Hybrid power generation system and power generation method using the same

Abstract

The present embodiments may provide a hybrid power generation system comprising: a first power generation unit that produces an electric current from the heat of a gas emitted from a heat source; and a second power generation unit that produces an electric current from the heat of a gas delivered through a second pipe.

Description

Technology Field

[0001] The present embodiment relates to a hybrid power generation system and a method of generating electricity using the same. More specifically, it relates to a hybrid power generation system that produces electricity from medium-to-low temperature waste gas through the thermoelectric effect and an organic Rankine cycle, and a method of generating electricity using the same. Background Technology

[0002] Power generation systems that provide low-cost energy while minimizing environmental impact and can be immediately integrated into existing power grids or rapidly installed as standalone units help meet critical power demands in many sectors. In particular, systems that generate electricity by utilizing waste heat from the industrial sector are known to contribute to the reduction of direct power production costs and greenhouse gas emissions.

[0003] Meanwhile, a basic Organic Rankine Cycle (ORC) may include a turbo generator, a preheater, a condenser, and a liquid pump, and can generate electricity from low-temperature waste gas using an organic Rankine refrigerant. The organic Rankine refrigerant can accept waste heat at a temperature higher than the boiling point of the refrigerant and can release the heat accepted into surrounding water or air at a temperature lower than the boiling point of the refrigerant.

[0004] However, organic Rankine cycles have a limitation in that it is difficult to secure uniform power generation performance for waste heat of various temperature ranges because the temperature of waste heat that can be accommodated is limited by the boiling point of the refrigerant.

[0005] Therefore, it can be said that there is an urgent need to secure technology for power generation systems with relatively low dependence on the temperature of the heat source. The problem to be solved

[0006] In this embodiment, we aim to provide a hybrid power generation system having improved power generation performance for medium and low temperatures. means of solving the problem

[0007] A hybrid power generation system according to one embodiment comprises: a first pipe connected to a heat source and flowing gas emitted from the heat source; a first power generation unit connected to the first pipe and producing current from the heat of the gas; a second pipe connected to the first power generation unit and flowing gas; a second power generation unit connected to the second pipe and producing current from the heat of the gas; and a third pipe connected to the second power generation unit and flowing gas emitted from the second power generation unit, wherein the first power generation unit includes a first thermoelectric material, and the second power generation unit can generate power by an organic Rankine cycle.

[0008] A power generation method according to another embodiment can produce electricity from a power generation system according to one embodiment. Effects of the invention

[0009] According to one embodiment, the hybrid power generation system according to one embodiment includes a first power generation unit and a second power generation unit, and since the first power generation unit and the second power generation unit produce electricity according to different principles, the hybrid power generation system according to one embodiment can efficiently produce electricity from a heat source having a wide temperature range of medium to low temperatures.

[0010] In addition, low-to-medium temperature industrial waste heat, which was previously unrecovered due to difficulties in economic feasibility, maintenance, and management, is recovered using a hybrid power generation system, resulting in reduced energy consumption and consequent greenhouse gas reduction. Brief explanation of the drawing

[0011] FIG. 1 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a first branch pipe. FIG. 3 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a second-2 generator. FIG. 4 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a third power generation unit. FIG. 5 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a first branch pipe and a third power generation unit. FIG. 6 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a first branch pipe, a second-2 generator, and a third power generation unit. FIG. 7 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a submodule. Specific details for implementing the invention

[0012] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0013] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0014] When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between.

[0015] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0017] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0019] A hybrid power generation system according to one embodiment may include: a first pipe connected to a heat source and flowing gas emitted from the heat source; a first power generation unit connected to the first pipe and producing an electric current from the heat of the gas; a second pipe connected to the first power generation unit and flowing gas; a second power generation unit connected to the second pipe and producing an electric current from the heat of the gas; and a third pipe connected to the second power generation unit and flowing gas emitted from the second power generation unit.

[0020] The first power generation unit may include a first thermoelectric material, and the first thermoelectric material may produce electricity from gas emitted from the heat source by the thermoelectric effect.

[0021] In addition, the second power generation unit may include an organic Rankine refrigerant and may generate power by an organic Rankine cycle.

