A waste heat utilization device for LNG internal combustion powered ships

Abstract

The present invention provides a waste heat utilization device for an LNG internal combustion powered ship, comprising a heat exchange box; a first heat exchange tube and a second heat exchange tube disposed within the heat exchange box; a heat transfer fluid contained within the heat exchange box; the first heat exchange tube being hermetically rotatably connected to the engine's cooling water pipeline and having a first heat exchange fin arrayed along its length; the second heat exchange tube being hermetically rotatably connected to the fuel pipeline between the LNG storage tank and the engine and having a second heat exchange fin arrayed along its length; the first heat exchange fins and the second heat exchange fins being arranged in an alternating pattern; and a heat exchange rate control unit configured to adjust the size of the axially projected overlapping area between the first and second heat exchange fins by controlling the rotation of the first and second heat exchange tubes. The device of the present invention rapidly adjusts the heat exchange rate from the cooling water pipeline to the fuel pipeline when the output power of the LNG engine changes, rationally utilizing waste heat and achieving energy conservation and emission reduction effects in the operation of the LNG internal combustion powered ship.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat utilization of LNG internal combustion powered ships, and in particular provides a waste heat utilization device for LNG internal combustion powered ships. Background Art

[0002] LNG fuel, as a high-quality, efficient, and economical clean energy source, has garnered widespread attention and optimism. With China's advocacy for clean energy and the continuous advancement of technology, LNG-powered ships are gradually being adopted in inland and coastal shipping. During operation, LNG fuel from the tank is supplied to the engine through valves and fuel lines, where it is converted from liquid to gas due to a significant pressure differential. Under normal temperature conditions, tiny amounts of incompletely vaporized liquid LNG gas can remain in the fuel lines and enter the LNG engine in an unsaturated state, leading to incomplete fuel combustion. This not only affects system efficiency and wastes fuel, but also causes environmental pollution when exhaust gases from incomplete combustion are released into the air.

[0003] To address these issues, some LNG engines use a heat exchanger to preheat the fuel line with heat from the engine's cooling water to improve LNG vaporization. However, extensive practical experience has shown that existing heat exchangers have a fixed heat transfer rate, making them incapable of adapting to varying engine output conditions. Under heavy loads, the LNG tank supplies fuel to the engine through the fuel line at a high rate. Limited by the fixed heat transfer rate of the heat exchanger, heat from the cooling water line cannot be transferred to the fuel line in a timely manner, resulting in poor preheating of the fuel line and inability to address insufficient LNG vaporization. Furthermore, the cooling water heat cannot be dissipated quickly enough, exceeding the ideal temperature, impacting engine performance. Under light loads, the LNG tank supplies fuel to the engine through the fuel line at a lower rate. Limited by the fixed heat transfer rate of the heat exchanger, excessive heat is dissipated from the cooling water line to the fuel line, resulting in heat waste and causing the cooling water to dissipate excessively below its ideal temperature, impacting engine performance. Summary of the Invention

[0004] Based on this, the present invention provides a waste heat utilization device for LNG internal combustion powered ships, which is provided with a heat exchange box with adjustable heat exchange speed. When the output power of the LNG engine changes, the heat exchange speed from the cooling water pipeline to the fuel pipeline can be quickly adjusted to adapt to the change of LNG fuel supply speed, improve the vaporization rate of LNG in the fuel pipeline, and keep the water temperature of the cooling water within the set range, so as to reasonably utilize the waste heat and achieve the purpose of energy saving and emission reduction in the operation of LNG internal combustion powered ships.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] An LNG internal combustion powered ship waste heat utilization device, comprising a heat exchange box and a heat exchange speed control unit;

[0007] The heat exchange box is provided with a first heat exchange tube and a second heat exchange tube parallel to each other and extending in the horizontal direction. The first heat exchange tube and the second heat exchange tube both pass through the side walls of the heat exchange box and are sealed and rotatably connected to the heat exchange box. The heat exchange box is filled with heat transfer fluid.

