Heat treatment system

Abstract

To provide a heat treatment system capable of recovering proper treatment gas without complicated facilities and control thereof.SOLUTION: A heat treatment system is provided with: a heat treatment section for heat-treating objects to be treated in treatment gas; a supply passage for supplying the treatment gas to the heat treatment section; a discharge passage for discharging the treatment gas from the heat treatment passage; a recovery passage branched from the discharge passage as well as connected to the supply passage to recover the treatment gas from the discharge passage; a discharge adjustment valve capable of adjusting the flow rate of the treatment gas discharged outside; a recovery adjustment valve capable of adjusting the flow rate of the treatment gas to be recovered; and a control section for controlling the heat treatment system, wherein the control section closes the recovery adjustment valve as opening the discharge adjustment valve when index density being density of an object component in the treatment gas in the heat treatment section is lower than the concentration threshold, and opens at least the recover adjustment valve out of the discharge adjustment valve and the recovery adjustment valve when the index density is equal to or more than the concentration threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermal processing system. [Background technology]

[0002] A heat treatment system is a system for heat treating a workpiece in a treatment gas. For example, Patent Document 1 discloses a heat treatment system equipped with a carburizing treatment device that performs a carburizing treatment on a workpiece using a modified gas containing CO (carbon monoxide) gas, H (hydrogen) gas, N (nitrogen) gas, CO (carbon dioxide) gas, HO (moisture), etc. as the treatment gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5478007 Summary of the Invention [Problem to be solved by the invention]

[0004] In the heat treatment system disclosed in Patent Document 1, gas exhausted from a carburizing treatment device is separated by a recycling device into a purified gas equivalent to the modified gas and its residual off-gas. The separated purified gas is then reused for the carburizing treatment. However, such recycling devices tend to have a complex configuration and control. For this reason, there has been a demand for a technology that can recover suitable treatment gas without the need for complex devices and control.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a heat treatment system that can recover suitable process gases without requiring complex equipment and its control. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) According to one aspect of the present invention, there is provided a heat treatment system comprising: a heat treatment section capable of accommodating a workpiece and heat-treating the workpiece in a treatment gas; a supply flow path for supplying the treatment gas to the heat treatment section; an exhaust flow path for exhausting the treatment gas from the heat treatment section to the outside; a recovery flow path branching from the exhaust flow path and connected to the supply flow path for recovering the treatment gas from the exhaust flow path; an exhaust control valve located in the exhaust flow path downstream of where the recovery flow path branches and capable of adjusting the flow rate of the treatment gas exhausted to the outside; a recovery control valve located in the recovery flow path and capable of adjusting the flow rate of the recovered treatment gas; and a controller for controlling the heat treatment system, wherein the controller opens the exhaust control valve and closes the recovery control valve when an index concentration, which is the concentration of a target component in the treatment gas in the heat treatment section, is lower than a concentration threshold; and opens at least the recovery control valve out of the exhaust control valve and the recovery control valve when the index concentration is equal to or higher than the concentration threshold.

[0008] According to this configuration, the process gas sent from the thermal processing unit to the exhaust flow path can be returned to the supply flow path via the recovery flow path, allowing the process gas to be reused. Therefore, the amount of process gas to be generated for the thermal processing of the workpiece can be reduced, thereby reducing the consumption of raw material gas required for generating the process gas. Furthermore, according to this configuration, when the index concentration is lower than the concentration threshold, the recovery control valve is closed to prevent the process gas from being recovered from the exhaust flow path. On the other hand, when the index concentration is equal to or higher than the concentration threshold, the recovery control valve is opened to recover the process gas from the exhaust flow path, so that the concentration of the target component in the recovered process gas is equal to or higher than the concentration threshold. Therefore, the process gas containing the target component can be recovered suitably without requiring a complex device and its control for purifying the process gas sent from the thermal processing unit.

[0009] (2) The heat treatment system of the above embodiment may further include a gas tank provided in the recovery flow path, capable of storing the processing gas recovered from the exhaust flow path and capable of delivering the stored processing gas to the supply flow path, and a first pressure measurement unit that measures the pressure in the gas tank, wherein the control unit may open the exhaust control valve while closing the recovery control valve when the index concentration is lower than the concentration threshold or when an index pressure, which is the pressure in the gas tank, is equal to or higher than a first pressure threshold, and may open at least the recovery control valve out of the exhaust control valve and the recovery control valve when the index concentration is equal to or higher than the concentration threshold and the index pressure is lower than the first pressure threshold. According to this configuration, the recovery adjustment valve is closed not only when the index concentration is lower than the concentration threshold but also when the index pressure is equal to or higher than the first pressure threshold, thereby preventing the process gas from being recovered from the exhaust line. When the index pressure is equal to the first pressure threshold, it is considered that a certain amount of process gas is stored in the gas tank. Therefore, by not recovering the process gas in such a case, it is possible to prevent excessive accumulation of process gas in the gas tank. Furthermore, according to this configuration, when the index concentration is equal to or higher than the concentration threshold and the index pressure is lower than the first pressure threshold, the recovery adjustment valve is opened to recover the process gas from the exhaust line. Therefore, process gas containing the target component can be preferably stored in a gas tank that stores a smaller amount of process gas than a certain amount.

[0010] (3) The heat treatment system of the above embodiment may further include a generation unit that generates the processing gas and delivers it to the supply flow path, and the control unit may stop the generation of the processing gas by the generation unit while delivering the processing gas from the gas tank to the supply flow path when the index pressure is equal to or higher than the first pressure threshold, and may deliver the processing gas from the gas tank to the supply flow path at a flow rate adjusted according to the index concentration and the index pressure while continuing the generation of the processing gas by the generation unit when the index pressure is lower than the first pressure threshold. According to this configuration, when the index pressure is equal to or greater than the first pressure threshold, the generation unit does not send the processing gas to the supply flow path, and only the gas tank sends the processing gas to the supply flow path. Also, according to this configuration, when the index pressure is lower than the first pressure threshold, the generation unit sends the processing gas to the supply flow path, while the gas tank also sends the processing gas to the supply flow path at a flow rate adjusted according to the index concentration and the index pressure. Therefore, since the processing gas can be sent from the gas tank to the supply flow path according to the index concentration and the index pressure, the consumption of raw material gas required to generate the processing gas can be reduced compared to a configuration in which the processing gas can be sent to the supply flow path only from the generation unit.

