CN112362391B - Liquid asphalt sampling system and method - Google Patents

Abstract

The present invention relates to a liquid asphalt sampling system and method, wherein the liquid asphalt sampling system comprises a sampling pipeline, a cooling unit, a sampling unit and a cleaning unit; one end of the sampling pipeline is connected to the liquid asphalt pipeline upstream of a ΔP device, and the other end is connected to the liquid asphalt pipeline downstream of the ΔP device; the cooling unit comprises a cooler; the sampling unit comprises a sampler; the cleaning unit comprises a high-level tank and a low-level tank; the present invention thoroughly solves the problem of asphalt blocking pipelines and valves during online sampling of liquid asphalt, and simultaneously solves the problem of asphalt fume emissions polluting the environment during the sampling process and the cleaning process.

Description

Liquid asphalt sampling system and method

Technical Field

The invention relates to the field of coking technology, and in particular to a coal tar liquid asphalt sampling system and method in asphalt production and deep processing.

Background Art

During the processing of coal tar, about 50% to 60% of medium-temperature asphalt is produced, which is a major product of tar processing. The larger the processing scale, the more asphalt is produced. Modified asphalt is currently the main downstream product of asphalt, mainly used in the production of pre-baked anodes, preparation of battery rods or electrode binders in the electrolytic aluminum industry. In addition, asphalt coke, needle coke, etc. are also downstream products of medium-temperature asphalt. Regardless of the production process used, it is necessary to sample and test the liquid asphalt in the production process to ensure the quality of the final product.

The conventional online sampling method for liquid asphalt pipelines usually adds a sampler consisting of a branch short pipe and an insulated cock to the pipeline where sampling is required. Asphalt is a slightly smelly black solid at room temperature and has no fixed melting point. The production process of asphalt is mostly in a high temperature environment of 130 to 400°C. At this time, asphalt is in a black fluid state. If sampling is carried out in an open atmospheric environment, not only is the high-temperature asphalt itself very dangerous, but it will also emit a large amount of asphalt fumes with a strong pungent odor and high toxicity. Operators exposed to such an environment will cause harm to their bodies and pollute the environment. At the same time, after the asphalt is sampled, the remaining asphalt will condense in the sampling pipeline, blocking the sampling pipeline and valve.

The Chinese patent application with application number CN 202010119181.5 discloses "a coal tar asphalt sampling valve and an online sampling system". The coal tar asphalt online sampling system includes a coal tar asphalt sampling valve, an asphalt cooler, an asphalt sampling cylinder, an electronic weighing scale, a purge unit and an exhaust unit; the coal tar asphalt sampling valve is directly arranged on the main pipeline of the coal tar asphalt, which can not only completely solve the blockage problem of the branch pipeline and the sampling valve when sampling with the branch pipeline, but also the asphalt samples obtained are all live flow samples, and there is no residual asphalt component in the pipeline. The above technical scheme only takes preventive measures for pipeline blockage and asphalt fume during the sampling process, and the residual asphalt after sampling has a large viscosity, and it is difficult to purge it clean with nitrogen, and the purged asphalt fume is directly discharged into the atmosphere, which will also cause environmental pollution. Therefore, it does not fundamentally solve the problem.

At present, there is no sampling system that can completely solve the problem of residual asphalt clogging the pipeline during online asphalt sampling and the emission of asphalt fume generated by online sampling.

Summary of the invention

The present invention provides a liquid asphalt sampling system and method, which completely solves the problem of asphalt blocking pipelines and valves during online sampling of liquid asphalt, and also solves the problem of asphalt fume emission polluting the environment during the sampling and cleaning processes.

