Gas replacement method and heating device

Abstract

To provide a gas replacement method for a heating device, which is capable of efficiently discharging a gas to be removed from a heating vessel, and a heating device.SOLUTION: In a heating device 10 having a heating vessel 12 for storing a molding material A to be heated, a gas replacement method for replacing gas in the heating vessel 12 includes: performing a pressure swing so that a pressure inside the heating vessel 12 becomes a high pressure P1 exceeding a saturated vapor pressure P0 of a replacement gas inside the heating vessel 12 and a low pressure P2 lower than the saturated vapor pressure P0; and replacing the gas in the heating vessel 12 with the replacement gas.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a gas replacement method and a heating device to which the gas replacement method is applied. [Background technology]

[0002] In a heating device for heating various molding materials, it is necessary to adjust the internal environment of the device before heating. For example, in Patent Document 1, a gas containing nitrogen gas and superheated steam is injected into the heating chamber to replace the internal gas, thereby eliminating unnecessary oxygen gas in the heating chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6778698 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a replacement gas is supplied for the gas replacement process, the flow in the heating container becomes steady. Therefore, a stagnation region of the flow occurs, and the gas replacement may not be performed smoothly compared to the flow rate of the replacement gas supplied. In addition, condensation of the replacement gas may occur on the surface of the molding material, which is the object to be heated, and the gas to be removed may be trapped on the surface of the molding material, making it difficult to discharge the gas to be removed. Because such a discharge obstruction of the gas to be removed occurs, it may be necessary to use a large amount of replacement gas to discharge the gas to be removed.

[0005] In view of the above, an object of the present disclosure is to provide a gas replacement method for a heating device, and a heating device, which are capable of efficiently discharging a gas to be removed from a heating container. [Means for solving the problem]

[0006] In order to achieve the above object, a gas replacement method according to a first aspect is a gas replacement method in a heating device having a heating container that stores a molding material to be heated, which replaces gas in the heating container, and replaces the gas in the heating container with the replacement gas while performing a pressure swing so that the pressure in the heating container becomes a high pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container and a low pressure that is lower than the saturated vapor pressure.

[0007] In the gas replacement method according to the first aspect, a pressure swing is performed so that the pressure in the heating container is between a high pressure and a low pressure. The high pressure is a pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container, and the low pressure is set to a pressure that is lower than the saturated vapor pressure.

[0008] When supplying replacement gas, there is a concern that the gas flow in the heating vessel will become steady and stagnation areas will occur. However, by implementing a pressure swing in the heating vessel in this manner, the gas in the heating vessel can be replaced while eliminating stagnation areas.

[0009] In addition, the replacement gas may condense on the surface of the molding material to be heated, covering the gas to be removed, which may hinder the removal of the gas. Even in this case, the replacement gas can be re-evaporated and the gas to be removed can be removed by lowering the pressure in the heating container below the saturated vapor pressure.

[0010] In this way, the stagnation of the flow is eliminated while the condensed replacement gas is evaporated, thereby enabling efficient gas replacement.

[0011] In the gas replacement method according to the second aspect, the pressure swing is performed by turning on and off the supply of the replacement gas.

[0012] In this way, the pressure swing is performed by turning on and off the supply of the replacement gas, so that the supply of the replacement gas and the high pressure can be easily linked.

[0013] In the gas replacement method according to a third aspect, the low pressure is atmospheric pressure.

[0014] In this way, by setting the low pressure of the pressure swing to atmospheric pressure, the amplitude of the pressure swing can be easily increased without using any pressure reducing device.

[0015] In the gas replacement method according to the fourth aspect, the pressure swing is performed with a cycle time that is less than ⅓ of the replacement time, where the replacement time is the time from the start to the completion of the gas replacement.

[0016] According to the gas replacement method of the fourth aspect, three or more pressure swings are performed from the start to the completion of gas replacement. If the number of pressure swings is small, the effect is small. By performing the pressure swing three or more times, gas replacement can be performed efficiently.

