A safe filling system and filling method for liquid ethane pipeline after maintenance

Abstract

The present invention discloses a safe filling system and filling method for liquid ethane pipeline after maintenance, including a trunk system, a trunk valve chamber system, an ethane filling system and a pipeline temperature and pressure detection system. The trunk valve chamber system is responsible for the venting and restarting of the upstream and downstream pipelines of the valve chamber, and also provides a channel for replacing the trunk pipeline. The ethane filling system is used to introduce ethane from the upstream trunk before the downstream trunk is restarted, and then heat and adjust the temperature to send it to the downstream trunk to be restarted. According to the functional requirements of restarting the liquid ethane pipeline after maintenance and discharge, based on the low-pressure vaporization and low-temperature characteristics of liquid ethane, the present invention adopts measures such as using the valve chamber bypass of the upstream pipe section to provide a filling medium channel, vaporizing and heating the external equipment of the initial filling medium, and boosting and liquefying during the middle and late filling, so as to effectively control the low temperature problem of the medium during the filling process of the isolated maintenance section of the liquid ethane pipeline, ensure the safe operation of the liquid ethane pipeline, and provide effective guarantee for the safe operation of the liquid ethane pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid ethane pipeline production after overhaul, and particularly relates to a liquid ethane pipeline safety filling system and filling method after overhaul. Background Art

[0002] With the development of natural gas processing technology and the development of natural gas efficient utilization technology, the recovery capacity of ethane in natural gas is constantly improving, and its long-distance transportation technology is in urgent need of vigorous development. As a type of natural gas ancillary product with a lighter molar mass, ethane products have a higher saturated vapor pressure, a critical temperature of about 32°C, and a critical pressure of about 4.5MPa. Therefore, it is possible to transport them in a single phase in gas or liquid state. Compared with the gaseous ethane pipeline transportation method, liquid transportation has the significant characteristics of small pipe diameter and high transportation efficiency, which is suitable for large-scale and networked transportation of ethane products.

[0003] During the operation of long-distance pipelines, it is a common working condition to empty a section of the pipeline for maintenance. After maintenance, the problem of safe filling needs to be considered to ensure the safety of pipeline restart. For conventional oil and natural gas pipelines, after the pipeline is overhauled and put into operation again, it is considered to import oil or natural gas from the upstream of the maintenance section, or fill it with a safe isolation medium, and fill the isolated pipeline under maintenance, and then it can be put into use again. In contrast, if the filling method of directly introducing ethane from the upstream is adopted, the liquid ethane will inevitably vaporize violently in the initial stage of filling during the empty pipe filling process, and the temperature of the vaporized medium can be as low as -90℃, which will cause safety hazards to the pipeline performance; if the external nitrogen stamping method is adopted, there will be problems with the operation of the intermediate pump station, and high-pressure nitrogen will appear at the terminal outlet, affecting the operation of the liquid phase equipment, and the operation will be unstable due to the lack of physical isolation between liquid ethane and nitrogen during the pipeline transportation process; if the external purified water stamping method is adopted, it is difficult for the system to further perform drying operations, which will cause hidden dangers to corrosion in the pipeline.

[0004] At present, there are few reports on the safe filling system of liquid ethane pipeline after maintenance. In view of the above-mentioned potential problems, it is necessary to carry out in-depth research on the safe filling system and method of liquid ethane pipeline after maintenance, take reasonable measures to ensure the safety of liquid ethane pipeline filling, and thereby ensure the restart effect of the system, and promote the development of liquid ethane pipeline transportation technology. Summary of the invention

[0005] The purpose of the present invention is to provide a liquid ethane pipeline safe filling system and filling method after maintenance in order to further promote the development of liquid ethane pipeline transportation technology and ensure operation safety in view of the above-mentioned problems.

[0006] The main technical idea of ​​the present invention is based on the operation and maintenance characteristics of long-distance liquid ethane pipelines, combined with the phase, pressure and temperature change characteristics of the medium in the isolated empty pipe section during the filling process of liquid ethane, and adopts measures such as using the valve chamber bypass in the upstream pipe section to provide a filling medium channel, vaporizing and heating the initial filling medium with external equipment, and pressurizing and liquefying in the middle and late filling, so as to effectively control the low temperature problem of the medium in the filling process of the isolated and maintenance section of the liquid ethane pipeline and ensure the safe operation of the liquid ethane pipeline.

[0007] The technical solution adopted by the present invention is: a liquid ethane pipeline safe filling system after maintenance, characterized by: comprising a trunk system, a trunk valve chamber system, an ethane filling system and a pipeline temperature and pressure detection system;

[0008] The trunk system includes an upstream trunk, a trunk shutoff valve and a downstream trunk connected in sequence, the trunk system is used to connect the upstream and downstream pipelines to form a liquid ethane delivery channel, and the trunk shutoff valve is used to connect or shut off the upstream trunk and the downstream trunk;

[0009] The trunk valve chamber system includes a valve chamber bypass and a bypass cut-off valve group, a bypass reserved pipeline cut-off valve group and a bypass replacement cut-off valve group arranged on the valve chamber bypass. The valve chamber bypass is connected to the upstream trunk line of the trunk system and connected to the downstream trunk line of the trunk system to form a bypass of the trunk system.

