JP6344218B2 - Heat treatment furnace - Google Patents

Description

  The present invention relates to a heat treatment furnace for heating an object to be processed using a reducing atmosphere gas containing hydrogen.

  2. Description of the Related Art Conventionally, in a heat treatment furnace that performs bright annealing or brazing of metals, atmospheric heat treatment is performed in order to suppress an oxidation reaction of an object to be processed during the heat treatment. As such a heat treatment furnace, one using hydrogen gas or a gas obtained by adding hydrogen to an inert gas as a reducing atmosphere has been put into practical use (see, for example, Japanese Patent Application Laid-Open No. 2011-162869 (Patent Document 1)). According to the heat treatment furnace, oxidation of the object to be processed can be suppressed even at a high heat treatment temperature at which the oxidation reaction easily proceeds. Further, in a heat treatment furnace that performs carburizing to harden the metal surface layer, a gas mainly composed of carbon monoxide, hydrogen, and nitrogen obtained by combining hydrocarbons and air and thermally decomposing them with a Ni catalyst ( RX gas) is used as the processing atmosphere. In the heat treatment described above, it is known that the partial pressure of water vapor in the atmosphere affects the processing result of the object to be processed, and it is often necessary to control the partial pressure of water vapor. Note that in this specification, hydrogen gas (100% hydrogen gas) and gas obtained by adding hydrogen gas to an inert gas or other gas are collectively referred to as “hydrogen-containing gas” or “gas containing hydrogen”.

JP 2011-162869 A

  In the above heat treatment furnace, in order to prevent oxygen in the air from reacting with the object to be treated, the furnace has entered the furnace while keeping the furnace at a positive pressure so that air (oxygen) does not enter the furnace as much as possible. Oxygen is reacted with hydrogen in a reducing atmosphere. Further, the used hydrogen-containing gas is high temperature and contains impurities, so that it is difficult to recover it, and it cannot be discharged as it is outside the heat treatment furnace. For this reason, conventionally, a combustion apparatus is provided in the vicinity of a discharge pipe for discharging the used hydrogen-containing gas from the furnace, and the discharged hydrogen-containing gas is burned.

  However, although heat is generated by the combustion treatment of the hydrogen-containing gas, it is difficult to use heat generated outside the heat treatment furnace as a heat source in the furnace. In addition, from the viewpoint of ensuring safety, it has been difficult to realize the introduction of the high-temperature hydrogen-containing gas discharged from the heat treatment furnace into another apparatus for reuse.

  A configuration in which the hydrogen-containing gas is discharged after sufficiently reducing the temperature of the hydrogen-containing gas in the furnace is conceivable. However, in order to cool the hydrogen-containing gas in the furnace, the exhaust pipe is discharged from the soaking zone in the furnace. It is necessary to increase the length of the furnace, and the furnace body may be enlarged. As described above, in the conventional heat treatment furnace, it is not always easy to utilize the used hydrogen-containing gas.

  An object of the present invention is to provide a heat treatment furnace capable of utilizing a used hydrogen-containing gas.

  A heat treatment furnace according to one embodiment of the present invention is a heat treatment furnace that performs heat treatment on an object to be processed by holding the object to be processed at a preset heat treatment temperature. In the heat treatment furnace, an interior space capable of accommodating an object to be processed is formed, and the interior space is accommodated in an introduction port for introducing a first gas, which is a gas containing hydrogen, and the interior space of the furnace. A furnace main body having a discharge port for discharging gas to the outside is provided. The in-furnace space has a heat treatment region that is maintained at the heat treatment temperature and a peripheral region that is disposed around the heat treatment region and is maintained at an ambient temperature that is lower than the heat treatment temperature. The heat treatment furnace further includes a hydrogen ion conduction type fuel cell disposed in the peripheral region and operating at an ambient temperature.

  According to the above, it is possible to realize a heat treatment furnace capable of utilizing the used hydrogen-containing gas.

2 is a schematic cross-sectional view illustrating a configuration of a heat treatment furnace according to Embodiment 1. FIG. It is a figure which shows typically the arrangement configuration of the fuel cell seen from the outer side of the furnace main body. It is sectional drawing which follows the III-III line of FIG. It is a figure which shows typically the arrangement configuration of a fuel cell. It is a figure which shows typically the other structural example of the arrangement structure of a fuel cell. It is sectional drawing which shows the structure of a fuel cell. 6 is a schematic diagram showing a configuration of a heat treatment furnace according to Embodiment 2. FIG. It is a schematic diagram which shows the state which looked at the heat processing furnace shown in FIG. 7 from the upper surface. It is a figure which shows typically the arrangement configuration of a fuel cell. It is a longitudinal cross-sectional view which shows the arrangement structure of a fuel cell. It is sectional drawing which follows the XI-XI line in FIG. FIG. 6 is a block diagram showing a configuration of a heat treatment furnace according to a modification of the first embodiment.

[Description of Embodiment of the Present Invention]
First, embodiments of the present invention will be listed and described.

  (1) A heat treatment furnace according to one embodiment of the present invention is a heat treatment furnace that heat-treats an object to be processed by holding the object to be processed at a preset heat treatment temperature. In the heat treatment furnace, an interior space capable of accommodating an object to be processed is formed, and the interior space is accommodated in an introduction port for introducing a first gas, which is a gas containing hydrogen, and the interior space of the furnace. A furnace main body having a discharge port for discharging gas to the outside is provided. The in-furnace space has a heat treatment region that is maintained at the heat treatment temperature and a peripheral region that is disposed around the heat treatment region and is maintained at an ambient temperature that is lower than the heat treatment temperature. The heat treatment furnace further includes a hydrogen ion conduction type fuel cell disposed in the peripheral region and operating at an ambient temperature.

  According to the heat treatment furnace described in the above (1), by disposing the fuel cell operable at the ambient temperature in the peripheral area held at a temperature (ambient temperature) lower than the heat treatment temperature in the furnace space. In the heat treatment, power can be generated using, for example, a hydrogen-containing gas used in a reducing atmosphere. Since the fuel cell can operate at an ambient temperature, it is not necessary to install a heater for heating the fuel cell, and the heat generated when the fuel cell generates electricity can be supplied to the furnace space. As a result, a heat treatment furnace capable of utilizing the used hydrogen-containing gas can be realized.

