CN116062838A - Device and method for treating waste liquid by membrane distillation - Google Patents

Device and method for treating waste liquid by membrane distillation Download PDF

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Publication number
CN116062838A
CN116062838A CN202211691395.5A CN202211691395A CN116062838A CN 116062838 A CN116062838 A CN 116062838A CN 202211691395 A CN202211691395 A CN 202211691395A CN 116062838 A CN116062838 A CN 116062838A
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China
Prior art keywords
waste liquid
membrane distillation
outlet
liquid
heat exchanger
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CN202211691395.5A
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Chinese (zh)
Inventor
杨涵
张兴娟
刘致君
杨春信
王超
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Beihang University
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Beihang University
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Priority to CN202211691395.5A priority Critical patent/CN116062838A/en
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/447—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by membrane distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0039—Recuperation of heat, e.g. use of heat pump(s), compression
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
    • B01D5/009—Collecting, removing and/or treatment of the condensate
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2303/00—Specific treatment goals
    • C02F2303/10—Energy recovery
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use
    • Y02A20/124—Water desalination
    • Y02A20/131—Reverse-osmosis

Abstract

The invention relates to a device and a method for treating waste liquid by membrane distillation, wherein the device comprises a first heat exchanger, a second heat exchanger and a third heat exchanger, wherein the first heat exchanger comprises a first refrigerant pipeline with a first inlet and a first outlet and a first heat medium pipeline with a second inlet and a second outlet, and the first inlet is used for introducing waste liquid to be treated; the membrane distillation assembly comprises a membrane distillation liquid inlet, a membrane distillation liquid outlet and a steam outlet, wherein the membrane distillation liquid inlet is communicated with the first outlet, and the membrane distillation liquid outlet is used for discharging distilled waste liquid; the vacuum pump is connected in series between the steam outlet and the second inlet; and the second heat exchanger is communicated with the second outlet and is used for liquefying the steam discharged from the second outlet. The high-purity separation of the waste liquid can be ensured by the membrane distillation treatment of the waste liquid, and the steam is introduced into the first heat exchanger through the vacuum pump, so that the waste liquid to be subjected to the membrane distillation treatment in the first heat medium pipeline is heated by utilizing the latent heat of the steam, the loss of heat energy is reduced, and the energy utilization rate is improved.

Description

Device and method for treating waste liquid by membrane distillation
Technical Field
The invention relates to the technical field of water treatment devices, in particular to a device and a method for treating waste liquid by membrane distillation.
Background
Many industrial water-saving approaches gradually develop to water intake diversification, and industrial wastewater recycling, town sewage utilization and rainwater collection and utilization become important means for heavy industrial water. In order to further improve the water efficiency, recycling of the high-salt wastewater is gradually emphasized. At present, the brine recovery technology is mature, the common desalination technology comprises reverse osmosis, multistage evaporation, multi-effect distillation and the like, and the comprehensive technologies such as thermal film coupling, water cogeneration and the like are rapidly developed along with the scale expansion and the integration degree improvement of wastewater treatment.
In recent years, membrane distillation techniques have been proposed and various researches have been made on the basis of thermal distillation and membrane separation. Because of its excellent separation performance and low operating temperature and pressure, membrane distillation technology has been applied in many fields such as sea water desalination, wastewater treatment, food processing and pharmaceutical.
Among them, the treatment of radioactive wastewater in nuclear industry by membrane method is a development trend. Uranium enrichment factory can produce a large amount of uranium-bearing waste water, and uranium is a natural radioactive substance, has very strong chemical toxicity, and can harm metabolic organs, viscera mucous membrane, destroy acid-base balance in blood etc. entering the human body, fluorine element can produce destructive effect to skeleton, thyroid gland etc. after entering the human body. Therefore, the uranium-containing wastewater is treated, so that the uranium element and fluorine element content in the wastewater can reach the national discharge standard before being discharged. The membrane distillation technology shows good performance in uranium-containing wastewater treatment, and the rejection rate of uranium elements is more than 99%. By utilizing the membrane distillation technology, the uranium-containing wastewater can be subjected to reduction treatment, so that chemical substances which need to be added when uranium elements and fluorine elements are removed in the later stage are reduced, and the production of radioactive solid wastes can be effectively reduced.
