Experimental device and method for researching temperature drop and pressure drop characteristics of natural gas conveying pipeline

Abstract

The invention relates to an experimental device and method for researching temperature drop and pressure drop characteristics of a natural gas conveying pipeline, the experimental device comprises a natural gas interface, a gas inlet pipe and a closed circulation loop, the gas inlet end of the gas inlet pipe is communicated with the natural gas interface, and the gas outlet end of the gas inlet pipe is communicated with the closed circulation loop; the closed circulation loop is provided with a closed circulation starting point and a closed circulation end point, and the closed circulation loop is provided with a gas speed increasing pump; wherein the gas speed increasing pump is started, so that natural gas in the closed circulation loop flows directionally, and temperature values and pressure values of a closed circulation starting point and a closed circulation ending point of the closed circulation loop are collected at the same time, so that the temperature drop and pressure drop characteristics of the natural gas conveying pipeline are researched. According to the experimental device for researching the temperature drop and pressure drop characteristics of the natural gas conveying pipeline, pipeline conveying characteristic parameters such as pipeline conveying pressure difference and temperature difference under different hydrogen doping ratios can be accurately measured, and the influence of the natural gas pipeline conveying characteristics under the different hydrogen doping ratios can be effectively evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas transportation, and in particular to an experimental device and method for studying temperature drop and pressure drop characteristics of a natural gas transportation pipeline. Background Art

[0002] The consumption of traditional fossil energy not only leads to resource depletion, but also intensifies greenhouse gas emissions, causing serious impacts on the environment. Therefore, the development of clean and low-carbon energy forms has become an inevitable choice. Hydrogen, as a clean energy, has only water as its combustion product and has the characteristics of zero emissions. It is considered to be an important part of the future energy structure. In the field of renewable energy, such as wind power and photovoltaics, due to the intermittent and unstable power generation, some electricity cannot be absorbed by the power grid in time, forming the so-called "abandoned power" problem. Converting these abandoned electricity into hydrogen and storing it through methods such as electrolysis of water is one of the effective ways to solve the problem of abandoned power. Hydrogen-blended natural gas pipeline transportation uses this idea to mix hydrogen with natural gas and transport it to end users through pipelines, realizing long-distance, large-scale transportation and utilization of hydrogen. The natural gas pipeline transportation system has been relatively mature and complete worldwide, with the advantages of low transportation cost, high efficiency and good safety. Mixing hydrogen into natural gas and using existing natural gas pipelines for transportation can not only reduce the transportation cost of hydrogen, but also make full use of existing infrastructure resources and reduce duplication of construction.

[0003] Although hydrogen-blended natural gas pipeline transportation has many advantages, it still faces some technical challenges. For example, the addition of hydrogen will affect the material properties of the natural gas pipeline and may cause safety issues such as hydrogen embrittlement; at the same time, the selection of hydrogen blending ratio and the design of the mixing process also need further research and optimization. Therefore, it is necessary to strengthen the research and development of hydrogen-blended natural gas pipeline transportation technology and promote the formulation and improvement of relevant standards and specifications. However, the existing technical solutions cannot provide comprehensive data support for solving the long pipeline hydrogen-blended natural gas transportation. It lacks a gas transmission platform for high-pressure hydrogen-blended natural gas long pipelines, and lacks pressure difference and temperature change information in terms of parameter measurement that can be provided.

[0004] In conclusion, there is currently a lack of experimental equipment and methods for studying the characteristics of parameters such as pressure difference and temperature in pipeline transportation. Summary of the invention

[0005] The purpose of the present invention is to provide an experimental device and method for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, so as to solve the problem that there is currently a lack of experimental devices and methods for studying the pressure difference and temperature and other parameter characteristics of pipeline transportation.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention discloses an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, comprising a natural gas interface, an air inlet pipe and a closed circulation loop. The air inlet end of the air inlet pipe is connected to the natural gas interface, and the air outlet end of the air inlet pipe is connected to the closed circulation loop; The closed cycle loop is provided with a closed cycle starting point and a closed cycle end point, the closed cycle starting point is respectively provided with a first temperature sensor and a first pressure sensor, and the closed cycle end point is respectively provided with a second temperature sensor and a second pressure sensor; A gas speed-increasing pump is provided on the closed circulation loop; Wherein, the closed circulation loop is filled with natural gas to simulate a natural gas transmission pipeline; The gas speed increasing pump is started to make the natural gas in the closed circulation loop flow in a directional manner. At the same time, the temperature and pressure values ​​of the closed circulation starting point and the closed circulation end point of the closed circulation loop are collected, and the temperature difference and pressure difference between the closed circulation starting point and the closed circulation end point are compared to study the temperature drop and pressure drop characteristics of the natural gas transmission pipeline.

[0007] Furthermore, it also includes at least one hydrogen cylinder, the gas outlet of the hydrogen cylinder and the natural gas interface are connected in parallel and converge at the gas inlet end of the gas inlet pipe.

[0008] Furthermore, it also includes a plurality of nitrogen cylinders, the gas outlets of the nitrogen cylinders are connected in parallel with the gas outlets of the hydrogen cylinders and the natural gas interface and are gathered at the gas inlet end of the gas inlet pipe.

