Unloading system and method for easily vaporizable liquid tank truck

Abstract

The present invention discloses an unloading system and method for a tank truck of easily vaporizable liquid, wherein the unloading system comprises a plurality of tank truck units, a liquid storage tank, and a plurality of compressors, wherein the liquid phase ports of the plurality of tank truck units are connected to the liquid phase ports of the liquid storage tank via a liquid phase pipeline, and the gas phase ports of the liquid storage tank are connected to the gas phase ports of a plurality of tank truck units via a gas phase pipeline assembly, and a plurality of compressors are arranged on the gas phase pipeline assembly. The present invention solves the current problem of using a centrifugal pump or a vane pump to directly unload the tank truck at the tank truck outlet by punching the tank truck so that the liquid material in the tank truck is automatically output to the liquid storage tank; the present invention can also realize the unloading of a plurality of tank trucks at the same time, and a plurality of compressors can freely switch between the standby and working states (punching or pumping), with high efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of liquid unloading, and in particular to an unloading system and method for a tank truck of easily vaporizable liquid. Background Art

[0002] At present, the method of unloading easily vaporized liquids (such as propylene) is generally to unload directly through a centrifugal pump or a vane pump connected in series at the outlet of the tank truck. However, because such liquids are very easy to vaporize, long-term operation of the centrifugal pump under cavitation conditions will seriously affect its service life, and it is inefficient and unsafe. Although the vane pump does not have the cavitation phenomenon of the centrifugal pump, because it is a positive displacement pump, it is very likely to have inlet vaporization and outlet pulse phenomenon, the pump load is unstable, the service life is short, and the conveying pipeline may also have pulse vibration during long-distance transportation. In addition, the unloading efficiency is low, the speed is slow, and the safety is also not guaranteed. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides an unloading system and method for a tank truck of easily vaporizable liquid.

[0004] In order to achieve the above-mentioned purpose, the technical scheme of the present invention is: an unloading system for a tank truck of easily vaporizable liquid, characterized in that it includes multiple tank truck units, liquid storage tanks, several compressors, a stamping line, and a pressure equalizing line; each tank truck unit includes a tank truck, an unloading crane position, and a multi-way valve, the unloading crane position is connected to the gas phase interface of the tank truck through a gas phase crane pipe, the unloading crane position is connected to the liquid phase interface of the tank truck through a liquid phase crane pipe, the multi-way valve includes multiple interfaces, and the outlet of the multi-way valve is connected to the unloading crane position through a pipeline; the liquid phase outlet of the liquid storage tank is connected to the unloading crane position through a liquid phase pipeline, and the gas phase outlet of the liquid storage tank is connected to the gas phase pipeline;

[0005] The inlet of each compressor is connected to the first branch line, and the outlet is connected to the third branch line and the fourth branch line in parallel. The first branch line is merged into the gas phase pipeline, the third branch line is merged into the stamping line, and the fourth branch line is merged into the equalizing pressure line. One end of the stamping line and one end of the equalizing pressure line are respectively connected to different inlets of the multi-way valve of each tank truck unit through branches, and the other end of the equalizing pressure line is merged into the gas phase pipeline.

[0006] Furthermore, it also includes a vapor-liquid separation tank and a pressure extraction line; the gas phase outlet of the liquid storage tank is connected to the gas phase inlet of the vapor-liquid separation tank through the first gas phase line, the gas phase outlet of the vapor-liquid separation tank is connected to the second gas phase line, and the inlet of each compressor is also connected to the second branch line, the first branch line is merged into the second gas phase line, and the second branch line is merged into the pressure extraction line;

[0007] The multi-way valve is a four-position four-way valve, which includes a BF open position, a CG open position, a DH open position and an AE closed position. The H port, G port and F port of the four-position four-way valve are all connected to the unloading crane position through pipelines; one end of the stamping line is connected to the B port of the four-position four-way valve of each tank truck unit through branches, one end of the pressure equalizing line is connected to the C port of the four-position four-way valve of each tank truck unit through branches, one end of the pressure extraction line is connected to the D port of the four-position four-way valve of each tank truck unit through branches, and the other end of the pressure equalizing line is merged into the first gas phase line; valves are provided on the gas phase crane pipe, liquid phase crane pipe, liquid phase pipeline, first gas phase line, second gas phase line, first branch line, second branch line, third branch line and fourth branch line.

