KR102765697B1 - High-efficiency air liquefaction energy storage system and control method thereof - Google Patents

Abstract

The present invention relates to a high-efficiency air liquefaction energy storage system and a control method thereof.
Specifically, in a high-efficiency air liquefaction energy storage system, the air liquefaction energy storage system includes a liquefied air forming unit including a pre-cooling heat exchanger and a condenser for liquefying air drawn in from the atmosphere, a liquefied air storage unit for storing liquefied air formed in the liquefied air forming unit, and an air power generation and cooling unit including a vaporizer and a cooler for generating and cooling the liquefied air stored in the liquefied air storage unit and supplying it to a demander, and the high-efficiency air liquefaction energy storage system is characterized in that one heat transfer medium circulates through the liquefied air forming unit and the air power generation and cooling unit to cool and heat the air.

Description

High-efficiency air liquefaction energy storage system and control method thereof

The present invention relates to a high-efficiency air liquefaction energy storage system and a control method thereof.

Specifically, the present invention relates to a high-efficiency air liquefaction energy storage system and a control method thereof, which can efficiently utilize a heat transfer medium (a liquid heat storage material) that can simultaneously perform the functions of a heat storage medium and a heat transfer medium in the entire cycle, such as air liquefaction, power generation, and cooling using clean air.

Liquid Air Energy Storage (LAES) for large-scale energy storage is divided into air liquefaction and air power generation. Air liquefaction is the liquefaction of ultra-low temperature gas, and the ultra-low temperature gas is liquefied by applying a refrigeration cycle (Claude, Brayton, Linde-Hampson, etc.), and air power generation is achieved through an open rankine cycle.

In order to reduce the compressor energy required in the air liquefaction process, low-temperature cold heat utilization is required, and the cold heat required at this time can be obtained through a heat exchange method during the re-gasification of liquefied air for the air power generation process. In addition, in order to produce more energy per unit mass in the air power generation process, heat utilization is required, and the necessary heat at this time can be obtained by recovering waste heat or heat generated during the compression process for air liquefaction.

At this time, it is a very difficult technology to store the cryogenic heat and utilize it when needed, and in this process, heat loss occurs during the insulation process after storing the cold heat, and a very large amount of energy loss occurs during the process of circulating a separate heat transfer medium to store the cold heat or utilize the stored cold heat.

In the case of the conventional cold storage and utilization process, the energy required to compress and circulate the gaseous heat transfer medium is approximately 20% of the power generation output, and considering that the round trip efficiency (RTE) of the liquid air energy storage system (LAES) is realistically around 50%, this has the effect of reducing the round trip efficiency (RTE) by approximately 10%.

Therefore, in order to reduce these negative effects, liquid-state cold storage media have been developed that can simultaneously perform the roles of cold storage and heat transfer media. At this time, in order for the cold storage media to simultaneously perform the roles of cold storage and heat transfer media, first, the possibility of fire and explosion should be low and the environmental impact should be small. Second, as a cold storage media, it should have a high specific heat. Third, as a heat transfer media, it should have a very low freezing point and a high vaporization point. Fourth, the density should be high, so that the storage volume is small, and the land utilization cost and facility investment cost should be low.

However, there is no material that satisfies all of the above requirements at extremely low temperatures, but there are materials that satisfy them to some extent, such as propane, methanol, and HFE (Hydro Fluoro Ether).

For propane, the freezing point is -188℃ at normal pressure, the vaporization point is -42℃, and the temperature range in which cold heat can be stored in the liquid phase is -188℃ to -42℃. For methanol, the freezing point is -97.6℃ at normal pressure, the vaporization point is 64.7℃, and the temperature range in which cold heat can be stored in the liquid phase is -97.6℃ to 64.7℃, making it a substance that partially satisfies the second and third conditions of the above requirements.

Specifically, when liquefied air is regasified, the temperature changes from -192℃ to -188℃ to room temperature, and propane and methanol are used together to store cold energy in the temperature range of -188℃ to -50℃ using propane, and to store cold energy in the temperature range of -50℃ to room temperature using methanol. However, methanol has the disadvantage of having a risk of fire and explosion and requiring a large storage volume due to its low density in the liquid state.

Meanwhile, HFE series substances are artificial chemicals developed as substitutes for CFC and HCFC series refrigerants, and are recently being used in special refrigeration processes such as ultra-low temperature cooling in semiconductor processes. Various products exist depending on the manufacturer's molecular synthesis method, and HFE-7200 (C ₄ F ₉ OC ₂ H ₅ ) is a representative example. In the case of HFE-7200, the freezing point is below -138℃ at normal pressure, and the vaporization point is 76℃, so the temperature range in which cold energy can be stored in a liquid state is -138℃ to room temperature.

Although its relatively high freezing point of -138℃ may be a major disadvantage, it has a significantly low risk of fire or explosion, satisfies environmental regulations, and has the advantage of having a density of 1798.8 kg/m3 at -138℃, which is 2.63 times that of propane.

In addition, unlike propane/methanol, HFE can be considered an economical and efficient cold storage material because it only requires one substance, except for its relatively high freezing point. In addition, the freezing point of HFE series can be lowered in the future through freezing point depression by dissolving non-volatile additives that disrupt intermolecular bonding in a process other than changing the molecular bonding structure through technological development according to demand.

As one of the large-capacity energy storage systems, the air liquefaction energy storage system is a system that stores energy through air liquefaction and produces electricity through liquid air power generation. The biggest disadvantage of the air liquefaction energy storage system is that its overall efficiency is lower than that of pumped storage power generation and compressed air energy storage.

Overall efficiency is defined as the ratio of the power that can be obtained in the power generation process to the power consumed in the energy storage process. The air liquefaction energy storage system has low efficiency due to limitations in the performance coefficient of the refrigeration cycle required for liquefaction and utilization of cold heat.

That is, in order to utilize the stored cold heat, a separate working fluid must be circulated, and usually the circulating heat medium is pressurized by a compressor in a gaseous state and used when storing or utilizing the cold heat.

Since the energy consumption of the compressor is very large during this process, it has the effect of reducing the RTE by about 10%.

In order to solve the above problems, the present invention aims to provide a high-efficiency air liquefaction energy storage system utilizing a liquid cold storage material and a control method thereof.

Specifically, the purpose is to provide a high-efficiency air liquefaction energy storage system and a control method thereof for effectively utilizing one or more liquid refrigeration storage materials capable of simultaneously performing the functions of heat storage and heat transfer medium in the entire cycle process such as air liquefaction, power generation, and air conditioning.

Specifically, the purpose is to provide a high-efficiency air liquefaction energy storage system using a liquid liquefaction energy storage material that can be used as a cold storage and heat transfer medium by applying propane and methanol to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

In addition, the purpose is to provide a high-efficiency air liquefaction energy storage system using liquid cold storage materials that can be used as a cold storage and heat transfer medium by applying HFE series materials to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the description below.

According to one aspect of the present invention for achieving the above object, in a high-efficiency air liquefaction energy storage system, the air liquefaction energy storage system includes a liquefied air forming unit including a pre-cooling heat exchanger and a condenser for liquefying air drawn in from the atmosphere, a liquefied air storage unit for storing the liquefied air formed in the liquefied air forming unit, and an air power generation and cooling unit including a vaporizer and a cooler for generating and cooling the liquefied air stored in the liquefied air storage unit and supplying it to a demander, and the high-efficiency air liquefaction energy storage system provides a high-efficiency air liquefaction energy storage system in which one heat transfer medium circulates through the liquefied air forming unit and the air power generation and cooling unit to cool and heat the air.

Preferably, the pre-cooling heat exchanger can perform primary cooling by heat-exchanging air taken in from the atmosphere with a heat transfer medium, and the condenser can form liquefied air by heat-exchanging the primary cooled air with the heat transfer medium.

Preferably, the liquefied air forming unit further includes a gas-liquid separator; the gas-liquid separator separates the liquefied air supplied from the condenser into liquefied air and gaseous air, the liquefied air separated from the gas-liquid separator is supplied to a liquefied air storage unit and stored, the gaseous air is re-supplied to the condenser and the pre-cooling heat exchanger and heated, and the heated air may be discharged to the atmosphere.

