CN107803098A - A kind of handling process of VOCs waste gas - Google Patents

A kind of handling process of VOCs waste gas Download PDF

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Publication number
CN107803098A
CN107803098A CN201710909477.5A CN201710909477A CN107803098A CN 107803098 A CN107803098 A CN 107803098A CN 201710909477 A CN201710909477 A CN 201710909477A CN 107803098 A CN107803098 A CN 107803098A
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China
Prior art keywords
waste gas
vocs
absorbent
unit
gas
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CN201710909477.5A
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黄龙
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Beijing Institute of Petrochemical Technology
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Beijing Institute of Petrochemical Technology
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Priority to CN201710909477.5A priority Critical patent/CN107803098A/en
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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
    • B01D53/14Separation 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 absorption
    • B01D53/18Absorbing units; Liquid distributors therefor
    • 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
    • B01D53/14Separation 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 absorption
    • B01D53/1406Multiple stage absorption
    • 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
    • B01D53/14Separation 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 absorption
    • B01D53/1487Removing organic compounds
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2257/00Components to be removed
    • B01D2257/70Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
    • B01D2257/708Volatile organic compounds V.O.C.'s
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2258/00Sources of waste gases
    • B01D2258/02Other waste gases
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Abstract

The invention discloses a kind of handling process of VOCs waste gas, including VOCs removal steps and vent gas treatment step, VOCs removal steps include at least two waste gas absorption units being arranged in series, in the same removal step, absorbent is entered by end waste gas absorption unit, after waste gas enters waste gas absorption unit and contacted with absorbent, the caused absorbing liquid part for being adsorbed with VOCs is recycled back into this waste gas absorption unit as absorbent to use, remaining is recycled back to previous waste gas absorption unit, absorbent as previous waste gas absorption unit uses, this technique has the purification efficiency for improving VOCs simultaneously, reduce the dosage of absorbent, reduce energy consumption and reduce the advantage for absorbing tower height degree;Further, since this technique has carried out recycling to the absorbent in waste gas, thus farthest reduce the dosage of absorbent.

Description

A kind of handling process of VOCs waste gas
Technical field
The invention belongs to technical field of waste gas treatment, and in particular to a kind of handling process of VOCs waste gas.
Background technology
Volatile organic matter (abbreviation VOCs) belongs to air pollutants, in particular to saturated vapour pressure surpasses at normal temperatures and pressures The organic compound of 70.91Pa, boiling point less than 260 DEG C is crossed, its main component is hydro carbons, oxygen hydro carbons, containing halohydrocarbon, nitrogen hydrocarbon and sulphur Hydro carbons etc..On the one hand, most VOCs have toxicity, and it has carcinogenic, teratogenesis, mutagenicity and interference human secretory system to human body The harm of system, and easily with some oxidants in air photochemical reaction occurs for most VOCs, generates photochemical fog, serious shadow Ring crop growth and can be detrimental to health;On the other hand, some VOCs can break fast ozone layer, such as chlorofluorocarbons and chlorine Fluorohydrocarbon;In addition, most VOCs belong to inflammable, explosive class compound, larger potential safety hazard is caused to enterprise's production.Therefore, VOCs The improvement of waste gas shows particularly important.
The main method of processing VOCs waste gas is absorption method, condensation method, membrane separation process, Oxidative demage method and absorption at present Method.Absorption method is mainly using activated carbon as adsorbent, and after absorption reaches VOCs saturations, activated carbon need to use hot blast, steam or change The method of pressure is desorbed, and the steam or hot blast after desorption containing VOCs carry out rectifying, extraction or infiltration evaporation operation, a side again Face, the process route is longer, and operating cost is larger, and the adsorbent bed used in above-mentioned technique is also easy to produce high temperature hotspot, peace be present Full hidden danger;On the other hand, above-mentioned acticarbon easy in inactivation, and secondary pollution be present in the activated carbon after inactivation, especially It is the VOCS waste gas of high concentration, desorption is frequent, and when being adsorbed using activated carbon, energy consumption is high.Condensation method mature technology, The recovery oil product of liquid can intuitively be seen, system support is simple and automatization level is high, but energy consumption is higher, and discharge is difficult to reach Mark, be not suitable for industrial applications.Membrane separation process gas film not yet realizes complete production domesticization, needs import and expensive.Oxidation Destruction method can be divided into directly burning, heat-accumulation combustion and catalysis burning etc., using Oxidative demage method according to the difference of failure mode When, finally VOCs is converted into CO2 emission, greenhouse effects can be triggered, and Oxidative demage method invests higher, floor space It is larger, need to preheat, can also produce secondary pollution in addition.Absorption process has small investment, operating cost low and the spy such as safe and effective Point, and absorption process can realize the recycling of resource, economic performance is good, therefore turns into focus of concern.
