CN115264377A - Cryogenic energy storage system and method based on LNG tank - Google Patents
Cryogenic energy storage system and method based on LNG tank Download PDFInfo
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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
- F17C6/00—Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases
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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
- F17C13/004—Details of vessels or of the filling or discharging of vessels for large storage vessels not under pressure
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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
- F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
- F17C13/026—Special adaptations of indicating, measuring, or monitoring equipment having the temperature as the parameter
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
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- F17C13/00—Details of vessels or of the filling or discharging of vessels
- F17C13/04—Arrangement or mounting of valves
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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
- F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J15/00—Systems for storing electric energy
- H02J15/006—Systems for storing electric energy in the form of pneumatic energy, e.g. compressed air energy storage [CAES]
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/008—Circuit arrangements for ac mains or ac distribution networks involving trading of energy or energy transmission rights
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
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- F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
- F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
- F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
- F17C2205/0352—Pipes
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- 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
- F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
- F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
- F17C2205/0388—Arrangement of valves, regulators, filters
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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
- F17C2227/01—Propulsion of the fluid
- F17C2227/0128—Propulsion of the fluid with pumps or compressors
- F17C2227/0135—Pumps
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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
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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
- F17C2227/0337—Heat exchange with the fluid by cooling
- F17C2227/0339—Heat exchange with the fluid by cooling using the same 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
- F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
- F17C2250/04—Indicating or measuring of parameters as input values
- F17C2250/0404—Parameters indicated or measured
- F17C2250/0439—Temperature
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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
- F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
- F17C2250/06—Controlling or regulating of parameters as output values
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- F17C2250/0631—Temperature
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Abstract
The invention relates to a cryogenic energy storage and storage system and method based on an LNG tank, belonging to the technical field of LNG energy storage, wherein an energy storage benefit evaluation module is used for judging the peak/valley logic of the electricity price of a power grid, LNG in an LNG storage tank is subjected to circulating cryogenic cooling to lower temperature by virtue of a cryogenic circulation module, cryogenic energy is stored, and the cryogenic LNG releases cold energy at proper time and is used for generating more electric power; in addition, the LNG can be stored to a lower temperature according to the logic judgment of the energy storage benefit evaluation module, so that the methane content of the LNG is unchanged, the LNG components are kept, the gasification of LNG liquid is reduced, the high quality of the LNG is kept, the sale is facilitated, and the cryogenic energy storage, utilization and development of the storage tank of the LNG receiving station are realized by utilizing the cryogenic operation and the logic judgment function of the LNG.
Description
Technical Field
The invention belongs to the technical field of LNG energy storage, and particularly relates to a cryogenic energy storage system and method based on an LNG tank.
Background
The energy storage refers to a process of storing energy through media or equipment and releasing the energy when needed, and the stored energy can improve the power utilization efficiency, improve the power stability and availability, cut peaks and fill valleys in the process of participating in peak shaving, standby and demand side response of a power grid, and can realize the important means of flexibility, economy and safety of a traditional power system. Cold and hot energy storage is different branches in the energy storage technology, and the cold and hot energy storage is used as a physical energy storage method, so that the outstanding advantage is that no chemical reaction exists in the working process of energy storage and energy release, the cleaning and the environmental protection are realized, the physical performance of an energy storage medium is not changed, and the energy storage benefit is easily exerted.
22 large receiving stations and large LNG storage tanks thereof are built in China to 2021 years, the total receiving capacity of the LNG in China is estimated to reach 9915 ten thousand tons, and the receiving capacity of the LNG in 2030 years is expected to reach ten thousand tons. Liquefied Natural Gas (LNG) is a liquid obtained by compressing and cooling natural gas to the boiling point (-161.5 ℃) of the natural gas, and exists in an ultralow temperature liquid form in a standard state, and is usually stored in a low-temperature LNG storage tank at the temperature of-160 ℃ and about 0.1MPa, most of the storage tanks of LNG receiving stations adopt a full-capacity heat preservation form, usually a large capacity of 5-22 ten thousand cubic meters, however, due to the fact that LNG stands still for a long time and has a huge temperature difference with the environment, the tank bottom wall of the LNG storage tank has heat leakage effect, the temperature can gradually rise from-160 ℃ during receiving goods, BOG is easy to gasify due to the influence of the environment heat in the LNG storage, the main component of BOG is methane, the LNG changes due to temperature rise and gasification, in addition, the temperature of the LNG storage tank is uneven, the LNG is easy to stratify due to long-term storage, as the phenomenon is generally called LNG storage aging problem, and the problem of LNG storage exists in the existing receiving stations, and no feasible solution exists.
