A high-precision servo-flow natural gas and hydrogen blending device and blending method

Abstract

This invention discloses a high-precision, flow-controlled natural gas-hydrogen blending device and method belonging to the field of clean energy safety applications. The natural gas-hydrogen blending device includes a natural gas pipeline, a hydrogen pipeline, a mixing pipeline, and a PLC control system. The natural gas and hydrogen pipelines are connected to a static mixer in the mixing pipeline. The PLC control system uses hydrogen component concentration signals measured at different cross-sectional positions or different depths of the same cross-section in the mixing pipeline to control the opening of the flow regulating valve in the hydrogen pipeline to respond in real time to changes in the natural gas pipeline flow rate. This allows for proportional adjustment of the hydrogen pipeline flow rate based on the natural gas pipeline flow rate, maintaining a fixed hydrogen blending ratio in real time with high precision. This invention offers higher blending precision and better uniformity, providing equipment and technical support for hydrogen-blended natural gas pipeline transportation.

Description

Technical Field

[0001] This invention belongs to the field of clean energy safety applications, and specifically relates to a high-precision follow-up flow natural gas and hydrogen blending device and blending method. Background Technology

[0002] With the rapid development of the global green and low-carbon economy, clean energy is receiving increasing attention. Hydrogen energy possesses significant advantages such as being clean and carbon-free, green and efficient, renewable, and having diverse application modes. Actively and orderly developing hydrogen energy is an important measure to achieve my country's "dual-carbon" goals. The entire hydrogen energy industry chain includes hydrogen production, storage, transportation, and utilization. Among these, hydrogen transportation connects upstream hydrogen production and storage with downstream end-users, making it a crucial link. Therefore, large-scale, long-distance, and low-cost hydrogen transportation is a critical issue that the hydrogen energy industry urgently needs to address. Blending a certain proportion of hydrogen into natural gas to form hydrogen-blended natural gas, and then transporting it using existing natural gas pipelines or networks, is an important way to achieve large-scale, safe, and efficient hydrogen transportation.

[0003] Typical downstream end-use applications of hydrogen-blended natural gas (hydrogen energy communities, hydrogen energy industrial parks) involve the combustion of thermal energy. To ensure combustion stability and gas safety, hydrogen and natural gas must be uniformly mixed in a set ratio in a mixing device before being introduced into the natural gas pipeline or network. Therefore, the natural gas-hydrogen blending device is a crucial process unit in the pipeline transportation of hydrogen-blended natural gas. Existing natural gas-hydrogen blending processes often employ follow-up flow mixing devices, where natural gas serves as the active gas source, and hydrogen acts as a follow-up gas source, changing in a pre-set ratio according to the changes in the active gas source, thus blending hydrogen into the natural gas at a fixed proportion. Although the follow-up flow mixing device has a good application effect in the field of gas blending such as natural gas and coal gas, there are still some shortcomings when it is used to blend natural gas and hydrogen, two gases with significant density differences: (1) The existing follow-up flow mixing device usually only measures the hydrogen component concentration on the mixed gas pipeline at a single point, and uses the hydrogen component concentration measured at a single point as a signal to correct the hydrogen flow rate, which cannot truly reflect the blending uniformity and blending accuracy of hydrogen and natural gas; (2) The flow guiding unit and the flow turbulence unit of the static mixer in the existing follow-up flow mixing device have relatively simple structures and insufficiently optimized structural parameters, and the uniform blending ability needs to be further improved.

[0004] Therefore, based on years of experience and practice in the natural gas and hydrogen pipeline transportation industry, the inventors have proposed a high-precision follow-up flow natural gas-hydrogen blending device, which can achieve high-precision and uniform blending of hydrogen into natural gas pipelines or networks, thus overcoming the shortcomings of existing technologies and devices. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision, flow-controlled natural gas-hydrogen blending device and method. The device comprises a natural gas pipeline 1, a hydrogen pipeline 2, a mixing pipeline 3, and a PLC control system 19. The PLC control system 19 is connected to the mixing pipeline 3, the natural gas pipeline 1, and the hydrogen pipeline 2. The natural gas pipeline 1 and the hydrogen pipeline 2 are connected to a static mixer 12 in the mixing pipeline 3, forming a high-precision, flow-controlled natural gas-hydrogen blending device. The PLC control system 19 acquires the hydrogen component concentration signal and the current flow rate signal of the natural gas in the mixing pipeline 3, sets the hydrogen blending ratio, performs control calculations, and outputs the control calculation results to the flow regulating valve 17 of the hydrogen pipeline 2. The opening of the flow regulating valve 17 on the hydrogen pipeline 2 is adjusted to respond in real time to changes in the flow rate of the natural gas pipeline 1, thereby achieving the purpose of adjusting the flow rate of the hydrogen pipeline 2 according to the flow rate of the natural gas pipeline 1. Regardless of changes in the flow rate of the natural gas pipeline 1, a fixed hydrogen blending ratio can always be achieved with high precision.

