Oil tank heating device and oil product storage system

Abstract

The invention provides an oil tank heating device and an oil product storage system, and particularly relates to the technical field of petroleum, the oil product storage system comprises the oil tank heating device, the oil tank heating device comprises a first heater and a second heater, the first heater comprises a tube shell and a heat exchange tube arranged in the tube shell, and the first end of the tube shell and the heat exchange tube are arranged in an oil tank; the second end of the pipe shell is arranged outside the oil tank, a corrugated pipe is adopted in the pipe shell to serve as a heat exchange pipe of a pipe pass, the first end of the pipe shell is open, the second heater is arranged outside the oil tank, the first heater is connected to the second heater, and the second heater comprises an oil product outlet. The heating target temperature of the first heater is lower than the heating target temperature of the second heater. The first heater can achieve the effects of preliminarily heating the oil in the oil tank and optimizing the fluidity of the oil in the oil tank, the oil in the oil tank can be prevented from being heated to be too high, and the second heater located outside the oil tank can heat the oil to the preset temperature for output.

Description

Technical Field

[0001] The invention relates to the field of petroleum technology, and in particular to an oil tank heating device and an oil product storage system. Background Art

[0002] In the current storage and transportation process of oil products in refineries, the high-viscosity heavy oil in the oil tank is heated by traditional methods such as installing coil heaters in the tank. The heavy oil in the tank is heated by heat exchange with heat media such as steam to reduce viscosity and improve its fluidity for easy pumping. However, this method also has many disadvantages: (1) Low steam utilization rate: In the actual production process, when only a small amount of heavy oil needs to be exported, the entire heavy oil in the tank must be heated, and the overall temperature is increased, making a large amount of steam useless; (2) Low heat utilization rate: The outlet temperature of the heater condensate is too high, often accompanied by a large amount of steam discharge, and the outlet temperature is ≥100℃, wasting a lot of thermal resources; (3) The heavy oil temperature is difficult to control: The traditional heater is a static natural convection heat exchanger for heavy oil heating, with a low heat transfer coefficient, resulting in a large amount of steam being discharged close to the heater. The temperature of the heavy oil near the heater is high, while the temperature of the heavy oil far from the heater is low; (4) Low heat exchange efficiency: For heavy oil with high viscosity, it is easy to produce decomposition products that aggregate on the surface of the heat exchange tube when it stays at high temperature for a long time on the heat exchange surface, causing the heavy oil temperature on the surface of the heat exchange tube to be too high, which is easy to coke, seriously affecting and hindering the conduction and distribution of heat; (5) Low production efficiency: Since it is impossible to heat the heavy oil quantitatively according to production needs, only the whole tank of heavy oil can be heated, the heat dissipation area is large, the heavy oil is heated slowly, the heating time is long, and the overall temperature distribution of the heavy oil is uneven. Especially in winter production, due to the influence of ambient temperature, the heating time will be longer; (6) Impact on heavy oil quality: Heavy oil produces a large number of fine decomposition products during the long-term and repeated heating process. Dissolving in the heavy oil will have a certain impact on the quality and increase the cost of later processing.

[0003] The local heater can only heat the oil to be transported to the outside, reducing the amount of heating. However, the existing built-in local heaters are large in size. The local heater of a 10,000 cubic meter storage tank can be more than 20 meters long, requiring a large installation space, which is not conducive to mechanical tank cleaning operations and limits the occasions of use. The external local heater cannot directly heat the more viscous oil in the tank to reduce the viscosity of the flow. When the oil enters the local heater from the storage tank, it is not easy for the oil to flow due to the high viscosity. Summary of the invention

[0004] One of the purposes of the present invention is to provide an oil tank heating device to solve the defect that only a built-in heater or a local heater can be used in the prior art.

[0005] In a first aspect, the present invention provides an oil tank heating device, comprising a first heater and a second heater, the first heater comprising a tube shell and a heat exchange tube arranged in the tube shell, the first end of the tube shell and the heat exchange tube are arranged inside the oil tank, the second end of the tube shell is arranged outside the oil tank, a corrugated tube is used as the heat exchange tube of the tube path in the tube shell, the first end of the tube shell is designed to be open, the second heater is arranged outside the oil tank, the first heater is connected to the second heater, the second heater comprises an oil product outlet, and the heating target temperature of the first heater is lower than the heating target temperature of the second heater.

