Experimental device and method suitable for stopping transportation and restarting of carbon dioxide pipeline

Abstract

The invention provides an experimental device and method suitable for stopping transportation and restarting of a carbon dioxide pipeline, and belongs to the field of carbon dioxide pipeline transportation. The low-temperature plunger pump and the heat exchanger are additionally arranged on the test pipeline, so that the transportation stopping and restarting working conditions of the impurity-containing supercritical-dense-phase carbon dioxide pipeline are simulated, and pressure, temperature and liquid holdup change data in the transportation stopping and restarting process of pipelines with different initial temperature pressures and phase states are obtained. The device makes up the blank of related experimental devices.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide pipeline transportation, and more specifically, to an experimental apparatus and method suitable for restarting a carbon dioxide pipeline after a shutdown. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) technology, as a large-scale CO2 emission reduction technology, has become a key technology for my country to achieve carbon peaking and carbon neutrality. Among these technologies, CO2-driven enhanced oil recovery (EOR) is one of the research hotspots in CCUS, effectively reducing CO2 emissions while improving block recovery, and is widely used in major oilfields. The CO2 captured from the carbon source needs to be transported to the oilfield for injection via CO2 pipelines; therefore, the safety of CO2 pipeline transportation is a crucial guarantee for the efficient and stable operation of CCUS projects.

[0003] According to the paper, the main pipeline of the CO2 leakage experiment at China University of Petroleum (East China) is 14.85m long, with an inner diameter of 15mm and a wall thickness of 3mm. The pressurization section consists of a CO2 cylinder, a refrigeration unit, a liquid CO2 high-pressure pump, a constant temperature water bath, and a high-pressure reactor, which can conduct leakage experiments on CO2 pipelines with different phases.

[0004] According to the paper, the CO2 pipeline device at Dalian University of Technology has a total length of 258m, mainly consisting of a 257m main pipeline and a 1m double-membrane rupture device. The pipeline dimensions are 273×20mm, and it uses 16MnD low-temperature steel and 304 stainless steel respectively. It was designed to achieve experiments involving high pressure, multiphase flow, full-diameter operation, horizontal and upward venting, and vertical venting.

[0005] According to Chinese patent application documents CN117705383A, CN105699023B, CN117989464A, and CN115577216A, current patent applications for experimental devices and methods for ensuring the safety of carbon dioxide (CO2) pipeline transportation are concentrated on leakage and diffusion characteristic testing, pipeline rupture and crack arrest testing, planned venting tests, and phase control.

[0006] The aforementioned devices involved experimental research on ensuring the safety of supercritical CO2 pipeline flow, but none of them considered the experimental requirements for restarting the CO2 pipeline after a shutdown. Therefore, it is crucial to establish a CO2 pipeline experimental platform capable of conducting experimental research on shutdown and restart scenarios. Summary of the Invention

[0007] To address the aforementioned technical problems in the existing technology, this invention provides an experimental apparatus and method suitable for restarting carbon dioxide pipelines after shutdown. By analyzing the pressure, temperature, and liquid holdup changes during pipeline shutdown and restart processes with different initial temperatures, pressures, and phases, the invention explores the synergistic change law of carbon dioxide temperature, pressure, phase, and liquid holdup, proposes shutdown boundary conditions, and optimizes the restart operation scheme, including restart timing, selection of the phase of the newly injected fluid, control of the mass flow rate of the injected fluid, and risk prevention measures during the restart process.

[0008] This invention provides an experimental device suitable for restarting a carbon dioxide pipeline after shutdown, including a main pipeline, multiple temperature and pressure sensors installed on the main pipeline, multiple impurity injection points and impurity gas cylinders; it also includes an electric heating belt installed on the main pipeline and a heating system temperature control box connected to the electric heating belt;

[0009] A vertical cryogenic storage tank and a main pipeline vent valve are sequentially installed on the main pipeline. A main pipeline gas phase filling pipe and a main pipeline liquid phase filling pipe are connected between the vertical cryogenic storage tank and the main pipeline vent valve. A first shut-off valve and a second shut-off valve are respectively installed between the main pipeline vent valve and the main pipeline gas phase filling pipe and the main pipeline liquid phase filling pipe. A heat exchanger and a cryogenic plunger pump are installed on the main pipeline between the main pipeline vent valve and the vertical cryogenic storage tank. A third shut-off valve, a fourth shut-off valve, and a fifth shut-off valve are respectively installed on the main pipeline between the main pipeline vent valve and the heat exchanger, on the main pipeline between the heat exchanger and the cryogenic plunger pump, and on the main pipeline between the cryogenic plunger pump and the vertical cryogenic storage tank.