The basic principle of membrane distillation is that a porous hydrophobic membrane is used as a medium for gas-liquid separation, only gas-phase substances in the porous hydrophobic membrane are allowed to pass through, the transmembrane driving force is the air pressure difference on two sides of the membrane, only substances capable of evaporating can be pushed to permeate the membrane, and non-volatile substances can be blocked by the membrane. Membrane distillation can be divided into the following four types according to different condensation methods: direct contact membrane distillation, air gap membrane distillation, vacuum membrane distillation, and air-swept membrane distillation.
In which, as shown in fig. 1, the hot feed liquid is subjected to membrane distillation treatment by a membrane module 100 to generate a liquid and steam after membrane distillation, a vacuum pump 300 introduces the steam into a condenser 200 by pumping, and the steam is condensed and liquefied by the condenser 200 to generate production water, and finally discharged. There is a worldwide concern due to the large driving force and membrane flux created by the application of a vacuum environment on the permeate side. It provides a simple and effective method for brine or wastewater treatment, but the phase change process in the membrane distillation process reduces the utilization rate of heat energy if the latent heat of fresh water vapor cannot be utilized.
Therefore, the recovery and utilization of the latent heat of the steam are considered in the design of the system, so that the loss of heat energy is reduced as much as possible, the energy utilization rate is improved, and the membrane distillation is more practical compared with other treatment technologies.
Disclosure of Invention
The invention aims to provide a device and a method for treating waste liquid by membrane distillation, which can fully utilize latent heat of steam, reduce loss of heat energy and improve energy utilization rate on the premise of ensuring high-purity separation.
To achieve the purpose, the invention adopts the following technical scheme:
a first aspect of the present application provides an apparatus for treating waste liquid by membrane distillation, comprising:
the first heat exchanger comprises a first refrigerant pipeline with a first inlet and a first outlet and a first heat medium pipeline with a second inlet and a second outlet, wherein the first inlet is used for introducing waste liquid to be treated;
the membrane distillation assembly comprises a membrane distillation liquid inlet, a membrane distillation liquid outlet and a steam outlet, wherein the membrane distillation liquid inlet is communicated with the first outlet, and the membrane distillation liquid outlet is used for discharging distilled waste liquid;
the vacuum pump is connected in series between the steam outlet and the second inlet;
and the second heat exchanger is communicated with the second outlet and is used for liquefying the steam discharged from the second outlet.
In some embodiments, the apparatus for treating waste liquid by membrane distillation further comprises:
a waste liquid container, a waste liquid outlet of which is communicated with the first inlet, for providing a waste liquid to be treated.
In some embodiments, the apparatus for treating waste liquid by membrane distillation further comprises:
the heater is arranged in the waste liquid container and is used for heating waste liquid to be treated; and/or the number of the groups of groups,
the first delivery pump is connected in series between the waste liquid outlet and the first inlet.
In some embodiments, the membrane distillation liquid outlet is in communication with a liquid inlet of the waste container.
In some embodiments, the apparatus for treating waste liquid by membrane distillation further comprises:
and the liquid inlet of the liquid storage container is communicated with the outlet of the second heat exchanger.
In some embodiments, the apparatus for treating waste liquid by membrane distillation further comprises:
the second delivery pump is connected in series between the second heat exchanger and the liquid storage container.
In some embodiments, the second heat exchanger is an air-cooled heat sink.
In some embodiments, the first heat exchanger and/or the second heat exchanger are structured as plate structures forming a plate heat exchanger.
A second aspect of the present application provides a method for treating waste liquid by membrane distillation, using the apparatus for treating waste liquid by membrane distillation, the method for treating waste liquid by membrane distillation comprising:
performing vacuum membrane distillation on the waste liquid to be treated through the membrane distillation assembly;
inputting steam obtained by vacuum membrane distillation into the first heat medium pipeline through the compressed air of the vacuum pump so as to preheat waste liquid to be treated flowing through the first refrigerant pipeline;
and inputting the steam and liquid water discharged from the first refrigerant pipeline into the second heat exchanger so as to liquefy the steam discharged from the first refrigerant pipeline.