[0011] (4) In the heat treatment system of the above form, the control unit may estimate the index concentration using the flow rate of the processing gas sent from the generation unit to the supply flow path and the flow rate of the processing gas sent from the gas tank to the supply flow path, and the concentration of the target component in the processing gas stored in the gas tank. According to this configuration, the value of the indicator concentration can be obtained without providing a concentration measurement unit for measuring the indicator concentration, thereby reducing the cost required to build a heat treatment system.

[0012] (5) The heat treatment system of the above embodiment may further include a generation unit that generates the processing gas and sends it to the supply flow path, a gas tank that is provided at a position in the supply flow path to which the recovery flow path is connected and that is capable of storing the processing gas generated by the generation unit and the processing gas recovered from the exhaust flow path and sending the stored processing gas to the supply flow path, and a first pressure measurement unit that measures the pressure in the gas tank, wherein the control unit may, when an index pressure that is the pressure in the gas tank is equal to or higher than a first pressure threshold, stop the generation of the processing gas by the generation unit and close the recovery adjustment valve, and when the index pressure is lower than the first pressure threshold, adjust the opening degree of the recovery adjustment valve according to the index concentration and the index pressure while allowing the generation unit to generate the processing gas. According to this configuration, when the index pressure is equal to or greater than the first pressure threshold, the processing gas is not supplied to the gas tank from either the generation unit or the recovery passageway. Furthermore, according to this configuration, when the index pressure is lower than the first pressure threshold, the processing gas is supplied from the generation unit to the gas tank, while the recovery passageway also supplies the processing gas to the gas tank at a flow rate adjusted according to the index concentration and the index pressure. Therefore, since the processing gas can be supplied from the recovery passageway to the gas tank according to the index concentration and the index pressure, the consumption of raw material gas required to generate the processing gas can be reduced compared to a configuration in which the processing gas can be supplied to the gas tank only from the generation unit.

[0013] (6) In the heat treatment system of the above embodiment, the control unit may estimate the index concentration using the flow rate of the processing gas sent from the gas tank to the supply flow path and the concentration of the target component in the processing gas stored in the gas tank. According to this configuration, the value of the indicator concentration can be obtained without providing a concentration measurement unit for measuring the indicator concentration, thereby reducing the cost required to build a heat treatment system.

[0014] (7) The heat treatment system of the above embodiment may further include a second pressure measuring unit that measures the pressure inside the heat treatment unit, and a supply adjustment valve that is provided in a portion of the supply flow path downstream of the position where the recovery flow path is connected and that is capable of adjusting the supply flow rate, which is the flow rate of the processing gas supplied to the heat treatment unit, and the control unit may adjust the flow rate of the processing gas discharged from the heat treatment unit and the supply flow rate by controlling the opening degree of the supply adjustment valve, the opening degree of the exhaust adjustment valve, and the opening degree of the recovery adjustment valve depending on whether the received instruction signal or the pressure inside the heat treatment unit is higher than a second pressure threshold. According to this configuration, the pressure inside the thermal processing unit can be adjusted by adjusting the flow rate and supply flow rate of the processing gas delivered from the thermal processing unit, thereby adjusting the pressure inside the thermal processing unit to a desired pressure.

[0015] The present invention can be realized in various forms, for example, as a method for controlling a heat treatment system, a computer program for controlling a heat treatment system, a server device for distributing the computer program, a non-transitory storage medium storing the computer program, etc. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram illustrating the configuration of a heat treatment system according to a first embodiment. [Figure 2] 6 is a flowchart showing the procedure of a first control process. [Figure 3] 10 is a flowchart showing the procedure of a second control process. [Figure 4] 10 is a flowchart showing the procedure of a third control process. [Figure 5] FIG. 10 is an explanatory diagram illustrating the configuration of a heat treatment system according to a second embodiment. [Figure 6] 10 is a flowchart showing the procedure of a second control process. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment FIG. 1 is an explanatory diagram illustrating the configuration of a heat treatment system 1 according to one embodiment of the present invention. The heat treatment system 1 is a system for heat treating a workpiece in a treatment gas. Specifically, the heat treatment system 1 is a system for carburizing a workpiece made of steel in a treatment gas containing carbon monoxide. The heat treatment system 1 mainly includes a generation unit 10, a supply flow path F1, heat treatment units 20a and 20b, an exhaust flow path F2, a recovery flow path F3, and a gas tank 30.

[0018] The generation unit 10 is connected to a supply flow path F1, which will be described later. The generation unit 10 is a device that generates a process gas and sends it to the supply flow path F1. The generation unit 10 generates the process gas by converting hydrocarbons, which are raw material gases, supplied from a raw material gas supply source (not shown). This process gas contains carbon monoxide, hydrogen, nitrogen, and also trace amounts of carbon dioxide and water. In this embodiment, when raw material gas is supplied from the raw material gas supply source (not shown), the concentration of the process gas sent from the generation unit 10 to the supply flow path F1 is constant.

[0019] The supply flow path F1 is a flow path for supplying a processing gas to thermal processing units 20a and 20b (described later). The supply flow path F1 branches into supply flow paths F1a and F1b downstream. The supply flow paths F1a and F1b are connected to thermal processing units 20a and 20b, respectively. The piping forming the supply flow paths F1a and F1b is provided with supply adjustment valves V1a and V1b, respectively. More specifically, the supply adjustment valves V1a and V1b are provided in the piping forming a portion of the supply flow path F1 downstream of a position where a recovery flow path F3 (described later) is connected. Each of the supply adjustment valves V1a and V1b can adjust the supply flow rate, which is the flow rate of the processing gas supplied to thermal processing units 20a and 20b.

[0020] The heat treatment units 20a and 20b are connected in parallel to the supply flow path F1. The heat treatment units 20a and 20b are capable of accommodating workpieces to be heat-treated and heat-treat the workpieces in a processing gas. In this embodiment, the heat treatment units 20a and 20b are devices for carburizing the workpieces. The processing gas is introduced into the heat treatment units 20a and 20b via the supply flow paths F1a and F1b. The heat treatment units 20a and 20b also have openable doors (not shown). Opening the doors allows the workpieces to be placed in and removed from the heat treatment units 20a and 20b. The heat treatment units 20a and 20b are provided with pressure sensors P1a and P1b, respectively, for measuring the pressures within the heat treatment units 20a and 20b. The pressure sensors P1a and P1b correspond to second pressure measurement units (the first pressure measurement unit will be described later).

