KR20190057971A - Hybrid power generation system using a supercritical CO2 working fluid - Google Patents

Abstract

The present invention relates to a hybrid power generation system using a supercritical carbon dioxide working fluid, which comprises: a furnace for burning fuel to generate combustion heat; a boiler having a plurality of heat exchangers for heating a working fluid using the combustion heat; a turbine driven by the working fluid heated in the boiler; a recuperator for performing heat exchange with the working fluid through the turbine to cool the turbine; a condenser for cooling the working fluid through the recuperator; and a compressor for compressing the working fluid cooled in the condenser. Moreover, the working fluid is supercritical carbon dioxide.

Description

Technical Field [0001] The present invention relates to a hybrid power generation system using a supercritical carbon dioxide working fluid,

The present invention relates to a hybrid power generation system using a supercritical carbon dioxide working fluid, and more particularly, to a hybrid power generation system using a supercritical carbon dioxide working fluid capable of eliminating heat exchange inefficiency, ≪ / RTI >

 Internationally, there is an increasing need for efficient power generation. As the movement to reduce the generation of pollutants becomes more active, various efforts are being made to increase the production of electricity while reducing the generation of pollutants. As one of such efforts, research and development on a supercritical carbon dioxide (CO2) power generation system using supercritical carbon dioxide as a working fluid has been activated as disclosed in Korean Patent Laid-Open Publication No. 2013-0036180.

Since supercritical carbon dioxide has a gas-like viscosity at a density similar to that of a liquid state, it can minimize the power consumption required for compression and circulation of the fluid as well as miniaturization of the apparatus. At the same time, the critical point is 31.4 degrees Celsius, 72.8 atmospheres, and the critical point is much lower than the water at 373.95 degrees Celsius and 217.7 atmospheres, which is easy to handle. The supercritical carbon dioxide power generation system has a power generation efficiency of about 45% when operated at a temperature of 550 ° C. and has an advantage of improving the generation efficiency of the steam cycle by 20% or more and reducing the turbine power.

On the other hand, in the case of coal-fired power generation, power is generated by heating water using fossil fuels such as coal to generate steam, and driving the turbine with steam. FIG. 1 is a schematic view showing a conventional coal-fired power generation system, and FIG. 2 is a graph showing a relationship between a temperature and a specific heat capacity (TS) according to the working fluid of FIG.

As shown in FIG. 1, the coal-fired power generation system generates combustion heat by burning coal in a furnace 61 of a furnace 60, and the combustion heat is generated by a water wall of the boiler side and a water- and converts the water in the wall tube 62 into steam (wall tube section in FIG. 2). The steam is supplied to the steam turbine 10 after the superheater (the superheater section in FIG. 2) is reheated in the superheater (superheater 63) to operate the generator for generating the electric power (section (1) - (2) in FIG. The water that has passed through the steam turbine 10 is condensed in a condenser 20 and then converted into water again in a section of the condenser pump 30 to a feed water tank and heater 40, Lt; / RTI > The deaerated and heated water in the water dispenser 40 is supplied to the economizer 64 of the boiler through a feed water pump 50 to heat the boiler 60 Cooled water tube 62 of the water-cooled wall tube 62.

At this time, since the water in the economizer 64 is phase-changed into a vapor state, it is necessary to install a drum 65, and the water separated from the drum 65 flows along the transfer pipe 66 to the water- And is used to cool the furnace wall of the boiler (60).

Since the phase change occurs in the middle when water is supplied for cooling the furnace wall, it is possible to prevent the water-cooled wall tube 62 from being damaged due to the difference in the speed due to the difference in density of water and steam, A flow path is created.

The heat capacity of the economizer and the superheater is fixed when the temperature and pressure of the inlet of the turbine and the economizer are determined because the hot gas flows and the heat exchanges (concurrent heat exchange) are inefficient. tube section, the saturation temperature is determined by the pressure). Therefore, in order to increase the efficiency of the entire system, it is necessary to add some steam inside the turbine to raise the water temperature. Therefore, there is a problem that turbine design becomes complicated to improve system efficiency.