In some embodiments, the apparatus for membrane distillation treatment of waste liquid further comprises a waste liquid container, a waste liquid outlet of the waste liquid container being in communication with the first inlet for providing waste liquid to be treated, the membrane distillation liquid outlet being in communication with a liquid inlet of the waste liquid container, the membrane distillation treatment method further comprising delivering distilled waste liquid discharged from the membrane distillation liquid outlet to the waste liquid container to form a closed loop; and/or the number of the groups of groups,
in the step of inputting the steam and the liquid water discharged from the first refrigerant pipeline into the second heat exchanger for liquefying the steam discharged from the first refrigerant pipeline, the second heat exchanger is an air-cooled radiator for liquefying the steam discharged from the first refrigerant pipeline through air-cooled heat radiation.
The invention has the beneficial effects that:
compared with a vacuum membrane distillation system in the related art, the device and the method for treating the waste liquid by membrane distillation have the advantages that on one hand, the waste liquid is treated by membrane distillation by a membrane distillation group, so that the high-purity separation of the waste liquid can be ensured; on the other hand, the steam generated by the membrane distillation treatment is introduced into the first heat exchanger through the vacuum pump, so that the latent heat of the steam is utilized to heat the waste liquid to be subjected to the membrane distillation treatment flowing through the first heat medium pipeline, the high-efficiency utilization of the latent heat of the steam is realized, the loss of heat energy is reduced, and the energy utilization rate is improved; in still another aspect, the second heat exchanger further releases latent heat of vapor or sensible heat of condensed water which is liquefied, so that low-temperature condensed water with reduced temperature can be obtained for subsequent other use or storage, and recovery of condensed water is realized.
Drawings
FIG. 1 is a schematic diagram of a vacuum membrane distillation system of the related art;
FIG. 2 is a schematic diagram of an apparatus for treating waste liquid by membrane distillation in some embodiments provided herein;
FIG. 3 is a schematic diagram of an apparatus for treating waste liquid by membrane distillation in other embodiments provided by the present invention;
FIG. 4 is a schematic diagram of an apparatus for treating waste liquid by membrane distillation in still other embodiments provided by the present invention;
FIG. 5 is a schematic illustration of the steps of a method of treating waste liquid by membrane distillation in some embodiments of the invention.
In the figure:
100. a membrane module; 200. a condenser; 300. a vacuum pump;
1. a first heat exchanger; 11. a first inlet; 12. a first outlet; 13. a second inlet; 14. a second outlet;
2. a membrane distillation group; 21. a membrane distillation liquid inlet; 22. a membrane distillation liquid outlet; 23. a steam outlet;
3. a vacuum pump;
4. a second heat exchanger; 41. a third inlet; 42. a third outlet; 43. a fourth inlet; 44. a fourth outlet;
5. a waste liquid container; 6. a heater; 7. a first transfer pump; 8. a liquid storage container; 9. a second transfer pump;
10. a third heat exchanger; 101. a fifth inlet; 102. a fifth outlet; 103. a sixth inlet; 104. a sixth outlet;
15. and a third transfer pump.
Detailed Description
In order to make the technical problems solved, the technical scheme adopted and the technical effects achieved by the invention more clear, the technical scheme of the invention is further described below by a specific embodiment in combination with the attached drawings.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like are orientation or positional relationships based on those shown in the drawings, and are merely for convenience of description and simplicity of operation, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the invention. Furthermore, the terms "first," "second," and the like, are used merely for distinguishing between descriptions and not for distinguishing between them.
At present, the technology for recovering the brine at home and abroad is mature, the common desalination technology comprises reverse osmosis, multistage evaporation, multi-effect distillation and the like, and the comprehensive technologies such as thermal film coupling, water-electricity cogeneration and the like are rapidly developed along with the expansion of the wastewater treatment scale and the improvement of the integration degree.
In recent years, membrane distillation techniques have been proposed and various researches have been made on the basis of thermal distillation and membrane separation. The basic principle of membrane distillation is that a porous hydrophobic membrane is used as a medium for gas-liquid separation, only gas-phase substances in the porous hydrophobic membrane are allowed to pass through, the transmembrane driving force is the air pressure difference on two sides of the membrane, only substances capable of evaporating can be pushed to permeate the membrane, and non-volatile substances can be blocked by the membrane. Because of its excellent separation performance and low operating temperature and pressure, membrane distillation technology has been applied in many fields such as sea water desalination, wastewater treatment, food processing and pharmaceutical.