[0010] The ethane filling system is connected to the valve chamber bypass through a bypass reserved pipeline shut-off valve group. The ethane filling system is used to introduce ethane from the upstream trunk line and heat and adjust the temperature before the downstream trunk line is restarted, and then send it to the downstream trunk line to be restarted.

[0011] The liquid ethane pipeline safe filling system after maintenance of the present invention comprises a bypass cut-off valve group arranged on the bypass of the valve chamber, which comprises a bypass front section cut-off valve, a bypass middle section cut-off valve and a bypass rear section cut-off valve;

[0012] The bypass reserved pipeline shut-off valve group is composed of a bypass reserved outlet pipeline shut-off valve and a bypass reserved inlet pipeline shut-off valve, which are used for downstream trunk replacement and restart. The bypass reserved outlet pipeline shut-off valve is arranged between the bypass front section shut-off valve and the bypass middle section shut-off valve, and the bypass reserved inlet pipeline shut-off valve is arranged between the bypass middle section shut-off valve and the bypass rear section shut-off valve;

[0013] The bypass replacement shut-off valve group consists of a bypass replacement injection shut-off valve and a bypass replacement discharge shut-off valve. The bypass replacement injection shut-off valve is arranged between the bypass front section shut-off valve and the bypass middle section shut-off valve, and the bypass replacement discharge shut-off valve is arranged between the bypass middle section shut-off valve and the bypass rear section shut-off valve.

[0014] The liquid ethane pipeline safe filling system after maintenance described in the present invention comprises the bypass pipeline between the upstream trunk line and the bypass front section shut-off valve being the valve chamber bypass front section, the bypass pipeline between the bypass front section shut-off valve and the bypass rear section shut-off valve being the valve chamber bypass middle section, and the bypass pipeline between the bypass rear section shut-off valve and the downstream trunk line being the valve chamber bypass rear section.

[0015] The liquid ethane pipeline safe filling system after maintenance described in the present invention, wherein the bypass middle section shut-off valve is arranged in the bypass middle section of the valve chamber, the bypass reserved outlet pipeline shut-off valve and the bypass replacement injection shut-off valve are respectively connected to the bypass middle section pipeline of the valve chamber corresponding to the bypass front section shut-off valve and the bypass middle section shut-off valve; the bypass reserved inlet pipeline shut-off valve and the bypass replacement discharge shut-off valve are respectively connected to the bypass middle section pipeline of the valve chamber corresponding to the bypass middle section shut-off valve and the bypass rear section shut-off valve.

[0016] The liquid ethane pipeline safe filling system after maintenance described in the present invention, wherein the pipeline temperature and pressure detection system includes a temperature transmitter and a pressure transmitter, and the temperature transmitter and the pressure transmitter are respectively arranged on the valve chamber bypass front section and the valve chamber bypass rear section, and the pipeline temperature and pressure detection system is used to detect the pipeline pressure and temperature during normal operation of the pipeline and to monitor the pressure and temperature of the filling pipeline during pipeline filling.

[0017] The liquid ethane pipeline safe filling system after maintenance described in the present invention has a venting system connected to the pipeline of the bypass middle section of the valve chamber corresponding to the bypass middle section shut-off valve and the bypass rear section shut-off valve, and the venting system is used for venting the upstream trunk line and the downstream trunk line after shut-off.

[0018] The liquid ethane pipeline safe filling system after maintenance of the present invention comprises an inlet pipeline, an outlet pipeline and a vaporizer unit, an inlet shut-off valve and a regulating valve are arranged on the inlet pipeline, and an outlet shut-off valve is arranged on the outlet pipeline. The inlet pipeline of the ethane filling system is connected with the bypass reserved outlet pipeline shut-off valve, and the outlet pipeline of the ethane filling system is connected with the bypass reserved inlet pipeline shut-off valve. The vaporizer unit is arranged between the regulating valve and the outlet shut-off valve, and the vaporizer unit is used for vaporizing and heating the liquid ethane initially entering the downstream trunk line.

[0019] The liquid ethane pipeline safe filling system after maintenance described in the present invention, wherein the vaporizer unit is a series combination of an air-temperature vaporizer and an electric heating water bath vaporizer, or is an air-temperature vaporizer or an electric heating water bath vaporizer used alone, and the air-temperature vaporizer and the electric heating water bath vaporizer are respectively skid-mounted to form a movable and splicable mobile ethane filling system.

[0020] The liquid ethane pipeline safe filling system after maintenance described in the present invention is provided with a temperature transmitter between the vaporizer unit and the outlet shut-off valve, and the temperature transmitter is used to detect the ethane temperature after vaporization heat exchange in real time, and is used to control the opening of the regulating valve after feedback.