[0010] The vertical cryogenic storage tank is connected to a gas phase filling port and a liquid phase filling port.

[0011] A flow meter is connected to the main pipe at the other end of the third shut-off valve. Multiple temperature and pressure sensors are respectively installed at the vertical cryogenic storage tank, on the main pipe between the heat exchanger and the cryogenic plunger pump, on the main pipe between the third shut-off valve and the heat exchanger, and on the main pipe at the other end away from the third shut-off valve.

[0012] Multiple impurity injection points are distributed among multiple temperature and pressure sensors on the main pipeline connected to the flow meter and far from the third shut-off valve;

[0013] Multiple impurity injection points are connected to impurity gas cylinders, and each impurity injection point inlet is equipped with an impurity injection valve. The impurity gas cylinder is also equipped with an impurity gas cylinder valve.

[0014] A pressure relief rupture disc is also installed on the main pipeline connected to the flow meter and located away from the third shut-off valve.

[0015] Preferably, the vertical cryogenic storage tank is equipped with a vertical cryogenic storage tank vent valve.

[0016] Preferably, the vertical cryogenic storage tank is installed on the vertical cryogenic storage tank weighbridge.

[0017] Preferably, a check valve is also provided between the cryogenic plunger pump and the fourth shut-off valve.

[0018] This invention provides an experimental method for restarting a carbon dioxide pipeline after shutdown. The method utilizes the aforementioned experimental apparatus for restarting a carbon dioxide pipeline after shutdown, and includes the following steps:

[0019] Step S1: Perform an integrity check on the experimental setup suitable for restarting a carbon dioxide pipeline after a shutdown.

[0020] Step S2: Inject gaseous carbon dioxide at a temperature lower than room temperature into the main pipeline through the main pipeline gas phase filling pipe to purge, pre-cool, and check the airtightness of the main pipeline.

[0021] Step S3: The impurity gas is quantitatively injected from the impurity gas cylinder into the main pipeline through the impurity injection point;

[0022] Step S4: Select the test pipeline, close the corresponding shut-off valve, and conduct a stop-flow test on the test pipeline;

[0023] Step S5: Open the shut-off valve that was closed in step S4 and perform a restart test on the test pipeline.

[0024] Preferably, the shutdown and restart experiment of the test pipeline in steps S4 and S5 includes a shutdown and restart experiment of a supercritical carbon dioxide pipeline containing impurities and a shutdown and restart experiment of a dense phase carbon dioxide pipeline containing impurities.

[0025] Preferably, the pipeline shutdown experiment for supercritical carbon dioxide containing impurities is carried out according to the following steps:

[0026] Step S101, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met.

[0027] Step S102, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure.

[0028] Step S103, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process. The low-frequency pressure refers to the pressure in the 20-500Hz frequency band.

[0029] Preferably, the restart experiment of the supercritical carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0030] Step S111, Liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met.

[0031] Step S112, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipeline is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure.

[0032] Step S113, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0033] Step S114, restart the experiment: Open the fifth shut-off valve to fill the cryogenic plunger pump and heat exchanger with liquid carbon dioxide from the vertical cryogenic storage tank, and then start the cryogenic plunger pump and heat exchanger so that the temperature and pressure of the temperature and pressure sensors at the heat exchanger outlet are higher than the preset temperature and pressure. Then open the third shut-off valve at the heat exchanger outlet to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump and heat exchanger, and the experiment ends.

[0034] Preferably, the shutdown test of the dense phase carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0035] Step S201, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met.

[0036] Step S202, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the pressure is higher than the preset pressure, but the temperature is lower than the preset temperature;

[0037] Step S203, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0038] Preferably, the restart experiment of the dense phase carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0039] Step S211, Liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and at the same time open the main pipeline vent valve to replace the gaseous carbon dioxide with liquid carbon dioxide. Control the filling amount through the flow meter to reach the required mass for the experiment and then stop filling.