Preferably, the air generation cooling unit may further include a multi-stage expansion unit, which may perform multi-stage expansion of air vaporized in the vaporizer and supply the multi-stage expanded air to the cooler.

Preferably, the high-efficiency air liquefaction energy storage system comprises a heat transfer medium storage tank, a first heat transfer medium storage tank storing a heat transfer medium heated by passing through the pre-cooling heat exchanger, and a second heat transfer medium storage tank storing a heat transfer medium cooled by passing through the cooler and vaporizer, and the cooled heat transfer medium stored in the second heat transfer medium storage tank may be supplied to a condenser.

Preferably, the heat transfer medium may be one selected from hydrofluoro ether (HFE), ethyl perfluorobutyl ether, and carbon fluorine compounds.

According to another aspect of the present invention for achieving the above-mentioned object, a high-efficiency air liquefaction energy storage system is provided, wherein the air liquefaction energy storage system includes a liquefied air forming unit including a pre-cooling heat exchanger and a condenser to liquefy air drawn in from the atmosphere, a liquefied air storage unit storing the liquefied air formed in the liquefied air forming unit, and an air power generation and cooling unit including a first vaporizer, a second vaporizer, and a cooler to generate and cool the liquefied air stored in the liquefied air storage unit and supply it to a demander, wherein the high-efficiency air liquefaction energy storage system provides a high-efficiency air liquefaction energy storage system in which a first heat transfer medium and a second heat transfer medium simultaneously circulate through the liquefied air forming unit and the air power generation and cooling unit to cool and heat the air.

Preferably, the high-efficiency air liquefaction energy storage system includes a heat transfer medium storage tank, a third heat transfer medium storage tank storing a first heat transfer medium that has passed through the pre-cooling heat exchanger and been heated, a fourth heat transfer medium storage tank connected to the third heat transfer medium storage tank and storing a first heat transfer medium that has passed through the cooler and the second vaporizer and been cooled, a fifth heat transfer medium storage tank storing a second heat transfer medium that has passed through the condenser and been heated, and a sixth heat transfer medium storage tank connected to the fourth heat transfer medium storage tank and storing a second heat transfer medium that has passed through the first vaporizer and been cooled, and the first heat transfer medium stored in the fourth heat transfer medium storage tank may be supplied to the pre-cooling heat exchanger, and the second heat transfer medium stored in the sixth heat transfer medium storage tank may be supplied to the condenser.

Preferably, the temperature range for storing the cold heat of the first heat transfer medium is higher than the temperature range for storing the cold heat of the second heat transfer medium, and the first heat transfer medium may be one selected from alcohol compounds, and the second heat transfer medium may be one selected from hydrocarbon-based materials.

According to another aspect of the present invention for achieving the above-mentioned object, a method for controlling a high-efficiency air liquefaction energy storage system is provided, including a liquefied air forming step of supplying air introduced into a liquefied air forming unit from the atmosphere to a pre-cooling heat exchanger and a condenser to form liquefied air, a liquefied air storage step of storing the formed liquefied air in a liquefied air storage unit, and an air power generation and cooling step of supplying the liquefied air stored in the liquefied air storage unit to a vaporizer and a cooler of an air power generation and cooling unit to cool and generate power and supply it to a demander, wherein the high-efficiency air liquefied energy storage system includes a heat transfer medium circulation step of cooling and heating the air by circulating a single heat transfer medium through the liquefied air forming unit and the air power generation and cooling unit.

Preferably, the liquefied air forming step may include a precooling step of supplying air drawn in from the atmosphere to a precooling heat exchanger and performing heat exchange with a heat transfer medium to perform primary cooling, a condensing step of supplying the primary cooled air to a condenser and performing heat exchange with a heat transfer medium to form condensed liquefied air, and a gas-liquid separation step of supplying the condensed liquefied air to a gas-liquid separator to separate liquefied air and gaseous air.

Preferably, the liquefied air separated in the above-described gas-liquid separation step may be supplied to an air power generation and cooling unit to perform an air power generation and cooling step, and the gaseous air may be re-supplied to the condenser and pre-cooling heat exchanger to be heated and then released into the atmosphere.

Preferably, the heat transfer medium circulation step includes a first heat transfer medium storage step of storing the heat transfer medium heated by passing through the pre-cooling heat exchanger in a first heat transfer medium storage tank, and a second heat transfer medium storage step of storing the heat transfer medium cooled by passing through the cooler and vaporizer in a second heat transfer medium storage tank, and the cooled heat transfer medium stored in the second heat transfer medium storage tank may be sequentially supplied to the condenser and the pre-cooling heat exchanger.

According to another aspect of the present invention for achieving the above-described object, a method for controlling a high-efficiency air liquefaction energy storage system is provided, including a liquefied air forming step of supplying air introduced into a liquefied air forming unit from the atmosphere to a pre-cooling heat exchanger and a condenser to form liquefied air, a liquefied air storage step of storing the formed liquefied air in a liquefied air storage unit, and an air power generation and cooling step of supplying the liquefied air stored in the liquefied air storage unit to a first vaporizer, a second vaporizer and a cooler of an air power generation and cooling unit to cool and generate power and supply it to a demander, wherein the high-efficiency air liquefied energy storage system includes a heat transfer medium circulation step in which a first heat transfer medium and a second heat transfer medium circulate through the liquefied air forming unit and the air power generation and cooling unit to cool and heat the air.

Preferably, the heat transfer medium circulation step includes a third heat transfer medium storage step for storing the first heat transfer medium heated by passing through the pre-cooling heat exchanger in a third heat transfer medium storage tank, a fourth heat transfer medium storage step connected to the third heat transfer medium storage tank and storing the first heat transfer medium cooled by passing through the cooler and the second vaporizer in a fourth heat transfer medium storage tank, a fifth heat transfer medium storage step for storing the second heat transfer medium heated by passing through the condenser in a fifth heat transfer medium storage tank, and a sixth heat transfer medium storage step connected to the fifth heat transfer medium storage tank and storing the second heat transfer medium cooled by passing through the first vaporizer in a sixth heat transfer medium storage tank, and the first heat transfer medium stored in the fourth heat transfer medium storage tank may be supplied to the pre-cooling heat exchanger, and the second heat transfer medium stored in the sixth heat transfer medium storage tank may be supplied to the condenser. there is.

The present invention has the effect of providing a high-efficiency air liquefaction energy storage system utilizing a liquid cold storage material and a control method thereof.

Specifically, the present invention provides a high-efficiency air liquefaction energy storage system using a liquid liquefaction energy storage material that can be used as a cold storage and heat transfer medium by applying propane and methanol to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

In addition, by applying propane and methanol to the air liquefaction energy storage system, district cooling can be performed using clean air that meets the requirements of the demand site without additional power consumption, and the degree of freedom in turbine operation conditions in the power generation process can be increased.

In addition, there is an effect of providing a high-efficiency air liquefaction energy storage system using a liquid cold storage material that can be used as a cold storage and heat transfer medium by applying HFE series materials to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

In addition, by applying HFE series materials to liquid air energy storage systems (LAES), environmental issues can be resolved, and by performing the role of cold storage and heat transfer medium with a single high-density material, the required land area can be reduced, storage volume can be reduced, and facility investment costs can be reduced.

In addition, HFE is chemically stable and has a low risk of fire or explosion, so even if a gas leak occurs during operation, it does not lead to a major accident.

In addition, since the heat transfer medium (cold storage material) is circulated through the system, it is economical as it does not require additional facility investment or energy consumption as it does not utilize a cooling tower for cooling water circulation or use a separate chiller.

In addition, the air temperature at the turbine outlet can be independent of the final exhaust temperature for district cooling, which provides freedom in turbine operating conditions and enables stable power generation process operation.

In addition, it has the effect of being able to supply the final exhaust temperature for district cooling at a very low temperature.

Further scope of the applicability of the present invention will become apparent from the detailed description below. However, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art, it should be understood that the detailed description and specific examples, such as preferred embodiments of the present invention, are given by way of example only.

