JP2008150259A - Oxygen pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxygen pump in which stress is not imposed on a solid electrolyte cylindrical body arranged along the vertical direction and which has excellent durability. <P>SOLUTION: The oxygen pump is provided with: the solid electrolyte cylindrical body 30 having oxygen ion conductivity; electrodes to be arranged on the inside and outside surfaces of the solid electrolyte cylindrical body 30; and a heating means 31 for heating the solid electrolyte cylindrical body. Each of both ends of the solid electrolyte cylindrical body 30 is attached to a fixing side via flexible connectors 55 and 56. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an oxygen pump.

  Conventionally, a method for producing a single crystal sample or the like using an atmospheric gas whose oxygen partial pressure is controlled by an oxygen partial pressure control device having an electrochemical oxygen pump containing a solid electrolyte is known (Patent Document). 1).

  The oxygen partial pressure control apparatus shown in FIG. 3 includes a mass flow controller (MFC) 3 that controls the flow rate of the inert gas that has passed through the valve 2 to a set value, and the inert gas that has passed through the mass flow controller 3 as a target oxygen component. The oxygen oxygen for supply gas supplied to the next process (apparatus) such as a sample growing apparatus by monitoring the oxygen partial pressure of the inert gas controlled by the oxygen pump 4 and the inert gas controlled by the oxygen pump 4 It has a sensor 5.

Further, this apparatus compares the monitored value by the oxygen sensor 5 with the set value by the oxygen partial pressure setting unit 6 and the inertness sent out from the oxygen pump 4 to set a desired oxygen partial pressure value. An oxygen partial pressure control unit 7 that controls the oxygen partial pressure of the gas to a predetermined value and an oxygen partial pressure display unit 8 that displays a monitor value by the oxygen sensor 5 are provided. Normally, the oxygen partial pressure in the inert gas is about 10 ⁻⁴ atm.

As shown in FIG. 4, the electrochemical oxygen pump 4 has electrodes 4b and 4c made of platinum formed on both inner and outer surfaces of a solid electrolyte cylindrical body 4a having oxygen ion conductivity. The solid electrolyte cylindrical body 4a is, for example, a zirconia solid electrolyte, and is heated to about 600 ° C. by a heater (not shown). An inert gas is supplied in the axial direction from one opening of the solid electrolyte cylindrical body 4a toward the other opening. The inert gas is, for example, Ar + O ₂ (10 ⁻⁴ atm). A DC voltage of a DC power source E is applied between the inner and outer electrodes 4b and 4c. When a positive electrode is applied to the outer electrode 4c and a negative electrode is applied to the inner electrode 4b to flow a current I, oxygen molecules (O ₂ ) in the inert gas flowing through the solid electrolyte cylindrical body 4a are electrically charged. It is reduced to ions (O ²⁻ ) and released again as oxygen molecules (O ₂ ) through the solid electrolyte to the outside of the solid electrolyte cylindrical body 4a. Oxygen molecules released to the outside of the solid electrolyte cylindrical body 4a are exhausted together with an auxiliary gas such as air. The inert gas of Ar + O ₂ (10 ⁻⁴ atm) supplied to the solid electrolyte cylindrical body 4a becomes a processed gas (purified gas) that is controlled to a target oxygen partial pressure by reducing oxygen molecules, and is the next step. (Device).

In addition, the oxygen pump 4 of FIG. 4 can also perform a pump operation by applying a DC voltage having the opposite polarity between the electrodes 4b and 4c on the inner and outer surfaces of the solid electrolyte cylindrical body 4a. That is, when a negative electrode is applied to the outer electrode 4c and a positive electrode is applied to the inner electrode 4b, oxygen molecules (O ₂ ) in a gas such as air flowing along the outer surface of the solid electrolyte cylindrical body 4a are electrically It is reduced to ions (O ²⁻ ) and is released again as oxygen molecules (O ₂ ) through the solid electrolyte into the solid electrolyte cylindrical body 4a. In this case, the oxygen partial pressure of the inert gas flowing inside the solid electrolyte cylindrical body 4a is increased and fed to the outside.