  (2) Preferably, in the heat treatment furnace as described in (1) above, the fuel cell is disposed in a portion of the peripheral region located vertically above the heat treatment region. Since the used hydrogen-containing gas has a lower specific gravity than air or an inert gas such as nitrogen or argon used for the gas curtain at the entrance and exit of the furnace, it tends to gather on the upper side in the furnace. Therefore, the hydrogen-containing gas can be efficiently introduced into the anode of the fuel cell by arranging the fuel cell in the peripheral region located on the upper side in the furnace. As a result, the electrochemical reaction in the fuel cell can be promoted.

  (3) Preferably, in the heat treatment furnace described in (2) above, the peripheral region has a portion having a shape protruding upward inside the furnace body, and the fuel cell is disposed in the portion. As a result, the hydrogen-containing gas distributed above the heat treatment region can be collected in a part (a part having a shape protruding upward), so that it is more efficient than the anode of the fuel cell accommodated in the part. In particular, a hydrogen-containing gas can be introduced.

  (4) Preferably, in the heat treatment furnace described in (3) above, the portion of the shape protruding upward in the furnace body becomes smaller as the cross-sectional area in the horizontal plane goes upward. As a result, the hydrogen-containing gas distributed above the heat treatment region can be efficiently collected in part and introduced into the anode of the fuel cell.

  (5) Preferably, in the heat treatment furnace described in (3) or (4) above, the discharge port is formed on the inner wall surface of the furnace body facing a portion having a shape protruding upward in the furnace body. Thereby, by exhausting from the exhaust port facing the upwardly protruding shape part inside the furnace body, the hydrogen-containing gas can be collected more efficiently from the entire interior of the furnace body to the protruding shape part. it can.

  (6) Preferably, in the heat treatment furnace according to any one of (1) to (5), the fuel cell is disposed at a position sandwiched between the discharge port and the heat treatment region. For example, the hydrogen-containing gas used in the reducing atmosphere is discharged from the furnace body through the discharge port from the heat treatment region. Therefore, the hydrogen-containing gas can be efficiently introduced into the anode of the fuel cell by disposing the fuel cell in the peripheral region between the heat treatment region and the discharge port. As a result, the electrochemical reaction in the fuel cell can be promoted.

  (7) Preferably, in the heat treatment furnace according to any one of (1) to (6), the fuel cell includes a membrane electrode assembly. The membrane electrode assembly includes a hydrogen ion conductive solid electrolyte formed in a tubular body, a first electrode formed on the outer periphery of the solid electrolyte, into which the first gas is introduced, and an inner periphery of the solid electrolyte. And a second electrode into which a second gas that is a gas containing oxygen is introduced. Thereby, in the fuel cell, a structure is realized in which water is generated by an electrochemical reaction on the inner surface side of the membrane electrode assembly formed in a cylindrical shape, and no water is generated on the outer surface side of the membrane electrode assembly. For this reason, it can avoid that the produced | generated water is discharge | released by the atmospheric gas of the space in a furnace, and a water vapor | steam density | concentration rises.

  (8) Preferably, in the heat treatment furnace described in (7) above, the membrane electrode assembly has an opening at at least one end of the cylindrical body. The fuel cell is arranged so that one end including the opening of the membrane electrode assembly protrudes outside the furnace body. Thereby, since the inner surface side of the membrane electrode assembly can be isolated from the space in the furnace, it is possible to prevent the water generated on the inner surface side from being released to the atmospheric gas in the space in the furnace.

  (9) Preferably, in the heat treatment furnace described in (7) or (8) above, the hydrogen ion conductive solid electrolyte is a perovskite oxide represented by the general formula (1).

M2 _a Zr _x Ce _y M3 _(1-xy) O _3-δ (1)
(In the general formula (1), M2 represents at least one +2 valent metal ion selected from Ca, Sr, and Ba, and M3 represents a rare earth other than Ce and Mn, Fe, Co, Ni, Al, Ga. , In represents at least one kind of + 3-valent metal ion selected from In, a is 0.90 or more and 1.05 or less, x and y are each 0 or more and 1.0 or less, and x + y is 0. 75 to 1.0, and δ represents the number of oxygen ion defects in the crystal lattice.)
(10) In the heat treatment furnace according to any one of (1) to (9), preferably, the operating temperature of the fuel cell is 400 ° C. or higher and 600 ° C. or lower. Thereby, a fuel cell can be arrange | positioned in the peripheral region of the heat processing area | region whose heat processing temperature is about 600 to 1100 degreeC, for example.

[Details of the embodiment of the present invention]
Next, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

<Embodiment 1>
First, an overall configuration of a heat treatment furnace according to an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing a configuration of a heat treatment furnace 100 according to the first embodiment. The heat treatment furnace 100 according to Embodiment 1 heats the workpiece 200 by holding the workpiece 200 at a preset heat treatment temperature. The vertical direction in FIG. 1 indicates the height direction (vertical direction) of the heat treatment furnace 100, and the left-right direction in FIG. 1 indicates the width direction (horizontal direction) of the heat treatment furnace 100.

  As shown in FIG. 1, the heat treatment furnace 100 according to the first embodiment is a continuous heat treatment furnace capable of continuously heat-treating a plurality of workpieces 200. The heat treatment furnace 100 includes a furnace body 10, a carry-in port 13, a carry-out port 14, a carry belt 16, an introduction pipe 18, discharge pipes 20 and 22, heaters 40, 42 and 44, and a casing 110. Prepare.

  The furnace body 10 is housed in a housing 110. A carry-in port 13 is connected to one end of the furnace body 10 in the horizontal direction, and a carry-out port 14 is connected to the other end. The workpiece 200 is placed on the conveyor belt 16 at the carry-in port 13. The conveyor belt 16 is driven by a drive unit (not shown). The workpiece 200 placed on the conveyor belt 16 is carried into the furnace body 10.

  A furnace space that can accommodate the workpiece 200 is formed inside the furnace body 10. Heaters 40, 42, and 44 are provided in the furnace space. The atmosphere in the furnace space is heated by the heaters 40 and 42. The workpiece 200 is heated by the heated high-temperature atmosphere.