[0017] The heating device of the fifth aspect includes a heating container that stores a molding material to be heated and has a gas supply port and a gas exhaust port, a replacement gas supply unit that supplies a replacement gas from the gas supply port to the heating container, and a pressure control unit that implements a pressure swing such that the pressure inside the heating container becomes a high pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container, and a low pressure that is lower than the saturated vapor pressure.

[0018] In the heating device according to the fifth aspect, the pressure control unit performs a pressure swing so that the pressure in the heating container becomes a high pressure and a low pressure. The high pressure is a pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container, and the low pressure is set to a pressure that is lower than the saturated vapor pressure.

[0019] When supplying replacement gas, there is a concern that the gas flow within the heating vessel will become steady and stagnation areas will occur, but by implementing a pressure swing within the heating vessel in this manner, stagnation of the flow can be suppressed.

[0020] In addition, the replacement gas may condense on the surface of the molding material to be heated, covering the gas to be removed, which may hinder the removal of the gas. Even in this case, the replacement gas can be re-evaporated and the gas to be removed can be removed by lowering the pressure in the heating container below the saturated vapor pressure, thereby enabling efficient gas replacement.

[0021] In the heating device according to a sixth aspect, the pressure control unit performs the pressure swing by turning on / off the supply of the replacement gas by the replacement gas supply unit.

[0022] In this manner, pressure swing can be easily achieved by turning on and off the supply of replacement gas.

[0023] In the heating device according to a seventh aspect, the pressure control section performs the pressure swing so that the low pressure becomes atmospheric pressure.

[0024] In this way, by setting the low pressure of the pressure swing to atmospheric pressure, the amplitude of the pressure swing can be easily increased without using any pressure reducing device.

[0025] In the heating device according to an eighth aspect, the pressure control unit performs the pressure swing so that the pressure swing is performed in a cycle time that is less than 1 / 3 of the replacement time, where the replacement time is the time from the start to the completion of gas replacement.

[0026] According to the heating device of the eighth aspect, three or more pressure swings are performed from the start to the completion of gas replacement. If the number of pressure swings is small, the effect is small. By performing the pressure swing three or more times, gas replacement can be performed efficiently. Effect of the Invention

[0027] According to the gas replacement method and heating device of the present disclosure, the gas to be removed can be efficiently discharged from the heating container. [Brief description of the drawings]

[0028] [Figure 1] 1 is a schematic configuration diagram of a heating device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic block diagram of a control system of the heating device according to the present embodiment. [Diagram 3] 5 is a timing chart showing the relationship between the pretreatment time and the pressure in the heating chamber of the heating device according to the present embodiment. [Figure 4] 5 is a flowchart of a gas replacement process executed by a control unit of the heating device according to the present embodiment. [Diagram 5] 5 is a diagram showing a state of gas in a heating container of the heating device according to the embodiment. FIG. [Figure 6] 5A to 5D are diagrams showing changes in the state of gas in a heating container when a pressure swing is performed in the heating device according to the present embodiment. [Figure 7] 10 is a timing chart showing the relationship between the pretreatment time and the pressure in the heating chamber in an example of the heating device according to the present embodiment. [Figure 8] 11 is a graph showing a comparison of the amount of required steam in an example of the heating device according to the present embodiment with a comparative example. [Figure 9] 13 is a graph showing the relationship between the remaining oxygen concentration and the integrated amount of steam supply when the cycle time C0 is changed in an example of the heating device according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, an embodiment of a gas replacement method and a heating device according to the present disclosure will be described in detail with reference to the drawings. The heating device according to the present disclosure is used to heat molding materials such as resin and rubber. For example, it is used in the vulcanization process of tires and the heating process of carbon fiber reinforced resin before compression molding.

