Electronic grade hydrogen tail gas safe discharge system

Abstract

The application discloses an electronic-grade hydrogen tail gas safe discharge system, which comprises an exhaust machine table, a main flame arrester and a discharge vertical pipe. The exhaust machine table is connected to the discharge vertical pipe through a hydrogen conveying pipeline and the main flame arrester. A microporous flame arrester dispersion head is arranged at the top of the discharge vertical pipe. The microporous flame arrester dispersion head is made of a stainless steel powder metallurgy sintering material and forms a three-dimensional communicating pore structure with the functions of exhaust and flame arrester. The top of the microporous flame arrester dispersion head is in a blind plate sealing structure. The main flame arrester adopts a corrugated belt type or a metal powder metallurgy sintering plate structure. Compared with the prior art, the discharge system of the application has the advantages of low energy consumption, small back pressure and more comprehensive protection.

Description

Technical Field

[0001] This invention relates to the field of electronic-grade hydrogen emission technology, and more particularly to an electronic-grade hydrogen exhaust safety emission system. Background Technology

[0002] Electronic-grade hydrogen is an indispensable raw material gas in processes such as semiconductor manufacturing and optoelectronic production. During production and use, the process system generates exhaust gases containing hydrogen, which need to be safely released into the atmosphere.

[0003] Hydrogen, as a flammable and explosive gas, possesses significant hazardous characteristics, including extremely low ignition energy (only 0.02 mJ), a wide explosive limit range (4.0%-74.2%), and rapid flame propagation. During high-speed emission, the high-speed friction between hydrogen and the pipe wall easily generates static electricity. If impurities such as welding slag and rust are present in the pipeline, electrostatic discharge may occur. Furthermore, if the emission outlet is struck by lightning or ignited by an external open flame (such as nearby hot work or fireworks), the flame can rapidly spread back along the emission pipe to the internal pipelines of the plant, thereby endangering the safety of the entire process system.

[0004] In existing technologies, flame arresters are typically installed on exhaust pipelines as passive protection devices. However, the explosion-proof performance of flame arresters depends on the integrity and cleanliness of their internal corrugated plate or metal mesh structure. Once a flame arrester fails due to blockage, corrosion, or mechanical damage, or if the flame bypasses it (e.g., high-speed flame penetration or reduced flame-arresting ability after multiple detonation impacts), it will lose its protective function and cannot fundamentally eliminate the risk of backfire. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides an electronic-grade hydrogen exhaust safety emission system with dual physical flame arrestor barriers. Even if the main flame arrestor fails or the flame bypasses the barrier, the quenching effect of the microporous layer ensures that the flame cannot propagate back.

[0006] An electronic-grade hydrogen exhaust safety emission system includes an exhaust fan, a main flame arrester, and an emission riser. The exhaust fan is connected to the emission riser via a hydrogen delivery pipeline and the main flame arrester. The top of the emission riser is equipped with a microporous flame arrestor dispersion head. The microporous flame arrestor dispersion head is made of stainless steel powder metallurgy sintered material and forms a three-dimensional interconnected pore structure with exhaust and flame arrestor functions. The top of the microporous flame arrestor dispersion head has a blind plate sealing structure. The main flame arrester adopts a corrugated belt type or a metal powder metallurgy sintered plate structure.

[0007] The diameter of the pores is controlled between 0.3 and 0.8 mm, and the porosity is controlled between 30% and 50%.

[0008] The microporous flame-arresting and dispersing head is a cylindrical or conical shape with a sealed top, and is fitted or welded to the top of the discharge riser. A conical rainproof cap is also provided above the microporous flame-arresting and dispersing head, and is supported and connected by stiffening plates.

[0009] The outer diameter of the microporous flame-arresting dispersion head is larger than the outer diameter of the discharge riser, and there is an annular chamfered slope at the connection between the bottom of the microporous flame-arresting dispersion head and the discharge riser for guiding the flow; the bottom end of the discharge riser is provided with a water collection tank and a manual drain valve.

