain the temperature of the vessel 1 at the set temperature. In particular, when the raw fuel flow meter 6 is 30% or less of the measurement upper limit value or less than the measurement lower limit value, the opening degree of the raw fuel flow rate control valve 5 is in the forward closing direction or in the previous direction depending on the viewpoint, so Therefore, there is a problem that it is difficult to appropriately control the raw fuel flow rate control valve 5.

  For example, when the indicated value of the raw fuel flow meter 6 is smaller than the true value of the raw fuel flow rate, the raw fuel flow rate control valve 5 operates in the direction of increasing the opening, so that more raw fuel than necessary is introduced. Will be. On the other hand, in the temperature control of the reformer 1, an attempt is made to lower the temperature by reducing the raw fuel flow rate, but the indicated value of the raw fuel flow meter 6 is smaller than the true value of the raw fuel flow rate, in other words, the raw fuel. Since the true value of the flow rate is larger than the indicated value of the raw fuel flow meter 6, as a result, the temperature of the reformer 1 rises. Originally, the heat balance should be kept constant at the set raw fuel flow rate, that is, maintained at the set temperature. However, as described above, since the flow rate of the raw fuel actually flowing is larger than the set or planned raw fuel flow rate, there has been a problem that the operation of the fuel cell control device cannot be stably performed. .

  Contrary to the above, when the indicated value of the raw fuel flow meter 6 is larger than the true value of the raw fuel flow rate, the raw fuel flow rate control valve 5 operates in the direction of decreasing the opening degree. You will run out of fuel. On the other hand, the temperature control of the reformer 1 tries to increase the temperature by increasing the raw fuel flow rate, but the indicated value of the raw fuel flow meter 6 is larger than the true value of the raw fuel flow rate, in other words, the raw fuel. As a result, the amount of reformed gas supplied to the burner 2 decreases and the temperature of the reformer 1 falls. The phenomenon occurred. Originally, the heat balance should be kept constant at the set raw fuel flow rate, that is, maintained at the set temperature. However, as described above, since the flow rate of the raw fuel actually flowing is smaller than the set or planned raw fuel flow rate, there is a problem that the operation of the fuel cell control device cannot be stably performed. .

  Further, when the downstream pressure from which the hydrogen fuel gas exits the reformer 1 is lower than the control pressure, the temperature of the reformer 1 rises due to the increase in the off-gas flow rate, while the downstream pressure is controlled by the control pressure. If it is higher, there is a problem that the temperature of the reformer 1 decreases due to a decrease in the off-gas flow rate.

  Accordingly, an object of the present invention has been made to solve the above-mentioned problem, and even if the raw fuel flow rate control valve is appropriately set even if it is 30% or less of the measurement upper limit value of the raw fuel flow meter or less than the measurement lower limit value. To provide a raw fuel control device for a reformer that can be controlled and can continue operation of the reformer appropriately even in a relatively unstable region in raw fuel flow meter measurement is there.

  Another object of the present invention is to provide a reformer that can maintain the temperature of the reformer constant even when the downstream pressure at which the hydrogen fuel gas exits the reformer is different from the control pressure. To provide a fuel control device and the like.

  A raw fuel control apparatus according to the present invention is a raw fuel control apparatus that controls raw fuel supplied to a reformer that reforms raw fuel into a hydrogen-rich gas, and supplies the raw fuel to the reformer. And a raw fuel flow meter for measuring the flow rate of the supplied raw fuel and a raw fuel flow rate adjusting valve for adjusting the flow rate of the supplied raw fuel. When a thermometer for measuring temperature is provided and the raw fuel flow meter is used in a predetermined vicinity region of a measurement lower limit value, a measured value of the raw fuel flow meter and a predetermined set value of the raw fuel flow rate, Based on the measured value of the thermometer and the predetermined set value of the temperature of the reformer, the measured value of the raw fuel flow meter is prioritized over the indicated value of the raw fuel flow meter according to the measured value of the thermometer. Control is performed to increase or decrease the opening.

  Here, in the raw fuel control apparatus of the present invention, a pressure gauge for measuring the outlet pressure is further provided on the downstream side of the reformer, and the raw fuel flow rate control valve including the indicated value measured by the pressure gauge is opened. Control can be performed to increase or decrease the degree.

  Here, in the raw fuel control apparatus of the present invention, the predetermined vicinity region of the measurement lower limit value may be 30% or less of the measurement upper limit value of the raw fuel flow meter or less than the measurement lower limit value.