And when the LNG is sold at the LNG receiving station, the LNG receiving station has obvious selling price difference in light and busy seasons, has less gasification loss of the LNG with stable components and lower temperature, and is easier to sell.
In addition, the power generation by utilizing the LNG cold energy characteristic is mature day by day (the LNG cold energy is recovered in the form of electric energy), the LNG cold energy power generation is a power generation process based on the low-temperature LNG temperature rise, and a large amount of cold energy is released (specifically, the LNG low-temperature cold energy is utilized to liquefy a working medium, and the working medium is heated, gasified and expanded to do work to generate power, wherein the power generation method comprises a Rankine cycle method and a Brayton cycle method of an intermediate medium, and the like).
Disclosure of Invention
The invention aims to provide a cryogenic energy storage and storage system and method based on an LNG tank, which are suitable for LNG receiving stations with wide bases, realize the cryogenic energy storage function of LNG at the temperature lower than minus 160 ℃ by utilizing the peak-to-valley power difference of a power grid, meet the basic requirements of cold energy storage by taking the LNG as a medium and taking the existing conditions of a storage tank, improve the quality sale of the LNG through cryogenic energy storage and cryogenic power generation, and realize the cryogenic energy storage benefit of the LNG.
In order to solve the technical problems, the invention adopts the technical scheme that: a cryogenic energy storage and storage system based on an LNG tank comprises the LNG storage tank, an LNG circulating pump is located in the LNG storage tank, an output port of the LNG circulating pump is communicated with an input end of a heat exchanger through an output pipeline, and an output end of the heat exchanger is communicated with the LNG storage tank through a cryogenic return pipeline to form a heat exchange loop;
the temperature control module is respectively connected with the temperature measurement and evaluation unit and the cryogenic cycle module, the temperature measurement and evaluation unit is connected with a temperature detection instrument in the LNG storage tank, and the cryogenic cycle module is connected with the heat exchanger to realize temperature control;
the energy storage benefit evaluation module is respectively connected with the LNG circulating pump, the cryogenic circulating module, the three-way valve and the cold energy power generation unit, and benefit evaluation is achieved.
Furthermore, the inlet of the return pipe of the cryogenic return pipeline and the suction inlet of the LNG circulating pump are arranged diagonally. The back flow entry is diagonal angle with the LNG circulating pump sunction inlet and arranges, LNG circulating pump sunction inlet forms the maximum distance with the LNG back flow entry after cryrogenic like this, make LNG realize effective mixing action in the LNG storage tank is inside, (because the LNG temperature that the LNG circulating pump inhales LNG storage tank bottom is higher, the LNG temperature that flows back after heat exchanger cryrogenic is lower, then form the LNG fluid of different density different temperatures in the LNG storage tank, form the convection effect), LNG is the abundant quick convection current mix in the LNG storage tank, can ensure that temperature is even in the LNG storage tank, the composition is stable.
Furthermore, the three-way valve is installed on a branch line of the output pipeline, a first branch of the three-way valve is communicated with the cold energy power generation unit, and a second branch of the three-way valve is communicated with the LNG distribution branch pipe system.
A cryogenic energy storage method based on an LNG tank comprises the following steps: according to the judgment logic of the energy storage benefit evaluation module, an LNG circulating pump and a cryogenic circulation module are started, LNG is discharged from an LNG storage tank, is subjected to cryogenic treatment through a heat exchanger, and then flows back to the LNG storage tank through a cryogenic return pipeline, and then according to the judgment logic of the energy storage benefit evaluation module, the LNG goes to a cold energy power generation unit when LNG cold energy power generation is needed; when LNG needs to be sold, LNG is distributed to LNG branch piping.
Further, the temperature of the LNG storage tank is comprehensively judged through the temperature measurement and evaluation unit module, the temperature detection instruments are arranged at the upper part, the middle part and the bottom part, multipoint temperature values of the LNG storage tank are collected, the temperature is obtained through weighted average calculation, and the temperature is the evaluation temperature T of the LNG storage tank 1 The evaluation temperature T 1 The value will be the input signal to the temperature control module.
