JP2012229137A - Hydrogen generating apparatus, fuel cell system and operation method of hydrogen generating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen generating apparatus, fuel cell system and operation method of hydrogen generating apparatus, which can reduce troubles of a reformer in a state where the concentration of oxygen is high in a raw material.SOLUTION: The hydrogen generating apparatus 100 includes: the reformer 1 for generating hydrogen-containing gas from the raw material by a reforming reaction; and a controller 5 for stopping the operation when the concentration of oxygen is a second state higher than a first state in the raw material.

Description

  The present invention relates to a hydrogen generator, a fuel cell system, and a method for operating the hydrogen generator. More specifically, the present invention relates to a hydrogen generator that generates a hydrogen-containing gas using raw materials, a fuel cell system including the hydrogen generator, and a method for operating the hydrogen generator.

  A fuel cell system supplies a hydrogen-containing gas and an oxygen-containing gas to a fuel cell stack (hereinafter simply referred to as a “fuel cell”) to advance an electrochemical reaction between hydrogen and oxygen, thereby converting chemical energy into electricity. It is a system that generates electricity by taking it out as natural energy. The fuel cell system not only has high power generation efficiency, but also can easily use thermal energy generated during power generation. For this reason, the fuel cell system is being developed as a distributed power generation system capable of realizing high energy utilization efficiency.

  In general, there are often no facilities for supplying hydrogen-containing gas. For this reason, hydrogen generators are provided in conventional fuel cell systems. A typical hydrogen generator generates a hydrogen-containing gas (reformed gas) using, as a raw material, city gas mainly composed of natural gas, LPG, or the like supplied from an existing infrastructure. For this purpose, the hydrogen generator is, for example, modified to generate a hydrogen-containing gas by performing a reforming reaction with steam at a temperature of 600 to 700 ° C. using a desulfurization section that removes sulfur components in the raw material, a Ru catalyst, or a Ni catalyst. A quality device is provided (for example, see Patent Document 1).

  The hydrogen-containing gas obtained by the reforming reaction usually contains carbon monoxide derived from the raw material. When the concentration of carbon monoxide is high, the power generation characteristics of the fuel cell are degraded. Therefore, the hydrogen generator is often provided with a reactor such as a shifter, a selective oxidizer, and a methanation remover in addition to the reformer. The shifter includes a Cu—Zn-based catalyst, and reduces the carbon monoxide by causing a shift reaction between carbon monoxide and water vapor at a temperature of 200 ° C. to 350 ° C. The selective oxidizer selectively oxidizes carbon monoxide at a temperature of 100 ° C. to 200 ° C. to further reduce the carbon monoxide. The methanation remover selectively reduces carbon monoxide by selectively methanating it. A selective oxidizer or a methanation remover is also called a selective remover.

  Now, oxygen may be temporarily mixed in the raw material. Thus, a preliminary reforming method for oxygen-containing process gas (for example, natural gas, peak shaving gas, LPG, etc.) has been proposed (for example, see Patent Document 2).

JP 2003-183005 A Japanese Patent Laid-Open No. 2001-80907

  Here, as described in Patent Document 2, when the oxygen concentration in the raw material is relatively high, the heat balance of the reformer is generated by the heat generated by the oxidation reaction between hydrogen and oxygen in the hydrogen-containing gas. Can break down and cause problems in the reformer.

  The present invention solves such a problem, and provides a hydrogen generator, a fuel cell system, and an operation method of the hydrogen generator that can reduce the malfunction of the reformer in a state where the oxygen concentration in the raw material is high as compared with the conventional technology. For the purpose.

  In order to solve the above problems, a hydrogen generator of the present invention includes a reformer that generates a hydrogen-containing gas from a raw material by a reforming reaction, and a second state in which the oxygen concentration in the raw material is higher than the first state. And a controller for stopping the operation.

  The fuel cell system of the present invention includes the above hydrogen generator and a fuel cell that generates power using a hydrogen-containing gas supplied from the hydrogen generator.

  Moreover, the operating method of the hydrogen generator of the present invention includes a step of stopping the operation when the oxygen concentration in the raw material is in the second state higher than the first state.

  According to the hydrogen generator, the fuel cell system, and the operation method of the hydrogen generator of the present invention, the malfunction of the reformer can be reduced more than before in a state where the oxygen concentration in the raw material is high.

FIG. 1 is a block diagram illustrating an example of a schematic configuration of a hydrogen generator according to the first embodiment. FIG. 2 is a flowchart showing an example of an operation method of the hydrogen generator in the first embodiment. FIG. 3 is a block diagram illustrating an example of a schematic configuration of the fuel cell system according to the second embodiment.

(First embodiment)
The hydrogen generator according to the first embodiment operates when a reformer that generates a hydrogen-containing gas from a raw material by a reforming reaction and a second state in which the oxygen concentration in the raw material is higher than the first state. And a controller for stopping.

