Internal floating roof storage tank

Abstract

The utility model discloses an internal floating roof storage tank, which is used for storing organic liquid and at least comprises a tank body, a floating disc capable of moving up and down is arranged in the tank body, a liquid phase space is arranged below the floating disc, and a gas phase space is arranged above the floating disc; the air bag is in an air bellow type folding shape and is fixed on the upper surface of the floating disc; the upper end of the air bag is necked and is provided with a vent hole; the interior of the air bag is a nitrogen space, and the gas-phase space outside the air bag is an oil-gas space. According to the pull rope balance weight assembly, a plurality of pull ropes which are evenly arranged at intervals and arranged outside the air bag in a wrapping mode are arranged in the tank body, the bottom ends of the pull ropes are fixed to the upper surface of the floating disc in the circumferential direction of the bottom of the air bag, the top ends of the pull ropes converge and extend out of the tank body, and balance weight pieces are arranged at the free ends, extending out of the tank body, of the pull ropes. According to the utility model, the change of the liquid level in the tank can be intuitively observed outside the tank body through the arrangement of the bellows-type folding columnar air bag and the pull rope counterweight, so that the change of the pressure at the top of the tank can be quickly responded.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection and energy conservation, and particularly relates to an internal floating roof storage tank for energy conservation and emission reduction. Background Art

[0002] Organic liquids such as oil products and organic chemicals are generally stored in storage tanks. When the organic liquids in the tank evaporate, volatile organic compounds (VOCs) are generated and enter the gas space above the storage tank. These VOC-containing gases will be discharged into the atmosphere due to the "inhalation" and "exhaust" of the storage tank, causing environmental pollution and resource loss. Usually, for storage tanks of oil products and organic chemicals with relatively high vapor pressure, a floating disk needs to be installed inside the tank, or an external floating roof storage tank or an internal floating roof storage tank needs to be built to control the emission of VOCs. However, by installing a floating disk, the concentration of waste gas can only be reduced to a certain extent, far from meeting the emission standard requirements. In addition to adding a floating disk, in order to prevent the storage tank from introducing too much oxygen during inhalation, which may cause potential safety hazards and oxidation of oil products, a nitrogen seal is generally set in the storage tank. Nitrogen is supplemented into the tank body when the storage tank inhales to isolate the air. The consumption of nitrogen greatly increases the cost during the maintenance and use of the storage tank. In addition, the external floating roof or internal floating roof tank needs to be subjected to closed gas extraction treatment, and the extracted gas needs to be subjected to VOC recovery or high-temperature oxidation treatment to achieve near-zero emission of waste gas.

[0003] Chinese Patent Application CN114435780A discloses an energy-saving and emission-reducing storage tank. The storage tank includes a shell, an internal airbag located inside the shell, an airbag support, and a U-shaped oil and gas conduit; the internal airbag includes an outer airbag and an inner airbag. The outer airbag and the inner airbag share an airbag top, and a ventilation hole is provided on the airbag top; the outer airbag has no airbag bottom, and the outer airbag is fixed on the airbag support and can move up and down along the support; the lower part of the outer airbag extends below the upper surface of the oil product; one pipe orifice of the U-shaped oil and gas conduit is located in the space surrounded by the outer airbag and the shell, and the other pipe orifice is located in the space surrounded by the outer airbag, the inner airbag, and the oil product. This solution realizes the volume pressure balance and volume automatic adjustment of the oil and gas gas phase space in the inner and outer airbags of the storage tank, and no volatile oil and gas is discharged from the storage tank to the atmosphere, thereby achieving zero emission of the waste gas of the storage tank.

[0004] This type of solution uses the method of pressure balance in the oil and gas gas phase space in the inner and outer airbags of the storage tank to recover and treat the escaped oil and gas. However, in the existing solutions, the change of the liquid level inside the tank cannot be visually observed outside the tank body, and the change of the tank top pressure cannot be quickly responded to.

[0005] Therefore, there is an urgent need for an internal floating roof storage tank for energy conservation and emission reduction, which can visually observe the change of the liquid level inside the tank outside the tank body, and then quickly respond to the change of the tank top pressure.

