Main Liquid Container Leakage Liquid Level Detection and Control System in Three-Wall Atmospheric-Pressure Full-Volume Storage Tank

Abstract

The present invention relates to the field of oil and gas storage and transportation, and particularly to a leakage liquid level detection and control system for a main liquid container in a three-wall atmospheric full-capacity storage tank. The leakage liquid level detection and control system is installed in the three-wall atmospheric full-capacity storage tank. A pump well extending into the main liquid container is provided on the evaporation gas container, and a submersible pump is installed in the pump well. An outer perforated ring pipe and an inner perforated ring pipe are respectively installed in the first interlayer and the main liquid container, and a leakage liquid level detection device is provided in the first interlayer. Through the leakage liquid level detection device and an emergency cut-off valve provided on the first nitrogen pipe, the leakage liquid level detection device is communicatively connected to the submersible pump and the emergency cut-off valve through a controller. The leakage liquid level detection device monitors whether there is liquid leakage in the first interlayer. After liquid leakage occurs, during the liquid discharge process, the leakage liquid level detection device can monitor that the liquid level height of the main liquid container is not lower than the liquid level height of the leakage in the first interlayer, effectively preventing the instability of the main liquid container.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas storage and transportation, and particularly to a leakage liquid level detection and control system for a main liquid container in a three-wall atmospheric-pressure full-capacity storage tank. Background Art

[0002] At present, the three-wall metal full-capacity storage tanks operating on the market have obvious advantages in terms of high safety and are commonly used for storing LNG (liquefied natural gas), liquid ammonia, and other liquids with boiling points between 0°C and 165°C. There is a problem with existing three-wall metal full-capacity storage tanks that the main liquid container may leak. Since the gas phases of the main liquid container and the secondary liquid container are connected, the gas temperature of the secondary liquid container, as well as the temperatures of the cylinder wall and the bottom plate, are all similar to those of the main liquid container, with very small temperature differences or even no temperature differences. It is very difficult to determine whether the main liquid container is leaking by measuring the temperature difference between the cylinder walls of the main liquid container and the secondary liquid container. When the liquid in the main liquid container leaks into the first interlayer between the main liquid container and the secondary liquid container, it is inconvenient to drain the liquid in the first interlayer. During the process of emptying the storage tank, liquid residues are likely to occur in the first interlayer and the main liquid container, making it inconvenient to empty the storage tank.

[0003] In order to facilitate the detection of whether liquid has leaked into the first interlayer, the existing method is to install a differential pressure liquid level gauge in the first interlayer. However, when the existing differential pressure liquid level gauge takes pressure inside the liquid storage tank, the gas-phase guiding head and the liquid-phase guiding head need to be installed at the upper and lower parts of the liquid storage tank. After installation, when starting to take pressure, since the liquid at the liquid-phase guiding head is in an unstable state, it is easy to cause a large difference between the pressure-taking value and the correct value. In order to improve the accuracy of the pressure-taking result, it is necessary to stabilize the liquid at the liquid-phase guiding head so that it enters the liquid-phase guiding head in a stable state. Summary of the Invention

[0004] The technical problem to be solved by the present invention is a leakage liquid level detection and control system that can timely and conveniently determine whether the main liquid container leaks, can accurately measure the height of the liquid level in the first interlayer, can conveniently drain the liquid in the first interlayer and the main liquid container completely, and is convenient for tank cleaning.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] Leakage liquid level detection and control system for the main liquid container in a three-wall atmospheric storage tank, installed inside the three-wall atmospheric storage tank. The three-wall atmospheric storage tank includes an evaporation gas container, in which a secondary liquid container is installed, and in the secondary liquid container, a main liquid container is installed. A first interlayer is provided between the main liquid container and the secondary liquid container, and the first interlayer is in gas communication with the main liquid container. A second interlayer is provided between the evaporation gas container and the secondary liquid container, and heat insulation materials are provided in the second interlayer. A vent hole is also provided in the second interlayer. The upper parts of the main liquid container and the secondary liquid container are open. The upper part of the first interlayer is open and is in gas communication with the evaporation gas container and the main liquid container. A plurality of pump wells extending into the main liquid container are provided on the evaporation gas container, and submersible pumps are installed in each pump well. An outer porous ring pipe and an inner porous ring pipe are respectively installed in the first interlayer and the main liquid container. A leakage liquid level detection device is provided in the first interlayer. The nitrogen main pipeline is connected to the inner porous ring pipe through a second nitrogen pipe, and the nitrogen main pipeline is connected to the outer porous ring pipe through a first nitrogen pipe. An emergency cut-off valve is installed on the first nitrogen pipe. The leakage liquid level detection device is in communication connection with a controller, and the controller is respectively in communication connection with the submersible pump and the emergency cut-off valve.

