JPS6119562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method for controlling the oxygen concentration of a mixed gas containing oxygen. More specifically, it relates to an oxygen concentration control device and control method that allows a single electrochemical oxygen separation device to have both deoxidation and oxygen generation functions, and that can be separated from the container whose oxygen concentration is to be controlled. . In biology, chemistry, medicine, metallurgy, and other research fields, it is often necessary to arbitrarily control the oxygen concentration in the gas phase. However, conventionally, nitrogen, argon,
The method used was to mix oxygen with a gas such as carbon dioxide or helium.
Cylinder operation and gas flow rate adjustment operations were complicated. In contrast, the inventors of the present application
In No. 28907, we proposed a method to automatically control oxygen concentration using electrochemical methods. That is, in an electrolytic cell in which a gas diffusion electrode effective for electrolytic reduction of oxygen is used as a cathode, an oxygen generation electrode is used as an anode, and an aqueous solution of potassium hydroxide, sodium hydroxide, or sulfuric acid, or a cation exchange membrane, etc. is used as an electrolyte or electrolyte, When a DC voltage is applied between the anode and anode while supplying a mixed gas containing oxygen to the cathode, O ₂ +2H ₂ O+4e ^- →4OH ^- (alkaline electrolyte) or O ₂ +4H ⁺ +4e ^- →2H at the cathode. Oxygen is selectively consumed by the reaction ₂ O (acidic electrolyte or cation exchange membrane), and at the anode 4OH ^- +O ₂ +2H ₂ O+4e ^- (alkaline electrolyte) or 2H ₂ O→O ₂ +4H ⁺ +4e ^- Oxygen is generated by the reaction (acidic electrolyte or cation exchange membrane). In other words, since only oxygen in the oxygen-containing mixed gas moves from the cathode side to the anode side, such an electrolytic cell functions as an oxygen separation device. Therefore, two such oxygen separation devices are prepared, and one of the cathodes is brought into contact with the gas in the oxygen concentration control chamber in which the oxygen concentration is to be controlled, and the oxygen generated from the anode is removed from the system. while supplying air to the other cathode,
Oxygen generated from the anode is supplied to the oxygen concentration control chamber, and if the oxygen concentration in the oxygen concentration control chamber is too high than a predetermined value, the former oxygen separation device having an oxygen removal function is activated. When the oxygen concentration is lowered and is too low than the predetermined oxygen concentration, the latter oxygen separation device having an oxygen concentration generation function is activated to increase the oxygen concentration, thereby bringing the oxygen concentration in the oxygen concentration control chamber to the predetermined level. can be controlled. In this way, the above-mentioned Japanese Patent Publication No. 57-28907 describes a method of controlling the oxygen concentration by separately preparing an oxygen separation device that uses the oxygen removal function and an oxygen separation device that uses the oxygen generation function. However, this method cannot be said to be very effective. On the other hand, in conventional oxygen concentration control devices, an electrochemical oxygen separation device and a chamber with a relatively large volume that is the target of oxygen concentration control are integrated, and an oxygen concentration meter is placed inside this chamber. It was normal for it to be installed. However, in reality, it is not always necessary to control the oxygen concentration throughout a large chamber, and in many cases a relatively small volume container is sufficient. In many cases, it is still necessary to conduct experiments with various oxygen concentrations, but it would take too much time to conduct such experiments in a single chamber. The present invention aims to eliminate such drawbacks, and provides a single electrochemical oxygen separation device with both deoxidizing and oxygen generating functions, and also integrates a container whose oxygen concentration is to be controlled and an electrochemical oxygen separator. The feature is that the oxygen concentration control device, which is mainly a separation device, is separate and independent. That is, the oxygen concentration control device of the present invention is composed of one electrochemical oxygen separation device, an oxygen concentration detection chamber housing an oxygen concentration meter, a control section, a deoxidizing gas line, and an oxygen supply line, When this oxygen concentration control device and an airtight container are connected, oxygen is generated from the anode when air is introduced into the deoxidizing gas circulation path or the cathode, which utilizes the deoxidizing reaction at the cathode of the electrochemical oxygen separation device. The oxygen concentration in the airtight container is controlled by appropriately selecting an oxygen supply line for supplying the oxygen to the airtight container. In addition, the oxygen concentration control device and the airtight container are connected by a removable gas socket, and after the oxygen concentration is controlled, the airtight container is separated from the oxygen concentration control device and placed in the chamber, which is a constant temperature room. It is now possible to put it in. Adopting this method is extremely convenient because a normal general-purpose constant temperature bath can be used. Furthermore, conventionally, the oxygen concentration meter