[0021] A method for safely filling a liquid ethane pipeline after maintenance, characterized in that it comprises the following specific steps:

[0022] Step 1: Set up bypass systems in various trunk valve rooms and a movable ethane filling system in the pipeline center management area. When the trunk system is operating normally, keep all valves of the trunk valve room system closed and the movable ethane filling system in a maintenance standby state;

[0023] Step 2: After the downstream trunk line is shut down, emptied and overhauled, the movable ethane filling system is transported to the valve room. If the temperature of the operating environment is lower than -10°C, the movable ethane filling system is configured with a series combination of an air-temperature vaporizer and an electric-heating water bath vaporizer; if the ambient temperature is higher than -10°C, the movable ethane filling system is only configured with an air-temperature vaporizer or an electric-heating water bath vaporizer, and the switching of the combination is completed through the internal bypass of the movable ethane filling system;

[0024] Step 3: Connect the reserved pipeline of the trunk valve chamber system to the inlet pipeline and outlet pipeline of the movable ethane filling system, keep the trunk shut-off valve of the valve chamber closed, keep the bypass front-end shut-off valve closed, keep the venting valve of the venting system closed, open the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, the inlet shut-off valve, the regulating valve, the outlet shut-off valve and the bypass rear-end shut-off valve, keep the bypass middle-section shut-off valve closed, and inject nitrogen from the pipeline where the bypass replacement injection shut-off valve is located to realize the overall nitrogen filling and replacement of the movable ethane filling system and the downstream trunk line, and the duration is 5 to 10 minutes;

[0025] Close the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, open the bypass middle section shut-off valve, and continue to inject nitrogen from the pipeline where the bypass replacement injection shut-off valve is located to achieve overall nitrogen filling and replacement of the valve chamber bypass and the downstream trunk line, until the oxygen content of the gas at the downstream valve chamber nitrogen replacement outlet is less than 1%, completing the nitrogen replacement;

[0026] Step 4: Close the inlet shut-off valve and the bypass middle shut-off valve, and further inject nitrogen from the nitrogen filling port of the bypass displacement injection shut-off valve until the pressure is increased to 2MPa, so as to establish the back pressure of the pipeline from the bypass front shut-off valve to the inlet shut-off valve;

[0027] Step 5: Pre-start the movable ethane filling system, open the bypass front-end shut-off valve and the inlet shut-off valve, slowly open the regulating valve of the movable ethane filling system, detect the outlet medium temperature of the movable ethane filling system through the temperature transmitter in the ethane filling system, maintain the outlet medium temperature of the system above -15°C, and start to continuously discharge nitrogen from the downstream pipeline until the nitrogen content in the outlet gas of the downstream bypass replacement discharge shut-off valve is less than 1%;

[0028] Close the downstream bypass replacement discharge shut-off valve. The pressure in the downstream trunk line continues to rise due to the continuous filling of ethane. When the downstream trunk line pressure is higher than 2MPa, disconnect the movable ethane filling system, open the bypass middle section shut-off valve, and continue to pressurize the downstream trunk line from the valve chamber bypass until the downstream trunk line pressure rises to the original stop-transmission pressure. During this process, maintain continuous ethane injection into the ethane pipeline from the upstream starting station to maintain the phase stability of the ethane pipeline upstream of the filling pipeline.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] According to the functional requirement of restarting the liquid ethane pipeline after maintenance and discharge, based on the low-pressure vaporization and low-temperature characteristics of liquid ethane, the present invention adopts measures such as using a valve chamber bypass in the upstream pipe section to provide a filling medium channel, vaporizing and heating the initial filling medium with external equipment, and pressurizing and liquefying in the middle and late filling, so as to effectively control the low temperature problem of the medium in the filling process of the isolated maintenance section of the liquid ethane pipeline, ensure the safe operation of the liquid ethane pipeline, and provide effective guarantee for the safe operation of the liquid ethane pipeline throughout its life cycle.

[0031] The specific manifestations are:

[0032] (1) Scientific setting

[0033] Based on the characteristics of liquid ethane vaporizing under low pressure, this system comprehensively considers the maintenance and venting issues during its production operation, and further ensures the safety of pipeline restart and the purity of the medium. Scientific measures are taken to ensure restart safety: a movable ethane filling system is set up to make full use of external heat supply equipment to achieve safe introduction of ethane in the upstream pipeline to the pipeline section to be put into operation, avoiding low temperature problems caused by unheated introduction; a valve chamber bypass nitrogen filling pipeline is set up to effectively control the back pressure of the pipeline to be filled, avoiding low temperature caused by the initial low back pressure during the introduction process; in addition, the relocation feature is used to effectively achieve efficient use of equipment.

[0034] (2) Economical

[0035] This system includes a skid-mounted movable ethane filling system, which can directly use the ethane in the upstream pipeline to fill the downstream pipeline, avoiding the problem of using water injection to establish back pressure, and also avoiding the subsequent treatment problems at the downstream end caused by water injection, saving a lot of investment; secondly, the combination of ethane vaporization and heating can be selected according to the ambient temperature, further rationally utilizing natural energy; thirdly, the movable system can radiate multiple valve chambers, avoiding duplicate construction investment.

[0036] (3) Promoting technological development

[0037] In view of the fact that the development of liquid ethane pipelines in my country is still in its infancy, the present invention, based on a thorough study of the demand for restarting liquid ethane pipelines after maintenance, proposes relevant safeguard measures, which can provide support and reference for the technical development of liquid ethane pipelines in my country and help promote the further development of this technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be described by way of specific embodiments with reference to the accompanying drawings, in which

[0039] Figure 1 It is a system schematic diagram of the present invention.

