CN115501637A - VOC condensation recovery system and corresponding VOC condensation recovery method - Google Patents

VOC condensation recovery system and corresponding VOC condensation recovery method Download PDF

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Publication number
CN115501637A
CN115501637A CN202211295327.7A CN202211295327A CN115501637A CN 115501637 A CN115501637 A CN 115501637A CN 202211295327 A CN202211295327 A CN 202211295327A CN 115501637 A CN115501637 A CN 115501637A
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cold source
airflow
channel
defrosting
voc
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CN115501637B (en
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陈海洋
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Shenzhen Dejieli Cryogenic Technology Co ltd
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Shenzhen Dejieli Cryogenic Technology Co ltd
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Priority to CN202310706506.3A priority patent/CN116637392A/en
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    • 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
    • B01D5/0003—Condensation of vapours; Recovering volatile solvents by condensation by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium
    • B01D5/0006—Coils or serpentines
    • 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
    • B01D5/0036—Multiple-effect condensation; Fractional condensation
    • 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
    • B01D5/0096—Cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
    • B01D2257/708—Volatile organic compounds V.O.C.'s
    • 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
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Treating Waste Gases (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention provides a VOC condensation recovery system and a corresponding VOC condensation recovery method. The VOC condensation recovery system comprises a precooling device, a condensing device, a final cooling device, a cold source access port, an airflow input port, an airflow discharge port, a cold source discharge port and a solvent storage tank; the VOC condensation recovery method comprises the following steps: sequentially carrying out primary precooling treatment, secondary condensing treatment and tertiary final cooling treatment on the VOC gas flow, and finally generating clean gas flow; the cold medium in the third-stage final cooling treatment is a cold source, and the cold source forms a secondary cold source after the third-stage final cooling treatment and is used as a refrigerant for the first-stage pre-cooling treatment; the clean air flow is used as a refrigerant for secondary condensation treatment. The cold source can be used for multiple times, and the cold energy of the clean air flow can be utilized, so that the cold energy is fully utilized, and the energy is saved; the VOC air flow temperature is gradually reduced, the frosting phenomenon caused by too fast temperature reduction is reduced, harmful substances can be comprehensively condensed to form a solvent, and the treatment effect is good.

Description

VOC condensation recovery system and corresponding VOC condensation recovery method
Technical Field
The invention relates to the field of volatile gas treatment, in particular to a VOC condensation recovery system and a corresponding VOC condensation recovery method.
Background
VOC is an English abbreviation for volatile organic compounds (volatile organic compounds). VOCs in the general sense are commanding organic matters; but the definition in the environmental protection sense refers to an active class of volatile organic compounds, namely, volatile organic compounds which can cause harm. Therefore, the VOC needs to be purified and then discharged.
In the prior art, when VOC is purified, the harmful substances in the VOC are condensed and collected by adopting a cold source. When the cold source is reused for heat exchange with the VOC gas flow, the phenomenon of frosting is easily caused due to the fact that the temperature of the VOC gas flow is reduced too fast, so that the treatment speed is reduced, even blockage is caused, and the purification treatment of the VOC is influenced; meanwhile, the cold source is discharged after being used once, so that cold energy is not fully utilized, and waste is caused.
Disclosure of Invention
The invention provides a VOC condensation recovery system and a corresponding VOC condensation recovery method, which can improve the treatment effect and make full use of cold energy.
In one aspect, the invention provides a VOC condensation recycling system for condensation recycling of VOC gas flow, comprising a pre-cooling device, a condensing device, a final cooling device, a cold source access port, a gas flow input port, a gas flow discharge port, a cold source discharge port and a solvent storage tank;
a pre-cooling airflow channel and a pre-cooling cold source channel for heat exchange are arranged in the pre-cooling device, a condensing airflow channel and a condensing cold air channel for heat exchange are arranged in the condensing device, and a final cold airflow channel and a final cold source channel for heat exchange are arranged in the final cooling device;
the gas flow input port is used for accessing VOC gas flow; the air flow discharge port is used for discharging purified cleaning air flow; the airflow input port, the precooled airflow channel, the condensed airflow channel, the final cool airflow channel, the condensed cool airflow channel and the airflow discharge port are sequentially communicated in series; the cold source discharge port is used for discharging a cold source, and the cold source access port, the final cooling cold source channel, the precooling cold source channel and the cold source discharge port are sequentially communicated in series;
the condensed air flow channel, the final cool air flow channel and the condensed cool air channel are communicated to the solvent storage tank, so that the solvent formed after the VOC air flow is cooled is guided to the solvent storage tank.
In another aspect, the present invention provides a method for condensing and recycling VOC gas stream, comprising the steps of;
sequentially carrying out primary precooling treatment, secondary condensing treatment and tertiary final cooling treatment on the VOC gas flow to finally generate clean gas flow, wherein the VOC gas flow generates and collects a solvent in the primary precooling treatment, the secondary condensing treatment and the tertiary final cooling treatment;
the secondary cold source is used as the refrigerant for the primary pre-cooling treatment; and the clean airflow is used as a refrigerant for the secondary condensation treatment.
According to the VOC condensation recovery system and the corresponding VOC condensation recovery method, the cold source connected to the cold source access port can be used for multiple times, and the cold energy of the purified clean air flow can be utilized in the condensation device, so that the cold energy is fully utilized, and the energy is saved; the VOC air flow passes through the condensed air flow channel, the final cooled air flow channel and the condensed cooled air channel in sequence, the temperature is gradually reduced, the frosting phenomenon caused by too fast temperature reduction is reduced, harmful substances can be more comprehensively condensed to form a solvent, and the treatment effect is good.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required in the embodiments are briefly introduced below, and the drawings in the following description are only corresponding to some embodiments of the present invention.
Fig. 1 is a schematic view of a VOC condensation recovery system according to a first embodiment of the present invention;
FIG. 2 is a schematic view of a VOC condensing and recycling system provided by a second embodiment of the invention;
FIG. 3 is a schematic view of the VOC condensation recovery system of FIG. 2 during a defrosting process;
fig. 4 is a schematic view of the VOC condensate recovery system of fig. 2 after defrosting has been removed and before normal treatment is resumed.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
Referring to fig. 1, a first embodiment of the present invention provides a VOC condensation recycling system for condensation recycling a VOC gas stream, which includes a pre-cooling device 10, a condensing device 20, a final cooling device 30, a cold source inlet 41, a gas stream inlet 51, a gas stream discharge port 52, a cold source discharge port 42, and a solvent storage tank 60. The cold source inlet 41 is used for being connected with a cold source for condensing the VOC gas flow, the gas flow inlet 51 is used for being connected with the VOC gas flow, the VOC gas flow forms a solvent and a clean gas flow after passing through the precooling device 10, the condensing device 20 and the final cooling device 30, the solvent enters the solvent storage tank 60, the clean gas flow is discharged through the gas flow discharge port 52, and the cold source is discharged through the cold source discharge port 42 after being used.
The air flow discharge port 52 is provided with a blower 53 for accelerating the air flow to increase the air flow speed.