was installed inside the chamber, but in the case of the present invention, it is installed on the oxygen concentration control device side, so the airtight container can be carried freely as described above. can. Furthermore, it is quite easy to set different oxygen concentrations for each airtight container. The airtight container used in the present invention must have a lid, but a container made of glass or acrylic resin is suitable in order to allow observation of the inside. As the electrolyte for an electrochemical oxygen separator, sulfuric acid or a cation exchange membrane, which is not affected by carbon dioxide gas, is suitable. As the cation exchange membrane, a hydrogen ion conductive membrane based on perfluorocarbon and having sulfonic acid groups or carboxylic acid groups introduced therein is suitable. When sulfuric acid is used as the electrolyte, a mixture of a platinum group metal catalyst supported on carbon and a fluororesin is bonded to an expanded metal made of titanium or tantalum plated with gold or platinum, and porous polyester is used as the cathode. An anode lined with a tetrafluoroethylene film is suitable, and an expanded titanium metal plate plated with platinum or coated with a composite oxide of platinum and iridium is suitable as the anode. When a cation exchange membrane is used as the electrolyte, a cathode and an anode are integrally bonded to the membrane. For the cathode, a mixture of a catalyst powder made of platinum black powder or an alloy powder of platinum and gold and a fluorine resin, or a mixture of cation exchange resin powder or short fibers mixed with this mixture is hot pressed onto an ion exchange membrane. It is better to do so. The anode is suitably hot-pressed using iridium oxide or platinum black powder as a catalyst in the same manner as the cathode, or electrolessly plated with platinum or rhodium. As the oxygen concentration meter, a galvanic cell type (fuel cell type) type, a polarographic type, or a zirconia type is used. The control unit of the oxygen concentration control device is an electric circuit consisting of a comparator, a sequence circuit, and a power supply.The comparator compares whether the detection signal from the oxygen concentration meter is higher or lower than a predetermined value, and It determines whether the oxygen separator is to operate as an oxygen scavenger or an oxygen generator, and a sequence circuit controls the opening and closing order of the valves as described below, as well as directing current from the power source to the electrochemical oxygen separator. is supplied and the pump is driven. The valves described below are preferably electromagnetic valves that are automatically controlled by a control unit, but may be manually operated in some cases. To maintain a relative humidity of 100% in an airtight container, you can store a container filled with water inside an airtight container. When using this oxygen concentration control device for culturing microorganisms or cells, by using a smooth buffer solution in the culture medium, the pH of the culture medium can be kept constant without having to particularly adjust the carbon dioxide concentration in the airtight container. Retained. An embodiment of the present invention will be described in detail below. Embodiment: FIG. 1 shows a system diagram of an oxygen concentration control system according to an embodiment of the present invention. The oxygen concentration control system is broadly divided into an oxygen concentration control device 1 and an airtight container 2. The oxygen concentration control device 1 is mainly an electrochemical oxygen separation device 3
It is composed of an oxygen concentration detection chamber 4, an electric circuit 5 for controlling the oxygen concentration, an outgoing gas line 6 , and an incoming gas line 7 . The electrochemical deoxidation separation device 3 includes a cation exchange membrane 8 in which sulfonic acid groups are introduced into perfluorocarbon, a cathode 9 made of a mixture of platinum black powder and polytetrafluoroethylene, and an iridium oxide powder and polytetrafluoroethylene. Anode 10 made of a mixture with ethylene, cathode current collector 11 made of platinized expanded titanium, anode current collector 12 made of platinized expanded titanium, cathode terminal plate 13 made of a titanium plate, titanium plate. It consists of an anode terminal plate 14, a cathode gas chamber 15, an anode water chamber 16, and a cell frame 17. The cathode 9 and the anode 10 are integrally joined to the cation exchange membrane 8. A water tank 18 is provided in the anode water chamber 16.
Water is supplied from the cation exchange membrane 8, and the cation exchange membrane 8 functions as a hydrogen ion conductor due to this water supply. A removable outward gas plug 19 and a return gas plug 20 are attached to the airtight container 2, and a removable outbound gas socket 21 is attached to the tip of the outbound gas line 6 of the oxygen concentration control device 1 . gas line
A return trip gas socket 22 is attached to the tip of the return trip gas plug 19 and an outward trip gas socket 21, and the return trip gas plug 20 is connected to the return trip gas socket 22.
and the return path gas socket 22 are connected.
By connecting the gas plug and the gas socket in this way, the oxygen concentration control device 1 and the airtight container 2 are brought into communication. When the gas plug and gas socket are separated, the gas plug becomes a kind of valve, and the airtight container 2
Airtightness is maintained. The oxygen concentration inside the airtight container 2 is determined by the oxygen concentration detection chamber 4.