[0040] Markings in the figure: 1 is the upstream trunk line, 2 is the trunk line shut-off valve, 3 is the downstream trunk line, 4 is the bypass front section shut-off valve, 5 is the bypass middle section shut-off valve, 6 is the bypass rear section shut-off valve, 7 is the bypass reserved outlet pipeline shut-off valve, 8 is the bypass reserved inlet pipeline shut-off valve, 9 is the bypass replacement injection shut-off valve, 10 is the bypass replacement discharge shut-off valve, 11 is the valve chamber bypass front section, 12 is the valve chamber bypass middle section, 13 is the valve chamber bypass rear section, 14 is the temperature transmitter, 15 is the pressure transmitter, 16 is the inlet pipeline, 17 is the outlet pipeline, 18 is the inlet shut-off valve, 19 is the regulating valve, 20 is the outlet shut-off valve, 21 is the air-temperature vaporizer, 22 is the electric heating water bath vaporizer, and 23 is the vent valve. DETAILED DESCRIPTION

[0041] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0042] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0043] like Figure 1As shown, a liquid ethane pipeline safe filling system after maintenance includes a trunk system, a trunk valve chamber system, an ethane filling system and a pipeline temperature and pressure detection system.

[0044] The trunk system includes an upstream trunk line 1, a trunk line shutoff valve 2 and a downstream trunk line 3 connected in sequence. The trunk system is used to connect the upstream and downstream pipelines to form a liquid ethane delivery channel. The trunk line shutoff valve 2 is used to connect or shut off the upstream trunk line 1 and the downstream trunk line 3. The trunk system is responsible for providing a fluid delivery channel and maintenance during normal delivery, and implementing pipeline shutoff in the event of an accident.

[0045] Specifically, the upstream trunk line 1 and the downstream trunk line 3 are both made of ordinary carbon steel, and the trunk line shut-off valve 2 is an electrically controlled full-diameter ball valve, which is in a normally open state and is closed when the upstream trunk line 1 or the downstream trunk line 3 needs to be repaired.

[0046] The trunk valve chamber system includes a valve chamber bypass and a bypass cut-off valve group, a bypass reserved pipeline cut-off valve group and a bypass replacement cut-off valve group arranged on the valve chamber bypass. The valve chamber bypass is connected to the upstream trunk line 1 of the trunk system and connected to the downstream trunk line 3 of the trunk system to form a bypass of the trunk system. The trunk valve chamber system is responsible for the venting and restarting of the upstream and downstream pipeline systems of the valve chamber, and also provides a channel for trunk pipeline replacement.

[0047] In this embodiment, the bypass cut-off valve group arranged on the bypass of the valve chamber is composed of a bypass front-end cut-off valve 4 , a bypass middle-end cut-off valve 5 and a bypass rear-end cut-off valve 6 .

[0048] The bypass reserved pipeline shut-off valve group consists of a bypass reserved outlet pipeline shut-off valve 7 and a bypass reserved inlet pipeline shut-off valve 8, which are used for replacement and restarting of the downstream trunk line 3. The bypass reserved outlet pipeline shut-off valve 7 is arranged between the bypass front section shut-off valve 4 and the bypass middle section shut-off valve 5, and the bypass reserved inlet pipeline shut-off valve 8 is arranged between the bypass middle section shut-off valve 5 and the bypass rear section shut-off valve 6.

[0049] The bypass replacement shut-off valve group consists of a bypass replacement injection shut-off valve 9 and a bypass replacement discharge shut-off valve 10. The bypass replacement injection shut-off valve 9 is arranged between the bypass front-section shut-off valve 4 and the bypass middle-section shut-off valve 5, and the bypass replacement discharge shut-off valve 10 is arranged between the bypass middle-section shut-off valve 5 and the bypass rear-section shut-off valve 6.

[0050] The bypass pipeline between the upstream trunk line 1 and the bypass front section shut-off valve 4 is the valve chamber bypass front section 11, the bypass pipeline between the bypass front section shut-off valve 4 and the bypass rear section shut-off valve 6 is the valve chamber bypass middle section 12, the bypass pipeline between the bypass rear section shut-off valve 6 and the downstream trunk line 3 is the valve chamber bypass rear section 13, the bypass middle section shut-off valve 5 is arranged in the valve chamber bypass middle section 12, the bypass reserved outlet pipeline shut-off valve 7 and the bypass replacement injection shut-off valve 9 are respectively connected to the bypass front section shut-off valve 4 and The valve chamber bypass middle section 12 pipeline corresponding to the bypass middle section shut-off valve 5 is connected with the pipeline; the bypass reserved inlet pipeline shut-off valve 8 and the bypass replacement discharge shut-off valve 10 are respectively connected with the valve chamber bypass middle section 12 pipeline corresponding to the bypass middle section shut-off valve 5 and the bypass rear section shut-off valve 6; the valve chamber bypass middle section 12 pipeline corresponding to the bypass middle section shut-off valve 5 and the bypass rear section shut-off valve 6 is connected with a venting system, and the venting system is used for venting after the upstream trunk line 1 and the downstream trunk line 3 are cut off.