[0040] Step S212, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized to a pressure higher than the preset pressure, but the temperature is lower than the preset temperature;

[0041] Step S213, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0042] Step S214, restart the experiment: Open the fifth shut-off valve to fill the cryogenic plunger pump and heat exchanger with liquid carbon dioxide from the vertical cryogenic storage tank, and then start the cryogenic plunger pump and heat exchanger so that the pressure of the temperature and pressure sensor at the heat exchanger outlet is higher than the preset pressure, but the temperature is lower than the preset temperature. Then open the third shut-off valve at the heat exchanger outlet to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump and heat exchanger, and the experiment ends.

[0043] Preferably, the preset temperature is the critical temperature of the experimental gas medium, and the preset pressure is the critical pressure of the experimental gas medium.

[0044] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0045] (1) This invention simulates the shutdown and restart conditions of a supercritical-dense phase carbon dioxide pipeline containing impurities by adding a low-temperature plunger pump and a heat exchanger to the test pipeline. It obtains data on pressure, temperature and liquid holdup changes during the shutdown and restart processes of pipelines with different initial temperatures, pressures and phase states. This helps to propose shutdown boundary conditions and optimize the restart operation scheme, including restart timing, selection of the phase state of the newly injected fluid, control of the mass flow rate of the injected fluid, and risk prevention measures during the restart process.

[0046] (2) This invention simulates the initial phase state of the fluid in the pipe before pipeline shutdown by changing the initial temperature and pressure of the fluid inside the pipe; by recording the changes in temperature and pressure of the fluid inside the pipe during pipeline shutdown, it analyzes the synergistic change law of temperature, pressure and phase state of the fluid inside the pipe during the shutdown of impurity-containing carbon dioxide pipelines with different initial temperature and pressure and phase state; by changing the pressure, temperature and flow rate of the injected fluid, it records the changes in temperature and pressure of the fluid inside the pipe during pipeline restart, and can analyze the temperature and pressure change law of the fluid inside the pipe and phase state during the restart process after the shutdown of impurity-containing carbon dioxide pipelines with different initial temperature and pressure and phase state; by summarizing and analyzing the above laws, it can obtain the shutdown and restart characteristics of impurity-containing supercritical-dense phase carbon dioxide pipelines and propose process optimization schemes. Currently, there is no device or method capable of conducting the above experimental objectives, and this invention fills the gap in related experimental devices. Attached Figure Description

[0047] Figure 1 A schematic diagram of an experimental apparatus for restarting a carbon dioxide pipeline after a shutdown, as provided in one embodiment of the present invention.

[0048] Diagram: 1-Main pipeline, 2-Vertical cryogenic storage tank, 3-Vertical cryogenic storage tank vent valve, 4-Vertical cryogenic storage tank weighbridge, 5-Vertical cryogenic storage tank vapor phase filling port, 6-Vertical cryogenic storage tank liquid phase filling port, 7-Cryogenic plunger pump, 8-Heat exchanger, 9-Pressure relief rupture disc, 10-Main pipeline vent valve, 11-Main pipeline vapor phase filling pipe, 12-Main pipeline liquid phase filling pipe, 13-Flow meter, 14-27-Temperature and pressure sensors, 28-35-Impurity injection valve, 36-Impurity gas cylinder valve, 37-Second shut-off valve, 38-First shut-off valve, 39-Third shut-off valve, 40-Fourth shut-off valve, 41-Fifth shut-off valve, 42-Check valve. Detailed Implementation

[0049] The present invention will be further described below with reference to specific implementation examples. However, the description of the following embodiments is only for the purpose of helping to understand the principles and core ideas of the present invention, and is not intended to limit the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements made to the present invention without departing from the principles of the present invention also fall within the scope of protection of the claims of the present invention.

[0050] The following detailed description, in conjunction with the accompanying drawings, describes the specific implementation of the experimental apparatus and method provided by the present invention for restarting carbon dioxide pipelines after shutdown.