[0007] Specifically, the leakage liquid level detection device includes a differential pressure liquid level gauge body and a stable box fixed at the bottom of the first interlayer. A first connecting pipe is provided at the lower end of the stable box, and the first connecting pipe is communicated with the differential pressure liquid level gauge body. The differential pressure liquid level gauge body is communicated with the upper end of the first interlayer through a second connecting pipe. A liquid inlet pipe communicated with it is provided at the upper end of the stable box. An inclined plate is fixed in the stable box, and buffer nets are installed at the four corners of the inclined plate. Round holes are provided on the inclined plate, and a buffer device is rotatably arranged in the round holes. The buffer device includes a rotating plate, the rotating plate is in the same plane as the inclined plate, and a plurality of through holes are circumferentially and evenly arranged on the rotating plate. An elastic liquid bag corresponding to the through holes is provided below the rotating plate, and the upper end of the elastic liquid bag is communicated with the through hole above it. A counterweight block is fixed at the lower end of the elastic liquid bag. The liquid outlet end of the liquid inlet pipe is located directly above a certain point on the movement track of the through hole and is staggered with the lowest position of the movement track of the through hole. The liquid discharged from the liquid outlet end of the liquid inlet pipe is allowed to drive the buffer device to rotate. During the rotation of the buffer device, the liquid is allowed to intermittently enter the elastic liquid bag and expand it to buffer the liquid. After the elastic liquid bag is staggered with the liquid inlet pipe, the elastic liquid bag is allowed to squeeze out the liquid inside it.

[0008] Specifically, a gas phase guiding head is installed on the second connecting pipe, and a liquid phase guiding head is installed on the liquid inlet pipe.

[0009] Specifically, a shaft rod concentric with it is rotatably connected to the upper end of the rotating plate, and the shaft rod is fixedly connected to the upper end of the stable box.

[0010] Specifically, a minimum gap allowing the rotating plate to rotate is provided between the outer edge of the rotating plate and the hole wall of the round hole.

[0011] Specifically, mounting ears are provided on the stabilizing box. The stabilizing box is fixedly installed inside the lower part of the first interlayer through the mounting ears. The differential pressure liquid level gauge body is fixed with a mounting plate, and the differential pressure liquid level gauge body is fixed inside the first interlayer through the mounting plate.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] 1. The present invention provides a leakage liquid level detection device in the first interlayer between the main liquid container and the secondary liquid container, an emergency cut-off valve is provided on the first nitrogen pipe, and the leakage liquid level detection device is communicatively connected to the submerged pump and the emergency cut-off valve through a controller. The leakage liquid level detection device can monitor in real time and effectively whether there is liquid leakage in the first interlayer. When liquid leakage occurs in the first interlayer, the leakage liquid level detection device sends control signals to the submerged pump and the emergency cut-off valve through the controller. The submerged pump starts to pump out the liquid in the main liquid container. At the same time, the emergency cut-off valve opens, and nitrogen enters the outer perforated ring pipe and sprays out, causing the liquid in the first interlayer to vaporize and be discharged from the first interlayer. After liquid leakage occurs, during the liquid discharge process, the leakage liquid level detection device monitors the liquid level height inside the first interlayer leakage to ensure that the liquid level height of the main liquid container is not lower than the liquid level height of the first interlayer leakage, effectively preventing instability caused by the pressure difference between the outer wall and the inner wall of the main liquid container, and providing a strong guarantee for the safe operation of the storage tank.