In order to achieve the above object, the present invention adopts the following technical solutions:

A liquid asphalt sampling system comprises a sampling pipeline, a cooling unit, a sampling unit and a cleaning unit; one end of the sampling pipeline is connected to the liquid asphalt pipeline upstream of a △P device, and the other end is connected to the liquid asphalt pipeline downstream of the △P device; the cooling unit comprises a cooler; the sampling unit comprises a sampler; the cleaning unit comprises a high-level tank and a low-level tank; the sampling pipeline is provided with a cleaning medium inlet, a cooler, a sampler, an exhaust port, and a cleaning medium outlet in sequence along the asphalt flow direction; the exhaust port is connected to the high-level tank through an exhaust pipe, and the cleaning medium outlet is connected to the high-level tank through a cleaning medium outlet pipe; a bottom outlet is provided at the bottom of the high-level tank, which is connected to an upper inlet of a low-level tank through a bottom pipe, and a top outlet is provided at the top of the low-level tank, which is connected to an upper inlet of the upper part of the high-level tank through a top pipe; a heater is provided in the low-level tank, and a cleaning medium outlet is provided at the bottom of the low-level tank, which is connected to the sampling pipeline upstream of the cooler through a cleaning medium pipe.

The ΔP device is a valve or a pressure reducing device.

The cooling unit also includes a pressure gauge and a temperature gauge; the pressure gauge is arranged on the sampling pipeline upstream of the cooler, and the temperature gauge is arranged on the sampling pipeline downstream of the cooler; a valve is arranged on the sampling pipeline upstream of the cooling unit.

The sampling unit also includes a hose 1 and a hose 2; the sampler is an integrated sampling device composed of a quick connector 1, a needle valve 1, a sampling bottle, a needle valve 2, and a quick connector 2 connected in sequence, and the quick connector 1 and the quick connector 2 are respectively connected to the sampling pipeline through the hose 1 and the hose 2 at the corresponding ends.

The sampling pipelines at both ends of the sampling unit are respectively provided with valve three and valve four; the sampling pipeline upstream of valve three is connected with the sampling pipeline downstream of valve four through a traffic pipe, and valve two is provided on the traffic pipe.

The exhaust pipe is provided with valve five, the cleaning medium outlet pipe is provided with valve six, the bottom pipe is provided with valve seven, the top pipe is provided with valve eight; the sampling pipe downstream of the cleaning medium inlet is provided with valve nine; the cleaning medium pipe is provided with valve ten.

The top of the high-position tank is provided with a venting air pipe and an anthracene oil inlet pipe.

A safety valve is arranged on the top of the low-level tank, and a pressurized nitrogen inlet pipe is arranged on the upper part; a liquid level gauge and a thermometer are also arranged in the low-level tank.

A liquid asphalt sampling method, comprising:

1) The temperature of the incoming asphalt in the liquid asphalt pipeline is 130-400℃. When sampling begins, the asphalt upstream of the △P device passes through valve 1, cooling unit, traffic pipe and valve 9 in sequence, and then returns to the liquid asphalt pipeline downstream of the △P device;

2) If the asphalt temperature is between 130 and 150°C, the cooler is not turned on; if the asphalt temperature is above 150°C, the cooler is turned on, and when the asphalt temperature measured by the thermometer is between 130 and 150°C, valve 2 is closed to allow the asphalt to enter the sampling unit;

3) The sampling unit receives the asphalt from the cooling unit, and while gradually closing valve 2, opens valve 3, needle valve 1, needle valve 2 and valve 5 on the sampling pipeline in sequence. Valve 4 is opened after the gas in the upstream sampling pipeline is emptied, and valve 5 on the exhaust pipeline is closed while valve 4 is opened; the liquid asphalt returns to the liquid asphalt pipeline after a closed-loop circulation through the sampling pipeline;

4) Take the current sample, open valve 2 after taking the sample, close valve 3, valve 4, needle valve 1, needle valve 2, remove the sampler containing the sample, and replace it with a clean sampler;

5) Clean the sampling pipeline; the asphalt fume and air in the cleaning process are discharged into the high-level tank through the exhaust pipe, and finally connected to the original asphalt venting system through the venting pipe. No asphalt fume and air are discharged during the sampling and cleaning processes.