[0051] Specifically, the valve chamber bypass front section 11, the valve chamber bypass middle section 12, and the valve chamber bypass rear section 13 are all made of ordinary carbon steel, and the pipe diameter is DN100; the bypass front section shut-off valve 4, the bypass middle section shut-off valve 5 and the bypass rear section shut-off valve 6 are all manually controlled ball valves, made of ordinary carbon steel, with a size of DN100, and are all in a normally closed state; the bypass replacement injection shut-off valve 9 is a carbon steel manual ball valve, which is in a normally closed state and is used for nitrogen replacement (injection) connection between the trunk valve chamber system and the downstream trunk pipeline, and is also used to pressurize the valve chamber pipeline before introducing ethane from the upstream pipeline to provide sufficient back pressure; the bypass replacement discharge shut-off valve 10 is a carbon steel manual ball valve, which is in a normally closed state , used for nitrogen replacement (discharge) connection between the trunk valve chamber system and the upstream trunk pipeline; the bypass reserved outlet pipeline shut-off valve 7 and the bypass reserved inlet pipeline shut-off valve 8 are manual ball valves, which are in the normally closed state, made of carbon steel, and are used to connect the movable ethane filling system before the downstream trunk is restarted; the bypass replacement injection shut-off valve 9, the bypass replacement discharge shut-off valve 10, the bypass reserved outlet pipeline shut-off valve 7 and the bypass reserved inlet pipeline shut-off valve 8 are all connected to the valve chamber bypass pipeline at one end and connected to the blind flange at the other end to establish an injection or discharge channel; the vent valve 23 is located on the vent pipeline, which is in the normally closed state, connected to the vent system, and is used for venting the valve chamber bypass and the trunk pipeline.

[0052] The ethane filling system is connected to the valve chamber bypass through a bypass reserved pipeline shut-off valve group. The ethane filling system is used to introduce ethane from the upstream trunk line 1 before the downstream trunk line 3 is restarted, and then heat and adjust the temperature to send it to the downstream trunk line 3 to be restarted.

[0053] The pipeline temperature and pressure detection system includes a temperature transmitter 14 and a pressure transmitter 15, which are respectively arranged on the valve chamber bypass front section 11 and the valve chamber bypass rear section 13. The pipeline temperature and pressure detection system is used to detect the pipeline pressure and temperature during normal operation of the pipeline and to monitor the pressure and temperature of the filling pipeline during filling.

[0054] Among them, the ethane filling system includes an inlet pipe 16, an outlet pipe 17 and a vaporizer unit. An inlet shut-off valve 18 and a regulating valve 19 are arranged on the inlet pipe 16, and an outlet shut-off valve 20 is arranged on the outlet pipe 17. The head end of the inlet pipe 16 of the ethane filling system is provided with an interface for connecting with the bypass reserved outlet pipeline shut-off valve 7 of the trunk valve chamber system, and the end of the outlet pipe 17 of the ethane filling system is provided with an interface for connecting with the bypass reserved inlet pipeline shut-off valve 8 of the trunk valve chamber system. The vaporizer unit is arranged between the regulating valve 19 and the outlet shut-off valve 20, and the vaporizer unit is used to vaporize and heat the liquid ethane initially entering the downstream trunk line 3.

[0055] In this embodiment, the vaporizer unit can adopt a series combination of an air-temperature vaporizer 21 and an electric heating water bath vaporizer 22, or use the air-temperature vaporizer 21 or the electric heating water bath vaporizer 22 separately, depending on the ambient temperature. The air-temperature vaporizer 21 and the electric heating water bath vaporizer 22 are separately pried to form a movable and splicable mobile ethane filling system. At the same time, the movable ethane filling system also includes a matching power supply system.

[0056] A temperature transmitter 14 is provided between the vaporizer unit and the outlet shut-off valve 20 , and the temperature transmitter 14 is used to detect the temperature of ethane after vaporization heat exchange in real time, and to control the opening of the regulating valve 19 after feedback.

[0057] Specifically, the inlet shut-off valve 18 is a stainless steel ball valve, which is in a normally closed state and is opened after nitrogen with sufficient pressure is filled upstream of the valve; the regulating valve 19 is a logic control regulating valve, made of stainless steel, used to introduce ethane into the air-temperature vaporizer 21 and the electrically heated water bath vaporizer 22, and adjust the opening according to the temperature feedback of the ethane after temperature adjustment obtained by the temperature transmitter 14; the air-temperature vaporizer 21 is a small air-heating vaporizer, made of stainless steel, and is also equipped with an induced draft fan; the air-temperature vaporizer 21 is also provided with a stainless steel bypass, which is enabled when the ethane temperature entering the air-temperature vaporizer is higher than -20°C; the electrically heated water bath vaporizer 2 2 is a small water bath vaporizer, which adopts a power supply to provide energy and is made of stainless steel. The electrically heated water bath vaporizer 22 is also provided with a stainless steel bypass, which is enabled when the temperature of ethane entering the electrically heated water bath vaporizer is higher than -20°C; the outlet shut-off valve 20 is a stainless steel ball valve, which is in a normally closed state; further, since a separate regulating valve 19 is used to control the flow, the air temperature vaporizer 21 and the electrically heated water bath vaporizer 22 normally only provide a medium heating function. After the regulating valve 19 fails or fails, the flow regulation function of the air temperature vaporizer 21 and the electrically heated water bath vaporizer 22 is enabled to achieve multiple flow control protections.

[0058] At the same time, the system also includes a logic control system that realizes transmitter signal transmission, processing and valve control.

