JP2019182711A - Hydrogen generator, and method of operating the same - Google Patents

Abstract

To provide a hydrogen generator capable of operating stably by preventing a product material flow path connected to a reactor from being clogged with a deposited product material.SOLUTION: The hydrogen generator 100 includes: a reactor 5 for generating hydrogen and a product material by reacting metal hydride with water; a raw material feeder 2 for feeding metal hydride to the reactor 5; a water feeder 4 for feeding water to the reactor 5; a product material flow path 6 for discharging the product material and water generated by the reactor 5 from the reactor 5; a temperature detector 9 for detecting a temperature of at least any one of the reactor 5 and the product material flow path 6; and a controller 50 for controlling a ratio W/F of a feeding flow of water by the water feeder 4 to a feeding flow of metal hydride by the raw material feeder 2 so that a deposition temperature of the product material is lower than a temperature detected by the temperature detector 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydrogen generator that reacts a metal hydride with water to generate hydrogen.

  In recent years, hydrogen energy has attracted attention as a clean alternative energy because of environmental problems such as global warming caused by carbon dioxide emissions and energy problems such as the depletion of petroleum resources. However, hydrogen gas has not yet been developed as a general infrastructure gas, and it is important to develop technology for safely storing, transporting and supplying hydrogen.

  There are several candidates for hydrogen storage methods. Among them, a hydrogen generator that uses metal hydride as a hydride capable of reversibly storing and releasing hydrogen and reacts with water to generate hydrogen. It has been known.

Known metal hydrides used in this type of conventional hydrogen generator include NaH, NaBH ₄ , NaAlH ₄ , LiALH ₄ , LiBH ₄ , LiH, CaH ₂ , AlH ₃ , MgH ₂ , and the like. For example, it is known that NaBH ₄ reacts with water to produce hydrogen and NaBO ₂ as a product by the hydrolysis reaction shown in (Chemical Formula 1).

従来のこの種の水素生成装置は、金属水素化物と水とを混合したものを、触媒が担持された反応器に供給して、水素を生成している。そして、生成された水素と、生成物と、反応に供されなかった水とは、混合物として反応器に接続された生成物流路を経て、分離器に供給され、水素は、分離器から排出されるように構成されている（例えば、特許文献１参照）。

In this type of conventional hydrogen generator, a mixture of a metal hydride and water is supplied to a reactor on which a catalyst is supported to generate hydrogen. The produced hydrogen, the product, and the water that has not been subjected to the reaction are supplied as a mixture to the separator through the product flow path connected to the reactor, and the hydrogen is discharged from the separator. (For example, refer patent document 1).

Japanese Patent No. 4792632

  However, in the conventional configuration, when the temperature of the product flow path connected to the reactor is lowered, the solubility of the product dissolved in water is lowered and the product may be precipitated. In that case, the product flow path is clogged by the precipitated product, and the product cannot be discharged from the reactor, and the operation of the hydrogen generator cannot be continued.

  An object of the present invention is to solve the conventional problems, and to provide a hydrogen generator that can be stably operated by suppressing clogging of a product flow path connected to a reactor with a deposited product. .

In order to solve the above-mentioned conventional problems, the hydrogen generator of the present invention includes a reactor for reacting a metal hydride and water to produce hydrogen and a product, and a raw material for supplying the metal hydride to the reactor. Temperature of at least one of the supply, the water supply for supplying water to the reactor, the product flow path for discharging the product and water produced in the reactor, and the reaction flow path A temperature detector for detecting the water supply, and the controller supplies water to the supply flow rate of the metal hydride by the raw material supplier so that the precipitation temperature of the product is lower than the temperature detected by the temperature detector. The ratio W / F of the water supply flow rate by the vessel is controlled.

  As a result, the amount of water that has not been subjected to the reaction is an amount that can dissolve all of the product, so that precipitation of the product dissolved in water in the product channel can be suppressed. It is possible to suppress clogging with the deposited product and to stably operate the hydrogen generator.

  The hydrogen generation apparatus of the present invention generates a product by controlling the ratio W / F of the water supply flow rate to the metal hydride supply flow rate so that the product precipitation temperature is lower than the temperature detected by the temperature detector. Precipitation of the product dissolved in water in the product channel can be suppressed, the product channel can be prevented from being clogged with the deposited product, and the hydrogen generator can be operated stably.

  Moreover, the maintenance which removes the clogging with a product can be made unnecessary.