The oxygen concentration meter 23 housed in the oxygen concentration meter 23 detects the oxygen concentration, and the signal is sent to the electric circuit section 5. If the oxygen concentration in the airtight container 2 is too high than the desired value, the electrochemical oxygen separator 3 acts as a deoxidizer. In this case, open the outgoing deoxygenation gas valve 24 and oxygen release valve 25 provided in the outgoing gas line 6 and the return deoxidation gas valve 26 provided in the incoming gas line 7 , and Close the outgoing oxygen supply valve 27 provided in the system line 6 , the deoxygenated residual air release valve 28, and the air introduction valve 29 provided in the return gas system line 7 ,
While driving the circulation pump 30, the cathode terminal plate 13
When a direct current is applied between the anode terminal plate 14 and the anode terminal plate 14, the gas in the airtight container 2 is supplied to the cathode gas chamber 15 via the return gas line 7 , where a deoxidation reaction occurs at the cathode 9, and the gas is deoxidized. Deoxygenation gas valve 2 for gas going out
Oxygen generated from the anode 10 during this deoxidation reaction is released from the oxygen release valve 25 to the outside of the system. The pressure reduction compensation valve 31 provided in the return gas line 7 is composed of a so-called relief valve or a liquid valve that uses a liquid with low vapor pressure such as propylene glycol, and when the pressure inside the system is reduced due to deoxidation, this valve This is to automatically introduce atmospheric air into the system to compensate for the reduced pressure. Note that the oxygen in the air introduced for this pressure reduction compensation is also removed by the electrochemical oxygen separation device 3 . By repeating such gas circulation and deoxidation operations, the oxygen concentration within the airtight container 2 is lowered to a desired value. On the other hand, if the oxygen concentration in the airtight container 2 is too low than the desired value, the electrochemical oxygen separation device 3
functions as an oxygen generator. In this case, open the outbound oxygen supply valve 27, deoxidized residual air release valve 28, and air introduction valve 29, close the outbound deoxygenation gas valve 24, oxygen release valve 25, and return deoxygenation gas valve 26, When the air introduction pump 32 is driven and a direct current is applied between the cathode terminal plate 13 and the anode terminal plate 14, air is supplied from outside the system to the cathode gas chamber 15 by the air introduction pump 32, and the anode 9 Electrolytic reduction of oxygen occurs, and the deoxygenated gas is released from the deoxygenated residual air release valve 28 to the outside of the system, and at the same time, the oxygen generated from the anode 10 passes through the outward oxygen supply valve 27 to the airtight container 2. is supplied to The gas expelled from the airtight container 2 by the supply of oxygen gas is discharged to the outside of the system via the oxygen concentration detection chamber 4 and the overpressure compensating valve 33 provided in the return gas line 7 . When the reading of the oxygen concentration meter 23 housed in the oxygen concentration detection chamber 4 reaches a desired value, the direct current is turned off. The various valves mentioned above, except for the pressure reduction compensation valve 31 and the overpressure compensation valve 33, are all solenoid valves, and are automatically and appropriately controlled by a sequence circuit built into the electric circuit section 5. Opening and closing are performed in accordance with the following order. The circulation pump 30 and the air introduction pump 32 are driven according to a certain sequence. After the oxygen concentration in the airtight container 2 reaches the desired value, disconnect the outbound gas plug 19 and outbound gas socket 21, and disconnect the inbound gas plug 2.
0 and the return gas socket 22 are separated. In this way, the airtight container 2 and the oxygen concentration control device 1 are separated. In order to keep the temperature of this airtight container 2 constant, it may be placed in a constant temperature room. The action area of the cathode 9 and anode 10 of the electrochemical oxygen separator 3 described above is 2 dm ² , and the airtight container 2
If the internal volume of the container 2 is 15 and there is air in the airtight container 2 at first, the oxygen concentration will increase to 10% and 30% in 20 minutes.
I was able to make it into %. In the above-described embodiment, the electrochemical deoxidation separation device 3 is composed of a single cell, but it may be composed of a plurality of cells. Moreover, the overpressure compensation valve 33 may be a solenoid valve, and this valve may be opened when the electrochemical oxygen separation device 3 is operated as an oxygen generator. Furthermore, the circulation pump 30 and the air introduction pump 32 are made into one pump,
It may be installed at the position of the circulation pump 30. In this case, the air introduction valve 29 will also be adjacent to the circulation pump 30. As described in detail above, the present invention provides a single electrochemical oxygen separation device with a deoxidizing function and an oxygen generating function, thereby making it possible to control the oxygen concentration more efficiently. This invention provides an oxygen concentration control device and a method for controlling oxygen concentration that can be separated and independent from the container to be controlled, and has extremely high industrial value.

