Safe gas collection and detection device and control method thereof

Abstract

The invention relates to the technical field of gas detection, and provides a safe gas collection and detection device and a control method thereof, which can prevent leakage and accumulation of sample gas caused by untight sealing of a gas circuit of the device when combustible or toxic and harmful gas is detected, and improve the long-term stability of a gas analyzer. The device has high safety, the capability of automatically detecting and treating hazardous gas in the device is increased, a gas concentration collecting point in the device is designed, when it is detected that the gas concentration in the device exceeds the limit, power-off operation on the device is executed, ignition and explosion risks of combustible gas are prevented, meanwhile, the vacuum generator is started to generate negative pressure, and the safety of the device is improved. Gas in the device is discharged through the vacuum generator, external clean air is injected, and hazardous gas replacement is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a safe gas collection and detection device and a control method thereof. Background Art

[0002] The existing gas collection and detection device (hereinafter referred to as the device) uses one or two vacuum pumps to extract and sample the gas in the detection space in a certain order, and sends the sampled gas to the gas analyzer for concentration detection after filtering and gas-water separation. After the concentration detection is completed, the exhaust gas is discharged from the device into an environmentally safe area. Although flame arresters are installed at the air inlet and outlet of the device to prevent the ignition and explosion of combustible gases from affecting the detection space and the external environment of the device, the aging of the gas circuit seals during long-term use is often overlooked, which may lead to the risk of gas leakage in the gas circuit. When the gas circuit is not sealed tightly and leaks, flammable or toxic and harmful gases will accumulate in the device, and the concentration will exceed the safety limit. The device is generally placed in a limited space such as a control room or a dispatching room, posing a threat to the personal safety of the staff therein. At the same time, the gas analyzer has zero drift and range drift during long-term operation, requiring equipment maintenance personnel to perform regular calibration of the zero point and range. The on-site space is small and the calibration operation is relatively difficult. Summary of the Invention

[0003] In view of this, the present invention provides a safe gas collection and detection device and a control method thereof, which can prevent the leakage and accumulation of sample gas due to poor sealing of the device's gas path when detecting flammable or toxic and harmful gases, while improving the long-term stability of the gas analyzer.

[0004] To achieve the above-mentioned purpose, the present invention proposes a safe gas collection and detection device, comprising: a gas collection and detection device body and a control system; the gas collection and detection device body comprises:

[0005] The dual vacuum pump module includes a detection vacuum pump and a sampling vacuum pump, which are used to extract sample gas from the detection gas circuit and temporarily store sample gas in the pre-sampling gas circuit respectively;

[0006] The grouped collection gas path module includes group A and group B collection points. Each group includes multiple collection points, and the gas path is controlled by a solenoid valve;

[0007] Internal gas concentration detection module, including gas collection points inside the device and external clean air collection points, used to detect the gas concentration inside the device and trigger zero point calibration;

[0008] Hazardous gas displacement module, including vacuum generator, solenoid valve and displacement port, used to discharge hazardous gas through negative pressure and inject clean air when the concentration exceeds the limit;

[0009] Gas circuit status monitoring module, including flow sensor, pressure sensor and vacuum gauge, used to detect gas circuit status in real time;

[0010] The control system includes:

[0011] Dual power switching module for automatic switching between primary and backup power supplies;

[0012] The safety response module cuts off the power supply to the device and starts the gas replacement process after receiving the concentration limit signal through the PLC;

[0013] The automatic calibration module regularly collects external clean air to trigger the zero point calibration of the gas analyzer and supports manual range calibration.

[0014] Among them, in the grouped collection gas path module, group A and group B perform detection and pre-sampling operations alternately in sequence, specifically:

[0015] When the detection vacuum pump starts the collection point of group A, the sampling vacuum pump will start the next collection point of group B simultaneously for pre-sampling;

[0016] After the detection is completed, switch to group B detection, and at the same time pre-sampling is performed at the next collection point of group A, and the order of A1→B1→A2→B2→…→An→Bn is executed cyclically.

