CN109704928A - A kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water dynamic control scheme - Google Patents

A kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water dynamic control scheme Download PDF

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Publication number
CN109704928A
CN109704928A CN201910003711.7A CN201910003711A CN109704928A CN 109704928 A CN109704928 A CN 109704928A CN 201910003711 A CN201910003711 A CN 201910003711A CN 109704928 A CN109704928 A CN 109704928A
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China
Prior art keywords
tower
propylene glycol
water
rectifying column
glycol monomethyl
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Pending
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CN201910003711.7A
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Chinese (zh)
Inventor
王英龙
刘晓斌
戴姚
朱兆友
崔培哲
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Qingdao University of Science and Technology
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Qingdao University of Science and Technology
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Abstract

The present invention provides a kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water dynamic control schemes.It include: flow controller, for adjusting feed flow rates;Fluid level controller is respectively used to adjust the liquid level of tower reactor and the liquid level of phase-splitter;Pressure controller is respectively used to adjust the tower pressure of two rectifying columns;Temperature controller is respectively used to adjust the tower temperature of rectifying column and the temperature of heat exchanger;Composition control device, for adjusting the composition of product water;Proportional controller is respectively used to the ratio of the reboiler heat duty of fixer liquid extraction tower feed flow rates and extractant circulation flow-rate and rectifying column.The present invention realizes the automatic control to liquid-liquid extraction tower flow and rectifying column temperature, pressure and flow, it is ensured that the high-purity quiet run of two kinds of product propylene glycol monomethyl ethers and water, and there is good dynamic control effect.The equipment requirement that the present invention uses is low, easy to accomplish, and the present invention has preferable dynamic controllability, low cost, and low energy consumption reduces CO2The advantages that discharge, product purity is high.