[0006] The natural gas pipeline 1 includes a nitrogen purge port 4, a vent valve 5, a pressure gauge 6, a ball valve 7, a filter 8, a pressure regulating valve 9, a flow meter 10, and a check valve 11. The ball valve 7, filter 8, pressure regulating valve 9, flow meter 10, and check valve 11 are connected in series on the natural gas pipeline. A nitrogen purge port 4, a vent valve 5, and a pressure gauge 6 are installed at the inlet end of the natural gas pipeline. Another vent valve 5 is installed on the natural gas pipeline between the pressure regulating valve 9 and the flow meter 10. The flow meter measures the flow rate of the natural gas pipeline and transmits the flow signal to the PLC control system. The check valve prevents backflow of natural gas in the pipeline. Depending on the source of the natural gas, a buffer tank or pressure regulating skid is installed before the natural gas pipeline 1 as a pressure stabilizing device to further stabilize the natural gas pressure, ensuring more stable flow in the natural gas pipeline 1 and helping the PLC control system 19 maintain higher hydrogen blending control accuracy.

[0007] The models and parameters of the instruments, valves and equipment on the natural gas pipeline are reasonably selected according to the pressure, flow rate and temperature range of the natural gas transported by the pipeline, and explosion-proof requirements are taken into account; and a backup method of one in use and one in standby is adopted to ensure that the pipeline can still operate normally when a natural gas pipeline fails.

[0008] The hydrogen pipeline includes a nitrogen purge port 4, a vent valve 5, a pressure gauge 6, a first ball valve 7, a filter 8, a pressure regulating valve 9, a flow meter 16, a flow control valve 17, a shut-off valve 18, and a check valve 11. The ball valve 7, filter 8, pressure regulating valve 9, flow meter 16, flow control valve 17, second ball valve 7, shut-off valve 18, and check valve 11 are connected in series on the hydrogen pipeline. The nitrogen purge port 4, vent valve 5, and pressure gauge 6 are installed at the hydrogen inlet end of the pipeline before the first ball valve 7. The second vent valve 5 is installed between the pressure regulating valve 9 and the flow meter 16. The second ball valve 7 is connected to the shut-off valve 18. A second pressure gauge 6 is installed between points 8; flow meter 16 and flow regulating valve 17 receive flow regulation signals from PLC control system 19 via flow regulation signal transmission line 22; and adjust the valve opening according to the flow regulation signal to control the flow rate of hydrogen pipeline 2; the check valve prevents hydrogen backflow in the pipeline, ensuring safe operation of the equipment; and according to the source of hydrogen, a buffer tank or pressure regulating skid is set before hydrogen pipeline 2 as a pressure stabilizing device to further stabilize the hydrogen pressure, ensuring more stable flow in hydrogen pipeline 2, which helps PLC control system 19 maintain higher hydrogen doping control accuracy. A backup system is adopted with one operating and one standby to ensure normal operation even if one hydrogen pipeline fails.

[0009] The models and parameters of the instruments, valves and equipment on the hydrogen pipeline are reasonably selected according to the pressure, flow rate and temperature range of the hydrogen transported by the pipeline, and explosion-proof requirements are also taken into account; the pipeline steel is preferably hydrogen-resistant steel; the flow meter is preferably a hydrogen-specific flow meter; the sealing connection of the valves and instruments is preferably made of materials and processes that prevent hydrogen leakage.

[0010] The gas mixing pipeline 3 includes a static mixer 12, a differential pressure gauge 13, a drain port 14, a pressure gauge 6, a ball valve 7, a hydrogen analyzer 15, and a nitrogen purging port 4. The static mixer 12 and the ball valve 7 are connected in series on the gas mixing pipeline 3, with the pressure gauge 6 installed between them. The differential pressure gauge 13 and the drain port 14 are installed on the static mixer 12. The hydrogen analyzer 15 and the nitrogen purging port 4 are installed at the gas inlet of the gas mixing pipeline 3, and the hydrogen analyzer 15 is connected to the PLC control system 19. The hydrogen analyzer 15 can detect the concentration of hydrogen components in the gas mixing pipeline 3 online and transmit the hydrogen component concentration signal to the PLC control system 19. The static mixer 12 provides space for the efficient mixing of hydrogen and natural gas. The pressure gauge 6 can measure the pressure of the gas mixing pipeline 3. The ball valve 7 can adjust the opening of the gas mixing pipeline 3. The nitrogen purging port 4 is used to purge and replace the gas in the gas mixing pipeline 3 with nitrogen.

[0011] The static mixer includes a flow guiding unit, a flow disturbance unit, a differential pressure gauge, and a drain outlet. The flow guiding unit is optimized to fully consider the density difference and flow direction of natural gas and hydrogen. The natural gas pipeline is connected to the axial main inlet of the static mixer to ensure that natural gas enters the flow guiding unit as the active gas source, and the hydrogen pipeline is connected to the lateral inlet of the static mixer to ensure that hydrogen enters the flow guiding unit as the follower gas source. The flow guiding unit adopts a cylindrical screen structure, which is beneficial to maximally disturb the flow direction of natural gas and hydrogen to complete pre-mixing. The flow disturbance unit is preferably a combination of crossbar type, corrugated plate type, and spiral type. The number and combination of different structural types of flow disturbance units are optimized and selected according to the processing capacity and mixing uniformity requirements of the static mixer to ensure that the mixing uniformity of the static mixer is not less than 95%. Due to the optimized design of the flow guiding unit and the flow disturbance unit, the static mixer can achieve high mixing uniformity. The differential pressure gauge can display the pressure inside the static mixer; the drain port can periodically drain the static mixer.

[0012] The hydrogen analyzer can measure the hydrogen component concentration at different cross-sectional locations or at different radii of the same cross-sectional location on the gas mixing pipeline, realizing three-dimensional online detection of hydrogen component concentration at typical detection locations in the gas mixing pipeline, thereby reasonably and accurately characterizing the uniformity and precision of hydrogen and natural gas mixing.