[0006] The information disclosed in this background section is only intended to enhance the overall understanding of the background of the present utility model and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Utility Model

[0007] The purpose of the present utility model is to provide an internal floating roof storage tank. Through the setting of a "bellows-type" folded columnar airbag and a rope weight, the change of the liquid level in the tank can be visually observed outside the tank body, and then the change of the tank top pressure can be quickly responded to.

[0008] To achieve the above purpose, the present utility model provides an internal floating roof storage tank for storing organic liquids, which at least includes: a tank body, inside which there is a floating disc that can move up and down. Below the floating disc is a liquid phase space, and above the floating disc is a gas phase space; an airbag, which is in a bellows-type folded shape and is fixed on the upper surface of the floating disc; the upper end of the airbag is provided with a reduced opening and has a ventilation hole; the inside of the airbag is a nitrogen space, and the gas phase space outside the airbag is an oil and gas space; a rope weight assembly, which is provided with a plurality of ropes arranged at equal intervals in the tank body and surrounding the outside of the airbag. The bottom ends of the plurality of ropes are circumferentially fixed on the upper surface of the floating disc along the bottom of the airbag, and the top ends of the plurality of ropes converge and extend outside the tank body. A weight is provided at the free end of the rope extending outside the tank body.

[0009] Further, in the above technical solution, when the airbag is filled with nitrogen and in a fully unfolded state, the volume ratio of the nitrogen space inside the airbag to the oil and gas space outside the airbag is preferably 9:1.

[0010] Further, in the above technical solution, the outer wall surface of the airbag can be serrated to form a bellows-type airbag that can be vertically folded.

[0011] Further, in the above technical solution, limit rings can be provided at the creases of different heights on the outer wall surface of the airbag, and a plurality of ropes can pass through the limit rings arranged in corresponding multiple columns.

[0012] Further, in the above technical solution, after the plurality of ropes converge at the top of the airbag in the tank, they can extend outside the tank through a single rope and are connected to the weight through a fixed pulley.

[0013] Further, in the above technical solution, the nitrogen space and the oil and gas space can be selectively communicated with independently controlled nitrogen supply pipelines.

[0014] Further, in the above technical solution, the nitrogen space can also be selectively communicated with a low-concentration waste gas discharge pipeline. The oil and gas space can also be selectively communicated with a high-concentration oil and gas discharge pipeline.

[0015] Further, in the above technical solution, a pressure gauge for monitoring the oil and gas pressure can be provided at the top of the tank body.

[0016] Furthermore, in the above technical solution, flow meters and valves can be correspondingly provided on the nitrogen gas supply pipeline, the low-concentration waste gas discharge pipeline, and the high-concentration oil and gas discharge pipeline.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] 1) By setting the "bellows-type" folded columnar airbag and the pull rope counterweight assembly in the utility model, multiple pull ropes are set outside the airbag, forming an effect similar to a "net bag". The pull ropes extend outside the tank body and a counterweight is set at the free end, so that the change of the liquid level in the tank can be visually observed outside the tank body, and then the change of the tank top pressure can be quickly responded to. In addition, since the volume of the nitrogen gas space B in the airbag is relatively larger than that of the oil and gas space A, most of the discharged gas can be nitrogen gas in the airbag on the premise of keeping the tank top pressure stable during oil inlet, so as to reduce the oil and gas emission of the internal floating roof storage tank.

[0019] 2) The inventor has found through research that the larger the proportion of the nitrogen gas space B, the greater the flexibility of the storage tank pressure regulation. When the volume ratio of the two is about 9:1, especially during the large breathing process of the storage tank, inflating and deflating the nitrogen gas space B in the airbag can basically balance the tank top pressure. Even when the pressure cannot be effectively regulated, only a small amount of high-concentration oil and gas in the oil and gas space A needs to be discharged, which can better achieve low oil and gas emission at the source of the storage tank.

[0020] 3) In the utility model, the bottom of the airbag is fixed on the upper surface of the floating roof, and the outer wall surface is serrated to form a bellows-type airbag structure that can be vertically folded. The airbag can always maintain the shape of a cylinder when contracting and stretching, and only the height changes with the rise and fall of the floating roof, which is beneficial to the uniform stress of the floating roof.

