Gas switching system and gas switching method thereof

Abstract

The application discloses a gas switching system, which comprises the following parts: an air inlet end of a detection instrument connected with an instrument gas supply pipe; an air inlet end of an A exhaust valve connected with an air inlet end of a cut-off valve through a first pipeline, and an air outlet end connected with an air inlet of a gas concentration detector; an air outlet end of the cut-off valve connected with the instrument gas supply pipe; an air outlet end of an A pressure reducing valve connected with an air inlet end of an A gas supply valve; an air outlet end of the A gas supply valve connected with the first pipeline; an air outlet end of a B pressure reducing valve connected with an air inlet end of a B gas supply valve; an air outlet end of the B gas supply valve connected with the instrument gas supply pipe; an air inlet end of a B exhaust valve connected with the air outlet end of the B pressure reducing valve, and an air outlet end connected with the air inlet of the gas concentration detector; and the gas concentration detector used for detecting the gas concentration of the air inlet. The application further discloses a gas switching method of the gas switching system. The application can exhaust the mixed air when replacing the gas cylinder, avoids the problem that the detection instrument cannot work due to the mixed air when replacing the gas cylinder, and can replace the gas cylinder on line without shutdown.

Description

Technical Field

[0001] This invention relates to combustible gas detection technology, and in particular to a gas switching system and a gas switching method thereof. Background Technology

[0002] Currently, coating drying systems utilize a Low Explosive Limit (LEL) detector to monitor combustible gases in real-time under high-temperature (above 200°C) conditions. This detector requires continuous combustion of hydrogen to calculate the concentration of combustible gases in the drying system, ensuring that the concentration remains below safe limits and guaranteeing the safe operation of the production line. Figure 1 As shown, an existing LEL (Lower Explosive Limit) detector for real-time detection of combustible gases in a coating and drying system under high-temperature (above 200°C) conditions uses a 50L hydrogen cylinder for hydrogen supply. Over time, the hydrogen in the cylinders (Cylinder A and Cylinder B) is consumed, requiring replacement with a new hydrogen cylinder (Cylinder C). Each time the hydrogen cylinder is replaced, outside air is introduced into the pipeline between the shut-off valve and the pressure reducing valve, and this air cannot be expelled. As a result, the LEL detector fails to function due to insufficient hydrogen concentration, causing the coating and drying system to shut down. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to remove the air mixed in when changing the gas cylinder, so as to avoid the detection instrument from malfunctioning due to air mixing in when changing the gas cylinder, and to allow the gas cylinder to be changed online without stopping the machine.

[0004] To solve the above-mentioned technical problems, the present invention provides a gas switching system, which includes an A pressure reducing valve 11, an A gas supply valve 12, an A vent valve 13, a B pressure reducing valve 21, a B gas supply valve 22, a B vent valve 23, a gas concentration detector 31, an isolation valve 32, and a detection instrument 9.

[0005] One air inlet end of the detection instrument 9 is connected to the instrument's air supply pipe;

[0006] The A vent valve 13 has its inlet end connected to the inlet end of the isolation valve 32 via a first pipeline, and its outlet end connected to the inlet of the gas concentration detector 31 via a second pipeline.

[0007] The outlet end of the isolation valve 32 is connected to the instrument's air supply pipe;

[0008] The pressure reducing valve 11 (A) has its inlet end connected to the outlet of a gas cylinder, and its outlet end connected to the inlet end of the gas supply valve 12 (A) via a third pipeline.

[0009] The A gas supply valve 12 has its outlet connected to the first pipeline;

[0010] The B pressure reducing valve 21 has its inlet connected to the outlet of another gas cylinder and its outlet connected to the inlet of the B gas supply valve 22 through the fourth pipeline;

[0011] The B gas supply valve 22 has its outlet connected to the instrument gas supply pipeline;

[0012] The B emptying valve 23 has its inlet connected to the outlet of the B pressure reducing valve 21 and its outlet connected to the inlet of the gas concentration detector 31 through the fifth pipeline;

[0013] The gas concentration detector 31 is used to detect the concentration of gas at its inlet.

