Hydrogen-doped natural gas long-distance pipeline transportation simulation system and method

Abstract

This invention provides a simulation system and method for long-distance pipeline transportation of hydrogen-blended natural gas. The system includes a gas supply system, a multi-stage pressure regulation and temperature control system, and a reinjection system. It optimizes the design of the number of pressure regulation and temperature control pipeline segments by considering the pressure difference of the throttle valve, the compression ratio of the compressor, and the pressure parameters at the start and end points of the test pipeline. Utilizing a combined process of "throttle valve + cooling / heating heat exchanger + compressor," it solves the problems of multi-stage pressure reduction, pressure increase, and temperature control in short pipelines, enabling multi-station joint operation simulation of hydrogen-blended natural gas long-distance pipelines. Hydrogen is introduced from the bottom of a static mixer, and the ultrasonic flow meter is installed at a distance of more than 200 times the pipe diameter downstream of the bottom interface of the static mixer to enhance mixing uniformity and reduce the interference of incomplete turbulence on the performance of the ultrasonic flow meter. This invention can achieve high-pressure mixing, metering, multi-stage pressure regulation, and temperature control of hydrogen-blended natural gas, providing an experimental basis for long-distance transportation simulation of hydrogen-blended natural gas at different pressures and concentrations, and for pipe material performance testing.

Description

Technical Field

[0001] This invention belongs to the field of pipeline storage and transportation technology, and in particular relates to a simulation system and method for long-distance pipeline transportation of hydrogen-blended natural gas. Background Technology

[0002] Hydrogen-blended natural gas pipeline transportation involves blending hydrogen into existing natural gas pipeline networks and continuously delivering the blended natural gas to users using existing long-distance pipelines and urban gas distribution networks. This represents a potential pathway for large-scale, efficient hydrogen energy transportation. Long-distance hydrogen-blended natural gas pipeline transportation includes processes such as gas blending, pressure regulation, and metering. The hydrogen-blended gas formed by mixing hydrogen and natural gas exhibits certain differences in physicochemical properties compared to conventional natural gas. This not only affects the operating parameters of existing pipeline equipment but can also lead to hydrogen damage to pipelines and welds. Establishing a simulation platform for long-distance hydrogen-blended natural gas pipelines to investigate the impact of hydrogen blending on pipeline transportation processes and material safety is a crucial prerequisite for supporting the design and operation management of hydrogen-blended natural gas pipeline transportation processes.

[0003] Unlike conventional techniques, the challenges of simulating long-distance pipeline transportation of hydrogen-blended natural gas include: ① The starting pressure of long-distance pipelines is high (usually around 10 MPa), and the gas temperature and pressure drop significantly after flowing for tens to hundreds of kilometers. Subsequent pipeline transportation requires multiple pressurization or heat exchange operations to meet the requirements of long-distance gas transportation. However, experimental pipelines are usually short, and the pressure and temperature drops of the experimental gas are very limited. It is necessary to solve the problems of multi-stage depressurization, pressurization, and temperature control within short pipelines. ② During the depressurization process, the mixed hydrogen gas exhibits throttling cooling or heating effects depending on the temperature, pressure, and hydrogen concentration before depressurization. Furthermore, the pressure difference before and after pressure regulation affects the temperature after pressure regulation. Therefore, when determining the number of pressure and temperature control stages for the experimental pipeline, the influence of the throttling characteristics of the mixed hydrogen gas must be considered. ③ Long-distance hydrogen mixing experiments require a large amount of experimental gas, and direct venting would lead to a significant waste of fuel gas. Using a recirculation pipeline can greatly reduce losses, but it requires reinjecting the low-pressure gas from the end of the multi-stage pressure regulation process back to the starting point of the high-pressure pipeline. If the end pressure is too low, it will increase the number of pressure regulation equipment and thus increase investment. Therefore, it is necessary to rationally optimize the number of multi-stage pressure regulation stages and the end pressure. ④ Research has found that the gas composition and flow field distribution within the mixer change depending on the location of hydrogen mixing, and the installation distance between the metering instruments and the mixer affects the mixing accuracy. When the pipeline is stopped and restarted, the metering instruments will experience measurement errors due to the stratification of the mixed hydrogen gas. Therefore, it is necessary to solve the problem of controlling gas uniformity and metering accuracy.

[0004] Domestic research on hydrogen-blended natural gas transportation is in its early stages. Patent CN115574264A discloses a multi-stage pressure natural gas pipeline hydrogen blending experimental system for medium- and low-pressure blending. This scheme blends hydrogen under medium- and low-pressure conditions (0.01–0.04 MPa), with the mixed hydrogen gas being transported from relatively low pressure to relatively high pressure. This differs significantly from the process of long-distance pipelines where hydrogen is blended under high pressure and the mixed hydrogen gas is transported from high pressure to low pressure. Patent CN113358316A uses a single-stage booster device and a water bath jacket to control pipeline pressure and temperature, which cannot simulate the combined operation of multiple booster stations in long-distance pipelines. Patents CN111992071A and CN115654374A disclose methods for controlling the uniformity and accuracy of hydrogen and natural gas blending, but do not consider the influence of the hydrogen injection position in the mixer and the installation position of metering instruments on the metering accuracy of the mixed hydrogen gas. Summary of the Invention

[0005] This invention provides a simulation system and method for long-distance pipeline transportation of hydrogen-blended natural gas, aiming to solve the current lack of simulation devices for long-distance hydrogen-blended natural gas pipelines and the problems it faces, such as multi-stage pressure and temperature control optimization, and control of hydrogen blending uniformity and metering accuracy. It provides an experimental basis for long-distance hydrogen blending simulation and pipe material performance testing. Based on this invention, high-pressure blending, metering, multi-stage pressure regulation, and temperature control of hydrogen can be realized, and it can simulate the joint operation of multiple booster stations in long-distance pipelines.

[0006] The technical solution adopted in this invention is:

[0007] A simulation system for long-distance pipeline transportation of hydrogen-blended natural gas includes a gas supply system, a multi-stage pressure regulation and temperature control system, and a reinjection system. The gas supply system includes a hydrogen supply pipeline, a natural gas supply pipeline, a nitrogen supply pipeline, and a mixed gas outlet pipeline. The main pipeline of the hydrogen supply pipeline originates from a hydrogen storage tank, passes through a first power valve, a first filter, a first temperature sensor, a first pressure sensor, a first rotor flowmeter, and a first ball valve, and then connects to the bottom interface of a first static mixer. A first branch pipeline of the hydrogen supply pipeline originates from the intermediate pipe between the first rotor flowmeter and the first ball valve. The pipeline leads out from the gas storage tank, passes through the second ball valve, and connects to the bottom interface of the second static mixer; the natural gas supply pipeline leads out from the natural gas storage tank, passes through the second power valve, the second filter, the second temperature sensor, the second pressure sensor, and the second rotor flow meter, and connects to the main fluid inlet of the first static mixer; the nitrogen supply pipeline leads out from the high-pressure nitrogen cylinder, passes through the first shut-off valve, and connects to the intermediate pipeline between the second rotor flow meter and the first static mixer; the mixed gas outlet pipeline leads out from the first static mixer, passes through the first ultrasonic flow meter and the third ball valve, and connects to the multi-stage pressure regulating and temperature control system.

[0008] The hydrogen supply pipeline of the gas supply system is connected from the bottom of the first static mixer. The hydrogen mixture is brought into a fully turbulent state by the action of gravity. The first ultrasonic flow meter is installed downstream of the first static mixer and is at a distance of more than 200D from the bottom interface of the first static mixer, where D is the inner diameter of the pipeline in which the first ultrasonic flow meter is installed.

