阅读说明：本技术 输气管道喷射火对邻近液烃管安全性影响实验平台及方法 (Experimental platform and method for influence of gas pipeline fire injection on safety of adjacent liquid hydrocarbon pipes ) 是由 何国玺 黄元洁 廖柯熹 王帅 陈迪 于 2020-11-30 设计创作，主要内容包括：本发明公开了一种输气管道喷射火对邻近液烃管安全性影响实验平台及方法,所述实验平台包括供液烃环道系统、检测系统、以及火焰系统；供液烃环道系统包括依次相连形成闭合回路的液烃储罐、管道泵、非测试管段一、测试管段、非测试管段二,液烃储罐与冷却装置相连,液烃储罐与管道泵之间设有出液烃管,出液烃管上设有截断阀,非测试管段二上设有排气阀；检测系统包括流量检测装置、压力检测装置、温度检测装置一、温度检测装置二、温度检测装置三、温度检测装置四、温度检测装置五；火焰系统位于闭合回路外,且处于测试管段两端之间的平面内。本发明能够用来开展气液相邻管道流动状态下天然气管道泄漏后气体燃烧对液烃管道的热影响实验研究。(The invention discloses an experimental platform and a method for influencing the safety of an adjacent liquid hydrocarbon pipe by the fire sprayed by a gas transmission pipeline, wherein the experimental platform comprises a liquid hydrocarbon supply loop system, a detection system and a flame system; the liquid hydrocarbon supply loop system comprises a liquid hydrocarbon storage tank, a pipeline pump, a non-testing pipe section I, a testing pipe section and a non-testing pipe section II which are sequentially connected to form a closed loop, wherein the liquid hydrocarbon storage tank is connected with a cooling device, a liquid hydrocarbon outlet pipe is arranged between the liquid hydrocarbon storage tank and the pipeline pump, a cut-off valve is arranged on the liquid hydrocarbon outlet pipe, and an exhaust valve is arranged on the non-testing pipe section II; the detection system comprises a flow detection device, a pressure detection device, a first temperature detection device, a second temperature detection device, a third temperature detection device, a fourth temperature detection device and a fifth temperature detection device; the flame system is located outside the closed loop and in a plane between the ends of the test tube section. The device can be used for carrying out experimental research on the thermal influence of gas combustion on the liquid hydrocarbon pipeline after the natural gas pipeline leaks in the flowing state of the gas-liquid adjacent pipelines.)

1. An experiment platform for influencing the safety of an adjacent liquid hydrocarbon pipe by a gas transmission pipeline jet fire is characterized by comprising a liquid hydrocarbon supply loop system, a detection system and a flame system;

the liquid hydrocarbon supply loop system comprises a liquid hydrocarbon storage tank, a pipeline pump, a non-testing pipe section I, a testing pipe section and a non-testing pipe section II which are sequentially connected to form a closed loop, wherein the liquid hydrocarbon storage tank is connected with a cooling device, a liquid hydrocarbon outlet pipe is arranged between the liquid hydrocarbon storage tank and the pipeline pump, a cut-off valve is arranged on the liquid hydrocarbon outlet pipe, and an exhaust valve is arranged on the non-testing pipe section II;

the detection system comprises a flow detection device, a pressure detection device and a temperature detection device I which are arranged on the non-test pipe section I, a temperature detection device II which is arranged at two ends of the test pipe section, a temperature detection device III which is arranged on the inner wall and the outer wall of the test pipe section, a temperature detection device IV which detects the temperature of fluid in the test pipe section, and a temperature detection device V which is arranged in the liquid hydrocarbon storage tank;

the flame system is located outside the closed loop and in a plane between the ends of the test tube section.

2. The gas pipeline fire spray experiment platform of claim 1, wherein the cooling device is a heat exchange coil disposed in the liquid hydrocarbon storage tank.