[0010] It also includes a micro-thermal nitrogen purging unit, which includes a nitrogen source, a nitrogen injection ring located at the bottom of the discharge riser, and a heating control box. The nitrogen source is connected to the nitrogen injection ring through a nitrogen supply pipe. The nitrogen injection ring has a ring-shaped structure adapted to the horizontal cross-section of the discharge riser. Multiple purging microholes are evenly distributed on the upper surface of the nitrogen injection ring. An electric heating structure is arranged along the nitrogen supply pipe and the heating is controlled by the heating control box.

[0011] The electric heat tracing structure includes a heat tracing tape attached to the outer surface of the nitrogen supply pipeline, and insulation wrapping tape, insulation cotton, and outdoor waterproof aluminum sheath wrapped from the inside out.

[0012] A control pipeline is also connected between the nitrogen source and the nitrogen supply pipeline. The control pipeline includes two lines: one is a normally open pipeline equipped with a float flow controller to maintain a slight positive pressure in the discharge riser; the other is a bypass pipeline that can be linked with the exhaust fan, equipped with a flow regulating valve and a flow meter. When hydrogen emission from the exhaust fan is detected, the bypass pipeline is automatically opened, the nitrogen flow is increased through the flow regulating valve, and monitored by the flow meter. If the opening flow does not meet the set value, the exhaust fan is shut down.

[0013] It also includes a buffer tank with a cyclone separation structure, located on the hydrogen delivery pipeline between the main flame arrester and the exhaust machine, and the bottom of the buffer tank is equipped with a drain valve.

[0014] It also includes a static-conducting grounding busbar, used to form an equipotential connection with each hydrogen-passing component of the emission system and the ground.

[0015] The electronic-grade hydrogen exhaust safety emission system of the present invention has the following advantages compared with the prior art: 1. High inherent safety: It adopts a dual physical fire barrier of "main flame arrester + end microporous flame arrestor dispersion head". Even if the main flame arrester fails or the flame bypasses, the quenching effect of the microporous layer can ensure that the flame cannot be transmitted back.

[0016] 2. Extremely low back pressure, which does not affect the operation of front-end equipment: The discharge riser, which serves as the main discharge channel, is a straight-through large-diameter pipe. The microporous flame-retardant dispersion head adopts a thin-walled design with high porosity and extremely low airflow resistance. Even at the maximum discharge flow rate, the back pressure increment is far below the allowable limit of the equipment.

[0017] 3. Maintaining positive pressure within the pipe through a small amount of nitrogen purging via a normally open pipeline completely eliminates the possibility of air backflow forming an explosive mixture. Energy consumption is extremely low, and operating costs are controllable: only a very small continuous flow of nitrogen purging is required (to maintain positive pressure), reducing nitrogen consumption by 80%-90% compared to traditional continuous high-flow nitrogen sealing solutions.

[0018] 4. Thoroughly prevents water accumulation: The discharge riser combines a "conical rain cap", a "root guide slope" and a "bottom drain valve" for triple protection. Rainwater, condensate, and backflow water can all be effectively discharged, eliminating freezing, blockage, and corrosion problems caused by water accumulation.

[0019] 5. Excellent diffusion effect: The microporous flame-retardant dispersion head breaks hydrogen into fine jets, which are discharged radially from the 360° micropores on the side wall. The specific surface area increases dramatically, and after discharge, it can be instantly mixed and diluted with air, fundamentally preventing local accumulation.

