CN109458554B - A marine LNG gasification and cold recovery heat exchange system and method - Google Patents

Abstract

The invention relates to a marine LNG gasification and cold recovery heat exchange system and method. The system comprises an LNG fuel gasification unit, a circulating heat exchange network and two cold energy recovery units, wherein the LNG fuel gasification unit and the two cold energy recovery units are connected with each other through the circulating heat exchange network for heat exchange; the circulating heat exchange network is an integrated composite circulating heat exchange device formed by packaging and integrating the three parts of the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 in the same multi-channel heat exchanger. The system is compact and efficient, the circulation times of the circulation heat exchange network are adjusted by selecting proper secondary refrigerant, the evaporation LNG which is not frozen can be efficiently used for supplying ship fuel, and the gasification cold quantity of the evaporation LNG can be simultaneously recovered to meet the temperature requirements of different refrigeration application occasions on the ship.

Description

A marine LNG gasification and cold recovery heat exchange system and method

technical field

The invention relates to a marine fuel heat exchange network and related heat exchanger equipment, in particular to a marine LNG gasification and cold recovery heat exchange system and method.

Background technique

In the world's cargo transportation, ocean transportation accounts for a large proportion. For my country, it accounts for more than 90% of the total import and export. According to the statistics of the International Maritime Organization (IMO), the annual air pollution caused by the exhaust gas containing SO ₂ and NO ₂ emitted by marine diesel engines accounts for about 5-11% of the total air pollution in the world. In order to protect the environment, IMO proposed the Convention on the Control of Harmful Emissions from Marine Diesel Engines, setting the emission limits of sulfur oxides, nitrogen oxides and other pollutants from ships, and stipulating that the sulfur content limit of fuel oil used by ships will be reduced to 0.5%. As a clean energy, liquefied natural gas (LNG) can reduce the emission of a large amount of particulate matter, sulfur oxides (SO _x ) and nitrogen oxides (NO _x ) when compared with traditional diesel fuel, and at the same Its greenhouse gas emissions under thermal mass conditions are only about 40% of diesel fuel. Therefore, LNG is considered to be an attractive fuel alternative on ocean-going ships (including yachts, barges, container ships, etc.), and more and more ships will use LNG or hybrid (diesel/LNG) as fuel . LNG is a cryogenic liquid fuel stored at -162°C under normal pressure. It must be evaporated and superheated to ambient temperature before entering the ship's main engine. During this process, LNG releases about 860kJ/kg of cold energy, which can be used for refrigeration, air conditioning, seawater desalination, power generation and other purposes on ships, which not only saves related refrigeration power consumption equipment, but also reduces power consumption , It also avoids the low-temperature hazard caused by the direct use of seawater gasification LNG to the marine environment and freezing of the hull.

However, at present, most LNG liquefaction methods do not have a self-contained cold energy recovery function, and common devices include open, submerged, and intermediate liquid vaporizers. The former two use air, seawater or industrial heat sources to gasify LNG. The main disadvantages are energy waste, residual chemical components and low-temperature seawater discharges that have negative effects on marine organisms. Although the intermediate liquid vaporizer uses brine as the intermediate heat exchange product, the huge difference in vaporization temperature often leads to low efficiency of this type of vaporizer, which cannot meet industrial needs. Especially in LNG-powered ships, improper gasification devices cannot meet the temperature requirements of marine natural gas fuel, and cannot guarantee the normal operation of the ship's main engine engine. In severe cases, the pipeline may even freeze and cause low-temperature damage to the ship.

Contents of the invention

In order to solve the above-mentioned problems, the present invention discloses a cold recovery heat exchange system and method for LNG-powered ships. Relevant refrigeration energy consumption, while also taking into account the characteristics of no freezing and compact structure, to meet the various cooling temperature requirements of LNG ships.

In order to achieve the above object, the present invention adopts the following technical solutions to achieve:

A cold energy recovery heat exchange system for LNG-powered ships, which consists of an LNG fuel gasification unit, a circulating heat exchange network, and two cold energy recovery units. The LNG fuel gasification unit and the two cold energy recovery units are connected through the heat exchange network hot, where:

The LNG fuel gasification unit includes an LNG storage tank 1, a ship main engine 5 and corresponding connecting pipelines; the LNG storage tank 1 communicates with the inlet of the circulation heat exchange network through a low-temperature pipeline, and the ship main engine 5 communicates with the circulation heat exchange network through a fuel gas pipeline. The outlet of the heat exchange network is connected to receive gasified LNG fuel;

The cyclic heat exchange network includes a multi-channel liquid evaporator 2, a multi-channel steam superheater 3, a multi-channel supercooled steam regenerator 4 and corresponding connecting pipelines; the multi-channel liquid evaporator 2, multi-channel The channel steam superheater 3 and the multi-channel supercooled steam regenerator 4 are both multi-stream heat exchangers, wherein the multi-channel liquid evaporator 2 is connected to the LNG storage tank 1 to receive the liquid LNG fuel from the LNG storage tank. The channel liquid evaporator 2 is connected with the multi-channel steam superheater 3 to form the LNG vaporization and gasification circulation circuit, and the multi-channel liquid evaporator 2 is connected with the multi-channel supercooled steam regenerator 4 to form the LNG steam reheating circuit. At the same time, the multi-channel The steam superheater 3 and the multi-channel subcooled steam regenerator 4 respectively receive the first brine Z1 and the second brine Z2 of the cooling recovery unit as heat sources, and enter the LNG evaporation gasification cycle and the LNG steam reheat cycle LNG circuit, heat exchange with LNG saturated steam and subcooled steam, after heat exchange, the first brine Z1 and the second brine Z2 in the multi-channel steam superheater 3 and multi-channel subcooled steam regenerator 4 are subcooled The liquid flows back from the outlet of the multi-channel steam superheater 3 and the outlet of the multi-channel subcooled steam regenerator 4 to the respective corresponding cooling recovery units, and the natural gas that reaches the specified temperature after the multi-channel circulation heat exchange is vaporized from the steam regenerator 4 The exit enters the main engine 5 of the ship;

The two cold recovery units respectively include the second cold utilization device 6, the first cold utilization device 7 and corresponding connecting pipelines; the second cold utilization device 6 and the first cold utilization The device 7 uses the second brine Z2 and the first brine Z1 as refrigerants to provide cold energy, and the high-temperature brine at its outlet enters the multi-channel supercooled steam regenerator 4 of the circulating heat exchange network through the pipeline and the multi-channel steam superheater 3 to recover the vaporized cooling capacity of LNG, and the first brine Z1 and the second brine Z2 flowing out of the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 after heat exchange The cold liquid flows back through the pipelines to the corresponding first cooling capacity utilization device 7 and the second cooling capacity utilization device 6, and after releasing the cooling capacity in the cooling capacity utilization device to refrigerate, it continues to become a high-temperature brine and enters the circulating heat exchange network. The second cooling capacity utilization device 6 and the first cooling capacity utilization device 7 are various types of marine refrigeration devices such as air conditioners, refrigerators or seawater desalination devices.

