JP2003212504A - Control of steam generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for generating steam having a stable steam quality and an excellent response to load changes. <P>SOLUTION: In a first steam generator, flow rates Y1 and Y2 of combustion fuel supplied to a vapor phase of a heat exchanger are feedback-controlled based on steam temperature Tm, while the flow rate Y3 of combustion fuel supplied to a liquid phase is feedback-controlled based on steam flow rate Fm. The two types of feedback controls are carried out independently from each other. A second steam generator is controlled based on the steam temperature Tm, calculated as a weighted average of a plurality of local steam temperatures measured at points near the outlets of a plurality of small channels wherein the steam flows. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for controlling a steam generator for heating a fluid to be heated and evaporating the fluid to generate a gaseous fluid to be heated.

[0002]

2. Description of the Related Art Steam generators are used in various plants and apparatuses, and steam generators are also used in fuel reformers for producing hydrogen to be supplied to fuel cells. The fuel reformer produces a hydrogen-rich fuel gas (also referred to as “reformed gas”) from a reforming raw material containing a hydrocarbon compound by a reforming reaction using a reforming catalyst. When a liquid reforming raw material such as gasoline or methanol is used, a steam generator (evaporating section) for vaporizing the reforming raw material is provided upstream of the reforming section containing the reforming catalyst. .

With respect to the steam generator, various control techniques have been devised. For example, JP-A-11-118116
The publication discloses a technique of detecting the temperature of a fluid to be heated and controlling the flow rate of the fluid to be heated in a steam generator using catalytic combustion. According to this technique, it is possible to generate steam earlier.

[0004]

However, in general, steam generation is accompanied by a phase change from a liquid phase to a vapor phase, and therefore it is not always easy to generate stable quality steam.
In addition, when the required steam generation amount fluctuates as in the evaporator used in the fuel reforming apparatus for vehicles, the responsiveness to the fluctuation of the required steam amount is also required. However, the conventional steam generator has a problem that stability of steam quality and responsiveness to load fluctuation are not always sufficient.

The present invention has been made in order to solve the above-mentioned conventional problems, and provides a technique capable of generating steam with excellent stability of steam quality and responsiveness to load fluctuation. With the goal.

[0006]

In order to achieve at least a part of the above object, the first steam generator according to the present invention heats and evaporates a fluid to be heated by a heating fluid to form a gas. A steam generator for generating a heated fluid in the form of a heat, comprising: a heat exchanger having a heating fluid flow path through which the heating fluid flows; and a heated fluid flow path through which the heated fluid flows, and the heating fluid. A flow rate adjusting unit for adjusting the flow rate of the heating fluid introduced into the flow path, and a control unit for controlling the flow rate adjusting unit are provided. The heat exchanger is a liquid phase part in which the fluid to be heated is mainly liquid,
And a vapor phase portion in which the fluid to be heated is mainly in a gaseous state. The flow rate adjusting unit includes at least one first flow rate adjusting element for introducing the heating fluid into the heating fluid channel of the vapor phase section, and the heating fluid in the heating fluid channel of the liquid phase section. And at least one second flow control element for introducing. The control unit includes a first flow rate of the heating fluid introduced into the gas phase section by the first flow rate adjusting element, and the heating fluid introduced into the liquid phase section by the second flow rate adjusting element. And the second flow rate of No. 2 are controlled based on different kinds of target values.

According to this first steam generator, the flow rate of the heating fluid introduced into the gas phase portion and the flow rate of the heating fluid introduced into the liquid phase portion are controlled based on different target values. Therefore, the heat exchange state desired for each of the gas phase portion and the liquid phase portion can be quickly realized. As a result, it is possible to generate steam with excellent steam quality and responsiveness to load changes.

It is preferable that the control section independently controls the first and second flow rate adjusting elements without directly depending on an operation amount of each other.

According to this structure, mutual control interference between the gas phase portion and the liquid phase portion can be prevented, so that the stability of the vapor quality and the responsiveness to load fluctuation can be further improved.

The controller controls the first flow rate adjusting element with the temperature of the gaseous heated fluid as a target value, and controls the second flow rate with the flow rate of the gaseous heated fluid as a target value. The element may be controlled.

Using such a target value, the vapor flow rate is controlled by adjusting the heating amount in the liquid phase portion, while the vapor temperature is controlled by the heating amount in the vapor phase portion. Therefore,
While preventing mutual interference in controlling steam temperature and steam flow,
It is possible to further improve the stability of steam quality and the responsiveness to load changes.

The heating fluid may contain combustion fuel, air, and combustion gas obtained by burning the combustion fuel as components. At this time, the first and second flow rate adjusting elements may be for adjusting the flow rate of the combustion fuel.

According to this structure, the steam temperature and the steam flow rate can be controlled by adjusting the flow rates of the combustion fuel to the gas phase section and the liquid phase section.

The flow rate adjusting section may further include a third flow rate adjusting element for supplying the air used for combustion of the combustion gas to the heating fluid passage. At this time, the control unit controls the flow rate of the air introduced into the heating fluid channel by the third flow rate adjusting element according to the total amount of the combustion fuel introduced into the heating fluid channel. May be.

According to this structure, it is possible to supply an appropriate amount of air to the heat exchanger according to the total amount of combustion fuel.

The heated fluid passage includes a plurality of vertical direct current passages arranged substantially vertically, and the heating fluid passage includes a plurality of horizontal passages arranged substantially horizontally. The exchanger may include an orthogonal heat exchange section including the vertical flow paths and the horizontal flow paths.

In such an orthogonal heat exchanger, since it is relatively easy to separate the gas phase portion and the liquid phase portion, it is possible to control the gas phase portion and the liquid phase portion with different target values. It's easy.

The plurality of horizontal flow passages are divided into a plurality of stages in which the flow direction of the heating fluid is different, and the horizontal flow passages of adjacent stages are connected to each other by a folded flow passage portion provided at an end. At least one stage of the plurality of stages that is relatively above may correspond to the gas phase portion. Further, at least one of the plurality of stages on the relatively lower side corresponds to the liquid phase portion, and the second flow rate adjusting element includes the stage of the liquid phase portion and the gas adjacent to each other. The flow rate of the heating fluid introduced into the folded flow path portion that connects between the step of the phase portion may be adjusted.