3. The gas pipeline fire injection experiment platform for influencing the safety of adjacent liquid hydrocarbon pipes according to claim 2, wherein the heat exchange coil is designed according to the following method:

combining the known parameters, the size of the liquid hydrocarbon storage tank, the burning time of the test pipe section, the physical properties of a flowing medium in the container, the initial temperature and the target temperature of burning, adopting clear water as the heat exchange medium in the heat exchange coil, setting the initial temperature and the initial flow rate, performing simulation calculation by using fluid dynamics software, and selecting the material and the pipe diameter of the heat exchange coil;

the selection of the inner diameter and the outer diameter of the pipe is to simulate different pipe diameters and different wall thicknesses in fluid dynamics software, and finally, the diameter and the wall thickness of the corresponding heat exchange coil pipe are selected according to the outlet temperature of heat exchange clean water so as to ensure that the heat taken away by the heat exchange coil pipe can enable the liquid supply hydrocarbon pipeline system to continuously and safely flow in a circulating manner;

in the determination of the tube pass parameters, the screw pitch is set to be 0.5 times of the diameter of the coil, and the outer diameter of the coil is obtained according to the design height of the coil, so that the number of coil turns can be calculated.

4. The gas pipeline fire injection testing platform of claim 1, wherein the vent valve is disposed proximate to the liquid hydrocarbon storage tank.

5. The gas transmission pipeline fire injection experiment platform for influencing safety of adjacent liquid hydrocarbon pipes according to claim 1, wherein the first non-test pipe section and the second non-test pipe section are both composed of straight pipe sections and bent pipe sections, the test pipe sections are straight pipe sections, and the liquid hydrocarbon supply loop system is integrally in a round-corner rectangular loop shape.

6. The gas pipeline fire-jet safety impact experiment platform adjacent to the liquid hydrocarbon pipeline as claimed in claim 5, wherein the distance between the bent pipe section on the first non-test pipe section closest to the test pipe section and the distance between the bent pipe section on the second non-test pipe section closest to the test pipe section and the test pipe section are respectively in the range of 8D-15D, and D is the diameter of the test pipe section.

7. The gas pipeline fire injection safety impact experiment platform adjacent to the liquid hydrocarbon pipeline as claimed in claim 1, wherein the third temperature detection device is a thermocouple temperature sensor, and the fourth temperature detection device is a thermal resistance temperature sensor.

8. The gas pipeline fire injection experiment platform of claim 7, wherein the thermocouple temperature sensor is a K-type integrated temperature transmitter, and the thermal resistance temperature sensor is an armored platinum temperature sensor.

9. An experiment method for influence of gas pipeline fire injection on safety of adjacent liquid hydrocarbon pipes is characterized in that the experiment is carried out by adopting the experiment platform for influence of gas pipeline fire injection of any one of claims 1 to 8 on safety of adjacent liquid hydrocarbon pipes, and comprises the following steps:

checking the tightness of the loop platform, and recording the temperature, the humidity and the pressure of the environment; starting a cut-off valve, a pipeline pump and an exhaust valve to fill the loop with the liquid hydrocarbon, and enabling the liquid hydrocarbon to circularly flow in the loop at a constant speed; starting a flame system for combustion, starting a cooling device to ensure that the fluid in the loop flows in a safe and circular manner, and detecting the temperature of the fluid in the pipeline of the test pipe section, the temperature of the inner wall and the outer wall of the pipeline, and the pressure and temperature change data in the loop by a detection system in the combustion process; closing the flame system to complete the combustion process; closing a valve of the liquid hydrocarbon storage tank, and stopping the flow of the fluid in the loop; disassembling the loop platform, and taking down the test pipe section for metallographic analysis;

recording data of the combustion width, the distance between the flame nozzle and the test pipe section, the ambient temperature, the ambient humidity, the ambient pressure and the ambient wind speed before the experiment;

recording data of combustion time, heat conductivity coefficient, expansion coefficient, specific heat capacity, density, liquid hydrocarbon viscosity, pipeline outer wall temperature, pipeline inner wall temperature, liquid hydrocarbon temperature in a pipe, pressure, flow rate, pipeline stress, pipeline strain and flame intensity in an experiment;

recording metallographic analysis results, tensile strength, hardness and impact toughness data of the tested pipe section after the experiment;

changing different experimental conditions, and the steps are carried out; the experimental conditions comprise the fluid flow rate, the material of the test pipe section, the pipe diameter of the test pipe section, the wall thickness of the test pipe section, the length of the test pipe section, the flame size of the flame system, the distance between the flame system and the test pipe section and the combustion time of the flame system.

10. The experimental method for testing the safety influence of the gas pipeline fire on the adjacent liquid hydrocarbon pipes is characterized by further comprising the following steps:

according to data before and in the experiment, the relation of pressure, flow velocity, pipeline stress and strain in the pipeline along with temperature is analyzed, the critical flow velocity of liquid hydrocarbon in the adjacent liquid hydrocarbon conveying pipeline after the natural gas pipeline is in a fire is determined, and the failure time of the pipeline is predicted;

and determining the failure mode and the maximum yield strength of the pipeline according to the data after the experiment.

