JP2008304182A - Intake/exhaust method of substrate baking furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake/exhaust system of a substrate baking furnace high in energy efficiency. <P>SOLUTION: A large amount of organic matter is generated from a glass substrate W heated in a furnace body 10. Hot exhaust containing organic matter is discharged from an exhaust opening 14 of the furnace body 10, and is delivered to a circulation passage 20 as an airflow of hot air by a fan 21, and the airflow is heated by a heater 22, thereafter cleaned by a heat-resistant HEPA filter 13 and supplied to an internal space of the furnace body 10 from a blowout port 12 again. A part of the hot exhaust flows in an exhaust pipe 30 and passes through a catalyst unit 31. Thermal decomposition and oxidation decomposition of the organic matter occur at the same time in the catalyst unit 31, most of the organic matter included in the exhaust gas is decomposed, and the outlet-side temperature of the catalyst unit 31 rises around 200°C relative to the inlet-side temperature thereof. The hot exhaust gas resultantly flows into a heat exchanger 50, and heat exchange thereof with intake air is executed, whereby energy efficiency can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate firing furnace that performs a firing process on a glass substrate for a liquid crystal display device, a glass substrate for a plasma display panel (PDP), and a substrate for a thin plate electronic component such as a semiconductor wafer (hereinafter simply referred to as “substrate”). The present invention relates to a supply / exhaust system.

  One of the manufacturing processes of a color filter is a process of baking a glass substrate on which color ink is landed by inkjet. This firing step proceeds by holding the glass substrate for a predetermined time in an air atmosphere in a firing furnace heated to a predetermined firing temperature. Moreover, when forming metal wiring on a glass substrate, a glass substrate is baked in inert gas atmosphere, such as nitrogen gas, in the same baking furnace. In any of the baking treatment steps, a large amount of organic substances are generated and diffused in the atmosphere by volatilization or oxidation of the organic solvent contained in the baking object such as color ink on the glass substrate.

  For this reason, during the firing process, clean hot air is constantly blown into the firing furnace, and exhaust is continuously performed so that organic substances do not stay in the firing furnace. Since a gas containing a large amount of organic matter exhausted from the firing furnace cannot be released to the outside as it is, a process of collecting the organic matter in the exhaust with a scrubber or the like has been performed.

  On the other hand, from the viewpoint of energy saving, an attempt has been made to perform heat exchange between hot air exhausted from the firing furnace and gas newly supplied to the firing furnace. That is, if the exhaust from the firing furnace is treated with a scrubber, the amount of heat energy taken away becomes very large and the energy efficiency is poor, so the exhausted gas and the newly supplied gas are introduced into the heat exchanger, This is an attempt to recover the exhaust heat from the baking furnace by exchanging heat between them.

  If the gas exhausted from the firing furnace is introduced into the heat exchanger as it is, organic substances adhere to the structure in the heat exchanger and clogging occurs. Therefore, the exhaust gas is catalyzed to decompose the organic substances after heat treatment. It is necessary to lead to. For example, Patent Document 1 discloses a technique for guiding the exhaust gas discharged from the furnace to the heat exchanger after the catalyst treatment.

JP 2001-20271 A

  However, even if the gas exhausted from the glass substrate firing furnace is treated with a catalyst, the organic matter cannot be removed sufficiently, and as a result, the heat exchanger is clogged with deposits in a relatively short time, resulting in a long continuous operation. This is not economical because the equipment utilization rate is low.

  For this reason, in many cases, the gas exhausted from the firing furnace is actually processed by a scrubber. In this case, in addition to the low energy efficiency described above, a waste liquid treatment after the treatment is required. There was a problem of high costs.

  This invention is made | formed in view of the said subject, and it aims at providing the supply-exhaust system of a substrate baking furnace with high energy efficiency.

  In order to solve the above-mentioned problems, the invention of claim 1 is characterized in that a furnace body that accommodates a substrate that generates organic matter by being heated and performs a baking process, and hot air discharged from the furnace body is circulated again to A substrate baking furnace having a circulation path for supplying to the furnace body, a fan provided in the circulation path for circulating hot air, and a heater provided in the circulation path for heating the hot air, and branched from the circulation path An exhaust path for discharging hot air, a catalyst unit provided in the exhaust path and having a catalyst for decomposing organic substances contained in the hot air discharged from the circulation path in an atmosphere containing oxygen, and discharged from the catalyst unit And a heat exchanger for exchanging heat between the heated air and the gas newly supplied to the circulation path.

