CN111013321A - Three-adsorber air separation purification device capable of recovering latent heat and method thereof - Google Patents

Three-adsorber air separation purification device capable of recovering latent heat and method thereof Download PDF

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CN111013321A
CN111013321A CN201911349228.0A CN201911349228A CN111013321A CN 111013321 A CN111013321 A CN 111013321A CN 201911349228 A CN201911349228 A CN 201911349228A CN 111013321 A CN111013321 A CN 111013321A
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molecular sieve
sieve adsorber
channel
circulating water
heat
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张春伟
张学军
邱利民
赵阳
林秀娜
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/02Separation 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 adsorption, e.g. preparative gas chromatography
    • B01D53/04Separation 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 adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/0407Constructional details of adsorbing systems
    • B01D53/0438Cooling or heating systems
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D53/00Separation 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
    • B01D53/02Separation 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 adsorption, e.g. preparative gas chromatography
    • B01D53/04Separation 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 adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B01D53/0454Controlling adsorption
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2253/00Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10Inorganic adsorbents
    • B01D2253/104Alumina
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2253/00Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10Inorganic adsorbents
    • B01D2253/106Silica or silicates
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2259/00Type of treatment
    • B01D2259/40Further details for adsorption processes and devices
    • B01D2259/40083Regeneration of adsorbents in processes other than pressure or temperature swing adsorption
    • B01D2259/40088Regeneration of adsorbents in processes other than pressure or temperature swing adsorption by heating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2259/00Type of treatment
    • B01D2259/40Further details for adsorption processes and devices
    • B01D2259/402Further details for adsorption processes and devices using two beds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2259/00Type of treatment
    • B01D2259/40Further details for adsorption processes and devices
    • B01D2259/414Further details for adsorption processes and devices using different types of adsorbents

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Of Gases By Adsorption (AREA)

Abstract

The invention discloses a three-adsorber air separation purification device capable of recovering latent heat and a method thereof. The air separation purifying device comprises three molecular sieve adsorbers working in parallel, an electric heater, an open direct contact type heat exchange box, a heat exchanger, a circulating water pump, a silencer, a waste nitrogen heating control valve, a waste nitrogen cold blowing control valve and the like. One side of the molecular sieve adsorber is respectively connected with a sewage nitrogen heating channel, a sewage nitrogen air cooling and blowing channel and an air outlet channel, and the other side of the molecular sieve adsorber is respectively connected with an air inlet channel, a sewage nitrogen emptying channel and a sewage nitrogen waste heat recovery channel. A pressure relief valve, a pressure increasing valve, an automatic control valve and the like are also arranged between the absorber and the pipeline. Through setting up two circulating water passageways, retrieve the adsorption heat of adsorber and exhaust cold blow dirty nitrogen waste heat respectively, and then reduce the adsorbent temperature, extension adsorber operating time, the latent heat of steam in the cold blow dirty nitrogen can effectively be retrieved to the heat transfer case during direct contact, reduces the electric heater energy consumption.

Description

Three-adsorber air separation purification device capable of recovering latent heat and method thereof
Technical Field
The invention relates to the field of molecular sieve design, in particular to a three-adsorber air separation purification device capable of recovering latent heat.
Background
In the cryogenic air separation system, a process of reducing the content of impurities such as water vapor, carbon dioxide and hydrocarbons in the raw air to a prescribed level is called an air separation purification process, and an apparatus used is called an air separation purification apparatus. However, the energy consumption of the purification process is high and accounts for about 16% of the total energy consumption of the air separation system. The analysis of the whole air separation purification system shows that the waste heat which is not utilized mainly has two parts, namely the adsorption heat of the activated alumina and the molecular sieve in the adsorber, and the high-temperature and high-humidity polluted nitrogen discharged from the cold blowing section of the adsorber. For the heat of adsorption, the working environment of the adsorbent is deteriorated, for example, water vapor is used as a strong adsorption phase, the heat of adsorption is higher than that of carbon dioxide, the temperature of the bed layer is rapidly increased to cause that part of the adsorbed carbon dioxide is desorbed, so that the concentration of the carbon dioxide is increased. For discharged cold blowing waste nitrogen, besides sensible heat, the interior of the discharged cold blowing waste nitrogen also contains a large amount of water vapor, and if the latent heat of the discharged cold blowing waste nitrogen can be recovered, the available residual heat of the system can be greatly increased. However, in the conventional air separation purification system, the influence of adsorption heat is ignored; the system structure is only provided with two molecular sieve adsorbers, one molecular sieve adsorber works for adsorption, the other molecular sieve adsorbs for regeneration, and the difference in time causes that the heat contained in the cold blow nitrogen is difficult to utilize, and the cold blow nitrogen is usually directly discharged to the air, thereby causing energy waste.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a three-adsorber air separation purification device capable of recovering latent heat. The waste heat of adsorption heat and cold blowing nitrogen is fully utilized, the running time of the adsorber is prolonged, the energy input of the heater is reduced, and the energy conservation and consumption reduction of the air separation purification system are realized.