[0013] The models and parameters of the instruments, valves and equipment on the gas mixing pipeline are reasonably selected according to the pressure, flow rate and temperature range of the hydrogen-blended natural gas transported by the pipeline, and explosion-proof requirements are also taken into account; the pipeline steel is preferably hydrogen-resistant steel; the sealing connection of the valves and instruments is preferably made of materials and processes that prevent hydrogen leakage.

[0014] The PLC control system includes hydrogen component concentration signal transmission lines, hydrogen flow rate signal transmission lines, natural gas flow rate signal transmission lines, flow regulation signal transmission lines, and a PID controller. The PID controller is divided into a primary coarse adjustment and a secondary fine adjustment. The primary coarse adjustment sets the hydrogen blending ratio based on the natural gas flow rate and coarsely adjusts the opening of the flow regulating valve on the hydrogen pipeline. The secondary fine adjustment refers to finely controlling the opening of the hydrogen flow regulating valve based on online detection information of hydrogen component concentration at different cross-sectional positions or different radii at the same cross-sectional position on the mixing pipeline. This allows for precise control of the hydrogen blending ratio and the achievement of a high-precision hydrogen blending ratio.

[0015] The natural gas pipeline, hydrogen pipeline, mixed gas pipeline, and PLC control system are installed on a mobile skid using a skid-mounted assembly method, which effectively reduces the footprint and facilitates installation and transportation.

[0016] The beneficial effects of this invention are based on a dual-feedback servo flow ratio PLC control system with "coarse adjustment + fine adjustment," overcoming the shortcomings of traditional blending methods that rely solely on single-point detection of hydrogen component concentration on the mixing pipeline, which cannot quantitatively characterize the blending uniformity and accurately represent the hydrogen blending ratio, and whose hydrogen blending precision is difficult to control precisely during feedback regulation. This invention significantly improves hydrogen blending precision. Furthermore, through optimized design of the internal flow guiding and turbulence units of the static blender, the blending efficiency and blending uniformity of the traditional static blender are further improved. This invention can achieve three-dimensional online detection of hydrogen component concentration at typical detection locations in the mixing pipeline, thereby accurately and quantitatively characterizing the blending uniformity and blending precision of hydrogen and natural gas. It can provide equipment and technical support for hydrogen-blended natural gas pipeline transportation. Attached Figure Description

[0017] Figure 1 This is a simplified flow chart of a high-precision servo-flow natural gas-hydrogen blending device;

[0018] Figure 2 This is a schematic diagram of three-dimensional online detection of hydrogen component concentration at typical detection locations in a gas mixing pipeline;

[0019] Figure 3 This is a schematic diagram of the static mixer.

[0020] Figure 4 This is the schematic diagram of a PID controller;

[0021] In the diagram: 1-Natural gas pipeline; 2-Hydrogen pipeline; 3-Mixing pipeline; 4-Safety venting system; 5-Nitrogen purging port; 6-Pressure gauge; 7-Ball valve; 8-Filter; 9-Pressure regulating valve; 10-Natural gas flow meter; 11-Check valve; 12-Static mixer; 13-Differential pressure gauge; 14-Drain valve; 15-Hydrogen analyzer; 16-Hydrogen flow meter; 17-Flow regulating valve; 18-Shut-off valve; 19-PLC control system; 20-Hydrogen component concentration signal transmission line; 21-Natural gas flow signal transmission line; 22-Hydrogen flow signal transmission line; 23-Flow regulating signal transmission line; 24-Flow guiding unit; 25-Flow turbulence unit. Detailed Implementation

[0022] This invention provides a high-precision follow-up flow natural gas and hydrogen blending device and blending method, which will be described below with reference to the accompanying drawings and embodiments.

[0023] like Figures 1-4The high-precision follow-up flow natural gas-hydrogen blending device shown includes a natural gas pipeline 1, a hydrogen pipeline 2, a mixing pipeline 3, and a PLC control system 19. The PLC control system 19 is connected to the mixing pipeline 3, the natural gas pipeline 1, and the hydrogen pipeline 2. The natural gas pipeline 1 and the hydrogen pipeline 2 are connected to the static mixer 12 in the mixing pipeline 3, forming a high-precision follow-up flow natural gas-hydrogen blending device. The PLC control system 19 collects the hydrogen component concentration signal and the current flow signal of the natural gas in the mixing pipeline 3, sets the hydrogen blending ratio, performs control calculations, and outputs the control calculation results to the flow regulating valve 17 of the hydrogen pipeline 2. The opening of the flow regulating valve 17 on the hydrogen pipeline 2 is adjusted to respond in real time to changes in the flow rate of the natural gas pipeline 1, thereby achieving the purpose of adjusting the flow rate of the hydrogen pipeline 2 according to the flow rate of the natural gas pipeline 1. Regardless of changes in the flow rate of the natural gas pipeline 1, a fixed hydrogen blending ratio can always be achieved with high precision.