  According to a second aspect of the present invention, in the substrate firing furnace air supply / exhaust system according to the first aspect of the present invention, the substrate firing furnace performs a substrate firing process in an air atmosphere.

  According to a third aspect of the present invention, in the substrate firing furnace supply / exhaust system according to the first aspect of the present invention, an air supply pipe for supplying air or oxygen is connected to the vicinity of the inlet side of the catalyst unit in the exhaust path. It is characterized by.

  According to a fourth aspect of the present invention, in the supply / exhaust system for a substrate firing furnace according to any one of the first to third aspects, the catalyst is a platinum catalyst.

  According to a fifth aspect of the present invention, in the substrate firing furnace supply / exhaust system according to any one of the first to fourth aspects of the present invention, heating from the heater to the gas outlet of the furnace body in the circulation path. The exhaust path is connected to a rear hot air passage region.

  The invention of claim 6 is the substrate firing furnace supply / exhaust system according to the invention of claim 5, wherein the catalyst unit is arranged at a branch connection point where the exhaust path is connected to the circulation path. It is characterized by.

  According to a seventh aspect of the present invention, in the substrate firing furnace supply / exhaust system according to any one of the first to sixth aspects, the number of substrates accommodated in the furnace body and subjected to a firing process is counted. And a flow rate control means for controlling an exhaust amount from the circulation path and an air supply amount to the circulation path according to the number of substrates counted by the counting means.

  Further, the invention according to claim 8 is the substrate supply furnace exhaust system according to any one of claims 1 to 7, wherein a new supply air is directly added to the circulation path without passing through the heat exchanger. It further has a bypass path for performing.

  The invention according to claim 9 is the supply / exhaust system for a substrate baking furnace according to the invention according to claim 8, wherein the pressure of hot air discharged from the catalyst unit and flowing into the heat exchanger and the heat exchanger are discharged. Pressure loss detecting means for detecting a pressure difference with the pressure of the hot exhaust gas, and an air supply path switching means for operating the bypass path when the pressure difference becomes a predetermined value or more. .

  According to the present invention, a catalyst unit having a catalyst for decomposing an organic substance contained in hot air discharged from the circulation path in an atmosphere containing oxygen, and the hot air discharged from the catalyst unit and the circulation path are newly supplied. A heat exchanger for exchanging heat with gas, so that pyrolysis and oxidative decomposition of organic matter occur simultaneously in the catalyst unit, and as a result, the outlet side temperature rises higher than the inlet side temperature of the catalyst unit. High-temperature hot air flows into the heat exchanger, and energy efficiency in the air supply / exhaust system can be increased.

  In particular, according to the invention of claim 5, since the exhaust path is connected to the heated hot air passage area from the heater to the gas outlet of the furnace body in the circulation path, the hot hot air immediately after being heated by the heater is The organic matter immediately flows into the catalyst unit, and the organic matter contained in the hot air is efficiently decomposed, so that most of the organic matter is decomposed. As a result, it is possible to minimize the adhesion of organic substances to the internal structure of the heat exchanger, so that the heat exchanger can be stably operated for a long time.

  In particular, according to the invention of claim 7, in order to control the exhaust amount from the circulation path and the air supply amount to the circulation path in accordance with the number of substrates accommodated in the furnace body and performing the firing process, the catalyst unit The concentration of the organic substance contained in the exhaust gas flowing into the gas can be made substantially constant, and the catalyst unit can be operated stably.

  In particular, according to the invention of claim 8, since a bypass path for supplying new air directly to the circulation path without passing through the heat exchanger is provided, heat exchange is performed by flowing a newly supplied gas to the bypass path. Is stopped and the internal structure of the heat exchanger is heated to remove the attached organic matter.

  In particular, according to the invention of claim 9, when the pressure difference between the pressure of the hot air discharged from the catalyst unit and flowing into the heat exchanger and the pressure of the hot exhaust discharged from the heat exchanger becomes a predetermined value or more. Since the bypass path is operated in this manner, the bypass path is activated when a certain amount of organic matter is attached to the internal structure of the heat exchanger, and effective organic substance removal can be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing a main configuration of a substrate firing furnace air supply and exhaust system according to the present invention. FIG. 2 is a cross-sectional view of the substrate baking furnace as viewed from above. The substrate baking furnace 1 is a hot air furnace for baking a square glass substrate W (a substrate referred to in the present invention) on which color ink or the like is placed. The substrate baking furnace 1 includes a furnace body 10 that contains a glass substrate W and performs a firing process, a circulation path 20 that circulates hot air discharged from the furnace body 10 and supplies the hot air to the furnace body 10 again, and a circulation path 20. A fan 21 that is provided and circulates hot air and a heater 22 that is provided in the circulation path 20 and heats the hot air are provided.

