PVT heat pump vacuum membrane distillation wastewater treatment system

Abstract

A PVT heat pump vacuum membrane distillation wastewater treatment system belongs to the field of energy saving and environmental protection. The system comprises a photovoltaic-thermal (PVT) heat pump, a vacuum membrane distillation assembly, a circulating pump, a vacuum pump and other equipment. Its characteristics are as follows: firstly, industrial wastewater is pretreated into a dilute solution, which is driven into a first heat exchanger by the circulating pump, and the dilute solution is preheated by using the heat energy generated by photovoltaic power generation. Secondly, the dilute solution is evaporated in the vacuum membrane distillation assembly, the produced secondary steam is compressed by a compressor to increase temperature and pressure, and then enters a second heat exchanger to condense and release heat to the concentrated liquid, and the heated concentrated liquid returns to the feed water tank for continuous concentration, and is recycled after reaching the required concentration. The invention makes full use of photovoltaic-thermal and secondary steam latent heat, meets the energy demand of the vacuum membrane distillation wastewater treatment process, has the advantages of high energy utilization efficiency, low operation cost, strong operation stability and the like, and is suitable for industrial heating, wastewater treatment and other fields.

Description

Technical Field

[0001] This utility model relates to a PVT heat pump vacuum membrane distillation wastewater treatment system, which belongs to the field of energy conservation and environmental protection. Background Technology

[0002] With the rapid development of global industrialization, industries such as manufacturing, chemicals, metallurgy, textiles, and pharmaceuticals generate large amounts of wastewater containing pollutants such as heavy metals, organic matter, and acids and alkalis. If not properly treated, this wastes resources and damages the ecological environment. Clearly, developing clean and efficient industrial wastewater treatment technologies is of significant value and importance in addressing the global energy crisis and environmental problems.

[0003] Vacuum membrane distillation is a hybrid technology based on membrane separation and distillation, aiming to achieve efficient separation of solution wastewater by utilizing hydrophobic microporous membranes and vacuum negative pressure to drive water vapor mass transfer. A vacuum membrane distillation system mainly consists of a vacuum membrane module, feed pump, feed tank, condensate tank, and vacuum pump. Due to its high efficiency, low temperature, and anti-fouling characteristics, it is widely used in the zero-discharge and resource utilization of industrial wastewater. However, existing vacuum membrane distillation systems lack latent heat recovery devices, resulting in high evaporation energy consumption, thus limiting its further industrial application.

[0004] Solar energy is a clean and renewable energy source with abundant reserves, wide distribution, and significant application potential. Photovoltaic thermal (PVT) heat pump technology is currently an effective way to utilize solar energy. Combining PVT technology with heat pump technology not only improves the efficiency of solar photovoltaic power generation but also meets heating and cooling needs. At present, PVT heat pump technology and vacuum membrane distillation technology are gradually being applied in my country, but research on their application in industrial wastewater treatment is limited. Therefore, coupling PVT heat pump technology and vacuum membrane distillation technology to efficiently and cost-effectively meet the needs of industrial wastewater treatment, achieving zero emissions and resource utilization, is of significant value and importance for achieving the grand strategic goal of "carbon peaking and carbon neutrality." Utility Model Content

[0005] This invention proposes a PVT heat pump vacuum membrane distillation wastewater treatment system and method with low energy consumption and high stability.

[0006] The PVT heat pump vacuum membrane distillation wastewater treatment system is characterized by mainly comprising: a pretreatment unit, a first control valve, a second control valve, a third control valve, a fourth control valve, a fifth control valve, a feed tank, a circulating pump, a throttling valve, a PVT evaporator, a battery, a photovoltaic inverter integrated machine, a gas-liquid separator, a first compressor, a second compressor, a first heat exchanger, a second heat exchanger, a vacuum membrane distillation assembly, a condensate tank, and a vacuum pump;

[0007] The pretreatment unit is connected to the inlet of the feed tank via a first control valve. The outlet of the feed tank is connected to the inlet of the circulating pump via a second control valve. The outlet of the circulating pump is connected to the cold side inlet of the first heat exchanger. The cold side outlet of the first heat exchanger is connected to the inlet of the vacuum membrane distillation assembly. The steam outlet of the vacuum membrane distillation assembly is connected to the inlet of the second compressor. The outlet of the second compressor is connected to the hot side inlet of the second heat exchanger. The hot side outlet of the second heat exchanger is connected to the top inlet of the condensate tank. The top outlet of the condensate tank is connected to the vacuum pump via a fifth control valve. The solution outlet of the vacuum membrane distillation assembly is connected to the cold side inlet of the second heat exchanger. The cold side outlet of the second heat exchanger is connected to the top inlet of the feed tank.