[0009] The multi-stage pressure regulation and temperature control system consists of N-stage pressure regulation and temperature control subsystems and a tail-end subsystem. The first-stage pressure regulation and temperature control subsystem includes one main pipeline and three branch pipelines: the main pipeline of the first-stage pressure regulation and temperature control subsystem extends from the outlet of the third ball valve, and is sequentially connected to the first-stage first temperature sensor, the first-stage first pressure sensor, the first-stage first ball valve, the first-stage ultrasonic flow meter, the first-stage throttle valve, the first-stage second ball valve, the first-stage second pressure sensor, the first-stage second temperature sensor, the first-stage third ball valve, and the first-stage compressor; the first branch pipeline of the first-stage pressure regulation and temperature control subsystem extends from the pipeline between the first-stage first pressure sensor and the first-stage first ball valve. The pipeline is led out and sequentially connected to the first section fourth ball valve, the first section static mixer, and then connected to the first section first ball valve and the first section ultrasonic flow meter in the intermediate pipeline; the second branch pipeline of the first section pressure regulation and temperature control subsystem is led out from the intermediate pipeline between the first section throttle valve and the first section second ball valve, connected to the first section fifth ball valve and the first section first heat exchanger, and then connected to the intermediate pipeline between the first section second ball valve and the first section second pressure sensor; the third branch pipeline of the first section pressure regulation and temperature control subsystem is led out from the intermediate pipeline between the first section second temperature sensor and the first section third ball valve, connected to the first section sixth ball valve, the first section pipe test section, the first section seventh ball valve, and then connected to the intermediate pipeline between the first section third ball valve and the first section compressor;

[0010] The multi-stage pressure and temperature control system comprises subsystems 2 to N connected sequentially. Each subsystem has identical equipment and connections, including a main pipeline and four branch pipelines. The term "segment m" represents any one of the subsystems 2 to N. The main pipeline of the segment m originates from the compressor outlet of the previous subsystem and connects sequentially to the first temperature sensor, first pressure sensor, first ball valve, ultrasonic flow meter, throttle valve, second ball valve, second pressure sensor, second temperature sensor, third ball valve, and compressor. The first branch pipeline of the segment m originates from the intermediate pipeline between the first pressure sensor and the first ball valve, connects sequentially to the fourth ball valve and the static mixer, and then connects to the intermediate pipeline between the first ball valve and the ultrasonic flow meter. The second branch pipe of the subsystem is led out from the intermediate pipe between the m-th section throttling valve and the m-th section second ball valve, connected to the m-th section fifth ball valve and the m-th section first heat exchanger, and then connected to the intermediate pipe between the m-th section second ball valve and the m-th section second pressure sensor; the third branch pipe of the m-th section pressure regulating and temperature control subsystem is led out from the intermediate pipe between the m-th section throttling valve and the m-th section second ball valve, connected to the m-th section sixth ball valve and the m-th section second heat exchanger, and then connected to the intermediate pipe between the m-th section second ball valve and the m-th section second pressure sensor. Piping; the fourth branch pipeline of the m-th segment pressure regulation and temperature control subsystem is led out from the intermediate pipeline between the m-th segment second temperature sensor and the m-th segment third ball valve, connected to the m-th segment seventh ball valve, the m-th segment pipe test section, the m-th segment eighth ball valve, and then connected to the intermediate pipeline between the m-th segment third ball valve and the m-th segment compressor; the m-th segment ultrasonic flow meter is installed downstream of the m-th segment static mixer and maintains a distance of more than 200D from the inlet of the mixer, where D is the inner diameter of the pipeline in which the m-th segment ultrasonic flow meter is installed;

[0011] The tail section subsystem of the multi-stage pressure regulation and temperature control system includes one main pipeline and five branch pipelines. The main pipeline of the tail section subsystem is led out from the outlet of the compressor in the Nth stage pressure regulation and temperature control subsystem, and is sequentially connected to the tail section first temperature sensor, tail section first pressure sensor, tail section first ball valve, tail section ultrasonic flow meter, tail section throttle valve, tail section second ball valve, tail section second pressure sensor, tail section second temperature sensor, and tail section third ball valve. The first branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section first pressure sensor and the tail section first ball valve, passes through the tail section fourth ball valve and the tail section static mixer, and then connects to the intermediate pipeline between the tail section first ball valve and the tail section ultrasonic flow meter. The second branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section throttle valve and the tail section second ball valve. The intermediate pipeline leads out, passes through the fifth ball valve of the tail section and the first heat exchanger of the tail section, and then connects to the intermediate pipeline between the second ball valve of the tail section and the second pressure sensor of the tail section; the third branch pipeline of the tail section subsystem leads out from the intermediate pipeline between the tail section throttle valve and the second ball valve of the tail section, passes through the sixth ball valve of the tail section and the second heat exchanger of the tail section, and then connects to the intermediate pipeline between the second ball valve of the tail section and the second pressure sensor of the tail section; the fourth branch pipeline of the tail section subsystem leads out from the intermediate pipeline between the second temperature sensor of the tail section and the third ball valve of the tail section, passes through the first shut-off valve of the tail section, and then connects to the atmosphere; the fifth branch pipeline of the tail section subsystem leads out from the intermediate pipeline between the fourth branch pipeline of the tail section and the third ball valve of the tail section, passes through the seventh ball valve of the tail section, the test section of the tail section pipe, and the eighth ball valve of the tail section, and then connects to the main pipeline at the outlet of the third ball valve of the tail section.

[0012] In the multi-stage pressure regulation and temperature control system, the ultrasonic flow meter in each subsystem is installed downstream of the first static mixer in that section and is kept at a distance of more than 200D from the inlet of the mixer, where D is the inner diameter of the pipe in which the ultrasonic flow meter is installed.

[0013] The number N of the multi-stage pressure regulation and temperature control subsystem of the system is determined by optimizing the starting pressure and ending pressure of the long-distance pipeline to be simulated, the pressure difference of the throttling valve within the subsystem, and the compressor compression ratio parameters. The specific steps include:

[0014] S1. Based on experimental requirements, determine the starting pressure of the long-distance pipeline to be simulated, i.e., the inlet pressure P1 of the multi-stage pressure regulating and temperature control system pipeline, with a maximum value not exceeding 12MPa; determine the ending pressure of the long-distance pipeline to be simulated, i.e., the outlet pressure P2 of the tail section subsystem, with a minimum value not lower than the maximum value of 0.25P1 and 1.5MPa; the inlet pressure P1 of the multi-stage pressure regulating and temperature control system pipeline is the test pressure of the first pressure sensor of the first section, and the outlet pressure P2 of the tail section subsystem is the test pressure of the second pressure sensor of the tail section;

[0015] S2, select the pressure difference ΔP0 of the throttling valve within the pressure range of 2MPa to 3MPa in the pressure regulation and temperature control subsystem; select the option that meets the conditions. The compression ratio R0;

[0016] S3, take the maximum value between 2 and R0P1 / ΔP0, denoted as N. max Take no more than N max The largest integer is used as the initial value N0 for the number of pressure-regulating and temperature-controlled pipe sections;

[0017] S4, Substitute ΔP0, R0, and N0 into the constraints. If this inequality holds, then the number of segments in the pressure regulating and temperature control subsystem N = N0; if Then return to step S2, and re-execute steps S3 and S4 by increasing ΔP0 or decreasing R0 until the constraint condition is met, taking N = N0; if Then return to step S2, and re-execute steps S3 and S4 by decreasing ΔP0 or increasing R0 until the constraint condition is met, and take N = N0.

[0018] The heat exchanger of the multi-stage pressure regulation and temperature control system is characterized in that the first heat exchanger in the first stage is a cooling heat exchanger, the first heat exchanger in the m-th stage is a cooling heat exchanger, the second heat exchanger in the m-th stage is a heating heat exchanger, the first heat exchanger in the tail stage is a cooling heat exchanger, and the second heat exchanger in the tail stage is a heating heat exchanger.

[0019] The reinjection system comprises one main pipeline and four branch pipelines: the main pipeline originates from the outlet of the third ball valve at the tail end, and sequentially connects to the fourth ball valve, the first compressor, the fifth ball valve, the third pressure sensor, the third temperature sensor, the sixth ball valve, the second compressor, the seventh ball valve, the fourth pressure sensor, the fourth temperature sensor, the mixed hydrogen storage tank, the fifth temperature sensor, the fifth pressure sensor, the third filter, and the eighth ball valve, which connects to the intermediate pipeline between the third ball valve and the first temperature sensor at the head end; the first branch pipeline of the reinjection system originates from the intermediate pipeline connecting the fourth ball valve and the fifth branch of the tail end subsystem of the multi-stage pressure and temperature control system. The pipeline leads out from the ninth ball valve and connects to the intermediate pipeline between the fifth ball valve and the third pressure sensor; the second branch pipeline of the reinjection system leads out from the intermediate pipeline between the third temperature sensor and the sixth ball valve, and connects to the intermediate pipeline between the seventh ball valve and the fourth pressure sensor after passing through the tenth ball valve; the third branch pipeline of the reinjection system leads out from the top of the mixed hydrogen storage tank, and connects to the atmosphere after passing through the second shut-off valve; the fourth branch pipeline of the reinjection system leads out from the intermediate pipeline between the third filter and the eighth ball valve, and connects to the intermediate pipeline between the third ball valve and the main pipeline of the reinjection system after passing through the eleventh ball valve, the second ultrasonic flow meter, the second static mixer, and the twelfth ball valve.

[0020] This invention also provides a simulation method for long-distance pipeline transportation of hydrogen-blended natural gas, characterized by utilizing the aforementioned simulation system for long-distance pipeline transportation of hydrogen-blended natural gas; the simulation method includes the following steps:

[0021] Step 1: Preset the required hydrogen doping concentration θ and tail section subsystem outlet pressure P2 for the experiment; close the hydrogen and natural gas supply pipelines, the eighth ball valve and the eleventh ball valve, open the remaining pipeline valves of the simulation system, purge the pipelines with nitrogen using a high-pressure nitrogen cylinder, and then close all pipeline valves.