  The furnace body 10 is a main body of the substrate baking furnace 1 and is a housing that can accommodate the glass substrates W in multiple stages (in this embodiment, 40 stages). The inside of the furnace body 10 is a heat treatment space 19 having a substantially quadrangular prism shape. A number of forks (not shown) are provided on the inner wall surface of the furnace body 10. Each fork extends in the horizontal direction from the inner wall surface of the furnace body 10 toward the heat treatment space 19. A plurality of forks arranged in the horizontal direction constitute a single shelf, and 40 such shelves are formed. It is possible to place one glass substrate W in a horizontal posture on each shelf.

  A louver-type shutter 11 is provided on the front side of the furnace body 10 (left side in FIG. 2). The shutter 11 is configured by laminating a plurality of louvers in multiple stages. Each louver is provided with an elevating drive mechanism (not shown), and can be moved up and down for each louver. When the unillustrated transfer robot carries the glass substrate W into and out of the substrate baking furnace 1, the position is almost the same as that of the shelf so that only the portion facing the loading / unloading destination shelf is an access opening. The louver rises. If it does in this way, the opening at the time of carrying in / out of the glass substrate W can be made into the minimum necessary, and the leakage of the heat energy accompanying carrying in / out can be suppressed to the minimum. When driving the louver at the lower part of the shutter 11, the upper louver is also driven in conjunction with the louver. Therefore, it is necessary to provide a drive mechanism that can obtain a larger torque than the lower louver. is there.

  On the side surface of the furnace body 10, a blowout port 12 for supplying hot air to the heat treatment space 19 and an exhaust port 14 for exhausting the hot air are provided opposite to each other. That is, in the substrate firing furnace 1 of the present embodiment, the hot air supplied from one side surface of the furnace body 10 flows in the heat treatment space 19 in the horizontal direction along the surface of the glass substrate W and flows into the opposite side surface. is there. The blowout port 12 and the exhaust port 14 are provided at a height position corresponding to the entire multistage shelf that accommodates at least the glass substrate W on the inner wall surface of the furnace body 10. For this reason, hot air can be supplied uniformly to the glass substrate W accommodated in the furnace body 10 to perform a uniform heat treatment.

  A high-temperature heat-resistant HEPA filter 13 is provided at the outlet 12. The heat-resistant HEPA filter 13 removes particles contained in the hot air that has been blown through the circulation path 20 to produce clean hot air. On the other hand, the exhaust port 14 is provided with a punching metal 15 having a large number of ventilation holes arranged on the entire surface. Hot air flowing through the heat treatment space 19 is exhausted from the vent hole of the punching metal 15 to the circulation path 20. In addition, the wall surface facing the shutter 11 among the inner wall surfaces of the furnace body 10 is a furnace wall formed of a member without a vent hole. Moreover, you may make it arrange | position the thing similar to the punching metal 15 in two directions except the shutter 11 and the wall surface facing it among the inner wall surfaces of the furnace body 10. FIG.

  The circulation path 20 is a flow path through which gas can pass through the exhaust port 14 and the blowout port 12 of the furnace body 10, and is formed between the outer wall surface of the furnace body 10 and the inner wall surface of the heat-resistant wall that covers the entire substrate baking furnace 1. It is configured with a space formed between them. A circulation path 20 of the substrate baking furnace 1 is provided with a fan 21 and a heater 22. In the present embodiment, a fan 21 is provided on the upstream side of the circulation path 20, and a heater 22 is provided on the downstream side. The upstream side of the circulation path 20 is a side close to the exhaust port 14 of the furnace body 10, and conversely, the downstream side is a side close to the blowout port 12. Specifically, as shown in FIG. 2, the fan 21 is installed at a site that is close to and opposed to the exhaust port 14. The fan 21 includes a motor 21a and swirl vanes 21b. When the motor 21a rotates the swirl vanes 21b, an air flow (that is, blown out from the exhaust port 14) flows from the upstream side to the downstream side in the circulation path 20. An air flow toward the mouth 12) occurs. In FIG. 2, two fans 21 are provided, but the number of fans 21 installed is arbitrary.

