A safety control method for an ultra-low concentration gas pretreatment system

Abstract

The present invention provides a safety control method for an ultra-low concentration gas pretreatment system, which includes the following steps: S1. Linkage adjustment of regulating valves; S2. Redundancy of similar equipment and instruments; S3. Design of safety distance; S4. Emergency linkage discharge; S5. Setting up a safety protection subsystem. By means of redundancy of similar equipment and instruments, the present invention ensures that the gas emission reduction and utilization device can still operate normally when any two (sets) or less of the instruments or equipment fail; and by using the means of linkage adjustment of regulating valves, design of safety distance and emergency linkage discharge, the extracted gas concentration is controlled within a safe range; finally, through the safety subsystem, high-pressure safety protection gas can be quickly released in case of a failure, and a safety air curtain is quickly formed at the entrance of the gas emission reduction and utilization device to block the combustible gas from entering the gas emission reduction and utilization device, further increasing the safety and reliability of the gas emission reduction and utilization system.

Description

Technical Field

[0001] The invention relates to a safety control method for an ultra-low concentration gas pretreatment system, belonging to the technical field of coal mine gas emission reduction and utilization. Background Art

[0002] Gas extraction refers to the process of extracting gas from underground mines or oil fields. Mines and oil fields often contain large quantities of hazardous and flammable gases, including methane. These gases are generated by geological structures and biodegradable materials. Gas concentrations between 5% and 16% can explode when exposed to open flames. High-concentration gas refers to gas with a concentration greater than 25%, while low-concentration gas refers to gas with a concentration less than 25%. Ultra-low-concentration coal mine gas emissions are enormous, equivalent to over 40 billion cubic meters of pure methane nationwide each year. Due to the low concentration and high safety risks, emission reduction technologies are not available, and all gas is discharged, resulting in a significant source of greenhouse gas emissions. Currently, gas pretreatment systems primarily utilize conventional features such as water removal, filtration, and concentration adjustment. The Chinese utility model patent number CN202222552536.7 discloses a cooling and dehydration device for gas pretreatment, which can ensure that the gas does not contain water vapor to the greatest extent; the Chinese invention patent number CN202211085414.X discloses a method for predicting gas concentration in an excavation working face based on a three-dimensional echo state network, which can predict and identify the gas concentration in the excavation face in real time.

[0003] However, the inventors of the present invention have discovered the following problems with existing technologies: Current gas pretreatment systems lack reliable measures to regulate concentration, and cannot guarantee absolute safety in the event of extreme circumstances such as instrument or equipment failures. Therefore, improvements are needed. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a safety control method for an ultra-low concentration gas pretreatment system. The safety control method for an ultra-low concentration gas pretreatment system adopts multiple control means, equipment redundancy and other methods to ensure the absolute safety of the gas emission reduction and utilization system.

[0005] The present invention is achieved through the following technical solutions.

[0006] The present invention provides a safety control method for an ultra-low concentration gas pretreatment system, comprising the following steps:

[0007] S1. Control valve linkage adjustment: The relief control valve is linked with the first and second gas flow control valves to allow an appropriate flow of extracted gas to enter the pretreatment system;

[0008] S2. Redundancy of similar equipment and instruments: For similar equipment with a primary mixing mixer and a secondary mixing mixer set successively, a first quick cut-off valve and a second quick cut-off valve are set adjacent to each other, as well as similar instruments such as a gas pressure sensor before the mixing state, a gas flow sensor, a methane concentration sensor before mixing, a methane concentration sensor after secondary mixing after the mixing state, a flow sensor after mixing, a laser in-situ methane concentration sensor, and a methane concentration sensor after primary mixing;

[0009] S3. Design safety distance: The installation distance between the primary mixing mixer and the methane concentration sensor after primary mixing is equal to the installation distance between the secondary mixing mixer and the methane concentration sensor after secondary mixing, set as L1, and the installation distance between the laser in-situ methane concentration sensor and the emergency mixing valve is set as L2;

[0010] S4. Emergency linkage discharge: When a fault occurs, the quick cut-off valve is cut off, and the emergency mixing valve and the purge and discharge valve are opened simultaneously. Fresh air enters the pipeline from the emergency mixing valve, and the mixed gas is discharged into the atmosphere by the purge and discharge valve;

[0011] S5. Set up a safety protection subsystem: When a fault occurs, the emergency inflation valve is opened, and the high-pressure safety protection gas stored in the safety protection gas storage tank quickly fills the pipeline at the inlet of the gas emission reduction and utilization device to prevent gas with an excessive concentration from entering the gas emission reduction and utilization device.