Further, the energy storage benefit evaluation module takes evaluation information according to the rated input power of the cryogenic circulation module, the rated output power of the LNG cold energy power generation, the parameters of the LNG storage tank, LNG price sales information and power grid peak/valley price information as the logic input value of the energy storage benefit evaluation module, the benefit value comparison and the intelligent calculation are carried out under the intelligent logic A (priority) of the energy storage benefit evaluation module and the intelligent logic B (secondary) of the energy storage benefit evaluation module, whether the cryogenic operation of the LNG storage tank is executed or not is determined according to logic, the cryogenic setting temperature of the LNG after the cryogenic energy storage is determined, a certain value T in a certain temperature interval is set at the cryogenic temperature of the LNG storage tank under logic, and the setting target of the cryogenic energy storage of the LNG storage tank and the cryogenic temperature of the LNG after the cryogenic energy storage is determined.
Further, the energy storage benefit evaluation module intelligent logic a: calculating rated input power of the cryogenic cycle module, the power grid valley electricity price and the constant, comparing rated output power of the cold energy power generation corresponding to the LNG and the power grid peak electricity price to judge whether the LNG is valuable or not by cryogenic energy storage power generation, and determining a cryogenic temperature value T by combining with the LNG storage tank 1 parameter 2 (if between-160 ° and-172 °).
Furthermore, the energy storage benefit evaluation module intelligently calculates and judges that the cryogenic energy storage power generation is valuable and can be executed, and the temperature is set at T after the intelligent logic calculation of the LNG storage tank 2 ，T 2 The temperature control module is used as an energy storage system temperature control target and passes through a set value T 2 And T 1 Comparing, carrying out temperature PID regulation deep cooling operation, outputting instructions to a deep cooling circulation module for temperature control, and when the peak value of the power grid can release the cryogenic power generation, a first branch of the three-way valve is opened to the cold energy power generation unit, and the LNG cold energy power generation is started.
Further, the energy storage benefit evaluation module intelligent logic B: when the power grid valley electricity price appears, the rated input power of the LNG cryogenic cycle module, the power grid valley electricity price and the expected time constant (namely the LNG storage tank maintains the low temperature T) are compared according to the LNG sales price information 3 The generated valley electricity fee) is compared with the high-quality sales appreciation in the LNG expected time, the LNG cryogenic circulation module is started when the value of the LNG stored cryogenically is comprehensively judged to be met, and the cryogenic storage temperature T of the LNG storage tank is determined according to the intelligent logic B of the energy storage benefit evaluation module 3 And the cryogenic circulating module is subjected to LNG storage tank temperatureDegree control, LNG storage tank maintained at T 3 And under the intelligent logic B of the energy storage benefit evaluation module, when the LNG high-price selling condition is judged to be met, high-quality LNG selling can be carried out, the LNG selling value is increased, and the energy storage benefit evaluation module opens the second branch of the three-way valve to the LNG distribution branch pipe system for selling.
Further, if the intelligent logic A of the energy storage benefit evaluation module and the intelligent logic B of the energy storage benefit evaluation module are judged to be out of order, the LNG storage tank restores the original natural storage state.
The method judges the peak/valley logic of the power price of the power grid through the energy storage benefit evaluation module, carries out circulating cryogenic cooling on LNG (about-160 ℃) in an LNG storage tank to lower temperature by means of the cryogenic circulation module, stores cryogenic energy, and releases cold energy from the cryogenic LNG at proper time for generating more electric power; in addition, the LNG can be stored to a lower temperature lower than minus 160 ℃ according to the logic judgment of the energy storage benefit evaluation module, so that the methane content of the LNG is unchanged, the LNG components are kept, the gasification of LNG liquid is reduced, the high quality of the LNG is kept, the sale is facilitated, and the cryogenic energy storage, utilization and development of the storage tank of the LNG receiving station are realized by utilizing the cryogenic operation and logic judgment function of the LNG.