  The heater 22 is installed between the furnace wall facing the shutter 11 of the furnace body 10 and the heat-resistant wall of the substrate baking furnace 1. The heater 22 reheats the hot air flowing through the circulation path 20. In the substrate baking furnace 1 of the present embodiment, the air flow sent out by the upstream fan 21 of the circulation path 20 is heated by the downstream heater 22 and then purified by the heat-resistant HEPA filter 13 and then the heat treatment space from the outlet 12. 19 will be supplied. And the hot air discharged | emitted from the exhaust port 14 of the furnace body 10 is again sent by the fan 21 to the downstream of the circulation path 20. FIG. In FIG. 2, three heaters 22 are provided, but the number of heaters 22 installed is arbitrary.

  As described above, the substrate baking furnace 1 is configured as a so-called hot air circulation type baking furnace, and when the glass substrate W is heat-treated, the hot air exhausted from the furnace body 10 is constantly reheated and returned. . By constantly supplying new hot air to the furnace body 10, the temperature of the heat treatment space 19 is maintained at a predetermined firing temperature (in this embodiment, set in a range from 200 ° C. to 300 ° C. according to the treatment). Yes.

  By the way, as described above, when the glass substrate W is heated, an organic solvent contained in an object to be fired (color ink or the like) on the glass substrate W is volatilized or oxidized, so that many organic substances are generated. Since an air flow of hot air is constantly formed in the heat treatment space 19, the organic matter released from the glass substrate W flows into the circulation path 20 from the exhaust port 14 together with the air flow. If the hot air circulation system of the substrate firing furnace 1 is completely closed, the firing of new organic matter is suppressed by a large amount of organic matter, or the heat-resistant HEPA filter 13 is rapidly clogged and deteriorated. In the embodiment, new gas is supplied to the circulation path 20 and exhausted from the circulation path 20.

  As an exhaust path, an exhaust pipe 30 is connected in communication with the heated hot air passage area 20 a from the heater 22 to the gas outlet 12 of the furnace body 10 in the circulation path 20. A catalyst unit 31 is disposed in the exhaust pipe 30. The catalyst unit 31 contains a platinum (Pt) catalyst for decomposing organic substances. Here, in this embodiment, as shown in FIG. 2, the catalyst unit 31 is disposed immediately after the heater 22 in the circulation path 20 so as to face the heated hot air passage region 20 a. That is, the catalyst unit 31 is arranged at a branch connection point formed in the housing of the substrate baking furnace 1 and where the exhaust pipe 30 is connected to the circulation path 20.

  The other end of the exhaust pipe 30 (the end opposite to the circulation path 20) is connected to the heat exchanger 50. The heat exchanger 50 of the present embodiment is a heat storage heat exchanger of a type in which a heat storage unit rotates, and heat exchange is performed by alternately contacting a high-temperature gas and a low-temperature gas to the rotating heat storage unit element. It is. As this type of heat exchanger, for example, a Jungstrom (registered trademark) heat exchanger can be used.

  In addition to the catalyst unit 31, a flow rate adjusting valve 32 and an inlet pressure gauge 33 are inserted in the exhaust pipe 30. The flow rate adjustment valve 32 adjusts the exhaust flow rate flowing through the exhaust pipe 30. The inlet-side pressure gauge 33 detects the pressure of hot air that is discharged from the catalyst unit 31 and flows into the heat exchanger 50. An outlet pressure gauge 34 is inserted in the heat exhaust path 30a that guides the exhaust gas discharged from the heat exchanger 50 to a heat exhaust duct or the like. The outlet side pressure gauge 34 detects the pressure of the hot exhaust discharged from the heat exchanger 50.

  On the other hand, as an air supply path to the circulation path 20, an air supply pipe 40 is connected in communication with a region near the fan 21 in the circulation path 20. More specifically, the gas supplied from the air supply pipe 40 is configured to flow around the axis of the swirl vane 21b. A flow rate adjustment valve 42 is inserted in the air supply pipe 40. The flow rate adjustment valve 42 adjusts the supply air flow rate flowing through the supply pipe 40. The other end of the air supply pipe 40 (the side opposite to the circulation path 20) is bifurcated. One branch pipe 40a is connected to the heat exchanger 50 and the other branch pipe is connected to the heat exchanger 50. The bypass pipe 40b does not go through.