If a gas whose oxygen partial pressure is controlled by such an oxygen pump is supplied, crystal growth, alloying, heat treatment, semiconductor manufacturing process, etc. can be performed in an atmosphere such as an inert gas whose oxygen partial pressure is controlled.
JP 2002-326887 A

  In the oxygen pump shown in FIG. 4, one circular pipe-shaped solid electrolyte cylindrical body is used. That is, the gas to be treated is caused to flow in the axial direction in the internal space of the single solid electrolyte cylindrical body, and the ionic conductivity is pumped inside and outside the solid electrolyte partition wall while flowing through the solid electrolyte cylindrical body.

The solid electrolyte cylindrical body is used after being heated to 500 ° C. or higher in order to keep oxygen ion conduction at an appropriate value. The thermal expansion coefficient of the solid electrolyte material is, for example, about 10 × 10 ^{−6 in} zirconia, which is larger than that of a general ceramic material. For this reason, when a solid electrolyte cylindrical body having a length of 500 mm is heated in order to obtain gas purification performance, the end portion is displaced by more than 0.2 mm in calculation. However, the pipe end portion is actually fixed to the branch pipe or the like in an airtight structure, and thermal stress is generated. If such stress occurs, the solid electrolyte cylindrical body is damaged, and the life of the solid electrolyte cylindrical body is shortened. The magnitude of this stress is affected by the heating temperature, thermal expansion coefficient and length of the solid electrolyte cylindrical body. However, the heating temperature and the coefficient of thermal expansion are determined by the material of the solid electrolyte cylindrical body, and the longer the length, the greater the stress. However, the longer one is advantageous in view of efficient use of the solid electrolyte cylindrical body. Usually long ones are used. Therefore, in order to release the stress, it is conceivable to hold the solid electrolyte cylindrical body with a degree of freedom in the axial direction.

  On the other hand, if the solid electrolyte cylindrical body is allowed to expand and contract in the axial direction, a part of the solid electrolyte and a part of the electrode may be peeled off. If a part of the solid electrolyte or the like is peeled off, a part of the peeled off is mixed into the purified gas (treated gas), and the quality of the gas supplied to the sample preparation chamber or the like is lowered. Further, there may be a problem in the gas flow in the circulation path of the oxygen partial pressure control device.

  In view of the above problems, the present invention provides an oxygen pump excellent in durability without applying stress to a solid electrolyte cylindrical body.

  The oxygen pump of the present invention includes a solid electrolyte cylindrical body having oxygen ion conductivity, electrodes disposed on the inner surface and the outer surface of the solid electrolyte cylindrical body, and heating means for heating the solid electrolyte cylindrical body. In the oxygen pump, both ends of the solid electrolyte cylindrical body are respectively attached to the fixed side via flexible coupling bodies.

  According to the oxygen pump of the present invention, since both ends of the solid electrolyte cylindrical body are respectively attached to the fixed side via the flexible coupling body, the solid electrolyte cylindrical body is allowed to expand and contract in the axial direction, and the solid electrolyte cylindrical body In contrast, no axial stress occurs.

  A plurality of solid electrolyte cylinders may be arranged at a predetermined pitch on one vertical plane, or a columnar solid electrolyte cylinder bundle may be constituted by a plurality of solid electrolyte cylinders. In addition, the heating means is constituted by a flat heater, and the solid electrolyte cylindrical body is sandwiched between the heating means, and the heating means is constituted by a heating wire wound around the solid electrolyte cylindrical body. can do. In addition, when a columnar solid electrolyte cylinder bundle is constituted by a plurality of solid electrolyte cylinders, the plurality of solid electrolyte cylinders may be arranged along the circumferential direction.

  By the way, if the solid electrolyte cylindrical body is allowed to expand and contract in the axial direction, a part of the solid electrolyte or a part of the electrode may be peeled off due to thermal expansion or the like. Therefore, if the gas flows into the solid electrolyte cylindrical body from below, the treated gas will flow out from above, so that the peeled off solid electrolyte etc. stays below and the treated gas supply Do not let out.