The use of membrane processes for the treatment of radioactive waste water from the nuclear industry is a growing trend. Uranium enrichment factory can produce a large amount of uranium-bearing waste water, and uranium is a natural radioactive substance, has very strong chemical toxicity, and can harm metabolic organs, viscera mucous membrane, destroy acid-base balance in blood etc. entering the human body, fluorine element can produce destructive effect to skeleton, thyroid gland etc. after entering the human body. Therefore, the uranium-containing wastewater is treated, so that the uranium element and fluorine element content in the wastewater can reach the national discharge standard before being discharged. The membrane distillation technology shows good performance in uranium-containing wastewater treatment, and the rejection rate of uranium elements is more than 99%. By utilizing the membrane distillation technology, the uranium-containing wastewater can be subjected to reduction treatment, so that chemical substances which need to be added when uranium elements and fluorine elements are removed in the later stage are reduced, and the production of radioactive solid wastes can be effectively reduced.
In general, membrane distillation can be classified into the following four types according to different condensation methods: direct contact membrane distillation, air gap membrane distillation, vacuum membrane distillation, and air-swept membrane distillation. Wherein, a schematic diagram of a vacuum membrane distillation system in the related art is shown in fig. 1. The hot feed liquid is subjected to membrane distillation treatment by the membrane module 100 to generate liquid and steam after membrane distillation, the vacuum pump 300 introduces the steam into the condenser 200 by pumping air, and the steam is condensed and liquefied by the condenser 200 to generate production water and finally discharged. There is a worldwide concern due to the large driving force and membrane flux created by the application of a vacuum environment on the permeate side. It provides a simple and effective method for brine or wastewater treatment, but the phase change process in the membrane distillation process reduces the utilization rate of heat energy if the latent heat of fresh water vapor cannot be utilized. Specifically, the hot feed liquid may be concentrated sulfuric acid waste liquid to be treated, or the like.
Therefore, in the design of the system, the recovery and utilization of the latent heat of the steam are considered, so that the loss of heat energy is reduced as much as possible, the energy utilization rate is improved, and the membrane distillation is more practical compared with other treatment technologies.
In view of the above problems, referring to fig. 2, in some embodiments of the present application, an apparatus for treating waste liquid, i.e., wastewater, by membrane distillation is provided. The device for treating waste liquid by membrane distillation comprises a first heat exchanger 1, a membrane distillation assembly 2, a vacuum pump 3 and a second heat exchanger 4. The first heat exchanger 1 comprises a first refrigerant line with a first inlet 11 and a first outlet 12, a first heating medium line with a second inlet 13 and a second outlet 14, the first inlet 11 being for letting in waste liquid to be treated; the first refrigerant pipeline and the first heat medium pipeline are mutually arranged at intervals, so that heat exchange can be performed. The membrane distillation assembly 2 comprises a membrane distillation liquid inlet 21, a membrane distillation liquid outlet 22 and a steam outlet 23, wherein the membrane distillation liquid inlet 21 is communicated with the first outlet 12, and the membrane distillation liquid outlet 22 is used for discharging distilled waste liquid; the internal structure of the membrane distillation assembly 2 is in the prior art, and details thereof are not described herein. A vacuum pump 3 is connected in series between the steam outlet 23 and the second inlet 13 for providing a compressive suction force for compressing and sucking the steam in the membrane distillation assembly 2 to the first heat exchanger 1; while the second heat exchanger 4 is in communication with the second outlet 14, the second heat exchanger 4 is configured to liquefy the vapor discharged from the second outlet 14, specifically, the vapor discharged from the second outlet 14 enters through the fourth inlet 43 and is discharged through the fourth outlet 44.
The apparatus for treating waste liquid by membrane distillation in the embodiment of the present application has advantages in comparison with the vacuum membrane distillation system in the related art in that: on one hand, the waste liquid is treated by membrane distillation of the membrane distillation group 2, so that the high-purity separation of the waste liquid can be ensured; on the other hand, the steam generated by the membrane distillation treatment is introduced into the first heat exchanger 1 through the vacuum pump 3, so that the latent heat of the steam is utilized to heat the waste liquid to be subjected to the membrane distillation treatment flowing through the first heat medium pipeline, the high-efficiency utilization of the latent heat of the steam is realized, the loss of heat energy is reduced, and the energy utilization rate is improved; on the other hand, the second heat exchanger 4 further releases the latent heat of vapor or the sensible heat of the generated condensed water, so that the condensed water with low temperature can be obtained for subsequent other use or storage, and the condensed water is recovered.