According to this structure, since the gas phase portion and the liquid phase portion are distinguished by the stages of the horizontal flow path, the amounts of the heating fluid supplied to the gas phase portion and the liquid phase portion are individually controlled. It is easy to do.

A second steam generator according to the present invention is a steam generator for heating and evaporating a fluid to be heated by a heating fluid to generate a gaseous fluid to be heated. A heat exchanger having a fluid flow path and a heated fluid flow path through which the heated fluid flows, a flow rate adjusting unit for adjusting the flow rate of the heating fluid introduced into the heating fluid flow path, A temperature measuring unit for measuring the temperature of the heating fluid, a control unit for controlling the flow rate adjusting unit,
Equipped with. The heated fluid channel is divided into a plurality of small channels inside the heat exchanger. The temperature measuring unit has a plurality of temperature sensors provided near the outlets of at least some of the small channels in the plurality of small channels. In addition, the control unit calculates an average temperature of the gaseous heated fluid discharged from the heat exchanger by performing unequal weighting on the plurality of temperatures measured by the plurality of temperature sensors, respectively, The flow rate adjusting unit is controlled based on the average temperature.

According to this second steam generator, the gas is obtained by weighting and averaging the plurality of temperatures measured by the plurality of temperature sensors provided in the vicinity of the outlets of the plurality of small channels of the fluid to be heated. Since the average temperature of the fluid to be heated (also referred to as "average vapor temperature") is obtained, it is possible to obtain the average vapor temperature relatively accurately with no time delay. Since the amount of heating fluid is controlled using this average steam temperature, it is possible to generate steam with excellent responsiveness to load changes.

The present invention can be realized in various modes. For example, a steam generator and a steam generating method, a fuel reformer using the same and a control method thereof,
Fuel cell system including fuel reforming device and fuel cell, control method thereof, mobile device including those devices or systems, and control method thereof, computer program for realizing functions of those methods or devices, and computer program thereof Can be realized in the form of a recording medium having recorded therein, a data signal including the computer program embodied in a carrier wave, and the like.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described in the following order based on examples. A. Structure of electric vehicle: B. First Example: C.I. Second embodiment: D. Modification:

A. Device Configuration of Embodiment: FIG. 1 is a schematic configuration diagram of an electric vehicle as one embodiment of the present invention. A wheel drive mechanism of this electric vehicle (hereinafter, simply referred to as “vehicle”) includes a motor 20, a torque converter 30, and a transmission 40. The rotating shaft 13 of the motor 20 is coupled to the torque converter 30. The output shaft 14 of the torque converter is coupled to the transmission 40. The output shaft 15 of the transmission 40 is connected to an axle 17 of a wheel 18 via a differential gear 16.

The motor 20 includes a rotor 22 and a stator 2
4 is a three-phase synchronous motor. A plurality of permanent magnets are provided on the outer peripheral surface of the rotor 22. Also,
A three-phase coil for forming a rotating magnetic field is wound around the stator 24. The motor 20 is rotationally driven by the interaction between the magnetic field generated by the permanent magnet provided in the rotor 22 and the magnetic field generated by the three-phase coil of the stator 24. Further, when the rotor 22 is rotated by an external force, an electromotive force is generated at both ends of the three-phase coil due to the interaction of these magnetic fields. In this case, the motor 20
Acts as a generator.

The motor 20 is equipped with two power sources, a fuel cell system 60 as a main power source and a battery (secondary battery) 50 as an auxiliary power source. The battery 50 supplies insufficient power to the motor 20 when the fuel cell system 60 fails, or when the fuel cell system 60 cannot output sufficient power such as when the vehicle is started. The power of the battery 50 is further supplied to a control unit 70 that controls the vehicle and power equipment (not shown) such as a lighting device.

Electric power from the two power sources 50 and 60 is supplied to the motor 20 via the respective drive circuits 51 and 52 and the changeover switch 80. The changeover switch 80 can arbitrarily switch the connection state among the battery 50, the fuel cell system 60, and the motor 20. The stator 24 is electrically connected to the battery 50 via the changeover switch 80 and the first drive circuit 51, and
It is connected to the fuel cell system 60 via the changeover switch 80 and the second drive circuit 52. Two drive circuits 5
Reference numerals 1 and 52 are each composed of a transistor inverter, and each of the three phases of the motor 20 is provided with a plurality of transistors with two sets on the source side and the sink side as one set. These drive circuits 51 and 52 are electrically connected to the control unit 70.

The control unit 70 includes a shift lever 72.
Then, various controls for the vehicle are executed based on the driver's commands given from the accelerator pedal 74 and the brake pedal 76. The control unit 70 has a drive circuit 51,
When the on / off time of each transistor of 52 is PWM-controlled, a pseudo three-phase alternating current using the battery 50 and the fuel cell system 60 as a power source flows in the three-phase coil of the stator 24 to form a rotating magnetic field. The motor 20 functions as an electric motor or a generator as described above by the action of the rotating magnetic field.

Various control operations of the control unit 70 are realized by the control unit 70 executing a computer program stored in a memory (not shown) built in the control unit 70. As this memory, various recording media such as a ROM and a hard disk can be used.

B. First Embodiment: FIG. 2 is an explanatory diagram showing the configuration of the fuel cell system 60 in the first embodiment.
The fuel cell system 60 includes an FC control unit 100, a fuel reformer 200, and a fuel cell 300.
The fuel reformer 200 includes an evaporator 210 and a reformer 220.
And a CO purification unit 230.

The evaporating section 210 is provided with a combustion gas passage 212 drawn as a meandering passage and a reforming raw material passage 214 intersecting with the combustion gas passage 212. The combustion gas passage 212 is
The horizontal flow paths 213a to 213c in a plurality of stages have a shape in which they are sequentially connected by substantially U-shaped return flow path parts 218a and 218b. The reforming raw material flow path 214 is divided into a large number of small vertical direct current paths 214a extending vertically from the lower part of the evaporation part 210 to the upper part thereof. Horizontal passage 21 for fuel gas
3a to 213c and the vertical flow path 214a of the reforming raw material,
It constitutes a so-called orthogonal heat exchanger.

