Residual liquid discharging and tank body cleaning device for buried sump oil collecting tank

Abstract

The utility model discloses a residual liquid discharging and tank body cleaning device for a buried sump oil collecting tank. The residual liquid discharging and tank body cleaning device comprises a liquid collecting device, an exhaust device, a liquid discharging device, an auxiliary liquid discharging device and a cleaning device, the liquid collecting device is arranged underground, a liquid inlet and a liquid collecting bag are arranged on the surface of the liquid collecting device, and the liquid collecting bag is located at the bottom of the liquid collecting device and protrudes in the direction away from the ground; the exhaust device is communicated with the top of the liquid collecting device; the liquid discharging device extends into the liquid collecting bag from the top of the liquid collecting device; the auxiliary liquid discharging device comprises a buffer tank, residue discharging pipes and a closed discharging auxiliary pump, the buffer tank is arranged above the ground, the residue discharging pipes are installed at the bottom of the buffer tank and extend into the bottoms of the liquid collecting bags, the closed discharging auxiliary pump is installed at the bottom of the buffer tank, and the number of the residue discharging pipes is consistent with that of the liquid collecting bags; and the cleaning device extends into the liquid collecting device from the top of the liquid collecting device.

Description

Technical Field

[0001] The present application belongs to the technical field of oil and gas processing, and specifically relates to a device for removing residual liquid from an underground waste oil collection tank and for cleaning the tank body. Background Art

[0002] Oil and gas processing plants are equipped with underground waste oil collection tanks. These tanks collect oil and gas discharged during maintenance and overhaul at various wastewater discharge points within the plant through buried pipelines, forming a closed wastewater discharge system (hereinafter referred to as the closed discharge system). Because the materials handled by this system are flammable, explosive, toxic, and hazardous, the system must be completely sealed and maintain a slight positive pressure within the tank.

[0003] Conventional buried closed-drain systems typically use single-screw pumps for their closed-drain pumps. The pumps start when the liquid level is high and stop when it is low. The stop level is determined by the pump's ability to avoid cavitation. To maximize the capacity of the waste oil collection tank, a "liquid collection bag" is typically installed at the tank bottom, with the closed-drain pump inserted into it to minimize the stop level. However, the lowest liquid level is always higher than the tank bottom elevation, meaning the closed-drain pump alone cannot completely drain the tank.

[0004] When the waste oil collection tank needs to be opened for any reason, such as when a closed-discharge pump needs to be withdrawn for maintenance or when the tank's instrumentation needs to be repaired, the toxic and hazardous gases within the tank must first be replaced. Conventional waste oil collection tanks and systems cannot completely drain the liquid within the tank, and because oil is lighter than water, the liquid remaining in the tank is often "condensate oil," a very low-density, highly volatile substance. This "condensate oil" continues to evaporate, making it very easy for the nitrogen replacement to fail for extended periods, preventing maintenance work and severely impacting production. Therefore, the development of a device that can quickly drain the residual liquid from the tank is urgently needed. Utility Model Content

[0005] The present application aims to provide a device for removing residual liquid from an underground waste oil collection tank and for cleaning the tank body, so as to solve the problem that the liquid in the waste oil collection tank cannot be completely drained.

[0006] In order to solve the above technical problems, this application is implemented as follows:

[0007] In a first aspect, an embodiment of the present application provides a device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body, comprising: a liquid collecting device, an exhaust device, a liquid draining device, an auxiliary liquid draining device, and a cleaning device;

[0008] The liquid collecting device is arranged below the ground, and a liquid inlet and a liquid collecting bag are arranged on the surface of the liquid collecting device. The liquid collecting bag is located at the bottom of the liquid collecting device and protrudes away from the ground.