  In the furnace space, a heating zone, a soaking zone, and a cooling zone are formed in this order from the upstream side to the downstream side in the conveyance direction of the workpiece 200. In each band, the set temperature is determined according to the quality, dimensions, and the like of the workpiece 200, and heat treatment is performed over the entire length of the workpiece 200. The heaters 40, 42, and 44 are controlled by the control panel 24, so that each of the heating zone, the soaking zone, and the cooling zone can be maintained at the set temperature.

  With the above configuration, the workpiece 200 carried into the furnace body 10 from the carry-in entrance 13 is heated to a predetermined temperature by the heater 40 in the heating zone, and then constant by the heater 42 in the soaking zone. Heat treatment is performed by maintaining the temperature constant for a certain time. The heating zone is maintained in a temperature range of 200 ° C. to 800 ° C., for example. The soaking zone temperature (heat treatment temperature) during the heat treatment of the workpiece 200 is, for example, about 800 ° C. to 1000 ° C. The to-be-processed object 200 is cooled to about 200 ° C. to 800 ° C. in the cooling zone after being heat treated in the soaking zone. That is, the soaking zone forms a “heat treatment region” that is maintained at the heat treatment temperature, and the heating zone and the cooling zone are arranged around the heat treatment region and are held at an ambient temperature that is lower than the heat treatment temperature. The “peripheral region” is formed. When the heat treatment step is completed in this manner, the workpiece 200 is unloaded from the unloading port 14.

A first gas that is a reducing atmosphere gas is held in the furnace space. The first gas is a gas containing hydrogen (H ₂ ). The first gas is a gas containing 100% hydrogen, or a gas obtained by adding hydrogen gas to an inert gas or other gas (that is, a hydrogen-containing gas). Since hydrogen has a strong reducing power, oxygen (O ₂ ) in the atmosphere can be strongly reduced by using a hydrogen-containing gas in the reducing atmosphere. Thereby, the oxidation reaction of the to-be-processed object 200 during heat processing can be suppressed. As the first gas, for example, ammonia (NH ₃ ) decomposition gas, RX gas, a gas containing hydrogen and nitrogen (N ₂ ), a mixed gas of hydrogen and an inert gas, or the like is used. In the following description, both the hydrogen-containing gas introduced into the furnace space and the hydrogen-containing gas after being used in the reducing atmosphere in the furnace space are referred to as “first gas”. The gas composition (hydrogen concentration) may not necessarily match.

  The first gas is introduced from the introduction pipe 18 into the furnace body 10. At this time, the first gas is introduced so that the furnace has a positive pressure. The first gas introduced into the furnace body 10 is heated by the heaters 40 and 42. The first gas used in the reducing atmosphere is discharged from each of the discharge pipe 20 provided at the carry-in port 13 and the discharge pipe 22 provided at the carry-out port 14. Each of the discharge pipes 20 and 22 is connected to the exhaust pipe 111. The first gas discharged from the discharge pipes 20 and 22 is subjected to a combustion process in the hydrogen treatment apparatus 112 installed in the vicinity of the discharge pipes 20 and 22.

  The heat treatment furnace 100 further includes a control panel 24, an external power wiring 26, a fuel cell 30, a voltage application unit 32, and a private power wiring 34.

  Electric power is supplied from the control panel 24 to the heaters 40, 42 and 44 via the external power wiring 26. The control panel 24 receives power from an external power source (for example, commercial power source) and controls power feeding to the heaters 40, 42, and 44. Specifically, the furnace body 10 is provided with a plurality of thermometers (not shown) for detecting the temperatures of the heating zone, the soaking zone, and the cooling zone. When the control panel 24 acquires the detection values of the plurality of thermometers, each of the heaters 40, 42, and 44 is based on the deviation of the detection value of the thermometer with respect to the set temperature for each of the heating zone, the soaking zone, and the cooling zone. Controls the power supplied to Thereby, a heating zone, a soaking zone, and a cooling zone are each kept at preset temperature.

  The fuel cell 30 is disposed in a peripheral region of the soaking zone (heat treatment region) in the furnace space. In the present embodiment, the fuel cell 30 can be disposed in at least one of the heating zone and the cooling zone. FIG. 1 shows an example in which the fuel cell 30 is arranged in the heating zone. The fuel cell 30 is disposed in a portion of the surrounding area located vertically above the soaking zone. The arrangement position of the fuel cell 30 will be described later.

The fuel cell 30 can operate at a temperature (ambient temperature) lower than the heat treatment temperature of the workpiece 200. The operating temperature of the fuel cell 30 is preferably 400 ° C to 600 ° C. As such a fuel cell 30, for example, an intermediate temperature solid oxide fuel cell (IT-SOFC) can be used. The IT-SOFC is an SOFC used for a hydrogen ion (H ⁺ ) conductive solid electrolyte typified by, for example, barium zirconate doped with a trivalent cation such as yttrium or barium serate. IT-SOFC is, for example, the general formula _{M2 a Zr x Ce y M3 (} 1-x-y) perovskite oxide represented by _{O 3-δ.} In the above general formula, M2 represents at least one +2 valent metal ion selected from Ca, Sr, and Ba, M3 represents rare earth excluding Ce, and Mn, Fe, Co, Ni, Al, Ga, and In. Represents at least one kind of +3 valent metal ion selected, a is 0.90 or more and 1.05 or less, x and y are each 0 or more and 1.0 or less, and x + y is 0.75 or more and 1 0.0 or less, and δ represents the number of defects of oxygen ions in the crystal lattice. In addition, by setting the operating temperature to a low temperature range of about 400 ° C. to 600 ° C., it can be applied to a heat treatment furnace having a low operating temperature that cannot be applied to a conventional SOFC.

  Thus, by adopting IT-SOFC that can operate at the ambient temperature as the fuel cell 30, the fuel cell 30 can be operated by being heated by the first gas used in the reducing atmosphere. Therefore, it is possible to install the fuel cell 30 in the furnace space without installing a dedicated heater for heating the fuel cell 30 to the operating temperature in the furnace space. It is also possible to supply heat generated when the fuel cell 30 generates power to the furnace space.