FIG. 3 shows the horizontal flow paths 213a-2 of the combustion gas.
It is a perspective view which shows the orthogonal heat exchanger comprised by 13c and the vertical flow path 214a of a reforming raw material. Note that the folded flow path portions 218a and 218b (FIG. 1) are omitted in FIG. 3 for convenience. The combustion gas is introduced from the left end of the uppermost horizontal flow passage 213a and flows rightward in each horizontal flow passage 213a. The combustion gas reaching the right end portion of each horizontal flow passage 213a once merges in the return flow passage portion 218a (FIG. 1), and then flows again into the plurality of middle horizontal flow passages 213b. Similarly, at the left end of the horizontal flow passage 213b in the middle stage, the combustion gas once merges in the turn-back flow passage portion 218b (FIG. 1) and splits again into the plurality of horizontal flow passages 213c in the lowermost stage. Then, the combustion gas is discharged from the right end of the lowermost horizontal flow path 213c.

The reforming raw material is a plurality of vertical DC paths 2 in a liquid state.
14a is introduced from the lower side, becomes a gas state, and is discharged from the upper side of the vertical flow path 214a. In the example of FIG. 3, the liquid surfaces L1 to L3 of the reforming raw material exist near the boundary between the lowermost horizontal flow path 213c and the middle horizontal flow path 213b. In other words, the reforming raw material is liquid in the height range corresponding to the lowermost horizontal flow path 213c, and the reforming raw material is in the height range corresponding to the middle and uppermost horizontal flow paths 213b and 213a. Is a gas. Therefore, in the following description, as shown in FIG. 3, the horizontal flow paths 213b and
The heat exchanger portion in the height range corresponding to 13a is called a "gas phase portion", and the heat exchanger portion in the height range corresponding to the lowermost horizontal flow path 213c is called a "liquid phase portion".

However, as can be understood from FIG. 3, the height of the liquid surface is slightly different for each vertical flow path 214a. When the liquid level is at an intermediate position of the horizontal flow path of a certain stage, it can be defined as the liquid phase part or the gas phase part according to the height of the average liquid level in that stage. For example, the ratio of the average liquid level height range (liquid phase height) to the overall height of the step (ie liquid phase + gas phase height) is 1/2 or more. At that time, the stage is called a "liquid phase part".
On the other hand, when the value of the ratio of the height of the liquid phase in the stage to the total height of the stage is less than 1/2, the stage is called the "gas phase portion".

As the liquid reforming raw material, a mixture of methanol and water or a mixture of gasoline and water can be used.

As shown in FIG. 2, combustion air, combustion raw materials (for example, methanol and natural gas), and anode exhaust gas of the fuel cell 300 are supplied to the uppermost inlet portion of the combustion gas passage 212. ing. The flow rates of the combustion air and the combustion raw material are adjusted by the respective actuators 242 and 244. Further, the flow rate of the anode exhaust gas is adjusted by the flow rate adjusting valve 262 provided in the anode exhaust gas passage 260. The combustion raw material is further introduced into the folded flow path portions 218a and 218b by actuators 246 and 248, respectively. As these actuators, such as pumps and flow control valves,
Any mechanism capable of adjusting the flow rate (referred to as "flow rate adjusting element" or "flow rate adjusting mechanism") can be used.

The combustion raw material introduced into the inlet portion of the combustion gas flow passage 212 and the first turn-back flow passage portion 218a mainly boils the reforming raw material near the boiling point, and the gaseous reforming raw material (" It is used to superheat the raw material vapor "). On the other hand, the second folded flow path portion 218
The combustion raw material introduced into b is mainly used for raising the temperature of the liquid reforming raw material to almost the boiling point.

An electrically heated combustion catalyst section 216 (referred to as “EHC”) is provided near the inlet of the combustion gas flow path 212. The EHC 216 has a combustion catalyst for promoting the oxidation reaction of the hydrogen gas in the combustion raw material and the anode exhaust gas, and an electrically heated heater. Evaporator 210
At the time of startup, it is possible to start the combustion reaction of the combustion raw material and the anode exhaust gas early by raising the temperature of the EHC 216 by electric heating. The evaporation unit 2
The EHC 216 in 10 is referred to as "combustion EHC".

As described above, the combustion gas containing the combustion raw material and the anode exhaust gas is combusted, and the combustion gas passage 212 is formed.
The exhaust gas is discharged from the outlet of the lowermost flow passage 213c from the uppermost flow passage 213a to the lowermost flow passage 213c. On the other hand, the liquid reforming raw material is supplied from the lower inlet of the reforming raw material flow path 214, and is supplied to the vertical flow path 214a.
As it flows upward, it is heated by the combustion gas and evaporated. A temperature sensor 302 is provided near the inlet of the reforming raw material flow path 214. Further, in the vicinity of the outlet of the reforming raw material flow path 214, the temperature sensor 304 and the flow meter 30
And 6 are provided.

The reforming raw material vapor vaporized in the evaporation section 210 is introduced into the reforming section 220 together with the air for partial oxidation.
The reforming section 220 accommodates the reforming catalyst 222. The reforming catalyst 222 is supported on, for example, a honeycomb carrier. An electrically heated reforming catalyst unit (EHC) 224 is provided at the inlet and the center of the flow path of the reforming unit 220, respectively. These EHCs 224 have a reforming catalyst for promoting the reforming reaction of the reforming raw material vapor and an electrically heated heater. When starting the fuel reformer 200,
By raising the temperature of these EHC 224 by electric heating, it is possible to start the reforming reaction early.
A temperature sensor 226 is installed in the EHC 224 near the entrance. The central EHC 224 may be omitted. Below, the EHC 224 in the reforming section 220 is
It is called "reforming EHC".