  A three-way valve 44 is provided in the supply path 40 c for supplying new gas (inert gas such as air or nitrogen gas) to the heat exchanger 50. A bypass pipe 40b is also connected to the three-way valve 44. The three-way valve 44 selects whether to supply newly supplied gas to the supply pipe 40 via the heat exchanger 50 or to supply the supply pipe 40 via the bypass pipe 40b without passing through the heat exchanger 50. Switch. When the newly supplied gas passes through the bypass pipe 40b, the bypass pipe 40b functions as a bypass path that directly supplies new air to the circulation path 20 without passing through the heat exchanger 50. Regardless of which path the newly supplied gas passes through, the gas finally flows into the supply pipe 40, and the supply flow rate is adjusted by the flow rate adjustment valve 42.

  The heat exchanger 50 performs heat exchange between the hot air discharged from the catalyst unit 31 and the gas newly supplied to the circulation path 20. The heat exchanger 50 of the present embodiment is a regenerative heat exchanger, and hot hot air discharged from the catalyst unit 31 and fed from the exhaust pipe 30 and relatively cool gas fed from the supply path 40c. Are alternately brought into contact with the element of the heat storage section, and the heat retained by the discharged hot air is transmitted to the newly supplied gas through the element.

  Moreover, the control part 90 is provided in the air supply / exhaust system of this embodiment. The configuration of the control unit 90 as hardware is the same as that of a general computer. That is, the control unit 90 stores a CPU that performs various arithmetic processes, a ROM that is a read-only memory that stores basic programs, a RAM that is a readable and writable memory that stores various information, and control applications and data. It is equipped with a magnetic disk. The controller 90 is electrically connected to the flow rate adjusting valves 32 and 42 and the three-way valve 44, and controls their operations. The control unit 90 also controls the operation of each operation unit (for example, the fan 21, the heater 22, and the lifting / lowering drive mechanism of the shutter 11) of the substrate baking furnace 1. Further, the control unit 90 is also electrically connected to the entry-side pressure gauge 33, the exit-side pressure gauge 34, and a counter 91 of the substrate baking furnace 1 described later, and receives detection signals from these sensors.

  Next, the operation | movement content in the air supply / exhaust system of the substrate baking furnace 1 which has the said structure is demonstrated. First, during the firing process, the transfer robot sequentially carries the glass substrates W into the furnace body 10 at regular intervals and passes them to a shelf on a predetermined stage. The glass substrate W placed on the fork constituting the shelf is heated to the firing temperature by the hot air from the outlet 12. Then, the glass substrate W after a predetermined baking time has passed in the heat treatment space 19 is unloaded by the transfer robot. When the object to be fired placed on the glass substrate W is a color ink as in the present embodiment, the heat treatment space 19 is in an air atmosphere (that is, heated air is circulated). When the ink is for wiring, an inert gas atmosphere such as nitrogen gas is used (that is, the heated inert gas is circulated).

  The hot exhaust discharged from the exhaust port 14 of the furnace body 10 is sent out as a hot air stream by the fan 21 to the circulation path 20, and the air stream is heated by the heater 22 and then purified by the heat-resistant HEPA filter 13 and from the outlet 12. The heat treatment space 19 is supplied again. The heater 22 is controlled by the controller 90 and heats the airflow sent out by the fan 21 to a temperature corresponding to the firing temperature. In addition, a temperature sensor is provided in the heat treatment space 19 of the furnace body 10, and the control unit 90 feedback-controls the heater 22 so that the heat treatment space 19 becomes a temperature corresponding to the firing temperature based on the measurement result of the temperature sensor. Anyway.

  In the above circulation process, the hot air heated by the heater 22 is branched into an air flow toward the outlet 12 and an air flow flowing into the exhaust pipe 30. A catalyst unit 31 is provided in the exhaust pipe 30 so as to face the hot air passage region 20a after heating. Therefore, part of the hot air that is several tens of degrees higher than the firing temperature immediately after being heated by the heater 22 immediately flows into the catalyst unit 31.

  When the hot air immediately after being heated by the heater 22 immediately flows into the catalyst unit 31 and comes into contact with the platinum catalyst, the platinum catalyst also becomes high temperature, and the organic matter contained in the hot air discharged from the circulation path 20 is decomposed with high efficiency. Will be. At this time, when the glass substrate W is fired in an inert gas atmosphere, the organic substance is thermally decomposed in the catalyst unit 31, and in the case where it is fired in an air atmosphere, Thus, thermal decomposition and oxidative decomposition of organic matter occur simultaneously. As a result, most of the organic substances contained in the hot air discharged from the circulation path 20 to the exhaust pipe 30 are decomposed into harmless substances.

