CN115140698A

CN115140698A - Oil discharge system

Info

Publication number: CN115140698A
Application number: CN202110352797.1A
Authority: CN
Inventors: 许轲; 张永虎; 汪洋; 吴兰杰; 袁亮; 董小卫; 舒博钊; 刘海龙; 裴晶晶; 朱万雨
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2022-10-04

Abstract

The invention provides an oil unloading system which comprises an oil storage tank, an oil tank truck and an air balance pipeline, wherein the oil storage tank is used for storing crude oil; the oil tank truck comprises a tank body, the tank body is used for collecting crude oil at a dispersion point, and the tank body is communicated with the oil storage tank through an oil discharge pipeline so as to convey the crude oil at the dispersion point into the oil storage tank; the first end of the gas balance pipeline is communicated with the oil storage tank, and the second end of the gas balance pipeline is communicated with the tank body, so that a closed oil unloading environment is formed between the oil tank truck and the oil storage tank. The invention solves the problems of serious oil gas volatilization and potential safety hazard caused by exposure of crude oil in the air in the oil unloading process of the oil tank truck in the prior art.

Description

Oil discharge system

Technical Field

The invention relates to the technical field of crude oil unloading equipment, in particular to an oil unloading system.

Background

With the development and deployment of oil fields, oil areas of a plurality of oil fields are dispersed far away, oil wells cannot be directly connected to an established ground gathering and transportation pipe network, and only the crude oil of the dispersed oil pulling points can be transported to the oil unloading points to be centrally unloaded by adopting a pull transportation mode of an oil tank truck.

In the prior art, the horizontal height of the oil tank truck is increased through the stacking platform, so that crude oil in the oil tank truck is unloaded into the oil storage tank through the hose under the action of gravity, or the oil tank truck and the oil storage tank are connected through the quick connector, so that crude oil in the oil tank truck is unloaded into the oil storage tank through the hose, and when the oil unloading mode is adopted for unloading, the crude oil is exposed in the air, so that oil gas is seriously volatilized, and the potential safety hazard problem exists.

Disclosure of Invention

The invention mainly aims to provide an oil unloading system to solve the problems that in the prior art, crude oil is exposed in the air in the oil unloading process of an oil tank truck, oil gas is seriously volatilized, and potential safety hazards exist.

In order to achieve the above object, the present invention provides an oil discharge system, comprising an oil storage tank, an oil tank truck and an air balance pipeline, wherein the oil storage tank is used for storing crude oil; the oil tank truck comprises a tank body, the tank body is used for collecting crude oil at a dispersion point, and the tank body is communicated with the oil storage tank through an oil discharge pipeline so as to convey the crude oil at the dispersion point into the oil storage tank; the first end of the gas balance pipeline is communicated with the oil storage tank, and the second end of the gas balance pipeline is communicated with the tank body, so that a closed oil discharge environment is formed between the oil tank truck and the oil storage tank.

Further, the oil discharge system also comprises a buffer device, a compressor and an oil gas recovery device, wherein the buffer device is arranged on the gas balance pipeline; the compressor is communicated with the buffer device and is used for compressing oil gas flowing out of the buffer device; the oil gas recovery device is communicated with the compressor and is positioned at the downstream of the compressor, and the oil gas recovery device is used for recovering and treating oil gas compressed and treated by the compressor.

Furthermore, the connecting position of the oil and oil discharging pipeline and the tank body is vertically positioned below the tank body, and the connecting position of the air balance pipeline and the tank body is vertically positioned above the tank body.

Further, the tank truck further comprises a first liquid level monitoring module, the first liquid level monitoring module is arranged on the outer surface of the tank body and communicated with the inside of the tank body, and the first liquid level monitoring module is used for monitoring the liquid level height of crude oil in the tank body in real time.

Further, the oil discharge system also comprises a first oil discharge pump, a flow monitoring module and a first control module, wherein the first oil discharge pump is arranged on the oil discharge pipeline; the flow monitoring module is arranged on the oil unloading pipeline and is used for monitoring the flow information of the oil unloading pipeline in real time; the first control module is connected with the first oil unloading pump, and the first control module controls the oil unloading power of the first oil unloading pump according to the flow information.

