KR101559251B1 - Organic Rankine Cycle System and Method for That Same - Google Patents

Abstract

An organic rankine cycle system according to an embodiment of the present invention to improve exergy efficiency includes: a compressing unit which pressurizes a working fluid; a heating unit which heats the working fluid pressurized by the compressing unit; an expansion unit which is connected to a power generator and generates power for operating the power generator by using the working fluid heated by the heating unit to allow the power generator to produce power; and a condensation unit which condenses the working fluid discharged to the expansion unit by using LNG. The working fluid consists of a ternary system material.

Description

[0001] The present invention relates to an organic Rankine cycle system,

The present invention relates to a Rankine cycle system, and more particularly to an organic Rankine cycle system.

The Rankine Cycle system consists of a pump, an evaporator, a turbine, and a condenser. It is a cycle in which the isothermal expansion and compression process, which can not be realized in the Carnot cycle, are replaced by static pressure expansion and compression processes.

The structure of the Rankine cycle system is composed of an evaporator 10, a turbine 20, a condenser 30 and a pump 40, as shown in FIG. Of these Rankine cycle systems, the Rankine cycle system, which mainly uses an organic medium as a working fluid, is referred to as an Organic Rankine Cycle system. The organic Rankine cycle system has a relatively low temperature range (60 to 200 DEG C ) To recover the heat source and produce energy.

The operation of this organic Rankine cycle system will be described in more detail with reference to FIG.

2 is a graph showing the temperature and entropy relationship of the organic Rankine cycle system.

As shown in FIG. 2, the 1-2 process is a compression process in which the working fluid in the low-pressure liquid state is compressed by the pump and becomes the working fluid in the high-pressure liquid state.

The process 2-3 is a heating process in which the working fluid in the high-pressure liquid state is heated by the evaporator and becomes a working fluid in the high-pressure gas state. At this time, as shown in Fig. 2, heat of Q _in is required to make the working fluid in the high-pressure liquid state as the working fluid in the high-pressure gaseous state.

Step 3-4 is an expansion process, in which the working fluid in the high-pressure gas state becomes the working fluid in the low-pressure gas state by the turbine. At this time, the working fluid in the high-pressure gaseous state rotates the axis of the generator in the _turbine to produce one (W _turbine ), which causes the pressure and temperature of the working fluid to become low,

Step 4-1 is a condensation process in which a working fluid in a low-pressure gas state is condensed by a condenser and becomes a working fluid in a low-pressure liquid state. At this time, as shown in FIG. 2, heat of Q _out from the working fluid is discharged to the outside. The working fluid condensed by the condenser is returned to the pump.

However, since the organic Rankine cycle system as described above is required to receive heat from an external heat source in order to heat the working fluid, not only the energy efficiency is lowered but also the single-component organic medium is used as the working fluid. The exergy efficiency of the system can not be maximized.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic Rankine cycle system capable of improving exergy efficiency and a control method thereof, which are designed to solve the above problems.

It is another object of the present invention to provide an organic Rankine cycle system and a control method thereof that can improve energy efficiency.

According to an aspect of the present invention, there is provided an organic Rankine cycle system including: compression means for pressing a working fluid; Heating means for heating the working fluid pressurized by the compression means; An expansion means connected to the generator for generating power to operate the generator using a working fluid heated by the heating means so that the generator produces electric power; And condensing means for condensing the working fluid discharged from the expansion means using liquefied natural gas (LNG), wherein the working fluid is composed of a three-component material.

In one embodiment, the three-component material comprises two materials selected from the group consisting of R 3, R 30, R 601, R 2 45fa, and R 2 36fa with R23 as the base material, The material is characterized in that it is composed of one material selected from the group consisting of R30, R601, R245fa, and R236fa, R23, and R14.

The heating means includes a preheater for preheating the working fluid; An evaporator for evaporating the working fluid preheated by the preheater using steam generated in the power generation facility; And a superheater which superheats the working fluid evaporated by the evaporator.