[0008] The hot-side outlet of the first heat exchanger is connected to the throttle valve, and then connected to the inlet of the evaporation coil in the PVT evaporator via the third control valve. The outlet of the evaporation coil in the PVT evaporator is connected to the left inlet of the gas-liquid separator. The top outlet of the gas-liquid separator is connected to the inlet of the first compressor. The outlet of the first compressor is connected to the hot-side inlet of the first heat exchanger. The bottom outlet of the gas-liquid separator is connected to the fourth control valve.

[0009] The photovoltaic inverter is connected to both the battery and the PVT evaporator.

[0010] The PVT heat pump vacuum membrane distillation wastewater treatment system is characterized in that: the PVT evaporator is composed of a glass cover plate, an EVA film, a photovoltaic panel, an aluminum-based back plate, and an evaporation coil.

[0011] The PVT heat pump vacuum membrane distillation wastewater treatment system is characterized in that: the vacuum membrane distillation component is composed of multiple hollow fiber membrane filaments, each membrane filament is made of polytetrafluoroethylene hydrophobic evaporation membrane with a pore size of less than 0.2 μm and a porosity of 20%-85%.

[0012] The PVT heat pump vacuum membrane distillation wastewater treatment system is characterized in that the working fluid used in the heat pump system is R134a, or R22, or R123, or R410A.

[0013] The working method of the PVT heat pump vacuum membrane distillation wastewater treatment system is characterized by the following process: Industrial wastewater is pretreated by a pretreatment unit and then enters the feed tank; the second control valve and circulation pump are opened to charge the solution wastewater into the cold side of the first heat exchanger; the refrigerant in the heat pump system absorbs heat energy generated by photovoltaic panels in the evaporation coil of the PVT evaporator and evaporates into high-temperature, low-pressure steam, which then enters the first compressor through a gas-liquid separator for compression, heating, and pressurization, becoming high-temperature, high-pressure steam, and then enters the hot side of the first heat exchanger to exchange heat with the wastewater. After releasing heat, it is throttled by a throttling valve to become a low-temperature, low-pressure liquid. The heated wastewater then enters the tube side of the vacuum membrane distillation module.

[0014] The vacuum pump is turned on to evacuate the shell side of the vacuum membrane distillation assembly, creating a certain vapor pressure difference between the tube side and shell side membrane surfaces. Water molecules in the bulk solution in the tube side of the vacuum membrane distillation assembly reach the membrane surface and evaporate. Driven by the vapor pressure difference across the membrane, they reach the shell side and then enter the second compressor for compression, heating, and pressurization. The high-temperature, high-pressure vapor after compression exchanges heat with the concentrate from the vacuum membrane distillation assembly and finally condenses into liquid water, which is collected in the condensate tank. The concentrate is returned to the feed tank for continued circulation and concentration until the required concentration is reached, at which point it is recycled.

[0015] The PVT evaporator absorbs solar energy to generate electricity, which is then converted into AC power by a photovoltaic inverter. This AC power is stored in a battery and used to drive the circulating pump, the first compressor, the second compressor, the vacuum pump, and output to the power grid.

[0016] The working method of the PVT heat pump vacuum membrane distillation wastewater treatment system is characterized by the following: the main impurities in the industrial wastewater include suspended particles, organic matter, and heavy metal ions. The pretreatment process of the industrial wastewater in the pretreatment unit is as follows: the industrial wastewater first passes through an equalization tank to adjust the circulation volume and pH value; secondly, suspended particles are removed in a filtration tank using sand filtration, filter cloth, or CN filter; thirdly, organic matter is removed by oxidizing and decomposing it using oxidants such as hydrogen peroxide; and finally, heavy metal ions are removed by chemical precipitation or electrochemical methods using alkaline reagents, thereby turning the industrial wastewater into a dilute solution.