Further, the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 of the heat exchange network are plate-fin, plate, wound tube or shell-and-tube multi-strand flow heat exchanger.

Further, the said cycle heat exchange network is formed by packaging and integrating multi-channel liquid evaporator 2, multi-channel steam superheater 3 and multi-channel subcooled steam regenerator 4 into the same multi-channel heat exchanger One-piece compound circulation heat exchange device, easy to install.

Further, the heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 all adopt fin structures. The heat channels are preferably straight fins or open-hole fins, the heat exchange channels for LNG saturated steam and superheated and subcooled steam adopt zigzag or corrugated fins, and the first refrigerant Z1 and the second refrigerant Z2 The heat exchange channel should use straight or corrugated fins.

Further, the heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are arranged in a single-layer, double-layer or combined manner of hot and cold fluids. , that is, a layer of cold (or hot) channels is sandwiched between two adjacent layers of hot (or cold) channels, and stacked repeatedly.

Further, the multi-channel liquid evaporator 2 is a single multi-stream plate-fin heat exchanger, and the multi-channel steam superheater 3 and the multi-channel supercooled steam regenerator 4 are combined into a heat exchanger with an integrated structure. Industrial plate-fin heat exchanger fins are used in the hot channel, and vacuum heat insulation layers K are respectively set on both sides of the multi-channel liquid evaporator 2, multi-channel steam superheater 3 and multi-channel supercooled steam regenerator 4 to insulate Heat transfer between the heat exchanger and the outside world and between heat exchangers.

A method for recovering and exchanging cold energy for LNG-powered ships, characterized in that the steps are as follows:

(1) Evaporation and gasification of LNG liquid fuel

The liquid LNG fuel in the LNG storage tank 1 is transported to the multi-channel liquid evaporator 2 of the circulating heat exchange network through a low-temperature pipeline. The recirculated LNG superheated steam after heat exchange in the regenerator 4 is evaporated and gasified as a hot fluid, thereby being converted into LNG saturated steam;

(2) LNG steam cycle heat recovery

LNG saturated steam enters the multi-channel steam superheater 3 and exchanges heat with the first refrigerant Z1 to become the first reflux superheated steam, returns to the multi-channel liquid evaporator 2 to exchange heat with the initial LNG liquid to become supercooled steam, and finally enters In the multi-channel supercooled steam regenerator 4, the cold energy is released to the second refrigerant Z2, thereby completing the first heat recovery cycle; The LNG superheated steam flows back into the multi-channel liquid evaporator 2 again, as the start of the next reheating cycle, after vaporizing the initial LNG liquid, it flows back into the multi-channel supercooled steam regenerator 4 to continue reheating;

(3) LNG is gasified and supplied to the main engine

According to the fuel supply requirements of the ship, after the LNG liquid passes through n cycles in the set cycle heat exchange network, the number of cycles is n≥2, and finally it is output in the form of natural gas at the specified temperature at the outlet of the multi-channel supercooled steam regenerator 4 , and transported to the main engine 5 of the ship through the fuel gas pipeline for combustion, thereby completing the gasification cycle of the LNG fuel;

In the gasification cycle of the above-mentioned LNG fuel, the LNG liquid fuel is gasified into natural gas at a specified temperature through the circulating heat exchange network and delivered to the main engine of the ship. The first brine Z1 is absorbed, and the other part is absorbed by the second brine Z2 in the multi-channel supercooled steam regenerator 4 .

(4) Cooling recovery cycle

The first brine Z1 used by the first cold utilization device 7 passes into the multi-channel steam superheater 3 to absorb the cold of LNG saturated steam, and then returns to the first cold utilization device 7 to release cold refrigeration. The measured first refrigerant Z1 continues to enter the multi-channel steam superheater 3, thereby realizing a recovery cycle of LNG vaporization cooling capacity;

The second brine Z2 used by the second cold utilization device 6 passes into the multi-channel subcooled steam regenerator 4 to absorb the cold of the LNG supercooled steam, and then returns to the second cold utilization device 6 to release the cold Refrigeration, the second brine Z2 after releasing the cooling capacity continues to enter the multi-channel subcooled steam regenerator 4, thereby realizing the secondary recovery cycle of the cooling capacity of LNG vaporization.

Further, the first brine Z1 and the second brine Z2 can be the same or different, and should be selected according to different cycle times and required temperature conditions.

Further, the first brine Z1 and the second brine Z2 use ethylene glycol aqueous solution and/or propylene glycol aqueous solution, and the type and flow rate of the brine should be determined according to the LNG supply, that is: in multi-channel steam The first refrigerant Z1 in the superheater 3 should ensure that the LNG gas returned to the multi-channel liquid evaporator 2 for the first time is in a superheated state. The superheated state refers to the continuous heating after the LNG is completely evaporated into gas under the working environment pressure. State; the freezing point of the second brine Z2 in the multi-channel subcooled steam regenerator 4 must be higher than the temperature of the LNG supercooled gas, and the freezing point refers to the triple point temperature at which the refrigerant freezes under the pressure of the working environment .