In addition, it is necessary to install a condenser for converting steam into water, so that it is inevitable to install a condensate pump and components such as a drum are necessary, which makes it difficult to simplify the system.

Korean Patent Laid-Open Publication No. 2013-0036180 (published on March 31, 2013)

It is an object of the present invention to provide a hybrid power generation system using a supercritical carbon dioxide working fluid capable of eliminating heat exchange inefficiency and capable of high efficiency simplified power generation without a drum and a condensate pump for the separation of the water.

A hybrid power generation system using a supercritical carbon dioxide working fluid according to the present invention comprises a furnace having a furnace for combusting fuel to generate combustion heat, a plurality of heat exchangers for heating a working fluid using the combustion heat, A condenser for cooling the working fluid through the recuperator, and a condenser for cooling the working fluid cooled by the condenser, wherein the working fluid is cooled by the condenser, And the working fluid is supercritical carbon dioxide.

The superheater is installed on the upper end of the boiler and heats the working fluid flowing into the boiler. The superheater is provided at a discharge end of the boiler to absorb heat from the combustion gas discharged after burning the fuel, And an economizer for heating the incoming working fluid.

And a separator provided at a rear end of the compressor and branching the working fluid through the compressor to the recuperator and the economizer, respectively.

The working fluid branched to the recuperator is heat-exchanged with the working fluid passing through the turbine, and is supplied to the boiler after being reheated.

And the working fluid branched to the economizer is heated in the economizer and supplied to the boiler.

And a mixer provided outside the boiler and branched from the separator to mix the recirculator and the economizer into the boiler.

The boiler further includes a fluid wall tube provided along the longitudinal direction inside the boiler and circulating the working fluid through the mixer to cool the furnace.

The fluid wall tube is characterized in that the working fluid moves from the upper side to the lower side of the boiler.

The working fluid passing through the fluid wall tube is supplied to the superheater, and the working fluid passing through the superheater is circulated to the turbine.

Wherein the flow rate of the working fluid branched from the separator is branched to the economizer so that the temperature of the working fluid after absorbing the heat of the combustion gas is branched to the recuperator via the compressor, And the temperature of the working fluid after absorbing the heat of the working fluid through the turbine is adjusted to be the same.

The present invention also relates to a superheater comprising a furnace for burning fuel to generate combustion heat, a superheater provided on the upper side of the boiler for heating a working fluid, and a superheater provided at a discharge end of the boiler for combusting the fuel, A boiler having a fluid wall tube for circulating the working fluid therein to cool the furnace, a turbine driven by the working fluid, A condenser for cooling the working fluid through the recuperator; and a compressor for compressing the working fluid cooled in the condenser, wherein the working fluid is supplied to the boiler Is fed into the turbine and is maintained in a one-phase state in the boiler And a supercritical carbon dioxide working fluid.

The working fluid flows into the upper side of the fluid wall tube and is discharged to the lower side of the furnace.

And a separator provided at a rear end of the compressor and branching the working fluid through the compressor to the recuperator and the economizer, respectively.

The working fluid branched to the recuperator is heat-exchanged with the working fluid passing through the turbine, and is supplied to the boiler after being reheated.

And the working fluid branched to the economizer is heated in the economizer and supplied to the boiler.

And a mixer provided outside the boiler and branched from the separator to mix the recirculator and the economizer into the boiler.

And the flow direction of the working fluid in the fluid wall tube is opposite to the flowing direction of the combustion gas.

The working fluid passing through the fluid wall tube is supplied to the superheater, and the working fluid passing through the superheater is circulated to the turbine.

Wherein the flow rate of the working fluid branched from the separator is branched to the economizer so that the temperature of the working fluid after absorbing the heat of the combustion gas is branched to the recuperator via the compressor, And the temperature of the working fluid after absorbing the heat of the working fluid through the turbine is adjusted to be the same.