The invention aims to realize the purpose of the invention by the following technical scheme:
a three-adsorber air separation purification device capable of recovering latent heat comprises a first molecular sieve adsorber, a second molecular sieve adsorber, a third molecular sieve adsorber, a first heat exchanger, a first circulating water pump, an electric heater, a second heat exchanger, an open direct contact type heat exchange box, a second circulating water pump, a first branch of a waste nitrogen heating channel, a second branch of the waste nitrogen heating channel, a waste nitrogen cold blowing channel, a waste nitrogen waste heat recovery channel, a waste nitrogen emptying channel, an air outlet channel, an air inlet channel, a first circulating water channel and a second circulating water channel;
the pipeline at one end of the first molecular sieve adsorber is divided into three branches, wherein the first branch is connected with the sewage nitrogen heating channel and is provided with a first automatic control valve, the second branch is connected with the sewage nitrogen cold blowing channel and is provided with a second automatic control valve, the third branch is connected with the air outlet channel and is provided with a third automatic control valve; the pipeline at the other end of the first molecular sieve adsorber is divided into four branches, the first branch and the second branch are respectively connected with an air inlet channel, the first branch is provided with a tenth automatic control valve, the second branch is provided with a first pressure increasing valve, the third branch is provided with a first pressure reducing valve, the fourth branch is provided with an eleventh automatic control valve, the third branch and the fourth branch are connected with an inlet channel of a first three-way valve after being converged, and the other two outlet channels of the first three-way valve are respectively connected with a waste nitrogen gas waste heat recovery channel and a waste nitrogen gas emptying channel; the two ends of the second molecular sieve adsorber and the third molecular sieve adsorber are connected with each channel in the same way as the first molecular sieve adsorber;
a waste nitrogen inlet pipeline entering the air separation purification device is divided into two paths, wherein one path is connected to a waste nitrogen cold blowing channel, and a waste nitrogen cold blowing control valve is arranged on the waste nitrogen cold blowing channel; the other branch is divided into two branches after passing through a waste nitrogen heating control valve, the first branch of a waste nitrogen heating channel is connected with a second heat exchanger, the second branch of the waste nitrogen heating channel is connected with the first heat exchanger, the two branches are connected into the waste nitrogen heating channel after being converged, and the waste nitrogen heating channel is sequentially connected with a sixteenth automatic control valve and an electric heater;
the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber are internally provided with heat exchange coil pipes connected with the first circulating water channel, and double-layer bed bodies formed by activated alumina and molecular sieves are filled among the coil pipes; the first circulating water channel is provided with a first circulating water pump for providing circulating power, and circulating water is divided into three branches in the circulating process, flows into the heat exchange coil pipes in the three molecular sieve adsorbers and is used for taking away heat in the double-layer bed body; the first branch is sequentially connected with a first molecular sieve absorber and a first circulating water valve; the second branch is sequentially connected with a second molecular sieve adsorber and a second circulating water valve; the third branch is sequentially connected with a third molecular sieve adsorber and a third circulating water valve; three branches of the first circulating water channel are converged and then flow through the first heat exchanger to exchange heat with the second branch of the waste nitrogen heating channel;
the second circulating water channel is sequentially connected with a second heat exchanger, an open direct contact type heat exchange box and a second circulating water pump in the circulating process, and circulating water in the second circulating water channel exchanges heat with the first branch of the waste nitrogen heating channel in the second heat exchanger;
the waste heat recovery channel of the waste nitrogen is discharged after passing through the open direct contact type heat exchange box, and directly exchanges heat with circulating water in the open direct contact type heat exchange box;
the tail end of the waste nitrogen gas emptying channel is directly emptied;
air to be purified is introduced from the air inlet channel; the purified air is discharged from the air outlet passage.
Preferably, the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber have the same structural form and respectively comprise a molecular sieve adsorber shell, and a molecular sieve adsorber inlet and a molecular sieve adsorber outlet for the air to be purified to pass in and out are arranged on the molecular sieve adsorber shell; a double-layer bed body is arranged inside the shell of the molecular sieve adsorber, wherein the outer bed body is an activated alumina adsorption bed, and the inner bed body is a molecular sieve adsorption bed; an outer molecular sieve adsorber channel communicated with an inlet of the molecular sieve adsorber is arranged between the outer bed body and the shell, and a central molecular sieve adsorber channel communicated with an outlet of the molecular sieve adsorber is arranged in the center of the inner bed body; the bed body of the outer layer is internally provided with an active alumina adsorption bed internal heat exchange coil, the bed body of the inner layer is internally provided with a molecular sieve adsorption bed internal heat exchange coil, and the active alumina adsorption bed internal heat exchange coil and the molecular sieve adsorption bed internal heat exchange coil are both communicated with a first circulating water channel.
Furthermore, the double-layer bed body is in an internal and external coaxial nested form, the upper side and the lower side of the active alumina adsorption bed and the molecular sieve adsorption bed are closed, and air to be purified can only flow in from the side surface.
Preferably, the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber are operated in parallel, and continuous and low-consumption operation of the purification process is realized by mutual switching.
Preferably, the waste nitrogen at the outlets of the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber is discharged through a waste nitrogen gas emptying channel in the heating desorption process, and is discharged through a waste nitrogen gas waste heat recovery channel in the cold blowing process.
Preferably, the heat exchange coil pipes in the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber respectively control circulation of internal circulating water through a first circulating water valve, a second circulating water valve and a third circulating water valve.
Preferably, the end of the waste nitrogen gas vent passage is provided with a silencer for noise elimination of the vent port.
Preferably, the first heat exchanger and the second heat exchanger are both air-water type heat exchangers.
Another object of the present invention is to provide a method for purifying air in an air separation purification apparatus according to any of the above embodiments, which comprises the steps of:
1) firstly, a first molecular sieve adsorber starts to be in an adsorption state, a second molecular sieve adsorber is in a heating desorption ending state, and a third molecular sieve adsorber is in an adsorption saturation state; through valve switching, the third molecular sieve adsorber finishes pressure relief, and the cold blowing of the second molecular sieve adsorber starts; a circulating water branch connected with the first molecular sieve adsorber is opened, and adsorption heat is transferred to the first heat exchanger under the action of the first circulating water pump; cold blow-off nitrogen discharged by the second molecular sieve adsorber exchanges heat with circulating water in the open direct contact type heat exchange box and is directly exhausted, and the recovered waste heat is transferred to a second heat exchanger under the action of a second circulating water pump; the waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger through a first branch of a waste nitrogen heating channel, and the second branch of the waste nitrogen heating channel exchanges heat with the first heat exchanger; the preheated regeneration sewage nitrogen is converged and then enters an electric heater for further heating, and enters a third molecular sieve adsorber for heating regeneration after the set temperature requirement is met; after the regeneration of the third molecular sieve adsorber is finished, preparing cold blowing by valve switching; after the cold blowing of the second molecular sieve adsorber is finished, the pressure is increased by switching the valve;
2) then, the second molecular sieve adsorber starts to be in an adsorption state, the third molecular sieve adsorber is in a heating desorption ending state, and the first molecular sieve adsorber is in an adsorption saturation state; through valve switching, the first molecular sieve adsorber finishes pressure relief, and the third molecular sieve adsorber starts cold blowing; a circulating water branch connected with the second molecular sieve adsorber is opened, and adsorption heat is transferred to the first heat exchanger under the action of the first circulating water pump; cold blow-off nitrogen discharged by the third molecular sieve adsorber exchanges heat with circulating water in the open direct contact type heat exchange box and is directly exhausted, and the recovered waste heat is transferred to a second heat exchanger under the action of a second circulating water pump; the waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger through a first branch of a waste nitrogen heating channel, and the second branch of the waste nitrogen heating channel exchanges heat with the first heat exchanger; the preheated regeneration sewage nitrogen is converged and then enters an electric heater for further heating, and enters a first molecular sieve adsorber for heating and regeneration after reaching the set temperature requirement; after the regeneration of the first molecular sieve adsorber is finished, preparing cold blowing by valve switching; after the cold blowing of the third molecular sieve adsorber is finished, starting to boost pressure through valve switching;
3) then, the third molecular sieve adsorber starts to be in an adsorption state, the first molecular sieve adsorber is in a heating desorption ending state, and the second molecular sieve adsorber is in an adsorption saturation state; through valve switching, the second molecular sieve adsorber finishes pressure relief, and the first molecular sieve adsorber starts cold blowing; a circulating water branch connected with the third molecular sieve adsorber is opened, and adsorption heat is transferred to the first heat exchanger under the action of the first circulating water pump; cold blow-off nitrogen discharged by the first molecular sieve adsorber exchanges heat with circulating water in the open direct contact type heat exchange box and is directly exhausted, and the recovered waste heat is transferred to a second heat exchanger under the action of a second circulating water pump; the waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger through a first branch of a waste nitrogen heating channel and exchange heat with the first heat exchanger through a second branch of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater for further heating, and enters a second molecular sieve adsorber for heating and regeneration after the set temperature requirement is met; after the regeneration of the second molecular sieve adsorber is finished, preparing cold blowing by valve switching; after the cold blowing of the first molecular sieve adsorber is finished, starting boosting through valve switching;
4) and (4) continuously circulating the steps 1) to 3) to finish the air separation purification.
