Hydrogen tail gas emission safety detection system

Abstract

The invention relates to a hydrogen tail gas emission safety detection system, which is characterized in that a gas monitoring system, a nitrogen dilution system, an alarm system and a safety emergency interlocking system are additionally arranged on the basis of the structure of a CVD (chemical vapor deposition) or ICP (inductively coupled plasma) hydrogen tail gas emission system in the prior art, the safety of exhausted gas is monitored, and corresponding protection measures are set. The device has the advantages that the structural design is reasonable, the hydrogen and oxygen concentration detectors are arranged on the tail gas emission pipeline of the CVD or ICP hydrogen tail gas emission system and interlocked with the nitrogen pipeline, the condition of gas in the pipeline can be better monitored, when the hydrogen or oxygen concentration exceeds the standard, an alarm can be automatically given at first, the emission air volume can be manually increased according to needs, and the emission efficiency is improved. Early warning is realized, and dangerous sources are eliminated; when the secondary standard exceeds the standard, a dilution means can be automatically adopted in time, nitrogen purging is started, and the hydrogen concentration is reduced. Explosion and fire accidents can be effectively prevented, property loss is avoided in time, safety protection is provided, and the safety facility design can be effectively met.

Description

A hydrogen exhaust emission safety detection system Technical Field

[0001] This invention relates to a hydrogen exhaust emission safety detection system, specifically a safety detection system for hydrogen exhaust emission systems used in CVD or ICP. Background Technology

[0002] Hazardous waste gases generated in industries such as semiconductors, microelectronics, LEDs, university laboratories, research institutions, and solar photovoltaics, especially the exhaust gases generated by deposition or etching equipment such as CVD (chemical vapor deposition) and ICP (inductively coupled plasma etching) systems, generally contain toxic, harmful, flammable, and explosive media, and the emissions are large. They are usually treated by professional scrubber equipment (exhaust gas treatment equipment) before being directly discharged.

[0003] In existing technologies, emissions after scrubber treatment are generally not controlled and generally include the following forms: (1) Combustion and water washing type: This is a tail gas treatment technology based on combustion and water washing. CVD tail gas is treated by combustion and water washing through a combustion scrubber device and then discharged directly.

[0004] (2) Ion electrolysis: This is a tail gas treatment technology based on the principle of high-temperature ion combustion. CVD tail gas is treated by high-temperature ion combustion in an ion electrolysis scrubber device and then discharged directly.

[0005] The above two types of equipment have high investment costs, require uninterrupted daily processing, and consume a lot of energy. Although direct discharge is possible, the high cost and energy consumption make them uneconomical and hinder their implementation.

[0006] (3) Water washing type: This is a tail gas treatment technology based on water washing and solvent dissolution. CVD tail gas is treated by water washing and dilution through water washing scrubber equipment. The media with environmental pollution is treated by water washing and then discharged directly.

[0007] The above methods generate large amounts of wastewater, increasing the wastewater treatment load. Secondary treatment and discharge are neither environmentally friendly nor economical. Furthermore, hydrogen cannot be absorbed and is ultimately released directly into the atmosphere, posing a risk of combustion and explosion. Without control, this method presents significant safety risks.

[0008] (4) Adsorption type: This is a tail gas treatment technology based on the principles of adsorption and chemical reaction. CVD tail gas is treated by adsorption using an organic adsorption scrubber device to adsorb and treat the media with environmental pollution, and then discharged directly after treatment.

[0009] In the above methods, hydrogen is ultimately released directly into the atmosphere. Hydrogen is a flammable and explosive gas, and direct release poses a risk of combustion and explosion. Without control, this method presents significant safety risks.

[0010] In summary, because existing technologies generally employ water washing or adsorption treatment methods, there are significant environmental and safety risks. After passing through exhaust gas treatment equipment, the exhaust gases from CVD, ICP, and other equipment are directly emitted (as shown in Figure 1), without monitoring or emergency measures for hydrogen concentration, flow rate, and safety. Generally, only detectors for pollutants are installed at the final emission point to transmit data to relevant departments according to environmental requirements, but hydrogen is not strictly controlled, posing a fire hazard. In the event of an accident, it would cause significant economic losses and fails to meet safety facility design requirements. Summary of the Invention

[0011] This invention proposes a hydrogen exhaust gas emission safety detection system, which aims to overcome the above-mentioned shortcomings of the existing technology and effectively improve the safety of gas emissions from equipment such as CVD and ICP after treatment by exhaust gas treatment equipment.