[0014] Preferably, a pressure gauge 41, a pressure buffer tank 42 and a pneumatic stop valve 43 are arranged on the instrument gas supply pipeline;

[0015] The pneumatic stop valve 43 is arranged between the pressure buffer tank 42 and the detection instrument 9;

[0016] One pressure gauge 41 is arranged on the instrument gas supply pipeline at the inlet side of the pressure buffer tank 42;

[0017] Another pressure gauge 41 is arranged on the instrument gas supply pipeline at the outlet side of the pressure buffer tank 42.

[0018] Preferably, the third pipeline and the fourth pipeline are flexible pipes;

[0019] The fifth pipeline is a rigid pipe;

[0020] The inlet of the A pressure reducing valve 11 is connected to the outlet of a gas cylinder through a flexible pipe;

[0021] The inlet of the B pressure reducing valve 21 is connected to the outlet of another gas cylinder through a flexible pipe.

[0022] Preferably, the gas cylinder is used to store hydrogen gas;

[0023] The gas concentration detector 31 is used to detect the concentration of hydrogen gas at its inlet.

[0024] Preferably, the detection instrument 9 is used to detect the concentration of combustible gas in a coating drying system;

[0025] The detection instrument 9 detects the concentration of combustible gas in a coating drying system by continuously burning hydrogen gas.

[0026] Preferably, the gas switching system further comprises a gas storage tank 44;

[0027] The pneumatic stop valve 43 and at least one of the A pressure reducing valve 11, the A gas supply valve 12, the A emptying valve 13, the B pressure reducing valve 21, the B gas supply valve 22, the B emptying valve 23 and the partition valve 32 are powered by the gas tank 44.

[0028] Preferably, the gas switching system further comprises a controller 8.

[0029] The actions of the pneumatic stop valve 43 and the A pressure reducing valve 11, the A gas supply valve 12, the A emptying valve 13, the B pressure reducing valve 21, the B gas supply valve 22, the B emptying valve 23 and the partition valve 32 are respectively controlled by valve control signals sent by the controller.

[0030] Preferably, the controller is a PLC or an MCU.

[0031] To solve the above technical problems, the gas switching method of the gas switching system provided by the present application comprises the following steps when switching from the gas supply by the gas cylinder connected to the inlet of the A pressure reducing valve 11 to the gas supply by the gas cylinder connected to the inlet of the B pressure reducing valve 21:

[0032] S11. Open the B emptying valve 23 at a first opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B emptying valve 23, then open the B pressure reducing valve 21, and make the outlet pressure of the B pressure reducing valve 21 less than the outlet pressure of the A pressure reducing valve 11, so that the gas in the gas cylinder connected to the inlet of the B pressure reducing valve 21 is discharged through the B emptying valve 23;

[0033] S12. Open the partition valve 32 and the A emptying valve 13.

[0034] S13. Open the B gas supply valve 22 at a second opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B gas supply valve 22, so that the gas in the fifth pipeline is discharged to the gas inlet of the gas concentration detector 31 under the gas pressure of the gas cylinder connected to the inlet of the A pressure reducing valve 11 and under the gas pressure of the gas cylinder connected to the inlet of the B pressure reducing valve 21.

[0035] S14. When the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the B emptying valve 23, and then increase the outlet pressure of the B pressure reducing valve 21 to the outlet pressure of the A pressure reducing valve 11 for gas supply.

[0036] S15. Close the A gas supply valve 12 and the partition valve 32.

[0037] S16. Switching is completed.

[0038] Preferably, when switching from the gas supply by the gas cylinder connected to the inlet of the B pressure reducing valve 21 to the gas supply by the gas cylinder connected to the inlet of the A pressure reducing valve 11, the method comprises the following steps:

[0039] S21. Open the A exhaust valve 13 at a third opening degree, which is 1 / 1000~1 / 10 of the maximum opening degree of the A exhaust valve 13, and then open the A pressure reducing valve 11, and make the gas pressure value at the outlet of the A pressure reducing valve 11 less than the gas pressure value at the outlet of the B pressure reducing valve 21;

[0040] S22. Open the A gas supply valve 12, so that the gas in the gas cylinder connected to the gas inlet of the A pressure reducing valve 11 is discharged to the gas concentration detector 31 through the A gas supply valve 12 and the A exhaust valve 13;

[0041] S23. When the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the A exhaust valve 13;

[0042] S24. Close the B gas supply valve 22;

[0043] S25. Switching is completed.

