JP4506091B2 - How to start the evaporator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for starting an evaporator obtained by evaporating a raw material gas of a fuel cell system from a liquid raw material.
[0002]
[Prior art]
Conventionally, an evaporator in which a liquid raw material is evaporated and supplied as a raw material gas to a reforming reactor of a fuel cell system is known (see Patent Document 1).
[0003]
This evaporator introduces combustion gas obtained by burning the anode exhaust gas of the fuel cell into a pipe arranged in the evaporation chamber as an evaporation heat source, and directs the liquid raw material from the raw material injection device provided in the upper part of the evaporation chamber toward the pipe. By being injected, it is configured to evaporate and gasify as a raw material gas.
[0004]
[Patent Document 1]
JP 2002-124278 A
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional example, the liquid material is injected into a pipe into which an evaporation heat source in the evaporator is introduced to evaporate and gasify. Due to thermal shock, excessive thermal stress is generated in the evaporator itself, and the reliability of the evaporator is lowered.
[0006]
In addition, even when liquid raw material is jetted and evaporated whenever required on the reformer side, excessive thermal stress is generated in the evaporator due to the thermal shock due to the temperature difference, thereby reducing the reliability of the evaporator. There was a bug to do.
[0007]
Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a method for starting an evaporator that can prevent thermal shock and improve durability reliability.
[0008]
[Means for Solving the Problems]
  BookThe invention is to first evaporate the liquid raw material to be evaporated, And stop the supply when the evaporator is full,Next, introduce the hot side fluid into the evaporator.Then, while continuing the introduction of the high temperature side fluid, a part of the liquid raw material filled in the evaporator is withdrawn outside the evaporator to reduce the amount of the liquid raw material in the evaporator, and then the liquid raw material in the evaporator is increased. In the process of being heated, the extracted liquid raw material or new liquid raw material is supplied again to the evaporator.I did it.
[0010]
【The invention's effect】
  Therefore,BookIn the invention, the liquid raw material to be vaporized first is, And stop the supply when the evaporator is full,Next, since the high temperature side fluid is introduced into the evaporator, the liquid raw material sequentially takes away the latent heat of evaporation from the evaporator, thereby suppressing the occurrence of a local temperature gradient in the evaporator and preventing thermal shock. The durability and reliability of the evaporator can be improved.
  In addition, while continuing the introduction of the high temperature side fluid, a part of the liquid raw material filled in the evaporator is extracted outside the evaporator to reduce the amount of the liquid raw material in the evaporator, and then the liquid raw material in the evaporator is increased. In the process of being warmed, the extracted liquid raw material or new liquid raw material is again supplied to the evaporator, so that the temperature rise of the evaporator can be accelerated and the startup time can be shortened.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the starting method of the evaporator of this invention is demonstrated based on each embodiment.
[0013]
  (Reference example)
  1 to 3 show the present invention.Is the premise ofHow to start the evaporatorReference exampleFIG. 1 showsReference exampleFIG. 2 is a schematic diagram of a fuel cell system including the evaporator, FIG. 2 is a system configuration diagram of an evaporator operating device, and FIG. 3 is a flowchart of a starting method by a controller. First, according to FIG.Reference exampleA fuel cell system including the operation device for the evaporator will be described.
[0014]
In FIG. 1, a fuel cell system includes a reforming reactor 1 that generates a hydrogen-rich reformed gas from a raw material gas, and a fuel cell stack 2 that generates power using hydrogen contained in the reformed gas and oxygen contained in the air. And a combustor 3 for burning the anode exhaust gas of the fuel cell stack 2 with air, and a raw material gas supply means 4 for supplying the raw material gas to the reforming reactor 1.