[0008] Furthermore, a regulating valve is provided on the second gas phase line.

[0009] Furthermore, the stamping line is connected to a first remote pressure transmitter through a pipeline, and part of the compressor and the regulating valve are electrically connected to the first remote pressure transmitter.

[0010] Furthermore; the liquid phase pipeline is provided with a first valve and a second valve, the first valve is close to the liquid phase outlet of the liquid storage tank, the liquid phase pipeline is provided with branches at both ends of the second valve, the branch lines are provided with a third valve, a pipeline pump and a fourth valve in sequence, the liquid phase pipeline is connected to the second remote pressure transmitter through a pipeline, and the pipeline pump is electrically connected to the second remote pressure transmitter.

[0011] Furthermore, the inlet of each compressor is also connected to the fifth branch line, and the outlet is connected to the sixth branch line. After the fifth branch line and the sixth branch line are merged, they are merged into the flare line through the seventh branch line. The fifth branch line, the sixth branch line and the seventh branch line are all provided with valves.

[0012] Furthermore, an electrostatic grounding interlock is provided between the multi-way valve and the tank truck, the liquid phase pipeline is merged into the flare line through an eighth branch line, and a valve is provided on the eighth branch line.

[0013] Another technical solution of the present invention is: a method for unloading a vehicle using the above-mentioned unloading system, characterized in that it comprises the following steps:

[0014] Step 1: Open the valves on the gas phase crane pipe, the liquid phase crane pipe, the liquid phase pipeline, the first gas phase line and the second gas phase line, open the first branch line valve at the compressor inlet electrically connected to the first remote pressure transmitter, open the third branch line valve at the outlet, and close the remaining valves;

[0015] Step 2: Start the compressor electrically connected to the first remote pressure transmitter. When the pressure of the stamping line rises to a value close to that of the tank truck, operate the four-position four-way valve to rotate the valve core of the four-position four-way valve from the AE closed position to the BF open position. The stamping line is connected to the tank truck, and the regulating valve automatically adjusts the opening according to the pressure signal output by the first remote pressure transmitter. The compressor electrically connected to the first remote pressure transmitter automatically adjusts the speed according to the pressure signal output by the first remote pressure transmitter.

[0016] Step 3: Under the action of the compressor, the pressure in the tank truck continues to increase. When the pressure in the tank truck is greater than the pressure in the liquid storage tank, the liquid material in the tank truck will be pressed into the liquid storage tank until the unloading is completed;

[0017] Step 4: After the unloading is completed, the compressor electrically connected to the first remote pressure transmitter is turned off, the liquid phase crane valve is closed, and the four-position four-way valve is operated to rotate the valve core of the four-position four-way valve from the BF open position to the CG open position, and the tank truck is connected to the pressure equalizing line to balance the pressure in the tank truck with the pressure in the liquid storage tank;

[0018] Step 5: When the pressure in the tank truck needs to be lower than that in the liquid storage tank, operate the four-position four-way valve, rotate the valve core of the four-way valve from the CG open position to the DH open position, connect the tank truck with the pressure extraction line, close the first branch valve at the inlet of the compressor electrically connected to the first remote pressure transmitter and the third branch valve at the outlet, open the remaining compressors, and the second branch valve at the inlet and the fourth branch valve at the outlet. At this time, the compressor inlet that is not electrically connected to the first remote pressure transmitter is connected to the pressure extraction line, and the outlet is connected to the pressure equalization line. Under the action of the compressor, the pressure in the tank truck continues to drop;

[0019] Step six, when the pressure in the tank truck reaches the requirement, operate the four-position four-way valve, rotate the four-way valve core from the DH open position to the AE closed position, and close the compressor, the second branch valve at the inlet, and the fourth branch valve at the outlet.