[0014] 2. Introducing nitrogen into the inner perforated ring pipe and the outer perforated ring pipe can conveniently vaporize and discharge the remaining liquid in the first interlayer and the main liquid container, facilitating the tank cleaning operation.

[0015] 3. By providing a stabilizing box on the leakage liquid level detection device, it can buffer the low-temperature liquid introduced into the differential pressure liquid level gauge body, avoid too large a gap between the pressure-taking value and the correct value, and improve the accuracy of the pressure-taking result. Description of the Drawings

[0016] Figure 1 is a schematic structural diagram of the present invention.

[0017] Figure 2 is a three-dimensional view of the leakage liquid level detection device.

[0018] Figure 3 is a schematic internal structure diagram of the stabilizing box.

[0019] Figure 4 is Figure 3 an enlarged view of area A in

[0020] Figure 5 is a schematic structural diagram of the buffer device.

[0021] The part names in the drawings are:

[0022] 1. Stabilizing box; 2. First connecting pipe; 3. Differential pressure liquid level gauge body; 4. Mounting plate; 5. Second connecting pipe; 6. Gas phase guiding head; 7. Liquid phase guiding head; 8. Liquid inlet pipe; 9. Inclined plate; 10. Buffer net; 11. Rotating plate; 12. Shaft rod; 13. Through hole; 14. Elastic liquid sac; 15. Counterweight; 16. Mounting ear; 17. Main liquid container; 18. Secondary liquid container; 19. Evaporation gas container; 20. Submersible pump; 21. Pump well; 22. Nitrogen main pipeline; 23. First nitrogen pipe; 24. Second nitrogen pipe; 25. Outer porous ring pipe; 26. Inner porous ring pipe; 27. Emergency cut-off valve. Detailed implementation mode

[0023] As Figure 1 shown, the three-wall atmospheric pressure full containment storage tank includes an evaporation gas container 19, in which a secondary liquid container 18 is installed, and a main liquid container 17 is installed in the secondary liquid container 18. A first interlayer is arranged between the main liquid container 17 and the secondary liquid container 18, and the first interlayer is gas-connected to the main liquid container. In the use state, the first interlayer is a gas space filled with natural gas, without any other heat insulation materials. The main liquid container 17 and the secondary liquid container 18 are open at the top, and the first interlayer is open at the top and is gas-connected to the evaporation gas container 19 and the main liquid container 17.

[0024] A second interlayer is arranged between the evaporation gas container and the secondary liquid container, and the thickness of the second interlayer is not less than 1 meter. Heat insulation materials are arranged in the second interlayer, and ventilation holes are also arranged in the second interlayer. The heat insulation materials include an elastic blanket arranged on the surface of the secondary liquid container cylinder body and an expanded perlite filling layer between the elastic blanket and the evaporation gas container 19. Corresponding heat insulation measures are adopted between the secondary liquid container 18 and the evaporation gas container 19, and corresponding ventilation holes are arranged, so that heat preservation and gas phase connection can be ensured between the secondary liquid container and the evaporation gas container.

[0025] The leakage liquid level detection and control system for the main liquid container in the three-wall atmospheric pressure full containment storage tank is installed in the three-wall atmospheric pressure full containment storage tank.

[0026] A plurality of pump wells 21 extending into the main liquid container 17 are arranged on the evaporation gas container 19, and submersible pumps 20 are installed in the pump wells 21. An outer porous ring pipe 25 and an inner porous ring pipe 26 are respectively installed in the first interlayer and the main liquid container 17. The outer porous ring pipe 25 is installed at the lower end in the first interlayer. The inner porous ring pipe 26 is installed at the lower end in the main liquid container 17. A leakage liquid level detection device is arranged in the first interlayer. The nitrogen main pipeline 22 is communicated with the inner porous ring pipe 26 through the second nitrogen pipe 24, and the nitrogen main pipeline 22 is communicated with the outer porous ring pipe 25 through the first nitrogen pipe 23. An emergency cut-off valve 27 is installed on the first nitrogen pipe 23. The leakage liquid level detection device is in communication connection with the controller, and the controller is respectively in communication connection with the submersible pump 20 and the emergency cut-off valve 27.