[0030] As shown in Fig. 1, the heating device 10 includes a cylindrical heating container 12. A heating chamber 13 for storing a molding material A is formed inside the heating container 12. The heating container 12 has an opening / closing part (not shown) that can be opened and closed, and the molding material A is put in and taken out through the opening / closing part. In Fig. 1, the upward direction is indicated by UP, and the downward direction is indicated by DN.

[0031] One end of a supply pipe 20 is connected to the heating container 12. A supply port is arranged in the supply pipe 20 below the molding material A stored in the heating chamber 13 so that gas flows in along the molding material A. The other end of the supply pipe 20 is connected to a replacement gas supply unit 14. In this embodiment, a case where water vapor is used as the replacement gas will be described. Water vapor is supplied from the replacement gas supply unit 14 to the heating container 12 through the supply pipe 20. A supply valve 22 is provided in the supply pipe 20. By opening and closing the supply valve 22, the supply of water vapor from the replacement gas supply unit 14 is switched on and off. The supply valve 22 is connected to a control unit 30 described later.

[0032] An exhaust pipe 24 is connected to the heating container 12. The exhaust pipe 24 is provided at the top of the heating container 12, and is configured so that gas is exhausted from the side opposite to the side to which the water vapor of the molding material A stored in the heating chamber 13 is supplied. An exhaust valve 26 is provided to the exhaust pipe 24. The amount of gas exhausted from the heating container 12 is controlled by adjusting the opening degree of the exhaust valve 26. The exhaust valve 26 is connected to a control unit 30, which will be described later.

[0033] A pressure gauge 16 for measuring the pressure inside the heating chamber 13 is disposed in the heating container 12. The pressure gauge 16 is connected to a control unit 30, which will be described later.

[0034] The heating device 10 includes a control unit 30. As shown in Fig. 2, the control unit 30 is connected to the supply valve 22, the replacement gas supply unit 14, the exhaust valve 26, and the pressure gauge 16. The control unit 30 includes a CPU (Central Processing Unit) 31, a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, an input / output interface (I / O) 34, and a storage unit 35.

[0035] The CPU 31, the ROM 32, the RAM 33, and the I / O 34 are connected to each other via a bus 36. The I / O 34 is connected to each of the functional units including the supply valve 22, the replacement gas supply unit 14, the exhaust valve 26, and the pressure gauge 16. These functional units are capable of communicating with the CPU 31 mutually via the I / O 34.

[0036] For example, a hard disk drive (HDD), a solid state drive (SSD), a flash memory, etc. are used as the storage unit 35. A control program for controlling each part of the heating device 10 and various data are stored in the storage unit 35. The control program and various data may be stored in the ROM 32.

[0037] In this embodiment, a gas replacement process program and the like are stored as part of the control program. In addition, high pressure P1, low pressure P2, cycle time C0, replacement time T0, and the like are stored as data used in this process.

[0038] In the heating device 10, the molding material A, which is the object to be heated, is placed in the heating container 12 and is therefore open to the atmosphere, so that the heating chamber 13 is filled with air. This air is the gas to be removed. In this embodiment, before the molding material A is heated, the air, which is the gas to be removed, is replaced with water vapor, which is the replacement gas. The time required for this replacement is set as replacement time T0. Replacement time T0 is the time required for the oxygen concentration in the heating chamber 13 to reach a predetermined low concentration or lower, and is set in advance.

[0039] In this embodiment, the pressure P in the heating container 12 is swung to replace the gas in the heating container 12. The gas replacement in the heating container 12 is carried out until the oxygen concentration in the heating container 12 becomes equal to or lower than a target oxygen concentration. The target oxygen concentration is set to a level that does not affect the heat treatment of the molding material A, and is set to 0.1% or less in this embodiment, for example. The time from the start to the end of the gas replacement in the heating container 12 is defined as replacement time T0.