The organic Rankine cycle system further includes carbon dioxide collecting means for collecting carbon dioxide and liquefying the collected carbon dioxide, wherein the heating means preheats the working fluid using liquefaction heat generated when the collected carbon dioxide is liquefied .

The expansion means includes a high-pressure turbine and a low-pressure turbine, connected to the generator, for generating power for operating the generator using a working fluid heated by the heating means; And a reheater that reheats the working fluid discharged from the high-pressure turbine to overheat and supplies the working fluid in an overheated state to the low-pressure turbine.

According to another aspect of the present invention, there is provided a method of controlling an organic Rankine cycle system, the method comprising: pressurizing a working fluid composed of a three-component material; Heating the pressurized working fluid; Rotating the turbine using the heated working fluid to generate power; And condensing the working fluid discharged from the turbine using liquefied natural gas (LNG).

Wherein the three-component material comprises two materials selected from the group consisting of R14, R30, R601, R245fa, and R236fa with R23 as the base material, and preferably the three-component material is selected from the group consisting of R30, R601, R245fa, And R236fa, R23, and R14.

Wherein the heating step comprises: preheating the working fluid using liquefaction heat generated when liquefied carbon dioxide is collected; Evaporating the preheated working fluid using steam generated in a power plant; And bringing the evaporated working fluid into an overheated state.

Wherein the generating comprises: supplying the heated working fluid to a high pressure turbine to generate power; Reheating the working fluid discharged from the high-pressure turbine to overheat; And supplying the working fluid reheated to an overheated state to the low-pressure turbine to generate electric power.

According to the present invention, since a multi-component material having thermal properties similar to the thermal characteristics of liquefied natural gas used as a refrigerant is used as a working fluid, energy recovery from the refrigerant can be increased during condensation of the working fluid, Is improved.

Further, according to the present invention, the working fluid is preheated through the heat exchange between the collected gaseous carbon dioxide and the working fluid, and the captured gaseous carbon dioxide can be liquefied, so that the heat energy The amount of condensed energy required for liquefaction of carbon dioxide captured in gaseous state can be reduced, and energy efficiency is improved.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram showing the construction of a general organic Rankine cycle system.
2 is a graph showing the temperature and entropy relationship of the organic Rankine cycle system shown in FIG.
3 is a block diagram illustrating the configuration of an organic Rankine cycle system in accordance with one embodiment of the present invention.
4 is a graph showing the temperature and entropy relationship of the organic Rankine cycle system for each working fluid.
5A is a graph comparing the irreversibility of an organic Rankine cycle system using a multi-component material as a working fluid and an organic Rankine cycle system using a one-component or two-component material as a working fluid.
FIG. 5B is a graph showing the electric power produced by an organic Rankine cycle system using a multi-component material as a working fluid and an organic Rankine cycle system using a one-component or two-component material as a working fluid.
6A to 6D are graphs showing a comparison of the heat curves of the respective working fluids.
FIG. 7 is a graph showing a comparison of the power generation amount of the organic Rankine cycle system for each working fluid.
8 is a table showing a comparison between the constituent components and the pressures of the respective working fluids.
9 is a graph showing the temperature and entropy relationship of an organic Rankine cycle system using a three component working fluid.

The meaning of the terms described herein should be understood as follows.

The word " first, "" second," and the like, used to distinguish one element from another, are to be understood to include plural representations unless the context clearly dictates otherwise. The scope of the right should not be limited by these terms.

It should be understood that the terms "comprises" or "having" does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, Means any combination of items that can be presented from more than one.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of an organic Rankine cycle system according to an embodiment of the present invention.

3, the organic Rankine cycle system 300 according to an embodiment of the present invention includes a compression means 310, a heating means 320, an expansion means 330, and a condensation means 340 do.

That is, the organic Rankine cycle system 300 according to an embodiment of the present invention is characterized in that the compression means 310, the heating means 320, the expansion means 330, and the condensing means 340 are sequentially connected And a working fluid for operating the organic Rankine cycle is circulated through the closed circuit and energy is generated through a generator (not shown) connected to the expansion means 330.