[0022] Step 2: Sequentially open the natural gas supply pipeline, the main pipeline of the hydrogen supply pipeline, all main pipelines of the multi-stage pressure regulation and temperature control system, and the fourth branch pipeline of the tail section subsystem; by adjusting the opening of the first power valve, the second power valve, and the first ball valve, change the monitored flow of the first rotor flow meter and the second rotor flow meter, so that the hydrogen concentration in the mixed gas outlet pipeline reaches the preset value.

[0023] Step 3: Open the fifth ball valve and the first heat exchanger of the first section, and close the second ball valve of the first section; starting from the second section pressure regulation and temperature control subsystem, based on the monitoring pressure P of the second pressure sensor of the m-th section. II The pipeline flow between the m-th segment throttle valve and the m-th segment second pressure sensor, which switches according to the preset hydrogen doping concentration value θ: When P II When ≥4MPa and 100%≥θ≥0%, open the fifth ball valve of section m and the first heat exchanger of section m, and close the second ball valve of section m; when 4MPa>P II When the pressure is ≥1.5MPa and the θ ≥10%, open the fifth ball valve of the m-th section and the first heat exchanger of the m-th section, and close the second ball valve of the m-th section; when 4MPa > P II When the pressure is ≥1.5MPa and 10% > θ ≥ 0%, open the sixth ball valve of the m-th section and the second heat exchanger of the m-th section, and close the second ball valve of the m-th section.

[0024] Step 4: Adjust the throttle valve opening, compressor compression ratio, and heat exchanger power on the main pipeline of the multi-stage pressure and temperature control system so that the pressure monitored by the second pressure sensor of the tail section subsystem reaches the preset value of the outlet pressure P2 of the multi-stage pressure and temperature control system pipeline, and so that the temperature monitored by the second temperature sensor of the tail section subsystem is not lower than 20℃.

[0025] Step 5, activate the pipeline circulation mode: Close the first shut-off valve at the end of the multi-stage pressure regulating and temperature control system, open the main pipeline between the fourth and seventh ball valves, adjust the compression ratios of the first and second compressors, and adjust the power of each heat exchanger in the multi-stage pressure regulating and temperature control system until the pressure monitored by the mixed hydrogen storage tank reaches the inlet pressure P1 of the multi-stage pressure regulating and temperature control system pipeline; close all pipelines of the gas supply system and open the eighth ball valve;

[0026] Step 6: Simulate the joint operation of long-distance pipelines: Simulate the pressure loss of long-distance pipelines by adjusting the throttle valve opening of the multi-stage pressure regulation and temperature control system; change the pipeline temperature conditions by adjusting the heat exchanger power of the multi-stage pressure regulation and temperature control system; change the pipeline pressure conditions by adjusting the compressor compression ratio of the multi-stage pressure regulation and temperature control system and the reinjection system; and monitor the changes in flow rate, pressure and temperature in the pipeline by using ultrasonic flow meters, pressure sensors and temperature sensors, respectively.

[0027] Step 7: Based on the pressure monitored by the second pressure sensor of each subsystem of the multi-stage pressure regulation and temperature control system, select the pipe test section that meets the pressure requirements, open the branch pipeline where the pipe test section is located, and simulate the pressure and temperature conditions of the pipe under service environment by adjusting the opening of the throttle valve and the power of the heat exchanger in the subsystem to which the test section belongs.

[0028] Step 8: Shut down the heat exchangers and compressors of the multi-stage pressure and temperature control system and the reinjection system; open the second shut-off valve to release or recycle the high-pressure gas in the pipeline; after the release or recycling is completed, open the first shut-off valve and the third ball valve, and use high-pressure nitrogen to purge the pipeline; shut down all equipment and end the simulation test.

[0029] By adopting the above technical solutions, the present invention can achieve the following beneficial effects:

[0030] (1) The range of values ​​for the inlet pressure, tail section subsystem pressure, pressure difference of the throttle valve within the section of the multi-stage pressure regulating and temperature control system, and compressor compression ratio were optimized. The above parameters were used to construct the constraint conditions for the number of pressure regulating and temperature control subsystems. Under the condition of determining the starting pressure and ending pressure of the long-distance pipeline to be simulated, the number of sections of the pressure regulating and temperature control subsystem can be easily determined, and the optimal combination of matching parameters can be obtained, providing a basis for the adjustment of the throttle valve, compressor, and heat exchanger of the pressure regulating and temperature control subsystem.

[0031] (2) Considering the temperature change characteristics of hydrogen-blended natural gas under the conditions of "pressure after throttling ≥ 4 MPa, hydrogen concentration of 0-100%", "4 MPa > pressure after throttling ≥ 1.5 MPa, hydrogen concentration of 10-100%", and "4 MPa > pressure after throttling ≥ 1.5 MPa, hydrogen concentration of 0-10%", the hydraulic and thermodynamic change law during the long-distance transportation of hydrogen-blended natural gas was simulated by using a multi-stage "throttling valve + cooling / heating heat exchanger + compressor" combination process. This solved the problems of multi-stage pressure reduction, pressure increase and temperature control in short pipelines, and realized the simulation of multi-station joint operation of hydrogen-blended natural gas long-distance pipeline.

[0032] (3) It is proposed to introduce hydrogen gas with a lower density from the bottom of the static mixer, install the ultrasonic flow meter downstream of the static mixer and keep it at a distance of more than 200D from the bottom interface of the mixer, and use the effect of gravity field to make the mixed hydrogen gas reach a fully turbulent development state, enhance the uniformity of gas mixing, and reduce the interference of the non-fully turbulent state of the fluid on the ultrasonic metering accuracy. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a simulation system for long-distance pipeline transportation of hydrogen-blended natural gas according to the present invention.

[0034] Figure 2 This is a schematic diagram of the m-th segment of the voltage regulation and temperature control subsystem of the present invention.

[0035] In the diagram: The first digit of the label number represents the specified system or pipeline: "0" represents the gas supply system; "1" represents the reinjection system; the numbers between "2" and "M" represent the pressure regulation and temperature control subsystem, where "2" represents the first stage pressure regulation and temperature control subsystem, "M" represents the m-th stage pressure regulation and temperature control subsystem, where m is an integer in the range of 2≤m≤N, "M" is a variable value m+1, and M≤8; "9" represents the tail stage subsystem of the multi-stage pressure regulation and temperature control system.

[0036] Meaning of gas supply system markings: 001-Hydrogen storage tank, 002-First power valve, 003-First filter, 004-First temperature sensor, 005-First pressure sensor, 006-First rotor flow meter, 007-First ball valve, 008-Second ball valve, 011-Natural gas storage tank, 012-Second power valve, 013-Second filter, 014-Second temperature sensor, 015-Second pressure sensor, 016-Second rotor flow meter, 021-High-pressure nitrogen cylinder, 022-First shut-off valve, 031-First static mixer, 032-First ultrasonic flow meter, 033-Third ball valve;

[0037] Meaning of the markings on the reinjection system: 101-Fourth ball valve, 102-First compressor, 103-Fifth ball valve, 104-Third pressure sensor, 105-Third temperature sensor, 106-Sixth ball valve, 107-Second compressor, 108-Seventh ball valve, 109-Fourth pressure sensor, 110-Fourth temperature sensor, 111-Mixed hydrogen storage tank, 112-Fifth temperature sensor, 113-Fifth pressure sensor, 114-Third filter, 115-Eighth ball valve, 121-Ninth ball valve, 131-Tenth ball valve, 141-Second shut-off valve, 151-Eleventh ball valve, 152-Second ultrasonic flow meter, 153-Second static mixer, 154-Twelfth ball valve;

[0038] Meaning of markings for the pressure and temperature control subsystems of a multi-stage pressure and temperature control system: 201 - First stage first temperature sensor, 202 - First stage first pressure sensor, 203 - First stage first ball valve, 204 - First stage ultrasonic flow meter, 205 - First stage throttle valve, 206 - First stage second ball valve, 207 - First stage second pressure sensor, 208 - First stage second temperature sensor, 209 - First stage third ball valve, 210 - First stage compressor, 221 - First stage fourth ball valve, 222 - First stage static mixer, 231 - First stage fifth ball valve, 232 - First stage first heat exchanger, 241 - First stage sixth ball valve, 242 - First stage pipe test section, 243 - First stage seventh ball valve; M01 - First temperature sensor of the m-th stage. Temperature sensor, M02 - first pressure sensor of section m, M03 - first ball valve of section m, M04 - ultrasonic flow meter of section m, M05 - throttle valve of section m, M06 - second ball valve of section m, M07 - second pressure sensor of section m, M08 - second temperature sensor of section m, M09 - third ball valve of section m, M10 - compressor of section m, M21 - fourth ball valve of section m, M22 - static mixer of section m, M31 - fifth ball valve of section m, M32 - first heat exchanger of section m, M41 - sixth ball valve of section m, M42 - second heat exchanger of section m, M51 - seventh ball valve of section m, M52 - pipe test section of section m, M53 - eighth ball valve of section m;

[0039] The markings on the tail section subsystems of the multi-stage pressure and temperature control system are as follows: 901 - Tail section first temperature sensor, 902 - Tail section first pressure sensor, 903 - Tail section first ball valve, 904 - Tail section ultrasonic flow meter, 905 - Tail section throttle valve, 906 - Tail section second ball valve, 907 - Tail section second pressure sensor, 908 - Tail section second temperature sensor, 909 - Tail section third ball valve, 911 - Tail section fourth ball valve, 912 - Tail section static mixer, 921 - Tail section fifth ball valve, 922 - Tail section first heat exchanger, 931 - Tail section sixth ball valve, 932 - Tail section second heat exchanger, 941 - Tail section first shut-off valve, 951 - Tail section seventh ball valve, 952 - Tail section pipe test section, 953 - Tail section eighth ball valve. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described below with reference to the accompanying drawings in this embodiment.