[0020] 6. Reliable structure and easy maintenance: There are no complex moving parts, the stainless steel sintered material is corrosion resistant and has a long service life, the micro-purging system has a high degree of automation, and the daily maintenance workload is minimal. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the electronic-grade hydrogen exhaust gas safety emission system of the present invention; Figure 2 This is an enlarged schematic diagram of the structure of the microporous flame-retardant dispersion head of the present invention; Figure 3 This is a three-dimensional schematic diagram of the microporous flame-retardant dispersion head of the present invention; Figure 4 This is a schematic diagram of the structure of the microporous flame-retardant dispersion head of the present invention; Figure 5 This is a top enlarged schematic diagram of the nitrogen injection ring of the present invention; Figure 6 This is a schematic diagram of the radial cross-section of the electric heat tracing structure of the present invention. Detailed Implementation

[0022] The present invention will now be further described in the form of an electronic-grade hydrogen exhaust gas safety emission system.

[0023] like Figure 1As shown, the electronic-grade hydrogen exhaust safety emission system of the present invention includes an exhaust unit 1, a main flame arrester 5, and a large-diameter (DN25-DN50) emission riser 6. The exhaust unit 1 is connected to the emission riser 6 via a hydrogen delivery pipeline 18 and the main flame arrester 5. The main flame arrester 5 adopts a corrugated belt or metal powder metallurgy sintered plate structure, which has sufficient flame arresting velocity to suppress the propagation of hydrogen deflagration flame, and can serve as the first line of fire prevention.

[0024] Combination Figures 2-4 As shown, the top of the discharge riser 6 is equipped with a microporous flame-arresting and dispersing head 14. The microporous flame-arresting and dispersing head 14 is made of stainless steel powder metallurgy sintered material and forms a three-dimensional interconnected pore structure 21 with both exhaust and flame-arresting functions. Pore 21 parameters: The diameter of the pore 21 is controlled at 0.3-0.8 mm (smaller than the flame quenching diameter of hydrogen, ensuring the flame cannot pass through), and the porosity is controlled at 30%-50% (ensuring low exhaust resistance). The dispersing head 14 is designed as a thin-walled (1.5-4 mm thick) cylindrical or conical shape, fitted or welded to the top of the discharge riser 6. The top of the dispersing head 14 has a blind-plate sealed structure. After hydrogen enters from the riser 6, because the top is sealed, it cannot be directly discharged upwards. Instead, it passes through the interconnected pores 21 on the side wall of the dispersing head 14 and is radially discharged into the atmosphere from the 360° micropores on the side wall. Above it is a conical rain cap 15, which is supported and connected to the outer wall of the dispersing head 14 by a rib plate, together forming an annular exhaust slit 16. This slit 16 is the gap between the dispersing head 14 and the rain cap 15. The reason for leaving this slit 16 is that hydrogen molecules are relatively light, and this slit 16 can facilitate air convection (see...). Figure 2 (Dashed arrow in the middle) This prevents hydrogen from accumulating under the rain cap 15. The dispersion head 14 itself serves as both an exhaust channel and a terminal flame arrestor. During normal discharge, hydrogen is divided into countless micro-jet streams through the micropores, resulting in a sharp increase in surface area. After discharge, it can instantly mix and dilute with air. In case of abnormal flashback, the flame front touches the micropore layer and is quenched by heat absorption by the pore walls, preventing it from penetrating into the riser 6. The conical rain cap 15, made of stainless steel, covers the dispersion head 14 and is used to block vertical rainfall. The outer diameter of the microporous flame arrestor dispersion head 14 is larger than that of the discharge pipe 6. At the connection between the bottom of the microporous flame arrestor dispersion head 14 and the discharge riser 6, there is a 45° annular chamfered slope to form a root guide slope 22, which guides the small amount of water flowing down the pipe wall to drip outwards (see...). Figure 2 (See arrow in the middle) to prevent it from entering through the pores 21 at the root of the microporous flame arrestor dispersion head 14 (see...) Figure 2 (Indicated by the dashed arrow), and then into the lower part of riser 6. A conical water collection trough and a manual drain valve 17 are installed at the lowest point of the bottom of riser 6 to regularly drain any condensate that may accumulate (usually once a quarter or adjusted according to the local climate).