  In the present invention, axial stress is not generated in the solid electrolyte cylindrical body. For this reason, since the factor which causes damage mainly is deleted, the lifetime of the solid electrolyte cylindrical body is extended.

  The solid electrolyte cylindrical body can be sandwiched by a flat heater, and a compact oxygen pump can be configured. In particular, when sandwiched between sandwiches, if a plurality of solid electrolyte cylindrical bodies are arranged at a predetermined pitch on one vertical plane, the size can be further reduced, and the oxygen partial pressure using this oxygen pump can be increased. Incorporation into the control device is improved. In addition, since a plurality of solid electrolyte cylindrical bodies are provided, the purification capacity can be improved.

  When a columnar solid electrolyte cylindrical bundle is constituted by a plurality of solid electrolyte cylindrical bodies, a heating wire (heater) is arranged on the outer peripheral side of the solid electrolyte cylindrical bundle as a heating means so as to surround the outer periphery. It is possible to use a heating wire (heater) arranged on the inner peripheral side and surrounding the inner periphery, or a heating wire (heater) surrounding both the outer peripheral side and the inner peripheral side. For this reason, each solid electrolyte cylindrical body 30 of the solid electrolyte cylindrical body bundle can be heated more efficiently, and moreover, since a plurality of solid electrolyte cylindrical bodies are provided, the purification ability can be improved.

  By supplying gas to the solid electrolyte cylindrical body from below, the peeled material stays below and does not flow out to the treated gas supply side. For this reason, pure purified gas can be supplied, and the operation in the sample preparation chamber or the like on the gas supply side is stabilized.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. The oxygen pump according to the present invention includes a solid electrolyte cylindrical body 30 having oxygen ion conductivity, electrodes (not shown) disposed on the inner and outer surfaces of the solid electrolyte cylindrical body 30, and the solid electrolyte cylindrical body 30. The heating means 31 which heats is provided. In this case, platinum plating etc. are given to the inner surface and outer surface of the solid electrolyte cylindrical body 30, and an electrode is comprised. This oxygen pump has a plurality (five in the illustrated example) of solid electrolyte cylinders 30, and each solid electrolyte cylinder 30 is surrounded by a heat insulating structure 35. Each solid electrolyte cylindrical body 30 and the heat insulating structure 35 are accommodated in a casing (not shown).

  The heat insulating structure 35 includes halves 37 and 37 made of a heat insulating material, and a gap 40 having a predetermined size is formed between the mating surfaces 37 a and 37 a of the halves 37 and 37. That is, the gap 40 is set to be slightly larger than the outer diameter dimension of the solid electrolyte cylindrical body 30, and the solid electrolyte cylindrical body 30 is disposed in the gap 40 so as not to contact the halved body 37.

  Here, the heat insulating material is a material that blocks the transfer of thermal energy, and includes an inorganic material and an organic material. In general, an inorganic material is used when the temperature is high, and an organic material is used when the temperature is low. Examples of inorganic heat insulating materials include fiber heat insulating materials using ceramic fibers, glass fibers, asbestos, etc., powder heat insulating materials using calcium silicate, magnesium carbonate, etc., and porous heat insulating materials such as perlite / foam glass. For this reason, since the solid electrolyte cylindrical body 30 is heated by the heating means 31 to about 600 degreeC, it can select from what can respond to this temperature.

  Moreover, rectangular recesses 41 and 41 are provided in the mating surfaces 37a and 37a, and a pair of heaters 43 and 43 constituting the heating means 31 are arranged in a space 42 formed by the recesses 41 and 41. Has been. A cover material 39 is attached to the recesses 41 and 41. As described above, the present oxygen pump arranges the plurality of solid electrolyte cylindrical bodies 30 at a predetermined pitch on one vertical plane, and uses the planar heaters 43 and 43 constituting the heating means 31 to form a plurality of solids. A cylindrical body group 29 composed of the electrolyte cylindrical body 30 is sandwiched.