Technical Field

The invention relates to the technical field of petroleum and natural gas pipeline transportation safety, in particular to an experiment platform and method for influences of gas pipeline jet fire on safety of adjacent liquid hydrocarbon pipes.

Background

The pipeline is the most economic and reasonable transportation mode acknowledged by the petroleum and natural gas industry, and with the continuous development of the domestic economic level and the increase of the energy demand, the situation that a plurality of pipelines are laid in parallel for medium transportation is rare at present in the climax period of pipeline construction. Parallel gas-liquid pipelines, especially pipelines laid in parallel in a close distance, can bring certain challenges to the safe operation of the pipelines. If the natural gas pipeline explosion accident occurs in two or three parallel pipe sections, especially the pipe sections in the same ditch, the same tunnel and the same bridge, serious consequences can be caused to adjacent conveying pipelines, and great risks are brought. At present, relevant documents concentrate on determination of safe laying intervals of parallel gas-liquid pipelines and risk analysis in design and construction stages, but among all risk factors of the parallel gas-liquid pipelines, the maximum influence on the safety of the pipelines is in the operation stage of the parallel gas-liquid pipelines, so that the research on the influence of natural gas pipelines on adjacent conveying pipelines when a combustion and explosion accident occurs is very necessary. In addition, considering that the parallel gas-liquid pipelines are mostly parallel to the petroleum gas pipelines, if the invalid natural gas pipeline burns the adjacent liquid hydrocarbon pipelines all the time, the liquid hydrocarbon pipelines may deform or explode, and at the moment, the liquid hydrocarbon leaks to pollute the soil, which brings long-term adverse effects on public health and ecological environment. Therefore, the research on the thermal influence experiment of the combustion of the natural gas pipeline in the flowing state of the adjacent pipelines has very important engineering practical significance.

Disclosure of Invention

Aiming at the problems, the invention aims to provide an experimental platform and method for influence of gas pipeline jet fire on the safety of adjacent liquid hydrocarbon pipes.

The technical scheme of the invention is as follows:

on one hand, the experiment platform for the influence of the gas transmission pipeline jet fire on the safety of the adjacent liquid hydrocarbon pipe comprises a liquid hydrocarbon supply loop system, a detection system and a flame system;

the liquid hydrocarbon supply loop system comprises a liquid hydrocarbon storage tank, a pipeline pump, a non-testing pipe section I, a testing pipe section and a non-testing pipe section II which are sequentially connected to form a closed loop, wherein the liquid hydrocarbon storage tank is connected with a cooling device, a liquid hydrocarbon outlet pipe is arranged between the liquid hydrocarbon storage tank and the pipeline pump, a cut-off valve is arranged on the liquid hydrocarbon outlet pipe, and an exhaust valve is arranged on the non-testing pipe section II;

the detection system comprises a flow detection device, a pressure detection device and a temperature detection device I which are arranged on the non-test pipe section I, a temperature detection device II which is arranged at two ends of the test pipe section, a temperature detection device III which is arranged on the inner wall and the outer wall of the test pipe section, a temperature detection device IV which detects the temperature of fluid in the test pipe section, and a temperature detection device V which is arranged in the liquid hydrocarbon storage tank;

the flame system is located outside the closed loop and in a plane between the ends of the test tube section.

Preferably, the cooling device is a heat exchange coil arranged in the liquid hydrocarbon storage tank.

Preferably, the heat exchange coil is designed according to the following method:

combining the known parameters, the size of the liquid hydrocarbon storage tank, the burning time of the test pipe section, the physical properties of a flowing medium in the container, the initial temperature and the target temperature of burning, adopting clear water as the heat exchange medium in the heat exchange coil, setting the initial temperature and the initial flow rate, performing simulation calculation by using fluid dynamics software, and selecting the material and the pipe diameter of the heat exchange coil;

the selection of the inner diameter and the outer diameter of the pipe is to simulate different pipe diameters and different wall thicknesses in fluid dynamics software, and finally, the diameter and the wall thickness of the corresponding heat exchange coil pipe are selected according to the outlet temperature of heat exchange clean water so as to ensure that the heat taken away by the heat exchange coil pipe can enable the liquid supply hydrocarbon pipeline system to continuously and safely flow in a circulating manner;

in the determination of the tube pass parameters, the screw pitch is set to be 0.5 times of the diameter of the coil, and the outer diameter of the coil is obtained according to the design height of the coil, so that the number of coil turns can be calculated.