[0025] The emission system also includes a trace amount of hot nitrogen purging unit, comprising a nitrogen source 30, a nitrogen injection ring 7 horizontally located at the bottom of the emission riser 6 (near the ground for easy maintenance), and a heating control box 13. The nitrogen source 30 is connected to the nitrogen injection ring 7 via a nitrogen supply pipe 19. Please refer to... Figure 5 As shown, the injection ring has a hollow ring structure adapted to the horizontal cross-section of the discharge riser 6, with multiple purge microholes 71 evenly distributed on its upper surface to ensure uniform distribution of nitrogen gas across the cross-section of the riser 6. An electric heating structure 20 is arranged along the nitrogen supply pipe 19, and the heating is controlled by the heating control box 13 to preheat the nitrogen gas to 30-60℃ (adjustable according to the ambient temperature) to enhance the buoyancy of the mixed gas and promote diffusion at the discharge port.

[0026] Please combine Figure 6 As shown, the electric heat tracing structure 20 includes a heat tracing tape 23 attached to the outer surface of the nitrogen supply pipe 19, and an insulation wrapping tape 24, insulation cotton 25, and an outdoor waterproof aluminum sheath 26 wrapped from the inside out.

[0027] A control pipeline 8 is also connected between the nitrogen source 30 and the nitrogen supply pipeline 19. This pipeline includes two lines: one is a normally open pipeline equipped with a pressure reducing valve 9 and a float flow controller 12, set to a continuously low flow rate to maintain a slight positive pressure (typically 50-100 Pa higher than atmospheric pressure) in the discharge riser 6, preventing outside air from flowing back into the riser 6. The other line is a bypass pipeline that can be linked with the exhaust fan 1. It is equipped with a flow regulating valve 10 and a flow meter 11. When hydrogen emission from the exhaust fan 1 is detected, the bypass pipeline automatically opens, increasing the nitrogen flow rate through the flow regulating valve 10. The flow meter 11 monitors the nitrogen flow rate. If the opening flow rate does not meet the set value, the exhaust fan 1 is shut down, creating an interlock.

[0028] The exhaust system may also include a hydrogen pretreatment unit, comprising a buffer tank 2 with a cyclone separator structure located on the hydrogen delivery pipeline 18, used to separate any trace droplets or solid particles that may be entrained during the process, preventing impurities from generating an ignition source due to friction with the high-speed airflow. A drain valve 3 is located at the bottom of the buffer tank 2. The buffer tank 2 is designed with a volume of less than 25L and an operating pressure of less than 1.0MPa. This unit can be omitted if the hydrogen is confirmed to be clean.

[0029] The exhaust system also includes a static grounding busbar 4, which is used to form an equipotential connection with each hydrogen-carrying component of the exhaust system (such as hydrogen delivery pipe 18, buffer tank 2, exhaust riser 6, etc.) and the ground to prevent static electricity accumulation.

[0030] The working principle of the emission system of the present invention is as follows: Normal operating conditions (no emissions / minor leaks): When a small amount of hot nitrogen (30-60℃) is continuously injected from the bottom, it forms an upward micro-positive pressure airflow in the riser 6, preventing backflow of outside air. At the same time, the hot nitrogen rises along the pipe wall, providing heat tracing and antifreeze for the pipeline, and is discharged from the top microporous flame arrestor 14.

[0031] Emission Condition (Process Venting): When a large amount of hydrogen enters the exhaust riser 6, it mixes with continuously injected hot nitrogen. The mixed gas (hydrogen + nitrogen) is broken into fine jets as it passes through the microporous flame-retardant diffuser 14, radially diffusing from the 360° micropores on the side wall. It is rapidly diluted by air and ejected at high speed. The overall exhaust airflow channel is unobstructed (including the hydrogen delivery pipe 18, riser 6, and pores 21), resulting in extremely low back pressure. An annular exhaust gap is formed between the diffuser 14 and the rain cap 15, facilitating air convection and preventing hydrogen accumulation.

