System for removing heated fuel oil from an elongated storage tank

Abstract

The present invention describes a system for removing heated heavy oil from an elongated heavy oil storage tank (1). The system comprises a convection shield (2) having closed top (8) and sides (9) and a substantially open bottom, the convection shield (2) being mounted with a gap between the bottom of the storage tank (1) and a lower edge of the convection shield, such that the heavy oil can enter the convection shield through the open bottom, with a heating element (4) and a fuel intake line (3) disposed therein. The system is characterized by an elongated inflow convection shield (10) connected to the lower edge of the convection shield (2) and having an inflow heating element (15) therein, sharing a common interior through which the heated heavy oil can flow unimpeded from the inflow convection shield to the convection shield.

Description

[Technical field]

[0001] The present invention relates to a fuel system for large ships fuelled with heavy fuel oil, and more particularly to a system for removing heated heavy fuel oil from low height, elongated storage tanks. [Background technology]

[0002] Most large ships run on heavy fuel oil, which is a readily available fuel but has a high viscosity and needs to be heated to flow from storage tanks to consumer tanks. In the past, it was customary to heat the entire storage tank of heavy fuel oil, which was a waste of energy.

[0003] EP 2 630 402 describes a storage tank for heavy oil or other highly viscous fluids which, according to the patent, is provided with a convection shield having a heating element therein which allows pumping from the tank without the need to heat the entire tank.

[0004] However, many storage tanks are often located near the bottom of the ship and are formed as elongated rectangular parallelepipeds with low height. If the system according to EP 2630402 is installed in such storage tanks to save fuel heating energy, two problems arise. The first is that the entire tank is not heated when the bulk heating valve is open, because during cold conditions the convection pattern does not reach the end far from the convection shield due to the high viscosity. The second problem is that during cold conditions, especially when the fuel level is low, there is insufficient flow into the convection shield according to EP 2630402. The problem that arises during such conditions is that not enough fuel can enter the convection shield, and as a result the fuel intake line does not function properly.

[0005] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention to overcome the above-mentioned problems and to ensure reliable fuel flow even during low temperature conditions. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] European Patent No. 2630402 Summary of the Invention

[0007] The invention is set forth and characterized in the independent claims, with further characteristic features of the invention being set forth in the dependent claims.

[0008] In one aspect, the present invention describes a system for removing heated heavy oil from an elongated heavy oil storage tank, the system comprising a convection shield having closed top and sides and a substantially open bottom, the convection shield mounted with a gap between the storage tank bottom and a lower edge of the convection shield, and the heavy oil can flow into the convection shield through the open bottom.

[0009] The system further comprises a heating element disposed within the convection shield for heating the heavy oil within the convection shield, and a fuel intake line disposed within the convection shield for removing the heated heavy oil from the heavy oil storage tank. The system further comprises an elongated inflow convection shield having a closed upper portion including a top and sides, and a lower portion disposed at or below the lower edge of the convection shield, the lower portion having a through-flow opening through which the heavy oil can enter the inflow convection shield. The inflow convection shield is connected to the lower edge of the convection shield and shares a common interior so that the heated heavy oil can flow unimpeded from the inflow convection shield to the convection shield. The inflow heating element for heating the heavy oil within the inflow convection shield is disposed along the length of the inflow convection shield and within the inflow convection shield, the inflow convection shield extending longitudinally along the bottom of the storage tank.

[0010] In one embodiment, the inflow heating element is a heating pipe that loops through the inflow convection shield from the convection shield (2) to the end piece and back again.

[0011] In another embodiment, the inflow convection shield has an elongated rectangular shape with a top, two sides, an end piece at an outer end of the inflow convection shield, and a bottom having a number of openings.

[0012] In yet another embodiment, the inflow convection shield extends along more than 10% of the length or width of the storage tank, preferably more than 30% of the length of the storage tank.

[0013] In yet another embodiment, the convection shield has a bulk heating bulb mounted on top of the convection shield.

[0014] In yet another embodiment, the fuel intake line is located within the convection shield near the top.

[0015] In yet another embodiment, the system includes a second stage heater downstream of the convection shield, the second stage heater including a second stage convection shield having closed top and sides and a primarily closed bottom, a second stage heating element disposed within the second stage convection shield, a second stage channel directing partially heated heavy oil from the top of the second stage convection shield to the bottom of the second stage heater, and a fuel inlet line disposed within the inlet convection shield.

[0016] In yet another embodiment, the fuel inlet line is located within the second stage convection shield near the top.

[0017] In yet another embodiment, the second stage convection shield has a bulk heating bulb mounted on top of the convection shield.

[0018] In yet another embodiment, the second stage convection shield has drainage holes in the bottom of the second stage convection shield.