Preferably, the vent valve is disposed proximate to the liquid hydrocarbon storage tank.

Preferably, the first non-test pipe section and the second non-test pipe section are both composed of a straight pipe section and a bent pipe section, the test pipe section is a straight pipe section, and the whole liquid supply hydrocarbon loop system is in a round-corner rectangular loop shape.

Preferably, the distance between the bent pipe section closest to the test pipe section on the non-test pipe section one and the test pipe section and the distance between the bent pipe section closest to the test pipe section on the non-test pipe section two and the test pipe section are respectively in the range of 8D-15D, and D is the diameter of the test pipe section.

Preferably, the third temperature detection device is a thermocouple temperature sensor, and the fourth temperature detection device is a thermal resistance temperature sensor.

Preferably, the thermocouple temperature sensor is a K-type integrated temperature transmitter, and the thermal resistance temperature sensor is an armored platinum temperature sensor.

In another aspect, an experiment method for the influence of the gas pipeline fire injection on the safety of the adjacent liquid hydrocarbon pipes is provided, and the experiment is carried out by using the experiment platform for the influence of the gas pipeline fire injection on the safety of the adjacent liquid hydrocarbon pipes, and comprises the following steps:

checking the tightness of the loop platform, and recording the temperature, the humidity and the pressure of the environment; starting a cut-off valve, a pipeline pump and an exhaust valve to fill the loop with the liquid hydrocarbon, and enabling the liquid hydrocarbon to circularly flow in the loop at a constant speed; starting a flame system for combustion, starting a cooling device to ensure that the fluid in the loop flows in a safe and circular manner, and detecting the temperature of the fluid in the pipeline of the test pipe section, the temperature of the inner wall and the outer wall of the pipeline, and the pressure and temperature change data in the loop by a detection system in the combustion process; closing the flame system to complete the combustion process; closing a valve of the liquid hydrocarbon storage tank, and stopping the flow of the fluid in the loop; disassembling the loop platform, and taking down the test pipe section for metallographic analysis;

recording data of the combustion width, the distance between the flame nozzle and the test pipe section, the ambient temperature, the ambient humidity, the ambient pressure and the ambient wind speed before the experiment;

recording data of combustion time, heat conductivity coefficient, expansion coefficient, specific heat capacity, density, liquid hydrocarbon viscosity, pipeline outer wall temperature, pipeline inner wall temperature, liquid hydrocarbon temperature in a pipe, pressure, flow rate, pipeline stress, pipeline strain and flame intensity in an experiment;

recording metallographic analysis results, tensile strength, hardness and impact toughness data of the tested pipe section after the experiment;

changing different experimental conditions, and the steps are carried out; the experimental conditions comprise the fluid flow rate, the material of the test pipe section, the pipe diameter of the test pipe section, the wall thickness of the test pipe section, the length of the test pipe section, the flame size of the flame system, the distance between the flame system and the test pipe section and the combustion time of the flame system.

Preferably, the method further comprises the following steps: according to data before and in the experiment, the relation of pressure, flow velocity, pipeline stress and strain in the pipeline along with temperature is analyzed, the critical flow velocity of liquid hydrocarbon in the adjacent liquid hydrocarbon conveying pipeline after the natural gas pipeline is in a fire is determined, and the failure time of the pipeline is predicted; and determining the failure mode and the maximum yield strength of the pipeline according to the data after the experiment.

The invention has the beneficial effects that:

the invention can be used for carrying out the experimental study on the heat influence of the combustion of the natural gas pipeline in the flowing state of the adjacent pipelines, can comprehensively study the heat influence generated by the combustion of the natural gas pipeline in the flowing state of the adjacent pipelines, and can determine the critical flow rate of the natural gas pipeline to the adjacent conveying pipelines during the combustion by microcosmic metallographic analysis and combining the strength change rule of the pipe and the failure condition of the pipeline.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an experimental platform for the influence of a gas pipeline fire jet on the safety of an adjacent liquid hydrocarbon pipe;

FIG. 2 is a schematic structural diagram of an embodiment of a test pipe section of an experimental platform for the influence of a gas pipeline fire jet on the safety of an adjacent liquid hydrocarbon pipe.