FIG. 1 is a drawing showing a high-efficiency air liquefaction energy storage system utilizing one heat transfer medium according to one embodiment of the present invention.
FIG. 2 is a drawing showing a high-efficiency air liquefaction energy storage system utilizing two heat transfer media according to one embodiment of the present invention.

The purpose and technical configuration of the present invention and the detailed operation and effect thereof will be more clearly understood by the detailed description based on the drawings attached to the specification of the present invention.

The terms used in this specification are used only to describe specific embodiments and are not intended to limit the invention. For example, when a component is said to "include" in this specification, unless specifically stated otherwise, it does not exclude other components, but rather means that other components may be included.

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the attached drawings. The embodiments described below are provided so that those skilled in the art can easily understand the technical idea of the present invention, and should not be construed as limiting the present invention thereby, and it is obvious that the embodiments of the present invention can have various applications to those skilled in the art.

FIG. 1 is a drawing showing a high-efficiency air liquefaction energy storage system using one heat transfer medium according to one embodiment of the present invention, and FIG. 2 is a drawing showing a high-efficiency air liquefaction energy storage system using two heat transfer media according to one embodiment of the present invention.

Referring to Fig. 1, a high-efficiency air liquefaction energy storage system may be configured to include a liquefied air forming unit, a liquefied air storage unit, and an air power generation cooling unit. At this time, the high-efficiency air liquefaction energy storage system is characterized in that one heat transfer medium circulates through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.

The above liquefied air forming unit liquefies air taken in from the atmosphere and may include a pre-cooling heat exchanger (205) and a condenser (206).

The above pre-cooling heat exchanger (205) can perform primary cooling by exchanging heat with air drawn in from the atmosphere with a heat transfer medium. Specifically, the pre-cooling heat exchanger (205) includes one stage of a hot stream and two stages of a cold stream, and it is preferable that the air drawn in from the atmosphere is introduced into the hot stream and the heat transfer medium introduced into the cold stream is circulated at the rear end of the expansion turbine (207) and the gas-liquid separator (209) and the low temperature air that has passed through the condenser (206) is first cooled.

At this time, air drawn in from the atmosphere is supplied to the pre-cooling heat exchanger (205) along the first air supply line, and a low-pressure compressor (201), an intermediate cooler (202), a high-pressure compressor (203), and a post-cooler (204) are arranged on the first air supply line. Before being supplied to the pre-cooling heat exchanger (205), it is preferable to compress and cool the air to the pressure and temperature required by the pre-cooling heat exchanger (205) through the low-pressure compressor (201), the intermediate cooler (202), the high-pressure compressor (203), and the post-cooler (204).

The above condenser (206) is connected to the pre-cooling heat exchanger (205) through a second air supply line, and can form liquefied air by receiving air that has been primarily cooled from the pre-cooling heat exchanger (205) and condensing it through heat exchange with the heat transfer medium.

In detail, the condenser (206) includes one hot stream and two cold streams, and it is preferable that the primary cooled air is introduced into the hot stream and heat-exchanged with the heat transfer medium introduced into the cold stream and the low temperature air circulated and supplied from the rear end of the expansion turbine (207) and the gas-liquid separator (209) to condense the primary cooled air.

At this time, the pre-cooling heat exchanger (205) and condenser (206) may be manufactured as one heat exchanger.

Meanwhile, the condensed air that has passed through the condenser (206) is in a high-pressure supercritical state but is close to a liquid state. Accordingly, the condensed air in a high-pressure supercritical state will be referred to as a liquid state and liquefied air hereinafter.

The above condenser (206) may be connected to the gas-liquid separator (209) and the third air supply line. In addition, an expansion valve (208) may be arranged on the third air supply line to store the high-pressure supercritical state condensed air that has passed through the condenser (206) at a low pressure.

In detail, the high-pressure liquefied air that has passed through the condenser (206) passes through the expansion valve (208) and becomes a two-phase state in which low-pressure liquid and gas that can be stored in large quantities coexist.

Thereafter, the two-phase air in which the low-pressure liquid and gas are in rotation is supplied to the gas-liquid separator (209) and separated into liquid air (liquefied air) and gaseous air. The liquefied air separated in the gas-liquid separator (209) is supplied to a liquefied air storage unit and stored, and the gaseous air can be resupplied to the condenser (206) and the pre-cooling heat exchanger (205).

Specifically, it is preferable that the gaseous air separated in the gas-liquid separator (209) is supplied to the cold stream of the condenser (206) and the pre-cooling heat exchanger (205), and is heated to a temperature close to room temperature by heat exchange with the air in the atmosphere supplied to the hot stream of the condenser (206) and the pre-cooling heat exchanger (205) and then discharged to the atmosphere.

Accordingly, the lower part of the gas-liquid separator (209) is connected to the liquefied air storage unit and the fourth air supply line, the upper part of the gas-liquid separator (209) is connected to the cold stream of the condenser (206) and the fifth air supply line, and the cold stream of the condenser (206) can be connected to the cold stream of the pre-cooling heat exchanger (205) and the sixth air supply line. In addition, the air heated while passing through the cold stream of the pre-cooling heat exchanger (205) can be discharged into the atmosphere through the seventh air supply line.

Meanwhile, some of the air that has been first cooled in the pre-cooling heat exchanger (205) is supplied to the condenser (206), and some of the air is branched off from the second air supply line and supplied to the cryogenic expander (207). The first cooled air supplied to the cryogenic expander (207) is expanded to have a temperature lower than that of the liquefied air, separated in the gas-liquid separator (209), and the flow is merged with air in a gaseous state having the same temperature as that of the liquefied air, and is re-supplied to the condenser (206) in a state where the average temperature is lower than that of the liquefied air, thereby liquefying the air. Thereafter, the air is continuously re-supplied to the pre-cooling heat exchanger (205) to pre-cool the air after the rear cooler (204).

The above liquefied air storage unit stores liquefied air formed in the liquefied air forming unit, and it is preferable to store the generated liquefied air in the liquefied air storage tank (101).

The above air power generation and cooling unit generates and cools liquefied air stored in the liquefied air storage unit and supplies it to a demand source. The air power generation and cooling unit may include a vaporizer (104) and a cooler (109).

The above vaporizer (104) heats the liquefied air stored in the liquefied air storage tank (101) by exchanging heat with a heat transfer medium, thereby vaporizing the liquefied air.

In addition, the vaporizer (104) is connected to the liquefied air storage tank (101) and the first liquefied air supply line, and it is preferable that the first liquefied air pump (102) and the first flow rate control valve (103) are arranged on the first liquefied air supply line.

Specifically, the liquefied air supplied to the vaporizer (104) passes through the first liquefied air pump (103) and is pressurized and then supplied to the cold stream of the vaporizer (104). It is preferable that the air condition of the cold stream at the outlet of the vaporizer (104) be a supercritical state (about 38 bar or more at room temperature) for high efficiency during the power generation process.

The air heated in the above vaporizer (104) is cooled in the cooler (109) and then supplied to a demand location requiring cooling. The vaporizer (104) and the cooler (109) can be connected to the eighth air supply line. At this time, the air supplied from the vaporizer (104) to the cooler (109) is used for power generation. A multi-stage expansion unit may be further included on the eighth air supply line.

In detail, the multi-stage expansion unit may include a first heater (105), a first turbine (106), a second heater (107), and a second turbine (108). At this time, the multi-stage expansion unit is described as an example of the first turbine (106) and the second turbine (108), but the number of turbines may increase depending on the pressure range required for cooling, and there is no limitation thereto.

Meanwhile, the above air power generation cooling unit is intended for power generation and district cooling using clean air at the turbine outlet. In order to increase power generation, the turbine inlet temperature (TIT) must be increased. However, the turbine outlet temperature is proportional to the TIT, so the power generation amount and the district cooling effect are inversely proportional. To this end, a cooler (109) is used to increase the turbine inlet temperature while not reducing the district cooling effect, and a heat transfer medium is utilized as a means for cooling in the cooler (109).

