CN108869213B - Photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device and method - Google Patents

Abstract

The invention provides a photon-enhanced thermion emission and carbon dioxide cycle combined power generation device, which includes a solar concentrator and a receiver, the receiver is connected with a photon-enhanced thermion emission module group, and the photon-enhanced thermion emission module group is connected for cooling The circuit is connected with the supercritical carbon dioxide cycle through the intermediate heat exchanger, and the supercritical carbon dioxide cycle includes: a compressor, a low-temperature regenerator, a high-temperature regenerator, a turbine, a generator, and a precooler. The invention also provides a combined power generation method of photon-enhanced thermionic emission and carbon dioxide cycle. The solar energy first passes through the photon-enhanced thermionic emission module to convert part of the energy into electrical energy, and the remaining energy is transferred to the supercritical carbon dioxide cycle in the form of anode waste heat. , forming a combined circulation system. The invention reduces the loss of heat released to the environment, and the overall power generation efficiency of the combined cycle system is high, the structure is compact, and the application range is wide.

Description

Photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device and method

technical field

The invention relates to a photon-enhanced thermal ion emission and supercritical carbon dioxide cycle combined power generation device, which belongs to the technical field of solar power generation.

Background technique

Solar energy is inexhaustible and inexhaustible green energy, and solar thermal power generation is one of the main ways to utilize solar energy. In recent years, this technology has developed very rapidly, and more mature technologies include trough, tower, Fresnel, dish and other solar concentrating thermal power generation technologies. Solar heat transfers heat to power cycle systems through intermediate media and heat exchangers, such as: steam turbine generator sets, Stirling engines, and converts heat energy into electrical energy.

Since the current operating temperature level of the power cycle system is not high and the energy conversion efficiency is relatively low, the competitive advantage of solar thermal power generation over photovoltaic power generation is not obvious. On the one hand, it is necessary to develop a more efficient power cycle system. The current mainstream research and development direction is the supercritical carbon dioxide cycle, and at the same time strive to improve the temperature parameters of the cycle; on the other hand, introduce new energy conversion methods and constantly explore new breakthrough points, especially It is a new type of thermoelectric converter, such as: thermionic emission device, the cathode operates at high temperature, and the higher temperature waste heat generated by the anode can continue to provide heat for the bottom cycle.

In recent years, solar power generation technology based on photon-enhanced thermionic emission effect is being widely developed at home and abroad, combined with anode waste heat power generation to form a solar combined power generation device, which can greatly improve the efficiency of solar power generation. However, how to match the solar power generation technology based on the photon-enhanced thermionic emission effect with the advanced power cycle to form a combined power generation system is an urgent problem to be solved.

Contents of the invention

The technical problem to be solved by the present invention is how to match the solar power generation technology based on the photon-enhanced thermionic emission effect with the advanced power cycle to form a combined power generation system, so as to improve the overall power generation efficiency of the combined power generation system.

In order to solve the above technical problems, the technical solution of the present invention is to provide a photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device, which is characterized in that: it includes a solar concentrator and a receiver, and the concentrator and the receiver are arranged opposite , the receiver is connected with the photon-enhanced thermionic emission module group;

The photon-enhanced thermion emission module group is divided into two types: the first photon-enhanced thermion emission module group and the second photon-enhanced thermion emission module group, and the anode temperature corresponding to the first photon-enhanced thermion emission module group is lower than that of the second photon-enhanced thermion emission module group The anode temperature corresponding to the photon-enhanced thermionic emission module group;

The anodes of the first photon-enhanced thermion emission module group and the second photon-enhanced thermion emission module group are respectively connected to the first cooler and the second cooler; the outlet of the first cooler is connected to the heat transfer medium side inlet of the first intermediate heat exchanger , the outlet of the heat transfer medium side of the first intermediate heat exchanger is connected to the inlet of the first medium pump, and the outlet of the first medium pump is connected to the inlet of the first cooler to form a first cooling circuit; the outlet of the second cooler is connected to the second intermediate heat exchanger The inlet on the heat medium side, the outlet on the heat transfer medium side of the second intermediate heat exchanger is connected to the inlet of the second medium pump, and the outlet of the second medium pump is connected to the inlet of the second cooler to form a second cooling circuit;

The carbon dioxide side of the first intermediate heat exchanger and the carbon dioxide side of the second intermediate heat exchanger are connected to the supercritical carbon dioxide circulation system, and release the heat of the heat transfer medium in the first and second cooling circuits to the carbon dioxide working medium of the supercritical carbon dioxide circulation system.