[0012] In the said step S1, the bleed regulating valve is installed in the middle of the gas bleed pipe; the first gas flow regulating valve and the second gas flow regulating valve are arranged in parallel.

[0013] In the said step S2, the first quick cut-off valve and the second quick cut-off valve are successively arranged between the cyclone dehydrator and the gas pressure sensor.

[0014] In the said step S2, the primary mixing mixer is set adjacent to the downstream of the first gas flow regulating valve; another upstream direction of the primary mixing mixer is connected with a primary mixing blower; the downstream direction of the primary mixing mixer is adjacent to and successively connected with a primary mixing mixer and a methane concentration sensor after primary mixing.

[0015] In the said step S2, the gas pressure sensor before the mixing state and the gas flow sensor are successively arranged between the second quick cut-off valve and the first gas flow regulating valve; the downstream of the secondary mixing mixer is adjacent to and successively connected with a methane concentration sensor after secondary mixing, a flow sensor after mixing, and a laser in-situ methane concentration sensor.

[0016] In the said step S3, L1 should satisfy the following relational expression:

[0017] L1 = C1·D, where C1 is a constant with a value range of 1.0×10-2 to 1.5×10-2. For a pipe diameter less than 1000 mm, the upper limit value is taken; for a pipe diameter greater than 2000 mm, the lower limit value is taken; D is the nominal pipe diameter.

[0018] In the said step S3, L2 should satisfy the following relational expression:

[0019] L2 = C2·v·D, where C2 is a constant with a value range of 3.2×10-3 to 4.0×10-3; v is the designed pipe flow velocity; D is the nominal pipe diameter.

[0020] In the said step S4, the emergency mixing valve is arranged on the upstream pipe of the blower and connected to the atmosphere; the purging and discharging valve is arranged on the downstream pipe of the blower and connected to the atmosphere.

[0021] In the said step S5, the emergency inflation valve is arranged on the upstream pipe of the quick cut-off valve, and the emergency inflation valve is connected to the safety protection gas storage tank downstream through a pipe.

[0022] The gas storage volume of the safety protection gas storage tank is V, and V should satisfy the following relational expression: V = C3·v·D2 / P, where C3 is a constant with a value range of 7.46×10-7 to 8.24×10-7; v is the designed pipe flow velocity; D is the nominal pipe diameter; P is the storage gas pressure. When storing compressed air, P is 0.8 to 1.2; when storing nitrogen, carbon dioxide, or argon, P is 1.6 to 2.0.

[0023] The beneficial effects of the present invention are as follows: By means of redundancy of similar equipment and instruments, it is ensured that the gas emission reduction and utilization device can still work normally when any two (sets) or less of the instruments or equipment fail; and by adopting the means of linkage adjustment of the regulating valve, designing the safety distance, and emergency linkage discharge, the concentration of the extracted gas is controlled within a safe range; finally, through the safety subsystem, the high-pressure safety protection gas can be quickly released in case of a failure, and a safety air curtain can be quickly formed at the inlet of the gas emission reduction and utilization device to block the combustible gas from entering the gas emission reduction and utilization device, further increasing the safety and reliability of the gas emission reduction and utilization system. Brief Description of the Drawings

[0024] Figure 1 It is the flowchart of the safety control method for the ultra-low concentration gas pretreatment system;

[0025] Figure 2 It is the structural schematic diagram of the ultra-low concentration gas pretreatment system.