Accordingly, the high-efficiency air liquefaction energy storage system of the present invention can be configured to include a heat transfer medium storage tank that stores a heat transfer medium.

It is characterized by including a first heat transfer medium storage tank (501) and a second heat transfer medium storage tank (504) that circulate through a vaporizer (104), a cooler (109), a condenser (206) and a pre-cooling heat exchanger (205) in an air liquefaction energy system to perform heat exchange with air, and storing the heat transfer medium according to the temperature of the heat transfer medium.

Specifically, in order for the heat transfer medium to circulate through the vaporizer (104), the cooler (109), the condenser (206), and the pre-cooling heat exchanger (205), the first heat transfer medium storage tank (501) is connected to the cold stream of the pre-cooling heat exchanger (205) and the first heat transfer medium supply line, the cold stream of the cooler (109) and the second heat transfer medium supply line, the cold stream of the cooler (109) is connected to the hot stream of the vaporizer (104) and the third heat transfer medium supply line, and the hot stream of the vaporizer (104) is connected to the second heat transfer medium storage tank (504) and the fourth heat transfer medium supply line.

At this time, the heat transfer medium heated through heat exchange in the pre-cooling heat exchanger (205) is stored in the first heat transfer medium storage tank (501), and it is preferable that the heat transfer medium stored in the first heat transfer medium storage tank (501) is supplied to the cooler (109) to perform heat exchange with the air passing through the multi-stage expansion unit.

In addition, it is preferable that a first heat transfer medium supply pump (502) and a first heat transfer medium flow rate control valve (503) are arranged on the second heat transfer medium supply line to supply the heat transfer medium stored in the first heat transfer medium storage tank (501) to the cooler (109).

The heat transfer medium supplied to the above cooler (109) is heated by heat exchange with air, and it is preferable to supply the heated heat transfer medium to the hot stream of the vaporizer (104) along the third heat transfer medium supply line.

The heat transfer medium supplied as a hot stream of the vaporizer (104) exchanges heat with the low-temperature air passing through the cold stream of the vaporizer (104), so that the heat transfer medium is cooled, and it is preferable to supply the cooled heat transfer medium to a second heat transfer medium storage tank (504) and store it.

The heat transfer medium stored in the second heat transfer medium storage tank (504) is heated by being supplied to the cold stream of the condenser (206), and the heat transfer medium heated by heat exchange in the cold stream of the condenser (206) can be heated by being supplied to the pre-cooling heat exchanger (205).

Accordingly, the cold stream of the second heat transfer medium storage tank (504) and the condenser (206) are connected to a fifth heat transfer medium supply line, the cold stream of the condenser (206) and the cold stream of the pre-cooling heat exchanger (205) are connected to a sixth heat transfer medium supply line, and it is preferable that a second heat transfer medium supply pump (505) and a second heat transfer medium flow rate control valve (506) are arranged on the fifth heat transfer medium supply line.

Meanwhile, it is preferable to use a liquid-phase cold storage material that can simultaneously perform the functions of heat storage and heat transfer medium by circulating within the system and cooling and heating the air as the heat transfer medium.

Specifically, in order for the heat transfer medium to simultaneously perform the functions of heat storage and heat transfer medium, it is preferable to use a material having a low freezing point, a high vaporization point, and a high specific heat and density.

For example, the heat transfer medium is one selected from hydrofluoro ether (HFE), ethyl perfluorobutyl ether, and a carbon fluorine compound, and it is preferable to use a compound having a molecular formula similar to C ₄ F ₉ OC ₂ H ₅ as the carbon fluorine compound.

Fig. 2 is another embodiment of the present invention to explain a high-efficiency air liquefaction energy storage system. In this case, the same components described above are given the same numbers as much as possible even if they are shown in different drawings, and detailed descriptions of the same components are replaced with those described above.

Referring to FIG. 2, a high-efficiency air liquefaction energy storage system is configured to include a liquefied air forming unit, a liquefied air storage unit, and an air power generation cooling unit, and the high-efficiency air liquefaction energy storage system is characterized in that two heat transfer media circulate through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.

The above air power generation cooling unit may be configured to include a first vaporizer (104-1), a second vaporizer (104-2), and a cooler (109) to cool and generate liquefied air stored in the liquefied air storage unit and supply it to a demand source.

In detail, the first vaporizer (104-1) heats the liquefied air stored in the liquefied air storage tank (101) by exchanging heat with a heat transfer medium, thereby allowing the liquefied air to be primarily vaporized.

The air that has been primarily vaporized in the first vaporizer (104-1) is supplied to the second vaporizer (104-2), and can be secondarily vaporized by exchanging heat with a heat transfer medium.

At this time, it is preferable that the heat transfer medium performing heat exchange in the first vaporizer (104-1) and the heat transfer medium performing heat exchange in the second vaporizer (104-2) use different heat transfer media.

Accordingly, the high-efficiency air liquefaction energy storage system of the present invention may be configured to include a plurality of heat transfer medium storage tanks to store different heat transfer media.

Specifically, the heat transfer medium includes a first heat transfer medium and a second heat transfer medium, and is characterized in that it circulates through a first vaporizer (104-1), a second vaporizer (104-2), a cooler (109), a condenser (206), and a pre-cooling heat exchanger (205) in the high-efficiency air liquefaction energy storage system and performs heat exchange with air.

Accordingly, the heat transfer medium storage tank is characterized by including a third heat transfer medium storage tank (301), a fourth heat transfer medium storage tank (304), a fifth heat transfer medium storage tank (401), and a sixth heat transfer medium storage tank (404) depending on the type and temperature of the heat transfer medium.

In detail, the first heat transfer medium is stored in the third heat transfer medium storage tank (301), the third heat transfer medium storage tank (301) is connected to the cold stream of the pre-cooling heat exchanger (205) and the seventh heat transfer medium supply line, and is connected to the cold stream of the cooler (109) and the eighth heat transfer medium supply line, the cold stream of the cooler (109) is connected to the hot stream of the second vaporizer (104-2) and the ninth heat transfer medium supply line, the hot stream of the vaporizer (104-2) is connected to the fourth heat transfer medium storage tank (304) and the tenth heat transfer medium supply line, and the fourth heat transfer medium storage tank (304) is characterized in that it is connected to the cold stream of the pre-cooling heat exchanger (205) and the eleventh heat transfer medium supply line.

At this time, it is preferable that the first heat transfer medium be heated through heat exchange in the pre-cooling heat exchanger (205) and stored in the third heat transfer medium storage tank (301), and the first heat transfer medium stored in the third heat transfer medium storage tank (301) be supplied to the cooler (109) to perform heat exchange with the air passing through the multi-stage expansion unit.

At this time, it is preferable that a third heat transfer medium supply pump (302) and a third heat transfer medium flow rate control valve (303) be arranged on the eighth heat transfer medium supply line to supply the first heat transfer medium stored in the third heat transfer medium storage tank (301) to the cooler (109).

The first heat transfer medium supplied to the cooler (109) is heated by heat exchange with air, and it is preferable to supply the heated first heat transfer medium to the hot stream of the second vaporizer (104-2) along the ninth heat transfer medium supply line.

The first heat transfer medium supplied as a hot stream of the vaporizer (104) exchanges heat with low-temperature air passing through the cold stream of the vaporizer (104), so that the first heat transfer medium is cooled, and it is preferable to supply and store the cooled first heat transfer medium to the fourth heat transfer medium storage tank (304).

The heat transfer medium stored in the fourth heat transfer medium storage tank (304) is supplied to the cold stream of the pre-cooling heat exchanger (205), and it is preferable that a fourth heat transfer medium supply pump (305) and a fourth heat transfer medium flow rate control valve (306) are arranged on the eleventh heat transfer medium supply line.

Meanwhile, the second heat transfer medium is heated through heat exchange in the condenser (206) and stored in the fifth heat transfer medium storage tank (401). The fifth heat transfer medium storage tank (401) is connected to the cold stream of the condenser (206) and the 12th heat transfer medium supply line, and is connected to the hot stream of the first vaporizer (104-1) and the 13th heat transfer medium supply line. The hot stream of the first vaporizer (104-1) is connected to the sixth heat transfer medium storage tank (404) and the 15th heat transfer medium supply line, and the sixth heat transfer medium storage tank (404) is connected to the cold stream of the condenser (206) and the 16th heat transfer medium supply line.