[0051] This invention provides an experimental device suitable for restarting a carbon dioxide pipeline after shutdown, including a main pipeline 1, multiple temperature and pressure sensors installed on the main pipeline 1, multiple impurity injection points and impurity gas cylinders; it also includes an electric heating belt (not shown in the figure) installed on the main pipeline 1 and a heating system temperature control box (not shown in the figure) connected to the electric heating belt.

[0052] A vertical cryogenic storage tank 2 and a main pipeline vent valve 10 are sequentially installed on the main pipeline 1. A main pipeline gas phase filling pipe 11 and a main pipeline liquid phase filling pipe 12 are connected between the vertical cryogenic storage tank 2 and the main pipeline vent valve 10. A first shut-off valve 38 and a second shut-off valve 37 are respectively installed between the main pipeline vent valve 10 and the main pipeline gas phase filling pipe 11 and the main pipeline liquid phase filling pipe 12. A heat exchanger 8 and a cryogenic plunger pump 7 are installed on the main pipeline 1 between the main pipeline vent valve 10 and the vertical cryogenic storage tank 2. A third shut-off valve 39, a fourth shut-off valve 40 and a fifth shut-off valve 41 are respectively installed on the main pipeline 1 between the main pipeline vent valve 10 and the heat exchanger 8, on the main pipeline 1 between the heat exchanger 8 and the cryogenic plunger pump 7, and on the main pipeline 1 between the cryogenic plunger pump 7 and the vertical cryogenic storage tank 2.

[0053] The vertical cryogenic storage tank 2 is connected to a vertical cryogenic storage tank gas phase filling port 5 and a vertical cryogenic storage tank liquid phase filling port 6.

[0054] A flow meter 13 is connected to the main pipe 1 at the other end of the third shut-off valve 39. Multiple temperature and pressure sensors are respectively installed at the vertical cryogenic storage tank 2, on the main pipe 1 between the heat exchanger 8 and the cryogenic plunger pump 7, on the main pipe 1 between the third shut-off valve 39 and the heat exchanger 8, and on the main pipe 1 at the other end away from the third shut-off valve 39.

[0055] Multiple impurity injection points are distributed among multiple temperature and pressure sensors on the main pipeline 1, which is connected to the flow meter 13 and is far from the third shut-off valve 39.

[0056] Multiple impurity injection points are connected to impurity gas cylinders, and each impurity injection point inlet is equipped with an impurity injection valve. The impurity gas cylinder is also equipped with an impurity gas cylinder valve.

[0057] A pressure relief rupture disc 9 is also installed on the main pipeline 1 that connects to the flow meter 13 and is far away from the third shut-off valve 39.

[0058] According to a specific embodiment of the present invention, a vertical cryogenic storage tank 2 is provided with a vertical cryogenic storage tank vent valve 3.

[0059] According to a specific embodiment of the present invention, the vertical cryogenic storage tank 2 is installed on the vertical cryogenic storage tank weighbridge 4.

[0060] According to a specific embodiment of the present invention, a one-way valve 42 is further provided between the cryogenic plunger pump 7 and the fourth shut-off valve 40.

[0061] This invention provides an experimental method for restarting a carbon dioxide pipeline after shutdown. The method utilizes the aforementioned experimental apparatus for restarting a carbon dioxide pipeline after shutdown, and includes the following steps:

[0062] Step S1: Perform an integrity check on the experimental setup suitable for restarting a carbon dioxide pipeline after a shutdown.

[0063] Step S2: Inject gaseous carbon dioxide at a temperature lower than room temperature into the main pipeline 1 through the main pipeline gas phase filling pipe 11 to purge, pre-cool, and check the airtightness of the main pipeline 1.

[0064] Step S3: The impurity gas is quantitatively injected from the impurity gas cylinder into the main pipeline 1 through the impurity injection point;

[0065] Step S4: Select the test pipeline, close the corresponding shut-off valve, and conduct a stop-flow test on the test pipeline;

[0066] Step S5: Open the shut-off valve that was closed in step S4 and perform a restart test on the test pipeline.

[0067] According to a specific embodiment of the present invention, the shutdown and restart experiment of the test pipeline in steps S4 and S5 includes a shutdown and restart experiment of a supercritical carbon dioxide pipeline containing impurities and a shutdown and restart experiment of a dense phase carbon dioxide pipeline containing impurities.

