JPS59112247A - Apparatus for generating hydrated standard gas - Google Patents

Abstract

PURPOSE:To obtain a hydrated standard gas of known water concn. in a relatively simple procedure and with high precision by using an apparatus of relatively simple structure by generating water by allowing to react hydrogen and oxygen produced from a water electrolytic cell. CONSTITUTION:Gaseous nitrogen from a gaseous nitrogen bomb 1 is passed to a drying part 3 through a stop valve 2 and is set to <=0.1ppm water concn. Next, the gaseous nitrogen is controlled to a prescribed pressure by a pressure control valve 4 and a pressure gauge 5, the flow rate is controlled by a flow rate control valve 6 and a flow meter 7 and sent to a gaseous hydrogen oxygen reaction pipe 8 and passed therethrough. ON the other hand, gaseous hydrogen from the negative pole and gaseous oxygen from the positive pole of the electrolytic cell 12 and set to <=0.1ppm water concn. through drying parts 13, 14, are joined and sent to a pipe connecting the pipe 8 and a flow meter 11. The obtained mixed gas is sent to the pipe 8, heated to about 350 deg.C by a heating furnace 10 having a temp. controller 9, allowed to react to form water, and the hydrated standard gas diluted by the gaseous nitrogen is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is capable of producing a moisture standard gas containing desired moisture by mixing hydrogen gas and oxygen gas of known concentration at a fixed flow rate ratio and then reacting to convert the mixture into moisture. Regarding the generation device, a supply line for hydrogen generated from a water electrolyzer, a supply line for oxygen generated from a water electrolyzer that is the same as or different from this hydrogen generation source, or from another oxygen generation source;
The present invention also relates to a moisture standard gas generator having a configuration in which all of the cine active gas supply channels are merged into a conduit leading to a hydrogen/oxygen gas reaction section, if desired.

The biggest problem with moisture meters for measuring moisture in gas samples is that they are difficult to calibrate.

Conventionally, as a method of performing the above-mentioned calibration, there is a method of performing the calibration using a calibration device compliant with the US NBS law. However, this method has two drawbacks: 1) The device is bulky and complicated to operate, so the user cannot calibrate it (the device manufacturer takes over and performs the calibration);
2) Since it is based on the amount of water vapor generated from a constant temperature water tank, there are problems such as low reliability, especially on the high dew point side.

In addition to this, there is also a vermeation tube type calibration device that utilizes the membrane permeability of water (for example, the Moisture Generator manufactured by DuPont in the United States), but this is only a secondary standard, so The problem is that sometimes it is necessary to calibrate with a primary reference.

The reason why a moisture meter cannot be easily calibrated as described above is because a moisture standard gas with a known moisture concentration is not easily available. Other gas analyzers, such as carbon dioxide gas meters and sulfur dioxide gas meters, do not have this problem because standard gases are easily available.

The present invention has been made under such circumstances, and includes an inert gas supply section, optionally a cine active gas drying section,
The inert gas flow rate control section and the hydrogen/oxygen gas reaction section are connected in this order by a conduit; furthermore, the hydrogen generation section of the water electrolyzer and the optional hydrogen drying section are connected in this order by a conduit. An oxygen gas supply path formed by connecting the hydrogen gas supply path formed by the inert gas flow rate control section and the oxygen generating section of the electrolyzer and the oxygen drying section (if desired) in this order with a conduit is connected to the hydrogen/oxygen gas flow control section and The present invention provides a moisture standard gas generator which is connected to a conduit connected to a gas reaction section.

The apparatus of this invention connects an inert gas supply section, optionally a cine active gas drying section, an inert gas flow rate control section, and a hydrogen/oxygen gas reaction section in this order with a conduit, and further connects a water electrolyzer to a water electrolysis tank. It is characterized by a configuration in which a hydrogen supply path from the same water electrolyzer and an oxygen supply path from the same water electrolyzer are merged into the conduit between the inert gas flow rate control section and the hydrogen/oxygen gas reaction section. It is something to do.

As the inert gas supply section used in the apparatus of this invention, a cylinder of high purity nitrogen gas, helium, argon, etc. with a capacity of about 99 or more (the following gas concentrations are all 96 in capacity) is used. The moisture content of the standard gas is selected depending on the moisture concentration of the standard gas and its required accuracy. Note that this selection also applies to each gas cylinder described later. Further, an inert gas drying section may be used as desired, and whether or not to install it is appropriately determined depending on the moisture concentration of the target moisture standard gas and the required accuracy. Note that this also applies to each gas source described later.