At this time, it is preferable that a fifth heat transfer medium supply pump (402) and a fifth heat transfer medium flow rate control valve (403) be arranged on the third heat transfer medium supply line to supply the second heat transfer medium stored in the fifth heat transfer medium storage tank (401) to the first vaporizer (104-1).

The second heat transfer medium supplied to the first vaporizer (104-1) is cooled by heat exchange with air, and it is preferable to supply and store the cooled second heat transfer medium to the sixth heat transfer medium storage tank (404) along the 14th heat transfer medium supply line.

The second heat transfer medium stored in the sixth heat transfer medium storage tank (404) is supplied to the cold stream of the condenser (206), and it is preferable that a sixth heat transfer medium supply pump (405) and a sixth heat transfer medium flow rate control valve (406) are arranged on the 15th heat transfer medium supply line.

Meanwhile, the first heat transfer medium and the second heat transfer medium are distinguished based on the temperature range in which they can store cold heat in a liquid phase, and it is preferable that the first heat transfer medium uses a material having a higher temperature range in which cold heat can be stored in a liquid phase compared to the second heat transfer medium.

Specifically, the first heat transfer medium may be one selected from alcohol compounds, which has a high temperature range in which the liquid can store cold heat. For example, the second heat transfer medium may be one selected from methanol and ethanol.

The second heat transfer medium may be one selected from hydrocarbon-based materials, having a temperature range in which the second heat transfer medium can store cold heat in a liquid state lower than the temperature range of the first heat transfer medium. For example, the second heat transfer medium may be one selected from propane and ethane.

Below, a control method for a high-efficiency air liquefaction energy storage system is described.

In accordance with one embodiment of the present invention, a method for controlling a high-efficiency air liquefaction energy storage system may include a liquefied air forming step of forming liquefied air by supplying air introduced from the atmosphere into a liquefied air forming unit to a pre-cooling heat exchanger (205) and a condenser (206), a liquefied air storage step of storing the formed liquefied air in a liquefied air storage unit, and an air power generation and cooling step of supplying the liquefied air stored in the liquefied air storage unit to a vaporizer (104) and a cooler (109) of an air power generation and cooling unit to generate power and cool the air, and supply the same to a demand source.

At this time, the high-efficiency air liquefaction energy storage system is characterized by including a heat transfer medium circulation step in which one heat transfer medium circulates through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.

The above liquefied air forming step may include a precooling step of supplying air drawn in from the atmosphere to a precooling heat exchanger (205) and performing heat exchange with a heat transfer medium to perform primary cooling, a condensing step of supplying the primary cooled air to a condenser (206) and performing heat exchange with a heat transfer medium to form condensed liquefied air, and a gas-liquid separation step of supplying the condensed liquefied air to a gas-liquid separator to separate liquefied air and gaseous air.

At this time, it is preferable that the liquefied air separated in the above-mentioned gas-liquid separation step be supplied to an air power generation and cooling unit to perform an air power generation and cooling step, and that the air in a gaseous state be re-supplied to the above-mentioned condenser (206) and pre-cooling heat exchanger (205) to be heated and then released into the atmosphere.

Meanwhile, some of the air that has been first cooled in the pre-cooling heat exchanger (205) is supplied to the condenser (206), and some of the air is branched off from the second air supply line and supplied to the cryogenic expander (207). The first cooled air supplied to the cryogenic expander (207) is expanded to have a temperature lower than that of the liquefied air, separated in the gas-liquid separator (209), and the flow is merged with the air in a gaseous state having the same temperature as that of the liquefied air, and is re-supplied to the condenser (206) in a state where the average temperature is lower than that of the liquefied air, thereby liquefying the air. Thereafter, the air is continuously re-supplied to the pre-cooling heat exchanger (205) to pre-cool the air after the rear cooler (204).

The above air power generation and cooling stage is intended for power generation and district cooling using clean air exiting the turbine, and may include a vaporization stage, a power generation stage, and a cooling stage.

The above vaporization step is to supply the liquefied air stored in the liquefied air storage tank (101) to the vaporizer (104). It is preferable to pressurize the liquefied air through the first liquefied air pump (102) and supply the pressurized liquefied air to the vaporizer (104) to vaporize it. At this time, it is preferable that the pressurized liquefied air supplied to the vaporizer (104) performs heat exchange with a heat transfer medium.

It is preferable that the above-mentioned development stage performs multi-stage expansion by repeatedly heating and expanding the vaporized gaseous air through the first heater (105), the first turbine (106), the second heater (107), and the second turbine (108).

The above cooling step cools the multi-stage expanded air by exchanging heat with a heat transfer medium, and the cooled air is supplied to the demand source.

The above heat transfer medium circulation step is characterized in that it circulates through the vaporizer (104), cooler (109), condenser (206) and pre-cooling heat exchanger (205) in the high-efficiency air liquefaction energy storage system to perform heat exchange with air, and includes a first heat transfer medium storage step of storing the heat transfer medium heated while passing through the pre-cooling heat exchanger (205) in a first heat transfer medium storage tank (501), and a second heat transfer medium storage step of storing the heat transfer medium cooled while passing through the cooler (109) and vaporizer (104) in a second heat transfer medium storage tank (504), and the cooled heat transfer medium stored in the second heat transfer medium storage tank (504) is sequentially supplied to the condenser (206) and the pre-cooling heat exchanger (205).

Specifically, the heat transfer medium heated through heat exchange in the pre-cooling heat exchanger (205) is stored in the first heat transfer medium storage tank (501), and the heat transfer medium stored in the first heat transfer medium storage tank (501) is supplied to the cooler (109) to perform heat exchange with the air passing through the multi-stage expansion unit.

In addition, the heat transfer medium supplied to the cooler (109) is heated by heat exchange with air, and the heated heat transfer medium is supplied to the hot stream of the vaporizer (104) along the third heat transfer medium supply line.

Thereafter, the heat transfer medium supplied to the hot stream of the vaporizer (104) exchanges heat with the low-temperature air passing through the cold stream of the vaporizer (104), thereby cooling the heat transfer medium, and the cooled heat transfer medium is supplied to the second heat transfer medium storage tank (504) and stored.

In addition, it is preferable that the heat transfer medium stored in the second heat transfer medium storage tank (504) is heated by supplying it to the cold stream of the condenser (206), and the heat transfer medium heated by heat exchange in the cold stream of the condenser (206) is heated by supplying it to the pre-cooling heat exchanger (205).

For example, when HFE-7200 is applied as a single heat transfer medium, the vaporizer (104) is not divided but is integrated and used as one. In addition, even when only one heat transfer medium is used, the cooler (109) is necessarily used. HFE-7200 is heated and stored in the first heat transfer medium storage tank (501) to determine the temperature of the air discharged through the pre-cooling heat exchanger (205) in the air liquefaction process.

The above stored HFE-7200 is heated in the cooler (109) during the power generation process to determine cooling conditions using clean air, and then cooled in the vaporizer (104) and stored in a cryogenic liquid state in the second heat transfer medium storage tank (504).

In addition, it supplies cold heat to the condenser (206) to play a role in taking charge of a portion of the total cold heat required for air liquefaction, and then continues to circulate by being sent back to the pre-cooling heat exchanger (205).

According to another embodiment of the present invention, a control method for a high-efficiency air liquefaction energy storage system may include a liquefied air forming step of forming liquefied air by supplying air introduced from the atmosphere into a liquefied air forming unit to a pre-cooling heat exchanger (205) and a condenser (206), a liquefied air storage step of storing the formed liquefied air in a liquefied air storage unit, and an air power generation and cooling step of supplying the liquefied air stored in the liquefied air storage unit to a first vaporizer (104-1), a second vaporizer (104-2), and a cooler (109) of an air power generation and cooling unit to cool and generate power, and supplying the same to a demand source.