[0017] The working method of the PVT heat pump vacuum membrane distillation wastewater treatment system is characterized by:

[0018] When solar radiation is good, the PVT heat pump system is used to preheat the wastewater with the heat energy generated by photovoltaic power generation. Then, a small amount of electricity is used to drive the second compressor to recover the latent heat of secondary vapor in the vacuum membrane distillation process of the wastewater, providing a heat source for the evaporation of the wastewater.

[0019] When solar radiation is weak, the second compressor is driven by the electrical energy stored in the battery. The wastewater is concentrated by evaporating the latent heat of the secondary steam in the vacuum membrane distillation process. The whole process does not require an external heat source, and the energy saving effect is very significant.

[0020] The working method of the PVT heat pump vacuum membrane distillation wastewater treatment system is characterized in that: the heat energy generated by the photovoltaic panel in the PVT evaporator is exchanged with the refrigerant in the evaporation coil, which on the one hand causes the refrigerant to evaporate, and on the other hand reduces the temperature of the photovoltaic panel, thereby improving the power generation efficiency.

[0021] This invention makes full use of photovoltaic photothermal energy and latent heat of secondary steam to meet the energy demand in the vacuum membrane distillation wastewater treatment process. It has the advantages of high energy utilization efficiency, low operating cost and strong operational stability, and is suitable for industrial heating, wastewater treatment and other fields. Attached Figure Description

[0022] Figure 1 This utility model proposes a PVT heat pump vacuum membrane distillation wastewater treatment system and method; Figure 2 This is a pretreatment process for industrial wastewater.

[0023] The following are the labels in the diagram: 1 Pretreatment Unit, 2-1 First Control Valve, 2-2 Second Control Valve, 2-3 Third Control Valve, 2-4 Fourth Control Valve, 2-5 Fifth Control Valve, 3 Feed Tank, 4 Circulation Pump, 5 Throttling Valve, 6 PVT Evaporator, 7 Battery, 8 Photovoltaic Inverter Unit, 9 Gas-Liquid Separator, 10-1 First Compressor, 10-2 Second Compressor, 11-1 First Heat Exchanger, 11-2 Second Heat Exchanger, 12 Vacuum Membrane Distillation Module, 13 Condensate Tank, 14 Vacuum Pump. Detailed Implementation

[0024] Figure 1 This utility model proposes a PVT heat pump vacuum membrane distillation wastewater treatment system and method. Figure 2 This is the industrial wastewater pretreatment process, see below for reference. Figure 1 and 2 Describe the specific working process of this technology.

[0025] The working process of this device is as follows: Industrial wastewater mainly includes suspended particles, organic matter, and heavy metal ions. It first passes through a pretreatment unit to become a dilute solution, and then enters a PVT heat pump vacuum membrane distillation system for evaporation and concentration. During the pretreatment process, the industrial wastewater first passes through an equalization tank to adjust the circulation rate and pH value; secondly, suspended particles are removed in a filtration tank using sand filtration, filter cloth, or CN filter; thirdly, organic matter is removed through oxidative decomposition using oxidants such as hydrogen peroxide; finally, heavy metal ions are removed using alkaline reagents via chemical precipitation or electrochemical methods, thus turning the industrial wastewater into a dilute solution, which is then stored in the feed tank 3. The second control valve 2-2 and the circulation pump 4 are opened to charge the wastewater solution into the cold side of the first heat exchanger 11-1. The refrigerant in the heat pump system absorbs heat energy generated by the photovoltaic panels in the evaporation coil of the PVT evaporator 6, evaporating into high-temperature, low-pressure steam. This steam then passes through the gas-liquid separator 9 and enters the first compressor 10-1 for compression, heating, and pressurization, becoming high-temperature, high-pressure steam. It then enters the hot side of the first heat exchanger 11-1 to exchange heat with the wastewater. After releasing heat, it is throttled by the expansion valve 5 to become a low-temperature, low-pressure liquid. The heated wastewater then enters the tube side of the vacuum membrane distillation module 12. The vacuum pump is activated to create a vacuum in the shell side of the vacuum membrane distillation assembly 12, resulting in a vapor pressure difference between the tube side and shell side membrane surfaces. Water molecules in the bulk solution in the tube side of the assembly evaporate at the membrane surface and, driven by the vapor pressure difference across the membrane, reach the shell side, where they enter the second compressor 10-2 for compression, heating, and pressurization. The compressed high-temperature, high-pressure vapor exchanges heat with the concentrate from the vacuum membrane distillation assembly 12, eventually condensing into liquid water and collecting it in the condensate tank 13. The concentrate is returned to the feed tank 3 for continued circulation and concentration until the required concentration is reached, at which point it is recycled. The PVT evaporator 6 absorbs solar energy, which is then processed by the photovoltaic inverter 8. The DC power is stored in the battery 7 and converted into AC power to drive the circulation pump 4, the first compressor 10-1, the second compressor 10-2, the vacuum pump 14, and output to the power grid.