The compression means 310 compresses the working fluid. That is, the compression means 310 compresses the working fluid discharged from the condensing means 340, thereby increasing the pressure of the working fluid discharged from the condensing means 340. The compression means (310) is installed between the condensing means (340) and the heating means (320). Accordingly, the organic Rankine cycle system 300 according to the present invention increases the compression ratio of the working fluid by compressing the working fluid through the compression means 310 after cooling the working fluid through the condensing means 340 And the power generation efficiency can be improved.

In one embodiment, the compression means 310 may be implemented as a pump (Pump, Pl) as shown in FIG.

The heating means (320) heats the working fluid pressurized by the compression means (310). In one embodiment, the heating means 320 may include a preheater HX2, an evaporator HX3, and a superheater SH, as shown in FIG.

The preheater HX2 preheats the working fluid discharged from the compression means 310. [ In one embodiment, the preheater HX2 may preheat the working fluid using liquefied heat generated when liquefying the gaseous carbon dioxide into liquid carbon dioxide in the process of collecting carbon dioxide.

That is, the preheater HX2 heat-exchanges the gaseous carbon dioxide with the working fluid to liquefy the gaseous carbon dioxide into liquid carbon dioxide and preheat the working fluid.

As described above, according to the present invention, the organic Rankine cycle system 300 and the carbon capture and storage (CCS) are linked to use the liquefied heat generated in the carbon dioxide capture unit as the heat source of the organic Rankine cycle system 300 The energy efficiency can be improved.

The evaporator HX3 evaporates the working fluid discharged from the preheater HX2 using steam generated from a power generation facility (not shown). As described above, the present invention allows the organic Rankine cycle system 300 to heat the working fluid using waste heat such as steam generated in the power generation facility, thereby improving the energy recovery efficiency as well as the energy recovery efficiency.

The superheater (SH) superheats the working fluid discharged from the evaporator (HX3). That is, the superheater SH heats the working fluid to an overheated state so that the expansion means 330 can generate power using the working fluid.

In one embodiment, the heating means 320 may further include a first gas-liquid separator FLASH1 positioned between the preheater HX2 and the evaporator HX3, as shown in FIG. The first gas-liquid separator FLASH1 separates the gaseous component from the working fluid when a phase change occurs in the working fluid discharged from the preheater HX2.

The expansion means 330 serves to generate power for operating the generator by using the working fluid discharged from the heating means 320. That is, the expansion means 330 is connected to the generator and uses the working fluid discharged from the heating means 320 to generate power for operating the generator so that the generator produces electric power.

In one embodiment, the expansion means 330 comprises a high pressure turbine T1, a restrictor RH, and a low pressure turbine T2.

The high pressure turbine T1 generates power for operating the first generator (not shown) connected to the high pressure turbine T1 by using the working fluid discharged from the heating means 320. [ And the first generator is generated by the generated power to produce electric power.

That is, the working fluid discharged from the heating means 320 can generate power by rotating an impeller (not shown) of the high-pressure turbine T 1 while passing through the high-pressure turbine T 1. The first generator generates power using power provided from the high-pressure turbine (T1). The first generator may be connected to the high-pressure turbine (T1) through a shaft or the like.

The reheater (RH) reheats the working fluid discharged from the high-pressure turbine (T1) so that the working fluid is again overheated. As described above, since the working fluid is reheated by using the restrictor (RH) in the present invention, the temperature of the working fluid can be reduced due to the passage of the high-pressure turbine (T1) To supply the fluid to the low pressure turbine (T2).

The low-pressure turbine T2 generates power for operating a second generator (not shown) connected to the low-pressure turbine T2 by using a working fluid that has been overheated by the limiter RH. And the second generator is generated by the generated power to produce electric power.

That is, the working fluid discharged from the restrictor RH can generate power by rotating an impeller (not shown) of the low-pressure turbine T2 while passing through the low-pressure turbine T2. The second generator generates power using power provided from the low-pressure turbine (T2). The second generator may be connected to the low-pressure turbine (T2) through a shaft or the like.