  Each heater 43 is provided with a temperature detector (not shown) (for example, a thermoelectric thermometer), and the temperature of the heater 43 is monitored. Here, the thermoelectric thermometer is a thermometer using a thermocouple. That is, the temperature measuring contact is connected to the heater side (the heater itself or a support body (not shown) supporting the heater), and the electromotive force between the temperature measuring contact and the reference contact is measured.

  Each solid electrolyte cylindrical body 30 has an upper end side and a lower end side attached to a casing (not shown) via flexible coupling bodies 55 and 56. That is, the casing is provided with space portions at the upper and lower portions thereof, and connecting pipe joints 59 and 60 are respectively attached to the upper and lower ends of the solid electrolyte cylindrical body 30 protruding into the space portion. A gas junction pipe 61 is disposed in the upper space, and a gas branch pipe 62 is disposed in the lower space. The gas junction pipe 61 and the gas branch pipe 62 are connected to the gas junction pipe 61 and the flexible branch bodies 55 and 56, respectively. Thus, the connecting pipe joints 59 and 60 are connected.

  The flexible coupling bodies 55 and 56 are flexible pipes, and are connected to the flexible main bodies 55a and 56a, the connection portions 55b and 56b connected to the coupling pipe joints 59 and 60, and the gas junction pipe 61 or the gas branch pipe 62. Connecting portions 55c and 56c. Moreover, as shown in FIG. 2, the flexible main bodies 55a and 56a are formed in a loop shape.

  Each of the gas junction pipe 61 and the gas branch pipe 62 has an axial hole 66 extending in the longitudinal direction and a plurality of (in this case, five corresponding to the solid electrolyte cylindrical body 30) communicating with the axial hole 66. ) Connecting portion 67. The connecting portions 67 are arranged at a predetermined pitch (constant pitch) along the axial hole 66. And the flexible connection bodies 55 and 56 are connected to each connection part 67.

  The gas junction pipe 61 is fixed to the upper wall of the casing, and a connecting pipe 68 connected to the axial hole 66 is connected. In this case, the axial hole 66 of the merging pipe 61 opens to one side wall side (right side in FIG. 1) of the casing, and this opening is connected to the connecting pipe 68 fixed to one side wall of the casing.

  The gas branch pipe 62 is fixed to the lower wall of the casing, and a connecting pipe 69 connected to the axial hole 66 is connected. In this case, the axial hole 66 of the branch pipe 62 opens on the other side wall side (left side in FIG. 1) of the casing, and this opening is connected to the connecting pipe 69 fixed to one side wall of the casing. For this reason, after the connecting pipe 69 protrudes from the branch pipe 62 to the other side wall side, it makes a U-turn to the one side wall side.

  In this case, gas flows into the solid electrolyte cylindrical body 30 from below through the branch pipe 62 and the flexible connection body 56 from the lower connection pipe 69, and oxygen molecules are reduced to control the target oxygen partial pressure. This gas is treated gas (purified gas), and the treated gas flows out from above the solid electrolyte cylindrical body 30 to the upper connecting pipe 68 through the flexible connecting body 55 and the junction pipe 61.

  By the way, in the oxygen pump of the present invention, the gas flowing into the solid electrolyte cylindrical body 30A on one side wall side enters the branch pipe 62 from the opening on the other side wall side, and the axial hole 66 of this branch pipe 62 Will flow into one side wall and then flow in. The purified gas flowing through the solid electrolyte cylindrical body 30A flows into the opening side of the axial center hole 66 of the merging pipe 61 through the flexible connecting body 55, and passes through the connecting pipe 68 to the oxygen sensor side. To leak. The gas flowing into the solid electrolyte cylindrical body 30E on the other side wall side enters the branch pipe 62 from the opening on the other side wall side, and passes through the flexible coupling body 56 from the coupling portion 67 on the other side wall side. Gas that has flowed in and purified by the solid electrolyte cylindrical body 30E flows into the connecting portion 67 on the other side wall side of the axial hole 66 of the merging pipe 61, flows through the axial hole 66 to the opening side, and is connected. It flows out to the oxygen sensor side through the pipe 68.