[0009] Preferably, the closed circulation loop includes a left coil, a right coil and an outer ring pipeline, the left coil and the right coil are formed by pipes spiraling from bottom to top in sequence, the bottom of the left coil and the right coil are respectively provided with coil air inlet ends, the coil air inlet end of the left coil is connected to the air outlet end of the air inlet pipe through a left three-way valve, and the coil air inlet end of the right coil is connected to the air outlet end of the air inlet pipe through a right three-way valve; the tops of the left coil and the right coil are respectively provided with air outlets, and the left coil The tube and the air outlet at the top of the right coil are connected through a connecting pipe, and the coil air inlet ends at the bottom of the left coil and the right coil are respectively connected to the two ends of the outer ring pipeline, and the outer ring pipeline, the left coil, the connecting pipe and the right coil are connected together to form the closed circulation loop; the closed circulation starting point is set at the junction of the coil air inlet end of the left coil and the air outlet end of the air inlet pipe, and the closed circulation end point is set at the junction of the coil air inlet end of the right coil and the air outlet end of the air inlet pipe.

[0010] Furthermore, the outer ring pipeline includes a main pipe portion, a left arc portion and a right arc portion, and the two ends of the main pipe portion are respectively connected to the coil air inlet ends at the bottom of the left coil and the right coil through the left arc portion and the right arc portion; the gas speed increasing pump is arranged on the main pipe portion of the outer ring pipeline; and a vacuum pump is arranged at the central position of the main pipe portion of the outer ring pipeline.

[0011] Furthermore, a drain valve is also provided on the left arc-shaped portion of the outer ring pipeline; and switch valves are respectively provided on the left arc-shaped portion and the right arc-shaped portion of the outer ring pipeline.

[0012] Furthermore, the main pipeline portion of the outer ring pipeline is provided with a flow regulating valve, the gas speed increasing pump, a first fluidized bed, a flow meter, a gas buffer tank, and a second fluidized bed in sequence from left to right.

[0013] Furthermore, a third temperature and pressure detection point is set on the connecting pipe between the left coil and the right coil, and a third temperature sensor and a pressure transmitter are respectively provided on the third temperature and pressure detection point; a fourth temperature and pressure detection point is set on the main pipe portion of the outer ring pipeline, and a fourth temperature sensor and a pressure transmitter are respectively provided on the fourth temperature and pressure detection point.

[0014] In a second aspect, the present invention further discloses an experimental method for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, using the above-mentioned experimental device, comprising: Step 1: Start the vacuum pump to evacuate the inside of the closed circulation loop; Step 2: Conduct an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under pure natural gas conditions, including the following steps: Step 21: except for the drain valve, all other valves in the closed circulation loop are opened; Step 22: Open the valve, pressure reducing valve and control valve of the natural gas interface respectively, and the natural gas enters the closed circulation loop through the air inlet pipe and is filled in the closed circulation loop until the natural gas pressure in the closed circulation loop reaches the pressure design value; Step 23: closing the valve of the left three-way valve through which the air inlet pipe flows to the air inlet end of the left coil and the valve of the right three-way valve through which the air inlet pipe flows to the air inlet end of the right coil, and stopping the air inlet pipe from injecting natural gas into the closed circulation loop; Step 24: Turn on the gas speed increasing pump to make the natural gas in the closed circulation loop flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point and the closed circulation end point are in a stable state; Step 25: The first temperature sensor and the first pressure sensor at the starting point of the closed cycle respectively collect the temperature and pressure of the starting point of the closed cycle, and the second temperature sensor and the second pressure sensor at the end point of the closed cycle respectively collect the temperature and pressure of the end point of the closed cycle; and according to the temperatures of the starting point of the closed cycle and the end point of the closed cycle, the temperature drop of the natural gas transmission pipeline is obtained, and according to the pressures of the starting point of the closed cycle and the end point of the closed cycle, the pressure drop of the natural gas transmission pipeline is obtained; Step 26: Turn off the gas speed increasing pump and open the drain valve to discharge the natural gas in the closed circulation loop.

[0015] In a third aspect, the present invention also discloses an experimental method for studying the temperature drop and pressure drop characteristics of a hydrogen-blended natural gas transmission pipeline, using the above-mentioned experimental device, including: Step S1: using the partial pressure method to calculate the partial pressures of hydrogen and natural gas in the hydrogen-blended natural gas; Step S2: starting the vacuum pump to evacuate the inside of the closed circulation loop; Step S3: Conducting an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under hydrogen-blended natural gas working conditions, including the following steps: Step S31: Filling the closed circulation loop with natural gas until the natural gas pressure reaches the natural gas partial pressure, and closing the valve of the natural gas interface; Step S32: opening the valve of the hydrogen cylinder and filling the closed circulation loop with hydrogen gas until the pressure reading in the closed circulation loop reaches the designed total pressure of the hydrogen-blended natural gas, thereby obtaining the hydrogen-blended natural gas; Step S33: Turn on the gas speed increasing pump to make the hydrogen-blended natural gas in the closed circulation loop flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point and the closed circulation end point are in a stable state; Step S34: the first temperature sensor and the first pressure sensor at the start point of the closed cycle respectively collect the temperature and pressure of the start point of the closed cycle, and the second temperature sensor and the second pressure sensor at the end point of the closed cycle respectively collect the temperature and pressure of the end point of the closed cycle; and according to the temperature of the start point of the closed cycle and the end point of the closed cycle, the temperature drop of the hydrogen-blended natural gas transmission pipeline is obtained, and according to the pressure of the start point of the closed cycle and the end point of the closed cycle, the pressure drop of the hydrogen-blended natural gas transmission pipeline is obtained; Step S35: Turn off the gas speed increasing pump and open the drain valve to discharge the hydrogen-blended natural gas in the closed circulation loop.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (I) The present invention discloses an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, comprising a natural gas interface, an air inlet pipe and a closed circulation loop, wherein the air inlet end of the air inlet pipe is connected to the natural gas interface, and the air outlet end of the air inlet pipe is connected to the closed circulation loop; a closed circulation starting point and a closed circulation end point are provided on the closed circulation loop, wherein the closed circulation starting point is provided with a first temperature sensor and a first pressure sensor, respectively, and the closed circulation end point is provided with a second temperature sensor and a second pressure sensor, respectively; a gas speed-increasing pump is provided on the closed circulation loop; wherein the closed circulation loop is filled with natural gas to simulate a long-distance high-pressure natural gas transmission pipeline; the gas speed-increasing pump is started to make the natural gas in the closed circulation loop flow in a directional manner, and at the same time, the temperature values ​​and pressure values ​​of the closed circulation starting point and the closed circulation end point of the closed circulation loop are collected, and the temperature difference and pressure difference between the closed circulation starting point and the closed circulation end point are compared to study the temperature drop and pressure drop characteristics of the natural gas transmission pipeline. The experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline disclosed in the present invention can realize accurate control of pipeline pressure and avoid large pressure fluctuations during the transmission process. It can accurately measure pipeline transmission characteristic parameters such as pipeline transmission pressure difference and temperature difference under different hydrogen blending ratios, study the stratification phenomenon that may occur during the transmission of hydrogen-blended natural gas, and effectively evaluate the impact of different hydrogen blending ratios on the transmission characteristics of the natural gas pipeline.