[0017] Among them, the hazardous gas replacement module also includes an air injection port, which is connected to the air compressor and switched to the purge position through the solenoid valve. The compressed air generates negative pressure through the vacuum generator to discharge the hazardous gas in the device to a safe area; the replacement port injects external clean air through the B1 point pipeline and continuously replaces until the internal concentration is lower than the safety threshold.

[0018] Wherein, the automatic calibration module includes:

[0019] The timing trigger unit collects clean air at point B1 at every preset time and sends a zero point calibration instruction to the gas analyzer;

[0020] Calibration verification unit: re-measure point B1 after calibration. If the deviation exceeds 2% of the full scale, an alarm is triggered;

[0021] Manual range calibration interface, connect the standard gas cylinder through the solenoid valve for range calibration.

[0022] Among them, the alarm conditions of the gas path status monitoring module include:

[0023] When the flow sensor detection value is lower than 0.5L / min, the air path is determined to be blocked;

[0024] When the pressure sensor detection value exceeds 50kPa or is lower than 10kPa, the pump is judged to be faulty;

[0025] When the vacuum gauge detection value exceeds the range of -80kPa to -20kPa, a shutdown alarm is triggered.

[0026] Among them, the control system also includes: a gas-water separator maintenance module, which opens the drainage solenoid valve regularly through PLC to discharge the stored water; a forced opening button, which cuts off the power supply and triggers the gas replacement process in an emergency.

[0027] The present invention also proposes a control method for the gas collection and detection device of the present invention, comprising the following steps:

[0028] Step S1: Device startup and self-test:

[0029] The control system switches to the main power supply, and the PLC initializes and detects the vacuum pump and samples the vacuum pump status;

[0030] Check the initial position of the solenoid valve, read the flow, pressure and vacuum data, and enter the purge process after confirming that the air path is unobstructed;

[0031] Step S2, alternating collection and detection:

[0032] Control the A group detection gas circuit and the B group pre-sampling gas circuit to run synchronously, and switch to the B group detection and A group pre-sampling after the detection is completed;

[0033] The cycle continues until all collection points are tested. If the gas concentration in the device is detected to be above the limit, the PLC outputs a dry contact signal to the control system, cuts off the power supply, and activates the vacuum generator to exhaust the dangerous gas. Clean air is injected through the displacement port and continues to be replaced until the concentration is below the safety threshold.

[0034] Regularly collect external clean air to trigger zero-point calibration and verify the calibration results; regularly open the drain solenoid valve every day to drain the water accumulated in the air-water separator.

[0035] The specific process of alternating collection and detection in step S2 includes:

[0036] The detection pump extracts the sample gas of the current collection point of group A to the analyzer, and at the same time the sampling pump extracts the sample gas of the next collection point of group B for temporary storage;

[0037] After completing the detection of group A, switch to the detection of group B and trigger the zero point calibration. At the same time, the sampling pump extracts the sample gas from the next collection point of group A;

[0038] Execute in a loop according to the grouping order to shorten the overall detection cycle.

[0039] The gas replacement process in step S3 further includes:

[0040] After the device is powered off, the solenoid valve switches to the purge position, and the compressed air enters the vacuum generator through the pressure reducing filter;

[0041] After the dangerous gas in the negative pressure extraction device is mixed with compressed air, it is discharged to a safe area through a flame arrester;

[0042] After the replacement lasts for a set time, the maintenance personnel reset the system and re-apply power.

[0043] The manual range calibration in step S4 includes:

[0044] Open the solenoid valve to connect the standard gas cylinder, and use the test pump to extract the standard gas to the analyzer;

[0045] The analyzer reads the concentration and adjusts the range parameters. After calibration, the solenoid valve is closed.