Gas after reforming reaction (referred to as "reforming gas")
Usually contains carbon monoxide. CO purification unit 230
Has a function of reducing carbon monoxide in the reformed gas. As the reaction in the CO purification unit 230, a shift reaction or a selective oxidation reaction is used. For example, when a reforming raw material containing methanol and water is used, only the selective oxidation reaction is used in the CO purification unit 230. On the other hand, when the reforming raw material containing gasoline and water is used, both the shift reaction and the selective oxidation reaction are used in the CO purification unit 230. In the latter case, the CO purification section 230 is divided into a shift reaction section and a selective oxidation section.

Hydrogen-rich fuel gas containing less carbon monoxide is discharged from the CO purification unit 230. This fuel gas is supplied to the anode side of the fuel cell 300, and air is supplied to the cathode side. The flow rate of the fuel gas supplied to the fuel cell 300 is controlled by the flow rate adjusting valve 254. In addition to the pressure sensor 252, a temperature sensor, a flow rate sensor, and the like (not shown) are provided on the fuel gas flow path from the fuel reformer 200 to the fuel cell 300. F
The C control unit 100 controls the operating states of the fuel reformer 200 and the fuel cell 300 in response to signals from these various sensors and commands from the control unit 70 (FIG. 1) of the vehicle body.

FIG. 4 shows the evaporation section 210 in the first embodiment.
It is a control block diagram regarding control of. FC controller 10
0 has a gas phase control unit 110 and a liquid phase control unit 120. The vapor phase control unit 110 includes a vapor phase heat quantity calculation unit 112.
, Subtractor 116, PID control unit 114, and adder 1
18 and. The vapor phase control unit 110 controls the temperature of the reforming raw material vapor generated in the evaporation unit 210 (hereinafter, simply referred to as “vapor temperature”) as a target value, and the vapor phase unit of the evaporation unit 210 is controlled. The flow rates Y1 and Y2 of the combustion raw material supplied to are determined. The two flow rates Y1 and Y2 are the flow rates of the combustion fuel introduced by the actuators 244 and 246, respectively.

The gas phase heat quantity calculation unit 112 calculates the heat quantity Hg to be supplied to the gas phase section according to the required steam quantity, and the flow rate Y1 of the combustion fuel supplied to the gas phase section according to this heat quantity Hg.
It is a feedforward control element that determines a and Y2a. The amount of heat Hg to be supplied to the gas phase portion is calculated by the following equation (1), for example.

[0045]   Hg = kg / Ag / Fg / (Tg-Tb) / Cpg (1)

Here, kg is the heat transfer efficiency of the gas phase part, Ag
Is the heat transfer area of the vapor phase portion, Fg is the steam flow rate target value (requested steam flow rate), Tg is the steam temperature target value (requested steam temperature), Tb
Is the boiling point, and Cpg is the specific heat of steam. In addition, Fg, T
g, Tb, and Cpg are values related to the reforming raw material.

The vapor phase calorie calculation unit 112 calculates the required vapor flow rate Fg among these parameters and the required vapor temperature T.
g and have been entered. The total flow rate (Y1a + Y2a) of the combustion fuel to be introduced into the gas phase portion is calculated by dividing this heat quantity Hg by the unit calorific value of the combustion fuel.
The ratio of the flow rates Y1a and Y2a is determined according to a preset map. FIG. 5 shows the flow rate Y1 of the combustion fuel.
It is a graph which shows the map of a / Y2a. Flow rate ratio Y1a
/ Y2a may be a constant value as shown by the solid line, or may be set so as to change according to the total value of the flow rates as shown by the broken line. Alternatively, the flow rate ratio Y1a / Y2a may be changed according to the flow rate of the combustion air.

In this embodiment, the case where the anode exhaust gas is not used as the combustion gas will be described. When the anode exhaust gas is used, the above-mentioned two flow rates Y1
The relationship between a and Y2a and the flow rate of the anode exhaust gas is set in advance using a map.

The subtractor 116 and the PID control unit 114 execute PID control with the steam temperature as a target value. That is, the subtractor 116 is configured to measure the steam temperature target value Tg and the measured value Tg.
The deviation ΔT from m is obtained, and the PID control unit 114 performs PID compensation according to the deviation ΔT and outputs the flow rates Y1b and Y2b. The ratio of the flow rates Y1b and Y2b is set, for example, using the same map as in FIG. 5 described above.

The adder 118 is used in the vapor phase heat quantity calculation section 112.
The flow rate Y1a, Y2a calculated in
The flow rates Y1b and Y2b calculated in 4 are added,
The addition results Y1 and Y2 are output as control signals. The actuators 244 and 246 are controlled by these control signals Y.
A flow rate of combustion fuel corresponding to 1 and Y2 is introduced into the vapor phase part of the evaporation part 210.

The liquid phase control unit 120, like the gas phase control unit 110, also has a liquid phase heat quantity calculation unit 122, a subtractor 126,
It has a PID control unit 124 and an adder 128.
The liquid phase control unit 120 controls the flow rate of the reforming raw material vapor generated in the evaporation unit 210 (hereinafter, simply referred to as “vapor flow rate”) as a target value, and the liquid portion of the evaporation unit 210 burns. Flow rate Y3 of the actuator 248 for introducing the raw material
To decide.

The liquid phase heat quantity calculation unit 122 is a feedforward control element that calculates the heat quantity Hq to be supplied to the liquid phase section and determines the flow rate Y3a of the combustion fuel according to the heat quantity Hq. The amount of heat Hq to be applied to the liquid phase portion is calculated, for example, by the following equation (2).

[0053]   Hq = kq · Aq · Fg {(Tb−Tq) · Cpq + ΔH} (2)

Here, kq is the heat transfer efficiency of the liquid phase portion, Aq
Is the heat transfer area of the liquid phase part, Fg is the required vapor flow rate, Tb is the boiling point, Tq is the temperature of the liquid reforming raw material introduced into the evaporation part 210 (reforming raw material inlet temperature), and Cpq is the liquid reforming raw material. Specific heat, ΔH is the latent heat of vaporization. In addition, Fg, Tb, T
q, Cpq, and ΔH are values relating to the reforming raw material.