[0017] (II) The present invention discloses an experimental method for studying the temperature drop and pressure drop characteristics of natural gas transmission pipelines, including experiments on the temperature drop and pressure drop characteristics of natural gas long pipelines under pure natural gas and hydrogen-blended natural gas working conditions. Aiming at the problem of insufficient research on the design of long-distance high-pressure gas pipeline equipment and the influence of hydrogen blending on pipeline transmission characteristics, the coil layout scheme is adopted to complete the long pipeline design and save experimental land, and the experimental parameters of coil research on longer pipelines can be further increased. The hydrogen blending ratio can be controlled smoothly and accurately, the pipeline transmission characteristics of parameters such as pressure difference and temperature can be measured, and data can be recorded and analyzed.

[0018] In addition, the present invention also has the following advantages: 1. The whole device adopts a circulating test system, which greatly reduces the gas consumption. The coil layout scheme is adopted to reduce the footprint of the device while ensuring the pipe length.

[0019] 2. The device uses a gas speed-increasing pump as the power equipment, and reduces the pressure fluctuation caused by the pump through the arrangement of a fluidized bed and a gas buffer tank, which facilitates accurate measurement of data.

[0020] 3. The main body of the device adopts an integrated design and a skid-mounted design, which has the characteristics of simple operation, easy maintenance, low cost, multi-layer safety protection and early warning.

[0021] 4. By blending hydrogen into natural gas and using existing natural gas pipelines for transportation, theoretical support can be provided, which can not only reduce the transportation cost of hydrogen, but also utilize existing natural gas pipeline infrastructure resources. The research and development of hydrogen-blended natural gas pipeline transportation technology provides guidance for the formulation and improvement of relevant standards and specifications, and has significant engineering significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a top view of an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline provided in Example 1 of the present invention; Figure 2 yes Figure 1 A schematic diagram of the structure involving a closed circulation loop in which the skid-mounted support etc. is removed and the pipeline is retained; Figure 3 It is a front view of an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline provided in Example 1 of the present invention; Figure 4 is a side view of an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline provided in Example 1 of the present invention; Figure 5 It is a back view of the experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline provided in Example 1 of the present invention; Figure 6 yes Figure 5 The schematic diagram of the structure involving the connection between the air inlet pipe, the air inlet end of the coil and the left coil and the right coil; Figure 7 yes Figure 6 The structural diagram involving the closed loop starting point and the closed loop end point.

[0023] Description of reference numerals: A-closed cycle starting point, B-closed cycle end point, C-third temperature and pressure detection point, D-fourth temperature and pressure detection point; 10-intake pipe, 11-natural gas interface, 12-hydrogen cylinder, 13-nitrogen cylinder; 2-skid bracket, 20-coil air inlet end, 21-left coil, 22-right coil, 23-connecting pipe, 24-outer ring pipeline; 30-gas speed increasing pump, 31-left three-way valve, 32-right three-way valve; 41-vacuum pump, 42-drain valve, 43-switch valve, 51-flow regulating valve, 52-first fluidized bed, 53-flow meter, 54-gas buffer tank, 55-second fluidized bed; 61-Electrical control cabinet, 62-Digital acquisition control board. DETAILED DESCRIPTION

[0024] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0025] In order to solve the problem of the current lack of experimental devices and methods for studying the parameter characteristics such as pressure difference and temperature of pipeline transportation, the present invention discloses an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, comprising a natural gas interface, an air inlet pipe and a closed circulation loop, the air inlet end of the air inlet pipe is connected to the natural gas interface, and the air outlet end of the air inlet pipe is connected to the closed circulation loop; a closed circulation starting point and a closed circulation end point are provided on the closed circulation loop, the closed circulation starting point is respectively provided with a first temperature sensor and a first pressure sensor, and the closed circulation end point is respectively provided with a second temperature sensor and a second pressure sensor; a gas speed increasing pump is provided on the closed circulation loop; wherein the closed circulation loop is filled with natural gas to simulate a long-distance high-pressure natural gas transmission pipeline; the gas speed increasing pump is started to make the natural gas gas in the closed circulation loop flow in a directional manner, and at the same time, the temperature value and pressure value of the closed circulation starting point and the closed circulation end point of the closed circulation loop are collected, and the temperature difference and pressure difference between the closed circulation starting point and the closed circulation end point are compared to study the temperature drop and pressure drop characteristics of the natural gas transmission pipeline. The experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline disclosed in the present invention can realize accurate control of pipeline pressure and avoid large pressure fluctuations during the transmission process. It can accurately measure pipeline transmission characteristic parameters such as pipeline transmission pressure difference and temperature difference under different hydrogen blending ratios, study the stratification phenomenon that may occur during the transmission of hydrogen-blended natural gas, and effectively evaluate the impact of different hydrogen blending ratios on the transmission characteristics of the natural gas pipeline.