[0068] According to a specific embodiment of the present invention, the pipeline shutdown experiment for supercritical carbon dioxide containing impurities is carried out according to the following steps:

[0069] Step S101, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe 12 to the tank truck liquid phase pipeline, and open the main pipeline vent valve 10 at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter 13. Stop filling after the experimental requirements are met.

[0070] Step S102, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure.

[0071] Step S103, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process. The low-frequency pressure refers to the pressure in the 20-500Hz frequency band.

[0072] According to a specific embodiment of the present invention, the restart experiment of a supercritical carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0073] Step S111, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe 12 to the tank truck liquid phase pipeline, and open the main pipeline vent valve 10 at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter 13. Stop filling after the experimental requirements are met.

[0074] Step S112, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipeline is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure.

[0075] Step S113, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0076] Step S114, restart the experiment: Open the fifth shut-off valve 41 to fill the cryogenic plunger pump 7 and heat exchanger 8 with liquid carbon dioxide from the vertical cryogenic storage tank 2, and then start the cryogenic plunger pump 7 and heat exchanger 8 so that the temperature and pressure of the temperature and pressure sensors at the outlet of heat exchanger 8 are higher than the preset temperature and pressure. Then open the third shut-off valve at the outlet of heat exchanger 8 to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump 7 and heat exchanger 8, and the experiment ends.

[0077] According to a specific embodiment of the present invention, the shutdown test of a dense-phase carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0078] Step S201, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe 12 to the tank truck liquid phase pipeline, and open the main pipeline vent valve 10 at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter 13. Stop filling after the experimental requirements are met.

[0079] Step S202, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the pressure is higher than the preset pressure, but the temperature is lower than the preset temperature;

[0080] Step S203, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0081] According to a specific embodiment of the present invention, the restart experiment of a dense-phase carbon dioxide pipeline containing impurities is carried out according to the following steps:

[0082] Step S211, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe 12 to the tank truck liquid phase pipeline, and at the same time open the main pipeline vent valve 10 to replace the gaseous carbon dioxide with liquid carbon dioxide. After the filling amount reaches the required mass for the experiment, stop filling by controlling the filling amount through the flow meter 13.

[0083] Step S212, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized to a pressure higher than the preset pressure, but the temperature is lower than the preset temperature;

[0084] Step S213, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

[0085] Step S214, restart the experiment: Open the fifth shut-off valve 41 to fill the cryogenic plunger pump 7 and heat exchanger 8 with liquid carbon dioxide from the vertical cryogenic storage tank 2, and then start the cryogenic plunger pump 7 and heat exchanger 8 so that the pressure of the temperature and pressure sensor at the outlet of heat exchanger 8 is higher than the preset pressure, but the temperature is lower than the preset temperature. Then open the third shut-off valve at the outlet of heat exchanger 8 to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump 7 and heat exchanger 8, and the experiment ends.

[0086] According to a specific embodiment of the present invention, the preset temperature is the critical temperature of the experimental gas medium, and the preset pressure is the critical pressure of the experimental gas medium.

[0087] Example 1

[0088] Figure 1 The present invention illustrates an experimental apparatus applicable to the shutdown and restart of a carbon dioxide pipeline. The apparatus is used to conduct a shutdown and restart experiment on a supercritical-dense phase carbon dioxide pipeline containing impurities, comprising the following steps:

[0089] 1. Purging and precooling: Open the main pipeline vent valve 10 at the end of the main pipeline, connect the tanker's gas phase pipeline to the main pipeline gas phase filling pipe 11, and start injecting low-temperature gaseous CO2 into the main pipeline 1 for purging and precooling.

[0090] 2. Impurity injection: Open the impurity injection valve 28-35 and the impurity gas cylinder valve 36 to inject the impurity gas into the pipe in a measured amount.

[0091] 3. Liquid CO2 filling: Connect the main pipeline liquid phase filling pipe 12 to the tank truck liquid phase pipeline, and simultaneously open the main pipeline vent valve 10. Use liquid CO2 to replace gaseous CO2. Control the filling amount through the flow meter 13 until the required mass for the experiment is reached, then stop filling.

[0092] 4. Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the tube is heated and pressurized until the required temperature, pressure and phase state are reached.