Preferably, the first circulation water pump, the second circulation water pump and the electric heater are stopped.
The invention has the beneficial effects that: the adsorbent is cooled, so that the adsorption capacity of the adsorbent to impurities such as water vapor, carbon dioxide and the like is increased, and the operation time of the adsorber is prolonged; the designed open type direct contact heat exchange box and the additional device thereof can effectively recover sensible heat of cold blowing nitrogen and latent heat of water vapor; the purification process of the three adsorbers can realize the recovery of the waste heat of cold blowing waste nitrogen and the preheating of regenerated waste nitrogen at the same time period; in general, the invention can prolong the operation time of the adsorber, reduce the power of the electric heater and reduce the energy consumption of the whole air separation purification system.
The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings so as to fully understand the objects, the features and the effects of the present invention.
Drawings
FIG. 1 is a schematic diagram of an air separation purification plant with three adsorbers capable of recovering latent heat according to the present invention.
FIG. 2 is a schematic diagram of the structure of a molecular sieve adsorber of the present invention.
The reference numbers in the figures are: a first molecular sieve adsorber 1, a second molecular sieve adsorber 2, a third molecular sieve adsorber 3, a first heat exchanger 4, a first circulating water pump 5, an electric heater 6, a second heat exchanger 7, an open direct contact heat exchange tank 8, a second circulating water pump 9, a silencer 10, a first automatic control valve 11, a second automatic control valve 12, a third automatic control valve 13, a fourth automatic control valve 14, a fifth automatic control valve 15, a sixth automatic control valve 16, a seventh automatic control valve 17, an eighth automatic control valve 18, a ninth automatic control valve 19, a tenth automatic control valve 20, a first booster valve 21, a first relief valve 22, an eleventh automatic control valve 23, a first three-way valve 24, a twelfth automatic control valve 25, a second booster valve 26, a second relief valve 27, a thirteenth automatic control valve 28, a second three-way valve 29, a fourteenth automatic control valve 30, a third booster valve 31, A third pressure relief valve 32, a fifteenth automatic control valve 33, a third three-way valve 34, a sixteenth automatic control valve 35, a dirty nitrogen heating control valve 36, a dirty nitrogen cold blowing control valve 37, a first circulating water valve 38, a second circulating water valve 39, a third circulating water valve 40, a dirty nitrogen heating channel first branch 41, a dirty nitrogen heating channel second branch 42, a dirty nitrogen heating channel 43, a dirty nitrogen cold blowing channel 44, a dirty nitrogen waste heat recovery channel 45, a dirty nitrogen emptying channel 46, an air outlet channel 47, an air inlet channel 48, a first circulating water channel 49, a second circulating water channel 50, a molecular sieve adsorber inlet 1-1, a molecular sieve adsorber shell 1-2, a molecular sieve adsorber outer channel 1-3, a molecular sieve adsorber central channel 1-4, a molecular sieve adsorber outlet 1-5, an activated alumina adsorption bed 1-6, a molecular sieve adsorber shell 1-2, a molecular sieve adsorber outer channel 1-3, a molecular sieve adsorber central channel 1-4, a molecular sieve adsorber outlet, 1-7 parts of molecular sieve adsorption bed, 1-8 parts of heat exchange coil in active alumina adsorption bed and 1-9 parts of heat exchange coil in molecular sieve adsorption bed.
Detailed Description
The invention is further described in the following with specific embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, a three-adsorber air separation purification device capable of recovering latent heat includes a first molecular sieve adsorber 1, a second molecular sieve adsorber 2, a third molecular sieve adsorber 3, a first heat exchanger 4, a first circulating water pump 5, an electric heater 6, a second heat exchanger 7, an open direct contact heat exchange box 8, a second circulating water pump 9, a silencer 10, a first branch 41 of a waste nitrogen heating channel, a second branch 42 of the waste nitrogen heating channel, a waste nitrogen heating channel 43, a waste nitrogen blowing channel 44, a waste nitrogen waste heat recovery channel 45, a waste nitrogen emptying channel 46, an air outlet channel 47, an air inlet channel 48, a first circulating water channel 49, and a second circulating water channel 50.
The pipeline at one end of the first molecular sieve adsorber 1 is divided into three branches, wherein the first branch is connected with the sewage nitrogen heating channel 43 and is provided with a first automatic control valve 11, the second branch is connected with the sewage nitrogen cold blowing channel 44 and is provided with a second automatic control valve 12, the third branch is connected with the air outlet channel 47 and is provided with a third automatic control valve 13; the pipeline at the other end of the first molecular sieve adsorber 1 is divided into four branches, the first branch and the second branch are respectively connected with an air inlet channel 48, the first branch is provided with a tenth automatic control valve 20, the second branch is provided with a first pressure increasing valve 21, the third branch is provided with a first pressure reducing valve 22, the fourth branch is provided with an eleventh automatic control valve 23, the third branch and the fourth branch are connected with an inlet channel of a first three-way valve 24 after being converged, and the other two outlet channels of the first three-way valve 24 are respectively connected with a waste nitrogen gas waste heat recovery channel 45 and a waste nitrogen gas emptying channel 46; the end of the dirty nitrogen vent channel 46 is vented directly. The end of the dirty nitrogen vent passage 46 is fitted with a silencer 10 for noise abatement of the exhaust.