[0044] Preferably, in step S14, when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, the B exhaust valve 23 is closed, and when the pressure in the instrument gas supply pipe is stable, the gas supply is performed by increasing the gas pressure value at the outlet of the B pressure reducing valve 21 to be higher than the gas pressure value at the outlet of the A pressure reducing valve 11;

[0045] In step S24, when the pressure in the instrument gas supply pipe is stable, the B gas supply valve 22 is closed.

[0046] Preferably, when the difference between the pressure at the inlet side and the pressure at the outlet side of the pressure buffer tank 42 is less than a set value, the pressure in the instrument gas supply pipe is stable.

[0047] Preferably, in step S22, the A gas supply valve 12 is opened, and then the cut-off valve 32 is opened.

[0048] Preferably, in step S23, when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, the A exhaust valve 13 is closed and the cut-off valve 32 is opened.

[0049] Preferably, in step S15, the A exhaust valve 13 is also closed.

[0050] Preferably, in step S12, the cut-off valve 32 and the A exhaust valve 13 are opened at 1 / 1000~1 / 10 of their maximum opening degrees, respectively.

[0051] Preferably, after the switching from the gas supply by the gas cylinder connected to the gas inlet of the A pressure reducing valve 11 to the gas supply by the gas cylinder connected to the gas inlet of the B pressure reducing valve 21 is completed, the gas cylinder currently connected to the gas inlet of the A pressure reducing valve 11 is removed, and a standby gas cylinder is connected to the gas inlet of the A pressure reducing valve 11, so that the replacement of the gas cylinder connected to the gas inlet of the A pressure reducing valve 11 is completed.

[0052] After the gas supply from the gas cylinder connected to the gas inlet end of the B pressure reducing valve 21 is switched to the gas supply from the gas cylinder connected to the gas inlet end of the A pressure reducing valve 11, the gas cylinder currently connected to the gas inlet end of the B pressure reducing valve 21 is removed, and a standby gas cylinder is connected to the gas inlet end of the B pressure reducing valve 21, thereby completing the replacement of the gas cylinder connected to the gas inlet end of the B pressure reducing valve 21.

[0053] The gas switching system and the gas switching method thereof can discharge the mixed air when replacing the gas cylinder, avoid the detection instrument from being unable to work due to the mixed air when replacing the gas cylinder, replace the gas cylinder on line without shutdown, and reduce the production loss caused by the shutdown of the production line system. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0055] Figure 1 is a schematic diagram of a LEL detector for real-time detection of flammable gas in a coating and drying system in a high-temperature environment;

[0056] Figure 2 is a schematic diagram of the gas switching system of the present application.

[0057] BRIEF DESCRIPTION OF DRAWINGS

[0058] 11A pressure reducing valve; 12A gas supply valve; 13A air exhaust valve; 21B pressure reducing valve; 22B gas supply valve; 23B air exhaust valve; 31 gas concentration detector; 32 isolation valve; 9 detection instrument; 41 pressure gauge; 42 pressure buffer tank; 43 pneumatic stop valve; 44 gas storage tank; 8 controller. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0060] The terms "first", "second", and similar terms used in the present application do not denote any order, quantity, or importance, but are used to distinguish different constituent parts. The terms "include", "contain", and similar terms mean that the elements or objects before the terms encompass the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connect" or "connected" or similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "upper", "lower", "left", "right", "front", "back", and the like are used only to indicate relative positional relationships, and when the absolute positions of the described objects are changed, the relative positional relationships can also be changed accordingly.

[0061] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0062] Embodiment one

[0063] A gas switching system as shown in the figure, which comprises an A pressure reducing valve 11, an A gas supply valve 12, an A emptying valve 13, a B pressure reducing valve 21, a B gas supply valve 22, a B emptying valve 23, a gas concentration detector 31, a partition valve 32, and a detector instrument 9. Figure 2

[0064] The gas inlet end of the detector instrument 9 is connected to the instrument gas supply pipe.