[0046] Beneficial effects:

[0047] 1. The device of the present invention has high safety, increases the ability to automatically detect and process dangerous gases in the device, and designs a gas concentration collection point inside the device. When it is detected that the gas concentration in the device exceeds the limit, the device is powered off to prevent the risk of ignition and explosion of combustible gases. At the same time, the vacuum generator is started to generate negative pressure, so that the gas in the device is discharged through the vacuum generator and external clean air is injected to achieve dangerous gas replacement.

[0048] 2. The device of the present invention adopts a dual sampling pump design, one for detection and the other for collection. While detecting one path, the sample gas of the next path is collected in advance, shortening the entire sampling and detection cycle.

[0049] 3. The device of the present invention has strong stability. It can collect clean air at regular intervals while collecting and detecting, so as to realize automatic zero point calibration of the gas analyzer. Equipment maintenance personnel only need to perform range calibration regularly.

[0050] 4. In the device of the present invention, the gas concentration in the device is detected while collecting and detecting. The start and stop of the device are controlled according to the detection results, and the dangerous gas in the device is replaced to prevent the leakage and accumulation of sample gas due to poor sealing of the device gas path when detecting flammable or toxic and harmful gases, which poses a safety threat to the environment where the device is located.

[0051] 5. In the device of the present invention, the pipeline is regularly connected to the external clean air, which is sucked into the gas analyzer through the vacuum pump. The zero point calibration instruction is executed on the gas analyzer in the device to complete the zero point calibration, realizing the regular automatic zero point calibration function. The automatic zero point calibration can reduce the instrument calibration workload of maintenance personnel.

[0052] 6. The control method for the gas collection and detection device of this invention incorporates multiple safety mechanisms. When concentration exceeds a limit, the PLC immediately shuts off power and initiates a gas replacement process. Through the coordinated operation of vacuum generator ZF1 and solenoid valve VC1, hazardous gases within the device are expelled, allowing clean air from outside to flow in through the replacement port, effectively preventing the risk of explosion or poisoning. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of the composition and connection of a gas collection and detection device according to an embodiment of the present invention.

[0054] Figure 2 This is a schematic diagram of the gas path design of the main body of the gas collection and detection device of the present invention.

[0055] Figure 3 This is a schematic diagram of the internal electrical layout of the control system of the gas collection and detection device of the present invention.

[0056] Figure 4 This is a schematic diagram of the control system circuit of the gas collection and detection device of the present invention. DETAILED DESCRIPTION

[0057] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0058] The present invention provides a safe gas collection and detection device that supports multi-point sequential collection and detection. The device of the present invention includes a gas collection and detection device body and a control system. In this embodiment, the control system is an external control box. The gas collection and detection device of the embodiment of the present invention is composed and connected as follows: Figure 1 shown.

[0059] Specifically, the main body of the gas collection and detection device includes a control unit, a solenoid valve, a vacuum pump, an audible and visual alarm, a flow sensor, a pressure sensor and a gas analyzer;

[0060] The control unit is a PLC, which is used to control the solenoid valves, vacuum pumps, and sound and light alarms in each gas collection path, as well as the data collection and communication configuration of the flow sensor, pressure sensor, and gas analyzer, as well as data transmission outside the device;

[0061] In this embodiment, the main body of the device uses two vacuum pumps to collect or detect sample gas at two collection points at the same time, and all collection points are divided into two groups, A and B. The two groups perform collection or detection actions alternately in sequence, thereby reducing the time for the device to collect and detect all points.

[0062] Furthermore, the device incorporates two additional collection points: one for collecting gas inside the device and one for collecting clean external air. If the detected gas is flammable, toxic, or hazardous, and the concentration of the gas collected within the device exceeds the limit, the device will output a dry contact signal to the control system. At regular intervals, the device connects to the external clean air collection point to automatically zero-calibrate the analyzer within the device.

[0063] In addition, the device can be equipped with an air injection port, which can be connected to an external air compressor to purge air at each collection point when not in use, preventing condensation or dust accumulation in the collection pipeline from blocking it. Furthermore, when the control system powers off the device, the two-position three-way valve behind the air injection port switches, allowing compressed air to flow through the vacuum generator, removing the hazardous gases within the device and discharging them to a safe external environment.