[0009] The exhaust device is in communication with the top of the liquid collecting device;

[0010] The liquid draining device extends from the top of the liquid collecting device into the liquid collecting bag;

[0011] The auxiliary liquid drainage device includes a buffer tank, a residual discharge pipe, and a closed-drain auxiliary pump. The buffer tank is arranged above the ground. The residual discharge pipe is installed at the bottom of the buffer tank and extends into the bottom of the liquid collection bag. The closed-drain auxiliary pump is installed at the bottom of the buffer tank. The number of the residual discharge pipes is the same as the number of the liquid collection bags. The exhaust device introduces inert gas into the liquid collection device to press the liquid into the buffer tank through the residual discharge pipe.

[0012] The cleaning device extends from the top of the liquid collecting device.

[0013] Optionally, the liquid discharge device includes a closed-discharge main pump, one end of which extends into the liquid collection bag and the other end is connected to the crude oil processing system. The number of the closed-discharge main pumps is consistent with the number of the liquid collection bags.

[0014] Optionally, the closed-drain auxiliary pump is connected to the crude oil processing system and the drainage system respectively; when performing auxiliary drainage work, the closed-drain auxiliary pump is connected to the crude oil processing system; when performing cleaning work, the closed-drain auxiliary pump is connected to the drainage system.

[0015] Optionally, the auxiliary drainage device further includes an auxiliary air inlet pipe, an auxiliary exhaust pipe and an auxiliary water inlet pipe, the auxiliary air inlet pipe is used to introduce inert gas, the auxiliary exhaust pipe is connected to the flare system, and the closed drainage auxiliary pump is connected to the drainage system.

[0016] Optionally, the closed-discharge auxiliary pump is arranged above the ground, and the bottom elevation of the buffer tank is higher than the inlet of the closed-discharge auxiliary pump. When the liquid in the buffer tank reaches the bottom of the tank, the closed-discharge auxiliary pump does not generate cavitation.

[0017] Optionally, a liquid level gauge is provided on the side of the buffer tank.

[0018] Optionally, the cleaning device includes a water inlet pipe, which extends into the bottom of the liquid collecting device.

[0019] Optionally, the exhaust device includes an air inlet pipe and an exhaust pipe, the air inlet pipe is used to introduce inert gas, and the exhaust pipe is connected to the flare system.

[0020] Optionally, the inert gas is nitrogen, and the pressure is 0.5-0.7 MPa.

[0021] Optionally, an inspection hole for maintenance is provided on the top of the liquid collecting device.

[0022] In an embodiment of the present application, an auxiliary drainage device is added to the existing underground closed-drain system. The residual discharge pipe at the bottom of the auxiliary drainage device connects to the bottom of the liquid collection bag. Inert gas is introduced into the liquid collection device to pressurize the remaining liquid into a buffer tank, where it is then discharged to the crude oil processing system by the closed-drain auxiliary pump. The existing drainage device uses the closed-drain main pump to pump liquid. To prevent damage from cavitation to the pump, a minimum liquid level must be maintained in the liquid collection device. The auxiliary drainage device uses gas pressure to drain liquid. Liquid entering the buffer tank does not pass through the pump, so a minimum liquid level is not required in the liquid collection device to prevent pump cavitation. Because the auxiliary drainage device is entirely above ground, its height can be easily adjusted when entering the closed-drain auxiliary pump. Cavitation can be addressed by adjusting the closed-drain auxiliary pump's elevation. Furthermore, a flushing device is connected to the tank wall to rinse away material stuck to the tank wall and discharge it along with the water. Replacing the tank with inert gas is then performed. Since the residual liquid and material stuck to the tank wall are now cleaned, the replacement is completed quickly and qualified, allowing for quick start of the next maintenance work. In addition, when the drainage device fails, the auxiliary drainage device can replace the drainage device for a short period of time to maintain the operation of the closed drainage system and increase the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0024] Figure 1 It is a schematic diagram of a device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to an embodiment of the present application.

