Low-concentration gas concentration allocation system and method

Abstract

The invention relates to a low-concentration gas concentration distribution system and method, and belongs to the technical field of gas concentration. Comprising a gas inlet main path used for conveying raw material gas; the concentration increasing branch is communicated with the shunting node; the main branch is communicated with the shunting node, is connected with the concentration increasing branch in parallel and is used for receiving the other part of raw material gas; an inlet of the mixing and rationing unit is connected with the concentration increasing branch and the main branch, and an outlet of the mixing and rationing unit is used for outputting mixed target gas; and the flow regulation and control mechanism is used for dynamically regulating the physical flow ratio of the main branch gas entering the mixed distribution unit to the concentrated gas according to the gas concentration parameter of the output end of the mixed distribution unit. Through cooperation of the concentration unit and the mixing and distributing unit, efficient trapping, boosting and concentration of ultralow-concentration gas are achieved.

Description

Technical Field

[0001] This invention belongs to the field of gas enrichment technology, specifically relating to a low-concentration gas enrichment and distribution system and method. Background Technology

[0002] Coal mine gas is not only a harmful gas that threatens mine safety, but also a high-quality clean energy source. For a long time, how to efficiently and safely utilize the low-concentration gas generated during the extraction process has been a key focus of coal mine energy management and carbon emission reduction efforts.

[0003] Currently, in practical engineering applications, according to GB51134-2015 "Design Code for Coal Mine Gas Power Plants", due to the limitations of existing ultra-low concentration gas enrichment technology, gas with a concentration of less than 8% often cannot be effectively utilized and is directly emitted. At the same time, because the concentration of gas extracted from mines fluctuates greatly, the utilization concentration is often at a low level, resulting in the power generation efficiency of existing generator units being maintained at only about 35%, causing serious resource misallocation.

[0004] In addition, the existing generator sets and their supporting systems have a low level of intelligence. When faced with drastic changes in core process parameters such as gas concentration and pressure, they mainly rely on manual control, resulting in obvious logical delays and action lags in the unit response. This makes it impossible to achieve dynamic and accurate distribution of gas flow and concentration, which in turn leads to low system operating efficiency and poor stability.

[0005] Furthermore, because ultra-low concentration methane of 6%-8% is not effectively extracted and blended, a large amount of methane gas is directly emitted into the atmosphere every year. This not only causes serious energy waste, but also deviates from the requirements of the national green and low-carbon goals, and puts enormous pressure on mine production. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a low-concentration gas enrichment and distribution system and method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A low-concentration gas enrichment and distribution system is provided, comprising:

[0009] An intake main is used to transport raw material gas, and the intake main has a branching node;

[0010] The concentration boosting branch is connected to the diversion node and is used to receive part of the raw material gas. The concentration boosting branch is equipped with a concentrating unit for increasing the gas concentration and a buffer unit for stabilizing the airflow pressure.

[0011] The main branch, connected to the diversion node and in parallel with the concentration boosting branch, is used to receive another portion of raw material gas;

[0012] The mixing and dispensing unit has its inlet connected to the concentration boosting branch and the main branch, respectively, and its outlet is used to output the mixed target gas.

[0013] The flow control mechanism is used to dynamically adjust the physical flow ratio of the main branch gas and the concentrated gas entering the mixing and distribution unit according to the gas concentration parameter at the output end of the mixing and distribution unit.

[0014] Preferably, the concentration unit includes a compressor and a gas separation membrane assembly arranged sequentially along the airflow direction;

[0015] The gas separation membrane assembly is used to purify a portion of the raw material gas to a methane concentration of over 30%.

[0016] Preferably, the flow control mechanism includes a first regulating valve disposed on the main branch and a second regulating valve disposed at the outlet end of the buffer unit;

[0017] The first regulating valve and the second regulating valve are linked in opening by receiving control commands to adjust the flow rate ratio entering the mixing and dispensing unit.

[0018] Preferably, the main air intake or the concentration boosting branch is provided with a raw material gas pretreatment unit, which includes a dehydrator, a filter and a dryer.

[0019] Preferably, it further includes:

[0020] Distributed sensing array;

[0021] The distributed sensing array includes concentration sensors and pressure sensors located at the front end of the diversion node, the outlet end of each branch, and the outlet end of the mixing and dispensing unit.