The existing main method that VOCs waste gas is handled using absorption process is to be fed directly to inhale by the waste gas containing VOCs Receive tower simultaneously inversely to be contacted with absorbent in absorption tower, then directly drain into waste gas after treatment in air outside, And be expelled directly out the absorbent for being adsorbed with VOCs from absorb the bottom of the tower, the purification efficiency that above-mentioned processing method has VOCs is low, Absorbent dosage is big, causes to drain into that VOCs tail gas in air is not up to standard and serious waste absorbent outside so that the above method Process costs are higher;In addition the above method does not carry out recycling to VOCs, can not realize zero-emission.Therefore, Chinese patent Document CN205216516U discloses the processing unit of VOCs in industrial waste gas a kind of, and the device includes air-cooled heat exchanger, absorbed Tower, secondary heat exchanger, oil-water separation tank, overhead condenser, rectifying column, first-class heat exchanger, heating chamber, separation chamber, evaporative condenser Device and pump, the tower reactor air inlet on absorption tower are connected with the outlet of air-cooled heat exchanger, and absorption tower is stages cycle, and every section of bottom is set There is liquid collecting distributing disc, the outlet of liquid collecting distributing disc connects next section of pump inlet, and absorption tower tower top sets offgas outlet, absorbing tower Kettle extraction pipeline is sequentially connected evaporative condenser and first-class heat exchanger, first-class heat exchanger outlet connection rectifying column inlet, rectifying column Tower top outlet connects oil-water separation tank, oil-water separation tank oil phase connection storage tank, oil-water separation tank aqueous phase outlet connection heating chamber, adds Hot cell connects separation chamber.Above-mentioned processing unit has that VOCs purification efficiencies are high, the advantages such as absorbent dosage is few, and realizes pair VOCs recycling.But the absorption tower of above-mentioned stages cycle design, is not followed to the absorbent in tower reactor absorber portion Ring recycles, and causes fresh absorbent dosage more;Further, since above-mentioned absorption tower inner absorbent connects with VOCs waste gas adverse current Touch so that VOCs waste gas increases step by step with the increase gas-flow resistance that hop count is absorbed in absorption tower, and pressure drop also increases step by step, in order to protect Card waste gas is smoothly discharged from tower top, and this undoubtedly will carry out pressurized treatment to the waste gas of absorption tower entrance, and required energy consumption is larger;With This is simultaneously higher in the height of vertical direction by the absorption tower that absorbing liquid is carried out to counter current contacting with waste gas, is unfavorable for industry Change amplification production;Importantly, agent is partially absorbed by being carried in the gas of row outside said apparatus, if directly outer without processing Row, can cause serious waste to absorbent.
Therefore, how the processing method of existing VOCs waste gas is improved so that improve the same of VOCs purification efficiencies When reduce absorbent dosage and energy consumption, reduce absorb tower height degree be allowed to be more suitable for industrialize it is significant.
The content of the invention
Therefore, the technical problems to be solved by the invention are to overcome existing VOCs waste gas processing methods not improving Absorbent dosage is reduced while VOCs purification efficiencies, reduce energy consumption and reduces absorption tower height degree, and then a kind of VOCs is provided and given up The processing recovery process of gas.
Therefore, the technical scheme that the application takes is,
A kind of handling process of VOCs waste gas, including VOCs removal steps and vent gas treatment step, it is characterised in that warp The gas discharged after the processing of VOCs removal steps is handled again as the pretreatment waste gas of vent gas treatment step, will be through tail gas The directly outer row of gas after processing step processing;
The VOCs removal steps include at least two waste gas absorption units being arranged in series, in the VOCs removal steps In, waste gas is entered by head end waste gas absorption unit, and the waste gas after previous waste gas absorption cell processing is as latter waste gas absorption The pretreatment waste gas of unit, the gas obtained after the waste gas absorption cell processing of end discharge the removal step;Absorbent is by end Waste gas absorption unit enters, after waste gas enters waste gas absorption unit and contacted with absorbent, by caused absorbing liquid one Point be recycled back to this waste gas absorption unit uses as absorbent, and remaining is recycled back to previous waste gas absorption unit, as previous waste gas The absorbent of absorptive unit uses, wherein, a caused absorbing liquid part is recycled back to the head end in head end waste gas absorption unit Waste gas absorption unit, remaining absorbing liquid carries out isolated absorbent, and the isolated absorbent is recycled into end Waste gas absorption unit;
The vent gas treatment step includes at least one tail gas treating unit, waste gas enter tail gas treating unit and with absorption After agent solvent is contacted, the gas obtained after the processing of this tail gas treating unit is discharged into the step;By this vent gas treatment A caused absorbing liquid part is recycled back to this tail gas treating unit in unit, and remaining absorbing liquid carries out isolated absorbent, and The isolated absorbent is recycled to the end waste gas absorption unit of VOCs removal steps.