[0065] The gas inlet end of the A emptying valve 13 is connected to the gas inlet end of the partition valve 32 through a first pipe, and the gas outlet end is connected to the gas inlet of the gas concentration detector 31 through a second pipe.

[0066] The gas outlet end of the partition valve 32 is connected to the instrument gas supply pipe.

[0067] The gas inlet end of the A pressure reducing valve 11 is used to connect to the gas outlet of a gas cylinder, and the gas outlet end is connected to the gas inlet end of the A gas supply valve 12 through a third pipe.

[0068] The gas outlet end of the A gas supply valve 12 is connected to the first pipe.

[0069] The gas inlet end of the B pressure reducing valve 21 is used to connect to the gas outlet of another gas cylinder, and the gas outlet end is connected to the gas inlet end of the B gas supply valve 22 through a fourth pipe.

[0070] The gas outlet end of the B gas supply valve 22 is connected to the instrument gas supply pipe.

[0071] The gas inlet end of the B emptying valve 23 is connected to the gas outlet end of the B pressure reducing valve 21, and the gas outlet end is connected to the gas inlet of the gas concentration detector 31 through a fifth pipe.

[0072] ​The gas concentration detector 31 is used to detect the gas concentration of the gas inlet.

[0073] The gas switching system of the first embodiment can discharge the mixed air when replacing the gas cylinder, avoids the situation that the detector 9 cannot work due to the mixed air when replacing the gas cylinder, can replace the gas cylinder on line without stopping, and can reduce the production loss caused by the stop of the production line system.

[0074] The second embodiment

[0075] The gas switching system of the first embodiment, the instrument gas supply pipe is provided with a pressure gauge 41, a pressure buffer tank 42 and a pneumatic stop valve 43;

[0076] The pneumatic stop valve 43 is arranged between the pressure buffer tank 42 and the detector 9;

[0077] One pressure gauge 41 is arranged on the instrument gas supply pipe on the gas inlet side of the pressure buffer tank 42;

[0078] Another pressure gauge 41 is arranged on the instrument gas supply pipe on the gas outlet side of the pressure buffer tank 42.

[0079] Preferably, the third pipeline and the fourth pipeline are flexible pipes;

[0080] The fifth pipeline is a rigid pipe;

[0081] The gas inlet end of the A pressure reducing valve 11 is connected to the gas outlet of one gas cylinder through a flexible pipe;

[0082] The gas inlet end of the B pressure reducing valve 21 is connected to the gas outlet of another gas cylinder through a flexible pipe.

[0083] Preferably, the gas cylinder is used to store hydrogen;

[0084] The gas concentration detector 31 is used to detect the hydrogen concentration of the gas inlet.

[0085] Preferably, the detector 9 is used to detect the combustible gas concentration in the coating drying system;

[0086] The detector 9 detects and calculates the combustible gas concentration in the coating drying system by continuously burning hydrogen.

[0087] Preferably, the gas switching system further comprises a gas storage tank 44;

[0088] The pneumatic stop valve 43 and at least one of the A pressure reducing valve 11, the A gas supply valve 12, the A emptying valve 13, the B pressure reducing valve 21, the B gas supply valve 22, the B emptying valve 23 and the partition valve 32 are powered by the gas storage tank 44.

[0089] Preferably, the gas switching system further comprises a controller 8.

[0090] The controller 8 is signal connected with the A pressure reducing valve 11, the A gas supply valve 12, the A gas exhaust valve 13, the B pressure reducing valve 21, the B gas supply valve 22, the B gas exhaust valve 23, the gas concentration detector 31, the partition valve 32, the pressure gauge 41 and the pneumatic stop valve 43.

[0091] The pneumatic stop valve 43 and the A pressure reducing valve 11, the A gas supply valve 12, the A gas exhaust valve 13, the B pressure reducing valve 21, the B gas supply valve 22, the B gas exhaust valve 23 and the partition valve 32 are respectively controlled by the valve control signals sent by the controller 8.

[0092] Preferably, the controller 8 is a PLC (programmable logic controller) or an MCU (microprocessor).