[0022] Preferably, the mixing and dispensing unit includes a premixing mechanism, the premixing mechanism comprising:

[0023] The outer and inner tubes are arranged in a coaxial nested configuration;

[0024] One end of the outer tube is connected to the main branch, and one end of the inner tube is connected to the concentration enhancement branch;

[0025] A diffuser head is located at the end of the inner tube extending into the outer tube. The diffuser head is in the shape of an outwardly expanding cone, and its circumferential surface is provided with a number of spiral spray holes.

[0026] The throat section is fixedly disposed on the inner wall of the outer tube and sleeved on the outside of the diffuser head; a ring negative pressure ejection channel is formed between the inner wall surface of the throat section and the conical side wall of the diffuser head.

[0027] Furthermore, the axial position of the diffuser head within the throat section is adjustable, which is used to change the cross-sectional area of ​​the negative pressure ejector channel.

[0028] Preferably, the axis of the spiral nozzle is offset at a tangential angle of 30° to 60° with the radial plane of the inner tube, and the inner wall of the spiral nozzle is provided with a spiral guide groove for inducing fluid spin.

[0029] The present invention also provides a method for concentrating and distributing low-concentration gas, comprising the following steps:

[0030] S1. Parameter Acquisition: Real-time acquisition of raw material gas concentration in the intake main and target gas concentration at the outlet of the mixing and dispensing unit;

[0031] S2. Calculate the ratio: Based on the preset value of the target gas concentration and the real-time value of the raw material gas concentration, calculate the flow ratio index of the concentrated gas and the raw material gas entering the mixing and feeding unit.

[0032] S3. Linkage Control: Based on the flow ratio index, the opening degrees of the first regulating valve and the second regulating valve are linked and adjusted;

[0033] S4. Feedback Correction: Based on the real-time detection value of the target gas concentration, dynamically compensate the opening degree of the first regulating valve and the second regulating valve.

[0034] Preferably, the step of calculating the proportions further includes:

[0035] S11. Trend prediction: Based on the concentration change curve of the intake general path within a preset historical time period, the predicted concentration value of raw material gas at future moments is calculated using a concentration prediction model.

[0036] S12. Feedforward pre-adjustment: Using the predicted concentration value as a feedforward compensation parameter, the opening step size of the first regulating valve and the second regulating valve is adjusted in advance.

[0037] Preferably, the linkage control step further includes:

[0038] S31. Pre-determine the minimum ejector pressure difference threshold ∆Pmin that enables the negative pressure ejector channel to generate stable suction under different raw material gas concentrations;

[0039] S32. Real-time acquisition of the main branch pressure P1 and the concentration boosting branch outlet pressure P2, and calculation of the current real-time pressure difference ∆P = P2 - P1;

[0040] S33. When the target gas concentration is detected to decrease, the output pressure of the enrichment unit is increased first to increase ∆P until ∆P≥∆Pmin, so as to force the gas in the main branch to participate in the mixing.

[0041] Under the premise of satisfying ∆Pmin, the weights of the two gas flow rates entering the throat section are finely adjusted by simultaneously changing the opening ratio of the first regulating valve and the second regulating valve.

[0042] S34. Based on the fluctuation frequency of the concentration at the outlet of the mixing and dispensing unit, the axial position of the diffuser head within the throat section is reversed to physically change the flow area of ​​the negative pressure ejector channel.

[0043] This invention provides a low-concentration gas enrichment and distribution system and method. The beneficial effects of this invention are as follows:

[0044] Addressing the pain point mentioned in GB51134-2015 standard that methane concentrations below 8% are often directly emitted, this invention achieves efficient capture and pressurization enrichment of ultra-low concentration methane through the synergy of an enrichment unit and a mixing and distribution unit. It enhances low-concentration methane (3%-8%), which is originally emission-grade, to a preset gain concentration of over 30%, and precisely blends it to the concentration required by the unit.

[0045] To address the issue of lag in manual control of existing systems when faced with rapid changes in pressure and concentration, this invention can identify concentration fluctuations in advance and preset valve opening, thus eliminating static deviations.