[0032] Abnormal operating condition (emission port ignited): When the flame attempts to propagate back through the dispersion head 14, because the diameter of the pore 21 is smaller than the quenching diameter of the hydrogen flame, the flame is quenched by heat absorption by the wall in the microporous channel and cannot propagate into the pipeline, thus achieving intrinsic safety.

[0033] Drainage process: When rainwater is blocked by the rain cap 15, a small amount of water flowing down the wall is guided to drip outward through the root guide slope to prevent it from entering the pipe; the bottom condensate can be discharged periodically through the drain valve to ensure that there is no water accumulation in the system.

[0034] Example For example, in a hydrogen purifier vent modification project at a semiconductor factory, the maximum exhaust gas emission from the purifier was 8 Nm³. 3 / h, normal discharge pressure 0.2MPa, maximum allowable back pressure of the equipment 0.05MPa. The system of this invention is used for discharge.

[0035] Installation parameters: Discharge riser 6: DN40 (φ48×3.5) 316L stainless steel pipe, 6 meters high (2 meters above the factory roof).

[0036] Buffer tank 2: 20L capacity, design pressure 1.0MPa, working pressure 0.2MPa, equipped with cyclone separator internals. (Optional) Microporous flame-retardant dispersion head 14: Made of 316L stainless steel powder sintered material, it is cylindrical with a wall thickness of 2.5mm and an outer diameter of 65mm, and is fitted onto the top of the riser 6. The diameter of the pores 21 is controlled to be 0.5mm (±0.1mm), and the porosity is 45%. A 45° annular chamfer is machined at the connection between the dispersion head 14 and the riser 6.

[0037] Nitrogen purging: The continuous purging flow rate is set to 3L / min (at normal temperature and pressure volume), and automatically interlocked to increase to 15L / min (at normal temperature and pressure volume) during discharge. The nitrogen is heated to 40℃ via heating control box 13. The pipeline heat tracing uses self-regulating electric heating tape 23, with a power of 30W, which is wrapped around the nitrogen pipeline before the injection ring and is insulated and waterproofed.

[0038] Drainage structure: A water collection trough is installed at the lowest point of riser 6, and a manual drain ball valve is installed. It is recommended to drain the water once per quarter (adjust according to local climate).

[0039] Performance test results and recommendations: Regulatory compliance: Confirmed with the local special inspection institute, buffer tank 2 with a volume of <25L, pipeline DN40, and design pressure <1.0MPa does not fall under the regulatory scope of pressure vessels and pressure pipelines, and therefore does not require inspection.

[0040] Back pressure test: at maximum discharge flow rate of 8 Nm 3 If the back pressure at the bottom of the discharge riser 6 (after the main flame arrester 5) is measured at 0.2 MPa / h, and is much lower than the allowable limit of 0.05 MPa, it indicates that the device fully meets the operating requirements of the front-end equipment.

[0041] Nitrogen consumption: Normal purging rate is 3L / min, with an average of 2 purgings per day (5 minutes each time), which translates to an annual consumption of approximately 1650 Nm³ of high-purity nitrogen. 3 If traditional continuous high-flow-rate nitrogen blanketing is used (based on a dilution to 4%, 192 Nm³ is required). 3 / h), with an annual consumption of approximately 1.682 million Nm³. 3 This solution saves approximately 99% of nitrogen.

[0042] Flame-retardant performance verification: In third-party testing, hydrogen gas was artificially ignited at the emission port. If the flame was extinguished immediately after touching the microporous flame-retardant dispersion head 14 and did not return to the inside of the pipeline, the flame-retardant effect was significant.

[0043] Water accumulation prevention effect: After operating for a full rainy season (6 months) in East China, the bottom of riser 6 and diffuser head 14 were disassembled and inspected to confirm that the inside was dry and free of water accumulation. A small amount of water marks were visible on the root guide slope, proving that the drainage function was normal. At the same time, the operation of the bottom drain valve was checked.

