CN107490245A - A kind of Automatic load change control method for air separation unit - Google Patents

A kind of Automatic load change control method for air separation unit Download PDF

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Publication number
CN107490245A
CN107490245A CN201710589931.3A CN201710589931A CN107490245A CN 107490245 A CN107490245 A CN 107490245A CN 201710589931 A CN201710589931 A CN 201710589931A CN 107490245 A CN107490245 A CN 107490245A
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flow
air
airtot
func
variable
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CN107490245B (en
Inventor
姜昊
付定君
韩立峰
崔拥军
张强
周筱俊
孙彬
吴文英
张育哲
徐小芹
侯新刚
韦霆
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Yingde Gas Engineering Zhejiang Co ltd
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Zhejiang Zhihai Chemical Equipment Engineering Co Ltd
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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
    • 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
    • F25J3/04812—Different modes, i.e. "runs" of operation
    • F25J3/04836—Variable air feed, i.e. "load" or product demand during specified periods, e.g. during periods with high respectively low power costs
    • 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
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/40—Air or oxygen enriched air, i.e. generally less than 30mol% of O2
    • 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
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/50—Advanced process control, e.g. adaptive or multivariable control

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

A kind of Automatic load change control method for air separation unit, described Automatic load change control method comprise the following steps：1）Obtain the PFD data of crucial process parameter under each operating mode of air separation unit flow scheme design；2）The variable of final products flow is determined as, these variables are as the desired value set during process operator varying duty；3）It is determined that crucial intermediate variable；These crucial intermediate variables are used for calculating the set point of final PID controller；4) PID controller of participation Automatic load change is determined；5）Step 2 is obtained by fitting）With step 3）It is between middle parameter, with step 3）Middle variable is dependent variable, step 2）Middle variable is the fitting function of independent variable；6）Step 3 is obtained by fitting）With step 4）It is between middle parameter, with step 4）Middle variable is dependent variable, step 3）Middle variable is the fitting function of independent variable；7）For the work point data under same technological parameter difference operating mode, respectively worked point model come interpolation by polynomial function, obtain the varying duty linear change track of the technological parameter；8）The startup of Automatic load change and stopping needs meeting some requirements；9）According to the difference of flow, above parameter can increase or decrease.

Description

A kind of Automatic load change control method for air separation unit
Technical field
The present invention relates to a kind of Automatic load change control method of air separation unit in air separation production process, belong to Air separation unit 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, in Shang Ta Bottom obtains liquid oxygen, and enters main heat exchanger after liquid oxygen pump compresses, and gas oxygen product cooling box is used as after re-heat.Part liquid oxygen is straight Pick out ice chest and enter liquid oxygen vessel as liquid oxygen product；Liquid nitrogen product is extracted from upper top of tower, into liquid nitrogen storage tank；By from master A certain amount of Argon fraction is extracted in tower middle and lower part on ice chest, liquid argon product is obtained after crude argon column and pure argon column rectifying, into liquid argon Storage tank.
Air-separating plant has the characteristics that flow is complicated, coupling is serious：First, a large amount of uses are thermally integrated in air separation unit With Recycle of material technology, the feature for making air separation unit that there is typical energy to be coupled with height of materials.As above tower is total to lower tower With a condenser/evaporator, a tower liquid air part is and for example descended to be flowed back directly as in the middle part of upper tower, other part condenses for crude argon column Device provides cold, finally returns to tower in space division and participates in rectifying；These factors increase the difficulty of air separation unit varying duty operation.Becoming In load process, it is impossible to individually the unit of device is adjusted.
Secondly, the operation of air separation unit varying duty is the Dynamic Regulating Process of one group of key job point, is production process from one Transition of the individual operating mode to another operating mode；But in ascending, descending load process, user's determination is only the yield of product, not true The desired value of the other critical process variables of the operating mode that sets the goal, empirical method is unpredictable, and time-consuming longer, and easy hyperharmonic is shaken Swing.
