CN107525348A - A kind of multivariable predicting control method for air separation unit - Google Patents
A kind of multivariable predicting control method for air separation unit Download PDFInfo
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- CN107525348A CN107525348A CN201710589812.8A CN201710589812A CN107525348A CN 107525348 A CN107525348 A CN 107525348A CN 201710589812 A CN201710589812 A CN 201710589812A CN 107525348 A CN107525348 A CN 107525348A
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- separation unit
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
- F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
- F25J3/04—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream for air
- F25J3/04763—Start-up or control of the process; Details of the apparatus used
- F25J3/04769—Operation, control and regulation of the process; Instrumentation within the process
- F25J3/04848—Control strategy, e.g. advanced process control or dynamic modeling
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
- G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
- G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
- G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
- F25J2290/10—Mathematical formulae, modeling, plot or curves; Design methods
Abstract
A kind of multivariable predicting control method for air separation unit, described multivariable predicting control method are：a）Increase a host computer on the DCS system LAN of air separation unit, for creating air separation unit MVPC servers；b）Determine variable：According to air separation unit process optimization target, controlled variable CV, performance variable MV, disturbance variable DV are determined；c）The establishment principle of MVPC matrix sizes：Choose key parameter, variable as few as possible；The output of the lower PID controller of MVPC performance variable controlling opening of valve, i.e. matching convention control；When MVPC works, PID controller corresponding to MVPC performance variables is serials control, the output tracking MVPC performance variables of PID controller；When MVPC does not work, for PID controller corresponding to MVPC performance variables to automatically control, MVPC performance variables track the output of PID control；d）Establish model：One air separation unit, which establishes a MVPC controller model or is divided into different workshop sections, establishes independent MVPC controller models；e）Training, adjustment model：Gain K, time constant Tau, lag time Tdelay in initial setting model, after model is put into, system can provide gain, time constant and the lag time after optimization automatically；f）Come into operation.
Description
Technical field
The present invention relates to a kind of air separation unit umlti-variable finite elements being used in air separation production process
（MVPC: Multi-Variable Predictive Control）Method, belong to automation control engineering technical field.
Background technology
In the technological process of air separation unit, raw air by a series of filtering, compression, precooling, purification, supercharging,
After the operation link such as expansion and heat exchange, into lower tower；Air obtains oxygen-enriched liquid air after the preliminary rectifying of lower tower, in lower tower bottom,
Pure liquid nitrogen is obtained in lower top of tower, and enters upper tower via subcooler supercooling deutomerite stream.
After the further rectifying of upper tower, liquid oxygen is obtained in upper tower bottom, and enters main heat exchanger after liquid oxygen pump compresses, it is multiple
Gas oxygen product cooling box is used as after heat.Liquid oxygen direct cooling box in part enters liquid oxygen vessel as liquid oxygen product；From upper top of tower
Liquid nitrogen product is extracted, into liquid nitrogen storage tank.
By extracting a certain amount of Argon fraction from tower middle and lower part on main ice chest, liquid is obtained after crude argon column and pure argon column rectifying
Argon product, into liquid argon storage tank.
Air-separating plant has the characteristics that flow is complicated, coupling is serious；Simultaneously in the production process of air separation unit, outside
The features such as periodicity, stage, batch (-type) are often presented to the demand for producing gas for portion's pipe network, and it is unnecessary that oxygen dissipation can cause
Energy consumption and economic loss.
The content of the invention
It is an object of the invention to overcome the shortcomings of the prior art, and it is more steady to provide a kind of operating mode for making air separation unit
It is fixed, oxygen product recovery rate can be improved, reduces the dissipative shock wave of oxygen product, improves argon gas product recovery rate, it is unnecessary to reduce
Extra cold produces, the energy-saving multivariable predicting control method for air separation unit.
The present invention is achieved by following technical solution：A kind of umlti-variable finite elements side for air separation unit
Method, described multivariable predicting control method are：
a）Increase a host computer on the DCS system LAN of air separation unit, for creating air separation unit MVPC servers,
MVPC clients are then arranged on DCS engineer station or operator station；
b）Determine variable：According to air separation unit process optimization target（For example product flow fluctuation is reduced, reduce energy consumption etc.）,
Determine controlled variable CV, performance variable MV, disturbance variable DV；
c）The establishment principle of MVPC matrix sizes：Choose key parameter, variable as few as possible；CV's and MV's phase is determined simultaneously
Close the setting such as limitation；The output of the lower PID controller of MVPC performance variable controlling opening of valve, i.e. matching convention control；In MVPC
During work, PID controller corresponding to MVPC performance variables is serials control, the output tracking MVPC performance variables of PID controller；
When MVPC does not work, PID controller corresponding to MVPC performance variables is automatically controls, MVPC performance variables tracking PID control
Output；
d）Establish model：One air separation unit, which establishes a MVPC controller model or is divided into different workshop sections, establishes independent MVPC
Controller model；
e）Training, adjustment model：Gain K, time constant Tau, lag time Tdelay in initial setting model, model input
Afterwards, system can provide gain, time constant and the lag time after optimization automatically；
f）Come into operation, further Optimized model.