Furthermore, according to the LNG flow rate required by the process, the design parameters of the circulating heat exchange network are determined by the specific heat, flow rate, number of cycles of the brine and the outlet temperature that the brine needs to reach; customized according to different flow and temperature requirements Different design parameters have greater flexibility and wide applicability. The calculation formula of the cycle heat exchange number n of the cycle heat exchange network is as follows:

In the formula: m is the mass flow rate of LNG, r is the latent heat of vaporization of LNG, c _p is the specific heat capacity of LNG, t _LNG-0 and t _LNG-12 are the temperature of LNG liquid at the inlet and outlet of the circulation heat exchange network, respectively, t _LNG-3 is the temperature of the LNG subcooled steam entering the multi-channel subcooled steam regenerator 4 in the first recovery cycle, t _Z1-1 and t _Z1-2 are the first brine at the inlet and outlet of the multi-channel steam superheater 3 respectively The temperature of Z1, t _Z2-1 and t _Z2-2 are the temperatures of the second brine Z2 at the inlet and outlet of the multi-channel subcooled steam regenerator 4, respectively.

In the case of a given LNG supply flow rate determination, the number of cycles n decreases with the temperature t _Z1-2 of the first brine Z1 at the outlet of the multi-channel steam superheater 3 and the temperature at the inlet of the multi-channel subcooled steam regenerator 4 The temperature t _Z2-1 of the second brine refrigerant Z2 decreases and increases with the decrease of the inlet temperature t _LNG-0 of the cold fluid in the multi-channel liquid evaporator 2 . By adjusting the number of cycles n of the cyclic heat exchange network, it is possible to achieve different temperatures of the brine that meet the needs of various users.

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

1. Since the LNG liquid exchanges heat with its own superheated steam many times in the multi-channel liquid evaporator, its phase change latent heat is all transferred to its own superheated steam, thus avoiding the direct contact between the low-temperature liquid and the refrigerant in the traditional heat exchange equipment. Heat transfer between them, no freezing phenomenon;

2. The unique design of the heat exchange network of the present invention lies in that the LNG liquid does not directly exchange heat with the refrigerant in the evaporator, effectively avoiding the risk of freezing of the refrigerant during direct heat exchange. At the same time, through the heat transfer between the LNG liquid and its own superheated steam, and the heat exchange between the first brine and LNG saturated steam, the second brine and LNG supercooled steam, different cycles have different The temperature gradient is more conducive to improving the energy transfer efficiency of the circulating heat exchange network; at the same time, there is a large heat transfer temperature difference between the LNG liquid and its own superheated steam in the multi-channel liquid evaporator, which is conducive to the complete gasification of the LNG liquid; In the multi-channel supercooled steam regenerator, the refrigerant and the natural gas supercooled steam are heat-exchanged with a small temperature difference, which can obtain relatively high cold energy recovery efficiency;

3. The multi-channel steam superheater added in the cyclic heat exchange network ensures the superheated state of the LNG steam, and at the same time adds a variety of degrees of freedom to the cyclic heat exchange network to adapt to the refrigerant products that produce various temperatures;

4. By selecting an appropriate refrigerant and adjusting the number of cycles of the heat exchange network, a variety of different refrigerant temperatures can be obtained under process specification conditions to meet the needs of different occasions in the ship;

5. In the case of a given number of heat exchange system cycles, the temperature of the intermediate fluid in the heat exchange system can also be controlled by changing any parameter of the process specification, for example: by adjusting the flow rate of the refrigerant, different refrigerant temperatures and natural gas outlets can be obtained temperature and flow range etc. This makes the invention widely adaptable in LNG powered ships.

To sum up, the system of the present invention is compact and efficient, not only can efficiently evaporate LNG without freezing for ship fuel supply, but also can recover its vaporized cooling capacity at the same time to meet the temperature requirements of different refrigeration applications on ships. The system of the present invention and The method is suitable for popularization and use in the field of marine LNG.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Figure 1 is a schematic diagram of the structure and principle of a marine LNG gasification and cooling recovery heat exchange system in Embodiment 1 of the present invention;

Fig. 2 is a schematic diagram of the device structure of the cyclic heat exchange network in Fig. 1;

Fig. 3 is a schematic diagram of the arrangement of the heat exchange channels of the multi-channel liquid evaporator of the cyclic heat exchange network in Fig. 1;

Fig. 4 is a schematic diagram of the arrangement of the heat exchange channels of the multi-channel steam superheater and the multi-channel subcooled steam regenerator of the integrated structure of the cyclic heat exchange network in Fig. 1;

In the figure: 1. LNG liquid storage tank, 2. Multi-channel liquid evaporator, 3. Multi-channel steam superheater, 4. Multi-channel subcooled steam regenerator, 5. Ship main engine, 6. Second cooling utilization device , 7 The first cooling utilization device, Z1, the first brine, Z2, the second brine, K, the vacuum insulation layer.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and examples.

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 It is only some embodiments of the present invention, but not all embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way taken as limiting the invention, its application or uses. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

It should be noted that the terminology used here is only for describing specific embodiments, and is not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly dictates otherwise, the singular is intended to include the plural, and it should also be understood that when the terms "comprising" and/or "comprising" are used in this specification, they mean There are features, steps, operations, means, components and/or combinations thereof.

The relative arrangements of components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. At the same time, it should be clear that, for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the authorized description. In all examples shown and discussed herein, any specific values should be construed as exemplary only, and not as limitations. Therefore, other examples of the exemplary embodiment may have different values. It should be noted that like numerals and letters denote like items in the following figures, therefore, once an item is defined in one figure, it does not require further discussion in subsequent figures.

In the description of the present invention, it should be understood that orientation words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" etc. indicate the orientation Or positional relationship is generally based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description. In the absence of a contrary statement, these orientation words do not indicate or imply the device or element referred to. It must have a specific orientation or be constructed and operated in a specific orientation, so it should not be construed as limiting the scope of the present invention: the orientation words "inside and outside" refer to inside and outside relative to the outline of each part itself.

For the convenience of description, spatially relative terms may be used here, such as "on ...", "over ...", "on the surface of ...", "above", etc., to describe The spatial positional relationship between one device or feature shown and other devices or features. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, devices described as "above" or "above" other devices or configurations would then be oriented "beneath" or "above" the other devices or configurations. its underlying device or construction". Thus, the exemplary term "above" can encompass both an orientation of "above" and "beneath". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptions used herein interpreted accordingly.

In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing corresponding components. To limit the protection scope of the present invention.