[0006] In an optional embodiment, the heating target temperature of the first heater is 30 to 40 degrees Celsius, and the heating target temperature of the second heater is 40 to 60 degrees Celsius.

[0007] In an alternative embodiment, the heating load of the first heater is 20% to 50% of the total heating load.

[0008] In an optional embodiment, the heat exchange tubes are distributed in at least two layers of concentric circles with the central axis of the tube shell as the symmetry axis, and the spacing between the heat exchange tubes in each layer of heat exchange tubes increases from the inner layer to the outer layer.

[0009] In an optional embodiment, the spacing between the heat exchange tubes in the innermost layer is not less than 6 mm, and the spacing between the heat exchange tubes in the outermost layer is not greater than twice the outer diameter of the heat exchange tubes.

[0010] In an optional embodiment, the distance between the innermost heat exchange tube and the adjacent heat exchange tube is not less than 6 mm, and the distance between the outermost heat exchange tube and the adjacent heat exchange tube is not greater than 1 times the outer diameter of the heat exchange tube.

[0011] In an optional embodiment, the diameter of the tube shell is 400 mm to 1800 mm.

[0012] In an optional embodiment, the heat exchange tube uses steam as the heat medium; the heat exchange tube is electrically heated.

[0013] In an optional embodiment, the second end of the tube shell further includes a bell mouth with an expanded diameter.

[0014] The second object of the present invention is to provide an oil storage system to solve the problem of inconvenience in transporting high-viscosity heavy oil in the prior art.

[0015] In a second aspect, the present invention provides an oil storage system, comprising an oil tank and an oil tank heating device according to any one of the aforementioned embodiments.

[0016] The oil tank heating device provided by the present invention has the following beneficial effects:

[0017] 1. The heating target temperature of the first heater is lower than the heating target temperature of the second heater, and the heat exchange tube of the first heater is arranged inside the oil tank. The first heater can preliminarily heat the oil in the oil tank and optimize the fluidity of the oil in the oil tank, and can also avoid the problem of steam consumption caused by the oil in the oil tank being heated to too high a temperature. The second heater located outside the oil tank only needs to heat the oil to a predetermined temperature for external transmission;

[0018] 2. The shell and tube adopts a bellows as the tube pass, which can improve the heat transfer performance of the shell and tube and increase the heat transfer efficiency of the first heater;

[0019] 3. The first end of the tube shell is designed to be open, and the oil can directly enter the tube shell completely from the first end of the tube shell. The flow cross-sectional area of ​​the oil entering the tube shell inlet is large, which greatly reduces the flow rate of the low-temperature oil in the oil tank entering the tube shell and the pressure drop at the tube shell inlet. At the same time, the tube shell can prevent the heat of the heated oil in the tube shell from being lost to the outside of the tube shell.

[0020] The oil storage system provided by the present invention includes a separation device according to any one of the aforementioned embodiments, which also has the above advantages and will not be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic diagram of the overall structure of the oil storage system provided by the present invention;

[0023] Figure 2 One of the schematic diagrams of the installation state of the first heater of the oil tank heating device provided by the present invention;

[0024] Figure 3 A schematic diagram of the distribution state of the heat exchange tubes of the first heater of the oil tank heating device provided by the present invention;

[0025] Figure 4 The second schematic diagram of the installation state of the first heater of the oil tank heating device provided by the present invention.

[0026] Icon: 100 - oil tank; 200 - first heater; 210 - tube shell; 211 - first end; 212 - second end; 220 - heat exchange tube; 300 - second heater. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0030] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0031] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0032] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0034] Oil tank heating device

[0035] The embodiment of the present invention provides an oil tank heating device, such as Figures 1 to 3 As shown, it includes a first heater 200 and a second heater 300. The first heater 200 includes a tube shell 210 and a heat exchange tube 220 arranged in the tube shell 210. The first end 211 of the tube shell and the heat exchange tube 220 are arranged inside the oil tank 100, and the second end 212 of the tube shell is arranged outside the oil tank 100. The tube shell 210 adopts a corrugated tube as a tube pass, and the first end of the tube shell 210 is an open design. The second heater 300 is arranged outside the oil tank 100, the first heater 200 is connected to the second heater 300, and the second heater 300 includes an oil product outlet. The heating target temperature of the first heater 200 is lower than the heating target temperature of the second heater 300.