The required vapor flow rate Fg among these parameters and the reforming raw material inlet temperature Tq are input to the liquid phase portion calorie calculation unit 122. The flow rate Y3a of the combustion fuel to be supplied to the liquid phase portion is calculated by dividing this heat quantity Hq by the unit calorific value of the combustion fuel.

The subtracter 126 obtains the deviation ΔF between the target value Fg of the steam flow rate and the measured value Fm, and the PID controller 124 performs PID compensation according to this deviation ΔF and outputs the flow rate Y3b for the actuator 248. To do.

The adder 128 includes a liquid phase portion calorie calculation portion 122.
The flow rate Y3a calculated in step S3 and the flow rate Y3b calculated in the PID control unit 124 are added, and the addition result Y3 is output as a control signal. The actuator 248 introduces the combustion fuel having a flow rate according to the control signal Y3 into the liquid phase portion of the evaporation unit 210.

Although not shown, the FC controller 100 includes three actuators 244, 246 and 24.
8 determines the flow rate of the combustion air according to the total flow rate (Y1 + Y2 + Y3) of the combustion fuel supplied to the evaporation unit 210, and controls the operation of the air actuator 242.
Combustion air is used for combustion of combustion fuel in both the gas phase portion and the liquid phase portion. Therefore, the air amount depends on both the flow rate (Y1 + Y2) of the combustion fuel supplied to the gas phase section and the flow rate Y3 of the combustion fuel supplied to the liquid phase section.

As can be understood from the configuration of FIG. 4, the flow rate (Y1 + Y2) of the combustion fuel supplied to the gas phase section and the flow rate Y3 of the combustion fuel supplied to the liquid phase section are feedbacks performed independently of each other. Determined by control. Here, the phrase "two types of flow rates are determined by feedback control performed independently of each other" means that feedback control using different target values is performed, and one flow rate is the other flow rate. It does not directly depend on. In other words, in the gas phase control unit 110, the flow rate Y3 of the combustion fuel to the liquid phase unit is set.
Is not directly used, and the liquid phase control unit 120
In, the flow rate (Y1 + Y2) of the combustion fuel to the gas phase portion is not directly used. However, for example, when the flow rate Y3 of the combustion fuel supplied to the liquid phase portion increases, the heating amount of the reforming raw material increases, and as a result, the flow rate (Y1 + Y2) of the combustion fuel supplied to the gas phase portion decreases. There is a causal relationship of doing. However, also in this case, the flow rate Y of the combustion fuel supplied to the liquid phase portion in the gas phase control unit 110
3 is not used, and these are determined by feedback control performed independently of each other.

FIG. 6 shows the evaporation section 210 in the first embodiment.
3 is a flowchart showing the control procedure of FIG. Step S1
Then, the FC control unit 100 uses the control unit 70 (FIG. 1).
Target values Fg and Tg of steam flow rate and steam temperature transmitted from
To receive. In step S2, the FC control unit 100
Boundary between gas phase part and liquid phase part (liquid level heights L1 to L shown in FIG. 3)
Determine 3).

The liquid level heights L1 to L3 can be determined by the following various methods, for example. In the first method, the flow rate of the reforming raw material supplied to the evaporation unit 210,
The temperature distribution of the combustion gas in the evaporator 210 is measured, and the liquid level heights L1 to L3 are estimated based on these measured values. The second method utilizes the method disclosed in Japanese Patent Application Laid-Open No. 2001-272031 disclosed by the present applicant. In this method, the evaporation unit 210 is provided with a plurality of temperature sensors, and the liquid surface heights L1 to L3 are calculated based on the temperatures measured by these temperature sensors. In the third method, the liquid level heights L1 to L3 are estimated by using a so-called observer based on the steam flow rate and the steam temperature of the reforming raw material. In the fourth method, the liquid level gauges L1 to L are used by using a liquid level gauge.
Measure 3. In addition, various methods other than these may be adopted.

In step S3, the steam temperature Tm and the steam flow rate F are measured using the temperature sensor 304 and the flow meter 306 (FIG. 2).
m and are respectively measured. Instead of this, the steam temperature Tm and the steam flow rate Fm may be estimated by using an estimation means such as an observer. In step S4, it is determined whether the steam temperature Tm and the steam flow rate Fm satisfy the respective target values Tg and Fg. In the configuration of FIG. 4, in step S4, the deviations ΔT and ΔF are calculated by the subtracters 116 and 126.
Is equivalent to seeking.

In steps S5 to S7, the vapor phase controller 110
It is a steam temperature control routine performed by. In step S5, the vapor phase heat amount calculation unit 112 calculates the amount of heat Hg to be given to the vapor phase unit in order to achieve the required vapor amount. For this calculation, for example, the above-mentioned formula (1) is used. In step S6, the vapor phase heat quantity calculation unit 112 calculates the flow rates Y1a and Y2a of the combustion fuel according to the heat quantity Hg,
At the same time, the PID control unit 114 causes the steam temperature deviation ΔT
The flow rates Y1b and Y2b corresponding to the above are calculated. Further, the air amount corresponding to the total value of these flow rates (= Y1 + Y2) is also calculated. In step S7, the control signals Y1 and Y2 are supplied from the vapor phase control unit 110 to the actuators 244 and 246 (FIG. 2) to adjust the flow rate of the combustion fuel.

In steps S8 to S10, the liquid phase controller 12
It is a steam flow rate control routine performed by 0. In step S8, the liquid phase part heat amount calculation unit 122 calculates the heat amount Hq to be given to the liquid phase part in order to achieve the required vapor amount. For this calculation, for example, the above-mentioned formula (2) is used. In step S7, the liquid phase heat quantity calculation unit 122 calculates the flow rate Y3a of the combustion fuel according to the heat quantity Hq, and at the same time, the PID control unit 124 calculates the flow rate Y3b according to the steam flow rate deviation ΔF. Further, the air amount corresponding to this flow rate Y3b is also calculated. In step S10, the liquid phase controller 120 supplies the control signal Y3 to the actuator 248 to adjust the flow rate of the combustion fuel.

