Solar PVT steam preparation system based on two-stage air-supply enthalpy-increasing heat pump cascade upgrading

Abstract

The invention discloses a solar PVT steam preparation system based on cascade upgrading of a two-stage gas-supplementing enthalpy-increasing heat pump. The system comprises a first-stage gas-supplementing enthalpy-increasing PVT heat pump system, a heat storage system, a second-stage gas-supplementing enthalpy-increasing high-temperature heat pump system, a steam generation system and a green power supply system. The first-stage air-supplementing enthalpy-increasing PVT heat pump system uses a PVT assembly as an evaporator to prepare medium-temperature hot water and store the medium-temperature hot water in the heat storage system. The second-stage air-supplementing enthalpy-increasing high-temperature heat pump system uses the heat storage system as a stable low-temperature heat source to prepare high-temperature hot water. The steam generation system flashes high-temperature hot water into saturated steam, and then the saturated steam is pressurized into steam required by industry through the steam compressor. The PVT assembly simultaneously generates electricity for self-use of the system, and residual electricity is connected to the internet. According to the steam and electric energy co-production system, cascade improvement and efficient utilization of heat are achieved through the two-stage air-supplementing enthalpy-increasing heat pump technology, the energy storage technology is coupled, the problem that steam supply is unstable due to solar energy intermittency is solved, steam and electric energy co-production is achieved, and the system is efficient, stable and low-carbon.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar photovoltaic and photothermal comprehensive utilization and industrial steam, and particularly relates to a solar PVT steam preparation system based on two-stage air supplementing and enthalpy increasing heat pump cascade upgrading, so as to realize stable and efficient preparation of industrial steam. TECHNICAL BACKGROUND Industrial steam is the core energy in the fields of food processing, textile printing and dyeing, and chemical production. At present, steam supply mainly depends on coal-fired or gas-fired boilers, which has the problems of high carbon emission and large energy consumption. As a clean and renewable energy, solar energy directly used to generate industrial steam faces two big bottlenecks: one is low energy density and strong intermittency, which is difficult to continuously and stably supply energy; the other is that the conventional solar heat collection system or single-stage heat pump is difficult to reach the high temperature (usually > 120 DEG C) required by industry.

[0002] In the prior art, a solar photovoltaic and photothermal (PVT) assembly can synchronously output electric energy and low-temperature heat energy, but the heat energy has a low grade; a high-temperature heat pump can increase the temperature, but has strict requirements on the stability of the heat source. The system simply combining the PVT and the heat pump has a sharp performance decline when the solar radiation fluctuates, and cannot realize stable output of high-temperature steam. Therefore, there is an urgent need for a system scheme which can integrate solar energy, realize heat cascade upgrading and storage, and finally stably output high-temperature steam. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art, and provide a solar PVT steam preparation system based on two-stage air supplementing and enthalpy increasing heat pump cascade upgrading. The system realizes efficient conversion of solar energy in time and grade through multi-stage coupling of "PVT power generation and heat collection, first-stage heat pump temperature upgrading and heat storage, second-stage heat pump high-temperature heating, and flash compression steam generation", and is configured with heat storage buffer and green power supply, so as to finally continuously and stably output industrial high-temperature steam and electric energy.

[0004] To achieve the above purpose, the present application adopts the following technical scheme: A solar PVT steam preparation system based on two-stage air supplementing and enthalpy increasing heat pump cascade upgrading, characterized in that it comprises a first-stage air supplementing and enthalpy increasing PVT heat pump system, a heat storage system, a second-stage air supplementing and enthalpy increasing high-temperature heat pump system, a steam generation system, and a green power supply system which are connected in sequence and work cooperatively.

[0005] The first-stage air supplementing and enthalpy increasing PVT heat pump system takes a PVT assembly as an evaporator to absorb solar energy and air energy, and prepares medium-temperature hot water which is stored in the heat storage system; The heat storage system serves as a heat buffer and storage unit to provide a stable low-temperature heat source for the second-stage system; The second-stage air supplementing and enthalpy increasing high-temperature heat pump system takes the hot water in the heat storage system as a heat source to prepare high-temperature hot water; The steam generation system flashes high-temperature hot water into saturated steam, which is then pressurized by a steam compressor to meet industrial steam requirements. The green power supply system generates electricity from PVT modules and prioritizes its own use, with surplus electricity going to the grid. When insufficient, the grid supplements the power supply, achieving self-balancing and greening of the system's electricity consumption.