It should be noted that, in some embodiments, the first inlet 11 is used for introducing the waste liquid to be treated, and generally, a pumping mode may be adopted, or a communicating vessel principle is utilized to make the liquid level of the waste liquid source higher, so that the waste liquid to be treated is left to flow out by means of a liquid level difference, or other existing modes are adopted for introducing the waste liquid to be treated. The membrane distillation liquid outlet 22 is used for discharging distilled waste liquid, and the discharged distilled waste liquid can be introduced into a storage container or other pipeline systems.
Further, to provide an environment for containing waste liquid, referring to fig. 3, in some embodiments, the apparatus for membrane distillation treatment of waste liquid further comprises a waste liquid container 5. The waste outlet of the waste container 5 communicates with the first inlet 11, and the waste container 5 is adapted to provide waste to be treated.
Still further, in some embodiments, referring to fig. 3, the apparatus for treating waste liquid by membrane distillation further comprises a heater 6 and/or a first transfer pump 7. The heater 6 sets up in waste liquid container 5, and heater 6 is used for heating the waste liquid of waiting to handle, and then can carry out the preliminary heating waste liquid of waiting to handle to better satisfy subsequent membrane distillation demand. The first transfer pump 7 is connected in series between the waste liquid outlet and the first inlet 11 for pumping the waste liquid to be treated into the first heat exchanger 1.
Applicant has found that there is significant energy waste due to the fact that the effluent from the membrane distillation outlet 22 still has a certain temperature, i.e. has latent heat that is not reasonably utilized. Therefore, in order to further utilize the latent heat of the distilled waste liquid. Further, referring to fig. 3, in some embodiments, the membrane distillation liquid outlet 22 is communicated with the liquid inlet of the liquid waste container 5, that is, the distilled liquid waste flows back into the liquid waste container 5 and is mixed with the liquid waste to be treated in the liquid waste container 5, so as to form the liquid waste to be treated in a closed state, thereby realizing the recovery and utilization of latent heat of the distilled liquid waste and realizing the closed loop of the membrane distillation treatment process.
Further, referring to fig. 3, in order to be able to recover condensed water or produced water generated after the condensation of steam. The device for treating the waste liquid by membrane distillation also comprises a liquid storage container 8. The liquid inlet of the liquid storage container 8 is communicated with the outlet of the second heat exchanger 4 so as to be used for recycling condensed water or produced water generated after condensing the recovered steam.
Still further, referring to fig. 3, the apparatus for treating waste liquid by membrane distillation further comprises a second transfer pump 9: the second transfer pump 9 is connected in series between the second heat exchanger 4 and the reservoir 8 to provide power for sucking condensate water into the reservoir 8 by the second transfer pump 9. In some other embodiments, the condensed water can be introduced into the liquid storage container 8 by self-flowing, but is limited by the arrangement condition constraint of the equipment, so that the universality is poor; the use of the second transfer pump 9 for pumping allows a more flexible arrangement of the apparatus.
Further, referring to fig. 3, in some embodiments, the second heat exchanger 4 is an air-cooled radiator. The air-cooled radiator has a simple structure, adopts natural wind for cooling, does not need to arrange additional water-cooled pipelines, cold sources and conveying pumps, and has lower cost.
In the embodiment shown in fig. 3, the waste liquid to be treated is accommodated in a waste liquid container 5, which can be heated by a heater 6 at a predetermined temperature to better satisfy the subsequent membrane distillation treatment; then, the waste liquid is conveyed out through a first conveying pump 7, firstly passes through a first refrigerant pipeline of the first heat exchanger 1, then enters the membrane distillation assembly 2 for membrane distillation treatment, and finally returns to the waste liquid container 5; the steam with latent heat generated by the membrane distillation assembly 2 is compressed and pumped to the first heat medium pipeline of the first heat exchanger 1 through the vacuum pump 3, so that waste liquid to be treated in the first heat medium pipeline is subjected to heat exchange heating, the latent heat capacity recycling is realized, and finally, the steam after heat exchange or condensed water which is partially liquefied enters the second heat exchanger 4 and is subjected to further heat release, and finally flows into and is stored in the liquid storage container 8 under the pumping action of the second conveying pump 9.