  The operation method of the hydrogen generator according to the first embodiment includes a step of generating a hydrogen-containing gas from a raw material in a reformer, and an operation when the oxygen concentration in the raw material is in a second state higher than the first state. The step of stopping is provided.

  With such a configuration, the malfunction of the reformer can be reduced more than before when the oxygen concentration in the raw material is high.

  “Stopping the operation” means stopping the hydrogen generation operation in the reformer. Also, the stop of the hydrogen generation operation means that at least one of the operations necessary for the progress of the reforming reaction is stopped in the reformer. For example, it means stopping at least one of the supply of reaction raw materials to the reformer and the heating operation of the reformer. In the case of the steam reforming reaction, the reaction raw materials are the raw material and water vapor. In the case of the autothermal reaction, the reaction raw material is the raw material, water vapor and air. In the case of the partial oxidation reaction, the reaction raw material is the raw material and air. .

  The hydrogen generation apparatus includes a temperature detector that detects the temperature of the reformer, and the controller has an oxygen concentration in the raw material when the temperature detected by the temperature detector is equal to or higher than a predetermined upper limit temperature. It may be configured to determine that the state is the second state and stop the operation.

  The hydrogen generation apparatus includes a temperature detector that detects the temperature of the reformer, and the controller is configured such that when the rate of increase in temperature detected by the temperature detector per unit time is equal to or higher than a predetermined rate of increase. The operation may be stopped by determining that the oxygen concentration in the raw material is in the second state.

[Device configuration]
FIG. 1 is a block diagram illustrating an example of a schematic configuration of a hydrogen generator according to the first embodiment.

  In the example shown in FIG. 1, the hydrogen generator 100 of this embodiment includes a reformer 1, a temperature detector 3, and a controller 5.

  Hereinafter, a configuration example of each component included in the example illustrated in FIG. 1 will be described.

  The reformer 1 generates a hydrogen-containing gas from a raw material by a reforming reaction. The raw material contains at least an organic compound having carbon and hydrogen as constituent elements, and specific examples include natural gas, city gas, hydrocarbons such as LPG and LNG, and alcohols such as methanol and ethanol. City gas refers to gas supplied from a gas company to households through piping. The reforming reaction may be any reforming reaction, and specific examples include a steam reforming reaction, an autothermal reaction, and a partial oxidation reaction.

  As illustrated in FIG. 1, the reformer 1 may be supplied with heat from the combustor 2 to advance the reforming reaction. At least the above raw materials are used as the fuel for the combustor 2, and when the generation of the hydrogen-containing gas is started in the reformer 1, the hydrogen-containing gas is also used as the fuel.

  The hydrogen generator 100 includes an oxygen concentration state detector that detects the state of the oxygen concentration contained in the raw material. The oxygen concentration state detector may be any detector as long as it can detect the state of the oxygen concentration contained in the raw material. Here, the state of oxygen concentration is defined as meaning at least one of an oxygen concentration value in the raw material and a relative high or low state of the oxygen concentration in the raw material.

  Specifically, the oxygen concentration state detector includes a first temperature detector that detects the temperature of the hydrodesulfurizer, a second temperature detector that detects the temperature of the reformer, and a pressure detector that detects the supply pressure of the raw material. An oxygen concentration detector provided in the raw material supply path 10 and an ammonia concentration detector provided in the hydrogen supply path 11 are exemplified. The oxygen concentration state detector is communicably connected to the controller 5 and sends information related to the oxygen concentration state to the controller 5. Examples of the information on the oxygen concentration state include a hydrodesulfurizer temperature, a reformer temperature, and an oxygen concentration.

  As described above, the first temperature detector detects the magnitude of heat generated when the oxygen in the raw material and the hydrogen in the hydrogen-containing gas supplied to the hydrodesulfurizer undergo an oxidation reaction as the temperature of the hydrodesulfurizer. To do. The controller 5 can determine the relative high / low state of the oxygen concentration based on at least one of the magnitude of the temperature acquired from the first temperature detector and the change rate of the temperature.

  The second temperature detector detects, as the temperature of the reformer, the magnitude of heat generation when oxygen in the raw material supplied to the reformer and hydrogen generated in the reformer undergo an oxidation reaction. The controller 5 can determine the relative high or low state of the oxygen concentration based on at least one of the magnitude of the temperature acquired from the second temperature detector and the rate of temperature change.

  Usually, the raw material supply pressure decreases before execution of peak shaving, and the raw material supply pressure decreases after execution of peak shaving. Based on the pressure change detected by the pressure detector, the controller 5 can determine that the oxygen concentration in the raw material is high by peak shaving.

  The oxygen concentration detector can detect the oxygen concentration value itself.