[0021] 4) The design of multiple pull ropes passing through the correspondingly arranged multiple rows of limit rings in the utility model can ensure that the pull ropes are basically always in the same position when the airbag contracts or stretches and deforms, and a better setting effect can be formed.

[0022] 5) The internal floating roof storage tank of the utility model can be applied in the large breathing and / or small breathing process of the storage tank. Under normal conditions, the contraction of the nitrogen gas space B in the airbag can be used to meet the requirement of basically stable tank top pressure. When the tank top pressure still cannot be adjusted to the required stable pressure in this case, a small amount of oil and gas can be appropriately discharged for pressure regulation to achieve the effect of energy conservation and emission reduction.

[0023] 6) For the storage tank adopting the utility model, the oil product is hermetically separated from the air, which can ensure that the oil and gas generated by the evaporation of the oil product is pure oil and gas (not containing air), and the gas itself is non-explosive, and the evaporated oil and gas can be safely controlled. The storage tank can be used for the storage process of oil products or organic chemicals, and has the characteristics of energy conservation, environmental protection, simple process, and safe operation.

[0024] The above description is only an overview of the technical solution of the present utility model. In order to more clearly understand the technical means of the present utility model and be implemented according to the content of the description, and at the same time to make the above and other purposes, technical features and advantages of the present utility model more understandable, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings as follows. Description of the Drawings

[0025] Figure 1 It is a schematic internal sectional view of the internal floating roof storage tank of the present utility model.

[0026] Main reference numeral description:

[0027] 1 - Tank body, 10 - Floating disc, 11 - Tank top pressure gauge, 2 - Airbag, 21 - Vent hole, 3 - Cable weight assembly, 31 - Multiple cables, 32 - Single cable, 33 - Fixed pulley, 34 - Weight, 4 - Nitrogen supply pipeline, 40 - Nitrogen flowmeter, 41 - First air supply branch, 411 - First nitrogen valve, 42 - Second air supply branch, 421 - Second nitrogen valve, 5 - Low - concentration waste gas discharge pipeline, 50 - Waste gas flowmeter, 51 - Waste gas valve, 6 - High - concentration oil - gas discharge pipeline, 60 - Oil - gas flowmeter, 61 - Oil - gas valve;

[0028] A - Oil - gas space, B - Nitrogen space. Detailed Embodiment

[0029] The following combines the accompanying drawings to describe the detailed embodiment of the present utility model in detail, but it should be understood that the protection scope of the present utility model is not limited by the detailed embodiment.

[0030] Unless otherwise clearly stated, throughout the description and claims, the term "comprising" or its variations such as "including" or "having" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0031] In this article, for the convenience of description, spatial relative terms such as "below", "beneath", "under", "above", "over", "on" etc. can be used to describe the relationship between one element or feature and another element or feature in the drawings. It should be understood that the spatial relative terms are intended to include different directions of the object in use or operation other than the directions depicted in the figures. For example, if the object in the figure is flipped, the element described as "below" or "under" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both the below and above directions. The object can also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0032] In this text, the terms "first", "second", etc. are used to distinguish two different components or parts, rather than to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchanged with each other.

[0033] As Figure 1 shown, the present utility model provides an internal floating roof storage tank for storing organic liquids such as oil products and organic chemicals, and at least includes a tank body 1, an airbag 2, and a cable weight assembly 3. Among them, a floating tray 10 (i.e., the internal floating roof storage tank) that can move up and down is provided in the tank body 1. Below the floating tray 10 is a liquid phase space, and above the floating tray is a gas phase space. The airbag 2 is in a bellows-like folded shape and is fixed on the upper surface of the floating tray 10; the upper end of the airbag 2 is provided with a reduced opening and has a ventilation hole 21; the inside of the airbag is a nitrogen space B, and the gas phase space outside the airbag is an oil and gas space A. The cable weight assembly 3 is provided with a plurality of cables in the tank body 1 that are evenly spaced and surround the outside of the airbag 2. The bottom ends of the plurality of cables 31 are circumferentially fixed on the upper surface of the floating tray 10 along the bottom of the airbag 2, and the top ends of the plurality of cables 31 converge and extend outside the tank body 1. A weight 34 is provided at the free end of the cable extending outside the tank.