[0008] The first heat exchange tube is sealingly and rotatably connected to the cooling water pipeline of the engine, and a plurality of first heat exchange fins are arranged in an array along the length of the tube surface located in the heat exchange box; the second heat exchange tube is sealingly and rotatably connected to the fuel pipeline between the LNG storage tank and the engine, and a plurality of second heat exchange fins are arranged in an array along the length of the tube surface located in the heat exchange box; the plurality of first heat exchange fins and the plurality of second heat exchange fins are arranged in an alternating manner;

[0009] The heat exchange speed control unit is configured to adjust the size of the axially projected overlapping area between the first heat exchange fin and the second heat exchange fin by controlling the rotation of the first heat exchange tube and the second heat exchange tube.

[0010] Furthermore, the first heat exchange fin and the second heat exchange fin are both circular plates, the first heat exchange tube passes through the first heat exchange fin and the axis of the first heat exchange tube is eccentrically arranged relative to the axis of the first heat exchange fin, and the second heat exchange tube passes through the second heat exchange fin and the axis of the second heat exchange tube is eccentrically arranged relative to the axis of the second heat exchange fin.

[0011] Furthermore, the heat exchange speed control unit includes a rotation mechanism capable of driving the first heat exchange tube to rotate and a constant velocity transmission mechanism provided between the first heat exchange tube and the second heat exchange tube. When the first heat exchange tube rotates, the constant velocity transmission mechanism drives the second heat exchange tube to rotate in a constant circumferential direction.

[0012] The eccentric direction of the axis of the first heat exchange tube relative to the axis of the first heat exchange fin is symmetrical to the eccentric direction of the axis of the second heat exchange tube relative to the axis of the second heat exchange fin.

[0013] Furthermore, the heat exchange speed control unit drives the first heat exchange tube and the second heat exchange tube to rotate. When the distance between the axes of the first heat exchange fin and the second heat exchange fin is the smallest, the second heat exchange fin is inserted between two adjacent first heat exchange fins, and the axial projection overlap area between the first heat exchange fin and the second heat exchange fin is the largest; when the distance between the axes of the first heat exchange fin and the second heat exchange fin is the largest, the axial projection overlap area between the first heat exchange fin and the second heat exchange fin is the smallest or there is no axial projection overlap area.

[0014] Furthermore, the first heat exchange tube is located directly above the second heat exchange tube; the heat transfer liquid level in the heat exchange box is higher than the first heat exchange tube, and when the axial projection overlap area between the first heat exchange fin and the second heat exchange fin is the smallest or there is no axial projection overlap area, most of the portion of the first heat exchange fin located above the first heat exchange tube is exposed to the heat transfer liquid surface.

[0015] Furthermore, the constant speed transmission mechanism includes a driving gear and a driven gear with equal number of teeth and meshing with each other, the driving gear is connected to the first heat exchange tube, and the driven gear is connected to the second heat exchange tube; the rotating mechanism includes an adjusting motor and a belt transmission assembly, the driving pulley of the belt transmission assembly is connected to the motor shaft of the adjusting motor; the driven pulley of the belt transmission assembly is connected to the first heat exchange tube, the transmission belt is arranged between the driving pulley and the driven pulley, and the adjusting motor drives the first heat exchange tube to rotate through the belt transmission assembly.

[0016] Furthermore, a fuel flow monitor is provided on the fuel pipeline, and the fuel flow monitor is electrically connected to the heat exchange speed control unit;

[0017] The heat exchange speed control unit is configured to control the action of the rotating mechanism according to the monitoring value of the fuel flow monitor;

[0018] When the fuel flow rate value monitored by the fuel flow monitor increases, the heat exchange speed control unit adjusts the axial projection overlap area between the first heat exchange fin and the second heat exchange fin to increase. When the fuel flow rate monitoring value decreases, the heat exchange speed control unit drives the axial projection overlap area between the first heat exchange fin and the second heat exchange fin to decrease.

[0019] Furthermore, a fuel temperature monitor is provided on the fuel pipeline, and the fuel temperature monitor is electrically connected to the heat exchange speed control unit;

[0020] The heat exchange speed control unit is configured to control the action of the rotating mechanism according to the monitoring value of the fuel temperature monitor;

[0021] When the fuel temperature value monitored by the fuel temperature monitor decreases, the heat exchange speed control unit adjusts the axial projection overlap area between the first heat exchange fin and the second heat exchange fin to increase. When the fuel temperature monitoring value increases, the heat exchange speed control unit drives the axial projection overlap area within the first heat exchange fin and the second heat exchange fin bracket to decrease.