[0015]
The reforming reactor 1 reforms a raw material gas mainly composed of hydrocarbons supplied from the raw material gas supply means 4 to generate a hydrogen-rich reformed gas, and supplies it to the fuel cell stack 2 as an anode gas. To do. The fuel cell stack 2 generates power by an electrochemical reaction between hydrogen in the reformed gas supplied from the reforming reactor 1 and oxygen in the air sent out by the air supply blower 9. The anode exhaust gas discharged without being subjected to the electrochemical reaction is supplied to the exhaust hydrogen combustor 3, and the cathode exhaust gas is supplied to the raw material gas supply means 4 as a low-temperature side heating gas. The exhaust hydrogen combustor 3 burns the anode exhaust gas from the fuel cell stack 2 with the air sent from the air supply blower 9 and supplies the combustion gas to the raw material gas supply means 4 as a high temperature side heating gas.
[0016]
The raw material gas supply means 4 generates a raw material gas from a liquid raw material and supplies it to the reforming reactor 1 of the fuel cell system, an evaporator 6 for evaporating and gasifying the liquid raw material, and the exhaust hydrogen The heat source control means 7 selectively supplies the combustion gas of the combustor 3 and the cathode exhaust gas of the fuel cell stack 2 as heat sources to the evaporator 6, and the liquid raw material supply means 8 that supplies the liquid raw material to the evaporator 6. .
[0017]
The evaporator 6 stores the liquid raw material supplied from the liquid raw material supply means 8 in an evaporation container (not shown), and evaporates and gasifies it by the heat of the heating gas supplied as a heat source from the heat source control means 7. 10 to the reforming reactor 1.
[0018]
The heat source control means 7 is, for example, a first flow rate adjusting valve 11 that adjusts the supply amount of anode exhaust gas to the evaporator 6, and a first adjuster that adjusts the supply amount of combustion gas of the exhaust hydrogen combustor 3 to the evaporator 6. 2 flow rate adjusting valve 12.
[0019]
As the first flow rate adjusting valve 11, the cathode exhaust gas of the fuel cell stack 2 can be supplied to the evaporator 6 as a low-temperature side heating gas at one switching position, and can be discharged to the outside air at the switching position to the other. . Further, the first flow rate adjusting valve 11 can adjust the proportion of the discharge amount and the supply amount to both the cathode exhaust gas at the intermediate switching position by adjusting the switching position of the cathode exhaust gas.
[0020]
As the second flow rate control valve 12, the combustion gas of the exhaust hydrogen combustor 3 can be supplied to the evaporator 6 as a high-temperature side heating gas at one switching position, and the evaporator 6 is bypassed at the switching position to the other. And can be discharged to the outside air. The second flow rate adjusting valve 12 can adjust the distribution ratio of the discharge amount and the supply amount to both of them by adjusting the switching position of the combustion gas at the intermediate switching position.
[0021]
The temperature of the cathode exhaust gas is usually about 60 ° C. to 70 ° C., and the temperature of the combustion gas is usually about 400 ° C., for example. For this reason, the temperature of the gas supplied to the evaporator 6 can be adjusted by adjusting the mixing ratio of the combustion gas and the cathode exhaust gas. When only the combustion gas is supplied, the heating energy becomes maximum, and the cathode exhaust gas is supplied. In the case of supplying only the heating energy, the heating energy can be minimized.
[0022]
The liquid source supply means 8 includes a tank 13 for storing the liquid source, a pump 14 for supplying the liquid source in the tank 13 to the evaporator 6, and a return passage 16 with a condenser 15 extending from the three-way valve 10 to the tank 13. With. When the operation is stopped, the pump 14 can be reversed so that the liquid raw material in the evaporator 6 is drawn out and collected in the tank 13, and the raw material gas evaporated from the evaporation container is supplied by the condenser 15 via the three-way valve 10. It can be liquefied and collected in the tank 13.
[0023]
In the fuel cell system having the above configuration, the reformed gas obtained by reforming the source gas from the source gas supply means 4 by the reforming reactor 1 and the air from the air supply blower 9 are introduced into the fuel cell stack 2. Used for power generation. The anode exhaust gas, which is the reformed gas that has not been used for power generation, is supplied to the exhaust hydrogen combustor 3 and combusted by the air supplied from the air supply blower 9 in the exhaust hydrogen combustor 3, and the combustion gas is a raw material gas supply means. 4 is introduced. The cathode exhaust gas from the fuel cell stack 2 is also introduced into the raw material gas supply means 4.