The cleaning unit uses anthracene oil, a component of asphalt, as a flushing medium to clean the sampling pipeline; the specific process is as follows:

1) adding anthracene oil to the high-level tank, opening valve seven on the bottom pipeline and valve eight on the top pipeline, and allowing the anthracene oil to flow into the low-level tank by gravity; closing valve seven and valve eight, heating the anthracene oil in the low-level tank by a heater, monitoring the heating temperature with a thermometer, and starting cleaning after heating to a set temperature;

2) Confirm the valve switch before cleaning: valve 1 and valve 9 are always in the closed state during the cleaning process, the safety valve is in the working state, and the cooling water supply is not in the state of flowing into the cooler;

3) Clean the sampling pipeline; after the clean sampler is installed, valve seven, valve eight, valve two, valve four, and valve six are all in a closed state, and valve ten, valve three, needle valve one, needle valve two, and valve five are all in an open state; the heated anthracene oil enters the low-level tank through the pressurized nitrogen inlet pipe, and under the action of pressure, the anthracene oil returns to the high-level tank from the cleaning medium outlet at the bottom of the low-level tank through valve ten, cooler, valve three, hose one, quick connector one, needle valve one, sampling bottle, needle valve two, quick connector two, hose two, and valve five; then open valve seven on the bottom pipeline and valve eight on the top pipeline, and put the anthracene oil into the low-level tank again; repeat the above process to repeatedly rinse the sampling pipeline until it is clean;

4) Flush the traffic pipe; close valve three, valve four and valve five, open valve six and valve two, and the heated anthracene oil returns to the high-level tank from the cleaning medium outlet at the bottom of the low-level tank through valve ten, cooler, valve two, valve six in sequence, and then open valve seven on the bottom pipe and valve eight on the top pipe, and put the anthracene oil back into the low-level tank again, and repeat the above process to repeatedly flush the traffic pipe until it is clean.

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

1) The present invention can thoroughly clean the asphalt remaining in the sampling pipeline after sampling, and clean without dead angles, thereby keeping the sampling pipeline always in a clean state, and completely solving the problem of blockage of the sampling pipeline and the valve thereon; and the asphalt samples obtained at any time are live flow samples, and there is no residual asphalt component in the pipeline, thereby ensuring the accuracy of the asphalt sample.

2) It ensures that no asphalt smoke is discharged during the sampling process and before and after sampling, while also avoiding the danger of high-temperature asphalt itself, completely solving the impact of asphalt smoke with pungent odor on the surrounding environment, and playing a good role in improving the asphalt production working environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a liquid asphalt sampling system according to the present invention.

In the figure: 1. Valve 1 2. Cooler 3. Valve 2 4. Valve 9 5. Valve 3 6. Hose 1 7. Quick connector 1 8. Needle valve 1 9. Sampling bottle 10. Needle valve 2 11. Quick connector 2 12. Hose 2 13. Valve 4 14. Valve 5 15. High-level tank 16. Low-level tank 17. Valve 7 18. Valve 8 19. Safety valve 20. Valve 10 21. Valve 6 22. Pressure gauge 23. Thermometer 24. Liquid level gauge 25. Heater 26. Venting pipe 27. Anthracene oil inlet pipe 28. Pressurized nitrogen inlet pipe 29. Exhaust pipe 30. Thermometer 31. Liquid asphalt pipeline 32. △P device 33. Original asphalt venting system