[0064] Specifically, in this embodiment, the gas path design in the device body is as follows: Figure 3 As shown, all sampling points are divided into two groups, A and B, numbered A1-An and B1-Bn. VAn, VBn, and VCn are two-position, three-way valves; M_dtc is a detection vacuum pump; M_pre is a sampling vacuum pump; VA_dtc, VA_pre, VB_dtc, VB_pre, VFA, and VFB are two-position, two-way valves; V_dtc and V_pre are vacuum gauges; P_dtc, P_pre, and PS are pressure gauges; FA and FB are gas-water separators; FC is a pressure reducing filter; ZAn, ZBn, and ZCn are flame arresters; and ZF1 is a vacuum generator. After the device is powered on, the PLC activates the two vacuum pumps M_dtc and M_pre, controlling VAn, VBn, VA_dtc, VA_pre, VB_dtc, and VB_pre to cycle through the collection and testing sequence A1->B1->A2->B2->…->An->Bn. A1 represents the internal sampling point, and B1 represents the external clean air sampling point. Simultaneously, VC1 is controlled to flush the injected air to the collection and testing points. When the device samples at point B1, the PLC sends a zero calibration command to the analyzer, automatically completing the zero calibration. When span calibration is required, solenoid valve VC2 is manually opened, and standard gas is introduced through the calibration port for manual span calibration. The PLC also periodically opens valves VFA and VFB to remove water from the air-water separator. The flow meter, vacuum meter and pressure gauge are used to detect the normal operation of the gas circuit. When the detection values ​​of the three are too low or too high, the device will generate an audible and visual alarm signal to indicate a system failure. When the concentration at the detection point exceeds the limit, the device will also generate an audible and visual alarm signal to indicate a safety alarm at the collection point.

[0065] The control system includes dual power supply switches, contactors, relays, buttons and indicator lights. The internal electrical layout is as follows: Figure 2As shown, it is used to cut off the power supply to the device body in case of danger and control the display and operation of the system status.

[0066] In this embodiment, the external control box casing has 5 indicator lights and 3 buttons. The indicator lights are used to display power supply 1, power supply 2, control box closing, control box opening and external opening, and the buttons are used to operate closing, opening and resetting respectively.

[0067] Specifically, when the external control box is operating in normal main and backup power supply mode, the control box outputs main power supply 1 to the device, and the power supply 1 indicator light H1 is on; when the main power supply 1 is cut off, the control box outputs backup power supply 2 to the device, and the power supply 2 indicator light H2 is on; when the backup power supply 2 is restored, the control box outputs main power supply 1 to the device, and the power supply 1 indicator light H1 is on.

[0068] When the device needs to be powered on, press the closing button SB, the closing indicator SB will light up, and the opening indicator SS will go out; when the device needs to be powered off, press the opening button SS, the closing indicator SB will go out, and the opening indicator SS will light up.

[0069] When the device collects the gas concentration at point A1 and finds that it exceeds the limit, the PLC will output a dry contact signal to the external control box (see Figure 1 Signal input). When the external control box receives the dry contact signal, coil KA1 is energized, normally open KA1 is closed, and the external control trip indicator SF lights up; normally closed KA1 is disconnected, coil KM is de-energized, normally open KM disconnect indicator SB goes out, normally closed KM closed indicator SS lights up, and the AC220V power supply to the device body is cut off.

[0070] When the power supply of the device is cut off, only after pressing the reset button SF, the coil KA1 is de-energized, the normally open KA1 is disconnected, the external control opening indicator SF goes out, the normally closed KA1 is closed, and the closing button SB is enabled. If the reset button SF is not pressed, the closing button SB will not be able to perform the closing operation. Since the device is powered off, the solenoid valve VC1 (see Figure 3 ) When positions 2 and 3 are turned on, the reduced-pressure air from the air compressor flows through the vacuum generator ZF1. The air pressure inside the device is higher than that inside the vacuum generator. The air inside the device will be injected into the vacuum generator and will flow out of the device to the safe environment area through the flame arrester ZC1 together with the reduced-pressure air. At the same time, the external clean air will flow into the device from the replacement air intake, achieving the effect of discharging dangerous gases and allowing safe gases to enter, thereby preventing explosions and poisoning incidents.