A pre-cooling airflow channel 101 and a pre-cooling cold source channel 102 for heat exchange are arranged in the pre-cooling device 10, and airflow inside the pre-cooling airflow channel 101 and the pre-cooling cold source channel 102 can exchange heat in the pre-cooling device 10. A condensed air flow channel 201 and a condensed cold air channel 202 for heat exchange are arranged in the condensing device 20, and the air flows in the condensed air flow channel 201 and the condensed cold air channel 202 can exchange heat in the condensing device 20. A final cooling flow path 301 and a final cooling source path 302 for heat exchange are provided in the final cooling device 30.
The air inlet 51 is used to receive the VOC air stream and the air outlet 52 is used to discharge the cleaned air stream generated by purifying the VOC air stream. The gas flow inlet 51, the precooling gas flow channel 101, the condensed gas flow channel 201, the final cooling gas flow channel 301, the condensed cooling gas channel 202 and the gas flow discharge port 52 are sequentially communicated in series; the cold source inlet 41 can be connected to the cold source device 40 to be connected to a cold source, the cold source discharge port 42 is used for discharging the cold source after heat exchange treatment, and the cold source inlet 41, the final cold source channel 302, the precooling cold source channel 102 and the cold source discharge port 42 are sequentially connected in series.
The VOC gas flow sequentially passes through the pre-cooling gas flow channel 101, the condensed gas flow channel 201 and the final cooling gas flow channel 301 for cooling and condensing. Wherein, the cold source that cold source access port 41 inserts carries out the heat exchange with the VOC air current in the cold source passageway of ending 301 in the cold source passageway of ending 302, because the cold source that cold source access port 41 inserts is in the minimum state of temperature in cold source passageway of ending 302, can be with the temperature of the VOC air current in the cold source passageway of ending 301 will be minimum, make the abundant condensation of harmful substance in the VOC air current form the solvent, and form clean air current, this clean air current temperature is lower, enter into condensation cold air passageway 202, cool down as the VOC air current of refrigerant in to condensation air current passageway 201, can abundant cold energy, discharge through air current discharge port 52 again, in order to save the energy.
The cold source that cold source access mouth 41 inserts can enter into precooling cold source passageway 102 after cold source passageway 302 heat exchange eventually, carries out preliminary cooling to the VOC air current in precooling airflow channel 101, can be so that the cold source that cold source access mouth 41 inserts discharges again after obtaining make full use of in precooling apparatus 10 to the energy can be saved.
When the VOC gas flow after the preliminary cooling by the pre-cooling device 10 passes through the condensed gas flow channel 201 of the condensing device 20, the VOC gas flow can exchange heat with the clean gas flow with lower temperature in the condensed gas flow channel 202, the temperature of the VOC gas flow is reduced again, a solvent is formed after partial harmful substances are condensed, finally the VOC gas flow exchanges heat with the cold source with the lowest temperature in the final gas flow channel 301, the temperature is about to be the lowest, and the residual harmful substances are condensed to form the solvent and form the clean gas flow to be discharged.
The cold source in the condensing device 20 can be used for many times, and the cold energy of the clean air flow with lower temperature can be utilized in the condensing device 20, so that the cold energy of the condensing device 20 can be fully utilized, and the energy can be saved. The VOC air flow passes through the condensed air flow channel 201, the final cooled air flow channel 301 and the condensed cooled air channel 202 in sequence, the temperature is gradually reduced, so that harmful substances can be more comprehensively condensed to form a solvent, and the treatment effect is good.
The condensed air flow channel 201, the final cool air flow channel 301 and the condensed cool air channel 202 are all connected to the solvent storage tank 60, so as to guide the solvent formed by condensing the VOC air flow to the solvent storage tank 60. The solvent formed can be collected by the solvent storage tank 60 and disposed of.
A shut-off valve, preferably a pneumatic shut-off valve, is provided at the gas flow inlet 51, with which the open or suspended access of the VOC gas flow can be controlled. One or more of a flame arrester, a temperature sensor, a pressure sensor and the like are arranged on a pipeline from the precooling airflow channel 101 to the airflow input port 51, the flame arrester can avoid fire, and the temperature sensor and the pressure sensor can detect the temperature and the pressure of the input VOC airflow.
The invention also provides a VOC condensation and recovery method corresponding to the first embodiment of the VOC condensation and recovery system, which comprises the following steps.
And sequentially carrying out primary precooling treatment, secondary condensing treatment and tertiary final cooling treatment on the VOC gas flow to finally generate clean gas flow, and generating and collecting a solvent in the primary precooling treatment, the secondary condensing treatment and the tertiary final cooling treatment on the VOC gas flow. The primary pre-cooling treatment is performed in the pre-cooling device 10, the secondary condensation treatment is performed in the condensing device 20, and the tertiary final cooling treatment is performed in the final cooling device 30. The solvent is collected in a solvent storage tank 60.
The refrigerant in the third-stage final cooling treatment is a cold source, and the cold source is a cold source directly led out from the cold source access port 41. The cold source access port 41 is connected to the cold source device 40, the cold source is liquid nitrogen, and the cold source device 40 can be a liquid nitrogen tank.
The cold source forms a secondary cold source after the three-stage final cooling treatment, and the secondary cold source is used as a refrigerant for the primary pre-cooling treatment; the clean air flow is used as a refrigerant for secondary condensation treatment.
In the final cooling device 30, the cold source is located in the final cooling source pipeline, and forms a secondary cold source after heat exchange, and leads to the pre-cooling cold source channel in the pre-cooling device to be used as a cold medium for pre-cooling treatment, so that the cold source can be reused, and the utilization rate of cold energy is improved.
After the first-stage pre-cooling treatment is carried out on the VOC airflow in the pre-cooling terminal, the temperature is reduced by one stage, the VOC airflow enters the condensing device 20 again to be subjected to second-stage condensation treatment, the temperature is reduced again, and finally the third-stage final cooling treatment is carried out in the final cooling device 30, so that the temperature of the VOC airflow is lowest, harmful substances are fully condensed to form a solvent, and clean airflow is generated. The temperature of the VOC gas stream gradually decreases, which can reduce frosting caused by an excessively fast cooling. The clean air flow is used as a refrigerant for secondary condensation treatment, so that the cold energy of the clean air flow can be fully utilized, and the utilization rate of the cold energy is improved.
The VOC air current is after one-level precooling, can divide into the stranded sub-air current and carry out second grade condensation respectively in proper order and the processing of tertiary final cooling, and condensing equipment and final cooling device can be more than two promptly, and the two one-to-one connection, and the condensation subsystem that a set of condensing equipment and final cooling device connect into corresponds a strand of sub-air current to improve condensation effect.
The same heat exchanger may be used for the pre-cooling device 10, the condensing device 20 and the final cooling device 30 for maintenance. A buffer device (not shown in the figure) may be disposed between the bottom of the heat exchanger and the solvent storage tank, and the buffer device is described by taking a pre-cooling device as an example, where the buffer device includes a buffer three-way valve, a buffer pipe, and a check valve, and the pre-cooling airflow channel, the buffer three-way valve, the buffer pipe, the check valve, and the solvent storage tank are sequentially connected. Three interfaces of the buffer three-way valve are respectively communicated to the airflow input port, the precooling airflow pipe and one end of the buffer pipe, and the one-way valve is connected between the other end of the buffer pipe and the solvent storage tank.