When the processes of steps S7 and S10 are completed, the process returns to step S3, and steps S3 to S1 described above are performed.
The process of 0 is repeatedly executed. The control unit 7
When the required steam amount given to the FC control unit 100 (that is, the target values Fg, Tg of the steam flow rate and the steam temperature) is changed from 0, the process is started again from step S1.

In the first embodiment described above, the flow rates Y1 and Y2 of the combustion fuel mainly used for heating the reforming raw material in the vapor phase part are based on the feedback control with the vapor temperature of the reforming raw material as the target value. The flow rate Y3 of the combustion fuel mainly used for heating the reforming raw material in the liquid phase portion is adjusted based on the feedback control with the vapor flow rate of the reforming raw material as a target value. In other words, the flow rates Y1, Y2 of the combustion fuel supplied to the gas phase portion,
The flow rate Y3 of the combustion fuel supplied to the liquid phase portion is controlled by an independent feedback control block. As a result,
It is possible to prevent the phenomenon in which the steam temperature and the steam flow rate interfere with each other, and it is possible to generate the reformed fuel steam at a stable flow rate and temperature. Further, particularly in a fuel reformer used in a vehicle, the required steam amount of reformed fuel also fluctuates considerably in accordance with load fluctuations. However, in the above-described embodiment, since the steam temperature and the steam flow rate are respectively controlled using the independent control blocks whose target values are the steam temperature and the steam flow rate, respectively, a high responsiveness is achieved even when the load changes. It is possible to

Although the vapor phase heat quantity calculation unit 112 and the liquid phase heat quantity calculation unit 122 can be omitted, it is said that the feedforward control using them enhances the responsiveness when the load changes. It is preferable in terms.

In the above-described first embodiment, the vapor phase controller 11
Although the steam temperature Tg is used as the control target value of 0 and the steam flow rate Fg is used as the control target value of the liquid phase control unit 120, instead of these values Tg and Fg, other values having a strong correlation with them are used. It is also possible to use. For example, instead of the vapor flow rate Fg, the average value of the liquid surface heights L1 to L3 can be used as the control target value. Generally, as the liquid level increases, the amount of heat transfer in the vapor phase portion decreases, so the steam flow rate increases, and conversely, when the liquid level decreases, the steam flow rate decreases. Therefore, it is possible to control the liquid phase portion by using the liquid level height as a control target value. Further, instead of the steam temperature, the steam pressure may be used as a control target value to control the gas phase portion. However, since it is desirable to control the steam temperature Tg and the steam flow rate Fg according to the load, it is preferable to use these as the control target value in terms of stability and responsiveness of the control.

C. Second Embodiment: FIG. 7 is an explanatory diagram showing the internal configuration of a fuel cell system 60a in the second embodiment. This fuel cell system 60a is different from the system 60 of the first embodiment shown in FIG. 2 only in the number and position of the temperature sensors provided in the evaporation part 210, and the others are the first.
Same as the embodiment.

In the evaporator 210a of the second embodiment, temperature sensors 304a to 304c for measuring the vapor temperature in each vertical flow path 214a are provided near the outlets of some vertical flow paths 214a through which the reformed fuel gas passes. Is provided. Hereinafter, these temperature sensors 304a to 304c are referred to as "local vapor temperature sensors". In the example of FIG. 7, the number of the local vapor temperature sensors 304a to 304c is three, but in general, any number of temperature sensors of two or more may be provided.

FIG. 8A shows a local vapor temperature sensor 304.
FIGS. 8A and 8B show an example of local vapor temperatures T1 to T3 measured by a to 304c, and FIG. 8B schematically shows the gas phase portion (FIG. 3) of the orthogonal heat exchanger. The temperature of the reforming raw material vapor flowing through each vertical flow path 214a depends on several parameters such as the temperature of the combustion gas and the heights of the liquid levels L1 to L3 (that is, the heat transfer area of the gas phase). It is usually different from each other. In the example of FIG. 8 (A), the local steam temperature is lowered as it is closer to the steam outlet of the evaporation unit 210a (closer to the reforming unit 220) among the plurality of vertical DC paths 214a. The reason for this is that the combustion gas flow path 2 at the top is
This is because in 13a, the temperature of the combustion gas is lower as it is closer to the vapor outlet of the evaporation section 210a.

The reforming raw material vapors that have exited from many vertical flow paths 214a are mixed and supplied to the reforming section 220. However, the temperature of the reforming raw material vapor is not always well equalized before reaching the reforming section 220. Also, since a considerable flow path length is required to make the temperature uniform, there is a possibility that a considerable time delay will occur from the generation of steam to the measurement of the steam temperature when trying to measure the steam temperature after making it uniform. There is.

Therefore, in the second embodiment, the evaporation section 210a
The temperature Tm of the reforming raw material steam generated in Step 1 is calculated according to the following equation (3) based on the local steam temperatures T1 to T3.

Tm = K · Σ (σi · Ti) (3)

Here, Σ () is an operator indicating the operation of adding the values in the parentheses, Ti is the local steam temperature measured by the i-th local steam temperature sensor, and σi is the i-th local steam temperature. , K is a coefficient.

Note that the weights σi are not all set to the same value, and at least one is set to a value different from other weights. In other words, the steam temperature Tm is a value obtained by averaging the local steam temperature Ti with non-uniform weights σi. The coefficient K is a value preset according to the weight σi.

Thus, by calculating the steam temperature Tm as a weighted average of the local steam temperature Ti, the temperature Tm of the reforming raw material steam generated in the evaporator 210a can be obtained with almost no time delay. . Further, by appropriately setting the weight σi and the coefficient K, it is possible to accurately measure the average steam temperature Tm.

As the method of setting the weight σi, the following several methods can be adopted. (1) The value of each predetermined weight σi is always used. (2) The steam flow rate of each vertical flow path 214a is measured or estimated, and the steam flow rate ratio is set as the weight σi. (3) The steam flow rate of each vertical flow path 214a is measured or estimated and set using a map showing the relationship between the steam flow rate and the weight σi.

As in the above method (2) or (3),
If the weight σi is set according to the steam flow rate of each vertical flow path 214a, a more accurate average steam temperature Tm can be obtained. As a method of obtaining the weighted average, it is possible to use the geometric average instead of the arithmetic average.