The vent gas treatment step includes multiple tail gas treating units being arranged in series, and waste gas is by head end tail gas treating unit Into, pretreatment waste gas of the waste gas as latter tail gas treating unit after the processing of previous tail gas treating unit, end tail gas The gas obtained after processing unit processes discharges the step;Absorbent solvent is entered by end tail gas treating unit, and waste gas enters Tail gas treating unit and after being contacted with absorbent solvent, this tail gas treating unit is recycled back to by a caused absorbing liquid part Used as absorbent solvent, remaining is recycled back to previous tail gas treating unit, and the absorbent as previous tail gas treating unit is molten Agent uses, wherein, a caused absorbing liquid part is recycled back to the head end tail gas treating unit in head end tail gas treating unit, its Remaining absorbing liquid carries out isolated absorbent, and the end that the isolated absorbent is recycled into VOCs removal steps is given up Aspiration unit.
In the VOCs removal steps, absorbent is 1-METHYLPYRROLIDONE, N- ethyl pyrrolidones or gamma-butyrolacton In one or more;In the vent gas treatment step, the absorbent solvent is water.
In the VOCs removal steps and vent gas treatment step, remaining absorbing liquid, which is sent into same rectifying column, is divided From VOCs, absorbent solvent and absorbent is obtained, the pressure of the rectifying column is 20~120Kpa, and bottom temperature is 80~210 ℃。
In the vent gas treatment step, it is recycled back to the absorbing liquid of this tail gas treating unit and is recycled back to previous vent gas treatment The mass ratio of the absorbing liquid of unit is (10~300):1;In the vent gas treatment step, the absorbing liquid is being recycled back to tail gas The step of also including being cooled to 5~25 DEG C before processing unit.
In the VOCs removal steps, waste gas contacts with absorbent cross-flow in waste gas absorption unit, wherein, end waste gas Waste gas and absorbent counter current contacting in absorptive unit.
In the VOCs removal steps, it is recycled back to the absorbing liquid of this waste gas absorption unit and is recycled back to previous waste gas absorption The mass ratio of the absorbing liquid of unit is (10~250):1.
In the VOCs removal steps, the absorbing liquid for being adsorbed with VOCs is also wrapped before waste gas absorption unit is recycled back to Include the step of being cooled to -15~25 DEG C;
In the VOCs removal steps, in waste gas absorption unit by the absorbing liquid that this discarded absorptive unit is recycled back to Enter this discarded absorptive unit after the absorbing liquid mixing that latter waste gas absorption unit is recycled back to use as absorbent.
In the VOCs removal steps, in waste gas absorption unit by the absorbing liquid that this discarded absorptive unit is recycled back to The absorbing liquid that latter waste gas absorption unit is recycled back to respectively enters this discarded absorptive unit and used as absorbent.
Technical solution of the present invention, have the following advantages that:
1. the handling process of VOCs waste gas provided by the invention, including VOCs removal steps and vent gas treatment step, VOCs Removal step includes at least two waste gas absorption units being arranged in series, and first, in removal step, VOCs waste gas passes through successively Cross at least two waste gas absorption units being arranged in series so that absorbent fully contacts with VOCs waste gas, such maximizing The VOCs in waste gas is removed, the purification efficiency of VOCs waste gas is improved, reduces the VOCs tail gas amounts being emitted into air;Two Then, in removal step, the caused absorbing liquid part for being adsorbed with VOCs is recycled back to this waste gas absorption unit and made by this technique Used for absorbent, remaining is recycled back to previous waste gas absorption unit, and the absorbent as previous waste gas absorption unit uses, thus Recycling for absorbent is realized, reduces the dosage of absorbent, reduces the operating cost of handling process, due to each useless Absorbing liquid in aspiration unit realizes cycling and reutilization, so that absorption tower can reach minimum liquid-gas ratio;Three, this In technique VOCs removal steps, a caused absorption waste liquid part is recycled back to head end waste gas absorption list in head end waste gas absorption unit Member, remaining absorbs waste liquid and carries out isolated absorbent, and isolated absorbent is recycled into end waste gas absorption unit, VOCs recycling is thus achieved, while also isolated absorbent can be subjected to cycling and reutilization, therefore one can be entered Step reduces the dosage of absorbent, saves process costs, and the outer row of VOC free s absorbing liquids, realizes zero-emission truly Put;Four fundamental rules, after this technique handles VOCs removal steps the gas discharged as vent gas treatment step pretreatment waste gas again Handled, the absorbent that VOCs removal steps end waste gas absorption unit efflux gas is taken out of can be subjected to recycling, Thus the absorbent in efflux gas is can remove, absorbent dosage can be saved, further reduce process costs.