[0022] Furthermore, both ends of the first heat exchange tube are sealed and rotatably connected to the cooling water pipeline through a first rotary sealing mechanism, and both ends of the second heat exchange tube are sealed and rotatably connected to the fuel pipeline through a second rotary sealing mechanism.

[0023] Compared with the existing technology, the technical advantages of the LNG internal combustion powered ship waste heat utilization device provided are at least reflected in:

[0024] On the one hand, a heat exchange box is set between the engine and the LNG storage tank, including a first heat exchange tube sealed and rotatably connected to the cooling water pipeline, and a second heat exchange tube sealed and rotatably connected to the fuel pipeline. A first heat exchange fin is set on the first heat exchange tube, and a second heat exchange fin is set on the second heat exchange pipeline. The heat exchange speed control unit adjusts the size of the axial projection overlapping area of ​​the two heat exchange fins by changing the relative positions of the first heat exchange fin and the second heat exchange fin, dynamically changes the heat exchange speed, adapts to changes in the output power operating conditions of the engine, adapts to changes in the LNG fuel supply speed, improves the LNG vaporization rate, and keeps the water temperature of the cooling water within the set range, thereby achieving energy saving and emission reduction effects during the operation of LNG internal combustion powered ships.

[0025] Secondly, the first heat exchange fin on the surface of the first heat exchange tube is eccentrically set, and the second heat exchange fin on the surface of the second heat exchange tube is eccentrically set. The first heat exchange tube and the second heat exchange tube are connected by a constant speed transmission mechanism. The two heat exchange fins are symmetrically arranged in the eccentric direction. The rotating mechanism drives the two heat exchange tubes to rotate at a constant speed to achieve the overlap adjustment of the axial projection area of ​​the heat exchange fins, so as to achieve the purpose of fast and stable adjustment of the heat exchange speed between the two heat exchange tubes.

[0026] Thirdly, a monitor for monitoring fuel flow and temperature is installed in the fuel pipeline. The heat exchange rate control unit adjusts the axial projection overlapping area of ​​the first heat exchange fin and the second heat exchange fin according to the monitored fuel flow and temperature information, thereby accurately controlling the heat exchange rate between the two heat exchange tubes, improving the LNG vaporization rate and maintaining a reasonable water temperature for the cooling water, achieving a balanced operating condition of the engine, rationally utilizing waste heat, and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 This is a schematic structural diagram of the LNG internal combustion powered ship waste heat utilization device provided by the present invention;

[0029] Figure 2 It is a structural schematic diagram of the heat exchange box provided by the present invention;

[0030] Figure 3 A schematic diagram of the structure of the heat exchange box provided by the present invention with part of the box body removed;

[0031] Figure 4This is a control system block diagram of the LNG internal combustion powered ship waste heat utilization device provided by the present invention;

[0032] Figure 5 This is a schematic diagram of the state of the heat exchange box provided by the present invention being adjusted to a high-speed heat exchange state;

[0033] Figure 6 This is a schematic diagram of the state in which the first heat exchange tube and the second heat exchange tube of the present invention are adjusted to a high-speed heat exchange state;

[0034] Figure 7 This is a schematic diagram of the state in which the first heat exchange fin plate and the second heat exchange fin plate of the present invention are adjusted to a high-speed heat exchange state;

[0035] Figure 8 This is a schematic diagram of the state where the heat exchange box provided by the present invention is adjusted to a low-speed heat exchange state;

[0036] Figure 9 This is a schematic diagram of the state in which the first heat exchange tube and the second heat exchange tube of the present invention are adjusted to a low-speed heat exchange state;

[0037] Figure 10 It is a schematic diagram of the state in which the first heat exchange fin plate and the second heat exchange fin plate of the present invention are adjusted to a low-speed heat exchange state.

[0038] Description of the accompanying drawings:

[0039] 1-heat exchange box, 11-first heat exchange tube, 12-first heat exchange fin, 13-first rotary sealing mechanism, 14-second heat exchange tube, 15-second heat exchange fin, 16-second rotary sealing mechanism;

[0040] 2-engine, 21-cooling water pipeline, 22-fuel pipeline;

[0041] 3-LNG storage tank;

[0042] 4-heat exchange speed control unit, 41-rotation mechanism, 42-constant speed transmission mechanism, 43-fuel flow monitor, 44-fuel temperature monitor;

[0043] 5-Thermal fluid level.