  Hot air that has been decomposed and purified by the catalyst unit 31 through the organic substance passes through the flow rate adjusting valve 32 and flows into the heat exchanger 50. On the other hand, when the normal baking process is performed on the glass substrate W, the three-way valve 44 is set so that the newly supplied gas passes through the heat exchanger 50. That is, the bypass pipe 40b is closed. Thereby, in the heat exchanger 50, heat exchange is performed between the high-temperature hot air discharged from the catalyst unit 31 and the low-temperature gas newly supplied to the circulation path 20, and the temperature of the exhaust gas is reduced and supplied. The temperature of the gas rises. At this time, since most of the organic substances contained in the hot air discharged from the circulation path 20 to the exhaust pipe 30 are decomposed, the adhesion of organic substances to elements and the like in the heat exchanger 50 is very small, and the heat exchanger 50 clogging can be prevented.

  Exhaust gas whose temperature has decreased after passing through the heat exchanger 50 is discharged to an external exhaust heat duct or the like through the heat exhaust path 30a. Of course, organic matter is hardly contained in the exhaust airflow. On the other hand, the supply gas whose temperature has risen after passing through the heat exchanger 50 flows into the supply tube 40 through the branch pipe 40a, and flows into the circulation path 20 through the flow rate adjustment valve 42. Since the newly supplied gas flows into the vicinity of the fan 21 in the circulation path 20 (that is, upstream of the heater 22), there is no possibility of lowering the temperature of the hot air blown into the heat treatment space 19. Then, the heat treatment space 19 is supplied from the outlet 12.

  In this way, the hot hot air immediately after being heated by the heater 22 immediately flows into the catalyst unit 31 and the organic matter contained in the hot air is efficiently decomposed, so that most of the organic matter is decomposed. . As a result, since organic substances are prevented from adhering to the internal structure of the heat exchanger 50 to a minimum, the heat exchanger 50 can be stably operated for a long period of time. If heat exchange between the supply gas and the exhaust gas can be performed using the heat exchanger 50, the energy efficiency in the supply / exhaust system of the substrate baking furnace 1 can be increased.

  In particular, when the firing process is performed in an air atmosphere, thermal decomposition and oxidative decomposition of organic matter occur simultaneously in the catalyst unit 31, and as a result, the inlet side temperature of the catalyst unit 31 is a temperature that approximates the firing temperature. It was found that the temperature on the outlet side increased by about 200 ° C. at the outlet side temperature. Generally, in a heat exchanger, the higher the temperature of the high-temperature side fluid, the better the thermal efficiency, and the higher the exhaust gas having a temperature of about 400 ° C. or higher flows into the heat exchanger 50, the better the energy efficiency. Can do. Rather, when viewed from the substrate baking furnace 1, decomposition heat is added by the catalyst unit 31, so that more heat than that released by the exhaust can be obtained by supplying air.

  Further, the substrate baking furnace 1 is provided with a counter 91 that measures the number of glass substrates W that are accommodated in the furnace body 10 and subjected to a baking process. The counter 91 may be a hardware counting mechanism such as an optical sensor that detects whether or not the glass substrate W is placed on each shelf, or is accommodated in the furnace body 10 from a processing recipe. Software that recognizes the number of glass substrates W may be used. The number of glass substrates W being processed counted by the counter 91 is transmitted to the control unit 90 as an electrical signal. Then, the control unit 90 controls the flow rate adjustment valve 32 and the flow rate adjustment valve 42 according to the number of glass substrates W counted by the counter 91, and the exhaust amount from the circulation path 20 and the supply amount to the circulation path 20. Adjust. Specifically, the larger the number of glass substrates W on which the firing process is performed, the larger the amount of organic matter generated in proportion thereto, so the exhaust amount from the circulation path 20 and the air supply amount to the circulation path 20 The controller 90 controls the flow rate adjustment valves 32 and 42 so that the flow rate increases. In this way, the air concentration of the organic matter contained in the exhaust gas flowing into the catalyst unit 31 becomes substantially constant, so that the platinum catalyst functions stably. In addition, when the number of glass substrates W on which the baking process is performed is small, the amount of air supply / exhaust is reduced to reduce the heat energy taken away from the circulation path 20 of the substrate baking furnace 1, and conversely the number of glass substrates W is reduced. When the amount is large, the generated organic matter can be discharged as early as possible by increasing the supply / exhaust amount.