[0026] In the figure: 1 - Drainage pump station, 2 - Bleed regulating valve, 3 - Gas bleed pipe, 4 - Manual valve at the inlet of the emission reduction system, 5 - Automatic water seal bleed valve, 6 - Methane concentration sensor before mixing, 7 - Cyclone dehydrator, 8 - First quick cut-off valve, 9 - Second quick cut-off valve, 10 - Gas pressure sensor, 11 - Gas flow sensor, 12 - First gas flow regulating valve, 13 - Second gas flow regulating valve, 14 - Primary mixing blower, 15 - Primary mixing mixer, 16 - Methane concentration sensor after primary mixing, 17 - Secondary mixing mixer, 18 - Air mixing regulating valve, 19 - Methane concentration sensor after secondary mixing, 20 - Flow sensor after mixing, 21 - Laser in-situ methane concentration sensor, 22 - Emergency mixing valve, 23 - Blower, 24 - Purge bleed valve, 25 - Emergency charging valve, 26 - Safety protection gas storage tank, 27 - Quick cut-off valve, 28 - Gas emission reduction and utilization device. Detailed implementation manners

[0027] The technical solution of the present invention will be further described below, but the scope of protection claimed is not limited thereto.

[0028] The first embodiment of the present invention mainly relates to a safety control method for an ultra-low concentration gas pretreatment system as shown in Figure 1-2 and includes the following steps:

[0029] S1. Linkage adjustment of regulating valves: The bleed regulating valve 2 is linked with the first gas flow regulating valve 12 and the second gas flow regulating valve 13 to allow an appropriate flow of extracted gas to enter the pretreatment system; when reducing and utilizing the gas, the bleed regulating valve 2 is closed slightly and the manual valve 4 at the inlet of the emission reduction system is opened. The bleed regulating valve 2 is linked with the first gas flow regulating valve 12 and the second gas flow regulating valve 13. When the extraction volume is large and the utilization volume is small, the bleed regulating valve 2 is opened wide; conversely, it is closed slightly. When the extraction and utilization volumes still cannot be matched after the adjustment of the bleed regulating valve 2 or the first quick cut-off valve 8 and the second quick cut-off valve 9 are closed, the automatic water seal bleed valve 5 is opened to bleed the excess extracted gas and ensure the safety of the system.

[0030] S2. Redundancy of similar equipment and instruments: Similar equipment including the primary mixing mixer 15 and the secondary mixing mixer 17 is provided successively, the first quick cut-off valve 8 and the second quick cut-off valve 9 are arranged adjacent to each other, and similar instruments such as the gas pressure sensor 10, the gas flow sensor 11, the methane concentration sensor 6 before mixing, the methane concentration sensor 19 after secondary mixing, the flow sensor 20 after mixing, the laser in-situ methane concentration sensor 21, and the methane concentration sensor 16 after primary mixing are arranged adjacent to each other before the mixing state; various sensors can detect the extracted gas data to ensure the safety of the system; the laser in-situ methane concentration sensor 21 adopts a monitoring instrument with a fast response, and its response time must be less than 1 s.

[0031] S3. Design safety distance: The installation distance between the primary mixing mixer 15 and the methane concentration sensor 16 after primary mixing is equal to the installation distance between the secondary mixing mixer 17 and the methane concentration sensor 19 after secondary mixing, which is set as L1, and the installation distance between the laser in-situ methane concentration sensor 21 and the emergency mixing valve 22 is set as L2; Sufficient safety distance can allow the extracted gas and fresh air to be fully mixed;

[0032] S4. Emergency linkage discharge: When a fault occurs, the quick cut-off valve 27 is cut off, and the emergency mixing valve 22 and the purge and discharge valve 24 are opened simultaneously. Fresh air enters the pipeline from the emergency mixing valve 22, and the mixed gas is discharged into the atmosphere by the purge and discharge valve 24; The gas concentration in the upstream and downstream pipelines of the blower 23 is rapidly reduced to ensure the safety of the gas emission reduction and utilization system;

[0033] S5. Set up a safety protection subsystem: When a fault occurs, the emergency inflation valve 25 is opened, and the high-pressure safety protection gas stored in the safety protection gas storage tank 26 quickly fills the pipeline at the inlet of the gas emission reduction and utilization device 28 to prevent the gas with an excessive concentration from entering the gas emission reduction and utilization device 28; Ensure the safety of the gas emission reduction and utilization system.