The buffer three-way valve has a buffer state and a recovery state: when the cache three-way valve is in a cache state, the airflow input port, the precooling airflow pipe and the cache pipe are communicated, the one-way valve is in a closed state, and the cache pipe is used for caching the solvent flowing out of the precooling airflow pipe; when the buffer memory three-way valve is in the recovery state, close between buffer memory three-way valve and the buffer memory pipe, the check valve is in the open mode to make the solvent in the buffer memory pipe flow into the solvent holding vessel. Through the cooperation of buffer memory three-way valve and check valve, when the interior solvent of buffer memory was deposited to capacity, guide the solvent to the solvent holding vessel again, can make the solvent that the condensation formed carry out the recovery of flowing automatically, and avoid the VOC air current to enter into in the solvent holding vessel.
The bottom of the condensing unit 20 and the bottom of the final cooling unit 30 are both provided with the above-mentioned buffer units, and the structures thereof are the same as those described above, and are not described herein again.
Referring to fig. 2, a second embodiment of the present invention provides a VOC condensation recycling system for condensation recycling of a VOC gas stream, which includes a pre-cooling device 10, a cold source inlet 41, a gas stream inlet 51, a gas stream outlet 52, a cold source outlet 42, and a solvent storage tank 60. The cold source inlet 41 is used for being connected with a cold source for condensing the VOC air flow, the air flow inlet 51 is used for being connected with the VOC air flow, the VOC air flow forms a solvent and a clean air flow after passing through the precooling device 10 and the condensation subsystem, the solvent enters the solvent storage tank 60, the clean air flow is discharged through the air flow discharge port 52, and the cold source is discharged through the cold source discharge port 42 after being used. An air blower for accelerating the air flow is disposed at the air flow discharge port 52 to increase the air flow speed.
A pre-cooling airflow channel 101 and a pre-cooling cold source channel 102 for heat exchange are arranged in the pre-cooling device 10, and airflow inside the pre-cooling airflow channel 101 and the pre-cooling cold source channel 102 can exchange heat in the pre-cooling device 10.
A condensing device and a final cooling device are connected to form two condensing subsystems. For convenience of description, the two condensation subsystems are the first condensation subsystem 91 and the second condensation subsystem 92, respectively, and the condensation device and the final cooling device in the first condensation subsystem 91 are the first condensation device 21 and the first final cooling device 31, respectively. The condensing unit and the final cooling unit within the second condensing subsystem 92 are the second condensing unit 22 and the second final cooling unit 32, respectively.
The first condensing unit 21 is provided with a first condensing airflow channel 211 and a first condensing cold air channel 212 for heat exchange, and the first final cooling unit 31 is provided with a first final cold airflow channel 311 and a first final cold source channel 312 for heat exchange. The first condensed air flow channel 211, the first final cool air flow channel 311 and the first condensed cool air channel 212 are communicated in sequence.
The second condensing unit 22 is provided with a second condensing air flow passage 221 and a second condensing cold air passage 222 for heat exchange, and the second final cooling unit 32 is provided with a second final cold air flow passage 321 and a second final cold source passage 322 for heat exchange. The second condensed air flow channel 221, the second final cool air flow channel 321 and the second condensed cool air channel 222 are communicated in sequence.
An input end of pre-cooled gas flow channel 101 is connected to gas flow input port 51. One end of the first condensed airflow channel 211, which is far away from the first final cool airflow channel 311, and one end of the second condensed airflow channel 221, which is far away from the second final cool airflow channel 321, are both communicated to the output end of the pre-cool airflow channel 101.
The input ends of the first final cooling source channel 312 and the second final cooling source channel 322 are both communicated to the cold source inlet 41, the output ends are both communicated to the input end of the pre-cooling cold source channel 102, and the output end of the pre-cooling cold source channel 102 is communicated to the cold source discharge port 42.
The VOC gas stream first passes through the pre-cooling gas stream channel 101 and then is divided into two sub-gas streams, a first sub-gas stream and a second sub-gas stream, which enter the first condensation gas stream channel 211 and the second condensation gas stream channel 221, respectively. The cold source accessed and output by the cold source access port 41 is divided into two paths, and the two paths enter the first final cooling source channel 312 and the second final cooling source channel 322 respectively.
The first sub-airflow passing through the first condensed airflow channel 211 enters the first final cooling airflow channel 311, and exchanges heat with the cold source in the first final cooling airflow channel 311 and the first final cooling cold source channel 312. The cold source input in the first final cooling source channel 312 is the cold source directly accessed from the cold source access port 41, and the temperature of the cold source is in the lowest state, so that in the first final cooling device 31, the temperature of the VOC gas flow can be reduced to the lowest state, so that harmful substances in the VOC gas flow can be fully condensed in the first final cooling flow channel 311 of the first final cooling device 31 to form a solvent, and a first clean gas flow is formed. The clean air flow has a low temperature, and is guided to the first condensed cold air channel 212 to be used as a refrigerant to cool the VOC air flow in the first condensed air channel 211, so that the VOC air flow can be sufficiently cooled and then discharged through the air flow discharge port 52, thereby saving energy.
The condensation of the second sub-stream entering the second condensed stream channel 221 is performed in the second condensing subsystem, similar to the condensation of the first sub-stream. The second sub air flow enters the second final cooling air flow channel 321 through the second condensed air flow channel 221, and exchanges heat with another cold source in the second final cooling source channel 322 in the second final cooling device 32 to generate a solvent and a second clean air flow, and the second clean air flow enters the second condensed air flow channel 222 to cool the second sub air flow in the second condensed air flow channel 221.
After the two cold sources respectively carry out heat exchange through the first final cold source channel 312 and the second final cold source channel 322, the two cold sources are converged and then enter the pre-cooling cold source channel 102, so that the VOC air flow in the pre-cooling air flow channel 101 is preliminarily cooled, and the cold source accessed through the cold source access port 41 can be discharged after being fully utilized in the pre-cooling device 10, so that energy is saved.
The VOC air current probably takes place to frost in the pipeline of two subsystems because the temperature is too low in first condensation subsystem 91, second condensation subsystem 92, can influence the VOC air current and pass through speed, also can lead to the VOC air current can't fully carry out the heat exchange and form the solvent, and the VOC air current can't obtain abundant condensation and retrieve, causes environmental pollution, therefore needs to handle the frost problem, follows to be the solution in this embodiment.
An output port of the pre-cooling airflow channel 101 is connected with a main airflow pipe 110, an input port of the first condensation airflow channel 211 is connected with a first sub airflow pipe 111, an input port of the second condensation airflow channel 221 is connected with a second sub airflow pipe 112, and the first sub airflow pipe 111 and the second sub airflow pipe 112 are arranged in parallel and are both communicated with the main airflow pipe 110. The first sub gas flow pipe 111, the second sub gas flow pipe 112, and the main gas flow pipe 110 may be connected by a three-way flow dividing valve 113, and the three pipes may be connected by a three-way valve 113 while being controlled by the three-way flow dividing valve 113.
A first defrosting three-way valve 71 is arranged on a pipeline between the first condensed cold air channel 212 and the air flow discharge port 52, and three interfaces of the first defrosting three-way valve 71 are respectively communicated with the first condensed cold air channel 212, the air flow discharge port 52 and the second sub air flow pipe 112 of the second condensing subsystem 92. More specifically, the first defrosting three-way valve 71 may be communicated to the second sub gas flow pipe 112 through a first defrosting pipe, and a three-way pipe is provided at a middle portion of the second sub gas flow pipe 112, and the three-way pipe is communicated with the first defrosting pipe.