[0012] The technical solution of this invention is a hydrogen exhaust gas safety detection system. Based on the existing CVD or ICP hydrogen exhaust gas emission system, it adds a gas monitoring system, a nitrogen dilution system, an alarm system, and a safety emergency interlock system to monitor the safety of the emitted gases and implement corresponding protective measures. This effectively ensures safety, protects production, and prevents losses.

[0013] Specifically, its structure includes several exhaust gas treatment devices. The exhaust pipes of all exhaust gas treatment devices are connected to the main exhaust pipe, which is connected to an explosion-proof exhaust fan located on the roof. The explosion-proof exhaust fan is connected to the exhaust pipe, and an online hydrogen detection alarm is installed on the exhaust pipe. The signal of the online hydrogen detection alarm is connected to the PLC control cabinet. The nitrogen purging system is connected to the exhaust pipes of each exhaust gas treatment device, and the signal of the nitrogen purging system is connected to the PLC control cabinet.

[0014] Preferably, an online oxygen detector and alarm is installed on the main exhaust pipe, and the signal of the online oxygen detector and alarm is connected to the PLC control cabinet.

[0015] Preferably, the PLC control cabinet is also connected to an explosion-proof exhaust fan for signal control, enabling interlocking control of the fan.

[0016] Preferably, the PLC control cabinet is also connected to a hydrogen flow remote display, which is connected to each exhaust gas treatment device to achieve pressure feedback monitoring.

[0017] Preferably, the online hydrogen detection alarm consists of a gas detection alarm transmitter and a fixed hydrogen detector. The gas detection alarm transmitter is connected to the PLC control cabinet, and the fixed hydrogen detector is installed on the exhaust pipe. The fixed hydrogen detector converts the hydrogen concentration detected by the sensor into an electrical signal. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter issues an alarm signal and starts the nitrogen purging system.

[0018] Preferably, the online oxygen detection alarm consists of a gas detection alarm transmitter and a fixed oxygen detector. The gas detection alarm transmitter is connected to the PLC control cabinet, and the fixed oxygen detector is installed on the main exhaust pipe at the front end of the explosion-proof exhaust fan. The fixed oxygen detector converts the oxygen concentration detected by the sensor into an electrical signal. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter issues an alarm signal.

[0019] Preferably, the nitrogen purging system includes a nitrogen source, a nitrogen pipeline connecting the nitrogen source to the outlet pipes of each exhaust gas treatment device, and a pneumatic valve, a check valve, and a pressure gauge installed on the nitrogen pipeline. The pneumatic valve signal is connected to the PLC control cabinet.

[0020] The advantages of this invention are: A reasonable structural design; hydrogen and oxygen concentration detectors are installed on the exhaust pipe of the CVD or ICP hydrogen exhaust system and interlocked with the nitrogen pipeline, allowing for better monitoring of the gas conditions within the pipeline. When hydrogen or oxygen concentrations exceed the standard, an automatic alarm is triggered first, and the exhaust air volume can be manually increased as needed to achieve early warning and eliminate potential hazards. When secondary exceedances occur, dilution measures can be automatically implemented in a timely manner, initiating nitrogen purging to reduce the hydrogen concentration. This effectively prevents explosions and fires, promptly avoids property damage, provides safety protection, and effectively meets the design requirements of safety facilities. Attached Figure Description

[0021] Figure 1 is a schematic diagram of an embodiment of a prior art CVD or ICP hydrogen exhaust system.

[0022] Figure 2 is a schematic diagram of the hydrogen exhaust emission safety detection system of the present invention.

[0023] In the diagram, 1 is the exhaust gas treatment equipment (scrubber equipment), 2 is the explosion-proof exhaust fan, 3 is the roof, 4 is the exhaust port, 5 is the online hydrogen detector and alarm, 6 is the PLC control cabinet, 7 is the online oxygen detector and alarm, 8 is the nitrogen purging system, and 9 is the hydrogen flow remote display. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to embodiments and specific implementation methods.