[0026] Example 1: An experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline Embodiment 1 of the present invention provides an experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, and its structure is described in detail below.

[0027] refer to Figure 1 , Figure 3 , Figure 4 and Figure 5 The experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transmission pipeline includes a natural gas interface 11, an air inlet pipe 10 and a closed circulation loop.

[0028] refer to Figure 2 , and combined with Figure 1 , the air inlet end of the air inlet pipe 10 is connected to the natural gas interface 12, and the air outlet end of the air inlet pipe 10 is connected to the closed circulation loop; The closed cycle loop is provided with a closed cycle starting point A and a closed cycle end point B, wherein the closed cycle starting point A is provided with a first temperature sensor and a first pressure sensor, and the closed cycle end point B is provided with a second temperature sensor and a second pressure sensor, such as Figures 5 to 7 shown.

[0029] The closed circulation loop is provided with a gas speed increasing pump 30; Wherein, the closed circulation loop is filled with natural gas to simulate a natural gas transmission pipeline; The gas speed increasing pump 30 is started to make the natural gas in the closed circulation loop flow in a directional manner. At the same time, the temperature value and pressure value of the closed circulation starting point A and the closed circulation end point B of the closed circulation loop are collected, and the temperature difference and pressure difference between the closed circulation starting point A and the closed circulation end point B are compared to study the temperature drop and pressure drop characteristics of the natural gas transmission pipeline.

[0030] Specifically, the first pressure sensor at the closed cycle starting point A and the second pressure sensor at the closed cycle end point B are both high-precision single-point pressure sensors with a measuring range of 0-10 MPa and an accuracy of 0.1%, which are used to measure the experimental pipeline pressure.

[0031] The first temperature sensor at the closed loop starting point A and the second temperature sensor at the closed loop end point B are both PT100 temperature sensors, which are thermocouple temperature sensors with a measuring range of -50~120°C and an accuracy of ±0.05°C~±0.5°C.

[0032] In order to study the long pipeline transportation of hydrogen-blended natural gas, hydrogen needs to be introduced. Therefore, the experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transportation pipeline also includes at least one hydrogen cylinder 12, and the gas outlet of the hydrogen cylinder 12 is connected in parallel with the natural gas interface 11 and converges at the gas inlet end of the inlet pipe 10.

[0033] In order to facilitate vacuuming and ensure that the oxygen concentration in the pipeline is below the limit oxygen concentration, thereby reducing the risk of combustion and explosion of combustible gas during the filling process, the experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transmission pipeline also includes a number of nitrogen cylinders 13, and the gas outlet of the nitrogen cylinder 13 is connected in parallel with the gas outlet of the hydrogen cylinder 12 and the natural gas interface 11 and converges at the gas inlet end of the inlet pipe 10.

[0034] As a specific implementation method, continue to refer to Figure 2 The closed circulation loop includes a left coil 21, a right coil 22 and an outer ring pipeline 24.

[0035] The left coil 21 and the right coil 22 are both formed by pipes being spiraled from bottom to top in sequence. Coil air inlet ends 20 are respectively provided at the bottom of the left coil 21 and the right coil 22. The coil air inlet end 20 of the left coil 21 is connected to the air outlet end of the air inlet pipe 10 through a left three-way valve 31, and the coil air inlet end 20 of the right coil 22 is connected to the air outlet end of the air inlet pipe 10 through a right three-way valve 32.

[0036] The tops of the left coil 21 and the right coil 22 are respectively provided with air outlets, and the air outlets at the tops of the left coil 21 and the right coil 22 are connected through a connecting pipe 23, and the coil air inlet ends 20 at the bottoms of the left coil 21 and the right coil 22 are respectively connected to the two ends of the outer ring pipeline 24, and the outer ring pipeline 24, the left coil 21, the connecting pipe 23 and the right coil 22 are connected together to form the closed circulation loop.

[0037] Among them, the left three-way valve 31 can control the conductivity between the air outlet end of the air intake pipe 10 and the coil air inlet end 20 of the left coil 21; the right three-way valve 32 can control the conductivity between the air outlet end of the air intake pipe 10 and the coil air inlet end 20 of the right coil 22.

[0038] When the left three-way valve 31 and the right three-way valve 32 separately control the conduction between the air outlet end of the air intake pipe 10 and the coil air intake ends 20 of the left coil 21 and the right coil 22, the gas flows from the air intake pipe 10 into the coil air intake ends 20 of the left coil 21 and the right coil 22.

[0039] Specifically, the gas speed-increasing pump 30 is arranged on the outer ring pipeline 24. The gas speed-increasing pump 30 can ensure the gas tightness of hydrogen under high pressure conditions and can be remotely controlled, with a maximum flow rate of 25 m / s and a flow rate control accuracy of 0.1 m / s.