[0046] By fully capturing and controlling the blending of methane in the 6%-8% concentration range, the direct venting of methane from the mine is greatly reduced. Attached Figure Description

[0047] Figure 1 This is a front view of the low-concentration gas enrichment and distribution system proposed in this invention;

[0048] Figure 2 This is one of the structural schematic diagrams of the premixing mechanism in the low-concentration gas enrichment and distribution system proposed in this invention;

[0049] Figure 3 This is the second schematic diagram of the premixing mechanism in the low-concentration gas enrichment and distribution system proposed in this invention;

[0050] Figure 4 This is one of the flowcharts of the low-concentration gas enrichment and distribution method proposed in this invention;

[0051] Figure 5 This is the second schematic diagram of the low-concentration gas enrichment and distribution method proposed in this invention;

[0052] Figure 6 This is the third schematic diagram of the low-concentration gas enrichment and distribution method proposed in this invention.

[0053] Explanation of reference numerals in the attached figures:

[0054] 1. Main intake circuit; 2. Concentration boosting branch circuit; 3. Main branch circuit; 4. Compressor; 5. Gas separation membrane assembly; 6. First regulating valve; 7. Second regulating valve; 8. Buffer unit; 9. Dehydrator; 10. Filter; 11. Dryer; 12. Distributed sensing array; 13. Mixing and dispensing unit; 1301. Outer pipe; 1302. Inner pipe; 1303. Diffuser; 1304. Spiral nozzle; 1305. Throat constriction section. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Please see Figures 1-6 As shown, the specific embodiments provided by the present invention are as follows:

[0057] like Figure 1 As shown, an embodiment of the present invention proposes a low-concentration gas enrichment and distribution system, which includes an intake main duct 1, a concentration enhancement branch 2, a main branch 3, a mixing and distribution unit 13, and a flow control mechanism.

[0058] Specifically, intake manifold 1 serves as the gas source inlet for the entire system, responsible for conveying the raw material gas extracted from the mine. In this embodiment, the methane concentration of the raw material gas can be in the low concentration range of 3% to 10%. The system uses the enrichment unit described below to increase it to a preset target gain concentration (such as above 30% or a specific value higher than the raw material gas concentration) to meet subsequent mixing requirements. A diversion node is provided at the end of intake manifold 1, which divides the raw material gas flow channel into two parallel parts.

[0059] The concentration boosting branch 2 is connected to the diversion node and is used to receive and process a portion of the raw material gas. A concentration unit is installed on this branch to increase the methane concentration in the gas to a preset usable level. To ensure stable pressure in subsequent feeding processes, a buffer unit 8 is further installed on the concentration boosting branch 2 to absorb process fluctuations and stabilize the gas flow pressure on the output side. The buffer unit 8 is specifically a pressure stabilizing tank with a preset volume, which is equipped with a pressure relief valve to counteract pressure pulsations generated by the preceding process.

[0060] Among them, the main branch 3 is also connected to the diversion node and maintains a parallel relationship with the concentration enhancement branch 2, which is used to directly receive and transport another part of raw material gas that has not been concentrated.

[0061] The mixing and distribution unit 13 serves as the core of the system's component convergence, with its inlet connected to the concentration enhancement branch 2 and the main branch 3, respectively. The enhanced high-concentration gas and the original concentration gas are spatially mixed within the mixing and distribution unit 13, and finally, the mixed target gas with a concentration that meets the power generation requirements is output through the outlet.

[0062] The flow control mechanism dynamically adjusts the physical flow ratio between the main branch gas and the enriched gas entering the mixing and distribution unit 13 by monitoring the gas concentration parameter at the output of the mixing and distribution unit 13 in real time. When the gas source concentration fluctuates, the flow control mechanism can automatically increase or decrease the inflow ratio of the two gas streams, thereby ensuring that the target gas concentration at output remains constant.

[0063] In a preferred embodiment, the concentration unit includes a compressor 4 and a gas separation membrane assembly 5 arranged sequentially along the airflow direction. The compressor 4 serves as a power source, responsible for pressurizing the low-pressure raw material gas from the concentration enhancement branch 2, providing the pressure head required to overcome separation resistance.