At this time, the high-efficiency air liquefaction energy storage system is characterized by including a heat transfer medium circulation step in which the first heat transfer medium and the second heat transfer medium circulate through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.

The heat transfer medium circulation step is to perform heat exchange with air by circulating through the first vaporizer (104-1), the second vaporizer (104-2), the cooler (109), the condenser (206) and the pre-cooling heat exchanger (205) in the high-efficiency air liquefaction energy storage system, and the heat transfer medium circulation step is to store the first heat transfer medium heated by passing through the pre-cooling heat exchanger (205) in a third heat transfer medium storage tank (301), a fourth heat transfer medium storage step connected to the third heat transfer medium storage tank (301) and storing the first heat transfer medium cooled by passing through the cooler (109) and the second vaporizer (104-2) in a fourth heat transfer medium storage tank (304), and a fifth heat transfer medium heated by passing through the condenser (206). It is characterized by including a fifth heat transfer medium storage step for storing in a storage tank (401) and a sixth heat transfer medium storage step for storing a second heat transfer medium that is connected to the fifth heat transfer medium storage tank (401) and cooled by passing through a first vaporizer (104-1) in a sixth heat transfer medium storage tank (404).

At this time, it is preferable that the first heat transfer medium stored in the fourth heat transfer medium storage tank (304) be supplied to the pre-cooling heat exchanger (205), and the second heat transfer medium stored in the sixth heat transfer medium storage tank (404) be supplied to the condenser (206).

In detail, the first heat transfer medium is heated through heat exchange in the pre-cooling heat exchanger (205) and stored in the third heat transfer medium storage tank (301), and the first heat transfer medium stored in the third heat transfer medium storage tank (301) is supplied to the cooler (109) to perform heat exchange with air passing through the multi-stage expansion unit.

At this time, the first heat transfer medium supplied to the cooler (109) is heated by heat exchange with air, and the heated first heat transfer medium is supplied to the hot stream of the second vaporizer (104-2) along the ninth heat transfer medium supply line.

In addition, the first heat transfer medium supplied as a hot stream of the vaporizer (104) exchanges heat with low-temperature air passing through the cold stream of the vaporizer (104), so that the first heat transfer medium is cooled, and the cooled first heat transfer medium is supplied to and stored in a fourth heat transfer medium storage tank (304), and it is preferable that the first heat transfer medium stored in the fourth heat transfer medium storage tank (304) is supplied to the cold stream of the precooling heat exchanger (205).

Meanwhile, the second heat transfer medium is heated through heat exchange in the condenser (206) and stored in the fifth heat transfer medium storage tank (401), and the second heat transfer medium stored in the fifth heat transfer medium storage tank (401) is supplied to the first vaporizer (104-1).

At this time, the second heat transfer medium supplied to the first vaporizer (104-1) is cooled by heat exchange with air, and the cooled second heat transfer medium is supplied to the sixth heat transfer medium storage tank (404) and stored, and it is preferable that the second heat transfer medium stored in the sixth heat transfer medium storage tank (404) is supplied to the cold stream of the condenser (206).

For example, when methanol and propane are used as heat transfer media, the outlet temperature (S301) of methanol in the precooling heat exchanger (205) for precooling the air liquefaction process is set to be lower than the exhaust air temperature, and is stored in a liquid state in the third heat transfer medium storage tank (301).

The stored liquid methanol is pumped and the flow rate is controlled by the third flow control valve (303) and flows to the cooler (109). The air has a discharge temperature (S109) determined by the indirect heat exchange method, and the pressure is controlled by the discharge air pressure control valve (110) in consideration of the differential pressure due to transport to the demand location, and is supplied to the demand location.

In addition, methanol whose temperature has increased while providing cooling heat to the cooler (109) is supplied to the second vaporizer (104-2) and cooled, and the cooled methanol is stored in a liquid state in the fourth heat transfer medium storage tank (304).

The methanol stored in the fourth heat transfer medium storage tank (304) is continuously circulated to be used as cold heat for precooling the air liquefaction process.

Hereinafter, the present invention will be described in detail through examples and experimental examples. However, the following examples and experimental examples are only intended to illustrate the present invention, and the present invention is not limited to the following examples and experimental examples.

Tables 1 to 5 show the process conditions and results according to the heat transfer medium applied to the high-efficiency air liquefaction energy storage system. In this case, the process results are the results obtained by applying the process conditions required to produce 1MWh output energy through the air power generation process to aspen HYSYS.

Table 1 shows the liquid air composition ratio and the air power generation process boundary conditions, Table 2 shows the heat and mass balance of the 1MWh air power generation process analyzed by Aspen HYSYS, and Table 3 shows the heat amount of the heat exchange process. In addition, Table 4 shows the temperature, flow rate, and heat according to the change in the heat transfer medium in the vaporization process of the 1MWe air power generation process, and Table 5 shows the results of calculating the volume of cold storage material required to produce 1MWh output energy through the air power generation process.

Liquid air composition ratio
(Mole Frac.) ingredient Mole fraction nitrogen 0.7589 oxygen 0.2304 argon 0.0107 Air power generation process
Boundary conditions Pump insulation efficiency 75% Turbine isentropic efficiency 75% Differential pressure in the carburetor 0.5 bar Each stage turbine inlet temperature 150℃ Carburetor outlet temperature 20℃ Clean air exhaust temperature 11℃

Stream Name s101 s102 s103 s103-2 s104 s105
liquid
sifter
ball
energy
/
ball
energy Vapour Fraction 0.0 0.0 0.0 1.0 1.0 1.0 Temperature [Degree C.] -192.0 -188.8 -188.8 -50.0 20.0 150.0 Pressure [bar_Abs.] 1.30 71.00 71.00 70.70 70.50 70.40 Mass Flow [g/s] 5500.0 5500.0 5500.0 5500.0 5500.0 5500.0 Stream Name s106 s107 s108 s109 s110 Vapour Fraction 1.0 1.0 1.0 1.0 1.0 Temperature [Degree C.] 53.4 150.0 25.7 11.0 11.0 Pressure [bar_Abs.] 20.42 20.32 3.60 3.50 3.50 Mass Flow [g/s] 5500.0 5500.0 5500.0 5500.0 5500.0 mail
burnt
all Stream Name s301 s302 s303 s304 s305 s306 s307 Vapour Fraction 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Temperature [Degree C.] 10.0 10.0 10.0 10.0 21.9 -48.0 -48.0 Pressure [bar_Abs.] 1.10 1.10 1.40 1.40 1.30 1.10 1.10 Mass Flow [g/s] 2765.0 2765.0 2765.0 2765.0 2765.0 2765.0 2765.0 print
as
board Stream Name s401 s402 s403 s404 s405 s406 Vapour Fraction 0.0 0.0 0.0 0.0 0.0 0.0 Temperature [Degree C.] -48.0 -48.0 -48.0 -48.0 -138.0 -138.0 Pressure [bar_Abs.] 1.10 1.10 1.40 1.40 1.10 1.10 Mass Flow [g/s] 8984.3 8984.3 8984.3 8984.3 8984.3 8984.3

flux Turbine output Heat in the first carburetor Heat in the second carburetor Heat in the cooler Heat in the heat exchange process result g/s kW KW _th KW _th KW _th KW _th liquid air
/air 5500.00 1204.99 1682.65 455.63 -81.30 2056.98 vaporization, development Methanol 2765.00 -455.63 81.30 -374.33 Cold storage Propane 8984.35 -1682.65 -1682.65 Cold storage Summation 0.00 0.00 0.00 0.00

carburetor
Inlet pressure
[bar_Abs.] carburetor
outlet pressure
[bar_Abs.] carburetor
Inlet temperature
[℃] carburetor
outlet temperature
[℃] flux
[kg/s] heat
(Heat)
[kW _th ] For power generation
Working Fluid air 71 70.5 -188.8 20.0 5.50 2138.28 A cold storage material HFE
-7200 1.6 1.1 21.9 -138.0 12.63 -2138.28 Two cold storage materials Carburetor 1
Inlet pressure
[bar_Abs.] Carburetor 1
outlet pressure
[bar_Abs.] Carburetor 1
Inlet temperature
[℃] Carburetor 1
outlet temperature
[℃] Propane 1.4 1.1 -48.0 -138.0 8.98 -1682.65 Second carburetor
Inlet pressure
[bar_Abs.] Second carburetor
outlet pressure
[bar_Abs.] Second carburetor
Inlet temperature
[℃] Second carburetor
outlet temperature
[℃] Methanol 1.3 1.1 21.9 -48.0 2.77 -455.63