[0025] Figure numerals: 10: liquid collecting device; 11: liquid inlet; 111: first valve; 12: liquid collecting bag; 13: inspection hole; 20: exhaust device; 21: air inlet pipe; 211: second valve; 22: exhaust pipe; 221: third valve; 30: liquid discharge device; 31: closed discharge main pump; 311: fourth valve; 40: auxiliary liquid discharge device; 41: residual discharge pipe; 411: fifth valve; 42: buffer tank; 421: sixth valve; 43: closed discharge auxiliary pump; 431: seventh valve; 44: auxiliary air inlet pipe; 441: eighth valve; 45: auxiliary exhaust pipe; 451: ninth valve; 46: auxiliary water inlet pipe; 461: tenth valve; 47: liquid level gauge; 48: drain valve; 50: cleaning device; 51: water inlet pipe; 511: eleventh valve. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] It should be understood that references throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic associated with the embodiment is included in at least one embodiment of the present application. Therefore, the appearances of "in one embodiment" or "in an embodiment" throughout this specification do not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0028] Reference Figure 1 , showing a schematic diagram of a buried waste oil collection tank residual liquid removal and tank cleaning device provided in an embodiment of the present application;

[0029] like Figure 1 As shown, the buried waste oil collection tank residual liquid removal and tank cleaning device includes: a liquid collecting device 10, an exhaust device 20, a drain device 30, an auxiliary drain device 40 and a cleaning device 50; the liquid collecting device 10 is set below the ground, and the surface of the liquid collecting device 10 is provided with a liquid inlet 11 and a liquid collecting bag 12, the liquid collecting bag 12 is located at the bottom of the liquid collecting device 10 and protrudes away from the ground; the exhaust device 20 is connected to the top of the liquid collecting device 10; the drain device 30 extends from the top of the liquid collecting device 10 to the liquid collecting bag 12 In the middle; the auxiliary drainage device 40 includes a buffer tank 42, a residual discharge pipe 41 and a closed discharge auxiliary pump 43. The buffer tank 42 is arranged above the ground. The residual discharge pipe 41 is installed at the bottom of the buffer tank 42 and extends to the bottom of the liquid collecting bag 12. The closed discharge auxiliary pump 43 is installed at the bottom of the buffer tank 42. The number of residual discharge pipes 41 is consistent with the number of liquid collecting bags 12; the exhaust device 20 introduces inert gas into the liquid collecting device 10, and presses the liquid into the buffer tank 42 through the residual discharge pipe 41; the cleaning device 50 extends from the top of the liquid collecting device 10.

[0030] In the embodiment of the present application, the buried waste oil collection tank residual liquid removal and tank cleaning device includes: a liquid collection device 10, an exhaust device 20, a liquid discharge device 30, an auxiliary liquid discharge device 40, and a cleaning device 50. The device body is buried below the ground. The liquid collection device 10 is used to collect oil and gas discharged from various drainage points. The fluid entering the liquid collection device 10 undergoes gas-liquid separation within the device. The separated gas is sent to the flare for combustion by the exhaust device 20, while the liquid is recovered by the liquid discharge device 30 and returned to the crude oil processing system.

[0031] The liquid discharge device 30 usually adopts a single-screw pump. When pumping liquid, there is a problem of cavitation of the liquid inside the pump damaging the pump body. During the operation of the pump, the pressure inside the impeller is different, and there are low-pressure areas and high-pressure areas. The lower the pressure, the lower the vaporization temperature of the liquid. When the liquid pressure in the low-pressure area is lower than the vaporization pressure at the ambient temperature, bubbles are generated in the liquid. When the liquid containing a large number of bubbles moves forward through the high-pressure area in the impeller, the bubbles shrink rapidly under the action of pressure and even burst. The surrounding liquid rushes into the space originally occupied by the bubbles at an extremely high speed, generating a huge impact force, causing damage to the impeller and pump casing. In order for the pump to operate normally and avoid damage from cavitation, the pressure inside the pump should not be lower than the saturated vapor pressure of the liquid at the delivery temperature. Therefore, the pump has a minimum installation height related to the saturated vapor pressure of the liquid. In this embodiment, the liquid transported is dirty oil, whose main components are all low-boiling and volatile, and the corresponding minimum installation height is very low. Therefore, it is necessary to increase the liquid height in the liquid collecting device 10 to increase the water head. The liquid collecting device 10 has a minimum operating liquid level when discharging liquid through the liquid discharge device 30. The pump is started when the liquid level is high and stopped when the liquid level is low. The stop level is based on the pump not generating cavitation. When the liquid in the liquid collecting device 10 is lower than the minimum operating liquid level, the pump is at risk of being damaged by cavitation. This results in the liquid height in the liquid collecting device 10 always being higher than the bottom elevation of the device, and the residual liquid cannot be completely drained.