[0059] The working principle of the filling system of the present invention is:

[0060] (1) Liquid ethane pipelines are inevitably subject to maintenance. When the downstream trunk pipeline is emptied and the maintenance is completed, it is necessary to fill it with a medium to increase the back pressure of the pipeline section to prevent the ethane in the upstream trunk pipeline from being strongly vaporized and causing low temperatures that can damage the downstream trunk pipeline due to the low back pressure after being filled into the downstream trunk pipeline. Therefore, this system is set up.

[0061] (2) When preparing to restart the downstream trunk pipeline, first keep all valves in the valve chamber bypass closed and consider the configuration of the movable ethane filling system according to the ambient temperature. If the ambient temperature is higher than -10°C, only select an air-temperature vaporizer; if the ambient temperature is lower than -10°C, select a series combination of an air-temperature vaporizer and an electric heating water bath vaporizer. The reason for selecting a vaporizer is to utilize the heat exchange principle of the vaporizer to vaporize the ethane introduced into the upstream trunk pipeline and then exchange heat, so as to avoid the medium temperature entering the downstream trunk pipeline being lower than -20°C (-20°C is the minimum design temperature of carbon steel).

[0062] (3) After the trunk valve chamber system is connected to the movable ethane filling system, nitrogen is first filled into the valve chamber through the nitrogen injection port to achieve nitrogen replacement of the valve chamber bypass and the downstream trunk pipeline, and the replaced air is discharged from the downstream adjacent valve chamber; further, the valve chamber bypass, the movable ethane filling system, and the downstream trunk pipeline are replaced by closing the bypass middle section cut-off valve and opening the bypass reserved outlet pipeline cut-off valve 7, the bypass reserved inlet pipeline cut-off valve 8, the inlet cut-off valve 18, and the outlet cut-off valve 20; finally, the valve chamber bypass system, the movable ethane filling system, and the downstream trunk pipeline are replaced with nitrogen. At this time, the pressure in the downstream trunk pipeline is close to normal pressure.

[0063] (4) Since the valve chamber bypass pipeline is made of carbon steel, the pipeline between the bypass front section block valve and the inlet block valve needs to be injected with nitrogen at about 2MPa to increase the pressure of this section of the pipeline and avoid a sudden drop in temperature of this section of the pipeline after the bypass front section block valve is opened.

[0064] (5) By opening the regulating valve, the liquid ethane in the upstream trunk pipeline is introduced into the air-temperature vaporizer and the electrically heated water bath vaporizer of the movable ethane filling system. The medium temperature is heat exchanged or heated from -90°C at the vaporizer inlet to above -20°C, and then introduced into the downstream trunk pipeline after detection by the temperature transmitter; the ethane in the upstream trunk pipeline is continuously supplemented in small quantities through the pipeline starting point pump station, and the pressure of the downstream trunk pipeline continues to increase to about 2MPa.

[0065] (6) When the pressure of the downstream trunk pipeline is higher than 2MPa, even if the liquid ethane is depressurized to this pressure, the medium temperature is higher than -10℃, so the heat exchange or heating function of the vaporizer can be cut off. Further, ethane is normally continuously introduced into the downstream trunk pipeline through the valve chamber bypass until the medium pressure in the downstream trunk pipeline reaches the original stop pressure and the medium is all liquid. At this time, the pipeline is pressurized and can be safely restarted.

[0066] like Figure 1 As shown, a method for safely filling a liquid ethane pipeline after maintenance includes the following specific steps:

[0067] Step 1: Set up a bypass system in each trunk valve room and a movable ethane filling system in the pipeline center management area. When the trunk system is operating normally, keep all valves in the trunk valve room system closed and the movable ethane filling system in a maintenance standby state.

[0068] Step 2: After the downstream trunk line is shut down, emptied and overhauled, the movable ethane filling system is transported to the valve room. If the operating environment temperature is lower than -10°C, the movable ethane filling system is configured with a series combination of an air-temperature vaporizer and an electric-heated water bath vaporizer; if the ambient temperature is higher than -10°C, the movable ethane filling system is only configured with an air-temperature vaporizer or an electric-heated water bath vaporizer, and the switching of the combination is completed through the internal bypass of the movable ethane filling system.

[0069] Step three: connect the reserved pipeline of the trunk valve chamber system to the inlet pipeline and outlet pipeline of the movable ethane filling system, keep the trunk shut-off valve of the valve chamber closed, keep the bypass front-end shut-off valve closed, keep the vent valve 23 of the venting system closed, open the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, the inlet shut-off valve, the regulating valve, the outlet shut-off valve and the bypass rear-end shut-off valve, keep the bypass middle-section shut-off valve closed, and inject nitrogen from the pipeline where the bypass displacement injection shut-off valve is located to realize the overall nitrogen filling and replacement of the movable ethane filling system and the downstream trunk line, and the duration is 5 to 10 minutes.

[0070] Close the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, open the bypass middle section shut-off valve, and continue to inject nitrogen from the pipeline where the bypass replacement injection shut-off valve is located to achieve overall nitrogen filling and replacement of the valve chamber bypass and downstream trunk line, until the oxygen content of the gas at the nitrogen replacement outlet of the downstream valve chamber is less than 1%, completing the nitrogen replacement.