The two ends of the second molecular sieve adsorber 2 and the third molecular sieve adsorber 3 are connected with each channel in the same way as the first molecular sieve adsorber 1.
A waste nitrogen inlet pipeline entering the air separation purification device is divided into two paths, one path is connected to a waste nitrogen cold blowing channel 44, and a waste nitrogen cold blowing control valve 37 is arranged on the waste nitrogen cold blowing channel 44; the other branch is divided into two branches after passing through the waste nitrogen heating control valve 36, the first branch 41 of the waste nitrogen heating channel is connected with the second heat exchanger 7, the second branch 42 of the waste nitrogen heating channel is connected with the first heat exchanger 4, the two branches are connected into the waste nitrogen heating channel 43 after being converged, and the sixteenth automatic control valve 35 and the electric heater 6 are sequentially connected onto the waste nitrogen heating channel 43.
The first molecular sieve adsorber 1, the second molecular sieve adsorber 2 and the third molecular sieve adsorber 3 are internally provided with heat exchange coil pipes connected with a first circulating water channel 49, and double-layer bed bodies formed by activated alumina and molecular sieves are filled among the coil pipes; the first circulating water channel 49 is provided with a first circulating water pump 5 for providing circulating power, and circulating water is divided into three branches in the circulating process, flows into heat exchange coils in three molecular sieve adsorbers and is used for taking away heat in the double-layer bed body; the first branch is sequentially connected with a first molecular sieve adsorber 1 and a first circulating water valve 38; the second branch is sequentially connected with the second molecular sieve adsorber 2 and a second circulating water valve 39; the third branch is sequentially connected with a third molecular sieve adsorber 3 and a third circulating water valve 40; three branches of the first circulating water passage 49 are merged and then flow through the first heat exchanger 4 to exchange heat with the second branch 42 of the waste nitrogen heating passage.
The second circulating water channel 50 is sequentially connected with the second heat exchanger 7, the open direct contact type heat exchange box 8 and the second circulating water pump 9 in the circulating process, and circulating water in the second circulating water channel 50 exchanges heat with the first branch 41 of the dirty nitrogen heating channel in the second heat exchanger 7;
the waste nitrogen waste heat recovery channel 45 is emptied after passing through the open direct contact type heat exchange box 8, and directly exchanges heat with circulating water in the open direct contact type heat exchange box 8;
air to be purified is introduced from the air inlet passage 48; the purified air is discharged from the air outlet passage 47.
In the air separation purification device, a first molecular sieve adsorber 1, a second molecular sieve adsorber 2 and a third molecular sieve adsorber 3 are connected in parallel for operation, and continuous and low-consumption operation of a purification process is realized by mutual switching. The waste nitrogen at the outlets of the first molecular sieve adsorber 1, the second molecular sieve adsorber 2 and the third molecular sieve adsorber 3 is discharged through a waste nitrogen gas emptying channel 46 in the heating desorption process, and is discharged through a waste nitrogen gas waste heat recovery channel 45 in the cold blowing process. The heat exchange coil pipes in the first molecular sieve adsorber 1, the second molecular sieve adsorber 2 and the third molecular sieve adsorber 3 respectively control the circulation of the circulating water in the first molecular sieve adsorber, the second molecular sieve adsorber and the third molecular sieve adsorber through a first circulating water valve 38, a second circulating water valve 39 and a third circulating water valve 40.
In the invention, the operation efficiency of the air separation purification device is improved and the energy consumption is reduced by two parts, wherein the open direct contact type heat exchange box 8 is used for recovering the waste heat of cold blowing nitrogen, and the circulating water channels 49 on the three molecular sieve adsorbers are used for improving the adsorption capacity of the molecular sieve adsorbers and reducing the power consumption, and the principle is as follows:
in the existing molecular sieve adsorber, air to be purified flows through an activated alumina adsorption bed and a molecular sieve adsorption bed in sequence, and carbon dioxide and water vapor in the air are taken out. The applicant has found through research that the main cause of the problems of adsorption saturation and short operation time is that the judgment of adsorption saturation is inconsistent with the actual judgment. The heat of adsorption of water vapor is about 50kJ/mol, while the heat of adsorption of carbon dioxide is about 30 kJ/mol; and the water vapor is used as a strong adsorption phase, the adsorption heat of the water vapor is higher than that of the carbon dioxide, the temperature of the bed layer is rapidly increased, and part of the adsorbed carbon dioxide is resolved out, so that the concentration of the carbon dioxide is increased. However, when the actual air separation purification system is operated, the concentration of carbon dioxide is used as a judgment standard for judging whether the adsorber is saturated, and when the concentration of carbon dioxide exceeds the standard, the molecular sieve adsorber is considered to be saturated in adsorption and needs to be regenerated. In the conventional air separation purification device, when the molecular sieve adsorber finishes running, the molecular sieve adsorber cannot continuously adsorb carbon dioxide, but still keeps certain water vapor adsorption capacity. In addition, because the adsorbent volume in the adsorber is very huge in actual operation, and active alumina and molecular sieve will inevitably produce the adsorption heat when adsorbing steam or carbon dioxide, when it can not discharge fast, the adsorption heat can pile up inside the adsorber, makes active alumina and molecular sieve adsorbent rapid heating up, worsens the operational environment of adsorbent, reduces the adsorption capacity of adsorbent to impurity such as steam and carbon dioxide. Therefore, it is necessary to remove the heat generated in the molecular sieve adsorber.
In order to better achieve the above purpose, the present invention designs an adsorber structure suitable for heat dissipation for the first molecular sieve adsorber 1, the second molecular sieve adsorber 2, and the third molecular sieve adsorber 3.
As shown in FIG. 2, the molecular sieve adsorbers optimally designed in the invention all comprise a molecular sieve adsorber shell 1-2, and a molecular sieve adsorber inlet 1-1 and a molecular sieve adsorber outlet 1-5 for the air to be purified to enter and exit are arranged on the molecular sieve adsorber shell 1-2; a double-layer bed body is arranged inside the shell 1-2 of the molecular sieve adsorber, wherein the outer bed body is an active alumina adsorption bed 1-6, and the inner bed body is a molecular sieve adsorption bed 1-7; an outer passage 1-3 of the molecular sieve adsorber is communicated with an inlet 1-1 of the molecular sieve adsorber between the outer bed body and the shell, and a central passage 1-4 of the molecular sieve adsorber is communicated with an outlet 1-5 of the molecular sieve adsorber at the center of the inner bed body; the outer bed body is distributed with active alumina adsorption bed inner heat exchange coil pipes 1-8, and the inner bed body is distributed with molecular sieve adsorption bed inner heat exchange coil pipes 1-9. Active alumina adsorbent is filled between 1-8 heat exchange coils in the active alumina adsorbent bed; molecular sieve adsorbent is filled between 1-9 heat exchange coils in the molecular sieve adsorption bed, and a cold source needs to be introduced into the heat exchange coils for heat exchange.