The content of the invention
It is an object of the invention to overcome the shortcomings of the prior art, and a kind of air separation unit that mainly solves is provided and becomes negative The problems such as mutual decoupling, the easy hyperharmonic of energy and material are vibrated during lotus, ensures air separation unit stabilization and product quality On the premise of, realize smooth, the Automatic load change control method for air separation unit of fast transition between different operating modes.
The purpose of the present invention is completed by following technical solution, a kind of Automatic load change control for air separation unit Method processed, described Automatic load change control method comprise the following steps：
1）Obtain each operating mode of air separation unit flow scheme design, including at least crucial process parameter under minimum operating mode and maximum duty PFD data；
2）It is determined as the variable of final products flow：Low oxygen product flow LPOG, low-pressure nitrogen product flow LPNG, argon Gas product flow ArG, liquid nitrogen product flow NL；Liquid oxygen product flow OL；These variables are as process operator varying duty process The desired value of middle setting；
3）It is determined that crucial intermediate variable：AIRtot enter ice chest air capacity, NLeq liquefying powers, AIRturb expanded airs amount, NGturb expansions nitrogen quantity, HPAIR pressure-airs amount, HPALhp High pressure liquid air amounts；These crucial intermediate variables are used for calculating finally The set point of PID controller；
4) PID controller of participation Automatic load change is determined：Air mass flow is controlled by adjusting main compressor inlet guide vane FIC1294, pressure-air amount HPair FIC7418, the dirty nitrogen flow FIC1213 of regeneration, dirty nitrogen pressure PIC1626, high pressure Lean solution backflow FIC1557, the top of tower in regulation of liquid air FIC1556, regulation medium pressure column hypomere and lower pressure column upper end reflux ratio The liquid nitrogen reflux FIC1558 of reflux ratio and purity, oxygen-enriched liquid air liquid level LIC1601, low-pressure nitrogen flow FIC1520, elevated pressure nitrogen Throughput FIC1501, low oxygen flow FIC1510, argon flow amount FIC1540, liquid nitrogen gas product flow FIC1630, The thick liquid argon flows of FIC1704, medium pressure nitrogen gas to evaporator of pure argon column flow FIC1731, crude argon column oxygen-enriched liquid air liquid level LIC1701；
5）Step 2 is obtained by fitting）With step 3）It is between middle parameter, with step 3）Middle variable is dependent variable, step 2）In Variable is the fitting function of independent variable；
6）Step 3 is obtained by fitting）With step 4）It is between middle parameter, with step 4）Middle variable is dependent variable, step 3）In Variable is the fitting function of independent variable；
7）For the work point data under same technological parameter difference operating mode, by polynomial function come each operating point mould of interpolation Type, obtain the varying duty linear change track of the technological parameter；Wherein business-critical needs to go to correct with component, and liquid level needs to limit Make within the specific limits, so that the product that device produces after stabilization converts on the premise of air separation unit stabilization, purity are up to standard Load；
8）The startup of Automatic load change and stopping needs meeting some requirements；
9）According to the difference of flow, above parameter can increase or decrease.
As preferred：Described step 5）In, the functional relation of independent variable and dependent variable is as follows：
AIRtot=func (LPOG, OL), it is fitted to obtain function by the parameter value of AIRtot, LPOG, OL under different operating modes,
The oxygen content of crude argon column charging is used for correcting AIRtot；
Revised functional relation is that AIRtot*=func (LPOG, OL)+AIC1716 wherein AIC1716 corrections are +/- the 10% of AIRtot design discharges；
NLeq=func (NL, OL, FIC1704) characterizes the ability of production fluid product；
AIRturb=func (AIRtot, NLeq) maintains overall ice chest balance；
NGturb=func (AIRtot, NLeq) maintains overall ice chest balance；
The pressure-air amount that HPair=FIC7418 production low oxygens need；
It is into ice chest air capacity that air capacity and pressure-air amount sum are pressed in MPair=AIRtot-HPair；