The first defrosting three-way valve 71 has a normal state and a defrosting state.
As shown in fig. 2, when the first frost three-way valve 71 is in a normal state, the first condensed cold air channel 212 is communicated with the air flow discharge port 52 via the first frost three-way valve 71, and the first frost three-way valve 71 is closed to the second sub air flow pipe 112 of the second condensation subsystem 92, and at this time, the air flow flowing out of the first condensed cold air channel 212 can be discharged via the air flow discharge port 52.
As shown in fig. 3, when the first defrosting three-way valve 71 is in a defrosting state, the first condensate cold air passage 212 is communicated with the second air flow sub-pipe 112 of the second condensation subsystem 92 through the first defrosting three-way valve 71, and the space between the first defrosting three-way valve 71 and the air flow discharge port 52 is closed, at this time, air flows from the first condensate cold air passage 212 and the second air flow sub-pipe 112 are not discharged through the air flow discharge port 52, and VOC air flows can flow between the first condensate cold air passage 212 and the second air flow sub-pipe 112.
A second frost three-way valve 72 is arranged on a pipeline between the second condensate cold air channel 222 and the air flow discharge port 52, and three interfaces of the second frost three-way valve 72 are respectively communicated with the second condensate cold air channel 222, the air flow discharge port 52 and the first sub air flow pipe 111 of the first condensation subsystem 91. More specifically, the second defrosting three-way valve 72 may be communicated to the first sub gas flow pipe 111 through a second defrosting pipe, and a three-way pipe is provided at a middle portion of the first sub gas flow pipe 111, and the three-way pipe is communicated with the second defrosting pipe.
The second three-way valve 72 has a normal state and a defrosting state. When the second frost three-way valve 72 is in a normal state, the second condensate cold air path 222 is communicated with the air flow discharge port 52 through the second frost three-way valve 72, and the second frost three-way valve 72 is closed to the first sub air flow pipe 111 of the first condensation subsystem 91, and at this time, the air flow flowing out of the second condensate cold air path 222 can be discharged through the air flow discharge port 52. When the second defrosting three-way valve 72 is in a defrosting state, the second condensed cold air passage 222 is communicated with the first sub air flow pipe 111 of the first condensing subsystem 91 through the first defrosting three-way valve 71, and the second defrosting three-way valve 72 is closed from the air flow discharge port 52, at this time, air flows from the second condensed cold air passage 222 and the first sub air flow pipe 111 are not discharged through the air flow discharge port 52, and the VOC air flow can be communicated between the second condensed cold air passage 222 and the first sub air flow pipe 111.
A first cold source valve 411 is arranged between the first end cold source channel 312 and the cold source inlet 41, and the first cold source valve 411 is used for controlling the connection and disconnection between the first end cold source channel 312 and the cold source inlet 41. The first cool source valve 411 has a communication state and a closing state: as shown in fig. 2, when the first cool source valve 411 is in a communication state, the first cool end source channel 312 is communicated with the cool source inlet 41 through the first cool source valve 411, and at this time, the cool source inlet 41 is connected to the cool source device 40 and can provide a cool source into the first cool end source channel 312; as shown in fig. 3, when the first cool source valve 411 is in a closed state, the first cool end source passage 312 and the cool source inlet 41 are closed by the first cool source valve 411, and at this time, the cool source inlet 41 stops supplying the cool source into the first cool end source passage 312.
A second cold source valve 412 is disposed between the second final cold source channel 322 and the cold source inlet 41, and the second cold source valve 412 is used for controlling the on-off between the second final cold source channel 322 and the cold source inlet 41. The second cool source valve 412 has a closed state and an open state: when the second cool source valve 412 is in a communication state, the second cool end source channel 322 is communicated with the cool source inlet 41 through the second cool source valve 412, and at this time, the cool source inlet 41 can provide a cool source to the second cool end source channel 322; when the second cool source valve 412 is in the closed state, the second cool final source passage 322 and the cool source inlet 41 are closed by the second cool source valve 412, and at this time, the cool source inlet 41 stops supplying the cool source into the second cool final source passage 322.
As shown in fig. 2, when the first condensing subsystem 91 is normally operated, the first cold source valve 411 is in a connected state, and the first frost three-way valve 71 is in a normal state. When the second condensing subsystem 92 normally operates, the second cool source valve 412 is in a communication state, and the second defrosting three-way valve 72 is in a normal state.
When frosting occurs in the first condensing subsystem 91, as shown in fig. 3, the first cold source valve 411 is in a closed state, and the first defrosting three-way valve 71 is in a defrosting state. At this time, the first final cooling source channel 312 and the cold source inlet 41 are closed by the first cold source valve 411, so that the cold source inlet 41 no longer provides the cold source to the first final cooling source channel 312, and the condensation process of the first condensation subsystem 91 is stopped; the space between the first condensed cold air channel 212 and the air flow discharge port 52 is in a closed state through the first defrosting three-way valve 71, so that the first stream of clean air cannot be discharged through the first defrosting three-way valve 71 and the air flow discharge port 52; the second sub airflow pipe 112 of the second condensing subsystem 92 is in communication with the first condensed cold air channel 212 through the first defrosting three-way valve 71, so that the VOC airflow can sequentially enter the first condensed cold air channel 212, the first final cold air channel 311 and the first condensed air channel 211 through the second sub airflow pipe 112 of the second condensing subsystem 92 for defrosting.
By using the first defrosting three-way valve 71, the VOC gas flow which is not condensed by the two condensing subsystems and has a higher temperature can reversely flow in the first condensing subsystem 91 along the purification route, and sequentially pass through the first condensed cold gas channel 212, the first final cold gas channel 311 and the first condensed gas channel 211 in the first condensing subsystem 91, so as to defrost by using the VOC gas flow with a higher temperature; the VOC gas flow for defrosting flows out of the first condensation flow channel 211 and then enters the second condensation subsystem 92 through the first sub-gas flow pipe 111 and the second sub-gas flow pipe 112, at this time, the second condensation subsystem 92 is in a normal working state, and the VCO gas flow for defrosting can be processed in the second condensation subsystem 92 to form a clean gas flow and then discharged. When the first condensing subsystem 91 is frosted, the first cold source valve 411, the first defrosting three-way valve 71 and the second condensing subsystem 92 can ensure the uninterrupted processing of the VOC gas flow.
When frosting occurs in the second condensing subsystem 92, the second cold source valve 412 is in a closed state, the second defrosting three-way valve 72 is in a defrosting state, at this time, the second condensing subsystem 92 can be defrosted, the VOC gas flow can be continuously processed through the first condensing subsystem 91, the defrosting process is similar to that of the first condensing subsystem 91, and details are not repeated here.
In order to further improve the defrosting effect: the output ports of the first final cooling source channel 312 and the second final cooling source channel 322 are both communicated to the pre-cooling cold source conveying pipe 33, a pre-cooling three-way valve 43 is arranged between the pre-cooling cold source conveying pipe 33 and the input port of the pre-cooling cold source channel 102, two cold source airflows which are subjected to heat exchange in the first final cooling source channel 312 and the second final cooling source channel 322 are converged into the pre-cooling cold source conveying pipe 33, are conveyed to the pre-cooling three-way valve 43 through the pre-cooling cold source conveying pipe 33, and pass through the pre-cooling three-way valve 43, so that the cold source airflows in the pre-cooling cold source conveying pipe 33 enter the pre-cooling cold source channel 102 or are directly discharged through the cold source discharge port 42.