The fuel cell 30 includes a membrane electrode assembly (MEA) as a main component. The MEA includes an anode (first electrode) into which a first gas that is a hydrogen-containing gas is introduced, a cathode (second electrode) into which a second gas is introduced, and an ion conductive insulating layer sandwiched between two electrodes. Consists of. In this embodiment, a hydrogen ion conductive solid electrolyte is used for the ion conductive insulating layer. That is, the fuel cell 30 is a hydrogen ion conduction type SOFC. The MEA generates power by causing an electrochemical reaction between hydrogen contained in the first gas and the second gas. The second gas may be any gas that generates an electrochemical reaction to generate power in combination with the first gas. However, in this embodiment, an example in which oxygen, that is, oxygen (O ₂ ) in the air is used, is shown. As shown in FIG. 1, the air as the second gas enters from the outside of the housing 110 and is introduced into the MEA in the furnace body 10.

  The electric power generated by the fuel cell 30 is supplied to the private power wiring 34. As shown in FIG. 1, the electric power generated by the above-described electrochemical reaction can be supplied to the heaters 40, 42, 44 via the private power wiring 34. Thereby, the shortage of power consumption in the heaters 40, 42 and 44 is supplied from the external power source via the control panel 24, and the power supplied from the external power source can be reduced. As a result, the running cost of the heat treatment furnace 100 can be suppressed. Although not shown in the drawing, the same effect can be obtained even when the electric power generated by the fuel cell 30 is supplied to an electric load (for example, a lighting device) other than the heater via the private power wiring 34. Can do.

  A voltage application unit 32 is inserted in the private power line 34. The voltage application unit 32 is controlled by the control panel 24. The voltage application unit 32 applies a forward voltage of an electrochemical reaction between the anode (first electrode) and the cathode (second electrode) of the MEA. While the heat treatment furnace 100 is stopped, the electrochemical reaction is in a dormant state, so that oxidation proceeds when oxygen comes into contact with the anode or the like. Further, when the heat treatment furnace 100 is operated, the reduction proceeds by restarting the electrochemical reaction. In this way, oxidation and reduction are repeated as the heat treatment furnace 100 is repeatedly operated and stopped. This repeated oxidation and reduction damages the electrode material and may degrade the electrode. In the present embodiment, the application of voltage by the voltage application unit 32 can suppress the oxidative reaction during the pause, so that the deterioration of the electrode can be prevented. The voltage application unit 32 can be configured using a circuit including a diode and a transistor, for example.

(Fuel cell layout)
FIG. 2 is a diagram schematically showing the arrangement configuration of the fuel cell 30 as viewed from the outside of the furnace body 10. 3 is a cross-sectional view taken along line III-III in FIG.

  As shown in FIG. 1, the fuel cell 30 is provided in a portion of the peripheral region located vertically above the heat treatment region. “A portion of the peripheral region located vertically above the heat treatment region” is a portion located at a position higher than the heat treatment region. The portion may be provided in a peripheral region located obliquely above the heat treatment region as shown in FIG. 1 or may be provided in a peripheral region located directly above the heat treatment region.

  The first gas that is a hydrogen-containing gas has a lower specific gravity than air. Therefore, the first gas used in the reducing atmosphere in the soaking zone is likely to gather vertically above the furnace space. Therefore, a concentration distribution in which the concentration of the first gas increases upward is generated in the furnace space. Therefore, by disposing the fuel cell 30 in the peripheral region located higher than the heat treatment region, the fuel cell 30 can be disposed in the region where the concentration of the first gas is high. Thereby, since 1st gas can be efficiently introduce | transduced into the anode (1st electrode) of MEA, the electrochemical reaction in MEA can be promoted.

  As shown in FIGS. 1 and 2, the peripheral region may have a portion (hereinafter simply referred to as a “protruding portion”) 15 having a shape protruding upward in the furnace body 10. The fuel cell 30 is disposed inside the protruding portion 15. The shape of the projecting portion 15 is not particularly limited as long as a space can be formed therein, and is cylindrical, triangular, quadrangular, polygonal, hemispherical in section, or elliptical in section. Shape, conical shape, triangular pyramid shape, quadrangular pyramid shape, polygonal pyramid shape, truncated cone shape, triangular frustum shape, quadrangular frustum shape, polygonal frustum shape, and other shapes. As a result, the first gas dispersed vertically above the furnace space can be collected in the space inside the protruding portion 15.

  FIG. 2 shows an example in which the protruding portion 15 has a quadrangular pyramid shape. A hole 150 for inserting the fuel cell 30 is formed in each of a pair of opposing side wall surfaces of the four side wall surfaces of the protruding portion 15.

  In the present embodiment, fuel cell 30 has a cylindrical (for example, cylindrical) MEA. As shown in FIG. 3, in the cylindrical MEA 7, the outer peripheral surface is an anode (first electrode) into which the first gas is introduced, and the inner peripheral surface is a cathode (second electrode) into which the second gas is introduced. . The MEA 7 is inserted into the hole 150 formed in the pair of side wall surfaces of the protruding portion 15. Openings at both ends of the MEA 7 protrude outside the furnace body 10. Therefore, the inside (cathode side) of the MEA 7 is isolated from the furnace space. In this way, the fuel cell 30 is disposed through the furnace body 10 in the protruding portion 15. The gap between the inner peripheral surface of the hole 150 and the outer peripheral surface of the fuel cell 30 is closed to prevent the first gas from leaking outside the furnace body 10.

  FIG. 4 is a diagram schematically illustrating a configuration example of the protruding portion 15. As shown in FIG. 4, the protruding portion 15 is formed so as to decrease as the cross-sectional area in the horizontal plane goes upward. That is, the protruding portion 15 is formed so that the cross-sectional area of the opening (area S2 in the drawing) is the largest and the uppermost cross-sectional area (area S1 in the drawing) is the smallest.

  With such a configuration, the first gas dispersed vertically above the furnace space is collected inside the protruding portion 15. And inside the protrusion part 15, the density | concentration of 1st gas becomes high, so that it goes upwards. Therefore, the first gas can be efficiently introduced into the outer peripheral surface (anode) of the MEA 7 accommodated in the protruding portion 15.