As described above, according to the present invention, since the expansion means 330 is constituted by using the high pressure turbine and the low pressure turbine T1 and T2, the working fluid is injected into the high pressure turbine T1, And the working fluid reheated by the limiter RH is injected into the low-pressure turbine T2, thereby generating secondary power by the second generator connected to the low-pressure turbine T2, And at the same time, the power generation efficiency can be increased.

The condensing means (340) condenses the working fluid discharged from the expansion means (330) using Liquefied Natural Gas (LNG). In one embodiment, the condensing means 340 includes a first heat exchanger HX1 and a second heat exchanger HX4.

The first heat exchanger HX1 exchanges the liquefied natural gas with the working fluid to phase-convert the liquefied natural gas to the gaseous state and cools the working fluid.

The second heat exchanger HX4 is for completely vaporizing the liquefied natural gas when the liquefied natural gas that has passed through the first heat exchanger HX1 is not vaporized sufficiently and is a natural gas that has passed through the first heat exchanger HX1, And the working fluid discharged from the expansion means 330 is heat exchanged so that the liquefied natural gas is completely vaporized and the working fluid is primarily cooled.

The working fluid discharged from the second heat exchanger HX4 is injected into the first heat exchanger HX1 and is secondarily cooled.

Although the condensing means 340 has been described as including both the first and second heat exchangers HX1 and HX4 in the above-described embodiment, this is only one example. In a modified embodiment, the condensing means 340 May include only the first heat exchanger HX1. According to this embodiment, the working fluid discharged from the expansion means 330 is cooled by being exchanged with the liquefied natural gas through the first heat exchanger HX1 and then supplied to the compression means 310. The liquefied natural gas 1 heat exchanger HX1, and is discharged to the outside.

In the organic Rankine cycle system 300 according to the present invention having the above-described configuration, the working fluid can be constructed using materials having similar thermal characteristics of liquefied natural gas. That is, the working fluid according to the present invention may be composed of a material having a heat curve similar to the heat curve of liquefied natural gas. This is because the exergy efficiency of the organic Rankine cycle system 300 is improved when the working fluid is composed of materials having similar thermal characteristics of the liquefied natural gas used as the refrigerant of the working fluid, This is because a lot of energy can be recovered.

In one embodiment, the working fluid may be constructed using a multi-component system, particularly a three-component system material. FIG. 4 is a graph showing the relationship between the TS curve of steam, the TS curve of the working fluid constituted by using the one-component material (Pure), the TS curve of the working fluid constituted by using a binary material and the tertiary material (Ternary) The TS curve of the working fluid, and the TS curve of the liquefied natural gas. In Fig. 4, the X-axis represents the entropy (S) and the Y-axis represents the temperature (T).

As shown in FIG. 4, it can be seen that the thermal characteristics of a working fluid constructed using a three-component material (Ternary) are most similar to the thermal characteristics of a liquefied natural gas as disclosed in the present invention.

5A is a graph showing the irreversibilities of an organic Rankine cycle system using a multi-component material as a working fluid and an organic Rankine cycle system using a one-component or two-component material as a working fluid.

As shown in FIG. 5A, the organic Rankine cycle system using a multicomponent material as a working fluid has improved irreversibility by about 30% as compared with an organic Rankine cycle system using a one-component or two-component material as a working fluid. .

FIG. 5B is a graph showing an amount of electric power produced by an organic Rankine cycle system using a multi-component material as a working fluid and an organic Rankine cycle system using a one-component or two-component material as a working fluid.

As shown in FIG. 5B, it can be seen that the organic Rankine cycle system using a multicomponent material as a working fluid is improved by about 50% as compared with an organic Rankine cycle system using a one-component or two-component material as a working fluid .

In one embodiment, the working fluid may be composed of a three-component material consisting of two materials selected from the group consisting of R14, R30, R601, R245fa, and R236fa with R23 as the base material.