[0041] The terms "the" and "the" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.; the term "hydrogen concentration" refers to the molar ratio of hydrogen to natural gas; the term "downstream" indicates the position of the fluid after it flows through the outlet of a pipe or equipment in the flow direction; the terms "open" and "closed" indicate the start-up and stop actions of all types of valves, sensors, filters, flow meters, and other equipment that can be opened or closed within the object. When a pipeline is opened, it means that the equipment connected in the middle of the pipeline is in a normal working state and the fluid can flow in the pipeline; when a pipeline is closed, it means that the equipment connected in the middle of the pipeline is in a stopped working state and the fluid cannot flow in the pipeline.

[0042] As attached Figure 1 This invention provides a simulation system for long-distance pipeline transportation of hydrogen-blended natural gas, which consists of a gas supply system, a multi-stage pressure regulation and temperature control system, and a reinjection system.

[0043] The gas supply system includes a hydrogen supply pipeline, a natural gas supply pipeline, a nitrogen supply pipeline, and a mixed gas outlet pipeline: the main pipeline of the hydrogen supply pipeline is led out from the hydrogen storage tank 001, passes through the first power valve 002, the first filter 003, the first temperature sensor 004, the first pressure sensor 005, the first rotor flow meter 006, and the first ball valve 007, and then connects to the bottom interface of the first static mixer 031; the first branch pipeline of the hydrogen supply pipeline is led out from the middle pipeline between the first rotor flow meter 006 and the first ball valve 007, passes through the second ball valve 008, and then connects to the bottom interface of the second static mixer 153. The natural gas supply pipeline originates from the natural gas storage tank 011, passes through the second power valve 012, the second filter 013, the second temperature sensor 014, the second pressure sensor 015, and the second rotor flow meter 016, and then connects to the main fluid inlet of the first static mixer 031; the nitrogen supply pipeline originates from the high-pressure nitrogen cylinder 021, passes through the first shut-off valve 022, and then connects to the intermediate pipeline between the second rotor flow meter 016 and the first static mixer 031; the mixed gas outlet pipeline originates from the first static mixer 031, passes through the first ultrasonic flow meter 032 and the third ball valve 033, and then connects to the multi-stage pressure regulation and temperature control system.

[0044] The hydrogen supply pipeline of the gas supply system is connected from the bottom of the first static mixer 031. The hydrogen mixture is brought into a fully turbulent state by the action of gravity. The first ultrasonic flow meter 032 is installed downstream of the first static mixer 031 and is at a distance of more than 200D from the bottom interface of the first static mixer 031, where D is the inner diameter of the pipeline in which the first ultrasonic flow meter is installed.

[0045] The multi-stage pressure regulation and temperature control system consists of N-stage pressure regulation and temperature control subsystems and a tail-end subsystem. The first-stage pressure regulation and temperature control subsystem includes one main pipeline and three branch pipelines: the main pipeline originates from the outlet of the third ball valve 033, and is sequentially connected to the first-stage first temperature sensor 201, the first-stage first pressure sensor 202, the first-stage first ball valve 203, the first-stage ultrasonic flow meter 204, the first-stage throttle valve 205, the first-stage second ball valve 206, the first-stage second pressure sensor 207, the first-stage second temperature sensor 208, the first-stage third ball valve 209, and the first-stage compressor 210; the first branch pipeline originates from the intermediate pipeline between the first-stage first pressure sensor 202 and the first-stage first ball valve 203, and is sequentially connected to the first-stage fourth ball valve 221, the first-stage static mixer 222, and then connected to the first-stage first ball valve 210. The intermediate pipeline of the first section ultrasonic flow meter 204 is connected to the first section throttle valve 205 and the first section second ball valve 206. The second branch pipeline of the first section pressure regulating and temperature control subsystem is led out from the intermediate pipeline of the first section throttle valve 205 and the first section second ball valve 206, connected to the first section fifth ball valve 231 and the first section first heat exchanger 232, and then connected to the intermediate pipeline of the first section second ball valve 206 and the first section second pressure sensor 207. The third branch pipeline of the first section pressure regulating and temperature control subsystem is led out from the intermediate pipeline of the first section second temperature sensor 208 and the first section third ball valve 209, connected to the first section sixth ball valve 241, the first section pipe test section 242 and the first section seventh ball valve 243, and then connected to the intermediate pipeline of the first section third ball valve 209 and the first section compressor 210. The first section ultrasonic flow meter 204 is installed downstream of the first section static mixer 222 and at a distance of more than 200D from the inlet of the mixer, where D is the inner diameter of the pipeline in which the first section ultrasonic flow meter 204 is installed.

[0046] As attached Figure 1 As shown, the dashed box represents the piping of the pressure regulating and temperature control subsystem from the 2nd to the Nth segment. This piping originates from the outlet pipe of the first compressor 210 and ultimately connects to the first ball valve 903 in the tail segment. The pressure regulating and temperature control subsystems from the 2nd to the Nth segment are connected sequentially, and each segment has the same equipment and connection method, including one main pipeline and four branch pipelines. The m-th (2≤m≤N) segment represents any segment of the pressure regulating and temperature control subsystem from the 2nd to the Nth segment. A schematic diagram of this segment of the pressure regulating and temperature control subsystem is attached. Figure 2As shown; the main pipeline of the m-th segment pressure regulation and temperature control subsystem is led out from the compressor outlet of the previous segment subsystem, and is connected in sequence to the m-th segment first temperature sensor M01, m-th segment first pressure sensor M02, m-th segment first ball valve M03, m-th segment ultrasonic flow meter M04, m-th segment throttle valve M05, m-th segment second ball valve M06, m-th segment second pressure sensor M07, m-th segment second temperature sensor M08, m-th segment third ball valve M09, and m-th segment compressor M10; The first branch of the m-th segment pipeline originates from the intermediate pipeline between the first pressure sensor M02 and the first ball valve M03 of the m-th segment, and sequentially connects to the fourth ball valve M21 of the m-th segment, the static mixer M22 of the m-th segment, and then connects to the intermediate pipeline between the first ball valve M03 of the m-th segment and the ultrasonic flow meter M04 of the m-th segment; the second branch of the m-th segment pipeline originates from the intermediate pipeline between the throttle valve M05 of the m-th segment and the second ball valve M06 of the m-th segment, and connects to the fifth ball valve M31 of the m-th segment, the... The first heat exchanger M32 of section m is connected to the intermediate pipeline between the second ball valve M06 and the second pressure sensor M07 of section m; the third branch pipeline of section m originates from the intermediate pipeline between the throttle valve M05 and the second ball valve M06 of section m, connects to the sixth ball valve M41 of section m and the second heat exchanger M42 of section m, and then connects to the intermediate pipeline between the second ball valve M06 and the second pressure sensor M07 of section m; the fourth branch pipeline of section m originates from the second ball valve M06 of section m... The intermediate pipeline between temperature sensor M08 and the third ball valve M09 of the m-th section is led out, connected to the seventh ball valve M51 of the m-th section, the test section M52 of the m-th section, the eighth ball valve M53 of the m-th section, and then connected to the intermediate pipeline between the third ball valve M09 of the m-th section and the compressor M10 of the m-th section; the ultrasonic flow meter M04 of the m-th section is installed downstream of the static mixer M22 of the m-th section and maintains a distance of more than 200D from the inlet of the mixer, where D is the inner diameter of the pipeline in which the ultrasonic flow meter M04 of the m-th section is installed;