Description

A kind of dynamic control of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water Scheme
[technical field]
The invention belongs to chemical fields, and in particular to a kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water Dynamic control scheme more particularly to Chemical Manufacture automation control area.
[background technique]
Propylene glycol monomethyl ether is commonly used for detergent and emulsifier, can be by esterification come synthesizing propylene glycol monomethyl ether acetic acid Ester, water are by-product.Since propylene glycol monomethyl ether and water form the azeotropic mixture of minimum boiling point, the dehydration of propylene glycol monomethyl ether is this Essential but crucial step in the process.The dehydration of propylene glycol monomethyl ether is used in heterogeneous azeotropic distillation and extractive distillation process During, energy consumption is high.In general, effectively dividing for the mixture with low energy consumption may be implemented in the mixed method comprising liquid-liquid extraction From, therefore we combine liquid-liquid extraction with rectifying.
It is dynamically control on exploitation and performance evaluation, the simulation of driving and parking process, the process working condition calibration of process control system Etc. be used widely.For rectifying separation process, common is exactly to control the purity of product, therefore for distillation process The research of control technique have great importance.
In distillation process, by the constraint for connecting the circulation logistics of two towers during rectifying, height is generated in distillation process Coupling, occur disturbance in a tower and be transmitted as readily to another tower, cause to be formed between Liang Ta certain mutual Effect, this interaction inevitably cause control problem.At present very for the dynamic control research of binary system separation It is few, as the introducing of third component extractant, so that the control difficulty for process greatly increases, therefore present invention is generally directed to The steady-state flow of heterogeneous separation of extractive distillation propylene glycol monomethyl ether-water proposes a kind of effective control program, guarantees two kinds of products The high-purity quiet run of propylene glycol monomethyl ether and water.
Patent (CN106431812A) discloses the method and dress of a kind of separation of extractive distillation toluene-methanol-water azeotropic mixture Set, this method by Liang Ta and phase-splitter separation of tertiary system methanol-toluene-water, obtain high purity methanol, toluene and Water, but this patent is not carried out dynamic control.
Patent (CN106916050A) discloses a kind of separation system and its application method for low carbon mixed alcohol, is applicable in In the dehydration of low carbon mixed alcohol, which gives the single column Dynamic Control Strategy of single tower distillation separation, compared to this patent Heterogeneous liquid-liquid extraction combination distillation control, the variable that single column control needs to control is few and simple, and control difficulty is lower than this patent.
[summary of the invention]
[technical problems to be solved]
It solves the problems, such as to be overcome the deficiencies in the prior art, proposes a kind of heterogeneous liquid-liquid extraction combination rectifying separation third Glycol methyl ether-water dynamic control scheme, the invention patent problem in science to be solved are as follows:
The object of the present invention is to provide one kind to be suitable for heterogeneous liquid-liquid extraction combination rectifying separating binary mixture process Dynamic control scheme.
It is a further object of the present invention to provide the control programs in the application of separating propylene glycol methyl ether-aqueous systems.
[technical solution]
The present invention is using the dynamic control scheme of a kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water come really The high-purity quiet run for protecting two various product propylene glycol monomethyl ethers and water, mainly comprises the steps that
(1) steady state process: propylene glycol monomethyl ether and aqueous mixtures enter extraction tower T1 tower bottom through valve V2, and extractant is pushed up from T1 Portion enters, and through extracting, water and a small amount of propylene glycol monomethyl ether and extractant enter mixer MIX1 through valve V3, pump P1 from T1 tower top, Rectifying column C1, propylene glycol monomethyl ether-water-extractant are mixed into propylene glycol monomethyl ether-water-extractant from phase-splitter DE lower layer Enter mixer MIX2 from tower top, product water is produced from rectifying column C1 tower bottom;A large amount of extractants and PM and a small amount of water are from extraction The bottom tower T1 enters at the top of rectifying column C2 through valve V4 and pump P2, and propylene glycol monomethyl ether-water-extractant enters from rectifying column C2 tower top Mixer MIX2, product propylene glycol monomethyl ether are produced from the bottom rectifying column C2;Propylene glycol monomethyl ether-the water-flowed out from mixer MIX2 Extractant enters phase-splitter DE through heat exchanger HX, adds extractant and adds people, upper layer propylene glycol monomethyl ether-water-at the top of phase-splitter DE Extractant returns to mixer MIX1, and lower layer's extractant enters extraction tower T1 and recycle through pump P3, valve V1.
(2) dynamic control scheme: extraction tower T1 inlet amount is controlled by flow controller FC, and phase-splitter DE is recycled to extraction The circulation stream flowrates of tower T1 are based on proportional controller SVF and pass through circulation logistics flow controller FC1 control, the flow rate control Device FC and FC2 are Reverse Turning Control;The tower top pressure of rectifying column C1 and rectifying column C2 pass through corresponding overhead condenser thermic load Rate control is removed, pressure controller PC1, PC2 are Reverse Turning Control;The tower reactor liquid level of rectifying column C1 and rectifying column C2 by adjusting The control of tower bottom produced quantity, tower reactor fluid level controller LC1, LC2 are positive control;The liquid level of phase-splitter DE by adjusting add extraction The inlet amount and upper layer produced quantity of agent control, and fluid level controller LC3, LC4 are positive control;By temperature controller TC1, TC2, TC3 is respectively used to adjust rectifying column C1, the tower temperature of rectifying column C2 and the temperature of heat exchanger HX.