[0044] Diffusion effect: Within a 1-2 meter radius of the emission outlet, multiple points were detected using a portable hydrogen detector. No hydrogen concentration exceeding 25% LEL was detected, demonstrating excellent diffusion effect.

[0045] However, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Any changes or modifications to the above embodiments that are within the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. An electronic-grade hydrogen exhaust safety emission system, comprising an exhaust fan, characterized in that: It also includes a main flame arrester and an exhaust riser. The exhaust unit is connected to the exhaust riser via the hydrogen delivery pipeline and the main flame arrester. The top of the exhaust riser is provided with a microporous flame arrestor dispersion head. The microporous flame arrestor dispersion head is made of stainless steel powder metallurgy sintered material and forms a three-dimensional interconnected pore structure with exhaust and flame arrestor functions. The top of the microporous flame arrestor dispersion head has a blind plate sealing structure. The main flame arrester adopts a corrugated belt type or metal powder metallurgy sintered plate structure.

2. The electronic-grade hydrogen exhaust safety emission system as described in claim 1, characterized in that: The diameter of the pores is controlled between 0.3 and 0.8 mm, and the porosity is controlled between 30% and 50%.

3. The electronic-grade hydrogen exhaust safety emission system as described in claim 1 or 2, characterized in that: The microporous flame-arresting and dispersing head is a cylindrical or conical shape with a sealed top, and is fitted or welded to the top of the discharge riser. A conical rainproof cap is also provided above the microporous flame-arresting and dispersing head, and is supported and connected by stiffening plates.

4. The electronic-grade hydrogen exhaust safety emission system as described in claim 3, characterized in that: The outer diameter of the microporous flame-arresting dispersion head is larger than the outer diameter of the discharge riser, and there is an annular chamfered slope at the connection between the bottom of the microporous flame-arresting dispersion head and the discharge riser for guiding the flow; the bottom end of the discharge riser is provided with a water collection tank and a manual drain valve.

5. The electronic-grade hydrogen exhaust safety emission system as described in claim 1, characterized in that: It also includes a micro-thermal nitrogen purging unit, which includes a nitrogen source, a nitrogen injection ring located at the bottom of the discharge riser, and a heating control box. The nitrogen source is connected to the nitrogen injection ring through a nitrogen supply pipe. The nitrogen injection ring has a ring-shaped structure adapted to the horizontal cross-section of the discharge riser. Multiple purging microholes are evenly distributed on the upper surface of the nitrogen injection ring. An electric heating structure is arranged along the nitrogen supply pipe and the heating is controlled by the heating control box.

6. The electronic-grade hydrogen exhaust safety emission system as described in claim 5, characterized in that: The electric heat tracing structure includes a heat tracing tape attached to the outer surface of the nitrogen supply pipeline, and insulation wrapping tape, insulation cotton, and outdoor waterproof aluminum sheath wrapped from the inside out.

7. An electronic-grade hydrogen exhaust safety emission system as described in claim 5 or 6, characterized in that: A control pipeline is also connected between the nitrogen source and the nitrogen supply pipeline. The control pipeline includes two lines: one is a normally open pipeline equipped with a float flow controller to maintain a slight positive pressure in the discharge riser; the other is a bypass pipeline that can be linked with the exhaust fan, equipped with a flow regulating valve and a flow meter. When hydrogen emission from the exhaust fan is detected, the bypass pipeline is automatically opened, the nitrogen flow is increased through the flow regulating valve, and monitored by the flow meter. If the opening flow does not meet the set value, the exhaust fan is shut down.

8. The electronic-grade hydrogen exhaust safety emission system as described in claim 1, characterized in that: It also includes a buffer tank with a cyclone separation structure, located on the hydrogen delivery pipeline between the main flame arrester and the exhaust machine, and the bottom of the buffer tank is equipped with a drain valve.

9. The electronic-grade hydrogen exhaust safety emission system as described in claim 1, characterized in that: It also includes a static-conducting grounding busbar, used to form an equipotential connection with each hydrogen-passing component of the emission system and the ground.

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