[0022] The second power generation unit may include an evaporator connected to the second pipe and the third pipe; an expander connected to the evaporator; a second-1 generator connected to the expander; and a condenser connected to the expander and the evaporator, and the organic Rankine refrigerant may be circulated repeatedly in the order of the evaporator, the expander, the condenser, and the evaporator.

[0023] Additionally, the organic Rankine refrigerant may pass through an expander and expand from high-pressure vapor to low-pressure vapor, and may produce mechanical energy. In some exemplary embodiments, the expander may be a positive expansioner or a dynamic expansioner. Examples of positive expansioners may include pistons, spirals, etc., and examples of dynamic expansioners may include turbines.

[0024] The mechanical energy generated in the expander can be converted into electrical energy through the above-mentioned 2-1 generator.

[0025] Meanwhile, the organic Rankine refrigerant converted into low-pressure vapor by the expander can be cooled and condensed in the condenser. The condensed organic Rankine refrigerant is then fed back into the evaporator to complete the organic Rankine cycle. In some exemplary embodiments, the second generator may further include a pump to recirculate the organic Rankine refrigerant back into the evaporator.

[0026] FIG. 1 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention. Referring to FIG. 1, the flow of electricity production from a hybrid power generation system according to one embodiment can be easily understood.

[0027] According to the hybrid power generation system of the exemplary embodiment shown in FIG. 1, gas released from a heat source flows into the first power generation unit (100) through the first pipe (10).

[0028] The gas introduced into the first power generation unit (100) interacts with the first thermoelectric material contained in the first power generation unit (100), and as a result, at least a portion of the thermal energy of the gas is converted into electrical energy.

[0029] Afterward, the gas released from the first power generation unit (100) flows into the evaporator (210) of the second power generation unit (200) through the second pipe (20). Heat exchange occurs between the organic Rankine refrigerant and the gas within the evaporator (200), and the organic Rankine refrigerant is heated. The heated organic Rankine refrigerant flows into the expansion unit (220) and is transformed into low-pressure steam by the expansion unit (220). The second-1 generator (230) can produce electricity by utilizing the mechanical energy generated from the pressure change of the organic Rankine refrigerant.

[0030] Meanwhile, the organic Rankine refrigerant, which has been transformed into low-pressure steam, flows into the condenser (240) to be cooled and condensed. The condensed organic Rankine refrigerant flows back into the evaporator (210) for recycling. A pump (not shown) may be placed between the evaporator (210) and the condenser (240) to increase the flow rate of the organic Rankine refrigerant.

[0031] Meanwhile, in some exemplary embodiments, a cooling device (50) may be additionally included to facilitate cooling of the first thermoelectric material and the organic Rankine refrigerant. The cooling device (50) may be connected to the condenser (240) and / or the first power generation unit (100) through separate piping, and the gas released from the heat source, the first thermoelectric material, and the organic Rankine refrigerant may not be introduced into the interior of the cooling device (50).

[0032] In this embodiment, the heat source can be, for example, industrial waste heat of about 200 to 400°C that is discarded in industrial processes, so it is very advantageous to have an energy saving effect.

[0034] A hybrid power generation system according to one embodiment further comprises: a first branch pipe having one end connected to the first pipe; a first flow control valve for controlling the opening and closing of the first pipe; and a second flow control valve for controlling the opening and closing of the first branch pipe, wherein the other end of the first branch pipe is connected to the second pipe to allow gas to flow to the second power generation unit. As a result, gas released from a heat source may flow into the second power generation unit without passing through the first power generation unit, or only a portion of the gas may pass through the first power generation unit while the remainder flows directly into the second power generation unit.

[0035] Meanwhile, the first flow control valve may be placed at the connection point between the first pipe and the first branch pipe. In this case, the function of the second flow control valve can be performed by the first flow control valve.

[0036] In addition, by making the power generation conditions of the first and second power generation sections different, the gas temperature, flow rate, and pressure conditions capable of generating power with maximum efficiency can be diversified.

[0037] In this embodiment, the second power generation unit can generate power under lower temperature conditions than the first power generation unit. For example, the first power generation unit can produce electrical energy more efficiently at a temperature of 300°C or higher, and the second power generation unit can produce electrical energy more efficiently at a temperature of less than 300°C.

