JP2010059503A - Method for starting water electrolysis apparatus, starter of the apparatus and the apparatus equipped with the starter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for starting a water electrolysis apparatus from which high-purity hydrogen gas and high-purity oxygen gas can be obtained with high efficiency and to provide a starter of the water electrolysis apparatus and the water electrolysis apparatus equipped with the starter. <P>SOLUTION: The method for starting the water electrolysis apparatus includes the steps of: detecting an amperage of an electric current flowing through a water electrolysis stack; increasing the amperage of the electric current flowing through the water electrolysis stack to the rated amperage by setting a voltage of the water electrolysis stack smaller than the upper limit voltage when the detected amperage is smaller than the rated amperage; and keeping the electric current flowing through the water electrolysis stack as it is when the voltage of the water electrolysis stack is not smaller than the upper limit. The starter of the water electrolysis apparatus is provided with: an electric current detecting means for measuring the amperage of the electric current flowing through the water electrolysis stack and comparing the measured amperage with the rated amperage; and a stack voltage detecting means for measuring the voltage of the water electrolysis stack and comparing the measured voltage with the upper limit voltage. The electric current is applied to the water electrolysis stack as far as the measured amperage becomes the rated amperage while keeping the measured voltage smaller than the upper limit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for starting a water electrolysis device, a start device for starting the water electrolysis device to a rated operating condition, and a water electrolysis device including the start device.

  A water electrolysis apparatus generally includes a solid polymer electrolyte membrane, electrolyzes circulating water to generate hydrogen gas and oxygen gas, a container for storing the circulating water, and circulates in the water electrolysis stack. A water supply pipe for supplying water, a supply pipe for supplying oxygen gas and hydrogen gas generated in the water electrolysis stack to the container together with circulating water, and a discharge section for discharging hydrogen gas and oxygen gas from the container, Heating means for heating the circulating water at the start-up and nitrogen gas supply means for supplying nitrogen gas into the circulating water at the start-up.

  When operating the water electrolyzer, if the rated current is passed while the circulating water temperature is low, the stack resistance is high under the low temperature condition, so the voltage in the water electrolysis stack (stack voltage) rises rapidly, An abnormality may occur in the electrolytic stack. In addition, the amount of heat generated in the stack increases, and an abnormality may occur in the water electrolysis stack due to a sudden temperature change. For this reason, the water electrolysis apparatus is normally operated at a rated operation by increasing the temperature of the water to about 80 ° C. while circulating the water in the water electrolysis apparatus and then applying a current to the water electrolysis stack.

  Conventionally, when starting a water electrolysis apparatus, a natural circulation is generated by supplying nitrogen gas into a feed pipe from a nitrogen gas supply means installed outside the water electrolysis apparatus, and a heating means is used. The circulating water was raised to the rated operating temperature.

In Patent Document 1, a heating medium and a refrigerant are selectively circulated between a downcomer pipe (water supply pipe) through which water from which hydrogen gas and oxygen gas have been removed circulates and a water electrolysis tank (water electrolysis stack). A water electrolysis apparatus provided with a heat exchanger capable of performing the above is disclosed. In the water electrolysis apparatus of Patent Document 1, when starting up, oxygen is supplied to an oxygen rising pipe (feed pipe) to naturally circulate water, and a heat medium is supplied to a heat exchanger to raise the temperature of the circulating water. Let After the temperature of the circulating water rises above the specified value, the supply of oxygen to the riser and the supply of the heating medium to the heat exchanger are stopped, and the water electrolysis device is rated.
Japanese Patent No. 2639457

  For example, when the operation and stop of the water electrolysis device are repeated, such as a power storage device combining a water electrolysis device and a fuel cell, once the water electrolysis device is stopped, the water circulation is stopped and the water in the device The temperature of the also decreases. In the start-up method in which the nitrogen gas is supplied and the heater is heated, nitrogen gas is supplied into the water electrolyzer every time the water electrolyzer is started, so that the purity of the generated hydrogen gas and oxygen gas is lowered. In order to store high-purity hydrogen gas and oxygen gas, it is necessary to perform system replacement with the generated gas for a certain time after the rated operation, and there is a problem in that the electrolytic efficiency is lowered. Moreover, the electric power for operating a heating means is required at the time of starting, and there existed a problem that energy efficiency fell.

  In the water electrolysis apparatus of Patent Document 1, by supplying oxygen to the oxygen riser and generating natural circulation, it is possible to prevent a decrease in purity of hydrogen gas and oxygen gas and a decrease in electrolysis efficiency. However, since it is necessary to flow the heating medium set to a temperature at which the circulating water can be heated up to the rated operating condition at the time of startup, the energy efficiency is low.