[0040] When the junction of the coil air inlet end 20 of the left coil 21 and the air outlet end of the air inlet pipe 10 is set as the closed cycle starting point A, the air flow flows directionally in the closed cycle loop, passes through the outer ring pipeline 24, the left coil 21, the connecting pipe 23, and the right coil 22 in sequence, until it reaches the junction of the coil air inlet end 20 of the right coil 22 and the air outlet end of the air inlet pipe 10, which just constitutes the internal circulation of the gas between the left coil 21 and the right coil 22. Then, the junction of the coil air inlet end 20 of the right coil 22 and the air outlet end of the air inlet pipe 10 can be used as the closed cycle end point B. Therefore, the closed cycle starting point A is set at the junction of the coil air inlet end 20 of the left coil 21 and the air outlet end of the air inlet pipe 10, and the closed cycle end point B is set at the junction of the coil air inlet end 20 of the right coil 22 and the air outlet end of the air inlet pipe 10.

[0041] Further, continue to refer to Figure 2 The outer ring pipeline 24 includes a main pipeline portion, a left arc portion and a right arc portion. The two ends of the main pipeline portion are respectively connected to the coil air inlet ends 20 at the bottom of the left coil 21 and the right coil 22 through the left arc portion and the right arc portion; the gas speed increasing pump 30 is arranged on the main pipeline portion of the outer ring pipeline 24; and a vacuum pump 41 is arranged at the central position of the main pipeline portion of the outer ring pipeline 24.

[0042] Specifically, the vacuum pump 41 is an explosion-proof vacuum pump used for vacuum inerting.

[0043] In order to facilitate emptying, a drain valve 42 is further provided on the left arc portion of the outer ring pipeline 24 .

[0044] Specifically, the exhaust valve 42 is an exhaust explosion-proof switch valve.

[0045] In order to facilitate the control of gas flow in the closed circulation loop, switch valves 43 are respectively provided on the left arc-shaped portion and the right arc-shaped portion of the outer ring pipeline 24 .

[0046] Specifically, the switch valve 43 is an explosion-proof switch valve.

[0047] In order to conveniently control the flow of gas from the intake pipe 10 into the closed circulation loop, an intake switch valve is provided on the intake pipe 10 .

[0048] Specifically, the air intake switch valve is an air intake explosion-proof switch valve.

[0049] In order to facilitate gas buffering in the closed circulation loop, a gas buffer tank 54 is provided on the main pipeline portion of the outer ring pipeline 24 .

[0050] Specifically, referring to the figure, the main pipeline portion of the outer ring pipeline 24 is provided with a flow regulating valve 51, the gas speed increasing pump 30, a first fluidized bed 52, a flow meter 53, a gas buffer tank 54, and a second fluidized bed 55 from left to right.

[0051] Specifically, the flow regulating valve 51 is a high-pressure explosion-proof flow regulating valve.

[0052] Specifically, the flow meter 53 is a high-pressure explosion-proof flow meter.

[0053] The first fluidized bed 52 and the second fluidized bed 55 are used to reduce the pressure fluctuation in the pipeline that may be caused during the operation of the gas speed increasing pump 30 .

[0054] The gas buffer tank 54 is used to reduce the pressure fluctuation caused by the gas speed increasing pump 30 during the actual operation.

[0055] When the gas enters the closed circulation loop, it passes through the gas speed increasing pump 30 and the first fluidized bed 52, then through the gas buffer tank 54, and finally through the second fluidized bed 55, so that the gas flows in a steady and directional manner, during which the flow rate in the system is adjusted by the flow regulating valve 51.

[0056] In order to detect the temperature and pressure of the gas circulating inside the closed circulation loop, a third temperature and pressure detection point C is set on the connecting pipe 23 between the left coil 21 and the right coil 22, and a third temperature sensor and a pressure transmitter are respectively provided on the third temperature and pressure detection point C; a fourth temperature and pressure detection point D is set on the main pipeline portion of the outer ring pipeline 24, and a fourth temperature sensor and a pressure transmitter are respectively provided on the fourth temperature and pressure detection point D.

[0057] Among them, the third temperature sensor and the fourth temperature sensor are both common temperature sensors.

[0058] In order to facilitate the placement of the left coil 21, the right coil 22 and the outer ring pipeline 24 of the closed circulation loop, the experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transmission pipeline also includes a skid-mounted bracket 2, and the left coil 21, the right coil 22 and the outer ring pipeline 24 are arranged on the skid-mounted bracket 2.

[0059] Specifically, the skid-mounted bracket 2 has a load-bearing capacity of 2500 kg and is used to carry the entire experimental platform.

[0060] The skid-mounted bracket 2 adopts a tilted-mounted design and is a set of 4.2×2.5×2.5 m3 frame.

[0061] The outer ring pipeline 24 of the closed circulation loop is made of 304 stainless steel, with an outer diameter of 45 mm and a wall thickness of 4 mm.

[0062] The design pressure in the closed circulation loop is 12 MPa, and two sets of coils are designed, each set is 60 m long, with a total length of 120 m. The outer diameter of the coil is 1.6 m, and the height of the coil is 1.6 m.

[0063] In order to facilitate the movement of the experimental device outdoors and enhance the safety of the experimental process, the bottom of the skid-mounted bracket 2 is also configured with universal wheels.

[0064] In order to facilitate the control and distribution of pressure, the experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transmission pipeline also includes an electrical control cabinet 61, which is used for remote control of various electrical control components such as a gas speed increasing pump 18, a flow meter, and a pneumatic valve.