Therefore, if the adsorbent is to be cooled effectively, an effective cooling source needs to be found. The regenerated waste nitrogen from the rectification column is a good choice, the temperature is low, and the temperature needs to be raised. However, if the low-temperature regenerated waste nitrogen directly cools the alumina and the molecular sieve adsorbent, the effect of gas-gas heat exchange is poor, so that the adoption of circulating water for heat transfer is an ideal mode. In the invention, the heat exchange coil pipes 1-8 in the active alumina adsorption bed and the heat exchange coil pipes 1-9 in the molecular sieve adsorption bed are communicated with a circulating water pipeline for heat exchange. In this embodiment, heat exchange coils 1-8 in the activated alumina adsorbent bed and heat exchange coils 1-9 in the molecular sieve adsorbent bed are connected to the same first circulating water channel 49.
In the molecular sieve adsorber, a double-layer bed body is in an internal and external coaxial nested form, the upper and lower sides of an activated alumina adsorption bed 1-6 and a molecular sieve adsorption bed 1-7 are closed, and air to be purified can only flow in from the side surface. Air to be purified enters from an inlet 1-1 of the molecular sieve adsorber and then enters an outer channel 1-3 of the molecular sieve adsorber; then the air enters an active alumina adsorption bed 1-6, and the active alumina firstly adsorbs the air to be purified and has the main function of adsorbing water vapor; then the mixture enters a molecular sieve adsorption bed 1-7, and the molecular sieve adsorbent mainly adsorbs carbon dioxide and water vapor which is not completely removed; after adsorption is finished, purified air enters a central channel 1-4 of the molecular sieve adsorber and is then discharged from an outlet 1-5 of the molecular sieve adsorber. The heat generated in the activated alumina adsorption beds 1-6 and the molecular sieve adsorption beds 1-7 can be taken away by the circulating cooling water in the three branches of the first circulating water channel 49, so that the adsorption capacity of the bed is improved, the carbon dioxide adsorbed in the bed body can be prevented from being desorbed due to adsorption heat, and the judgment result is ensured to be consistent with the actual condition under the condition that the concentration of the carbon dioxide is used as the judgment standard for judging whether the adsorber is saturated or not. The high-temperature water in the first circulating water channel 49 exchanges heat with the regenerated waste nitrogen gas in the first heat exchanger 4, and is cooled again. Therefore, the adsorption heat released by the adsorber is further used for preheating and regenerating the polluted nitrogen, the energy consumption of the heater is reduced, and the air separation purification system can operate efficiently and stably.
In order to improve the heat exchange efficiency, the first heat exchanger 4 and the second heat exchanger 7 are both air-water type heat exchangers.
Based on the device, the air separation purification method of the three-adsorber air separation purification device capable of recovering latent heat can also be provided, and the steps are as follows:
1) firstly, the first molecular sieve adsorber 1 is in an adsorption state, the second molecular sieve adsorber 2 is in a heating desorption ending state, and the third molecular sieve adsorber 3 is in an adsorption saturation state; through valve switching, the third molecular sieve adsorber 3 finishes pressure relief, and the second molecular sieve adsorber 2 starts cold blowing; a circulating water branch connected with the first molecular sieve adsorber 1 is opened, and adsorption heat is transferred to the first heat exchanger 4 under the action of the first circulating water pump 5; cold blow-off nitrogen discharged by the second molecular sieve adsorber 2 is directly exhausted after exchanging heat with circulating water in the open direct contact type heat exchange box 8, and the recovered waste heat is transferred to a second heat exchanger 7 under the action of a second circulating water pump 9; waste nitrogen for heating regeneration is divided into two paths to exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel, and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a third molecular sieve adsorber 3 for heating regeneration after the set temperature requirement is met; after the regeneration of the third molecular sieve adsorber 3 is finished, preparing cold blowing by valve switching; after the cold blowing of the second molecular sieve adsorber 2 is finished, the pressure is increased by switching the valve;
2) then, the second molecular sieve adsorber 2 starts to be in an adsorption state, the third molecular sieve adsorber 3 is in a heating desorption ending state, and the first molecular sieve adsorber 1 is in an adsorption saturation state; through valve switching, the first molecular sieve adsorber 1 finishes pressure relief, and the third molecular sieve adsorber 3 starts cold blowing; a circulating water branch connected with the second molecular sieve adsorber 2 is opened, and adsorption heat is transferred to the first heat exchanger 4 under the action of the first circulating water pump 5; cold blow-off nitrogen discharged by the third molecular sieve adsorber 3 exchanges heat with circulating water in the open direct contact type heat exchange box 8 and is directly exhausted, and the recovered waste heat is transferred to the second heat exchanger 7 under the action of the second circulating water pump 9; waste nitrogen for heating regeneration is divided into two paths to exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel, and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a first molecular sieve adsorber 1 for heating regeneration after reaching the set temperature requirement; after the regeneration of the first molecular sieve adsorber 1 is finished, cold blowing is prepared by valve switching; after the cold blowing of the third molecular sieve adsorber 3 is finished, the pressure is increased by switching the valve;
3) then, the third molecular sieve adsorber 3 starts to be in an adsorption state, the first molecular sieve adsorber 1 is in a heating desorption ending state, and the second molecular sieve adsorber 2 is in an adsorption saturation state; through valve switching, the second molecular sieve adsorber 2 finishes pressure relief, and the first molecular sieve adsorber 1 starts cold blowing; a circulating water branch connected with the third molecular sieve adsorber 3 is opened, and adsorption heat is transferred to the first heat exchanger 4 under the action of the first circulating water pump 5; cold blow-off nitrogen discharged by the first molecular sieve adsorber 1 is directly exhausted after exchanging heat with circulating water in an open direct contact type heat exchange box 8, and the recovered waste heat is transferred to a second heat exchanger 7 under the action of a second circulating water pump 9; the waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a second molecular sieve adsorber 2 for heating regeneration after reaching the set temperature requirement; after the regeneration of the second molecular sieve adsorber 2 is finished, cold blowing is prepared by valve switching; after the cold blowing of the first molecular sieve adsorber 1 is finished, the pressure is increased by switching the valve;
4) and (4) continuously circulating the steps 1) to 3) to finish the air separation purification.