[0040] The swing of pressure P (pressure swing) is performed by changing between a high pressure P1, which is higher than the saturated vapor pressure P0 of water vapor (replacement gas) corresponding to the set temperature in the heating vessel 12, and a low pressure P2, which is lower than the saturated vapor pressure P0. By setting the low pressure P2 to atmospheric pressure, a pressure reducing device is not required. The amplitude of the pressure swing can be easily increased without the high pressure P1. When the low pressure P2 is atmospheric pressure, the high pressure P1 is preferably 1.1 times or more the saturated vapor pressure P0.

[0041] As shown in Fig. 3, the pressure swing is performed by repeatedly changing a high pressure P1 and a low pressure at a constant cycle time C0. The cycle time C0 is preferably set to less than 1 / 3 of the replacement time T0. By setting the cycle time C0 to less than 1 / 3 of the replacement time T0, the effect of the pressure swing described below can be efficiently obtained.

[0042] In this embodiment, the pressure inside the heating container 12 is controlled by opening and closing (ON / OFF) the supply valve 22. That is, the supply valve 22 is opened to supply steam into the heating container 12 to create a high pressure P1, and the supply valve 22 is closed to stop the supply of steam to create a low pressure P2. Note that the exhaust valve 26 adjusts the opening so that the inside of the heating container 12 becomes the high pressure P1 when the supply valve 22 is open. Also, when the supply valve 22 is closed, the exhaust valve 26 is opened to create the inside of the heating container 12 becomes the low pressure P2 of atmospheric pressure.

[0043] Next, the gas replacement process, which is a pre-heating process in the heating device 10, will be described.

[0044] First, the heating container 12 is opened, the molding material A is placed in the heating container 12, and the heating container 12 is closed. When an instruction to start the gas replacement process is input from an input unit (not shown), the control unit 30 executes the gas replacement process shown in FIG.

[0045] In step S10, an instruction to start supplying water vapor is given to the replacement gas supply unit 14, and in step S12, the supply valve 22 is opened. As a result, water vapor is supplied into the heating vessel 12, and the pressure inside the heating vessel 12 increases.

[0046] In step S14, the pressure inside the heating container 12 measured by the pressure gauge 16 is obtained, and in step S16, it is determined whether or not the pressure exceeds the high pressure P1. If the determination is affirmative, in step S18, the exhaust valve 26 is opened. The exhaust valve 26 is opened by adjusting the opening so that the pressure P inside the heating container 12 is maintained at the high pressure P1, taking into consideration the flow rate of the steam supplied into the heating container 12. In practice, the pressure is adjusted to be maintained within a predetermined range around the high pressure P1, for example, within ±5%. As a result, while the pressure P inside the heating container 12 is maintained at the high pressure P1, steam is continuously supplied along the lower side of the molding material A, and the gas inside the heating container 12 is discharged from the exhaust pipe 24.

[0047] As the supply of water vapor and the discharge of gas from the discharge pipe 24 continue, the flow in the heating container 12 becomes steady, and a stagnation region Y1 of the flow occurs, as shown in Fig. 5. In Fig. 5 and Fig. 6, areas with high oxygen concentrations are shown in dark colors. In addition, condensation of water vapor occurs on the surface of the molding material A, which is the object to be heated, and on the inner surface of the heating container 12, and the gas to be discharged is trapped on the surface of the molding material A and on the inner surface of the heating container 12 (Y2 in Fig. 5).

[0048] Therefore, in step S20, it is determined whether a predetermined time (1 / 2 cycle time C0) has elapsed, and if the determination is negative, the process waits until the determination is positive, and if the determination is positive, the supply valve 22 is closed in step S22. This changes the gas flow in the heating container 12, and the stagnation region Y1 of the flow is diffused. In addition, the pressure P in the heating container 12 is reduced to a low pressure P2 (atmospheric pressure) lower than the saturated vapor pressure P0 of water vapor, so that the water condensed on the surface of the molding material A and the inner surface of the heating container 12 evaporates, and the trapped gas can be diffused.