[0093] Embodiment Three

[0094] The gas switching method of the gas switching system of Embodiment One or Two comprises the following steps when switching the gas supply from the gas cylinder (A cylinder) connected to the inlet of the A pressure reducing valve 11 to the gas cylinder (B cylinder) connected to the inlet of the B pressure reducing valve 21.

[0095] S11. Open the B gas exhaust valve 23 at a first opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B gas exhaust valve 23, then open the B pressure reducing valve 21, and make the outlet pressure of the B pressure reducing valve 21 less than the outlet pressure of the A pressure reducing valve 11 (preferably, the outlet pressure of the B pressure reducing valve 21 is 2 / 3 of the outlet pressure of the A pressure reducing valve 11), so that the gas in the gas cylinder (B cylinder) connected to the inlet of the B pressure reducing valve 21 is exhausted through the B gas exhaust valve 23;

[0096] S12. Open the partition valve 32 and the A gas exhaust valve 13.

[0097] S13. Open the B gas supply valve 22 at a second opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B gas supply valve 22, so that the gas in the fifth pipeline is exhausted to the inlet of the gas concentration detector 31 under the gas pressure of the gas cylinder connected to the inlet of the A pressure reducing valve 11 and under the gas pressure of the gas cylinder connected to the inlet of the B pressure reducing valve 21.

[0098] S14. When the gas concentration at the inlet of the gas concentration detector 31 reaches a set value, close the B gas exhaust valve 23, and then increase the outlet pressure of the B pressure reducing valve 21 to the outlet pressure of the A pressure reducing valve 11 (preferably, the outlet pressure of the B pressure reducing valve 21 is 1-1.5 times of the outlet pressure of the A pressure reducing valve 11) for gas supply.

[0099] S15. Close the A gas supply valve 12 and the partition valve 32.

[0100] S16. Switching is completed.

[0101] Preferably, the A exhaust valve 13 is also closed in step S15.

[0102] Preferably, the block valve 32 and the A exhaust valve 13 are respectively opened to 1 / 1000-1 / 10 of their maximum opening in step S12.

[0103] In the gas switching method of embodiment three, when switching from the gas supplied by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supplied by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21, the B exhaust valve 23 is first slightly opened, then the B pressure reducing valve 21 is opened, and the gas outlet pressure value of the B pressure reducing valve 21 is made less than the gas outlet pressure value of the A pressure reducing valve 11, so that the gas in the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 is discharged through the B exhaust valve 23, then the block valve 32 and the A exhaust valve 13 are opened, and the B gas supply valve 22 is slightly opened, so that the gas in the pipeline between the B pressure reducing valve 21 and the gas concentration detector 31 is discharged to the gas inlet of the gas concentration detector 31 under the gas pressure of the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 and under the gas pressure of the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21; when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, the B exhaust valve 23 is closed, and the gas outlet pressure of the B pressure reducing valve 21 is adjusted to the normal gas outlet pressure of the A pressure reducing valve 11 for gas supply; then the A gas supply valve 12 is closed, the block valve 32 is closed, and the switching is completed, which can be automatically controlled by the controller 8 program. During the switching from the gas supplied by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supplied by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21, the air mixed in the B pressure reducing valve 21 and the B gas supply valve 22 is discharged, and then the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 starts to supply gas to the instrument gas supply pipe, so that the detector instrument 9 can work without insufficient gas concentration.

[0104] Embodiment four

[0105] In the gas switching method of embodiment three, when switching from the gas supplied by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supplied by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21, the B exhaust valve 23 is first slightly opened, then the B pressure reducing valve 21 is opened, and the gas outlet pressure value of the B pressure reducing valve 21 is made less than the gas outlet pressure value of the A pressure reducing valve 11, so that the gas in the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 is discharged through the B exhaust valve 23, then the block valve 32 and the A exhaust valve 13 are opened, and the B gas supply valve 22 is slightly opened, so that the gas in the pipeline between the B pressure reducing valve 21 and the gas concentration detector 31 is discharged to the gas inlet of the gas concentration detector 31 under the gas pressure of the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 and under the gas pressure of the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21; when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, the B exhaust valve 23 is closed, and the gas outlet pressure of the B pressure reducing valve 21 is adjusted to the normal gas outlet pressure of the A pressure reducing valve 11 for gas supply; then the A gas supply valve 12 is closed, the block valve 32 is closed, and the switching is completed, which can be automatically controlled by the controller 8 program. During the switching from the gas supplied by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supplied by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21, the air mixed in the B pressure reducing valve 21 and the B gas supply valve 22 is discharged, and then the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 starts to supply gas to the instrument gas supply pipe, so that the detector instrument 9 can work without insufficient gas concentration.