Furthermore, the oil unloading system also comprises an earthwork platform, a second oil unloading pump and an oil unloading tank, wherein the oil tank truck is positioned on the earthwork platform, and the earthwork platform is used for increasing the height of the oil tank truck; the second oil unloading pump is arranged on the oil unloading pipeline; the oil discharge tank is arranged on the oil discharge pipeline and located at the upstream of the second oil discharge pump, crude oil in the tank body is discharged into the oil discharge tank, and when the crude oil in the oil discharge tank meets preset conditions, the crude oil in the oil discharge tank is discharged into the oil storage tank.

The oil unloading system further comprises a second liquid level monitoring module and a second control module, wherein the second liquid level monitoring module is arranged in the oil unloading tank and is used for monitoring the liquid level of crude oil in the oil unloading tank; the second control module is connected with the second oil unloading pump, and the second control module controls the second oil unloading pump to be opened and closed according to the liquid level height.

Further, the liquid level height of the crude oil in the oil unloading tank is h, and the oil unloading system further comprises a first preset value A and a second preset value B, wherein A is less than B; when the A is not more than h and is less than B, the second control module controls the second oil unloading pump to be closed; and when h is larger than or equal to B, the second control module controls the second oil discharge pump to be started.

Further, the oil discharge tank is communicated with the gas balance pipeline.

Furthermore, the position where the oil unloading tank is communicated with the air balance pipeline is located above the oil unloading tank in the vertical direction, the oil unloading tank is provided with an oil inlet and an oil outlet, the oil inlet and the oil outlet are respectively located on two sides of the oil unloading tank in the horizontal direction, and the height of the oil inlet is higher than that of the oil outlet in the vertical direction.

Furthermore, the oil unloading tank also comprises an oil inlet pipe, the oil inlet pipe is arranged in the oil unloading tank, the first end of the oil inlet pipe is communicated with the oil unloading pipeline through an oil inlet, the second end of the oil inlet pipe extends towards the bottom of the oil unloading tank, and on the path that the oil inlet pipe extends towards the bottom of the oil unloading tank, part of the oil inlet pipe extends upwards for a preset distance and then extends towards the bottom of the oil unloading tank, so that part of the oil inlet pipe is U-shaped.

Furthermore, the oil discharge system also comprises an oil collecting device which is arranged on the oil discharge pipeline and is provided with an oil collecting tank, and when the tank body finishes the oil discharge operation, the oil collecting tank is used for collecting the residual crude oil in the oil discharge pipeline between the tank body and the oil collecting device.

The oil unloading system with the air balance pipeline is characterized in that the oil storage tank and the oil tank truck are connected through the air balance pipeline, and a closed oil unloading environment can be formed between the oil tank truck and the oil storage tank during the oil unloading process of the tank body of the oil tank truck to the oil storage tank, so that the crude oil is prevented from being exposed in the air, the oil gas volatilization is avoided, and the oil unloading safety is ensured.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 shows a schematic structural view of an oil discharge system according to a first embodiment of the present invention;

FIG. 2 is a schematic view showing the structure of an oil discharge system according to a second embodiment of the present invention;

FIG. 3 shows a schematic structural view of a tank wagon of an oil discharge system according to an alternative embodiment of the invention;

fig. 4 shows a schematic structural view of a discharge tank of the oil discharge system according to an alternative embodiment of the present invention.

Wherein the figures include the following reference numerals:

10. an oil storage tank; 11. a safety valve; 20. a tank wagon; 21. a tank body; 22. a first liquid level monitoring module; 23. a first oil pipe; 24. a first air pipe; 30. an oil discharge pipeline; 31. a check valve; 32. a filtration device; 33. a valve; 40. a gas balance pipeline; 41. a quick coupling; 42. a butterfly valve; 50. a buffer device; 60. a compressor; 70. an oil gas recovery device; 80. a first oil discharge pump; 90. an earthwork high platform; 100. a second oil discharge pump; 110. unloading the oil tank; 1101. an oil inlet; 1102. an oil outlet; 1103. an oil inlet pipe; 1104. a second oil pipe; 1105. a third oil pipe; 1106. a second air pipe; 120. an oil collecting device.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides an oil unloading system, aiming at solving the problems that in the oil unloading process of an oil tank truck in the prior art, crude oil is exposed in air, so that oil gas is seriously volatilized, and potential safety hazards exist.