In the air separation purification process, after the heating regeneration process is completed, the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6 stop operating.
In the above steps, the operating states of different molecular sieve adsorbers can be changed by different valve switching operations, and the flow of the valve switching operations in different stages is described in detail as follows:
assuming that the first water circulation pump 5, the second water circulation pump 9 and the electric heater 6 are in the off state in the current time period; the first molecular sieve adsorber 1 starts to be in a working state, the second molecular sieve adsorber 2 is heated and desorbed, the cold blowing is waited for after the heating and desorption, and the third molecular sieve adsorber 3 is adsorbed and not depressurized after the adsorption. Current state of the valve: the third automatic control valve 13, the tenth automatic control valve 20, the thirteenth automatic control valve 28, the sixteenth automatic control valve 35, the waste nitrogen heating control valve 36 and the waste nitrogen cold blowing control valve 37 are opened; the first automatic control valve 11, the second automatic control valve 12, the fourth automatic control valve 14, the fifth automatic control valve 15, the sixth automatic control valve 16, the seventh automatic control valve 17, the eighth automatic control valve 18, the ninth automatic control valve 19, the first pressure increasing valve 21, the first pressure relief valve 22, the eleventh automatic control valve 23, the twelfth automatic control valve 25, the second pressure increasing valve 26, the second pressure relief valve 27, the thirteenth automatic control valve 28, the fourteenth automatic control valve 30, the third pressure increasing valve 31, the third pressure relief valve 32, the fifteenth automatic control valve 33, the first circulating water valve 38, the second circulating water valve 39 and the third circulating water valve 40 are closed;
the first three-way valve 24 is connected with the waste heat recovery channel 45 of the polluted nitrogen, the second three-way valve 29 is connected with the blowdown channel 46 of the polluted nitrogen, and the third three-way valve 34 is connected with the waste heat recovery channel 45 of the polluted nitrogen.
Stage I: the first molecular sieve adsorber 1 is initially in an adsorption state.
1) And (3) the third molecular sieve adsorber 3 starts to release pressure, the third three-way valve 34 turns to the sewage nitrogen gas emptying channel 46, the third pressure relief valve 32 is opened, and after the pressure relief process is finished, the third pressure relief valve 32 is closed to wait for the cold blowing process of the second molecular sieve adsorber 2 to start.
2) And starting the cold blowing process of the second molecular sieve adsorber 2, turning the second three-way valve 29 to the waste nitrogen heat recovery channel 45, and opening the fifth automatic control valve 15. The waste nitrogen gas discharged in the cold blowing process of the second molecular sieve adsorber 2 enters the open direct contact type heat exchange box 8 through the channel 45, exchanges heat with the circulating water in the open direct contact type heat exchange box and is discharged.
3) And starting the heating regeneration process of the third molecular sieve adsorber 3, opening the first circulating water valve 38, the seventh automatic control valve 17 and the fifteenth automatic control valve 33, and starting the operation of the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6. The waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a third molecular sieve adsorber 3 for desorption and regeneration after the set temperature requirement is met. When the heating process is finished, the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6 stop operating, and the first circulating water valve 38 and the seventh automatic control valve 17 are closed.
4) And (3) ending the cold blowing process of the second molecular sieve adsorber 2, closing the fifth automatic control valve 15 and the thirteenth automatic control valve 28, opening the second pressure increasing valve 26, starting pressure increasing of the second molecular sieve adsorber 2, closing the second pressure increasing valve 26 after the pressure increasing is ended, opening the sixth automatic control valve 16 and the twelfth automatic control valve 25, and starting parallel work of the second molecular sieve adsorber 2 and the first molecular sieve adsorber 1. Then the third automatic control valve 13 and the tenth automatic control valve 20 are closed, and the first molecular sieve adsorber 1 finishes the adsorption state.
And stage II: the second molecular sieve adsorber 2 is initially in an adsorption state.
1) The first molecular sieve adsorber 1 starts to release pressure, the first three-way valve 24 turns to the sewage nitrogen gas emptying channel 46, the first pressure relief valve 22 is opened, and when the pressure relief process is finished, the first pressure relief valve 22 is closed to wait for the start of the cold blowing process of the third molecular sieve adsorber 3.
2) And starting the cold blowing process of the third molecular sieve adsorber 3, turning the third three-way valve 34 to the waste heat recovery channel 45 of the waste nitrogen, and opening the eighth automatic control valve 18. The waste nitrogen gas discharged in the cold blowing process of the third molecular sieve adsorber 3 enters the open direct contact type heat exchange box 8 through the channel 45, exchanges heat with the circulating water in the open direct contact type heat exchange box and is discharged.
3) And starting the heating regeneration process of the first molecular sieve adsorber 1, opening the second circulating water valve 39, the first automatic control valve 11 and the eleventh automatic control valve 23, and starting the operation of the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6. The waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a first molecular sieve adsorber 1 for desorption and regeneration after the set temperature requirement is met. When the heating process is finished, the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6 stop operating, and the second circulating water valve 39 and the first automatic control valve 11 are closed.
4) And (3) ending the cold blowing process of the third molecular sieve adsorber 3, closing the eighth automatic control valve 18 and the fifteenth automatic control valve 33, opening the third pressure increasing valve 31, starting the pressure increasing of the third molecular sieve adsorber 3, closing the third pressure increasing valve 31 when the pressure increasing is ended, opening the ninth automatic control valve 19 and the fourteenth automatic control valve 30, and starting the parallel work of the third molecular sieve adsorber 3 and the second molecular sieve adsorber 2. Then the sixth automatic control valve 16 and the twelfth automatic control valve 25 are closed, and the second molecular sieve adsorber 2 finishes the adsorption state.
Stage III: the third molecular sieve adsorber 3 is initially in an adsorption state.
1) The second molecular sieve adsorber 2 starts to release pressure, the second three-way valve 29 is switched to the waste nitrogen gas release passage 46, the second pressure relief valve 27 is opened, and when the pressure release process is finished, the second pressure relief valve 27 is closed. Waiting for the first molecular sieve adsorber 1 to start the cold blowing process.
2) The cold blowing process of the first molecular sieve adsorber 1 is started, the first three-way valve 24 is switched to the waste heat recovery channel 45 of the waste nitrogen, and the second automatic control valve 12 is opened. The waste nitrogen gas discharged in the cold blowing process of the first molecular sieve adsorber 1 enters the open direct contact type heat exchange box 8 through the channel 45, exchanges heat with the circulating water in the open direct contact type heat exchange box and is discharged.