[0006] Furthermore, the primary gas-fuel-injection enthalpy-increasing PVT heat pump system mainly consists of compressor 1, oil separator 2, one-way valve 3, hot water heat exchanger 4, dryer filter 5, liquid receiver 6, sight glass 7, electronic expansion valve 8, intercooler 9, one-way valve 2 10, electronic expansion valve 2 11, PVT array 12, and gas-liquid separator 13. Compressor 1 is sequentially connected to oil separator 2, one-way valve 3, hot water heat exchanger 4, dryer filter 5, liquid receiver 6, and sight glass 7, and then splits into two paths. One path connects to electronic expansion valve 8, intercooler 9, and one-way valve 2 10 to enter the low-pressure inlet of compressor 1; the other path connects to intercooler 9, electronic expansion valve 2 11, PVT array 12, and gas-liquid separator 13 to enter the low-pressure inlet of compressor 1. Furthermore, the two-stage gas replenishment and enthalpy-increasing high-temperature heat pump system mainly consists of compressor 218, oil separator 219, one-way valve 320, hot water heat exchanger 321, dryer filter 222, liquid receiver 23, sight glass 24, electronic expansion valve 325, intercooler 26, one-way valve 427, electronic expansion valve 428, hot water heat exchanger 217, and gas-liquid separator 29. Compressor 218 is sequentially connected to oil separator 219, one-way valve 320, hot water heat exchanger 321, dryer filter 222, liquid receiver 23, and sight glass 24, and then splits into two paths. One path connects to electronic expansion valve 325, intercooler 226, and one-way valve 427 to enter the low-pressure inlet of compressor 218; the other path connects to intercooler 226, electronic expansion valve 428, hot water heat exchanger 217, and gas-liquid separator 29 to enter the low-pressure inlet of compressor 218. Furthermore, the compressor types 1 and 2 include rotary, scroll, piston, and centrifugal types; Furthermore, the steam compressor type 32 includes single-screw, twin-screw, and centrifugal types; Furthermore, the types of hot water heat exchangers 1-4, 3-21, and 2-17 include flat plate, spiral plate, plate-ribbed, shell-and-tube, and shell-and-tube types. Furthermore, the heat storage system mainly consists of a hot water storage tank 14, a hot water heat exchanger 14, a hot water heat exchanger 2 17, a water pump 15, and a water pump 2 16. The water side of the hot water heat exchanger 14 is connected to the water pump 15 and the hot water storage tank 14 via water pipes; the water side of the hot water heat exchanger 2 17 is connected to the water pump 2 16 and the hot water storage tank 14 via water pipes. Furthermore, the steam generation system mainly consists of a hot water heat exchanger 321, a water pump 30, a flash tank 31, a steam compressor 32, a water pump 43, a solenoid valve 34, and a hot water storage tank 14. The steam side of the flash tank 31 is connected to the steam compressor 32 via a steam pipeline; the water side of the flash tank 31 is connected to the water pump 30 and the hot water heat exchanger 321 via a water pipeline; the water side of the flash tank 31 is connected to the hot water storage tank 14, the water pump 43, and the solenoid valve 34 via a water pipeline. Furthermore, the power supply system mainly consists of a PVT array 12, a DC converter 35, and an AC / DC inverter 36. The power supply system is divided into two paths: one path connects the PVT array 12 to the DC converter 35, and the other path connects the municipal power grid to the AC / DC inverter 36. The two paths are combined and connected to compressor 1, compressor 2, steam compressor 32, water pump 1, water pump 2, water pump 3, and water pump 4. Furthermore, the solar cell element types of the PVT array 12 include monocrystalline silicon, polycrystalline silicon, copper indium gallium selenide, gallium arsenide, cadmium telluride, and perovskite; compressor 1, compressor 2 18, steam compressor 32, water pump 1 15, water pump 2 16, water pump 3 30, and water pump 4 33 are driven by DC motors, including DC brushless motors or permanent magnet synchronous motors.