Reference numbers in the figures: the system comprises a liquid hydrocarbon storage tank 1, a pipeline pump 2, a non-testing pipe section I3, a testing pipe section 4, a non-testing pipe section II 5, a liquid hydrocarbon outlet pipe 6, a cut-off valve 7, an exhaust valve 8, a flow detection device 9, a pressure detection device 10, a temperature detection device I11, a temperature detection device II 12, a temperature detection device III 13, a temperature detection device IV 14, a temperature detection device V15, a cooling device 16 and a flame system 17.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

It should be noted that, in the present application, the embodiments and the technical features of the embodiments may be combined with each other without conflict.

It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

In the present invention, the terms "first", "second", and the like are used for distinguishing similar objects, but not for describing a particular order or sequence order, unless otherwise specified. It is to be understood that the terms so used; the terms "upper", "lower", "left", "right", and the like are used generally with respect to the orientation shown in the drawings, or with respect to the component itself in a vertical, or gravitational orientation; likewise, "inner", "outer", and the like refer to the inner and outer relative to the contours of the components themselves for ease of understanding and description. The above directional terms are not intended to limit the present invention.

As shown in fig. 1-2, the present invention provides an experimental platform for testing the influence of a gas pipeline fire jet on the safety of an adjacent liquid hydrocarbon pipe, which comprises a liquid hydrocarbon supply loop system, a detection system, and a flame system 17;

the liquid hydrocarbon supply loop system comprises a liquid hydrocarbon storage tank 1, a pipeline pump 2, a non-testing pipe section I3, a testing pipe section 4 and a non-testing pipe section II 5 which are sequentially connected to form a closed loop, wherein a liquid hydrocarbon outlet pipe 6 is arranged between the liquid hydrocarbon storage tank 1 and the pipeline pump 2, a cut-off valve 7 is arranged on the liquid hydrocarbon outlet pipe 6, and an exhaust valve 8 is arranged on the non-testing pipe section II 5;

the detection system comprises a flow detection device 9, a pressure detection device 10, a temperature detection device I11, a temperature detection device II 12, a temperature detection device III 13 and a temperature detection device IV 14, wherein the flow detection device 9, the pressure detection device 10 and the temperature detection device I11 are arranged on the non-test pipe section I3;

the flame system 17 is located outside the closed circuit and in a plane between the two ends of the test tube section 4.

In order to control the temperature of the liquid hydrocarbon, optionally, the gas pipeline fire injection safety influence experiment platform adjacent to the liquid hydrocarbon pipe further comprises a temperature detection device five 15 and a cooling device 16, wherein the temperature detection device five 15 is arranged in the liquid hydrocarbon storage tank 1, and the cooling device 16 is connected with the liquid hydrocarbon storage tank 1. In a specific embodiment, the cooling device 16 is a heat exchange coil disposed in the liquid hydrocarbon storage tank 1, and the heat exchange coil is designed according to the following method:

according to the known parameters, the size of the liquid hydrocarbon storage tank, the combustion time of the heating pipeline, the physical properties of the flowing medium in the container, the initial temperature and the target temperature of combustion, and clear water in the heat exchange coil pipe are used as the heat exchange medium, the initial temperature and the initial flow rate can be set, calculation is carried out by using a related algorithm, and the material and the pipe diameter of the heat exchange coil pipe can be selected. When the pipe of the test heating section changes, the heat exchange amount of the heat exchange pipe and the temperature change of water in the heat exchange coil pipe are different, and a proper test pipe section can be selected by combining economic factors; the selection of the inner diameter and the outer diameter of the tube is to simulate different tube diameters and different wall thicknesses in related software, and finally, the diameter and the wall thickness of the heat exchange coil are selected according to the outlet temperature of heat exchange clean water; in the determination of the tube pass parameters, the thread pitch can be set to 0.5 times the diameter of the coil, and the outer diameter of the coil can be obtained according to the design height of the coil, so that the number of coil turns can be calculated. Therefore, according to the steps, the related parameters of the heat exchange coil can be finally determined: the specification of the pipe and the thread pitch are 0.5 of the outer diameter of the pipe, the diameter of the coil pipe and the height of the coil pipe.

It should be noted that the cooling device 16 is used to reduce the temperature of the liquid hydrocarbon, and other cooling devices of the prior art may be used besides the heat exchange coil in the above embodiment, and the above embodiment is not intended to limit the cooling device of the present invention.