[0021] The exhaust flow path F2 is a flow path for exhausting the processing gas from the thermal processing units 20a and 20b to the outside of the thermal processing system 1. The exhaust flow path F2 includes an exhaust flow path F2a connected to the thermal processing unit 20a and an exhaust flow path F2b connected to the thermal processing unit 20b. The piping forming the exhaust flow paths F2a and F2b is provided with concentration sensors C2a and C2b, respectively. The concentration sensors C2a and C2b measure the concentration of a target component in the processing gas sent from the thermal processing units 20a and 20b to the exhaust flow paths F2a and F2b, respectively. In this embodiment, the target component in the processing gas is carbon monoxide. The concentrations measured by the concentration sensors C2a and C2b can be considered as the concentration of the target component in the processing gas in the thermal processing units 20a and 20b. Furthermore, exhaust adjustment valves V2a and V2b are provided in the piping forming the exhaust flow paths F2a and F2b downstream of the branch point of the recovery flow path F3 (described later). The exhaust regulating valves V2a and V2b are each capable of adjusting the flow rate of the processing gas exhausted to the outside of the heat treatment system 1.

[0022] The recovery flow path F3 is a flow path that branches off from each of the exhaust flow paths F2a and F2b and is connected to the supply flow path F1. The recovery flow path F3 is a flow path for recovering the processing gas from each of the exhaust flow paths F2a and F2b. The recovery flow path F3 includes a recovery flow path F3a that branches off from a portion of the exhaust flow path F2a that is upstream of the position where the exhaust adjustment valve V2a is provided, and a recovery flow path F3b that branches off from a portion of the exhaust flow path F2b that is upstream of the position where the exhaust adjustment valve V2b is provided. The pipes that form the recovery flow paths F3a and F3b are provided with recovery adjustment valves V3a and V3b, respectively. The recovery adjustment valves V3a and V3b are capable of adjusting the flow rate of the processing gas recovered from each of the exhaust flow paths F2a and F2b.

[0023] The recovery flow path F3 includes a recovery flow path F3c, which is a portion downstream of the point where the recovery flow paths F3a and F3b join, and a recovery flow path F3d, which connects the gas tank 30 (described later) to the supply flow path F1. A compressor Cm is provided in the piping that forms the recovery flow path F3c. The compressor Cm pressurizes the processing gas that flows through the recovery flow paths F3a and F3b and sends it downstream of the recovery flow path F3c.

[0024] The gas tank 30 is provided in the piping forming the recovery flow path F3. Specifically, in this embodiment, as shown in FIG. 1 , the gas tank 30 is connected to the recovery flow paths F3c and F3d and is provided in the piping as part of the piping forming the recovery flow path F3. The gas tank 30 is a tank that can store the processing gas recovered from the exhaust flow path F2 and can deliver the stored processing gas to the supply flow path F1 via the recovery flow path F3d. The piping forming the recovery flow path F3d is provided with a delivery adjustment valve V4. The flow rate of the processing gas delivered from the gas tank 30 to the supply flow path F1 is adjusted by controlling the aperture of the delivery adjustment valve V4. The gas tank 30 is also provided with a pressure sensor P3 and a concentration sensor C3. The pressure sensor P3 measures the pressure inside the gas tank 30. The pressure sensor P3 corresponds to a first pressure measurement unit. The concentration sensor C3 measures the concentration of a target component in the processing gas stored in the gas tank 30.

[0025] The control unit 40 is a computer including a ROM, a RAM, and a CPU, and controls the heat treatment system 1. The control unit 40 receives information indicating various measurement values ​​from the pressure sensors P1a and P1b, the concentration sensors C2a and C2b, the pressure sensor P3, and the concentration sensor C3. The objects controlled by the control unit 40 include the supply adjustment valves V1a and V1b, the exhaust adjustment valves V2a and V2b, the recovery adjustment valves V3a and V3b, and the delivery adjustment valve V4.

[0026] 2 to 4 are flowcharts showing the procedure of the system control process executed by the control unit 40. The system control process is a process for controlling the generation of the process gas by the generation unit 10 and the opening and closing of each valve. The system control process includes first to third control processes. Each of the system control processes is constantly executed while the heat treatment system 1 is operating.

[0027] 2 is a flowchart showing the procedure of the first control process of the system control process. The first control process is executed for each of the thermal processing units 20a and 20b, but here, the thermal processing unit 20a will be described as an example. When the first control process is started, the control unit 40 first calculates the index concentration C , which is the concentration of the target component in the processing gas in the thermal processing unit 20a. H is the concentration threshold C A (Step S11). H is the concentration measured by the concentration sensor C2a (the concentration of the target component in the processing gas in the thermal processing unit 20a). A is a threshold value set as a criterion for determining whether or not at least a portion of the processing gas sent from the thermal processing unit 20a to the exhaust passage F2a is allowed to flow into the recovery passage F3a.

[0028] Index concentration C H is the concentration threshold C A If the index concentration C is lower than the reference concentration C (step S11: YES), the control unit 40 opens the exhaust control valve V2a and closes the recovery control valve V3a (step S12). That is, at this time, the control unit 40 exhausts the processing gas sent from the thermal processing unit 20a to the exhaust flow path F2a to the outside of the thermal processing system 1 without allowing it to flow into the recovery flow path F3a. H is the concentration threshold C A If the concentration of the target component in the processing gas sent from the thermal processing unit 20a to the exhaust flow path F2a is lower than 0.05 (step S11: YES), the control unit 40 does not recover such processing gas because the concentration of the target component in the processing gas sent from the thermal processing unit 20a to the exhaust flow path F2a is relatively low. After that, the control unit 40 ends the first control process.

[0029] On the other hand, the index concentration CH is the concentration threshold C A If it is equal to or greater than this (step S11: NO), the control unit 40 determines the index pressure P T It is determined whether the index pressure P is equal to or greater than the first pressure threshold (step S13). T is the pressure in the gas tank 30 measured by the pressure sensor P3. The first pressure threshold is the upper limit pressure P MAX The index pressure P is set to a value obtained by multiplying this by 0.8. T is equal to or greater than the first pressure threshold (step S13: YES), the control unit 40 H is the concentration threshold C A Similarly to when the index pressure P is lower than the reference pressure P (step S11: YES), the exhaust adjustment valve V2a is opened and the recovery adjustment valve V3a is closed (step S12). T is equal to or greater than the first pressure threshold (step S13: YES), the pressure in the gas tank 30 is equal to or greater than the upper limit pressure P MAX Since the temperature is close to 100°C, the process gas is not recovered in such a case. After that, the control unit 40 ends the first control process.