DETAILED DESCRIPTION

The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

As shown in FIG1 , a liquid asphalt sampling system of the present invention comprises a sampling pipeline, a cooling unit, a sampling unit and a cleaning unit; one end of the sampling pipeline is connected to a liquid asphalt pipeline 31 upstream of a △P device 32, and the other end is connected to a liquid asphalt pipeline 31 downstream of the △P device 32; the cooling unit comprises a cooler 2; the sampling unit comprises a sampler; the cleaning unit comprises a high-level tank 15 and a low-level tank 16; a cleaning medium inlet, a cooler 2, a sampler, an exhaust port, and a cleaning medium outlet are sequentially arranged on the sampling pipeline along the asphalt flow direction; The exhaust port is connected to the high-level tank 15 through the exhaust pipe 29, and the cleaning medium outlet is connected to the high-level tank 15 through the cleaning medium outlet pipe; the bottom of the high-level tank 15 is provided with a bottom outlet (anthracene oil outlet) connected to the upper inlet (anthracene oil inlet) of the low-level tank 16 through the bottom pipe, and the top of the low-level tank 16 is provided with a top outlet (gas outlet) connected to the upper inlet (gas inlet) of the high-level tank 15 through the top pipe; the low-level tank 16 is provided with a heater 25, and the bottom of the low-level tank 16 is provided with a cleaning medium outlet connected to the sampling pipe upstream of the cooler 2 through the cleaning medium pipe.

The ΔP device 32 is a valve or a pressure reducing device.

The cooling unit also includes a pressure gauge 22 and a temperature gauge 23; the pressure gauge 22 is arranged on the sampling pipeline upstream of the cooler 2, and the temperature gauge 23 is arranged on the sampling pipeline downstream of the cooler 2; a valve 1 is arranged on the sampling pipeline upstream of the cooling unit.

The sampling unit also includes a hose 1 6 and a hose 2 12; the sampler is an integrated sampling device composed of a quick connector 1 7, a needle valve 1 8, a sampling bottle 9, a needle valve 2 10, and a quick connector 2 11 connected in sequence, and the quick connector 1 7 and the quick connector 2 11 are respectively connected to the sampling pipeline through the hose 1 6 and the hose 2 12 at the corresponding ends.

The sampling pipelines at both ends of the sampling unit are respectively provided with valve three 5 and valve four 13; the sampling pipeline upstream of valve three 5 is connected with the sampling pipeline downstream of valve four 13 through a traffic pipe, and valve two 3 is provided on the traffic pipe.

A valve five 14 is provided on the exhaust pipe 19, a valve six 21 is provided on the cleaning medium outlet pipe, a valve seven 17 is provided on the bottom pipe, and a valve eight 18 is provided on the top pipe; a valve nine 4 is provided on the sampling pipe downstream of the cleaning medium inlet; and a valve ten 20 is provided on the cleaning medium pipe.

The top of the high-position tank 15 is provided with a gas emission pipe 26 and an anthracene oil inlet pipe 27 .

A safety valve 19 is disposed at the top of the low-level tank 16 , and a pressurized nitrogen inlet pipe 28 is disposed at the upper portion; a liquid level gauge 24 and a thermometer 30 are also disposed in the low-level tank 16 .

A liquid asphalt sampling method, comprising:

1) The temperature of the incoming asphalt in the liquid asphalt pipeline 31 is 130-400°C. When sampling begins, the asphalt upstream of the ΔP device 32 passes through valve 1, cooling unit 2, traffic pipe and valve 9 4 in sequence, and then returns to the liquid asphalt pipeline 31 downstream of the ΔP device 32;

2) If the asphalt temperature is between 130 and 150°C, cooler 2 is not turned on; if the asphalt temperature is above 150°C, cooler 2 is turned on, and when the asphalt temperature measured by the thermometer 23 is between 130 and 150°C, valve 2 3 is closed to allow the asphalt to enter the sampling unit;

3) The sampling unit receives the asphalt from the cooling unit, and while gradually closing the valve 2 3, opens the valve 3 5, the needle valve 1 8, the needle valve 2 10 and the valve 5 14 on the exhaust pipe 29 in sequence on the sampling pipe. The valve 4 13 is opened after the gas in the upstream sampling pipe is emptied. The valve 5 14 on the exhaust pipe 29 is closed while the valve 4 13 is opened; the liquid asphalt returns to the liquid asphalt pipe 31 after a closed-loop circulation through the sampling pipe;

4) Take the current sample, open valve 2 3 after taking the sample, close valve 3 5, valve 4 13, needle valve 1 8, needle valve 2 10, remove the sampler containing the sample, and replace it with a clean sampler;

5) Clean the sampling pipeline; the asphalt fume and air during the cleaning process are discharged to the high-level tank 15 through the exhaust pipe 29, and finally connected to the original asphalt venting system 33 through the venting pipe 26. No asphalt fume and air are discharged during the sampling process and the cleaning process.