[0025] As shown in Figure 2, a hydrogen exhaust gas emission safety detection system comprises several exhaust gas treatment devices 1. The outlet pipes of all exhaust gas treatment devices 1 are connected to a main outlet pipe, which is connected to an explosion-proof exhaust fan 2 (one for use and one for standby) located on the roof 3. The explosion-proof exhaust fan 2 is connected to an exhaust pipe, and the exhaust port 4 of the exhaust pipe is preferably ≥3m away from the roof 3. An online hydrogen detection alarm 5 is installed on the exhaust pipe, and the signal of the online hydrogen detection alarm 5 is connected to a PLC control cabinet 6. An online oxygen detection alarm 7 is installed on the main outlet pipe, and the signal of the online oxygen detection alarm 7 is connected to the PLC control cabinet 6. A nitrogen purging system 8 is connected to the outlet pipes of each of the two exhaust gas treatment devices 1, and the signal of the nitrogen purging system 8 is connected to the PLC control cabinet 6.

[0026] In a preferred embodiment, the PLC control cabinet 6 is also connected to the explosion-proof exhaust fan 2 and the hydrogen flow remote display 9, which is connected to each exhaust gas treatment device 1. This enables pressure feedback monitoring and fan interlock control.

[0027] During operation, PID control is implemented. The online hydrogen detector 5 is interlocked with the nitrogen purging system 8 via the PLC control cabinet 6. When the online hydrogen detector 5 detects that the hydrogen concentration at the exhaust pipe is greater than 1% (25% of the lower explosive limit of hydrogen), the nitrogen purging system 8 is activated to purge the exhaust pipes of each exhaust gas treatment device 1 with nitrogen, achieving a dilution and protection function. At the same time, an online oxygen detector 7 is installed at the front end (main exhaust pipe) of the explosion-proof exhaust fan 2 to ensure an oxygen-free environment in the pipeline.

[0028] The online hydrogen detector alarm 5 consists of a gas detection alarm transmitter and a fixed hydrogen detector. The gas detection alarm transmitter is connected to the central control center of the plant through the PLC control cabinet 6 to monitor and control each monitoring point. The fixed hydrogen detector is installed at the end of the exhaust gas emission (exhaust pipe), and its core component is a gas sensor.

[0029] The fixed hydrogen detector converts the hydrogen concentration detected by the sensor into an electrical signal, which is transmitted to the central control center of the plant via cable through a gas detection alarm transmitter. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter will issue an alarm signal and can activate external equipment to automatically eliminate potential hazards.

[0030] As one embodiment, the fixed hydrogen detector adopts the following specifications: Detected gas: hydrogen; Sensor: electrochemical / catalytic combustion; Detection range: 0-100% LEL for combustible gases; Resolution: 1% LEL; Alarm points: two-level alarm points (high alarm and high-high alarm); Detection method: natural diffusion type, pipeline type; Detection accuracy: ±3%FS; Explosion-proof rating: Exd II CT3; Protection rating: IP65; Response time: ≤10s; Temperature range: -20℃-50℃; Humidity range: ≤95%; Alarm method: three-level alarm (audible, visual, and vibration); Alarm volume: ≥75dB.

[0031] As one example, the gas detection alarm transmitter adopts the following specifications: multiple standard signal outputs for easy access to industrial control systems such as controllers / PLCs / DSCs; built-in factory reset button to avoid accidental operation; explosion-proof certification level Exd II CT3 or higher, protection level: IP54 or higher.

[0032] The online oxygen detector alarm 7 consists of a gas detection alarm transmitter and a fixed oxygen detector. The gas detection alarm transmitter is connected to the central control center of the plant through the PLC control cabinet 6 to monitor and control each monitoring point. The fixed oxygen detector is installed at the front end (main outlet pipe) of the exhaust fan (explosion-proof exhaust fan 2), and its core component is a gas sensor.

[0033] The fixed oxygen detector converts the oxygen concentration detected by the sensor into an electrical signal, which is transmitted to the central control center of the plant via cable through a gas detection alarm transmitter. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter will issue an alarm signal and can activate external equipment to automatically eliminate potential hazards.