  The present invention provides a method for starting a water electrolysis apparatus, a starter for a water electrolysis apparatus, and a water electrolysis apparatus including the starter that can obtain highly pure hydrogen gas and oxygen gas with high efficiency.

  In order to solve the above-described problems, the present invention includes a step of detecting a current value flowing through the water electrolysis stack, and a voltage value of the water electrolysis stack is preset when the detected current value is smaller than a rated current value. Less than the upper limit voltage, the step of increasing the current flowing through the water electrolysis stack to a rated current value, and the current flowing through the water electrolysis stack when the voltage value of the water electrolysis stack is greater than or equal to the upper limit value. And a method for starting the water electrolysis apparatus.

  The start-up method of the water electrolysis apparatus of the present invention is a method of setting the upper limit value of the stack voltage and gradually increasing the current to the rated current value while monitoring the stack voltage and the current flowing through the water electrolysis stack. The present invention prevents the occurrence of an abnormality in the water electrolysis stack due to a rapid rise in the stack voltage, and performs water electrolysis from a low temperature. As a result, the water in the device is naturally circulated by the generated gas and the circulating water is heated by Joule heat generated by water electrolysis. Can be activated automatically. That is, it is not necessary to supply nitrogen gas and circulate water for generating water circulation, so that high-purity hydrogen gas and oxygen gas can be obtained with high efficiency, and energy efficiency can be improved.

  The present invention measures the current value flowing through the water electrolysis stack, compares the measured current value with the rated current value, measures the voltage value of the water electrolysis stack, and determines the measured voltage value. A stack voltage detecting means for comparing with a set voltage upper limit value, and setting the measured voltage as less than the upper limit value, and a water electrolyzer starting device for applying a current to the water electrolysis stack up to the rated current value provide. Moreover, a water electrolysis apparatus provided with the said starting device is provided.

  If the starter of the present invention is used, water electrolysis is performed from a low temperature while water is electrocirculated from the generated oxygen gas and hydrogen gas while preventing the occurrence of abnormalities in the water electrolysis stack due to a sudden rise in stack voltage. At the same time, the temperature of the circulating water can be raised using Joule heat generated by electrolysis in the starting process. Therefore, the water electrolysis apparatus of the present invention can simplify the water electrolysis apparatus because the nitrogen gas supply means and the circulating water heating means are unnecessary. Moreover, it is possible to produce highly pure hydrogen gas and oxygen gas with high efficiency.

  By using the water electrolysis apparatus start-up method and start-up apparatus of the present invention, it is possible to perform water electrolysis while preventing a rapid increase in stack voltage from a low temperature, so the water in the apparatus is circulated by the generated gas. The circulating water temperature can be raised using Joule heat at the time of water electrolysis, and the circulating water temperature and the rated current value at which rated operation can be performed automatically can be reached. According to the present invention, it is not necessary to supply nitrogen gas for starting and heating the circulating water by the heating means, so that the water electrolysis apparatus can be simplified, and high purity with high energy efficiency and electrolysis efficiency. It becomes possible to produce hydrogen gas and oxygen gas. The water electrolysis apparatus of the present invention is particularly advantageous when applied to a power storage apparatus that is repeatedly operated and stopped.

Below, embodiment of the starting method of the water electrolysis apparatus concerning the present invention is described.
The water electrolysis apparatus of the present embodiment includes a water electrolysis stack, an activation apparatus for activating the water electrolysis apparatus, a container for storing circulating water, a water supply pipe for supplying circulating water to the water electrolysis stack, A supply pipe that supplies oxygen gas and hydrogen gas generated in the water electrolysis stack to the container together with the circulating water, and a discharge unit that discharges the hydrogen gas and oxygen gas from the container. The activation device includes a computer, for example. Note that the water electrolysis apparatus of the present embodiment is not provided with a heating means and a nitrogen gas supply means such as a cylinder for heating the circulating water to the rated operating condition at the time of startup, such as a heater and a boiler.

  Next, a method for starting the water electrolysis apparatus of the present embodiment will be described with reference to FIG. FIG. 1 is a flowchart showing the operation of the activation device of the present embodiment.