[0027] The leakage level detection device can monitor whether the first interlayer leaks in real time and effectively. When the first interlayer leaks, the leakage level detection device sends a start signal to the submersible pump 20 and the emergency shut-off valve 27, and the submersible pump 20 starts to pump out the liquid in the main liquid container 17. At the same time, the emergency shut-off valve 27 opens, and the nitrogen in the nitrogen main pipeline 22 enters the outer porous annular tube 25 through the first nitrogen pipe 23 and then sprays out and vaporizes the liquid in the first interlayer and then discharges it from the first interlayer. The discharge of the leaked liquid from the first interlayer can effectively prevent the main liquid container 17 from becoming unstable, providing a strong guarantee for the safe operation of the storage tank.

[0028] For example, the liquid level alarm value transmitted by the leakage liquid level detection device is set to 60mm. When the liquid level of the first interlayer exceeds 60mm, an alarm is sounded. The liquid level upper limit value transmitted by the leakage liquid level detection device is set to 100mm. When the liquid level of the first interlayer exceeds 100mm, the emergency shut-off valve 27 is opened in a chain, and the submersible pump 20 is opened in a chain to pump liquid. The premise for opening the submersible pump 20 is that there is a tank truck at the filling end. If there is no tank truck, the liquid pumped out by the submersible pump 20 is pumped back.

[0029] When the tank needs to be emptied, the valves on the second nitrogen pipe 24 and the first nitrogen pipe 23 are opened, and nitrogen is introduced into the inner porous annular tube 26 and the outer porous annular tube 25, so that the residual liquid in the main liquid container 17 and the first interlayer can be vaporized and discharged, thereby facilitating the tank cleaning operation.

[0030] During the drainage process of the secondary liquid container 18, it is imperative to ensure that the liquid level of the main liquid container 17 is not lower than the liquid level of the leakage of the first interlayer. In practical applications, since the cavitation margin of the submersible pump 20 is generally not less than 450mm, if the submersible pump 20 is not stopped, the maximum liquid level is 450mm, and the submersible pump 20 cannot be started again. The liquid level of the first interlayer is monitored in real time by the leakage liquid level detection device. The liquid level of the first interlayer between the main liquid container 17 and the secondary liquid container 18 is controlled at a liquid level lower than 450mm, so there is no possibility of instability of the main liquid container 17.

[0031] like Figures 2 - 5 As shown, the leakage liquid level detection device includes a differential pressure level gauge body 3 and a stabilizing box 1 fixed at the bottom of the first interlayer. The stabilizing box 1 is provided with a mounting ear 16, and the stabilizing box 1 is fixedly mounted at the lower end of the first interlayer through the mounting ear 16. The differential pressure level gauge body 3 is fixed with a mounting plate 4, and the differential pressure level gauge body 3 is fixedly connected to the fixing frame through the mounting plate 4. The differential pressure level gauge body 3 can be set in the storage tank or outside the storage tank according to actual needs.

[0032] At the lower end of the stabilizing tank 1, there is a first connecting pipe 2, and the first connecting pipe 2 is communicated with the differential pressure liquid level gauge body 3. The differential pressure liquid level gauge body 3 is communicated with the upper end part of the first interlayer through a second connecting pipe 5. A gas phase guiding head 6 is installed on the second connecting pipe 5. At the upper end of the stabilizing tank 1, there is a liquid inlet pipe 8 communicated with it, and a liquid phase guiding head 7 is installed on the liquid inlet pipe 8. An inclined plate 9 is fixed in the stabilizing tank 1, and buffer nets 10 are installed at the four corners of the inclined plate 9. Round holes are formed in the inclined plate 9, and a buffer device is rotatably arranged in the round holes.

[0033] The buffer device includes a rotating plate 11, and there is a minimum gap allowing the rotating plate 11 to rotate between the outer edge of the rotating plate 11 and the hole wall of the round hole. The upper end of the rotating plate 11 is rotatably connected with a concentric shaft rod 12, and the shaft rod 12 is fixedly connected with the upper end of the stabilizing tank 1. The rotating plate 11 and the inclined plate 9 are in the same plane. A plurality of through holes 13 are evenly distributed in a circular pattern on the rotating plate 11. Below the rotating plate 11, there is an elastic liquid bag 14 corresponding to the through holes 13, and the upper end of the elastic liquid bag 14 is communicated with the through hole 13 above it. A counterweight 15 is fixed at the lower end of the elastic liquid bag 14.