The invention has the following specific effects: 1. the LNG storage tank can intelligently guide three operation states of natural storage, LNG cryogenic storage and cryogenic power generation by using the energy storage benefit evaluation module, and LNG storage and energy storage benefit judgment are realized by using an intelligent means; 2. according to the invention, the LNG cryogenic energy storage is carried out when the power grid is low in price by utilizing the intelligent judgment of the energy storage benefit evaluation module; 3. the method utilizes the energy storage benefit evaluation module to intelligently judge and generate power by cryogenic release of LNG cold energy when the power grid is high in price; 4. the comprehensive temperature of the LNG storage tank is evaluated by a temperature measurement and evaluation unit; 5. the temperature control module is used for adjusting the temperature of the LNG storage tank within a temperature range (such as-160 ℃ to-170 ℃); according to the invention, the cryogenic storage of LNG and the high-income sale of LNG are comprehensively judged through the energy storage benefit evaluation module.
In conclusion, compared with other energy storage modes (such as water storage tank energy storage), the cryogenic energy storage system disclosed by the invention realizes the development of cryogenic energy storage function based on the existing LNG storage function of the LNG receiving station storage tank, and has the advantages of convenience in basic conditions, simplicity in modification work, cleanness and environmental friendliness. In addition, the LNG physical properties do not change in the period, the LNG quality is improved, the energy storage benefit is easily and better realized, meanwhile, the price is intelligently judged for sale, and the LNG receiving station is favorable for exerting more benefits.
With the continuous expansion of the construction scale of LNG receiving stations in China and the wide distribution in coastal areas in China, the invention carries out energy storage transformation on the receiving stations, realizes the energy storage function, is beneficial to commercial popularization, can realize scale effect and is easy to generate good value, thereby driving the utilization and development of LNG energy storage technology.
Drawings
The advantages and realisation of the invention will be more apparent from the following detailed description, given by way of example, with reference to the accompanying drawings, which are given for the purpose of illustration only, and which are not to be construed in any way as limiting the invention, and in which:
FIG. 1 is a diagram of a cryogenic energy storage system for an LNG tank of the present invention;
fig. 2 is a logic diagram of a cryogenic energy storage function of an LNG tank of the present invention.
In the figure:
1. an LNG storage tank; 2. an LNG circulation pump; 3. a heat exchanger; 4. a cryogenic cycle module; 5. a temperature measurement evaluation unit; 6. a temperature control module; 7. an energy storage benefit evaluation module; 8. a cold energy power generation unit; 9. an electric three-way valve; 10. LNG distribution branch piping; i, a return pipe inlet; II, an LNG circulating pump suction inlet.
Detailed Description
As shown in fig. 1, the cryogenic energy storage system based on an LNG tank of the present invention includes an LNG storage tank 1, an LNG circulation pump 2, a heat exchanger 3, a cryogenic circulation module 4, a temperature measurement and evaluation unit 5, a temperature control module 6, an energy storage benefit evaluation module 7, a cold energy power generation unit 8, and a three-way valve (an electric three-way valve 9).
The temperature control module 6 is respectively connected with the temperature measurement and evaluation unit 5 and the cryogenic cycle module 4, the temperature measurement and evaluation unit 5 is connected with a temperature detection instrument in the LNG storage tank 1, wherein the temperature detection instrument respectively corresponds to the upper part (point a), the middle part (point b) and the bottom (point c) to acquire multipoint temperature values of the LNG storage tank 1. Meanwhile, the cryogenic cycle module 4 is connected to the heat exchanger 3.
The energy storage benefit evaluation module 7 is respectively connected with the LNG circulating pump 2, the cryogenic circulating module 4, the electric three-way valve 9 and the cold energy power generation unit 8, wherein the electric three-way valve 9 is installed on a branch line of an output pipeline, a first branch line of the electric three-way valve 9 is communicated with the cold energy power generation unit 8, and a second branch line of the electric three-way valve 9 is communicated with the LNG distribution branch pipe system 10.
A cryogenic energy storage method based on an LNG tank comprises the following steps:
the LNG process flow of the energy storage system is as follows: starting an LNG circulating pump 2 at the bottom layer of an LNG storage tank 1 and starting a cryogenic circulating module 4 (judging logic according to an energy storage benefit evaluation module 7), wherein LNG is discharged from a discharge pipe of the LNG storage tank 1, is subjected to cryogenic cooling through a heat exchanger 3 and then flows back from the top of the LNG storage tank 1 through a cryogenic return pipeline, and a return pipe inlet I and an LNG circulating pump suction inlet II are arranged in a diagonal manner, so that the maximum distance is formed between the LNG circulating pump suction inlet II and the cryogenic LNG return pipe inlet I, and the effective mixing effect of the LNG in the LNG storage tank 1 is realized; judging logic according to the energy storage benefit evaluation module 7, and opening a first branch of an electric three-way valve 9 to a cold energy power generation unit 8 when LNG cold energy power generation is needed; when the LNG needs to be sold, the second branch of the electric three-way valve 9 is opened to the LNG distribution branch piping system 10.