  The raw fuel control method of the present invention is a raw fuel control method for controlling raw fuel supplied to a reformer that reforms raw fuel into a hydrogen-rich gas, and supplies the raw fuel to the reformer. And a raw fuel flow meter for measuring the flow rate of the supplied raw fuel and a raw fuel flow rate adjusting valve for adjusting the flow rate of the supplied raw fuel. When a thermometer for measuring temperature is provided and the raw fuel flow meter is used in a predetermined vicinity region of a measurement lower limit value, a measured value of the raw fuel flow meter and a predetermined set value of the raw fuel flow rate, Based on the measured value of the thermometer and the predetermined set value of the temperature of the reformer, the measured value of the raw fuel flow meter is prioritized over the indicated value of the raw fuel flow meter according to the measured value of the thermometer. Control is performed to increase or decrease the opening.

  Here, in the raw fuel control method of the present invention, a pressure gauge for measuring the outlet pressure is further provided on the downstream side of the reformer, and the raw fuel flow rate control valve including the indicated value measured by the pressure gauge is opened. Control can be performed to increase or decrease the degree.

  Here, in the raw fuel control method of the present invention, the predetermined vicinity region of the measurement lower limit value may be 30% or less of the measurement upper limit value of the raw fuel flow meter or less than the measurement lower limit value.

  The raw fuel flow rate measurement value (PV1) and raw fuel flow rate setting value (SV1) measured by the raw fuel flow meter 6 and the reformer temperature measurement value (measured by the thermometer 9 provided in the reformer 1) PV2) and the reformer temperature set value (SV2), the opening degree of the raw fuel flow rate control valve 5 is increased or decreased according to the temperature of the reformer 1 in preference to the indicated value of the raw fuel flow meter 6. Can be controlled. For this reason, even if it is 30% or less of the measurement upper limit value or less than the measurement lower limit value of the raw fuel flow meter 6, the raw fuel flow rate control valve 5 can be appropriately controlled. There is an effect that it is possible to provide the reformer raw fuel control device 40 capable of appropriately continuing the operation of the reformer 1 even in an unstable region.

  Hereinafter, each embodiment will be described in detail with reference to the drawings.

  FIG. 1 shows a raw fuel control device 40 of a reformer 1 (hydrogen generator) in Embodiment 1 of the present invention. In FIG. 1, the same reference numerals as those in the conventional fuel cell control device shown in FIG. In FIG. 1, reference numeral 40 denotes a raw fuel control device that controls the raw fuel flow rate control valve 5 from the indicated value of the raw fuel flow meter 6 and the temperature measured by the thermometer 9 of the reformer 1, and 20 denotes a combustion-use device. An air blower for sending air 50 to the burner 2, 52 is a raw material mainly composed of hydrocarbons such as natural gas, LNG (Liquefied Natural Gas), LPG (Liquefied Petroleum Gas) or methanol. It is fuel. In the burner 2 provided in the reformer 1, the combustion gas 50 sent by the air blower 20 is used to burn off gas 51 that has not been used for power generation in a fuel cell (not shown) to raise the temperature of the catalyst layer. Thus, heat for the endothermic reaction can be applied from the outside of the reformer 1. In the reformer 1, the raw fuel 52 supplied from the raw fuel supply line 55 and the steam supplied from the steam supply line (not shown) are generated as hydrogen-rich reformed gas (hydrogen 53) by the steam reforming reaction. The combustion exhaust gas 54 is discharged.

  Next, the function of the raw fuel control device 40 will be described. The raw fuel control device 40 uses the raw fuel flow meter 6 according to the temperature of the reformer 1 measured by the thermometer 9 when using the raw fuel flow meter 6 at 30% or less of the measured value upper limit value or below the measured lower limit value. The control is performed to increase or decrease the opening degree of the raw fuel flow rate control valve 5 in preference to the total indicated value of 6. FIG. 2 shows a control block diagram of the raw fuel control device 40 according to the first embodiment of the present invention. In FIG. 2, the same reference numerals as those in FIG. In FIG. 2, reference numeral 21 denotes a deviation Δt between the reformer temperature measurement value PV2 measured by the thermometer 9 and the reformer temperature set value SV2 for keeping the catalyst temperature of the reformer 1 constant. A subtractor, 22 is a function calculator for obtaining the raw fuel flow rate correction value SV3 based on the output of the subtractor 21, and 25 is a raw fuel flow rate correction value SV3 to the raw fuel flow rate set value SV1 set when the reformer 1 is operated. 26 is a subtractor for obtaining a deviation ΔF between the raw fuel flow rate measurement value PV1 measured by the raw fuel flow meter 6 and the SV4 obtained by the adder 25, and 27 is obtained by the subtractor 26. An arithmetic unit (PID controller or the like) for obtaining an operation value MV1 that makes the deviation ΔF zero, 24 is a raw fuel measurement value PV1 of 30% or less of the upper limit value of the raw fuel flow meter 6 or a measurement lower limit value Determine that you are in the following area Determinator, 23 is a function calculator for obtaining the flow meter correction value MV2 based on the obtained difference △ t at the subtractor 21. When the determination unit 24 determines that the raw fuel measurement value PV1 has entered an area that is 30% or less of the upper limit value of the raw fuel flow meter 6 or less than the measurement lower limit value, the function calculator 23 uses the correction start command 29 to The obtained flow meter correction value MV2 is added by the adder 28 with the operation value MV1 obtained by the calculator 27, and an opening degree command to the raw fuel flow rate control valve 5 can be output.