[0032] To maximize the capacity of the liquid collecting device 10, a liquid collecting bag 12 protruding from the surface is provided at the bottom of the liquid collecting device 10. The bottom elevation of the liquid collecting bag 12 is lower than the elevation of other parts of the bottom of the liquid collecting device 10. A liquid draining device 30 extends from the top of the liquid collecting device 10 into the liquid collecting bag 12 to minimize the liquid level required for pump shutdown. However, the lowest liquid level is always higher than the bottom elevation of the liquid collecting device 10, and the residual liquid in the liquid collecting device 10 cannot be completely drained by the liquid draining device 30 alone. Under normal circumstances, the residual liquid in the device will not affect normal operation. However, when the liquid collecting device 10 must be opened for maintenance, the residual liquid in the device will evaporate and produce a large amount of toxic and harmful gases, seriously affecting the maintenance work.

[0033] Furthermore, to drain the liquid from the device, the present embodiment adds an auxiliary drainage device 40 to the existing drainage device 30. The auxiliary drainage device 40 comprises a buffer tank 42, a residual drain pipe 41, and a closed-drain auxiliary pump 43. The buffer tank 42 is located above ground level. The residual drain pipe 41 is installed at the bottom of the buffer tank 42, with its upper end connected to the bottom nozzle of the buffer tank 42 and its lower end extending into the bottom of the liquid collection bag 12. The bottom elevation of the residual drain pipe 41 is the same as the bottom inner wall elevation of the liquid collection bag 12. A manual isolation valve is provided at the upper end near the tank bottom. The number of residual drain pipes 41 matches the number of liquid collection bags 12. The closed-drain auxiliary pump 43 is installed at the bottom of the buffer tank 42. A cleaning device 50 extends from the top of the liquid collection device 10. The auxiliary drainage device 40 does not pump liquid. Instead, it introduces inert gas into the liquid collection device 10 through the exhaust device 20. The gas pressure is used to pressurize the liquid into the buffer tank 42, where it is then pressurized by the closed-drain auxiliary pump 43 and discharged into the crude oil processing system. When the liquid enters the buffer tank 42, it does not pass through the pump and there is no minimum liquid level requirement. When it enters the closed-drain auxiliary pump 43, because the auxiliary drainage device 40 is entirely on the ground, height adjustment is very convenient, and the elevation of the closed-drain auxiliary pump 43 is lower than the elevation of the bottom of the buffer tank 42, there is no need to worry about cavitation problems.

[0034] Furthermore, in some embodiments, the auxiliary liquid draining device 40 may cooperate with the cleaning device 50 to clean the liquid collecting device 10 , and the waste water after cleaning is discharged from the liquid collecting device 10 through the auxiliary liquid draining device 40 .

[0035] The specific process of using the buried waste oil collection tank residual liquid removal and tank cleaning device in this embodiment to remove residual liquid and clean the tank body is as follows:

[0036] The liquid inlet 11 is closed, the liquid discharge device 30 is started, the liquid level in the liquid collecting device 10 is reduced to the minimum control liquid level, and the liquid discharge device 30 is stopped.

[0037] Open one residual discharge pipe 41 , partially open the exhaust device 20 in the liquid collecting device 10 and fill in inert gas, the pressure in the liquid collecting device 10 increases, and the residual liquid at the bottom is pressed into the buffer tank 42 through the residual discharge pipe 41 .

[0038] Start the closed discharge auxiliary pump 43, open the pump outlet door, and pump the residual liquid into the closed discharge main pump 31 outlet main pipe, and the residual liquid is recovered to the crude oil processing system.