[0030] On the other hand, the index pressure P T If the index concentration C is lower than the first pressure threshold (step S13: NO), the control unit 40 opens both the exhaust regulating valve V2a and the recovery regulating valve V3a (step S14). The opening degrees of the exhaust regulating valve V2a and the recovery regulating valve V3a at this time are set arbitrarily. H is the concentration threshold C A If the above is true (step S11: NO), and the index pressure P T is lower than the first pressure threshold (step S13: NO), the concentration of the target component in the processing gas sent from the thermal processing unit 20a to the exhaust flow path F2a is relatively high, and the upper limit pressure P MAX Since the temperature is not close to 0.5°C, the process gas is recovered in this case. After that, the control unit 40 ends the first control process.

[0031] 3 is a flowchart showing the procedure of the second control process of the system control process. Like the first control process, the second control process is executed for each of the heat treatment units 20a and 20b, but here, the heat treatment unit 20a will be used as an example. When the second control process is started, the control unit 40 first calculates the index pressure P T It is determined whether the index pressure P is equal to or greater than the first pressure threshold (step S21). T As in the first control process, the first pressure threshold value is the pressure in the gas tank 30 measured by the pressure sensor P3. As in the first control process, the first pressure threshold value is the upper limit pressure P MAX The index pressure P is set to a value obtained by multiplying this by 0.8. T is equal to or greater than the first pressure threshold (step S21: YES), the control unit 40 determines the flow rate V of the processing gas to be sent from the generation unit 10 to the supply flow path F1. P 0, the flow rate V of the processing gas delivered from the gas tank 30 to the supply flow path F1 t is adjusted to be greater than 0 (step S22). That is, the control unit 40 stops the generation of the process gas by the generation unit 10 by at least one of stopping the supply of the raw material gas from the raw material gas supply source (not shown) to the generation unit 10 and stopping the transformation in the generation unit 10, and opens the delivery adjustment valve V4 to deliver the process gas from the gas tank 30 to the supply flow path F1. T is equal to or greater than the first pressure threshold (step S21: YES), the pressure in the gas tank 30 is equal to or greater than the upper limit pressure P MAX Since the pressure in the gas tank 30 is close to the pressure in the supply flow path F1, the process gas is sent only from the gas tank 30 to the supply flow path F1 to reduce the pressure in the gas tank 30. After that, the control unit 40 ends the second control process.

[0032] On the other hand, the index pressure P T is the first pressure threshold (0.8P MAX ) (step S21: NO), the control unit 40 H is the concentration threshold C B (Step S23). B is the concentration threshold C Ais a different value from the flow rate V P and flow rate V t The threshold value is set as a standard for controlling the index concentration C. H is the concentration threshold C B If the flow rate V P and flow rate V t are all greater than 0, and the flow rate V P is the flow rate V t That is, the control unit 40 adjusts the flow rate V to be larger than V by controlling the supply amount of the raw material gas from the raw material gas supply source (not shown) to the generation unit 10 and the opening degree of the delivery adjustment valve V4. P is the flow rate V t Adjust the concentration so that it is greater than the index concentration C H is the concentration threshold C B If the index concentration C is lower than the index concentration C (step S23: YES), the processing gas that has not been used for the heat treatment in the heat treatment unit 20a (the processing gas derived from the generation unit 10) is sent to the supply flow path F1 in a larger amount than the processing gas that has been used for the heat treatment (the processing gas derived from the gas tank 30). H After that, the control unit 40 ends the second control process.

[0033] On the other hand, the index concentration C H is the concentration threshold C B If it is equal to or greater than this (step S23: NO), the control unit 40 determines the index pressure P T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ) (Step S25). T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ) (step S25: YES), the control unit 40 P is set to a value greater than 0, and the flow rate V t That is, the control unit 40 controls the delivery adjustment valve V4 to be closed while supplying the raw material gas from a raw material gas supply source (not shown) to the generation unit 10, thereby adjusting the flow rate VP is set to a value greater than 0, and the flow rate V t Adjust so that the index pressure P T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ), the amount of processing gas stored in the gas tank 30 is small, so the processing gas is sent to the supply flow path F1 only from the generation unit 10. Thereafter, the control unit 40 ends the second control process.

[0034] On the other hand, the index pressure P T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ) or more (step S25: NO), the control unit 40 T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) (Step S27). T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) (step S27: YES), the control unit 40 H is the concentration threshold C B Similarly, if the flow rate V P and flow rate V t are all greater than 0, and the flow rate V P is the flow rate V t (Step S24). T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ), the control unit 40 outputs a larger amount of processing gas to the generation unit 10 than to the gas tank 30, while outputting the processing gas from both the generation unit 10 and the gas tank 30 to the supply flow path F1. Then, the control unit 40 terminates the second control process.

[0035] On the other hand, the index pressure PT is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) or more (step S27: NO), the control unit 40 P and flow rate V t are all greater than 0, and the flow rate V t is the flow rate V P The index pressure P T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) or more (step S27: NO), the index pressure P T is the first pressure threshold (0.8P MAX ), a relatively large amount of processing gas is stored in the gas tank 30, so that the processing gas is sent from both the generation unit 10 and the gas tank 30 to the supply flow path F1, and more processing gas is sent to the gas tank 30 than to the generation unit 10. Thereafter, the control unit 40 ends the second control process.

[0036] In this way, in the second control process, the control unit 40 T is above the first pressure threshold (0.8P MAX ) (step S21: YES), the control unit 40 stops the generation of the processing gas by the generation unit 10 and causes the processing gas to be sent from the gas tank 30 to the supply flow path F1. T is the first pressure threshold (0.8P MAX ) (step S21: NO), the generation unit 10 is allowed to generate the process gas while the index concentration C H and index pressure P T Flow rate V adjusted according to t The processing gas is delivered from the gas tank 30 to the supply flow path F1 (steps S24, S26, S28). t is adjusted to be 0.

[0037] 4 is a flowchart showing the procedure of the third control process among the system control processes. The third control process is executed for each of the heat treatment units 20a and 20b, similar to the first and second control processes, but here, the heat treatment unit 20a will be used as an example for explanation. When the third control process is started, the control unit 40 first calculates the index pressure P H is the second pressure threshold P D (Step S31). H is the pressure in the thermal processing unit 20a measured by the pressure sensor P1a. D A pressure value suitable for performing the heat treatment in the heat treatment section 20a is set in the parameter .

