Vacuum membrane distillation wastewater treatment system driven by combined photothermal-heat pump

Abstract

A kind of vacuum membrane distillation wastewater treatment system of photo-heat-heat pump combined drive belongs to energy saving and environmental protection field.The system includes two groups of water tank, condenser, vacuum membrane distillation component, double compressor, multi-stream heat exchanger, evaporator, solar collector and the like.The first water tank forms circulation loop through control valve, circulating pump, condenser cold side, solar collector, multi-stream heat exchanger first pipe passage.The second water tank is connected in sequence control valve, circulating pump, vacuum membrane distillation component, first compressor, multi-stream heat exchanger second pipe passage, evaporator hot side, condenser, control valve, vacuum pump.The evaporator cold side outlet returns to evaporator cold side inlet through second compressor, condenser hot side, throttle valve.The vacuum membrane distillation component solution outlet is connected with multi-stream heat exchanger shell side inlet, and shell side outlet is connected with second water tank inlet.The system combines solar heat utilization technology, heat pump technology and vacuum membrane distillation technology, efficiently and at low cost meets the demand of industrial wastewater treatment.

Description

Technical Field

[0001] This utility model patent relates to a vacuum membrane distillation wastewater treatment system and method driven by a combination of solar thermal and heat pump, which belongs to the field of energy conservation and environmental protection. Background Technology

[0002] With the increasing severity of global water scarcity and environmental pollution, the recycling and efficient treatment of industrial wastewater has become a key focus for governments and businesses worldwide. Currently, industrial wastewater treatment methods mainly include neutralization, chemical oxidation, pyrolysis, evaporation, biological methods, and membrane methods, all of which generally suffer from low separation efficiency, high energy consumption, and poor operational stability. Therefore, there is an urgent need to develop a new and efficient industrial wastewater treatment method to achieve the sustainable use of water resources.

[0003] Vacuum membrane distillation is a novel membrane separation technology that combines the advantages of traditional distillation and membrane technology. It is primarily used in fields such as high-salinity wastewater treatment, seawater desalination, and medical technology. Its core principle is to use a hydrophobic microporous membrane as a barrier, employing a vacuum pump to create a negative pressure environment downstream of the membrane. Driven by the vapor pressure difference across the hydrophobic microporous membrane, liquid water molecules in the solution evaporate at the membrane surface and permeate through the membrane pores, achieving efficient separation. However, existing vacuum membrane distillation systems fail to effectively utilize internal energy, resulting in enormous evaporation energy consumption, which limits its further industrial application.

[0004] Solar energy is a clean and renewable energy source, and its utilization technologies are mainly divided into three categories: photothermal conversion, photovoltaic conversion, and photochemical conversion. Among these, photothermal conversion is the primary utilization technology. A heat pump system is an energy-efficient device that utilizes the reverse Carnot cycle principle to transfer heat from a low-temperature heat source to a high-temperature side by consuming a small amount of electrical or thermal energy. Currently, solar thermal utilization technology and heat pump technology have been widely applied in my country, but research on their application in the vacuum membrane distillation process for industrial wastewater treatment is limited. Therefore, combining solar thermal utilization technology, heat pump technology, and vacuum membrane distillation technology to efficiently and cost-effectively meet the needs of industrial wastewater treatment and achieve zero discharge and resource utilization is of great significance. Summary of the Invention

[0005] This invention proposes a vacuum membrane distillation wastewater treatment system and method with low energy consumption and high stability, driven by a combination of solar thermal and heat pump.

[0006] The aforementioned vacuum membrane distillation wastewater treatment system driven by a combination of solar thermal and heat pump is characterized by mainly comprising: a first feed tank, a second feed tank, a first control valve, a second control valve, a third control valve, a fourth control valve, a first circulation pump, a second circulation pump, a condenser, a vacuum pump, a condensate tank, a vacuum membrane distillation assembly, a first compressor, a second compressor, a multi-stream heat exchanger, an evaporator, a solar collector, and a throttling valve; The first feed tank is connected to the inlet of the first circulating pump via the first control valve. The outlet of the first circulating pump is connected to the cold side inlet of the condenser. The cold side outlet of the condenser is connected to the inlet of the solar collector. The outlet of the solar collector is connected to the inlet of the first tube side of the multi-stream heat exchanger. The outlet of the first tube side of the multi-stream heat exchanger is connected to the inlet of the first feed tank. The outlet of the second feed tank is connected to the inlet of the second circulating pump via a second control valve. The outlet of the second circulating pump 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 first compressor. The outlet of the first compressor is connected to the inlet of the second tube side of the multi-stream heat exchanger. The outlet of the second tube side of the multi-stream heat exchanger is connected to the hot-side inlet of the evaporator. The hot-side outlet of the evaporator is connected to the inlet of the condensate tank. The outlet of the condensate tank is connected to the vacuum pump via a fourth control valve. The cold-side outlet of the evaporator is connected to the inlet of the second compressor. The outlet of the second compressor is connected to the hot-side inlet of the condenser. The hot-side outlet of the condenser is connected to the inlet of the throttle valve. The outlet of the throttle valve is connected to the cold-side inlet of the evaporator. The solution outlet of the vacuum membrane distillation assembly is connected to the shell-side inlet of the multi-stream heat exchanger. The shell-side outlet of the multi-stream heat exchanger is connected to the inlet of the second feed tank.

