Photothermal-Heat Pump Coupled Cogeneration Heating System and Method

Abstract

Disclosed is a cogeneration heating system and method coupling solar thermal energy and heat pump. In the system, steam is introduced into a power plant generator to do work. The extraction steam of the steam turbine is connected to the power plant generator. The first heat network heater is connected to the exhaust end of the steam turbine. The deaerator is connected to the exhaust end of the steam turbine and the power plant generator. The condenser is connected to the exhaust end of the steam turbine and the deaerator. The first absorption heat pump is connected to the first heat network heater and the condenser. The solar collector is connected to the first heat network heater and the first absorption heat pump to heat up the absorbed solar energy to the first heat network heater and the first absorption heat pump by heat transfer with heat-conducting oil. The second absorption heat pump is connected to the condenser and the second heat network heater via a circulating pump. The power plant circulating water cooling facility is connected to the second heat network heater, the second absorption heat pump and the condenser.

Description

Technical Field

[0001] The present invention relates to the technical field of energy, and particularly to a cogeneration heating system and method coupling solar thermal energy and heat pump. Background Art

[0002] Combined heat and power (CHP) refers to the combined production of thermal energy and electrical energy, providing thermal energy to users while generating electricity. The biggest feature of CHP is to adopt the principle of cascade utilization of energy, using steam with higher quality for power generation and steam with lower quality for heating.

[0003] The CHP system consists of a coal-fired power generation system and a heating system. The coal-fired power generation system uses the thermal energy of fuel to heat feed water, thereby generating high-temperature and high-pressure steam. The steam does work in the steam turbine to generate mechanical energy to drive the generator to generate electricity. The heating system extracts high-temperature and high-pressure steam from the intermediate pressure cylinder, reduces the pressure through a pressure reducing valve, and directly enters the heat network heater to heat the heat network water. To further save energy, an absorption heat pump can be selected for coupling. Heat pump technology uses high-temperature thermal energy as the driving source to recover and utilize low-temperature thermal energy, so as to achieve the effect of energy conservation and emission reduction, and has a wide range of forms.

[0004] Although CHP technology can reduce some heat losses, it also has defects such as low energy utilization efficiency, irreversible losses in the heat exchange between the extraction steam from the intermediate pressure cylinder and the heat network water, and waste heat losses. Traditional CHP units adopt the method of extracting steam from the intermediate pressure cylinder to heat the return water of the heat network water to the specified temperature through a steam-water heater. Due to the large temperature difference between the high-temperature and high-pressure steam and the return water of the heat network water, the irreversible loss of energy is relatively serious. There are various energy losses in the process of converting the chemical energy of fuel into electrical energy in the coal-fired power generation system, resulting in the inability to completely convert chemical energy into electrical energy. More than about 60% of the heat is dissipated into the environment through boiler flue gas and condenser circulating cooling water. And most traditional CHP energy structures are mainly based on single fossil fuels, without making full use of clean energy, improving the clean and efficient utilization of fossil fuels, and reducing the harm to the environment caused by emission pollution.

[0005] According to the second law of thermodynamics, the heat dissipation of the condenser is inevitable. If all or part of this part of the heat is recovered, it can reduce the irreversible loss of steam-water heat exchange, improve the energy utilization rate of the power plant, increase the power generation of the unit, and reduce environmental pollution.

[0006] The information disclosed in the background art section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0007] In view of the deficiencies or defects existing in the prior art, a cogeneration heating system and method coupling solar thermal energy and heat pumps are provided to improve the utilization efficiency of thermal power plants and solar thermal energy.

[0008] The object of the present invention is achieved through the following technical solutions.

