KR101808111B1 - Low temperature power generation system - Google Patents

Abstract

To solve the problem, an embodiment of the present invention provides a low temperature power generation system, comprising: a lower temperature heat source unit; a vaporization unit where introduced work fluid absorbs thermal energy of the low temperature heat source unit; an expansion unit generating kinetic energy while the work fluid leaked from the vaporization unit is expanded; a power generation unit converting the kinetic energy into electric energy; a condensing unit cooling the gaseous work fluid to be condensed into the work fluid; and a liquid pump compressing the work fluid leaked from the condensing unit to be transferred to the vaporization unit.

Description

[0001] LOW TEMPERATURE POWER GENERATION SYSTEM [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generation system, and more particularly, to a low temperature power generation system that generates electricity using a low temperature heat source such as waste heat.

The waste heat generation system, which is generated by using waste heat from various processes of industrial plant facilities and waste heat generated from fuel cells, is used as a technology for using renewable energy which is generated by using low temperature heat. However, It is not widely available than the technology of using renewable energy.

In particular, a power generation technology using an organic working fluid (refrigerant) having a very low boiling point, such as refrigerant for refrigeration, for generating electricity using a low-temperature heat source, should be a technology for using renewable energy capable of utilizing waste heat of around 100 ° C. However, It is a reality that there is a technical limit which is extremely inefficient on the heat exchange type closed circuit.

The power generation cycle using the working fluid is circulated, for example, to compression, expansion, evaporation, expansion (evaporation), and condensation. At this time, in order to improve power generation efficiency, it is necessary to raise the temperature and the pressure at the same time and evaporate. However, considering the characteristics of the material, the evaporation conditions are lowered by the pressure, the evaporation is easy by raising the temperature, and the condensation condition is the condensation condition by raising the pressure and lowering the temperature.

In addition, the supply of the required heat amount based on the minimum heating temperature necessary for the evaporation capable of absorbing the latent heat of evaporation during the phase change in the evaporator is continued, so that the continuous evaporation of the working fluid enables generation of electricity. As such, it is impossible to expect economical power generation efficiency as a utilization technology of new and renewable energy. Therefore, it is required to develop a low temperature power generation system by a power generation cycle which can improve power generation efficiency by a new method.

Korean Patent Laid-Open No. 10-2016-0081758 (published on July 20, 2016) Korean Patent Publication No. 10-2011-0050328 (published on May 13, 2011) Korean Registered Patent No. 10-1162619 (registered on June 28, 2012)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a low-temperature power generation system in which a configuration of a conventional power generation cycle is partially modified.

It is also intended to provide a low-temperature power generation system capable of further improving the efficiency of a fuel cell independently used in a building or the like. At this time, the low-temperature power generation system is intended to be appropriately controlled in response to the temperature change of the low-temperature heat source. Further, it is desirable to provide a system in which the surplus portion of generated electricity can be stored through the energy storage device.

In order to solve the above-described problems, an embodiment of the present invention provides a low-temperature heat source unit, An evaporating portion in which an incoming liquid working fluid absorbs thermal energy of the low temperature heat source portion and is converted into a vapor operating fluid; An expansion unit for generating kinetic energy while expanding the vapor-phase working fluid flowing out from the evaporation unit; A generator for converting the kinetic energy into electrical energy; A condenser for cooling the gas-phase working fluid to condense it into a liquid working fluid; And a liquid pump for compressing the liquid working fluid flowing out from the condensing part and transferring the liquid working fluid to the evaporating part.

The low-temperature heat source may be waste heat generated in the fuel cell.

The expansion unit includes a casing; An expansion unit disposed at an inlet of the casing and having a diameter enlarged along the flow direction so as to increase the pressure of the gas-phase working fluid; A plurality of blade portions formed at a longitudinal end portion of the expansion portion and rotated by the flow of the gas-phase working fluid; And a shaft that is rotated by a rotational force of the blade unit.

The expanding portion may further include at least one discharge passage formed in the radial direction of the blade portion.

The power generator may be an induction generator that utilizes the rotational force of the shaft.

And an inverter unit converting the electric energy produced by the power generation unit into an alternating current.

And a control unit for controlling the AC power converted by the inverter unit to be supplied to at least one or more of the electricity consumers and the energy storage unit.

As described above, according to the present invention, various effects including the following can be expected. However, the present invention does not necessarily achieve the following effects.

Waste heat generated in a fuel cell or the like can be effectively used for electricity production. In addition, the produced electricity can be supplied to a refrigerator or an air conditioner installed in a building or the like requiring a small power, thereby improving the efficiency of the fuel cell.