[0034] The liquid outlet end of the liquid inlet pipe 8 is arranged corresponding to the position of the through hole 13. The liquid inlet pipe 8 is above the movement track of the through hole 13. And during the rotation of the through hole 13, at a certain moment, it is opposite to the liquid outlet end of the liquid inlet pipe 8. During the rotation of the through hole 13, a movement track is formed, and the liquid outlet end of the liquid inlet pipe 8 is not opposite to the lowest position of the movement track of the through hole 13. The liquid outlet end of the liquid inlet pipe 8 is directly above a certain point of the movement track of the through hole 13 and is staggered with the lowest position of the movement track of the through hole 13.

[0035] The liquid discharged from the liquid outlet end of the outlet pipe allows the buffer device to rotate. During the rotation of the buffer device, the liquid allows to intermittently enter the elastic liquid bag 14 and expand it, thereby buffering the liquid. After the elastic liquid bag 14 is staggered with the liquid inlet pipe 8, the elastic liquid bag 14 allows the liquid inside it to be extruded.

[0036] When detecting the liquid level of the liquid in the first interlayer, liquid pressure is taken through the liquid-phase guide head 7, and the liquid enters the stable box 1 through the liquid inlet pipe 8. The liquid entering the stable box 1 from the liquid inlet pipe 8 impacts the rotating plate 11 and first enters the corresponding elastic liquid bag 14 through the inlet through hole 13 adjacent to the liquid inlet pipe 8. Under the combined action of the force formed by the liquid shooting at the rotating plate 11 and passing through the through hole 13 on the elastic liquid bag 14 and the gravity of the liquid in the elastic liquid bag 14, the rotating plate 11 rotates. During the rotation of the rotating plate 11, the liquid entering each through hole 13 quickly enters the elastic liquid bag 14 below it, causing the elastic liquid bag 14 to expand and increase in weight. The elastic liquid bag 14 buffers the liquid discharged from the liquid inlet pipe 8 through expansion. When the expanded elastic liquid bag 14 intersects with the liquid inlet pipe 8, under the elastic force of the elastic liquid bag 14, the liquid in the elastic liquid bag 14 is squeezed out. The liquid discharged from the liquid inlet pipe 8 is intermittently injected into the elastic liquid bag 14, and the expansion of the elastic liquid bag 14 is used to buffer the liquid discharged from the liquid inlet pipe 8, thereby making the liquid tend to be stable.

[0037] The liquid discharged from the elastic liquid bag 14 falls into the stable box 1 below the inclined plate 9 through the buffer net 10. By setting the buffer net 10, the liquid can be buffered again, which can avoid the large gap between the pressure-taking value and the correct value and improve the accuracy of the pressure-taking result.

[0038] Under the gravity of the counterweight 15, the elastic liquid bag 14 is always in a vertical state. During the rotation of the rotating plate 11 with multiple elastic liquid bags 14, the liquid in the stable box 1 below the inclined plate 9 can be stirred, further changing the irregularly flowing liquid into a regularly flowing liquid and reducing its unstable factors. Then the stable liquid enters the differential pressure liquid level gauge body 3 through the first connecting pipe 2, and the gas enters the differential pressure liquid level gauge body 3 through the second connecting pipe 5, realizing the pressure-taking operations of the gas phase and the liquid phase.