[0036] Figure 1 The overall structural diagram of the oil storage system provided by the present invention includes an overall structural diagram of the oil tank 100 and the heating device. Figure 2 This is a schematic diagram of the installation state of the first heater 200 of the heating device of the oil tank 100 provided by the present invention, wherein the oil tank 100 is partially schematically shown. Figure 3 Schematic diagram of the distribution state of the heat exchange tubes 220 of the first heater 200 of the oil tank 100 heating device provided by the present invention.

[0037] In the heating device of the oil tank 100 provided in the present embodiment, the heating target temperature of the first heater 200 is lower than the heating target temperature of the second heater 300, and the heat exchange tube 220 of the first heater 200 is arranged inside the oil tank 100. The first heater 200 can play the role of preliminarily heating the oil products for external transmission in the oil tank 100, thereby improving the fluidity of the oil products in the oil tank 100, and can also avoid the problem of steam consumption caused by the temperature of all the oil products in the oil tank 100 being heated to too high. The second heater 300 located outside the oil tank 100 only needs to heat the oil products to a predetermined temperature for external transmission.

[0038] Moreover, due to the separate arrangement of the first heater 200 and the second heater 300, the overall volume of the first heater 200 can be made smaller, especially the volume of the portion of the first heater 200 located inside the oil tank 100 can be made smaller, and the space occupied inside the oil tank 100 is also correspondingly smaller. For existing storage tanks with smaller renovation space, the space requirement inside the tank is small, which is conducive to renovation and application.

[0039] In the heating device of the oil tank 100 provided in this embodiment, a corrugated tube is used in the tube shell 210 as a heat exchange tube of the tube pass, which can improve the heat transfer performance in the tube shell 210 and increase the heat transfer efficiency of the first heater 200.

[0040] When using a bellows as the pipe pass, the velocity vector of the fluid in the bellows will gather toward the center when it flows out of the bellows, and the fluid in the bellows will detach from the wall, resulting in the pressure at the center of the pipe being greater than the wall pressure, the velocity near the inner wall of the bellows tends to 0, and the flow field in the bellows is chaotic, the center velocity is greater than the inlet velocity, and there is an obvious flow vortex in the corrugated area of ​​the bellows. When considering the heat transfer properties of the bellows, because the internal fluid will be affected by the vortex in the bellows, more fluid can exchange heat in the bellows, and because the presence of the bellows increases the heat exchange area, the heat transfer performance of the bellows will be better than that of the straight circular tube. The local vortex causes the time of convective heat exchange between the fluid and the tube wall to increase, significantly improving the heat transfer efficiency. In addition, according to literature reports, the use of bellows can reduce the shell-side pressure drop by 3.42% to 7.9% compared with the use of smooth tubes, and increase the Nusselt number by 11.01% to 28.74%. Compared with the use of smooth straight tubes, bellows have better heat transfer effects.

[0041] In the oil tank 100 heating device provided in the present embodiment, the first end of the tube shell 210 is designed to be open, and the oil can directly enter the tube shell 210 completely from the first end of the tube shell 210. The flow cross-sectional area of ​​the oil entering the inlet of the tube shell 210 is large, which greatly reduces the flow rate of the low-temperature oil in the oil tank 100 entering the tube shell 210 and the pressure drop at the inlet of the tube shell 210. At the same time, the tube shell 210 can prevent the heat of the heated oil in the tube shell 210 from being dissipated outside the tube shell 210.

[0042] The high-viscosity heavy oil in the oil tank 100 has a low storage temperature, high viscosity, and poor fluidity. The general built-in heating device only adopts a structural design in which an oil product inlet is set on the side or bottom of the oil tank 100. At this time, the diameter of the shell side inlet can often only be about 1 / 4 of the diameter of the tube shell 210, resulting in a difference of 16 times with the internal flow cross-sectional area of ​​the first heat exchanger, and the local inlet flow rate is 16 times the shell side flow rate of the first heat exchanger. Due to the high viscosity of low-temperature oil products and the natural flow, there is still a large pressure drop near the heat exchanger inlet, which is not conducive to pumping. In addition, because the high-viscosity heavy oil in the oil tank 100 has a high viscosity, an excessively high flow rate will produce a large pump inlet pressure drop, which is not conducive to operation.