When the liquid hydrocarbon is filled, in order to exhaust gas in the pipeline more quickly, the liquid hydrocarbon is made to completely fill the experimental pipe section to reach a full flow state, and optionally, the exhaust valve 8 is arranged close to the liquid hydrocarbon storage tank 1.

In a specific embodiment, each of the first non-test pipe section 3 and the second non-test pipe section 5 is composed of a straight pipe section and a bent pipe section, the bent pipe section adopts a 90-degree elbow, the test pipe section 4 is a straight pipe section, and the whole liquid hydrocarbon supply loop system is in a rounded rectangular loop shape.

In order to be able to ignore the influence of the fluid passing through the bend section on the test pipe section, optionally, the distance between the bend section of the non-test pipe section one 3 closest to the test pipe section 4 and the distance between the bend section of the non-test pipe section two 5 closest to the test pipe section and the test pipe section 4 are respectively in the range of 8D-15D, where D is the diameter of the test pipe section 4.

In order to improve the accuracy of the temperature detection device in the high-temperature environment and avoid the influence on data acquisition caused by the possible failure of the temperature detection device in the high-temperature environment, optionally, the third temperature detection device 13 is a thermocouple temperature sensor, the thermocouple temperature sensor is a K-type integrated temperature transmitter, the fourth temperature detection device 14 is a thermal resistance temperature sensor, and the thermal resistance temperature sensor is an armored platinum temperature sensor.

In a specific embodiment, the temperature detecting devices three 13 and four 14 are provided in plurality and are uniformly distributed in the axial direction and the radial direction of the test tube segment 4, respectively. Optionally, the third temperature detection device 13 arranged on the inner wall of the test pipe section 4 and the third temperature detection device 13 arranged on the outer wall of the test pipe section 4 in the same radial direction are arranged opposite to each other.

The experimental platform for the influence of the gas pipeline jet fire on the safety of the adjacent liquid hydrocarbon pipes can be used for carrying out the heat influence experimental research on the combustion of the natural gas pipeline under the flowing state of the adjacent pipelines. When the device is used for carrying out experiments, the size of the loop can be selected as required, and the proper liquid hydrocarbon storage tank 1 and the pipeline pump 2 are determined according to the size of the loop, so that the liquid hydrocarbon in the loop is ensured to keep a continuous flowing state, and the flowing scene of a field liquid hydrocarbon pipeline can be really restored. After the selection, the flange is adopted for pipeline connection, so that the pipe can be conveniently detached, and different pipe diameters and pipes (pipes with different wall thicknesses, pipe diameters and materials) can be replaced according to the experiment purpose. In the experimental process, through the arranged detection system, the temperature change conditions of the inner wall and the outer wall of the pipeline of the test pipe section 4 and the liquid hydrocarbon in the pipeline can be obtained by utilizing the third temperature detection device 13 and the fourth temperature detection device 14, and the temperature change conditions of the flowing medium in the pipeline can be monitored by utilizing the second temperature detection device 12. The flame system can simulate the combustion state of a natural gas pipeline, and heat influence research experiments under different fire scenes can be carried out by adjusting the size and the distance of flame. Through the discharge valve that sets up, open this valve when filling liquid hydrocarbon, can the gas in the exhaust pipe, make liquid hydrocarbon fill up the experiment pipeline section completely, reach the full flow state.

In a specific embodiment, the maximum flow of the gas pipeline jet fire on the safety influence experiment platform of the adjacent liquid hydrocarbon pipe is 60m³H, the pipe diameters of the non-test pipe section I3, the test pipe section 4 and the non-test pipe section II 5 are the same and are D114 multiplied by 7.1mm, the total length of the straight pipe is 10m, the liquid hydrocarbon storage volume is 510L, and the total occupied area of the loop is about 14m². The main equipment parameters of the experimental platform for influencing the safety of the adjacent liquid hydrocarbon pipe by the gas pipeline fire are shown in the table 1:

TABLE 1 gas pipeline jet fire impact on safety of neighboring liquid hydrocarbon pipe experiment platform main equipment parameters

In the above embodiment, the third temperature detection device 13 and the fourth temperature detection device 14 are further respectively connected to a data acquisition instrument (not shown in the figure), and the data acquisition instrument can acquire temperature change data in the experimental process in real time. The pumps, valves, pressure gauges, thermometers and temperature sensors are also connected with a central control room (not shown in the figure) through a PLC control cabinet.