[0026] Although the specific implementation process of this utility model has been described in detail above with reference to the accompanying drawings, this does not limit this utility model. Those skilled in the art should understand that all changes and improvements made within the spirit and principles of this utility model and under its guidance are within the protection scope of this utility model.

Claims

1. A PVT heat pump vacuum membrane distillation wastewater treatment system, characterized in that Mainly includes: Pretreatment unit (1), first control valve (2-1), second control valve (2-2), third control valve (2-3), fourth control valve (2-4), fifth control valve (2-5), feed water tank (3), circulating pump (4), throttle valve (5), PVT evaporator (6), storage battery (7), photovoltaic inverter integrated machine (8), gas-liquid separator (9), first compressor (10-1), second compressor (10-2), first heat exchanger (11-1), second heat exchanger (11-2), vacuum membrane distillation assembly (12), condensate tank (13), vacuum pump (14); The pretreatment unit (1) is connected to the inlet of the feed tank (3) via the first control valve (2-1). The outlet of the feed tank (3) is connected to the inlet of the circulating pump (4) via the second control valve (2-2). The outlet of the circulating pump (4) is connected to the cold side inlet of the first heat exchanger (11-1). The cold side outlet of the first heat exchanger (11-1) is connected to the inlet of the vacuum membrane distillation assembly (12). The steam outlet of the vacuum membrane distillation assembly (12) is connected to the inlet of the second compressor (10-2). The outlet of the second compressor (10-2) is connected to the hot side inlet of the second heat exchanger (11-2), the hot side outlet of the second heat exchanger (11-2) is connected to the top inlet of the condensate tank (13), the top outlet of the condensate tank (13) is connected to the vacuum pump (14) via the fifth control valve (2-5), the solution outlet of the vacuum membrane distillation assembly (12) is connected to the cold side inlet of the second heat exchanger (11-2), and the cold side outlet of the second heat exchanger (11-2) is connected to the top inlet of the feed water tank (3). The hot-side outlet of the first heat exchanger (11-1) is connected to the throttle valve (5), and then connected to the inlet of the evaporation coil in the PVT evaporator (6) via the third control valve (2-3). The outlet of the evaporation coil in the PVT evaporator (6) is connected to the left inlet of the gas-liquid separator (9). The top outlet of the gas-liquid separator (9) is connected to the inlet of the first compressor (10-1). The outlet of the first compressor (10-1) is connected to the hot-side inlet of the first heat exchanger (11-1). The bottom outlet of the gas-liquid separator (9) is connected to the fourth control valve (2-4). The photovoltaic inverter (8) is connected to the battery (7) and the PVT evaporator (6) respectively.

2. The PVT heat pump vacuum membrane distillation wastewater treatment system of claim 1, wherein: The PVT evaporator (6) consists of a glass cover plate, EVA film, photovoltaic panel, aluminum back plate, and evaporation coil.

3. The PVT heat pump vacuum membrane distillation wastewater treatment system of claim 1, wherein: The vacuum membrane distillation assembly (12) is composed of multiple hollow fiber membrane filaments. Each membrane filament is made of polytetrafluoroethylene hydrophobic evaporation membrane with a pore size of less than 0.2 μm and a porosity of 20%-85%.

4. The PVT heat pump vacuum membrane distillation wastewater treatment system of claim 1, wherein: The working fluid used in the above heat pump system is R134a, or R22, or R123, or R410A.

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