CN112830535B - Alkali decrement wastewater recovery process for microfiber leather - Google Patents

Alkali decrement wastewater recovery process for microfiber leather Download PDF

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Publication number
CN112830535B
CN112830535B CN202110069892.0A CN202110069892A CN112830535B CN 112830535 B CN112830535 B CN 112830535B CN 202110069892 A CN202110069892 A CN 202110069892A CN 112830535 B CN112830535 B CN 112830535B
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tank
concentrated solution
ethylene glycol
wastewater
water
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CN112830535A (en
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刘坤
王众
王金舟
张景铸
孟繁昌
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Yantai Dongjie Environmental Protection Machinery Engineering Co ltd
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Yantai Dongjie Environmental Protection Machinery Engineering Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/34—Nature of the water, waste water, sewage or sludge to be treated from industrial activities not provided for in groups C02F2103/12 - C02F2103/32
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/08—Multistage treatments, e.g. repetition of the same process step under different conditions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Water, Waste Water Or Sewage (AREA)

Abstract

The invention relates to a process for recycling alkali decrement wastewater of microfiber leather, and belongs to the field of recycling wastewater in microfiber synthetic leather production. The method comprises the following steps: step one, alkali decrement wastewater flowing out of an alkali decrement wastewater tank enters a wastewater evaporator for primary evaporation, top steam enters a first condenser for condensation to become water for recovery, and bottom wastewater concentrate enters a concentrate tank; secondly, secondarily evaporating the waste water concentrated solution in the concentrated solution tank in the first step, and condensing the top steam through a second condenser to obtain crude glycol; and step three, the crude glycol obtained in the step two enters an ethylene glycol rectifying tower for rectification, water obtained in the early stage of rectification is recycled to the water tank, middle distillate is obtained in the middle stage of rectification and enters the middle distillate tank, and the ethylene glycol is obtained in the later stage of rectification. The beneficial effects of the invention are: the process for recovering the wastewater does not need to add any auxiliary agent, active carbon or membrane technology, has simple flow, good treatment effect and recycling, and saves the enterprise cost.