As preferred：Described further Optimized model is mainly according to air separation unit flow process optimization aim, increase
CV, MV, DV quantity；Can using the energy consumption relevant parameters such as the aperture of air compressor guide vane, air compressor machine electric current as CV with further
It is energy-saving；
The MVPC controller models use 2, including main space division MVPC controllers and ar system MVPC controllers, 2 controls
The control of device is separate；Or described main space division MVPC controllers and ar system MVPC controllers are synthesized 1.
As preferred：Described MVPC controllers are according to current time each performance variable MV measured value, calculate each behaviour
Make variable MV variable quantity, its predicted value corrected according to each controlled variable CV current measurement value, by predictive control algorithm according to
According to Control performance standard, optimization calculates each performance variable MV optimum control increment Delta MV.
As preferred：The MVPC is actually decoupled system so that couples serious procedures system and simplifies；It is easy to predict
And control；
Described MVPC is actually constrained control, and by limiting CV high and low limit, deviation suppresses；The high lower bounds of MV are limited, are become
Change amplitude, deviation suppress etc. so that controlled variable in the range of high and low limit as close possible to set point, or as far as possible towards
One direction is close, i.e. the close high limit of CV set point or lower bound.
The present invention has operating mode more stable, can improve oxygen product recovery rate, reduces the dissipative shock wave of oxygen product, improves argon
Gas product recovery rate, reduce unnecessary extra cold and produce, it is energy-saving the features such as.
Brief description of the drawings
Fig. 1 is main space division MVPC matrix diagram.
Fig. 2 is ar system MVPC matrix diagram.
Fig. 3 is oxygen product flow diagram.
Fig. 4 is Argon recovery rate figure.
Embodiment
The present invention will be described in detail below in conjunction with the accompanying drawings and the specific embodiments：It is a kind of to be used for the changeable of air separation unit
Forecast Control Algorithm is measured, described multivariable predicting control method is：
a）Increase a host computer on the DCS system LAN of air separation unit, for creating air separation unit MVPC servers,
MVPC clients are then arranged on DCS engineer station or operator station；
b）Determine variable：According to air separation unit process optimization target（For example product flow fluctuation is reduced, reduce energy consumption etc.）,
Determine controlled variable CV, performance variable MV, disturbance variable DV；
c）The establishment principle of MVPC matrix sizes：Choose key parameter, variable as few as possible；CV's and MV's phase is determined simultaneously
Close the setting such as limitation；The output of the lower PID controller of MVPC performance variable controlling opening of valve, i.e. matching convention control；In MVPC
During work, PID controller corresponding to MVPC performance variables is serials control, the output tracking MVPC performance variables of PID controller；
When MVPC does not work, PID controller corresponding to MVPC performance variables is automatically controls, MVPC performance variables tracking PID control
Output；
d）Establish model：One air separation unit, which establishes a MVPC controller model or is divided into different workshop sections, establishes independent MVPC
Controller model；
e）Training, adjustment model：Gain K, time constant Tau, lag time Tdelay in initial setting model, model input
Afterwards, system can provide gain, time constant and the lag time after optimization automatically；
f）Come into operation, further Optimized model.
Further Optimized model of the present invention mainly according to air separation unit flow process optimization aim, increase CV,
MV, DV quantity；The energy consumption relevant parameters such as the aperture of air compressor guide vane, air compressor machine electric current can be further saved as CV
Consumption reduction；
The MVPC controller models use 2, including main space division MVPC controllers and ar system MVPC controllers, 2 controls
The control of device is separate；Or described main space division MVPC controllers and ar system MVPC controllers are synthesized 1.
MVPC controllers of the present invention are according to current time each performance variable MV measured value, calculate each operation and become
MV variable quantity is measured, its predicted value is corrected according to each controlled variable CV current measurement value, by predictive control algorithm according to control
Performance indications processed, optimization calculate each performance variable MV optimum control increment Delta MV.
MVPC of the present invention is actually decoupled system so that couples serious procedures system and simplifies；Be easy to prediction and
Control；
Described MVPC is actually constrained control, and by limiting CV high and low limit, deviation suppresses；The high lower bounds of MV are limited, are become
Change amplitude, deviation suppress etc. so that controlled variable in the range of high and low limit as close possible to set point, or as far as possible towards
One direction is close, i.e. the close high limit of CV set point or lower bound.
The beneficial effect of this patent is：Operating mode is more stable, reduces oxygen and dissipates, energy-saving.
In Fig. 1：Numeral 1 also serves as MV while representing same parameter as CV, i.e., acts simultaneously, direction, amplitude are complete
It is complete consistent；Direction arrow is generally one order inertia and adds purely retarded model；Different directions represent positive, Back Up；Blank represents
Not related, i.e., time lag of first order Model Parameter K/Tau/Delay is 0.
If the direction of arrow negates in model, then during training pattern, data can dissipate；This is an easy hair
Now with solve the problems, such as.