[0093] 5. Shutdown test: Natural cooling to simulate the shutdown process. Detect and record the low-frequency pressure, top fluid temperature, bottom fluid temperature, and pipe wall temperature at 11 test sections along the pipeline before and after fluid vaporization during the shutdown process.

[0094] 6. Restart Experiment: Open shut-off valves 40-41 to allow the liquid CO2 in the vertical cryogenic storage tank 2 to fill the cryogenic plunger pump 7 and heat exchanger 8. Then start the cryogenic plunger pump 7 and heat exchanger 8 to make the temperature and pressure values ​​of the temperature and pressure sensor 17 reach the required experimental values. After that, open the fifth shut-off valve 41 to allow the high-temperature and high-pressure fluid to fill the main pipe after the shutdown experiment to simulate the restart process. When the pressure at the temperature and pressure sensor 27 at the end of the test pipe reaches the requirement, stop the cryogenic plunger pump 7 and heat exchanger 8, and the experiment ends.

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. An experimental apparatus suitable for restarting a carbon dioxide pipeline after shutdown, characterized in that, It includes a main pipeline, multiple temperature and pressure sensors installed on the main pipeline, multiple impurity injection points and impurity gas cylinders; it also includes an electric heating belt installed on the main pipeline and a heating system temperature control box connected to the electric heating belt. A vertical cryogenic storage tank and a main pipeline vent valve are sequentially installed on the main pipeline. A main pipeline gas phase filling pipe and a main pipeline liquid phase filling pipe are connected between the vertical cryogenic storage tank and the main pipeline vent valve. A first shut-off valve and a second shut-off valve are respectively installed between the main pipeline vent valve and the main pipeline gas phase filling pipe and the main pipeline liquid phase filling pipe. A heat exchanger and a cryogenic plunger pump are installed on the main pipeline between the main pipeline vent valve and the vertical cryogenic storage tank. A third shut-off valve, a fourth shut-off valve, and a fifth shut-off valve are respectively installed on the main pipeline between the main pipeline vent valve and the heat exchanger, on the main pipeline between the heat exchanger and the cryogenic plunger pump, and on the main pipeline between the cryogenic plunger pump and the vertical cryogenic storage tank. The vertical cryogenic storage tank is connected to a gas phase filling port and a liquid phase filling port. A flow meter is connected to the main pipe at the other end of the third shut-off valve. Multiple temperature and pressure sensors are respectively installed at the vertical cryogenic storage tank, on the main pipe between the heat exchanger and the cryogenic plunger pump, on the main pipe between the third shut-off valve and the heat exchanger, and on the main pipe at the other end away from the third shut-off valve. Multiple impurity injection points are distributed among multiple temperature and pressure sensors on the main pipeline connected to the flow meter and far from the third shut-off valve; Multiple impurity injection points are connected to impurity gas cylinders. Impurity injection valves are installed at the inlets of each impurity injection point, and impurity gas cylinders are also equipped with impurity gas cylinder valves. A pressure relief rupture disc is also installed on the main pipeline connected to the flow meter and located away from the third shut-off valve.

2. The experimental apparatus for restarting a carbon dioxide pipeline after shutdown as described in claim 1, characterized in that, Vertical cryogenic storage tanks are equipped with vent valves.

3. The experimental apparatus for restarting a carbon dioxide pipeline after shutdown as described in claim 1, characterized in that, The vertical cryogenic storage tank is installed on the vertical cryogenic storage tank weighbridge.

4. The experimental apparatus for restarting a carbon dioxide pipeline after shutdown as described in claim 1, characterized in that, A check valve is also installed between the cryogenic plunger pump and the fourth shut-off valve.

5. An experimental method suitable for restarting a carbon dioxide pipeline after shutdown, characterized in that, The shutdown and restart experiment using the experimental apparatus for restarting a carbon dioxide pipeline as described in any one of claims 1-4 includes the following steps: Step S1: Perform an integrity check on the experimental setup applicable to the restart of a carbon dioxide pipeline after shutdown. Step S2: Inject gaseous carbon dioxide at a temperature lower than room temperature into the main pipeline through the main pipeline gas phase filling pipe to purge, pre-cool, and check the airtightness of the main pipeline. Step S3: The impurity gas is quantitatively injected from the impurity gas cylinder into the main pipeline through the impurity injection point; Step S4: Select the test pipeline, close the corresponding shut-off valve, and conduct a stop-flow test on the test pipeline; Step S5: Open the shut-off valve closed in step S4 and perform a restart test on the test pipeline.