As the drying section, a cylindrical container made of metal, glass, etc., filled with a desiccant such as Molecular Sieve 3A (manufactured by Linde) is used. The inert gas flow rate control section may be of a commonly used type, such as one in which a pressure regulating valve, a pressure gauge, a flow rate control valve, and a flow meter are connected in this order through a conduit. In addition to this, a highly accurate flow rate control device such as a capillary flow ratio mixing method or a mass flow rate control method may be used.

The water electrolysis tank of the apparatus of this invention is of a closed type, and the electrolyte is a 20% aqueous solution of sodium hydroxide or potassium hydroxide, and the positive electrode is nickel.
Those using platinum or iron for the negative electrode are used. Further, the drying section which is optionally provided in each supply path of hydrogen gas and oxygen gas from the water electrolysis tank is similar to the above-mentioned inert gas drying section.

In addition, the hydrogen/oxygen gas reaction section of the device of this invention includes:
For example, a reaction tube made of quartz glass, ceramic, heat-resistant metal, etc., filled with an oxidation catalyst such as platinum or copper oxide, and a heating furnace equipped with a temperature controller to heat the reaction tube can be mentioned. The reaction is usually carried out at 300-400°C.

Next, the apparatus of this invention will be explained with reference to the drawings. FIG. 1 is an explanatory diagram of the configuration of an embodiment of the apparatus of the present invention.

With this device a moisture standard gas diluted with an inert gas is obtained.

The nitrogen gas generated from the nitrogen gas cylinder (1) is
It is passed through the drying section (3) (glass drying column filled with molecular sieve 3A) through the Tsufuha tv7' (2), and the water concentration is reduced to i0. 1 ppm or less. Next, the pressure is controlled to a constant pressure using the pressure regulating valve (Rito pressure gauge (5)), and the flow rate control valve (
6) and a flow meter (7) to control the flow rate to the desired flow rate,
The gas is sent to and passed through a hydrogen/oxygen gas reaction tube (8) in which a quartz glass tube is filled with a platinum catalyst. On the other hand, water electrolysis tank (1
Oxygen gas generated from the negative electrode of the hydrogen i, z, g and water electrolyzer (12) is transferred to the respective drying sections (13) (Y4) (the nitrogen gas The hydrogen/oxygen gas is sent to the conduit connecting the hydrogen/oxygen gas reaction tube (8) and the flow meter (11) with a water concentration of less than 0.1 ppm. The thus obtained mixed gas of hydrogen gas, oxygen gas, and nitrogen gas is sent to a reaction tube (8) made of a quartz glass tube filled with a platinum catalyst, and is sent to a heating furnace (1o) equipped with a temperature controller (9). ) is heated to approximately 350°C. As a result, hydrogen gas and oxygen gas react to form water), and a moisture standard gas diluted with nitrogen gas is obtained.

When water is electrolyzed, it is decomposed into hydrogen and oxygen, and the current efficiency at this time is almost 100%, and the purity of the hydrogen and oxygen obtained is also extremely high, with hydrogen being 99.5 to 99.7%.
%, oxygen is 99.0-99.5%. Furthermore, according to Faraday's law of electrolysis, 1 gram equivalent of a substance is generated with an amount of electricity of 96.485 coulombs: 26.801 Ah. Therefore, by controlling the electrolysis current, it is possible to generate arbitrary amounts of hydrogen and oxygen, and by measuring the entire electrolysis current, the amount of hydrogen and oxygen generated can be easily determined. The molar ratio of hydrogen and oxygen obtained by electrolytic generation is equal to the molar ratio required to produce water in an oxidation reaction, so there is no need to add additional oxygen, but if even a small amount of hydrogen remains, it is inconvenient to dilute. Just add a small amount of oxygen to the gas.

According to the apparatus of this example, a moisture standard gas of 1.400 ppm can be obtained under the conditions of an electrolytic current of 100 mA and a dilution gas (nitrogen gas) flow rate of 500 ml/rrAn. In addition, according to this device, hydrogen and oxygen are obtained in a water electrolyzer, so there is no need for other supply sources such as cylinders for hydrogen and oxygen. is obtained.

Furthermore, from another point of view, the present invention provides a hydrogen gas supply line formed by connecting a hydrogen generating part of a water electrolyzer, optionally a hydrogen drying part, and a stop valve in this order with a conduit: and another water electrolyzer. An oxygen gas supply line that connects the oxygen generation section of the tank, the desired oxygen purification section, the oxygen drying section, and the stop valve in this order with a conduit! Alternatively, an oxygen gas supply path is formed by connecting a purified air supply device, a supply section for oxygen gas or a mixed gas of oxygen gas and an inert gas, a gas drying section if desired, and a flow rate control section in this order through a conduit. The present invention provides a moisture standard gas generating device in which the gas is merged into a conduit leading to a hydrogen/oxygen gas reaction section.