Block diagram of the hydrogen generator in Embodiment 1 of the present invention The characteristic view which shows the relationship between the solubility of sodium metaborate of the hydrogen generator in Embodiment 1 of this invention, and temperature The characteristic view which shows the temperature and the relationship of W / F which the sodium metaborate of the hydrogen generator in Embodiment 1 of this invention precipitates

  A hydrogen generation apparatus according to a first aspect of the present invention includes a reactor for reacting a metal hydride and water to produce hydrogen and a product, a raw material supplier for supplying the metal hydride to the reactor, and a water supply for the reactor. A water supply for supplying the product, a product flow path for discharging the product and water generated in the reactor from the reactor, a temperature detector for detecting the temperature of at least one of the reactor and the product flow path, A ratio of the water supply flow rate of the water supply to the metal hydride supply flow rate of the raw material supplier so that the product precipitation temperature is lower than the temperature detected by the temperature detector. W / F is controlled.

  As a result, the amount of water that has not been subjected to the reaction is an amount that can dissolve all of the product, so that precipitation of the product dissolved in water in the product channel can be suppressed. It is possible to suppress clogging with the deposited product and to stably operate the hydrogen generator.

  According to a second aspect of the present invention, there is provided an operation method of a hydrogen generator, a reactor for reacting a metal hydride and water to produce hydrogen and a product, a raw material supplier for supplying the metal hydride to the reactor, A water supply for supplying water to the reactor, a product flow path for discharging the product and water produced in the reactor from the reactor, and temperature detection for detecting the temperature of at least one of the reactor and the product flow path And a water supply device with respect to the supply flow rate of the metal hydride by the raw material supply device so that the precipitation temperature of the product is lower than the temperature detected by the temperature detector. The ratio W / F of the water supply flow rate is adjusted.

  As a result, the amount of water that has not been subjected to the reaction is an amount that can dissolve all of the product, so that precipitation of the product dissolved in water in the product channel can be suppressed. It is possible to suppress clogging with the deposited product and to stably operate the hydrogen generator.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a block diagram of a hydrogen generator according to Embodiment 1 of the present invention.

As shown in FIG. 1, the hydrogen generator 100 of the present embodiment includes a raw material container 1 filled with sodium borohydride (NaBH ₄ ), which is a raw material metal hydride, and a borohydride in the raw material container 1. A raw material supplier 2 for supplying sodium to the reactor 5, a water container 3 filled with water, a water supplier 4 for supplying water from the water container 3 to the reactor 5, and the temperature of the reactor 5 are detected. A temperature detector 9 and a controller 50 are provided.

The reactor 5 is connected to a product flow path 6 for discharging the produced product sodium metaborate (NaBO ₂ ) and hydrogen. A product container 8 is connected to the product flow path 6. The hydrogen flowing through the product flow path 6 flows through the hydrogen flow path 7 branched from the product flow path 6 and is supplied to the external fuel cell 200.

  The fuel cell 200 generates electricity by electrochemical reaction from hydrogen supplied through the hydrogen flow path 7 and oxygen in the air. The controller 50 includes an MPU and a memory, has an arithmetic function and a storage function, stores various control programs, and controls various operations of the hydrogen generator 100.

  In the hydrogen generator 100 of the present embodiment configured as described above, the operation and action will be described below.

  The sodium borohydride filled in the raw material container 1 is supplied from the raw material supplier 2 to the reactor 5. The water filled in the water container 3 is supplied from the water supply device 4 to the reactor 5.

  In the reactor 5, sodium borohydride and water undergo the hydrolysis reaction shown in (Chemical Formula 2) to generate hydrogen and sodium metaborate.

生成した水素とメタホウ酸ナトリウムには、水供給器４から供給された水のうち反応に用いられなかった余剰の水（以下、残存水と記載する）も混在している。メタホウ酸ナトリウムは、残存水に溶解しており、メタホウ酸ナトリウム水溶液の状態となっている。

The generated hydrogen and sodium metaborate also contain excess water (hereinafter referred to as residual water) that was not used for the reaction among the water supplied from the water supplier 4. Sodium metaborate is dissolved in the remaining water and is in the form of an aqueous sodium metaborate solution.

  Hydrogen produced in the reactor 5 flows through the hydrogen flow path 7 and is supplied to the fuel cell 200. The aqueous sodium metaborate solution generated in the reactor 5 flows through the product flow path 6 and is stored in the product container 8.

  Further, the temperature of the reactor 5 is detected by a temperature detector 9. Further, W / is the weight ratio of the water supply flow rate to the supply flow rate of sodium borohydride, which is a metal hydride, so that the temperature detected by the temperature detector 9 becomes higher than the precipitation temperature of sodium metaborate. F is set to 15, and the raw material supplier 2 and the water supplier 4 are controlled.