[0034] The second embodiment of the present invention is basically the same as the first embodiment, mainly in the preferred scheme of the safety control method. In step S1, the discharge regulating valve 2 is installed in the middle of the gas discharge pipe 3; The first gas flow regulating valve 12 and the second gas flow regulating valve 13 are arranged in parallel to regulate the extracted gas flow rate. The parallel arrangement of the two valves improves the regulation accuracy.

[0035] In step S2, the first quick cut-off valve 8 and the second quick cut-off valve 9 are sequentially arranged between the cyclone dehydrator 7 and the gas pressure sensor 10, and are opened simultaneously when using gas and closed simultaneously in case of a fault to ensure the reliable cut-off of the extracted gas.

[0036] In step S2, the primary mixing mixer 15 is closely arranged downstream of the first gas flow regulating valve 12; Another upstream direction of the primary mixing mixer 15 is connected with a primary mixing blower 14; Downstream of the primary mixing mixer 15, the primary mixing mixer 15 and the methane concentration sensor 16 after primary mixing are closely connected in sequence. Both the primary mixing mixer 15 and the secondary mixing mixer 17 can reduce the concentration of the extracted gas by mixing with fresh air.

[0037] In step S2, the gas pressure sensor 10 and the gas flow sensor 11 before the blending state are successively arranged between the second quick cut-off valve 9 and the first gas flow regulating valve 12; downstream of the secondary blending mixer 17, a secondary post-blending methane concentration sensor 19, a post-blending flow sensor 20, and a laser in-situ methane concentration sensor 21 are successively connected adjacent to each other. The use of secondary blending and three methane concentration sensors increases equipment redundancy and improves the safety and reliability of the system.

[0038] The third embodiment of the present invention is basically the same as the first embodiment, mainly in further optimization. In step S3, L1 should satisfy the following relational expression:

[0039] L1 = C1·D where C1 is a constant, and its value range is 1.0×10-2 to 1.5×10-2. When the pipe diameter is less than 1000 mm, the upper limit value is taken; when the pipe diameter is greater than 2000 mm, the lower limit value is taken; D is the nominal pipe diameter in units of mm. When the requirement of the installation distance L1 is met, the methane-air mixture can be ensured to be evenly mixed, and the methane concentration detection result is true and reliable.

[0040] In step S3, L2 should satisfy the following relational expression:

[0041] L2 = C2·v·D where C2 is a constant, and its value range is 3.2×10-3 to 4.0×10-3; v is the designed pipe flow velocity in units of m / s; D is the nominal pipe diameter in units of mm. When the requirement of the installation distance L2 is met, it can be ensured that the quick cut-off valve 27 has been closed before the gas mixture with excessive concentration reaches the quick cut-off valve 27, ensuring the safety of the gas emission reduction and utilization system.

[0042] In step S4, the emergency blending valve 22 is arranged on the upstream pipe of the blower 23 and is connected to the atmosphere; the purge and relief valve 24 is arranged on the downstream pipe of the blower 23 and is connected to the atmosphere. When a device failure occurs, the quick cut-off valve 27 cuts off, and the emergency blending valve 22 and the purge and relief valve 24 are opened simultaneously. Fresh air enters the pipe from the emergency blending valve 22, and the mixed gas is discharged into the atmosphere by the purge and relief valve 24, quickly reducing the gas concentration in the upstream and downstream pipes of the blower 23 and ensuring the safety of the gas emission reduction and utilization system.

