KR101461828B1 - Apparatus for Converting Thermal Energy - Google Patents

Abstract

The present invention provides an apparatus for converting thermal energy which uses working fluid in which at least two fluids having different boiling points are mixed. The apparatus for converting thermal energy includes: an evaporator for generating evaporated working fluid by exchanging heat between heat source fluid and working fluid; an energy converting means which is connected to the evaporator and receives evaporated working fluid to convert energy of the evaporated working fluid into mechanical energy; a condenser which is connected to the energy converting means to condense consumed working fluid; a pumping means which is connected to the condenser to increase pressure by pressurizing the condensed working fluid; a separator which receives evaporated working fluid between the evaporator and the energy converting means to divide into a thick flow and a rarefied flow; a concordant flow part at which the thick flow and the rarefied flow consumed after passing through the energy converting means are joined; a throttle valve arranged between the concordant flow part and the separator to lower the pressure of the rarefied flow to the same pressure as a first thick flow passing through the energy converting means; a first heat exchanger which is located at the front end of the evaporator and in which a heat source fluid passing through the evaporator and the working fluid passing through the pumping means exchange heat with each other; and a second heat exchanger which is located between the first heat exchanger and the evaporator and in which the temperature-increased working fluid and the rarefied flow exchange heat with each other.

Description

[0001] Apparatus for Converting Thermal Energy [

The present invention relates to a device for converting thermal energy from a heat source using an expanded and regenerated working fluid and more specifically to a device for converting a thermal energy at a low temperature using two or more mixed working fluids, To extract a large amount of power and to convert the heat energy capable of controlling the cycle according to the condition of the heat source.

Thermal power plants using coal, oil or gas as fuel typically use water as the working fluid. In the case of LNG combined-cycle power generation, since the exhaust gas from the gas turbine is high at 500 to 600 ° C., the steam is converted into steam and the steam turbine is driven to generate electricity.

A low-temperature and low-temperature array power generation technology is being developed and expanded at a temperature of 100 to 500 ° C for generating electricity using an array source having a temperature lower than that of a conventional steam generator. To develop at low temperatures, a working fluid with a boiling point at a low temperature, i.e. a refrigerant or a hydrocarbon-based fuel, is used. The organic rankine cycle system, the kalina cycle, and the uehara cycle system, depending on the characteristics of the working fluid or the system configuration. The organic Rankine cycle utilizes a single working fluid, while the Carina and Uehara cycle systems use a mixture of ammonia and water.

The organic Rankine cycle, which is a normal Rankine cycle, is composed of basic elements of an evaporator 40, a turbine 50, a condenser 20 and a pump 30 as shown in FIG. 1, and the generator 50 is connected to the turbine 50, And converts the mechanical energy converted by the turbine 50 into electric energy. The evaporator 40 is a place where the working fluid is phase-changed to a gas by heat and the turbine 50 serves to change the pressure difference between the evaporator 40 and the condenser 20 to a work. The condenser 20 is a turbine 50) from the low-temperature low-pressure working fluid to the liquid. The pump 30 serves to supply the low-pressure working fluid in the condenser to the evaporator.

In this Rankine cycle, the low-temperature and low-pressure working fluid 1 passes through the pump 30 and becomes the working fluid 2 of low temperature and high pressure, becomes the working fluid 3 of high temperature and high pressure while passing through the evaporator 40, After passing through the turbine 50, the working fluid 4 becomes a low-pressure working fluid 4, and then through the condenser 20, the working fluid 1 becomes a low-temperature low-pressure working fluid again. do.

The organic Rankine cycle differs from the Rankine cycle in that it is a working fluid that evaporates at low temperatures using organic materials with a lower boiling point than water. Organic Rankine cycle is an organic material in which the working fluid consists of one component.

On the other hand, the Carina cycle uses ammonia water mixed with water and ammonia as a working fluid, unlike the organic Rankine cycle which uses a pure substance as a working fluid. 2, the low-temperature and low-pressure working fluid 1 is discharged to the high-pressure working fluid 2 through the pump 30 and is preheated in the preheater or regenerator 45, do. Thereafter, the gas is vaporized through the evaporator 40 to become a high-temperature high-pressure working fluid 3, and the working fluid 3 flows into the gas-liquid separator 60. Here, the saturated liquid containing a large amount of water is separated into a lean stream (7) containing little ammonia and a concentrated stream (6), which is a saturated steam which is mainly composed of ammonia. The concentrated stream (6) is supplied to the turbine The turbine 50 converts the chemical energy into mechanical energy and the mechanical energy produces electricity through the generator (not shown), and then the enrichment 6 is converted into the consumed enrichment 11 ).