Three ports of the pre-cooling three-way valve 43 are respectively communicated to the pre-cooling cold source delivery pipe 33, the input port of the pre-cooling cold source channel 102, and the cold source discharge port 42, and the pre-cooling three-way valve 43 has a pre-cooling state and a discharge state.
As shown in fig. 2, when the precooling three-way valve 43 is in a precooling state, the precooling cold source conveying pipe 33 is communicated with the input port of the precooling cold source channel 102 through the precooling three-way valve 43, and the precooling three-way valve 43 is closed with the cold source discharge port 42, at this time, the cold source airflow in the precooling cold source conveying pipe 33 enters the precooling cold source channel 102 to precool the VOC airflow, and does not discharge the VOC airflow through the cold source discharge port 42.
As shown in fig. 3, when the precooling three-way valve 43 is in the discharging state, the precooling cold source delivery pipe 33 is communicated with the cold source discharging port 42 through the cold source three-way valve, and the precooling three-way valve 43 is closed with the input port of the precooling cold source channel 102, at this time, the cold source airflow entering the precooling cold source delivery pipe 33 is not passed through the precooling cold source channel 102, but is directly discharged through the cold source discharging port 42.
When the first condensing subsystem 91 and the second condensing subsystem 92 both normally operate, the pre-cooling three-way valve 43 is in a pre-cooling state to perform secondary utilization on cold energy of the cold source. When the frosting phenomenon occurs in any one of the first condensation subsystem 91 and the second condensation subsystem 92, the precooling three-way valve 43 is in the discharge state, so that the cold source accessed by the cold source access port 41 is not reused, namely, the VOC air flow is not precooled by the precooling device 10, the air flow entering the main air flow pipe 110 is not precooled, the temperature of the air flow is higher than that of the precooled air flow, the VOC air flow enters the condensation subsystem with the frosting phenomenon, and the frosting efficiency and the frosting effect can be improved.
Still further, the VOC condensation recycling system may further include a defrosting device 80, and the defrosting device 80 is disposed on the main gas flow pipe 110 for heating and warming the VOC gas flow entering each condensation subsystem. When the phenomenon of frosting appears in arbitrary condensing subsystem, can open the device 80 that defrosts, the device 80 that defrosts is in the running state, and the device 80 that defrosts heats the VOC air current in main air pipe 110, improves the VOC air current temperature in getting into the condensing subsystem, and then can further improve the efficiency of defrosting and the effect of defrosting. Here, in other embodiments, the defrosting device 80 may also be disposed on a pipeline between the pre-cooling airflow channel 101 and the airflow input 51, and may heat and raise the temperature of the VOC airflow entering each condensing subsystem.
The VOC condensing and recycling system further includes a control module (not shown in the figure), at least one of the condensing cold air channel 202, the final cold air channel 301 and the condensing air channel 201 of the same condensing subsystem is provided with a frost formation sensor (not shown in the figure), that is, at least one of the first condensing cold air channel 212, the first final cold air channel 311 and the first condensing air channel 211 is provided with a frost formation sensor (not shown in the figure), and at least one of the second condensing cold air channel 222, the second final cold air channel 321 and the second condensing air channel 221 is provided with a frost formation sensor for sensing a frost formation state.
The frosting sensor, the defrosting device 80, the first defrosting three-way valve 71, the second defrosting three-way valve 72, the first cold source valve 411, the second cold source valve 412 and the precooling three-way valve 43 are electrically connected to the control module, and the control module is used for receiving the signal of the frosting sensor and controlling the states of the defrosting device 80, the first defrosting three-way valve 71, the second defrosting three-way valve 72, the first cold source valve 411, the second cold source valve 412, the precooling three-way valve 43 and the like.
The frost formation sensor can be one or more of a combination of a temperature sensor, a flow velocity sensor, and a pressure sensor. When the frosting phenomenon occurs in each condensing subsystem, the temperature, the flow and the pressure of the air flow in the condensing cold air channel 202, the final cold air channel 301 and the condensing air flow channel 201 all change, the change of the air flow is detected by the control module, if the sensing signal of the frosting sensor exceeds the frosting threshold value, the frosting phenomenon is generated in the condensing subsystem, and the state change of the defrosting device 80, the defrosting three-way valve, the cold source valve and the precooling three-way valve 43 is controlled.
The frosting threshold comprises a first threshold and a second threshold. The frosting phenomenon is more severe in the second threshold state than in the first threshold state. If the frosting sensor is a temperature sensor, the frosting threshold value is a temperature value, and the first threshold value is larger than the second threshold value, namely, the lower the temperature is, the more serious the frosting phenomenon is. If the frosting sensor is a flow sensor, the frosting threshold value is a flow value passing through the frosting sensor in unit time, and the first threshold value is larger than the second threshold value, namely the frosting phenomenon is more serious as the flow passing through the frosting sensor in unit time is smaller. If the frosting sensor is a flow velocity sensor, the frosting threshold value is a flow velocity value of the air flow, and the first threshold value is larger than the second threshold value, namely, the lower the flow velocity is, the more serious the frosting phenomenon is. If the frosting sensor is a pressure sensor, the frosting threshold value is a pressure value in the pipeline, the first threshold value is smaller than the second threshold value, namely, the larger the pressure is, the more serious the frosting phenomenon is.
Taking the first condensing subsystem 91 as an example, the frosting phenomenon occurs, when the sensing signal of the frosting sensor exceeds the first threshold value, the frosting phenomenon is not very serious, the control module can control the first defrosting three-way valve 71 to be in the defrosting state, the precooling three-way valve 43 to be in the discharging state, and the first cold source valve 411 to be in the closing state, so that the first condensing subsystem 91 stops condensing, and the VOC gas flow which is not subjected to precooling treatment directly reversely passes through the first condensing subsystem 91 to be subjected to defrosting treatment.
When the sensing signal of the frost inductor exceeds the second threshold value, the phenomenon of frosting is comparatively serious this moment, perhaps, does not reach the expectation in certain time through the aforesaid processing effect of defrosting, and control module can further control on the above-mentioned basis that it is in the running state to change the white device 80, heats the back to the VOC air current, makes it reverse through second condensation subsystem 92 to improve the effect of changing white.
A defrosting temperature sensor may be disposed on the main air flow pipe 110 to detect a heating effect of the defrosting device 80, and the defrosting temperature sensor may be electrically connected to the control module to control a heating power of the defrosting device 80 according to a signal of the defrosting temperature sensor.
Here, it can be understood that, as another embodiment, the first threshold and the second threshold may not be set, and when a frosting phenomenon occurs, the control module directly controls the first defrosting three-way valve 71 to be in a defrosting state, the precooling three-way valve 43 to be in a discharging state, the first cold source valve 411 to be in a closed state, and the defrosting device 80 to be in an operating state, so as to increase the defrosting speed.
When the frosting state of the first condensing subsystem 91 occurs, the first defrosting three-way valve 71 is controlled to be in the frosting state, and then the first cold source valve 411 is controlled to be in the closing state, so that the situation that the VOC gas flow which is not subjected to purification treatment is discharged through the first defrosting three-way valve 71 after the first cold source valve 411 is avoided.