Liquid is obtained after the expansion of HPALhp=HPair-FIC1556 pressure-airs, partly enters medium pressure column, another part enters low Press tower；The flow of lower pressure column is removed in regulation, and to maintain the reflux for comparing, this strand of liquefied air flow is adjusted the charging of lower pressure column by FIC1556 Valve FV1556 is controlled；HPALhp is only intermediate variable, is not involved in varying duty；
In described step 6, thick liquid argon flow RSP [FIC1704]=func (AIRtot)；
Air total amount FIC1294=func (AIRtot)+IA, wherein IA instrument airs flow, generally definite value；
Dirty nitrogen flow FIC1213=func (AIRtot)；
Dirty nitrogen pressure PIC1626=func (AIRtot, LPNG)；
Liquid air FIC1556=func (AIRtot)；
Lean solution backflow FIC1557=func (AIRtot)；
Liquid nitrogen reflux FIC1558=func (AIRtot, MPNG)；
Oxygen-enriched liquid air liquid level LIC1601=func (AIRtot), wherein upper and lower spacing high and low alarm when being industrial design is set Fixed point；
Low pressure nitrogen flow FIC1520=LPNG；
Medium pressure nitrogen throughput FIC1501=func (AIRtot)；
Low pressure oxygen flow FIC1510=LPOG；
Argon flow amount FIC1540=ArG；
Liquid nitrogen flow FIC1630=NL；
Thick liquid argon flow FIC1704=func (AIRtot)；
FIC1731 = func(FIC1704)；
LIC1701=func (AIRtot), wherein upper and lower spacing high and low alarm settings point when being industrial design；
Air expander air mass flow FIC1530=AIRturb；
The road flow FIC1502=NGturb of low-pressure nitrogen 1；
Participate in the constituent analysis measuring point of amendment：Oxygen content, crude argon column middle part oxygen content, forward direction compensation in the middle part of lower pressure column；
Top exit is thick liquid argon（CAL）, thick liquid argon is admitted to pure argon column K11, and thick liquid argon flow is according to the air for entering ice chest Total amount calculates, and is corrected by the purity analyzer AIC1705 output valves in argon column stage casing；
RSP[FIC1704]* = func(AIRtot) + AIC1705；
AIC1705 extent of amendment is +/- 20 % of the maximum mixed traffic of thick liquid argon, because the response time of argon column is longer, So the PID adjustment for participating in component analysis amendment should be slow.
As preferred：Described step 7）In, operation rate：0.2%/min ~ 0.33%/min, and every 3 ~ 5 minutes become Change 1% load；The operation of device can be according to the demand of gas and fluid product come adjust automatically, by setting under a certain operating mode The flow of final products, according to material balance, the conservation of energy come the anti-crucial intermediate parameters released under the operating mode, including：Enter Ice chest air capacity, expanded air amount, expansion nitrogen amount, middle pressure air capacity, pressure-air amount, High pressure liquid air amount, liquefying power；From And the flow on critical workflow pipeline is further extrapolated, the liquid level of critical container；Control valve aperture is gone by PID controller So as to adjust corresponding flow, liquid level these key parameters so that the product that produces after stabilization of device air separation unit it is stable, Load is converted on the premise of purity is up to standard；
Described step 8）In, the entry condition of Automatic load change is：
A) related PID control is in auto state；
B) air separation unit is stable；
C) ice chest air capacity is entered in normal range (NR)；
D) gas oxygen product yield is in normal range (NR)；
E) analyzer for participating in amendment is switched to corresponding analysis measuring point；
F) PID controller of amendment is participated in auto state；
- meet above-mentioned condition after, control system picture can show that " permission Automatic load change " is prompted, and click on manually " automatic to become negative Lotus puts into button "；
The stop condition of Automatic load change is：
A) air separation unit stops；
B) enter ice chest air capacity to overrun；
C) gas oxygen product yield overruns；
D) " Automatic load change releasing button " is clicked on manually.
Automatic load change control method of the present invention need not add extra software and hardware, participate in conventional control System（DCS or PLC）Can is realized；Control that need not be complicated can be achieved between different operating modes it is stable, smooth, quickly from Dynamic varying duty process；Present invention mainly solves the mutual decoupling of energy during air separation unit varying duty and material, easy overshoot The problems such as with vibration, on the premise of ensureing air separation unit stabilization and product quality, realize smooth, quick mistake between different operating modes Cross.