[0034] Through the setting of the "bellows-like" folded columnar airbag and the cable weight assembly in the above technical solution of the present utility model, a plurality of cables surround the outside of the airbag, forming an effect similar to a "net bag", and the cables extend outside the tank body and a weight is provided at the free end. Since the bottom of the airbag is fixed on the upper surface of the floating tray, during the oil receiving or oil discharging process of the storage tank, as the space inside the airbag changes, the weight will move up and down. Therefore, the change of the liquid level in the tank can be visually observed outside the tank, and then the change of the tank top pressure can be quickly responded to; in addition, since the volume of the nitrogen space B in the airbag is relatively larger than that of the oil and gas space A, on the premise of keeping the tank top pressure stable during oil inlet, most of the discharged gas can be nitrogen in the airbag. Thus, not only can the waste gas emission of the internal floating roof storage tank be reduced, but also the change of the tank top pressure can be quickly responded to and kept basically stable. It should be noted here that: the airbag material used in the present utility model is an organic polymer membrane material. This kind of membrane material generally absorbs molecules that are similar and compatible with it. The gas phase space outside the airbag (i.e., the oil and gas space A) contains high-concentration oil and gas. Under high pressure, a very small amount of oil and gas will penetrate into the nitrogen space B inside the airbag. Therefore, after a period of time, there may be a mixture of nitrogen + a small amount of waste gas in the nitrogen space B, that is, nitrogen containing a low VOCs concentration ( Figure 1 the low-concentration waste gas in

[0035] Further, preferably but not limited to, when the airbag 2 is filled with nitrogen and in a fully expanded state, the volume ratio of the nitrogen space B in the airbag 2 to the oil-gas space A outside the airbag is 9:1. The inventor has found through research that the larger the proportion of the nitrogen space B, the greater the flexibility of the storage tank pressure regulation. When the volume ratio of the two is about 9:1, especially during the large breathing process of the storage tank, inflating and deflating the nitrogen space B in the airbag can basically balance the tank top pressure. Even when the pressure cannot be effectively regulated, only a small amount of high-concentration oil and gas in the oil-gas space A needs to be discharged, which can better achieve low emissions of oil and gas at the source of the storage tank.

[0036] Further as Figure 1 shown, the airbag 2 is preferably a bellows-type airbag with a serrated outer wall surface that can be vertically folded. Since the bottom of the airbag is fixed on the upper surface of the floating roof, with such an airbag structure, the airbag can always maintain a cylindrical shape during contraction and expansion, and only the height changes with the rise and fall of the floating roof, which is beneficial to the uniform stress of the floating roof.

[0037] Further as Figure 1 shown, limit rings (not shown in the figure) are provided at the creases of different heights on the outer wall surface of the airbag 2. Multiple columns of limit rings are provided, and the number of columns is the same as the number of stay ropes. Multiple stay ropes 31 pass through the corresponding multiple columns of limit rings. Through such a setting method, it can be ensured that when the airbag contracts or expands and deforms, the position of the stay ropes is always in the same position, forming a good pocketing effect. Further, multiple stay ropes 31 converge at the top of the airbag 2 in the tank and then extend outside the tank through a stay rope 32 and are connected to a counterweight 34 through a fixed pulley 33. Therefore, the up and down displacement of the counterweight 34 can reflect the up and down displacement of the floating roof in the tank, and the displacement of the floating roof is the change in the liquid level in the tank.