In this embodiment, main gas flow pipe 110 is connected to first sub gas flow pipe 111 and second sub gas flow pipe 112 by a three-way flow dividing valve 113. The flow-dividing three-way valve 113 has a flow-dividing state and a purge state.
When the three-way valve 113 is in the diversion state, the main airflow pipe 110 is connected to the first sub airflow pipe 111 and the second sub airflow pipe 112, so that the VOC airflow can be divided into two flows by the three-way valve 113 and enter the first sub airflow pipe 111 and the second sub airflow pipe 112.
When the three-way shunt valve 113 is in a purification state, the main gas flow pipe 110 is communicated with the sub gas flow pipe of the condensation subsystem which finishes defrosting through the three-way shunt valve 113, and the three-way shunt valve 113 is closed with the sub gas flow pipe of the condensation subsystem which does not frost.
For example, after the first condensing subsystem 91 is frosted and the defrosting process is completed, the internal pipeline of the first condensing subsystem is recovered to normal, as shown in fig. 4, at this time, the first cold source valve 411 is controlled to be in an open state, the shunt three-way valve 113 is in a purification state, and the defrosting device 80 is in a closed state, so that the first defrosting three-way valve 71 is kept in the defrosting state, the main airflow pipe 110 is communicated with the first sub airflow pipe 111, and is disconnected from the second sub airflow pipe 112, so that the VOC airflow of the main airflow pipe 110 enters the first condensing subsystem 91 through the first sub airflow pipe 111 for purification, the treated clean airflow can enter the second condensing subsystem 92 through the first defrosting three-way valve 71, and the VOC airflow for defrosting remaining in the first condensing cold air passage is purified in the second condensing subsystem 92. After a period of operation, at this time, there is no longer an untreated VOC gas flow in the first condensing cold gas channel, and then the first defrosting three-way valve 71 is controlled to be in a normal state, so that the first condensing subsystem resumes normal operation.
Here, whether the defrosting operation is completed may be determined by whether the signal of the frost formation sensor is restored to normal.
In this embodiment, the control module is used to control the state switching of the components such as the precooling three-way valve, the defrosting device, the defrosting three-way valve and the cold source valve, in other embodiments, the components can be manually operated in a manual mode, and the frosting sensor can be connected with an audible and visual alarm device to prompt an operator to operate the components.
In the above embodiment, the VOC gas flow for defrosting remaining in the first condensed cold air passage is removed by the diversion three-way valve 113, and here, a gas flow reversing device may be disposed between the first defrosting three-way valve and the second sub gas flow pipe, and the VOC gas flow for defrosting is removed by controlling the gas flow direction between the first defrosting three-way valve and the second sub gas flow pipe. For example, when the frosting of the first condensation subsystem is eliminated, the airflow reversing device is controlled to enable the flowing direction of the airflow to be from the second sub airflow pipe to the first defrosting three-way valve so as to guide the VOC airflow for defrosting into the first condensation subsystem; when frosting is eliminated, the airflow reversing device is switched, so that the flowing direction of the airflow is from the first defrosting three-way valve to the second sub airflow pipe, and the VOC airflow for defrosting enters the second sub airflow pipe and is purified by the second condensing subsystem.
In the above embodiment, there are one or two condensing subsystems, but in other embodiments, there may be three or more condensing subsystems, and it can be seen from the combination of the second embodiment that when there are more than two condensing subsystems, the condensing airflow channel, the final cooling airflow channel, and the condensing cooling airflow channel in the same condensing subsystem are sequentially connected in series; the condensation air flow channels in all the condensing devices are communicated with the precooling air flow channels, the condensation cold air channels in all the condensing devices are communicated with the precooling air flow channels, and the final cooling source channels in all the final cooling devices are communicated with the cold source device; the input port of each condensed cold air channel is connected with a sub-airflow pipe, and all the sub-airflow pipes are arranged in parallel and are communicated with the main airflow pipe; the defrosting three-way valve and the sub-gas flow pipes of the condensing subsystem can be sequentially connected in a circulating manner, so that VOC gas flow is conveyed to the defrosting three-way valve and the channel of the defrosting three-way valve of the condensing subsystem with the frosting phenomenon through the sub-gas flow pipes of other condensing subsystems, and defrosting treatment is carried out on the VOC gas flow.
For example, when there are three condensation subsystems, that is, a third condensation subsystem is further included in the second embodiment, one interface of the first frost three-way valve 71 of the first condensation subsystem 91 is communicated to the second sub gas flow pipe 112 of the second condensation subsystem 92, one interface of the second frost three-way valve 72 of the second condensation subsystem 92 is communicated to the third sub gas flow pipe of the third condensation subsystem, and one interface of the third frost three-way valve of the third condensation subsystem is communicated to the first sub gas flow pipe 111 of the first condensation subsystem 91. In this way, when the first condensation subsystem 91 frosts, the VOC gas flow of the second sub-gas flow pipe 112 can be used to defrost the pipelines in the first condensation subsystem 91; when the second condensation subsystem 92 frosts, the VOC gas flow of the third sub gas flow pipe can be used for defrosting each pipeline in the second condensation subsystem 92; when the third condensing subsystem frosts, the VOC gas flow of the first sub gas flow pipe 111 can be used to defrost the pipes in the third condensing subsystem. When the condensing subsystems are more than four, similar to three time phases, the condensing subsystems can be sequentially connected in a circulating mode, so that when one or two condensing subsystems frost, the defrosting treatment can be effectively carried out.
In combination with the second embodiment of the VOC condensation recycling system, the invention also provides another VOC condensation recycling method, which comprises the following steps.
And sequentially carrying out primary precooling treatment, secondary condensing treatment and tertiary final cooling treatment on the VOC gas flow to finally generate clean gas flow, and generating and collecting a solvent in the primary precooling treatment, the secondary condensing treatment and the tertiary final cooling treatment on the VOC gas flow. The primary precooling treatment is carried out in the precooling device 10, the secondary condensing treatment is carried out in the first and second condensing devices, and the tertiary final cooling treatment is carried out in the first and second final cooling devices. The solvent is recovered to the solvent storage tank 60. The temperature of the VOC gas flow is gradually reduced, and frosting caused by too fast temperature reduction can be reduced. The clean air flow is used as a refrigerant for secondary condensation treatment, so that the cold energy of the clean air flow can be fully utilized, and the utilization rate of the cold energy is improved.
The refrigerant in the third-stage final cooling treatment is a cold source, and the cold source is a cold source directly connected from a cold source inlet 41. The cold source is liquid nitrogen, and the cold source device 40 connected to the cold source inlet 41 can be a liquid nitrogen tank. The cold source forms a secondary cold source after three-stage final cooling treatment, namely, the air flows flowing out of the first and second final cooling source channels are the secondary cold source, and the secondary cold source is used as a refrigerant for the primary pre-cooling treatment; the clean air flow is used as a refrigerant for secondary condensation treatment. In first, second end cold charge, the cold source is located first, second end cold source pipeline, forms the secondary cold source after the heat exchange to guide as the refrigerant of one-level precooling processing in the precooling apparatus, make the cold source can reutilization, improve cold energy utilization ratio.