[0047] The tail section subsystem includes one main pipeline and five branch pipelines: the main pipeline of the tail section subsystem is led out from the outlet of the compressor in the Nth section pressure regulating and temperature control subsystem, and is sequentially connected to the tail section first temperature sensor 901, tail section first pressure sensor 902, tail section first ball valve 903, tail section ultrasonic flow meter 904, tail section throttle valve 905, tail section second ball valve 906, tail section second pressure sensor 907, tail section second temperature sensor 908, and tail section third ball valve 909; the tail section... The first branch pipe of the tail section subsystem is led out from the intermediate pipe between the tail section first pressure sensor 902 and the tail section first ball valve 903, passes through the tail section fourth ball valve 911 and the tail section static mixer 912, and then connects to the intermediate pipe between the tail section first ball valve 903 and the tail section ultrasonic flow meter 904; the second branch pipe of the tail section subsystem is led out from the intermediate pipe between the tail section throttle valve 905 and the tail section second ball valve 906, passes through the tail section fifth ball valve 921 and the tail section first heat exchanger 922, and then connects to the tail section second ball valve 906 and the tail section... The intermediate pipeline of the second pressure sensor 907 in the tail section; the third branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section throttle valve 905 and the tail section second ball valve 906, passes through the tail section sixth ball valve 931 and the tail section second heat exchanger 932, and then connects to the intermediate pipeline between the tail section second ball valve 906 and the tail section second pressure sensor 907; the fourth branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section second temperature sensor 908 and the tail section third ball valve 909, passes through the tail section first shut-off valve 941, and then connects to the large Air connection; the fifth branch pipeline of the tail section subsystem is led out from the middle pipeline between the fourth branch pipeline of the tail section and the third ball valve 909 of the tail section, and connects to the main pipeline at the outlet of the third ball valve 909 of the tail section after passing through the seventh ball valve 951 of the tail section, the test section 952 of the tail section pipe, and the eighth ball valve 953 of the tail section; the ultrasonic flow meter 904 of the tail section is installed downstream of the static mixer 912 of the tail section and maintains a distance of more than 200D from the inlet of the mixer, where D is the inner diameter of the pipeline in which the ultrasonic flow meter 904 of the tail section is installed;

[0048] The heat exchangers of the multi-stage pressure regulation and temperature control system are characterized in that the first heat exchanger 232 in the first stage is a cooling heat exchanger, the first heat exchanger M32 in the m-th stage is a cooling heat exchanger, the second heat exchanger M42 in the m-th stage is a heating heat exchanger, the first heat exchanger (922) in the tail stage is a cooling heat exchanger, and the second heat exchanger 932 in the tail stage is a heating heat exchanger.

[0049] The reinjection system comprises a main pipeline and four branch pipelines: the main pipeline originates from the outlet of the third ball valve 909 at the tail end, and is sequentially connected to the fourth ball valve 101, the first compressor 102, the fifth ball valve 103, the third pressure sensor 104, the third temperature sensor 105, the sixth ball valve 106, the second compressor 107, the seventh ball valve 108, the fourth pressure sensor 109, the fourth temperature sensor 110, the mixed hydrogen storage tank 111, the fifth temperature sensor 112, the fifth pressure sensor 113, the third filter 114, and the eighth ball valve 115, connecting to the intermediate pipeline between the third ball valve 033 and the first temperature sensor 201 at the beginning of the system; the first branch pipeline of the reinjection system originates from the intermediate pipeline connecting the fourth ball valve 101 and the fifth branch pipeline of the tail end subsystem. The reinjection system's second branch line originates from the intermediate pipeline between the third temperature sensor 105 and the sixth ball valve 106, passes through the tenth ball valve 131, and connects to the intermediate pipeline between the seventh ball valve 108 and the fourth pressure sensor 109. The reinjection system's third branch line originates from the top of the mixed hydrogen storage tank 111, passes through the second shut-off valve 141, and connects to the atmosphere. The reinjection system's fourth branch line originates from the intermediate pipeline between the third filter 114 and the eighth ball valve 115, passes through the eleventh ball valve 151, the second ultrasonic flow meter 152, the second static mixer 153, and the twelfth ball valve 154, and connects to the intermediate pipeline between the third ball valve 033 and the main reinjection system pipeline connection point.

[0050] Example 1

[0051] Taking a long-distance pipeline with a starting pressure of 12 MPa and a ending pressure of 3 MPa as an example, the specific steps for determining the number of segments N of the pressure regulation and temperature control subsystem in this invention are explained as follows:

[0052] S1. Based on the experimental requirements, determine the starting pressure of the long-distance pipeline to be simulated, i.e., the inlet pressure P1 of the multi-stage pressure regulation and temperature control system pipeline is 12MPa; determine the ending pressure of the long-distance pipeline to be simulated, i.e., the outlet pressure P2 of the tail section subsystem is 3MPa.

[0053] S2, within the pressure range of 2MPa to 3MPa, select a throttle valve pressure difference ΔP0 of 3MPa within the pressure regulating and temperature control subsystem; select a system that meets the following conditions. The compression ratio R0 is 1.3;

[0054] S3, take the maximum value N between 2 and R0P1 / ΔP0. max The value is 5.2; the value should not exceed N. max The largest integer is used as the initial value N0 for the number of pressure-regulating and temperature-controlled pipe sections, which is 5.

[0055] S4, Substitute ΔP0 = 3MPa, R0 = 1.3, and N0 = 5 into the constraints. because If the constraints are not met, return to steps S2, S3, and S4:

[0056] S2, within the pressure range of 2MPa to 3MPa, select a throttle valve pressure difference ΔP0 of 3MPa within the pressure regulating and temperature control subsystem; select a system that meets the following conditions. The compression ratio R0 is 1.27;

[0057] S3, take the maximum value N between 2 and R0P1 / ΔP0. max The value is 5.1; the value should not exceed N. max The largest integer is used as the initial value N0 for the number of pressure-regulating and temperature-controlled pipe sections, which is 5.

[0058] S4, substituting ΔP0 = 3MPa, R0 = 1.25, and N0 = 5 into the constraints, we have: If this inequality holds, then the number of segments in the pressure regulating and temperature control subsystem is determined to be N = 5.

[0059] Example 2 uses a simulated long-distance pipeline with an initial pressure of 7 MPa and an ending pressure of 1.75 MPa to illustrate the specific steps for determining the number of segments N in the pressure regulation and temperature control subsystem in this invention:

[0060] S1. Based on the experimental requirements, determine the starting pressure of the long-distance pipeline to be simulated, i.e., the inlet pressure P1 of the multi-stage pressure regulating and temperature control system is 7MPa; determine the ending pressure of the long-distance pipeline to be simulated, i.e., the tail section subsystem P2 of the multi-stage pressure regulating and temperature control system is 1.75MPa.

[0061] S2, within the pressure range of 2MPa to 3MPa, select a throttle valve pressure difference ΔP0 of 3MPa within the pressure regulating and temperature control subsystem; select a system that meets the following conditions. The compression ratio R0 is 1.15;

[0062] S3, take the maximum value N between 2 and R0P1 / ΔP0. max The value is 2.7; the value should not exceed N. max The largest integer is used as the initial value N0 for the number of pressure-regulating and temperature-controlled pipe sections, which is 2.

[0063] S4, Substitute ΔP0 = 3MPa, R0 = 1.15, and N0 = 2 into the constraints. because If the constraints are not met, return to steps S2, S3, and S4:

[0064] S2, within the pressure range of 2MPa to 3MPa, select a pressure difference ΔP0 of 2.8MPa for the throttle valve in the pressure regulating and temperature control subsystem section, which is smaller than 3MPa; from the range The compression ratio R0 is selected as 1.15;

[0065] S3, take the maximum value N between 2 and R0P1 / ΔP0. max The value is 2.9; the value should not exceed N. max The largest integer is used as the initial value N0 for the number of pressure-regulating and temperature-controlled pipe sections, which is 2.

[0066] S4, substituting ΔP0 = 3MPa, R0 = 1.25, and N0 = 5 into the constraints, we get: If this inequality holds, then the number of pressure regulating and temperature control subsystems is determined to be N = 2.

[0067] Through the above embodiments, it can be clearly seen that the hydrogen-blended natural gas long-distance pipeline transportation simulation system provided by the present invention has significant technical features and beneficial effects, including: the step of determining the number N of the pressure regulating and temperature control subsystem, which utilizes the inlet pressure P1 of the multi-stage pressure regulating and temperature control system pipeline, the tail section subsystem pressure P2, the pressure difference ΔP0 of the throttling valve within the pressure regulating and temperature control subsystem section, and the compressor compression ratio R0 to construct the constraint conditions for the number of pressure regulating and temperature control subsystem sections. By optimizing the range of values ​​for the above parameters, the number of segments in the pressure regulation and temperature control subsystem can be easily determined under the condition that the starting pressure P1 and the ending pressure P2 of the long-distance pipeline to be simulated are known. The optimized combination of parameters P1, P2, ΔP0, and R0 associated with these parameters can be obtained, providing a basis for the adjustment of the throttle valve, compressor, and heat exchanger in the pressure regulation and temperature control subsystem.