[0034] As one embodiment, the fixed oxygen detector adopts the following specifications: Detected gas: oxygen; Sensor: electrochemical, with optional optical fluorescence or zirconium oxide; Detection range: 0~30% VOL for combustibles; Resolution: 0.1% VOL; Alarm points: two-level alarm points (high alarm and high-high alarm); Detection method: natural diffusion type, pipeline type; Detection accuracy: ±1%FS; Explosion-proof rating: Exd IICT3; Protection rating: IP65; Response time: ≤10s; Temperature range: -20℃-50℃; Humidity range: ≤95%; Alarm method: three-level alarm (audible, visual, and vibration); Alarm volume: ≥75dB. As another embodiment, the gas detection alarm transmitter adopts the following specifications: multiple standard signal outputs for easy integration into industrial control systems such as controllers / PLCs / DSCs; built-in factory reset button to avoid human error; meets explosion-proof certification level Exd II CT3 or higher, and protection rating: IP54 or higher.

[0035] The nitrogen purging system 8 includes a nitrogen source, a nitrogen pipeline connecting the nitrogen source to the outlet pipes of each exhaust gas treatment device 1, and pneumatic valves, check valves, and pressure gauges installed on the nitrogen pipelines. The pneumatic valve signal is connected to the PLC control cabinet 6.

[0036] The above structure has been implemented in multiple projects. During project implementation, environmental impact assessments and safety assessments required the addition of CVD exhaust gas emission safety facilities. CVD exhaust gas emissions were collected, and oxygen content monitoring, hydrogen content monitoring, and nitrogen protection were implemented. The emission volume was increased, and online alarms were set up. This solution met the requirements of the environmental impact assessments and safety assessments.

[0037] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A hydrogen exhaust gas emission safety detection system, comprising a plurality of exhaust gas treatment devices (1), wherein the outlet pipes of all exhaust gas treatment devices (1) are connected to a main outlet pipe, the main outlet pipe is connected to an explosion-proof exhaust fan (2) located on the roof (3), and the explosion-proof exhaust fan (2) is connected to an exhaust pipe, characterized in that, An online hydrogen detector (5) is installed on the exhaust pipe, and the signal of the online hydrogen detector (5) is connected to the PLC control cabinet (6); the nitrogen purging system (8) is connected to the exhaust pipe of each (2) tail gas treatment device (1), and the signal of the nitrogen purging system (8) is connected to the PLC control cabinet (6).

2. The hydrogen exhaust emission safety detection system as described in claim 1, characterized in that, An online oxygen detector (7) is installed on the main exhaust pipe, and the signal of the online oxygen detector (7) is connected to the PLC control cabinet (6).

3. The hydrogen exhaust emission safety detection system as described in claim 1, characterized in that, The PLC control cabinet (6) is also connected to the explosion-proof exhaust fan (2).

4. The hydrogen exhaust gas emission safety detection system as described in claim 1, characterized in that, The PLC control cabinet (6) is also connected to the hydrogen flow remote display (9), which is connected to each exhaust gas treatment device (1).

5. The hydrogen exhaust emission safety detection system as described in claim 1, characterized in that, The online hydrogen detection alarm (5) consists of a gas detection alarm transmitter and a fixed hydrogen detector. The gas detection alarm transmitter is connected to the PLC control cabinet (6). The fixed hydrogen detector is installed on the exhaust pipe. The fixed hydrogen detector converts the hydrogen concentration detected by the sensor into an electrical signal. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter issues an alarm signal and starts the nitrogen purging system (8).

6. The hydrogen exhaust emission safety detection system as described in claim 2, characterized in that, The online oxygen detector alarm (7) consists of a gas detection alarm transmitter and a fixed oxygen detector. The gas detection alarm transmitter is connected to the PLC control cabinet (6). The fixed oxygen detector is installed on the main exhaust pipe at the front end of the explosion-proof exhaust fan (2). The fixed oxygen detector converts the oxygen concentration detected by the sensor into an electrical signal. The higher the gas concentration, the stronger the electrical signal. When the gas concentration reaches or exceeds the alarm point set by the gas detection alarm transmitter, the gas detection alarm transmitter issues an alarm signal.

7. The hydrogen exhaust emission safety detection system as described in claim 1, characterized in that, The nitrogen purging system (8) includes a nitrogen source, a nitrogen pipeline connecting the nitrogen source to the outlet pipe of each tail gas treatment device (1), and a pneumatic valve, a check valve and a pressure gauge installed on the nitrogen pipeline. The pneumatic valve signal is connected to the PLC control cabinet (6).

Images