In the above embodiment, the parameters of the heat exchange coil are determined by the following steps:

experimentally known parameters include: the size of the liquid hydrocarbon storage tank is 510L, the flame combustion time is estimated to be 2 hours, the flowing medium in the loop is diesel liquid hydrocarbon, water is adopted in the heat exchange coil pipe as the heat exchange medium, the initial temperature is set to be 20 ℃, the flow speed is set to be 1m/s, and the pipe is selected to be low-carbon steel by combining economic factors. Selecting pipes with different pipe diameters from 21-38 mm and under the condition of different wall thicknesses in terms of selection of the inner diameter and the outer diameter of the pipe, and finally selecting D32 multiplied by 2.5 according to the outlet temperature of water; the pipe pass parameters are determined, the screw pitch is set to be 0.5 times of the diameter of the coil pipe, the outer diameter of the coil pipe can be known according to the design height of the coil pipe of 0.7m, and 15 turns are needed. Therefore, the parameters of the final heat exchange coil are D32 multiplied by 2.5, the thread pitch is 0.5 tube external diameter, the diameter of the coil is 0.7m, and the height is 0.7 m.

The liquid hydrocarbon storage tank 1 in the above embodiment stores finished liquid hydrocarbons; the explosion-proof pipeline pump can provide power to ensure stable pipeline liquid flow and prevent explosion in the flowing process of the heating liquid hydrocarbon. The shut-off valve 7 on the pipeline can facilitate the control of the experimental process. The specification of the elbow in the loop is R1.5D, the distance between an experimental pipe section for a combustion test and the elbow is 100cm, and the influence of fluid passing through the elbow on the experimental pipe section can be ignored in the experiment within the range of 8D-15D. The heat exchange medium in the heat exchange coil is clean water, and the heat of the liquid hydrocarbon is taken away through continuous circular flow. The thermometer can monitor the temperature change of the liquid hydrocarbon in the liquid hydrocarbon storage tank at any time. The flowmeter is arranged behind the pump and can determine the flow rate of the pipeline under the current condition. A manometer and a thermometer are arranged behind the anti-explosion pipeline pump, and the initial pressure value and the temperature value of liquid flowing can be detected. The front and the back of the test pipe section are provided with thermometers which can observe the temperature change of the fluid in the pipeline. Meanwhile, temperature sensors are arranged on the inner wall and the outer wall of the test pipe section, so that the temperature change of the inner wall and the outer wall of the pipeline in a combustion state can be transmitted in real time. All pumps, valves, pressure gauges, temperature gauges and temperature sensors are connected to a central control room through a PLC control cabinet so as to control switches and collect data. And all components of the loop are connected by flanges, so that the assembly and disassembly are convenient.

After the experimental platform for the influence of the gas transmission pipeline fire injection on the safety of the adjacent liquid hydrocarbon pipe is built, a tightness experiment needs to be carried out, and the operation steps are as follows:

the circuit is filled with water, pressurized by a pump and held for a certain time. The reading of the pressure gauge is kept stable, which indicates that the loop sealing performance is good. Through the test of water and pressure tests, the sealing performance of the loop is good, and the loop has no water leakage phenomenon under the maximum pressure head provided by the explosion-proof pipeline pump. Meanwhile, the installation of the flange needs to check the form, the size, the material and the like of the gasket and the flange in detail, and ensure that the bolts meet the corresponding installation requirements; the surface of the flange is kept free from corrosion damage, mechanical damage, old gasket residue and the like. At the same time, the roughness of the flange needs to be checked, the boss can be aligned, the gap between the flange surface and the flange surface is proper, and the parallelism of the planes of the two front surfaces can meet the form of the corresponding gasket.

By combining various research methods such as temperature change and thermal radiation influence range caused by natural gas pipeline combustion, the experimental platform for influence of gas pipeline jet fire on the safety of the adjacent liquid hydrocarbon pipes is utilized to carry out experimental research on the influence of natural gas pipeline combustion on the adjacent pipelines under the flowing condition.

In the experimental process, the combustion temperature of the natural gas can be obtained by solving methods such as a direct solution method, an iteration method, an interpolation method, a specific heat approximation method and the like according to the combustion state principle of the natural gas pipeline, so that the temperature of external flame can be determined.