[0020] Furthermore; the liquid phase pipeline is provided with a first valve and a second valve, the first valve is close to the liquid phase outlet of the liquid storage tank, the liquid phase pipeline is provided with branches at both ends of the second valve, the branch lines are sequentially provided with a third valve, a pipeline pump and a fourth valve, the liquid phase pipeline is connected to the second remote pressure transmitter through the pipeline, and the pipeline pump is electrically connected to the second remote pressure transmitter; in the step one, when the material in the tank truck needs to be transmitted over a long distance, the first valve, the third valve, the pipeline pump and the fourth valve on the liquid phase pipeline are further opened, and the second valve is closed; the pipeline pump automatically adjusts the speed according to the pressure signal output by the second remote pressure transmitter.

[0021] Furthermore; the inlet of each compressor is also connected to the fifth branch line, and the outlet is connected to the sixth branch line. The fifth branch line and the sixth branch line are merged and then merged into the flare line through the seventh branch line. The fifth branch line, the sixth branch line and the seventh branch line are all provided with valves; and step seven is also included, when the compressor needs maintenance, the valves on the fifth branch line, the sixth branch line and the seventh branch line are opened, the other valves are closed, and the compressor is emptied and then maintained.

[0022] Beneficial effects of the present invention:

[0023] 1) By punching the tank truck, the liquid materials in the tank truck are automatically output to the liquid storage tank, solving the current problem of using centrifugal pumps or vane pumps to directly unload the tank truck at the tank truck outlet;

[0024] 2) The present invention can realize the simultaneous unloading of multiple tank trucks, and multiple compressors can be freely switched between standby and working states (pressing or pumping), with high efficiency;

[0025] 3) By installing a pipeline pump on the liquid phase pipeline branch line, the ultra-long-distance transmission of materials in the tank truck can be achieved, and the pressure during the tank truck unloading stamping can be appropriately reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of the present invention.

[0027] In the figure: 1. tank truck; 2. unloading crane position; 3. four-position four-way valve; 4. gas phase crane pipe; 5. liquid phase crane pipe; 6. liquid storage tank; 7. liquid phase pipeline; 8. first gas phase line; 9. vapor-liquid separation tank; 10. second gas phase line; 11. compressor; 12. first branch line; 13. second branch line; 14. fifth branch line; 15. third branch line; 16. fourth branch line; 17. sixth branch line; 18. pumping line; 19. stamping line; 20. equalizing pressure line; 21. seventh branch line; 22. flare removal line; 23. first remote pressure transmitter; 24. regulating valve; 25. first valve; 26. second valve; 27. third valve; 28. pipeline pump; 29. ​​fourth valve; 30. second remote pressure transmitter; 31. eighth branch line. DETAILED DESCRIPTION

[0028] Embodiment 1:

[0029] like Figure 1 As shown, a tank truck unloading system for easily vaporized liquids includes a plurality of tank truck units, a liquid storage tank 6, four compressors 11, a vapor-liquid separation tank 9, a punching line 19, a pressure equalizing line 20, a pressure extraction line 18, and a flare removal line 22.

[0030] Each tank truck unit includes a tank truck 1, an unloading crane position 2 and a four-position four-way valve 3. The unloading crane position 2 is connected to the gas phase interface of the tank truck 1 through a gas phase crane pipe 4, and the unloading crane position 2 is connected to the liquid phase interface of the tank truck 1 through a liquid phase crane pipe 5. The four-position four-way valve 3 includes a BF open position, a CG open position, a DH open position and an AE closed position. The H port, G port and F port of the four-position four-way valve are all connected to the unloading crane position 2 through pipelines.

[0031] The liquid phase outlet of the liquid storage tank 6 is connected to each tank truck unit unloading crane position 2 through a liquid phase pipeline 7, the gas phase outlet of the liquid storage tank 6 is connected to the gas phase inlet of the gas-liquid separation tank 9 through a first gas phase line 8, and the gas phase outlet of the gas-liquid separation tank 9 is connected to a second gas phase line 10.