To sum up, this technique has the purification efficiency for improving VOCs, the dosage for reducing absorbent, reduces the excellent of energy consumption simultaneously Gesture.
2. the handling process of VOCs waste gas provided by the invention, in removal step, waste gas is with inhaling in waste gas absorption unit Agent cross-flow contact is received, only by waste gas in the waste gas absorption unit of end and absorbent counter current contacting, thus can reduce VOCs waste gas and exist Gas-flow resistance in absorption tower, pressure drop is reduced, can be to overall work compared to the counter current contacting with waste gas in the prior art and absorbent The less energy consumption of skill;At the same time, by the way that absorbing liquid and waste gas are carried out into adverse current setting, the height on absorption tower is reduced, beneficial to work Industryization amplification production.
3. the handling process of VOCs waste gas provided by the invention, can be as needed in waste gas absorption list in removal step The absorbing liquid being recycled back to by this discarded absorptive unit mixed with the absorbing liquid that latter waste gas absorption unit is recycled back in member laggard Enter this discarded absorptive unit to use as absorbent, also can be by the absorbing liquid being recycled back to by this discarded absorptive unit and latter waste gas The absorbing liquid that absorptive unit is recycled back to respectively enters this discarded absorptive unit and used as absorbent.
Brief description of the drawings
, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical scheme of the prior art The required accompanying drawing used is briefly described in embodiment or description of the prior art, it should be apparent that, in describing below Accompanying drawing is some embodiments of the present invention, for those of ordinary skill in the art, before creative work is not paid Put, other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 is the processing technological flow figure of VOCs waste gas in the embodiment of the present invention 1;
Fig. 2 is the processing technological flow figure of VOCs waste gas in the embodiment of the present invention 2;
Wherein, reference is as follows:
1- circulating pumps;2- heat exchangers;3- head ends absorption tower;4- two-level absorption towers;5- head end tail gas treating absorbing towers;6- tri- Level absorption tower;7- two level tail gas treating absorbing towers.
Embodiment
Technical scheme will be clearly and completely described below, it is clear that described embodiment is this hair Bright part of the embodiment, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not having There is the every other embodiment made and obtained under the premise of creative work, belong to the scope of protection of the invention.In addition, below As long as it is mutual not form conflict can each other for involved technical characteristic in described different embodiments of the present invention With reference to.
For ease of comparing, the waste gas absorption unit used in the following embodiments of the application is absorption tower, specially gravity type Absorption tower or deflector type hypergravity absorption tower, in other embodiments, as long as other devices can also be used to realize Its function, in addition, being cooled in following embodiments using heat exchanger to the absorbing liquid;Using circulating pump to the suction Receive liquid and carry out circular treatment.
In the present invention, absorbent enters from the top of waste gas absorption unit.
In order to save the process costs of processing, the preferably number of waste gas absorption unit is 3~6, more preferably waste gas absorption The number of unit is 3~5.The quantity of waste gas absorption unit is more, and VOCs contents are lower in the purified gas of discharge, fresh absorption Agent dosage is fewer, and now cost and operation energy consumption will improve.
The waste gas absorption unit being arranged in series can be each absorption tower individually arrange, can also by absorption tower according to Order from low to high is integrated in an overall space and placed, and saves device space.
Cross-flow passes in the present invention refer to that the flow direction angle of waste gas and absorbent is also not equal to 180 degree not equal to 0, But certain angle is presented, and in the present invention, it is preferred to angle is 60-120 degree, more preferably 80-100 degree.In the present invention Cross-flow passes can reduce the problem of droop loss is excessive in multitower absorption process, while can also significantly save the device space.
Embodiment 1
The total concentration that VOCs waste gas treatment process as shown in Figure 1 contains to certain chemical enterprise is used as 10000mg/m3's The mix waste gas of dichloromethane and acetone is handled, and detailed process is as follows:
In the present embodiment, VOCs refers specifically to dichloromethane and acetone.
Waste gas treatment process of the present embodiment containing dichloromethane and acetone includes VOCs removal steps and vent gas treatment step, VOCs removal steps include the waste gas absorption unit of two series connection, i.e. head end absorption tower 3 and two-level absorption tower in the present embodiment 4, vent gas treatment step includes a tail gas treating unit, i.e. head end tail gas treating absorbing tower 5.