[0044] It should be understood that the size of each part shown in the drawings is not drawn according to the actual proportional relationship.In addition, the same or similar reference numerals represent the same or similar components. DETAILED DESCRIPTION

[0045] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure, its application, or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of the components and steps and the composition of the materials set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0046] Example 1:

[0047] A waste heat utilization device for LNG internal combustion powered ships, such as Figures 1 to 4 As shown, it includes a heat exchange box 1 and a heat exchange speed control unit 4;

[0048] The heat exchange box 1 is provided with a first heat exchange tube 11 and a second heat exchange tube 14 that are parallel to each other and extend in the horizontal direction. The first heat exchange tube 11 and the second heat exchange tube 14 both pass through the side walls of the heat exchange box 1 at both ends and are sealed and rotatably connected to the heat exchange box 1. The heat exchange box 1 is filled with heat transfer fluid.

[0049] The first heat exchange tube 11 is sealed and rotatably connected to the cooling water pipeline 21 of the engine 2, and a plurality of first heat exchange fins 12 are arranged in an array along the length of the tube surface located within the heat exchange box 1. The second heat exchange tube 14 is sealed and rotatably connected to the fuel pipeline 22 between the LNG storage tank 3 and the engine 2, and a plurality of second heat exchange fins 15 are arranged in an array along the length of the tube surface located within the heat exchange box 1. The plurality of first heat exchange fins 12 and the plurality of second heat exchange fins 15 are arranged in an alternating manner.

[0050] The heat exchange rate control unit 4 is configured to adjust the size of the axially projected overlapping area between the first heat exchange fins 12 and the second heat exchange fins 15 by controlling the rotation of the first heat exchange tube 11 and the second heat exchange tube 14, that is, to adjust the heat exchange rate between the first heat exchange tube 11 and the second heat exchange tube 14. The first heat exchange fins 12 and the second heat exchange fins 15 exchange heat via a heat transfer fluid.

[0051] Currently, LNG engines on LNG internal combustion powered ships use heat from the engine cooling water to preheat the fuel pipeline through a heat exchanger. However, extensive practical experience has shown that the heat exchange rate of the heat exchanger is fixed and cannot adapt to the changing operating conditions of the engine's output power, thus affecting the normal working state of the engine.

[0052] Based on the LNG internal combustion powered ship waste heat utilization device provided in this embodiment, the heat exchange rate control unit dynamically changes the heat exchange rate between the two heat exchange tubes by changing the relative position of the first heat exchange fin 12 and the second heat exchange fin 15, adjusting the size of the axial projection overlapping area between the first heat exchange fin 12 and the second heat exchange fin 15, so as to quickly adjust the heat exchange rate from the cooling water pipeline to the fuel pipeline, adapt to the change of the output power of the LNG engine, rationally utilize the waste heat, and achieve the energy saving and emission reduction effect of the ship operation.

[0053] Specifically, when the working condition is heavy load, the axial projection overlapping area of ​​the first heat exchange fin 12 and the second heat exchange fin 15 is increased, thereby improving the heat exchange speed; when the working condition is light load, the axial projection overlapping area of ​​the first heat exchange fin 12 and the second heat exchange fin 15 is reduced, thereby reducing the heat exchange speed, thereby adapting to the changes in the output power of the engine and the changes in the working conditions. It not only adapts to the changes in the LNG fuel supply speed and improves the LNG vaporization rate, but also keeps the water temperature of the cooling water within the set range, thereby realizing the rational use of waste heat and achieving the energy-saving and emission reduction effects of the operation of LNG internal combustion powered ships.

[0054] like Figures 5 to 10 As shown, in this embodiment, the first heat exchange fin 12 and the second heat exchange fin 15 are both circular plates. The first heat exchange tube 11 passes through the first heat exchange fin 12, and the axis of the first heat exchange tube 11 is eccentrically arranged relative to the axis of the first heat exchange fin 12. The second heat exchange tube 14 passes through the second heat exchange fin 15, and the axis of the second heat exchange tube 14 is eccentrically arranged relative to the axis of the second heat exchange fin 15. In other embodiments, the heat exchange fins may also be eccentrically arranged in an elliptical, oblate, or other shape.