The same control as the control described in the first embodiment can be applied to the control of the evaporation unit 210a using the vapor temperature Tm. However, in the second embodiment, any method other than the method described in the first embodiment can be adopted.

As described above, in the second embodiment, the evaporation unit 21 is obtained by taking the weighted average of the local vapor temperature Ti.
The temperature Tm of the steam generated at 0a can be accurately obtained with a small time delay. Further, since the vaporizing section 210a is controlled using this vapor temperature Tm, it is possible to improve the control response of the vaporizing section 210a.

C. Modifications: The present invention is not limited to the above-described embodiments and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are also possible. is there.

C1. Modified Example 1: In each of the above embodiments, the combustion gas passage 212 in the evaporation part 210 was divided into three stages, but the combustion gas passage 212 does not need to be divided into a plurality of stages, and only one stage is possible. good. Further, the present invention is not limited to the orthogonal heat exchanger, and can be applied to an evaporation unit using another type of heat exchanger.

C2. Modified Example 2: In the above-described embodiment, heat for raising the temperature of the liquid reforming raw material to near the boiling point is supplied in the liquid phase portion, and the reforming raw material near the boiling point is vaporized and the steam is heated in the gas phase portion. It was supposed to be supplied with heat to do so. However, instead of this, heat may be supplied to the liquid phase portion to heat the liquid reforming raw material to near the boiling point and vaporize it, and to supply heat to heat the vapor in the gas phase portion. Good. Alternatively, the amount of heat required for vaporization may be separately supplied to the gas phase portion and the liquid phase portion.

C3. Modification 3: In the first embodiment, two actuators 24 are provided to supply combustion fuel to the gas phase portion.
4, 246 are provided, but instead of this, only one actuator may be provided to supply the combustion fuel to the gas phase portion. That is, in the configuration of the first embodiment, one or more actuators may be provided for supplying the combustion fuel to the gas phase portion and the liquid phase portion, respectively. In this case, at least one actuator for supplying the combustion fuel to the gas phase portion and at least one actuator for supplying the combustion fuel to the liquid phase portion are respectively controlled using mutually different control target values. You can do it like this.

C4. Modification 4: In the above embodiment, the combustion gas that burns in the evaporation unit 210 was supplied to the evaporation unit 210, but instead of this, a heating fluid that has been preheated outside is supplied to the evaporation unit 210. It may be one.

C5. Modification 5: In the above embodiment, the PID
Although control was used, other types of control methods could be used instead, such as control using state feedback.

C6. Modification 6: As the reforming fuel, various hydrocarbon fuels other than methanol and gasoline can be used. For example, alcohols other than methanol, and various hydrocarbon compounds such as aldehydes and ethers can be used.

C7. Variant 7: The present invention is not limited to the reforming raw material evaporation unit 210 in the fuel reformer, but is generally for heating a heated fluid with a heating fluid and evaporating it to generate a gaseous heated fluid. It is applicable to steam generators. However, in the evaporating portion for the fuel reforming device mounted on the vehicle, the load variation is large, and the required steam amount varies considerably accordingly, so that the present invention has a great advantage.

C8. Modification 8: In the above embodiment, an example of an electric vehicle using the fuel cell system 60 was described, but the present invention is a hybrid vehicle using two prime movers, a motor and an internal combustion engine, as a prime mover for driving wheels. It can also be applied to (hybrid vehicles). The present invention is also applicable to moving bodies other than automobiles, such as ships and trains. That is, the present invention can be applied to a moving body including a fuel cell, a fuel reformer, and a prime mover driven by electric power supplied from a power source including the fuel cell. The present invention is also applicable to a stationary fuel reformer.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electric vehicle as an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an internal configuration of a fuel cell system 60 in the first embodiment.

FIG. 3 is a perspective view showing an orthogonal heat exchanger of an evaporation section 210.

FIG. 4 is a control block diagram relating to control of an evaporation unit 210 in the first embodiment.

FIG. 5 is a graph showing a map of a ratio Y1 / Y2 of flow rates Y1 and Y2.

FIG. 6 is a flowchart showing a control procedure of the evaporation unit 210 in the first embodiment.

FIG. 7 is an explanatory diagram showing an internal configuration of a fuel cell system 60a in a second embodiment.

FIG. 8 is an explanatory diagram showing an example of local steam temperatures T1 to T3 measured by local steam temperature sensors 304a to 304c.

[Explanation of symbols]

13 ... Rotation axis 14 ... Output shaft 15 ... Output shaft 16 ... Differential gear 17 ... Axle 18 ... Wheels 20 ... Motor 22 ... rotor 24 ... Stator 30 ... Torque converter 40 ... Transmission 50 ... Battery 51, 52 ... Driving circuit 60 ... Fuel cell system 70 ... Control unit 72 ... Shift lever 74 ... accelerator pedal 76 ... Brake pedal 80 ... Changeover switch 100 ... FC control unit 110 ... Gas phase control unit 112 ... Gas phase calorific value calculation unit 114 ... PID control unit 116 ... Subtractor 118 ... Adder 120 ... Liquid phase control unit 122 ... Liquid phase calorie calculation unit 124 ... PID control unit 126 ... Subtractor 128 ... Adder 200 ... Fuel reformer 210 ... Evaporator 212 ... Combustion gas flow path 213a-213c ... Horizontal flow path 214 ... Reforming material flow path 214a ... Vertical DC path 216 ... Electrically heated combustion catalyst section (combustion EHC) 218a, 218b ... Folded flow path section 220 ... reforming section 222 ... Reforming catalyst 224 ... Electric heating type reforming catalyst section (reforming EHC) 226 ... Temperature sensor 230 ... CO purification unit 244, 246, 248 ... Actuator 252 ... Pressure sensor 254 ... Flow rate adjusting valve 260 ... Anode exhaust gas flow path 262 ... Flow rate adjusting valve 300 ... Fuel cell 302 ... Temperature sensor 304 ... Temperature sensor 304a-304c ... Local vapor temperature sensor 306 ... Flowmeter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/06 H01M 8/06 G (72) Inventor Kiyomi Nagamiya 1 Toyota-cho, Toyota-shi, Aichi Toyota Auto In-car F-term (reference) 3K068 AA00 AB22 AB35 EA03 3L021 BA03 DA21 FA11 4G140 EA02 EA03 EA06 EB03 EB04 EB43 5H027 AA02 BA01 DD05 MM13