[0038] Further as Figure 1 shown, in order to maintain the pressure stability of the tank top during the large breathing and / or small breathing process of the storage tank, the present invention also designs a nitrogen supply pipeline 4, a low-concentration waste gas discharge pipeline 5, and a high-concentration oil and gas discharge pipeline 6. The nitrogen space B and the oil-gas space A are selectively communicated with the independently controlled nitrogen supply pipeline. Referring to Figure 1 , a nitrogen flowmeter 40 is provided on the nitrogen supply pipeline 4 to facilitate the statistics of the amount of nitrogen entering the spaces A and B of the storage tank. The nitrogen supply pipeline 4 includes a first air supply branch 41 (for supplying nitrogen to the nitrogen space B) and a second air supply branch 42 (for supplying nitrogen to the oil-gas space A). A first nitrogen valve 411 is provided on the first air supply branch 41, and a second nitrogen valve 421 is provided on the second air supply branch 42.

[0039] Further as Figure 1As shown, the low-concentration exhaust gas pipeline 5 is selectively connected to the nitrogen space B. An exhaust gas flowmeter 50 and an exhaust gas valve 51 are provided on the low-concentration exhaust gas pipeline 5. The high-concentration oil and gas discharge pipeline 6 is selectively connected to the oil and gas space A. An oil and gas flowmeter 60 and an oil and gas valve 61 are provided on the high-concentration oil and gas discharge pipeline 6. A pressure gauge 11 for monitoring the oil and gas pressure is provided at the top of the tank body 1. Through this pressure gauge 11, the pressure change can be monitored in real time, and the exhaust or inflation of the airbag nitrogen space B can be controlled according to the pressure change. In the case where the exhaust and inflation of the airbag cannot stabilize the tank top pressure, the oil and gas space A can be further exhausted or filled with nitrogen.

[0040] The working process of the internal floating roof storage tank of the present utility model will be described in detail below:

[0041] Before the storage tank is put into use, first install the airbag 2 inside the storage tank, and then introduce nitrogen into the A space to complete the air replacement of the storage tank; then, fill the B space inside the airbag with nitrogen. While filling, the exhaust gas volume of the A space is measured by the flowmeter 60 (i.e., FT101). When the exhaust gas volume reaches a certain value, observe that the airbag has fully expanded, and stop filling nitrogen. At this time, the oil receiving can be prepared. The oil receiving is the storage process, and the oil discharging is the oil discharging process. These two processes are the large breathing processes of the storage tank.

[0042] During the oil inlet process of the storage tank, the floating disc 10 rises with the rise of the liquid level, and the counterweight 34 descends. The lifting and lowering of the counterweight can display the fluctuation of the liquid level. The counterweight moves from the highest position from the ground at the start of oil inlet to the central balance position at the end of oil inlet. During the oil inlet process, the liquid level continuously rises, and the floating disc also moves upward, and the airbag is compressed until the oil inlet is completed. A large amount of oil and gas will be generated during this process; monitor the tank top pressure. For example, when the pressure is higher than 600 Pa, open the exhaust gas valve 51 (i.e., KV-102) to an appropriate opening degree, and appropriately discharge the low-concentration exhaust gas in the B space. When the pressure is lower than 600 Pa, close the exhaust gas valve 51 to keep the tank top pressure at 600 Pa. As the oil inlet liquid level rises, both the A space and the B space will be compressed. By detecting the size of the tank top pressure, first, the gas in the B space is still preferentially discharged to ensure the oil inlet volume. If the tank top pressure cannot be reduced to 600 Pa, then the oil and gas valve 61 (i.e., KV-101) is also opened to discharge a small amount of oil and gas.

[0043] During the oil discharging process of the storage tank, the liquid level continuously decreases, and the floating roof moves downward accordingly. The airbag unfolds until the oil discharging is completed and the pressure on the tank top becomes low. During this process, nitrogen needs to be replenished into space B in a timely manner. Open the first nitrogen valve 411 (i.e., KV-104). When the pressure on the tank top reaches 600 Pa, close the first nitrogen valve 411. The counterweight 34 is at the highest position from the start of oil discharging to the end of oil discharging at the center position from the ground. As the liquid level of the oil discharging drops, both space A and space B will become larger. By detecting the magnitude of the pressure on the tank top, nitrogen is preferentially replenished into space B to ensure the pressure balance inside the tank. When the pressure on the tank top cannot reach 600 Pa all the time, nitrogen can be appropriately replenished into space A (i.e., open the second nitrogen valve 421 (i.e., KV-103) with a smaller opening).