[0071] The present invention also proposes a control method for controlling the gas collection and detection device of the present invention, comprising the following steps:

[0072] The device starts and performs a self-test; wherein the self-test process includes:

[0073] After the external control box's main power supply (H1) is connected and the closing pushbutton (SB) is pressed, the PLC initiates a system self-test, checking the status of the vacuum pump (M_dtc) and sampling vacuum pump (M_pre); verifying the initial positions of each solenoid valve (VAn, VBn, VC1, etc.); and reading the initial values ​​of the flow meter, pressure gauge, and vacuum gauge to confirm that the air path is unobstructed. If the self-test passes, an audible and visual alarm will sound briefly, indicating readiness.

[0074] After the self-test is completed, the air circuit is purged, and then multi-point alternating collection and detection are carried out; the specific implementation method of the air circuit purge is that the PLC controls the solenoid valve VC1 to switch to the purge position (2-3 positions are turned on), and the air compressor is started to purge the non-working collection pipeline with compressed air for 30 seconds to remove residual water vapor or dust.

[0075] During the test, the concentration and gas path status are determined in real time. If normal, the cycle continues; if abnormal, an alarm or safety response is triggered. If the concentration exceeds the limit, the system jumps to the safety protection process, completes the replacement, and waits for reset.

[0076] Specifically, the multi-point alternating acquisition and detection process is as follows:

[0077] 1. Grouped cyclic collection:

[0078] Group A testing and Group B pre-sampling: The PLC activates the test pump (M_dtc), controlling the conduction of the solenoid valves (VA1, VA_dtc) in Group A to draw sample gas from point A1 to the analyzer for testing. Simultaneously, the sampling pump (M_pre) activates the solenoid valves (VB1, VB_pre) in Group B to draw clean air from point B1 and temporarily store it in the pre-sampling line.

[0079] Group B testing and Group A pre-sampling: After completing the A1 point test, the PLC closes VA1 and opens VB1, and M_dtc switches to testing the sample gas at B1 (triggering the analyzer zero calibration). At the same time, M_pre opens the solenoid valve at the next sampling point in Group A (such as A2) to extract the sample gas for temporary storage.

[0080] Loop logic: Loop in the order of A1→B1→A2→B2→…→An→Bn, and each group of detection is executed synchronously with the next group of pre-sampling.

[0081] 2. Real-time monitoring and alarm:

[0082] Gas line status monitoring: When the flow meter detection value falls below the set threshold (e.g., <0.5L / min), the gas line is considered blocked and an audible and visual alarm is triggered. If the pressure gauge (P_dtc, P_pre) exceeds the limit (e.g., >50kPa or <10kPa) or the vacuum level is abnormal (V_dtc, V_pre exceeds the range of -80kPa to -20kPa), the pump is considered faulty, immediately shutting down and sounding an alarm.

[0083] Concentration over-limit response: If the concentration at point A1 (inside the device) exceeds the limit (such as combustible gas ≥ 25% LEL), the PLC outputs a dry contact signal to the external control box, triggering a power outage and gas replacement process.

[0084] The gas replacement process includes:

[0085] 1. Power-off response when concentration exceeds limit:

[0086] When the concentration at point A1 exceeds the limit, the PLC outputs a dry contact signal to the external control box KA1 coil, closing the normally open contact of KA1 and lighting the external trip indicator SF. The contactor KM coil is de-energized, the main power supply (AC220V) is cut off, the closing indicator SB goes out, and the opening indicator SS lights up.

[0087] 2. Hazardous gas replacement:

[0088] Gas circuit switching: After the device is powered off, the solenoid valve VC1 automatically switches to position 2-3, and the compressed air from the air compressor enters the vacuum generator ZF1 through the pressure reducing filter FC (0.2MPa).