[0024]
Next, the system configuration of the evaporator operating device will be described with reference to FIG.
[0025]
In the evaporator 6, the combustion gas from the exhaust hydrogen combustor 3 and the exhaust cathode gas from the fuel cell stack 2 are mixed by the first and second flow rate adjusting valves 11 and 12 of the heat source control means 7 to adjust the temperature. The high temperature gas is supplied, and the high temperature gas is discharged through the outlet valve 17. Here, the first and second flow rate adjusting valves 11 and 12 are illustrated as a single valve, and are hereinafter simply referred to as the inlet valve 11. In this case, the inlet valve 11 may be a case where only the combustion gas from the exhaust hydrogen combustor 3 is supplied. The inlet valve 11 and the outlet valve 17 are controlled to open and close by the controller 5.
[0026]
The evaporator 6 is provided with a level sensor 18 for detecting the liquid level of the supplied liquid raw material, and a level signal from the level sensor 18 is input to the controller 5.
[0027]
  The liquid material supply means 8 is provided in the tank 13.StoredThe system for supplying the liquid raw material to the evaporator 6 includes a pump 14 and an inlet valve 19. The inlet valve 19 is controlled to be opened and closed by the controller 5. The pump 14 is driven by the electric motor 20, and the electric motor 20 is driven by the controller 5. The rotation direction and rotation speed are controlled. The raw material gas evaporated from the evaporator 6 is supplied to the reforming reactor 1 through a three-way valve 10 that is controlled to open and close by the controller 5.
[0028]
The controller 5 starts the evaporator 6 according to the start command for the evaporator 6 output from the control device 21 of the host fuel cell system, and stops the evaporator 6 according to the stop command for the evaporator 6.
[0029]
The operation device for the evaporator having the above configuration is controlled by the controller according to the control flowchart shown in FIG. The start-up control of the evaporator will be described based on the control flowchart of FIG. Further, the temperature of the evaporator itself will be described with reference to the time chart of FIG. 4 showing the time. Note that the processing of FIG. 3 is executed at regular intervals in the controller 5.
[0030]
  First, in step 1, it is determined whether or not the start-up control of the evaporator 6 is performed. If the evaporator 6 has already been activated, the routine proceeds to step 5 where normal control is executed, and an activation command is issued from the control device 21 of the fuel cell system.IssuedIf it is time to start up, go to Step 2.
[0031]
When the evaporator 6 is stopped, the liquid material in the evaporator 6 is extracted into the tank 13, the pump of the liquid material supply means 8 is stopped, and the inlet valve 19 and the three-way valve 10 are also shut off. . Further, for example, the combustion gas of the exhaust hydrogen combustor 3 that is a heat source is blocked by the inlet valve 11 to be prevented from flowing in, and the outlet valve 17 for the high-temperature gas is also closed.
[0032]
In step 2, the inlet valve 19 is opened, the electric motor 20 is rotated forward, and the liquid raw material, which is a low temperature fluid, is supplied from the tank 13 to the evaporator 6 via the inlet valve 19 by the pump 14 (FIG. 4). (See time t0).
[0033]
  In step 3, the level of the liquid material in the evaporator 6 is monitored by the level sensor 18, and it is determined whether or not the low temperature side fluid is filled up to the specified amount in the evaporator 6. The forward rotation of 20 is continued and the supply of the liquid raw material by the pump 14 is continued. Liquid raw materialUp to the specified amountIf satisfied, go to Step 4.
[0034]
In step 4, the operation of the electric motor 20 is stopped, the inlet valve 19 is shut off, and the inflow of the low temperature side fluid into the evaporator 6 is stopped. In the evaporator 6, the liquid raw material is in a state of being filled by a specified amount, and the temperature is in a low temperature state that is the temperature of the supplied liquid raw material. At the same time, the inlet valve 11 and the outlet valve 17 are opened, the inflow of the high temperature side fluid into the evaporator 6 is started, and the start-up process of the evaporator 6 is ended (see time t1 in FIG. 4).