The device of this invention has a hydrogen supply path from a water electrolyzer and an oxygen supply path from another water electrolyzer, or only oxygen gas or a mixed gas of oxygen gas and inert gas. It is characterized by a configuration in which the supply path merges with a conduit leading to the hydrogen/oxygen gas reaction section.

As the water electrolyzer for the apparatus of this invention, the same one as described above is used. A drying section similar to the above-mentioned drying section is used as the drying section which is optionally provided in the hydrogen gas supply path and the oxygen gas supply path from the water electrolysis tank. In addition, the acidic part installed in this oxygen gas supply path as required is used when it is necessary to completely remove trace amounts of hydrogen from the oxygen gas, such as a column packed with copper oxide equipped with a heater. .

Further, as the purified air supply device for the oxygen gas supply path of the apparatus of the present invention, a commonly used device for purifying air by pressurizing it with a compressor can be mentioned. As the oxygen gas supply section, an oxygen cylinder having a high purity of about 99% or more can be used. As the supply unit for the mixed gas of oxygen gas and inert gas, for example, since the inert gas is nitrogen gas, helium, or argon, a cylinder in which the concentration of oxygen gas in the inert gas is 10 ppm to 30% is used. If a drying section is required, one similar to the one for the hydrogen gas supply path described above is used. The flow rate control section for this oxygen gas supply path is similar to the one described above.

Further, the hydrogen/oxygen gas reaction section of the apparatus of the present invention may be similar to those described above.

Next, the above-mentioned apparatus of the present invention will be explained with reference to the drawings.

FIG. 2 is an explanatory diagram of the configuration of one embodiment of the apparatus of the present invention. This device provides a moisture standard gas diluted with oxygen.

Hydrogen gas generated from the negative electrode of the water electrolyzer (21) is passed through a drying section (22) (similar to the above embodiment) to reduce the water concentration to below 'io, lppm. In addition, hydrogen is removed by passing the oxygen gas generated from the positive electrode of another water electrolyzer (23), and the water concentration is reduced to 'tO-1pp.
m or less. In each electrolytic cell, the electrolytic current is adjusted so that oxygen is generated in excess of hydrogen. Each gas is then combined via a respective stop valve (26) (27)'. The thus obtained mixed gas of hydrogen and excess oxygen is sent to a quartz glass reaction tube (28) filled with a platinum catalyst and heated to approximately 350°C with a heater equipped with a temperature controller (29). be done. As a result, hydrogen and oxygen react to form water, yielding a moisture standard gas diluted with excess oxygen.

According to this device, since hydrogen gas and oxygen gas are both generated from a water electrolyzer, there is no need for other gas supply sources such as cylinders. Moreover, a moisture standard gas of any concentration can be easily obtained by simply controlling the electrolytic current.

According to the apparatus of this embodiment, the hydrogen generation electrolytic current is 100
mA, under the condition of oxygen generation electrolytic current 10A, 1.98%
of water standard gas f 35 m//min can be generated.

FIG. 3 is an explanatory diagram of the configuration of another embodiment of the apparatus of the present invention. In this device, when oxygen gas is used as the oxygen supply source, a moisture standard gas diluted with oxygen gas is obtained, and when a mixed gas of oxygen gas and inert gas is used as the oxygen supply source, this mixed gas or A moisture standard gas diluted with inert gas is obtained.

Hydrogen gas generated from the negative electrode of the water electrolyzer (41) is passed through a drying section (42) (similar to that of the previous embodiment) to reduce the water concentration i0. Stone 7” as lppm or less
Pass through valve (43)'. On the other hand, an oxygen gas cylinder (
An excess amount of oxygen gas relative to the above hydrogen generated from the fourth stage is passed through a stop pulp (through the fourth stage, drying section C46) (same as above) to reduce the water concentration to 0.1 ppm or less. Next, this oxygen gas is passed through a pressure regulating valve (47) and a pressure gauge (
48) to maintain a constant pressure, and the flow rate control valve (49) and flow meter (5) to control the flow rate to a desired flow rate.The hydrogen gas and oxygen gas obtained in this way are combined and mixed. The gas is sent to a hydrogen/oxygen gas reaction tube (51) (same as the reaction tube described above) and heated to approximately 350'C in a heating furnace (53) with a temperature controller (52).As a result, hydrogen and oxygen react. water and a moisture standard gas diluted with excess oxygen is obtained.

If a mixed gas cylinder of oxygen gas and an inert gas such as nitrogen gas, helium, or argon is used instead of the oxygen gas cylinder (44), the moisture standard gas diluted with the mixed gas or the inert gas can be used. can get.

According to this device, since the hydrogen source is a water electrolyzer, no other hydrogen supply source such as a cylinder is required, and a moisture standard gas with any moisture concentration can be obtained with easy operation.