[0032] The inlet of each compressor 11 is connected in parallel to the first branch line 12, the second branch line 13 and the fifth branch line 14, and the outlet is connected in parallel to the third branch line 15, the fourth branch line 16 and the sixth branch line 17. The first branch line 12 is merged into the second gas phase line 10, the second branch line 13 is merged into the suction line 18, the third branch line 15 is merged into the stamping line 19, the fourth branch line 16 is merged into the equalizing pressure line 20, and the fifth branch line 14 and the sixth branch line 17 are merged and merged into the flare removal line 22 through the seventh branch line 21.

[0033] One end of the punching line 19 is connected to the B port of the four-position four-way valve 3 of each tank truck unit through a branch, one end of the pressure equalizing line 20 is connected to the C port of the four-position four-way valve 3 of each tank truck unit through a branch, one end of the pressure extraction line 18 is connected to the D port of the four-position four-way valve 3 of each tank truck unit through a branch, and the other end of the pressure equalizing line 20 is merged into the first gas phase line 8.

[0034] The stamping line 19 is connected to the first remote pressure transmitter 23 through a pipeline. The second gas phase line 10 is also provided with a regulating valve 24 . The regulating valve 24 is electrically connected to the first remote pressure transmitter 23 . The two compressors 11 are electrically connected to the first remote pressure transmitter 23 .

[0035] The liquid phase pipeline 7 is provided with a first valve 25 and a second valve 26, wherein the first valve 25 is close to the liquid phase outlet of the liquid storage tank 5, and the liquid phase pipeline 7 is provided with branches at both ends of the second valve 26, and the branch lines are provided with a third valve 27, a pipeline pump 28 and a fourth valve 29 in sequence, and the liquid phase pipeline 7 is connected to the second remote pressure transmitter 30 through a pipeline, and the pipeline pump 28 is electrically connected to the second remote pressure transmitter 30.

[0036] The gas phase crane pipe 4, the liquid phase crane pipe 5, the first gas phase line 8, the second gas phase line 10, the first branch line 12, the second branch line 13, the third branch line 15, the fourth branch line 16, the fifth branch line 14, the sixth branch line 17 and the seventh branch line 21 are all provided with valves.

[0037] As an optimization solution of this embodiment, an electrostatic grounding interlock is provided between the four-position four-way valve 3 and the tank truck 1 .

[0038] As an optimization solution of this embodiment, the liquid phase pipeline 7 is merged into the flare removal line 22 through the eighth branch line 31 , and the eighth branch line 31 is provided with a valve.

[0039] Embodiment 2:

[0040] like Figure 1 As shown, a method for unloading a tank truck of easily vaporizable liquids comprises the following steps:

[0041] Step 1: First, purge and clean the pipeline, valve and vapor-liquid separation tank 9, and fill the other pipelines except the liquid phase pipeline 7 with the gas phase of the liquid by venting or replacing, so that the liquid phase fills the liquid phase pipeline 7;

[0042] Open the valves on the gas phase crane pipe 4, the liquid phase crane pipe 5, the first gas phase line 8 and the second gas phase line 10, open the first valve 25 and the second valve 26 of the liquid phase pipeline 7, open the valve of the first branch line 12 at the inlet of the compressor 11 electrically connected to the first remote pressure transmitter 23, open the valve of the third branch line 15 at the outlet, and close the remaining valves;

[0043] Step 2, start the compressor 11 electrically connected to the first remote pressure transmitter 23, when the pressure of the stamping line 19 rises to be close to the pressure of the tank car 1, operate the four-position four-way valve 3, rotate the valve core from the AE closed position to the BF open position, the stamping line 19 is connected to the tank car 1, the regulating valve 24 automatically adjusts the opening according to the setting according to the pressure signal output by the first remote pressure transmitter 23, and the compressor 11 electrically connected to the first remote pressure transmitter 23 automatically adjusts the speed according to the setting according to the pressure signal output by the first remote pressure transmitter 23;

[0044] Step 3: Under the action of the compressor 11 electrically connected to the first remote pressure transmitter 23, the pressure in the tank truck 1 continues to increase. When the pressure in the tank truck 1 is greater than the pressure in the liquid storage tank 6, the liquid material in the tank truck 1 will be pressed into the liquid storage tank 6 until the unloading is completed.