Example 1

As shown in Figure 1, an LNG-powered marine cold energy recovery heat exchange system consists of an LNG fuel gasification unit, a circulating heat exchange network, and two cold energy recovery units. The LNG fuel gasification unit and the two cold energy recovery units pass through The cyclic heat exchange network connects the heat exchange, where:

The LNG fuel gasification unit includes an LNG storage tank 1, a ship main engine 5 and corresponding connecting pipelines; the LNG storage tank 1 communicates with the inlet of the circulation heat exchange network through a low-temperature pipeline, and the ship main engine 5 communicates with the circulation heat exchange network through a fuel gas pipeline. The outlet of the heat exchange network is connected to receive gasified LNG fuel;

The cyclic heat exchange network includes a multi-channel liquid evaporator 2, a multi-channel steam superheater 3, a multi-channel supercooled steam regenerator 4 and corresponding connecting pipelines; the multi-channel liquid evaporator 2, multi-channel The channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are both multi-stream heat exchangers, wherein the multi-channel liquid evaporator 2 is connected to the LNG storage tank 1 and receives liquid LNG-0 fuel from the LNG storage tank , the multi-channel liquid evaporator 2 communicates with the multi-channel steam superheater 3 to form an LNG vaporization and gasification circulation loop, and the multi-channel liquid evaporator 2 communicates with the multi-channel supercooled steam regenerator 4 to form an LNG steam reheating circulation loop. The multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 respectively receive the first brine Z1 and the second brine Z2 of the cooling recovery unit as heat sources, and enter the LNG evaporation and gasification circulation loop and the LNG steam return loop. Thermal circulation circuit, heat exchange with LNG saturated steam and supercooled steam, first refrigerant Z1 and second refrigerant Z2 in multi-channel steam superheater 3 and multi-channel supercooled steam regenerator 4 after heat exchange The subcooled liquid flows back from the multi-channel steam superheater 3 outlet and the multi-channel subcooled steam regenerator 4 outlet respectively to their corresponding cooling recovery units, and the natural gas NG (LNG-12) that reaches the specified temperature after heat exchange and vaporization is circulated. Enter the main engine 5 of the ship from the outlet of the steam regenerator 4;

The two cold recovery units respectively include the second cold utilization device 6, the first cold utilization device 7 and corresponding connecting pipelines; the second cold utilization device 6 and the first cold utilization The device 7 is various types of marine refrigeration devices such as air conditioners, refrigerators or seawater desalination devices, and uses the second brine Z2 and the first brine Z1 as refrigerants to provide cold energy, which is released in the first cold utilization device 7 The cooled high-temperature brine Z1-1 enters the multi-channel steam superheater 3 of the circulating heat exchange network through pipelines to recover part of the vaporized cooling capacity of LNG, and releases the cooling capacity in the second cooling capacity utilization device 6. The high-temperature refrigerant Z2-1 enters the multi-channel subcooled steam regenerator 4 of the circulating heat exchange network through the pipeline to recover the remaining LNG gasification cooling capacity, and flows out of the multi-channel steam superheater 3 and multi-channel subcooled after heat exchange. The supercooled liquid of the first brine Z1-2 and the second brine Z2-2 of the steam regenerator 4 flows back to the corresponding first cooling capacity utilization device 7 and the second cooling capacity utilization device 6 respectively through pipelines, After releasing the cooling capacity in the cooling utilization device for refrigeration, it continues to become a high-temperature brine and enters the circulating heat exchange network.

The multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 of the circulating heat exchange network are plate-fin, plate, wound tube or shell-and-tube multi-stream heat exchangers. As shown in Figure 2, the cyclic heat exchange network is formed by packaging and integrating multi-channel liquid evaporator 2, multi-channel steam superheater 3 and multi-channel subcooled steam regenerator 4 into the same multi-channel heat exchanger One-piece compound circulation heat exchange device, easy to install. The multiple heat exchange channels involved in LNG liquid, saturated steam, superheated and subcooled steam, and brine are distributed to the circulation heat exchange network through deflector bundles and heads.

The heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 all adopt a fin structure. Considering the high viscosity of the LNG liquid, the heat exchange channels are preferably straight fins. The heat exchange channels of LNG saturated steam and superheated and subcooled steam adopt zigzag or corrugated fins, while the heat exchange channels of the first refrigerant Z1 and the second refrigerant Z2 should adopt flat fins. Straight or corrugated fins.

As shown in Figure 3, the multi-channel liquid evaporator 2 is a single multi-stream plate-fin heat exchanger, the fins of the industrial plate-fin heat exchanger are used in the heat exchange channel, and the vacuum insulation layer K is arranged on both sides of the heat exchanger. , used to isolate the heat transfer between the heat exchanger and the outside world. The arrangement of the heat exchange channels in the multi-channel liquid evaporator 2 adopts a single-layer, double-layer or combined configuration of cold and hot fluids, that is, a layer of cold (or hot) is sandwiched between two adjacent layers of hot (or cold) channels. ) channel, and repeat the stack.

As shown in Figure 4, the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are combined into a heat exchanger with an integrated structure, and both sides of the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are Vacuum insulation layers K are respectively provided to isolate the heat exchanger from the outside world and heat transfer between the heat exchangers. The heat exchange channels in the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are arranged in a single-layer, double-layer or combined manner of hot and cold fluids, that is, the hot (or cold) A layer of cold (or hot) channels is sandwiched between channels and stacked repeatedly.