[0035]
The hot gas from the heat source is introduced into the evaporator 6 and is discharged from the outlet valve 17 via a circulation path (not shown) in the evaporator 6. In the evaporator 6, the temperature is gradually raised by circulation of the high temperature side fluid, and when the evaporation temperature is reached, evaporation and gasification of the liquid material in the evaporator 6 is started, and the raw material obtained by opening the three-way valve 10. Gas is supplied to the reforming reactor 1 (time t2 in FIG. 4).
[0036]
The liquid material is evaporated and gasified in accordance with the temperature rise of the evaporation container due to the supply of the high temperature side fluid after the time point t2, and the liquid material supply means 8 is detected each time the level sensor 18 detects a decrease in the amount of the liquid material due to the evaporation. And the evaporator 6 is shifted to a steady operation.
[0037]
FIG. 5 shows a temperature distribution in the evaporator 6 when the high temperature side fluid is supplied in a state where the low temperature side fluid is filled in the evaporator 6, and the high temperature side fluid that has flowed in raises the temperature of the low temperature side fluid. The temperature of the low-temperature fluid is gradually raised from the range A near the inlet of the high-temperature fluid to the range B. It can be understood that the low-temperature side fluid gradually takes sensible heat and latent heat of vaporization from the evaporator, and gradually rises in temperature over a wide range A and B to some extent, and there is no local temperature gradient and is effective in mitigating thermal shock. .
[0038]
On the other hand, the comparative example shown in FIG. 6 shows the temperature distribution of the evaporator when the low-temperature fluid flows in the state where the evaporator is heated from the high-temperature side fluid. When the low temperature side fluid flows in the evaporator, the temperature is locally lowered in the inflow portions C and D of the low temperature side fluid, a local temperature gradient is generated, and a thermal shock is generated in the evaporator. Reduces durability and reliability such as damage.
[0039]
As described above, at the time of starting to supply the liquid raw material that is the low temperature side fluid to the evaporator 6, the liquid raw material is supplied before the heating gas that is the high temperature side fluid, and the inside of the evaporator 6 is filled with the liquid raw material. To supply heated gas. As a result, the temperature of the evaporation container is governed by the temperature of the liquid raw material with good heat transfer, so that even if the heating gas is supplied all at once, the evaporator 6 itself does not undergo a sudden temperature change. The generation of excessive stress due to thermal shock can be suppressed.
[0040]
  BookReference exampleCan produce the effects described below.
[0041]
(A) First, the liquid raw material to be evaporated is filled in the evaporator 6 and then the evaporator 6 is started by introducing the high temperature side fluid into the evaporator 6. It will be taken away from the evaporator 6, generation of a local temperature gradient in the evaporator 6 can be suppressed, thermal shock can be prevented, and durability reliability of the evaporator 6 can be improved.
[0042]
  (First embodiment)
  FIGS. 7 and 8 show an evaporator starting method to which the present invention is applied.First embodimentFIG. 7 is a system configuration diagram of the evaporator operating device, and FIG. 8 is a control flowchart by the controller. In the present embodiment, a configuration in which the transition to the evaporation temperature is accelerated by temporarily removing the liquid raw material in the evaporator during the temperature rising process of the evaporator.Reference exampleIt is added to. In addition,Reference exampleThe same apparatus is denoted by the same reference numeral, and the description thereof is omitted or simplified.
[0043]
In FIG. 7, a separate tank 23 is connected to the evaporator 6 via a pipe 22, and the evaporator 6 and the separate tank 23 are selected between a communication state and a cutoff state by a valve 24 arranged in the pipe 22. In addition, when the valve 24 is opened, the pump 25 provided in the pipe 22 is rotated forward or reverse by the electric motor 26 to transfer the liquid raw material in the evaporator 6 to another tank 23 or to another tank. The liquid raw material in 23 can be transferred back to the evaporator 6.
[0044]
The separate tank 23 stores the liquid raw material temporarily removed from the evaporator 6 and has a heat retaining function in order to suppress a temperature drop during storage. The rotation direction and rotation speed of the electric motor 26 and the opening / closing of the valve 24 are controlled by the controller 5. The controller 5 monitors the temperature in the separate tank 23 and the evaporator 6 with temperature sensors 27 and 28 provided respectively. Other configurations are the same as those in the first embodiment.