In accordance with another preferred embodiment of the present invention, it is characterised in that: composition control device CC is for adjusting product water Purity;Extraction tower T1 tower reactor uses proportional controller QRVF, and the feed flow rates F based on extraction tower T1 adjusts rectifying column C2 tower bottom again Boiling device thermic load QR is to guarantee that rectifying column C2 tower reactor produces the purity of product.
In accordance with another preferred embodiment of the present invention, it is characterised in that: the control program steady can control ± Feed flow rates within 20% disturb and ± 20% feed composition disturbs, and the purity of water is 99.9% or more, third after separation The purity of glycol methyl ether is 99.8% or more.
[beneficial effect]
The present invention compared with prior art, mainly have it is following the utility model has the advantages that
(1) ensure the high-purity quiet run of three kinds of product propylene glycol monomethyl ethers and water using simple control structure.
(2) this control technique can well solve the disturbance of feed flow rates and feed composition.
(3) it is suitable for controlling more demanding propylene glycol monomethyl ether dehydration liquid-liquid extraction hybrid technique.
(4) present invention has low cost, and low energy consumption reduces CO2The advantages that discharge, product purity is high.
[Detailed description of the invention]
Attached drawing 1 is flow diagram of the invention, in which:
T1 extraction tower, C1 rectifying column, C2 rectifying column, valve V1-V6, pump P1-P3, mixer MIX1-MIX2, heat exchanger HX, phase-splitter DE;PC1, PC2 tower top pressure controller, LC1, LC2 tower reactor fluid level controller, LC3, LC4 phase-splitter DE liquid level control Device processed, FC extraction tower T1 feed flow rates controller, FC1 recycle logistics flow controller, and TC1, TC2, TC3 are respectively rectifying column The temperature controller of C1, rectifying column C2 and heat exchanger HX, CC are the purity composition control device for adjusting product water, and SVF is fixed extraction Take the proportional controller of the feed flow rates F of tower T1 and the flow rate S of extractant, the feed flow rates F that QRVF is fixed extractor tower T1 with The proportional controller of rectifying column C2 tower bottom reboiler thermic load QR, △ T are the dead time;Solid line with the arrow indicates each stream tube Road, dotted line with the arrow indicate the input or output signal of controller.
Attached drawing 2 is the dynamic response figure of feed flow rates disturbance, and the feed flow rates that solid line is+20% disturb, and dotted line is -20% Feed flow rates disturbance.
Attached drawing 3 is the dynamic response figure of feed composition disturbance, and the feed composition that solid line is+20% disturbs, and dotted line is -20% Feed composition disturbance.
[specific embodiment]
It is further illustrated below in conjunction with attached drawing 1, not limits range according to the present invention.
Steady state process process: feeding temperature is 45 DEG C, flow rate 1000kmol/h, and pressure is 1.5atm (absolute pressure), charging In aqueous 92.2%, contain propylene glycol monomethyl ether 7.8%.Extraction tower (T1) operating pressure is 1atm (absolute pressure), and number of theoretical plate 9 follows Ring extractant feed plate is 1, and feedstock plate is 9, rectifying column (C1) operating pressure 1atm (absolute pressure), number of theoretical plate 20, into Flitch is 1, and temperature sensitive plate is the 14th block of column plate, rectifying column (C2) operating pressure 1atm (absolute pressure), number of theoretical plate 8, charging Plate is 1, and temperature sensitive plate is the 4th block of column plate, and under this process condition, the purity of water can achieve 99.9% or more, propylene glycol The purity of methyl ether can achieve 99.8% or more.
Embodiment 1: each controller automatically enters setting value after initialization operation, and determines by median of setting value Range does test method with closed loop.On initial steady state Process ba- sis addition ± 20% feed flow rates disturbance, i.e., into Stream rate is addition+20% respectively after the process stabilizing operation of 1000kmol/h (water 92.2%, propylene glycol monomethyl ether 7.8%) The flow rate disturbance of (1200kmol/h) and the flow rate of -20% (800kmol/h) disturb.
After being added to disturbance, purity and rectifying column C2 bottom product propylene glycol monomethyl ether to the bottom rectifying column C1 product water Purity carries out data record, to test the control performance of kinetic-control system.Dynamic response figure such as 2 institute of attached drawing of flow rate disturbance Show, the feed flow rates that solid line is+20% disturb, and the feed flow rates that dotted line is -20% disturb.
When the disturbance of charging addition ± 20%, the concentration of propylene glycol monomethyl ether and water is by initial 1000kmol/h's in product 99.9% has carried out oscillation on small scale, and the two after 3h product be all up initial 99.9%, there is preferable robust Property and stability.
Embodiment 2: each controller automatically enters setting value after initialization operation, and determines by median of setting value Range does test method with closed loop.On initial steady state Process ba- sis addition ± 20% feed composition disturbance, i.e., into Stream rate be 1000kmol/h (water 92.2%, propylene glycol monomethyl ether 7.8%) process stabilizing operation after, respectively add isobutanol+ (isobutanol 93.76% contains benzene for the composition disturbance of 20% (water 90.64%, propylene glycol monomethyl ether 9.36%) and isobutanol -20% 6.24%) composition disturbance.
After being added to disturbance, purity and rectifying column C2 bottom product propylene glycol monomethyl ether to the bottom rectifying column C1 product water Purity carries out data record, to test the control performance of kinetic-control system.Dynamic response figure such as 3 institute of attached drawing of flow rate disturbance Show, the feed composition that solid line is+20% disturbs, and the feed composition that dotted line is -20% disturbs.
When the disturbance of feed composition addition ± 20%, the concentration of propylene glycol monomethyl ether and water is by initial in product The 99.9% of 1000kmol/h has carried out oscillation on small scale, and after 1.5h, aquatic products can reach initial 99.9%, propylene glycol first Ether product reaches 99.8%, has preferable robustness and stability.