[0039] FIG. 2 is a schematic diagram of a hybrid power generation system according to an embodiment of the present invention, further including a first branch pipe. According to FIG. 2, in the hybrid power generation system of an exemplary embodiment, gas can be directly introduced into the evaporator (210) of the second power generation unit (200) through the first branch pipe (12) without passing through the first power generation unit (100).

[0040] Meanwhile, whether the first pipe (10) is open or closed can be determined by the first flow control valve (11). The first pipe (10) can be completely closed or partially closed by the first flow control valve (11). Additionally, whether the first branch pipe (15) is open or closed can be determined by the second flow control valve (16). The first branch pipe (15) can be completely closed or partially closed by the second flow control valve (16).

[0041] In addition, in a hybrid power generation system according to one embodiment, the first flow control valve (11) and the second flow control valve (15) can each control the opening and closing of the first pipe (10) and the first branch pipe (15) based on the temperature of the gas released from the heat source.

[0042] In addition, in a hybrid power generation system according to one embodiment, the first flow control valve (11) and the second flow control valve (15) can each control the opening and closing of the first pipe (10) and the first branch pipe (15) based on the pressure of the gas released from the heat source.

[0044] A hybrid power generation system according to one embodiment may further include a second generator located between the evaporator and the expander and directly connected to the evaporator and the expander. As a result, additional electrical energy can be produced before the organic Rankine refrigerant is expanded and cooled.

[0046] FIG. 3 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a second-2 generator. In the hybrid power generation system according to one embodiment, the second-2 generator (250) may include a second thermoelectric material.

[0047] Referring to FIG. 3, heat exchange occurs between the gas introduced into the evaporator (210) of the second power generation unit (200) through the second pipe (20) and the organic Rankine refrigerant. The heated organic Rankine refrigerant is preferentially introduced into the second-2 generator (250), and heat exchange occurs between the second thermoelectric material contained in the second-2 generator and the organic Rankine refrigerant, and electrical energy is generated by the second thermoelectric material. Additionally, the cooled organic Rankine refrigerant is introduced into the expansion unit (220) and passes through the organic Rankine cycle.

[0048] Therefore, even if the organic Rankine refrigerant is heated to a level unsuitable for producing electrical energy through the organic Rankine cycle, additional electrical energy can be produced by the generator. As a result, the electrical energy production efficiency of the organic Rankine cycle can be further improved.

[0050] A hybrid power generation system according to one embodiment further comprises: a third power generation unit connected to the third pipe to produce an electric current from the heat of the gas; and a fourth pipe connected to the third power generation unit to allow the gas discharged from the third power generation unit to flow, wherein the third power generation unit may include a third thermoelectric material. The fourth pipe may discharge the gas to the outside of the hybrid power generation system.

[0052] FIG. 4 is a schematic diagram of a hybrid power generation system according to an embodiment of the present invention, further including a third power generation unit. Referring to FIG. 4, it can be seen that gas passing through the first power generation unit (100) and the second power generation unit (200) flows into the third power generation unit (300) through the third pipe (30). The gas, whose thermal energy has been reduced by passing through the first power generation unit (100) and the second power generation unit (200), can further interact with the third thermoelectric material of the third power generation unit (300). As a result, the third thermoelectric material can additionally produce electrical energy.

[0053] The first thermoelectric material and the second and third thermoelectric materials described below may all be materials capable of producing electrical energy from thermal energy through the Seebeck effect. Additionally, the first to third thermoelectric materials may have the same or different Seebeck coefficients. The first to third thermoelectric materials may each include an N-type semiconductor and a P-type semiconductor, and the Seebeck coefficient of each thermoelectric material may be controlled by varying the N-type semiconductor and the P-type semiconductor.

[0054] In a hybrid power generation system according to one embodiment, the first thermoelectric material and the third thermoelectric material can generate power at different temperatures. Additionally, the first thermoelectric material and the third thermoelectric material can be prepared using different compounds so that a thermoelectric effect can occur at different temperatures.

[0055] In addition, in a hybrid power generation system according to one embodiment, the power generation temperature of the first thermoelectric material may be higher than the power generation temperature of the third thermoelectric material.