  Thus, although the vertical movement of each solid electrolyte cylindrical body 30 is allowed, the vertical positions are made to correspond to the predetermined height positions by the upper and lower flexible coupling bodies 55 and 56. In other words, the flexible connectors 55 and 56 need to be able to be held at positions corresponding to the heaters 43 and have rigidity to allow the solid electrolyte cylindrical body 30 to move up and down. It is also preferable to arrange a regulating member that regulates the horizontal movement of the solid electrolyte cylindrical body 30 in the heat insulating structure 35.

  According to the present invention, since the upper end and the lower end of the solid electrolyte cylindrical body 30 are attached to the fixed side via the flexible coupling bodies 55 and 56, respectively, the solid electrolyte cylindrical body 30 is allowed to expand and contract in the axial direction, No axial stress is generated on the solid electrolyte cylindrical body 30. For this reason, since the factor which causes damage mainly is deleted, the lifetime of the solid electrolyte cylindrical body is extended.

  By the way, if the solid electrolyte cylindrical body 30 is allowed to expand and contract in the axial direction, a part of the solid electrolyte or a part of the electrode may be peeled off due to thermal expansion or the like. However, even in such a case, in the present invention, the gas flows into the solid electrolyte cylindrical body 30 from below, so that the treated gas flows out from above, and the solid electrolyte or the like peeled off is below this Stay on the gas supply side after treatment. For this reason, pure purified gas can be supplied, and the operation in the sample preparation chamber or the like on the gas supply side is stabilized.

  Further, a plurality of solid electrolyte cylindrical bodies 30 are arranged at a predetermined pitch on one vertical plane, and the solid electrolyte cylindrical bodies 30 are sandwiched between flat heaters 43 constituting the heating means 31. As a result, a compact oxygen pump can be formed, and the incorporation into an oxygen partial pressure control apparatus using this oxygen pump is improved. In addition, since a plurality of solid electrolyte cylindrical bodies 30 are provided, the purification capacity can be improved.

  In the oxygen pump of this embodiment, the flexible coupling body 56 for supplying gas from the gas branch pipe 62 to each solid electrolyte cylindrical body 30, the gas branch pipe 62 to which the gas inflow pipe 69 is connected, the gas A flow rate control mechanism including a gas junction pipe 61 to which the outflow pipe 68 is connected and a flexible coupling body 55 that supplies the gas junction pipe 61 from each solid electrolyte cylindrical body 30 is configured. By this flow rate control mechanism, the flow path length in the upstream flow path from the gas inflow tube 69 to the solid electrolyte cylindrical body 30 and the downstream flow path from the solid electrolyte cylindrical body 30 to the gas outflow pipe 68 is reduced. In addition, the total length of the upstream channel and the downstream channel for each solid electrolyte cylindrical body was made constant.

  Therefore, in the oxygen pump, the flow rate control mechanism makes the flow path lengths different between the upstream side and the downstream side for each of the solid electrolyte cylindrical bodies 30 arranged side by side, and flows into the oxygen pump and branches. Thereafter, the lengths of the flow paths of the gas to be merged are matched. For this reason, the flow rate of the gas flowing through each solid electrolyte cylindrical body 30 is the same, and the processing capability of each solid electrolyte cylindrical body 30 is the same.

  By the way, in the said embodiment, although the planar heater 43 was used as the heating means 31, instead of using the planar heater 43, the heating wire (using a heater) which makes the solid electrolyte cylindrical body 30 a surrounding shape is used. In this case, even if a plurality of ring-shaped heating wires are arranged at a predetermined pitch along the axial direction, one heating wire is spirally wound around the solid electrolyte cylindrical body 30 (coiled). In this way, by using a surrounding heating wire, the solid electrolyte cylindrical body 30 can be heated from the entire circumferential direction, and efficient heating is possible. Become.

  Moreover, in the said embodiment, although each solid electrolyte cylindrical body 30 is arrange | positioned on one vertical surface, as another embodiment, a column-shaped solid electrolyte cylindrical body in the some solid electrolyte cylindrical body 30 is provided. You may comprise a bundle. In this case, a plurality of solid electrolyte cylindrical bodies 30 can be disposed along the circumferential direction, or a plurality of solid electrolyte cylindrical bodies 30 can be disposed so as to be bundled. Moreover, when arrange | positioning along the circumferential direction, you may arrange | position on the some concentric circle.