Preferably, the supercritical carbon dioxide circulation system includes a compressor, and the outlet of the compressor is divided into two paths: one path is connected to the low-temperature side inlet of the low-temperature regenerator, and the other path is connected to the carbon dioxide side inlet of the first intermediate heat exchanger; the low-temperature regenerator The outlet on the low temperature side and the outlet on the carbon dioxide side of the first intermediate heat exchanger are combined and then connected to the inlet on the low temperature side of the high temperature regenerator, the outlet on the low temperature side of the high temperature regenerator is connected to the inlet on the carbon dioxide side of the second intermediate heat exchanger, and the second intermediate heat exchanger The outlet on the carbon dioxide side is connected to the inlet of the turbine, the outlet of the turbine is connected to the inlet on the high-temperature side of the high-temperature regenerator, the outlet on the high-temperature side of the high-temperature regenerator is connected to the inlet on the high-temperature side of the low-temperature regenerator, and the outlet on the high-temperature side of the low-temperature regenerator is connected to the inlet of the pre-cooler. The outlet of the cooler is connected to the inlet of the compressor; the compressor, turbine and generator are connected coaxially.

Preferably, the concentrator is a dish concentrator, a tower concentrator or a Fresnel lens concentrator.

Preferably, the receiver is a direct-irradiation receiver with a cavity structure.

Preferably, the anode temperature of the first photon-enhanced thermion emission module group is 150-300°C; the anode temperature of the second photon-enhanced thermion emission module group is 500-700°C.

Preferably, the heat transfer medium of the first cooling circuit is heat transfer oil; the heat transfer medium of the second cooling circuit is a low melting point metal liquid (such as alkali metal liquid) or molten salt.

Preferably, the first cooler and the second cooler are provided with extended heat dissipation surfaces, such as fins (bars).

Preferably, the first intermediate heat exchanger and the second intermediate heat exchanger are partition wall heat exchangers, and the heat exchange walls on the carbon dioxide side of the first intermediate heat exchanger and the second intermediate heat exchanger are provided with extended heat exchangers. The hot surface, for example, adopts an externally finned heat exchange tube, and the outside of the tube is carbon dioxide.

Preferably, the low-temperature regenerator and the high-temperature regenerator are compact heat exchangers.

The present invention also provides a photon-enhanced thermionic emission and carbon dioxide cycle combined power generation method, which is characterized in that: using the above-mentioned photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device, the steps are: the sunlight is focused by the concentrator to receive The receiver heats the cathodes of the first photon-enhanced thermionic emission module group and the second photon-enhanced thermionic emission module group, the electrons emitted by the cathode reach the anode through the gap between the two poles and output electric energy from the two poles at the same time, the first cooler and the second cooling The device cools the anode and transfers the waste heat to the heat transfer medium;

The first medium pump and the second medium pump continuously circulate the heat transfer medium from the first cooler and the second cooler to the first intermediate heat exchanger and the second intermediate heat exchanger, and the heat transfer medium releases heat to the super Carbon dioxide working medium of critical carbon dioxide cycle system;

In the supercritical carbon dioxide circulation system, the compressor compresses the carbon dioxide working medium, and the carbon dioxide working medium at the outlet of the compressor is divided into two paths: one path enters the low-temperature regenerator, and the other path enters the first intermediate heat exchanger; The mass enters the high-temperature regenerator together, then enters the second intermediate heat exchanger for further heating, and then enters the turbine to expand and do work, driving the generator to generate electric energy; the exhaust gas of the turbine enters the high-temperature regenerator and the low-temperature regenerator in turn, and the Part of the heat is transferred to the carbon dioxide working medium, then cooled by the pre-cooler, and finally returned to the compressor.

Compared with the prior art, the photon-enhanced thermionic emission and supercritical carbon dioxide cycle combined power generation device provided by the present invention has the following beneficial effects:

1. The anode waste heat of the photon-enhanced thermionic emission module is transferred to the supercritical carbon dioxide cycle, which reduces the loss of heat released to the environment, and the overall power generation efficiency of the combined cycle system is high.

2. The photon-enhanced thermionic emission module is an area-type power generation device with high power density and high power generation efficiency. It is an efficient and compact solar power generation device, and different anode temperatures can be designed according to the characteristics of the bottom cycle.