The specific parallel gas-liquid pipeline exposed section combustion loop experiment comprises the following steps:

checking a liquid hydrocarbon storage tank, valves, flanges, an explosion-proof pipeline pump and the like; calibrating and checking a manometer and a thermometer and calibrating and checking a temperature sensor; checking the safety of the flame spray head and checking the filling of fuel gas; recording the temperature, humidity and pressure of the environment at the moment; opening a valve of the liquid hydrocarbon storage tank, and adjusting an explosion-proof pipeline pump to enable the flow rate of fluid in the pipeline to be in a constant speed state; sixthly, simultaneously opening an exhaust valve to exhaust gas in the pipeline, wherein liquid hydrocarbon in the pipeline is in a full flow state; opening a flame nozzle valve to burn, adjusting the flame size, the distance between the flame nozzle and the test pipe section, the length of the flame combustion test pipe section and the flame combustion time, and collecting the data of the fluid temperature inside the test pipe, the temperature of the inner wall and the outer wall of the pipe, the pressure inside the loop and the temperature change every 1 s; eighthly, closing a flame nozzle valve to finish the combustion process; closing the valve of the liquid hydrocarbon storage tank and stopping the fluid flow in the pipe; ninthly, disassembling related experimental instruments, checking or maintaining, taking down the combustion test pipe section, and performing metallographic analysis; and (3) changing the fluid flow rate at the red (R) part or replacing the test sections with different materials, different pipe diameters and different wall thicknesses, and repeating the steps to finish the combustion experiment under the pipeline flowing state under various different conditions.

Data before, during and after the experiment are collected, wherein the data before the experiment comprise the combustion width, the distance between a flame nozzle and a test pipe section, the ambient temperature, the ambient humidity, the ambient pressure, the ambient wind speed and the like. The data collected in the experiment include combustion time, thermal conductivity, expansion coefficient, specific heat capacity, density, liquid hydrocarbon viscosity, pipe outer wall temperature, pipe inner wall temperature, pipe liquid hydrocarbon temperature, pressure, flow rate, pipe stress, pipe strain, flame intensity, etc. The data collected after the experiment include the metallographic analysis result, tensile strength, hardness, impact toughness and the like of the test pipe section.

After the experiment is finished, the recorded data is utilized to analyze the relation of pressure, flow velocity, pipeline stress and strain in the pipeline along with temperature, the critical flow velocity of liquid hydrocarbon in the adjacent liquid hydrocarbon conveying pipeline after the natural gas pipeline is in a fire is determined, and the failure time of the pipeline is predicted. After the experiment, the material properties such as metallographic structure, tensile strength, hardness, impact toughness and the like of the pipeline at the experimental test section are analyzed, the damage form, the maximum yield strength and the like of the pipeline are determined, and a corresponding pipeline protection strategy is provided as a basis.

Specifically, the critical flow rate, the pipe aging time, the pipeline failure mode and the maximum yield strength are obtained by replacing different experimental conditions, the combustion results of the test pipe section under different experimental conditions are obtained, and judgment is carried out according to the combustion results and the reaction in the combustion process. For example, the flow rates of the liquid hydrocarbons in different pipelines and the burning resistant time of the corresponding test pipe sections are different, the burning resistant time of the corresponding test pipe section under each flow rate condition is obtained by changing the flow rates of the liquid hydrocarbons in different pipelines, and the flow rate which can make the burning resistant time of the test pipe section longest is selected as the critical flow rate according to the burning resistant time of the test pipe section. The critical flow rate of the present invention means that the combustion-resistant time is short when the critical flow rate is less than the critical flow rate, and the combustion-resistant time cannot be prolonged when the critical flow rate is more than the critical flow rate. The critical flow rate is determined, so that the burning resistance time of the pipe is longer, and the time is won for emergency repair and maintenance. And after the critical flow rate is determined, keeping the speed of the liquid hydrocarbon in the pipeline as the critical flow rate, continuing to burn, and determining the failure time of the pipe according to the temperature change of the test pipe section and the tolerance temperature of the selected material of the test pipe section. Continuing the combustion, the test tube segment is observed for failure modes, such as fracture, split, or rupture. And after the failure time is determined, testing the yield strength of the current test pipe section, wherein the corresponding value is the maximum yield strength.

In conclusion, the heat influence generated by combustion of the natural gas pipeline in the flowing state of the adjacent pipeline can be comprehensively researched, and the critical flow velocity of the natural gas pipeline to the adjacent conveying pipeline during combustion can be determined by virtue of microscopic metallographic analysis and combination of the strength change rule of the pipe and the failure condition of the pipeline.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.