[0024] like Figure 1 As shown, the natural gas pipeline 1 includes a nitrogen purging port 4, a vent valve 5, a pressure gauge 6, a ball valve 7, a filter 8, a pressure regulating valve 9, a flow meter 10, and a check valve 11. Specifically, the first ball valve 7, filter 8, pressure regulating valve 9, flow meter 10, second ball valve 7, and check valve 11 are connected in series on the natural gas pipeline. The nitrogen purging port 4, vent valve 5, and pressure gauge 6 are installed at the inlet end of the natural gas pipeline. Another vent valve 5 is installed on the natural gas pipeline between the pressure regulating valve 9 and the flow meter 10. The nitrogen purging port 4 is used to purge the natural gas pipeline 1 with nitrogen. The gas pipeline 1 is vented by the following components: a vent valve 5 for emergency venting or purging; a pressure gauge 6 for measuring the pressure of the gas pipeline 1; a ball valve 7 for adjusting the opening of the gas pipeline 1; a filter 8 for filtering impurities from the natural gas; a pressure regulating valve 9 for adjusting the pressure of the natural gas pipeline 1; a flow meter 10 for accurately measuring the flow rate of the natural gas pipeline 1 and transmitting the flow signal to the PLC control system 19 via the natural gas flow signal transmission line 21; and a check valve 11 for preventing backflow of natural gas in the natural gas pipeline 1. The models and parameters of the various instruments, valves, and equipment on the natural gas pipeline 1 are rationally selected based on the pressure, flow rate, and temperature range of the natural gas transported in the pipeline, taking explosion-proof requirements into account. Furthermore, depending on the source of the natural gas, a buffer tank or pressure regulating skid is installed before the natural gas pipeline 1 as a pressure stabilizing device to further stabilize the natural gas pressure, ensuring more stable flow in the natural gas pipeline 1 and helping the PLC control system 19 maintain higher hydrogen blending control accuracy.

[0025] The natural gas pipeline 1 can be used with the same backup, and the one-in-use and one-backup method is adopted to ensure that the embodiment of the present invention can still work normally when a natural gas pipeline fails.

[0026] like Figure 1 As shown, the hydrogen pipeline includes a nitrogen purge port 4, a vent valve 5, a pressure gauge 6, a ball valve 7, a filter 8, a pressure regulating valve 9, a flow meter 16, a flow regulating valve 17, a shut-off valve 18, and a check valve 11. The first ball valve 7, filter 8, pressure regulating valve 9, flow meter 16, flow regulating valve 17, second ball valve 7, shut-off valve 18, and check valve 11 are connected in series on the hydrogen pipeline. The nitrogen purge port 4, vent valve 5, and pressure gauge 6 are installed at the hydrogen pipeline inlet before the first ball valve 7. The second vent valve 5 is installed between the pressure regulating valve 9 and the flow meter 16. The second pressure gauge 6 is installed between the second ball valve 7 and the shut-off valve 18. The flow meter 16 and the flow regulating valve 17 receive flow regulation signals from the PLC control system 19 via the flow regulation signal transmission line 22, and adjust the valve opening according to the flow regulation signals to control the flow rate of the hydrogen pipeline 2.

[0027] The nitrogen purging port 4 is used to purge and replace the hydrogen pipeline 2 with nitrogen; the vent valve 4 can vent the hydrogen pipeline 2 in an emergency or during purging; the pressure gauge 6 can measure the pressure of the hydrogen pipeline 2; the ball valve 7 can adjust the opening of the hydrogen pipeline 2; the filter 8 can filter impurities in the hydrogen; the pressure regulating valve 9 can adjust the pressure of the hydrogen pipeline 2; the flow meter 16 can measure the flow rate of the hydrogen pipeline 2 and transmit the flow signal to the PLC control system through the hydrogen flow signal transmission line; the flow regulating valve 17 is connected to the PLC control system 19, receives the signal from the PLC control system 19 through the flow regulating signal transmission line 22, and adjusts the valve opening according to the signal to control the flow rate of the hydrogen pipeline 2; the shut-off valve 18 can shut off the hydrogen pipeline 2 in an emergency; the check valve 11 can prevent hydrogen backflow in the hydrogen pipeline 2.

[0028] The models and parameters of the instruments, valves and equipment on the hydrogen pipeline 2 are reasonably selected according to the pressure, flow rate and temperature range of the hydrogen transported by the pipeline, and explosion-proof requirements are also taken into consideration; the material of the hydrogen pipeline 2 is preferably hydrogen-resistant steel; the flow meter 16 is preferably a hydrogen-specific flow meter; the sealing connection of the valves and instruments is preferably made of materials and processes that prevent hydrogen leakage.

[0029] The hydrogen pipeline 2 can be equipped with the same backup, and the one-in-use and one-in-backup method can be used to ensure that the embodiment of the present invention can still operate normally when one hydrogen pipeline fails.

[0030] Depending on the source of the hydrogen, a buffer tank or pressure regulating skid or other pressure stabilizing device can be installed before the hydrogen pipeline 2 to further stabilize the pressure and flow of the hydrogen, ensuring a more stable flow in the hydrogen pipeline 2, which helps the PLC control system 19 maintain higher hydrogen doping control accuracy.