[Brief explanation of the drawing]

FIG. 1 shows a system diagram of an oxygen concentration control system according to an embodiment of the present invention. 1 ...Oxygen concentration control device, 2...Airtight container, 3
...Electrochemical oxygen separation device, 4...Oxygen concentration detector, 5...Electric circuit section, 6 ...Outgoing gas system line,
7 ...Return gas line, 8...Cation exchange membrane, 9
... cathode, 10 ... anode, 11 ... cathode current collector,
12... Anode current collector, 13... Cathode terminal plate, 14
... Anode terminal plate, 15 ... Cathode gas chamber, 16 ...
Anode water chamber, 17...Cell frame, 18...Water tank, 19...Gas plug for outbound trip, 20...Gas plug for return trip, 21...Gas socket for outbound trip, 2
2...Gas socket for return trip, 23...Oxygen concentration meter, 24...Oxygen gas valve for outward trip, 25...Oxygen release valve, 26...Deoxidation gas valve for return trip, 27...Oxygen supply valve for outward trip, 28 ... Deoxidized residual air release valve, 29 ... Air introduction valve, 30 ... Circulation pump,
31... pressure reduction compensation valve, 32... air introduction pump,
33... Overpressure compensation valve.

Claims (1)

[Scope of Claims] 1. Electrochemical oxygen separation comprising a cathode consisting of a gas diffusion electrode effective for selective electrolytic reduction of oxygen, an anode consisting of an oxygen generating electrode, and an electrolyte, and having an oxygen deoxidizing function and an oxygen generating function. It consists of an oxygen concentration detection chamber that houses the device and oxygen concentration meter, an electric circuit section for controlling the oxygen concentration, an outgoing gas line, and an incoming gas line, and an outgoing gas socket is installed at the tip of the outgoing gas line. The outgoing gas system path is branched into an outgoing deoxidizing gas system path and an outgoing oxygen generating system path, and an outgoing deoxidizing gas valve and a deoxygenated residual air release valve are installed in the outgoing deoxidizing gas system path. In addition to installing an oxygen supply valve and an oxygen release valve in the oxygen generating system for the outward journey, a gas socket for the return journey is installed at the tip of the gas system for the return journey, and an oxygen concentration detection chamber and an overpressure valve are installed in the gas system for the return journey. An oxygen concentration control device comprising a compensation valve, a return deoxygenation gas valve, a circulation pump, a pressure reduction compensation valve, an air introduction pump, and an air introduction valve. 2. An electrochemical oxygen separator and an oxygen concentration meter, which are composed of a cathode consisting of a gas diffusion electrode effective for selective electrolytic reduction of oxygen, an anode consisting of an oxygen generation electrode, and an electrolyte, and have an oxygen removal function and an oxygen generation function. It consists of an oxygen concentration detection chamber to be housed, an electric circuit section for controlling the oxygen concentration, an outgoing gas system line, and an incoming gas system line.The outgoing gas socket is attached to the tip of the outgoing gas system line, and the outgoing gas system The route is branched into an outbound deoxygenation gas system route and an outbound oxygen generation system route, and an outbound deoxygenation gas valve and a deoxidized residual air release valve are provided in the outbound deoxygenation gas system route, and the outbound oxygen generation An outbound oxygen supply valve and an oxygen release valve are installed in the system, and a return gas socket is installed at the tip of the return gas line, and an oxygen concentration detection chamber, an overpressure compensation valve, and a return oxygen deoxidation valve are installed in the return gas line. The outgoing gas socket and the incoming gas socket of an oxygen concentration control device comprising a gas valve, a circulation pump, a pressure reduction compensation valve, an air introduction pump, and an air introduction valve are used as an outgoing gas plug of an airtight container whose oxygen concentration is to be controlled. If the oxygen concentration in the airtight container is too high than the desired value, open the outbound deoxygenation gas valve, oxygen release valve, and return deoxygenation gas valve to release the remaining deoxygenated gas. By closing the discharge valve, outbound oxygen supply valve, and air introduction valve, and driving the circulation pump, a direct current is applied to the electrochemical oxygen separator from the electric circuit for controlling the oxygen concentration. When the deoxygenated gas is circulated in the airtight container and the oxygen concentration in the airtight container is too low than a desired value, an outgoing oxygen supply valve,
Open the deoxygenated residual air release valve and air intake valve,
Close the outbound deoxygenation gas valve, oxygen release valve, and return deoxygenation gas valve, and while driving the air introduction pump, direct current is applied from the electric circuit for controlling oxygen concentration to the electrochemical deoxygenation and separation device. By energizing, oxygen is supplied to the container, and the gas expelled from the airtight container via the return gas plug is discharged to the outside of the system via the overpressure compensating valve. A method for controlling oxygen concentration, comprising controlling the oxygen concentration, and then separating the outgoing gas socket and the outgoing gas plug, and the incoming gas socket and the incoming gas plug, respectively.