[0019] In a second aspect of the invention, an ocean-going vessel comprising a system according to the first aspect of the invention is described.

[0020] In order to facilitate an understanding of the invention, the following drawings are included, which illustrate embodiments of the invention and are described herein by way of example only: [Brief description of the drawings]

[0021] [Figure 1] 1 shows the convection shield with the inlet convection shield installed. [Diagram 2] 1 shows a convection shielded heavy fuel oil tank with an inflow convection shield installed. [Diagram 3] FIG. 13 illustrates a cross-sectional view of an embodiment with an inflow convection shield installed. [Figure 4] The embodiment of FIG. 2 is fitted with a second stage heater to illustrate a typical flow pattern of heavy oil through an active system. [Diagram 5] 13 illustrates the flow pattern in a storage tank using an embodiment of the present invention with the bulk heater valve open. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention describes a system for removing heated fuel oil from an elongated fuel oil storage tank 1, typically used for fuel. It is particularly useful for low height fuel oil tanks. Mostly, removing fuel oil is a slow process, e.g. to fuel engines or consumer tanks, but in some cases it may be necessary to empty the storage tank immediately.

[0023] As seen in Figures 1 and 2, the system comprises a convection shield 2 having a closed top 8 and closed sides 9 and a primarily open bottom side. Typically, the convection shield 2 has a box shape, alternatively an inverted bucket shape with a circular top or a hollow cylinder shape. A heating element 3 is disposed within the convection shield 2, and convection 6 occurs when the heating element heats the fuel oil. An exemplary flow pattern is shown in Figure 2. The heated fuel oil is taken from the interior of the convection shield 2 by a fuel inlet line 4. The inlet of the fuel inlet line 4 is disposed near the top end of the convection shield near the top where the temperature of the fuel oil is high. The convection shield 2 is mounted near the bottom of the storage tank 1, but a gap is provided between the bottom of the storage tank 1 and the lower edge of the convection shield to allow the fuel oil to flow into the convection shield 2 through the open bottom. The gap between the lower edge of the convection shield and the bottom of the storage tank is 5-70 cm, more preferably 10-15 cm.

[0024] To alleviate the aforementioned problems associated with low height storage tanks, the present invention describes an elongated inflow convection shield 10 having a closed upper portion 11 with a top 12 and sides 13 and an end piece 14 at the outer end of the inflow convection shield 10. The inflow convection shield further comprises a lower portion 16 having an opening 17 and is mounted at the same height as or lower than the lower edge of the convection shield, so that the heavy oil can enter the convection shield through the opening at the bottom of the lower portion. In one embodiment, the inflow convection shield 10 has the shape of an elongated rectangular parallelepiped with an open bottom. The inflow convection shield is connected to the lower edge of the convection shield. Preferably, for further heating, an opening is cut in the underside of the convection shield to which the inflow convection shield is fixed, matching the cross section of the inflow convection shield, allowing the partially heated heavy oil to flow unimpeded from the inflow convection shield 10 to the convection shield 2. The convection shield and the inflow convection shield share a common interior, allowing the heated heavy oil to flow unimpeded from the inflow convection shield to the convection shield.

[0025] The inflow heating element 15 is disposed along the length of and within the inflow convection shield 10. Preferably, the inflow heating element is a heating pipe that loops from the convection shield 2 to the end piece 14 and back again. The heating pipe has a heat carrier such as steam or a thermal fluid.

[0026] The inflow convection shield extends mainly along the bottom of the storage tank at the same height as the lower edge of the convection shield. This allows the heavy oil to flow into the heated section over a longer distance. Preferably, the inflow convection shield extends over more than 10% of the length of the storage tank 1, more preferably over 30%. Preferably, the convection shield is located at the rear / aft side of the storage tank. This is advantageous because ships are usually trimmed low aft and the convection shield is located at the lowest point in the storage tank. In other words, the convection shield is preferably located at the lowest point in the storage tank.

[0027] In one embodiment, a bulk heating valve 5 having an open and closed position is attached to the top 8 of the convection shield 2. In the open position, heated oil flows out of the convection shield upwards, and unheated oil is sucked in through the inlet convection shield 10 and the bottom side of the convection shield 2, resulting in convection 7 appearing in most of the storage tank, as shown in FIG. 5. When the bulk heating valve 5 is in the closed position, only the oil in the convection shield 2 is heated. The size of the valve is 2-30%, more preferably 2-10% of the area of ​​the top 8. In other words, the present invention functions as a normal convection shield when the bulk heating valve is in the closed position, and functions as a bulk heater when the bulk heating valve 5 is in the open position. The size of the bulk heating valve determines the proportion of heat released from the convection shield to the bulk of the storage tank. In a low height storage tank, most of the oil remains in the tank when the liquid level reaches the height of the bulk heating valve 5, at which point the flow pattern described above stops.