In still other embodiments, referring to fig. 4, the apparatus for treating waste liquid by membrane distillation includes a first heat exchanger 1, a membrane distillation assembly 2, a vacuum pump 3, and a second heat exchanger 4, as compared to the apparatus for treating waste liquid by membrane distillation in some embodiments provided with reference to fig. 3. The first heat exchanger 1 comprises a first refrigerant line with a first inlet 11 and a first outlet 12, a first heating medium line with a second inlet 13 and a second outlet 14, the first inlet 11 being for letting in waste liquid to be treated; the first refrigerant pipeline and the first heat medium pipeline are mutually arranged at intervals, so that heat exchange can be performed. The membrane distillation assembly 2 comprises a membrane distillation liquid inlet 21, a membrane distillation liquid outlet 22 and a steam outlet 23, wherein the membrane distillation liquid inlet 21 is communicated with the first outlet 12, and the membrane distillation liquid outlet 22 is used for discharging distilled waste liquid; the internal structure of the membrane distillation assembly 2 is in the prior art, and details thereof are not described herein. A vacuum pump 3 is connected in series between the steam outlet 23 and the second inlet 13 for providing a compressive suction force for compressing and sucking the steam in the membrane distillation assembly 2 to the first heat exchanger 1; while the second heat exchanger 4 is in communication with the second outlet 14, the second heat exchanger 4 is configured to liquefy the vapor exiting the second outlet 14, in particular, by entering through the fourth inlet 43 and exiting through the fourth outlet 44.
Further, referring to fig. 4, in this embodiment, the apparatus for treating waste liquid by membrane distillation further includes a second heat exchanger 4, the second heat exchanger 4 including a second refrigerant line having a third inlet 41 and a third outlet 42, and a second heat medium line having a fourth inlet 43 and a fourth outlet 44; the second refrigerant pipeline and the second heat medium pipeline are arranged at intervals so as to exchange heat. Wherein the third inlet 41 is used for introducing waste liquid to be treated, the third outlet 42 is communicated with the first inlet 11, and the fourth inlet 43 is communicated with the second outlet 14. In this embodiment, it further uses the latent heat of the steam discharged from the second outlet 14 to heat the waste liquid to be treated flowing through the second refrigerant line, and for some embodiments in which the latent heat of the steam is not efficiently used by the first heat exchanger 1, this embodiment allows the latent heat of the steam to be further recycled.
Also, in some embodiments, to better utilize the latent heat of the effluent after distillation exiting the membrane distillation outlet 22. Referring to fig. 4, the apparatus for treating waste liquid by membrane distillation further includes a third heat exchanger 10. The third heat exchanger 10 includes a third refrigerant line having a fifth inlet 101 and a fifth outlet 102, and a third heat medium line having a sixth inlet 103 and a sixth outlet 104; the third refrigerant pipeline and the third heat medium pipeline are arranged at intervals so as to exchange heat. The fifth inlet 101 is used for introducing waste liquid to be treated, and the fifth outlet 102 is connected with the first inlet 11 in parallel so as to enable the third refrigerant pipeline to be connected with the second refrigerant pipeline; the sixth inlet 103 is communicated with the membrane distillation liquid outlet 22, and the sixth outlet 104 is used for discharging the waste liquid after heat exchange treatment, so that the latent heat of the waste liquid after distillation discharged from the membrane distillation liquid outlet 22 is further utilized in a heat exchange mode, and the energy utilization efficiency is improved.
In addition, referring to fig. 4, the apparatus for treating waste liquid by membrane distillation further includes a third transfer pump 15, and an inlet of the third transfer pump 15 communicates with a sixth outlet 104, thereby generating pumping power by the third transfer pump 15.
Still further, referring to fig. 4, the apparatus for treating waste liquid by membrane distillation further includes a first transfer pump 7 and a second transfer pump 9 provided in some embodiments as described in fig. 3. In order to provide a storage environment, the embodiment shown in fig. 4 may be further used to provide a waste liquid container 5, a heater 6 and a liquid storage container 8 according to some embodiments shown in fig. 3, which will not be described in detail.