3. The supercritical carbon dioxide cycle has a compact structure and maintains high efficiency in a large power generation span (hundreds of kW to hundreds of MW). It can be combined with a photon-enhanced thermionic emission module to form a small and compact power generation device or a medium-sized , Large-scale power generation devices to meet different application requirements.

Description of drawings

1 is a schematic diagram of a photon-enhanced thermionic emission combined with carbon dioxide cycle power generation device provided in this embodiment;

Explanation of reference signs:

1-Concentrator, 2-Receiver, 3-First photon-enhanced thermionic emission module group, 4-First cooler, 5-First intermediate heat exchanger, 6-First medium pump, 7-Second Photon-enhanced thermionic emission module group, 8-second cooler, 9-second intermediate heat exchanger, 10-second medium pump, 11-compressor, 12-low temperature regenerator, 13-high temperature regenerator, 14-turbine, 15-generator, 16-precooler.

Detailed ways

Below in conjunction with specific embodiment, further illustrate the present invention.

Fig. 1 is the schematic diagram of the photon-enhanced thermion emission and carbon dioxide cycle combined power generation device provided in this embodiment, and the described photon-enhanced thermion emission and carbon dioxide cycle combined power generation device includes a solar concentrator 1, a receiver 2, and a concentrator The device 1 is arranged opposite to the receiver 2, and the receiver 2 is connected with a photon-enhanced thermion emission module group comprising a plurality of modules. In this embodiment, the photon-enhanced thermion emission module group is divided into two types: the first photon-enhanced thermion emission module group 3 and the second photon-enhanced thermion emission module group 7, and the corresponding anodes are low temperature and high temperature (here Low temperature and high temperature are relative concepts. In this embodiment, the anode temperature corresponding to the first photon-enhanced thermionic emission module group 3 is lower than the anode temperature corresponding to the second photon-enhanced thermionic emission module group 7).

The low-temperature and high-temperature anodes are respectively connected to the first cooler 4 and the second cooler 8 . The outlet of the first cooler 4 is connected to the inlet of the heat transfer medium side of the first intermediate heat exchanger 5, the outlet of the heat transfer medium side of the first intermediate heat exchanger 5 is connected to the inlet of the first medium pump 6, and the outlet of the first medium pump 6 is connected to the first cooler The inlet of device 4 constitutes the first cooling circuit. The outlet of the second cooler 8 is connected to the inlet of the heat transfer medium side of the second intermediate heat exchanger 9, the outlet of the heat transfer medium side of the second intermediate heat exchanger 9 is connected to the inlet of the second medium pump 10, and the outlet of the second medium pump 10 is connected to the second cooler The inlet of device 8 constitutes the second cooling circuit.

The first intermediate heat exchanger 5 and the second intermediate heat exchanger 9 are connected with a supercritical carbon dioxide circulation system. The supercritical carbon dioxide circulation system includes: a compressor 11, the outlet of the compressor 11 is divided into two paths, one path is connected to the low-temperature side inlet of the low-temperature regenerator 12, and the other path is connected to the carbon dioxide side inlet of the first intermediate heat exchanger 5; the low-temperature regenerator 12 The outlet on the low temperature side and the outlet on the carbon dioxide side of the first intermediate heat exchanger 5 are combined and then connected to the high temperature regenerator 13 The inlet on the low temperature side, the outlet on the low temperature side of the high temperature regenerator 13 is connected to the inlet on the carbon dioxide side of the second intermediate heat exchanger 9, the second Second intermediate heat exchanger 9 carbon dioxide side outlet is connected to turbine 14 inlet, turbine 14 outlet is connected to high temperature regenerator 13 high temperature side inlet, high temperature regenerator 13 high temperature side outlet is connected to low temperature regenerator 12 high temperature side inlet, low temperature regenerator The outlet of the high temperature side of the device 12 is connected to the inlet of the precooler 16, and the outlet of the precooler 16 is connected to the inlet of the compressor 11; the compressor 11, the turbine 14, and the generator 15 are coaxially connected.

The integrated alkali metal thermoelectric converter provided in this embodiment is connected to each device of the carbon dioxide cycle power generation device through pipelines, and valves, instruments and other equipment can also be arranged on the pipelines according to system control requirements. The system can also include auxiliary facilities, electrical systems, control systems, etc.