No. How to use Cold storage
substance Storage tank
type necessary
Storage capacity
[kg] At storage tank temperature
Material density
[kg/m ³ ] Tank Star
Storage volume
[m ³ ] Total storage volume
[m ³ ] 1 Parallel use of propane/methanol Methanol Methanol Cold_Tank 9954.00 855.54 11.63 59.02 Propane Propane Cold_Tank 32343.65 682.55 47.39 2 HFE series exclusive use HFE-7200 HFE-7200 Cold_Tank 45470.40 1798.80 25.28 25.28

Example 1. Application of methanol and propane as heat transfer media in a high-efficiency air liquefaction energy storage system

The composition of the air liquefaction process is not much different from the existing one, so the composition ratio of the produced liquefied air is reflected as shown in Table 1, and the boundary conditions of the power generation process are disclosed in Table 1. At this time, the focus was on the air power generation process.

Under the above boundary conditions, the clean air exhaust temperature should be controlled independently at 11℃ regardless of the turbine operating conditions, and the use of methanol for this purpose should be properly balanced through the heating and cooling processes. At this time, the power generation capacity was fixed at 1MWe and analyzed using the commercial code Aspen HYSYS, and the heat and material balances are presented in Table 2.

Referring to Table 2, it can be seen that the turbine final outlet temperature was determined to be 25.7°C according to the turbine inlet temperature and expansion ratio, but the outlet temperature was then lowered to 11°C by the cooler (109), and that this was determined by the temperature of the first heat transfer medium storage tank (301) in which liquid methanol was stored, and was not affected by the turbine operating conditions.

Methanol performs a cooling function for the air outlet temperature, so that the outlet temperature of the cooler (109) rises by 11.9°C to 21.9°C, but is then cooled to -48°C by the second vaporizer (104-2) and stored.

At this time, the -48℃ methanol temperature is the set point for utilizing two heat transfer media (liquid cold storage material) of propane and methanol, and is not significantly affected by the use of methanol in the cooler (109).

However, while maintaining the set temperature, the methanol flow rate in the cooler (109) changes depending on the use.

The increase in pump output due to the increase in methanol flow rate is very small, and the change in the air discharge temperature of the liquefaction process, which is affected by the outlet temperature of the methanol pre-cooling heat exchanger (205) in the liquefaction process, can also be ignored because it is a condition of air discharged to the atmosphere.

That is, in order to independently achieve clean air emission conditions through the use of a methanol cooler (109) in the power generation process, it can be said that changes in the flow rate of methanol and the emission temperature of air in the air liquefaction process are not issues of concern.

As shown in Fig. 2, in an example of a 1 MWe-class power generation process utilizing three heat exchangers, including a first vaporizer (104-1), a second vaporizer (104-2), and a cooler (109), the amount of heat in the heat exchange process between air, propane, and methanol is shown in Table 3.

Referring to Table 3, in the air liquefaction process, 81.3 kW _th of heat was removed from the purified air through the pretreatment process (removal of moisture, carbon dioxide, impurities, and fine dust in the air, etc.) to be used for cooling after power generation. Considering the total heat of the heat exchange process and the electric energy consumed in the pretreatment process, it can be said that it does not account for a large proportion.

Example 2. Application of HFE-7200 as a heat transfer medium in a high-efficiency air liquefaction energy storage system

When using HFE-7200 as a heat transfer medium, in order to simply compare the results under the same conditions as when using propane and methanol, the final inlet temperature was assumed to be -138℃ and the final outlet temperature was assumed to be 21.9℃, and the calculations were performed, and the results are disclosed in Table 4.

Referring to Table 4, it can be seen that when one heat transfer medium (cooling storage material) is used, the flow rate increases but the storage volume decreases compared to when two are used. This is because the specific heat of HFE-7200 is lower than that of propane/methanol.

In addition, the required volume of each heat transfer medium (cold storage material) to operate a 1 MWe power generation process for 1 hour and generate 1 MEh of output energy was calculated and listed in Table 5.

Referring to Table 5, when using propane/methanol, the storage volume is greatly dependent on the density of propane. The density of HFE-7200 is 2.63 times that of propane, so when HFE-7200 was used, the storage volume was found to be 42.83% of the theoretical calculation compared to when using propane/methanol.

Accordingly, it can be confirmed that although there are limitations in low-temperature conditions due to the use of HFE-7200, the number of storage tanks can be reduced and the storage volume can be reduced by less than 50%.

As described above, the present invention has the effect of providing a high-efficiency air liquefaction energy storage system utilizing a liquid cold storage material and a control method thereof.

Specifically, the present invention provides a high-efficiency air liquefaction energy storage system using a liquid liquefaction energy storage material that can be used as a cold storage and heat transfer medium by applying propane and methanol to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

In addition, by applying propane and methanol to the air liquefaction energy storage system, district cooling can be performed using clean air that meets the requirements of the demand site without additional power consumption, and the degree of freedom in turbine operation conditions in the power generation process can be increased.

In addition, there is an effect of providing a high-efficiency air liquefaction energy storage system using a liquid cold storage material that can be used as a cold storage and heat transfer medium by applying HFE series materials to a liquid air liquefaction energy storage system (LAES), and a control method thereof that can be used as district cooling and clean air.

In addition, by applying HFE series materials to liquid air energy storage systems (LAES), environmental issues can be resolved, and by performing the role of cold storage and heat transfer medium with a single high-density material, the required land area can be reduced, storage volume can be reduced, and facility investment costs can be reduced.

In addition, HFE is chemically stable and has a low risk of fire or explosion, so even if a gas leak occurs during operation, it does not lead to a major accident.

In addition, it is economical because it does not require additional facility investment or energy consumption as it does not utilize a cooling tower for cooling water circulation or a separate chiller depending on the circulating heat transfer medium (cold storage material) in the system.

In addition, the air temperature at the turbine outlet can be independent of the final exhaust temperature for district cooling, which provides freedom in turbine operating conditions and enables stable power generation process operation.

In addition, it has the effect of being able to supply the final exhaust temperature for district cooling at a very low temperature.

Although this specification describes only a few examples among various embodiments performed by the inventors of the present invention, the technical idea of the present invention is not limited or restricted thereto, and can be modified and implemented in various ways by those skilled in the art.

101: liquefied air storage tank, 102: first liquefied air pump, 103: first flow control valve, 104: vaporizer, 104-1: first vaporizer, 104-2: second vaporizer, 105: first heater, 106: first turbine, 107: second heater, 108: second turbine, 110: exhaust air pressure control valve
201: low pressure compressor, 202: intercooler, 203: high pressure compressor, 204: aftercooler, 205: precooling heat exchanger, 206: condenser, 207: cryogenic expander, 208: Joule-Thompson valve, 209: gas-liquid separator
301: Third heat transfer medium storage tank, 302: Third heat transfer medium supply pump, 303: Third heat transfer medium flow rate control valve, 304: Fourth heat transfer medium storage tank, 305: Fourth heat transfer medium supply pump, 306: Fourth heat transfer medium flow rate control valve
401: Fifth heat transfer medium storage tank, 402: Fifth heat transfer medium supply pump, 403: Fifth heat transfer medium flow rate control valve, 404: Sixth heat transfer medium storage tank, 405: Sixth heat transfer medium supply pump, 406: Sixth heat transfer medium flow rate control valve
501: first heat transfer medium storage tank, 502: first heat transfer medium supply pump, 503: first heat transfer medium flow rate control valve, 504: second heat transfer medium storage tank, 505: second heat transfer medium supply pump, 506: second heat transfer medium flow rate control valve