As shown in fig. 2, the method for deep cooling energy storage logic and setting cryogenic temperature in the energy storage benefit evaluation module 7: the energy storage benefit evaluation module 7 takes evaluation information such as the rated input power of the cryogenic cycle module 4, the rated output power of LNG cold energy power generation, LNG storage tank parameters, LNG price sales information, power grid peak/valley price information and the like as logic input values of the energy storage benefit evaluation module 7, compares benefit values and intelligently calculates under an intelligent priority logic A model and a logic B model of the energy storage benefit evaluation module 7, determines whether cryogenic operation of the LNG storage tank 1 is executed or not according to logic, and determines the cryogenic set temperature of the LNG after cryogenic energy storage. And under logic, the cryogenic temperature of the LNG storage tank 1 is set to a certain value T in a certain temperature interval, namely the target for the cryogenic energy storage of the LNG storage tank and the temperature of the LNG after cryogenic temperature.
The energy storage benefit evaluation module intelligent logic A: calculating rated input power of a cryogenic cycle module 4 and a power grid valley electricity price constant, comparing rated output power of cold energy power generation corresponding to the LNG and a power grid peak electricity price to judge whether LNG cryogenic energy storage power generation is valuable or not, and determining a cryogenic temperature value T by combining parameters (capacity performance and the like) of an LNG storage tank 1 2 (e.g., between-160 ℃ and-172 ℃).
Under the logic A, the value of the cryogenic energy storage power generation is judged by assuming the intelligent calculation of the energy storage benefit evaluation module 7, and when the value can be executed, the temperature of the LNG storage tank is set to a certain value T within the range from-160 ℃ to-172 ℃ after the intelligent logic calculation 2 ，T 2 The temperature control module 6 passes the set value T as the temperature control target of the energy storage system 2 And T 1 And comparing, performing temperature PID regulation cryogenic operation, and outputting an instruction to the cryogenic circulation module 4 for temperature control. When the energy storage benefit evaluation module judges that the logic A judges that the peak value of the power grid can release the deep cooling power generation, a first branch of the electric three-way valve 9 is opened to the cold energy power generation unit 8, and the LNG cold energy power generation is started.
The energy storage benefit evaluation module intelligent logic B: { the value of high-quality LNG is reflected in that the LNG composition is stable after cryogenic cooling, no temperature rise and no gasification loss, and lower-temperature (such as from-160 ℃ to-165 ℃) LNG is convenient to transport and store for distribution and is more easily sold, so that the value-added benefit of LNG is reflected }. When the power grid valley electricity price appears, the rated input power of the LNG cryogenic cycle module 4, the power grid valley electricity price and the expected time constant (namely the LNG storage tank maintains low temperature T) are compared according to the price information of LNG sales (different stages) at the same time 3 The generated valley electricity fee), comparing the high-quality sales appreciation in the LNG expected time, starting the LNG cryogenic circulation module 4 when the value of the LNG stored in the cryogenic storage is comprehensively judged to be up, and determining the cryogenic storage temperature T of the LNG storage tank 1 according to the logic B 3 (if from-160 ℃ to-165 ℃), and the LNG storage tank is maintained at T by performing LNG storage tank temperature control on the cryogenic cycle module 4 3 . Under the judgment logic B of the energy storage benefit evaluation module, when the LNG high-price selling condition is judged to be satisfied (when the expected selling price is reached), high-quality LNG can be sold, the selling value of the LNG is increased, and the energy storage benefit evaluation module 7 opens the second branch of the electric three-way valve 9 to the LNG distribution branch pipe system 10 for selling.
If under logic B, the initial LNG storage tank comprehensively evaluates the temperature T 1 The temperature is higher than-160 ℃, the energy storage temperature control module 6 PID regulates the output power of the cryogenic equipment, namely, the cryogenic refrigeration action is carried out, and the temperature value T set after the logic calculation of the energy storage benefit evaluation module 7 is continuously compared 3 Carrying out PID control cryogenic cycle equipment, and maintaining the temperature of the LNG storage tank 1 at T 3 The value is obtained. Realize LNG storage tank 1 through 4 circulation refrigeration operations of cryrogenic circulation module, LNG storage tank 1 realizes the energy storage effect at lower low temperature, through the temperature is automaticAnd the working condition of system temperature regulation is stable through control.