[0007] The beneficial effects of this invention are: This invention enables a cascaded and efficient conversion of solar energy into high-temperature steam. Through a two-stage gas-injection and enthalpy-enhancing design—a "first-stage gas-injection and enthalpy-enhancing heat pump (PVT heat pump) + a second-stage gas-injection and enthalpy-enhancing heat pump (high-temperature steam heat pump)"—the heat is efficiently and progressively increased from ambient temperature to intermediate temperature and then from intermediate temperature to high temperature, making it possible to use solar energy to produce high-temperature industrial steam.

[0008] This invention completely solves the problem of intermittent solar energy supply. The heat storage system, as a key buffer unit, stores the heat energy generated by the first-stage gas-injection enthalpy-increasing heat pump, providing a continuous and stable low-temperature heat source for the second-stage gas-injection enthalpy-increasing heat pump. This effectively smooths out fluctuations in solar energy and ensures the continuity and stability of steam output.

[0009] This invention utilizes energy comprehensively and has a high energy efficiency ratio. The system simultaneously utilizes both the "light" and "heat" of solar energy. The PVT module generates electricity for self-use, reducing dependence on the external power grid and operating electricity costs; both-stage heat pumps employ gas injection and enthalpy enhancement technology, improving the energy efficiency ratio (COP) under wide temperature range and high pressure ratio conditions, resulting in a high overall primary energy utilization rate for the system.

[0010] This invention is a green and low-carbon technology with broad application prospects. It directly uses solar energy as its driving force, producing almost no direct carbon emissions, thus aligning with the "dual-carbon" strategy. The system is highly modular, suitable for the renovation or new construction of various industrial plants with existing steam demand, and has significant potential for widespread adoption. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascade quality improvement, according to the present invention. Numbering in the diagram: 1-Compressor I, 2-Oil Separator I, 3-Check Valve I, 4-Hot Water Heat Exchanger I, 5-Dryer Filter I, 6-Liquid Receiver I, 7-Sight Glass I, 8-Electronic Expansion Valve I, 9-Intercooler I, 10-Check Valve II, 11-Electronic Expansion Valve II, 12-PVT Array, 13-Gas-Liquid Separator I, 14-Hot Water Storage Tank, 15-Water Pump I, 16-Water Pump II, 17-Hot Water Heat Exchanger II, 18-Compressor II, 19 - Oil separator II, 20- One-way valve III, 21- Hot water heat exchanger III, 22- Dryer filter II, 23- Liquid receiver II, 24- Sight glass II, 25- Electronic expansion valve III, 26- Intercooler II, 27- One-way valve IV, 28- Electronic expansion valve IV, 29- Gas-liquid separator II, 30- Water pump III, 31- Flash tank, 32- Steam compressor, 33- Water pump IV, 34- Solenoid valve, 35- DC converter, 36- AC / DC inverter. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] like Figure 1 As shown in this embodiment, a solar PVT steam preparation system based on a two-stage gas-injection enthalpy-enhancing heat pump for cascaded quality improvement includes a first-stage gas-injection enthalpy-enhancing PVT heat pump system, a heat storage system, a second-stage gas-injection enthalpy-enhancing high-temperature heat pump system, a steam generation system, and a green power supply system.

[0014] The primary gas-fuel-injection enthalpy-increasing PVT heat pump system mainly consists of a compressor-1, an oil separator-2, a one-way valve-3, a hot water heat exchanger-4, a dryer filter-5, a liquid receiver-6, a sight glass-7, an electronic expansion valve-8, an intercooler-9, a one-way valve-2, an electronic expansion valve-2, a PVT array-12, and a gas-liquid separator-13, all connected by refrigerant piping. The two-stage gas-fuel-injection high-temperature heat pump system mainly consists of compressor 218, oil separator 219, one-way valve 320, hot water heat exchanger 21, dryer filter 22, liquid receiver 23, sight glass 24, electronic expansion valve 325, intercooler 26, one-way valve 427, electronic expansion valve 428, hot water heat exchanger 317, and gas-liquid separator 29 connected by refrigerant pipelines. The heat storage system mainly consists of a hot water storage tank 14, a hot water heat exchanger 1 4, a hot water heat exchanger 3 17, a water pump 1 15, and a water pump 2 16 connected by water pipes. The flash tank 31 is connected to the steam compressor 32 via a steam pipeline on its steam side; the flash tank 31 is connected to the water pump 30 and the hot water heat exchanger 21 via a water pipeline on its water side; the flash tank 31 is also connected to the hot water storage tank 14, the water pump 43, and the solenoid valve 34 via a water pipeline on its water side. The power supply system mainly consists of a PVT array 12, a DC-DC converter 35, and an AC-DC inverter 36 connected by circuits.