[0064] The pressurized gas stream enters the gas separation membrane module 5, which utilizes the difference in permeation rates of different gas components in the membrane material to achieve concentration. The gas separation membrane module 5 is used to efficiently separate a portion of the received raw gas and purify its methane concentration to over 30%, thereby providing a high-quality, enhanced gas source for subsequent mixing with the gas from the main branch 3. The gas separation membrane module 5 adopts a single-stage or multi-stage series structure, dynamically adjusting the osmotic pressure difference according to the inlet gas concentration to ensure that the methane concentration enriched on the stagnant side stably reaches the utilization threshold.

[0065] In one specific embodiment, the gas separation membrane module 5 is composed of a membrane core consisting of multiple sets of hollow fiber membrane filaments with high permeability selectivity and a pressure-bearing outer shell. During actual operation, the raw material gas, pressurized by the pre-compressor 4, enters the pressure chamber of the membrane module. Utilizing the physical difference in the permeation rates of methane molecules with nitrogen and oxygen molecules in the membrane material, efficient component separation is achieved.

[0066] Specifically, the gas separation membrane module 5 can selectively intercept methane molecules and enrich them on the stagnation side of the membrane, thereby purifying some of the raw material gas to a methane concentration of over 30%. This enrichment process not only provides the necessary high-concentration gas source for subsequent blending, but also ensures good component stability of the output gas flow through the physical characteristics of membrane separation technology, laying a technological foundation for the continuous and reliable operation of the entire distribution system.

[0067] In a preferred embodiment, the flow control mechanism includes a first regulating valve 6 disposed on the main branch 3 and a second regulating valve 7 disposed at the outlet end of the buffer unit 8.

[0068] The first regulating valve 6 directly controls the flow rate of the raw gas with the original concentration entering the mixing and dispensing unit 13, while the second regulating valve 7 is deployed at the end of the concentration process to accurately control the flow rate of the high-concentration gas after purification and pressure stabilization.

[0069] During system operation, the first regulating valve 6 and the second regulating valve 7 are linked in opening by receiving control commands. Specifically, based on the deviation between the target concentration and the real-time gas source concentration, they output complementary opening commands through the controller, thereby adjusting the flow rate ratio entering the mixing and dispensing unit 13. Both the first regulating valve 6 and the second regulating valve 7 are intelligent electric regulating valves or pneumatic regulating valves with positioners to ensure that the response time meets the requirements of dynamic system adjustment.

[0070] By linking the real-time positions of the first regulating valve 6 and the second regulating valve 7, the system can dynamically compensate for the mixing weight of enriched gas and raw gas according to the fluctuation of raw material gas concentration, ensuring that the final output target gas is always maintained within the preset process index range.

[0071] In a preferred embodiment, the main air intake duct 1 or the concentration enhancement branch 2 is provided with a raw material gas pretreatment unit to ensure the reliability of subsequent concentration and mixing processes.

[0072] Specifically, the raw gas pretreatment unit includes a dehydrator 9, a filter 10, and a dryer 11. Specifically, the dehydrator 9 is used to remove condensate and saturated water vapor from the raw gas to prevent moisture from causing physical damage or performance degradation to the subsequent gas separation membrane assembly 5; the filter 10 is used to intercept solid particulate impurities such as coal dust and dirt in the gas flow to ensure the cleanliness of the gas flow.

[0073] Through the synergistic effect of the dehydrator 9, filter 10 and dryer 11, the raw gas pretreatment unit provides the entire system with a controlled gas source that is physically stable and has clean components, effectively extending the service life of key core components and improving the overall dispensing accuracy of the system.

[0074] In a preferred embodiment, a distributed sensing array 12 is also included to enable full-process status monitoring and data feedback.

[0075] Specifically, the distributed sensing array 12 includes concentration sensors and pressure sensors located at the front end of the diversion node, the outlet ends of each branch, and the outlet end of the mixing and dispensing unit 13. Each sensor in the distributed sensing array 12 is electrically connected to the central controller via an industrial bus, forming a multi-loop closed-loop feedback system.

[0076] Specifically, the sensor located at the front end of the diversion node is used to monitor the original quality of the raw material gas in real time; the sensor located at the outlet of concentration boosting branch 2 and the outlet of main branch 3 is used to monitor the physical state of each branch before entering the mixing process; and the sensor located at the outlet of mixing and dispensing unit 13 is used to finally verify the dispensing accuracy of the target gas.

