CN109458554B - Marine LNG gasification and cold recovery heat exchange system and method - Google Patents
Marine LNG gasification and cold recovery heat exchange system and method Download PDFInfo
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- CN109458554B CN109458554B CN201811499586.5A CN201811499586A CN109458554B CN 109458554 B CN109458554 B CN 109458554B CN 201811499586 A CN201811499586 A CN 201811499586A CN 109458554 B CN109458554 B CN 109458554B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
- F17C7/02—Discharging liquefied gases
- F17C7/04—Discharging liquefied gases with change of state, e.g. vaporisation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C13/00—Details of vessels or of the filling or discharging of vessels
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2221/00—Handled fluid, in particular type of fluid
- F17C2221/03—Mixtures
- F17C2221/032—Hydrocarbons
- F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
- F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
- F17C2223/0146—Two-phase
- F17C2223/0153—Liquefied gas, e.g. LPG, GPL
- F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
- F17C2225/01—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the phase
- F17C2225/0107—Single phase
- F17C2225/0123—Single phase gaseous, e.g. CNG, GNC
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
- F17C2227/03—Heat exchange with the fluid
- F17C2227/0302—Heat exchange with the fluid by heating
- F17C2227/0309—Heat exchange with the fluid by heating using another fluid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2260/00—Purposes of gas storage and gas handling
- F17C2260/04—Reducing risks and environmental impact
- F17C2260/046—Enhancing energy recovery
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
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
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
In world cargo transportation, the proportion of ocean transportation is large, and the proportion of ocean transportation to the total import and export is up to more than 90% for China. According to International Maritime Organization (IMO) statistics, the annual emission of marine diesel engine contains SO 2 、NO 2 The exhaust gas of (2) causes about 5-11% of the total global atmosphere pollution. In order to protect the environment, IMO proposed regulations for controlling harmful emissions of marine diesel engines, set emission limits for pollutants such as marine sulfur oxides and nitrogen oxides, and set sulfur content limits for marine fuel oil to be reduced to 0.5% by 2020. Liquefied Natural Gas (LNG) as a clean energy source reduces a significant amount of particulates, sulfur Oxides (SO) when compared to conventional diesel fuel when burned to provide power x ) And Nitrogen Oxides (NO) x ) The waste is discharged and is under the condition of equivalent thermal massThe greenhouse gas emissions are only about 40% of diesel fuel. LNG is therefore considered an extremely attractive fuel alternative on marine vessels (including yachts, barges, container ships, etc.), and more vessels will use liquefied natural gas or hybrid (diesel/liquefied natural gas) as fuel. LNG is a low temperature liquid fuel stored at-162 ℃ under normal pressure conditions, which must be vaporized and superheated to ambient temperature before entering the ship's host engine. In the process, the LNG releases 860kJ/kg of cold energy, and the energy can be used for refrigerating, air conditioning, sea water desalination, power generation and other purposes on the ship, so that related refrigeration power consumption equipment is omitted, power consumption is reduced, and low-temperature damage to the marine environment and the ship body caused by directly gasifying the LNG by using the sea water is avoided.
However, the cold energy recovery function is not carried out in most LNG liquefaction modes at present, and common devices are open, immersed and intermediate liquid gasifiers. The former two uses air, seawater or industrial heat sources for LNG vaporization, and the main disadvantages are energy waste, the negative effects of residual chemical components and low-temperature seawater discharge on marine organisms. While intermediate liquid gasifiers use a coolant as an intermediate heat exchange product, the vast gasification temperature difference often results in low efficiency of the type of gasifiers, which cannot meet the industrial requirements. In particular to an LNG power ship, an improper gasification device cannot meet the temperature requirement of natural gas fuel for the ship, the normal operation of a ship main engine cannot be ensured, and the ship is damaged at low temperature due to serious damage even to a frozen pipeline.
Disclosure of Invention
In order to solve the problems, the invention discloses a cold energy recovery heat exchange system and a cold energy recovery heat exchange method for an LNG power ship, which not only can effectively gasify LNG fuel to supply to a ship host engine, but also can efficiently recover cold energy in the process to reduce related refrigeration energy consumption, simultaneously has the characteristics of no freezing and compact structure, and meets various cold energy and temperature requirements of the LNG ship.