[0049] In step S24, it is determined whether a predetermined time (1 / 2 cycle time C0) has elapsed, and if the determination is negative, the process waits until the determination is positive, and if the determination is positive, the supply valve 22 is opened in step S26. As a result, as shown in Fig. 6(A), water vapor is supplied to the area where oxygen has diffused to a certain extent, and as shown in Fig. 6(B), the gas in the heating vessel 12 is discharged from the discharge pipe 24.

[0050] In step S28, it is determined whether or not the replacement time T0 has elapsed, and if the replacement time T0 has not elapsed, the process returns to step S20 and repeats the above process. Flow stagnation occurs again, and the gas is trapped again due to condensation of water vapor (see FIG. 6(C)). However, by swinging the pressure P in the heating vessel 12 across the saturated vapor pressure P0, the stagnation of the gas flow in the heating vessel 12 is eliminated while the water vapor is re-evaporated (see FIG. 6(D)), and the oxygen-containing gas in the heating vessel 12 can be replaced with water vapor. If the replacement time T0 has elapsed, in step S29, the supply valve 22 and the exhaust valve 26 are closed, and the process ends.

[0051] According to this embodiment, by implementing a pressure swing within the heating vessel 12, it is possible to eliminate stagnation of the flow within the heating vessel 12 while re-evaporating the condensed water vapor, thereby efficiently performing gas replacement.

[0052] Furthermore, in this embodiment, the pressure swing is performed by opening and closing the supply valve 22 (turning the water vapor supply on and off), so that the supply of water vapor and the high pressure P1 can be easily linked together.

[0053] Furthermore, in this embodiment, the low pressure P2 of the pressure swing is set to atmospheric pressure, so that the amplitude of the pressure swing can be easily increased without the need for a pressure reducing device.

[0054] In this embodiment, the pressure P inside the heating container 12 is measured by the pressure gauge 16. However, instead of the pressure gauge 16, a flow meter may be provided in the supply pipe 20, and the pressure P inside the heating container 12 may be estimated based on the supply flow rate.

[0055] Furthermore, in this embodiment, the pressure swing is automatically performed by the control unit 30, but the same pressure swing may also be performed by manually operating the supply valve 22 and the discharge valve 26.

[0056] [Example]

[0057] In order to confirm the effect of the gas replacement method of the present disclosure, a two-dimensional CFD analysis was performed. The heating vessel 12 had a diameter of 1 m and a length of 1 m, the temperature inside the heating vessel 12 was 120°C, and the replacement gas was steam. The low pressure P2 was constant at atmospheric pressure.

[0058] First, in Comparative Examples 1, 2, and 3, the pressure P was set as follows and kept constant. In Examples 1, 2, and 3, the high pressure P1 was set as follows, and the cycle time C0 of the pressure swing was set to 15 seconds, as shown in FIG.

[0059] [Table 1]

[0060] The amounts of water vapor required to reduce the residual oxygen to 0.1% or less are compared between Comparative Example 1 and Example 1 (FIG. 8(1)), Comparative Example 2 and Example 2 (FIG. 8(2)), and Comparative Example 3 and Example 3 (FIG. 8(3)), which use the same high pressure P1. As shown in the graph in FIG. 8, it was confirmed that the amount of water vapor required was reduced when the pressure swing of the present disclosure was implemented at any high pressure P1.

[0061] Next, Comparative Example 1 and Examples 1-1 to 1-5 were carried out in which the cycle time C0 was set as follows at the high pressure P1 of Example 1. The replacement time T0 was set to 120 seconds.

[0062] [Table 2]

[0063] 9, it was confirmed that the amount of water vapor required was reduced when the pressure swing of the present disclosure was performed regardless of the cycle time. Note that the amount of water vapor required was particularly reduced when the pressure swing was repeated three or more times before the replacement time T0.