[0031] like Figure 1 As shown, the gas mixing pipeline 3 includes a static mixer 12, a differential pressure gauge 13, a drain port 14, a pressure gauge 6, a ball valve 7, a hydrogen analyzer 15, and a nitrogen purge port 4. The static mixer 12 and the ball valve 7 are connected in series on the gas mixing pipeline 3, with the pressure gauge 6 installed between them. The differential pressure gauge 13 and the drain port 14 are installed on the static mixer 12. The hydrogen analyzer 15 and the nitrogen purge port 4 are installed at the gas inlet of the gas mixing pipeline 3, and the hydrogen analyzer 15 is connected to the PLC control system 19. The hydrogen analyzer 15 can detect the concentration of hydrogen components in the gas mixing pipeline 3 online and transmit the hydrogen component concentration signal to the PLC control system 19. The static mixer 12 provides space for the efficient mixing of hydrogen and natural gas. The pressure gauge 6 can measure the pressure of the gas mixing pipeline 3. The ball valve 7 can adjust the opening of the gas mixing pipeline 3. The nitrogen purge port 4 is used to purge and replace the gas in the gas mixing pipeline 3 with nitrogen.

[0032] like Figure 3 As shown, the static mixer 12 includes a flow guiding unit 24, a flow disturbance unit 25, a differential pressure gauge 13, and a drain outlet 14. The structure of the flow guiding unit 24 is optimized by fully considering the density difference and flow direction of natural gas and hydrogen. The natural gas pipeline 1 is connected axially to the main inlet of the static mixer 12 to ensure that natural gas enters the static mixer as an active gas source. The hydrogen pipeline 2 is connected to the lateral inlet of the static mixer 12 to ensure that hydrogen enters the flow guiding unit 24 as a follower gas source. The flow guiding unit 24 adopts a cylindrical screen structure, which is beneficial for maximally disrupting the flow direction of natural gas and hydrogen, thus completing pre-mixing. The flow disturbance unit 25 preferably combines crossbar, corrugated plate, and spiral types. The number and combination of different structural types of flow disturbance units are optimized according to the processing capacity and mixing uniformity requirements of the static mixer 12. The concentration mixing influence factor ξ, which reflects the mixing effect of the flow disturbance unit, is calculated by the following formula.

[0033]

[0034] In the formula σ in σo ut The numbers ξ and ξ represent the mixing uniformity at the inlet and outlet of the turbulence unit, respectively. A larger ξ indicates a better mixing effect of the turbulence unit. The mixing uniformity of the static mixer 12 should be no less than 95%. The static mixer 12 achieves high mixing uniformity due to the optimized design of the flow guiding unit 24 and the turbulence unit 25. The differential pressure gauge 13 can display the pressure inside the static mixer 12. The drain port 14 can periodically drain the static mixer 12.

[0035] Preferably, the length-to-diameter ratio of the static mixer 12 can be 4:1 to 8:1.

[0036] like Figure 2 As shown, the hydrogen analyzer 15 can measure the hydrogen component concentrations c1, c2…c at different cross-sectional positions or different radii at the same cross-sectional position on the mixing pipeline 3. n This allows for online detection of hydrogen component concentration at three typical detection locations in the gas mixing pipeline, thus enabling reasonable and accurate characterization of the blending uniformity and blending precision of hydrogen and natural gas. The blending uniformity is calculated using the following formula.

[0037]

[0038] In the formula, c i These represent the hydrogen component concentration values ​​at different cross-sectional locations or at different radii of the same cross-sectional location. σ represents the average concentration of hydrogen components measured at all measurement points, where n is the number of measurement points; σ represents the mixing uniformity, where σ = 1 (100%) indicates complete mixing, and σ = 0 (0%) indicates complete separation.

[0039] The blending precision is calculated using the following formula.

[0040]

[0041] In the formula, η represents the mixing precision. The average concentration of hydrogen components measured at all measurement points is given by K, where K is the set hydrogen doping ratio.

[0042] The models and parameters of the instruments, valves and equipment on the gas mixing pipeline 3 are reasonably selected according to the pressure, flow rate and temperature range of the mixed gas transported by the pipeline, and explosion-proof requirements are also taken into account; the pipe material of the gas mixing pipeline 3 is preferably hydrogen-resistant steel; the sealing connection of the valves and instruments is preferably made of materials and processes that prevent hydrogen leakage.

[0043] like Figure 4 As shown, the PLC control system 19 includes a hydrogen component concentration signal transmission line 20, a natural gas flow signal transmission line 21, a hydrogen flow signal transmission line 22, a flow regulating valve signal transmission line 23, and a PID controller. The PID controller has two levels: a primary coarse adjustment and a secondary fine adjustment. The primary coarse adjustment refers to the PID controller coarsely adjusting the opening of the flow regulating valve 17 on the hydrogen pipeline 2 based on the natural gas flow rate and the set hydrogen blending ratio K. The secondary fine adjustment refers to finely controlling the opening of the hydrogen flow regulating valve 17 based on online detection information of hydrogen component concentration at different cross-sectional positions or different radii at the same cross-sectional position on the mixing pipeline 3. Figure 2As shown, the hydrogen component concentration information at different cross-sectional positions and at different radii of the same cross-section is transmitted to the PLC control system 19 through the hydrogen component concentration signal transmission line 22. The PLC control system 19 collects the hydrogen component concentration signal in the mixing pipeline 3, and performs PID control calculation together with the current flow signal of natural gas and the set hydrogen blending ratio K. The control calculation result is output to the flow regulating valve 17 of the hydrogen pipeline 2 through the flow regulation signal transmission line 23. The opening of the flow regulating valve 17 on the hydrogen pipeline 2 is adjusted to respond to the flow change of the natural gas pipeline 1 in real time, thereby finely controlling the hydrogen blending ratio K and obtaining a high-precision hydrogen blending ratio.