The specific implementation steps of the photon-enhanced thermionic emission combined with supercritical carbon dioxide cycle power generation device provided in this embodiment are as follows:

The sunlight is focused by the concentrator 1 to the receiver 2, and the receiver 2 heats the cathodes of the first photon-enhanced thermionic emission module group 3 and the second photon-enhanced thermionic emission module group 7, and the electrons emitted by the cathode reach the anode through the gap between the two poles At the same time, electric energy is output from the two poles, the first cooler 4 and the second cooler 8 cool the anode and transfer the waste heat to the heat transfer medium. The heat transfer medium of the first cooler 4 is heat conduction oil, and its temperature is about 200°C. The heat transfer medium of the second cooler 8 is sodium metal liquid, and its temperature is about 600°C. The first medium pump 6 and the second medium pump 10 continuously circulate the heat transfer medium from the first cooler 4 and the second cooler 8 to the first intermediate heat exchanger 5 and the second intermediate heat exchanger 9, heat transfer The medium releases heat to the working fluid of the supercritical carbon dioxide circulation system.

The compressor 11 compresses the carbon dioxide working medium to 25MPa, and the carbon dioxide working medium at the outlet of the compressor 11 is divided into two paths, one path enters the low-temperature regenerator 12, and the other path enters the first intermediate heat exchanger 5, and the two paths of carbon dioxide working medium come out The temperature reaches about 180°C, and then enters the high-temperature regenerator 13 together, and then enters the second intermediate heat exchanger 9 to be further heated to about 580°C, and then enters the turbine 14 to expand and do work, driving the generator 15 to generate electricity. The exhaust gas from the turbine 14 enters the high-temperature regenerator 13 and the low-temperature regenerator 12 , transfers part of the heat to the carbon dioxide working medium, and then cools to near normal temperature through the pre-cooler 16 , and finally returns to the compressor 11 .

It can be estimated from the above parameters that the peak solar power generation efficiency of the photon-enhanced thermionic emission combined with supercritical carbon dioxide cycle power generation device can reach more than 45%. The above system can also be provided with heat storage facilities, which can continuously provide heat input for the supercritical carbon dioxide cycle when there is no sunlight or the sunlight is weak.

It will be understood that, although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any form and in essence. Several improvements and supplements can be made, and these improvements and supplements should also be regarded as the protection scope of the present invention. Those who are familiar with this profession, without departing from the spirit and scope of the present invention, when they can use the technical content disclosed above to make some changes, modifications and equivalent changes of evolution, are all included in the present invention. Equivalent embodiments; at the same time, all changes, modifications and evolutions of any equivalent changes made to the above-mentioned embodiments according to the substantive technology of the present invention still belong to the scope of the technical solution of the present invention.

Claims (8)

1. A photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device is characterized in that: the solar energy collector comprises a solar light collector (1) and a receiver (2), wherein the solar light collector (1) and the receiver (2) are arranged oppositely, and the receiver (2) is connected with a photon enhanced thermionic emission module group;

the photon enhanced thermionic emission module components are divided into a first photon enhanced thermionic emission module group (3) and a second photon enhanced thermionic emission module group (7), and the anode temperature corresponding to the first photon enhanced thermionic emission module group (3) is lower than the anode temperature corresponding to the second photon enhanced thermionic emission module group (7);

the anodes of the first photon enhanced thermionic emission module group (3) and the second photon enhanced thermionic emission module group (7) are respectively connected with a first cooler (4) and a second cooler (8); the outlet of the first cooler (4) is connected with the heat transfer medium side inlet of the first intermediate heat exchanger (5), the heat transfer medium side outlet of the first intermediate heat exchanger (5) is connected with the inlet of the first medium pump (6), and the outlet of the first medium pump (6) is connected with the inlet of the first cooler (4) to form a first cooling loop; the outlet of the second cooler (8) is connected with the heat transfer medium side inlet of the second intermediate heat exchanger (9), the heat transfer medium side outlet of the second intermediate heat exchanger (9) is connected with the inlet of the second medium pump (10), and the outlet of the second medium pump (10) is connected with the inlet of the second cooler (8) to form a second cooling loop;