[0106] S21. The A exhaust valve 13 is opened to a third opening, which is 1 / 1000-1 / 10 of the maximum opening of the A exhaust valve 13, then the A pressure reducing valve 11 is opened, and the gas outlet pressure value of the A pressure reducing valve 11 is made less than the gas outlet pressure value of the B pressure reducing valve 21 (preferably, the gas outlet pressure value of the A pressure reducing valve 11 is made less than 2 / 3 of the gas outlet pressure value of the B pressure reducing valve 21);

[0107] S22. Open the A gas supply valve 12, so that the gas in the gas cylinder connected to the gas inlet end of the A pressure reducing valve 11 is discharged through the A gas supply valve 12 and the A exhaust valve 13 to the gas concentration detector 31 gas inlet;

[0108] S23. When the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the A exhaust valve 13.

[0109] S24. Close the B gas supply valve 22.

[0110] S25. Switching is complete.

[0111] Preferably, in step S14, when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the B exhaust valve 23, and when the pressure in the instrument gas supply pipe stabilizes, increase the B pressure reducing valve 21 outlet gas pressure to above the A pressure reducing valve 11 outlet gas pressure for gas supply.

[0112] In step S24, when the pressure in the instrument gas supply pipe stabilizes, close the B gas supply valve 22.

[0113] Preferably, when the difference between the pressure on the inlet side and the outlet side of the pressure buffer tank 42 is less than a set value, the pressure in the instrument gas supply pipe stabilizes.

[0114] Preferably, in step S22, open the A gas supply valve 12 and then open the isolation valve 32.

[0115] Preferably, in step S23, when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the A exhaust valve 13 and open the isolation valve 32.

[0116] In the gas switching method of Example Four, when switching from gas supply by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 to gas supply by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11, first slightly open the A exhaust valve 13, then open the A pressure reducing valve 11, and make the A pressure reducing valve 11 outlet gas pressure value less than the B pressure reducing valve 21 outlet gas pressure value; then open the A gas supply valve 12, so that the gas in the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 is discharged through the A gas supply valve 12 and the A exhaust valve 13 to the gas inlet of the gas concentration detector 31, and when the gas concentration at the gas inlet of the gas concentration detector 31 reaches a set value, close the A exhaust valve 13 and then close the B gas supply valve 22, completing the switching. The above actions can be automatically controlled by the controller 8 program. During the process of switching from gas supply by the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 to gas supply by the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11, the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 only starts to supply gas to the instrument gas supply pipe after the air mixed into the A pressure reducing valve 11 to the A gas supply valve 12 is discharged, and the detection instrument 9 will not fail to work due to insufficient gas concentration.

[0117] Example Five

[0118] The gas switching method of the gas switching system of Example Four, after the switching of the gas supply from the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supply from the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 is completed, the gas cylinder (A cylinder) currently connected to the gas inlet end of the A pressure reducing valve 11 is removed, a standby gas cylinder (C cylinder) is connected to the gas inlet end of the A pressure reducing valve 11, and the replacement of the gas cylinder connected to the gas inlet end of the A pressure reducing valve 11 is completed.

[0119] The gas switching method of the gas switching system of Example Four, after the switching of the gas supply from the gas cylinder (A cylinder) connected to the gas inlet end of the A pressure reducing valve 11 to the gas supply from the gas cylinder (B cylinder) connected to the gas inlet end of the B pressure reducing valve 21 is completed, the gas cylinder (A cylinder) currently connected to the gas inlet end of the A pressure reducing valve 11 is removed, a standby gas cylinder (C cylinder) is connected to the gas inlet end of the A pressure reducing valve 11, and the replacement of the gas cylinder connected to the gas inlet end of the A pressure reducing valve 11 is completed.