[0009] A cogeneration heating system coupling solar thermal energy and heat pumps includes

[0010] a power plant generator that imports steam to perform work,

[0011] a steam turbine whose extracted steam is connected to the power plant generator,

[0012] a first heat network heater that is connected to the exhaust end of the steam turbine,

[0013] a deaerator that is connected to the exhaust end of the steam turbine and the power plant generator,

[0014] a condenser that is connected to the exhaust end of the steam turbine and the deaerator,

[0015] a first absorption heat pump that is connected to the first heat network heater and the condenser,

[0016] a solar collector that is connected to the first heat network heater and the first absorption heat pump to heat the absorbed solar energy to the first heat network heater and the first absorption heat pump through heat transfer oil,

[0017] a second absorption heat pump that is connected to the condenser and the second heat network heater via a circulation pump,

[0018] a power plant circulating water cooling facility that is connected to the second heat network heater, the second absorption heat pump and the condenser.

[0019] In the cogeneration heating system coupling solar thermal energy and heat pumps, the power plant generator, the steam turbine and the deaerator form a loop.

[0020] In the cogeneration heating system coupling solar thermal energy and heat pumps, the first heat network heater is connected to the first absorption heat pump via a first heat user.

[0021] In the cogeneration heating system coupling solar thermal energy and heat pumps, the second heat network heater is connected to the second absorption heat pump via a second heat user.

[0022] In the cogeneration heating system coupling solar thermal energy and heat pumps, the power plant circulating water cooling facility is a power plant cooling tower.

[0023] In the cogeneration heating system coupling solar thermal energy and heat pumps, the circulating cooling water of the condenser is extracted from the power plant cooling tower, and the circulating cooling water enters the condenser to participate in heat exchange.

[0024] In the combined heat and power heating system with photo-thermal and heat pump coupling, the first absorption heat pump or the second absorption heat pump both includes an evaporator and a condenser.

[0025] In the combined heat and power heating system with photo-thermal and heat pump coupling, the solar collector is a trough solar collector.

[0026] In the combined heat and power heating system with photo-thermal and heat pump coupling, the first absorption heat pump or the second absorption heat pump is a lithium bromide absorption heat pump.

[0027] The operation method of the combined heat and power heating system with photo-thermal and heat pump coupling includes the following steps.

[0028] When the solar radiation intensity exceeds a predetermined threshold, steam enters the power plant generator to do work. A part of the steam that has done work in the power plant steam turbine is extracted and used as the inlet steam of the steam turbine that drives the compressor in the first absorption heat pump.

[0029] A part of the exhaust steam of the steam turbine is discharged into the first heat network heater to heat the heat network water, and the other part enters the condenser to be condensed and then sent back to the boiler feed water.

[0030] The circulating cooling water of the condenser is extracted from the power plant cooling tower. The circulating water enters the condenser to participate in heat exchange and then its temperature rises. After the heat network return water returns to the thermal power plant, it is divided into two streams. One stream is heated by the solar energy absorbed by the trough solar collector through heat conduction oil heat exchange to the first heat network heater and the first absorption heat pump. The heat discharged from the absorber and condenser of the first absorption heat pump is used to preheat the heat network supply water, and the heat network supply water is further heated to the specified temperature by the extraction steam of the deaerator in the first heat network heater. The other stream is heated by absorbing heat through the second absorption heat pump and supplies heat to the second heat user through the second heat network heater, ensuring that the temperature of the heat network water at the outlet of the heat collection device always remains unchanged.

[0031] At night or when the solar radiation intensity is lower than the predetermined threshold, the trough solar collector stops working and the second absorption heat pump operates alone.

[0032] Compared with the prior art, the beneficial effects brought by the present invention are as follows:

[0033] The present invention utilizes a solar heat collection device to improve the utilization efficiency of solar energy, generate electricity and supply heat using more clean and renewable energy, which has a significant effect on environmental emission reduction. The absorption heat pump can ensure stable heat supply. When the heat energy provided by solar energy is insufficient, it releases heat to supplement the heat required for the temperature rise of the heat network water, reducing the impact brought by the change of solar radiation. Moreover, this system does not require a heat storage device for a conventional single solar power generation system, saving construction costs. By applying cascaded energy utilization, it can effectively recover the waste heat of circulating cooling water and the pressure difference energy of the extraction steam from the intermediate pressure cylinder, save energy and reduce consumption, and improve the utilization efficiency of thermal power plants and solar thermal energy, having good economic performance.