[0038] Index pressure P H is the second pressure threshold P D If the index pressure P is lower than the reference pressure P (step S31: YES), the control unit 40 adjusts the delivery flow rate, which is the flow rate of the processing gas delivered from the thermal processing unit 20a, to be smaller than the supply flow rate, which is the flow rate of the processing gas supplied to the thermal processing unit 20a (step S32). Thereafter, the control unit 40 ends the third control process. H is the second pressure threshold P D If it is equal to or greater than that (step S31: NO), the control unit 40 adjusts the delivery flow rate, which is the flow rate of the processing gas delivered from the thermal processing unit 20a, to be equal to or greater than the supply flow rate, which is the flow rate of the processing gas supplied to the thermal processing unit 20a (step S33). Thereafter, the control unit 40 ends the third control process.

[0039] That is, in the third control process, the control unit 40 determines whether the pressure in the heat treatment unit 20a is equal to or greater than the second pressure threshold P D The opening degree of the supply regulating valve V1a, the opening degree of the exhaust regulating valve V2a, and the opening degree of the recovery regulating valve V3a are controlled depending on whether the opening degree of the supply regulating valve V1a, the exhaust regulating valve V2a, and the recovery regulating valve V3a are controlled to adjust the delivery flow rate and the supply flow rate.

[0040] 2 to 4, the first to third control processes for heat treatment unit 20a are described, but the first to third control processes for heat treatment unit 20b are also executed in parallel with the first to third control processes for heat treatment unit 20a.

[0041] As described above, according to the heat treatment system 1 of the first embodiment, the processing gas sent from the heat treatment units 20a and 20b to the exhaust flow path F2 can be returned to the supply flow path F1 via the recovery flow path F3, so that the processing gas can be reused. Therefore, the amount of processing gas to be generated for the heat treatment of the workpiece can be reduced, and the consumption of the raw material gas required for generating the processing gas can be reduced. Furthermore, according to the heat treatment system 1 of the first embodiment, the indicator concentration C H is the concentration threshold C A If the index concentration C is lower than the reference concentration C (step S11: YES), the recovery adjustment valves V3a and V3b are closed to prevent the recovery of the processing gas from the exhaust flow paths F2a and F2b. H is the concentration threshold C A If the above is true (step S11: NO), and the index pressure P T is the first pressure threshold (0.8P MAX ) (step S13: NO), the recovery adjustment valves V3a and V3b are opened to recover the processing gas from the exhaust flow paths F2a and F2b, so that the concentration of the target component in the recovered processing gas is lower than the concentration threshold C A As a result, the process gas containing the target component can be recovered without requiring a complex device for purifying the process gas sent out from the thermal processing units 20a and 20b and its control.

[0042] In the heat treatment system 1 of the first embodiment, the index concentration C H is the concentration threshold C A In addition to the case where the index pressure P T is the first pressure threshold (0.8P MAX ) or more (step S13: YES), the recovery adjustment valves V3a and V3b are closed to prevent the recovery of the processing gas from the exhaust flow paths F2a and F2b.T is the first pressure threshold (0.8P MAX ), it is considered that an amount of the processing gas stored in the gas tank 30 is close to the upper limit. Therefore, in such a case, by not recovering the processing gas, it is possible to prevent the processing gas from being excessively stored in the gas tank 30. In addition, in the heat treatment system 1 of the first embodiment, the index concentration C H is the concentration threshold C A If the above is true (step S11: NO), and the index pressure P T is the first pressure threshold (0.8P MAX ), the processing gas is recovered from the exhaust flow paths F2a and F2b, so that the processing gas containing the target component can be suitably stored in the gas tank 30 that stores a small amount of processing gas that is not close to the upper limit (step S13: NO).

[0043] In the heat treatment system 1 of the first embodiment, the index pressure P T is the first pressure threshold (0.8P MAX ) or more (step S21: YES), the generation unit 10 does not send the processing gas to the supply flow path F1, but only the gas tank 30 sends the processing gas to the supply flow path F1. T is the first pressure threshold (0.8P MAX ) (step S21: NO), the process gas is sent from the generation unit 10 to the supply flow path F1, and the indicator concentration C H and index pressure P T Flow rate V adjusted according to t The processing gas is sent to the supply flow path F1 (steps S24, S26, S28). H and index pressure P T Since the processing gas can be delivered from the gas tank 30 to the supply flow path F1 according to the amount of processing gas, the consumption of raw material gas required to generate the processing gas can be reduced compared to a configuration in which the processing gas can be delivered to the supply flow path F1 only from the generation unit 10.

[0044] In the heat treatment system 1 of the first embodiment, the pressure in the heat treatment units 20a and 20b is equal to or greater than the second pressure threshold P D The pressure in the heat treatment units 20a and 20b can be adjusted by adjusting the delivery flow rate and the supply flow rate depending on whether the pressure is higher than the reference pressure. Therefore, the pressure in the heat treatment units 20a and 20b can be adjusted to a desired pressure.

[0045] Second Embodiment 5 is an explanatory diagram illustrating the configuration of a heat treatment system 2 according to a second embodiment. The heat treatment system 2 according to the second embodiment differs from the heat treatment system 1 according to the first embodiment mainly in that the gas tank 30 is provided at a different position, that the recovery flow path F3d and the delivery adjustment valve V4 are not provided, and that the supply flow path F1c, the compressor CM, and the flow rate sensors f1 and f2 are provided.

[0046] In the heat treatment system 2 of the second embodiment, the gas tank 30 is provided at a position of the supply flow path F1 to which the recovery flow path F3c is connected. That is, the gas tank 30 is provided on the piping that forms the supply flow path F1 as a part of the piping. The gas tank 30 is connected to the supply flow paths F1a and F1b, and is connected to a recovery flow path F3c. The gas tank 30 is a tank that can store the processing gas generated in the generation unit 10 and the processing gas recovered from the exhaust flow path F2, and can deliver the stored processing gas to the supply flow paths F1a and F1b. While the heat treatment system 2 is operating, the gas tank 30 is always open to the supply flow paths F1a and F1b, so that the processing gas is always delivered to the supply flow paths F1a and F1b.

[0047] In the heat treatment system 2 of the second embodiment, the supply flow path F1 includes a supply flow path F1c that connects the generation unit 10 and the gas tank 30, in addition to the supply flow paths F1a and F1b. The supply flow path F1c is a flow path for delivering the processing gas generated in the generation unit 10 to the gas tank 30. A compressor CM that pressurizes the processing gas flowing from the generation unit 10 and delivers it toward the gas tank 30 is provided in the piping that forms the supply flow path F1c.