[0039] By adjusting the opening of the outlet valve of the closed-drain auxiliary pump 43, the liquid level of the buffer tank 42 is controlled. When the pump outlet valve is fully closed and the liquid level still drops rapidly, it means that the dirty oil collection tank has been drained and the "liquid collecting bag 12" corresponding to the opened valve drain pipe 41 has also been emptied. Close the valve of the opened residual drain pipe 41, open the valve of the other residual drain pipe 41 to continue to drain the residual liquid in the corresponding liquid collecting bag 12. When all the residual liquid in the liquid collecting bags 12 and the buffer tank 42 is drained, stop the closed-drain auxiliary pump 43 and close the pump outlet valve.

[0040] The exhaust device 20 in the liquid collecting device 10 is closed, the cleaning device 50 in the liquid collecting device 10 is opened, and water is injected into the liquid collecting device 10 to flush the inner wall.

[0041] When the liquid level in the liquid collecting device 10 reaches the requirement, the cleaning device 50 is closed, the exhaust device 20 is partially opened, and the flushing water is discharged into the buffer tank 42. The above operation on the auxiliary draining device 40 is repeated to discharge the flushing water.

[0042] Carry out routine gas replacement operations and hand it over for maintenance after passing the test.

[0043] Furthermore, in some embodiments, when all of the liquid collecting devices 10 fail, the auxiliary liquid drain device 40 can temporarily replace the liquid collecting devices 10. The operation is as follows: close the liquid inlet 11, open one residual drain pipe 41, close the exhaust port set at the top of the liquid collecting device 10, partially open the air inlet, and fill with inert gas. The pressure in the liquid collecting device 10 increases, and the liquid in the device is pressed into the buffer tank 42 through the residual drain pipe 41. The closed-drain auxiliary pump 43 is started to drain and recycle the liquid until the liquid in the liquid collecting device 10 is emptied. The closed-drain auxiliary pump 43 is stopped, the liquid inlet 11 is opened, the exhaust pipe 22 is opened, and the liquid is resumed. When the liquid level reaches a high level, the above drainage operation is repeated. This cyclic operation can still realize the function of the waste oil collection tank.

[0044] The drainage device 30 uses a pumping method to drain the liquid, and the auxiliary drainage device 40 uses the pressure of high-pressure gas to press the liquid out of the liquid collecting device 10. Compared with pumping, the capacity of the buffer tank 42 is limited. When replacing the drainage device 30, the above operations need to be repeated many times. The drainage operation using gas pressure is complicated and inefficient. Therefore, it is only used as a short-term backup equipment when the drainage device 30 fails, and cannot completely replace the drainage device 30.

[0045] In an embodiment of the present application, an auxiliary drainage device 40 is added to the existing underground closed drainage system. The residual discharge pipe 41 at the bottom of the auxiliary drainage device 40 is connected to the bottom of the liquid collecting bag 12. Inert gas is introduced into the liquid collecting device 10 to press the remaining liquid into the buffer tank 42, and then the closed drainage auxiliary pump 43 is discharged to the crude oil processing system. The original drainage device 30 sucks liquid through the closed drainage main pump 31. To avoid cavitation damage to the pump, a minimum liquid level needs to be maintained in the liquid collecting device 10. The auxiliary drainage device 40 uses gas pressure to drain liquid. When the liquid enters the buffer tank 42, it does not pass through the pump. There is no need to set a minimum liquid level in the liquid collecting device 10 to avoid pump cavitation. When entering the closed drainage auxiliary pump 43, because the auxiliary drainage device 40 is entirely on the ground, the height adjustment is very convenient. The cavitation problem can be solved by adjusting the elevation of the closed drainage auxiliary pump 43. In addition, the cleaning device 50 is connected for flushing, which can wash away the materials adhering to the tank wall and discharge them with the water. The inert gas is then used for replacement. Since the residual liquid and materials adhering to the inner wall of the tank have been cleaned, the replacement is completed in a short time and qualified, and the next maintenance work can be started quickly. In addition, if the drainage device 30 fails, the auxiliary drainage device 40 can temporarily replace the drainage device 30 to maintain the operation of the closed drainage system and increase system reliability.