[0055] In this embodiment, the heat exchange rate control unit 4 includes a rotation mechanism 41 that can drive the first heat exchange tube 11 to rotate, and a constant speed transmission mechanism 42 disposed between the first heat exchange tube 11 and the second heat exchange tube 14. When the first heat exchange tube 11 rotates, the constant speed transmission mechanism 42 drives the second heat exchange tube 14 to rotate in a constant circumferential direction.

[0056] The eccentricity of the axis of the first heat exchange tube 11 relative to the axis of the first heat exchange fin 12 is symmetrically arranged, as is the eccentricity of the axis of the second heat exchange tube 14 relative to the axis of the second heat exchange fin 15. With the two heat exchange fins arranged symmetrically in their eccentric directions, the rotating mechanism 41 drives the two heat exchange tubes to rotate at a constant speed, adjusting the overlap of the axial projected areas of the heat exchange fins and achieving rapid and stable regulation of the heat exchange rate between the two heat exchange tubes.

[0057] The heat exchange speed control unit 4 drives the first heat exchange tube 11 and the second heat exchange tube 14 to rotate. When the distance between the axes of the first heat exchange fin 12 and the second heat exchange fin 15 is the smallest, the second heat exchange fin 15 is inserted between the two adjacent first heat exchange fins 12, and the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 is the largest. Through this arrangement, uniform heat exchange can be performed through each heat exchange fin, thereby improving the heat exchange efficiency; when the distance between the axes of the first heat exchange fin 12 and the second heat exchange fin 15 is the largest, the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 is the smallest or there is no axial projection overlap area.

[0058] The first heat exchange tube 11 is located directly above the second heat exchange tube 14; the heat transfer liquid level 5 of the heat transfer liquid in the heat exchange box 1 is higher than the first heat exchange tube 11, and when the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 is the smallest or has no axial projection overlap area, most of the portion of the first heat exchange fin 12 located above the first heat exchange tube 11 is exposed to the heat transfer liquid level 5.

[0059] Based on the above arrangement, the heat transfer liquid level 5 in the heat exchange box 1 is submerged above the tube body of the first heat exchange tube 11. As the tube body of the first heat exchange tube 11 rotates, the volume of the first heat exchange fin 12 with an eccentric structure immersed in the heat transfer liquid changes, thereby changing the height of the heat transfer liquid level 5, so that the volume of the first heat exchange fin 12 exposed to the liquid surface changes, which not only changes the speed at which the first heat exchange fin 12 releases heat to the heat transfer liquid, but also indirectly changes the speed at which heat is conducted from the first heat exchange tube 11 to the second heat exchange tube 14.

[0060] The constant speed transmission mechanism 42 specifically includes a driving gear and a driven gear with equal number of teeth and meshing with each other. The driving gear is connected to the first heat exchange tube 11, and the driven gear is connected to the second heat exchange tube 14; the rotating mechanism 41 includes an adjusting motor and a belt transmission assembly, the driving pulley of the belt transmission assembly is connected to the motor shaft of the adjusting motor; the driven pulley of the belt transmission assembly is connected to the first heat exchange tube 11, and the transmission belt is arranged between the driving pulley and the driven pulley, and the adjusting motor drives the first heat exchange tube 11 to rotate through the belt transmission assembly.

[0061] In this embodiment, both ends of the first heat exchange tube 11 are sealed and rotatably connected to the cooling water pipeline 21 through the first rotary sealing mechanism 13 , and both ends of the second heat exchange tube 14 are sealed and rotatably connected to the fuel pipeline 22 through the second rotary sealing mechanism 16 .

[0062] Example 2:

[0063] like Figure 4 As shown, based on the LNG internal combustion powered ship waste heat utilization device of Example 1, a fuel flow monitor 43 and a fuel temperature monitor 44 connected to the heat exchange rate control unit 4 are provided.

[0064] Specifically, a fuel flow monitor 43 is provided on the fuel pipeline 22, and the fuel flow monitor 43 is electrically connected to the heat exchange speed control unit 4;

[0065] The heat exchange rate control unit 4 is configured to control the operation of the rotating mechanism 41 according to the monitoring value of the fuel flow monitor 43;

[0066] When the fuel flow rate value monitored by the fuel flow monitor 43 increases, the heat exchange speed control unit 4 adjusts the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 to increase. When the fuel flow rate monitoring value decreases, the heat exchange speed control unit 4 drives the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 to decrease.