More preferably, the working fluid can be composed of one material selected from the group consisting of R30, R601, R245fa, and R236fa, and a three-component material consisting of R23 and R14.

That is, the working fluid according to one embodiment of the present invention includes a three-component material composed of R30, R23, and R14, a three-component material composed of R601, R23, and R14, Or a three-component material composed of R236fa, R23, and R14.

FIGS. 6A to 6D are graphs showing a comparison of the heat curves of the four three-component materials. FIG. 7 is a graph showing a comparison of power production amounts of four three-component materials, and FIG. This table shows the composition and pressure of three-component materials.

As can be seen from the graphs and tables shown in FIGS. 6 to 8, it can be seen that the efficiency of the three-component material composed of R601, R23, and R14 among the three three-component materials is the highest.

Hereinafter, the operation of the organic Rankine cycle system according to an embodiment of the present invention will be briefly described with reference to FIGS. 3 and 9. FIG.

9 is a graph showing the temperature and entropy relationship of an organic Rankine cycle system using a three component working fluid.

As described above, in the organic Rankine cycle system 300, the working fluid is a three-component material composed of R30, R23, and R14, a three-component material composed of R601, R23, and R14, , Or a three-component material composed of R236fa, R23, and R14.

3 and 9, the working fluid S1 discharged from the first heat exchanger HX1 is supplied to the pump P1 of the compression means 310, and the working fluid S1 is supplied to the pump P1, (P1).

The working fluid S2 compressed by the pump P1 is then supplied to the preheater HX2 of the heating means 320. [ The preheater HX2 liquefies the gaseous carbon dioxide VCO2 into the liquid state carbon dioxide LCO2 by heat-exchanging the gaseous carbon dioxide VCO2 and the working fluid S2, S3).

Thereafter, the first gas-liquid separator FLASH1 removes the gas component from the working fluid S3 and supplies the working fluid S4 composed of the liquid component to the evaporator HX3. As described above, since the first gas-liquid separator FLASH1 is included in the case where the phase change occurs in the working fluid S3, the first gas-liquid separator FLASH1 can be omitted if necessary. When the first gas-liquid separator FLASH1 is omitted, the working fluid S3 is directly supplied to the evaporator HX3.

Thereafter, the evaporator HX3 evaporates the working fluid S4 into the working fluid S5 by exchanging heat between the steam ST1 and the working fluid S4 or S3 provided in the power generation facility (not shown) The temperature of the steam ST1 provided in the steam generator ST1 is reduced and discharged to the steam ST2.

Thereafter, the superheater SH heats the working fluid S5 into a working fluid S6 in an overheated state and supplies it to the high-pressure turbine T1 of the expansion means 330. [

Thereafter, the high-pressure turbine T1 produces power for operating the first generator (not shown) connected to the high-pressure turbine T1 using the working fluid S6 in an overheated state. And the first generator generates electric power according to the power.

The working fluid S7 discharged from the high pressure turbine T1 is supplied to the richer RH and the richer RH reheats the working fluid S7 to make the working fluid S8 in an overheated state, . At this time, the rich water (RH) exchanges heat between the steam ST3 supplied from the power generation facility and the working fluid S7 to make the working fluid S7 into the superheated working fluid S8 and the temperature of the steam ST3 reduced Steam (ST4).

Thereafter, the low-pressure turbine T2 produces power for operating a second generator (not shown) connected to the low-pressure turbine T2 using the working fluid S8 in an overheated state. And the second generator generates electric power according to the power.

The working fluid S9 discharged from the low pressure turbine T2 is supplied to the second gas-liquid separator FLASH2 included in the condensing means 340. [ The second gas-liquid separator FLASH2 removes the gas component from the working fluid S9 and supplies the working fluid S11 composed of the liquid component to the second heat exchanger HX4. As described above, since the second gas-liquid separator FLASH2 is included in the case where a phase change occurs in the working fluid S9, it can be omitted if necessary. When this second gas-liquid separator FLASH2 is omitted, the working fluid S9 is directly supplied to the second heat exchanger HX4.