[0064] (Implementation) The present invention may be embodied in the following dependent embodiments as shown in the appendix.

[0065] [Appendix 1] A gas replacement method for replacing a gas in a heating container in a heating device having a heating container that contains a molding material to be heated, comprising: The gas in the heating container is replaced with the replacement gas while performing a pressure swing such that the pressure in the heating container becomes a high pressure exceeding the saturated vapor pressure of the replacement gas in the heating container and a low pressure lower than the saturated vapor pressure. Gas replacement method.

[0066] [Appendix 2] The pressure swing is performed by turning on and off the supply of the replacement gas. 2. The gas replacement method according to claim 1.

[0067] [Appendix 3] The gas replacement method according to claim 1 or 2, wherein the low pressure is atmospheric pressure.

[0068] [Appendix 4] The pressure swing is performed with a cycle time that is less than 1 / 3 of the replacement time, where the replacement time is the time from the start to the completion of the gas replacement. A gas replacement method according to any one of Supplementary Note 1 to Supplementary Note 3.

[0069] [Appendix 5] A heating container that contains a molding material to be heated and has a gas supply port and a gas exhaust port; a replacement gas supply unit for supplying a replacement gas from the gas supply port to the heating container; a pressure control unit that performs a pressure swing such that the pressure in the heating container becomes a high pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container and a low pressure that is lower than the saturated vapor pressure; A heating device comprising:

[0070] [Appendix 6] The pressure control unit performs the pressure swing by turning on / off the supply of the replacement gas by the replacement gas supply unit. 6. The heating device according to claim 5.

[0071] [Appendix 7] The pressure control unit performs the pressure swing so that the low pressure becomes atmospheric pressure. 7. The heating device according to claim 5 or 6.

[0072] [Appendix 8] The pressure control unit performs the pressure swing so that the pressure swing is performed in a cycle time that is less than ⅓ of the replacement time, where the replacement time is a time from the start to the completion of the gas replacement. The heating device according to any one of claims 5 to 7. [Explanation of symbols]

[0073] 10 Heating device 12 Heating container 13 Heating chamber 14 Replacement gas supply section 20 Supply pipe (gas supply port) 24 Exhaust pipe (gas exhaust port) 30 Control section (pressure control section)

Claims

1. A gas replacement method for replacing a gas in a heating container in a heating device having a heating container that contains a molding material to be heated, comprising: The gas in the heating container is replaced with the replacement gas while performing a pressure swing such that the pressure in the heating container becomes a high pressure exceeding the saturated vapor pressure of the replacement gas in the heating container and a low pressure lower than the saturated vapor pressure. Gas replacement method.

2. The pressure swing is performed by turning on and off the supply of the replacement gas. The gas replacement method according to claim 1.

3. The gas replacement method according to claim 1 , wherein the low pressure is atmospheric pressure.

4. The pressure swing is performed with a cycle time that is less than 1 / 3 of the replacement time, where the replacement time is the time from the start to the completion of the gas replacement. The gas replacement method according to any one of claims 1 to 3.

5. A heating container that contains a molding material to be heated and has a gas supply port and a gas exhaust port; a replacement gas supply unit for supplying a replacement gas from the gas supply port to the heating container; a pressure control unit that performs a pressure swing such that the pressure in the heating container becomes a high pressure that exceeds the saturated vapor pressure of the replacement gas in the heating container and a low pressure that is lower than the saturated vapor pressure; A heating device comprising:

6. The pressure control unit performs the pressure swing by turning on / off the supply of the replacement gas by the replacement gas supply unit. The heating device according to claim 5.

7. The pressure control unit performs the pressure swing so that the low pressure becomes atmospheric pressure. The heating device according to claim 5.

8. the pressure control unit performs the pressure swing so that the pressure swing is performed in a cycle time that is less than ⅓ of the replacement time, where the replacement time is a time from the start to the completion of the gas replacement. The heating device according to any one of claims 5 to 7.

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