[0046] In addition, in some optional embodiments, the liquid discharge device 30 includes a closed-drain main pump 31, one end of which extends into the liquid collection bag 12, and the other end is connected to the crude oil processing system. The number of the closed-drain main pumps 31 is the same as the number of the liquid collection bags 12.

[0047] Generally, two sets of closed-discharge main pumps 31 are provided. The closed-discharge pumps of the buried closed-discharge system usually adopt single-screw pumps, one for use and one for standby operation. The start and stop of the pumps are controlled by a liquid level switch. The pumps are started when the liquid level is high and stopped when the liquid level is low. The stop level of the pump is determined based on the pump not generating cavitation.

[0048] In addition, in some optional embodiments, the closed-drain auxiliary pump 43 is connected to the crude oil processing system and the drainage system respectively; when performing auxiliary drainage work, the closed-drain auxiliary pump 43 is connected to the crude oil processing system; when performing cleaning work, the closed-drain auxiliary pump 43 is connected to the drainage system.

[0049] During auxiliary liquid drainage, one residual drain pipe 41 is opened, and the exhaust device 20 in the liquid collecting device 10 is partially opened to inject inert gas into the liquid collecting device 10. This increases the pressure in the liquid collecting device 10, and the residual liquid at the bottom is pressed into the buffer tank 42 through the residual drain pipe 41. The closed-drain auxiliary pump 43 is started, and the pump outlet door is opened. At this time, the closed-drain auxiliary pump 43 is connected to the outlet main pipe of the closed-drain main pump 31, the drainage system is closed, and the residual liquid is recovered to the crude oil processing system.

[0050] During cleaning, the exhaust device 20 in the liquid collection device 10 is closed, the cleaning device 50 in the liquid collection device 10 is opened, and water is injected into the liquid collection device 10 to flush the inner wall. When the liquid level in the liquid collection device 10 reaches the required level, the cleaning device 50 is closed, and the exhaust device 20 is partially opened to discharge the flushing water into the buffer tank 42. The closed-drain auxiliary pump 43 is started, and the pump outlet door is opened. At this time, the closed-drain auxiliary pump 43 is connected to the drainage system, and the pipeline leading to the outlet main pipe of the closed-drain main pump 31 is closed, allowing the wastewater after flushing to enter the drainage system.

[0051] In addition, in some optional embodiments, the cleaning device 50 includes a water inlet pipe 51 , which extends into the bottom of the liquid collecting device 10 .

[0052] The water inlet pipe 51 extends into the bottom of the liquid collecting device 10, and clean water is poured into the device from the bottom to prevent water from being directly injected from the top of the device, which causes the residual liquid at the bottom to splash onto the inner wall of the top of the liquid collecting device 10 under the impact of the clean water, causing inconvenience to the cleaning work.

[0053] In addition, in some optional embodiments, the auxiliary drainage device 40 also includes an auxiliary air inlet pipe 44, an auxiliary exhaust pipe 45 and an auxiliary water inlet pipe 46. The auxiliary air inlet pipe 44 is used to introduce inert gas, the auxiliary exhaust pipe 45 is connected to the flare system, and the closed drainage auxiliary pump 43 is connected to the drainage system.

[0054] When the oxygen content in the buffer tank 42 is too high, it is necessary to first introduce inert gas through the auxiliary air inlet pipe 44 to discharge the oxygen in the tank through the auxiliary exhaust pipe 45 .

[0055] The auxiliary water inlet pipe 46 is used to inject clean water into the buffer tank 42 to flush the buffer tank 42, and the flushing water is discharged through the closed-drain auxiliary pump 43 at the bottom.

[0056] In addition, in some optional embodiments, the closed-drain auxiliary pump 43 is arranged above the ground, and the bottom elevation of the buffer tank 42 is higher than the inlet of the closed-drain auxiliary pump 43. When the liquid in the buffer tank 42 reaches the bottom of the tank, the closed-drain auxiliary pump 43 does not produce cavitation.