[0067] A fuel temperature monitor 44 is provided on the fuel pipeline 22 and is electrically connected to the heat exchange rate control unit 4;

[0068] The heat exchange rate control unit 4 is configured to control the operation of the rotating mechanism 41 according to the monitoring value of the fuel temperature monitor 44;

[0069] When the fuel temperature value monitored by the fuel temperature monitor 44 decreases, the heat exchange speed control unit 4 adjusts the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 to increase. When the fuel temperature monitoring value increases, the heat exchange speed control unit 4 drives the axial projection overlap area in the bracket of the first heat exchange fin 12 and the second heat exchange fin 15 to decrease.

[0070] Based on this embodiment, the monitor for monitoring the fuel flow and temperature performs real-time monitoring of the fuel flow and temperature, and the heat exchange rate control unit adjusts the size of the axial projection overlapping area of ​​the first heat exchange fin 12 and the second heat exchange fin 15 according to the monitored fuel flow and temperature information, thereby accurately controlling the heat exchange rate between the two heat exchange tubes, improving the LNG vaporization rate and maintaining a reasonable water temperature of the cooling water, achieving a balanced operating condition of the engine, improving operating efficiency, and reducing energy consumption.

[0071] Example 3:

[0072] On the basis of the LNG internal combustion powered ship waste heat utilization device of Example 1, an intermediate baffle and a circulation pump may be provided in the heat exchange box 1, wherein the intermediate baffle is provided at the bottom of the second heat exchange tube 14 and extends along the length direction of the second baffle, the suction end of the circulation pump is connected to the space on one side of the intermediate baffle, and the output end is connected to the space on the other side of the intermediate baffle, and the heat conduction controller is connected to the circulation pump control. When the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 increases, the circulation pump is controlled to increase the displacement. When the axial projection overlap area between the first heat exchange fin 12 and the second heat exchange fin 15 decreases, the circulation pump is controlled to reduce the displacement, so as to achieve uniform temperature of the heat transfer liquid between the first heat exchange tooth plate and the second heat exchange tooth plate, which is beneficial to the balance of heat exchange.

[0073] 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 make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A waste heat utilization device for LNG internal combustion powered ships, characterized in that: It comprises a heat exchange box (1) and a heat exchange speed control unit (4); The heat exchange box (1) is provided with a first heat exchange tube (11) and a second heat exchange tube (14) which are parallel to each other and extend in a horizontal direction. The first heat exchange tube (11) and the second heat exchange tube (14) both pass through the side walls of both ends of the heat exchange box (1) and are sealed and rotatably connected to the heat exchange box (1). The heat exchange box (1) is filled with a heat transfer fluid. The first heat exchange tube (11) is sealed and rotatably connected to the cooling water pipeline (21) of the engine (2), and a plurality of first heat exchange fins (12) are arranged in an array along the length direction of the tube surface located in the heat exchange box (1); the second heat exchange tube (14) is sealed and rotatably connected to the fuel pipeline (22) between the LNG storage tank (3) and the engine (2), and a plurality of second heat exchange fins (15) are arranged in an array along the length direction of the tube surface located in the heat exchange box (1); the plurality of first heat exchange fins (12) and the plurality of second heat exchange fins (15) are arranged in an alternating manner; The heat exchange speed control unit (4) is configured to adjust the size of the axially projected overlapping area between the first heat exchange fin (12) and the second heat exchange fin (15) by controlling the rotation of the first heat exchange tube (11) and the second heat exchange tube (14).

2. The LNG internal combustion powered ship waste heat utilization device according to claim 1, characterized in that: The first heat exchange fin (12) and the second heat exchange fin (15) are both circular plates; the first heat exchange tube (11) passes through the first heat exchange fin (12) and the axis of the first heat exchange tube (11) is eccentrically arranged relative to the axis of the first heat exchange fin (12); the second heat exchange tube (14) passes through the second heat exchange fin (15) and the axis of the second heat exchange tube (14) is eccentrically arranged relative to the axis of the second heat exchange fin (15).