Example one

As shown in fig. 1, the oil unloading system includes a storage tank 10, a tank truck 20, and an air balance line 40, wherein the storage tank 10 is used for storing crude oil; the oil tank truck 20 comprises a tank body 21, the tank body 21 is used for collecting crude oil at a dispersion point, and the tank body 21 is communicated with the oil storage tank 10 through an oil unloading pipeline 30 so as to convey the crude oil at the dispersion point into the oil storage tank 10; a first end of the gas balance pipeline 40 is communicated with the oil storage tank 10, and a second end of the gas balance pipeline 40 is communicated with the tank body 21, so that a closed oil discharge environment is formed between the oil tank truck 20 and the oil storage tank 10.

The application provides an oil discharge system with gas balance pipeline 40 connects oil storage tank 10 and tank wagon 20 through gas balance pipeline 40, and the jar body 21 at tank wagon 20 is unloading the oil in-process to oil storage tank 10, ensures to form inclosed unloading environment between tank wagon 20 and the oil storage tank 10 to avoid crude oil to expose in the air, and then avoid oil gas to volatilize, ensure the security of unloading.

As shown in fig. 1, the oil discharge system further includes a buffer device 50, a compressor 60 and an oil gas recovery device 70, wherein the buffer device 50 is disposed on the gas balance pipeline 40; the compressor 60 is communicated with the buffer device 50, and the compressor 60 is used for compressing oil gas flowing out of the buffer device 50; the oil gas recovery device 70 is communicated with the compressor 60 and is located at the downstream of the compressor 60, and the oil gas recovery device 70 is used for recovering and treating oil gas compressed by the compressor 60. Therefore, the oil gas recovery device 70 can timely recover oil gas volatilized in the oil unloading process of the oil unloading system, and the problem of potential safety hazards caused by volatilization of the oil gas into air is avoided.

It should be noted that, in the present embodiment, considering that the crude oil is left downwards under its own weight and the gas is volatilized upwards, as shown in fig. 1 and 3, the connection position of the oil unloading and unloading pipeline 30 and the tank 21 is located below the tank 21 in the vertical direction, and the connection position of the gas balance pipeline 40 and the tank 21 is located above the tank 21 in the vertical direction. Thus, the reliability of oil discharge from the tank 21 is ensured.

As shown in fig. 3, the tank truck 20 further includes a first liquid level monitoring module 22, the first liquid level monitoring module 22 is disposed on the outer surface of the tank body 21 and is communicated with the inside of the tank body 21, and the first liquid level monitoring module 22 is used for monitoring the liquid level of the crude oil in the tank body 21 in real time. Like this, ensure that first liquid level monitoring module 22 can expose in operating personnel's sight range to ensure that first liquid level monitoring module 22 can feed back the liquid level height of the crude oil in the jar body 21 to operating personnel in real time, need not operating personnel and pay close attention to in real time at the oil discharge opening and unload the oil mass, reduced operating personnel's work load.

As shown in fig. 1, the oil discharge system further includes a first oil discharge pump 80, a flow rate monitoring module, and a first control module, wherein the first oil discharge pump 80 is disposed on the oil discharge line 30; the flow monitoring module is arranged on the oil unloading pipeline 30 and is used for monitoring the flow information of the oil unloading pipeline 30 in real time; the first control module is connected with the first oil discharge pump 80, and the first control module controls the oil discharge power of the first oil discharge pump 80 according to the flow information. Thus, the intelligent degree of the oil unloading system is improved.

As shown in fig. 1, the oil discharge line 30 is provided with an oil receiving device 120, a check valve 31, a filter 32, a valve 33, a first oil discharge pump 80, and a valve 33 in this order in the direction from the tank wagon 20 to the oil storage tank 10.