[0045] Step 4: After the unloading is completed, the compressor 11 electrically connected to the first remote pressure transmitter 23 is turned off, the valve of the liquid phase crane pipe 5 is closed, and the four-position four-way valve 3 is operated to rotate the valve core from the BF open position to the CG open position, so that the tank truck 1 is connected to the pressure equalizing line 20, so that the pressure in the tank truck 1 is equalized with the pressure in the liquid storage tank 6;

[0046] Step 5, when the pressure in the tank truck 1 needs to be lower than that in the liquid storage tank 6, operate the four-position four-way valve 3 to rotate the valve core from the CG open position to the DH open position, connect the tank truck 1 with the pressure extraction line 18, close the valve of the first branch line 12 at the inlet of the compressor 11 electrically connected to the first remote pressure transmitter 23 and the valve of the third branch line 15 at the outlet, open the remaining compressors 11 not electrically connected to the first remote pressure transmitter 23, and the valve of the second branch line 13 at the inlet and the valve of the fourth branch line 16 at the outlet. At this time, the inlet of the compressor 11 not electrically connected to the first remote pressure transmitter 23 is connected to the pressure extraction line 18, and the outlet is connected to the equalizing pressure line 20. Under the action of the compressor 11, the pressure in the tank truck 1 continues to drop;

[0047] Step 6, when the pressure in the tank truck 1 reaches the required pressure, operate the four-position four-way valve 3 to rotate the valve core from the DH open position to the AE closed position, and close the compressor 11 that is not electrically connected to the first remote pressure transmitter 23, and the valve of the second branch line 13 at the inlet and the valve of the fourth branch line 16 at the outlet;

[0048] Step seven, when the compressor 11 needs maintenance, open the valves on the fifth branch line 14, the sixth branch line 17 and the seventh branch line 21, close the other valves, and perform maintenance after venting.

[0049] As an optimization scheme of this embodiment, the electrostatic grounding condition of the tank truck 1 is checked through the electrostatic grounding interlock. If the electrostatic grounding is unqualified before unloading begins, the valve core of the four-position four-way valve 3 is always in the AE closed position and cannot operate normally.

[0050] Embodiment 3:

[0051] like Figure 1 As shown, a method for unloading a tank truck of an easily vaporizable liquid is different from that of Example 2 in that:

[0052] Step 1: First, purge and clean the pipeline, valve and vapor-liquid separation tank 9, and fill the other pipelines except the liquid phase pipeline 7 with the gas phase of the liquid by venting or replacing, so that the liquid phase fills the liquid phase pipeline 7;

[0053] When the material in the tank truck 1 needs to be transported over a long distance, open the valves on the gas phase crane pipe 4, the liquid phase crane pipe 5, the first gas phase line 8 and the second gas phase line 10, open the first valve 25, the third valve 27, the pipeline pump 28 and the fourth valve 29 of the liquid phase pipeline 7, open the valve of the first branch line 12 at the inlet of the compressor 11 electrically connected to the first remote pressure transmitter 23, open the valve of the third branch line 15 at the outlet, close the remaining valves, and the pipeline pump 28 automatically adjusts the speed according to the setting based on the pressure signal output by the second remote pressure transmitter 30.