[0057] Buffer tank 42 is located above ground, with its bottom opening connected to a closed-drain auxiliary pump 43. Liquid in buffer tank 42 flows into a pipeline system at the bottom, where it is pressurized and recovered by closed-drain auxiliary pump 43 to the crude oil processing system. Closed-drain auxiliary pump 43 can be a centrifugal or positive displacement pump, but its head must be no less than that of the closed-drain main pump 31 in the liquid displacement device 30.

[0058] In addition, in some optional embodiments, a liquid level gauge 47 is provided on the side of the buffer tank 42 .

[0059] When removing the residual liquid, the liquid level in the tank is observed by the liquid level gauge 47 on the side wall of the buffer tank 42. When the liquid level reaches above 50%, the closed discharge auxiliary pump 43 is started, the pump outlet door is opened, and the residual liquid is pumped into the closed discharge main pump 31 outlet main pipe, and the residual liquid is recovered to the crude oil processing system.

[0060] In addition, in some optional embodiments, the exhaust device 20 includes an air inlet pipe 21 and an exhaust pipe 22. The air inlet pipe 21 is used to introduce inert gas, and the exhaust pipe 22 is connected to the flare system.

[0061] The liquid collecting device 10 contains flammable, explosive, toxic and harmful gases and liquids. Before opening the device, the flammable, explosive, toxic and harmful gases must be replaced with inert gas. The inert gas is introduced through the air inlet pipe 21, and the flammable, explosive, toxic and harmful gases in the device are discharged into the torch through the exhaust pipe 22 and burned to prevent the personal safety of the maintenance personnel from being endangered when the tank is opened for maintenance.

[0062] An inspection hole is provided on the top of the liquid collecting device for maintenance. When the liquid collecting device needs to be opened for maintenance, the operation is performed through the inspection hole.

[0063] In addition, in some optional embodiments, the inert gas is nitrogen and the pressure is 0.5-0.7 MPa.

[0064] The inert gas is nitrogen commonly used in factories, with a pressure of 0.5-0.7 MPa. Accordingly, the liquid collecting device 10 and the buffer tank 42 are sealed tanks that can withstand pressure, and the design pressure of the liquid collecting device 10 and the buffer tank 42 is greater than the flare line pressure plus 0.1-0.2 MPa.

[0065] The materials processed by the residual liquid removal and tank cleaning device of the buried waste oil collection tank in the embodiment of the utility model are flammable, explosive, toxic and harmful, so the system needs to ensure complete sealing and slight positive pressure in the tank. The liquid collection device 10 and the buffer tank 42 are both sealed tanks that can withstand pressure.

[0066] In an embodiment of the present application, an auxiliary drainage device is added to the existing underground closed-drain system. The residual discharge pipe at the bottom of the auxiliary drainage device connects to the bottom of the liquid collection bag. Inert gas is introduced into the liquid collection device to pressurize the remaining liquid into a buffer tank, where it is then discharged to the crude oil processing system by the closed-drain auxiliary pump. The existing drainage device uses the closed-drain main pump to pump liquid. To prevent damage from cavitation to the pump, a minimum liquid level must be maintained in the liquid collection device. The auxiliary drainage device uses gas pressure to drain liquid. Liquid entering the buffer tank does not pass through the pump, so a minimum liquid level is not required in the liquid collection device to prevent pump cavitation. Because the auxiliary drainage device is entirely above ground, its height can be easily adjusted when entering the closed-drain auxiliary pump. Cavitation can be addressed by adjusting the closed-drain auxiliary pump's elevation. Furthermore, a flushing device is connected to the tank wall to rinse away material stuck to the tank wall and discharge it along with the water. Replacing the tank with inert gas is then performed. Since the residual liquid and material stuck to the tank wall are now cleaned, the replacement is completed quickly and qualified, allowing for quick start of the next maintenance work. In addition, when the drainage device fails, the auxiliary drainage device can replace the drainage device for a short period of time to maintain the operation of the closed drainage system and increase the reliability of the system.