Optionally, the unloading line 30 includes a plurality of branches, with the parts on each branch being identical to ensure that different vehicles can be connected to the oil collector 120 through their respective fuel lines at the same time.

Example two

It should be noted that, in the present application, the second embodiment is different from the first embodiment in that, as shown in fig. 2, the oil unloading system further includes an earthwork platform 90, a second oil unloading pump 100 and an oil unloading tank 110, wherein the oil tank truck 20 is located on the earthwork platform 90, and the earthwork platform 90 is used for increasing the height of the oil tank truck 20; the second oil discharge pump 100 is disposed on the oil discharge line 30; the oil discharge tank 110 is disposed on the oil discharge line 30 upstream of the second oil discharge pump 100, the crude oil in the tank body 21 is discharged into the oil discharge tank 110, and when the crude oil in the oil discharge tank 110 satisfies a predetermined condition, the crude oil in the oil discharge tank 110 is discharged into the oil storage tank 10. Thus, the earthwork platform 90 is beneficial to lifting the height of the oil tank truck 20, so that the crude oil in the tank body 21 of the oil tank truck 20 can be discharged under the action of the gravity of the crude oil.

As shown in fig. 2, the oil unloading system further includes a second liquid level monitoring module and a second control module, wherein the second liquid level monitoring module is disposed in the oil unloading tank 110, and the second liquid level monitoring module is used for monitoring the liquid level of the crude oil in the oil unloading tank 110; the second control module is connected with the second oil discharge pump 100, and the second control module controls the second oil discharge pump 100 to be opened and closed according to the liquid level. In this way it is possible to obtain,

optionally, the liquid level of the crude oil in the oil discharge tank 110 is h, and the oil discharge system further comprises a first preset value a and a second preset value B, wherein a is less than B; when A is not less than h and less than B, the second control module controls the second oil discharge pump 100 to close; and when h is larger than or equal to B, the second control module controls the second oil discharge pump 100 to be started. Thus, the intelligent degree of the oil unloading system is improved.

As shown in fig. 2 and 3, the oil dump tank 110 is in communication with the air balance line 40. Therefore, the oil gas volatilized in the process of unloading the crude oil in the tank body 21 into the oil unloading tank 110 can timely flow into the buffer device 50 through the gas balance pipeline 40, then flows into the oil gas recovery device 70 for recovery after being compressed by the compressor 60, and the whole sealing performance of the oil unloading system is ensured.

It should be noted that, in the present embodiment, considering that the crude oil is left downwards under the action of its own gravity, and the gas is volatilized upwards, as shown in fig. 2 and fig. 4, the position where the oil unloading tank 110 is communicated with the gas balance pipeline 40 is located above the oil unloading tank 110 in the vertical direction, the oil unloading tank 110 has an oil inlet 1101 and an oil outlet 1102, the oil inlet 1101 and the oil outlet 1102 are respectively located on two sides of the oil unloading tank 110 in the horizontal direction, and the height of the oil inlet 1101 is higher than that of the oil outlet 1102 in the vertical direction.

As shown in fig. 4, the oil discharge tank 110 further includes an oil inlet pipe 1103, the oil inlet pipe 1103 is disposed in the oil discharge tank 110, a first end of the oil inlet pipe 1103 is communicated with the oil discharge line 30 through an oil inlet 1101, a second end of the oil inlet pipe 1103 extends to the bottom of the oil discharge tank 110, and on a path of the oil inlet pipe 1103 extending to the bottom of the oil discharge tank 110, a part of the oil inlet pipe 1103 extends upward by a predetermined distance and then extends to the bottom of the oil discharge tank 110, so that a part of the oil inlet pipe 1103 is U-shaped. Thus, the formation of static electricity due to the fluid impact of the crude oil in the oil discharge tank 110 is avoided, and the oil discharge reliability of the oil discharge system is ensured.