Regarding the apparatus of the present invention described in detail above, it is preferable to control the flow rate when mixing each gas by mass flow rate rather than volumetric flow rate, but there is no problem in practical use if the flow rate is controlled by volumetric flow rate. When using a volumetric flow rate, the mass flow rate may change as the temperature or pressure changes, but the hydrogen source, oxygen source, and inert gas (diluent gas) source all undergo similar changes. , there is almost no change in the relative flow rate ratio, and the mixing ratio remains constant.

Furthermore, in the apparatus of the present invention, a reaction is carried out in which 1 mole of water is generated from 17 μm of hydrogen and 2 moles of oxygen, so the amount of oxygen used is more than twice the amount of hydrogen. By doing so, there is no problem even if the oxygen of interest is contained in the moisture standard gas. Conversely, a gas with a known water concentration can also be obtained when hydrogen is reacted with excess hydrogen and hydrogen remains. Since the presence of hydrogen may be undesirable depending on the use of the moisture standard gas, it is desirable to perform an equivalent reaction of hydrogen and oxygen or a reaction in an excess state of oxygen.

Furthermore, the apparatus of the present invention is capable of producing any moisture standard gas from a low concentration of several ppm to a high concentration; however, when producing a moisture standard gas of 4% or more, the lower explosive limit of hydrogen is 4.69.
d, safety devices are installed, such as installing a safety circuit to prevent the temperature from rising above the ignition point, or cutting off the circuit if the hydrogen concentration exceeds a certain value.

As described above in detail, the moisture standard gas generator of the present invention has the following advantages.

(1) The device has a relatively simple structure, and a moisture standard gas with a known moisture concentration can be obtained with high accuracy through simple operations.

(2) Since water is generated by reacting hydrogen gas and oxygen gas mixed at a constant flow rate ratio, the reaction is 100% as expected in theory, and a moisture standard gas with a calculated moisture concentration can be obtained.
The following criteria can be used.

(3) Moisture standard gas with a wide range of moisture concentrations from low to high concentrations can be obtained.

(4) A cylinder is not required as a hydrogen gas supply source, and a cylinder is not required as an oxygen gas supply source, except in the case where the target moisture standard gas is diluted with an inert gas.

In addition to being used as a gas adjustment device for calibrating a moisture meter as mentioned above, this moisture standard gas generator can also be used as: a) a moisture generator for tests to clarify the oxidation-reduction mechanism of steel;
b) It is used as a moisture supply source for an annealing furnace, and C) It is used as a moisture supply source for various tests and industrial applications that require moisture management, such as for preventing food from drying out.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams of the construction of an embodiment of the moisture standard gas generator of the present invention. (1)...Inert gas cylinder, (2), (26),
(27). (43), (45)...stop valve, (6), (
49)...Flow control valve, <3), (13), (1
4), (22), (25), (42), (46
)...Gas drying section, (24)...Oxygen purification section, (4
), (47)...pressure regulating valve, (5), (4B)...
・Pressure gauge, (7), (11). (31), (50), (54)...flow meter, (1
2), (21), (23). (41)...Water electrolysis tank, (15), (32)
, (33), (55)...Power supply for water electrolyzer, (8), (2B), (51) Mountain hydrogen/oxygen gas reaction tube, (10), (30), (53) ... Heating furnace, <9), (29), (52) ... Temperature regulator of heating furnace. one

Claims (1)

[Claims] 1゜Inert gas supply section, optional cine active gas drying section,
Do not connect the inert gas flow rate control section and the hydrogen/oxygen gas reaction section with a conduit in this order; furthermore, connect the hydrogen generation section of the water electrolyzer and the hydrogen drying section if desired with a conduit in this order. A hydrogen gas supply path formed by connecting the oxygen generating section of the electrolyzer and an optional oxygen drying section in this order with a conduit is connected to the inert gas flow rate control section and the hydrogen gas supply path. A moisture standard gas generator that is connected to the conduit between the oxygen gas reaction section and the oxygen gas reaction section. 2. A hydrogen gas supply line formed by connecting a hydrogen generating part of a water electrolyzer, an optional hydrogen drying part, and a stop valve in this order with a conduit; and an oxygen generating part of another water electrolyzer; and an oxygen gas supply line connecting the oxygen purification section, oxygen drying section, and stop pulp in this order with a conduit, or a purified air supply device, or an oxygen gas supply line for oxygen gas or a mixed gas of oxygen gas and an inert gas. A moisture standard gas generator in which an oxygen gas supply path is formed by connecting a supply section, optionally a gas drying section, and a flow rate control section in this order via a conduit, and merges into a conduit leading to a hydrogen/oxygen gas reaction section.