[0048] In the heat treatment system 2 of the second embodiment, a flow rate sensor f1 is provided in a pipe forming the supply flow path F1 at a position upstream of the branching point into the supply flow paths F1a and F1b. The flow rate sensor f1 measures the flow rate of the processing gas delivered from the gas tank 30. In addition, a flow rate sensor f2 is provided in a pipe forming the recovery flow path F3c. The flow rate sensor f2 measures the flow rate of the processing gas flowing through the recovery flow paths F3a and F3b.

[0049] The system control process executed by the heat treatment system 2 of the second embodiment includes first to third control processes, similar to the system control process executed by the heat treatment system 1 of the first embodiment. On the other hand, among the first to third control processes executed by the heat treatment system 2 of the second embodiment, the first and third control processes are similar to those of the first embodiment, but the second control process is different from that of the first embodiment.

[0050] 6 is a flowchart showing the procedure of the second control process among the system control processes executed by the control unit 40 of the second embodiment. In the heat treatment system 2 of the second embodiment, the second control process is executed for each of the heat treatment units 20a and 20b, as in the first control process, but here, the heat treatment unit 20a will be described as an example. When the second control process is started, the control unit 40 first calculates the index pressure P T is the first pressure threshold (0.8P MAX ) or more (step S41). T As in the first control process, the index pressure P is the pressure inside the gas tank 30 measured by the pressure sensor P3. T is equal to or greater than the first pressure threshold (step S41: YES), the control unit 40 determines the flow rate V of the processing gas to be sent from the generation unit 10 to the gas tank 30. P and the flow rate V of the processing gas recovered into the gas tank 30 via the recovery flow path F3c. Rand are adjusted to 0 (step S42). That is, the control unit 40 stops the generation of the process gas by the generation unit 10 by at least one of stopping the supply of the raw material gas from the raw material gas supply source (not shown) to the generation unit 10 and stopping the transformation in the generation unit 10, and closes both the recovery adjustment valves V3a and V3b to stop the recovery of the process gas to the gas tank 30 via the recovery flow path F3c. The index pressure P T is equal to or greater than the first pressure threshold (step S41: YES), the pressure in the gas tank 30 is equal to or greater than the upper limit pressure P MAX Since the gas supply location is close to the gas tank 30, the process gas is not supplied from either the generation unit 10 or the recovery passage F3c to the gas tank 30. After that, the control unit 40 ends the second control process.

[0051] On the other hand, the index pressure P T is the first pressure threshold (0.8P MAX ) (step S41: NO), the control unit 40 H is the concentration threshold C B (Step S43). H is the concentration threshold C B If the flow rate V P and flow rate V R are all greater than 0, and the flow rate V P is the flow rate V R That is, the control unit 40 adjusts the flow rate V to be larger than V by controlling the amount of raw material gas supplied from a raw material gas supply source (not shown) to the generation unit 10 and the opening degree of the recovery adjustment valves V3a and V3b. P is the flow rate V R Then, the control unit 40 ends the second control process.

[0052] On the other hand, the index concentration C H is the concentration threshold C B If it is equal to or greater than this (step S43: NO), the control unit 40 determines the index pressure P T is the upper limit pressure P MAX multiplied by 0.2 (0.2PMAX ) (Step S45). T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ) (step S45: YES), the control unit 40 P is set to a value greater than 0, and the flow rate V R That is, the control unit 40 adjusts the flow rate V P is set to a value greater than 0, and the flow rate V R is adjusted to be 0. After that, the control unit 40 ends the second control process.

[0053] On the other hand, the index pressure P T is the upper limit pressure P MAX multiplied by 0.2 (0.2P MAX ) or more (step S45: NO), the control unit 40 T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) (Step S47). T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) (step S47: YES), the control unit 40 H is the concentration threshold C B Similarly, if the flow rate V P and flow rate V R are all greater than 0, and the flow rate V P is the flow rate V R (Step S44) After that, the control unit 40 ends the second control process.

[0054] On the other hand, the index pressure P T is the upper limit pressure P MAX Multiplied by 0.5 (0.5P MAX ) or more (step S47: NO), the control unit 40P and flow rate V R are all greater than 0, and the flow rate V R is the flow rate V P The control unit 40 then adjusts the temperature to the above value (step S48). After that, the control unit 40 ends the second control process.

[0055] In this way, in the second control process, the control unit 40 T is the first pressure threshold (0.8P MAX ) or more (step S41: YES), the control unit 40 stops the generation of the process gas by the generation unit 10 and closes the recovery adjustment valves V3a and V3b. T is the first pressure threshold (0.8P MAX ) (step S41: NO), the generation unit 10 is allowed to generate the process gas while the index concentration C H and index pressure P T In step S46, the opening degree of the recovery adjusting valves V3a and V3b is adjusted according to the flow rate V R The recovery adjustment valves V3a and V3b are closed so that the

[0056] As described above, in the heat treatment system 2 of the second embodiment, the index pressure P T is the first pressure threshold (0.8P MAX ) or more (step S41: YES), the process gas is not supplied to the gas tank 30 from either the generation unit 10 or the recovery passage F3c. T is the first pressure threshold (0.8P MAX ) (step S41: NO), the process gas is supplied from the generation unit 10 to the gas tank 30, and the index concentration C H and index pressure P T The process gas is supplied to the gas tank 30 at a flow rate adjusted according to the index concentration C H and index pressure P TSince the processing gas can be supplied to the gas tank 30 from the recovery flow path F3c according to the amount of raw material gas consumed to generate the processing gas can be reduced compared to a configuration in which the processing gas can be supplied to the gas tank 30 only from the generation section 10.

[0057] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0058] In the above embodiment, the heat treatment systems 1 and 2 are systems for carburizing a workpiece made of steel in a process gas containing carbon monoxide, but this is not limiting. The heat treatment systems 1 and 2 may be systems for heat treating a workpiece made of any material in any process gas. Of course, the target components in the process gas whose concentrations are measured by the concentration sensors C2a and C2b may also be any components.

[0059] In the above embodiment, the heat treatment systems 1 and 2 include two heat treatment sections 20a and 20b, but may include three or more heat treatment sections.