  FIG. 2 is a characteristic diagram showing the relationship between the solubility of sodium metaborate and the temperature of the hydrogen generator 100 according to Embodiment 1 of the present invention.

As shown in FIG. 2, the lower the temperature, the lower the solubility of sodium metaborate in water,
Precipitation tends to occur. For example, when a 22% by weight aqueous sodium metaborate solution is 25 ° C. or lower, precipitation of sodium metaborate occurs.

  FIG. 3 is a characteristic diagram showing the relationship between the temperature at which sodium metaborate is deposited and W / F in the hydrogen generator 100 according to Embodiment 1 of the present invention.

  As shown in FIG. 3, the lower the temperature is, the higher the set lower limit value of W / F for suppressing the precipitation of sodium metaborate. This is because the higher the W / F, the lower the concentration of sodium metaborate in the aqueous sodium metaborate solution, and the lower the precipitation temperature of sodium metaborate.

  More specifically, W / F is 10 or more at 20 ° C., and W / F is 12 or more at 10 ° C., so that precipitation of sodium metaborate can be suppressed.

  In the present embodiment, the temperature of the reactor 5 detected by the temperature detector 9 is configured to be 30 ° C., and the set value of W / F is 15. At this time, the concentration of sodium metaborate in the aqueous solution of sodium metaborate is 14% by weight, the precipitation temperature is 0 ° C., and the precipitation temperature of sodium metaborate is lower than the temperature of 30 ° C. in the reactor 5. , Precipitation of sodium metaborate can be suppressed.

  As described above, in the present embodiment, the ratio W / F of the water supply flow rate to the metal hydride supply flow rate so that the temperature detected by the temperature detector 9 is higher than the precipitation temperature of sodium metaborate. By controlling the amount of water, the amount of water that has not been subjected to the reaction is an amount that can dissolve all of the sodium metaborate, so that the precipitation of sodium metaborate dissolved in water in the product flow path 6 can be suppressed. It is possible to suppress the clogging of the product channel 6 with the precipitated sodium metaborate, and to stably operate the hydrogen generator. Moreover, the maintenance which removes the clogging with sodium metaborate can be made unnecessary.

  In this embodiment, W / F is set to 15. However, based on the relationship between the concentration and solubility of sodium metaborate in the sodium metaborate aqueous solution, W / F is set to a temperature at which sodium metaborate does not precipitate. / F may be set, and wasteful water can be suppressed as W / F is set lower.

  Moreover, when the temperature of the reactor 5 detected by the temperature detector 9 changes during operation, the W / F may be changed so that the sodium metaborate does not precipitate.

  As described above, the hydrogen generator and the operation method thereof according to the present invention enable stable operation of the hydrogen generator by suppressing clogging of the product flow path connected to the reactor. The present invention can be applied to a hydrogen generator that reacts with water to generate hydrogen and a fuel cell system using the hydrogen generator.

DESCRIPTION OF SYMBOLS 1 Raw material container 2 Raw material supply device 3 Water container 4 Water supply device 5 Reactor 6 Product flow path 7 Hydrogen flow path 8 Product container 9 Temperature detector 50 Controller 100 Hydrogen generator 200 Fuel cell

Claims (2)

A reactor for reacting a metal hydride with water to produce hydrogen and a product;
A raw material supplier for supplying the metal hydride to the reactor;
A water supply for supplying water to the reactor;
A product flow path for discharging the product and water generated in the reactor from the reactor; a temperature detector for detecting a temperature of at least one of the reactor and the product flow path;
With a controller,
The controller controls the supply flow rate of the water by the water supply device with respect to the supply flow rate of the metal hydride by the raw material supply device so that the precipitation temperature of the product is lower than the temperature detected by the temperature detector. A hydrogen generator characterized by controlling the ratio W / F. A reactor for reacting a metal hydride with water to produce hydrogen and a product;
A raw material supplier for supplying the metal hydride to the reactor;
A water supply for supplying water to the reactor;
A product flow path for discharging the product and water produced in the reactor;
A temperature detector for detecting the temperature of at least one of the reactor and the product flow path;
A method of operating a hydrogen generator comprising:
The ratio W / F of the water supply flow rate by the water supply device to the metal hydride supply flow rate by the raw material supply device is set so that the precipitation temperature of the product is lower than the temperature detected by the temperature detector. The operation method of the hydrogen generator to be adjusted.

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