3) The heating regeneration process of the second molecular sieve adsorber 2 is started, the third circulating water valve 40, the fourth automatic control valve 14 and the thirteenth automatic control valve 28 are opened, and the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6 start to operate. The waste nitrogen for heating regeneration is divided into two paths to respectively exchange heat with the second heat exchanger 7 through the first branch 41 of the waste nitrogen heating channel and exchange heat with the first heat exchanger 4 through the second branch 42 of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater 6 for further heating, and enters a second molecular sieve adsorber 2 for desorption and regeneration after the set temperature requirement is met. When the heating process is finished, the first circulating water pump 5, the second circulating water pump 9 and the electric heater 6 stop running, and the third circulating water valve 40 and the fourth automatic control valve 14 are closed.
4) And (3) ending the cold blowing process of the first molecular sieve adsorber 1, closing the second automatic control valve 12 and the eleventh automatic control valve 23, opening the first pressure increasing valve 21, starting pressure increasing of the first molecular sieve adsorber 1, closing the first pressure increasing valve 21 when the pressure increasing is ended, opening the third automatic control valve 13 and the tenth automatic control valve 20, and starting parallel operation of the first molecular sieve adsorber 1 and the third molecular sieve adsorber 3. Then the ninth automatic control valve 19 and the fourteenth automatic control valve 30 are closed, and the adsorption state of the third molecular sieve adsorber 3 is finished.
And entering the stage I again to finish the circulation.
Therefore, the invention can respectively recover the adsorption heat of the adsorber and the waste heat of the discharged cold blowing nitrogen by arranging the two paths of circulating water channels, thereby reducing the temperature of the adsorbent, prolonging the operation time of the adsorber, effectively recovering the latent heat of water vapor in the cold blowing nitrogen by the heat exchange box during direct contact and reducing the energy consumption of the electric heater.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are also included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A three-adsorber air separation purification device capable of recovering latent heat is characterized in that: the device comprises a first molecular sieve adsorber (1), a second molecular sieve adsorber (2), a third molecular sieve adsorber (3), a first heat exchanger (4), a first circulating water pump (5), an electric heater (6), a second heat exchanger (7), an open direct contact type heat exchange box (8), a second circulating water pump (9), a dirty nitrogen heating channel first branch (41), a dirty nitrogen heating channel second branch (42), a dirty nitrogen heating channel (43), a dirty nitrogen cold blowing channel (44), a dirty nitrogen waste heat recovery channel (45), a dirty nitrogen emptying channel (46), an air outlet channel (47), an air inlet channel (48), a first circulating water channel (49) and a second circulating water channel (50);
the pipeline at one end of the first molecular sieve adsorber (1) is divided into three branches, wherein the first branch is connected with a sewage nitrogen heating channel (43), a first automatic control valve (11) is arranged on the first branch, the second branch is connected with a sewage nitrogen cold blowing channel (44), a second automatic control valve (12) is arranged on the second branch, the third branch is connected with an air outlet channel (47), and a third automatic control valve (13) is arranged on the third branch; the pipeline at the other end of the first molecular sieve adsorber (1) is divided into four branches, the first branch and the second branch are respectively connected with an air inlet channel (48), the first branch is provided with a tenth automatic control valve (20), the second branch is provided with a first pressure increasing valve (21), the third branch is provided with a first pressure reducing valve (22), the fourth branch is provided with an eleventh automatic control valve (23), the third branch and the fourth branch are connected with an inlet channel of a first three-way valve (24) after being converged, and the other two outlet channels of the first three-way valve (24) are respectively connected with a waste nitrogen waste heat recovery channel (45) and a waste nitrogen emptying channel (46); the two ends of the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) are connected with each channel in the same way as the first molecular sieve adsorber (1);
a waste nitrogen inlet pipeline entering the air separation purification device is divided into two paths, one path is connected to a waste nitrogen cold blowing channel (44), and a waste nitrogen cold blowing control valve (37) is arranged on the waste nitrogen cold blowing channel (44); the other branch is divided into two branches after passing through a waste nitrogen heating control valve (36), a first branch (41) of a waste nitrogen heating channel is connected with a second heat exchanger (7), a second branch (42) of the waste nitrogen heating channel is connected with a first heat exchanger (4), the two branches are connected into a waste nitrogen heating channel (43) after being converged, and the waste nitrogen heating channel (43) is sequentially connected with a sixteenth automatic control valve (35) and an electric heater (6);
the first molecular sieve adsorber (1), the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) are internally provided with heat exchange coil pipes connected with a first circulating water channel (49), and double-layer bed bodies formed by activated alumina and molecular sieves are filled among the coil pipes; a first circulating water pump (5) for providing circulating power is arranged on the first circulating water channel (49), and circulating water is divided into three branches in the circulating process, flows into heat exchange coils in three molecular sieve adsorbers and is used for taking away heat in the double-layer bed body; the first branch is sequentially connected with a first molecular sieve absorber (1) and a first circulating water valve (38); the second branch is sequentially connected with a second molecular sieve adsorber (2) and a second circulating water valve (39); the third branch is sequentially connected with a third molecular sieve adsorber (3) and a third circulating water valve (40); three branches of the first circulating water channel (49) are converged and then flow through the first heat exchanger (4) to exchange heat with the second branch (42) of the waste nitrogen heating channel;
the second circulating water channel (50) is sequentially connected with a second heat exchanger (7), an open direct contact type heat exchange box (8) and a second circulating water pump (9) in the circulating process, and circulating water in the second circulating water channel (50) exchanges heat with the first branch (41) of the waste nitrogen heating channel in the second heat exchanger (7);
the waste nitrogen waste heat recovery channel (45) is emptied after passing through the open direct contact type heat exchange box (8), and directly exchanges heat with circulating water in the open direct contact type heat exchange box (8);
the tail end of the waste nitrogen gas emptying channel (46) is directly emptied;
air to be purified is introduced from the air inlet passage (48); the purified air is discharged from the air outlet passage (47).
2. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the first molecular sieve adsorber (1), the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) have the same structural form and respectively comprise a molecular sieve adsorber shell (1-2), and a molecular sieve adsorber inlet (1-1) and a molecular sieve adsorber outlet (1-5) for the air to be purified to enter and exit are arranged on the molecular sieve adsorber shell (1-2); a double-layer bed body is arranged inside the shell (1-2) of the molecular sieve adsorber, wherein the outer bed body is an active alumina adsorption bed (1-6), and the inner bed body is a molecular sieve adsorption bed (1-7); an outer passage (1-3) of the molecular sieve adsorber, which is communicated with an inlet (1-1) of the molecular sieve adsorber, is arranged between the outer bed body and the shell, and a central passage (1-4) of the molecular sieve adsorber, which is communicated with an outlet (1-5) of the molecular sieve adsorber, is arranged in the center of the inner bed body; the active alumina adsorption bed is characterized in that an active alumina adsorption bed inner heat exchange coil (1-8) is distributed in the outer bed body, a molecular sieve adsorption bed inner heat exchange coil (1-9) is distributed in the inner bed body, and the active alumina adsorption bed inner heat exchange coil (1-8) and the molecular sieve adsorption bed inner heat exchange coil (1-9) are communicated with a first circulating water channel (49).