In VOCs removal steps, absorbent is specially 1-METHYLPYRROLIDONE, and 1-METHYLPYRROLIDONE is inputted to two Level absorption tower 4, is contacted, head end absorption tower 3 into the waste gas in head end absorption tower 3 with the absorbent cross-flow in head end absorption tower 3 The volume ratio of absorbent and the waste gas containing dichloromethane and acetone be 1:60 so that dichloromethane is enriched in N- methylpyrroles In alkanone, the waste gas after head end absorption tower 3 is handled then is delivered to two level as the pretreatment waste gas of two-level absorption tower 4 and inhaled Receive in tower 4, be adsorbed with dichloromethane caused by head end absorption tower 5 and an absorbing liquid part for acetone is conveyed by circulating pump 1 To heat exchanger, and -15 DEG C are cooled in heat exchanger, the absorbing liquid after cooling in heat exchanger then is recycled back into head end absorbs Tower 3 uses as absorbent, and remaining absorbing liquid is sent into rectifying column and separated, in absorbing liquid caused by head end absorption tower 3, It is 250 that the absorbing liquid on head end absorption tower 3, which is recycled back to, with the mass ratio of the absorbing liquid separated:1.
Waste gas after head end absorption tower 3 is handled is delivered in two-level absorption tower 4, and with the N- in two-level absorption tower 4 Methyl pyrrolidone counter current contacting, the volume ratio of absorbent and the waste gas containing dichloromethane and acetone in two-level absorption tower 4 For 1:60, the caused absorbing liquid for being adsorbed with dichloromethane and acetone is delivered to heat exchanger by circulating pump 1 and is cooled to 25 DEG C, And the absorbing liquid part after cooling is recycled back to two-level absorption tower 4 as absorbent and used, remaining is recycled back to head end absorption tower 3 Absorbent as head end absorption tower 3 is used, and in the present embodiment, the absorbing liquid and circulation for being recycled back to two-level absorption tower 4 are turned one's head The mass ratio for holding the absorbing liquid on absorption tower 3 is 50:1.
Waste gas after two-level absorption tower 4 is handled is delivered in head end tail gas treating absorbing tower 5, in this step, inhaled It is specially water to receive agent solvent, water is inputted to head end tail gas treating absorbing tower 5, into head end tail gas treating absorbing tower 5 Waste gas and the water counter current contacting in head end tail gas treating absorbing tower 5 so that the 1-METHYLPYRROLIDONE in waste gas is enriched in water, Then by the directly outer row of the waste gas handled through head end tail gas treating absorbing tower 5;The caused suction in head end tail gas treating absorbing tower 5 An attached liquid part is delivered to heat exchanger by circulating pump 1, and 5 DEG C are cooled in heat exchanger, after then cooling in heat exchanger Absorbing liquid be recycled back to head end tail gas treating absorbing tower 5 as absorbent solvent and use, remaining absorbing liquid and VOCs removal steps Separated in the rectifying column that remaining absorbing liquid in head end absorption tower is delivered in VOCs removal steps respectively, collected in tower reactor 1-METHYLPYRROLIDONE is obtained, and it is delivered to heat exchanger using circulating pump 1, and is conveyed after being cooled to 10 DEG C in heat exchanger To two-level absorption tower 4, as the absorbent of two-level absorption tower 4, in the overhead extraction dichloromethane and water of rectifying column, the rectifying column Pressure be 120Kpa, bottom temperature 80.In absorbing liquid caused by head end tail gas treating absorbing tower 5, head end tail gas is recycled back to It is 300 that the absorbing liquid on absorption tower 5, which is handled, with the mass ratio of the absorbing liquid separated:1.
In the present embodiment, VOCs removal steps are that the absorbing liquid and two on head end absorption tower is recycled back to by head end absorption tower The absorbing liquid that level absorption tower is recycled back to head end absorption tower enters head end absorption tower as absorption from the both sides on head end absorption tower respectively Agent uses.
The purified gas containing dichloromethane after head end tail gas treating absorbing tower 5 is handled directly is arranged outside, after measured, The total content of dichloromethane and acetone is 7.5mg/m in outer waste air3, meet discharge standard;And the present embodiment exhaust-gas treatment work The liquid-gas ratio of 1-METHYLPYRROLIDONE and the waste gas containing dichloromethane and acetone is 0.23L/m in skill3;In addition, in efflux gas The content of 1-METHYLPYRROLIDONE is 0.05mg/m3.Waste gas pressure drop sum behind the absorption tower of the present embodiment is 3.6kpa.
In the present embodiment, also dichloromethane and acetone will can be contained after head end tail gas treating absorbing tower 5 is handled Waste gas outside drain into charcoal absorption-desorption apparatus, the dichloromethane in waste gas and acetone can further be removed, in other realities Apply in example, also can be by the directly outer row of the waste gas containing dichloromethane and acetone after head end tail gas treating absorbing tower 5 is handled To photochemical catalyst oxidation unit, plasma waste gas decomposer, the dichloromethane in waste gas and acetone are further removed.