[0015] In this embodiment, as Figure 1 As shown, the working principle of the first-stage gas-fuel-injection-enthalpy-increasing PVT heat pump system is as follows: Compressor 1 compresses the refrigerant into a high-temperature, high-pressure gas, which then passes through oil separator 2 and one-way valve 3 before entering the hot water heat exchanger 4, where it releases heat and condenses into the circulating water. The liquid refrigerant, after passing through dryer filter 5 and receiver 6, is divided into two paths: one path throttles through electronic expansion valve 8 and enters intercooler 9 to absorb heat, becoming a medium-temperature, medium-pressure gas; the other path, after being subcooled by intercooler 9, is throttled by electronic expansion valve 11 and enters PVT array 12 to absorb solar radiation heat and evaporate with air energy, ultimately returning to compressor 1. During this process, the circulating water, driven by water pump 15, flows through hot water heat exchanger 4 and is heated to 60-70℃, then stored in hot water storage tank 14. In this embodiment, as Figure 1 As shown, the working principle of the two-stage gas-fuel-injection enthalpy-increasing high-temperature heat pump system is as follows: When the water temperature in the hot water storage tank 14 reaches the set value, the two-stage gas-fuel-injection enthalpy-increasing high-temperature heat pump system starts. The high-temperature refrigerant discharged from compressor 2 18 releases heat and condenses in the hot water heat exchanger 3 21. The liquid refrigerant is also divided into two paths: one path enters the intercooler 2 26 after being throttled by electronic expansion valve 3 25 to absorb heat and inject gas; the other path, after being subcooled, enters the hot water heat exchanger 2 17 after being throttled by electronic expansion valve 4 28, absorbs the stable low-temperature heat source (such as 60℃ hot water) provided by the hot water storage tank 14 and evaporates, returning to compressor 2 18. The high-temperature water is heated in the hot water heat exchanger 3 21 under the drive of water pump 3 30. In this embodiment, as Figure 1As shown, the working principle of the steam generation system is as follows: High-temperature saturated liquid water (120℃, 1.98 bar) in flash tank 31 is pressurized under the drive of water pump 30, enters hot water heat exchanger 321 to absorb heat and rise in temperature, and then transforms into higher-temperature saturated liquid water (125℃, 2.32 bar), and then flashes into a gas-liquid two-phase state (120℃, 1.98 bar) in flash tank 31. The liquid water is then pressurized under the drive of water pump 30 and continues to absorb heat in heat exchanger 21; while the gaseous water vapor is pressurized and heated to the industrial steam required (150℃) by steam compressor 32 and then output; in addition, the water loss caused by steam output of the steam generation system is automatically replenished by hot water storage tank 14 through water pump 33 and solenoid valve 34. In this embodiment, as Figure 1 As shown, the working principle of the green power supply system is as follows: The solar cells in the PVT array 12 absorb solar shortwave radiation and convert solar energy into DC power. After being converted into DC 750V by the DC converter 35, it is preferentially used by compressor 1, compressor 2 18, steam compressor 32, water pump 1 15, water pump 2 16, water pump 30, and water pump 4 33. If the output power of the PVT array 12 is greater than the system power consumption, the excess power is connected to the grid through the AC / DC inverter 36. If the output power of the PVT array 12 is less than the system power consumption, the grid is converted into DC 750V by the AC / DC inverter 36 to power compressor 1, compressor 2 18, steam compressor 32, water pump 1 15, water pump 2 16, water pump 30, and water pump 4 33.

[0016] During nighttime or periods without sunlight, the primary gas-fueled enthalpy-increasing PVT heat pump system can be shut down, while the secondary gas-fueled enthalpy-increasing high-temperature heat pump system continues to use the heat stored in the hot water storage tank 14 as a heat source to drive the steam generation system to work continuously, thereby achieving stable steam supply around the clock.