[0044] During the daily use and storage of oil products in the storage tank, "inhalation" and "exhalation" (i.e., the minor breathing process) will occur due to the influence of temperature, environmental changes, etc. The "inhalation" and "exhalation" of the storage tank will cause slight fluctuations in the liquid level inside the tank. With the solution of the present utility model, these changes can still be observed through the displacement of the counterweight 34. When the liquid level rises, the counterweight will drop accordingly; when the liquid level drops, the counterweight will rise accordingly. Through long-term observation and recording, the position change curve of the counterweight can be obtained, which is convenient for further studying the "inhalation" and "exhalation" laws of the minor breathing of the storage tank.

[0045] Therefore, the internal floating roof storage tank of the present utility model can be applied in the major breathing and / or minor breathing processes of the storage tank. Under normal conditions (i.e., when the pressure on the tank top is not too high), the contraction of the nitrogen space B in the airbag can be preferentially used to meet the requirement of the basic stability of the pressure on the tank top. When the pressure on the tank top cannot be adjusted to the required stable pressure in this case, a small amount of oil and gas can be appropriately discharged for pressure regulation to achieve the effect of energy conservation and emission reduction.

[0046] The foregoing description of the specific exemplary embodiments of the present utility model is for the purposes of illustration and exemplification. These descriptions are not intended to limit the present utility model to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present utility model and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the present utility model, as well as various different selections and changes. Any simple modification, equivalent change, and modification made to the above exemplary embodiments shall fall within the protection scope of the present utility model.

Claims

1. An internal floating roof storage tank, characterized in that: For storage of organic liquids, including: The tank body is provided with a floating plate that can move up and down, the space below the floating plate is a liquid phase, and the space above the floating plate is a gas phase; The airbag is folded in a bellows-like shape and fixed on the upper surface of the floating plate; the upper end of the airbag is configured as a contraction and has a vent hole; the airbag contains a nitrogen space, and the gas phase space outside the airbag is an oil-gas space; A draw rope counterweight assembly comprises a plurality of draw ropes evenly spaced apart and folded outside the airbag, the bottom ends of the draw ropes are fixed to the upper surface of the floating plate along the circumference of the bottom of the airbag, the top ends of the draw ropes converge and extend outside the tank body, and the free ends of the draw ropes extending outside the tank body are provided with counterweights.

2. The internal floating roof storage tank according to claim 1, characterized in that: When the airbag is filled with nitrogen and is in a fully expanded state, the volume ratio of the nitrogen space inside the airbag to the oil and gas space outside the airbag is 9:

1.

3. The internal floating roof storage tank according to claim 1, characterized in that: The outer wall surface of the airbag is serrated, forming a bellows-type airbag that can be folded vertically.

4. The internal floating roof storage tank according to claim 3, characterized in that: Limiting rings are arranged at folds at different heights on the outer wall of the airbag, and the plurality of drawstrings are passed through the limiting rings arranged in corresponding rows.

5. The internal floating roof storage tank according to claim 4, characterized in that: The plurality of draw ropes are gathered at the top of the air bag in the tank and extended to the outside of the tank through a draw rope, and are connected to the counterweight through a fixed pulley.

6. The internal floating roof storage tank according to claim 1, characterized in that: The nitrogen space and the oil-gas space are selectively connected to independently controlled nitrogen gas supply pipelines.

7. The internal floating roof storage tank according to claim 6, characterized in that: The nitrogen space is also selectively connected to a low-concentration exhaust gas discharge pipeline.

8. The internal floating roof storage tank according to claim 7, characterized in that: The oil and gas space is also selectively connected to a high-concentration oil and gas discharge pipeline.

9. The internal floating roof storage tank according to claim 1, characterized in that: A pressure gauge for monitoring oil and gas pressure is provided on the top of the tank.

10. The internal floating roof storage tank according to claim 8, characterized in that: The nitrogen gas supply pipeline, the low-concentration exhaust gas discharge pipeline and the high-concentration oil and gas discharge pipeline are all provided with flow meters and valves accordingly.

Images