[0045]
The operation device for the evaporator having the above configuration is controlled by the controller according to the control flowchart shown in FIG. 8 executed at regular intervals in the controller. 8 are the same as steps 1 to 5 of the first embodiment, and here, the start-up control of the evaporator from step 6 will be described based on the control flowchart. The change in the temperature of the evaporator itself will be described together with the time chart of FIG.
[0046]
In step 6, for example, the heat capacity of the evaporator 6 that varies depending on the volume of the evaporator 6 and the liquid, the use environment state that varies depending on the temperature of the evaporator 6 and the liquid, and the actual evaporation input by the temperature sensor 28. The startup time ts predicted from the temperature rise rate of the vessel 6 is shorter than the startup time td required by the fuel cell system 21 (waiting time until steam is supplied to the fuel cell system) (ts ≦ td). It is determined whether or not. If the predicted activation time ts is shorter than the requested activation time td, the process proceeds to step 10, and if it is longer, the process proceeds to step 7. When it is determined that the predicted activation time ts is shorter than the required activation time td, it is not necessary to go through steps 7 to 9 for shortening the temperature rise time described later, and the liquid material by the high-temperature side fluid is retained while holding the liquid material. The temperature rise is continued.
[0047]
In step 7, the valve 24 is opened, the pump 25 is driven by the electric motor 26, and the liquid raw material, which is the low-temperature side fluid stored in the evaporator 6, is extracted into another tank 23 (see time t3 in FIG. 9). . The level sensor 18 monitors the presence or absence of the liquid raw material in the evaporator 6, and at the time of extraction, the electric motor 26 and the pump 25 are stopped and the valve 24 is closed. The evaporator 6 in a state where the liquid raw material has been removed has a small heat capacity, while the supply of the high temperature side fluid is continued, so that the rate of temperature rise is increased.
The liquid raw material withdrawn into the separate tank 23 is suppressed from being reduced in temperature by the heat retention function of the separate tank 23.
[0048]
In step 8, the temperature of the evaporator 6 monitored by the temperature sensor 28 is the temperature at which steam can be supplied within the startup time td required for the fuel cell system when a predetermined amount of liquid is supplied again. It is determined whether or not the temperature has increased to the predetermined temperature. If the predicted temperature has been reached (see time t5 in FIG. 9), the process proceeds to step 9. Note that the amount of the predetermined amount of liquid is desirably the amount of liquid that should be present in the evaporator 6 in a steady operation state (design value determined from the design matters of the evaporator).
[0049]
In step 9, the valve 24 is opened, and the pump 25 is driven by the electric motor 26 in the supply direction opposite to the extraction direction, so that the liquid material extracted in the separate tank 23 is supplied to the evaporator 6 again. The amount of the liquid raw material in the evaporator 6 is monitored by the level sensor 18, and when the specified amount of the evaporator 6 is reached, the electric motor 26 and the pump 25 are stopped, and the valve 24 is closed. Since the liquid raw material returned to the evaporator 6 has been heated in the evaporator 6 and kept warm in the separate tank 23 between Step 4 and Step 5, the temperature difference from the temperature of the evaporator 6 is The liquid raw material in the tank 13 is small and does not cause a thermal shock to the evaporator 6, and the temperature is quickly raised to the evaporation temperature, thereby realizing reliable evaporation of the liquid raw material.
[0050]
In step 10, when the start-up time comes, the inlet valve 19 is opened, the pump 14 is driven by the electric motor 20, and a liquid material having a flow rate required for the fuel cell system 21 is supplied from the tank 13 to the evaporator 6. Is transferred to steady operation.
[0051]
As shown in the time chart of FIG. 9, the evaporator 6 starts from the time t <b> 3 when the liquid raw material is extracted, rather than the vapor generation time indicated by the dotted line (time t <b> 2 in FIG. 9) when the filled liquid raw material is not extracted. The temperature rise rate increases, and steam can be generated exceeding the evaporation temperature at an early time point t4. In some cases, after the temperature is further increased as at time point t5, the liquid from the separate tank 23 is generated. The temperature is temporarily lowered by the raw material.