And controlling the flow rate of the working fluid to be supplied to the economizer to be higher when the temperature of the working fluid after the absorption of the heat of the combustion gas in the economizer is larger than the temperature of the working fluid after absorbing heat in the recuperator Wherein when the temperature of the working fluid after the absorption of the heat of the combustion gas in the economizer is lower than the temperature of the working fluid after the heat is absorbed by the recuperator, the flow rate ratio of the working fluid supplied to the economizer Is controlled to be low.

Since the hybrid power generation system using the supercritical carbon dioxide working fluid according to the embodiment of the present invention uses a single-phase working fluid, it is possible to construct an efficient power generation system, and it is possible to eliminate the drum and the boost pump, .

1 is a schematic diagram showing a conventional coal thermal power generation system,
FIG. 2 is a graph showing the relationship between the temperature and the specific heat capacity (TS) according to the working fluid of FIG. 1;
FIG. 3 is a schematic diagram showing a hybrid power generation system using a supercritical carbon dioxide working fluid according to an embodiment of the present invention.
Fig. 4 is a view showing a heat exchange flow of the working fluid according to Fig. 1,
5 is a view showing a heat exchange flow of the working fluid according to Fig. 3, Fig.
Fig. 6 is a graph showing the relationship between the temperature of the working fluid and the specific heat capacity (TS) according to Fig. 3,
FIG. 7 is a graph showing the temperature change at the entrance of the water-cooling wall tube according to the economizer heat capacity change according to FIG.

Hereinafter, a hybrid power generation system using supercritical carbon dioxide working fluid according to an embodiment of the present invention will be described in detail with reference to the drawings. (For a part of the coal power generation system, see FIGS. 1 and 2 Quot;).

The hybrid power generation system using the supercritical carbon dioxide working fluid of the present invention is a hybrid power generation system that combines a coal-fired power generation system with a supercritical carbon dioxide power generation system and constitutes a power generation cycle without a phase change of the working fluid.

The hybrid power generation system of the present invention uses supercritical carbon dioxide as the working fluid and forms a closed cycle in which the used carbon dioxide is not discharged to the outside.

The working fluid may supply carbon dioxide separately from the exhaust gas of the boiler 600 or may supply additional carbon dioxide. The working fluid flowing in the cycle may be in a supercritical state, or most of the working fluid may be in a supercritical state and the remainder may be in a subcritical state.

The carbon dioxide described in the present invention includes pure carbon dioxide in a chemical sense, carbon dioxide in a state in which impurities are contained in a general sense, and fluid in which carbon dioxide is mixed with at least one fluid as an additive do.

In the present invention, the terms low temperature and high temperature are relative terms, and it should be understood that a specific temperature is used as a reference value, higher temperature is higher temperature and lower temperature is not lower temperature.

It is to be understood that each configuration of the present invention is connected by a transfer pipe through which the working fluid flows, and that the working fluid flows along the transfer pipe even if not specifically mentioned. However, in the case where a plurality of structures are integrated, it is to be understood that, in this case, the working fluid flows along the conveyance pipe, as there will be a part or region which actually acts as a conveyance pipe in the integrated structure Pipelines shall be numbered in parentheses).

3 is a schematic diagram illustrating a hybrid power generation system using a supercritical carbon dioxide working fluid according to an embodiment of the present invention.

3, a hybrid power generation system using a supercritical carbon dioxide working fluid according to an embodiment of the present invention includes a boiler 600 as a part of a coal-fired power generation system, a furnace 600 installed in a boiler 600 610, a superheater 630, an economizer 640, and an air preheater 650 for preheating the air entering for combustion. In addition, a turbine 400 and a generator (not shown) driven by a supercritical carbon dioxide working fluid which is a constituent of the supercritical carbon dioxide power generation system, a recuperator 200 for cooling and recovering the working fluid, A condenser 500 for cooling, and a compressor 100 for compressing the working fluid.