In order to achieve the above object, the present invention is realized by adopting the following technical scheme:
the utility model provides a heat transfer system is retrieved to marine cold volume of LNG power, includes LNG fuel gasification unit, circulation heat transfer network and two cold volume recovery units are constituteed, 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 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, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are all multi-flow 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 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 refrigerant Z1 and a second refrigerant Z2 of a cold recovery unit as heat sources, the first refrigerant Z1 and the second refrigerant Z2 enter the LNG evaporation gasification circulation loop and the LNG steam regenerative circulation loop to exchange heat with LNG saturated steam and supercooling steam, and the supercooled liquid in the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 respectively flow back to respective corresponding cold energy units from outlets of the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4, and the supercooled liquid after heat exchange respectively reaches the specified temperature of the main engine 5 after the multi-channel heat exchange;
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 cold energy utilization device 6 and the first cold energy utilization device 7 respectively use the second cold energy Z2 and the first cold energy utilization device Z1 as refrigerants to provide cold energy, the high-temperature cold energy at the outlet of the second cold energy utilization device enters the multichannel supercooling steam heat regenerator 4 and the multichannel steam heat regenerator 3 of the circulating heat exchange network through pipelines to recover the gasified cold energy of LNG, and the supercooled liquid of the first cold energy utilization device 7 and the second cold energy utilization device 6 which are respectively corresponding to the first cold energy utilization device Z1 and the second cold energy utilization device Z2 which flow out of the multichannel steam heat regenerator 3 and the multichannel supercooling steam heat regenerator 4 after heat exchange returns through pipelines, so that the high-temperature cold energy is continuously changed into the high-temperature cold energy after the cold energy is released in the cold energy utilization devices to enter the circulating heat exchange network. The second cold energy utilization device 6 and the first cold energy utilization device 7 are various marine refrigerating devices such as an air conditioner, a refrigerated cabinet or a sea water desalination device.
Further, 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.
Furthermore, 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, and is convenient to install.
Further, the heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 all adopt fin structures, in consideration of the fact that the viscosity of the LNG liquid is high, the heat exchange channels are preferably flat fins or perforated fins, the heat exchange channels of the LNG saturated steam and the superheated and supercooled steam adopt zigzag fins or corrugated fins, and the heat exchange channels of the first refrigerating medium Z1 and the second refrigerating medium Z2 are preferably flat fins or corrugated fins.
Further, the arrangement mode of the heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 is configured in a single-layer, double-layer or combined mode of cold and hot fluid, namely, a layer of cold (or hot) channels is sandwiched between two adjacent layers of hot (or cold) channels, and the two layers of cold (or hot) channels are repeatedly stacked.
Further, 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 regenerator 4 are combined into a heat exchanger with an integrated structure, the heat exchange channels are internally provided with industrial plate-fin heat exchanger fins, and two sides of the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are respectively provided with a vacuum heat insulation layer K for isolating the heat transfer between the heat exchanger and the outside and between the heat exchangers.
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 the 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 vaporization, so that the LNG superheated steam is converted into LNG saturated steam;
(2) Circulation backheating of LNG steam
The LNG saturated steam enters the multichannel steam superheater 3 to exchange heat with the 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 the multichannel supercooled steam regenerator 4 to release cold energy to the 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 designated temperature flows back to the multichannel liquid evaporator 2 again, and as the start of the next regenerative cycle, the gasified initial LNG liquid flows back to the multichannel supercooling steam regenerator 4 again to continue regenerative operation;
(3) LNG gasification and supply host
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 supercooled 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 cycle of LNG fuel is completed;
in the gasification cycle of the LNG fuel, the LNG liquid fuel is gasified into natural gas with a specified temperature through the circulation heat exchange network and is transferred to the ship host, and part of the cold released in the LNG gasification process is absorbed by the first refrigerating medium Z1 in the multi-channel steam superheater 3, and the other part is absorbed by the second refrigerating medium Z2 in the multi-channel supercooled steam regenerator 4.
(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 releasing the refrigerating capacity continuously enters the multi-channel steam superheater 3, so that the primary recovery cycle of LNG gasification refrigerating capacity is realized;
the 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 release continuously enters the multichannel supercooling steam regenerator 4, so that the secondary recovery cycle of LNG gasification refrigerating capacity is realized.
Further, the first coolant Z1 and the second coolant Z2 may be the same or different, and should be specifically selected according to different cycle times and desired temperature conditions.
Further, the first and second refrigerants Z1 and Z2 are ethylene glycol aqueous solutions and/or propylene glycol aqueous solutions, and the type and flow rate of the refrigerants should be determined according to the LNG supply amount, that is: the first secondary refrigerant Z1 in the multi-channel steam superheater 3 should ensure that LNG gas returned to the multi-channel liquid evaporator 2 for the first time is in a superheated state, wherein the superheated state refers to a state that LNG is completely vaporized into gas under the working environment pressure and then is continuously heated; the freezing point of the second refrigerant Z2 in the multichannel subcooled steam regenerator 4, which is the triple point temperature at which the refrigerant solidifies at the operating ambient pressure, must be higher than the temperature of the LNG subcooled gas.