[0077] By coordinating the concentration and pressure sensors at multiple points in the distributed sensing array 12, the system can build a comprehensive sensing network from source to end, providing accurate decision-making basis for the flow control mechanism, thereby ensuring that the output concentration remains constant even when the gas source parameters fluctuate.

[0078] like Figure 2 and Figure 3 As shown, in a preferred embodiment, the mixing and dispensing unit 13 includes a premixing mechanism.

[0079] Specifically, it includes an outer pipe 1301 and an inner pipe 1302 arranged coaxially and nested. One end of the outer pipe 1301 is connected to the main branch 3 and is responsible for introducing low-pressure raw material gas; one end of the inner pipe 1302 is connected to the concentration enhancement branch 2 and is responsible for introducing concentrated high-pressure gas.

[0080] A diffuser head 1303 is provided at the end of the inner tube 1302 extending into the outer tube 1301. The diffuser head 1303 is in the shape of an outwardly expanding cone, and its circumferential surface is provided with a plurality of spiral nozzles 1304. This cone-shaped expansion structure, in conjunction with the spiral nozzles 1304, can convert the high-pressure enriched gas discharged from the inner tube 1302 into a high-speed rotating vortex, thereby enhancing the shear force with the airflow in the outer tube 1301.

[0081] Correspondingly, a throat section 1305 is fixedly provided on the inner wall of the outer tube 1301, and the throat section 1305 is sleeved on the outside of the diffuser head 1303. An annular negative pressure ejection channel is formed between the inner wall surface of the throat section 1305 and the conical sidewall of the diffuser head 1303. When high-pressure gas is ejected through the diffuser head 1303, a local negative pressure zone is generated in this annular channel, thereby actively entraining low-pressure raw material gas in the outer tube 1301 into the mixing zone, effectively solving the pressure difference shielding problem when high and low pressure airflows converge.

[0082] Furthermore, the axial position of the diffuser head 1303 within the throat section 1305 is adjustable. By adjusting the axial extension / retraction position of the diffuser head 1303, the flow cross-sectional area of ​​the negative pressure ejector channel can be dynamically changed. This allows the system to physically adjust the ejection intensity and mixing space according to real-time flow requirements, thereby achieving rapid compensation and suppression of concentration fluctuations at the mechanical structure level.

[0083] In a preferred embodiment, the axis of the spiral nozzle 1304 is offset tangentially by 30° to 60° from the radial plane of the inner tube 1302. This specific tangential angle allows the high-pressure enriched gas discharged from the inner tube 1302 to generate a strong circumferential tangential velocity when entering the mixing space, thereby forming a high-speed rotating vortex field within the throat section 1305.

[0084] Furthermore, the inner wall of the spiral nozzle 1304 is provided with a spiral guide groove for inducing fluid spin. When the high-pressure gas flow passes through the spiral guide groove, the turbulence intensity and spin momentum of the gas flow are significantly enhanced under the forced guidance of the groove line. Through the synergistic effect of the tangential offset angle and the spiral guide groove, the high-pressure enriched gas can penetrate and entrain the low-pressure raw material gas in the outer pipe 1301 with extremely high spiral kinetic energy, which greatly enhances the molecular diffusion and collision frequency of the two gas flows at the microscopic level, thereby effectively solving the problems of uneven mixing and component stratification in the low-concentration gas blending process.

[0085] In a preferred embodiment, the mixing and dispensing unit 13 includes a mixing mechanism connected to the premixing mechanism for receiving the premixed gas. The mixing mechanism is a static mixer with cross-arranged helical blades or corrugated packing material fixed inside. By repeatedly cutting, splitting, and radially mixing the premixed gas flow, it ensures that the final output gas composition meets the homogenization requirements.

[0086] like Figure 4 and Figure 6 As shown, in an embodiment of the present invention, a method for concentrating and distributing low-concentration gas is also provided, specifically including the following steps:

[0087] S1. Parameter Acquisition: After the system starts, the physical parameters of key nodes are collected in real time through the distributed sensing array 12.

[0088] Specifically, the initial methane concentration of the raw material gas is obtained by a concentration sensor located at the front end of the intake manifold 1, and the real-time monitoring value of the target gas concentration at the outlet of the mixing and feeding unit 13 is simultaneously acquired. This basic data provides a real-time and accurate input source for subsequent logical judgments.