Embodiment
Below in conjunction with specific embodiment, the present invention will be described in detail：One kind of the present invention is used for air separation unit Automatic load change control method, described Automatic load change control method comprises the following steps：
1）Obtain each operating mode of air separation unit flow scheme design（Including at least minimum operating mode and maximum duty）Lower critical workflow ginseng Several PFD data；Air separation unit flow scheme design, more using general process scheme simulation softwards such as Aspen Plus or HYSYS；
2）It is determined as the variable of final products flow：Low oxygen product flow LPOG, low-pressure nitrogen product flow LPNG, argon Gas product flow ArG, liquid nitrogen product flow NL；Liquid oxygen product flow OL；These variables are as process operator varying duty process The desired value of middle setting；
3）It is determined that crucial intermediate variable：AIRtot enter ice chest air capacity, NLeq liquefying powers, AIRturb expanded airs amount, NGturb expansions nitrogen quantity, HPAIR pressure-airs amount, HPALhp High pressure liquid air amounts；These crucial intermediate variables are used for calculating finally The set point of PID controller；
4) PID controller of participation Automatic load change is determined：FIC1294（Sky is controlled by adjusting main compressor inlet guide vane Throughput）, HPair FIC7418 pressure-airs amount, the dirty nitrogen flow FIC1213 of regeneration, dirty nitrogen pressure PIC1626, FIC1556 High pressure liquid airs, the backflow of FIC1557 lean solutions（Adjust the reflux ratio of medium pressure column hypomere and lower pressure column upper end）, FIC1558 liquid Nitrogen flows back（Top of tower reflux ratio and purity in regulation）, LIC1601 oxygen-enriched liquid airs liquid level, FIC1520 low-pressure nitrogens flow, FIC1501 high pressure nitrogens flow, FIC1510 low oxygens flow, FIC1540 argon flow amounts, FIC1630 liquid nitrogen gas product streams Amount, the thick liquid argon flows of FIC1704, FIC1731 medium pressure nitrogens gas to evaporator of pure argon column flow, LIC1701 crude argon column oxygen-enriched liquid airs Liquid level；
5）Step 2 is obtained by fitting）With step 3）Between middle parameter, with step 3）Middle variable is dependent variable, step 2）In Variable is the fitting function of independent variable；
6）Step 3 is obtained by fitting）With step 4）Between middle parameter, with step 4）Middle variable is dependent variable, step 3）In Variable is the fitting function of independent variable；
7）For the work point data under same technological parameter difference operating mode, by polynomial function come each operating point mould of interpolation Type, obtain the varying duty linear change track of the technological parameter；Wherein business-critical needs to go to correct with component, and liquid level needs to limit Make within the specific limits, so that the product that device produces after stabilization converts on the premise of air separation unit stabilization, purity are up to standard Load；
8）The startup of Automatic load change and stopping needs meeting some requirements.
9）According to the difference of flow, above parameter can increase or decrease.
Further embodiment of the present invention is：Described step 5）In, the functional relation of independent variable and dependent variable is as follows：
AIRtot=func (LPOG, OL), it is fitted to obtain function by the parameter value of AIRtot, LPOG, OL under different operating modes,
The oxygen content of crude argon column charging is used for correcting AIRtot；Revised functional relation be AIRtot*=func (LPOG, OL)+AIC1716 wherein AIC1716 corrections are +/- the 10% of AIRtot design discharges；
NLeq=func (NL, OL, FIC1704) characterizes the ability of production fluid product；
AIRturb=func (AIRtot, NLeq) maintains overall ice chest balance（Ice chest heat leak, heat exchanger warm end temperature difference It has been sent to the liquid of each storage tank）；
NGturb=func (AIRtot, NLeq) maintains overall ice chest balance（Ice chest heat leak, heat exchanger warm end temperature difference It has been sent to the liquid of each storage tank）；
The pressure-air amount that HPair=FIC7418 production low oxygens need；
It is into ice chest air capacity that air capacity and pressure-air amount sum are pressed in MPair=AIRtot-HPair；
Liquid is obtained after the expansion of HPALhp=HPair-FIC1556 pressure-airs, partly enters medium pressure column, another part enters low Press tower；The flow of lower pressure column is removed in regulation, and to maintain the reflux for comparing, this strand of liquefied air flow is adjusted the charging of lower pressure column by FIC1556 Valve FV1556 is controlled；HPALhp is only intermediate variable, is not involved in varying duty.