The lean stream 7 in a high temperature state is sent to a preheater or regenerator 45 to recover the heat while preheating the working fluid 2 to become a heat exchanged lean flow 8. The reheated lean stream 8 is supplied to a throttle valve The pressure is lowered to the pressure at the rear end of the turbine 50 and becomes the lean stream 9 of low pressure. The low-pressure diluent 9 and the spent rich stream 11 are mixed in the absorber 80 to become the working fluid 10. The working fluid 10 is supplied to the condenser 11 and becomes the working fluid 1 in a state where the working fluid 10 is condensed by the cooling water of low temperature.

The heating fluid having a high temperature heat source is supplied to and discharged from the evaporator 40, and the cooling water is supplied to and discharged from the condenser 20. The carina cycle can regulate the opening of the pressure controller 70 while adjusting the level of the gas-liquid separator 60.

In this carina cycle design, it is necessary to increase the amount of rich flow in the gas-liquid separator 60 to increase the amount of power generation. For this purpose, it is necessary to supply the working fluid in the saturated liquid state at the front end of the evaporator 40.

On the other hand, in the case of geothermal power generation, since the temperature of the heat source is not constant and the heat source is heated due to the geothermal heat, the generation amount itself is important even though the thermal efficiency is somewhat lower than the thermodynamic efficiency. When constructing a system to increase the thermal efficiency, the thermal efficiency itself may rise, but there is a problem that it may be lagged at a power generation amount that is obtained from the case where more heat sources are absorbed from the heat source.

On the other hand, Patent Document 1 discloses a configuration in which heat exchange is performed a plurality of times with a heat source. However, in the case of Patent Document 1, the heat exchange between the working fluid and the heat source after passing through the gas-liquid separator does not affect the amount of the working fluid separated by the gas-liquid separator, There is a problem that you can not.

(Patent Document 1) WO 2004-102082 A

The present invention aims to further convert the heat energy even though the thermal efficiency is reduced by adding preheating and changing the order of the working fluid to fully utilize the heat source.

In order to achieve the above object, the present invention provides an apparatus for converting heat energy as follows.

The present invention relates to an evaporator, comprising: an evaporator for heat exchange with a heat source fluid and a working fluid to produce an evaporative working fluid; Energy conversion means connected to the evaporator for receiving an evaporation working fluid to convert the energy of the evaporation working fluid into mechanical energy; A condenser connected to the energy conversion means for condensing the spent working fluid; And a pumping means connected to the condenser for pumping and pressurizing the condensed working fluid, wherein the working fluid is mixed with two fluids having different boiling points of 2 or more, the apparatus comprising: A separator for receiving the evaporative working fluid and separating the evaporated working fluid into a rich stream and a lean stream; A merging portion in which the spent rich stream having passed through the energy conversion means and the lean flow are merged; A throttle valve disposed between the merging section and the separator to lower the lean flow to the same pressure as the first rich flow passing through the energy conversion section; A first heat exchanger located at a front end of the evaporator and performing heat exchange between the heat source fluid passing through the evaporator and the working fluid passing through the pumping means; And a second heat exchanger located between the first heat exchanger and the evaporator, the second heat exchanger performing heat exchange between the heated working fluid and the lean flow.

At this time, the first heat exchanger and the second heat exchanger may be configured so that the working fluid that has passed through the second heat exchanger becomes a saturated liquid.

A branching unit for branching the working fluid that has passed through the condenser into a first flow path and a second flow path; A third heat exchanger connected to the first flow path of the branch portion and performing heat exchange between the combined working fluid of the merging portion and the working fluid passing through the condenser; And a second merging portion in which a working fluid that has passed through the third heat exchanger and a working fluid that has passed through the second flow path join together.

In addition, the present invention is characterized by a flow control valve disposed in the first flow path and the second flow path, respectively; A temperature sensor disposed on an evaporator inlet side to measure a temperature of the heat source fluid flowing into the evaporator; And a controller connected to the flow rate control valve and the temperature sensor, wherein the controller can adjust the flow rate of the first flow path and the second flow path based on the temperature of the heat source fluid measured by the temperature sensor.

Further, the control unit may adjust the flow rate of the working fluid supplied to the evaporator through the first flow path and the second flow path so as to be supplied to the saturated liquid.

When the ammonia concentration is low in the carina cycle design, the evaporation temperature of the water increases, and the evaporator outlet temperature of the heat source must be increased. That is, even if the thermal efficiency is increased, the heat source flow rate may need to be increased.

Considering the above points, the present invention can sufficiently utilize a heat source and increase the amount of energy conversion by adding an additional heat source recovery heat exchanger in a heat source and changing the preheating sequence to lower the outlet temperature of the heat source.

In addition, it is possible to adjust the cycle according to the condition of the heat source, and it is possible to provide the working fluid introduced into the evaporator as the saturated liquid.