[0065] Specifically, the drain valve 42, the switch valve 43, and the air intake explosion-proof switch valve are all remotely controllable valves, the gas speed-increasing pump 30 is remotely controllable, and the controller of the gas speed-increasing pump 30, the drain valve 42, the switch valve 43, the air intake explosion-proof switch valve controller, and all pressure gauges are arranged in the electrical control cabinet. Therefore, different hydrogen blending ratios are achieved by using the pressure gauge of the electrical control cabinet 61 using the partial pressure method.

[0066] Specifically, the pressure gauge is used to control different hydrogen blending ratios using the partial pressure method, and then the well-proportioned gas source is introduced into the gas buffer tank for full mixing, and further passes through the gas speed increasing pump 30 and the first fluidized bed 52 to output it stably at a specified flow rate, and finally enters the disc-shaped pipeline for gas circulation, and the experimental parameters under different working conditions are monitored by temperature and pressure sensors.

[0067] In order to facilitate the calculation of temperature drop according to the temperatures of the closed cycle starting point A and the closed cycle end point B, and the calculation of pressure drop according to the pressures of the closed cycle starting point A and the closed cycle end point B, the experimental device for studying the temperature drop and pressure drop characteristics of the natural gas transmission pipeline also includes a digital acquisition control board 62, and the first temperature sensor and the first pressure sensor of the closed cycle starting point A, and the second temperature sensor and the second pressure sensor of the closed cycle end point B are respectively connected to the digital acquisition control board 62.

[0068] Example 2: An experimental method for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline Embodiment 2 of the present invention provides an experimental method for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, using the experimental device of Embodiment 1, and the experimental method comprises the following steps: Step 1: Start the vacuum pump 41 to evacuate the inside of the closed circulation loop, including the following steps: Step 11: Open the valve of the nitrogen bottle 13 and inject nitrogen into the closed circulation loop until the nitrogen pressure in the closed circulation loop reaches normal pressure; Step 12: Start the vacuum pump to evacuate the inside of the closed circulation loop until the oxygen concentration in the closed circulation loop drops below the safety limit, ensuring that the oxygen concentration in the pipeline is below the limit oxygen concentration, thereby reducing the risk of combustion and explosion of combustible gas during the filling process; Step 13: Close all valves.

[0069] Step 2: Conduct an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under pure natural gas conditions of 4Mpa, including the following steps: Step 21: Except for the drain valve 42, all other valves in the closed circulation loop are opened.

[0070] Step 22: Open the valve, pressure reducing valve and control valve of the natural gas interface 11 respectively, and the natural gas enters the closed circulation loop through the intake pipe 10 and is filled in the closed circulation loop until the natural gas pressure in the closed circulation loop reaches the design pressure value.

[0071] Specifically, the natural gas is methane gas.

[0072] Specifically, the pressure design value is 4Mpa.

[0073] When the pressure of the methane gas in the closed circulation loop and the natural gas interface 11 are balanced and insufficient to reach the design pressure, the natural gas interface 11 is replaced and the gas is continuously filled into the pipeline.

[0074] Step 23: Close the valve in the left three-way valve 31 through which the air intake pipe 10 flows to the coil air intake end 20 of the left coil 21 and the valve in the right three-way valve 32 through which the air intake pipe 10 flows to the coil air intake end 20 of the right coil 22, and stop the air intake pipe 10 from injecting natural gas into the closed circulation loop.

[0075] Step 24: Turn on the gas speed increasing pump 30 to make the natural gas in the closed circulation loop flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point A and the closed circulation end point B are in a stable state.

[0076] Specifically, the stable state means that the pressure value fluctuates no more than 5%.

[0077] Step 25: The first temperature sensor and the first pressure sensor of the closed cycle starting point A respectively collect the temperature and pressure of the closed cycle starting point A, and the second temperature sensor and the second pressure sensor of the closed cycle end point B respectively collect the temperature and pressure of the closed cycle end point B; and according to the temperatures of the closed cycle starting point A and the closed cycle end point B, the temperature drop of the natural gas transmission pipeline is obtained, and according to the pressures of the closed cycle starting point A and the closed cycle end point B, the pressure drop of the natural gas transmission pipeline is obtained.

[0078] Step 26: Turn off the gas speed increasing pump 30 and open the drain valve 42 to discharge the natural gas in the closed circulation loop.

[0079] Example 3: An experimental method for studying the temperature drop and pressure drop characteristics of hydrogen-blended natural gas in long pipeline transportation Embodiment 3 of the present invention provides an experimental method for studying the temperature drop and pressure drop characteristics of long pipeline transportation of hydrogen-blended natural gas, which is an experimental method for studying the temperature drop and pressure drop characteristics of long pipeline transportation of natural gas under hydrogen-blended natural gas working conditions. The experimental device of Embodiment 1 is used, and the experimental method comprises the following steps: Step S1: using the partial pressure method to calculate the pressures of hydrogen and natural gas in the hydrogen-blended natural gas respectively; Specifically, the length of the pipeline is 130 meters, of which the experimental pipeline is 120 meters, with an inner diameter of 37 mm, and the gas volume that can be loaded is 90L. If the volume content of hydrogen in the mixture of hydrogen and natural gas is 30%, the required hydrogen pressure using the partial pressure method is 1.2Mpa and the methane gas pressure is 2.8Mpa. The total design pressure of hydrogen-blended natural gas is 4Mpa.