[0054] Embodiment 4:

[0055] like Figure 1 As shown, a method for unloading a tank truck of an easily vaporizable liquid is different from that of Example 2 in that:

[0056] Step three, under the action of the compressor 11 electrically connected to the first remote pressure transmitter 23, the pressure in the tank truck 1 continues to increase. When the pressure in the tank truck 1 is greater than the pressure in the liquid storage tank 6, the liquid material in the tank truck 1 will be pressed into the liquid storage tank 6 until the unloading is completed. During the unloading process, when the pressure in the tank truck 1 is too high, the second valve 26 of the liquid phase pipeline 7 is closed, and the third valve 27, the pipeline pump 28 and the fourth valve 29 are opened. The pipeline pump 28 automatically adjusts the speed according to the setting based on the pressure signal output by the second remote pressure transmitter 30.

[0057] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

[0058] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

Claims

1. A tank truck unloading system for easily vaporizable liquids, characterized in that: It includes multiple tank truck units, liquid storage tanks, several compressors, a stamping line, and a pressure equalizing line; each tank truck unit includes a tank truck, a truck unloading crane position, and a multi-way valve, the truck unloading crane position is connected to the tank truck gas phase interface through a gas phase crane pipe, the truck unloading crane position is connected to the tank truck liquid phase interface through a liquid phase crane pipe, the multi-way valve includes multiple interfaces, and the multi-way valve outlet is connected to the truck unloading crane position through a pipeline; the liquid phase outlet of the liquid storage tank is connected to the truck unloading crane position through a liquid phase pipeline, and the gas phase outlet of the liquid storage tank is connected to the gas phase pipeline; The inlet of each compressor is connected to the first branch line, and the outlet is connected to the third branch line and the fourth branch line in parallel. The first branch line is merged into the gas phase pipeline, the third branch line is merged into the stamping line, and the fourth branch line is merged into the equalizing pressure line. One end of the stamping line and one end of the equalizing pressure line are respectively connected to different inlets of each tank car unit multi-way valve through branches, and the other end of the equalizing pressure line is merged into the gas phase pipeline; It also includes a vapor-liquid separation tank and a pumping and pressure line; the gas phase outlet of the liquid storage tank is connected to the gas phase inlet of the vapor-liquid separation tank through a first gas phase line, the gas phase outlet of the vapor-liquid separation tank is connected to a second gas phase line, and the inlet of each compressor is also connected to a second branch line, the first branch line is merged into the second gas phase line, and the second branch line is merged into the pumping and pressure line; The multi-way valve is a four-position four-way valve, which includes a BF open position, a CG open position, a DH open position and an AE closed position. The H port, G port and F port of the four-position four-way valve are all connected to the unloading crane position through pipelines; one end of the stamping line is connected to the B port of each tank truck unit's four-position four-way valve through a branch, one end of the pressure equalizing line is connected to the C port of each tank truck unit's four-position four-way valve through a branch, one end of the pressure extraction line is connected to the D port of each tank truck unit's four-position four-way valve through a branch, and the other end of the pressure equalizing line is merged into the first gas phase line; the gas phase crane pipe, liquid phase crane pipe, liquid phase pipeline, first gas phase line, second gas phase line, first branch line, second branch line, third branch line and fourth branch line are all provided with valves; The second gas phase line is provided with a regulating valve; The stamping line is connected to a first remote pressure transmitter via a pipeline, and some of the compressors and regulating valves are electrically connected to the first remote pressure transmitter; The liquid phase pipeline is provided with a first valve and a second valve, wherein the first valve is close to the liquid phase outlet of the liquid storage tank, and the liquid phase pipeline is provided with branches at both ends of the second valve, and the branches are provided with a third valve, a pipeline pump and a fourth valve in sequence, and the liquid phase pipeline is connected to the second remote pressure transmitter through a pipeline, and the pipeline pump is electrically connected to the second remote pressure transmitter.

2. The unloading system for a tank truck of easily vaporizable liquid according to claim 1, characterized in that: The inlet of each compressor is also connected to the fifth branch line, and the outlet is connected to the sixth branch line. After the fifth branch line and the sixth branch line are merged, they are merged into the flare line through the seventh branch line. Valves are provided on the fifth branch line, the sixth branch line and the seventh branch line.