A method for recovering and exchanging cold energy for LNG-powered ships, characterized in that the steps are as follows:

(1) Evaporation and gasification of LNG liquid fuel

The liquid LNG-0 fuel in the LNG storage tank 1 is transported to the multi-channel liquid evaporator 2 of the circulating heat exchange network through a low-temperature pipeline. The LNG superheated steam (LNG-2, LNG-4, LNG-6, LNG-8, LNG-10) returned after heat exchange in channel subcooled steam regenerator 4 is used as hot fluid for evaporation and gasification, thus converting into saturated LNG Steam LNG-1;

(2) LNG steam cycle heat recovery

Saturated steam LNG-1 enters the multi-channel steam superheater 3 to exchange heat with the first refrigerant Z1 and then becomes the first refluxed superheated steam LNG-2, and returns to the multi-channel liquid evaporator 2 to exchange heat with the initial LNG-0 liquid Become the supercooled steam LNG-3, and finally enter the multi-channel supercooled steam regenerator 4 to release the cold energy to the second refrigerant Z2, thereby completing the first heat recovery cycle; in the multi-channel supercooled steam regenerator 4 After the internal heat exchange, the LNG superheated steam (LNG-4, LNG-6, LNG-8, LNG-10) that has not reached the specified temperature flows back into the multi-channel liquid evaporator 2 again, as the start of the next heat recovery cycle, After vaporizing the initial LNG-0 liquid, it flows back to the multi-channel supercooled steam regenerator 4 to continue reheating;

(3) LNG is gasified and supplied to the main engine

According to the fuel supply requirements of ships, after the LNG liquid passes through n cycles in the set cycle heat exchange network, the number of cycles n≥2, n=5 in this embodiment, and finally at the outlet of the multi-channel supercooled steam regenerator 4 LNG-12 is output in the form of natural gas NG at a specified temperature, and is transported to the main engine 5 of the ship through the fuel gas pipeline for combustion, thereby completing the gasification cycle of LNG fuel;

In the gasification cycle of the above LNG fuel, the LNG-0 liquid fuel is gasified into natural gas NG at a specified temperature through the circulating heat exchange network and delivered to the main engine of the ship. The first brine Z1 in 3 is absorbed, and the other part is absorbed by the second brine Z2 in the multi-channel subcooled steam regenerator 4 .

(4) Cooling recovery cycle

The first brine Z1-1 used by the first cooling capacity utilization device 7 passes into the multi-channel steam superheater 3 to absorb the saturated steam LNG-1, and the cooling capacity of LNG-1 becomes Z1-2, and returns to the first cooling capacity utilization device 7 Release the cooling capacity to refrigerate. After releasing the cooling capacity, it becomes Z1-1 and continues to enter the multi-channel steam superheater 3, so as to realize the primary recovery cycle of LNG vaporization cooling capacity;

The second brine Z2-1 used by the second cooling utilization device 6 is passed into the multi-channel supercooled steam regenerator 4 to absorb LNG supercooled steam (LNG-3, LNG-5, LNG-7, LNG- 9. The cooling capacity of LNG-11) becomes Z2-2, and returns to the second cooling utilization device 6 to release the cooling capacity for refrigeration. After releasing the cooling capacity, it becomes Z2-1 again and continues to enter the multi-channel supercooled steam regenerator 4 , so as to realize the secondary recovery cycle of LNG gasification cooling capacity;

The first refrigerant Z1 and the second refrigerant Z2 respectively pass into different first cold energy utilization devices 7 and second cold energy utilization devices 6 after absorbing the latent heat of evaporation of LNG and the latent heat of the temperature difference with the environment. The capacity utilization device 7 and the second cooling capacity utilization device 6 are various types of marine refrigeration devices such as air conditioners, refrigerators or seawater desalination devices, and the first refrigerant Z1 and the second refrigerant Z2 release the cold capacity and return to the heat exchange network Absorb the cold energy released during the LNG evaporation process again to complete the cold energy recovery cycle.

The first brine Z1 and the second brine Z2 use ethylene glycol aqueous solution and/or propylene glycol aqueous solution. The first brine Z1 and the second brine Z2 can be the same or different, and should be selected according to different cycle times and required temperature conditions.

The types and flow rates of the first brine Z1 and the second brine Z2 should be determined according to the LNG supply, that is, in the multi-channel steam superheater 3, the first brine Z1 should ensure that the first return The LNG-2 gas in the channel liquid evaporator 2 is in a superheated state, and the superheated state refers to the state where the LNG is completely evaporated into a gas under the working environment pressure and continues to be heated; in the multi-channel subcooled steam regenerator 4, the first The freezing point of the secondary refrigerant Z2 must be higher than the temperature of LNG supercooled steam (LNG-3, LNG-5, LNG-7, LNG-9, LNG-11), the freezing point refers to the refrigerant under the pressure of the working environment The triple point temperature of solidification.

According to the LNG flow rate required by the process, the design parameters of the circulating heat exchange network are determined by the specific heat, flow rate, number of cycles of the brine and the outlet temperature that the brine needs to achieve; different designs can be customized according to different flow and temperature requirements parameters, with great flexibility and wide applicability.

The calculation formula of the cycle heat exchange number n of the cycle heat exchange network is as follows:

In the formula: m is the mass flow rate of LNG, r is the latent heat of vaporization of LNG, _cp is the specific heat capacity of LNG, t is the temperature of each fluid in Figure 1, and the fluid types corresponding to each temperature are shown in the corresponding subscripts, namely: LNG- 12. The temperature of LNG-0, LNG-3, Z1-2, Z1-1, Z2-2, Z2-1 fluid.

In the case of a given LNG supply flow rate determination, the number of cycles n decreases with the temperature t _Z1-2 of the first brine Z1 at the outlet of the multi-channel steam superheater 3 and the temperature at the inlet of the multi-channel subcooled steam regenerator 4 The temperature t _Z2-1 of the second brine refrigerant Z2 decreases and increases with the decrease of the inlet temperature t _LNG-0 of the cold fluid in the multi-channel liquid evaporator 2 . By adjusting the number of cycles n of the cyclic heat exchange network, it is possible to achieve different temperatures of the brine that meet the needs of various users.