[0071] Step 4: Close the inlet shut-off valve and the middle shut-off valve of the bypass, and further inject nitrogen from the nitrogen filling port of the bypass displacement injection shut-off valve until the pressure is increased to 2MPa. Establish the back pressure of the pipeline from the bypass front shut-off valve to the inlet shut-off valve to avoid excessive pressure drop after the introduction of upstream ethane, which may cause the downstream pipeline to produce a low temperature lower than the material tolerance temperature, thereby affecting the performance of the valve room bypass pipe.

[0072] Step 5: Pre-start the movable ethane filling system, open the bypass front-end shut-off valve and the inlet shut-off valve, slowly open the regulating valve of the movable ethane filling system, detect the outlet medium temperature of the movable ethane filling system through the temperature transmitter in the ethane filling system, maintain the system outlet medium temperature above -15°C, and start to continuously discharge nitrogen from the downstream pipeline until the nitrogen content in the outlet gas of the downstream bypass replacement discharge shut-off valve is less than 1%.

[0073] Close the downstream bypass replacement discharge shut-off valve. The pressure in the downstream trunk line continues to rise due to the continuous filling of ethane. When the downstream trunk line pressure is higher than 2MPa, disconnect the movable ethane filling system, open the bypass middle section shut-off valve, and continue to pressurize the downstream trunk line from the valve chamber bypass until the downstream trunk line pressure rises to the original stop-transmission pressure. During this process, maintain continuous ethane injection into the ethane pipeline from the upstream starting station to maintain the phase stability of the ethane pipeline upstream of the filling pipeline.

[0074] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A liquid ethane pipeline safe filling system after maintenance, characterized by: Including trunk system, trunk valve room system, ethane filling system and pipeline temperature and pressure detection system; The trunk system comprises an upstream trunk (1), a trunk shutoff valve (2) and a downstream trunk (3) which are connected in sequence, the trunk system is used to connect upstream and downstream pipelines to form a liquid ethane delivery channel, and the trunk shutoff valve (2) is used to connect or shut off the upstream trunk (1) and the downstream trunk (3); The trunk valve chamber system comprises a valve chamber bypass and a bypass shutoff valve group, a bypass reserved pipeline shutoff valve group and a bypass replacement shutoff valve group arranged on the valve chamber bypass. The valve chamber bypass is connected to an upstream trunk line (1) of the trunk system and is connected to a downstream trunk line (3) of the trunk system to form a bypass of the trunk system. The ethane filling system is connected to the valve chamber bypass through a bypass reserved pipeline shutoff valve group. The ethane filling system is used to introduce ethane from the upstream trunk line (1) before the downstream trunk line (3) is restarted, and then heat and adjust the temperature before sending it to the downstream trunk line (3) to be restarted; the bypass shutoff valve group arranged on the valve chamber bypass is composed of a bypass front section shutoff valve (4), a bypass middle section shutoff valve (5) and a bypass rear section shutoff valve (6); The bypass reserved pipeline shutoff valve group is composed of a bypass reserved outlet pipeline shutoff valve (7) and a bypass reserved inlet pipeline shutoff valve (8), and is used for replacement and restarting of the downstream trunk line (3). The bypass reserved outlet pipeline shutoff valve (7) is arranged between the bypass front section shutoff valve (4) and the bypass middle section shutoff valve (5), and the bypass reserved inlet pipeline shutoff valve (8) is arranged between the bypass middle section shutoff valve (5) and the bypass rear section shutoff valve (6); The bypass replacement shut-off valve group is composed of a bypass replacement injection shut-off valve (9) and a bypass replacement discharge shut-off valve (10), wherein the bypass replacement injection shut-off valve (9) is arranged between the bypass front section shut-off valve (4) and the bypass middle section shut-off valve (5), and the bypass replacement discharge shut-off valve (10) is arranged between the bypass middle section shut-off valve (5) and the bypass rear section shut-off valve (6); the ethane filling system comprises an inlet pipe (16), an outlet pipe (17) and a vaporizer unit, wherein an inlet shut-off valve (18) and a regulating valve (19) are arranged on the inlet pipe (16), and an outlet shut-off valve (20) is arranged on the outlet pipe (17); the inlet pipe (16) of the ethane filling system is connected to the bypass reserved outlet pipe shut-off valve (7), and the outlet pipe (17) of the ethane filling system is connected to the bypass reserved outlet pipe shut-off valve (20). The inlet pipeline shut-off valve (8) is connected, the vaporizer unit is arranged between the regulating valve (19) and the outlet shut-off valve (20), and the vaporizer unit is used to vaporize and heat the liquid ethane that initially enters the downstream trunk line (3); the vaporizer unit is a series combination of an air-temperature vaporizer (21) and an electric heating water bath vaporizer (22), or is an air-temperature vaporizer (21) or an electric heating water bath vaporizer (22) used alone, the air-temperature vaporizer (21) and the electric heating water bath vaporizer (22) are respectively skid-type to form a movable and splicable mobile ethane filling system; a temperature transmitter (14) is arranged between the vaporizer unit and the outlet shut-off valve (20), and the temperature transmitter (14) is used to detect the ethane temperature after vaporization heat exchange in real time, and to control the opening of the regulating valve (19) after feedback.