  If a plurality of solid electrolyte cylindrical bodies 30 constitutes a columnar solid electrolyte cylindrical bundle, a heating wire 31 is disposed on the outer peripheral side of the solid electrolyte cylindrical bundle as a heating means 31 and surrounds the outer periphery ( Heater), a heating wire (heater) disposed on the inner peripheral side and surrounding the inner periphery, or a heating wire (heater) surrounding both the outer peripheral side and the inner peripheral side can be used. For this reason, each solid electrolyte cylindrical body 30 of the solid electrolyte cylindrical body bundle can be heated more efficiently, and moreover, since a plurality of solid electrolyte cylindrical bodies are provided, the purification ability can be improved.

  As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to the said embodiment, A various deformation | transformation is possible, for example, either one of the upper end of the solid electrolyte cylindrical body 30, and a lower end May be connected by a flexible connector. The number of solid electrolyte cylindrical bodies 30 can be increased or decreased, and at least one solid electrolyte cylindrical body 30 is sufficient. Even when it is arranged on a vertical plane, it may be an unequal pitch instead of a constant pitch. Further, each solid electrolyte cylindrical body 30 may be disposed along the horizontal direction or the like without being disposed along the vertical direction.

  In the embodiment, the connecting pipe 69 connected to the lower branch pipe 62 is elongated, but the connecting pipe 68 connected to the upper junction pipe 61 may be elongated. Further, in the embodiment, the gas flows in from the lower connecting pipe 69 and is processed in each solid electrolyte cylindrical body 30, and then flows out from the upper connecting pipe 68. It may flow out from the connecting pipe 68 and then flow out from the lower connecting pipe 69 after being treated by each solid electrolyte cylindrical body 30.

  As the heater 43 of the heating means 31, the solid electrolyte cylindrical body 30 is sandwiched in the embodiment, but may be disposed on either the front side or the rear side. In addition, a planar heater 43 may be used as the heating means 31 for a column-shaped solid electrolyte cylindrical body bundle constituted by a plurality of solid electrolyte cylindrical bodies 30. Even when sandwiched between two flat heaters 43, one flat heater 43 may be disposed on either the front side or the rear side, and further, four flat planes may be provided. The solid electrolyte cylindrical bundle may be arranged so as to surround the four directions of the front, rear, left and right with the heater 43 having a shape.

It is a principal part front view inside the oxygen pump which shows embodiment of this invention. It is a cross-sectional side view of the oxygen pump. . It is a simplified diagram of a conventional oxygen partial pressure control device. It is explanatory drawing of the principle of an oxygen pump.

Explanation of symbols

30 Solid electrolyte cylindrical body 31 Heating means 43 Heater 55 Flexible connector 56 Flexible connector

Claims (6)

In an oxygen pump comprising a solid electrolyte cylindrical body having oxygen ion conductivity, electrodes disposed on the inner and outer surfaces of the solid electrolyte cylindrical body, and heating means for heating the solid electrolyte cylindrical body,
An oxygen pump characterized in that both ends of a solid electrolyte cylindrical body are respectively attached to a fixed side via a flexible connector.   2. The oxygen pump according to claim 1, wherein a plurality of solid electrolyte cylindrical bodies are arranged at a predetermined pitch on one vertical plane.   2. The oxygen pump according to claim 1, wherein a columnar solid electrolyte cylindrical bundle is constituted by a plurality of solid electrolyte cylindrical bodies.   4. The oxygen pump according to claim 2, wherein the heating means is constituted by a planar heater, and the solid electrolyte cylindrical body is sandwiched between the planar heaters.   4. The oxygen pump according to claim 2, wherein the heating means comprises a heating wire that winds the solid electrolyte cylindrical body in a surrounding shape.   The oxygen pump according to any one of claims 1 to 5, wherein the solid electrolyte cylindrical body is disposed along the vertical direction, and gas flows from below.

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