  Furthermore, it is good also as a structure by which the discharge port 152 for discharging | emitting the gas accommodated in the space in a furnace is provided in the inner wall face of the furnace main body 10 which faces the protrusion part 15. FIG. FIG. 5 illustrates a configuration in which the discharge port 152 is provided on the upper surface of the protruding portion 15. According to this, the first gas collected inside the protruding portion is discharged to the outside of the furnace body 10 through the discharge port 152. That is, a flow path of the first gas is formed inside the protruding portion so that the first gas flows from the opening side toward the discharge port 152. By disposing the fuel cell 30 on the flow path of the first gas, the first gas can be efficiently introduced into the outer peripheral surface (anode) of the MEA 7.

  Even if the discharge port 152 is provided on any one of the four side wall surfaces of the protruding portion 15, the fuel cell 30 is disposed on the flow path of the first gas, so that a certain effect can be obtained.

(Configuration of fuel cell)
Hereinafter, the configuration of the fuel cell 30 disposed in the heat treatment furnace 100 according to Embodiment 1 will be described with reference to FIG. FIG. 6 is a cross-sectional view showing the configuration of the fuel cell 30. 6A is a longitudinal sectional view of the fuel cell 30, and FIG. 6B is a sectional view taken along line VIB-VIB in FIG. 6A.

  As shown in FIG. 6, the cylindrical MEA 7 covers the cylindrical solid electrolyte 1, the cathode (second electrode) 2 provided so as to cover the inner surface of the solid electrolyte 1, and the outer surface of the solid electrolyte 1. And an anode (first electrode) 5 provided on the substrate. The anode 5 is also referred to as “fuel electrode”, and the cathode 2 is also referred to as “air electrode”. As shown in FIG. 3, the inside of the MEA 7 is isolated from the furnace space.

  A cathode current collector 11 is disposed so as to fill the inner cylinder of the cylindrical solid electrolyte 1. An anode current collector 12 is disposed so as to wrap around the outer surface of the anode 5.

  The cathode current collector 11 includes a Ni (nickel) mesh sheet 11a, a porous metal body 11s, and a central conductive rod 11k. The Ni mesh sheet 11a contacts the cathode 2 on the inner surface side of the MEA 7 and conducts from the porous metal body 11s to the central conductive rod 11k. As the porous metal body 11s, in order to reduce the pressure loss of air, it is preferable to use a metal plating body that can increase the porosity, such as Celmet (registered trademark: Sumitomo Electric Industries, Ltd.). Thereby, the pressure loss of gas introduction to the cathode 2 side can be reduced while lowering the overall electrical resistance of the cathode current collector 11.

  The anode current collector 12 includes a silver paste coated wiring 12g and a Ni mesh sheet 12a. The Ni mesh sheet 12 a contacts the outer surface of the MEA 7 and conducts to the private power wiring 34. The silver paste coated wiring 12g contributes to lowering the electrical resistance of the anode current collector 12.

The hydrogen-containing gas that is the first gas contacts the anode 5 while passing through the gaps in the Ni mesh sheet 12a. The anode 5 decomposes hydrogen to generate hydrogen ions (H ⁺ ) and electrons (e ⁻ ). The anode 5 sends out hydrogen ions (H ⁺ ) toward the solid electrolyte 1 toward the cathode 2. The anodic reaction is as follows.

(Anode reaction): H ₂ → 2H ⁺ + 2e ⁻
The air, which is the second gas, contacts the cathode 2 while passing through the gaps between the Ni mesh sheet 11a and the porous metal body 11s. At the cathode 2, hydrogen ions (H ⁺ ) that have reached through the solid electrolyte 1 react with oxygen (O ₂ ) to generate water (H ₂ O). The cathode reaction is as follows.

(Cathode reaction): 2H ⁺ + 1 / 2O ₂ + 2e ⁻ → H ₂ O
As a result of the electrochemical reaction, electric power is generated, and a current I flows from the cathode current collector 11 to the anode current collector 12 due to a potential difference generated between the anode 5 and the cathode 2. By connecting an electrical load, for example, heaters 40, 42, and 44, between the cathode current collector 11 and the anode current collector 12, electric power can be supplied to the electrical load. As shown in FIG. 6, it is preferable to connect the cathode current collector 11 and the heaters 40, 42, and 44 with a private power wiring 34 and insert the voltage application unit 32 into the private power wiring 34.

  Here, in the present embodiment, by using the hydrogen ion conductive solid electrolyte 1, at the cathode 2 inside the cylindrical MEA 7 isolated from the furnace space, hydrogen ions, oxygen molecules, electrons, Reacts to produce water. In other words, water is generated inside the MEA 7 while water is not generated outside the MEA 7, that is, in the furnace space. Thereby, it can be easily avoided that water is released into the atmospheric gas in the furnace space and the water vapor partial pressure is increased. As a result, as shown in FIG. 1, the MEA 7 of the fuel cell 30 can be directly installed in the furnace body 10.

  As described above, according to the continuous heat treatment furnace 100 according to the first embodiment, the peripheral region disposed around the heat treatment region and maintained at the peripheral temperature lower than the heat treatment temperature can be operated at the ambient temperature. A fuel cell is arranged. Thereby, electric power can be generated in the fuel cell using the hydrogen-containing gas used for the heat treatment. By supplying the electric power generated in the fuel cell to an electric load such as a heater, the running cost of the heat treatment furnace can be suppressed.

  In addition, since the fuel cells arranged in the peripheral region are fuel cells that can operate at an ambient temperature, a heater for heating the fuel cell is not required, and heat generated when the fuel cell generates power is not required. Since it can supply to the space in a furnace, it contributes to the reduction of the running cost of a heat treatment furnace.

  Furthermore, the cathode inside the cylindrical hydrogen ion conductive solid electrolyte is configured to be isolated from the space in the furnace, so that the water generated by the electrochemical reaction is released to the atmospheric gas in the furnace. There is no. Therefore, the fuel cell can be installed directly on the furnace body.

  As a result, a heat treatment furnace capable of utilizing the hydrogen-containing gas used as the reducing atmosphere can be realized with a simple apparatus configuration.