  Further, the control unit 90 controls the flow rate adjusting valves 32 and 42 so that the exhaust amount from the circulation path 20 is slightly larger than the supply amount to the circulation path 20. In this way, the inside of the furnace body 10 is constantly in a slightly negative pressure state with respect to the outside air, and even when the shutter 11 is opened during loading / unloading of the glass substrate W, leakage of organic substances to the outside of the furnace and heat dissipation are performed. Can be suppressed.

  According to the air supply / exhaust system of the present embodiment, the organic matter hardly adheres to the internal structure such as the element of the heat exchanger 50, but the organic matter adheres gradually but continuously during a long period of operation. Is inevitable. When organic matter adheres to the internal structure of the heat exchanger 50, a so-called clogged state occurs and pressure loss occurs. For this reason, based on the pressure detection results of the inlet side pressure gauge 33 and the outlet side pressure gauge 34, the control unit 90 discharges from the heat exchanger 50 and the pressure of hot air discharged from the catalyst unit 31 and flowing into the heat exchanger 50. The pressure difference with the pressure of the heat exhaust is detected. And when the pressure difference becomes more than a predetermined threshold value, the control unit 90 switches the three-way valve 44 so that the newly supplied gas passes through the bypass pipe 40b. In this state, the newly supplied gas does not pass through the heat exchanger 50. Then, the high-temperature exhaust gas continues to flow into the heat exchanger 50, but the low-temperature gas is not supplied, so heat exchange does not occur, and the temperature of the elements of the heat exchanger 50 increases. As a result, the organic matter adhering to the internal structure of the heat exchanger 50 is sublimated again by heat and discharged. That is, by supplying a newly supplied gas to the bypass pipe 40b, organic substances are removed from the internal structure of the heat exchanger 50, and the cleaning process is executed. However, since no heat exchange is performed at the time of this cleaning process and energy efficiency is lowered, a gas newly supplied when the pressure difference between the inlet pressure gauge 33 and the outlet pressure gauge 34 becomes less than a predetermined value. , The control unit 90 switches the three-way valve 44 so as to pass through the heat exchanger 50 again.

  While the embodiments of the present invention have been described above, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention. For example, the air supply / exhaust system according to the present invention may be as shown in FIG. In FIG. 3, the same elements as those in FIG. 3 is different from that in FIG. 1 in that an air supply pipe 60 for supplying air (or oxygen) to the catalyst unit 31 is provided. The air supply pipe 60 is connected to the vicinity of the inlet side of the catalyst unit 31 of the exhaust pipe 30 through the heat exchanger 50. In order to realize such a configuration, in the system of FIG. 3, the catalyst unit 31 is disposed at a position slightly away from the heated hot air passage region 20 a in the exhaust pipe 30. That is, the air supply pipe 60 is connected in communication between the branch connection point where the exhaust pipe 30 is connected to the circulation path 20 and the catalyst unit 31.

  In the system of FIG. 3, an inert gas such as nitrogen gas is supplied from the air supply pipe 40, and the inside of the circulation path 20 and the furnace body 10 is an inert gas atmosphere. The air (or oxygen) heated by the heat exchanger 50 is supplied from the air supply pipe 60 in a different path to the vicinity of the inlet side of the catalyst unit 31 of the exhaust pipe 30. Since the air is supplied at the most upstream position of the exhaust pipe 30, the air is prevented from flowing back into the circulation path 20 having an inert gas atmosphere. When high-temperature air is supplied to the vicinity of the inlet side of the catalyst unit 31, thermal decomposition and oxidative decomposition of organic matter occur simultaneously in the catalyst unit 31 as in the case of performing the firing treatment in an air atmosphere. The outlet side temperature is higher than the inlet side temperature. As a result, the heat exchange efficiency in the heat exchanger 50 can be improved and the energy efficiency can be made better. Needless to say, the system of FIG. 3 can also be applied to an apparatus in which air is supplied from the air supply pipe 40 and the glass substrate W is fired in the atmosphere.

  Further, the configuration of the circulation path 20 is not limited to the form as shown in FIG. 2, and is a flow path through which the gas can pass between the exhaust port 14 and the outlet 12 of the furnace body 10, and the upstream side thereof. The fan 21 may be provided on the downstream side and the heater 22 may be provided on the downstream side. Therefore, for example, the heater 22 may be arranged at the bottom of the furnace body 10 so that the outer wall panel of the substrate baking furnace 1 can be easily opened.

  Further, the cleaning process of the heat exchanger 50 using the bypass pipe 40b may be executed at regular intervals regardless of the pressure difference between the inlet side pressure gauge 33 and the outlet side pressure gauge 34.