the carbon dioxide side of the first intermediate heat exchanger (5) and the carbon dioxide side of the second intermediate heat exchanger (9) are connected with a supercritical carbon dioxide circulation system, and the heat of the heat transfer medium in the first cooling loop and the heat transfer medium in the second cooling loop are released to a carbon dioxide working medium of the supercritical carbon dioxide circulation system;

the supercritical carbon dioxide circulating system comprises a compressor (11), wherein the outlet of the compressor (11) is divided into two paths: one path is connected with a low-temperature side inlet of the low-temperature heat regenerator (12), and the other path is connected with a carbon dioxide side inlet of the first intermediate heat exchanger (5); the low-temperature side outlet of the low-temperature heat regenerator (12) and the carbon dioxide side outlet of the first intermediate heat exchanger (5) are combined and then connected with the low-temperature side inlet of the high-temperature heat regenerator (13), the low-temperature side outlet of the high-temperature heat regenerator (13) is connected with the carbon dioxide side inlet of the second intermediate heat exchanger (9), the carbon dioxide side outlet of the second intermediate heat exchanger (9) is connected with the turbine (14) inlet, the turbine (14) outlet is connected with the high-temperature side inlet of the high-temperature heat regenerator (13), the high-temperature side outlet of the high-temperature heat regenerator (13) is connected with the high-temperature side inlet of the low-temperature heat regenerator (12), the high-temperature side outlet of the low-temperature heat regenerator (12) is connected with the inlet of the precooler (16), and the outlet of the precooler (16) is connected with the inlet of the compressor (11); the compressor (11), the turbine (14) and the generator (15) are coaxially connected;

the heat transfer medium of the first cooling loop is heat transfer oil; the heat transfer medium of the second cooling loop is alkali metal liquid or molten salt.

2. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the condenser (1) is a disc condenser, a tower condenser or a Fresnel lens condenser.

3. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the receiver is a direct-lit receiver of a cavity structure.

4. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the anode temperature of the first photon enhanced thermionic emission module group (3) is 150-300 ℃; the anode temperature of the second photon enhanced thermionic emission module group (7) is 500-700 ℃.

5. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the first cooler (4) and the second cooler (8) are provided with expansion radiating surfaces.

6. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the first intermediate heat exchanger (5) and the second intermediate heat exchanger (9) are partition wall heat exchangers, and heat exchange wall surfaces of carbon dioxide sides of the first intermediate heat exchanger (5) and the second intermediate heat exchanger (9) are provided with expansion heat exchange surfaces.

7. A photon enhanced thermionic emission and carbon dioxide cycle combined power generation device as defined in claim 1, wherein: the low-temperature heat regenerator (12) and the high-temperature heat regenerator (13) are compact heat exchangers.

8. A photon-enhanced thermionic emission and carbon dioxide cycle combined power generation method is characterized in that: a photon-enhanced thermionic emission and carbon dioxide cycle combined power generation device as claimed in any one of claims 1-7, comprising the steps of: sunlight is focused to a receiver (2) through a condenser (1), the receiver (2) heats cathodes of a first photon enhanced thermionic emission module group (3) and a second photon enhanced thermionic emission module group (7), electrons emitted by the cathodes reach anodes through gaps between the two poles and simultaneously output electric energy from the two poles, and a first cooler (4) and a second cooler (8) cool the anodes and transfer waste heat to a heat transfer medium;

the first medium pump (6) and the second medium pump (10) continuously circulate and convey the heat transfer medium from the first cooler (4) and the second cooler (8) to the first intermediate heat exchanger (5) and the second intermediate heat exchanger (9) respectively, and the heat transfer medium releases heat to the carbon dioxide working medium of the supercritical carbon dioxide circulating system;

in the supercritical carbon dioxide circulating system, a compressor (11) compresses a carbon dioxide working medium, and the carbon dioxide working medium at an outlet of the compressor (11) is divided into two paths: one path enters a low-temperature heat regenerator (12), and the other path enters a first intermediate heat exchanger (5); two paths of carbon dioxide working media from the low-temperature heat regenerator (12) and the first intermediate heat exchanger (5) enter the high-temperature heat regenerator (13) together, enter the second intermediate heat exchanger for further heating, enter the turbine (14) for expansion and work, and push the generator (15) to generate electric energy; the turbine (14) exhaust gas sequentially enters the high-temperature heat regenerator (13) and the low-temperature heat regenerator (12), part of heat is transferred to the carbon dioxide working medium, and then is cooled by the precooler (16), and finally returns to the compressor (11).

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