(Embodiment 2)
FIG. 7 is a schematic diagram illustrating a configuration of the heat treatment furnace 102 according to the second embodiment. FIG. 8 is a schematic diagram showing the heat treatment furnace 102 shown in FIG. 7 as viewed from above. The heat treatment furnace 102 according to the second embodiment is a batch type heat treatment furnace in which the workpiece 200 is carried into the furnace and heat treatment is performed in units thereof. 7 indicates the height direction (vertical direction) of the heat treatment furnace 102, and the left and right directions in FIGS. 7 and 8 indicate the width direction (horizontal direction) of the heat treatment furnace 102. Yes.

  As shown in FIG. 7, the heat treatment furnace 102 according to the second embodiment includes a furnace body 101, an introduction pipe 104, a discharge pipe 106, and heaters 46 and 48.

  The furnace body 101 has, for example, a rectangular parallelepiped shape, and accommodates the workpiece 200 therein. In FIG. 7, the example which heat-processes the to-be-processed object 200 per unit is shown. Heaters 46 and 48 are provided inside the furnace body 101. The atmosphere in the furnace body 101 is heated by the heaters 46 and 48.

  Inside the furnace main body 101, a soaking part is formed by the atmosphere heated by the heater 46 to a high temperature. The workpiece 200 carried into the furnace body 101 is subjected to heat treatment by being maintained at a constant temperature for a certain period of time in the soaking part. That is, the soaking part forms a “heat treatment region” maintained at the heat treatment temperature. The soaking zone temperature (heat treatment temperature of the workpiece 200) during the heat treatment of the workpiece 200 is, for example, about 800 ° C to 1000 ° C. After the heat treatment process is completed, the workpiece 200 is unloaded from the furnace body 101.

A first gas that is a reducing atmosphere gas is held inside the furnace body 101. The first gas is a hydrogen-containing gas similar to the first gas in the first embodiment. For example, ammonia (NH ₃ ) decomposition gas, RX gas, gas containing hydrogen and nitrogen (N ₂ ), hydrogen, and inert gas A mixed gas or the like is used.

  The first gas is introduced into the furnace body 101 from the introduction pipe 104. The first gas is introduced so that the furnace has a positive pressure. The first gas introduced into the furnace body 101 is heated by the heaters 46 and 48. The first gas used in the reducing atmosphere is exhausted from the exhaust pipe 106. The first gas discharged from the discharge pipe 106 is subjected to a combustion process in a hydrogen treatment apparatus (not shown) installed in the vicinity of the discharge pipe 106.

  The heat treatment furnace 102 further includes a control panel 24, an external power wiring 26, a fuel cell 50, a voltage application unit 32, and a private power wiring 34.

  Electric power is supplied from the control panel 24 to the heaters 46 and 48 via the external power wiring 26. The control panel 24 receives power from an external power source (for example, commercial power source) and controls power feeding to the heaters 46 and 48. Specifically, the furnace main body 101 is provided with a thermometer (not shown) for detecting the temperature of the soaking part. When the control panel 24 acquires the detection value of the thermometer, the control panel 24 controls the power supplied to the heater 46 based on the deviation of the detection value of the thermometer with respect to the set temperature of the soaking part. Thereby, the soaking | uniform-heating part is hold | maintained at preset temperature. On the other hand, the heater 48 is used in an auxiliary manner to adjust a peripheral region to be described later to an operating temperature region of the fuel cell 30.

  The fuel cell 50 is disposed in the furnace body 101 around the heat treatment region, and is provided in a peripheral region that is maintained at an ambient temperature that is lower than the heat treatment temperature. In the second embodiment, in the furnace main body 101, it is adjacent to the soaking part in the horizontal direction and is located in a peripheral area (corresponding to the area RGN in the drawing) located closer to the soaking part as viewed from the discharge pipe 106. The fuel cell 50 is arranged. Accordingly, the fuel cell 50 is provided in the furnace body 101 on the downstream side in the flow direction of the first gas from the heat treatment region, and receives the supply of the first gas used in the reducing atmosphere from the heat treatment region.

  The fuel cell 50 can be operated at a temperature (ambient temperature) lower than the heat treatment temperature of the workpiece 200, similarly to the fuel cell 30 in the heat treatment furnace 100 according to the first embodiment. The operating temperature of the fuel cell 50 is preferably 400 ° C to 600 ° C. As such a fuel cell 50, IT-SOFC is preferably used. By adopting IT-SOFC operable at ambient temperature for the fuel cell 50, the fuel cell 50 installed in the furnace body 101 can be operated by being heated by the first gas used in the reducing atmosphere. it can.

The fuel cell 50 has an MEA as a main component. The MEA includes an anode (first electrode) into which a first gas that is a hydrogen-containing gas is introduced, a cathode (second electrode) into which a second gas is introduced, and an ion conductive insulating layer sandwiched between two electrodes. Consists of. In the second embodiment, as in the first embodiment, a hydrogen ion (H ⁺ ) conductive solid electrolyte is used for the ion conductive insulating layer.

  FIG. 9 is a diagram schematically showing the arrangement configuration of the fuel cell 50. As shown in FIG. 9, the fuel cell 50 is accommodated in the peripheral region RGN. The fuel cell 50 includes a MEA 7 having a cylindrical body (for example, a cylindrical shape).

  The cylindrical MEA 7 is provided with a protrusion 41 by accommodating the lower part in the peripheral region RGN of the furnace body 101 and projecting the upper part upward from the furnace body 101. A connecting member 35 is provided at the opening end of the upper part of the MEA 7. The MEA 7 is configured to introduce air as the second gas into the MEA 7 through the connection member 35 and to discharge water generated by the electrochemical reaction.

  A heater 48 is provided in the peripheral region RGN. The ambient temperature of the peripheral region RGN can be adjusted by using the heater 48 so as to be in the operating temperature range (400 ° C. to 600 ° C.) of the fuel cell 50. Specifically, the furnace body 101 is provided with a thermometer (not shown) for detecting the temperature of the peripheral region RGN. When the detection value of the thermometer is acquired, the control panel 24 controls the power supplied to the heater 48 based on the deviation of the detection value of the thermometer with respect to the set temperature of the peripheral region RGN. Thereby, the peripheral region RGN is maintained in the operating temperature range of the fuel cell 50.