The cleaning unit uses anthracene oil, a component of asphalt, as a flushing medium to clean the sampling pipeline; the specific process is as follows:

1) Add anthracene oil to the high-level tank 15, open the valve 7 17 on the bottom pipeline and the valve 8 18 on the top pipeline, and the anthracene oil flows into the low-level tank 16 by gravity; close the valve 7 17 and the valve 8 18, heat the anthracene oil in the low-level tank 16 by the heater 25, monitor the heating temperature with a thermometer 30, and start cleaning after heating to the set temperature;

2) Confirm the valve switch before cleaning: valve 1 and valve 9 4 are always in the closed state during the cleaning process, the safety valve 19 is in the working state, and the cooling water supply is not in the state of being passed into the cooler 2;

3) Clean the sampling pipeline; after the clean sampler is installed, valve seven 17, valve eight 18, valve two 3, valve four 13, valve six 21 are all in a closed state, and valve ten 20, valve three 5, needle valve one 8, needle valve two 10, valve five 14 are all in an open state; the heated anthracene oil enters the low-level tank 16 through the pressurized nitrogen inlet pipe 28, and under the action of pressure, the anthracene oil returns to the high-level tank 15 from the cleaning medium outlet at the bottom of the low-level tank 16 through valve ten 20, cooler 2, valve three 5, hose one 6, quick connector one 7, needle valve one 8, sampling bottle 9, needle valve two 10, quick connector two 11, hose two 12, valve five 14; then open the valve seven 17 on the bottom pipeline and the valve eight 18 on the top pipeline, and put the anthracene oil into the low-level tank 16 again; repeat the above process to repeatedly rinse the sampling pipeline until it is rinsed clean;

4) Flush the traffic pipe; close valve three 5, valve four 13 and valve five 14, open valve six 21 and valve two 3, and the heated anthracene oil returns to the high-level tank 15 from the cleaning medium outlet at the bottom of the low-level tank 16 through valve ten 20, cooler 2, valve two 3, valve six 21, and then open valve seven 17 on the bottom pipeline and valve eight 18 on the top pipeline, and put the anthracene oil back into the low-level tank 16 again, and repeat the above process to repeatedly flush the traffic pipe until it is flushed clean.

In the liquid asphalt sampling system described in the present invention, a cooling unit is provided to solve the problem of cooling high-temperature asphalt above 150°C, and the asphalt temperature is reduced to 130-150°C, which is convenient for sampling and testing. The sampler in the sampling unit is easier to disassemble and replace, which is convenient for sampling operation. The cleaning unit mainly solves the problem of cleaning the sampling pipeline and valves and the emission of asphalt fume during the sampling process and before and after sampling, ensuring that the entire sampling system is always in a clean state without residual asphalt, and that the asphalt fume is not discharged externally and all enters the original asphalt emission system.

The working principle of the liquid asphalt sampling system described in the present invention is: the sampling unit receives asphalt from the cooling unit, opens the corresponding valve on the sampling pipeline and the valve on the exhaust pipeline, and after the gas in the sampling pipeline is emptied, closes the valve on the exhaust pipeline to intercept the current flow sample, opens the valve on the traffic pipe after intercepting the sample, closes the corresponding valve on the sampling pipeline and the needle valves before and after the sampling bottle, removes the sampler through the quick connector, and sends the asphalt to the laboratory for testing. There is residual asphalt left at the front and rear ends of the valve on the sampling pipeline. If it is not cleaned in time, it is easy to block the sampling pipeline and affect the collection of the next sample. After the sample is intercepted and the sampler is removed, the asphalt at the hose is exposed to the atmosphere, and the asphalt smoke will also affect the surrounding environment, so it is necessary to install a clean sampler in time to clean the sampling pipeline.