[0052]
In the above control flowchart, the liquid raw material in another tank 23 that is expected to have a small temperature difference from the evaporator 6 is returned to the evaporator 6. However, a thermal shock that causes deterioration is caused by the evaporator 6. If the temperature difference is small so as not to occur, the liquid raw material in the tank 13 having a temperature lower than that of the separate tank 23 may be supplied to the evaporator 6. The temperature difference between the evaporator 6 and the liquid when the liquid is supplied again can be obtained by heat conduction calculation or experiment such as 100 ° C. or 200 ° C., for example.
[0053]
In the control flowchart, the determination criterion in step 6 is the activation time, but although not shown, the determination in step 6 may be omitted and the process may proceed from step 4 to step 7. In this case, the determination in step 8 is performed based on whether or not the evaporator 6 has been heated to a temperature at which steam can be generated, or the temperature of the evaporator 6 that is being heated is the temperature of the liquid material to be introduced. It is determined whether the temperature is within a temperature range that does not cause thermal shock, or whether the temperature of the evaporator 6 has been raised to a saturated vapor temperature corresponding to the pressure of the liquid raw material to be introduced, and is satisfied. Thus, the liquid raw material is supplied to the evaporator 6. According to this, the start-up of the evaporator 6 can be accelerated by simpler control, and the thermal shock when the liquid material is introduced again can be effectively prevented.
[0054]
  In this embodiment,Reference exampleIn addition to the effect (a), the following effects can be achieved.
[0055]
  (A) The liquid raw material filled in the evaporator 6 is removed from the evaporator 6 while the introduction of the high temperature side fluid is continued.Reduce the amount of liquid raw material in the sampling evaporator,afterwardsIn the process of increasing the temperature of the liquid raw material in the evaporatorLiquid raw material is again put into the evaporator 6SupplyTo increase the temperature of the evaporator 6,Time until evaporation and gasification of the liquid material in the evaporator can startStartup time can be shortened.
[0056]
  (C) The liquid raw material of the evaporator 6SamplingFromResupplyIs determined from the liquid raw material, the heat capacity of the evaporator 6 itself, and the usage environment.Time required to start evaporation and gasification of the liquid material in the evaporatorOr the temperature rise rate of the evaporator 6 itself after the introduction of the high temperature side fluid is determined.Time required to start evaporation and gasification of the liquid material in the evaporatorTo change according toTime required to start evaporation and gasification of the liquid material in the evaporatorCan be raised and shortened in accordance with the required start-up time from the fuel cell system.
[0057]
  (D) Liquid raw materialsSamplingTo the later evaporator 6ResupplyIs started when the temperature of the evaporator 6 is increased to a temperature at which steam can be generated.ResupplyWhen starting when the temperature is within a temperature range that does not cause thermal shock with respect to the temperature of the liquid raw material to beResupplyWhen starting up at the time when the temperature of the liquid raw material is increased to the saturated vapor temperature corresponding to the pressure at that time, the start-up time can be shortened with simpler control, and the liquid raw material isResupplyCan effectively prevent thermal shock.
[0058]
  (E) From the evaporator 6ExtractedThe liquid raw material is stored in a separate tank with a heat retaining function,ResupplySometimes returned to the evaporator 6,SupplyThe liquid raw material is temporarily warmed once in the evaporator 6, and reliable evaporation can be realized.
[0059]
  (Second embodiment)
  FIG. 10 shows an evaporator start-up method to which the present invention is applied.Second embodimentIt is a control flowchart by the controller which shows. In the present embodiment, a configuration in which the transition to the evaporation temperature is accelerated by leaving a predetermined amount of the liquid raw material in the evaporator during the temperature rising process of the evaporator.First embodimentIt is added to. In addition,First embodimentThe same apparatus is denoted by the same reference numeral, and the description thereof is omitted or simplified. In addition, the system configuration of the evaporator operating device in the present embodiment is:First embodimentSince this is the same, the description thereof is omitted.