Claims (15)

In a high-efficiency air liquefaction energy storage system,
The above air liquefaction energy storage system comprises a liquefied air forming unit including a pre-cooling heat exchanger and a condenser to liquefy air taken in from the atmosphere;
A liquefied air storage unit for storing liquefied air formed in the above liquefied air forming unit; and
An air power generation and cooling unit including a vaporizer and a cooler to generate and cool liquefied air stored in the liquefied air storage unit and supply it to a demand source;
The above high-efficiency air liquefaction energy storage system is a system in which one heat transfer medium circulates through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.
High-efficiency air liquefaction energy storage system. In the first paragraph,
The above pre-cooling heat exchanger performs primary cooling by exchanging heat with the air drawn in from the atmosphere and the heat transfer medium.
The above condenser heat-exchanges the first cooled air with the heat transfer medium to form liquefied air.
High-efficiency air liquefaction energy storage system. In the second paragraph,
The above liquefied air forming unit further includes a gas-liquid separator;
The above gas-liquid separator separates the liquefied air supplied from the condenser into liquefied air and gaseous air.
The liquefied air separated in the above gas-liquid separator is supplied to the liquefied air storage unit and stored.
The gaseous air is re-supplied to the condenser and pre-cooling heat exchanger to be heated, and the heated air is discharged to the atmosphere.
High-efficiency air liquefaction energy storage system. In the first paragraph,
The above air power generation cooling unit further includes a multi-stage expansion unit;
The air vaporized in the above carburetor is expanded in multiple stages, and the multi-stage expanded air is supplied to the cooler.
High-efficiency air liquefaction energy storage system. In the first paragraph,
A high-efficiency air liquefaction energy storage system comprises a heat transfer medium storage tank;
A first heat transfer medium storage tank for storing a heat transfer medium that has been heated while passing through the above-mentioned pre-cooling heat exchanger; and
A second heat transfer medium storage tank for storing the cooled heat transfer medium passing through the cooler and vaporizer;
Supplying the cooled heat transfer medium stored in the second heat transfer medium storage tank to the condenser,
High-efficiency air liquefaction energy storage system.
In the first paragraph,
The above heat transfer medium is one selected from hydrofluoro ether (HFE), ethyl perfluorobutyl ether, and carbon fluorine compounds.
High-efficiency air liquefaction energy storage system. In a high-efficiency air liquefaction energy storage system,
The above air liquefaction energy storage system comprises a liquefied air forming unit including a pre-cooling heat exchanger and a condenser to liquefy air taken in from the atmosphere;
A liquefied air storage unit for storing liquefied air formed in the above liquefied air forming unit; and
An air power generation and cooling unit including a first vaporizer, a second vaporizer, and a cooler to generate and cool liquefied air stored in the liquefied air storage unit and supply it to a demand source;
The above high-efficiency air liquefaction energy storage system is a system in which the first heat transfer medium and the second heat transfer medium simultaneously circulate through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air.
High-efficiency air liquefaction energy storage system. In Article 7,
A high-efficiency air liquefaction energy storage system comprises a heat transfer medium storage tank;
A third heat transfer medium storage tank that stores the first heat transfer medium that has been heated while passing through the above-mentioned pre-cooling heat exchanger;
A fourth heat transfer medium storage tank connected to the third heat transfer medium storage tank and storing the cooled first heat transfer medium passing through the cooler and the second vaporizer;
A fifth heat transfer medium storage tank storing the second heat transfer medium that has passed through the above condenser and has been heated; and
A sixth heat transfer medium storage tank connected to the fourth heat transfer medium storage tank and storing the second heat transfer medium that has passed through the first vaporizer and has been cooled;
The first heat transfer medium stored in the fourth heat transfer medium storage tank is supplied to the pre-cooling heat exchanger.
The second heat transfer medium stored in the above sixth heat transfer medium storage tank is supplied to the condenser.
High-efficiency air liquefaction energy storage system. In Article 8,
The temperature range for storing the cold heat of the first heat transfer medium is higher than the temperature range for storing the cold heat of the second heat transfer medium.
The above first heat transfer medium is one selected from alcohol compounds,
The second heat transfer medium is one selected from hydrocarbon-based materials.
High-efficiency air liquefaction energy storage system. In a control method of a high-efficiency air liquefaction energy storage system,
A liquefied air forming step for forming liquefied air by supplying air introduced from the atmosphere into a liquefied air forming unit to a pre-cooling heat exchanger and a condenser;
A liquefied air storage step for storing the formed liquefied air in a liquefied air storage unit; and
An air power generation and cooling step for supplying liquefied air stored in the liquefied air storage unit to a vaporizer and cooler of an air power generation and cooling unit to cool and generate power and supply it to a demand source;
The above high-efficiency air liquefaction energy storage system includes a heat transfer medium circulation step in which one heat transfer medium circulates through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air;
Control method for a high-efficiency air liquefaction energy storage system. In Article 10,
The above liquefied air forming step is a precooling step in which air taken in from the atmosphere is supplied to a precooling heat exchanger and cooled primarily through heat exchange with a heat transfer medium;
A condensation step for supplying the above-mentioned primary cooled air to a condenser and exchanging heat with a heat transfer medium to form condensed liquefied air; and
A gas-liquid separation step for supplying the condensed liquefied air to a gas-liquid separator to separate liquefied air and gaseous air;
Control method for a high-efficiency air liquefaction energy storage system. In Article 11,
The liquefied air separated in the above-mentioned gas-liquid separation step is supplied to the air power generation and cooling unit to perform the air power generation and cooling step.
The above gaseous air is re-supplied to the condenser and pre-cooling heat exchanger, heated, and then released into the atmosphere.
Control method for a high-efficiency air liquefaction energy storage system. In Article 10,
The above heat transfer medium circulation step is a first heat transfer medium storage step for storing the heated heat transfer medium passing through the pre-cooling heat exchanger in a first heat transfer medium storage tank; and
A second heat transfer medium storage step for storing the cooled heat transfer medium passing through the cooler and vaporizer in a second heat transfer medium storage tank;
The cooled heat transfer medium stored in the second heat transfer medium storage tank is sequentially supplied to the condenser and the precooling heat exchanger.
Control method for a high-efficiency air liquefaction energy storage system. In a control method of a high-efficiency air liquefaction energy storage system,
A liquefied air forming step for forming liquefied air by supplying air introduced from the atmosphere into a liquefied air forming unit to a pre-cooling heat exchanger and a condenser;
A liquefied air storage step for storing the formed liquefied air in a liquefied air storage unit; and
An air power generation and cooling step for supplying liquefied air stored in the liquefied air storage unit to the first vaporizer, second vaporizer and cooler of the air power generation and cooling unit to cool and generate power and supply it to a demand source;
The high-efficiency air liquefaction energy storage system comprises a heat transfer medium circulation step in which a first heat transfer medium and a second heat transfer medium circulate through the liquefied air forming unit and the air power generation cooling unit to cool and heat the air;
Control method for a high-efficiency air liquefaction energy storage system. In Article 14,
The above heat transfer medium circulation step is a third heat transfer medium storage step of storing the first heat transfer medium heated by passing through the pre-cooling heat exchanger in a third heat transfer medium storage tank;
A fourth heat transfer medium storage step connected to the third heat transfer medium storage tank and storing the cooled first heat transfer medium passing through the cooler and the second vaporizer in the fourth heat transfer medium storage tank;
A fifth heat transfer medium storage step for storing the second heat transfer medium heated by passing through the above condenser in a fifth heat transfer medium storage tank; and
A sixth heat transfer medium storage step, which is connected to the fifth heat transfer medium storage tank and stores the second heat transfer medium that has passed through the first vaporizer and has been cooled in the sixth heat transfer medium storage tank;
The first heat transfer medium stored in the fourth heat transfer medium storage tank is supplied to the pre-cooling heat exchanger.
The second heat transfer medium stored in the above sixth heat transfer medium storage tank is supplied to the condenser.
Control method for a high-efficiency air liquefaction energy storage system.