[0068] Example 3

[0069] This invention also provides a simulation method for long-distance pipeline transportation of hydrogen-blended natural gas, characterized by utilizing the aforementioned simulation system for long-distance pipeline transportation of hydrogen-blended natural gas; the simulation method includes the following steps:

[0070] Step 1: Preset the required hydrogen doping concentration θ and tail section subsystem outlet pressure P2; close the hydrogen and natural gas supply pipelines, the eighth ball valve 115 and the eleventh ball valve 151, open the remaining pipeline valves of the simulation system, purge the pipelines with nitrogen using the high-pressure nitrogen cylinder 021, and then close all pipeline valves.

[0071] Step 2: Sequentially open the natural gas supply pipeline, the main pipeline of the hydrogen supply pipeline, all main pipelines of the multi-stage pressure regulation and temperature control system, and the fourth branch pipeline of the tail section subsystem; by adjusting the opening of the first power valve 002, the second power valve 012 and the first ball valve 007, change the monitored flow of the first rotor flowmeter 006 and the second rotor flowmeter 016, so that the hydrogen concentration in the mixed gas outlet pipeline reaches the preset value.

[0072] Step 3: Open the fifth ball valve 231 and the first heat exchanger 232 of the first section, and close the second ball valve 206 of the first section; starting from the second section pressure regulation and temperature control subsystem, based on the monitoring pressure P of the second pressure sensor M07 of the m-th section... II The pipeline flow between the m-th segment throttle valve M05 and the m-th segment second pressure sensor M07, which switches according to the preset hydrogen doping concentration θ: When P II When ≥4MPa and 100%≥θ≥0%, open the fifth ball valve M31 of the m-th section and the first heat exchanger M32 of the m-th section, and close the second ball valve M06 of the m-th section; when 4MPa>P II When the pressure is ≥1.5MPa and the θ ≥10%, open the fifth ball valve M31 of the m-th section and the first heat exchanger M32 of the m-th section, and close the second ball valve M06 of the m-th section; when 4MPa > P II When the pressure is ≥1.5MPa and 10%>θ≥0%, open the sixth ball valve M41 of the m-th section and the second heat exchanger M42 of the m-th section, and close the second ball valve M06 of the m-th section.

[0073] Step 4: Adjust the throttle valve opening, compressor compression ratio, and heat exchanger power on the main pipeline of the multi-stage pressure and temperature control system so that the pressure monitored by the second pressure sensor 907 of the tail section subsystem reaches the preset value of the outlet pressure P2 of the multi-stage pressure and temperature control system pipeline, and so that the temperature monitored by the second temperature sensor 908 of the tail section subsystem is not lower than 20°C.

[0074] Step 5, activate the pipeline circulation mode: Close the first shut-off valve 941 at the tail end of the multi-stage pressure regulating and temperature control system, open the main pipeline between the fourth ball valve 101 and the seventh ball valve 108, adjust the compression ratio of the first compressor 102 and the second compressor 107, and adjust the power of each section of the heat exchanger in the multi-stage pressure regulating and temperature control system until the pressure monitored by the mixed hydrogen storage tank 111 reaches the inlet pressure P1 of the multi-stage pressure regulating and temperature control system pipeline; close all pipelines of the gas supply system and open the eighth ball valve 115;

[0075] Step 6: Simulate the joint operation of long-distance pipelines: Simulate the pressure loss of long-distance pipelines by adjusting the throttle valve opening of the multi-stage pressure regulation and temperature control system; change the pipeline temperature conditions by adjusting the heat exchanger power of the multi-stage pressure regulation and temperature control system; change the pipeline pressure conditions by adjusting the compressor compression ratio of the multi-stage pressure regulation and temperature control system and the reinjection system; and monitor the changes in flow rate, pressure and temperature in the pipeline by using ultrasonic flow meters, pressure sensors and temperature sensors, respectively.

[0076] Step 7: Based on the pressure monitored by the second pressure sensor of each subsystem of the multi-stage pressure regulation and temperature control system, select the pipe test section that meets the pressure requirements, open the branch pipeline where the pipe test section is located, and simulate the pressure and temperature conditions of the pipe under service environment by adjusting the opening of the throttle valve and the power of the heat exchanger in the subsystem to which the test section belongs; for example, when the first pipe test section 242 that meets the pressure requirements is selected for testing, open the third branch pipeline of the first section pressure regulation and temperature control subsystem, and simulate the pressure and temperature conditions of the pipe under service environment by adjusting the opening of the first section throttle valve 205 and the power of the heat exchanger 207.

[0077] Step 8: Shut down the heat exchangers and compressors of the multi-stage pressure regulation and temperature control system and the reinjection system; open the second shut-off valve 141 to release or recycle the high-pressure gas in the pipeline; after the release or recycling is completed, open the first shut-off valve 022 and the third ball valve 033 to purge the pipeline with high-pressure nitrogen; shut down all equipment and end the simulation test.

[0078] Through the above embodiments, it can be clearly seen that the hydrogen-blended natural gas long-distance pipeline transportation simulation system and method provided by the present invention are designed to simulate the changes in hydraulic and thermodynamic parameters during the long-distance transportation of hydrogen-blended natural gas. Its significant technical features and beneficial effects include: 1) The pressure regulating and temperature control subsystem is equipped with an in-segment throttling valve, which, by adjusting its opening, can throttle and reduce the pressure of the high-pressure hydrogen-blended natural gas, thereby simulating the pressure drop along the pipeline during long-distance transportation of hydrogen-blended natural gas; 2) The pressure regulating and temperature control subsystem has a heat exchanger installed downstream of the in-segment throttling valve, which, by adjusting its power, can change the hydrogen content. The temperature of natural gas was used to simulate the temperature drop along the pipeline during long-distance transportation of hydrogen-blended natural gas. However, because hydrogen-blended natural gas with different pressures and concentrations exhibits different thermal and cooling effects during adiabatic throttling, the gas temperature rises or falls after throttling, which does not conform to the typical temperature drop pattern along the pipeline in long-distance gas transportation. Specifically, when the pressure after throttling is ≥4 MPa and the hydrogen concentration is 0–100%, and when the pressure after throttling is >4 MPa and the pressure after throttling is ≥1.5 MPa and the hydrogen concentration is 10–100%, the temperature of the hydrogen-blended natural gas after adiabatic throttling exhibits both slight increases and decreases. Taking a typical long-distance pipeline gas inlet temperature of 20℃ as a reference, the throttling temperature is still relatively high. Therefore, a cooler is installed to lower the temperature to simulate the temperature drop along the pipeline. When "4MPa > throttling pressure ≥ 1.5MPa, hydrogen doping concentration is 0-10%", the temperature of the hydrogen-doped natural gas drops after adiabatic throttling, falling below the 20℃ reference temperature, exhibiting a throttling cooling effect. Therefore, a heating heat exchanger is used to raise the temperature of the hydrogen-doped natural gas to simulate the temperature drop along the pipeline. Based on this, the pressure regulation and temperature control subsystem, starting from the second stage, is equipped with both cooling and heating heat exchangers downstream of the throttling valve, and provides a method for controlling the temperature drop along the pipeline. The flow rate and hydrogen concentration preset values ​​are used to determine the process basis for switching the fluid to the cooling heat exchanger or the heating heat exchanger; 3) To simulate the pressurization and transportation of hydrogen-blended natural gas through an intermediate pressurization station, the pressure regulation and temperature control subsystem is also equipped with a compressor downstream of the heat exchanger. By adjusting its compression ratio, the hydrogen-blended natural gas after throttling and depressurization is pressurized again; In summary, this invention uses a multi-stage "throttling valve + cooling / heating heat exchanger + compressor" combined process to solve the multi-stage depressurization, pressurization and temperature control problems in short pipelines, realizing the simulation of multi-station joint operation of hydrogen-blended natural gas long-distance pipelines. In order to reinject the hydrogen-blended natural gas after multi-stage throttling and depressurization and temperature control back to the high-pressure starting point upstream of the experimental pipeline, the reinjection system is also equipped with a two-stage pressurization process, thereby realizing the circulation flow of high-pressure hydrogen-blended natural gas pipeline and greatly reducing experimental gas loss.

[0079] Example 4

[0080] The aforementioned simulation method for long-distance pipeline transportation of hydrogen-blended natural gas also utilizes static mixers installed in multi-stage pressure regulation and temperature control systems and reinjection systems to control the uniformity of the mixed hydrogen gas and reduce metering deviations caused by gas stratification. When the aforementioned simulation method for long-distance pipeline transportation of hydrogen-blended natural gas causes stratification of hydrogen and natural gas in the pipeline due to shutdowns, the method closes the first ball valves in each pressure regulation and temperature control subsystem section, such as 203, ..., M03, the first ball valve 903 in the tail section, and the eighth ball valve 115, and opens the fourth ball valves in each pressure regulation and temperature control subsystem section, such as 221, ..., M21, the fourth ball valve 911 in the tail section, the eleventh ball valve 151, and the twelfth ball valve 154, so that the stratified gas is fully mixed by static mixers installed in branch pipelines before entering the main pipeline.