[0056] As a result, the first thermoelectric material can efficiently produce electrical energy by exchanging heat with a relatively high-temperature gas, and the third thermoelectric material can efficiently produce electrical energy by exchanging heat with a relatively low-temperature gas.

[0058] FIG. 5 is a schematic diagram of a hybrid power generation system according to one embodiment of the present invention, further including a first branch pipe and a third power generation unit. Through the first branch pipe (15) and flow control valves (11, 16), gas released from a heat source may pass through the first power generation unit (100) or may flow directly into the second power generation unit (200) without passing through the first power generation unit (100). For example, medium-temperature and high-pressure gas may pass through the first power generation unit (100), and low-temperature and high-pressure gas may flow directly into the second power generation unit (200).

[0059] The gas passing through the second power generation unit (200) is cooled to a lower temperature than before it enters the second power generation unit (200) and flows into the third power generation unit (300) through the third pipe (30). The third power generation unit (300) produces additional electricity through a thermoelectric effect from the gas at a lower temperature.

[0060] Accordingly, the gas released from the heat source loses thermal energy in stages according to temperature and pressure conditions, and the first power generation unit (100), the second power generation unit (200), and the third power generation unit (300) convert the thermal energy into electrical energy in stages. As a result, efficient production of electrical energy is possible from gases under various conditions released from the heat source.

[0062] FIG. 6 is a schematic diagram of a hybrid power generation system according to an embodiment of the present invention, further comprising a first branch pipe, a second-2 generator, and a third power generation unit. By further including the second-2 generator (250), the efficiency of the organic Rankine cycle can be further improved as described above. As a result, the efficiency of electric energy production can be guaranteed even if the conditions of the gas released from the heat source change significantly.

[0064] In a hybrid power generation system according to one embodiment, the second power generation unit comprises two or more submodules, each submodule comprising an expander and a generator, and the submodules may be connected in parallel to the evaporator and the condenser, respectively. Additionally, if the second power generation unit further comprises a second-2 generator, the submodules may be connected in parallel to the second-2 generator and the condenser, respectively.

[0065] FIG. 7 is a schematic diagram of a hybrid power generation system including additional submodules. According to FIG. 7, the submodules include a first submodule (261) and a second submodule (262), and the first submodule (261) and the second submodule (262) each include an expander (not shown) and a generator (not shown). Additionally, the number of submodules is not particularly limited.

[0066] In a hybrid power generation system according to some exemplary embodiments, each submodule (261, 262) may have different expansion and power generation conditions. As a result, the cooling of the organic Rankine refrigerant may occur sequentially, and the power generation efficiency of the organic Rankine cycle may be further improved independently of the temperature and flow rate of the initially introduced gas.

[0068] In addition, in a hybrid power generation system according to some exemplary embodiments, the temperature of the gas released from the heat source may be 200°C to 400°C. For example, gas at about 200°C may be released to the outside via the second power generation unit and the third power generation unit, and gas at about 400°C may be released to the outside via the first power generation unit, the second power generation unit, and the third power generation unit.

[0070] In addition, another embodiment of the present invention provides a method for generating electricity from a hybrid power generation system according to exemplary embodiments. Through the exemplary power generation method, electrical energy can be efficiently produced from a gas with varying temperature, flow rate, and pressure conditions.

[0071] An exemplary development method may satisfy the following conditions 1) to 4).

[0072] 1) When the temperature of the gas released from the heat source exceeds the first temperature, electricity can be produced in the first power generation unit. If the gas exceeding the first temperature is directly fed into the second power generation unit, the efficiency of producing electrical energy through the organic Rankine cycle may decrease. Therefore, by allowing the gas to pass through the first power generation unit, some of the thermal energy of the gas is converted into electrical energy, and thereby the power generation efficiency of the second power generation unit can also be improved.

[0073] 2) If the temperature of the gas is between the second temperature and the first temperature, electricity can be produced in the second power generation unit. The gas may be released directly from a heat source or released from the first power generation unit.

[0074] When the gas temperature is between the second and first temperatures, the production of electrical energy due to the thermoelectric effect may be negligible even if it passes through the first power generation unit, or a production efficiency above a certain level may not be secured even if it remains in the first power generation unit. Additionally, the inflow of gas into the second power generation unit may be unnecessarily delayed. As a result, the power generation efficiency of both the first and / or second power generation units may decrease.