Further, according to the flow of LNG required by the process, the design parameters of the circulating heat exchange network are determined by the specific heat, flow, circulation times of the secondary refrigerant and the outlet temperature required to be reached by the secondary refrigerant; different design parameters are customized according to different flow and temperature requirements, and the method has high flexibility and wide applicability. The calculation formula of the number n of the circulating heat exchange times of the 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 first recovery cycle the temperature of the LNG subcooled steam entering the multichannel subcooled steam regenerator 4, 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 coolant Z2 at the inlet and outlet of the multichannel subcooled steam regenerator 4, respectively.
The number of cycles n is a function of the temperature t of the first coolant Z1 at the outlet of the multichannel steam superheater 3 given a determined LNG feed flow rate Z1-2 Is used for reducing the temperature t of the second secondary refrigerant Z2 at the inlet of the multichannel supercooled steam regenerator 4 Z2-1 Is reduced with the decrease in the cold fluid inlet temperature t in the multichannel liquid evaporator 2 LNG-0 And increases with decreasing amounts of (c). By adjusting the circulation times n of the circulation heat exchange network, different coolant temperatures meeting various user demands can be realized.
Compared with the prior art, the invention has the following beneficial effects:
1. because LNG liquid exchanges heat with self-superheated steam in the multichannel liquid evaporator for many times, the phase change latent heat of the LNG liquid is completely transferred to the self-superheated steam, so that the heat transfer between low-temperature liquid and a secondary refrigerant in the traditional heat exchange equipment is avoided, and the freezing phenomenon is avoided;
2. The unique design of the heat exchange network is that LNG liquid does not directly exchange heat with the secondary refrigerant in the evaporator, so that the risk of freezing the secondary refrigerant during direct heat exchange is effectively avoided. Meanwhile, through the heat transfer of continuous circulation between LNG liquid and superheated steam thereof and the heat exchange between the first secondary refrigerant and LNG saturated steam, the second secondary refrigerant and LNG supercooled steam, different circulation has different temperature gradients, which is more beneficial to improving the energy transfer efficiency of the circulation heat exchange network; meanwhile, the multi-channel liquid evaporator has a larger heat exchange temperature difference between LNG liquid and self-superheated steam, which is beneficial to complete gasification of the LNG liquid; the coolant and the natural gas supercooled steam in the multichannel supercooled steam regenerator exchange heat by adopting small temperature difference, so that relatively high cold energy recovery efficiency can be obtained;
3. the added multi-channel steam superheater in the circulating heat exchange network ensures the overheat state of LNG steam, and simultaneously, various degrees of freedom are added to the circulating heat exchange network so as to be suitable for generating various temperature secondary refrigerant products;
4. by selecting proper secondary refrigerant and adjusting the circulation times of the circulation heat exchange network, various different secondary refrigerant temperatures can be obtained under the process standard conditions so as to meet the use requirements of different occasions in the ship;
5. The intermediate fluid temperature of the heat exchange system can also be controlled by varying any parameter of the process specification given the number of cycles of the heat exchange system, for example: different coolant temperatures, natural gas outlet temperatures, flow ranges and the like can be obtained by adjusting the coolant flow. The invention has very wide adaptability in LNG power ships.
In summary, the system is compact and efficient, not only can the evaporated LNG without freezing be used for supplying the fuel to the ship, but also the gasified cold energy can be recovered simultaneously to meet the temperature requirements of different refrigeration application occasions on the ship, and the system and the method are suitable for popularization and application in the field of marine LNG.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of the structure and principle of a heat exchange system for LNG gasification and cold recovery for a ship in embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of the apparatus structure of the cyclical heat exchange network of FIG. 1;
FIG. 3 is a schematic diagram of a heat exchange channel arrangement of a multi-channel liquid evaporator of the cyclical heat exchange network of FIG. 1;
FIG. 4 is a schematic diagram of an arrangement of heat exchange channels of a multi-channel steam superheater and a multi-channel subcooled steam regenerator of an integrated structure of the cyclical heat exchange network of FIG. 1;
in the figure: 1. LNG liquid storage pot 2, multichannel liquid evaporator, 3, multichannel steam superheater, 4, multichannel supercooling steam regenerator, 5, marine host computer, 6, second cold volume utilization device, 7 first cold volume utilization device, Z1, first secondary refrigerant, Z2, second secondary refrigerant, K, vacuum insulation layer.