The water electrolyzer before start-up is at a temperature lower than the circulating water temperature (about 80 ° C to 100 ° C) under rated operating conditions, for example, the water temperature in the device is room temperature, and there is no water circulation in the device. Is done. First, activation device, the current detecting unit measures a current value _{I real} flowing water electrolysis stack _and the current value of the rated operation conditions _{I real} (rated _current) is compared with _{I rated} (step S0).

I _real is smaller than _{I rated (I real <I rated} ) case, a power supply connected to the water electrolysis stack current is applied to the water electrolysis stack, increases the value of the current flowing through the water electrolysis stack (step S1 ). At this time, the value of the current applied to the water electrolysis stack is a value smaller than I _rated , a value that does not cause a rapid increase in stack voltage exceeding the upper limit and does not require a long time for startup. Is set as appropriate.

Activation device, the stack voltage detector measures a stack voltage _{V real,} the _{V real,} compared with the upper limit value _{V limit} of the stack voltage (step S2).

If V _real is lower than _{V limit,} activation device, the current detecting unit measures a current value _{I real} flowing water electrolysis _stack, compared with the rated current value _{I rated} the _{I real} (step S0). If I _real is less than _{I rated,} power current is applied to the water electrolysis stack, increasing the current flowing through the water electrolysis stack (step S1). _Thereafter, until _{V real =} V _{limit, or} until _{I real} ≧ _{I rated,} step S0~S2 are repeated. When _Ireal ≧ _Irated , the activation of the water electrolysis device is completed.

When _Vreal = _Vlimit , the value of the current flowing through the water electrolysis stack is maintained (step S3).

  In this embodiment, by applying a current to the water electrolysis stack, electrolysis of water is started even at a temperature below the rated operating condition, and hydrogen gas and oxygen gas are generated. The generated gas flows into the container through each supply pipe together with the circulating water. Since the density of the mixture of the generated gas and the circulating water in the feed pipe is smaller than the density of the circulating water in the water supply pipe, natural circulation occurs and pure water circulation is started. Moreover, circulating water is overheated by Joule heat generated by electrolysis.

As the circulating water is heated, the water electrolysis stack is heated by the circulating water. As the temperature of the water electrolysis stack rises, the stack voltage _Vreal decreases. The starting device measures V _real in the stack voltage detecting means and compares it with the upper limit value V _limit (step S4). If V _real = V _limit , the current is maintained (step S3). _Thereafter, until the _{V real <V limit,} step S3~S4 are repeated. That is, until the measured stack voltage becomes smaller than the upper limit value, the maintenance of the current and the monitoring of the stack voltage value and the current value flowing through the water electrolysis stack are repeated.

When V _real <V _limit is established, the activation device measures the current value I _real flowing through the water electrolysis stack in the current detection means, and compares I _real with the rated current value I _rated (step S0). For _{I real} <I _rated, the above steps S0~S4 are repeated. When _Ireal ≧ _Irated , the activation of the water electrolysis device is completed.

As described above, the water electrolysis apparatus start-up method and start-up apparatus of the present embodiment performs water electrolysis from a low temperature by applying current to the water electrolysis apparatus while managing the stack voltage and the current flowing through the water electrolysis apparatus. By doing so, natural circulation of the water in the apparatus is generated by the generated gas, and the circulating water is heated to the rated operating temperature using Joule heat during water electrolysis. As a result, the rated current value can be reached while preventing a rapid increase in the stack voltage at low temperatures.
Thus, energy efficiency is improved because it is not necessary to supply nitrogen gas at the time of startup or to heat the circulating water by the heating means. Moreover, high purity hydrogen gas and oxygen gas can be produced with high efficiency. Furthermore, since the nitrogen gas supply means and the heating means become unnecessary, the apparatus can be simplified.

It is the flowchart which showed operation | movement of the starting device of this invention.

Claims (3)

Detecting a current value flowing through the water electrolysis stack;
When the detected current value is smaller than the rated current value, setting the voltage value of the water electrolysis stack to less than a preset voltage upper limit value, and increasing the current flowing through the water electrolysis stack to the rated current value;
Maintaining the current flowing through the water electrolysis stack when the voltage value of the water electrolysis stack is equal to or greater than the upper limit value. A current detection means for measuring a current value flowing through the water electrolysis stack, and comparing the measured current value with a rated current value;
Stack voltage detection means for measuring the voltage value of the water electrolysis stack and comparing the measured voltage value with a set voltage upper limit value,
An apparatus for starting a water electrolysis apparatus that applies a current to the water electrolysis stack up to the rated current value by setting the measured voltage to be less than the upper limit value.   A water electrolysis device provided with the starting device according to claim 2.

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