  In the cleaning process of the heat exchanger 50, the bypass pipe 40b is used, and further, for example, a superheated steam nozzle for jetting high-temperature and high-pressure superheated steam provided separately at the exhaust inlet is used in a shorter time. You may raise the level.

  The heat exchanger 50 is not limited to a heat storage type heat exchanger, and may be a plate type heat exchanger having a flow path through which supply / exhaust air alternately passes.

  Further, the number of glass substrates W that can be accommodated in the furnace body 10 of the substrate baking furnace 1 is not limited to 40, and may be any number.

  Further, the substrate to be baked by the substrate baking furnace provided with the air supply / exhaust system according to the present invention is not limited to the glass substrate W, but may be a semiconductor wafer. The ink to be fired may be for banks, ITO electrodes (indium tin oxide transparent electrodes), or the like.

It is a schematic diagram which shows the principal part structure of the air supply / exhaust system of the substrate baking furnace which concerns on this invention. It is sectional drawing which looked at the substrate baking furnace from upper direction. It is a schematic diagram which shows the other example of the supply / exhaust system of the substrate baking furnace which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate baking furnace 10 Furnace body 12 Outlet 13 Heat-resistant HEPA filter 14 Exhaust port 20 Circulation path 20a Heated hot air passage area 21 Fan 22 Heater 30 Exhaust pipe 31 Catalyst unit 32, 42 Flow control valve 33 Inlet side pressure gauge 34 Outlet side Pressure gauge 40 Air supply pipe 40b Bypass pipe 50 Heat exchanger 90 Control unit 91 Counter W Glass substrate

Claims (9)

A furnace body that contains a substrate that generates organic matter by being heated and performs a firing process, a circulation path that circulates hot air discharged from the furnace body and supplies it to the furnace body again, and a circulation path that is provided in the circulation path A substrate firing furnace having a fan that circulates hot air and a heater that is provided in the circulation path and heats the hot air;
An exhaust path branched from the circulation path to discharge hot air;
A catalyst unit having a catalyst that is provided in the exhaust path and decomposes an organic substance contained in the hot air discharged from the circulation path in an atmosphere containing oxygen;
A heat exchanger for exchanging heat between the hot air discharged from the catalyst unit and the gas newly supplied to the circulation path;
An air supply / exhaust system for a substrate firing furnace. In the substrate baking furnace supply and exhaust system according to claim 1,
The substrate firing furnace is a substrate firing furnace supply / exhaust system, wherein the substrate firing process is performed in an air atmosphere. In the substrate baking furnace supply and exhaust system according to claim 1,
An air supply / exhaust system for a substrate firing furnace, wherein an air supply pipe for supplying air or oxygen is connected to the vicinity of an inlet side of the catalyst unit in the exhaust path. In the supply / exhaust system of the substrate baking furnace according to any one of claims 1 to 3,
A supply / exhaust system for a substrate firing furnace, wherein the catalyst is a platinum catalyst. In the supply and exhaust system of the substrate baking furnace according to any one of claims 1 to 4,
An air supply / exhaust system for a substrate firing furnace, wherein the exhaust path is connected to a heated hot air passage region from the heater to a gas outlet of the furnace body in the circulation path. In the supply and exhaust system of the substrate baking furnace according to claim 5,
The substrate firing furnace supply / exhaust system, wherein the catalyst unit is disposed at a branch connection point where the exhaust path is connected to the circulation path. The supply / exhaust system for a substrate firing furnace according to any one of claims 1 to 6,
A counting means for counting the number of substrates accommodated in the furnace body and performing a firing process;
Flow rate control means for controlling the amount of exhaust from the circulation path and the amount of air supplied to the circulation path in accordance with the number of substrates counted by the counting means;
An air supply / exhaust system for a substrate baking furnace, further comprising: In the supply and exhaust system of the substrate baking furnace according to any one of claims 1 to 7,
An air supply / exhaust system for a substrate firing furnace, further comprising a bypass path for supplying new air directly to the circulation path without going through the heat exchanger. The supply / exhaust system for a substrate baking furnace according to claim 8,
Pressure loss detecting means for detecting a pressure difference between the pressure of hot air discharged from the catalyst unit and flowing into the heat exchanger and the pressure of hot exhaust discharged from the heat exchanger;
An air supply path switching means for operating the bypass path when the pressure difference becomes a predetermined value or more;
An air supply / exhaust system for a substrate baking furnace, further comprising:

Images