6. The experimental method for restarting a carbon dioxide pipeline after shutdown according to claim 5, characterized in that, The shutdown and restart experiments of the test pipeline in steps S4 and S5 include shutdown and restart experiments of supercritical carbon dioxide pipeline containing impurities and shutdown and restart experiments of dense phase carbon dioxide pipeline containing impurities.

7. The experimental method for restarting a carbon dioxide pipeline after shutdown according to claim 6, characterized in that, The shutdown experiment for supercritical carbon dioxide containing impurities in a pipeline was conducted according to the following steps: Step S101, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met. Step S102, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipeline is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure. Step S103, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

8. The experimental method for restarting a carbon dioxide pipeline after shutdown according to claim 6, characterized in that, The restart experiment of a supercritical carbon dioxide pipeline containing impurities was conducted according to the following steps: Step S111, Liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met. Step S112, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the temperature is higher than the preset temperature and the pressure is higher than the preset pressure. Step S113, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process. Step S114, restart the experiment: Open the fifth shut-off valve to fill the cryogenic plunger pump and heat exchanger with liquid carbon dioxide from the vertical cryogenic storage tank, and then start the cryogenic plunger pump and heat exchanger so that the temperature and pressure of the temperature and pressure sensors at the heat exchanger outlet are higher than the preset temperature and pressure. Then open the third shut-off valve at the heat exchanger outlet to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump and heat exchanger, and the experiment ends.

9. The experimental method for restarting a carbon dioxide pipeline after shutdown according to claim 6, characterized in that, The shutdown test of a dense-phase carbon dioxide pipeline containing impurities shall be conducted according to the following steps: Step S201, liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter and stop filling after the experimental requirements are met. Step S202, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized until the pressure is higher than the preset pressure, but the temperature is lower than the preset temperature; Step S203, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process.

10. The experimental method for restarting a carbon dioxide pipeline after shutdown according to claim 6, characterized in that, The restart experiment for a dense-phase carbon dioxide pipeline containing impurities shall be conducted according to the following steps: Step S211, Liquid carbon dioxide filling: Connect the main pipeline liquid phase filling pipe to the tank truck liquid phase pipeline, and open the main pipeline vent valve at the same time. Use liquid carbon dioxide to replace gaseous carbon dioxide. Control the filling amount through the flow meter to reach the required mass for the experiment and then stop filling. Step S212, Phase establishment: The temperature and power of the electric heating belt are controlled by the temperature control box of the heating system, so that the fluid in the test pipe is heated and pressurized to a pressure higher than the preset pressure, but the temperature is lower than the preset temperature; Step S213, Shutdown Experiment: Turn off the temperature control box of the heating system and allow the fluid in the test pipeline to cool down naturally to the ambient temperature to simulate the shutdown process. Detect and record the low-frequency pressure, fluid temperature at the top of the pipe, fluid temperature at the bottom of the pipe, and pipe wall temperature at the test section along the pipeline before and after the fluid vaporization during the shutdown process. Step S214, restart the experiment: Open the fifth shut-off valve to fill the cryogenic plunger pump and heat exchanger with liquid carbon dioxide from the vertical cryogenic storage tank, and then start the cryogenic plunger pump and heat exchanger so that the pressure of the temperature and pressure sensor at the heat exchanger outlet is higher than the preset pressure, but the temperature is lower than the preset temperature. Then open the third shut-off valve at the heat exchanger outlet to allow fluid to fill the test pipeline after the shutdown experiment to simulate the restart process. When the pressure at the end of the test pipeline is higher than the preset pressure, stop the cryogenic plunger pump and heat exchanger, and the experiment ends.

11. The experimental method for restarting a carbon dioxide pipeline after shutdown according to any one of claims 7-10, characterized in that, The preset temperature is the critical temperature of the experimental gas medium, and the preset pressure is the critical pressure of the experimental gas medium.

Images