(Configuration of fuel cell)
Hereinafter, the configuration of the fuel cell 50 disposed in the heat treatment furnace 102 of the second embodiment will be described with reference to FIGS. 10 and 11.

  FIG. 10 is a longitudinal sectional view showing the arrangement configuration of the fuel cell 50. 11 is a cross-sectional view taken along line XI-XI in FIG.

  The cylindrical MEA 7 is provided so as to cover the cylindrical solid electrolyte 1, the anode (first electrode / fuel electrode) 5 provided so as to cover the outer surface of the solid electrolyte 1, and the inner surface of the solid electrolyte 1. And a cathode (second electrode / air electrode) 2.

  A hydrogen-containing gas flows as the first gas outside the MEA 7. Moreover, air flows as the second gas inside the MEA 7. The flow path inside the MEA 7 through which the second gas flows is defined as the second gas flow path 91, and the space (peripheral region RGN) inside the furnace body 101 outside the MEA 7 through which the first gas flows is the first gas. It is a flow path.

  As shown in FIG. 10, the cylindrical MEA 7 has a lower end sealed and a gas induction pipe 11 p inserted from the upper end. The lower end portion of the MEA 7 is provided with a sealing portion 94 by extending the solid electrolyte 1 and the cathode 2 located inside the solid electrolyte 1 and providing a bottom portion.

  The gas induction pipe 11p is inserted from the upper end portion of the MEA 7 toward the lower end portion (sealing portion 94). A cylindrical flow path 93 is formed between the inner peripheral surface of the cathode 2 of the MEA 7 and the outer peripheral surface of the gas induction pipe 11p. A porous metal body 11 s is inserted into the cylindrical flow path 93. A cylindrical flow path 93 is formed between the outer peripheral surface of the gas induction pipe 11p and the inner peripheral surface of the cathode 2 while holding the gas induction pipe 11p at the center.

  The second gas is caused to flow in the internal space 92 of the gas induction pipe 11p toward the sealing portion 94, and the second gas is caused to flow out of the gas induction pipe 11p in the vicinity of the sealing portion 94 and is reversed. The passage 93 is configured to flow the second gas in a direction opposite to the flow in the internal space 92. That is, the second gas flow path 91 is configured by the internal space 92 and the cylindrical flow path 93.

  By adopting the above configuration, the second gas flow path 91 can have a distance approximately twice the cylinder length of the MEA 7 in the space inside the MEA 7. Thereby, it heats in the gas induction pipe 11p and can be made to act on MEA7 in the state by which temperature was raised. As a result, the electrochemical reaction in MEA 7 can be promoted.

  The gas induction pipe 11 p is formed of a conductive metal such as stainless steel and functions as a component of the cathode current collector 11. On the other hand, an anode current collector 12 is disposed so as to wrap around the outer surface of the anode 5.

  The cathode current collector 11 includes a silver paste coating layer 11g, a Ni mesh sheet 11a, a porous metal body 11s, and a gas induction pipe 11p. The Ni mesh sheet 11a is configured to be in contact with the cathode 2 on the inner surface side of the MEA 7 through the silver paste coating layer 11g and to conduct electricity from the porous metal body 11s to the gas induction pipe 11p. By providing the silver paste coating layer 11g, the electrical resistance between the cathode 2 and the cathode current collector 11 can be reduced.

  The tip portion W1 of the Ni mesh sheet 11a is conductively connected in the vicinity of the sealing portion 94 so as to be wound around the outer peripheral portion of the gas induction pipe 11p via a band-shaped joining member W2. Therefore, the Ni mesh sheet 11a forms, in parallel, a conductive path called Ni mesh sheet 11a / porous metal body 11s / gas induction pipe 11p and a conductive path called Ni mesh sheet 11a / gas induction pipe 11p. Yes. As a result, the Ni mesh sheet 11a is located on the inner surface of the MEA 7 and can prevent an increase in pressure loss while maintaining a low electrical resistance.

  In addition, in order to reduce the pressure loss of 2nd gas, it is preferable to use the metal plating body which can raise the porosity, for example, cermet, for the porous metal body 11s.

  The anode current collector 12 includes a silver paste coated wiring 12g and a Ni mesh sheet 12a. The Ni mesh sheet 12 a is in contact with the outer surface of the MEA 7 and is electrically conducted to the private power wiring 34.

  The second gas is guided to the vicinity of the sealing portion 94 of the MEA 7 through the gas induction pipe 11p. Since the entire MEA 7 is heated to about 400 ° C. to 600 ° C. by the atmospheric gas, the temperature of the second gas rises while flowing in the gas induction pipe 11p. The second gas flows through the second gas flow path 91 from the internal space 92 into the cylindrical flow path 93, and passes through the gaps between the porous metal body 11s, the Ni mesh sheet 11a, and the silver paste coating layer 11g, and the cathode. Contact 2

A first gas is introduced into the anode 5. The anode 5 decomposes hydrogen contained in the first gas to generate hydrogen ions (H ⁺ ) and electrons (e ⁻ ), and sends the hydrogen ions to the solid electrolyte 1 toward the cathode 2. At the cathode 2, hydrogen ions that have reached through the solid electrolyte 1 react with oxygen to produce water.

  As a result of the electrochemical reaction, electric power is generated, and a current I flows from the cathode current collector 11 to the anode current collector 12 due to a potential difference generated between the anode 5 and the cathode 2. Therefore, by connecting an electrical load (for example, the heaters 46 and 48) between the cathode current collector 11 and the anode current collector 12, electric power can be supplied to the electrical load. As shown in FIG. 10, it is preferable to connect the cathode current collector 11 and the heater 48 with a private power wiring 34 and insert the voltage application unit 32 into the private power wiring 34.

  In the present embodiment, by using the hydrogen ion conductive solid electrolyte 1, water is generated by the reaction of hydrogen ions, oxygen molecules, and electrons at the cathode 2 inside the MEA 7 isolated from the furnace space. Is done. That is, water is generated inside the MEA 7 isolated from the furnace space, while water is not generated outside the MEA 7, that is, inside the furnace body 101. Therefore, as shown in FIG. 7, the fuel cell 50 can be installed in the furnace body 101.