[0060]
The operation device for the evaporator according to the present embodiment is controlled by the controller 5 in accordance with a control flowchart shown in FIG. Note that the processing of Step 1 to Step 5 and Step 8 to Step 10 of FIG. 10 is the same as that of the second embodiment, and here, the startup control of the evaporator 6 in Step 6 and Step 7 will be described. Further, a change in the temperature of the evaporator 6 itself will be described with reference to the time chart of FIG.
[0061]
In step 11, the heat capacity of the evaporator 6 that varies depending on the capacity of the evaporator 6 and the liquid, the use environment state that varies depending on the temperature of the evaporator 6 and the liquid, and the actual temperature of the evaporator 6 that is input by the temperature sensor 28. Whether the startup time ts predicted from the rising speed is shorter (ts ≦ td) than the startup time td required by the fuel cell system (waiting time until steam is supplied to the fuel cell system) When the predicted activation time ts is shorter than the requested activation time td, the process proceeds to step 10. When the predicted activation time ts is longer than the required activation time td, it is further calculated how much the liquid volume in the heat capacity of the evaporator 6 can be reduced to supply steam by the required activation time. And go to Step 12.
[0062]
In step 12, the valve 24 is opened, the pump 25 is driven by the electric motor 26, and the liquid raw material, which is the low-temperature side fluid stored in the evaporator 6, is extracted into another tank 23 (see time t3 in FIG. 11). . The presence or absence of the liquid material in the evaporator 6 is monitored by the level sensor 18, and when the amount of the liquid material calculated in step 11 is extracted, the electric motor 26 and the pump 25 are stopped and the valve 24 is closed. The evaporator 6 in which the liquid raw material is left has a small heat capacity, while the supply of the high-temperature fluid is continued, so that the rate of temperature rise is increased. Since the liquid raw material remains in the evaporator 6, the temperature rise becomes slower than that in the second embodiment, and the liquid raw material reaches the evaporation temperature at time t6 in FIG. The liquid raw material withdrawn into the separate tank 23 is suppressed from being reduced in temperature by the heat retention function of the separate tank 23.
[0063]
In step 8, the return timing of the liquid material in the separate tank 23 (time t6 in FIG. 11) is determined. In step 9, the liquid material in the separate tank 23 is returned to the evaporator 6.
[0064]
In this embodiment, the amount of the liquid raw material left in the evaporator 6 is adjusted according to the startup time, and the temperature rising rate of the evaporator 6 itself can be adjusted according to the amount, so that the liquid fuel remains. Therefore, the thermal shock at the time of injecting the fluid to be evaporated next is prevented while relaxing the thermal shock at the time of temperature rise.
[0065]
In steps 11 and 12, the liquid raw material filled in the evaporator 6 is withdrawn little by little, and how much liquid is reduced from the actual temperature rise rate of the evaporator 6, the required start-up. You may make it calculate and determine whether steam can be supplied by time.
[0066]
  In this embodiment, the effect of the first embodiment is achieved.Fruit (In addition to (a) and (e), the following effects can be achieved.
[0067]
  (F) From the evaporator 6ExtractedThe amount of the liquid raw material is determined by the heat capacity of the liquid raw material and the evaporator 6 itself and the use environment state.Time required to start evaporation and gasification of the liquid material in the evaporatorOr, it is determined from the temperature rise rate of the evaporator 6 itself after the introduction of the high temperature side fluid.Time required to start evaporation and gasification of the liquid material in the evaporatorSince the remaining liquid raw material is left in the evaporator 6, the temperature rise of the evaporator 6 can be adjusted according to the start-up time, and thermal shock can be prevented from occurring when the fluid is flowed again.
[Brief description of the drawings]
FIG. 1 of the present inventionAssumptionSchematic of a fuel cell system including an evaporator.
FIG. 2 of the present inventionReference exampleThe system block diagram of the operating device of the evaporator.
[Fig. 3]Reference exampleThe flowchart of the starting method by the controller of.