Embodiment 2
VOCs waste gas treatment process as shown in Figure 2 is used to contain concentration to certain chemical enterprise for 81000mg/m3Acetone Waste gas is handled, and detailed process is as follows:
In the present embodiment, VOCs refers specifically to acetone.
Waste gas treatment process of the present embodiment containing acetone includes VOCs removal steps and vent gas treatment step, in the present embodiment Middle VOCs removal steps include the waste gas absorption unit of three series connection, i.e. head end absorption tower 3, two-level absorption tower 4 and three-level absorbs Tower 6, vent gas treatment step include two tail gas treating units being arranged in series, i.e. head end tail gas treating absorbing tower 5 and two level tail Gas disposal absorption tower 7.
In VOCs removal steps, absorbent is specially N- ethyl pyrrolidones, and N- ethyl pyrrolidones are inputted to three Level absorption tower 6, is contacted, head end absorption tower 3 into the waste gas in head end absorption tower 3 with the absorbent cross-flow in head end absorption tower 3 The volume ratio of absorbent and the waste gas containing acetone be 1:55 so that acetone is enriched in N- ethyl pyrrolidones, then will Waste gas after head end absorption tower 3 is handled is delivered in two-level absorption tower 4 as the pretreatment waste gas of two-level absorption tower 4, in head The absorbing liquid part that acetone is adsorbed with caused by the absorption tower 3 of end is delivered to heat exchanger by circulating pump, and is dropped in heat exchanger Then absorbing liquid after cooling in heat exchanger is recycled back to head end absorption tower 3 as absorbent and used by temperature to -5 DEG C, remaining suction Receive and separated in liquid feeding rectifying column, in absorbing liquid caused by head end absorption tower 3, be recycled back to the absorbing liquid on head end absorption tower 3 Mass ratio with the absorbing liquid separated is 10:1.
Waste gas after head end absorption tower 3 is handled is delivered in two-level absorption tower 4, and the N- with two-level absorption tower 4 Ethyl pyrrolidone cross-flow contacts, and the volume ratio of the absorbent of two-level absorption tower 4 and the waste gas containing acetone is 1:60, by caused by The absorbing liquid for being adsorbed with acetone is delivered to heat exchanger by circulating pump and is cooled to 12 DEG C, and the absorbing liquid part after cooling is followed Loopback two-level absorption tower 4 uses as absorbent, and remaining is recycled back to head end absorption tower 3 makes as the absorbent on head end absorption tower 3 With, in the present embodiment, the mass ratio of the absorbing liquid for being recycled back to two-level absorption tower 4 and the absorbing liquid for being recycled back to head end absorption tower 3 For 10:1.
Waste gas after two-level absorption tower 4 is handled is delivered in three-level absorption tower 6, and with the N- in three-level absorption tower 6 The volume ratio of ethyl pyrrolidone counter current contacting, the absorbent on three-level absorption tower 6 and the waste gas containing acetone is 1:60, by caused by The absorbing liquid for being adsorbed with acetone is delivered to heat exchanger by circulating pump and is cooled to 20 DEG C, and the absorbing liquid part after cooling is followed Loopback three-level absorption tower 6 uses as absorbent, and remaining is recycled back to two-level absorption tower 4 makes as the absorbent of two-level absorption tower 4 With, in the present embodiment, the mass ratio of the absorbing liquid for being recycled back to three-level absorption tower 6 and the absorbing liquid for circulating two level end absorption tower 4 For 80:1.
Waste gas after three-level absorption tower 6 is handled is delivered in head end tail gas treating absorbing tower 5, in this step, inhaled It is specially water to receive agent solvent, water is inputted to two level tail gas treating absorbing tower 7, into head end tail gas treating absorbing tower 5 Waste gas and the water counter current contacting in head end tail gas treating absorbing tower 5 so that the N- ethyl pyrrolidones in waste gas are enriched in water, Then the waste gas handled through head end tail gas treating absorbing tower 5 is delivered to two level tail gas treating absorbing tower 7, in head end vent gas treatment A caused adsorption liquid part is delivered to heat exchanger by circulating pump 1 in absorption tower 5, and 25 DEG C are cooled in heat exchanger, then Absorbing liquid after in heat exchanger cooling is recycled back into head end tail gas treating absorbing tower 5 as absorbent solvent to use, remaining suction Receive the rectifying column being delivered to after liquid merges with remaining absorbing liquid in VOCs removal step head ends absorption tower 3 in VOCs removal steps In separated, collect to obtain N- ethyl pyrrolidones in tower reactor, and it is delivered into heat exchanger using circulating pump 1, and changing Three-level absorption tower 6 is delivered to after 10 DEG C are cooled in hot device, as the absorbent on three-level absorption tower 6, is adopted in the tower top of rectifying column Go out acetone and water, the pressure of the rectifying column is 20Kpa, and bottom temperature is 210 DEG C.Inhaled caused by head end tail gas treating absorbing tower 5 Receive in liquid, it is 50 to be recycled back to the absorbing liquid of head end tail gas treating absorbing tower 5 with the mass ratio of the absorbing liquid separated:1.