[0067] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0068] Although alternative embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including alternative embodiments and all changes and modifications that fall within the scope of the present invention.

[0069] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity from another, and do not necessarily require or imply any actual relationship or order between these entities. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that an article or terminal device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such article or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the article or terminal device comprising the element.

[0070] The above is a detailed introduction to the technical solution provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. At the same time, for those skilled in the art, according to the principles and implementation methods of the present application, there may be changes in the specific implementation methods and application scope. In summary, the contents of this specification should not be understood as limiting the present application.

Claims

1. A device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body, characterized in that: include: A liquid collecting device (1), an exhaust device (2), a liquid draining device (3), an auxiliary liquid draining device (4) and a cleaning device (5); The liquid collecting device (1) is arranged below the ground, and a liquid inlet (11) and a liquid collecting bag (12) are provided on the surface of the liquid collecting device (1). The liquid collecting bag (12) is located at the bottom of the liquid collecting device (1) and protrudes in a direction away from the ground. The exhaust device (2) is in communication with the top of the liquid collecting device (1); The liquid discharge device (3) extends from the top of the liquid collecting device (1) into the liquid collecting bag (12); The auxiliary liquid discharge device (4) comprises a buffer tank (42), a residual discharge pipe (41) and a closed discharge auxiliary pump (43); the buffer tank (42) is arranged above the ground; the residual discharge pipe (41) is installed at the bottom of the buffer tank (42) and extends to the bottom of the liquid collecting bag (12); the closed discharge auxiliary pump (43) is installed at the bottom of the buffer tank (42); the number of the residual discharge pipes (41) is the same as the number of the liquid collecting bags (12); the exhaust device (2) introduces inert gas into the liquid collecting device (1) to press the liquid into the buffer tank (42) through the residual discharge pipe (41); The cleaning device (5) extends from the top of the liquid collecting device (1).

2. The buried waste oil collection tank residual liquid removal and tank cleaning device according to claim 1 is characterized in that: The liquid discharge device (3) comprises a closed discharge main pump (31), one end of which extends into the liquid collection bag (12) and the other end is connected to the crude oil processing system. The number of the closed discharge main pumps (31) is the same as the number of the liquid collection bags (12).

3. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1 is characterized in that: The closed-discharge auxiliary pump (43) is connected to the crude oil processing system and the drainage system respectively; when performing auxiliary drainage work, the closed-discharge auxiliary pump (43) is connected to the crude oil processing system; when performing cleaning work, the closed-discharge auxiliary pump (43) is connected to the drainage system.

4. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1 is characterized in that: The auxiliary liquid discharge device (4) further comprises an auxiliary air inlet pipe (44), an auxiliary exhaust pipe (45) and an auxiliary water inlet pipe (46); the auxiliary air inlet pipe (44) is used for introducing inert gas, and the auxiliary exhaust pipe (45) is connected to a flare system.

5. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1 is characterized in that: The closed-discharge auxiliary pump (43) is arranged above the ground, and the bottom elevation of the buffer tank (42) is higher than the inlet of the closed-discharge auxiliary pump (43).

6. The buried waste oil collection tank residual liquid removal and tank cleaning device according to claim 1 is characterized in that: A liquid level gauge (47) is provided on the side of the buffer tank (42).

7. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1 is characterized in that: The cleaning device (5) comprises a water inlet pipe (51), and the water inlet pipe (51) extends into the bottom of the liquid collecting device (1).

8. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 4 is characterized in that: The exhaust device (2) comprises an air inlet pipe (21) and an exhaust pipe (22), wherein the air inlet pipe (21) is used to introduce inert gas, and the exhaust pipe (22) is connected to the flare system.

9. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1, characterized in that: The inert gas is nitrogen, and the pressure is 0.5-0.7 MPa.

10. The device for removing residual liquid from an underground waste oil collection tank and cleaning the tank body according to claim 1, characterized in that: A maintenance hole (13) for maintenance is provided on the top of the liquid collecting device (1).

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