Also, the low-temperature power generation system is suitably controlled in response to the temperature change of the waste heat, and stable operation is possible, and a surplus portion of generated electricity can be stored through the energy storage device.

1 is a schematic diagram of a low-temperature power generation system according to an embodiment of the present invention;
Fig. 2 is a schematic diagram showing the circulating flow of the working fluid for Fig. 1; Fig.
3 is a schematic cross-sectional view of the expanding portion of Fig.
Figure 4 is a schematic diagram showing the flow of working fluid within the expansion of Figure 3;

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

FIG. 1 is a system diagram of a low-temperature power generation system according to an embodiment of the present invention, and FIG. 2 is a systematic diagram showing a circulation flow of a working fluid in FIG. 1 and 2, a low temperature power generation system according to an embodiment of the present invention includes a low temperature heat source unit 10, an evaporator unit 20, an expansion unit 30, a power generation unit 40, a condenser unit 50 A liquid pump 60, an inverter unit 70, a control unit (not shown), a cooling tower 80, and the like. At this time, the working fluid has a cycle of circulating through the evaporator 20, the expander 30, the generator 40, and the condenser 50.

The low-temperature heat source unit 10 means a heat source having a temperature at least higher than the boiling point of the working fluid used in the present invention in a relative concept to a high-temperature heat source.

The low temperature heat source unit 10 may be, for example, waste heat generated in the fuel cell. Fuel cells allow independent operation of the system through its own energy production even if the power supply is shut off from the outside. On the other hand, the fuel cell generates waste heat in accordance with its operation, and it can be utilized in the form of waste heat water by disposing piping.

That is, the waste heat and hot water generated in the fuel cell may be supplied to the evaporator 20 through the pipe, and then may be introduced into the fuel cell when it is cooled by heat exchange in the evaporator 20. The low-temperature heat source unit 10 according to one embodiment is exemplified by the waste heat generated in the fuel cell, but the present invention is not limited thereto.

The evaporating unit 20 absorbs the heat energy of the low-temperature heat source unit 10 to be converted into the vapor-phase working fluid. Here, various kinds of refrigerants capable of phase change at a low temperature can be used as the working fluid. However, considering that the temperature of the waste heat generated in the fuel cell is about 60 degrees, it is preferable that the phase change occurs in the vicinity thereof.

At this time, the evaporator 20 may include an internal structure of a type that is wound to increase the surface area to be heat-exchanged. In addition, the inside of the evaporator 20 can be made of a material having a high thermal conductivity to improve the absorption efficiency of heat energy.

The liquid working fluid flowing into the evaporator (20) is in a compressed state by the liquid pump (60). At this time, the working fluid can be easily evaporated even at a low temperature depending on the kind, even though the pressure is increased according to the transfer. As a result, the liquid working fluid is phase-changed to a gas-phase working fluid, which is a high-pressure steam.

Fig. 3 is a schematic cross-sectional view of the expansion part of Fig. 1, and Fig. 4 is a schematic view showing the flow of working fluid in the expansion part of Fig. Referring to FIGS. 3 and 4, the expansion portion 30 causes the gas-phase working fluid flowing out of the evaporation portion 20 to expand and generate kinetic energy. For example, the expansion portion 30 is similar to a kind of turbine that rotates by the flow of fluid. Specifically, the expansion portion 30 includes a casing 32, an expansion portion 34, a blade portion 36, a shaft 38, a discharge passage 33, and the like.

The casing 32 is a member provided with a receiving space in which all the components of the expanding portion 30 can be accommodated. At this time, the respective components may be arranged in a line in the casing 32 along the flow direction.

The expansion portion (34) is disposed at the inlet of the casing (32), and has a shape in which the diameter of the expansion portion is increased along the flow direction so as to increase the pressure of the vapor working fluid. The expansion portion 34 may further include grooves or the like which can prevent the flow velocity from being decreased on the inner side thereof in consideration of the frictional resistance due to the flow. As a result, the flow of the gas-phase working fluid can be smoothly induced.

The blade portion (36) is formed at a longitudinal end portion of the expansion portion (34) and is made of a plurality of revolutions by the flow of the vapor-phase working fluid. The blade portion 36 is arranged in the radial direction, i.e., perpendicular to the flow direction. The blade portion 36 converts the kinetic energy of the vapor-phase working fluid into rotational force.

The shaft 38 is rotated by the rotational force of the blade portion 36. Specifically, the shaft 38 can be coupled to the center of the blade portion 36. The shaft 38 transmits rotational force in the expanding section 30 to the power generating section 40 so as to produce electric energy.