[0081] Example 5

[0082] The aforementioned simulation method for long-distance pipeline transportation of hydrogen-blended natural gas also utilizes the first branch of the hydrogen supply pipeline and the fourth branch of the reinjection system to inject hydrogen into the circulating gas in the pipeline. This allows for continuous adjustment of the hydrogen blending concentration from low to high, facilitating experiments under multiple hydrogen blending concentrations. The specific steps for injecting hydrogen into the circulating gas in the pipeline are as follows: sequentially open the eleventh ball valve 151 and the twelfth ball valve 154, close the eighth ball valve 115, and after the reading of the second ultrasonic flowmeter 152 stabilizes, open and adjust the opening of the first power valve 002 and the second ball valve 008 until the flow ratio monitored by the first rotor flowmeter 006 and the second ultrasonic flowmeter 152 reaches the preset experimental concentration value; sequentially close the first power valve 002 and the second ball valve 008, open the eighth ball valve 115, close the eleventh ball valve 151 and the twelfth ball valve 154, and stop the hydrogen injection operation.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A simulation system for long-distance pipeline transportation of hydrogen-blended natural gas, characterized in that: This includes a gas supply system, a multi-stage pressure regulation and temperature control system, and a reinjection system; among which: The gas supply system includes hydrogen supply pipelines, natural gas supply pipelines, nitrogen supply pipelines, and a mixed gas outlet pipeline. The main pipeline of the hydrogen supply line originates from the hydrogen storage tank (001), passes through the first power valve (002), the first filter (003), the first temperature sensor (004), the first pressure sensor (005), the first rotor flowmeter (006), and the first ball valve (007), and then connects to the bottom interface of the first static mixer (031). The first branch pipeline of the hydrogen supply line originates from the intermediate pipeline between the first rotor flowmeter (006) and the first ball valve (007), passes through the third ball valve (008), and then connects to the bottom interface of the second static mixer (153). The natural gas supply line originates from the natural gas storage tank (011), passes through the second power valve (012), and the second filter (013). The system is connected to the main fluid inlet of the first static mixer (031) after the second temperature sensor (014), the second pressure sensor (015), and the second rotor flow meter (016); the nitrogen supply pipeline is led out from the high-pressure nitrogen cylinder (021), passes through the first shut-off valve (022), and is connected to the intermediate pipeline between the second rotor flow meter (016) and the first static mixer (031); the mixed gas outlet pipeline is led out from the first static mixer (031), passes through the first ultrasonic flow meter (032) and the third ball valve (033), and is connected to the multi-stage pressure regulating and temperature control system; the first ultrasonic flow meter (032) is installed downstream of the first static mixer and is 200 degrees away from the bottom interface of the first static mixer (032). D The above distances, D The inner diameter of the pipe to which the first ultrasonic flow meter (032) is installed; The multi-stage pressure regulation and temperature control system consists of N The system consists of a pressure regulating and temperature control subsystem and a tail section subsystem. The first section pressure regulating and temperature control subsystem includes a main pipeline and three branch pipelines: the main pipeline of the first section pressure regulating and temperature control subsystem is led out from the outlet of the third ball valve (033), and is connected in sequence to the first temperature sensor (201), the first pressure sensor (202), the first ball valve (203), the first ultrasonic flow meter (204), the first throttle valve (205), the first second ball valve (206), the first second pressure sensor (207), the first second temperature sensor (208), the first third ball valve (209), and the first compressor (210); the first branch pipeline of the first section pressure regulating and temperature control subsystem is led out from the intermediate pipeline between the first pressure sensor (202) and the first ball valve (203), and is connected in sequence to the first fourth ball valve (221), the first static mixer (222), and then connected to the first ball valve (210). 203) and the intermediate pipeline of the first section ultrasonic flow meter (204); the second branch pipeline of the first section pressure regulating and temperature control subsystem is led out from the intermediate pipeline of the first section throttle valve (205) and the first section second ball valve (206), connected to the first section fifth ball valve (231), the first section first heat exchanger (232), and then connected to the intermediate pipeline of the first section second ball valve (206) and the first section second pressure sensor (207); the third branch pipeline of the first section pressure regulating and temperature control subsystem The pipeline originates from the intermediate pipeline between the first-section second temperature sensor (208) and the first-section third ball valve (209), connects to the first-section sixth ball valve (241), the first-section pipe test section (242), and the first-section seventh ball valve (243), and then connects to the intermediate pipeline between the first-section third ball valve (209) and the first-section compressor (210); the first-section ultrasonic flow meter (204) is installed downstream of the first-section static mixer (222) and maintains a 200° distance from the mixer inlet. D The above distances, D The inner diameter of the pipe to which the first section of the ultrasonic flow meter (204) is installed; The multi-stage pressure regulation and temperature control system, from the second to the third stage... N The pressure regulating and temperature control subsystems are connected sequentially, and each subsystem has the same equipment and connection method, including one main pipeline and four branch pipelines: using the first m The paragraph refers to the second to the third. N Any segment of the segmented pressure regulation and temperature control subsystem; the first segment m The main pipeline of the pressure regulating and temperature control subsystem is led out from the compressor outlet of the previous subsystem, and is connected sequentially to the next subsystem. m First temperature sensor (M01), the first m First pressure sensor (M02), the first m Section 1 ball valve (M03), Section 2 ball valve (M03), Section 3 ball valve (M03) m Section ultrasonic flow meter (M04), the first m Section throttle valve (M05), the first m Section 2 ball valve (M06), the m The second pressure sensor (M07), the first m Second temperature sensor (M08), m Section 3 ball valve (M09), m The first stage compressor (M10); m The first branch pipeline of the pressure regulating and temperature control subsystem starts from the first... m The first pressure sensor (M02) and the second m The intermediate pipeline of the first ball valve (M03) is led out and connected sequentially to the... m Section 4 ball valve (M21), the m After the static mixer (M22) is connected to the first m The first ball valve (M03) and the second m The intermediate pipeline of the ultrasonic flow meter (M04); the aforementioned first... m The second branch pipeline of the pressure regulating and temperature control subsystem starts from the first... m Section throttle valve (M05) and the first m The intermediate pipeline of the second ball valve (M06) is led out and connected to the first... m Section 5 ball valve (M31), the m The first heat exchanger (M32) is connected to the second stage. m The second ball valve (M06) and the first m The intermediate pipeline of the second pressure sensor (M07); the aforementioned... m The third branch pipeline of the pressure regulating and temperature control subsystem starts from the first... m Section throttle valve (M05) and the first m The intermediate pipeline of the second ball valve (M06) is led out and connected to the first... m Section 6 ball valve (M41), the m After the second heat exchanger (M42), the first... m The second ball valve (M06) and the first m The intermediate pipeline of the second pressure sensor (M07); the aforementioned first m The fourth branch pipeline of the pressure regulating and temperature control subsystem starts from the first... m The second temperature sensor (M08) and the first m The intermediate pipeline of the third ball valve (M09) is led out and connected to the first... m Section 7 ball valve (M51), the m Section of pipe test section (M52), No. m The eighth ball valve (M53) is connected to the first... m The third ball valve (M09) and the first m The intermediate piping of the first stage compressor (M10); the aforementioned first stage compressor (M10) m The ultrasonic flow meter (M04) is installed in the first section. m Downstream of the static mixer (M22) and 200° from the mixer inlet D The above distances, D For the first m The inner diameter of the pipe to which the ultrasonic flow meter (M04) is installed; The tail section subsystem includes one main pipeline and five branch pipelines: the main pipeline of the tail section subsystem starts from the first... N The section pressure regulating and temperature control subsystem is led out from the section compressor outlet, and is sequentially connected to the following components: the first temperature sensor (901), the first pressure sensor (902), the first ball valve (903), the ultrasonic flow meter (904), the throttle valve (905), the second ball valve (906), the second pressure sensor (907), the second temperature sensor (908), and the third ball valve (909). The first branch pipeline of the tail section subsystem starts from the first pressure sensor (901). The intermediate pipeline of the tail section ball valve (902) and the tail section first ball valve (903) is led out, and after passing through the tail section fourth ball valve (911) and the tail section static mixer (912), it is connected to the intermediate pipeline of the tail section first ball valve (903) and the tail section ultrasonic flow meter (904); the second branch pipeline of the tail section subsystem is led out from the intermediate pipeline of the tail section throttle valve (905) and the tail section second ball valve (906), and after passing through the tail section fifth ball valve (921) and the tail section first heat exchanger (922), it is connected to the tail section second ball valve (906) and the tail section second... The intermediate pipeline of the pressure sensor (907); the third branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section throttle valve (905) and the tail section second ball valve (906), passes through the tail section sixth ball valve (931) and the tail section second heat exchanger (932), and then connects to the intermediate pipeline between the tail section second ball valve (906) and the tail section second pressure sensor (907); the fourth branch pipeline of the tail section subsystem is led out from the intermediate pipeline between the tail section second temperature sensor (908) and the tail section third ball valve (909), passes through The tail section is connected to the atmosphere after the first shut-off valve (941); the fifth branch pipeline of the tail section subsystem is led out from the middle pipeline between the fourth branch pipeline of the tail section subsystem and the third ball valve (909) of the tail section, and connects to the main pipeline at the outlet of the third ball valve (909) of the tail section after passing through the seventh ball valve (951), the tail section pipe test section (952), and the eighth ball valve (953); the tail section ultrasonic flow meter (904) is installed downstream of the tail section static mixer (912) and is 200 degrees away from the inlet of the mixer. D The above distances, D The inner diameter of the pipe to which the tail section ultrasonic flow meter (904) is installed; The heat exchanger of the multi-stage pressure regulating and temperature controlling system is characterized in that the first heat exchanger (232) in the first stage is a cooling heat exchanger, and the second... m The first heat exchanger (M32) is a cooling heat exchanger. m The second heat exchanger (M42) in the first section is a heating heat exchanger, the first heat exchanger (922) in the last section is a cooling heat exchanger, and the second heat exchanger (932) in the last section is a heating heat exchanger. The reinjection system comprises a main pipeline and four branch pipelines: the main pipeline of the reinjection system extends from the outlet of the third ball valve (909) at the tail end, and is sequentially connected to the fourth ball valve (101), the first compressor (102), the fifth ball valve (103), the third pressure sensor (104), the third temperature sensor (105), the sixth ball valve (106), the second compressor (107), the seventh ball valve (108), the fourth pressure sensor (109), the fourth temperature sensor (110), the mixed hydrogen storage tank (111), the fifth temperature sensor (112), the fifth pressure sensor (113), the third filter (114), and the eighth ball valve (115), connecting to the intermediate pipeline of the third ball valve (033) and the first temperature sensor (201) at the head end; the first branch pipeline of the reinjection system extends from the middle of the connection point between the fourth ball valve (101) and the fifth branch pipeline of the tail end subsystem. The intermediate pipeline leads out from the middle pipeline, passes through the ninth ball valve (121), and then connects to the intermediate pipeline between the fifth ball valve (103) and the third pressure sensor (104); the second branch pipeline of the reinjection system leads out from the intermediate pipeline between the third temperature sensor (105) and the sixth ball valve (106), passes through the tenth ball valve (131), and then connects to the intermediate pipeline between the seventh ball valve (108) and the fourth pressure sensor (109); the third branch pipeline of the reinjection system leads out from the top of the mixed hydrogen storage tank (111), passes through the second shut-off valve (141), and then connects to the atmosphere; the fourth branch pipeline of the reinjection system leads out from the intermediate pipeline between the third filter (114) and the eighth ball valve (115), passes through the eleventh ball valve (151), the second ultrasonic flow meter (152), the second static mixer (153), and the twelfth ball valve (154), and then connects to the intermediate pipeline between the third ball valve (033) and the main pipeline connection point of the reinjection system.