Detailed Description
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Meanwhile, it should be clear that the dimensions of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.
In the description of the present invention, it should be understood that the azimuth or positional relationships indicated by the azimuth terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal", and "top, bottom", etc., are generally based on the azimuth or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and these azimuth terms do not indicate and imply that the apparatus or elements referred to must have a specific azimuth or be constructed and operated in a specific azimuth, and thus should not be construed as limiting the scope of protection of the present invention: the orientation word "inner and outer" refers to inner and outer relative to the contour of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In addition, the terms "first", "second", etc. are used to define the components, and are only for convenience of distinguishing the corresponding components, and the terms have no special meaning unless otherwise stated, and therefore should not be construed as limiting the scope of the present invention.
Example 1
As shown in fig. 1, the cold energy recovery heat exchange system for the LNG power ship comprises an LNG fuel gasification unit, a circulation heat exchange network and two cold energy recovery units, wherein the LNG fuel gasification unit and the two cold energy recovery units are connected to exchange heat through the circulation heat exchange network, and the LNG fuel gasification unit and the two cold energy recovery units are connected with each other through the circulation heat exchange network, 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 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, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are all multi-flow heat exchangers, wherein the multi-channel liquid evaporator 2 is connected with the LNG storage tank 1 and receives liquid LNG-0 fuel from the LNG storage tank, the multi-channel liquid evaporator 2 is communicated with the multi-channel 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 backheating circulation loop, meanwhile, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 respectively receive a first refrigerant Z1 and a second refrigerant Z2 of a cold energy recovery unit as heat sources, the heat is exchanged with LNG saturated steam and supercooling steam, the first refrigerant Z1 and the second refrigerant Z2 in the multi-channel supercooling steam regenerator 4 are respectively returned to corresponding cold energy units from an outlet of the multi-channel steam superheater 3 and an outlet of the multi-channel supercooling steam regenerator 4, and the heat exchanged first refrigerant Z1 and second refrigerant Z2 reach a specified temperature after heat exchange and reach a specified temperature (LNG-storage tank) and enter the LNG-storage vessel 5 to be gasified by the heat regenerator 4;
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 cold energy utilization device 6 and the first cold energy utilization device 7 are various marine refrigeration devices such as an air conditioner, a refrigerator or a sea water desalination device, the second cold energy Z2 and the first cold energy Z1 are respectively used as refrigerants to provide cold energy, the high-temperature cold energy Z1-1 after releasing cold energy in the first cold energy utilization device 7 enters the multi-channel steam superheater 3 of the circulating heat exchange network through a pipeline to recycle part of gasified cold energy of LNG, the high-temperature cold energy Z2-1 after releasing cold energy in the second cold energy utilization device 6 enters the multi-channel supercooling steam regenerator 4 of the circulating heat exchange network through a pipeline to recycle the rest of gasified cold energy of LNG, and supercooling liquid flowing out of the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 after heat exchange flows back to the corresponding first cold energy utilization device 7 and the second cold energy utilization device 6 through pipelines respectively, and the high-temperature cold energy Z2-2 continues to be changed into high-temperature cold energy after releasing cold energy in the cold energy utilization device enters the circulating heat exchange network.
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-and-tube type multi-flow heat exchangers. As shown in fig. 2, 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, and is convenient to install. The LNG liquid, saturated steam, superheated and supercooled steam and the refrigerating medium are distributed into the circulating heat exchange network through the deflector bundles and the end sockets.
The heat exchange channels in the multi-channel liquid evaporator 2, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 all adopt fin structures, the heat exchange channels are preferably flat fins or perforated fins in consideration of the fact that the viscosity of LNG liquid is large, the heat exchange channels of LNG saturated steam and superheated and supercooled steam adopt zigzag fins or corrugated fins, and the heat exchange channels of the first refrigerating medium Z1 and the second refrigerating medium Z2 are preferably flat fins or corrugated fins.
As shown in fig. 3, the multi-channel liquid evaporator 2 is a single multi-flow plate-fin heat exchanger, wherein an industrial plate-fin heat exchanger fin is selected in a heat exchange channel, and vacuum heat insulation layers K are arranged on two sides of the heat exchanger and used for isolating the heat exchanger from external heat transfer. The arrangement of heat exchange channels in the multi-channel liquid evaporator 2 is configured in a single layer, double layer or combination of hot and cold fluid, i.e. a layer of cold (or hot) channels is sandwiched between two adjacent layers of hot (or cold) channels, and stacked repeatedly.