[0089] S2. Calculation of the ratio: After receiving the collected parameters, the central controller calculates the required flow ratio of concentrated gas to raw gas entering the mixing and distribution unit 13 based on the preset target gas concentration standard (e.g., the stable intake gas concentration value required by the generator set) and the real-time fluctuation of the raw material gas concentration, using an internally preset material balance algorithm. This ratio establishes the ideal mass distribution relationship between the high-concentration branch and the low-concentration branch in the mixing space.

[0090] The material balance algorithm is implemented based on the following logic:

[0091] Ctarget∙(Q1+Q2)=Craw∙Q1+Crich∙Q2;

[0092] Wherein, Ctarget is the preset value of the target gas concentration, Craw is the real-time value of the raw material gas concentration of the intake main 1, and Crich is the real-time value of the concentrated gas concentration at the outlet of the concentration boosting branch 2; Q1 is the flow rate index of the main branch 3 entering the mixing and dispensing unit 13 through the first regulating valve 6, and Q2 is the flow rate index of the concentrated gas entering the mixing and dispensing unit 13 through the second regulating valve 7.

[0093] Specifically, the central controller, based on real-time collected Craw and Crich data and combined with preset total output demand or pressure balance requirements, solves the aforementioned set of equations to determine the target ratio of Q1 to Q2. This flow ratio indicator is then converted into preset opening commands for the first regulating valve 6 and the second regulating valve 7, realizing a quantitative mapping from concentration demand to the action of the physical actuators.

[0094] S3. Interlocking Control: Based on the calculated flow ratio, the system sends a synchronous control command to the flow control mechanism, interlocking the openings of the first regulating valve 6 on the main branch 3 and the second regulating valve 7 at the end of the concentration boosting branch 2. During this process, the first regulating valve 6 and the second regulating valve 7 employ a complementary interlocking control logic; that is, when the raw material gas concentration decreases, the opening of the second regulating valve 7 is increased while the opening of the first regulating valve 6 is correspondingly decreased to rapidly increase the methane content in the mixture.

[0095] S4. Feedback Correction: To eliminate static deviations caused by pipeline transmission delays or fluctuations in concentration efficiency, the system introduces a closed-loop feedback mechanism based on the real-time detection value of the target gas concentration at the outlet of the mixing and dispensing unit 13. Through PID control algorithms or fuzzy control strategies, the current opening degrees of the first regulating valve 6 and the second regulating valve 7 are fine-tuned and dynamically compensated in real time to ensure that the final output target gas concentration remains stable within a very small deviation range from the preset value.

[0096] In a preferred embodiment, the step of calculating the proportioning ratio further includes a trend prediction step S11 and a feedforward pre-adjustment step S12 before the calculation step, in order to eliminate the lag effect in the physical transportation process:

[0097] Specifically, S11. Trend Prediction: The system constructs a real-time concentration change curve based on the raw material gas concentration data collected by the distributed sensing array 12 within a preset historical time period (e.g., the past 30-60 seconds). Using a concentration prediction model (specifically, a first-order linear extrapolation algorithm, an autoregressive moving average model ARMA, or a preset concentration gradient change rate identification logic), the system calculates the predicted raw material gas concentration value at the future prediction time (corresponding to the physical transmission time required for gas to flow from the main line through the enrichment branch to the mixing point).

[0098] Specifically, S12. Feedforward Pre-adjustment: The system uses the calculated predicted concentration value as a feedforward compensation parameter to retrieve the corresponding valve control command in advance. Specifically, before the real-time concentration fluctuates significantly, the controller adjusts the opening step size of the first regulating valve 6 and the second regulating valve 7 in advance according to the trend of the predicted concentration value (rising or falling). This feedforward control logic enables the flow control mechanism to act before the concentration fluctuation arrives, thereby offsetting the physical time delay caused by the enrichment process unit and pipeline transmission, and effectively suppressing the concentration oscillation of the target gas at the output end.

[0099] It should be noted that a feedforward-feedback composite control module is installed inside the controller. The feedforward pre-adjustment command generated in steps S11 and S12 serves as a coarse adjustment term, used to quickly respond to trend fluctuations in the inlet concentration; the feedback correction command generated in step S4 serves as a fine adjustment term, used to eliminate residual deviations in the system. When the directions of the two commands conflict, the system prioritizes the feedforward pre-adjustment to prevent significant deviations, and sets an integral saturation limit for the feedback loop to prevent actuator oscillations caused by control redundancy.