[0007] The working method of the vacuum membrane distillation wastewater treatment system driven by a combination of solar thermal and heat pump is characterized by the following process: storing softened water in a first feed tank and storing pretreated industrial wastewater in a second feed tank. On one hand, industrial wastewater enters the vacuum membrane distillation unit for evaporation and concentration via the second control valve and the second circulation pump. The resulting concentrate enters the multi-stream heat exchanger to absorb heat, and after its temperature is raised, it returns to the first feed tank for continued circulation and concentration until the required concentration is reached and then recycled. The resulting secondary steam enters the first compressor for compression, heating, and pressurization to increase its enthalpy value. It then enters the multi-stream heat exchanger to heat the concentrate. After releasing heat, it enters the evaporator in the heat pump system to heat the refrigerant, eventually becoming low-temperature, low-pressure fresh water collected in the condensate tank. Meanwhile, the refrigerant absorbs heat and evaporates, entering the second compressor for compression into high-temperature, high-pressure steam. It then enters the condenser to heat the softened water, and after being throttled and depressurized by the throttling valve, it enters the evaporator for continued circulation and evaporation. On the other hand, the softened water enters the condenser to absorb heat via the first control valve and the first circulation pump. It then enters the solar collector array to absorb heat again, further raising its temperature. It then enters the multi-stream heat exchanger to heat the concentrate, and after releasing heat, it returns to the first feed tank.

[0008] The aforementioned vacuum membrane distillation wastewater treatment system driven by a combination of photothermal and heat pump 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 0.1-0.45μm and a porosity of 20%-85%, and each vacuum membrane distillation component can be connected in parallel.

[0009] The aforementioned vacuum membrane distillation wastewater treatment system driven by a combination of photothermal and heat pump is characterized in that the working fluid used in the heat pump system is R134a, or R22, or R123, or R142b, or R410A.

[0010] The aforementioned vacuum membrane distillation wastewater treatment system driven by a combination of solar thermal and heat pump is characterized in that: the first compressor is a steam compressor, mainly including centrifugal, Roots, and screw types. Beneficial effects

[0011] 1. The vacuum membrane distillation wastewater treatment system driven by a combination of photothermal and heat pump, characterized in that: the multi-stream heat exchanger contains three fluids: high-temperature steam, high-temperature liquid water, and concentrate, and the fluids exchange heat through isolated flow channels.

[0012] 2. The entire system utilizes heat pump technology, solar thermal technology, and steam mechanical recompression technology, combined with a multi-stream heat exchanger, to continuously, stably, and efficiently provide energy for the vacuum membrane distillation and evaporation process of industrial wastewater. This saves on external heat sources and cooling water, and fully recovers and utilizes solar energy, latent heat of steam within the system, and waste heat, achieving highly efficient and energy-saving separation and purification of industrial wastewater.

[0013] 3. By utilizing heat pump technology and multi-stream heat exchangers, the solar thermal and secondary steam latent heat are fully utilized to meet the energy requirements of 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

[0014] Figure 1 This utility model proposes a vacuum membrane distillation wastewater treatment system and method driven by a combination of photothermal and heat pump. The labels in the diagram are as follows: 1-1 First feed water tank, 1-2 Second feed water tank, 2-1 First control valve, 2-2 Second control valve, 2-3 Third control valve, 2-4 Fourth control valve, 3-1 First circulation pump, 3-2 Second circulation pump, 4 Condenser, 5 Vacuum pump, 6 Condensate tank, 7 Vacuum membrane distillation assembly, 8-1 First compressor, 8-2 Second compressor, 9 Multi-stream heat exchanger, 10 Evaporator, 11 Solar collector, 12 Throttling valve. Detailed Implementation

[0015] Figure 1 This utility model proposes a vacuum membrane distillation wastewater treatment system and method driven by a combination of solar thermal and heat pump, as described below. Figure 1 Describe the specific working process of this technology.