A furnace 610 for burning fossil fuel and the like is provided in the lower side of the boiler 600 and a superheater 630 for raising the temperature of the working fluid finally through convection heat transfer is provided inside the boiler 600 . The economizer 640 is provided at the rear end of the boiler 600 that has passed through the superheater 630 to absorb the heat of the post-combustion exhaust gas and increase the combustion efficiency. An air preheater () is provided at a discharge end of the boiler 600 where the exhaust gas is discharged to absorb the heat of the exhaust gas and preheat the air supplied to the furnace 610. A fluid wall tube 620 is provided in which the supercritical carbon dioxide working fluid flows from the top of the boiler 600 to the lower furnace 610 instead of the existing water cooling wall.

After the fuel is burnt, the combustion gas is exhausted from the furnace 610 to the outside of the boiler 600 after passing through the superheater 630 and the economizer 640, and the flow of the working fluid flows through the economizer 640, the furnace 610, A fluid wall tube 620, and a superheater 630 in this order (this will be described later).

The high-temperature, high-pressure working fluid passing through the superheater 630 of the boiler 600 is supplied to the turbine 400 to drive the turbine 400. A generator may be connected to the turbine 400, and the generator is operated by rotation of the turbine 400 to produce electric power. A plurality of turbines 400 may be provided, and each of them may be used for production of electric power, driving of a compressor, and the like. The working fluid supplied to the turbine 400 is expanded while being discharged to the output end of the turbine 400 with a relatively low temperature and pressure as compared with the input end of the turbine 400 due to a decrease in temperature and pressure.

The working fluid passing through the turbine 400 is sent to the recuperator 200 (2), heat-exchanged in the recuperator 200, cooled first, and then sent to the condenser 500 (3).

The recuperator 200 exchanges heat between the working fluid branched from the rear end of the compressor 100 and the working fluid passing through the turbine 400. The working fluid passing through the turbine 400 is cooled and flows to the rear end of the compressor 100 The working fluid that is diverged in the heating chamber is heated.

The condenser 500 serves to once cool the working fluid that has been primarily cooled in the recuperator 200 and may be an air-cooled type cooler that cools the working fluid through heat exchange with the outside air. The working fluid passing through the condenser 500 is supplied to the compressor 100 (4).

The compressor 100 compresses the working fluid cooled in the condenser 500 to bring it into a high pressure state and the working fluid passing through the compressor 100 is branched from the separator S to flow into the recuperator 200, And (6, flow rate m2) economizer 6 (flow rate m1), respectively (the flow rate control of the working fluid will be described later).

The working fluid branched from the separator S toward the recuperator 200 undergoes heat exchange with the working fluid passing through the turbine 400 from the recuperator 200. Since the working fluid passing through the turbine 400 is relatively higher in temperature than the working fluid branched from the separator S toward the recuperator 200, the working fluid is deprived of heat and cooled. The working fluid branched from the separator S toward the recuperator 200 receives heat from the working fluid passing through the turbine 400 and is recovered and supplied to the mixer M at the rear stage of the economizer 640.

The working fluid branched from the separator S toward the economizer 640 absorbs heat from the discharged exhaust gas and reheats the working fluid. The reheated working fluid is sent to the mixer M (9).

The mixer M mixes the working fluid supplied from the recuperator 200 and the economizer 640 and supplies it to the fluid wall tube 620.

The fluid wall tube 620 is a tube assembly in which a working fluid flows therein, and is installed such that the working fluid flows in a direction from the upper portion of the boiler 600 toward the lower furnace 610. Since the working fluid is carbon dioxide in the supercritical state, no phase separation occurs in the fluid wall tube 620, so that phase separation does not occur inside the fluid wall tube 620. Thus, fluid flow from top to bottom of the fluid wall tube 620 is possible (count current flow) to increase the heat exchange efficiency. The working fluid flows along the fluid wall tube 620 while being heated (11) by absorbing the heat generated by the combustion of the fuel in the furnace 610 and heating it to the superheater 630.