  The ammonia concentration detector detects the ammonia concentration in the hydrogen-containing gas. When oxygen is mixed into the raw material, air is usually mixed into the raw material, so that not only oxygen but also nitrogen is mixed into the raw material. Nitrogen mixed in the raw material reacts with hydrogen generated in the reformer 1 to generate ammonia. Therefore, based on the concentration acquired from the ammonia concentration detector, it is possible to determine the relative level of the oxygen concentration.

  The temperature detector 3 is a temperature detector for detecting the state of oxygen concentration in the raw material supplied to the reformer 1, and is an example of an oxygen concentration state detector. The temperature detector 3 is disposed at a predetermined position of the reformer 1 that can detect the temperature according to the state of the oxygen concentration in the raw material. In other words, the temperature detector 3 is an example of a second temperature detector. The temperature detector 3 is disposed, for example, in the upstream portion of the reformer 1. This is because oxygen in the raw material that has flowed into the reformer 1 is mostly consumed in the upstream portion of the reformer 1 due to an oxidation reaction with hydrogen, so the state of oxygen concentration in the raw material This is because the temperature of the reformer 1 is likely to change according to the above.

  The controller 5 only needs to have a control function, and includes an arithmetic processing unit (not shown) and a storage unit (not shown) that stores a control program. Examples of the arithmetic processing unit include an MPU and a CPU. A memory is exemplified as the storage unit. The controller may be composed of a single controller that performs centralized control, or may be composed of a plurality of controllers that perform distributed control in cooperation with each other (in other embodiments and modifications thereof). The same applies to the controller). The controller 5 is communicably connected to the temperature detector 3.

  The hydrogen generator 100 further includes a raw material supplier that is not shown.

  The raw material supplier adjusts the flow rate of the raw material supplied to the reformer 1. The raw material supplier may have any configuration as long as the flow rate of the raw material can be adjusted, and is configured by, for example, at least one of a booster and a flow rate adjustment valve.

  The hydrogen generator 100 further includes a water vapor supply device (not shown). The steam supplier supplies steam to the reformer 1. The water vapor supply device includes an evaporator (not shown) and a water supply device (not shown). In addition, when the reforming reaction in the reformer 1 is a partial oxidation reaction, the steam supply unit may not be provided.

  Although not shown in FIG. 1, the hydrogen generator 100 may include a carbon monoxide reducer downstream of the reformer 1. The carbon monoxide reducer reduces the concentration of carbon monoxide in the hydrogen-containing gas produced by the reformer 1. As the carbon monoxide reducer, at least one of a transformer and a carbon monoxide remover is used. The transformer reduces carbon monoxide by a shift reaction. The carbon monoxide remover reduces carbon monoxide in at least one of an oxidation reaction and a methanation reaction.

  The hydrogen generator 100 according to the present embodiment stops operation when the oxygen concentration in the raw material is in the second state higher than the first state.

  FIG. 2 is a flowchart showing an example of the above operation of the hydrogen generator in the first embodiment. Hereinafter, the operation method of the hydrogen generator 100 will be described with reference to FIG.

  That is, when the hydrogen generator 100 starts the determination operation of the oxygen concentration state (start), the controller 5 determines whether the oxygen concentration state is the second state based on the information received from the temperature detector 3. Is determined (step S101). The first state means when the oxygen concentration in the raw material is in a relatively low state. Here, the second state refers to a state in which the oxygen concentration in the raw material is relatively higher than that in the first state. The second state is a state in which it is difficult to continue the hydrogen generation operation in the reformer. For example, when the hydrogen generation operation is continued, the reformer structure is caused by an excessive temperature rise accompanying the oxidation reaction of hydrogen. Is set as an oxygen concentration exceeding at least one of the heat resistance temperature of the reforming catalyst and the heat resistance temperature of the reforming catalyst.

  The above determination can be made, for example, based on whether or not the temperature detected by the temperature detector 3 is equal to or higher than a predetermined upper limit temperature. In this case, when the detected temperature is equal to or higher than the upper limit temperature, it is determined to be in the second state, and when it is lower than the upper limit temperature, it is determined not to be in the second state, that is, to be in the first state. . The upper limit temperature is defined as the temperature when the oxygen concentration in the raw material is in the second state, and may be, for example, 700 ° C.

  When the state of the oxygen concentration in the raw material is the first state, the determination result in step S101 is No, and the controller 5 continues the operation of the hydrogen generator 100 (step S102) and ends the determination operation. (End).

  When the state of the oxygen concentration in the raw material is the second state, the determination result in step S101 is Yes, and the controller 5 stops the operation of the hydrogen generator 100 (step S103) and ends the determination operation. (End). In stopping the operation, the operations of the raw material supplier (not shown) and the water supplier (not shown) are stopped, and the hydrogen generation operation in the reformer is stopped.