[0034] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to the extent that those skilled in the art can implement it according to the content of the specification, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable, the following takes the specific embodiments of the present invention as examples for illustration. Brief Description of the Drawings

[0035] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of showing the preferred embodiments and are not considered as limiting the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0036] In the drawings:

[0037] Figure 1 is a schematic structural diagram of the solar thermal - heat pump coupled cogeneration heating system of the present invention.

[0038] The following further explains the present invention in conjunction with the drawings and embodiments. Detailed Description of the Preferred Embodiments

[0039] The following will describe the specific embodiments of the present invention in more detail with reference to the drawings. Although the specific embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0040] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different terms to refer to the same component. The specification and claims do not use the difference in terms as a way to distinguish components, but use the difference in the functions of components as the criterion for distinction. For example, the terms "comprising" or "including" mentioned throughout the specification and claims are open-ended terms, so they should be interpreted as "including but not limited to". The subsequent description in the specification is the preferred embodiment for implementing the present invention, but the description is for the purpose of the general principles of the specification and is not used to limit the scope of the present invention. The protection scope of the present invention shall be subject to what is defined by the appended claims.

[0041] For the convenience of understanding the embodiments of the present invention, the following will further explain with several specific embodiments in conjunction with the drawings, and each drawing does not constitute a limitation on the embodiments of the present invention.

[0042] For better understanding, as Figure 1 shown, a solar thermal - heat pump coupled cogeneration heating system includes

[0043] a power plant generator 1, which introduces steam to do work

[0044] a steam turbine 2, whose extracted steam is connected to the power plant generator 1

[0045] a first heat network heater 5, which is connected to the exhaust end of the steam turbine 2

[0046] a deaerator 3, which is connected to the exhaust end of the steam turbine 2 and the power plant generator 1

[0047] a condenser 4, which is connected to the exhaust end of the steam turbine 2 and the deaerator 3

[0048] a first absorption heat pump 6, which is connected to the first heat network heater 5 and the condenser 4

[0049] a solar collector 7, which is connected to the first heat network heater 5 and the first absorption heat pump 6 to heat up the absorbed solar energy to the first heat network heater 5 and the first absorption heat pump 6 through heat transfer oil

[0050] a second absorption heat pump 8, which is connected to the condenser 4 via a circulation pump and is connected to a second heat network heater 9

[0051] a power plant circulating water cooling facility 10, which is connected to the second heat network heater 9, the second absorption heat pump 8 and the condenser 4.

[0052] In the preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system described above, the power plant generator 1, the steam turbine 2 and the deaerator 3 form a loop.

[0053] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, the first heat network heater 5 is connected to the first absorption heat pump 6 via the first heat user 11.

[0054] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, the second heat network heater 9 is connected to the second absorption heat pump 8 via the second heat user 12.

[0055] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, the power plant circulating water cooling facility 10 is a power plant cooling tower.

[0056] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, the circulating cooling water of the condenser 4 is extracted from the power plant cooling tower, and the circulating cooling water enters the condenser 4 to participate in heat exchange.

[0057] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, both the first absorption heat pump 6 and the second absorption heat pump 8 include an evaporator and a condenser.

[0058] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, the solar collector 7 is a trough - type solar collector 7.

[0059] In a preferred embodiment of the solar thermal - heat pump coupled cogeneration heating system, both the first absorption heat pump 6 and the second absorption heat pump 8 are lithium bromide absorption heat pumps.

[0060] The operation method of the solar thermal - heat pump coupled cogeneration heating system includes the following steps.

[0061] When the solar radiation intensity exceeds a predetermined threshold, steam enters the power plant generator 1 to perform work. A part of the steam that has done work in the power plant steam turbine 2 is extracted and used as the inlet steam of the steam turbine 2 that drives the compressor in the first absorption heat pump 6.