Claims (5)

1. a kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water dynamic control scheme, it is characterised in that described The work that separating propylene glycol methyl ether-water binary mixture steady state process is extraction tower, two-tower rectification combination phase-splitter is separated Skill, the dynamic control scheme of the separating propylene glycol methyl ether-water binary mixture are extraction tower, two-tower rectification combination phase-splitter point The dynamic control scheme of separating process design.
2. as described in claim 1, it is characterised in that propylene glycol monomethyl ether-water binary mixture steady state process is as follows:
Propylene glycol monomethyl ether and aqueous mixtures enter extraction tower T1 tower bottom through valve V2, and extractant enters at the top of T1, through extracting, water Enter mixer MIX1 through valve V3, pump P1 from T1 tower top with a small amount of propylene glycol monomethyl ether and extractant, and under phase-splitter DE Water-propylene glycol monomethyl ether-extractant of layer is mixed into rectifying column C1, and water-propylene glycol monomethyl ether-extractant enters mixer from tower top MIX2, product water are produced from rectifying column C1 tower bottom;A large amount of extractants and propylene glycol monomethyl ether and a small amount of water are from the bottom extraction tower T1 Enter at the top of rectifying column C2 through valve V4 and pump P2, water-propylene glycol monomethyl ether-extractant enters mixer from rectifying column C2 tower top MIX2, product propylene glycol monomethyl ether are produced from the bottom rectifying column C2;Water-propylene glycol monomethyl ether-the extractant flowed out from mixer MIX2 Enter phase-splitter DE through heat exchanger HX, adds extractant and add people, upper water-propylene glycol monomethyl ether-extractant at the top of phase-splitter DE Mixer MIX1 is returned to, lower layer's extractant enters extraction tower T1 and recycle through pump P3, valve V1.
3. as described in claim 1, it is characterised in that control separation water-propylene glycol monomethyl ether binary mixture process dynamic control Scheme is as follows:
Feed flow rates controller FC is used to adjust the feed flow rates of extraction tower T1;Fluid level controller LC is respectively used to adjust tower reactor The liquid level of liquid level and phase-splitter;Pressure controller PC is respectively used to adjust the tower pressure of rectifying column C1 tower pressure and rectifying column C2; Temperature controller TC is respectively used to adjust rectifying column C1, the tower temperature of rectifying column C2 and the temperature of heat exchanger HX;Composition control device CC, for adjusting the purity of product water;Proportional controller QRVF adjusts rectifying column C2 tower bottom based on the feed flow rates F of extraction tower T1 Reboiler heat duty QR;Proportional controller SVF adjusts the flow rate S of extractant based on the feed flow rates F of extraction tower T1.
4. according to claim 1 described in -3, it is characterised in that: rectifying column (C2) tower reactor uses proportional controller QRVF, based on extraction The feed flow rates F of tower T1 is taken to adjust rectifying column C2 tower bottom reboiler thermic load QR;Rectifying column C1 tower reactor uses composition control device CC Control the purity of product water;Using proportional controller SVF, the feed flow rates F based on extraction tower T1 adjusts the flow rate S of extractant.
5. according to claim 1 described in -3, it is characterised in that: the control technique steady can control the charging within ± 20% Feed composition disturbance within flow rate disturbance and ± 20%, after separation the purity of water 99.9% or more, propylene glycol monomethyl ether it is pure Degree is 99.8% or more.
CN201910003711.7A 2019-01-03 2019-01-03 A kind of heterogeneous liquid-liquid extraction-rectifying separating propylene glycol methyl ether and water dynamic control scheme Pending CN109704928A (en)

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Application publication date: 20190503