And if the intelligent logic A of the energy storage benefit evaluation module and the intelligent logic B of the energy storage benefit evaluation module are judged to be out of order, the LNG storage tank 1 restores the original natural storage state.
The constants in the present invention are benefit constants.
The LNG cold energy power generation refers to a process for gradually releasing available cold energy through a medium by utilizing LNG low temperature, the medium is used for power generation, the existing method can be used, and similar technologies can refer to documents such as 'research on LNG cold energy power generation systems based on low temperature Rankine cycle' (author Xu Jiawei).
The LNG cryogenic cycle refrigeration refers to LNG cryogenic operation by using an inverse Brayton refrigeration cycle method, the method can be used, and similar technologies can be referred to in low-temperature engineering journal (2004-03, author Lin Bihong) of 'performance optimization of irreversible Brayton refrigeration cycle' and in low-temperature and characteristic journal (2016-10 author Chen Jianjun) of 'an inverse Brayton refrigeration cycle stepless regulation technology and industrial summary' of the document.
Peak/valley difference of the grid: the load and price of the power grid generally fluctuate with time and seasons, for example, the power demand is in the daytime and in winter and summer Ji Duo, otherwise, the power demand is less at night and in spring and autumn, the different power prices of the load of the power grid are different, and the peak/valley power price difference creates conditions for the energy storage of the LNG storage tank 1; and comparing the cryogenic storage-power generation energy storage benefit with the cryogenic storage-sales high-benefit LNG according to logic judgment, and if the cryogenic storage-sales high-quality LNG benefit is greater than the cryogenic storage-power generation energy storage benefit, performing cryogenic storage on the LNG quality in the storage tank, and selling the high-quality LNG at a proper time.
High-benefit LNG sales: the LNG storage tank is subjected to cryogenic storage, so that the LNG vaporization loss can be prevented, the LNG temperature is kept at a cryogenic lower temperature (the LNG temperature is kept from minus 160 ℃ to minus 165 ℃), the LNG quality can be improved without changing the LNG components, the LNG liquid state high selling price is realized for LNG sales, and the LNG storage tank has a good energy storage significance.
The design scheme of the invention develops the control algorithm of the energy storage evaluation module aiming at different influences of factors such as working condition temperature variable of the LNG storage tank, cryogenic circulating equipment energy consumption, cryogenic utilization power generation benefit, electricity price difference, LNG sales price information and the like on the system, and the environment variables are different under different working modes, thereby forming the high-efficiency decision of the cryogenic energy storage and storage system of the LNG storage tank.
The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should be covered by the present patent.
Claims (10)
1. The utility model provides a cryrogenic energy storage system based on LNG jar which characterized in that: the LNG circulating pump is positioned in the LNG storage tank, an output port of the LNG circulating pump is communicated with an input end of a heat exchanger through an output pipeline, and an output end of the heat exchanger is communicated with the LNG storage tank through a cryogenic reflux pipeline to form a heat exchange loop; the temperature control module is respectively connected with the temperature measurement and evaluation unit and the cryogenic cycle module, the temperature measurement and evaluation unit is connected with a temperature detection instrument in the LNG storage tank, and the cryogenic cycle module is connected with the heat exchanger to realize temperature control; and the energy storage benefit evaluation module is respectively connected with the LNG circulating pump, the cryogenic circulating module, the three-way valve and the cold energy power generation unit, so that benefit evaluation is realized.
2. The cryogenic energy storage system based on an LNG tank of claim 1, wherein: and the return pipe inlet of the cryogenic return pipeline and the LNG circulating pump suction inlet are arranged diagonally.
3. The cryogenic energy storage system based on an LNG tank of claim 1, wherein: the three-way valve is arranged on a branch line of the output pipeline, a first branch of the three-way valve is communicated with the cold energy power generation unit, and a second branch of the three-way valve is communicated with the LNG distribution branch pipe system.