The cleaning unit uses anthracene oil, a component in asphalt, as a flushing medium to clean the sampling pipeline. The anthracene oil is added to the high-level tank and then flows to the low-level tank by gravity. The cleaning can begin after the anthracene oil is heated by the heater. First, close the valves at both ends of the sampling pipeline, and then introduce pressurized nitrogen into the low-level tank through the pressurized nitrogen inlet pipe, and inject the hot anthracene oil into the sampling pipeline to clean the residual asphalt. The cleaned anthracene oil is tested by the sampler to see if it can still be used to clean asphalt. If it can, the anthracene oil is injected back to the high-level tank. If not, the anthracene oil is injected into the liquid asphalt pipeline. Since the asphalt itself contains anthracene oil, and the amount of anthracene oil injected is very small relative to the amount of the entire asphalt and can be ignored, it will not affect the quality of the asphalt.

The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims (9)

1. A liquid asphalt sampling system, characterized in that it comprises a sampling pipeline, a cooling unit, a sampling unit and a cleaning unit; one end of the sampling pipeline is connected to the liquid asphalt pipeline upstream of the △P device, and the other end is connected to the liquid asphalt pipeline downstream of the △P device; the △P device is a valve or a pressure reducing device; the cooling unit comprises a cooler; the sampling unit comprises a sampler; the cleaning unit comprises a high-level tank and a low-level tank; a cleaning medium inlet, a cooler, a sampler, an exhaust port, and a cleaning medium outlet are sequentially arranged on the sampling pipeline along the asphalt flow direction; the exhaust port is connected to the high-level tank through an exhaust pipe, and the cleaning medium outlet is connected to the high-level tank through a cleaning medium outlet pipe; a bottom outlet is arranged at the bottom of the high-level tank, which is connected to the upper inlet of the low-level tank through a bottom pipe, and a top outlet is arranged at the top of the low-level tank, which is connected to the upper inlet of the upper part of the high-level tank through a top pipe; a heater is arranged in the low-level tank, and a cleaning medium outlet is arranged at the bottom of the low-level tank, which is connected to the sampling pipeline upstream of the cooler through a cleaning medium pipe. 2. A liquid asphalt sampling system according to claim 1, characterized in that the cooling unit also includes a pressure gauge and a temperature gauge; the pressure gauge is arranged on the sampling pipeline upstream of the cooler, and the temperature gauge is arranged on the sampling pipeline downstream of the cooler; a valve is arranged on the sampling pipeline upstream of the cooling unit. 3. A liquid asphalt sampling system according to claim 1, characterized in that the sampling unit also includes hose 1 and hose 2; the sampler is an integrated sampling device composed of quick connector 1, needle valve 1, sampling bottle, needle valve 2, and quick connector 2 connected in sequence, and quick connector 1 and quick connector 2 are respectively connected to the sampling pipeline through hose 1 and hose 2 at the corresponding ends. 4. A liquid asphalt sampling system according to claim 1, characterized in that valve three and valve four are respectively provided on the sampling pipes at both ends of the sampling unit; the sampling pipe upstream of valve three and the sampling pipe downstream of valve four are connected through a traffic pipe, and valve two is provided on the traffic pipe. 5. A liquid asphalt sampling system according to claim 1, characterized in that a valve five is provided on the exhaust pipe, a valve six is provided on the cleaning medium outlet pipe, a valve seven is provided on the bottom pipe, and a valve eight is provided on the top pipe; a valve nine is provided on the sampling pipe downstream of the cleaning medium inlet; and a valve ten is provided on the cleaning medium pipe. 6. A liquid asphalt sampling system according to claim 1, characterized in that a venting pipe and an anthracene oil inlet pipe are provided on the top of the high-level tank. 