[0120] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A gas switching system, characterized by It comprises an A pressure reducing valve (11), an A gas supply valve (12), an A exhaust valve (13), a B pressure reducing valve (21), a B gas supply valve (22), a B exhaust valve (23), a gas concentration detector (31), a cut-off valve (32) and a detector (9); The detector (9) has an air inlet connected to a gas supply pipe; The A exhaust valve (13) has an air inlet connected to the air inlet of the cut-off valve (32) through a first pipe, and an air outlet connected to the air inlet of the gas concentration detector (31) through a second pipe; The cut-off valve (32) has an air outlet connected to the gas supply pipe; The A pressure reducing valve (11) has an air inlet connected to the air outlet of a gas cylinder, and an air outlet connected to the air inlet of the A gas supply valve (12) through a third pipe; The A gas supply valve (12) has an air outlet connected to the first pipe; The B pressure reducing valve (21) has an air inlet connected to the air outlet of another gas cylinder, and an air outlet connected to the air inlet of the B gas supply valve (22) through a fourth pipe; The B gas supply valve (22) has an air outlet connected to the gas supply pipe; The B exhaust valve (23) has an air inlet connected to the air outlet of the B pressure reducing valve (21), and an air outlet connected to the air inlet of the gas concentration detector (31) through a fifth pipe; The gas concentration detector (31) is used to detect the concentration of gas at its air inlet.

2. The gas switching system according to claim 1, wherein A pressure gauge (41), a pressure buffer tank (42) and a pneumatic stop valve (43) are arranged on the gas supply pipe; The pneumatic stop valve (43) is arranged between the pressure buffer tank (42) and the detector (9); One pressure gauge (41) is arranged on the gas supply pipe at the air inlet side of the pressure buffer tank (42); Another pressure gauge (41) is arranged on the gas supply pipe at the air outlet side of the pressure buffer tank (42).

3. The gas switching system according to claim 1, wherein The third pipe and the fourth pipe are flexible pipes; The fifth pipe is a rigid pipe; The air inlet of the A pressure reducing valve (11) is connected to the air outlet of a gas cylinder through a flexible pipe; The air inlet of the B pressure reducing valve (21) is connected to the air outlet of another gas cylinder through a flexible pipe.

4. The gas switching system according to claim 1, wherein The gas cylinders are used to store hydrogen gas; The gas concentration detector (31) is used to detect the concentration of hydrogen gas at its air inlet.

5. The gas switching system according to claim 4, wherein The detector (9) is used to detect the concentration of combustible gas in a coating drying system; The detector (9) detects the concentration of combustible gas in a coating drying system by continuously burning hydrogen gas.

6. The gas switching system according to claim 2, wherein The gas switching system further comprises a gas storage tank (44); The pneumatic stop valve (43) and at least one of the A pressure reducing valve (11), the A gas supply valve (12), the A exhaust valve (13), the B pressure reducing valve (21), the B gas supply valve (22), the B exhaust valve (23) and the cut-off valve (32) are powered by the gas storage tank (44).

7. The gas switching system according to claim 2, wherein the gas switching system further comprises a controller (8); the actions of the pneumatic shut-off valve (43), the A pressure reducing valve (11), the A gas supply valve (12), the A exhaust valve (13), the B pressure reducing valve (21), the B gas supply valve (22), the B exhaust valve (23), and the isolation valve (32) are controlled by valve control signals sent by the controller.