[0039] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A leakage liquid level detection and control system for a main liquid container in a three-wall atmospheric storage tank, which is installed in the three-wall atmospheric storage tank. The three-wall atmospheric storage tank includes an evaporation gas container (19), in which a secondary liquid container (18) is installed, and in the secondary liquid container (18), a main liquid container (17) is installed. A first interlayer is provided between the main liquid container (17) and the secondary liquid container (18), and the first interlayer is gas-connected to the main liquid container. A second interlayer is provided between the evaporation gas container and the secondary liquid container, and heat insulation material is provided in the second interlayer. A ventilation hole is also provided in the second interlayer. The upper parts of the main liquid container (17) and the secondary liquid container (18) are open, and the upper part of the first interlayer is open and gas-connected to the evaporation gas container (19) and the main liquid container (17). It is characterized in that, A plurality of pump wells (21) extending into the main liquid container (17) are provided on the evaporation gas container (19), and submersible pumps (20) are installed in each of the pump wells (21). An outer porous ring pipe (25) and an inner porous ring pipe (26) are installed in the first interlayer and the main liquid container (17) respectively. A leakage liquid level detection device is provided in the first interlayer. The nitrogen main pipeline (22) is connected to the inner porous ring pipe (26) through the second nitrogen pipeline (24), and the nitrogen main pipeline (22) is connected to the outer porous ring pipe (25) through the first nitrogen pipeline (23). An emergency cut-off valve (27) is installed on the first nitrogen pipeline (23). The leakage liquid level detection device is communicatively connected to the controller, and the controller is communicatively connected to the submersible pump (20) and the emergency cut-off valve (27) respectively; The leakage liquid level detection device includes a differential pressure liquid level gauge body (3) and a stable box (1) fixed at the bottom of the first interlayer. A first connecting pipe (2) is provided at the lower end of the stable box (1), and the first connecting pipe (2) is connected to the differential pressure liquid level gauge body (3). The differential pressure liquid level gauge body (3) is connected to the upper end of the first interlayer through a second connecting pipe (5), An inlet pipe (8) communicating with the stable box (1) is provided at the upper end of the stable box (1). An inclined plate (9) is fixed in the stable box (1). Buffer nets (10) are installed at the four corners of the inclined plate (9). Round holes are provided on the inclined plate (9), and a buffer device is rotatably arranged in the round holes. The buffer device includes a rotating plate (11). The rotating plate (11) is in the same plane as the inclined plate (9). A plurality of through holes (13) are circumferentially and evenly arranged on the rotating plate (11). An elastic liquid bag (14) corresponding to the through holes (13) is arranged below the rotating plate (11). The upper end of the elastic liquid bag (14) is communicated with the through hole (13) above it. A counterweight (15) is fixed to the lower end of the elastic liquid bag (14). The liquid outlet end of the liquid inlet pipe (8) is directly above a certain point on the movement track of the through hole (13) and is staggered with the lowest position of the movement track of the through hole (13). The liquid discharged from the liquid outlet end of the liquid inlet pipe (8) allows the buffer device to rotate. During the rotation of the buffer device, the liquid allows to intermittently enter the elastic liquid bag (14) and expand it, thereby buffering the liquid. After the elastic liquid bag (14) is staggered with the liquid inlet pipe (8), the elastic liquid bag (14) allows to squeeze out the liquid inside it.

2. The leakage liquid level detection and control system for the main liquid container in the three-wall atmospheric storage tank according to claim 1, wherein A gas phase guiding head (6) is installed on the second connecting pipe (5), and a liquid phase guiding head (7) is installed on the liquid inlet pipe (8).

3. The main liquid container leakage liquid level detection and control system in the three-wall atmospheric pressure full-capacity storage tank according to claim 1, wherein A shaft rod (12) concentric with the rotating plate (11) is rotatably connected to the upper end of the rotating plate (11), and the shaft rod (12) is fixedly connected to the upper end of the stable box (1).

4. The main liquid container leakage liquid level detection and control system in the three-wall atmospheric storage tank according to claim 1, characterized in that, A minimum clearance allowing the rotating plate (11) to rotate is provided between the outer edge of the rotating plate (11) and the hole wall of the circular hole.

5. The main liquid container leakage liquid level detection and control system in the three-wall atmospheric storage tank according to claim 1, characterized in that, Mounting ears (16) are provided on the stable box (1). The stable box (1) is fixedly installed inside the lower part of the first interlayer through the mounting ears (16). A mounting plate (4) is fixed to the differential pressure liquid level gauge body (3), and the differential pressure liquid level gauge body (3) is fixed inside the first interlayer through the mounting plate (4).

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