  As described above, according to the first embodiment of the present invention, the raw fuel flow rate measurement value PV1 and the raw fuel flow rate setting value SV1 measured by the raw fuel flow meter 6 and the thermometer 9 provided in the reformer 1 are measured. Based on the reformer temperature measurement value PV2 and the reformer temperature setting value SV2, the priority value of the raw fuel flow meter 6 is given priority over the indicated value of the raw fuel flow meter 6 according to the temperature of the reformer 1. Control to increase or decrease the opening can be performed. For this reason, even if it is 30% or less of the measurement upper limit value or less than the measurement lower limit value of the raw fuel flow meter 6, the raw fuel flow rate control valve 5 can be appropriately controlled. It is possible to provide a raw fuel control device 40 and a raw fuel control method for a reformer that can appropriately continue operation of the reformer 1 even in an unstable region.

  FIG. 3 shows the raw fuel control device 41 of the reformer 1 (hydrogen generator) in Embodiment 2 of the present invention. In FIG. 3, the same reference numerals as those of the raw fuel control device 40 of the reformer 1 shown in FIG. The raw fuel control device 41 of the second embodiment is different from the raw fuel control device 40 of the first embodiment in that the function value of the raw fuel control device 40 is the indicated value of the pressure gauge 42 installed on the downstream side of the reformer 1. Accordingly, a function of performing control to increase or decrease the opening degree of the raw fuel flow rate control valve 5 is added.

  Next, functions of the raw fuel control device 41 will be described. The raw fuel control device 41 uses the temperature of the reformer 1 measured by the thermometer 9 and the pressure gauge 42 when the raw fuel flow meter 6 is used at 30% or less of the measured value upper limit value or less than the measured lower limit value. In accordance with the measured pressure on the downstream side of the reformer 1, control is performed to increase or decrease the opening of the raw fuel flow rate control valve 5 in preference to the indicated value of the raw fuel flow meter 6. FIG. 4 shows a control block diagram of the raw fuel control device 41 in Embodiment 2 of the present invention. In FIG. 4, the portions denoted by the same reference numerals as those in FIGS. In FIG. 4, reference numeral 43 denotes a subtractor for obtaining a deviation Δt between the reformer outlet pressure measured value PV5 measured by the pressure gauge 42 and the reformer outlet pressure reference value SV5, and 44 is obtained by the subtractor 43. A function calculator 45 for obtaining a function a1 for increasing or decreasing the opening degree of the raw fuel flow rate control valve 5 based on the deviation Δt, 45 is obtained by the function calculator 24 to the flow meter correction value MV2 obtained by the function calculator 23. It is a multiplier for multiplying the function a1 to obtain the pressure flow rate correction value MV4. When the determination unit 24 determines that the raw fuel measurement value PV1 is in an area that is 30% or less of the upper limit value of the raw fuel flow meter 6 or less than the lower limit measurement value, the multiplier 45 receives the correction start command 46. The obtained pressure flow rate correction value MV4 is added by the adder 28 with the operation value MV1 obtained by the calculator 27, and an opening degree command to the raw fuel flow rate control valve 5 can be output.

  As described above, according to the second embodiment of the present invention, the raw fuel flow rate is adjusted according to the indicated value of the pressure gauge 42 installed on the downstream side of the reformer 1 in the function of the raw fuel control device 40 of the first embodiment. A function of performing control to increase or decrease the opening degree of the valve 5 can be added. Therefore, the raw fuel control device 41 uses the temperature and pressure of the reformer 1 measured by the thermometer 9 when the raw fuel flow meter 6 is used at 30% or less of the measured value upper limit value or less than the measured lower limit value. In accordance with the pressure on the downstream side of the reformer 1 measured by the meter 42, the opening degree of the raw fuel flow rate control valve 5 is controlled to increase and decrease in preference to the indicated value of the raw fuel flow meter 6. it can. As a result, even if the downstream pressure at which the hydrogen fuel gas exits from the reformer 1 is different from the control pressure, the raw fuel control of the reformer 1 that can maintain the temperature of the reformer 1 constant. The apparatus 41 and the raw fuel control method can be provided.