3. The latent heat recoverable three-adsorber air separation purification unit of claim 2 further comprising: the double-layer bed body is in an internal and external coaxial nested form, the upper and lower sides of the activated alumina adsorption beds (1-6) and the molecular sieve adsorption beds (1-7) are closed, and air to be purified can only flow in from the side surface.
4. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the first molecular sieve adsorber (1), the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) are connected in parallel to operate, and continuous and low-consumption operation of a purification process is realized by mutual switching.
5. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the waste nitrogen at the outlets of the first molecular sieve adsorber (1), the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) is discharged through a waste nitrogen gas emptying channel (46) in the heating desorption process and is discharged through a waste nitrogen gas waste heat recovery channel (45) in the cold blowing process.
6. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the heat exchange coil pipes in the first molecular sieve adsorber (1), the second molecular sieve adsorber (2) and the third molecular sieve adsorber (3) respectively control circulation of internal circulating water through a first circulating water valve (38), a second circulating water valve (39) and a third circulating water valve (40).
7. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the end of the waste nitrogen blowdown passage (46) is provided with a silencer (10) for noise abatement of the discharge port.
8. The triple adsorber air separation purification unit capable of recovering latent heat of claim 1 further comprising: the first heat exchanger (4) and the second heat exchanger (7) are both air-water type heat exchangers.
9. An air separation purification method of an air separation purification apparatus according to any one of claims 1 to 8, characterized by comprising the steps of:
1) firstly, a first molecular sieve adsorber (1) is in an adsorption state, a second molecular sieve adsorber (2) is in a heating desorption ending state, and a third molecular sieve adsorber (3) is in an adsorption saturation state; through valve switching, the third molecular sieve adsorber (3) completes pressure relief, and the cold blowing of the second molecular sieve adsorber (2) starts; a circulating water branch connected with the first molecular sieve adsorber (1) is opened, and adsorption heat is transferred to the first heat exchanger (4) under the action of a first circulating water pump (5); cold blow-off nitrogen discharged by the second molecular sieve adsorber (2) is directly exhausted after exchanging heat with circulating water in the open direct contact type heat exchange box (8), and the recovered waste heat is transferred to a second heat exchanger (7) under the action of a second circulating water pump (9); waste nitrogen for heating regeneration is divided into two paths to exchange heat with a second heat exchanger (7) through a first branch (41) of a waste nitrogen heating channel, and a second branch (42) of the waste nitrogen heating channel exchanges heat with a first heat exchanger (4); the preheated regeneration sewage nitrogen is converged and then enters an electric heater (6) for further heating, and enters a third molecular sieve adsorber (3) for heating regeneration after reaching the set temperature requirement; after the regeneration of the third molecular sieve adsorber (3) is finished, preparing cold blowing by valve switching; after the cold blowing of the second molecular sieve adsorber (2) is finished, the pressure is increased by switching the valve;
2) then, the second molecular sieve adsorber (2) starts to be in an adsorption state, the third molecular sieve adsorber (3) is in a heating desorption ending state, and the first molecular sieve adsorber (1) is in an adsorption saturation state; through valve switching, the first molecular sieve adsorber (1) completes pressure relief, and the third molecular sieve adsorber (3) starts cold blowing; a circulating water branch connected with the second molecular sieve adsorber (2) is opened, and adsorption heat is transferred to the first heat exchanger (4) under the action of the first circulating water pump (5); cold blow-off nitrogen discharged by the third molecular sieve adsorber (3) is directly exhausted after exchanging heat with circulating water in the open direct contact type heat exchange box (8), and the recovered waste heat is transferred to a second heat exchanger (7) under the action of a second circulating water pump (9); waste nitrogen for heating regeneration is divided into two paths to exchange heat with a second heat exchanger (7) through a first branch (41) of a waste nitrogen heating channel, and a second branch (42) of the waste nitrogen heating channel exchanges heat with a first heat exchanger (4); the preheated regeneration sewage nitrogen is converged and then enters an electric heater (6) for further heating, and enters a first molecular sieve adsorber (1) for heating regeneration after reaching the set temperature requirement; after the regeneration of the first molecular sieve adsorber (1) is finished, preparing cold blowing by valve switching; after the cold blowing of the third molecular sieve adsorber (3) is finished, the pressure is increased by switching the valve;
3) then, the third molecular sieve adsorber (3) starts to be in an adsorption state, the first molecular sieve adsorber (1) is in a heating desorption ending state, and the second molecular sieve adsorber (2) is in an adsorption saturation state; through valve switching, the second molecular sieve adsorber (2) completes pressure relief, and the first molecular sieve adsorber (1) starts cold blowing; a circulating water branch connected with the third molecular sieve adsorber (3) is opened, and adsorption heat is transferred to the first heat exchanger (4) under the action of the first circulating water pump (5); cold blow-off nitrogen discharged by the first molecular sieve adsorber (1) is directly exhausted after exchanging heat with circulating water in an open direct contact type heat exchange box (8), and the recovered waste heat is transferred to a second heat exchanger (7) under the action of a second circulating water pump (9); waste nitrogen for heating regeneration is divided into two paths to exchange heat with a second heat exchanger (7) through a first branch (41) of a waste nitrogen heating channel and exchange heat with a first heat exchanger (4) through a second branch (42) of the waste nitrogen heating channel; the preheated regeneration sewage nitrogen is converged and then enters an electric heater (6) for further heating, and enters a second molecular sieve adsorber (2) for heating and regeneration after reaching the set temperature requirement; after the regeneration of the second molecular sieve adsorber (2) is finished, cold blowing is prepared by valve switching; after the cold blowing of the first molecular sieve adsorber (1) is finished, the pressure is increased by switching the valve;
4) and (4) continuously circulating the steps 1) to 3) to finish the air separation purification.
10. A method of air separation purification according to claim 9, characterized in that: and after the heating regeneration process is finished, the first circulating water pump (5), the second circulating water pump (9) and the electric heater (6) stop operating.
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