As shown in Figure 3, in this embodiment, the number of cycles n of the cyclic heat exchange network is set to be 5 times, and the multi-channel liquid evaporator 2 is a multi-channel plate-fin heat exchanger, and its heat exchange channels are cold and hot fluids " In a sandwich arrangement, the LNG liquid channel is designed to have 5 layers of channels, and the LNG superheated steam for each cycle is set to 2 layers of channels, and circulates 5 times, a total of 10 layers of channels. In the multi-channel liquid evaporator 2, heat exchange is performed for one cold fluid LNG-0 and five hot fluids (LNG-2, LNG-4, LNG-6, LNG-8, LNG-10). Among them, the LNG liquid LNG-0 is distributed into 5 layers of heat exchange channels, and the fins of each layer of channels are perforated fins with a fin height of 6.5mm, a fin width of 1.4mm, and a fin thickness of 0.2mm. The LNG liquid in the 5 layers of channels They are all converged to the corresponding head by the deflector, and the model of the deflector is 65D4205; LNG superheated steam LNG-2, LNG-4, LNG-6, LNG-8, LNG-10 are 5 heat exchange loops, Each loop is divided into 2 layers, a total of 10 layers of heat exchange channels, each layer of fins are serrated fins, fin height 9.5mm, fin width 1.4mm, fin thickness 0.2mm, sawtooth pitch 3mm, 10 layers of channels The LNG vapor inside is converged to the corresponding head by the deflector, and the model of the deflector is 95D4205. In addition, in order to reduce the size of the heat exchanger and facilitate channel arrangement and distribution, the thermal fluid heat exchange layer in this embodiment is designed as a symmetrical structure with a ratio of 3:2, that is, the 6-layer channels include LNG-2, LNG-6 and LNG -10, 4-tier access including LNG-4 and LNG-8. For proper heat preservation, a vacuum heat insulation layer K is provided on both sides of the outermost layer of the heat exchange channel. Each channel above is composed of a head, a seal, a side plate, a deflector and a heat exchange fin. The five heat exchange circuits LNG-2, LNG-4, LNG-6, LNG-8, and LNG-10 in the multi-channel liquid evaporator 2 are heat exchanged sequentially instead of simultaneously, which can maximize the cooling energy recycling efficiency.

The multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 are combined into a heat exchanger with an integrated structure, as shown in Figure 4, the heat exchanger in the multi-channel steam superheater 3 and the multi-channel subcooled steam regenerator 4 The hot aisles are arranged as a "sandwich" of hot and cold fluids. In the multi-channel steam superheater 3, the first brine Z1 is distributed into three layers of channels, and the LNG saturated steam is distributed into two layers of channels, which are arranged alternately. In the multi-channel subcooled steam regenerator 4, the LNG subcooled steam for each cycle is set to 2 layers of passages and 5 cycles, with a total of 10 layers of channels; the second brine Z2 is set to 11 layers of channels , arranged at intervals and wrapping each layer of supercooled steam channels.

In the multi-channel supercooled steam regenerator 4, one hot fluid carrier refrigerant Z2-1 and five cold fluids (LNG-3, LNG-5, LNG-7, LNG-9, LNG-11) are exchanged hot. Among them, the brine Z2-1 is distributed into 11 layers of heat exchange channels, and the fins of each layer of channels are straight fins with a fin height of 9.5 mm, a fin width of 2 mm, and a fin thickness of 0.3 mm. The refrigerant liquid is converged by the deflector to the corresponding head and discharged. The model of the deflector is 95DD4205; LNG supercooled steam LNG-3, LNG-5, LNG-7, LNG-9, LNG-11 is divided into 5 Heat exchange loop, each loop is divided into 2 layers, a total of 10 layers of heat exchange channels, each layer of fins are sawtooth fins, fin height 9.5mm, fin width 1.4mm, fin thickness 0.2mm, sawtooth pitch 3mm, the LNG vapor in the 10-layer channel is converged to the corresponding head to be discharged by the guide vane, and the guide vane model is 95D4205. In addition, in order to reduce the size of the heat exchanger and facilitate the arrangement and distribution of heat exchange channels, the thermal fluid heat exchange layer is designed as a symmetrical structure with a ratio of 3:2, that is, the 6-layer channels include LNG-3, LNG-5 and LNG-7, 4 Layer channels include LNG-9 and LNG-11. For proper heat preservation, a vacuum heat insulation layer K is provided on both sides of the outermost layer of the heat exchange channel. Each channel above is composed of a head, a seal, a side plate, a deflector and a heat exchange fin. The five heat exchange loops LNG-3, LNG-5, LNG-7, LNG-9, and LNG-11 in the multi-channel supercooled steam regenerator 4 are also heat exchanged sequentially rather than simultaneously to further improve Cold energy recovery efficiency.

In addition, in order to reduce the structural size, the multi-channel steam superheater 3 is integrated inside the multi-channel subcooled steam regenerator 4 and separated by two vacuum insulation layers K. The multi-channel steam superheater 3 is provided with 3 layers of first brine heat exchange channels and 2 layers of LNG saturated steam heat exchange channels for heat exchange between the hot fluid Z1-1 and the cold fluid LNG-1. The structure is the same as the above structure and will not be repeated. Each channel above is composed of a head, a seal, a side plate, a deflector and a heat exchange fin.

According to the schematic diagram shown in Figure 1, the LNG-0 liquid enters the circulating heat exchange network from the LNG storage tank 1 after the flow rate of the fuel pump is adjusted. LNG-0 passes through the multi-channel liquid evaporator 2, transfers the latent heat of phase change to its own superheated steam LNG-2, LNG-4, LNG-6, ..., LNG-2n, and then becomes saturated LNG steam LNG-1 into the multi-channel The channel steam superheater 3 exchanges heat with the first refrigerant Z1, and is heated by the refrigerant Z1 to become superheated LNG vapor LNG-2; LNG-2 returns to the multi-channel liquid evaporator 2 as the first heat flow to heat the LNG initially Low-temperature liquid LNG-0; after exchanging heat with LNG-0, the superheated steam LNG-2 becomes supercooled steam LNG-3 and continues to flow into the multi-channel supercooled steam regenerator 4; in the multi-channel supercooled steam regenerator 4 , the second refrigerant Z2 circulates and heats supercooled steam LNG-3, LNG-5, LNG-7, ..., LNG-2n+1; LNG-3 heated by the refrigerant Z2 becomes superheated steam LNG-4 , and return to the multi-channel liquid evaporator 2 to complete a cycle in the cyclic heat exchange network; LNG-4 becomes the second heat flow and returns to the multi-channel liquid evaporator 2 to continue heating the initial low-temperature liquid LNG-0 of LNG, thus starting the next cycle cycle. Following the above method, after the LNG liquid releases the latent heat of phase change to its own superheated steam, it releases cold energy to the first refrigerant Z1 again through the multi-channel steam superheater 3, and finally continues to release cold energy in the multi-channel supercooled steam regenerator 4. Can give the second refrigerant Z2. After the above cycle is carried out n times in the multi-channel liquid evaporator 2 and the multi-channel subcooled steam regenerator 4, the LNG-2n+2 at the outlet of the multi-channel subcooled steam regenerator 4, as the gasification product of LNG, reaches the specified After the temperature is discharged, it enters the main engine of the ship and is used as power fuel.