[0100] In a preferred embodiment, the linkage control step further includes a differential pressure compensation and structural correction process based on the negative pressure ejection principle, specifically including the following steps:

[0101] S31. Pre-determination:

[0102] During the system commissioning phase, the minimum ejector pressure difference threshold ∆Pmin required to generate stable and continuous entrainment force in the negative pressure ejector channel under different raw material gas concentrations and flow rates was pre-determined. This threshold establishes the physical critical point at which high-pressure enriched gas can effectively eject low-pressure raw material gas, and is stored in the central controller's database as a benchmark reference.

[0103] S32. Real-time acquisition:

[0104] The distributed sensing array 12 acquires the inlet pressure P1 of the main branch 3 and the outlet pressure P2 of the concentration boosting branch 2 in real time, and the controller calculates the real-time pressure difference ∆P = P2 - P1 at the current confluence point of the two airflows. This step enables online monitoring of the dynamic state of the flow field at the inlet of the mixing and dispensing unit 13.

[0105] S33. Forced Ejection and Weight Fine-tuning:

[0106] When the target gas concentration is detected to decrease and fall below a preset threshold, the system prioritizes increasing the output power of compressor 4 in the enrichment unit to increase the outlet pressure P2 of the concentration enhancement branch 2, thereby actively increasing the real-time pressure difference ∆P until ∆P ≥ ∆Pmin is satisfied. By maintaining this physical pressure difference, the local negative pressure generated by the Venturi effect is used to forcibly increase and entrain the raw material gas of the main branch 3 to participate in the mixing, completely eliminating the shielding obstruction of the high-pressure side to the low-pressure side. Under the physical premise of satisfying ∆Pmin, the system simultaneously adjusts the flow weight of the two types of gas entering the throat section 1305 by changing the opening ratio of the first regulating valve 6 and the second regulating valve 7, based on the existing stable ejector flow field.

[0107] S34. Physical Space Correction:

[0108] The system further performs structural compensation based on the fluctuation frequency (i.e., oscillation intensity) of the concentration at the outlet of the mixing and dispensing unit 13. If the output concentration fluctuation frequency exceeds a set threshold, it indicates that the turbulent mixing intensity and flow rate within the current flow field are mismatched. At this time, the controller issues a command to drive the axial drive mechanism (e.g., an electric push rod, connected to the throat section 1305 or the diffuser head 1303) to correct the axial position of the diffuser head 1303 within the throat section 1305. By physically changing the cross-sectional area of ​​the negative pressure ejector channel, the fluid resistance and ejection intensity of the mixing space are redefined at the mechanical structure level, thereby fundamentally suppressing concentration oscillations and achieving real-time coupling between hardware structural parameters and software control logic.

[0109] Of course, in order to ensure operational reliability in a dusty and humid gas environment, the connection between the inner tube 1302 and the outer tube 1301 is provided with a double dynamic sealing assembly (such as a polytetrafluoroethylene sealing ring in conjunction with a stuffing box), and the axial drive mechanism is sealed inside an explosion-proof housing.

[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-concentration gas enrichment and distribution system, characterized in that, include: An intake main is used to transport raw material gas, and the intake main has a branching node; The concentration boosting branch is connected to the diversion node and is used to receive part of the raw material gas. The concentration boosting branch is equipped with a concentrating unit for increasing the gas concentration and a buffer unit for stabilizing the airflow pressure. The main branch, connected to the diversion node and in parallel with the concentration boosting branch, is used to receive another portion of raw material gas; The mixing and dispensing unit has its inlet connected to the concentration boosting branch and the main branch, respectively, and its outlet is used to output the mixed target gas. The flow control mechanism is used to dynamically adjust the physical flow ratio of the main branch gas and the concentrated gas entering the mixing and distribution unit according to the gas concentration parameter at the output end of the mixing and distribution unit.

2. The low-concentration gas enrichment and distribution system according to claim 1, characterized in that, The concentration unit includes a compressor and a gas separation membrane assembly arranged sequentially along the airflow direction; The gas separation membrane assembly is used to purify a portion of the raw material gas to a methane concentration of over 30%.