3. The unloading system for a tank truck of easily vaporizable liquid according to claim 1, characterized in that: An electrostatic grounding interlock is arranged between the multi-way valve and the tank truck, and the liquid phase pipeline is merged into the flare line through an eighth branch line, and a valve is arranged on the eighth branch line.

4. A method for unloading a tank truck using the unloading system for easily vaporizable liquids as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Open the valves on the gas phase crane pipe, the liquid phase crane pipe, the liquid phase pipeline, the first gas phase line and the second gas phase line, open the first branch line valve at the compressor inlet electrically connected to the first remote pressure transmitter, open the third branch line valve at the outlet, and close the remaining valves; Step 2: Start the compressor electrically connected to the first remote pressure transmitter. When the pressure of the stamping line rises to a value close to that of the tank truck, operate the four-position four-way valve to rotate the valve core of the four-position four-way valve from the AE closed position to the BF open position. The stamping line is connected to the tank truck, and the regulating valve automatically adjusts the opening according to the pressure signal output by the first remote pressure transmitter. The compressor electrically connected to the first remote pressure transmitter automatically adjusts the speed according to the pressure signal output by the first remote pressure transmitter. Step 3: Under the action of the compressor, the pressure in the tank truck continues to increase. When the pressure in the tank truck is greater than the pressure in the liquid storage tank, the liquid material in the tank truck will be pressed into the liquid storage tank until the unloading is completed; Step 4: After the unloading is completed, the compressor electrically connected to the first remote pressure transmitter is turned off, the liquid phase crane valve is closed, and the four-position four-way valve is operated to rotate the valve core of the four-position four-way valve from the BF open position to the CG open position, and the tank truck is connected to the pressure equalizing line to balance the pressure in the tank truck with the pressure in the liquid storage tank; Step 5: When the pressure in the tank truck needs to be lower than that in the liquid storage tank, operate the four-position four-way valve, rotate the valve core of the four-way valve from the CG open position to the DH open position, connect the tank truck with the pressure extraction line, close the first branch valve at the inlet of the compressor electrically connected to the first remote pressure transmitter and the third branch valve at the outlet, open the remaining compressors, and the second branch valve at the inlet and the fourth branch valve at the outlet. At this time, the compressor inlet that is not electrically connected to the first remote pressure transmitter is connected to the pressure extraction line, and the outlet is connected to the pressure equalization line. Under the action of the compressor, the pressure in the tank truck continues to drop; Step six, when the pressure in the tank truck reaches the requirement, operate the four-position four-way valve, rotate the four-way valve core from the DH open position to the AE closed position, and close the compressor, the second branch valve at the inlet, and the fourth branch valve at the outlet.

5. The unloading method of the unloading system of the easily vaporizable liquid tank truck according to claim 4, characterized in that: The liquid phase pipeline is provided with a first valve and a second valve, the first valve is close to the liquid phase outlet of the liquid storage tank, the liquid phase pipeline is provided with branches at both ends of the second valve, the branches are provided with a third valve, a pipeline pump and a fourth valve in sequence, the liquid phase pipeline is connected to the second remote pressure transmitter through a pipeline, and the pipeline pump is electrically connected to the second remote pressure transmitter; In the step one, when the material in the tank truck needs to be transported over a long distance, the first valve, the third valve, the pipeline pump and the fourth valve on the liquid phase pipeline are further opened, and the second valve is closed; the pipeline pump automatically adjusts the speed according to the pressure signal output by the second remote pressure transmitter.

6. The unloading method of the unloading system of the easily vaporizable liquid tank truck according to claim 4, characterized in that: The inlet of each compressor is also connected to the fifth branch line, and the outlet is connected to the sixth branch line. After the fifth branch line and the sixth branch line are combined, they are merged into the flare line through the seventh branch line. The fifth branch line, the sixth branch line and the seventh branch line are all provided with valves; The step also includes step seven, when the compressor needs maintenance, opening the valves on the fifth branch line, the sixth branch line and the seventh branch line, closing other valves, and performing maintenance after venting.

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