As shown in fig. 4, the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are combined into a heat exchanger with an integrated structure, and vacuum heat insulation layers K are respectively arranged on two sides of the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 and used for isolating heat transfer between the heat exchanger and the outside and between the heat exchangers. The arrangement mode of the heat exchange channels in the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 is configured in a single-layer, double-layer or combined mode of cold and hot fluid, namely, one layer of cold (or hot) channels is clamped between two adjacent layers of hot (or cold) channels, and the two layers of cold (or hot) channels are repeatedly stacked.
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-0 fuel in the LNG storage tank 1 is conveyed to the multichannel liquid evaporator 2 of the circulating heat exchange network through a low-temperature pipeline, the LNG-0 liquid fuel is used as cold fluid, and LNG superheated steam (LNG-2, LNG-4, LNG-6, LNG-8 and LNG-10) which flows back after heat exchange of the multichannel steam superheater 3 and the multichannel supercooled steam regenerator 4 is used as hot fluid to be evaporated and gasified, so that the LNG saturated steam LNG-1 is converted;
(2) Circulation backheating of LNG steam
The saturated steam LNG-1 enters a multi-channel steam superheater 3 to exchange heat with a first refrigerating medium Z1 and then becomes superheated steam LNG-2 of a first reflux, returns to the multi-channel liquid evaporator 2 to exchange heat with initial LNG-0 liquid and become supercooled steam LNG-3, and finally enters a multi-channel 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 supercooled steam regenerator 4, LNG superheated steam (LNG-4, LNG-6, LNG-8 and LNG-10) 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 gasified initial LNG-0 liquid flows back to the multichannel supercooled steam regenerator 4 again to continue regenerative;
(3) LNG gasification and supply host
According to the ship fuel supply requirement, after the LNG liquid circulates n times in a set circulation heat exchange network, the circulation times n is more than or equal to 2, n=5 in the embodiment, and finally, the LNG-12 is output in a form of natural gas NG at the outlet of the multichannel supercooling steam regenerator 4 according to the specified temperature and is conveyed to the ship host 5 for combustion through a fuel gas pipeline, so that the gasification circulation of the LNG fuel is completed;
in the gasification cycle of the LNG fuel, the LNG-0 liquid fuel is gasified into the natural gas NG with a specified temperature through the circulation heat exchange network and is transferred to the ship host, and part of the cold released in the LNG gasification process is absorbed by the first refrigerant Z1 in the multi-channel steam superheater 3, and the other part is absorbed by the second refrigerant Z2 in the multi-channel supercooled steam regenerator 4.
(4) Recovery cycle of cold
The first refrigerating medium Z1-1 used by the first refrigerating capacity utilization device 7 is introduced into the multi-channel steam superheater 3 to absorb the refrigerating capacity Z1-2 of saturated steam LNG-1, and returns to the first refrigerating capacity utilization device 7 to release refrigerating capacity for refrigeration, and is changed into Z1-1 again after the refrigerating capacity is released to enter the multi-channel steam superheater 3, so that primary recovery cycle of LNG gasification refrigerating capacity is realized;
The second refrigerating medium Z2-1 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 (LNG-3, LNG-5, LNG-7, LNG-9 and LNG-11) to change into Z2-2, and returns to the second refrigerating capacity utilization device 6 to release the refrigerating capacity for refrigeration, and then changes into Z2-1 again to continue to enter the multichannel supercooling steam regenerator 4 after the refrigerating capacity is released, so that the secondary recovery cycle of LNG gasification refrigerating capacity is realized;
the first refrigerating medium Z1 and the second refrigerating medium Z2 are respectively introduced into a first refrigerating capacity utilization device 7 and a second refrigerating capacity utilization device 6 which are different after absorbing the evaporation latent heat of LNG and the latent heat of temperature difference with the environment, the first refrigerating capacity utilization device 7 and the second refrigerating capacity utilization device 6 are various marine refrigerating devices such as an air conditioner, a refrigerated cabinet or a sea water desalination device, the first refrigerating medium Z1 and the second refrigerating medium Z2 release the refrigerating capacity and then return to a heat exchange network to absorb the refrigerating capacity released in the LNG evaporation process again, and the refrigerating capacity recovery cycle is completed.
The first secondary refrigerant Z1 and the second secondary refrigerant Z2 adopt glycol aqueous solution and/or propylene glycol aqueous solution. The first coolant Z1 and the second coolant Z2 may be the same or different and should be specifically selected according to different cycle times and desired temperature conditions.