When molecular sieve is pressed, have portion of air and flow into the jar regenerated.Generally can logical operation pneumatics
Machine stator increases a part of aperture automatically, to compensate portion of air, but still has fluctuation, also can be to the operating mode of air separation unit
Cause necessarily to disturb；When molecular sieve is parallel, certain disturbance can be also caused to the operating mode of air separation unit.So molecular sieve presses off
Begin that to this stage of parend a disturbance variable can be used as.
In Fig. 2：Numeral 1 also serves as MV while representing same parameter as CV, i.e., acts simultaneously, direction, amplitude are complete
It is complete consistent；Direction arrow is generally one order inertia and adds purely retarded model；Different directions represent positive, Back Up；Blank represents
Not related, i.e., time lag of first order Model Parameter K/Tau/Delay is 0.
If the direction of arrow negates in model, then during training pattern, data can dissipate；This is an easy hair
Now with solve the problems, such as.
In Fig. 3, flowmeter represents the flow of oxygen product cooling box before oxygen sends out valve and oxygen emptying valve herein.
It is under the antecedent basis met customer need, bulk flow is reduced, it is meant that oxygen dissipation amount is reduced.Also it can use and put from oxygen
The aperture trend of empty valve embodies（Offer trend is not provided here）.
In Fig. 4 it can be seen that after MVPC comes into operation, Argon recovery rate increases, while trend is more stable.
Claims (4)
- A kind of 1. multivariable predicting control method for air separation unit, it is characterised in that described multivariable predicting control method It is：a）Increase a host computer on the DCS system LAN of air separation unit, for creating air separation unit MVPC servers, MVPC clients are then arranged on DCS engineer station or operator station；b）Determine variable：According to air separation unit process optimization target, determine that controlled variable CV, performance variable MV, disturbance become Measure DV；c）The establishment principle of MVPC matrix sizes：Choose key parameter, variable as few as possible；CV's and MV's phase is determined simultaneously Close the setting such as limitation；The output of the lower PID controller of MVPC performance variable controlling opening of valve, i.e. matching convention control；In MVPC During work, PID controller corresponding to MVPC performance variables is serials control, the output tracking MVPC performance variables of PID controller； When MVPC does not work, PID controller corresponding to MVPC performance variables is automatically controls, MVPC performance variables tracking PID control Output；d）Establish model：One air separation unit, which establishes a MVPC controller model or is divided into different workshop sections, establishes independent MVPC Controller model；e）Training, adjustment model：Gain K, time constant Tau, lag time Tdelay in initial setting model, model input Afterwards, system can provide gain, time constant and the lag time after optimization automatically；f）Come into operation, further Optimized model.
- 2. the multivariable predicting control method according to claim 1 for air separation unit, it is characterised in that described enters One-step optimization model is mainly according to air separation unit flow process optimization aim, increase CV, MV, DV quantity；Can be pneumatics Machine leads the energy consumption relevant parameters such as leaf divergence, air compressor machine electric current as CV with further energy-saving；The MVPC controller models use 2, including main space division MVPC controllers and ar system MVPC controllers, 2 controls The control of device is separate；Or described main space division MVPC controllers and ar system MVPC controllers are synthesized 1.
- 3. the multivariable predicting control method according to claim 1 or 2 for air separation unit, it is characterised in that described MVPC controllers are the variable quantities that each performance variable MV is calculated according to current time each performance variable MV measured value, according to each Controlled variable CV current measurement value corrects its predicted value, is calculated by predictive control algorithm according to Control performance standard, optimization Go out each performance variable MV optimum control increment Delta MV.
- 4. the multivariable predicting control method according to claim 4 for air separation unit, it is characterised in that the MVPC It is actually decoupled system so that couple serious procedures system and simplify；It is easy to predict and controls；Described MVPC is actually constrained control, and by limiting CV high and low limit, deviation suppresses；The high lower bounds of MV are limited, are become Change amplitude, deviation suppress etc. so that controlled variable in the range of high and low limit as close possible to set point, or as far as possible towards One direction is close, i.e. the close high limit of CV set point or lower bound.
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Cited By (3)
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| CN110044134A (en) * | 2019-03-29 | 2019-07-23 | 安徽加力气体有限公司 | Full-automatic one key start stop control method of nitrogen making machine system |
| CN110595153A (en) * | 2018-06-12 | 2019-12-20 | 中国科学院沈阳自动化研究所 | Control method for air feeding amount in automatic load changing process of air separation device |
| US20220205819A1 (en) * | 2020-12-30 | 2022-06-30 | L'air Liquide, Societe Anonyme Pour L'etude Et L?Exploitation Des Procedes Georges Claude | Air separation control system and control method |
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Address after: No. 280 Xingye Road, Leidian Town, Deqing County, Huzhou City, Zhejiang Province, 313219 Patentee after: Yingde Gas Engineering (Zhejiang) Co.,Ltd. Address before: 313219 Jingyi Road, Linhang Industrial Zone, Deqing, Leidian Town, Huzhou City, Zhejiang Province Patentee before: ZHEJIANG ZHIHAI CHEMICAL EQUIPMENT ENGINEERING Co.,Ltd. |
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