The working fluid finally heated in the superheater 630 is superheated and circulated to the turbine 400 (1).

In the hybrid power generation system using the supercritical carbon dioxide working fluid according to an embodiment of the present invention having the above-described configuration, the flow rate control of the working fluid will be briefly described as follows.

The rate at which the operation fluid (flow rate m1) branched to the economizer 640 is lower than the temperature (the temperature at 9) after absorbing the heat of the combustion gas and the recuperator (Temperature at 8) after the working fluid (flow rate m2) branched to the turbine 100 and the turbine 100 absorbs the heat of the working fluid through the turbine 100 is adjusted. That is, the inflow temperature of the mixer M to be described later is controlled to be equal. At this time, it is preferable to keep the temperature difference between the outlet 3 of the high-temperature fluid side and the inlet 6 of the low-temperature fluid side of the recuperator 200 constant.

Therefore, if the temperature (at 9) after passing through the economizer 640 is greater than the temperature (at 8) after passing through the recuperator 200, the flow rate m1 of the working fluid supplied to the economizer 640 . Conversely, when the temperature (at 9) after passing through the economizer 640 is lower than the temperature (the temperature at 8) after passing through the recuperator 200, the flow rate m1 of the working fluid supplied to the economizer 640 Is lowered.

The heat exchange flow in the boiler of the hybrid power generation system using the supercritical carbon dioxide working fluid of the present invention and the conventional steam power generation system will be described in detail as follows.

FIG. 4 is a view showing a heat exchange flow of the working fluid according to FIG. 1, and FIG. 5 is a view showing a heat exchange flow of the working fluid according to FIG.

4, the combustion gas including the heat of combustion of the boiler 600 in the conventional thermal power generation system moves from the lower furnace 610 of the boiler 600 to the upper side of the boiler 600 (see Hot Gas Flow ). At this time, the water separated from the drum 65 enters the lower part of the boiler 600 along the flow path 9, and circulates along the water-cooling wall from the lower part of the boiler 600 to the upper part. Since the flow direction of the water / steam as the working fluid is the direction from the lower part to the upper part of the boiler 600, the heat flows along the same direction as the circulation direction of the combustion gas and concurrent flow occurs.

The temperature of the bottom of the boiler 600 is relatively high and the temperature of the bottom of the boiler 600 is relatively low. The temperature of the water / steam is relatively low at the lower part of the boiler 600, ). However, since the flow direction of the combustion gas and the water / steam is the same, the high temperature combustion gas and the low temperature water / steam exchange heat, and the relatively low temperature combustion gas and the high temperature water / steam heat exchange. Therefore, assuming that the temperature of the combustion gas under the boiler 600 is the highest temperature (100%), the temperature of the combustion gas above the boiler 600 can be regarded as about 50%. Assuming that the temperature of the water / steam supplied to the lower part of the boiler 600 is the lowest temperature (0%), the water / steam temperature at the upper part of the boiler can be regarded as about 50% of the temperature. Accordingly, the exchange gradient of the combustion gas and the water / steam in the lower part and the upper part of the boiler 600 becomes approximately 50%.

5, the combustion gas including the heat of combustion of the boiler 600 in the hybrid power generation system of the present invention moves toward the upper portion of the boiler 600 from the lower furnace 610 of the boiler 600 Gas flow). At this time, the working fluid supplied through the mixer M flows into the upper portion of the boiler 600 and circulates from the upper portion of the boiler 600 to the lower portion along the fluid wall. Since the flow direction of the supercritical carbon dioxide as the working fluid is the direction from the upper portion to the lower portion of the boiler 600, the heat exchange occurs along the opposite direction to the circulation direction of the combustion gas (Counter current flow).