8. The gas switching system according to claim 7, wherein the controller is a PLC or a MCU.

9. A gas switching method for the gas switching system according to claim 1 or 2, wherein when switching from the gas supply from the gas cylinder connected to the inlet of the A pressure reducing valve (11) to the gas supply from the gas cylinder connected to the inlet of the B pressure reducing valve (21), the method comprises the following steps: S11. opening the B exhaust valve (23) at a first opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B exhaust valve (23), and then opening the B pressure reducing valve (21) and making the outlet pressure of the B pressure reducing valve (21) lower than the outlet pressure of the A pressure reducing valve (11), so that the gas in the gas cylinder connected to the inlet of the B pressure reducing valve (21) is exhausted through the B exhaust valve (23); S12. opening the isolation valve (32) and the A exhaust valve (13); S13. opening the B gas supply valve (22) at a second opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the B gas supply valve (22), so that the gas in the fifth pipeline is exhausted to the gas concentration detector (31) inlet under the gas pressure of the gas cylinder connected to the inlet of the A pressure reducing valve (11) and under the gas pressure of the gas cylinder connected to the inlet of the B pressure reducing valve (21); S14. when the gas concentration at the inlet of the gas concentration detector (31) reaches a set value, closing the B exhaust valve (23), and then increasing the outlet pressure of the B pressure reducing valve (21) to the outlet pressure of the A pressure reducing valve (11) for gas supply; S15. closing the A gas supply valve (12) and the isolation valve (32); S16. switching is completed.

10. The gas switching method according to claim 9, wherein when switching from the gas supply from the gas cylinder connected to the inlet of the B pressure reducing valve (21) to the gas supply from the gas cylinder connected to the inlet of the A pressure reducing valve (11), the method comprises the following steps: S21. opening the A exhaust valve (13) at a third opening degree, which is 1 / 1000-1 / 10 of the maximum opening degree of the A exhaust valve (13), and then opening the A pressure reducing valve (11) and making the outlet pressure of the A pressure reducing valve (11) lower than the outlet pressure of the B pressure reducing valve (21); S22. opening the A gas supply valve (12), so that the gas in the gas cylinder connected to the inlet of the A pressure reducing valve (11) is exhausted to the gas concentration detector (31) inlet through the A gas supply valve (12) and the A exhaust valve (13); S23. when the gas concentration at the inlet of the gas concentration detector (31) reaches a set value, closing the A exhaust valve (13); S24. closing the B gas supply valve (22); S25. switching is completed.

11. The gas switching method according to claim 10, wherein ​ ​ ​ ​ ​ In step S14, when the gas concentration at the gas inlet of the gas concentration detector (31) reaches a set value, the B exhaust valve (23) is closed, and when the pressure in the instrument gas supply pipe stabilizes, the B pressure reducing valve (21) is adjusted to a gas outlet pressure higher than that of the A pressure reducing valve (11) to supply gas; In step S24, when the pressure in the instrument gas supply pipe stabilizes, the B gas supply valve (22) is closed.

12. The gas switching method according to claim 11, wherein When the difference between the pressure at the gas inlet side and the pressure at the gas outlet side of the pressure buffer tank (42) is less than a set value, the pressure in the instrument gas supply pipe stabilizes.

13. The gas switching method according to claim 10, wherein In step S22, the A gas supply valve (12) is opened, and then the cutoff valve (32) is opened.

14. The gas switching method according to claim 10, wherein In step S23, when the gas concentration at the gas inlet of the gas concentration detector (31) reaches a set value, the A exhaust valve (13) is closed and the cutoff valve (32) is opened.

15. The gas switching system according to claim 9, wherein In step S15, the A exhaust valve (13) is also closed.

16. The gas switching method according to claim 9, wherein In step S12, the cutoff valve (32) and the A exhaust valve (13) are opened at 1 / 1000 to 1 / 10 of their maximum opening degree, respectively.

17. The gas switching method according to claim 10, wherein After the switching from the gas supply from the gas cylinder connected to the gas inlet end of the A pressure reducing valve (11) to the gas supply from the gas cylinder connected to the gas inlet end of the B pressure reducing valve (21) is completed, the gas cylinder currently connected to the gas inlet end of the A pressure reducing valve (11) is detached, and a spare gas cylinder is connected to the gas inlet end of the A pressure reducing valve (11), thereby completing the replacement of the gas cylinder connected to the gas inlet end of the A pressure reducing valve (11); After the switching from the gas supply from the gas cylinder connected to the gas inlet end of the B pressure reducing valve (21) to the gas supply from the gas cylinder connected to the gas inlet end of the A pressure reducing valve (11) is completed, the gas cylinder currently connected to the gas inlet end of the B pressure reducing valve (21) is detached, and a spare gas cylinder is connected to the gas inlet end of the B pressure reducing valve (21), thereby completing the replacement of the gas cylinder connected to the gas inlet end of the B pressure reducing valve (21).

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