4. An energy storage method of a cryogenic energy storage system based on LNG tanks according to any of claims 1-3, characterized by: the method comprises the following steps: according to the judgment logic of the energy storage benefit evaluation module, an LNG circulating pump and a cryogenic circulation module are started, LNG is discharged from an LNG storage tank, is subjected to cryogenic treatment through a heat exchanger, and then flows back to the LNG storage tank through a cryogenic return pipeline, and then according to the judgment logic of the energy storage benefit evaluation module, the LNG goes to a cold energy power generation unit when LNG cold energy power generation is needed; when LNG needs to be sold, LNG is distributed to LNG branch piping.
5. The energy storage method of a cryogenic energy storage system based on an LNG tank according to claim 4, characterized in that: the LNG storage tank temperature is comprehensively judged through the temperature measurement and evaluation unit module, the temperature detection instrument is arranged at the upper part, the middle part and the bottom part, the multipoint temperature values of the LNG storage tank are collected, the temperature is obtained through weighted average calculation, and the temperature is the evaluation temperature T of the LNG storage tank 1 The evaluation temperature T 1 The value will be the input signal to the temperature control module.
6. The energy storage and storage method of a cryogenic energy storage system based on an LNG tank of claim 5, wherein: energy storage benefit evaluation module will be according to the rated input power of cryrogenic circulation module, LNG cold energy power generation rated output power, LNG storage tank parameter, LNG price sales information, the evaluation information of electric wire netting peak/millet price information is as the logic input value of energy storage benefit evaluation module, carry out benefit value comparison and intelligent calculation under energy storage benefit evaluation module intelligence logic A and energy storage benefit evaluation module intelligence logic B model, decide whether to carry out according to logic LNG storage tank cryrogenic operation, and decide cryogenic energy storage back LNG cryrogenic and set for the temperature, certain value T in certain temperature interval is set for to LNG storage tank cryrogenic temperature under the logic.
7. Cryogenic energy storage based on LNG tanks according to claim 6The stored energy storage method of the system is characterized in that: the energy storage benefit evaluation module intelligent logic A: calculating rated input power of a cryogenic cycle module and a power grid valley electricity price constant, comparing rated output power of cold energy power generation corresponding to the LNG and a power grid peak electricity price to judge whether LNG cryogenic energy storage power generation is valuable or not, and determining a temperature value T after cryogenic treatment by combining with LNG storage tank parameters 2 。
8. The energy storage method of a cryogenic energy storage system based on an LNG tank according to claim 7, characterized in that: the energy storage benefit evaluation module intelligently calculates and judges that the cryogenic energy storage power generation is valuable and can be executed, and the temperature is set at T after the intelligent logic calculation of the LNG storage tank 2 ，T 2 The temperature control module is used as an energy storage system temperature control target and passes through a set value T 2 And T 1 And comparing, performing temperature PID regulation cryogenic operation, outputting an instruction to a cryogenic circulation module for temperature control, and when judging that the peak value of the power grid can release cryogenic power generation, starting a first branch of a three-way valve to a cold energy power generation unit to start LNG cold energy power generation.
9. The energy storage method of a cryogenic energy storage system based on an LNG tank according to claim 6, characterized in that: the energy storage benefit evaluation module intelligent logic B: when the power grid valley electricity price occurs, comparing the rated input power of the LNG cryogenic circulation module with the power grid valley electricity price and the expected time constant according to the LNG sales price information, comparing the high-quality sales appreciation in the LNG expected time, starting the LNG cryogenic circulation module when the value of the LNG stored in the cryogenic circulation module is comprehensively judged to be established, and determining the cryogenic storage temperature T of the LNG storage tank according to the intelligent logic B of the energy storage benefit evaluation module 3 And the temperature of the LNG storage tank is controlled by the cryogenic circulation module, and the LNG storage tank is maintained at T 3 And under the intelligent logic B of the energy storage benefit evaluation module, when the LNG high-price selling condition is judged to be met, high-quality LNG selling can be carried out, the LNG selling value is increased, and the energy storage benefit evaluation module opens the second branch of the three-way valve to the LNG distribution branch pipe system for selling.
10. The energy storage method of a cryogenic energy storage system based on an LNG tank according to claim 6, characterized in that: and if the intelligent logic A of the energy storage benefit evaluation module and the intelligent logic B of the energy storage benefit evaluation module are judged to be out of order, the LNG storage tank restores the original natural storage state.
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