  Thus, according to the batch-type heat treatment furnace 102 according to the second embodiment, in the peripheral region adjacent to the heat treatment region in the furnace space in the horizontal direction and closer to the heat treatment region as seen from the discharge pipe, A fuel cell operable at an ambient temperature lower than the heat treatment temperature is arranged. Thereby, electric power can be generated in the fuel cell using the hydrogen-containing gas used in the reducing atmosphere in the heat treatment. As a result, also in the heat treatment furnace according to the second embodiment, the running cost of the heat treatment furnace can be suppressed as in the first embodiment.

  In addition, since heat generated when the fuel cell generates power can be supplied to the space in the furnace, it contributes to reducing the running cost of the heat treatment furnace.

  Furthermore, the cathode inside the cylindrical hydrogen ion conductive solid electrolyte is configured to be isolated from the space in the furnace, so that the water generated by the electrochemical reaction is released to the atmospheric gas in the furnace. There is no. Therefore, the fuel cell can be installed directly on the furnace body.

  As a result, a heat treatment furnace capable of utilizing the hydrogen-containing gas used as the reducing atmosphere can be realized with a simple apparatus configuration.

  In the first and second embodiments, the configuration in which the electric power generated by the fuel cell is input to an electric load such as a heater is exemplified. However, the electric power may be stored in the power storage device. FIG. 12 is a block diagram showing a configuration of a heat treatment furnace according to a modification of the first embodiment. As shown in FIG. 12, private power wiring 34 is connected to power storage device 300. Thereby, the voltage level of the electric power supplied to the electric load can be stabilized. Further, when the heat treatment furnace is activated, the heaters 40, 42, and 44 can be operated using the electric power stored in the power storage device 300 even when the fuel cell has not yet generated power.

  In the first and second embodiments described above, a configuration having a cylindrical MEA has been described as an example of a fuel cell. However, the present invention can be applied even to a configuration having a plate-like MEA. Is possible. However, by using the MEA of the cylindrical body, water by an electrochemical reaction is generated on the inner surface side of the cylindrical body MEA, so that it is possible to easily avoid the mixing of water vapor with the atmospheric gas in the furnace body. .

  The embodiment disclosed this time is to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

1 Solid electrolyte 2 Cathode (second electrode)
5 Anode (first electrode)
7 MEA
10, 101 Furnace body 11 Cathode current collector 11a, 12a Ni mesh sheet 11g Silver paste coating layer 11k Center conductive rod 11p Gas induction pipe 12 Anode current collector 12g Silver paste coating wiring 13 Carrying in port 14 Carrying out port 15 Protruding part 16 Transporting Belt 18 Introducing pipes 20 and 22 Discharge pipe 24 Control panel 26 External power wiring 30 and 50 Fuel cell 32 Voltage application section 34 Self power wiring 35 Connecting members 40, 42, 44, 46 and 48 Heater 41 Protruding sections 100 and 102 110 Housing 150 Hole 152 Discharge Port 200 Object to be Processed 300 Power Storage Device

Claims (10)

A heat treatment furnace for performing a heat treatment on the workpiece by holding the workpiece at a preset heat treatment temperature,
A furnace space that can accommodate the object to be processed is formed therein, and an inlet that introduces a first gas that is a gas containing hydrogen into the furnace space and a gas that is accommodated in the furnace space. A furnace body formed with a discharge port for discharging
The furnace space has a heat treatment region that is maintained at the heat treatment temperature, and a peripheral region that is disposed around the heat treatment region and is maintained at an ambient temperature that is lower than the heat treatment temperature,
The heat treatment furnace further includes
A heat treatment furnace comprising a hydrogen ion conduction type fuel cell disposed in the peripheral region and operating at the peripheral temperature.   The heat treatment furnace according to claim 1, wherein the fuel cell is disposed in a portion of the peripheral region located vertically above the heat treatment region.   The heat treatment furnace according to claim 1 or 2, wherein the peripheral region has a portion having a shape protruding upward in the furnace main body, and the fuel cell is disposed in the portion.   4. The heat treatment furnace according to claim 3, wherein a portion of the shape protruding upward in the furnace main body becomes smaller as a cross-sectional area in a horizontal plane goes upward.   5. The heat treatment furnace according to claim 3, wherein the discharge port is formed on an inner wall surface of the furnace body facing a portion having a shape protruding upward in the furnace body.   The heat treatment furnace according to any one of claims 1 to 5, wherein the fuel cell is disposed at a position sandwiched between the discharge port and the heat treatment region. The fuel cell includes a membrane electrode assembly,
The membrane electrode complex is
A hydrogen ion conductive solid electrolyte formed in a cylindrical body;
A first electrode formed on an outer periphery of the solid electrolyte and into which the first gas is introduced;
The heat treatment furnace according to any one of claims 1 to 6, further comprising: a second electrode that is formed on an inner peripheral portion of the solid electrolyte and into which a second gas that is a gas containing oxygen is introduced. The membrane electrode assembly has an opening at at least one end of the cylindrical body,
The heat treatment furnace according to claim 7, wherein the fuel cell is disposed such that the one end including the opening of the membrane electrode assembly protrudes outside the furnace body. The heat treatment furnace according to claim 7 or 8, wherein the hydrogen ion conductive solid electrolyte is a perovskite type oxide represented by the following general formula (1).
M2 _a Zr _x Ce _y M3 _(1-xy) O _3-δ (1)
(In the general formula (1), M2 represents at least one +2 valent metal ion selected from Ca, Sr, and Ba, and M3 represents a rare earth other than Ce and Mn, Fe, Co, Ni, Al, Ga. , In represents at least one kind of + 3-valent metal ion selected from In, a is 0.90 or more and 1.05 or less, x and y are each 0 or more and 1.0 or less, and x + y is 0. 75 to 1.0, and δ represents the number of oxygen ion defects in the crystal lattice.)   The heat treatment furnace according to any one of claims 1 to 9, wherein an operating temperature of the fuel cell is 400 ° C or higher and 600 ° C or lower.

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