[0044] As an optional embodiment of the present invention, the natural gas pipeline 1, hydrogen pipeline 2, mixed gas pipeline 3 and PLC control system 19 are preferably installed on a mobile skid using a skid-mounted assembly method to facilitate installation and transportation.

[0045] The present invention provides a high-precision follow-up flow natural gas-hydrogen blending device, which has the following advantages compared with traditional hydrogen blending devices:

[0046] (1) Based on the “coarse adjustment + fine adjustment” dual feedback follow-up flow ratio PLC control system 19, the hydrogen doping accuracy can be improved and the relative error of the hydrogen doping ratio can be controlled within ±1%.

[0047] (2) Online detection of hydrogen component concentration at typical detection locations in the gas mixing pipeline can scientifically quantify the mixing uniformity and provide more accurate online detection information of hydrogen component concentration for the PLC control system 19.

[0048] (3) The optimized design of the internal flow guiding unit and the turbulence unit of the static mixer can achieve high mixing uniformity.

[0049] Example

[0050] The high-precision servo-flow natural gas and hydrogen blending device of the present invention includes the following steps:

[0051] Step S1, Inspection device:

[0052] Check whether the high-precision follow-up flow natural gas-hydrogen blending device is in normal working condition, including: whether the hydrogen analyzer 15 is working properly, whether the PLC control system 19 is working properly, and whether the valves and instruments on the pipeline are in the correct on / off state, etc.

[0053] Step S2, Nitrogen purging and replacement:

[0054] Nitrogen is used to purge the high-precision servo-flow natural gas-hydrogen blending device using nitrogen from nitrogen purging ports 4 on natural gas pipeline 1 and hydrogen pipeline 2. This process replaces the gas in the blending device with nitrogen, preventing residual gas from forming an explosive mixture with the hydrogen-blended natural gas and ensuring the safety of the blending device. The purged and replaced gas is discharged through vent valve 5, and nitrogen purging port 4 is closed afterward.

[0055] Step S3: Coarsely adjust the hydrogen doping ratio:

[0056] Close nitrogen purging port 4, keep safety valve 5 open, set hydrogen blending ratio K through PLC control system 19, and adjust ball valve 7 on natural gas pipeline 1 to ensure natural gas flows at a given flow rate Q. NG Stable flow;

[0057] Step S4: Determine the hydrogen flow rate

[0058] Based on the flow rate Q of natural gas pipeline 1 NG Given the hydrogen doping ratio K, determine the hydrogen flow rate Q in hydrogen pipeline 2. H2 Open the ball valve 7 of hydrogen pipeline 2, and then adjust the flow regulating valve 17 on hydrogen pipeline 2 to make the hydrogen flow rate reach Q. H2 ;

[0059] Step S5, Normal hydrogen doping condition

[0060] Maintain the natural gas and hydrogen blending state for about 2 minutes, observe whether the online detection data of the hydrogen analyzer 15 is stable, and check whether the hydrogen component concentration has reached the blending ratio. If the online detection data is relatively stable and the hydrogen component concentration has reached the blending ratio K, open the outlet ball valve 7 on the mixing pipeline and then close the vent valve; otherwise, continue to vent the blended gas until the online detection data of the hydrogen analyzer 15 is stable and the hydrogen component concentration has reached the blending ratio K; then proceed with the normal blending of natural gas and hydrogen.

[0061] Step S6: Post-processing after hydrogen doping

[0062] After the natural gas and hydrogen are blended, first close the ball valve 7 at the inlet of the natural gas pipeline 1 and the hydrogen pipeline 2, then open the vent valve 5 and close the ball valve 7 at the end of the mixing pipeline 3. Use nitrogen to purge the blending device to replace the residual hydrogen-blended natural gas in the blending device and vent it. After the gas replacement is completed, close the nitrogen purging port 4.

[0063] As can be seen from the technical solutions provided by the present invention above, the high-precision follow-up flow natural gas-hydrogen blending device provided by the embodiments of the present invention has higher blending precision and better uniformity than existing blending devices, and can provide effective equipment and technical support for the pipeline transportation of hydrogen-blended natural gas.