  Further, the hydrogen generator 100 is not limited to a mode in which the state of the oxygen concentration in the raw material is determined based on the magnitude of the temperature detected by the temperature detector 3, and detects the state of the oxygen concentration in the raw material based on the speed of temperature change. It may be a form. That is, the controller 5 determines that the oxygen concentration in the raw material is in the second state when the rising speed per unit time of the temperature detected by the temperature detector is equal to or higher than a predetermined rising speed. The operation may be stopped. This is because when the oxygen concentration in the raw material changes, it tends to appear as a temperature change of the reformer 1 quickly.

  The increase in temperature may occur later than the increase in oxygen concentration. By the determination using the temperature increase rate, the oxygen concentration increase can be detected more quickly than the determination using the temperature itself. When the determination is performed using the temperature increase rate, the controller 5 may further include a timer (not shown). The controller 5 receives the temperature detected by the temperature detector 3 every predetermined time, stores it in the storage unit, and calculates the rate of temperature increase per unit time.

  Alternatively, the hydrogen generator 100 may be configured to detect the state of the oxygen concentration in the raw material based on the magnitude of the temperature detected by the temperature detector 3 and the rate of change of the detected temperature.

(Second Embodiment)
The fuel cell system according to this embodiment includes any one of the hydrogen generators according to the first embodiment and the modifications thereof, and a fuel cell that generates power using the hydrogen-containing gas supplied from the hydrogen generator.

  With such a configuration, the malfunction of the reformer can be reduced more than before when the oxygen concentration in the raw material is high.

  FIG. 3 is a block diagram illustrating an example of a schematic configuration of the fuel cell system according to the second embodiment. The fuel cell system 200 of the second embodiment includes a fuel cell 20 in addition to the hydrogen generator 100.

  In the fuel cell system of the present embodiment, the configuration other than the above can be configured in the same manner as the hydrogen generator of at least one of the first embodiment and its modification. Therefore, about the component which is common in FIG. 3 and FIG. 1, the same code | symbol and name are attached | subjected and description is abbreviate | omitted.

  The fuel cell 20 generates power using the hydrogen-containing gas supplied from the hydrogen generator 100. The fuel cell 20 corresponds to the hydrogen utilization device in the first embodiment. For example, the fuel cell 20 generates power by using a hydrogen-containing gas as a fuel gas and separately supplied air as an oxidant gas. The fuel cell 20 may include a heat recovery mechanism that recovers heat that is simultaneously generated during power generation.

  The fuel cell 20 may be any type of fuel cell, such as a polymer electrolyte fuel cell, a solid oxide fuel cell, or a phosphoric acid fuel cell.

  In the present embodiment, the operation of the fuel cell system 200 when the oxygen concentration in the raw material is in the second state can be the same as that in the first embodiment. Therefore, detailed description is omitted.

  In the fuel cell system 200 of the present embodiment, the operation of the hydrogen generator 100 is stopped and the power generation in the fuel cell 20 is also stopped in step S103 in the first embodiment. That is, the operation of the fuel cell system 200 is stopped.

  From the foregoing description, many modifications and other embodiments of the present invention are obvious to one skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.

  The hydrogen generator, fuel cell system, and operation method of the hydrogen generator of the present invention are a hydrogen generator, a fuel cell system, and a hydrogen generator that can alleviate the problem of the reformer as compared with the conventional method when the oxygen concentration in the raw material is high. This is useful as a driving method.

DESCRIPTION OF SYMBOLS 1 Reformer 2 Combustor 3 Temperature detector 5 Controller 10 Raw material supply path 11 Hydrogen supply path 20 Fuel cell 100 Hydrogen generator 200 Fuel cell system

Claims (5)

A reformer for generating a hydrogen-containing gas from a raw material by a reforming reaction;
And a controller that stops operation when the oxygen concentration in the raw material is in a second state higher than the first state. A temperature detector for detecting the temperature of the reformer,
When the temperature detected by the temperature detector is equal to or higher than a predetermined upper limit temperature, the controller determines that the oxygen concentration in the raw material is in the second state and stops the operation. The hydrogen generator according to claim 1, which is configured. A temperature detector for detecting the temperature of the reformer,
The controller determines that the oxygen concentration in the raw material is in the second state when the rising speed per unit time of the temperature detected by the temperature detector is equal to or higher than a predetermined rising speed. The hydrogen generator according to claim 1, configured to stop operation.   A fuel cell system comprising: the hydrogen generator according to any one of claims 1 to 3; and a fuel cell that generates electric power using a hydrogen-containing gas supplied from the hydrogen generator. Generating a hydrogen-containing gas from the raw material in the reformer;
A method for operating a hydrogen generator, comprising a step of stopping the operation when the oxygen concentration in the raw material is in a second state higher than the first state.

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