In addition, referring to fig. 4, in some embodiments of fig. 4, the third heat exchanger 10 is designed to recycle the latent heat of the effluent discharged from the membrane distillation outlet 22 after distillation by means of heat exchange, and recycle the latent heat of the steam of the membrane distillation outlet 22 by the first heat exchanger 1 and the second heat exchanger 4, so that the energy utilization efficiency is high.
In order to improve the integration degree of the apparatus, in some embodiments, the second heat exchanger 4 and the third heat exchanger 10 may be integrally designed, that is, two heat medium pipelines are designed in one heat exchanger, one of the two heat medium pipelines is used for discharging distilled waste liquid through the membrane distillation liquid outlet 22, and the other heat medium pipeline is used for heating waste liquid to be treated in the corresponding refrigerant pipeline by steam or condensed water which is partially liquefied and has a certain latent heat discharged through the second outlet 14.
In addition, the first heat exchanger 1, the second heat exchanger 4, and the third heat exchanger 10 mentioned in all the above embodiments are unified as heat exchangers. Still further, in a respective embodiment, at least one of the first heat exchanger 1, the second heat exchanger 4, the third heat exchanger 10 may be a plate heat exchanger. The plate heat exchanger is used as a condenser instead of a shell-and-tube heat exchanger, and the above-mentioned refrigerant pipes or heat medium pipes are merely limitations on the liquid passage, and are not limited to the shell-and-tube heat exchanger. The plate heat exchanger has the advantages of small occupied area, space saving, low cost, convenient manufacture and easy cleaning.
In addition, referring to fig. 4, in some embodiments, the waste liquid after membrane distillation discharged from the third transfer pump 15 may not be mixed with the waste liquid to be treated transferred from the first transfer pump 7, that is, the closed loop type treatment system shown in fig. 3 may not be adopted, but an open loop type treatment system may be adopted, although the energy utilization efficiency may be improved. However, the problem with the single open loop treatment system like that of fig. 4 is that higher concentration requirements cannot be achieved, as compared to the closed loop treatment system of fig. 3, which can achieve more concentration requirements, the apparatus for treating waste liquid by membrane distillation of fig. 4 requires a high power heater 6 to operate the membrane distillation process during use, whereas the closed loop treatment system of fig. 3 can operate normally with a lower power heater 6.
Further, referring to fig. 1 to 5, in some embodiments of the present application, there is also provided a method of treating waste liquid by membrane distillation using the apparatus for treating waste liquid by membrane distillation in the above-described embodiments. The method for treating the waste liquid by membrane distillation comprises the following steps:
step S1, performing vacuum membrane distillation on waste liquid to be treated through a membrane distillation assembly 2;
s2, inputting steam obtained by vacuum membrane distillation into a first heat medium pipeline through air compression of a vacuum pump 3 so as to preheat waste liquid to be treated flowing through the first heat medium pipeline;
step S3, the steam and liquid water discharged from the first refrigerant pipeline are input into the second heat exchanger 4 for liquefying the steam discharged from the first refrigerant pipeline.
Further, in some embodiments, the apparatus for membrane distillation treatment of waste liquid further comprises a waste liquid container 5, the waste liquid outlet of the waste liquid container 5 is communicated with the first inlet 11 for providing waste liquid to be treated, the membrane distillation liquid outlet 22 is communicated with the liquid inlet of the waste liquid container 5, and the membrane distillation treatment method further comprises delivering distilled waste liquid discharged from the membrane distillation liquid outlet 22 to the waste liquid container 5 to form a closed loop. The beneficial effects of the closed loop refer to the corresponding implementation mode of the device for treating the waste liquid by membrane distillation, and are not repeated here.
Further, in some embodiments, in the step of inputting the vapor and liquid water discharged from the first refrigerant line into the second heat exchanger 4 for liquefying the vapor discharged from the first refrigerant line, the second heat exchanger 4 is an air-cooled radiator to liquefy the vapor discharged from the first refrigerant line by air-cooled heat radiation. The air-cooled radiator has a simple structure, adopts natural wind for cooling, does not need to arrange additional water-cooled pipelines, cold sources and conveying pumps, and has lower cost.
The foregoing is merely illustrative of the preferred embodiments of the present invention, and modifications in detail will readily occur to those skilled in the art based on the teachings herein without departing from the spirit and scope of the invention.