Claims

1. A high-precision follow-up flow natural gas and hydrogen blending device, characterized in that, The system includes a natural gas pipeline (1), a hydrogen pipeline (2), a gas mixing pipeline (3), and a PLC control system (19). The PLC control system (19) is connected to the gas mixing pipeline (3), the natural gas pipeline (1), and the hydrogen pipeline (2). The natural gas pipeline (1) and the hydrogen pipeline (2) are connected to the static mixer (12) in the gas mixing pipeline (3), forming a high-precision servo-flow natural gas-hydrogen mixing device. The PLC control system (19) collects data from the gas mixing pipeline (3). The hydrogen component concentration signal and the current flow signal of the natural gas pipeline (1) are used to set the hydrogen blending ratio and perform control calculation. The control calculation result is output to the flow regulating valve (17) of the hydrogen pipeline (2). The opening of the flow regulating valve (17) on the hydrogen pipeline (2) is adjusted to respond to the flow change of the natural gas pipeline (1) in real time, thereby achieving the purpose of adjusting the flow of the hydrogen pipeline (2) according to the flow of the natural gas pipeline (1). No matter how the flow of the natural gas pipeline (1) changes, a fixed hydrogen blending ratio is always achieved with high precision. The gas mixing pipeline (3) includes a static mixer (12), a differential pressure gauge (13), a drain outlet (14), a pressure gauge (6), a ball valve (7), a hydrogen analyzer (15), and a nitrogen purge port (4); wherein, the static mixer (12) and the ball valve (7) are connected in series on the gas mixing pipeline (3), the pressure gauge (6) is installed between the two, the differential pressure gauge (13) and the drain outlet (14) are installed on the static mixer (12), and the hydrogen analyzer (15) and the nitrogen purge port (4) are installed at the gas inlet end of the gas mixing pipeline (3), and hydrogen is separated. The analyzer (15) and the PLC control system (19) are connected; the hydrogen analyzer (15) detects the concentration of hydrogen components in the gas mixing pipeline (3) online and transmits the hydrogen component concentration signal to the PLC control system (19); the static mixer (12) provides space for the efficient mixing of hydrogen and natural gas; the pressure gauge (6) measures the pressure of the gas mixing pipeline (3); the ball valve (7) adjusts the opening of the gas mixing pipeline (3); the nitrogen purging port (4) is used to purge and replace the gas in the gas mixing pipeline (3) with nitrogen. The hydrogen analyzer (15) measures the hydrogen component concentration at different cross-sectional positions or at different radii of the same cross-sectional position on the gas mixing pipeline (3), realizing three-dimensional online detection of hydrogen component concentration at typical detection positions of the gas mixing pipeline, accurately characterizing the mixing uniformity and mixing accuracy of hydrogen and natural gas. The mixing uniformity is calculated by the following formula. ， In the formula, c i These represent the hydrogen component concentration values ​​at different cross-sectional locations or at different radii of the same cross-sectional location. This represents the average concentration of hydrogen components measured at all measurement points, where n is the number of measurement points. Indicates the uniformity of mixing. =1 indicates complete mixing. =0 indicates complete separation; The mixing precision is calculated using the following formula. ， In the formula, For mixing precision, The average concentration of hydrogen components measured at all measurement points is given by K, where K is the set hydrogen doping ratio.

2. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The natural gas pipeline (1) includes a nitrogen purge port (4), a vent valve (5), a pressure gauge (6), a ball valve (7), a filter (8), a pressure regulating valve (9), a natural gas flow meter (10), and a check valve (11); wherein, on the natural gas pipeline, the first ball valve (7), the filter (8), the pressure regulating valve (9), the natural gas flow meter (10), the ball valve (7), and the check valve (11) are connected in series; a nitrogen purge port (4), a vent valve (5), and a pressure gauge (6) are installed at the gas inlet end of the natural gas pipeline; at the pressure regulating valve (9) A vent valve (5) is installed on the natural gas pipeline between the natural gas flow meter (10); the flow meter measures the flow of the natural gas pipeline and transmits the flow signal to the PLC control system; the check valve (11) prevents the natural gas from flowing back into the pipeline; and according to the source of the natural gas, a buffer tank or pressure regulating skid is set up before the natural gas pipeline (1) as a pressure stabilizing device to further stabilize the natural gas and ensure that the flow in the natural gas pipeline (1) is more stable, which helps the PLC control system (19) to maintain higher hydrogen doping control accuracy.

3. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 2, characterized in that, The models and parameters of the instruments, valves and equipment on the natural gas pipeline are reasonably selected according to the pressure, flow rate and temperature range of the natural gas transported by the pipeline, and explosion-proof requirements are taken into account; and a backup method of one in use and one in standby is adopted to ensure that the pipeline can still operate normally when a natural gas pipeline fails.

4. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The hydrogen pipeline includes a nitrogen purge port (4), a vent valve (5), a pressure gauge (6), a ball valve (7), a filter (8), a pressure regulating valve (9), a hydrogen flow meter (16), a flow regulating valve (17), a shut-off valve (18), and a check valve (11); wherein, the first ball valve (7), filter (8), pressure regulating valve (9), hydrogen flow meter (16), flow regulating valve (17), second ball valve (7), shut-off valve (18), and check valve (11) are connected in series on the hydrogen pipeline; the nitrogen purge port (4), vent valve (5), and pressure gauge (6) are installed at the hydrogen inlet end of the pipeline before the first ball valve (7); the second vent valve (5) is installed between the pressure regulating valve (9) and the hydrogen flow meter (16); the second ball valve (7) and shut-off valve (18) are connected in series on the second ball valve (7) and the shut-off valve (11). 8) Install a second pressure gauge (6) between them; the hydrogen flow meter (16) and the flow regulating valve (17) receive the flow regulating signal input from the PLC control system (19) through the flow regulating signal transmission line (22); and regulate the opening of the valve according to the flow regulating signal to control the flow of the hydrogen pipeline (2); the check valve (11) prevents the backflow of hydrogen in the pipeline and ensures the safe operation of the equipment; and according to the source of hydrogen, a buffer tank or pressure regulating skid is set before the hydrogen pipeline (2) as a pressure stabilizing device to further stabilize the hydrogen and ensure that the flow in the hydrogen pipeline (2) is more stable, which helps the PLC control system (19) to maintain higher hydrogen doping control accuracy; and a backup method is adopted to ensure that the system can still operate normally when a hydrogen pipeline fails.

5. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 4, characterized in that, The models and parameters of the instruments, valves and equipment on the hydrogen pipeline are reasonably selected according to the pressure, flow rate and temperature range of the hydrogen transported by the pipeline, and explosion-proof requirements are also taken into account; the pipeline steel is hydrogen-resistant steel; the flow meter is a hydrogen-specific flow meter; the sealing connection of the valves and instruments is made of materials and processes to prevent hydrogen leakage.

6. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The static mixer includes a flow guiding unit, a flow disturbance unit, a differential pressure gauge, and a drain outlet. The structure of the flow guiding unit is optimized by fully considering the density difference and flow direction of natural gas and hydrogen. The natural gas pipeline (1) is connected to the axial main inlet of the static mixer to ensure that natural gas enters the flow guiding unit as an active gas source, and the hydrogen pipeline (2) is connected to the lateral inlet of the static mixer to ensure that hydrogen enters the flow guiding unit as a follower gas source. The flow guiding unit adopts a cylindrical screen structure, which is beneficial to maximally disturb the flow of natural gas and hydrogen. The flow direction is controlled to complete pre-mixing; the turbulence unit structure is a combination of crossbar type, corrugated plate type and spiral type. The number and combination of different structural types of turbulence units are optimized and selected according to the processing capacity and mixing uniformity requirements of the static mixer to ensure that the mixing uniformity of the static mixer is not less than 95%; the static mixer achieves high mixing uniformity due to the optimized design of the flow guiding unit and turbulence unit; the differential pressure gauge displays the pressure inside the static mixer; the drain port regularly drains the static mixer.

7. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The models and parameters of the instruments, valves and equipment on the gas mixing pipeline are reasonably selected according to the pressure, flow rate and temperature range of the hydrogen-blended natural gas transported by the pipeline, and explosion-proof requirements are also taken into account; the pipeline steel is hydrogen-resistant steel; the sealing connection of the valves and instruments is made of materials and processes that prevent hydrogen leakage.

8. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The PLC control system includes hydrogen component concentration signal transmission lines, hydrogen flow rate signal transmission lines, natural gas flow rate signal transmission lines, flow regulation signal transmission lines, and a PID controller. The PID controller is divided into a primary coarse adjustment and a secondary fine adjustment. The primary coarse adjustment sets the hydrogen blending ratio based on the natural gas flow rate and coarsely adjusts the opening of the flow regulating valve on the hydrogen pipeline. The secondary fine adjustment refers to finely controlling the opening of the hydrogen flow regulating valve based on online detection information of hydrogen component concentration at different cross-sectional positions or different radii at the same cross-sectional position on the mixing pipeline. This allows for precise control of the hydrogen blending ratio, achieving a high-precision blending ratio, and using a calculation formula for accurate calculation.

9. The high-precision follow-up flow natural gas and hydrogen blending device according to claim 1, characterized in that, The natural gas pipeline, hydrogen pipeline, mixed gas pipeline, and PLC control system are installed on a mobile skid using a skid-mounted assembly method, which effectively reduces the footprint and facilitates installation and transportation.

10. A method for blending natural gas and hydrogen using a high-precision servo-flow natural gas and hydrogen blending device according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1, Inspection device: Check whether the high-precision follow-up flow natural gas-hydrogen blending device is in normal working condition, including: whether the hydrogen analyzer (15) is working properly, whether the PLC control system (19) is working properly, and whether the valves and instruments on the pipeline are in the correct on / off state; Step S2, Nitrogen purging and replacement: Nitrogen is used to purge the high-precision follow-up flow natural gas-hydrogen blending device with nitrogen from the nitrogen purging port (4) of the natural gas pipeline (1) and the hydrogen pipeline (2), and the gas in the device is replaced with nitrogen to prevent the residual gas in the blending device from forming an explosive gas with the hydrogen-blended natural gas, thus ensuring the safety of the blending device. The gas after purging and replacement is discharged through the vent valve (5), and the nitrogen purging port (4) is closed after completion. Step S3: Coarsely adjust the hydrogen doping ratio: Close the nitrogen purging port (4), keep the vent valve (5) open, set the hydrogen blending ratio K through the PLC control system (19), and adjust the ball valve (7) on the natural gas pipeline (1) so that the natural gas flows at a given flow rate Q. NG Stable flow; Step S4: Determine the hydrogen flow rate According to the flow rate Q of the natural gas pipeline (1) NG Based on the hydrogen doping ratio K, determine the hydrogen flow rate Q in the hydrogen pipeline (2). H2 Open the ball valve (7) of the hydrogen pipeline (2), and then adjust the flow regulating valve (17) on the hydrogen pipeline (2) to make the hydrogen flow rate reach Q. H2 ; Step S5, Normal hydrogen doping condition Maintain the mixture of natural gas and hydrogen for 2 minutes, observe whether the online detection data of the hydrogen analyzer (15) is stable, check whether the hydrogen component concentration reaches the hydrogen blending ratio, if the online detection data is relatively stable and the hydrogen component concentration reaches the hydrogen blending ratio K, then open the outlet ball valve (7) on the mixing pipeline and then close the vent valve; otherwise, continue to vent the mixed gas until the online detection data of the hydrogen analyzer (15) is stable and the hydrogen component concentration reaches the hydrogen blending ratio K; then carry out normal mixing of natural gas and hydrogen. Step S6: Post-processing after hydrogen doping After the natural gas and hydrogen are mixed, first close the ball valve (7) at the inlet of the natural gas pipeline (1) and the hydrogen pipeline (2), then open the vent valve (5) and close the ball valve (7) at the end of the mixing pipeline (3), use nitrogen to purge the mixing device, replace the residual hydrogen-blended natural gas in the mixing device and vent it; after the gas replacement is completed, close the nitrogen purging port (4).

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