1 is a block diagram of a conventional Rankine cycle.
2 is a configuration diagram of a conventional Carina cycle.
3 is a schematic diagram of an apparatus for converting heat energy according to an embodiment of the present invention.
4 is a schematic diagram of an apparatus for converting heat energy according to another embodiment of the present invention.

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

In the embodiment of the present invention, a mixture of water and ammonia is used as a working fluid. However, the present invention corresponds to the working fluid of the present invention when two or more fluids having different boiling points are mixed and used.

When a heat source such as geothermal heat is circulated in an open cycle, the power generation cycle is more important than the efficiency of the cycle itself. That is, if a large amount of heat can be extracted from the heat source, the efficiency of the power generation cycle can be increased because more power can be obtained even if the efficiency is somewhat inferior. As the heat source, heated water, oil, gas, or the like may be applied to the heat source, but it is needless to say that various heat sources can be applied.

The present invention is based on this point and increases the amount of generated power by transferring a large amount of heat to the working fluid by heating the working fluid again by heat-exchanging the heat source through the evaporator.

In addition, the present invention provides a working fluid in a saturated liquid state before passing through an evaporator so that a working fluid passing through an evaporator can be supplied to the turbine 50, which is an energy conversion means, using a heat source that has passed through an evaporator In addition, it is based on utilizing the working fluid before condensation.

The present invention includes all the configurations of FIG. 2, which is a typical carina cycle. However, in order to supply a larger amount of heat from a heat source and to supply a working fluid in a saturated liquid state before the evaporator, To the heat exchanger.

Figure 3 is a schematic diagram of one embodiment of the present invention.

The working fluid P1 that has passed through the condenser 20 in which the cooling water flows into the inlet 23 and the outlet 24 flows through the pumping means 30 and is pressurized to the working fluid P2. The pressurized working fluid P2 passes through the third heat exchanger 70, which is heat-exchanged with the working fluid P16 joined through the merging portion 110. [ The working fluid P2 that has been increased while passing through the third heat exchanger 70 is heated to become the temperature increasing working fluid P3.

The temperature increasing working fluid P3 that has passed through the third heat exchanger 70 is supplied to the first heat exchanger 80 and is supplied to the first heat exchanger 80 through the heat source fluid 26 passing through the evaporator 40, do. The temperature of the heat source fluid 26 passing through the evaporator 40 is lower than the temperature of the heat source fluid before the evaporator 40 is introduced but after passing through the condenser 20 and passing through the third heat exchanger 70, Temperature working fluid P3 in the first heat exchanger 70 receives energy from the heat source fluid 26 to become the working fluid P8.

The working fluid P8 is supplied to the second heat exchanger 90 so as to heat-exchange with the leachate P11 separated into liquid in the gas-liquid separator 60. [ Since the gas-liquid separator 60 is disposed at the evaporator downstream end 40, it has a temperature approximately equal to the outlet temperature of the evaporator 40, and thus has a higher temperature than the working fluid P8 to raise the working fluid P8 It is possible. At this time, the first heat exchanger 80 and the second heat exchanger 90 are preferably adjusted in capacity so that the working fluid P9 that has passed through the second heat exchanger 90 becomes a saturated liquid.

The working fluid (P9) that has passed through the second heat exchanger (90) is supplied to the evaporator (40). In the evaporator, in the evaporator 40, the working fluid P9 undergoes heat exchange with the high-temperature heat source fluid 25, and a large amount of working fluid becomes vaporized high-temperature working fluid P10. The high temperature heat source fluid may flow into the evaporator 40 through the inlet 25 and the outflow 26 and the heat source of the open cycle such as geothermal heat may be used.

The high temperature working fluid P10 that has passed through the evaporator 40 is supplied to the gas-liquid separator 60 and separated into the rich stream P12 and the lean stream P11 in the gas-liquid separator 60. The rich stream P12 is supplied to the turbine 50 corresponding to the energy conversion means and is converted into mechanical energy as the pressure and temperature decrease while passing through the turbine 50. [ Generally, the mechanical energy converted by the turbine 50 is converted back to electrical energy through a generator (not shown).

On the other hand, in the gas-liquid separator 60, the rare gas P11 having a low ammonia concentration passes through the second heat exchanger 90 sequentially in the state of high pressure, and transfers the heat energy to the working fluid P8, Resulting in a lowered lean stream (P13). The lean flow P13 that has passed through the second heat exchanger 90 passes through the throttle valve 100 and becomes low at the pressure before the pumping means 30 to become the lean flow P14. The lean stream P14 is combined with the exhausted rich stream P15 passing through the turbine 50 which is the energy conversion means at the merging section 110 and becomes the merging lean stream P16.

The combined lean sparge P16 is supplied to the third heat exchanger 70 and transfers the heat energy that has been flowing through the third heat exchanger 70 to the working fluid P2.