Claims (10)

1. A device for treating waste liquid by membrane distillation, comprising:
a first heat exchanger (1) comprising a first refrigerant line having a first inlet (11) and a first outlet (12) and a first heat medium line having a second inlet (13) and a second outlet (14), the first inlet (11) being for introducing waste liquid to be treated;
the membrane distillation assembly (2) comprises a membrane distillation liquid inlet (21), a membrane distillation liquid outlet (22) and a steam outlet (23), wherein the membrane distillation liquid inlet (21) is communicated with the first outlet (12), and the membrane distillation liquid outlet (22) is used for discharging distilled waste liquid;
a vacuum pump (3) connected in series between the steam outlet (23) and the second inlet (13);
-a second heat exchanger (4) in communication with the second outlet (14) for liquefying the steam exiting the second outlet (14).
2. The apparatus for treating waste liquid by membrane distillation according to claim 1, further comprising:
a waste liquid container (5) with a waste liquid outlet communicating with the first inlet (11) for providing waste liquid to be treated.
3. The apparatus for treating waste liquid by membrane distillation according to claim 2, further comprising:
a heater (6) provided in the waste liquid container (5) for heating waste liquid to be treated; and/or the number of the groups of groups,
and the first delivery pump (7) is connected in series between the waste liquid outlet and the first inlet (11).
4. The apparatus for treating waste liquid by membrane distillation according to claim 2, wherein said membrane distillation liquid outlet (22) is in communication with a liquid inlet of said waste liquid container (5).
5. The apparatus for treating waste liquid by membrane distillation according to claim 1, further comprising:
and the liquid inlet of the liquid storage container (8) is communicated with the outlet of the second heat exchanger (4).
6. The apparatus for treating waste liquid by membrane distillation according to claim 5, further comprising:
the second delivery pump (9) is connected in series between the second heat exchanger (4) and the liquid storage container (8).
7. The apparatus for treating waste liquid by membrane distillation according to claim 1, wherein the second heat exchanger (4) is an air-cooled radiator.
8. The device for treating waste liquid by membrane distillation according to any one of claims 1 to 7, characterized in that the structure of the first heat exchanger (1) and/or the second heat exchanger (4) is a plate structure forming a plate heat exchanger.
9. A method for treating waste liquid by membrane distillation, which is an apparatus for treating waste liquid by membrane distillation according to any one of claims 1 to 8, characterized in that the method for treating waste liquid by membrane distillation comprises:
performing vacuum membrane distillation on the waste liquid to be treated through the membrane distillation assembly (2);
inputting steam obtained by vacuum membrane distillation into the first heat medium pipeline through the compressed air of the vacuum pump (3) so as to preheat waste liquid to be treated flowing through the first heat medium pipeline;
and inputting the steam and liquid water discharged from the first refrigerant pipeline into the second heat exchanger (4) for liquefying the steam discharged from the first refrigerant pipeline.
10. The method for treating a waste liquid by membrane distillation according to claim 9,
the device for treating waste liquid by membrane distillation further comprises a waste liquid container (5), wherein a waste liquid outlet of the waste liquid container (5) is communicated with the first inlet (11) for providing waste liquid to be treated, a membrane distillation liquid outlet (22) is communicated with a liquid inlet of the waste liquid container (5), and the membrane distillation treatment method further comprises the step of conveying distilled waste liquid discharged from the membrane distillation liquid outlet (22) to the waste liquid container (5) so as to form a closed loop;
and/or the number of the groups of groups,
in the step of inputting the steam and liquid water discharged from the first refrigerant pipeline into the second heat exchanger (4) for liquefying the steam discharged from the first refrigerant pipeline, the second heat exchanger (4) is an air-cooled radiator for liquefying the steam discharged from the first refrigerant pipeline through air-cooled heat radiation.
CN202211691395.5A 2022-12-27 2022-12-27 Device and method for treating waste liquid by membrane distillation Pending CN116062838A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211691395.5A CN116062838A (en) 2022-12-27 2022-12-27 Device and method for treating waste liquid by membrane distillation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211691395.5A CN116062838A (en) 2022-12-27 2022-12-27 Device and method for treating waste liquid by membrane distillation

Publications (1)

Publication Number Publication Date
CN116062838A true CN116062838A (en) 2023-05-05

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Country Status (1)

Country Link
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