The types and the flow rates of the first refrigerating medium Z1 and the second refrigerating medium Z2 are determined according to the LNG supply quantity, namely: the first secondary refrigerant Z1 in the multi-channel steam superheater 3 should ensure that LNG-2 gas returned to the multi-channel liquid evaporator 2 for the first time is in a superheated state, wherein the superheated state refers to a state that LNG is completely vaporized into gas under the working environment pressure and then is continuously heated; the freezing point of the second refrigerant Z2 in the multichannel subcooled vapor regenerator 4, which refers to the triple point temperature at which the refrigerant solidifies at operating ambient pressure, must be higher than the temperature of the LNG subcooled vapor (LNG-3, LNG-5, LNG-7, LNG-9, LNG-11).
According to the flow of LNG required by the process, the design parameters of the circulating heat exchange network are determined by the specific heat, flow and circulation times of the secondary refrigerant and the outlet temperature required to be reached by the secondary refrigerant; different design parameters are customized according to different flow and temperature requirements, and the method has high flexibility and wide applicability.
The calculation formula of the number n of the circulating heat exchange times of the circulating heat exchange network is as follows:
wherein: m is LNG mass flow, r is LNG latent heat of vaporization, c p The specific heat capacity of LNG, t is the temperature of each fluid in fig. 1, and the fluid type corresponding to each temperature is shown by its corresponding subscript, namely: temperature of LNG-12, LNG-0, LNG-3, Z1-2, Z1-1, Z2-2, Z2-1 fluid.
The number of cycles n is a function of the temperature t of the first coolant Z1 at the outlet of the multichannel steam superheater 3 given a determined LNG feed flow rate Z1-2 Is used for reducing the temperature t of the second secondary refrigerant Z2 at the inlet of the multichannel supercooled steam regenerator 4 Z2-1 Is reduced with the decrease in the cold fluid inlet temperature t in the multichannel liquid evaporator 2 LNG-0 And increases with decreasing amounts of (c). By adjusting the circulation times n of the circulation heat exchange network, different coolant temperatures meeting various user demands can be realized.
As shown in fig. 3, in this embodiment, the number of cycles n of the circulating heat exchange network is set to 5, the multi-channel liquid evaporator 2 is a multi-channel plate-fin heat exchanger, the heat exchange channels thereof are arranged in a cold-hot fluid "sandwich" manner, the LNG liquid channels are designed to be 5 channels, and the LNG superheated steam for each cycle is set to 2 channels and circulated 5 times for a total of 10 channels. In the multichannel liquid evaporator 2, heat exchange is performed for 1 cold fluid LNG-0 and 5 hot fluids (LNG-2, LNG-4, LNG-6, LNG-8, LNG-10). The LNG liquid LNG-0 is distributed into 5 layers of heat exchange channels, each layer of channel fins are perforated fins, the fin height is 6.5mm, the fin width is 1.4mm, the fin thickness is 0.2mm, LNG liquid in the 5 layers of channels is converged to the corresponding end socket by guide plates and discharged, and the model of the guide plates is 65D4205; LNG superheated steam LNG-2, LNG-4, LNG-6, LNG-8, LNG-10 are 5 heat exchange circulation loops, and every loop is divided into 2 layers, and 10 layers of heat exchange channels altogether, and every layer of fin is the zigzag fin, and the fin height is 9.5mm, the fin width is 1.4mm, the fin thickness is 0.2mm, the zigzag pitch is 3mm, and LNG steam in the 10 layers of channels is assembled to corresponding head by the guide vane and is discharged, and the guide vane model is 95D4205. In addition, in order to reduce the size of the heat exchanger and facilitate the distribution of the channels, the heat exchange layer of the hot fluid in the embodiment is designed into a symmetrical structure, and the proportion is 3:2, namely: the 6-layer channels include LNG-2, LNG-6, and LNG-10, and the 4-layer channels include LNG-4 and LNG-8. In order to properly preserve heat, a vacuum heat insulation layer K is arranged on two sides of the outermost layer of the heat exchange channel. Each layer of channel consists of a seal head, a seal strip, a side plate, a guide vane and heat exchange fins. The 5 heat exchange loops LNG-2, LNG-4, LNG-6, LNG-8 and LNG-10 in the multichannel liquid evaporator 2 are sequentially subjected to heat exchange instead of simultaneous heat exchange, so that the cold energy recovery efficiency can be improved to a greater extent.
The multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are combined into a heat exchanger with an integrated structure, and as shown in fig. 4, heat exchange channels in the multi-channel steam superheater 3 and the multi-channel supercooling steam regenerator 4 are arranged in a cold and hot fluid sandwich manner. In the multi-pass steam superheater 3, the first coolant Z1 is distributed as 3-layer passes and the LNG-saturated steam is distributed as 2-layer passes, which are arranged alternately with each other. In the multichannel supercooling steam regenerator 4, the LNG supercooling steam for each cycle is set to be 2-layer passages and 5 cycles, and 10 layers of channels are formed in total; the second coolant Z2 is set to 11 layers of channels, and is arranged at intervals and wraps each layer of supercooled steam channels.
In the multichannel supercooled steam regenerator 4, heat exchange is performed for 1 hot fluid coolant Z2-1 and 5 cold fluids (LNG-3, LNG-5, LNG-7, LNG-9, LNG-11). The refrigerating medium Z2-1 is distributed into 11 layers of heat exchange channels, fins of each layer of channels are straight fins, the fin height is 9.5mm, the fin width is 2mm, the fin thickness is 0.3mm, refrigerating medium liquid in the 11 layers of channels is converged to corresponding seal heads by guide plates and is discharged, and the model of the guide plates is 95DD4205; LNG subcooling steam LNG-3, LNG-5, LNG-7, LNG-9, LNG-11 are divided into 5 heat exchange circulation loops, each loop is divided into 2 layers, 10 layers of heat exchange channels are arranged in total, each layer of fins is a zigzag fin, the fin height is 9.5mm, the fin width is 1.4mm, the fin thickness is 0.2mm, the zigzag pitch is 3mm, LNG steam in the 10 layers of channels is converged to the corresponding end sockets by guide plates and discharged, and the model of the guide plates is 95D4205. In addition, in order to reduce the size of the heat exchanger and facilitate the distribution of heat exchange channels, the heat exchange layer of the hot fluid is designed into a symmetrical structure, and the proportion is 3:2, i.e. 6 layer channels include LNG-3, LNG-5 and LNG-7, and 4 layer channels include LNG-9 and LNG-11. In order to properly preserve heat, a vacuum heat insulation layer K is arranged on two sides of the outermost layer of the heat exchange channel. Each layer of channel consists of a seal head, a seal strip, a side plate, a guide vane and heat exchange fins. The 5 heat exchange circulation loops LNG-3, LNG-5, LNG-7, LNG-9 and LNG-11 in the multichannel supercooling steam regenerator 4 also exchange heat sequentially instead of simultaneously, so that the cold energy recovery efficiency is further improved.
Furthermore, to reduce the constructional size, the multichannel steam superheater 3 is integrated inside the multichannel subcooled steam regenerator 4 and is separated by 2 vacuum insulation layers K. The multichannel steam superheater 3 is internally provided with 3 layers of first refrigerating medium heat exchange channels and 2 layers of LNG saturated steam heat exchange channels, and is used for carrying out heat exchange between the hot fluid Z1-1 and the cold fluid LNG-1, and the structure is the same as that described above and is not repeated. Each layer of channel consists of a seal head, a seal strip, a side plate, a guide vane and heat exchange fins.
According to the schematic diagram shown in fig. 1, LNG-0 liquid enters a circulation heat exchange network after being subjected to flow regulation by a fuel pump from an LNG storage tank 1. The LNG-0 passes through a multichannel liquid evaporator 2, the phase change latent heat is transferred to superheated steam LNG-2, LNG-4, LNG-6, … and LNG-2n, then the saturated LNG steam LNG-1 enters a multichannel steam superheater 3 to exchange heat with a first refrigerating medium Z1, and the refrigerating medium Z1 is heated to superheated LNG steam LNG-2; LNG-2 is returned to the multichannel liquid vaporizer 2 as a first heat stream to heat LNG-0, an initial cryogenic liquid; after exchanging heat with the LNG-0, the superheated steam LNG-2 is changed into the supercooled steam LNG-3 and continuously flows into the multichannel supercooled steam regenerator 4; in the multichannel supercooling steam regenerator 4, the second refrigerating medium Z2 circularly heats supercooling steam LNG-3, LNG-5, LNG-7, … and LNG-2n+1; the LNG-3 heated by the refrigerating medium Z2 is changed into superheated steam LNG-4, and the superheated steam LNG-4 is returned to the multi-channel liquid evaporator 2 to complete primary circulation in the circulating heat exchange network; LNG-4 is returned to the multichannel liquid vaporizer 2 as the second heat stream to continue heating LNG-0, the initial cryogenic liquid, and thus to start the next cycle. In the above manner, after the LNG liquid releases latent heat of phase change to its superheated steam, the LNG liquid releases cold energy again to the first coolant Z1 through the multi-pass steam superheater 3, and finally continues to release cold energy to the second coolant Z2 in the multi-pass supercooled steam regenerator 4. After the circulation is carried out n times in the multichannel liquid evaporator 2 and the multichannel supercooling steam regenerator 4, LNG-2n+2 at the outlet of the multichannel supercooling steam regenerator 4 is taken as the gasified product natural gas of LNG, and the gasified product natural gas is discharged after reaching a specified temperature and enters a ship host engine to be used as power fuel.