[0043] In order to reduce the flow resistance, this embodiment does not close the shell side, and the second end 212 of the tube shell located in the oil tank 100 is open. The inlet diameter is the shell side diameter. Compared with the scheme in which the shell side inlet diameter can only be 1 / 4 of the shell diameter, the inlet diameter of this embodiment can be enlarged to 4 times, and the flow speed of the low-temperature oil is further reduced, reducing the pressure drop. According to the Bernoulli equation, the pressure difference is proportional to the square difference of the speed, so the pressure drop at the inlet can be reduced to about 1% of the original.

[0044] In some embodiments, the second end 212 of the tube shell further includes a bell mouth with an expanded diameter, such as Figure 4 As shown, the length of the expanded diameter section does not exceed the diameter of the tube shell 210, and the expanded diameter section forms an angle of 0 to 45 degrees with the tube shell. Figure 4 The angle between the middle expanded diameter portion and the tube shell is marked as α, 0°<α≤45°. The diameter of the tube shell 210 is represented as D, the length of the non-expanded diameter section in the second end 212 of the tube shell disposed in the oil tank 100 is represented as L, the length of the expanded diameter section in the second end 212 is ≤D, and the length of the heat exchange tube 220 is between L and L+D.

[0045] On the other hand, compared with the built-in heater without the tube shell 210, in the built-in heater without the tube shell 210, the oil near the heat exchanger and the oil far away will generate convection, so that the heat of the oil will be lost to the far distance, and the heating effect of the heater without the tube shell 210 is poor. The tube shell 210 provided in this embodiment has an open design at the first end, and the oil after entering the tube shell 210 will flow in the tube shell 210, and the flow direction of the oil is relatively stable, without the influence of the dispersion flow in other directions, the temperature will not be lost, and a better heating effect is achieved.

[0046] In some embodiments, the heating target temperature of the first heater 200 is 30 to 40 degrees Celsius, and the heating target temperature of the second heater 300 is 40 to 60 degrees Celsius. For example, the heating target temperature of the first heater 200 can be set to 35 degrees Celsius, and the heating target temperature of the second heater 300 can be set to 45 degrees Celsius.

[0047] In some embodiments, the heating load of the first heater 200 is 20% to 50% of the total heating load. The first heater 200 mainly serves to improve the fluidity of the oil product, which can reduce the volume of the first heater 200, avoid the first heater 200 occupying too much internal space of the oil tank 100, and improve the convenience of installing the first heater 200 inside the oil tank 100.

[0048] In some embodiments, Figure 3As shown, the heat exchange tubes 220 are distributed in at least two layers of concentric circles with the central axis of the tube shell 210 as the axis of symmetry, and the spacing between the heat exchange tubes 220 in each layer of heat exchange tubes 220 increases from the inner layer to the outer layer. The multiple heat exchange tubes 220 are distributed in multiple layers of concentric circles, which is easier to control the spacing between the heat exchange tubes 220 in each layer of heat exchange tubes 220 than in a square or regular triangle arrangement. In the tube shell 210, the oil product flows faster near the center, and the spacing between the heat exchange tubes 220 in the inner layer is smaller, so a higher arrangement density can be achieved, and the densely distributed heat exchange tubes 220 can enhance heat transfer and improve the heating effect. The oil product flows slower near the tube shell 210, and the spacing between the heat exchange tubes 220 in the outer layer is larger, so a lower arrangement density can be achieved, and the heating effect on the oil product is relatively weak, which can effectively avoid coking and scaling of the oil product. At the same time, high temperature caused by slow flow in the tube shell 210 can also be avoided, and the heat transfer of the oil in the tube shell 210 to the surrounding oil outside the tube shell 210 can be effectively reduced, thereby ensuring the insulation effect of the first heater 200 and further improving the heating effect of the first heater 200.