[0017] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascaded quality improvement, characterized in that, The system includes a primary gas-injection enthalpy-increasing PVT heat pump system, a heat storage system, a secondary gas-injection enthalpy-increasing high-temperature heat pump system, a steam generation system, and a green power supply system. The primary gas-fuel-injection enthalpy-increasing PVT heat pump system mainly consists of a compressor (1), an oil separator (2), a check valve (3), a hot water heat exchanger (4), a dryer filter (5), a liquid receiver (6), a sight glass (7), an electronic expansion valve (8), an intercooler (9), a check valve (2) (10), an electronic expansion valve (2) (11), a PVT array (12), and a gas-liquid separator (13). The compressor (1) is connected in sequence to the oil separator (2) and the check valve (3). The hot water heat exchanger (4), the dryer filter (5), the liquid storage tank (6), and the sight glass (7) split into two paths. One path connects to the electronic expansion valve (8), the intercooler (9), and the one-way valve (10) and enters the low-pressure inlet of the compressor (1). The other path connects to the intercooler (9), the electronic expansion valve (11), the PVT array (12), and the gas-liquid separator (13) and enters the low-pressure inlet of the compressor (1). The heat storage system mainly consists of a hot water storage tank (14), a hot water heat exchanger (4), a hot water heat exchanger (17), a water pump (15), and a water pump (16). The water side of the hot water heat exchanger (4) is connected to the water pump (15) and the hot water storage tank (14) via water pipes; the water side of the hot water heat exchanger (17) is connected to the water pump (16) and the hot water storage tank (14) via water pipes. The two-stage gas-fuel-injection high-temperature heat pump system mainly consists of compressor two (18), oil separator two (19), one-way valve three (20), hot water heat exchanger three (21), dryer filter two (22), liquid receiver two (23), sight glass two (24), electronic expansion valve three (25), intercooler two (26), one-way valve four (27), electronic expansion valve four (28), hot water heat exchanger two (17), and gas-liquid separator two (29). The compressor two (18) is connected in sequence to the oil separator two (19) and the one-way valve three (20). Two paths branch off from the hot water heat exchanger (21), the dryer filter (22), the liquid receiver (23), and the sight glass (24). One path connects to the electronic expansion valve (25), the intercooler (26), and the check valve (27) and enters the low-pressure inlet of the compressor (18). The other path connects to the intercooler (26), the electronic expansion valve (28), the hot water heat exchanger (17), and the gas-liquid separator (29) and enters the low-pressure inlet of the compressor (18). The steam generation system mainly consists of a hot water heat exchanger (21), a water pump (30), a flash tank (31), a steam compressor (32), a water pump (33), a solenoid valve (34), and a hot water storage tank (14). The steam side of the flash tank (31) is connected to the steam compressor (32) via a steam pipeline; the water side of the flash tank (31) is connected to the water pump (30) and the hot water heat exchanger (21) via a water pipeline; the water side of the flash tank (31) is connected to the hot water storage tank (14), the water pump (33), and the solenoid valve (34) via a water pipeline. The power supply system mainly consists of a PVT array (12), a DC converter (35), and an AC / DC inverter (36). The power supply system is divided into two paths: one path connects the PVT array (12) to the DC converter (35), and the other path connects the municipal power grid to the AC / DC inverter (36). The two paths are combined and connected to the compressor one (1), the compressor two (18), the steam compressor (32), the water pump one (15), the water pump two (16), the water pump three (30), and the water pump four (33).

2. The solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascade quality improvement according to claim 1, characterized in that: The compressor type 1 (1) and compressor type 2 (18) include rotary, scroll, piston and centrifugal.

3. The solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascade quality improvement according to claim 1, characterized in that: The steam compressor (32) types include single-screw, twin-screw, and centrifugal.

4. The solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascaded quality improvement according to claim 1, characterized in that: The types of the hot water heat exchanger one (4), the hot water heat exchanger three (21), and the hot water heat exchanger two (17) include flat plate type, spiral plate type, plate rib type, shell and tube type, and shell and tube type.

5. The solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascaded quality improvement according to claim 1, characterized in that, The solar cell element types of the PVT array (12) include monocrystalline silicon, polycrystalline silicon, copper indium gallium selenide, gallium arsenide, cadmium telluride, and perovskite.

6. The solar PVT steam preparation system based on a two-stage gas-injection enthalpy-increasing heat pump for cascaded quality improvement according to claim 1, characterized in that: The compressor one (1), the compressor two (18), the steam compressor (32), the water pump one (15), the water pump two (16), the water pump three (30), and the water pump four (33) are driven by DC motors, including DC brushless motors or permanent magnet synchronous motors.

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