[0080] Step S2: starting the vacuum pump 41 to evacuate the inside of the closed circulation loop, including the following steps: Step S21: Open the valve of the nitrogen bottle 13 and inject nitrogen into the closed circulation loop until the nitrogen pressure in the closed circulation loop reaches normal pressure; Step S22: starting the vacuum pump to evacuate the inside of the closed circulation loop until the oxygen concentration in the closed circulation loop drops below the safety limit, ensuring that the oxygen concentration in the pipeline is below the limit oxygen concentration, thereby reducing the risk of combustion and explosion of combustible gas during the filling process; Step S23: Close all valves.

[0081] Step S3: Conducting an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under hydrogen-blended natural gas working conditions, including the following steps: Step S31: Filling the closed circulation loop with natural gas until the natural gas pressure reaches the natural gas partial pressure, and closing the valve of the natural gas interface 11; Specifically, the natural gas is methane.

[0082] Specifically, the partial pressure of natural gas is 2.8 MPa.

[0083] Step S32: Open the valve of the hydrogen cylinder 12 and fill the closed circulation loop with hydrogen gas until the pressure reading in the closed circulation loop reaches the designed total pressure of the hydrogen-blended natural gas, thereby obtaining the hydrogen-blended natural gas.

[0084] When the pressure of the hydrogen gas in the closed circulation loop and the pressure in the hydrogen cylinder 12 are balanced and insufficient to reach the design pressure, the hydrogen cylinder 12 is replaced and the closed circulation loop is continuously filled with gas until the design total pressure of the hydrogen-blended natural gas is reached.

[0085] Step S33: Turn on the gas speed increasing pump 30 to make the hydrogen-blended natural gas in the closed circulation loop flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point A and the closed circulation end point B are in a stable state.

[0086] Step S34: the first temperature sensor and the first pressure sensor of the closed cycle starting point A respectively collect the temperature and pressure of the closed cycle starting point A, and the second temperature sensor and the second pressure sensor of the closed cycle end point B respectively collect the temperature and pressure of the closed cycle end point B; and according to the temperatures of the closed cycle starting point A and the closed cycle end point B, the temperature drop of the hydrogen-blended natural gas transmission pipeline is obtained, and according to the pressures of the closed cycle starting point A and the closed cycle end point B, the pressure drop of the hydrogen-blended natural gas transmission pipeline is obtained.

[0087] Step S35: Turn off the gas speed increasing pump 30, open the exhaust valve 42, and discharge the hydrogen-blended natural gas in the closed circulation loop.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An experimental device for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, characterized in that: It includes a natural gas interface (11), an air inlet pipe (10) and a closed circulation loop. The air inlet end of the air inlet pipe (10) is connected to the natural gas interface (12), and the air outlet end of the air inlet pipe (10) is connected to the closed circulation loop; The closed cycle loop is provided with a closed cycle starting point (A) and a closed cycle end point (B), the closed cycle starting point (A) is respectively provided with a first temperature sensor and a first pressure sensor, and the closed cycle end point (B) is respectively provided with a second temperature sensor and a second pressure sensor; The closed circulation loop is provided with a gas speed increasing pump (30); Wherein, the closed circulation loop is filled with natural gas to simulate a natural gas transmission pipeline; The gas speed increasing pump (30) is started to make the natural gas in the closed circulation loop flow in a directional manner, and the temperature value and pressure value of the closed circulation starting point (A) and the closed circulation end point (B) of the closed circulation loop are collected at the same time, and the temperature difference and pressure difference between the closed circulation starting point (A) and the closed circulation end point (B) are compared to study the temperature drop and pressure drop characteristics of the natural gas transmission pipeline.

2. The experimental device according to claim 1, characterized in that: Also includes at least one hydrogen cylinder (12), The gas outlet of the hydrogen bottle (12) and the natural gas interface (11) are connected in parallel and converge at the gas inlet end of the gas inlet pipe (10).

3. The experimental device according to claim 2, characterized in that: Also included are a number of nitrogen bottles (13), The gas outlet of the nitrogen bottle (13), the gas outlet of the hydrogen bottle (12), and the natural gas interface (11) are connected in parallel and converge at the gas inlet end of the gas inlet pipe (10).

4. The experimental device according to claim 1, characterized in that: The closed circulation loop comprises a left coil (21), a right coil (22) and an outer ring pipeline (24). The left coil (21) and the right coil (22) are formed by pipes being spiraled in sequence from bottom to top; the bottoms of the left coil (21) and the right coil (22) are respectively provided with coil air inlet ends (20); the coil air inlet end (20) of the left coil (21) is connected to the air outlet end of the air inlet pipe (10) via a left three-way valve (31); and the coil air inlet end (20) of the right coil (22) is connected to the air outlet end of the air inlet pipe (10) via a right three-way valve (32); The tops of the left coil (21) and the right coil (22) are respectively provided with air outlets, and the air outlets at the tops of the left coil (21) and the right coil (22) are connected via a connecting pipe (23); the coil air inlet ends (20) at the bottoms of the left coil (21) and the right coil (22) are respectively connected to two ends of the outer ring pipeline (24); the outer ring pipeline (24), the left coil (21), the connecting pipe (23) and the right coil (22) are connected together to form the closed circulation loop; The closed cycle starting point (A) is set at the junction of the coil air inlet end (20) of the left coil (21) and the air outlet end of the air inlet pipe (10), and the closed cycle end point (B) is set at the junction of the coil air inlet end (20) of the right coil (22) and the air outlet end of the air inlet pipe (10).