[0062] A part of the exhaust steam of the steam turbine 2 is discharged into the first heat network heater 5 to heat the heat network water, and the other part enters the condenser 4 to be condensed and then sent back to the boiler feed water.

[0063] The circulating cooling water of the condenser 4 is extracted from the power plant cooling tower. After the circulating water enters the condenser 4 to participate in heat exchange, its temperature rises. After the return water of the heat supply network returns to the thermal power plant, it is divided into two streams. One stream of flow is heated by the solar energy absorbed by the trough solar collector 7 through heat exchange with heat-conducting oil and sent to the first heat supply network heater 5 and the first absorption heat pump 6. The heat discharged from the absorber and condenser of the first absorption heat pump 6 is used to preheat the heat supply network water. The heat supply network water is further heated to the specified temperature by the extraction steam of the deaerator 3 in the first heat supply network heater 5. The other stream of flow absorbs heat and rises in temperature through the second absorption heat pump 8, and supplies heat to the second heat user 12 through the second heat supply network heater 9, ensuring that the temperature of the heat supply network water at the outlet of the heat collection device always remains unchanged;

[0064] When night falls or the solar radiation intensity is lower than the predetermined threshold, the trough solar collector 7 stops working, and the second absorption heat pump 8 operates alone.

[0065] In one embodiment, the solar thermal - heat pump coupled cogeneration heating system includes a coal - fired power generation system and a heating system. While using the traditional coal - fired power generation system, a solar heat collection device is utilized to improve the utilization efficiency of solar energy and use more renewable energy for power generation and heating. Two sets of lithium bromide absorption heat pumps are used to recover the waste heat of the exhaust steam of the steam turbine 2 and the waste heat of the circulating cooling water of the condenser 4 respectively, saving energy and reducing consumption, and improving the utilization efficiency of the thermal power plant and solar thermal energy. When the solar radiation is insufficient, the solar thermal system can be bypassed, and the lithium bromide heat pump will operate alone.

[0066] In one embodiment, the solar thermal - heat pump coupled cogeneration heating system includes a steam turbine, a lithium bromide absorption heat pump, a trough solar collector, a heat supply network heater and its auxiliary equipment, which are connected by corresponding pipelines. The system can be divided into two working forms according to the sufficient solar radiation intensity. When the solar radiation intensity is sufficient during the day, the connection form of the system is that the extraction steam of the power plant generator 1 is connected to the steam turbine 2, the exhaust steam of the steam turbine 2 is connected to the first heat supply network heater 5 and the deaerator 3, the first heat supply network heater 5 is connected to the first absorption heat pump 6 and the first heat user 11, and the solar collector 7 heats the absorbed solar energy through heat exchange with heat - conducting oil and sends it to the first heat supply network heater 5 and the first absorption heat pump 6. The condenser 4 is connected to the evaporators of the first absorber heat pump 6 and the second absorber heat pump 8 through pipelines and circulating pumps, and the second absorber heat pump 8 is further connected to the second heat supply network heater 9 and the power plant circulating water cooling facility 10. When night falls or the solar radiation intensity is insufficient, the solar thermal system can be bypassed, and the second absorber heat pump 8 will operate alone.

[0067] In one embodiment, when the solar radiation intensity is sufficient during the day, steam enters the power plant generator 1 to do work. A part of the steam that has done work in the power plant generator 1 is extracted and used as the inlet steam for the steam turbine 2 that drives the compressor in the first absorption heat pump 6. A part of the exhaust steam of the steam turbine 2 is discharged into the first heat network heater 5 to heat the heat network water, and the other part enters the condenser 4 to be condensed and then sent back to the boiler feed water. The circulating cooling water of the condenser 4 is extracted from the power plant circulating water cooling facility 10 such as the power plant cooling tower. The circulating water enters the condenser 4 to participate in heat exchange and its temperature rises. After the heat network return water returns to the thermal power plant, it is divided into two streams. A small flow rate passes through the trough-type solar collector 7 to absorb solar energy and heat up the heat transfer oil, and then exchanges heat with the first heat network heater 5 and the first absorption heat pump 6. The heat discharged from the absorber and condenser of the first absorption heat pump 6 is used to preheat the heat network supply water, and the heat network supply water is further heated to the specified temperature by the extraction steam of the deaerator 3 in the first heat network heater. Another large flow rate absorbs heat and rises in temperature through the second absorption heat pump 8, and supplies heat to the second heat user 12 through the second heat network heater 9, ensuring that the temperature of the heat network water at the outlet of the heat collection device remains constant and ensuring stable heat supply.