The working fluid P17 is supplied to the condenser 20 so that all of them are condensed into liquid.

On the other hand, Fig. 4 shows another embodiment of the present invention.

3, the first and third heat exchangers 70, 80 and 90 are provided with the same operation fluid P2 as the third heat exchanger 70, Is different.

The embodiment of Figure 4 includes a branch 120 before the working fluid P2 is supplied to the third heat exchanger 70 and the working fluid P2 at the branch 120 is passed through a third heat exchanger The working fluid P3 supplied to the first heat exchanger 70 and the working fluid bypassing the third heat exchanger 70 are branched.

The working fluid P3 supplied to the third heat exchanger 70 is heat-exchanged with the third heat exchanger 70 and then becomes the temperature increasing working fluid P4. This is because the working fluid P3 bypassing the third heat exchanger 70 And merges at the confluence portion 130 to become the confluence working fluid P5.

Flow control valves 140 and 150 are provided in both the line through which the bypass working fluid flows and the line through which the working fluid flows into the third heat exchanger 70, respectively. The flow control valves 140 and 150 are connected to a control unit (not shown) to control the flow rate of the respective lines. The controller (not shown) receives the temperature value of the heat source fluid supplied from the temperature sensor for measuring the temperature of the heat source fluid 25, and adjusts the working fluid P9 immediately before the evaporator to become a saturated liquid. By doing so, virtually the same effect as adjusting the capacity without adjusting the capacity of the heat exchanger (70, 80, 90) can be obtained.

In the conventional case (FIG. 2), a heat source having an inlet temperature of 150 ° C. and an outlet temperature of 110 ° C. is used, and in order to meet the turbine inlet condition of 140 ° C. and 3 MPa, h heat source is required, but in one embodiment of the present invention the same heat source conditions 150 ° C, 204 t / h), an output of 1350 kW is possible in the turbine 50, and the outlet temperature of the heat source is 97 ° C. That is, it is possible to recover many heat sources from the heat source having the same flow rate, thereby increasing the output.

One way is to change the ammonia concentration to increase the output even if the efficiency drops. If the above condition (the heat source flow rate is 204t / h, the ammonia concentration is increased to 75% at the heat source outlet temperature of 97 ° C, the output can be increased up to 1250kW.

20: condenser 30: pumping means
40: Evaporator 50: Turbine
60: gas-liquid separator 70: third heat exchanger
80: first heat exchanger 90: second heat exchanger
100: throttle valve 110, 130:
120: branch 140, 150: flow control valve

Claims (5)

An evaporator in which a heat source fluid and a working fluid exchange heat to generate an evaporative working fluid;
Energy conversion means connected to the evaporator for receiving an evaporation working fluid to convert the energy of the evaporation working fluid into mechanical energy;
A condenser connected to the energy conversion means for condensing the spent working fluid;
And a pumping means connected to the condenser for pressurizing and pressurizing the condensed working fluid and using a working fluid in which two fluids having two or more different boiling points are mixed,
A separator for receiving an evaporative working fluid between the evaporator and the energy conversion means and separating the evaporated working fluid into a rich stream and a lean stream;
A merging portion in which the spent rich stream having passed through the energy conversion means and the lean flow are merged;
A throttle valve disposed between the merging section and the separator to lower the lean flow to the same pressure as the first rich flow passing through the energy conversion section;
A first heat exchanger located at a front end of the evaporator and performing heat exchange between the heat source fluid passing through the evaporator and the working fluid passing through the pumping means; And
And a second heat exchanger located between the first heat exchanger and the evaporator, the second heat exchanger performing heat exchange between the heated working fluid and the lean flow.
The method according to claim 1,
Wherein the first heat exchanger and the second heat exchanger are configured so that the working fluid that has passed through the second heat exchanger becomes a saturated liquid.
The method according to claim 1,
A branching portion for branching the working fluid that has passed through the condenser to the first flow path and the second flow path;
A third heat exchanger connected to the first flow path of the branch portion and performing heat exchange between the combined working fluid of the merging portion and the working fluid passing through the condenser; And
Further comprising: a second merging unit for merging a working fluid that has passed through the third heat exchanger and a working fluid that has passed through the second flow path.
The method of claim 3,
A flow control valve disposed in the first flow path and the second flow path, respectively;
A temperature sensor disposed on an evaporator inlet side to measure a temperature of the heat source fluid flowing into the evaporator; And
And a controller connected to the flow rate control valve and the temperature sensor,
Wherein the controller controls the flow rate of the heat source fluid passing through the first flow path and the second flow path based on the temperature of the heat source fluid measured by the temperature sensor.
5. The method of claim 4,
Wherein the controller controls the flow rate of the working fluid supplied to the evaporator through the first flow path and the second flow path so as to be supplied to the saturated liquid.

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