2. The liquid ethane pipeline post-maintenance safe filling system according to claim 1 is characterized by: The bypass pipeline between the upstream trunk line (1) and the bypass front section shutoff valve (4) is the valve chamber bypass front section (11), the bypass pipeline between the bypass front section shutoff valve (4) and the bypass rear section shutoff valve (6) is the valve chamber bypass middle section (12), and the bypass pipeline between the bypass rear section shutoff valve (6) and the downstream trunk line (3) is the valve chamber bypass rear section (13).

3. The liquid ethane pipeline post-maintenance safe filling system according to claim 2 is characterized by: The bypass middle section shutoff valve (5) is arranged in the bypass middle section (12) of the valve chamber, and the bypass reserved outlet pipeline shutoff valve (7) and the bypass replacement injection shutoff valve (9) are respectively connected to the valve chamber bypass middle section (12) pipeline corresponding to between the bypass front section shutoff valve (4) and the bypass middle section shutoff valve (5); the bypass reserved inlet pipeline shutoff valve (8) and the bypass replacement discharge shutoff valve (10) are respectively connected to the valve chamber bypass middle section (12) pipeline corresponding to between the bypass middle section shutoff valve (5) and the bypass rear section shutoff valve (6).

4. The liquid ethane pipeline post-maintenance safe filling system according to claim 2 is characterized by: The pipeline temperature and pressure detection system comprises a temperature transmitter (14) and a pressure transmitter (15), and the temperature transmitter (14) and the pressure transmitter (15) are respectively arranged on the valve chamber bypass front section (11) and the valve chamber bypass rear section (13). The pipeline temperature and pressure detection system is used to detect the pipeline pressure and temperature during normal operation of the pipeline and to monitor the pressure and temperature of the filling pipeline during filling of the pipeline.

5. The liquid ethane pipeline post-maintenance safe filling system according to claim 2 is characterized by: A venting system is connected to the pipeline of the bypass middle section (12) of the valve chamber corresponding to the bypass middle section shutoff valve (5) and the bypass rear section shutoff valve (6), and the venting system is used for venting the upstream trunk line (1) and the downstream trunk line (3) after shutoff.

6. A method for safe filling of liquid ethane pipeline after maintenance, using the safe filling system as claimed in claim 1, characterized in that: The specific steps include: Step 1: Set up bypass systems in various trunk valve rooms and a movable ethane filling system in the pipeline center management area. When the trunk system is operating normally, keep all valves of the trunk valve room system closed and the movable ethane filling system in a maintenance standby state; Step 2: After the downstream trunk line is shut down, emptied and overhauled, the movable ethane filling system is transported to the valve room. If the temperature of the operating environment is lower than -10°C, the movable ethane filling system is configured with a series combination of an air-temperature vaporizer and an electric-heating water bath vaporizer; if the ambient temperature is higher than -10°C, the movable ethane filling system is only configured with an air-temperature vaporizer or an electric-heating water bath vaporizer, and the switching of the combination is completed through the internal bypass of the movable ethane filling system; Step 3: Connect the reserved pipeline of the trunk valve chamber system to the inlet pipeline and outlet pipeline of the movable ethane filling system, keep the trunk shut-off valve of the valve chamber closed, keep the bypass front-end shut-off valve closed, keep the venting valve of the venting system closed, open the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, the inlet shut-off valve, the regulating valve, the outlet shut-off valve and the bypass rear-end shut-off valve, keep the bypass middle-section shut-off valve closed, and inject nitrogen from the pipeline where the bypass replacement injection shut-off valve is located to realize the overall nitrogen filling and replacement of the movable ethane filling system and the downstream trunk line, and the duration is 5 to 10 minutes; Close the bypass reserved outlet pipeline shut-off valve and the bypass reserved inlet pipeline shut-off valve, open the bypass middle section shut-off valve, and continue to inject nitrogen from the pipeline where the bypass replacement injection shut-off valve is located to achieve overall nitrogen filling and replacement of the valve chamber bypass and the downstream trunk line, until the oxygen content of the gas at the downstream valve chamber nitrogen replacement outlet is less than 1%, completing the nitrogen replacement; Step 4: Close the inlet shut-off valve and the bypass middle shut-off valve, and further inject nitrogen from the nitrogen filling port of the bypass displacement injection shut-off valve until the pressure is increased to 2MPa, so as to establish the back pressure of the pipeline from the bypass front shut-off valve to the inlet shut-off valve; Step 5: Pre-start the movable ethane filling system, open the bypass front-end shut-off valve and the inlet shut-off valve, slowly open the regulating valve of the movable ethane filling system, detect the outlet medium temperature of the movable ethane filling system through the temperature transmitter in the ethane filling system, maintain the outlet medium temperature of the system above -15°C, and start to continuously discharge nitrogen from the downstream pipeline until the nitrogen content in the outlet gas of the downstream bypass replacement discharge shut-off valve is less than 1%; Close the downstream bypass replacement discharge shut-off valve. The pressure in the downstream trunk line continues to rise due to the continuous filling of ethane. When the downstream trunk line pressure is higher than 2MPa, disconnect the movable ethane filling system, open the bypass middle section shut-off valve, and continue to pressurize the downstream trunk line from the valve chamber bypass until the downstream trunk line pressure rises to the original stop-transmission pressure. During this process, maintain continuous ethane injection into the ethane pipeline from the upstream starting station to maintain the phase stability of the ethane pipeline upstream of the filling pipeline.

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