7. A liquid asphalt sampling system according to claim 1, characterized in that a safety valve is provided on the top of the low-level tank, and a pressurized nitrogen inlet pipe is provided on the upper part; a liquid level meter and a thermometer are also provided in the low-level tank. 8. A method for sampling liquid asphalt, characterized in that the system described in any one of claims 1 to 7 is used; specifically comprising: 1) The temperature of the incoming asphalt in the liquid asphalt pipeline is 130-400℃. When sampling begins, the asphalt upstream of the △P device passes through valve 1, cooling unit, traffic pipe and valve 9 in sequence, and then returns to the liquid asphalt pipeline downstream of the △P device; 2) If the asphalt temperature is between 130 and 150°C, the cooler is not turned on; if the asphalt temperature is above 150°C, the cooler is turned on, and when the asphalt temperature measured by the thermometer is between 130 and 150°C, valve 2 is closed to allow the asphalt to enter the sampling unit; 3) The sampling unit receives the asphalt from the cooling unit, and while gradually closing valve 2, opens valve 3, needle valve 1, needle valve 2 and valve 5 on the sampling pipeline in sequence. Valve 4 is opened after the gas in the upstream sampling pipeline is emptied, and valve 5 on the exhaust pipeline is closed while valve 4 is opened; the liquid asphalt returns to the liquid asphalt pipeline after a closed-loop circulation through the sampling pipeline; 4) Take the current sample, open valve 2 after taking the sample, close valve 3, valve 4, needle valve 1, needle valve 2, remove the sampler containing the sample, and replace it with a clean sampler; 5) Clean the sampling pipeline; the asphalt fume and air in the cleaning process are discharged into the high-level tank through the exhaust pipe, and finally connected to the original asphalt venting system through the venting pipe. No asphalt fume and air are discharged during the sampling and cleaning processes. 9. A liquid asphalt sampling method according to claim 8, characterized in that the cleaning unit uses anthracene oil, a component in asphalt, as a flushing medium to clean the sampling pipeline; the specific process is as follows: 1) Add anthracene oil to the high-level tank, open valve 7 on the bottom pipeline and valve 8 on the top pipeline, and the anthracene oil flows into the low-level tank by gravity; close valve 7 and valve 8, heat the anthracene oil in the low-level tank by the heater, monitor the heating temperature with a thermometer, and start cleaning after heating to the set temperature; 2) Confirm the valve switch before cleaning: valve 1 and valve 9 are always in the closed state during the cleaning process, the safety valve is in the working state, and the cooling water supply is not in the state of flowing into the cooler; 3) Clean the sampling pipeline; after the clean sampler is installed, valve seven, valve eight, valve two, valve four, and valve six are all in the closed state, and valve ten, valve three, needle valve one, needle valve two, and valve five are all in the open state; the heated anthracene oil enters the low-level tank through the pressurized nitrogen inlet pipe, and under the action of pressure, the anthracene oil returns to the high-level tank from the cleaning medium outlet at the bottom of the low-level tank through valve ten, cooler, valve three, hose one, quick connector one, needle valve one, sampling bottle, needle valve two, quick connector two, hose two, and valve five; then open valve seven on the bottom pipeline and valve eight on the top pipeline, and put the anthracene oil into the low-level tank again; repeat the above process to repeatedly rinse the sampling pipeline until it is rinsed clean; 4) Flush the traffic pipe; close valve three, valve four and valve five, open valve six and valve two, and the heated anthracene oil will return to the high-level tank from the cleaning medium outlet at the bottom of the low-level tank through valve ten, cooler, valve two, valve six in sequence, and then open valve seven on the bottom pipe and valve eight on the top pipe, and put the anthracene oil back into the low-level tank again. Repeat the above process to flush the traffic pipe repeatedly until it is clean.