Sequentially carrying out primary precooling treatment, secondary condensation treatment and tertiary final cooling treatment on the VOC gas flow, then carrying out primary flow distribution on the VOC gas flow to divide the VOC gas flow into two or more sub-gas flows which are respectively sequentially subjected to the secondary condensation treatment and the tertiary final cooling treatment; namely, the water enters each condensing subsystem for treatment. For example, after the first-stage pre-cooling treatment, the VOC gas stream flows out from the pre-cooling device 10 and is divided into two sub-gas streams, i.e., a first sub-gas stream and a second sub-gas stream, the first sub-gas stream enters the first condensing subsystem 91, and the second sub-gas stream enters the second condensing subsystem 92. Each sub-gas flow is a purification route through a route which is sequentially passed through in the condensation recovery process of the condensation subsystem. For example, in the condensing recovery of the first condensing subsystem 91, the first sub-gas flow is purified by the first condensing gas flow channel 211, the first final cooling gas flow channel and the first condensing gas flow channel 211.
The VOC condensation recovery method further comprises the following defrosting treatment steps. When the frosting phenomenon occurs in one of the sub-air flow purification treatment processes, the defrosting treatment step is executed to solve the frosting phenomenon,
the defrosting treatment step comprises: closing the discharge channel of the strand of air flow, interrupting the supply of the cold source in the three-stage final cooling treatment of the strand of air flow, performing secondary flow division on the other strand of air flow to divide a strand of defrosting air flow, and reversely flowing the defrosting air flow along the purification route of the strand of air flow to perform defrosting treatment until the frosting phenomenon is eliminated.
In combination with the second embodiment of the VOC condensation recycling system, when the first sub-air flow frosts in the first condensing subsystem 91, the discharge channel of the first sub-air flow is closed, and the discharge of the first sub-air flow is stopped, that is, the first defrosting three-way valve 71 is controlled to be in a defrosting state; the supply of the cold source of the first final cooling device 31 in the three-stage final cooling treatment is interrupted, that is, the first cold source valve 411 is closed, so that the cold source cannot enter the first final cooling source channel in the first final cooling device 31, and the supply of the cold source in the three-stage final cooling treatment is further realized.
And the second sub airflow is divided for the second time to form a first defrosting airflow, and the first defrosting airflow reversely flows along the purification route of the first sub airflow to perform defrosting treatment, namely sequentially passes through the first condensed airflow channel, the first final cooled airflow channel 311 and the first condensed airflow channel 211. Because the first stream of defrosting air flow is not subjected to purification treatment by the second condensing subsystem 92, the temperature of the first stream of defrosting air flow is still in a high state, and the temperature of each pipeline of the first condensing subsystem 91 can be raised, so that the defrosting purpose is achieved.
In order to improve the defrosting effect, the secondary cold source formed after the three-stage final cooling treatment is directly discharged, the supply of the refrigerant subjected to the primary pre-cooling treatment is interrupted, namely, a pipeline between the first final cooling source channel 312 and the pre-cooling cold source channel 102 is closed, and the first final cooling source channel 312 is directly communicated to the cold source discharge port 42, so that the secondary cold source flowing out of the first final cooling source channel 312 is directly discharged, and secondary utilization is not performed any more. So that the VOC gas stream skips the primary pre-cooling process and its temperature does not drop, thereby allowing defrosting of the first condensing subsystem 91 at a higher temperature.
Further, when the first strand of sub-air current frosts, the heating process is carried out on the VOC air current before the first shunting, so that the temperature of the VOC air current reversely entering the first condensing subsystem 91 is higher, and the defrosting efficiency is accelerated. In this step, the VOC gas stream may be heated by the defrosting device 80 before entering the main gas line 110 or the primary precooling treatment.
Here, the supply of the refrigerant for the first-stage precooling process is interrupted, and the VOC gas flow before the first division is heated, and both processes may be performed simultaneously or alternatively.
After the frosting phenomenon is eliminated, the normal operation of the VOC gas flow is restored. In order to avoid the discharge of unpurified VOC gas streams, the defrosting process step of the present invention further comprises: when the frosting phenomenon is eliminated, closing a shunting channel between the VOC air flow and the other sub air flow to stop supplying the defrosting air flow; and recovering cold source supply in the three-stage final cooling treatment of the frost-removing sub-airflow, wherein the frost-removing sub-airflow flows along a purification route to perform purification treatment, and the purified clean airflow enters the purification route of the other sub-airflow along the reverse route of the frost-removing airflow. After the operation is carried out for a preset time, the discharge channel of the sub airflow for eliminating the frosting is opened, the channel for leading the defrosting airflow to reversely enter the secondary condensation treatment is closed, and finally, the flow dividing channel between the VOC airflow and the other sub airflow is recovered.
More specifically, for example, after the frost formation phenomenon of the first condensing subsystem 91 is eliminated, the flow dividing passage between the VOC gas flow and the second substream is closed, and the flow dividing three-way valve 113 is in a purification state, so that the second substream is not reformed into the first frost gas flow. The first sub-air flow enters the first condensing subsystem 91 along its own purification route for purification treatment, and forms a clean air flow, and the clean air flow enters the second sub-air flow purification route, namely the second condensing subsystem 92, along the reverse route of the first defrosting air flow. After the operation is preset for a long time, it can be ensured that the first condensation cold air channel 212 is not internally provided with the first unpurified defrosting air flow, the discharge channel of the first strand of sub air flow is opened again, the channel of the first defrosting air flow entering the first condensing device 21 is closed at the same time, the shunting channel between the VOC air flow and the second strand of sub air flow is opened again at last, the shunting three-way valve 113 is in a shunting state, at the moment, the normal treatment of the VOC air flow is recovered, and the defrosting treatment is completed.
When the frosting phenomenon occurs in the second sub airflow, the first sub airflow is divided for the second time to divide the second defrosting airflow, and the second defrosting airflow is used for defrosting the purification channel of the second sub airflow, and the process is the same as the process when the frosting phenomenon occurs in the first sub airflow, and is not repeated here.
In summary, although the present invention has been described with reference to the preferred embodiments, the above-described preferred embodiments are not intended to limit the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, therefore, the scope of the present invention shall be determined by the appended claims.

Claims (10)

1. A VOC condensation recovery system is used for carrying out condensation recovery on VOC airflow and is characterized by comprising a precooling device, a condensing device, a final cooling device, a cold source access port, an airflow input port, an airflow discharge port, a cold source discharge port and a solvent storage tank;
a pre-cooling airflow channel and a pre-cooling cold source channel for heat exchange are arranged in the pre-cooling device, a condensing airflow channel and a condensing cold air channel for heat exchange are arranged in the condensing device, and a final cold airflow channel and a final cold source channel for heat exchange are arranged in the final cooling device;
the gas flow input port is used for accessing VOC gas flow; the air flow discharge port is used for discharging purified clean air flow; the airflow input port, the precooling airflow channel, the condensed airflow channel, the final cool airflow channel, the condensed cool airflow channel and the airflow discharge port are sequentially communicated in series; the cold source discharge port is used for discharging a cold source, and the cold source access port, the final cooling cold source channel, the precooling cold source channel and the cold source discharge port are sequentially communicated in series;
the condensed air flow channel, the final cool air flow channel and the condensed cool air channel are communicated to the solvent storage tank so as to guide the solvent formed after the VOC air flow is cooled to the solvent storage tank.