[0049] In some embodiments, the spacing between the innermost heat exchange tubes 220 is not less than 6 mm to facilitate mechanical cleaning, so that the innermost heat exchange tubes 220 can also obtain a sufficient cleaning effect.

[0050] In some embodiments, the spacing between the outermost heat exchange tubes 220 is no greater than 2 times the outer diameter of the heat exchange tubes 220. The spacing between the innermost heat exchange tubes 220 and the adjacent heat exchange tubes 220 is no less than 6 mm, and the spacing between the outermost heat exchange tubes 220 and the adjacent heat exchange tubes 220 is no greater than 1 times the outer diameter of the heat exchange tubes 220.

[0051] In some embodiments, the diameter of the tube shell 210 is 400 mm to 1800 mm, so as to avoid being too small to achieve a sufficient heating effect, and to avoid being too large to occupy too much internal space of the oil tank 100.

[0052] In some embodiments, the heat exchange tube 220 uses steam as the heat medium. Since the heating target temperature of the first heater 200 is relatively low, relatively low-temperature steam can be used as the heat medium, which is beneficial for utilizing low-grade steam in the refinery and improving the efficiency of the entire steam system.

[0053] In some embodiments, the heat exchange tube 220 is electrically heated, which helps to avoid high temperature on the surface of the heat exchange tube 220, reduce the structure and coking on the surface of the heat exchange tube 220, and improve the efficiency of the heating system.

[0054] Oil storage system

[0055] An embodiment of the present invention provides an oil storage system, comprising any one of the oil tank 100 heating devices in the above embodiments.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oil tank heating device, characterized in that: The invention comprises a first heater (200) and a second heater (300), wherein the first heater (200) comprises a tube shell (210) and a heat exchange tube (220) arranged in the tube shell (210), wherein the first end (211) of the tube shell and the heat exchange tube (220) are arranged in the oil tank (100), and the second end (212) of the tube shell is arranged outside the oil tank (100), wherein a corrugated tube is used as the heat exchange tube (220) of the tube side in the tube shell (210), and the first end of the tube shell (210) is of an open design, and the second heater (300) is arranged outside the oil tank (100), wherein the first heater (200) is connected to the second heater (300), and the second heater (300) comprises an oil product outlet, and the heating target temperature of the first heater (200) is lower than the heating target temperature of the second heater (300).

2. The oil tank heating device according to claim 1, characterized in that: The heating target temperature of the first heater (200) is 30 to 40 degrees Celsius, and the heating target temperature of the second heater (300) is 40 to 60 degrees Celsius.

3. The oil tank heating device according to claim 1, characterized in that: The heating load of the first heater (200) is 20% to 50% of the total heating load.

4. The oil tank heating device according to claim 1, characterized in that: The heat exchange tubes (220) are distributed in at least two layers of concentric circles with the central axis of the tube shell (210) as the symmetry axis, and the spacing between the heat exchange tubes (220) in each layer of heat exchange tubes (220) increases from the inner layer to the outer layer.

5. The oil tank heating device according to claim 4, characterized in that: The spacing between the innermost layer of heat exchange tubes (220) is not less than 6 mm, and the spacing between the outermost layer of heat exchange tubes (220) is not greater than twice the outer diameter of the heat exchange tubes (220).

6. The oil tank heating device according to claim 4, characterized in that: The distance between the innermost heat exchange tube (220) and the adjacent heat exchange tube (220) is not less than 6 mm, and the distance between the outermost heat exchange tube (220) and the adjacent heat exchange tube (220) is not greater than 1 times the outer diameter of the heat exchange tube (220).

7. The oil tank heating device according to claim 1, characterized in that: The diameter of the tube shell (210) is 400 mm to 1800 mm.

8. The oil tank heating device according to claim 1, characterized in that: The heat exchange tube (220) uses steam as a heat medium; or, the heat exchange tube (220) uses electrical heating.

9. The oil tank heating device according to claim 1, characterized in that: The second end (212) of the tube shell also includes a bell mouth with an enlarged diameter.

10. An oil storage system, characterized in that: It comprises an oil tank (100) and an oil tank (100) heating device according to any one of claims 1 to 9.

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