Waste gas after head end tail gas treating absorbing tower 5 is handled is delivered in two level tail gas treating absorbing tower 7, into two Waste gas in level tail gas treating absorbing tower 7 and the water counter current contacting in two level tail gas treating absorbing tower 7 so that the N- second in waste gas Base pyrrolidones is enriched in water, is then directly arranged the waste gas handled through two level tail gas treating absorbing tower 7 outside, in two level tail gas A caused adsorption liquid part is delivered to heat exchanger by circulating pump 1 in processing absorption tower 7, and 25 DEG C are cooled in heat exchanger, Then the absorbing liquid after in heat exchanger cooling is recycled back into two level tail gas treating absorbing tower 7 as absorbent solvent to use, its Remaining absorbing liquid is recycled back to head end tail gas treating absorbing tower 5 and used as absorbent solvent, in the present embodiment, is recycled back to two level tail The mass ratio of absorbing liquid of the absorbing liquid on gas disposal absorption tower 7 with being recycled back to head end tail gas treating absorbing tower 5 is 10:1.
In the present embodiment, VOCs removal steps are that the absorbing liquid and two on head end absorption tower is recycled back to by head end absorption tower Level absorption tower uses after being recycled back to the absorbing liquid mixing on head end absorption tower into head end absorption tower as absorbent;Absorbed by two level Tower is recycled back to the absorbing liquid of two-level absorption tower and three-level absorption tower be recycled back to two-level absorption tower absorbing liquid mix after enter two level Absorption tower uses as absorbent.
By the directly outer row of the purified gas containing acetone after two level tail gas treating absorbing tower 7 is handled, after measured, outer row The content of acetone is 4mg/m in waste gas3, meet discharge standard;And N- ethyl pyrrolidones in the present embodiment waste gas treatment process Liquid-gas ratio with the waste gas containing acetone is 0.16L/m3;In addition, the content of N- ethyl pyrrolidones is in efflux gas 0.03mg/m3
Comparative example 1
Use the total concentration that the VOCs processing units in patent CN205216516U contain to certain chemical enterprise for 10000mg/m3Dichloromethane and the mix waste gas of acetone handled, in this comparative example, VOCs refers specifically to dichloromethane And acetone, absorbent are specially 1-METHYLPYRROLIDONE, the purified gas after the processing of above-mentioned processing unit is measured, passed through Determine, the total content of dichloromethane and acetone is 36mg/m in outer waste air3;In waste gas treatment process 1-METHYLPYRROLIDONE with The liquid-gas ratio of waste gas containing dichloromethane and acetone is 5.0L/m3;In addition, the content of 1-METHYLPYRROLIDONE is in efflux gas 102mg/m3, absorbent 1-METHYLPYRROLIDONE loses larger and total VOCS contents and reaches 138mg/m3(dichloromethane, third Ketone and 1-METHYLPYRROLIDONE concentration summation), beyond discharge standard.This comparative example waste gas total pressure drop after processing unit is 6.6KPa。
To sum up, compared with comparative example 1, the waste gas treatment process through the embodiment of the present invention 1 handles obtained N- methylpyrroles The liquid-gas ratio of alkanone and dichloromethane is smaller, it follows that the amount for the absorbent that the handling process of the present invention uses is smaller, is saving About cost while be more used in industrialized production;In addition, absorbed after the embodiment of the present invention is handled in the purified gas of outer row Agent dosage is less, and qualified discharge can be achieved.
Obviously, above-described embodiment is only intended to clearly illustrate example, and is not the restriction to embodiment.It is right For those of ordinary skill in the art, can also make on the basis of the above description it is other it is various forms of change or Change.There is no necessity and possibility to exhaust all the enbodiments.And the obvious change thus extended out or Among changing still in the protection domain of the invention.