[0068] In one embodiment, when the solar radiation intensity is sufficient during the day, the heat transfer oil leaving the solar collector is used as the driving heat source to release heat in the generator of the first absorption heat pump 6. The circulating working fluid absorbs heat and evaporates. The generated steam is condensed in the condenser of the heat pump and then throttled and flows into the evaporator. Then, the low-temperature heat source in the evaporator uses part of the circulated cooling water that has already exchanged heat. The steam absorbs heat from the circulated cooling water and evaporates. Finally, the saturated steam at low temperature and low pressure is sent to the absorber to be absorbed by the lithium bromide solution. Therefore, the heat discharged from the absorber and condenser of the first absorption heat pump 6 can be used to preheat the heat network supply water. After that, the heat network supply water is further heated to the specified temperature by the extraction steam of the deaerator 3 in the first heat network heater. Since the heat network water obtains energy in the absorption heat pump before the first heat network heater, the amount of heat required from the heat network heater becomes less, and the amount of extraction steam of the deaerator 3 entering the first heat network heater decreases. The saved extraction steam can continue to expand and do work in the steam turbine, increasing the total power generation of the system while keeping the heat supply constant. When it is night or the solar radiation is insufficient, the solar thermal system can be bypassed, and the second absorption heat pump 8 will operate alone to ensure stable heat supply of the system.

[0069] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present application are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present application. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present application to necessarily adopt the above specific details to implement.

[0070] The foregoing description has been presented for purposes of illustration and description. In addition, this description is not intended to limit embodiments of the present application to the forms disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize some variations, modifications, alterations, additions, and subcombinations thereof.

Claims

1. A solar thermal-heat pump coupled cogeneration heating system, characterized in that: These include, Power plant generators, which introduce steam to produce work, The steam turbine, whose extraction steam is connected to the power plant generator, a first heating network heater connected to the exhaust end of the steam turbine, a deaerator connected to the exhaust end of the steam turbine and the power plant generator, A condenser connected to the exhaust end of the steam turbine and the deaerator, a first absorption heat pump connected to the first heating network heater and the condenser, A solar thermal collector is connected to the first heat network heater and the first absorption heat pump to heat the absorbed solar energy to the first heat network heater and the first absorption heat pump by heat transfer oil. A second absorption heat pump is connected to the condenser and to a second heating network heater via a circulation pump, The power plant circulating water cooling facility is connected to the second heating network heater, the second absorption heat pump and the condenser.

2. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: Preferably, the power plant generator, steam turbine and deaerator form a loop.

3. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The first heating network heater is connected to the first absorption heat pump via the first heat user.

4. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The second heating network heater is connected to a second absorption heat pump via a second heat user.

5. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The power plant circulating water cooling facility is a power plant cooling tower.

6. The solar thermal-heat pump coupled cogeneration heating system according to claim 5, characterized in that: The circulating cooling water of the condenser is extracted from a cooling tower of a power plant, and the circulating cooling water enters the condenser to participate in heat exchange.

7. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The first absorption heat pump or the second absorption heat pump both includes an evaporator and a condenser.

8. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The solar thermal collector is a trough type solar thermal collector.

9. The solar thermal-heat pump coupled cogeneration heating system according to claim 1, characterized in that: The first absorption heat pump or the second absorption heat pump is a lithium bromide absorption heat pump.

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