5. The experimental device according to claim 4, characterized in that: The outer ring pipeline (24) comprises a main pipeline portion, a left arc-shaped portion and a right arc-shaped portion, and two ends of the main pipeline portion are respectively connected to the coil air inlet ends (20) at the bottoms of the left coil (21) and the right coil (22) through the left arc-shaped portion and the right arc-shaped portion; The gas speed increasing pump (30) is arranged on the main pipeline portion of the outer ring pipeline (24); A vacuum pump (41) is provided at the central position of the main pipeline portion of the outer ring pipeline (24).

6. The experimental device according to claim 5, characterized in that: A drain valve (42) is also provided on the left arc-shaped portion of the outer ring pipeline (24); On-off valves (43) are respectively provided on the left arc-shaped portion and the right arc-shaped portion of the outer ring pipeline (24).

7. The experimental device according to claim 5, characterized in that: The main pipeline portion of the outer ring pipeline (24) is provided with a flow regulating valve (51), the gas speed increasing pump (30), a first fluidized bed (52), a flow meter (53), a gas buffer tank (54), and a second fluidized bed (55) in sequence from left to right.

8. The experimental device according to claim 6, characterized in that: A third temperature and pressure detection point (C) is arranged on the connecting pipe (23) between the left coil (21) and the right coil (22), and a third temperature sensor and a pressure transmitter are respectively arranged on the third temperature and pressure detection point (C); The main pipeline portion of the outer ring pipeline (24) is provided with a fourth temperature and pressure detection point (D), and the fourth temperature and pressure detection point (D) is respectively provided with a fourth temperature sensor and a pressure transmitter.

9. An experimental method for studying the temperature drop and pressure drop characteristics of a natural gas transmission pipeline, using the experimental device described in any one of claims 1 to 8, characterized in that: include: Step 1: starting the vacuum pump (41) to evacuate the interior of the closed circulation loop; Step 2: Conduct an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under pure natural gas conditions, including the following steps: Step 21: Except for the drain valve (42), all other valves in the closed circulation loop are opened; Step 22: The valve, the pressure reducing valve and the control valve of the natural gas interface (11) are opened respectively, and the natural gas enters the closed circulation loop through the gas inlet pipe (10) and is filled in the closed circulation loop until the natural gas pressure in the closed circulation loop reaches the pressure design value; Step 23: closing the valve in the left three-way valve (31) through which the air inlet pipe (10) flows to the coil air inlet end (20) of the left coil (21) and the valve in the right three-way valve (32) through which the air inlet pipe (10) flows to the coil air inlet end (20) of the right coil (22), and stopping the air inlet pipe (10) from injecting natural gas into the closed circulation loop; Step 24: turning on the gas speed increasing pump (30) to allow the natural gas in the closed circulation loop to flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point (A) and the closed circulation end point (B) are in a stable state; Step 25: The first temperature sensor and the first pressure sensor at the closed cycle starting point (A) respectively collect the temperature and pressure of the closed cycle starting point (A), and the second temperature sensor and the second pressure sensor at the closed cycle end point (B) respectively collect the temperature and pressure of the closed cycle end point (B); and according to the temperatures of the closed cycle starting point (A) and the closed cycle end point (B), the temperature drop of the natural gas transmission pipeline is obtained, and according to the pressures of the closed cycle starting point (A) and the closed cycle end point (B), the pressure drop of the natural gas transmission pipeline is obtained; Step 26: Turn off the gas speed increasing pump (30), and open the drain valve (42) to discharge the natural gas in the closed circulation loop.

10. An experimental method for studying the temperature drop and pressure drop characteristics of a hydrogen-blended natural gas transmission pipeline, using the experimental device described in any one of claims 1 to 8, characterized in that: include Step S1: using the partial pressure method to calculate the partial pressures of hydrogen and natural gas in the hydrogen-blended natural gas; Step S2: starting the vacuum pump (41) to evacuate the interior of the closed circulation loop; Step S3: Conducting an experiment to study the temperature drop and pressure drop characteristics of natural gas long pipeline transportation under hydrogen-blended natural gas working conditions, including the following steps: Step S31: Filling the closed circulation loop with natural gas until the natural gas pressure reaches the natural gas partial pressure, and closing the valve of the natural gas interface (11); Step S32: opening the valve of the hydrogen cylinder (12) and filling the closed circulation loop with hydrogen gas until the pressure reading in the closed circulation loop reaches the designed total pressure of the hydrogen-blended natural gas, thereby obtaining the hydrogen-blended natural gas; Step S33: turning on the gas speed increasing pump (30) to make the hydrogen-blended natural gas in the closed circulation loop flow in a directional manner until the pressure values ​​collected by the pressure sensors at the closed circulation starting point (A) and the closed circulation end point (B) are in a stable state; Step S34: the first temperature sensor and the first pressure sensor at the closed cycle starting point (A) respectively collect the temperature and pressure of the closed cycle starting point (A), and the second temperature sensor and the second pressure sensor at the closed cycle end point (B) respectively collect the temperature and pressure of the closed cycle end point (B); and according to the temperature of the closed cycle starting point (A) and the closed cycle end point (B), the temperature drop of the hydrogen-blended natural gas transmission pipeline is obtained, and according to the pressure of the closed cycle starting point (A) and the closed cycle end point (B), the pressure drop of the hydrogen-blended natural gas transmission pipeline is obtained; Step S35: turning off the gas speed increasing pump (30) and opening the exhaust valve (42) to discharge the hydrogen-blended natural gas in the closed circulation loop.

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