Secondly, in the circulating heat exchange network, the first brine Z1 first absorbs the cooling capacity of LNG-1 vapor in the saturated state in the superheater, making it become superheated vapor LNG-2 and returns to the multi-channel liquid evaporator 2 Heating the LNG initial low-temperature liquid LNG-0; then, the second refrigerant Z2 circulates in the multi-channel subcooled steam regenerator 4 to absorb the LNG subcooled steam LNG-3 and LNG-5 from the multi-channel liquid evaporator 2 , LNG-7, ..., the cooling capacity of LNG-2n+1, after repeated cycles n times, the entire cooling capacity is obtained.

The cooling capacity of LNG is finally recovered by the first brine Z1 in the multi-channel steam superheater 3 and the second brine Z2 in the multi-channel subcooled steam regenerator 4 under different temperature gradient conditions: the first brine Agent Z1 is used for recovery of low-temperature cooling capacity, and its outlet temperature can be as low as -30°C according to the LNG flow rate, and the recovered cooling capacity can be used by ship refrigeration equipment; the second secondary refrigerant is used for high-temperature cooling capacity recovery, and its outlet temperature It can reach about 10°C, and the recovered cooling energy can be used by marine air conditioning and other systems. During the heat exchange process, the LNG steam and the refrigerant have a temperature gradient of 10°C to 30°C. In the above-mentioned cyclic heat exchange network, multiple cycles are used for temperature recovery, the inlet of the cyclic heat exchange network is LNG liquid, and the outlet of the cyclic heat exchange network is natural gas output.

The present invention proposes a marine LNG gasification and cooling capacity recovery heat exchange system and method. The LNG liquid in the ship fuel storage tank is efficiently gasified through the circulating heat exchange network and the cooling capacity is recovered by using the refrigerant at the same time. Not only can it meet the natural gas fuel supply demand of the ship's main engine, but it can also efficiently recover the cold energy released during the gasification process and supply the cold demand of ships' air conditioners, food cold storage and seawater desalination devices at different temperatures. The invention makes the cold and hot fluids conduct heat exchange with a large temperature difference to ensure complete gasification through the ingenious design of the LNG gasification, and makes the cold and hot fluids conduct heat exchange with a small temperature difference to improve the energy recovery efficiency when the cold energy is recovered, and through a unique The design of circulating self-evaporating and circulating refrigerant to recover cold energy effectively avoids the problems of freezing and low efficiency of traditional vaporizers.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (5)

1. The utility model provides a heat transfer system is retrieved to marine cold volume of LNG power, its characterized in that includes LNG fuel gasification unit, circulation heat transfer network and two cold volume recovery units, and LNG fuel gasification unit and two cold volume recovery units pass through circulation heat transfer network connection heat transfer, wherein:

the LNG fuel gasification unit comprises an LNG storage tank (1), a ship host (5) and corresponding connecting pipelines; the LNG storage tank (1) is communicated with the inlet of the circulating heat exchange network through a low-temperature pipeline, and the ship host (5) is communicated with the outlet of the circulating heat exchange network through a fuel gas pipeline to receive gasified LNG fuel;

the circulating heat exchange network comprises a multichannel liquid evaporator (2), a multichannel steam superheater (3), a multichannel supercooled steam regenerator (4) and corresponding connecting pipelines; the multi-channel liquid evaporator (2), the multi-channel steam superheater (3) and the multi-channel supercooling steam regenerator (4) are multi-stream heat exchangers, wherein the multi-channel liquid evaporator (2) is connected with the LNG storage tank (1) and receives liquid LNG fuel from the LNG storage tank, the multi-channel liquid evaporator (2) is communicated with the multi-channel supercooling steam superheater (3) to form an LNG evaporation gasification circulation loop, the multi-channel liquid evaporator (2) is communicated with the multi-channel supercooling steam regenerator (4) to form an LNG steam regenerative circulation loop, meanwhile, the multi-channel steam superheater (3) and the multi-channel supercooling steam regenerator (4) respectively receive a first cold-carrying agent (Z1) and a second cold-carrying agent (Z2) of a cold recovery unit as heat sources, enter the LNG evaporation gasification circulation loop and the LNG steam regenerative circulation loop and exchange heat with LNG saturated steam and supercooled steam, and the first cold agent (Z1) and the second cold agent (Z2) in the multi-channel supercooling steam superheater (3) after heat exchange respectively enter the multi-channel supercooling steam regenerator (4) from a multi-channel supercooling steam outlet (3) and a multi-channel supercooling steam regenerator (4) respectively to reach a specified heat recovery temperature from a multi-channel main engine (5) after the multi-channel supercooling steam regenerator and the multi-channel supercooling steam regenerator respectively enter the multi-channel evaporator and the multi-channel supercooling steam regenerator (4) and the multi-channel supercooling steam regenerator to be recycled;

The two cold energy recovery units respectively comprise a second cold energy utilization device (6), a first cold energy utilization device (7) and corresponding connecting pipelines; the second refrigerating capacity utilization device (6) and the first refrigerating capacity utilization device (7) respectively use the second refrigerating medium (Z2) and the first refrigerating medium (Z1) as refrigerants to provide cold energy, the high-temperature second refrigerating medium (Z2) and the high-temperature first refrigerating medium (Z1) at the outlets of the second refrigerating capacity utilization device (6) and the first refrigerating capacity utilization device (7) respectively enter the multichannel supercooling steam regenerator (4) and the multichannel steam superheater (3) of the circulating heat exchange network through pipelines to recover the gasified cold energy of LNG, the first refrigerating medium (Z1) and the second refrigerating medium (Z2) flowing out of the multichannel steam superheater (3) and the multichannel steam regenerator (4) after heat exchange flow back to the corresponding first refrigerating capacity utilization device (7) and the second refrigerating capacity utilization device (6) through pipelines, and the high-temperature second refrigerating medium (Z2) and the first refrigerating medium (Z1) continuously enter the circulating heat exchange network after the cold energy is released in the refrigerating capacity utilization devices;

the multi-channel liquid evaporator (2), the multi-channel steam superheater (3) and the multi-channel supercooling steam regenerator (4) of the circulating heat exchange network are plate-fin type, plate type, winding pipe type or shell-pipe type multi-flow heat exchangers;