The second heat exchanger HX4 exchanges heat between the liquefied natural gas discharged from the first heat exchanger HX1 and the working fluid S11 to discharge the liquefied natural gas to the outside in a fully vaporized form NG, S11 to the working fluid S12 and discharges it to the first heat exchanger HX1.

The first heat exchanger HX1 exchanges heat between the liquefied natural gas and the working fluid S12 to vaporize the liquefied natural gas and reduces the temperature of the working fluid S12 to reduce the temperature of the working fluid S1, To the pump P1.

When the condensing means 340 includes only the first heat exchanger 344 as described above, the working fluid S11 is heat-exchanged with the liquefied natural gas through the first heat exchanger HX1 and cooled by the working fluid S1 Is supplied to the pump (P1) of the compression means (310), and the liquefied natural gas is vaporized by heat exchange through the first heat exchanger (HX1) and then discharged to the outside.

The control method of the organic Rankine cycle system may be implemented in a form of a program that can be performed using various computer means. The control method of the organic Rankine cycle system may be a hard disk, a CD-ROM, a DVD, a ROM ), A RAM, or a computer-readable recording medium such as a flash memory.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and from the equivalent concept are to be construed as being included in the scope of the present invention .

300: Glass Rankine cycle system 310: Compression means
320: Heating means 330: Expansion means
340: condensing means

Claims (11)

Compression means for pressurizing the working fluid;
Heating means for heating the working fluid pressurized by the compression means;
An expansion means connected to the generator for generating power to operate the generator using a working fluid heated by the heating means so that the generator produces electric power;
Condensing means for condensing the working fluid discharged from the expansion means using liquefied natural gas (LNG); And
And carbon dioxide collecting means for collecting carbon dioxide and liquefying the collected carbon dioxide,
The heating means preheats the working fluid by using the heat of liquefaction generated when the collected carbon dioxide is liquefied,
RTI ID = 0.0 > 1, < / RTI > wherein the working fluid comprises a three-component material. The method according to claim 1,
Wherein the three-component material comprises two materials selected from the group consisting of R23 as a base material and R14, R30, R601, R245fa, and R236fa. The method according to claim 1,
Wherein the three-component material consists of one material selected from the group consisting of R30, R601, R245fa, and R236fa, R23, and R14. The method according to claim 1,
The heating means,
A preheater for preheating the working fluid;
An evaporator for evaporating the working fluid preheated by the preheater using steam generated in the power generation facility; And
And a superheater for superheating the working fluid evaporated by the evaporator. delete The method according to claim 1,
Wherein the expansion means comprises:
A high pressure turbine and a low pressure turbine, connected to the generator, for generating power for operating the generator using a working fluid heated by the heating means; And
And a reheater which reheats the working fluid discharged from the high-pressure turbine to reheat and superheat the working fluid, and supplies a working fluid in an overheated state to the low-pressure turbine. Pressurizing a working fluid composed of a three-component material;
Heating the pressurized working fluid;
Rotating the turbine using the heated working fluid to generate power; And
And condensing the working fluid discharged from the turbine using liquefied natural gas (LNG)
Wherein the heating step comprises: preheating the working fluid using liquefaction heat generated when liquefied carbon dioxide is collected;
Evaporating the preheated working fluid using steam generated in a power plant; And
And converting the vaporized working fluid into an overheated state. 8. The method of claim 7,
Wherein the three-component material comprises two materials selected from the group consisting of R14, R30, R601, R245fa, and R236fa with R23 as the base material. 8. The method of claim 7,
Wherein the three-component material consists of one material selected from the group consisting of R30, R601, R245fa, and R236fa, R23, and R14. delete 8. The method of claim 7,
Wherein the generating comprises:
Supplying the heated working fluid to a high pressure turbine to generate electric power;
Reheating the working fluid discharged from the high-pressure turbine to overheat; And
And supplying power to the low-pressure turbine to generate electric power by re-heating the superheated working fluid to generate power.

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