3. The LNG internal combustion powered ship waste heat utilization device according to claim 2, characterized in that: The heat exchange speed control unit (4) comprises a rotating mechanism (41) capable of driving the first heat exchange tube (11) to rotate, and a constant speed transmission mechanism (42) arranged between the first heat exchange tube (11) and the second heat exchange tube (14); when the first heat exchange tube (11) rotates, the constant speed transmission mechanism (42) drives the second heat exchange tube (14) to rotate in a constant speed circumferential direction; The eccentric direction of the axis of the first heat exchange tube (11) relative to the axis of the first heat exchange fin (12) and the eccentric direction of the axis of the second heat exchange tube (14) relative to the axis of the second heat exchange fin (15) are symmetrically arranged.

4. The LNG internal combustion powered ship waste heat utilization device according to claim 3, characterized in that: The heat exchange speed control unit (4) drives the first heat exchange tube (11) and the second heat exchange tube (14) to rotate. When the distance between the axes of the first heat exchange fin (12) and the second heat exchange fin (15) is the smallest, the second heat exchange fin (15) is inserted between two adjacent first heat exchange fins (12), and the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) is the largest. When the distance between the axes of the first heat exchange fin (12) and the second heat exchange fin (15) is the largest, the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) is the smallest or there is no axial projection overlap area.

5. The LNG internal combustion powered ship waste heat utilization device according to claim 4, characterized in that: The first heat exchange tube (11) is located directly above the second heat exchange tube (14); the heat transfer liquid level (5) of the heat transfer liquid in the heat exchange box (1) is higher than the first heat exchange tube (11); and when the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) is minimum or has no axial projection overlap area, the portion of the first heat exchange fin (12) located above the first heat exchange tube (11) is mostly exposed to the heat transfer liquid level (5).

6. The LNG internal combustion powered ship waste heat utilization device according to claim 3, characterized in that: The constant speed transmission mechanism (42) comprises a driving gear and a driven gear with equal numbers of teeth and meshing with each other, the driving gear being connected to the first heat exchange tube (11), and the driven gear being connected to the second heat exchange tube (14); the rotating mechanism (41) comprises an adjusting motor and a belt transmission assembly, the driving pulley of the belt transmission assembly being connected to the motor shaft of the adjusting motor; the driven pulley of the belt transmission assembly being connected to the first heat exchange tube (11), the transmission belt being arranged between the driving pulley and the driven pulley, and the adjusting motor driving the first heat exchange tube (11) to rotate through the belt transmission assembly.

7. The LNG internal combustion powered ship waste heat utilization device according to any one of claims 1 to 6, characterized in that: A fuel flow monitor (43) is provided on the fuel pipeline (22), and the fuel flow monitor (43) is electrically connected to the heat exchange speed control unit (4); The heat exchange speed control unit (4) is configured to control the operation of the rotating mechanism (41) according to the monitoring value of the fuel flow monitor (43); When the fuel flow rate value monitored by the fuel flow rate monitor (43) increases, the heat exchange rate control unit (4) adjusts the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) to increase; when the fuel flow rate monitoring value decreases, the heat exchange rate control unit (4) drives the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) to decrease.

8. The LNG internal combustion powered ship waste heat utilization device according to any one of claims 1 to 6, characterized in that: A fuel temperature monitor (44) is provided on the fuel pipeline (22), and the fuel temperature monitor (44) is electrically connected to the heat exchange rate control unit (4); The heat exchange rate control unit (4) is configured to control the operation of the rotating mechanism (41) according to the monitoring value of the fuel temperature monitor (44); When the fuel temperature value monitored by the fuel temperature monitor (44) decreases, the heat exchange rate control unit (4) adjusts the axial projection overlap area between the first heat exchange fin (12) and the second heat exchange fin (15) to increase; when the fuel temperature monitoring value increases, the heat exchange rate control unit (4) drives the axial projection overlap area in the bracket of the first heat exchange fin (12) and the second heat exchange fin (15) to decrease.

9. The LNG internal combustion powered ship waste heat utilization device according to any one of claims 1 to 6, characterized in that: Both ends of the first heat exchange tube (11) are sealed and rotatably connected to the cooling water pipeline (21) via a first rotary sealing mechanism (13), and both ends of the second heat exchange tube (14) are sealed and rotatably connected to the fuel pipeline (22) via a second rotary sealing mechanism (16).

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