At least one discharge flow path 33 is formed in the radial direction of the blade portion 36. That is, the gas-phase working fluid flows in the high-pressure state through the inlet of the expansion portion 34, and is discharged through the discharge flow passage 33.

The power generation unit 40 converts the kinetic energy generated in the expansion unit 30 into electric energy. The power generation section 40 may be accommodated inside the casing 32 constituting the expansion section 30 and may be disposed outside the expansion section 30. The power generation section 40 may be, for example, an induction generator that utilizes the rotational force of the shaft 38. [ That is, the power generation section 40 includes a rotor formed at an end of the shaft 38 and a stator disposed at an outer circumference of the rotor, thereby generating electric energy.

The condenser 50 cools the vapor-phase working fluid and condenses it into the liquid working fluid. That is, the condenser 50 can convert the low-pressure gaseous working fluid discharged from the inflator to the low-pressure liquid working fluid. For this purpose, the condensing section 50 can liquefy the vapor-phase working fluid by using outside air or cooling water.

In addition, the low temperature power generation system according to an embodiment may further include a cooling tower 80. The cooling tower 80 cools the heat exchanged cooling water in the condenser. That is, the cooling tower 80 cools the cooling water recovered through the cooling water recovery line and sends it to the condenser through the cooling water supply line to condense the gas-phase working fluid. The cooling water circulates repeatedly between the condensing section 50 and the cooling tower 80.

The liquid pump 60 compresses the liquid working fluid flowing out of the condensing section 50 and transfers the compressed liquid working fluid to the evaporating section 20. That is, the liquid pump 60 pressurizes the low-pressure liquid working fluid to a predetermined pressure and sends it to the evaporator 20. On the other hand, the feed amount of the liquid pump 60 can be controlled in accordance with the temperature of the low temperature heat source unit 10. Specifically, the liquid pump 60 can control the flow rate of the liquid working fluid discharged from the liquid pump 60 by adjusting the number of rotations of the motor disposed in the liquid pump 60 according to the temperature measured by the low temperature heat source unit 10. As a result, the low-temperature power generation system can be stably operated in response to the temperature change of the heat source portion (for example, waste heat generated in the fuel cell).

The low-temperature power generation system may further include an inverter unit 70 for converting the electric energy produced by the power generation unit 40 into an AC 60 Hz form. The low-temperature power generation system may further include a control unit (not shown) for controlling the alternating-current electricity converted by the inverter unit 70 to be supplied to at least one or more electricity consumers and energy storage units. That is, the produced electricity can be supplied to a refrigerator or an air conditioner installed in a building or the like requiring particularly small power, thereby improving the efficiency of the fuel cell. In addition, surplus alternating electricity can be sold to the outside.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.

10: low-temperature heat source unit 20:
30: Expansion section 40: Power generation section
50: condenser part 60: liquid pump
70: inverter section 80: cooling tower
32: casing 34:
36: blade portion 38: shaft
33: Exhaust flow path

Claims (7)

A low-temperature heat source unit capable of supplying energy by itself;
An evaporating portion in which an incoming liquid working fluid absorbs thermal energy of the low temperature heat source portion and is converted into a vapor operating fluid;
An expansion unit for generating kinetic energy while expanding the vapor-phase working fluid flowing out from the evaporation unit;
A generator for converting the kinetic energy into electrical energy;
A condenser for cooling the gas-phase working fluid to condense it into a liquid working fluid; And
And a liquid pump for compressing the liquid working fluid flowing out from the condensing part and controlling the flow rate of the liquid working fluid discharged according to the temperature of the low temperature heat source part to transfer the liquid working fluid to the evaporation part,
The expansion unit
Casing;
An expansion unit disposed at an inlet of the casing and having a diameter enlarged along the flow direction so as to reduce the pressure of the gaseous working fluid;
A blade portion formed at a longitudinal end portion of the expansion portion and formed of a plurality of blades rotated by the flow of the vapor-phase working fluid; And
And a shaft that is rotated by a rotational force of the blade portion.
The method according to claim 1,
Wherein the low-temperature heat source unit is waste heat generated in the fuel cell.
delete The method according to claim 1,
The expansion unit
And at least one discharge passage formed in a radial direction at the end of the blade portion from which the vapor-phase working fluid is discharged.
The method according to claim 1,
Wherein the power generation section is an induction generator that utilizes the rotational force of the shaft.
The method according to claim 1,
And an inverter unit converting the electric energy produced by the power generation unit into an AC type.
The method according to claim 6,
And a control unit for controlling the AC power converted by the inverter unit to be supplied to at least one or more of the electricity consumers and the energy storage unit.

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