3. The low-concentration gas enrichment and distribution system according to claim 1, characterized in that, The flow control mechanism includes a first regulating valve located on the main branch and a second regulating valve located at the outlet end of the buffer unit. The first regulating valve and the second regulating valve are linked in opening by receiving control commands to adjust the flow rate ratio entering the mixing and dispensing unit.

4. The low-concentration gas enrichment and distribution system according to claim 1, characterized in that, The main air intake or the concentration boosting branch is equipped with a raw material gas pretreatment unit, which includes a dehydrator, a filter, and a dryer.

5. The low-concentration gas enrichment and distribution system according to claim 1, characterized in that, Also includes: Distributed sensing array; The distributed sensing array includes concentration sensors and pressure sensors located at the front end of the diversion node, the outlet end of each branch, and the outlet end of the mixing and dispensing unit.

6. The low-concentration gas enrichment and distribution system according to claim 1, characterized in that, The mixing and dispensing unit includes a premixing mechanism, which includes: The outer and inner tubes are arranged in a coaxial nested configuration; One end of the outer tube is connected to the main branch, and one end of the inner tube is connected to the concentration enhancement branch; A diffuser head is located at the end of the inner tube extending into the outer tube. The diffuser head is in the shape of an outwardly expanding cone, and its circumferential surface is provided with a number of spiral spray holes. The throat section is fixedly disposed on the inner wall of the outer tube and sleeved on the outside of the diffuser head; a ring negative pressure ejection channel is formed between the inner wall surface of the throat section and the conical side wall of the diffuser head. Furthermore, the axial position of the diffuser head within the throat section is adjustable, which is used to change the cross-sectional area of ​​the negative pressure ejector channel.

7. The low-concentration gas enrichment and distribution system according to claim 6, characterized in that, The axis of the spiral nozzle is offset at a tangential angle of 30° to 60° with the radial plane of the inner tube, and the inner wall of the spiral nozzle is provided with a spiral guide groove for inducing fluid spin.

8. A method for concentrating and distributing low-concentration gas based on the system described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Parameter Acquisition: Real-time acquisition of raw material gas concentration in the intake main and target gas concentration at the outlet of the mixing and dispensing unit; S2. Calculate the ratio: Based on the preset value of the target gas concentration and the real-time value of the raw material gas concentration, calculate the flow ratio index of the concentrated gas and the raw material gas entering the mixing and feeding unit. S3. Linkage Control: Based on the flow ratio index, the opening degrees of the first regulating valve and the second regulating valve are linked and adjusted; S4. Feedback Correction: Based on the real-time detection value of the target gas concentration, dynamically compensate the opening degree of the first regulating valve and the second regulating valve.

9. The method for concentrating and distributing low-concentration gas according to claim 8, characterized in that, The following steps are included before the calculation of the proportions: S11. Trend prediction: Based on the concentration change curve of the intake general path within a preset historical time period, the predicted concentration value of raw material gas at future moments is calculated using a concentration prediction model. S12. Feedforward pre-adjustment: Using the predicted concentration value as a feedforward compensation parameter, the opening step size of the first regulating valve and the second regulating valve is adjusted in advance.

10. The method for concentrating and distributing low-concentration gas according to claim 9, characterized in that, The coordinated control steps also include: S31. Pre-determine the minimum ejector pressure difference threshold ∆Pmin that enables the negative pressure ejector channel to generate stable suction under different raw material gas concentrations; S32. Real-time acquisition of the main branch pressure P1 and the concentration boosting branch outlet pressure P2, and calculation of the current real-time pressure difference ∆P = P2 - P1; S33. When the target gas concentration is detected to decrease, the output pressure of the enrichment unit is increased first to increase ∆P until ∆P≥∆Pmin, so as to force the gas in the main branch to participate in the mixing. Under the premise of satisfying ∆Pmin, the weights of the two gas flow rates entering the throat section are finely adjusted by simultaneously changing the opening ratio of the first regulating valve and the second regulating valve. S34. Based on the fluctuation frequency of the concentration at the outlet of the mixing and dispensing unit, the axial position of the diffuser head within the throat section is reversed to physically change the flow area of ​​the negative pressure ejector channel.

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