Claims (10)

1. a kind of handling process of VOCs waste gas, including VOCs removal steps and vent gas treatment step, it is characterised in that through VOCs The gas discharged after removal step processing is handled again as the pretreatment waste gas of vent gas treatment step, will be through vent gas treatment The directly outer row of gas after step process;
The VOCs removal steps include at least two waste gas absorption units being arranged in series, in the VOCs removal steps, Waste gas is entered by head end waste gas absorption unit, and the waste gas after previous waste gas absorption cell processing is as latter waste gas absorption unit Pretreatment waste gas, the gas obtained after the waste gas absorption cell processing of end discharges the removal step;Absorbent is by end waste gas Absorptive unit enters, and after waste gas enters waste gas absorption unit and contacted with absorbent, a caused absorbing liquid part is followed Loopback this waste gas absorption unit uses as absorbent, and remaining is recycled back to previous waste gas absorption unit, as previous waste gas absorption The absorbent of unit uses, wherein, a caused absorbing liquid part is recycled back to the head end waste gas in head end waste gas absorption unit Absorptive unit, remaining absorbing liquid carries out isolated absorbent, and the isolated absorbent is recycled into end waste gas Absorptive unit;
The vent gas treatment step includes at least one tail gas treating unit, and waste gas enters tail gas treating unit and molten with absorbent After agent is contacted, the gas obtained after the processing of this tail gas treating unit is discharged into the step;By this tail gas treating unit In a caused absorbing liquid part be recycled back to this tail gas treating unit, remaining absorbing liquid carries out isolated absorbent, and by institute State the end waste gas absorption unit that isolated absorbent is recycled to VOCs removal steps.
2. the handling process of VOCs waste gas according to claim 1, it is characterised in that the vent gas treatment step includes more The individual tail gas treating unit being arranged in series, waste gas are entered by head end tail gas treating unit, after the processing of previous tail gas treating unit Pretreatment waste gas of the waste gas as latter tail gas treating unit, the gas discharge obtained after the processing of end tail gas treating unit should Step;Absorbent solvent is entered by end tail gas treating unit, and waste gas enters tail gas treating unit and carried out with absorbent solvent After contact, a caused absorbing liquid part is recycled back to this tail gas treating unit and used as absorbent solvent, remaining is recycled back to Previous tail gas treating unit, the absorbent solvent as previous tail gas treating unit use, wherein, in head end tail gas treating unit A caused absorbing liquid part is recycled back to the head end tail gas treating unit, and remaining absorbing liquid carries out isolated absorbent, and The isolated absorbent is recycled to the end waste gas absorption unit of VOCs removal steps.
3. the handling process of VOCs waste gas according to claim 1 or 2, it is characterised in that in the VOCs removal steps In, absorbent is the one or more in 1-METHYLPYRROLIDONE, N- ethyl pyrrolidones or gamma-butyrolacton;In the tail gas In processing step, the absorbent solvent is water.
4. the handling process of the VOCs waste gas according to claim any one of 1-3, it is characterised in that removed in the VOCs In step and vent gas treatment step, remaining absorbing liquid, which is sent into same rectifying column, carries out isolated VOCs, absorbent solvent And absorbent, the pressure of the rectifying column is 20~120Kpa, and bottom temperature is 80~210 DEG C.
5. the handling process of the VOCs waste gas according to claim any one of 1-4, it is characterised in that in the vent gas treatment In step, the mass ratio for being recycled back to absorbing liquid of the absorbing liquid of this tail gas treating unit with being recycled back to previous tail gas treating unit is (10~300):1;In the vent gas treatment step, the absorbing liquid also includes being cooled to before tail gas treating unit is recycled back to 5~25 DEG C of the step of.
6. the handling process of the VOCs waste gas according to claim any one of 1-5, it is characterised in that removed in the VOCs In step, waste gas contacts with absorbent cross-flow in waste gas absorption unit, wherein, waste gas and absorbent in the waste gas absorption unit of end Counter current contacting.
7. the handling process of the VOCs waste gas according to claim any one of 1-6, it is characterised in that removed in the VOCs In step, the mass ratio for being recycled back to absorbing liquid of the absorbing liquid of this waste gas absorption unit with being recycled back to previous waste gas absorption unit is (10~250):1.
8. the handling process of the VOCs waste gas according to claim any one of 1-7, it is characterised in that
In the VOCs removal steps, the absorbing liquid for being adsorbed with VOCs also includes drop before waste gas absorption unit is recycled back to The step of temperature is to -15~25 DEG C.
9. the handling process of the VOCs waste gas according to claim any one of 1-8, it is characterised in that removed in the VOCs In step, the absorbing liquid being recycled back in waste gas absorption unit by this discarded absorptive unit is recycled back to latter waste gas absorption unit Absorbing liquid mixing after enter this discarded absorptive unit and used as absorbent.
10. the handling process of the VOCs waste gas according to claim any one of 1-9, it is characterised in that gone in the VOCs Except in step, the absorbing liquid and latter waste gas absorption unit that are recycled back in waste gas absorption unit by this discarded absorptive unit circulate The absorbing liquid returned respectively enters this discarded absorptive unit and used as absorbent.
CN201710909477.5A 2017-09-29 2017-09-29 A kind of handling process of VOCs waste gas Pending CN107803098A (en)

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Application publication date: 20180316