[0060] In the above embodiment, the control unit 40 detects the index concentration C measured by the concentration sensors C2a and C2b. H For example, the control unit 40 calculates the index concentration C using the flow rate of the processing gas sent from the generation unit 10 to the supply flow path F1, the flow rate of the processing gas sent from the gas tank 30 to the supply flow path F1, and the concentration of the target component in the processing gas stored in the gas tank 30. H and the estimated indicator concentration C H The system control process may be performed using the above three parameters and the indicator concentration C HThe flow rate of the processing gas delivered from the generation unit 10 to the supply flow path F1 is obtained by referring to the amount of raw material gas supplied to the generation unit 10 from a raw material gas supply source (not shown), the conversion efficiency from the raw material gas to the processing gas in the generation unit 10, the flow path cross-sectional area of ​​the supply flow path F1, etc. The flow rate of the processing gas delivered from the gas tank 30 to the supply flow path F1 is obtained by referring to the amount of processing gas stored in the gas tank 30 (which can be estimated from the measurement value of the pressure sensor P3), the flow path cross-sectional area of ​​the supply flow path F1, etc. The concentration of the target component in the processing gas stored in the gas tank 30 is obtained by measurement by the concentration sensor C3. The control unit 40 estimates the index concentration by using the flow rate of the processing gas delivered from the gas tank 30 to the supply flow path F1 and the concentration of the target component in the processing gas stored in the gas tank 30, among the above-mentioned three parameters, and calculates the estimated index concentration C H The system control process may be performed using the above two parameters and the index concentration C H This is done using a map or equation that shows the correspondence between the index concentration C H Without providing concentration sensors C2a and C2b for measuring the index concentration C H Therefore, the cost required to construct the heat treatment systems 1 and 2 can be reduced.

[0061] In the above embodiment, in the first control process (FIG. 2), the index pressure P T is lower than the first pressure threshold (step S13: NO), the control unit 40 opens both the exhaust adjustment valve V2a (V2b) and the recovery adjustment valve V3a (V3b) (step S14), but this is not limited to this. Tis lower than the first pressure threshold (step S13: NO), the control unit 40 may close the exhaust adjustment valve V2a (V2b) and open the recovery adjustment valve V3a (V3b) (step S14). In this case, the processing gas sent from the thermal processing unit 20a (20b) to the exhaust flow path F2a (F2b) is not exhausted to the outside of the thermal processing system 1, 2 but flows into the recovery flow path F3a (F3b).

[0062] In the above embodiment, in the third control process (FIG. 4), the control unit 40 determines whether the pressure in the heat treatment units 20a and 20b reaches the second pressure threshold P D In the third control process (FIG. 4), the control unit 40 may adjust the delivery flow rate and the supply flow rate in response to a received instruction signal. The instruction signal is a signal indicating an instruction from an operator operating the heat treatment system 1 or 2. For example, when placing a workpiece in the heat treatment unit 20a (20b), a decrease in pressure within the heat treatment unit 20a (20b) is predicted upon opening the door of the heat treatment unit. Therefore, in order to increase the pressure within the heat treatment unit 20a (20b) before opening the door, the operator transmits an instruction signal to the control unit 40 via a user interface instructing the delivery flow rate to be smaller than the supply flow rate. By increasing the pressure in advance based on such an instruction signal, it is possible to prevent air from entering the heat treatment unit 20a (20b).

[0063] In the above embodiment, both the heat treatment systems 1 and 2 are provided with the gas tank 30, but both the heat treatment systems 1 and 2 may not be provided with the gas tank 30. In such a case, in the first control process (FIG. 2), the indicator concentration C H is the concentration threshold C A If the index concentration C is lower than the reference concentration C (step S11: YES), the control unit 40 opens the exhaust adjustment valve V2a (V2b) and closes the recovery adjustment valve V3a (V3b) (step S12). H is the concentration threshold C AIf this is the case (step S11: NO), the control unit 40 opens both the exhaust adjustment valve V2a and the recovery adjustment valve V3a without executing step S13 (step S14).

[0064] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0065] The present invention can also be realized in the following forms. [Application example 1] 1. A heat treatment system comprising: a heat treatment section capable of accommodating an object to be treated and heat-treating the object to be treated in a treatment gas; a supply flow path for supplying the processing gas to the heat treatment unit; an exhaust passage for exhausting the processing gas from the heat treatment section to the outside; a recovery flow path branching from the exhaust flow path and connected to the supply flow path, for recovering the processing gas from the exhaust flow path; an exhaust regulating valve provided in the exhaust flow path downstream of a position where the recovery flow path branches off, the exhaust regulating valve being capable of regulating a flow rate of the processing gas exhausted to the outside; a recovery adjusting valve provided in the recovery passage and capable of adjusting the flow rate of the processing gas to be recovered; a control unit that controls the heat treatment system, The control unit When an index concentration, which is a concentration of the target component in the processing gas in the thermal processing unit, is lower than a concentration threshold, the exhaust adjustment valve is opened while the recovery adjustment valve is closed; When the index concentration is equal to or greater than the concentration threshold, at least the recovery control valve of the exhaust control valve and the recovery control valve is opened. [Application example 2] The heat treatment system according to Application Example 1, further comprising: a gas tank provided in the recovery passage, capable of storing the processing gas recovered from the exhaust passage and delivering the stored processing gas to the supply passage; a first pressure measuring unit that measures the pressure inside the gas tank, The control unit When the index concentration is lower than the concentration threshold, or when the index pressure, which is the pressure in the gas tank, is equal to or higher than a first pressure threshold, the exhaust adjustment valve is opened while the recovery adjustment valve is closed; When the indicator concentration is equal to or greater than the concentration threshold value and the indicator pressure is lower than the first pressure threshold value, at least the recovery adjustment valve out of the exhaust adjustment valve and the recovery adjustment valve is opened. [Application example 3] The heat treatment system according to Application Example 1 or Application Example 2, further comprising: a generator that generates the processing gas and delivers it to the supply channel; The control unit When the index pressure is equal to or greater than the first pressure threshold, the generation of the processing gas by the generating unit is stopped and the processing gas is sent from the gas tank to the supply flow path; When the index pressure is lower than the first pressure threshold, the heat treatment system causes the generation unit to generate the processing gas while sending the processing gas from the gas tank to the supply flow path at a flow rate adjusted according to the index concentration and the index pressure. [Application example 4] The heat treatment system according to any one of Application Examples 1 to 3, a control unit that estimates the index concentration using the flow rate of the processing gas delivered from the generation unit to the supply flow path and the flow rate of the processing gas delivered from the gas tank to the supply flow path, and the concentration of the target component in the processing gas stored in the gas tank. [Application example 5] The heat treatment system according to any one of Application Examples 1 to 4, further comprising: a generating unit that generates the processing gas and sends it to the supply flow path; a gas tank that is provided in the supply flow path at a position to which the recovery flow path is connected, and that is capable of storing the processing gas generated in the generation unit and the processing gas recovered from the exhaust flow path and of delivering the stored processing gas to the supply flow path; a first pressure measuring unit that measures the pressure inside the gas tank, The control unit When an index pressure, which is the pressure in the gas tank, is equal to or greater than a first pressure threshold, the generation of the processing gas by the generation unit is stopped and the recovery adjustment valve is closed; When the index pressure is lower than the first pressure threshold, the heat treatment system adjusts the opening degree of the recovery adjustment valve in accordance with the index concentration and the index pressure while causing the generation unit to generate the process gas. [Application Example 6] The heat treatment system according to any one of Application Examples 1 to 5, The control unit estimates the index concentration using the flow rate of the processing gas delivered from the gas tank to the supply flow path and the concentration of the target component in the processing gas stored in the gas tank. [Application Example 7] The heat treatment system according to any one of Application Examples 1 to 6, further comprising: a second pressure measuring unit that measures the pressure in the heat treatment unit, a supply adjusting valve provided in a portion of the supply flow path downstream of a position where the recovery flow path is connected, the supply adjusting valve being capable of adjusting a supply flow rate, which is a flow rate of the processing gas supplied to the thermal processing unit; The control unit adjusts the flow rate of the processing gas delivered from the thermal processing unit and the supply flow rate by controlling the opening degree of the supply adjustment valve, the opening degree of the exhaust adjustment valve, and the opening degree of the recovery adjustment valve depending on the received instruction signal or whether the pressure in the thermal processing unit is higher than a second pressure threshold. [Explanation of symbols]