As shown in fig. 4, the oil drain tank 110 further includes a second oil pipe 1104, a third oil pipe 1105 and a second air pipe 1106, wherein a first end of the second oil pipe 1104 is communicated with the oil drain line 30, a second end of the second oil pipe 1104 is communicated with the oil inlet 1101, a first end of the third oil pipe 1105 is communicated with the oil outlet 1102, a second end of the third oil pipe 1105 is communicated with the oil drain line 30, and the second air pipe 1106 is communicated with the air balance line 40.

As shown in fig. 2, an oil receiving device 120, a check valve 31, an oil discharge tank 110, a filter device 32, a valve 33, and a second oil discharge pump 100 are sequentially provided on the oil discharge line 30 in the direction from the tank truck 20 to the oil storage tank 10.

As shown in fig. 1 and 2, the oil unloading system further includes an oil collecting device 120, the oil collecting device 120 is disposed on the oil unloading pipeline 30, and the oil collecting device 120 has an oil collecting tank for collecting crude oil remaining in the oil unloading pipeline 30 between the tank 21 and the oil collecting device 120 when the tank 21 completes the oil unloading operation. In this way, the crude oil remaining in the oil discharge line 30 between the tank 21 and the oil collector 120 is effectively prevented from escaping and dripping.

As shown in fig. 1 and fig. 2, the tank wagon 20 further comprises a first oil pipe 23 and a first gas pipe 24, wherein the first oil pipe 23 is communicated with a gas balance pipeline 40, a quick coupling 41 and a butterfly valve 42 are arranged at the communication position of the first oil pipe 23 and the gas balance pipeline 40, and the first gas pipe 24 is communicated with the oil unloading pipeline 30.

As shown in fig. 1 and 2, the oil storage tank 10 further includes a relief valve 11 to ensure safety of the oil discharge operation.

It should be noted that, in fig. 3, two reference numerals 41 refer to quick connectors, but not to the same quick connector 41, and each pipeline is provided with a respective quick connector 41.

It should be noted that, in the present application, in order to prevent the freezing and blocking phenomena from occurring in the gas balance pipeline 40 and the oil discharge pipeline 30 at the low ambient temperature, the gas balance pipeline 40 and the oil discharge pipeline 30 are respectively provided with the electric tracing, and when the ambient temperature is lower than 20 ℃, the electric tracing on the gas balance pipeline 40 and the electric tracing on the oil discharge pipeline 30 can both be automatically started to prevent the freezing and blocking phenomena from occurring in the gas balance pipeline 40 and the oil discharge pipeline 30.

It should be noted that, in the present application, the oil discharge system includes a quick coupling and a butterfly valve in turn on the gas balance line 40 from the tank 21 to the oil storage tank 10.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

For ease of description, spatially relative terms such as "over 8230 \ 8230;,"' over 8230;, \8230; upper surface "," above ", etc. may be used herein to describe the spatial relationship of one device or feature to another device or feature as shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary terms "at 8230; \8230; 'above" may include both orientations "at 8230; \8230;' above 8230; 'at 8230;' below 8230;" above ". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise, and it should be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of this application and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are capable of operation in other sequences than those illustrated or described herein.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An oil discharge system, comprising:

an oil storage tank (10), the oil storage tank (10) being for storing crude oil;

the oil tank truck (20), the oil tank truck (20) comprises a tank body (21), the tank body (21) is used for collecting crude oil at a dispersion point, and the tank body (21) is communicated with the oil storage tank (10) through an oil discharge pipeline (30) so as to convey the crude oil at the dispersion point into the oil storage tank (10);

the first end of gas balance pipeline (40) with oil storage tank (10) intercommunication, the second end of gas balance pipeline (40) with jar body (21) intercommunication, so that tank wagon (20) with form inclosed oil discharge environment between oil storage tank (10).

2. The oil discharge system of claim 1, further comprising:

a buffer device (50), wherein the buffer device (50) is arranged on the air balance pipeline (40);

the compressor (60), the compressor (60) is communicated with the buffer device (50), and the compressor (60) is used for compressing oil gas flowing out of the buffer device (50);

the oil gas recovery device (70), oil gas recovery device (70) with compressor (60) intercommunication and being located the downstream of compressor (60), oil gas recovery device (70) are used for to the process the oil gas after compressor (60) compression treatment carries out recovery processing.