Description

Alkali decrement wastewater recovery process for microfiber leather
Technical Field
The invention relates to a process for recycling alkali decrement wastewater of microfiber leather, and belongs to the field of recycling wastewater in microfiber synthetic leather production.
Background
In the production of synthetic leather, the decrement technology is a specific process for producing microfiber leather. The bicomponent sea-island fiber formed in the spinning step is subjected to a weight reduction technique to remove the continuous phase of the sea-island fiber, thereby obtaining a microfiber consisting of dispersed phases. The superfine fiber and the release property are the key points of the simulation and the softening of the synthetic leather.
The alkali reduction method is a common sea-island structure chemical stripping method for fixed island composite superfine fibers. The figured fiber is usually in a nylon (PA)/polyester fiber (COPET) structure, the COPET is a continuous phase component, and only by hydrolyzing and dissolving the COPET, a single dispersed phase component, namely the required superfine fiber, can be obtained. The alkali decrement is generally that sea island fiber is put into NaOH solution with certain concentration and temperature, water-soluble component COPET is cracked and dissolved to form carboxylic acid and ethylene glycol, and the carboxylic acid reacts with sodium hydroxide to form water-soluble sodium carboxylate. Therefore, the alkali weight reduction wastewater mainly comprises the following components: sodium terephthalate, ethylene glycol, a small amount of sodium hydroxide and water. At present, relevant researches are carried out in China aiming at treating alkali-reduction wastewater.
The Chinese patent with publication number CN102910778 discloses a terylene alkali-reduction water resource recovery process, which uses industrial concentrated hydrochloric acid as an alkali-reduction wastewater neutralizer, uses a cation exchange membrane and uses a freezing and cooling method to extract glycol.
Chinese patent publication No. CN105753687 discloses a method for obtaining large-particle terephthalic acid crystals from alkali-minimization wastewater, which comprises using aluminum chlorohydrol as a neutralizer of alkali-minimization wastewater, filtering with activated carbon, adding terephthalic acid into the clear liquid to obtain a solid-liquid mixture, and press-filtering with a filter press to recover terephthalic acid particles.
Chinese patent publication No. CN107628665 discloses a catalytic oxidation treatment method of alkali-reduced wastewater, which uses charcoal, nitric acid, FeSO4·7H2O, absolute ethanol, KBH4Solution, Na2S2O8And the materials are adopted, so that the effect of reaching the standard of wastewater discharge is achieved.
The process introduced in the above patent document can make the alkali reduction wastewater discharge reach the standard, but the process is complicated, the investment is large, the introduction of reagents and strong acids, the use of membrane technology, and the operation cost is high. At present, the control of dangerous chemicals is increasingly strict, and the solvent ethylene glycol in the wastewater needs to be recycled in the production of microfiber leather, so a simple alkali-reduction wastewater treatment method needs to be developed to reduce the emission of pollutants, recycle the solvent ethylene glycol in the wastewater in the production of microfiber leather and meet the production requirements of microfiber synthetic leather.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a process for recovering alkali-reduced wastewater of microfiber leather.
The technical scheme for solving the technical problems is as follows:
a microfiber leather alkali decrement wastewater recovery process comprises the following steps:
step one, alkali decrement waste water flowing out of an alkali decrement waste water tank enters a waste water evaporator for primary evaporation, the waste water evaporator is normal pressure equipment, the top temperature of the waste water evaporator is the boiling point of water under normal pressure, the temperature is 100-105 degrees at the moment, and top steam enters a first condenser to be changed into water to be recycled into a first recycling water tank for production and recycling; the concentrated solution of the bottom wastewater enters a concentrated solution tank;
step two, when the total amount of the waste water concentrated solution in the concentrated solution tank in the step one reaches the design amount, sucking the waste water concentrated solution into a concentrated solution evaporation tank by using a vacuum system and carrying out secondary evaporation, controlling the temperature to be 100-105 degrees, condensing top steam by using a second condenser to obtain crude glycol, entering the crude glycol tank for temporary storage, and periodically discharging residues in the concentrated solution evaporation tank through a drain valve; discharging sodium terephthalate in the wastewater from the bottom of the concentrated solution evaporation tank, further treating to obtain a pure product, or sending the pure product to a hazardous wastewater treatment center for disposal;
step three, the crude glycol temporarily stored in the crude glycol tank in the step two enters an ethylene glycol rectifying tower for rectification, the temperature is lower than 105 degrees in the initial stage of rectification, water is obtained after condensation by a third condenser, and the water is recovered to a second recovery water tank under the control of a valve; the temperature in the middle stage of rectification is 105-140 degrees, middle fraction ethylene glycol and water are obtained after the middle fraction ethylene glycol and the water are condensed by a third condenser, and the middle fraction ethylene glycol and the water are controlled by a valve and enter a middle fraction tank; the temperature in the later stage of rectification is 140-150 degrees, ethylene glycol is obtained after condensation by a third condenser, the ethylene glycol enters an ethylene glycol tank under the control of a valve, and residues are periodically discharged from an ethylene glycol rectifying tower through a blow-down valve.
Preferably, the concentrated solution evaporation tank and the ethylene glycol rectification tower in the second step are both negative pressure equipment, the ethylene glycol is arranged at the top under vacuum, the boiling point of the ethylene glycol is about 105 ℃, the second condenser is communicated with the concentrated solution evaporation tank, the second condenser is vacuumized by a vacuum system, the concentrated solution tank is normal pressure equipment, a valve between the concentrated solution tank and the concentrated solution evaporation tank is opened, and the liquid in the concentrated solution tank is absorbed into the concentrated solution evaporation tank under the pressure difference.
Preferably, the concentration of the ethylene glycol obtained in the third step is 92-98%.
The invention has the beneficial effects that: the process for recovering the wastewater does not need to add any auxiliary agent, active carbon or membrane technology, has simple flow, good treatment effect, strong operability, 98 percent reduction of the wastewater, less investment and low operating cost, recovers water and glycol while treating the wastewater, returns the wastewater to a workshop for cyclic utilization, saves resources for enterprises and reduces the cost.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
As shown in fig. 1, the process for recovering alkali-reduced wastewater of microfiber leather comprises the following steps:
step one, alkali decrement waste water flowing out of an alkali decrement waste water tank enters a waste water evaporator for primary evaporation, the waste water evaporator is normal pressure equipment, the top temperature of the waste water evaporator is the boiling point of water under normal pressure, the temperature is 100-105 degrees at the moment, and top steam enters a first condenser to be changed into water to be recycled into a first recycling water tank for production and recycling; the concentrated solution of the bottom wastewater enters a concentrated solution tank;
step two, when the total amount of the waste water concentrated solution in the concentrated solution tank in the step one reaches the design amount, sucking the waste water concentrated solution into a concentrated solution evaporation tank by using a vacuum system and carrying out secondary evaporation, controlling the temperature to be 100-105 degrees, condensing top steam by using a second condenser to obtain crude glycol, entering the crude glycol tank for temporary storage, and periodically discharging residues in the concentrated solution evaporation tank through a drain valve; discharging sodium terephthalate in the wastewater from the bottom of the concentrated solution evaporation tank, further treating to obtain a pure product, or sending the pure product to a hazardous wastewater treatment center for disposal;
step three, the crude glycol temporarily stored in the crude glycol tank in the step two enters an ethylene glycol rectifying tower for rectification, the temperature is lower than 105 degrees in the initial stage of rectification, water is obtained after condensation by a third condenser, and the water is recovered to a second recovery water tank under the control of a valve; the temperature in the middle stage of rectification is 105-140 degrees, middle fraction ethylene glycol and water are obtained after the middle fraction ethylene glycol and the water are condensed by a third condenser, and the middle fraction ethylene glycol and the water are controlled by a valve and enter a middle fraction tank; the temperature in the later stage of rectification is 140-150 degrees, ethylene glycol is obtained after condensation by a third condenser, the ethylene glycol enters an ethylene glycol tank under the control of a valve, and residues are periodically discharged from an ethylene glycol rectifying tower through a blow-down valve.
And (2) in the second step, the concentrated solution evaporation tank and the ethylene glycol rectifying tower are both negative pressure equipment, the top of the concentrated solution evaporation tank is ethylene glycol under vacuum, the boiling point of the ethylene glycol is about 105 ℃, the second condenser is communicated with the concentrated solution evaporation tank, the second condenser is vacuumized by a vacuum system, the concentrated solution tank is normal pressure equipment, a valve between the concentrated solution tank and the concentrated solution evaporation tank is opened, and the liquid in the concentrated solution tank is sucked into the concentrated solution evaporation tank under the pressure difference.
The concentration of the ethylene glycol obtained in the third step is 92-98%.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (3)