Claims (11)

[Claims] 1. A steam generator for heating a fluid to be heated by a heating fluid and evaporating the fluid to generate a gaseous fluid to be heated, the heating fluid passage through which the heating fluid flows, and the fluid to be heated. A heat exchanger having a heated fluid flow path through which a flow rate, a flow rate adjusting section for adjusting the flow rate of the heating fluid introduced into the heating fluid flow path, a control section for controlling the flow rate adjusting section, The heat exchanger has a liquid phase part in which the heated fluid is mainly liquid, and a vapor phase part in which the heated fluid is mainly gaseous, and the flow rate adjusting part is At least one first flow rate adjusting element for introducing the heating fluid into the heating fluid channel of the vapor phase section, and at least 1 for introducing the heating fluid into the heating fluid channel of the liquid phase section Two second flow rate adjusting elements, and The controller controls the first flow rate of the heating fluid introduced into the gas phase section by the first flow rate adjusting element and the first flow rate of the heating fluid introduced into the liquid phase section by the second flow rate adjusting element. A steam generator, wherein the second flow rate and the second flow rate are respectively controlled based on different types of target values. 2. The steam generator according to claim 1, wherein the control unit independently controls the first and second flow rate adjusting elements without directly depending on an operation amount of each other. ,
Steam generator. 3. The steam generator according to claim 1, wherein the control unit controls the first flow rate adjusting element with the temperature of the gaseous heated fluid as a target value, and the gas. Generator for controlling the second flow rate adjusting element with the flow rate of the heated fluid as a target value. 4. The steam generator according to claim 1, wherein the heating fluid contains combustion fuel, air, and combustion gas produced by burning the combustion fuel as components. The said 1st and 2nd flow volume adjustment element is a steam generator which is for adjusting the flow volume of the said combustion fuel. 5. The steam generator according to claim 4, wherein the flow rate adjusting unit further supplies a third flow rate for supplying air used for combustion of the combustion gas to the heating fluid flow path. An adjusting element is provided, and the control unit controls the flow rate of the air introduced into the heating fluid channel by the third flow rate adjusting element in accordance with the total amount of combustion fuel introduced into the heating fluid channel. To do
Steam generator. 6. The steam generator according to claim 1, wherein the heated fluid flow path includes a plurality of vertical direct current paths arranged substantially vertically, The passage includes a plurality of horizontal flow passages arranged substantially horizontally, and the heat exchanger includes an orthogonal heat exchange unit configured by the plurality of vertical flow passages and the plurality of horizontal flow passages, Steam generator. 7. The steam generator according to claim 6, wherein the plurality of horizontal flow passages are divided into a plurality of stages having different flow directions of the heating fluid, and the horizontal flow passages of adjacent stages are , At least one stage of the plurality of stages, which is connected to each other through a turn-back flow path portion provided at an end, corresponds to the gas phase portion, and is included in the plurality of stages. At least one step on the relatively lower side corresponds to the liquid phase section, and the second flow rate adjusting element connects between the step of the liquid phase section and the step of the gas phase section that are adjacent to each other. A steam generator for adjusting the flow rate of the heating fluid introduced into the folded flow path portion. 8. A steam generator for heating a fluid to be heated with a heating fluid to evaporate the fluid to be heated, the heating fluid passage having the heating fluid flowing therethrough, and the fluid to be heated. A heat exchanger having a heated fluid flow path through which a flow rate is adjusted, a flow rate adjusting unit for adjusting the flow rate of the heating fluid introduced into the heating fluid flow path, and for measuring the temperature of the heated fluid. A temperature measurement unit, and a control unit for controlling the flow rate adjustment unit, the heated fluid flow passage is divided into a plurality of small flow passages inside the heat exchanger, the temperature measurement unit, It has a plurality of temperature sensors provided in the vicinity of the outlet of at least some of the small channels in the plurality of small channels, the control unit, to a plurality of temperatures respectively measured by the plurality of temperature sensors The weighting is not equal to Calculates the average temperature of the gaseous heated fluid discharged from the exchanger, steam generator, wherein the controller controls the flow rate adjusting unit based on the average temperature. 9. A fuel reforming apparatus for producing a hydrogen-rich fuel gas from a reforming raw material containing a hydrocarbon compound, wherein a liquid reforming raw material is vaporized to produce a gaseous reforming raw material. A fuel reformer comprising: the steam generator according to any one of claims 1 to 8; and a reformer that reforms the gaseous reforming raw material. 10. A method for producing a gaseous heated fluid by heating and evaporating the heated fluid with a heating fluid, comprising: (a) a heating fluid channel through which the heating fluid flows;
A heat having a heated fluid flow path through which the heated fluid flows and divided into a liquid phase portion in which the heated fluid is mainly liquid and a vapor phase portion in which the heated fluid is mainly gaseous. A step of preparing an exchanger; (b) a first flow rate of the heating fluid introduced into the vapor phase part; and a second flow rate of the heating fluid.
Controlling the second flow rate of the heating fluid introduced into the liquid phase portion by the flow rate adjusting element based on different kinds of target values. 11. A method for heating a fluid to be heated by a heating fluid and evaporating the fluid to generate a gaseous fluid to be heated, comprising: (a) a heating fluid channel through which the heating fluid flows;
Preparing a heat exchanger having a heated fluid channel through which the heated fluid flows and dividing the heated fluid channel into a plurality of small channels; and (b) the plurality of small streams. In the vicinity of the outlet of at least a part of the small passage in the passage,
Measuring each of a plurality of temperatures, (c) unequal weighting the plurality of temperatures to calculate an average temperature of the gaseous heated fluid discharged from the heat exchanger, and (d) ) Controlling the flow rate of the heating fluid supplied to the heat exchanger based on the average temperature;
A steam generating method comprising: