Linkage cut-off protection device for chemical combustible gas detection

Abstract

The application discloses a linkage cut-off protection device for chemical combustible gas detection and belongs to the technical field of combustible gas detection. The device comprises a controller and at least one of the following: a detector, a main cut-off valve, an air exhaust mechanism and an explosion-proof mechanism. The controller is internally provided with a multi-stage concentration threshold module, a concentration change rate calculation module and a linkage control module. The device adopts a double-dimension determination mode combining the concentration value of combustible gas with the concentration rising rate, is more accurate and sensitive in risk identification of a gas pipeline, and improves the prevention and control accuracy when combustible gas leaks around the gas pipeline. The double-slope threshold and multi-stage concentration threshold can form a cooperative determination logic, which can avoid unnecessary production interruption of the gas pipeline due to slight leakage, ensure the continuity of workshop production, quickly respond to the leakage point of the gas pipeline, and achieve an optimal balance between safety protection requirements and the continuity of workshop production.

Description

Technical Field

[0001] This invention relates to the field of combustible gas detection technology, and in particular to a linkage cut-off protection device for detecting combustible chemical gases. Background Technology

[0002] Combustible gas transportation is a core production link in process industries such as petrochemicals and coal chemicals. Its safe and stable operation is directly related to the continuity of plant production, the safety of personnel and property, and the safety of the surrounding ecological environment. Combustible gas leakage is one of the most frequent and dangerous types of accidents in chemical production.

[0003] The applicant obtained the following prior art through searching. Specifically, patent CN120877483A discloses a gas safety linkage control method and system based on multi-level alarm thresholds, including the following steps: acquiring the operating data of the target to be tested, forming an operating feature vector, and dynamically correcting the standard lower explosive limit concentration threshold based on the operating feature vector; comparing the real-time gas concentration with the corrected concentration threshold, and generating an initial classification judgment result by combining the concentration change rate and duration parameters; performing trend prediction based on the time series data in the operating feature vector, and correcting the initial classification judgment result; spatially fusing the corrected classification judgment result, and cross-validating it with the operating status and reliability of the monitoring unit to generate a final risk level; triggering a progressive linkage control action based on the final risk level; this system solves the problems of missed alarms, false alarms, and response lag in gas safety monitoring through multi-level threshold dynamic correction and trend prediction.

[0004] As can be seen from the patent above, although the system constructs an operational feature vector by collecting multi-source operational data, thereby achieving dynamic correction of the standard lower explosive limit concentration threshold, and effectively solves the problems of missed alarms, false alarms, and response lag in traditional fixed threshold schemes, significantly improving the intelligence and accuracy of gas safety monitoring, it still has certain shortcomings in actual use. For example, existing on / off shut-off valves can usually only achieve two states: fully open or fully closed. When the system determines that there is a risk of leakage in the pipeline, it may either directly shut off the pipeline due to misjudgment, causing production stoppage, resulting in economic losses for the enterprise and reduced production efficiency; or it may delay the shut-off action to avoid production interruption, missing the best intervention opportunity, thus causing the leakage to continue to increase and the risk of accident to rise sharply. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of existing technologies and provide a chemical combustible gas detection and linkage cut-off protection device capable of tiered intervention, ensuring continuous and stable operation of workshop production, guaranteeing production efficiency, and improving the accuracy of combustible gas leakage prevention and control. This invention also provides a chemical combustible gas detection and linkage cut-off protection method.

[0006] To achieve the above objectives, the present invention provides a linkage cut-off protection device for detecting combustible chemical gases, comprising a controller and at least one detector, a main shut-off valve, an exhaust mechanism, and an explosion-proof mechanism communicatively connected to the controller. The controller incorporates a multi-level concentration threshold module, a concentration change rate calculation module, and a linkage control module. The detector is used to collect the combustible gas concentration around the gas pipeline in real time. The main shut-off valve is installed on the gas pipeline and its opening degree can be continuously adjusted. The explosion-proof mechanism is used to inject inert gas into the gas pipeline.

[0007] The controller is configured to activate the exhaust mechanism when the combustible gas concentration reaches a warning value and the rate of increase in concentration is lower than a first preset slope; when the combustible gas concentration reaches an intervention value, or the concentration reaches a warning value and the rate of increase in concentration exceeds the first preset slope, it outputs a pre-action signal to drive the main shut-off valve to adjust to a pre-closed state, and simultaneously activates the explosion-proof mechanism to inject inert gas into the gas pipeline; when the combustible gas concentration reaches a danger value, or the rate of increase in concentration at any concentration exceeds a second preset slope, it outputs a full-close signal to drive the main shut-off valve from the pre-closed state to the full-closed state.

[0008] Preferably, the system further includes a pressure sensor, which is disposed in the gas transmission pipeline upstream of the main shut-off valve. The main shut-off valve is pre-closed with an opening of 10%-50%. In the pre-closed state, the pressure sensor monitors the internal gauge pressure of the gas transmission pipeline in real time and feeds it back to the controller. The controller synchronously adjusts the opening of the main shut-off valve to maintain a gauge pressure of 0.01MPa-0.05MPa in the gas transmission pipeline.

[0009] Preferably, the multi-level concentration threshold module has built-in warning values, intervention values, and danger values, which correspond to 10%, 25%, and 50% of the standard lower explosive limit concentration of combustible gas, respectively; the first preset slope is 0.5%LEL / min, and the second preset slope is 2%LEL / min.

[0010] Preferably, the controller further includes an opening adjustment module, which is used to dynamically adjust the pre-closing opening of the main shut-off valve according to the real-time concentration rise rate: when the concentration rise rate is less than 0.5%LEL / min, the pre-closing opening is set to 40%-50%; when the concentration rise rate is 0.5%-2%LEL / min, the pre-closing opening is set to 20%-40%; when the concentration rise rate is greater than 2%LEL / min, the pre-closing opening is set to 10%-20%.

[0011] Preferably, the controller further includes a monitoring module, which is used to continuously monitor the changing trend of combustible gas concentration when the main shut-off valve is in a pre-closed state, so that the controller can adjust the opening degree of the main shut-off valve.

[0012] Preferably, the explosion-proof mechanism includes a gas tank, a solenoid valve, a pressure reducing valve, and a nozzle. The solenoid valve and the pressure reducing valve are connected in series on the pipeline between the gas tank and the nozzle. The gas tank is equipped with a monitoring sensor for real-time monitoring of the internal pressure of the gas tank. The monitoring sensor, the solenoid valve, and the pressure reducing valve are all communicatively connected to the controller.

[0013] A method for linkage cut-off protection for detection of combustible chemical gases, using a linkage cut-off protection device for detection of combustible chemical gases as described in any one of the above-mentioned methods, characterized by comprising the following steps:

[0014] S1: The detector collects the concentration of combustible gas around the gas pipeline in real time, the pressure sensor collects the gauge pressure inside the gas pipeline in real time, and the controller calculates the real-time concentration change rate.

[0015] S2: The controller compares the real-time concentration with multi-level concentration thresholds and combines the concentration change rate to generate a risk level judgment result of early warning level, intervention level or danger level;

[0016] S3: The controller executes corresponding linkage control actions according to the risk level: when the risk level is the warning level, the exhaust mechanism is activated; when the risk level is the intervention level, a pre-action signal is output to drive the main shut-off valve to adjust to the pre-closed state, and at the same time, the explosion-proof mechanism is activated to inject inert gas into the gas pipeline, and the controller adjusts the opening of the main shut-off valve according to the gauge pressure data fed back by the pressure sensor to maintain a gauge pressure of 0.01MPa-0.05MPa in the gas pipeline; when the risk level is the danger level, a full-close signal is output to drive the main shut-off valve from the pre-closed state to the full-closed state, and at the same time, the entire system emergency linkage is activated.

[0017] S4: When the main shut-off valve is in the pre-closed state, the controller continuously monitors the trend of combustible gas concentration change. If the concentration continues to decrease and falls below the warning value for a preset time, the controller drives the main shut-off valve to return to the fully open state and closes the explosion-proof mechanism. If the concentration continues to rise slowly, the controller further reduces the opening of the main shut-off valve and increases the inert gas injection flow rate of the explosion-proof mechanism through the opening adjustment module. If the concentration continues to rise rapidly, the controller immediately drives the main shut-off valve to adjust to the fully closed state.

[0018] S5: When the controller drives the main shut-off valve into a pre-closed state or a fully closed state, the controller synchronously sends a corresponding level of linkage signal to the chemical production process control system to trigger the chemical production process control system to perform a matching process adjustment operation.

[0019] Beneficial effects:

[0020] 1. The chemical combustible gas detection and linkage cut-off protection device of the present invention abandons the traditional crude judgment mode of single concentration threshold for combustible gas leakage detection. Instead, it adopts a two-dimensional judgment method that combines the concentration value of combustible gas and the concentration rise rate. This makes the risk identification of gas transmission pipelines more accurate and sensitive, and improves the accuracy of prevention and control of combustible gas leakage around gas transmission pipelines.

[0021] 2. The chemical combustible gas detection and linkage cut-off protection device of the present invention can form a collaborative judgment logic through dual slope threshold and multi-level concentration threshold. This can not only avoid unnecessary production interruptions caused by minor leaks in gas pipelines, ensuring the continuity of workshop production and guaranteeing the production efficiency of workshop operations, but also respond quickly to the leak point of gas pipelines, achieving an optimal balance between safety protection requirements and workshop production continuity.

[0022] 3. The chemical combustible gas detection and linkage cut-off protection device of the present invention can achieve a precise determination of the degree of risk of combustible gas leakage in gas pipelines by using the cooperation of two slope thresholds. This can effectively make up for the shortcomings of the existing technology that only detects the concentration value of combustible gas and cannot determine the leakage rate, thereby realizing the advanced prediction of leakage risk and precise graded response. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of a linkage cut-off protection device for detecting combustible chemical gases according to an embodiment of the present invention;

[0025] Figure 2 This is a flowchart of a chemical combustible gas detection and linkage cut-off protection method according to an embodiment of the present invention.

[0026] In the diagram: 1-Controller; 2-Main shut-off valve; 3-Explosion-proof mechanism; 4-Gas pipeline; 5-Gas tank; 6-Solenoid valve; 7-Pressure reducing valve; 8-Nozzle. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0029] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0030] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0031] Example 1:

[0032] This invention proposes a linkage cut-off protection device for detecting combustible chemical gases.

[0033] In one embodiment of the present invention, the linkage cut-off protection device for detecting combustible chemical gases includes a controller 1 and at least one detector, a main shut-off valve 2, an exhaust mechanism, and an explosion-proof mechanism 3 that are communicatively connected to the controller 1. The controller 1 has a built-in multi-level concentration threshold module, a concentration change rate calculation module, and a linkage control module. The detector is used to collect the concentration of combustible gas around the gas pipeline 4 in real time. The main shut-off valve 2 is installed on the gas pipeline 4 and its opening degree can be continuously adjusted. The explosion-proof mechanism 3 is used to inject inert gas into the gas pipeline 4.

[0034] The controller 1 is configured to activate the exhaust mechanism when the concentration of combustible gas reaches the warning value and the rate of increase of the concentration is lower than the first preset slope; when the concentration of combustible gas reaches the intervention value, or the concentration reaches the warning value and the rate of increase of the concentration exceeds the first preset slope, it outputs a pre-action signal to drive the main shut-off valve 2 to adjust to the pre-closed state, and at the same time activates the explosion-proof mechanism 3 to inject inert gas into the gas pipeline 4; when the concentration of combustible gas reaches the danger value, or the rate of increase of the concentration at any concentration exceeds the second preset slope, it outputs a full-close signal to drive the main shut-off valve 2 from the pre-closed state to the full-closed state.

[0035] Working principle: such as Figure 1 As shown, in the linkage cut-off protection device for detecting combustible chemical gases of the present invention, the detectors are arranged around the flanges, valves or welds of the gas pipeline 4, which are prone to leakage, thereby continuously collecting combustible gas concentration data of the surrounding environment of the gas pipeline 4 and transmitting it to the controller 1 in real time. The controller 1, as the core control unit of the entire device, stores the preset graded concentration thresholds through the built-in multi-level concentration threshold module, processes the concentration data transmitted by the detectors in real time through the concentration change rate calculation module to obtain the rate of increase of combustible gas concentration, and then performs a two-dimensional coupling judgment of the concentration value and the rate of increase of concentration through the linkage control module to generate corresponding control commands and send them to the main cut-off valve 2, the exhaust mechanism and the explosion-proof mechanism 3. The main shut-off valve 2, as the core actuator, is installed on the pipe body of the gas pipeline 4. Relying on its structural characteristic of continuously adjustable opening, it can receive commands from the controller 1 and smoothly switch between three states: fully open, pre-closed, and fully closed. The exhaust mechanism is located in the factory building or pipe gallery area where the gas pipeline 4 is located, and can start operation after receiving commands from the controller 1, thereby accelerating the diffusion and dilution of combustible gases. The explosion-proof mechanism 3 is connected to the gas pipeline 4 and, after receiving commands from the controller 1, injects inert gas (such as nitrogen) into the gas pipeline 4 in a directional manner, thereby achieving inertization protection inside the gas pipeline 4.

[0036] Specifically, such as Figure 1As shown, in this embodiment, the multi-level concentration threshold module, concentration change rate calculation module, and linkage control module built into the controller 1 work together to abandon the crude mode of relying solely on concentration values ​​to determine risk in existing technologies. Instead, a dual-dimensional determination method combining the concentration value of combustible gas and the concentration rise rate is adopted. This makes the risk identification of the gas transmission pipeline 4 more accurate and sensitive, improving the accuracy of prevention and control when combustible gas leaks in the gas transmission pipeline 4. Specifically, the multi-level concentration threshold module is used to delineate the risk levels of combustible gas leaks, serving as the basic basis for determining the risk level; the concentration change rate calculation module is used to calculate the unit time increase of combustible gas concentration in real time, i.e., the concentration rise rate, and matches it with two key thresholds: a first preset slope and a second preset slope; the linkage control module is used to output corresponding linkage control commands based on the dual determination results of concentration value and concentration rise rate, thereby avoiding misjudgments due to instantaneous concentration fluctuations or minor leaks in the gas transmission pipeline 4. This reduces unnecessary shut-off actions on the gas transmission pipeline 4 from the source of determination, laying the foundation for ensuring continuous production operation and improving the work efficiency of the workshop.

[0037] It should be noted that both the first preset slope and the second preset slope are threshold values ​​for the rate of increase of combustible gas concentration, expressed in %LEL / min. LEL stands for Lower Explosive Limit, a universally accepted standard unit of measurement for the safety detection of combustible gases in the chemical industry. The first preset slope is the primary threshold for leakage rate, used to distinguish between minor, slow leaks and moderately rapid leaks; the second preset slope is the secondary threshold for leakage rate, used to distinguish between moderately rapid leaks and acute, urgent leaks. This invention, through the combined use of these two slope thresholds, enables a refined assessment of the hazard level of combustible gas leaks in gas pipeline 4. This effectively overcomes the shortcomings of existing technologies that only detect the concentration of combustible gas and cannot determine the rate of leak development, thereby achieving advanced prediction and precise, tiered response to leakage risks.

[0038] Specifically, the dual-slope threshold and multi-level concentration threshold of the present invention can form a collaborative judgment logic. When the concentration value of combustible gas leakage has not yet reached the intervention value but its concentration rise rate has exceeded the first preset slope (that is, the current concentration of combustible gas is still at a low level and has not yet reached the concentration standard for conventional intervention. At this time, in order to ensure the overall production and processing efficiency of the workshop, it is not necessary to completely close the main shut-off valve 2, but the leakage rate is accelerating and the combustible gas concentration is rising synchronously), the controller 1 can identify the accelerating diffusion trend of combustible gas leakage in advance and immediately start the pre-closure of the main shut-off valve 2. Intervention causes the main shut-off valve 2 to close to a preset opening (not completely closed) to reduce the leakage rate and concentration of combustible gas. At the same time, the controller 1 issues an alarm message (which can be linked to alarm devices such as audible and visual alarms or directly sent to the operator's host computer) so that the operator can promptly detect the leak and repair it. This not only avoids unnecessary production interruptions caused by minor leaks in the gas pipeline 4, ensuring the continuity of workshop production and guaranteeing the production efficiency of workshop operations, but also enables a rapid response to the leak point of the gas pipeline 4, achieving an optimal balance between safety protection requirements and workshop production continuity. Furthermore, when the rate of increase of combustible gas concentration exceeds the second preset slope at any concentration value, the controller 1 directly determines it as a serious emergency leak such as a rupture of the gas pipeline 4, and immediately drives the main shut-off valve 2 to switch to the fully closed state and cut off the gas pipeline 4. This can cut off the continuous supply of combustible gas, prevent the further rapid expansion of the leak from the source, avoid the combustible gas from spreading over a large area in a short period of time and mixing with air to form an explosive mixture, and prevent major safety accidents caused by combustible gas leaks. At the same time, compared with the traditional system's delayed mechanism that requires waiting for the concentration to accumulate to a dangerous value before triggering pipeline shut-off, this invention sets the second preset slope as an independent emergency shut-off judgment condition, which can identify faults such as rupture of the gas pipeline 4 at the initial moment of the leak. This can reduce the response time from the traditional several minutes to the second level, and buy valuable golden time for the evacuation of on-site personnel and emergency response.

[0039] Furthermore, as a sensing component for combustible gas leaks, the detector can specifically adopt an explosion-proof combustible gas detector from the existing technology. It can use either catalytic combustion or infrared absorption detection principles, thereby enabling it to collect the combustible gas concentration around easily leaking points such as flanges, valves, or welds of the gas pipeline 4 in real time, accurately, and stably, and upload the concentration data to the controller 1 in real time, providing real and reliable raw data for the controller 1's two-dimensional risk assessment. Meanwhile, in this embodiment, the main shut-off valve 2 can be driven to open and close the gas pipeline 4 by a cylinder or a hydraulic cylinder. That is, the piston rod of the cylinder or hydraulic cylinder is connected to the valve stem of the main shut-off valve 2, and the control end of the cylinder or hydraulic cylinder is communicatively connected to the controller 1. This allows the controller 1 to precisely control the extension and retraction displacement of the piston rod by adjusting the air flow and pressure of the cylinder or the oil flow and pressure of the hydraulic cylinder. In this way, the linear displacement of the cylinder or hydraulic cylinder is converted into the opening adjustment action of the valve core of the main shut-off valve 2, thereby realizing the continuous and smooth adjustment of the main shut-off valve 2 within any opening range of 0-100%, and being able to stably maintain the pre-closed opening state.

[0040] Furthermore, in this embodiment, the exhaust mechanism, as the initial response unit for leaks, is activated independently only when the concentration of combustible gas reaches a warning value and the rate of increase in concentration is lower than the first preset slope, indicating a high-risk level. This means that forced ventilation accelerates the diffusion and dilution of combustible gas around the gas pipeline 4, effectively addressing minor, slow leaks without adjusting the opening of the main shut-off valve 2. This maximizes the maintenance of continuous and stable chemical production, effectively avoiding unplanned shutdowns caused by misjudging minor leaks and directly shutting off the gas pipeline 4 as in existing technologies. Simultaneously, when the main shut-off valve 2 enters the pre-closed state, the explosion-proof mechanism 3 is activated, injecting inert gas directionally into the gas pipeline 4. This, combined with the flow cross-section retained in the pre-closed state of the main shut-off valve 2, ensures a continuous directional flow of the upstream combustible gas and inert gas mixture from the gas pipeline 4 towards the leak point. This prevents external air from being drawn back into the gas pipeline 4 through the leak point, effectively avoiding the risk of secondary explosions caused by negative pressure forming in the gas pipeline 4 after the main shut-off valve 2 is quickly fully closed, resulting in an explosive mixture of air and residual combustible gas.

[0041] It is worth noting that controller 1 is also connected to the chemical production process control system in the workshop to send a pre-shutdown signal to the chemical production process control system when the main shut-off valve 2 enters the pre-closed state. This enables the chemical production process control system to perform at least one of the following operations: reduce the heating power and stirring speed of the reactor, reduce the flow rate of the feed pump to the minimum maintenance flow rate, or start the plant-wide inert gas protection system. This allows for the simultaneous reduction of the generation and transport load of combustible gas at the source, avoiding secondary process failures such as reaction runaway and equipment overload caused by the gas pipeline 4 being controlled alone.

[0042] Example 2:

[0043] This embodiment, based on Embodiment 1, further enhances the explosion-proof safety and operational stability of the entire device by adding a pressure sensor. Specifically, as shown... Figure 1 As shown, it also includes a pressure sensor, which is installed in the gas pipeline 4 upstream of the main shut-off valve 2. The opening degree of the main shut-off valve 2 in the pre-closed state is 10%-50%. In the pre-closed state, the pressure sensor monitors the internal gauge pressure of the gas pipeline 4 in real time and feeds it back to the controller 1. The controller 1 synchronously adjusts the opening degree of the main shut-off valve 2 to maintain the gauge pressure of 0.01MPa-0.05MPa in the gas pipeline 4.

[0044] In this embodiment, the pressure sensor can be an explosion-proof diffused silicon pressure sensor that meets the explosion-proof requirements of chemical industry, thus enabling the pressure sensor to operate stably for a long time in flammable and explosive gas environments. Simultaneously, the pressure sensor can be installed on the inner wall of the gas pipeline 4 1-2 meters upstream of the main shut-off valve 2. This location accurately reflects the pressure status of the gas pipeline 4 upstream of the main shut-off valve 2, thereby avoiding the influence of the throttling effect of the main shut-off valve 2 on the pressure detection accuracy and providing reliable raw data for the pressure regulation of the controller 1. It should be noted that the pre-closed state opening degree of the main shut-off valve 2 is 10%-50%. This opening range is determined by comprehensive optimization considering the normal operating pressure of the chemical gas pipeline 4, leakage control requirements, and anti-backflow requirements. Specifically, when the pre-closing opening of the main shut-off valve 2 is greater than 50%, the flow area of ​​the gas pipeline 4 is too large, making it difficult to effectively limit the expansion of leakage and thus hindering intervention and control. When the pre-closing opening is less than 10%, the flow area of ​​the gas pipeline 4 is too small, leading to insufficient supply of combustible gas. This causes the pressure inside the gas pipeline 4 to drop rapidly and form a negative pressure, increasing the risk of backflow of external air and potentially affecting the normal operation of downstream equipment in the workshop. Therefore, by controlling the pre-closing opening of the main shut-off valve 2 within a reasonable range of 10%-50%, it is possible to effectively limit leakage while ensuring the internal pressure of the gas pipeline 4, thus guaranteeing the normal operation of the workshop equipment.

[0045] Understandably, this embodiment, by setting a pressure sensor upstream of the main shut-off valve 2 and constructing a pressure closed-loop control system, can achieve precise dynamic regulation of the pressure inside the gas pipeline 4 when the main shut-off valve 2 is in a pre-closed state. Specifically, when the gauge pressure inside the gas pipeline 4 is lower than 0.01 MPa, the controller 1 drives the main shut-off valve 2 to increase its opening, increasing the inflow of upstream gas and raising the pressure inside the gas pipeline 4; when the gauge pressure inside the gas pipeline 4 is higher than 0.05 MPa, the controller 1 drives the main shut-off valve 2 to decrease its opening, reducing the inflow of upstream gas and lowering the pressure inside the gas pipeline 4. Through this real-time dynamic adjustment, the gauge pressure inside the gas pipeline 4 is always stably maintained within the slightly positive pressure range of 0.01 MPa-0.05 MPa. Furthermore, the slightly positive pressure of 0.01MPa-0.05MPa within the gas pipeline 4 ensures that the internal gas maintains a preset directional flow, effectively preventing outside air from being drawn back into the pipeline 4 through the leak point. This eliminates the core risk of secondary explosions caused by negative pressure forming in the pipeline 4 after the traditional shut-off valve is quickly fully closed, resulting in a mixture of air and residual combustible gas. Simultaneously, the stable pressure in the gas pipeline 4 prevents upstream compressors and pumps from experiencing surges or overloads due to excessive pressure fluctuations, ensuring the continuous and stable operation of the upstream production system. Moreover, this dynamic pressure control method automatically adjusts the opening of the main shut-off valve 2 according to changes in leakage, maximizing gas supply while ensuring safety, further balancing the relationship between safety protection and production continuity.

[0046] Example 3:

[0047] This embodiment, based on embodiment 2, further defines the multi-level concentration thresholds and concentration change rate thresholds built into controller 1 to clarify the boundary for determining the risk level, thereby further improving the device's accuracy in identifying and responding to leakage risks. Specifically, as follows... Figure 1 As shown, the multi-level concentration threshold module has built-in warning values, intervention values, and danger values, which correspond to 10%, 25%, and 50% of the standard lower explosive limit concentration of combustible gas, respectively; the first preset slope is 0.5%LEL / min, and the second preset slope is 2%LEL / min.

[0048] In this embodiment, the concentration threshold and the determination threshold of the concentration change rate of combustible gas are determined by comprehensively optimizing the general specifications for combustible gas safety detection in the chemical industry, a large amount of actual leakage accident data, and the control logic of the graded intervention of this invention. Specifically, the warning value is set at 10% LEL of the standard lower explosive limit of combustible gas concentration. At this time, it indicates that the leakage is extremely small and has not yet formed an explosion risk. The hidden danger can be eliminated by ventilation dilution only (but during the workshop shutdown and maintenance, the leakage point of gas pipeline 4 still needs to be maintained to avoid the risk of combustible gas leakage from increasing). The intervention value is set at 25% LEL of the standard lower explosive limit of combustible gas concentration. When the combustible gas concentration reaches this value, it indicates that the explosion risk has increased significantly, and active intervention measures must be taken to control the development of the leakage. The danger value is set at 50% LEL of the standard lower explosive limit of combustible gas concentration, which means that the concentration of combustible gas is close to half of the lower explosive limit, that is, an explosion may be triggered at any time by an ignition source. At this time, the gas supply must be cut off immediately to ensure the safety of workshop production.

[0049] Meanwhile, for the concentration change rate threshold, the first preset slope is set to 0.5%LEL / min to distinguish between minor, slow leaks and moderately rapid leaks in gas pipeline 4. When the concentration rise rate is below this value, it indicates that the leak source has a small aperture and the leak is developing slowly, allowing sufficient time for investigation and handling. Completely shutting down gas pipeline 4 is not necessary, which helps ensure production and processing operations in the workshop. When the concentration rise rate exceeds this value, it indicates that the leak is accelerating and, without timely intervention, will reach a dangerous concentration in a short time. The second preset slope is set to 2%LEL / min to distinguish between moderately rapid leaks and acute, emergency leaks. When the concentration rise rate exceeds this value, it indicates that gas pipeline 4 has experienced serious malfunctions such as rupture or flange detachment, and the leakage is increasing exponentially. Immediate emergency shut-off of gas pipeline 4 is necessary to ensure workshop operational safety.

[0050] Understandably, when the concentration of combustible gas reaches 10% LEL and the rate of increase is less than 0.5% LEL / min, only the exhaust mechanism is activated; when the concentration reaches 25% LEL, or when the concentration reaches 10% LEL and the rate of increase exceeds 0.5% LEL / min, the main shut-off valve 2 is pre-closed and synchronously inertized with the explosion-proof mechanism 3; when the concentration reaches 50% LEL, or the rate of increase at any concentration exceeds 2% LEL / min, the gas transmission pipeline 4 is immediately completely shut off. Compared with the prior art, this invention, through such precise parameter matching, can effectively avoid misjudgments caused by instantaneous concentration fluctuations and environmental interference, and can make differentiated responses to leaks with different rates of development. Under the premise of ensuring safety, it minimizes unnecessary production interruptions and further improves the operational reliability and practicality of the device.

[0051] Example 4:

[0052] This embodiment, based on embodiment 3, further refines and limits the opening adjustment module of controller 1 and the dynamic adjustment logic of the pre-closing opening, achieving precise matching between the pre-closing opening of the main shut-off valve 2 and the flammable gas leakage rate, further improving the control accuracy and adaptability of graded intervention. Specifically, as follows... Figure 1 As shown, the controller 1 also includes an opening adjustment module, which is used to dynamically adjust the pre-closing opening of the main shut-off valve 2 according to the real-time concentration rise rate: when the concentration rise rate is less than 0.5%LEL / min, the pre-closing opening is set to 40%-50%; when the concentration rise rate is 0.5%-2%LEL / min, the pre-closing opening is set to 20%-40%; when the concentration rise rate is greater than 2%LEL / min, the pre-closing opening is set to 10%-20%.

[0053] In this embodiment, the opening adjustment module communicates and links with the concentration change rate calculation module built into the controller 1. This allows the real-time acquisition of the combustible gas concentration rise rate collected and calculated by the detector. After comparing the rate value with a preset threshold, the module automatically matches and outputs the corresponding pre-closing opening control command, requiring no manual intervention throughout the process. This achieves adaptive adjustment of the leakage rate and the opening of the main shut-off valve 2. The pre-closing opening range of the main shut-off valve 2 is determined by comprehensively optimizing the leakage control requirements under different leakage rates, the pressure maintenance requirements of the gas pipeline 4, and the production gas supply guarantee requirements. This forms a precise one-to-one matching relationship with the concentration change rate threshold in Embodiment 3.

[0054] Specifically, when the concentration rise rate is less than 0.5% LEL / min, it is considered a slight, slow leak with a small leakage volume and gradual development. Setting the pre-closing opening to 40%-50% can both slightly limit the leak's spread and maintain a large flow area, ensuring stable gas flow and pressure within the gas pipeline 4 and maximizing the normal operation of downstream production equipment. Only the inert gas injection of the explosion-proof mechanism 3 is needed to eliminate the safety hazard. When the concentration rise rate is between 0.5% and 2% LEL / min, it is considered a moderately rapid leak with a gradually increasing leakage volume. Setting the pre-closing opening to 20%-40% can balance leakage control and gas supply demand, effectively curbing the expansion of leakage. At the same time, in conjunction with the closed-loop control of the pressure sensor, it can stably maintain a slightly positive pressure state in the gas pipeline 4, avoiding air backflow. When the concentration rise rate is greater than 2%LEL / min, it is considered a rapid emergency leak, and the leakage volume increases explosively. Setting the pre-closing opening to 10%-20% can quickly reduce the flow area with the minimum safe opening, cut off the leaking gas source to the maximum extent, and buy time for subsequent full closure. At the same time, it can avoid the risk of negative pressure in the gas pipeline 4 due to the opening being too small.

[0055] Understandably, this embodiment achieves graded adjustment of the pre-closing opening through the opening adjustment module, abandoning the coarse control method of fixing the pre-closing opening. It can cooperate with the pressure closed-loop control of Embodiment 2 and the threshold judgment system of Embodiment 3, so as to accurately control the amount of flammable gas leakage under different leakage levels, maintain a slight positive pressure in the gas pipeline 4 to prevent secondary explosions, minimize the impact on production continuity, and effectively improve the device's adaptability to complex leakage conditions and the reliability of safety protection.

[0056] Example 5:

[0057] This embodiment, based on embodiment 4, further refines and defines the monitoring module of controller 1 and the concentration trend monitoring and adjustment logic in the pre-shutdown state, realizing continuous tracking of leakage status and dynamic optimization of intervention strategies, further improving the device's adaptive control capability and safety protection reliability. Specifically, as Figure 1 As shown, the controller 1 also includes a monitoring module, which is used to continuously monitor the changing trend of combustible gas concentration when the main shut-off valve 2 is in the pre-closed state, so that the controller 1 can adjust the opening degree of the main shut-off valve 2.

[0058] In this embodiment, the monitoring module communicates with the detector in real time, thereby continuously collecting combustible gas concentration data and judging the concentration change trend. At the same time, the trend signal is synchronously fed back to the controller 1, so that the controller 1 can execute corresponding adjustment actions according to preset logic. That is, if the combustible gas concentration continues to decrease and falls below the warning value for a preset time, the main shut-off valve 2 is driven back to the fully open state, and the explosion-proof mechanism 3 is closed to avoid continuous intervention affecting production. If the combustible gas concentration rises slowly, the opening of the main shut-off valve 2 is reduced to 10%-15%, and the inert gas injection flow rate of the explosion-proof mechanism 3 is increased to improve the control effect on the leakage point of the gas pipeline 4. If the combustible gas concentration rises rapidly, the main shut-off valve 2 is immediately driven to adjust to the fully closed state to quickly cut off the gas source and eliminate safety risks. It is evident that this embodiment can achieve full-process tracking of the concentration trend of the main shut-off valve 2 in the pre-closed state through the monitoring module, and can make differentiated handling for three different leakage states. It can also form a complete closed-loop control of the main shut-off valve 2 with the pressure sensor, the graded threshold of the multi-level concentration threshold module and the opening adjustment module, thereby significantly improving the intelligence level and safety protection reliability of the present invention.

[0059] Example 6:

[0060] This embodiment, based on any of the above embodiments, further refines and defines the specific structure of the explosion-proof mechanism 3, clarifies the precise control method of the inert gas injection, and further improves the reliability and stability of the inertization protection inside the gas pipeline 4. Specifically, as follows... Figure 1As shown, the explosion-proof mechanism 3 includes a gas tank 5, a solenoid valve 6, a pressure reducing valve 7, and a nozzle 8. The solenoid valve 6 and the pressure reducing valve 7 are connected in series on the pipeline between the gas tank 5 and the nozzle 8. The gas tank 5 is equipped with a monitoring sensor for real-time monitoring of the internal pressure of the gas tank 5. The monitoring sensor, the solenoid valve 6, and the pressure reducing valve 7 are all connected to the controller 1.

[0061] In this embodiment, when the controller 1 determines that the leakage risk has reached the intervention level and activates the explosion-proof mechanism 3, it first sends an opening signal to the solenoid valve 6. The solenoid valve 6 quickly opens, connecting the gas tank 5 and the nozzle 8. At this time, the high-pressure inert gas in the gas tank 5 is adjusted to a preset injection pressure of 0.05MPa by the pressure reducing valve 7 and then evenly injected into the gas pipeline 4 through the nozzle 8. Furthermore, during the operation of the explosion-proof mechanism 3, the monitoring sensor continuously monitors the internal pressure of the gas tank 5. When the pressure of the gas tank 5 is detected to be lower than 0.2MPa, the controller 1 immediately issues a low-pressure alarm signal, thereby reminding the staff to replace the gas tank 5 in time to avoid inerting protection failure due to insufficient inert gas. At the same time, when the controller 1 needs to strengthen the inerting effect based on the slow increase in concentration signal fed back by the monitoring module, it can send an adjustment command to the pressure reducing valve 7 to increase the injection pressure to 0.1MPa-0.15MPa, increasing the injection flow rate of the inert gas and further improving the inerting speed and effect inside the gas pipeline 4.

[0062] A method for detecting and interlocking the protection against combustible chemical gases, using the combustible chemical gas detection and interlocking protection device as described above, includes the following steps:

[0063] S1: The concentration of combustible gas around the gas pipeline 4 is collected in real time by the detector, and the gauge pressure inside the gas pipeline 4 is collected in real time by the pressure sensor. The controller 1 calculates the real-time concentration change rate.

[0064] S2: Controller 1 compares the real-time concentration with multi-level concentration thresholds and combines the concentration change rate to generate a risk level judgment result of early warning level, intervention level or danger level;

[0065] S3: Controller 1 executes corresponding linkage control actions according to the risk level: When the risk level is the warning level, the exhaust mechanism is activated; when the risk level is the intervention level, a pre-action signal is output to drive the main shut-off valve 2 to adjust to the pre-closed state, and at the same time, the explosion-proof mechanism 3 is activated to inject inert gas into the gas pipeline 4, and the controller 1 adjusts the opening of the main shut-off valve 2 according to the gauge pressure data fed back by the pressure sensor, so that the gauge pressure in the gas pipeline 4 is maintained at 0.01MPa-0.05MPa; when the risk level is the danger level, a full-close signal is output to drive the main shut-off valve 2 from the pre-closed state to the full-closed state, and at the same time, the emergency linkage of the entire system is activated.

[0066] S4: When the main shut-off valve 2 is in the pre-closed state, the controller 1 continuously monitors the trend of combustible gas concentration change. If the concentration continues to decrease and falls below the warning value for a preset time, the controller 1 drives the main shut-off valve 2 to return to the fully open state and closes the explosion-proof mechanism 3. If the concentration continues to rise slowly, the controller 1 further reduces the opening of the main shut-off valve 2 and increases the inert gas injection flow rate of the explosion-proof mechanism 3 through the opening adjustment module. If the concentration continues to rise rapidly, the controller 1 immediately drives the main shut-off valve 2 to adjust to the fully closed state.

[0067] S5: When the controller 1 drives the main shut-off valve 2 into the pre-closed state or the fully closed state, the controller 1 synchronously sends a corresponding level of linkage signal to the chemical production process control system to trigger the chemical production process control system to perform the matching process adjustment operation.

[0068] Using this method, such as Figure 1 and Figure 2 As shown, by using a two-dimensional coupled determination of combustible gas concentration and concentration rise rate, the shortcomings of traditional single-threshold determination, such as easy false alarms and response lag, are overcome, achieving advanced prediction and precise graded response to leakage risks. Under intervention-level risks, the main shut-off valve 2 is pre-closed in conjunction with the explosion-proof mechanism 3 for inertization, and combined with dynamic pressure closed-loop adjustment to maintain a slight positive pressure in the gas pipeline 4. This effectively limits the expansion of leakage and completely blocks the risk of secondary explosion caused by backflow of air, avoiding unplanned complete shutdown in the event of minor leakage and ensuring the continuity of workshop production. At the same time, under the pre-closed state, the concentration change trend is continuously tracked, and the valve opening and inert gas flow are adaptively adjusted to achieve dynamic optimization of the intervention strategy. Combined with deep linkage with the process control system, the production load and reaction risk are reduced from the source, and the optimal balance between explosion-proof safety and continuous and stable production operation can be achieved.

[0069] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A linkage cut-off protection device for detecting combustible chemical gases, characterized in that, The system includes a controller (1) and at least one detector, a main shut-off valve (2), an exhaust mechanism, and an explosion-proof mechanism (3) that are communicatively connected to the controller (1). The controller (1) has a built-in multi-level concentration threshold module, a concentration change rate calculation module, and a linkage control module. The detector is used to collect the concentration of combustible gas around the gas pipeline (4) in real time. The main shut-off valve (2) is installed on the gas pipeline (4) and its opening degree can be continuously adjusted. The explosion-proof mechanism (3) is used to inject inert gas into the gas pipeline (4). The controller (1) is configured to activate the exhaust mechanism when the concentration of combustible gas reaches the warning value and the rate of increase of concentration is lower than the first preset slope; when the concentration of combustible gas reaches the intervention value, or the concentration reaches the warning value and the rate of increase of concentration exceeds the first preset slope, output a pre-action signal to drive the main shut-off valve (2) to adjust to the pre-closed state, and simultaneously activate the explosion-proof mechanism (3) to inject inert gas into the gas transmission pipeline (4); when the concentration of combustible gas reaches the danger value, or the rate of increase of concentration at any concentration exceeds the second preset slope, output a full-close signal to drive the main shut-off valve (2) to adjust from the pre-closed state to the full-closed state.

2. The linkage cut-off protection device for detecting combustible chemical gases according to claim 1, characterized in that, It also includes a pressure sensor, which is installed in the gas pipeline (4) upstream of the main shut-off valve (2). The opening degree of the main shut-off valve (2) in the pre-closed state is 10%-50%. In the pre-closed state, the pressure sensor monitors the internal gauge pressure of the gas pipeline (4) in real time and feeds it back to the controller (1). The controller (1) synchronously adjusts the opening degree of the main shut-off valve (2) so that the gauge pressure in the gas pipeline (4) is maintained at 0.01MPa-0.05MPa.

3. The linkage cut-off protection device for detecting combustible chemical gases according to claim 2, characterized in that, The multi-level concentration threshold module has built-in warning values, intervention values, and danger values, which correspond to 10%, 25%, and 50% of the standard lower explosive limit concentration of combustible gas, respectively; the first preset slope is 0.5%LEL / min, and the second preset slope is 2%LEL / min.

4. The linkage cut-off protection device for detecting combustible chemical gases according to claim 3, characterized in that, The controller (1) also includes an opening adjustment module, which is used to dynamically adjust the pre-closing opening of the main shut-off valve (2) according to the real-time concentration rise rate: when the concentration rise rate is less than 0.5%LEL / min, the pre-closing opening is set to 40%-50%; when the concentration rise rate is 0.5%-2%LEL / min, the pre-closing opening is set to 20%-40%; when the concentration rise rate is greater than 2%LEL / min, the pre-closing opening is set to 10%-20%.

5. The linkage cut-off protection device for detecting combustible chemical gases according to claim 4, characterized in that, The controller (1) also includes a monitoring module, which is used to continuously monitor the changing trend of combustible gas concentration when the main shut-off valve (2) is in a pre-closed state, so that the controller (1) can adjust the opening degree of the main shut-off valve (2).

6. The linkage cut-off protection device for detecting combustible chemical gases according to any one of claims 1 to 5, characterized in that, The explosion-proof mechanism (3) includes a gas tank (5), a solenoid valve (6), a pressure reducing valve (7), and a nozzle (8). The solenoid valve (6) and the pressure reducing valve (7) are connected in series on the pipeline between the gas tank (5) and the nozzle (8). The gas tank (5) is equipped with a monitoring sensor for real-time monitoring of the internal pressure of the gas tank (5). The monitoring sensor, the solenoid valve (6), and the pressure reducing valve (7) are all communicatively connected to the controller (1).

7. A method for linkage cut-off protection of chemical combustible gas detection, comprising the linkage cut-off protection device for chemical combustible gas detection as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1: The detector collects the concentration of combustible gas around the gas pipeline (4) in real time, the pressure sensor collects the gauge pressure inside the gas pipeline (4) in real time, and the controller (1) calculates the real-time concentration change rate. S2: The controller (1) compares the real-time concentration with the multi-level concentration thresholds and generates a risk level judgment result of warning level, intervention level or danger level by combining the concentration change rate; S3: The controller (1) performs corresponding linkage control actions according to the risk level: when the risk level is the warning level, the exhaust mechanism is activated; when the risk level is the intervention level, a pre-action signal is output to drive the main shut-off valve (2) to adjust to the pre-closed state, and at the same time, the explosion-proof mechanism (3) is activated to inject inert gas into the gas pipeline (4), and the controller (1) adjusts the opening of the main shut-off valve (2) according to the gauge pressure data fed back by the pressure sensor, so that the gauge pressure in the gas pipeline (4) is maintained at 0.01MPa-0.05MPa; when the risk level is the danger level, a full-close signal is output to drive the main shut-off valve (2) from the pre-closed state to the full-closed state, and at the same time, the emergency linkage of the whole system is activated. S4: When the main shut-off valve (2) is in the pre-closed state, the controller (1) continuously monitors the trend of combustible gas concentration change. If the concentration continues to decrease and falls below the warning value for a preset time, the controller drives the main shut-off valve (2) to return to the fully open state and closes the explosion-proof mechanism (3). If the concentration still rises slowly, the controller further reduces the opening of the main shut-off valve (2) and increases the inert gas injection flow rate of the explosion-proof mechanism (3) through the opening adjustment module. If the concentration still rises rapidly, the controller immediately drives the main shut-off valve (2) to adjust to the fully closed state. S5: When the controller (1) drives the main shut-off valve (2) into a pre-closed state or a fully closed state, the controller (1) synchronously sends a linkage signal of the corresponding level to the chemical production process control system to trigger the chemical production process control system to perform a matching process adjustment operation.

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