[0043] In step S5, the emergency inflation valve 25 is arranged on the pipeline upstream of the quick cut-off valve 27, and the emergency inflation valve 25 is connected to the downstream safety protection gas storage tank 26 through a pipeline. In case of a fault, the emergency inflation valve 25 is opened, and the high-pressure safety protection gas stored in the safety protection gas storage tank 26 quickly fills the pipeline at the inlet of the gas emission reduction and utilization device 28, preventing the gas with an excessive concentration from entering the gas emission reduction and utilization device 28 and ensuring the safety of the gas emission reduction and utilization system. The emergency inflation valve 25 and the safety protection gas storage tank 26 are a relatively independent safety protection subsystem, which can be automatically started in case of a fault or a power outage, further increasing the safety and reliability of the system.

[0044] The gas storage volume of the safety protection gas storage tank 26 is V (unit: m3), and V should satisfy the following relational expression: V = C3·v·D2 / P. Where, C3 is a constant, and its value range is 7.46×10-7~8.24×10-7; v is the designed pipeline flow velocity (unit: m / s); D is the nominal pipeline diameter (unit: mm); P is the storage gas pressure (unit: MPa). When storing compressed air, P is 0.8~1.2; when storing nitrogen, carbon dioxide, or argon, P is 1.6~2.0. The safety protection gas storage tank 26 can use compressed air as the safety protection gas; it can also use inert gases with flame retardant and explosion suppression functions such as nitrogen, carbon dioxide, and argon as the safety protection gas, and its safety protection effect is better. The protection gas that meets the gas storage volume formula can ensure that the stored protection gas can generate a protection gas curtain in a certain time and space, ensuring the safety protection effect.

Claims

1. A safety control method for an ultra-low concentration gas pretreatment system, characterized in that, It includes the following steps: S1. Linkage adjustment of regulating valves: The bleed regulating valve (2) is linked with the first gas flow regulating valve (12) and the second gas flow regulating valve (13) to allow the extracted gas with an appropriate flow rate to enter the pretreatment system; The bleed regulating valve (2) is installed in the middle of the gas bleed pipe (3); the first gas flow regulating valve (12) and the second gas flow regulating valve (13) are arranged in parallel; S2. Redundancy of similar equipment and instruments: Similar equipment including a primary blending mixer (15) and a secondary blending mixer (17) is successively arranged, and a first quick cut-off valve (8) and a second quick cut-off valve (9) are closely arranged, as well as similar instruments such as a gas pressure sensor (10), a gas flow sensor (11), a methane concentration sensor (6) before blending, a methane concentration sensor (19) after secondary blending, a flow sensor (20) after blending, a laser in-situ methane concentration sensor (21), and a methane concentration sensor (16) after primary blending before the blending state; The first quick cut-off valve (8) and the second quick cut-off valve (9) are successively arranged between the cyclone dehydrator (7) and the gas pressure sensor (10); The gas pressure sensor (10) and the gas flow sensor (11) before the blending state are successively arranged between the second quick cut-off valve (9) and the first gas flow regulating valve (12); downstream of the secondary blending mixer (17), a methane concentration sensor (19) after secondary blending, a flow sensor (20) after blending, and a laser in-situ methane concentration sensor (21) are successively and closely connected; S3. Design of safety distance: The installation distance between the primary blending mixer (15) and the methane concentration sensor (16) after primary blending is equal to the installation distance between the secondary blending mixer ( ​ ​ ​ 2. The safety control method for the ultra-low concentration gas pretreatment system according to claim 1, characterized in that: ​ 3. The safety control method for the ultra-low concentration gas pretreatment system according to claim 1, characterized in that: In the step S3, L1 should satisfy the following relational expression: L1 = C1·D where C1 is a constant, and its value range is 1.0×10 -2 ~1.5×10 -2 , when the pipe diameter is less than 1000 mm, take the upper limit value; when the pipe diameter is greater than 2000 mm, take the lower limit value; D is the nominal pipe diameter, unit: mm.

4. The safety control method for the ultra-low concentration gas pretreatment system according to claim 1, characterized in that: In the step S5, an emergency inflation valve (25) is arranged on the upstream pipeline of the quick cut-off valve (27), and the emergency inflation valve (25) is connected to a downstream safety protection gas storage tank (26) through a pipeline.

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