Secondly, in a circulating heat exchange network, the first secondary refrigerant Z1 firstly absorbs the cold energy of LNG-1 steam in a saturated state in a superheater to be changed into superheated steam LNG-2, and returns the superheated steam LNG-2 to the multichannel liquid evaporator 2 to heat LNG initial low-temperature liquid LNG-0; subsequently, the second refrigerating medium Z2 circularly absorbs the cold energy of LNG supercooling steam LNG-3, LNG-5, LNG-7, … and LNG-2n+1 from the multichannel liquid evaporator 2 in the multichannel supercooling steam regenerator 4, and the whole cold energy is obtained after repeated circulation for n times.
LNG refrigeration is ultimately recovered by a first refrigerant Z1 in the multichannel steam superheater 3 and a second refrigerant Z2 in the multichannel subcooled steam regenerator 4 at different temperature gradient conditions: the first refrigerating medium Z1 is used for recovering low-temperature cold energy, the outlet temperature of the first refrigerating medium Z1 can reach minus 30 ℃ at the lowest according to the flow of LNG, and the recovered cold energy can be used by ship refrigeration equipment; the second refrigerating medium is used for recovering the high Wen Lengliang, the outlet temperature of the second refrigerating medium can reach about 10 ℃, and the recovered cold can be used for systems such as ship air conditioners and the like. During the heat exchange process, the LNG vapor and the coolant have a temperature gradient of between 10 ℃ and 30 ℃. The circulating heat exchange network adopts multiple circulation to return temperature, the inlet of the circulating heat exchange network is LNG liquid, and the outlet of the circulating heat exchange network is natural gas output.
According to the LNG gasification and cold recovery heat exchange system and method for the ship, LNG liquid in the ship fuel liquid storage tank is gasified efficiently through the circulating heat exchange network, and cold recovery is performed by utilizing the secondary refrigerant, so that the natural gas fuel supply requirement of a ship host engine can be met, cold energy released in the gasification process can be recovered efficiently, and the cold energy requirements of devices such as ship air conditioners, food refrigerators and sea water desalination can be supplied at different temperatures. According to the invention, the cold and hot fluid performs large-temperature-difference heat exchange to ensure complete gasification when LNG is gasified through ingenious design, and performs small-temperature-difference heat exchange to improve energy recovery efficiency when cold energy is recovered, and the problems of freezing and low efficiency of the traditional gasifier are effectively avoided through unique circulating self-evaporation design and circulating refrigerating medium recovery cold energy design.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
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.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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| CN100434292C (en) * | 2003-01-17 | 2008-11-19 | 西安交通大学 | Car air conditioner making use of quantity of cold of liquefied natural gas |
| JP4396938B2 (en) * | 2005-03-25 | 2010-01-13 | 日産ディーゼル工業株式会社 | Air conditioner / refrigerator and automobile equipped with the same |
| CN101344354A (en) * | 2007-09-29 | 2009-01-14 | 上海海事大学 | LNG cold energy utilization method |
| CN101696857A (en) * | 2009-10-20 | 2010-04-21 | 无锡佳龙换热器制造有限公司 | Plate-fin heat exchanger |
| CN102135051B (en) * | 2011-01-25 | 2012-07-25 | 西安交通大学 | Unfrozen heat exchanger for liquefied natural gas (LNG) automobile air conditioner |
| JP6366411B2 (en) * | 2014-08-01 | 2018-08-01 | 大阪瓦斯株式会社 | Liquefied natural gas cold energy facility |
| CN204154017U (en) * | 2014-09-19 | 2015-02-11 | 廊坊新奥燃气有限公司 | LNG cold energy use system |
| CN106287212B (en) * | 2015-05-14 | 2020-08-04 | 浙江盾安人工环境股份有限公司 | Regenerative gasifier |
| CN105202806A (en) * | 2015-10-26 | 2015-12-30 | 中国水产科学研究院渔业机械仪器研究所 | Ship cooling system and cooling method for composite using of LNG and refrigerating unit cold energy |
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| CN107345728A (en) * | 2017-06-16 | 2017-11-14 | 上海工程技术大学 | A kind of cold energy of liquefied natural gas peculiar to vessel is used for the System and method for of freezer refrigerating |
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