[0089] Negative pressure discharge: The vacuum generator generates negative pressure, and the dangerous gas inside the device is sucked in, mixed with compressed air, and then discharged to the outdoor safe area through the flame arrester ZC1.

[0090] Clean air injection: External clean air flows into the device through the replacement port (original B1 point pipeline) and continues to replace for 5 minutes to ensure that the internal concentration drops below the safety threshold.

[0091] 3. Reset and recovery:

[0092] After the maintenance personnel have located the leak, they press the reset button SF. This de-energizes the KA1 coil, turns off the external trip indicator SF, and closes the normally closed contacts. Pressing the close button SB energizes the KM coil, restores the main power supply, and restarts the initialization process.

[0093] Furthermore, calibration and maintenance tasks are performed regularly during the detection process. The automatic calibration and maintenance process is as follows:

[0094] 1. Zero point automatic calibration:

[0095] Timer trigger: Automatically collect clean air at point B1 every 8 hours (configurable), the PLC sends a zero point calibration command to the analyzer, and logs the calibration after completion.

[0096] Calibration verification: Re-measure point B1 immediately after calibration. If the deviation is greater than 2% FS (full scale), the calibration is considered a failure, an alarm is triggered, and a fault code is recorded.

[0097] 2. Manual range calibration procedure: Maintenance personnel open solenoid valve VC2 and connect a standard gas cylinder (e.g., 50% LEL methane). The PLC controls the test pump (M_dtc) to draw the standard gas into the analyzer for 3 minutes to ensure the gas path is stable. The analyzer reads the standard gas concentration and automatically adjusts the range parameters to the matching value, completing the calibration.

[0098] 3. Gas-water separator maintenance: PLC opens the drain solenoid valves VFA and VFB regularly every day (5 seconds each time) to discharge the accumulated water in the gas-water separator (FA, FB).

[0099] In addition, the power management in the control method includes dual power switching and forced opening operation.

[0100] The specific implementation of dual power switching is as follows: when the main power supply (H1) is normal, the control box uses the main power supply first; if the main power supply fails, it switches to the backup power supply (H2) within 10ms, and the power supply 2 indicator H2 lights up. After the main power supply is restored, it automatically switches back to the main power supply, and the H1 indicator lights up.

[0101] The specific implementation method of the forced opening operation is: in an emergency, press the opening button SS to immediately cut off the power supply to the device, the opening indicator SS lights up, and the gas replacement process is triggered at the same time.

[0102] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A safe gas collection and detection device, characterized in that: include: Gas collection and detection device body and control system; The gas collection and detection device body includes: The dual vacuum pump module includes a detection vacuum pump and a sampling vacuum pump, which are used to extract sample gas from the detection gas circuit and temporarily store sample gas in the pre-sampling gas circuit respectively; The grouped collection gas path module includes group A and group B collection points. Each group includes multiple collection points, and the gas path is controlled by a solenoid valve; Internal gas concentration detection module, including gas collection points inside the device and external clean air collection points, used to detect the gas concentration inside the device and trigger zero point calibration; Hazardous gas displacement module, including vacuum generator, solenoid valve and displacement port, used to discharge hazardous gas through negative pressure and inject clean air when the concentration exceeds the limit; Gas circuit status monitoring module, including flow sensor, pressure sensor and vacuum gauge, used to detect gas circuit status in real time; The control system includes: Dual power switching module for automatic switching between primary and backup power supplies; The safety response module cuts off the power supply to the device and starts the gas replacement process after receiving the concentration limit signal through the PLC; The automatic calibration module regularly collects external clean air to trigger the zero point calibration of the gas analyzer and supports manual range calibration.