[0028] In one embodiment of the present invention, a second stage heater 21 is connected downstream of the convection shield. The purpose of the second stage heater is to provide a more stable oil temperature, since the height of the convection shield is low, resulting in a low height of the heating element 3, which results in a large temperature variation of the oil entering the fuel inlet line 4, which may cause the inlet line to become clogged. The second stage heater 21 comprises a second stage convection shield 19 having a closed top 9 and sides 8, a mainly closed bottom 24, and a second stage heating element 20. Since a secondary fuel suction pipe 23 takes the oil from the secondary convection shield, the bottom 24 of the secondary convection shield must be mainly closed to draw the heated oil from the convection shield 2 to the secondary convection shield 19. In one embodiment, the bottom 24 has drain holes. A second stage channel 22 directs the partially heated oil from the top of the convection shield to the bottom of the second stage heater 21. Inside the second stage convection shield 19, a second stage fuel suction line 23 is located. [Explanation of symbols]

[0029] 1. Heavy oil storage tank 2. Convection Shield 3 heating elements 4 Fuel intake line 5 Bulk Heating Valve 6 Convection in the convection shield 7 Convection in a Heavy Oil Storage Tank 8 Top (of convection shield) 9 (Convection Shield) Side 10 Inflow convection shield 11 Upper part of inlet convection shield 12 Top (of inlet convection shield) 13 (Inlet convection shield) side 14 End pieces (of the inlet convection shield) 15 Inlet heating element 16 Lower part 17 Opening 18 Convection Chamber 19 Second stage convection shield 20 Second stage heating element 21 Second stage heater 22 Second Stage Channel 23 Second stage fuel intake line 24 Bottom of second stage convection shield

Claims

1. A system for removing heated fuel oil from an elongated fuel oil storage tank (1), comprising: a convection shield (2) having closed top (8) and sides (9) and a substantially open bottom, said convection shield (2) being attached with a gap between the bottom of said storage tank (1) and a lower edge of said convection shield, said convection shield allowing heavy oil to flow into said convection shield through said open bottom; a heating element (3) disposed within the convection shield (2) for heating the heavy oil within the convection shield; a fuel intake line (4) disposed within the convection shield for removing heated fuel oil from the fuel oil storage tank; Equipped with An elongated inflow convection shield (10), comprising: a closed upper part (11) with a top (12) and sides (13); a lower portion (16) having through-flow openings (17) located at the same height or lower than the lower edge of the convection shield (2) to allow heavy oil to enter the inflow convection shield through the lower portion (16); Equipped with the inflow convection shield (10) is connected to the lower edge of the convection shield (2) and shares a common interior through which heated heavy oil can flow from the inflow convection shield to the convection shield; inflow heating elements (15) are disposed along the length and within the inflow convection shield (10) for heating the heavy oil within the inflow convection shield; The inlet convection shield extends longitudinally along the bottom of the storage tank. The system is characterized by an elongated inflow convection shield (10).

2. 2. The system of claim 1, wherein the inflow heating element (15) is a heating pipe that exits the convection shield (2) and loops along the length of the inflow convection shield (10) within the inflow convection shield (10) and then returns again.

3. 3. The system of claim 1 or 2, wherein the inflow convection shield (10) has an elongated rectangular shape having a top (12), two sides (13), an end piece (14) at an outer end of the inflow convection shield (10), and a bottom having a plurality of openings (17).

4. The system of claim 1, wherein the inflow convection shield (10) extends along more than 10% of the length or width of the storage tank, preferably more than 30% of the length of the storage tank.

5. The system of claim 1 , wherein the convection shield has a bulk heating valve mounted on top of the convection shield (2).

6. The system of claim 1 , wherein the fuel intake line (4) is disposed within the convection shield near the top.

7. The system comprises, downstream of the convection shield (2): a second stage convection shield (19) having closed top and sides and a primarily closed bottom; a second stage heating element (20) disposed within the second stage convection shield; a second stage channel (22) for directing partially heated fuel oil from the top of the convection shield to the bottom of the second stage heater (21); a second stage fuel intake line (23) disposed within the second stage convection shield (19); The system of claim 1 , further comprising a second stage heater (21) comprising:

8. The system of claim 7, wherein a fuel inlet line (23) is disposed within said second stage convection shield (19) near said top.

9. 8. The system of claim 7, wherein the second stage convection shield (19) has a bulk heating valve (5) mounted on top of the second stage convection shield (19).

10. The system of claim 7, wherein the bottom (24) of the second stage convection shield (19) has drainage holes.

11. 13. An ocean-going vessel comprising the system of claim 1.

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