The combustion gas has a relatively high temperature at the lower part of the boiler 600 and a lower temperature at the upper part. The operating fluid has a relatively lower temperature at the upper part of the boiler 600 and a higher temperature at the lower part (right graph in FIG. 4) . Since the flow direction of the combustion gas and the water / steam is opposite to each other, the high temperature combustion gas and the high temperature working fluid undergo heat exchange, and the relatively low temperature combustion gas and the low temperature working fluid undergo heat exchange. Assuming that the temperature of the combustion gas under the boiler 600 is the highest temperature (100%), the temperature of the combustion gas above the boiler 600 can be regarded as about 0%. Assuming that the temperature of the working fluid supplied to the upper part of the boiler 600 is the lowest temperature (0%), the working fluid temperature under the boiler can be regarded as about 100% of the temperature. Accordingly, the exchange gradient of the combustion gas and the working fluid in the lower portion and the upper portion of the boiler 600 is approximately 100%.

FIG. 6 is a graph showing the relationship between the temperature of the working fluid and the specific heat capacity (TS) according to FIG. 3, and FIG. 7 is a graph showing the temperature change of the inlet tube of the water cooling wall according to the variation of the economizer heat capacity The description will be made with reference to FIG. 2).

The steam generator using water / steam as the working fluid causes water / steam to circulate in the water-cooling wall tube 62 for cooling the furnace. The temperature of the circulating water / steam is controlled by the saturation temperature (Wall tube section in Fig. 2). Therefore, when the temperature of the inlet of the economizer 64 (the third point of FIG. 2) and the temperature of the outlet of the superheater 63 (the first point of FIG. 2) are limited, the heat capacity of each heat exchanger (economizer, superheater, .

In contrast, since the hybrid power generation system of the present invention uses supercritical carbon dioxide as the working fluid, there is no restriction on the saturation temperature of the working fluid as shown in FIG. 6 during power generation (the temperature of the wall tube section of FIG. 6 continuously increases ). Therefore, even if the temperature of the inlet of the economizer 640 (point 7 in FIG. 6) is determined, the temperature of the economizer 640 can be adjusted to adjust the temperature of the inlet of the fluid wall tube 620 have. The inlet / outlet temperature of the fluid wall tube 620 is limited only by the tubing material, and as shown in FIG. 7, when the temperature of the outlet of the superheater 630 (point 1 in FIG. 6) The heat capacity of the superheater 630 and the heat capacity of the super heater 630 have a trade-off relationship. Therefore, each heat exchanger (economizer, superheater, etc.) can be controlled according to the heat capacity distribution, thereby realizing a highly efficient power generation system.

In addition, since there is no phase change of the working fluid, installation of a drum for separating the water is not necessary, and the pressure of the fluid expanded in the turbine is sufficiently high, so that a separate booster pump is not required after the cooler (condenser). Therefore, the power generation system can be simplified and configured.

One embodiment of the present invention described above and shown in the drawings should not be construed as limiting the technical spirit of the present invention. The scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can improve and modify the technical spirit of the present invention in various forms. Accordingly, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

100: compressor 200: recuperator
400: turbine 500: condenser
600: boiler 610: furnace
620: Fluid wall tube 630: Superheater
640: Economizer 650: Air preheater
S: Separator M: Mixer

Claims (20)