The circulating heat exchange network is an integrated composite circulating heat exchange device formed by packaging and integrating a multichannel liquid evaporator (2), a multichannel steam superheater (3) and a multichannel supercooling steam heat regenerator (4) in the same multichannel heat exchanger, and is convenient to install;

the heat exchange channels in the multichannel liquid evaporator (2), the multichannel steam superheater (3) and the multichannel supercooling steam regenerator (4) all adopt fin structures, and the heat exchange channels of the multichannel liquid evaporator and the multichannel supercooling steam regenerator adopt straight fins or perforated fins in consideration of the fact that the viscosity of LNG liquid is high, and the heat exchange channels of the first refrigerating medium (Z1) and the second refrigerating medium (Z2) adopt straight or corrugated fins;

the multi-channel liquid evaporator (2) is a single multi-flow plate-fin heat exchanger, the multi-channel steam superheater (3) and the multi-channel supercooling steam heat regenerator (4) are combined into a heat exchanger with an integrated structure, industrial plate-fin heat exchanger fins are selected to be used in a heat exchange channel, and vacuum heat insulation layers (K) are respectively arranged on two sides of the multi-channel liquid evaporator (2), the multi-channel steam superheater (3) and the multi-channel supercooling steam heat regenerator (4) and used for isolating heat transfer between the heat exchanger and the outside and between the heat exchangers.

2. The cold energy recovery and heat exchange method for the LNG power ship is characterized by comprising the following steps of:

(1) Vaporization of LNG liquid fuels

The liquid LNG fuel in the LNG storage tank (1) is conveyed to a multichannel liquid evaporator (2) of the circulating heat exchange network through a low-temperature pipeline, the LNG liquid fuel is used as cold fluid, and LNG superheated steam which flows back after heat exchange of the multichannel steam superheater (3) and the multichannel supercooled steam regenerator (4) is used as hot fluid for evaporation and gasification, so that the LNG superheated steam is converted into LNG saturated steam;

(2) Circulation backheating of LNG steam

The LNG saturated steam enters a multichannel steam superheater (3) to exchange heat with a first refrigerating medium (Z1) and then becomes superheated steam of a first reflux, returns to the multichannel liquid evaporator (2) to exchange heat with the initial LNG liquid to become supercooled steam, and finally enters a multichannel supercooled steam regenerator (4) to release cold energy to a second refrigerating medium (Z2), so that the first regenerative cycle is completed; after heat exchange in the multichannel supercooling steam regenerator (4), the LNG superheated steam which does not reach the specified temperature flows back to the multichannel liquid evaporator (2) again, and as the start of the next regenerative cycle, the LNG liquid which is gasified initially flows back to the multichannel supercooling steam regenerator (4) again to continue regenerative operation;

(3) LNG is gasified and then supplied to a ship main engine

According to the ship fuel supply requirement, after LNG liquid circulates n times in a set circulation heat exchange network, the circulation times n is more than or equal to 2, and finally the LNG liquid is output at the outlet of the multichannel supercooling steam regenerator (4) in a natural gas mode according to the specified temperature and is conveyed to a ship host (5) for combustion through a fuel pipeline, so that the gasification circulation of LNG fuel is completed;

(4) Recovery cycle of cold

The first refrigerating medium (Z1) used by the first refrigerating capacity utilization device (7) is introduced into the multi-channel steam superheater (3) to absorb the refrigerating capacity of LNG saturated steam, then returns to the first refrigerating capacity utilization device (7) to release the refrigerating capacity for refrigeration, and the first refrigerating medium (Z1) after the refrigerating capacity release continuously enters the multi-channel steam superheater (3), so that the primary recycling cycle of LNG gasification refrigerating capacity is realized;

and a second refrigerating medium (Z2) used by the second refrigerating capacity utilization device (6) is introduced into the multichannel supercooling steam regenerator (4) to absorb the refrigerating capacity of LNG supercooling steam, then returns to the second refrigerating capacity utilization device (6) to release the refrigerating capacity for refrigeration, and the second refrigerating medium (Z2) after the refrigerating capacity is released continuously enters the multichannel supercooling steam regenerator (4), so that the secondary recovery cycle of LNG gasification refrigerating capacity is realized.

3. The heat exchange method for recovering cold energy of an LNG power ship according to claim 2, wherein the first and second refrigerants (Z1, Z2) are the same or different and are specifically selected according to different cycle times and required temperature conditions.

4. The heat exchange method for recovering cold energy of LNG power ship according to claim 2, wherein the first and second refrigerating media (Z1, Z2) are ethylene glycol aqueous solution and/or propylene glycol aqueous solution, and the type and flow rate of the refrigerating media are determined according to LNG supply amount, namely: the first coolant (Z1) in the multi-channel steam superheater (3) should ensure that the LNG gas that is returned to the multi-channel liquid evaporator (2) for the first time is in a superheated state, which is a state in which the LNG is completely vaporized to a gas at the working environment pressure and then is continuously heated.

5. The cold energy recovery heat exchange method for the LNG power ship according to claim 2 is characterized in that according to the flow of LNG required by the process, the calculation formula of the number n of circulating heat exchange times of a circulating heat exchange network is as follows:

wherein: m is LNG mass flow, r is LNG latent heat of vaporization, c _p Is the specific heat capacity of LNG, t _LNG-0 And t _LNG-12 The temperatures of the LNG liquid at the inlet and the natural gas at the outlet of the circulating heat exchange network are respectively t _LNG-3 For the temperature of the LNG subcooled steam entering the subcooled steam regenerator 4 for the first regenerative cycle, t _Z1-1 And t _Z1-2 The temperature, t, of the first coolant (Z1) at the inlet and outlet, respectively, of the multichannel steam superheater (3) _Z2-1 And t _Z2-2 The temperatures of the second refrigerating agent (Z2) at the inlet and the outlet of the multichannel supercooled steam regenerator (4) respectively.