2. The hydrogen-blended natural gas long-distance pipeline transportation simulation system according to claim 1, characterized in that: The number of segments of the voltage regulation and temperature control subsystem N The parameters of the starting and ending pressures of the long-distance pipeline to be simulated, the differential pressure of the throttling valve within the pressure regulating and temperature control subsystem, and the compressor compression ratio are optimized and determined. The specific steps include: S1. Based on experimental requirements, determine the starting pressure of the long-distance pipeline to be simulated, i.e., the inlet pressure of the multi-stage pressure regulation and temperature control system pipeline. P 1. The maximum value should not exceed 12 MPa; determine the terminal pressure of the long-distance pipeline to be simulated, i.e., the outlet pressure of the tail section subsystem. P 2, its minimum value is not less than 0.25 P The maximum values ​​of 1 and 1.5 MPa; S2, Select the differential pressure of the throttling valve within the pressure range of 2MPa to 3MPa in the pressure regulation and temperature control subsystem. Select those that meet the conditions. Compression ratio R 0; S3, take 2 and... The maximum of the two is denoted as N max Take no more than N max The largest integer is used as the initial value for the number of sections of the pressure regulating and temperature control tube. N 0; S4, , R 0 and N Substituting 0 into the constraint conditions If this inequality holds, then the number of segments in the pressure regulating and temperature control subsystem is... N = N 0; if Then return to step S2, by increasing or reduce R After reaching 0, repeat steps S3 and S4 until the constraint condition is met, then take... N = N 0; if Then return to step S2, by reducing or increase R After reaching 0, repeat steps S3 and S4 until the constraint condition is met, then take... N = N 0.

3. A simulation method for long-distance pipeline transportation of hydrogen-blended natural gas, characterized in that... The simulation system for long-distance pipeline transportation of hydrogen-blended natural gas, as described in any one of claims 1 to 2, includes the following steps: Step 1: Preset the required hydrogen doping concentration for the experiment. θ and tail section subsystem outlet pressure P 2; Close the hydrogen and natural gas supply pipelines, the eighth ball valve (115) and the eleventh ball valve (151), open the remaining pipeline valves of the simulation system, purge the pipelines with nitrogen using the high-pressure nitrogen cylinder (021), and then close all pipeline valves; Step 2: Sequentially open the natural gas supply pipeline, the main pipeline of the hydrogen supply pipeline, all main pipelines of the multi-stage pressure regulation and temperature control system, and the fourth branch pipeline of the tail section subsystem; by adjusting the opening of the first power valve (002), the second power valve (012), and the first ball valve (007), change the monitored flow of the first rotor flowmeter (006) and the second rotor flowmeter (016) so that the hydrogen concentration in the mixed gas outlet pipeline reaches the preset value; Step 3: Open the fifth ball valve (231) and the first heat exchanger (232) of the first section, and close the second ball valve (206) of the first section; starting from the second section pressure regulation and temperature control subsystem, according to the... m The monitoring pressure of the second pressure sensor (M07) P II Compared with the preset value of hydrogen doping concentration θ Switch to the first m Section throttle valve (M05) and the first m Piping flow between the second pressure sensor (M07): When P II ≥4MPa, 100%≥ θ When ≥0%, enable the first m Section 5 ball valve (M31), the m First heat exchanger (M32), shut down the first... m Second ball valve (M06); when 4MPa > P II ≥1.5MPa, 100%≥ θ When ≥10%, the first step is activated. m Section 5 ball valve (M31), the m First heat exchanger (M32), shut down the first... m Second ball valve (M06); when 4MPa > P II ≥1.5MPa, 10%> θ When ≥0%, enable the first m Section 6 ball valve (M41), the m The second heat exchanger (M42) of the first stage is shut down. m Section 2 ball valve (M06); Step four: Adjust the throttle valve opening, compressor compression ratio, and heat exchanger power on the main pipeline of the multi-stage pressure and temperature control system so that the pressure monitored by the second pressure sensor (907) of the tail section subsystem reaches the outlet pressure of the tail section subsystem. P The preset value of 2 ensures that the temperature monitored by the second temperature sensor (908) of the tail section subsystem is not lower than 20°C; Step 5, activate the pipeline circulation mode: Close the first shut-off valve (941) at the tail end, open the main pipeline between the fourth ball valve (101) and the seventh ball valve (108), adjust the compression ratio of the first compressor (102) and the second compressor (107), and adjust the power of each section of the heat exchanger in the multi-stage pressure regulation and temperature control system until the pressure monitored by the mixed hydrogen storage tank (111) reaches the inlet pressure of the multi-stage pressure regulation and temperature control system pipeline. P 1. Close all pipelines of the gas supply system and open the eighth ball valve (115). Step 6: Simulate the joint operation of long-distance pipelines: Simulate the pressure loss of long-distance pipelines by adjusting the throttle valve opening of the multi-stage pressure regulation and temperature control system; change the pipeline temperature conditions by adjusting the heat exchanger power of the multi-stage pressure regulation and temperature control system; change the pipeline pressure conditions by adjusting the compressor compression ratio of the multi-stage pressure regulation and temperature control system and the reinjection system; and monitor the changes in flow rate, pressure and temperature in the pipeline by using ultrasonic flow meters, pressure sensors and temperature sensors, respectively. Step 7: Based on the pressure monitored by the second pressure sensor of each subsystem of the multi-stage pressure regulation and temperature control system, select the pipe test section that meets the pressure requirements, open the branch pipeline where the pipe test section is located, and simulate the pressure and temperature conditions of the pipe under service environment by adjusting the opening of the throttle valve and the power of the heat exchanger in the subsystem to which the test section belongs. Step 8: Shut down the heat exchanger and compressor of the multi-stage pressure and temperature control system and the reinjection system, and open the second shut-off valve (141) to release or recycle the high-pressure gas in the pipeline; after the release or recycling is completed, open the first shut-off valve (022) and the third ball valve (033) to purge the pipeline with high-pressure nitrogen; shut down all equipment and end the simulation test.

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