3. The oil discharge system according to claim 1, wherein the connection position of the oil discharge and oil discharge pipeline (30) and the tank body (21) is vertically below the tank body (21), and the connection position of the gas balance pipeline (40) and the tank body (21) is vertically above the tank body (21).

4. The oil discharge system according to claim 1, wherein the tank wagon (20) further comprises:

the oil tank comprises a first liquid level monitoring module (22), wherein the first liquid level monitoring module (22) is arranged on the outer surface of the tank body (21) and communicated with the inside of the tank body (21), and the first liquid level monitoring module (22) is used for monitoring the liquid level height of crude oil in the tank body (21) in real time.

5. The oil drain system of claim 4, further comprising:

a first oil discharge pump (80), the first oil discharge pump (80) being disposed on the oil discharge line (30);

the flow monitoring module is arranged on the oil unloading pipeline (30) and is used for monitoring the flow information of the oil unloading pipeline (30) in real time;

the first control module is connected with the first oil unloading pump (80), and the first control module controls the oil unloading power of the first oil unloading pump (80) according to the flow information.

6. The oil drain system of claim 4, further comprising:

the oil tank truck (20) is positioned on the earthwork platform (90), and the earthwork platform (90) is used for increasing the height of the oil tank truck (20);

a second oil discharge pump (100), the second oil discharge pump (100) being disposed on the oil discharge line (30);

the oil unloading tank (110) is arranged on the oil unloading pipeline (30) and located at the upstream of the second oil unloading pump (100), crude oil in the tank body (21) is unloaded into the oil unloading tank (110), and when the crude oil in the oil unloading tank (110) meets preset conditions, the crude oil in the oil unloading tank (110) is unloaded into the oil storage tank (10).

7. The oil drain system of claim 6, further comprising:

a second liquid level monitoring module disposed within the oil dump tank (110), the second liquid level monitoring module for monitoring a liquid level of crude oil within the oil dump tank (110);

and the second control module is connected with the second oil unloading pump (100), and controls the second oil unloading pump (100) to be opened and closed according to the liquid level.

8. The oil discharge system of claim 7, wherein the level of crude oil in the oil discharge tank (110) is h, the oil discharge system further comprising a first preset value A and a second preset value B, wherein A < B;

when A is more than or equal to h and less than B, the second control module controls the second oil unloading pump (100) to close;

and when h is larger than or equal to B, the second control module controls the second oil discharge pump (100) to be started.

9. An oil discharge system according to claim 6, wherein the oil discharge tank (110) is in communication with the gas balance line (40).

10. The oil discharge system according to claim 9, wherein the oil discharge tank (110) is in communication with the gas balance pipeline (40) at a position vertically above the oil discharge tank (110), the oil discharge tank (110) has an oil inlet (1101) and an oil outlet (1102), the oil inlet (1101) and the oil outlet (1102) are respectively located on both sides of the oil discharge tank (110) in the horizontal direction, and the height of the oil inlet (1101) is higher than the height of the oil outlet (1102) in the vertical direction.

11. The oil discharge system of claim 10, wherein the oil discharge tank (110) further comprises:

oil inlet pipe (1103), oil inlet pipe (1103) sets up in oil unloading tank (110), oil inlet pipe (1103)'s first end is passed through oil inlet (1101) with oil unloading pipeline (30) intercommunication, oil inlet pipe (1103)'s second end to the tank bottoms of oil unloading tank (110) extend the setting oil inlet pipe (1103) to on the route that the tank bottoms of oil unloading tank (110) extend, part oil inlet pipe (1103) upwards extend and predetermine the distance after to extend again the tank bottoms of oil unloading tank (110) extend, so that the part oil inlet pipe (1103) is the U type.

12. The oil discharge system of claim 1, further comprising:

the oil collecting device (120) is arranged on the oil unloading pipeline (30), the oil collecting device (120) is provided with an oil collecting groove, and when the tank body (21) finishes oil unloading operation, the oil collecting groove is used for collecting residual crude oil in the oil unloading pipeline (30) between the tank body (21) and the oil collecting device (120).