  As an application example of the present invention, there is an application to a reformer that produces hydrogen from raw gas mainly composed of hydrocarbons such as natural gas, LNG, LPG, or methanol and steam.

It is a figure which shows the raw fuel control apparatus 40 of the reformer 1 (hydrogen generator) in Example 1 of this invention. It is a control block diagram of the raw fuel control apparatus 40 in Example 1 of this invention. It is a figure which shows the raw fuel control apparatus 41 of the reformer 1 (hydrogen generator) in Example 2 of this invention. It is a control block diagram of the raw fuel control apparatus 41 in Example 2 of this invention. 2 is a diagram illustrating a fuel cell control device described in Patent Literature 1. FIG. FIG. 6 is a block diagram of a corrected air flow rate calculation device 10A and an air control valve drive device 11A in FIG.

Explanation of symbols

1 reformer, 1a reformer reaction tube, 1b furnace body, 2 burner, 3 combustion air flow control valve, 4 combustion air flow meter, 5 raw fuel flow control valve, 6 raw fuel flow meter, 7 valve, 8A Raw material steam control valve, 8B Raw material steam flow meter, 9 Thermometer, 12A, 15A Function unit (FX), 13A, 18A, 21, 26, 43 Subtractor, 14A Correction amount calculator, 16A reference flow rate calculator , 17A, 25, 28 Adder, 19A Drive signal calculator, 20 Air blower, 22, 23, 44 Function calculator, 24 Determinator, 27 Calculator, 30 Corrected raw fuel flow rate calculation device, 31 Raw fuel flow rate control valve Drive device, 40, 41 Raw fuel control device, 42 Pressure gauge, 45 Multiplier, 29, 46 Correction start command, 50 Combustion air, 51 Off gas, 52 Raw fuel, 53 Hydrogen, 54 Combustion exhaust gas Su.

Claims (6)

A raw fuel control device that controls raw fuel supplied to a reformer that reforms raw fuel into a hydrogen-rich gas, the raw fuel supplied to a line that supplies the raw fuel to the reformer A raw fuel flow meter for measuring the flow rate of the raw fuel and a raw fuel flow rate control valve for adjusting the flow rate of the supplied raw fuel are provided, and the reformer is provided with a thermometer for measuring the temperature of the reformer. And
When the raw fuel flow meter is used in a predetermined vicinity region of the measurement lower limit value, the measured value of the raw fuel flow meter and the predetermined set value of the raw fuel flow rate, the measured value of the thermometer, and the reformer Based on a predetermined set value of temperature, control is performed to increase or decrease the opening of the raw fuel flow rate control valve in preference to the indicated value of the raw fuel flow meter according to the measured value of the thermometer. The raw fuel control device.   2. The raw fuel control apparatus according to claim 1, further comprising a pressure gauge for measuring an outlet pressure downstream of the reformer, and an opening degree of the raw fuel flow control valve including an indication value measured by the pressure gauge. A raw fuel control apparatus characterized by performing control to increase or decrease the fuel consumption.   3. The raw fuel control apparatus according to claim 1, wherein the predetermined vicinity region of the measurement lower limit value is 30% or less of the measurement upper limit value of the raw fuel flow meter or less than the measurement lower limit value. Control device. A raw fuel control method for controlling a raw fuel supplied to a reformer that reforms the raw fuel into a hydrogen-rich gas, the raw fuel supplied to a line for supplying the raw fuel to the reformer A raw fuel flow meter for measuring the flow rate of the raw fuel and a raw fuel flow rate control valve for adjusting the flow rate of the supplied raw fuel are provided, and the reformer is provided with a thermometer for measuring the temperature of the reformer. And
When the raw fuel flow meter is used in a predetermined vicinity region of the measurement lower limit value, the measured value of the raw fuel flow meter and the predetermined set value of the raw fuel flow rate, the measured value of the thermometer, and the reformer Based on a predetermined set value of temperature, control is performed to increase or decrease the opening of the raw fuel flow rate control valve in preference to the indicated value of the raw fuel flow meter according to the measured value of the thermometer. A raw fuel control method.   5. The raw fuel control method according to claim 4, further comprising a pressure gauge for measuring an outlet pressure downstream of the reformer, and including an indication value measured by the pressure gauge. A raw fuel control method characterized by performing control to increase or decrease the amount of fuel. 6. The raw fuel control method according to claim 4, wherein the predetermined vicinity region of the measurement lower limit value is 30% or less of the measurement upper limit value of the raw fuel flow meter or less than the measurement lower limit value. Control method.

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