2. The gas collection and detection device according to claim 1, characterized in that: In the grouped collection gas path module, Group A and Group B perform detection and pre-sampling operations alternately in sequence, specifically: When the detection vacuum pump starts the collection point of group A, the sampling vacuum pump will start the next collection point of group B simultaneously for pre-sampling; After the detection is completed, switch to group B detection, and at the same time pre-sampling is performed at the next collection point of group A, and the order of A1→B1→A2→B2→…→An→Bn is executed cyclically.

3. The gas collection and detection device according to claim 2, characterized in that: The hazardous gas replacement module also includes an air injection port, which is connected to an air compressor and switched to the purge position through a solenoid valve. The compressed air generates negative pressure through a vacuum generator, and the hazardous gas in the device is discharged to a safe area; the replacement port injects external clean air through the B1 point pipeline and continuously replaces until the internal concentration is lower than the safety threshold.

4. The gas collection and detection device according to claim 2 or 3, characterized in that: The automatic calibration module includes: The timing trigger unit collects clean air at point B1 at every preset time and sends a zero point calibration instruction to the gas analyzer; Calibration verification unit: re-measure point B1 after calibration. If the deviation exceeds 2% of the full scale, an alarm is triggered; Manual range calibration interface, connect the standard gas cylinder through the solenoid valve for range calibration.

5. The gas collection and detection device according to claim 4, characterized in that: The alarm conditions of the gas path status monitoring module include: When the flow sensor detection value is lower than 0.5L / min, the air path is determined to be blocked; When the pressure sensor detection value exceeds 50kPa or is lower than 10kPa, the pump is judged to be faulty; When the vacuum gauge detection value exceeds the range of -80kPa to -20kPa, a shutdown alarm is triggered.

6. The gas collection and detection device according to any one of claims 1 to 3, characterized in that: The control system also includes: a gas-water separator maintenance module, which uses the PLC to regularly open the drainage solenoid valve to drain the stored water; and a forced opening button, which cuts off the power supply and triggers the gas replacement process in an emergency.

7. A method for controlling the gas collection and detection device according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1: Device startup and self-test: The control system switches to the main power supply, and the PLC initializes and detects the vacuum pump and samples the vacuum pump status; Check the initial position of the solenoid valve, read the flow, pressure and vacuum data, and enter the purge process after confirming that the air path is unobstructed; Step S2, alternating collection and detection: Control the A group detection gas circuit and the B group pre-sampling gas circuit to run synchronously, and switch to the B group detection and A group pre-sampling after the detection is completed; The cycle continues until all collection points are tested. If the gas concentration in the device is detected to be above the limit, the PLC outputs a dry contact signal to the control system, cuts off the power supply, and activates the vacuum generator to exhaust the dangerous gas. Clean air is injected through the displacement port and continues to be replaced until the concentration is below the safety threshold. Regularly collect external clean air to trigger zero-point calibration and verify the calibration results; regularly open the drain solenoid valve every day to drain the water accumulated in the air-water separator.

8. The control method according to claim 7, characterized in that: The specific process of alternating collection and detection in step S2 includes: The detection pump extracts the sample gas of the current collection point of group A to the analyzer, and at the same time the sampling pump extracts the sample gas of the next collection point of group B for temporary storage; After completing the detection of group A, switch to the detection of group B and trigger the zero point calibration. At the same time, the sampling pump extracts the sample gas from the next collection point of group A; Execute in a loop according to the grouping order to shorten the overall detection cycle.

9. The control method according to claim 7 or 8, characterized in that: The gas replacement process in step S3 further includes: After the device is powered off, the solenoid valve switches to the purge position, and the compressed air enters the vacuum generator through the pressure reducing filter; the dangerous gas in the negative pressure extraction device is mixed with the compressed air and discharged to the safe area through the flame arrester; After the replacement lasts for a set time, the maintenance personnel reset the system and re-apply power.

10. The control method according to claim 7 or 8, characterized in that: The manual range calibration in step S4 includes: Open the solenoid valve to connect the standard gas cylinder, and use the test pump to extract the standard gas to the analyzer; The analyzer reads the concentration and adjusts the range parameters. After calibration, the solenoid valve is closed.

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