2. A VOC condensation recycling system according to claim 1, wherein a condensing unit and a final cooling unit are connected to form a condensing subsystem; the condensation subsystems are more than two, and a condensation air flow channel, a final cooling air flow channel and a condensation cooling air channel which are positioned in the same condensation subsystem are sequentially communicated in series; the condensing air flow channels in all the condensing devices are communicated to the precooling air flow channels, all the condensing cold air channels are communicated to the precooling air flow channels, and the input ends of all the final cooling source channels are communicated to the cold source access ports, and the output ends of all the final cooling source channels are communicated to the input ends of the precooling cold source channels.
3. The VOC condensation recycling system according to claim 2, wherein an output port of the pre-cooling airflow channel is connected to a main airflow pipe, an input port of each of the condensing airflow channels is connected to a sub-airflow pipe, and all the sub-airflow pipes are arranged in parallel and are all communicated with the main airflow pipe;
within the same condensing subsystem: a defrosting three-way valve is arranged between the condensed cold air channel and the air flow discharge port; three interfaces of the defrosting three-way valve are respectively communicated with the condensed cold air channel, the airflow discharge port and a sub airflow pipe of the other condensing subsystem; the defrosting three-way valve has a normal state and a defrosting state; when the defrosting three-way valve is in a normal state, the pipeline of the condensed cold air channel and the pipeline of the air flow discharge port are communicated through the defrosting three-way valve, and the channel between the defrosting three-way valve and the sub air flow pipe of the other condensing subsystem is closed; when the defrosting three-way valve is in a defrosting state, the condensing cold air channel is communicated with a sub airflow pipe of another condensing subsystem through the defrosting three-way valve, and a channel between the defrosting three-way valve and the airflow discharge port is closed; a cold source valve is arranged between the final cooling source channel and the cold source access port, and the cold source valve has a communication state and a closing state; when the cold source valve is in a communicated state, the final cooling source channel is communicated with the cold source access port through the cold source valve; when the cold source valve is in a closed state, the final cooling source channel and the cold source access port are closed through the cold source valve;
when the condensing subsystem normally operates, a cold source valve in the condensing subsystem is in a communicated state, and a defrosting three-way valve is in a normal state;
when the condensation subsystem frosts, a cold source valve in the condensation subsystem is in a closed state, and a defrosting three-way valve is in a defrosting state.
4. The VOC condensation recovery system of claim 3, wherein the output ports of all the final cooling source channels are communicated with a pre-cooling cold source conveying pipe, a pre-cooling three-way valve is arranged between the pre-cooling cold source conveying pipe and the input ports of the pre-cooling cold source channels, three interfaces of the pre-cooling three-way valve are respectively communicated with the pre-cooling cold source conveying pipe, the input ports of the pre-cooling cold source channels and the cold source discharge port, and the pre-cooling three-way valve has a pre-cooling state and a discharge state;
when the precooling three-way valve is in a precooling state, the precooling cold source conveying pipe is communicated with the input port of the precooling cold source channel through the precooling three-way valve, and the precooling three-way valve is closed with the cold source discharge port;
when the precooling three-way valve is in a discharging state, the precooling cold source conveying pipe is communicated with the cold source discharging port through the cold source three-way valve, and the precooling three-way valve is closed to the input port of the precooling cold source channel;
when the condensing subsystem normally operates, the precooling three-way valve is in a precooling state; when frosting occurs in the condensation subsystem, the pre-cooling three-way valve is in a discharge state.
5. The VOC condensation recovery system according to claim 4 further comprising a defrosting device for heating the VOC gas stream entering each of the condensing subsystems;
the defrosting device is arranged on the main airflow pipe, or the defrosting device is arranged on a pipeline between the precooling airflow channel and the airflow input port.
6. The VOC condensation recovery system of claim 5, further comprising a control module, wherein at least one of the condensed cold air channel, the final cold air channel and the condensed air channel of the same condensation subsystem is provided with a frosting sensor for sensing the frosting state;
the frosting sensor, the precooling three-way valve, the defrosting device, all the defrosting three-way valves and all the cold source valves are electrically connected to the control module, and the control module is used for receiving signals of the frosting sensor and controlling the states of the precooling three-way valve, the defrosting device, all the defrosting three-way valves and all the cold source valves.
7. A VOC condensation recovery method is used for carrying out condensation recovery on a VOC gas flow and is characterized by comprising the following steps:
sequentially carrying out primary precooling treatment, secondary condensing treatment and tertiary final cooling treatment on the VOC gas flow to finally generate clean gas flow, wherein the VOC gas flow generates and collects a solvent in the primary precooling treatment, the secondary condensing treatment and the tertiary final cooling treatment;
the refrigerant in the three-stage final cooling treatment is a cold source, the cold source forms a secondary cold source after the three-stage final cooling treatment, and the secondary cold source is used as the refrigerant of the primary pre-cooling treatment; and the clean airflow is used as a refrigerant for the secondary condensation treatment.
8. The method for condensing and recycling the VOC according to claim 7, wherein in the step of sequentially performing a primary precooling treatment, a secondary condensing treatment and a tertiary final cooling treatment on the VOC gas flow, the VOC gas flow is subjected to a primary flow splitting after the primary precooling treatment, so that the VOC gas flow is divided into more than two sub-gas flows which are sequentially subjected to the secondary condensing treatment and the tertiary final cooling treatment respectively;
the VOC condensation recovery method also comprises a defrosting treatment step; when the frosting phenomenon occurs in the purification treatment process of one sub-airflow, the defrosting treatment step is executed; the defrosting treatment step comprises the following steps: and closing the discharge channel of the sub airflow, interrupting the supply of the cold source in the three-stage final cooling treatment of the sub airflow, and performing secondary flow division on the other sub airflow to divide a defrosting airflow, wherein the defrosting airflow reversely flows along the purification route of the sub airflow to perform defrosting treatment.
9. The VOC condensation recycling method according to claim 8, wherein the defrosting step further comprises: directly discharging the secondary cold source formed after the three-stage final cooling treatment, and interrupting the supply of the refrigerant subjected to the primary pre-cooling treatment; and/or, heating the VOC gas stream prior to the first diversion.
10. The VOC condensation recycling method according to claim 8, wherein the defrosting process step further comprises:
when the frosting phenomenon is eliminated, closing a flow dividing channel between the VOC airflow and the other sub airflow so as to stop supplying the defrosting airflow;
recovering cold source supply in the three-stage final cooling treatment of the frost-removing sub-airflow, wherein the frost-removing sub-airflow flows along a purification route to carry out purification treatment, and the purified clean airflow enters the purification route of the other sub-airflow along the reverse route of the frost-removing airflow;
after the operation is carried out for a preset time, opening a discharge channel of the sub airflow for eliminating the frosting, and closing a channel for the defrosting airflow to reversely enter a secondary condensation treatment;
restoring a bypass channel between the VOC gas stream and another subsidiary gas stream.
CN202211295327.7A 2022-10-21 2022-10-21 VOC condensation recovery system and corresponding VOC condensation recovery method Active CN115501637B (en)

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CN215250626U (en) * 2021-04-20 2021-12-21 南京久鼎制冷空调设备有限公司 Multistage condensation oil gas recovery system based on secondary refrigerant
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