1. A microfiber leather alkali decrement waste water recovery process is characterized in that: the method comprises the following steps:
step one, alkali decrement waste water flowing out of an alkali decrement waste water tank enters a waste water evaporator to be subjected to primary evaporation,
the waste water evaporator is normal pressure equipment, the temperature at the top of the waste water evaporator is the boiling point of water under normal pressure, the temperature is 100-105 degrees at the moment, and top steam enters the first condenser to be changed into water to be recycled into the first recycling water tank for production and recycling; the concentrated solution of the bottom wastewater enters a concentrated solution tank;
step two, when the total amount of the waste water concentrated solution in the concentrated solution tank in the step one reaches the design amount, sucking the waste water concentrated solution into a concentrated solution evaporation tank by using a vacuum system and carrying out secondary evaporation, controlling the temperature to be 100-105 degrees, condensing top steam by using a second condenser to obtain crude glycol, entering the crude glycol tank for temporary storage, and periodically discharging residues in the concentrated solution evaporation tank through a drain valve; discharging sodium terephthalate in the wastewater from the bottom of the concentrated solution evaporation tank, further treating to obtain a pure product, or sending the pure product to a hazardous wastewater treatment center for disposal;
step three, the crude glycol temporarily stored in the crude glycol tank in the step two enters an ethylene glycol rectifying tower for rectification, the temperature is lower than 105 degrees in the initial stage of rectification, water is obtained after condensation by a third condenser, and the water is recovered to a second recovery water tank under the control of a valve; the temperature in the middle stage of rectification is 105-140 degrees, middle fraction ethylene glycol and water are obtained after the middle fraction ethylene glycol and the water are condensed by a third condenser, and the middle fraction ethylene glycol and the water are controlled by a valve and enter a middle fraction tank; the temperature in the later stage of rectification is 140-150 degrees, ethylene glycol is obtained after condensation by a third condenser, the ethylene glycol enters an ethylene glycol tank under the control of a valve, and residues are periodically discharged from an ethylene glycol rectifying tower through a blow-down valve.
2. The microfiber leather alkali deweighting wastewater recovery process of claim 1, wherein: and (2) in the second step, the concentrated solution evaporation tank and the ethylene glycol rectifying tower are both negative pressure equipment, the top of the concentrated solution evaporation tank is ethylene glycol under vacuum, the boiling point of the ethylene glycol is 105 ℃, the second condenser is communicated with the concentrated solution evaporation tank, the second condenser is vacuumized by a vacuum system, the concentrated solution tank is normal pressure equipment, a valve between the concentrated solution tank and the concentrated solution evaporation tank is opened, and the liquid in the concentrated solution tank is sucked into the concentrated solution evaporation tank under the pressure difference.
3. The microfiber leather alkali deweighting wastewater recovery process of claim 1, wherein: the concentration of the ethylene glycol obtained in the third step is 92-98%.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4332643A (en) * 1976-03-02 1982-06-01 Reid Laurence S Method of removing water from glycol solutions
WO2014191314A1 (en) * 2013-05-31 2014-12-04 Aquafil Engineering Gmbh Process for workup of a mixture obtained in polycondensation processes and a plant for performing the process
CN105111074A (en) * 2015-07-20 2015-12-02 浙江大学 Methyl esterification recycling method of alkali decrement wastewater solid residue

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4332643A (en) * 1976-03-02 1982-06-01 Reid Laurence S Method of removing water from glycol solutions
WO2014191314A1 (en) * 2013-05-31 2014-12-04 Aquafil Engineering Gmbh Process for workup of a mixture obtained in polycondensation processes and a plant for performing the process
CN105111074A (en) * 2015-07-20 2015-12-02 浙江大学 Methyl esterification recycling method of alkali decrement wastewater solid residue

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