A boiler provided with a furnace for combusting fuel to generate combustion heat, a plurality of heat exchangers for heating a working fluid using the combustion heat,
A turbine driven by the working fluid heated in the boiler;
A recuperator for performing heat exchange with the working fluid through the turbine to cool the turbine;
A condenser for cooling the working fluid through the recuperator,
And a compressor for compressing the working fluid cooled in the condenser,
Wherein the working fluid is supercritical carbon dioxide. ≪ RTI ID = 0.0 > 8. < / RTI > The method according to claim 1,
The superheater is installed on the upper end of the boiler and heats the working fluid flowing into the boiler. The superheater is provided at a discharge end of the boiler to absorb heat from the combustion gas discharged after burning the fuel, A hybrid power generation system using a supercritical carbon dioxide working fluid comprising an economizer for heating an incoming working fluid. 3. The method of claim 2,
Further comprising a separator provided at a rear end of the compressor, the separator separating the working fluid through the compressor into the recuperator and the economizer, respectively. The method of claim 3,
Wherein the working fluid branched to the recuperator is heat-exchanged with the working fluid passing through the turbine, and is supplied to the boiler after being reheated. 5. The method of claim 4,
Wherein the working fluid diverted to the economizer is heated in the economizer and fed to the boiler. 6. The method of claim 5,
Further comprising a mixer which is provided outside the boiler and which is branched from the separator and mixes the recirculator and the economizer with the rough working fluid and supplies the mixture to the boiler. The method according to claim 6,
Wherein the boiler further comprises a fluid wall tube disposed along the longitudinal direction inside the boiler, the fluid wall tube circulating inside the mixer through the mixer to cool the furnace. 8. The method of claim 7,
Wherein the fluid wall tube moves the working fluid from the top to the bottom of the boiler. 9. The method of claim 8,
Wherein the working fluid passing through the fluid wall tube is supplied to the superheater, and the working fluid passing through the superheater is circulated to the turbine. 9. The method of claim 8,
Wherein the flow rate of the working fluid branched from the separator is branched to the economizer so that the temperature of the working fluid after absorbing the heat of the combustion gas is branched to the recuperator via the compressor, Wherein the temperature of the working fluid after absorbing the heat of the working fluid through the turbine is adjusted to be the same. A superheater installed on the upper side of the boiler for heating a working fluid and a heater disposed at a discharge end of the boiler to absorb heat from the combustion gas discharged after burning the fuel An economizer for heating the working fluid; a boiler having a fluid wall tube for circulating the working fluid therein to cool the furnace;
A turbine driven by the working fluid;
A recuperator for performing heat exchange with the working fluid through the turbine to cool the turbine;
A condenser for cooling the working fluid through the recuperator,
And a compressor for compressing the working fluid cooled in the condenser,
Wherein the working fluid is heated in the boiler and fed to the turbine to maintain a one-phase state in the boiler. 12. The method of claim 11,
Wherein the working fluid flows into the upper side of the fluid wall tube and is discharged to the lower side of the furnace. 13. The method of claim 12,
Further comprising a separator provided at a rear end of the compressor, the separator separating the working fluid through the compressor into the recuperator and the economizer, respectively. 14. The method of claim 13,
Wherein the working fluid branched to the recuperator is heat-exchanged with the working fluid passing through the turbine, and is supplied to the boiler after being reheated. 15. The method of claim 14,
Wherein the working fluid diverted to the economizer is heated in the economizer and fed to the boiler. 16. The method of claim 15,
Further comprising a mixer which is provided outside the boiler and which is branched from the separator and mixes the recirculator and the economizer with the rough working fluid and supplies the mixture to the boiler. 17. The method of claim 16,
Wherein the flow direction of the working fluid in the fluid wall tube is opposite to the flow direction of the combustion gas. 18. The method of claim 17,
Wherein the working fluid passing through the fluid wall tube is supplied to the superheater, and the working fluid passing through the superheater is circulated to the turbine. 14. The method of claim 13,
Wherein the flow rate of the working fluid branched from the separator is branched to the economizer so that the temperature of the working fluid after absorbing the heat of the combustion gas is branched to the recuperator via the compressor, Wherein the temperature of the working fluid after absorbing the heat of the working fluid through the turbine is adjusted to be the same. 20. The method of claim 19,
And controlling the flow rate of the working fluid to be supplied to the economizer to be higher when the temperature of the working fluid after the absorption of the heat of the combustion gas in the economizer is larger than the temperature of the working fluid after absorbing heat in the recuperator Wherein when the temperature of the working fluid after the absorption of the heat of the combustion gas in the economizer is lower than the temperature of the working fluid after the heat is absorbed by the recuperator, the flow rate ratio of the working fluid supplied to the economizer Wherein the supercritical carbon dioxide working fluid is controlled to be lowered.

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