[0016] The device operates as follows: Softened water is stored in the first feed tank 1-1, and pretreated industrial wastewater is stored in the second feed tank 1-2. On one hand, the industrial wastewater enters the vacuum membrane distillation assembly 7 via the second control valve 2-2 and the second circulation pump 3-2 for evaporation and concentration. The resulting concentrate enters the multi-stream heat exchanger 9 to absorb heat, and after its temperature is raised, it returns to the first feed tank 1-2 for further circulation and concentration until the required concentration is reached, at which point it is recycled. The resulting secondary steam enters the first compressor 8-1 for compression, heating, and pressurization to increase its enthalpy value. It then enters the multi-stream heat exchanger 9 to heat the concentrate. After releasing heat, it enters the evaporator 10 in the heat pump system to heat the refrigerant, ultimately becoming a low-temperature, low-pressure desalinated liquid. Water is collected in the condensate tank 6, while the refrigerant absorbs heat and evaporates, entering the second compressor 8-2 to be compressed into high-temperature and high-pressure steam, which then enters the condenser 4 to heat and soften the water. After being throttled and depressurized by the expansion valve, it enters the evaporator to continue circulating and evaporating. On the other hand, the softened water enters the condenser 4 through the first control valve 2-1 and the first circulation pump 3-1 to absorb heat, and then enters the solar collector array 11 to absorb heat again, further increasing its temperature. It then enters the multi-stream heat exchanger 9 to heat the concentrate, and after releasing heat, it returns to the first feed water tank 1-1.

[0017] 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 photothermal-heat pump combined driving vacuum membrane distillation wastewater treatment system, characterized in that Mainly includes: First feed water tank (1-1), second feed water tank (1-2), first control valve (2-1), second control valve (2-2), third control valve (2-3), fourth control valve (2-4), first circulation pump (3-1), second circulation pump (3-2), condenser (4), vacuum pump (5), condensate tank (6), vacuum membrane distillation assembly (7), first compressor (8-1), second compressor (8-2), multi-stream heat exchanger (9), evaporator (10), solar collector (11), throttle valve (12); The first feed tank (1-1) is connected to the inlet of the first circulating pump (3-1) via the first control valve (2-1). The outlet of the first circulating pump (3-1) is connected to the cold side inlet of the condenser (4). The cold side outlet of the condenser (4) is connected to the inlet of the solar collector (11). The outlet of the solar collector (11) is connected to the inlet of the first tube side of the multi-stream heat exchanger (9). The outlet of the first tube side of the multi-stream heat exchanger (9) is connected to the inlet of the first feed tank (1-1). The outlet of the second feed tank (1-2) is connected to the inlet of the second circulating pump (3-2) via the second control valve (2-2). The outlet of the second circulating pump (3-2) is connected to the inlet of the vacuum membrane distillation assembly (7). The steam outlet of the vacuum membrane distillation assembly (7) is connected to the inlet of the first compressor (8-1). The outlet of the first compressor (8-1) is connected to the inlet of the second tube side of the multi-stream heat exchanger (9). The outlet of the second tube side of the multi-stream heat exchanger (9) is connected to the hot-side inlet of the evaporator (10). The hot-side outlet of the evaporator (10) is connected to the inlet of the condensate tank (6). The outlet of the tank (6) is connected to the vacuum pump (5) via the fourth control valve (2-4); the cold side outlet of the evaporator (10) is connected to the inlet of the second compressor (8-2), the outlet of the second compressor (8-2) is connected to the hot side inlet of the condenser (4), the hot side outlet of the condenser (4) is connected to the inlet of the throttle valve (12), and the outlet of the throttle valve (12) is connected to the cold side inlet of the evaporator (10); the solution outlet of the vacuum membrane distillation assembly (7) is connected to the shell-side inlet of the multi-stream heat exchanger (9), and the shell-side outlet of the multi-stream heat exchanger (9) is connected to the inlet of the second feed water tank (1-2).

2. The combined photothermal-heat pump driven vacuum membrane distillation wastewater treatment system according to claim 1, characterized in that: The vacuum membrane distillation assembly (7) is composed of multiple hollow fiber membrane filaments. Each membrane filament is made of polytetrafluoroethylene hydrophobic evaporation membrane with a pore size of 0.1-0.45μm and a porosity of 20%-85%. Each vacuum membrane distillation assembly can be connected in parallel.

3. The combined photothermal-heat pump driven vacuum membrane distillation wastewater treatment system according to claim 1, characterized in that: The first compressor (8-1) mentioned above is a steam compressor, specifically including centrifugal, Roots and screw types.

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