[0075] 3) If the temperature of the gas is below the second temperature, electricity can be produced in the third power generation unit. If the gas below the second temperature remains in the second power generation unit, the production of additional electrical energy may be limited by the organic Rankine cycle. Therefore, by allowing the gas below the second temperature to flow into the third power generation unit, the loss of unnecessary thermal energy can be limited and additional electrical energy can be produced.

[0076] 4) The first temperature may be 350°C or higher, and preferably between 350°C and 375°C. Additionally, the second temperature may be 250°C or lower, and preferably between 225°C and 250°C. By satisfying the above-described numerical ranges, the production of electrical energy through the first to third power generation units can be carried out in a stepwise and efficient manner.

[0078] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 A first pipe connected to a heat source and flowing gas discharged from the heat source; a first power generation unit connected to the first pipe and producing an electric current from the heat of the gas; a second pipe connected to the first power generation unit and flowing gas; a second power generation unit connected to the second pipe and producing an electric current from the heat of the gas; a third pipe connected to the second power generation unit and flowing gas discharged from the second power generation unit; and a cooling device connected to the first power generation unit, wherein the first power generation unit includes a first thermoelectric material, the second power generation unit generates power by an organic Rankine cycle, and the second power generation unit is configured to generate power under a lower temperature condition than the first power generation unit, and the second power generation unit comprises: an evaporator connected to the second pipe and the third pipe; an expander connected to the evaporator; a second-1 generator connected to the expander; and a condenser connected to the expander and the evaporator. A hybrid power generation system comprising a second-2 generator located between the evaporator and the expansion unit and directly connected to the evaporator and the expansion unit, wherein an organic Rankine refrigerant delivered from the evaporator flows in preferentially over the second-1 generator, the second-2 generator comprises a second thermoelectric material, and the cooling device cools the first thermoelectric material using the condenser of the second power generation unit. Claim 2 A hybrid power generation system according to claim 1, further comprising: a first branch pipe having one end connected to the first pipe; a first flow control valve for controlling the opening and closing of the first pipe; and a second flow control valve for controlling the opening and closing of the first branch pipe, wherein the other end of the first branch pipe is connected to the second pipe and flows gas to the second power generation unit. Claim 3 A hybrid power generation system according to paragraph 2, wherein the flow control valve controls the opening and closing of the first pipe and the opening and closing of the first branch pipe based on the temperature of the gas emitted from the heat source. Claim 4 A hybrid power generation system according to paragraph 2, wherein the first flow control valve controls the opening and closing of the first pipe and the opening and closing of the first branch pipe based on the pressure of the gas released from the heat source. Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 A hybrid power generation system according to claim 1, wherein the second power generation unit comprises two or more submodules, each submodule comprising an expander and a generator, and the submodules are connected in parallel to the evaporator and the condenser, respectively. Claim 10 A hybrid power generation system according to claim 1, further comprising: a third power generation unit connected to the third pipe to produce an electric current from the heat of the gas; and a fourth pipe connected to the third power generation unit to flow the gas discharged from the third power generation unit, wherein the third power generation unit comprises a third thermoelectric material. Claim 11 In item 10, the first thermoelectric material and the third thermoelectric material generate power at different temperatures, forming a hybrid power generation system. Claim 12 A hybrid power generation system according to claim 10, wherein the power generation temperature of the first thermoelectric material is higher than the power generation temperature of the third thermoelectric material. Claim 13 A hybrid power generation system according to claim 1, wherein the temperature of the gas emitted from the heat source is 200°C to 400°C. Claim 14 A method of generating electricity from a hybrid power generation system according to Paragraph 10. Claim 15 In claim 14, a power generation method satisfying the following conditions 1) to 4): 1) when the temperature of the gas released from the heat source exceeds the first temperature, electricity is produced in the first power generation unit; 2) when the temperature of the gas is between the second temperature and the first temperature, electricity is produced in the second power generation unit; 3) when the temperature of the gas is less than the second temperature, electricity is produced in the third power generation unit; 4) the first temperature is 350°C to 375°C, and the second temperature is 225°C to 250°C.

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