[0066] 1,2...Heat treatment system 10...Generation section 20a, 20b...heat treatment section 30...Gas tank 40...Control unit C2a, C2b...concentration sensors C3: Concentration sensor CM, Cm...Compressor F1, F1a, F1b, F1c...supply flow path F2, F2a, F2b...Exhaust passage F3, F3a, F3b, F3c, F3d...Recovery flow path P1a, P1b, P3...Pressure sensors V1a, V1b...supply adjustment valve V2a, V2b...Exhaust control valve V3a, V3b...Recovery adjustment valve V4: Delivery adjustment valve f1, f2...flow rate sensors

Claims

1. 1. A heat treatment system comprising: a heat treatment section capable of accommodating an object to be treated and heat-treating the object to be treated in a treatment gas; a supply flow path for supplying the processing gas to the heat treatment unit; an exhaust passage for exhausting the processing gas from the heat treatment section to the outside; a recovery flow path branching from the exhaust flow path and connected to the supply flow path, for recovering the processing gas from the exhaust flow path; an exhaust regulating valve provided in the exhaust flow path downstream of a position where the recovery flow path branches off, the exhaust regulating valve being capable of regulating a flow rate of the processing gas exhausted to the outside; a recovery adjusting valve provided in the recovery passage and capable of adjusting the flow rate of the processing gas to be recovered; a control unit that controls the heat treatment system, The control unit When an index concentration, which is a concentration of the target component in the processing gas in the thermal processing unit, is lower than a concentration threshold, the exhaust adjustment valve is opened while the recovery adjustment valve is closed; When the index concentration is equal to or greater than the concentration threshold, at least the recovery control valve of the exhaust control valve and the recovery control valve is opened.

2. 10. The thermal processing system of claim 1, further comprising: a gas tank provided in the recovery passage, capable of storing the processing gas recovered from the exhaust passage and delivering the stored processing gas to the supply passage; a first pressure measuring unit that measures the pressure inside the gas tank, The control unit When the index concentration is lower than the concentration threshold value, or when the index pressure, which is the pressure in the gas tank, is equal to or higher than a first pressure threshold value, the exhaust adjustment valve is opened while the recovery adjustment valve is closed; When the indicator concentration is equal to or greater than the concentration threshold value and the indicator pressure is lower than the first pressure threshold value, at least the recovery control valve of the exhaust control valve and the recovery control valve is opened.

3. 3. The heat treatment system of claim 2, further comprising: a generator that generates the processing gas and delivers it to the supply channel; The control unit When the index pressure is equal to or greater than the first pressure threshold, the generation of the processing gas by the generating unit is stopped and the processing gas is sent from the gas tank to the supply flow path; When the index pressure is lower than the first pressure threshold, the heat treatment system causes the generation unit to generate the processing gas while sending the processing gas from the gas tank to the supply flow path at a flow rate adjusted according to the index concentration and the index pressure.

4. 4. The heat treatment system of claim 3, a control unit that estimates the index concentration using the flow rate of the processing gas delivered from the generation unit to the supply flow path and the flow rate of the processing gas delivered from the gas tank to the supply flow path, and the concentration of the target component in the processing gas stored in the gas tank.

5. 10. The thermal processing system of claim 1, further comprising: a generating unit that generates the processing gas and sends it to the supply flow path; a gas tank that is provided in the supply flow path at a position to which the recovery flow path is connected, and that is capable of storing the processing gas generated in the generation unit and the processing gas recovered from the exhaust flow path and of delivering the stored processing gas to the supply flow path; a first pressure measuring unit that measures the pressure inside the gas tank, The control unit When an index pressure, which is the pressure in the gas tank, is equal to or greater than a first pressure threshold, the generation of the processing gas by the generation unit is stopped and the recovery adjustment valve is closed; When the index pressure is lower than the first pressure threshold, the heat treatment system adjusts the opening degree of the recovery adjustment valve in accordance with the index concentration and the index pressure while causing the generation unit to generate the process gas.

6. 6. The heat treatment system of claim 5, The control unit estimates the index concentration using the flow rate of the processing gas delivered from the gas tank to the supply flow path and the concentration of the target component in the processing gas stored in the gas tank.

7. 10. The thermal processing system of claim 1, further comprising: a second pressure measuring unit that measures the pressure in the heat treatment unit, a supply adjusting valve provided in a portion of the supply flow path downstream of a position where the recovery flow path is connected, the supply adjusting valve being capable of adjusting a supply flow rate, which is a flow rate of the processing gas supplied to the thermal processing unit; The control unit adjusts the flow rate of the processing gas delivered from the thermal processing unit and the supply flow rate by controlling the opening degree of the supply adjustment valve, the opening degree of the exhaust adjustment valve, and the opening degree of the recovery adjustment valve depending on the received instruction signal or whether the pressure in the thermal processing unit is higher than a second pressure threshold.

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