FIG. 4 is a time chart showing the temperature of the evaporator itself over time.
FIG. 5 is a temperature distribution diagram in the evaporator when the high temperature side fluid is supplied in a state where the evaporator is filled with the low temperature side fluid.
FIG. 6 is a temperature distribution diagram of an evaporator when a low temperature fluid flows in a state where the high temperature side fluid passage is filled with a high temperature side fluid.
[Fig. 7] of the present invention.First embodimentThe system block diagram of the operating device of the evaporator.
[Fig. 8]First embodimentThe flowchart of the starting method by the controller of.
FIG. 9First embodimentTime chart showing the temperature of the evaporator itself over time.
FIG. 10 shows the present invention.Second embodimentThe flowchart of the starting method by the controller of.
FIG. 11Second embodimentTime chart showing the temperature of the evaporator itself over time.
[Explanation of symbols]
  1 Reforming reactor
  2 Fuel cell stack
  3 Exhaust hydrogen combustor
  4 Raw material gas supply means
  5 Controller
  6 Evaporator
  7 Heat source control means
  8 Liquid raw material supply means
  9 Air supply blower
  11, 12 Flow control valve, inlet valve
  13 tanks
  14, 25 Pump
  18 Level sensor
  19 Inlet valve
  23 Separate tank
  24 valves
  27, 28 Temperature sensor

Claims (8)

A starting method of an evaporator obtained by evaporating a raw material gas of a fuel cell system from a liquid raw material by a high temperature side fluid supplied,
First, the liquid raw material to be evaporated is supplied to the evaporator, and the supply is stopped in a state where the evaporator is filled,
Next, the hot side fluid is introduced into the evaporator ,
While continuing the introduction of the high temperature side fluid, a part of the liquid raw material filled in the evaporator is extracted outside the evaporator to reduce the amount of the liquid raw material in the evaporator,
A method for starting an evaporator, characterized in that, in the process of raising the temperature of the liquid raw material in the evaporator thereafter, the extracted liquid raw material or a new liquid raw material is supplied again to the evaporator . The time from extraction to resupply of the liquid raw material of the evaporator depends on the time until the evaporation and gasification of the liquid raw material in the evaporator can be started, which is determined from the heat capacity of the liquid raw material and the evaporator itself and the use environment state. The method for starting an evaporator according to claim 1 , wherein the starting method is changed. The time from the extraction of the liquid material of the evaporator to the re-supply is the time from the start of evaporation / gasification of the liquid material in the evaporator determined from the temperature rise rate of the evaporator itself after the introduction of the high temperature side fluid. The method for starting an evaporator according to claim 1 , wherein the starting method is changed accordingly. The amount of the liquid raw material extracted from the evaporator is the time until the evaporation and gasification of the liquid raw material in the evaporator, which is determined by the heat capacity of the liquid raw material and the evaporator itself and the usage environment, or the high temperature side fluid It is characterized in that it is changed according to the time until evaporation / gasification of the liquid material in the evaporator can be started, which is determined from the temperature rise rate of the evaporator itself after introduction, and the remaining liquid material is left in the evaporator. The method for starting an evaporator according to any one of claims 1 to 3 . 2. The method for starting an evaporator according to claim 1 , wherein the resupply to the evaporator after the liquid raw material is extracted is started when the temperature of the evaporator is increased to a temperature at which steam can be generated. . Re-supply to the evaporator after extraction of the liquid material is started when the temperature of the evaporator being heated is within a temperature range that does not cause a thermal shock with respect to the temperature of the liquid material to be re-supplied. The method for starting an evaporator according to claim 1 , wherein: Resupply to the evaporator after withdrawal of the liquid feedstock, characterized in that it is started when the temperature of the evaporator is heated to saturated steam temperature corresponding to the pressure at the time of the liquid material resupplying The method for starting an evaporator according to claim 2 . Liquid material withdrawn from the evaporator is stored in a separate tank having a thermal insulation function, according to any one of claims 1 to 7 characterized in that it is returned to the evaporator at the time of re-supply How to start the evaporator.

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