In described step 6, thick liquid argon flow RSP [FIC1704]=func (AIRtot)；
Air total amount FIC1294=func (AIRtot)+IA, wherein IA instrument airs flow, generally definite value；
Dirty nitrogen flow FIC1213=func (AIRtot)；
Dirty nitrogen pressure PIC1626=func (AIRtot, LPNG)；
Liquid air FIC1556=func (AIRtot)；
Lean solution backflow FIC1557=func (AIRtot)；
Liquid nitrogen reflux FIC1558=func (AIRtot, MPNG)；
Oxygen-enriched liquid air liquid level LIC1601=func (AIRtot), wherein upper and lower spacing high and low alarm when being industrial design is set Fixed point；
Low pressure nitrogen flow FIC1520=LPNG；
Medium pressure nitrogen throughput FIC1501=func (AIRtot)；
Low pressure oxygen flow FIC1510=LPOG；
Argon flow amount FIC1540=ArG；
Liquid nitrogen flow FIC1630=NL；
Thick liquid argon flow FIC1704=func (AIRtot)；
FIC1731 = func(FIC1704)；
LIC1701=func (AIRtot), wherein upper and lower spacing high and low alarm settings point when being industrial design；
Air expander air mass flow FIC1530=AIRturb；
The road flow FIC1502=NGturb of low-pressure nitrogen 1；
Participate in the constituent analysis measuring point of amendment：Oxygen content, crude argon column middle part oxygen content, forward direction compensation in the middle part of lower pressure column；
Top exit is thick liquid argon（CAL）；Thick liquid argon is admitted to pure argon column K11；Thick liquid argon flow is according to the air for entering ice chest Total amount calculates, and is corrected by the purity analyzer AIC1705 output valves in argon column stage casing；
RSP[FIC1704]* = func(AIRtot) + AIC1705；
AIC1705 extent of amendment is +/- 20 % of the maximum mixed traffic of thick liquid argon；Because the response time of argon column is longer, So the PID adjustment for participating in component analysis amendment should be slow；
Further embodiment is：Described step 7）In, operation rate：0.2%/min ~ 0.33%/min（Every 3 ~ 5 minutes Change 1% load）；
The operation of device can finally be produced according to the demand of gas and fluid product come adjust automatically by setting under a certain operating mode The flow of product（Gas oxygen, gas nitrogen, gas argon, liquid oxygen, liquid nitrogen, liquid argon etc.）, according to material balance, the conservation of energy releases the operating mode come counter Under crucial intermediate parameters, such as：It is empty to enter ice chest air capacity, expanded air amount, expansion nitrogen amount, middle pressure air capacity, high pressure Tolerance, High pressure liquid air amount, liquefying power etc.；So as to further extrapolate the flow on critical workflow pipeline, the liquid of critical container Position etc., goes control valve aperture so as to adjust the key parameters such as corresponding flow, liquid level, so that device exists by PID controller The product produced after stable converts load on the premise of air separation unit stabilization, purity are up to standard.
Described step 8）In, the entry condition of Automatic load change is：
A) related PID control is in auto state；
B) air separation unit is stable；
C) ice chest air capacity is entered in normal range (NR)；
D) gas oxygen product yield is in normal range (NR)；
E) analyzer for participating in amendment is switched to corresponding analysis measuring point；
F) PID controller of amendment is participated in auto state；
- meet above-mentioned condition after, control system picture can show that " permission Automatic load change " is prompted, and click on manually " automatic to become negative Lotus puts into button "；
The stop condition of Automatic load change is：
A) air separation unit stops；
B) enter ice chest air capacity to overrun；
C) gas oxygen product yield overruns；
D) " Automatic load change releasing button " is clicked on manually.

Claims (3)

  1. A kind of 1. Automatic load change control method for air separation unit, it is characterised in that described Automatic load change control method Comprise the following steps：
    1）Obtain each operating mode of air separation unit flow scheme design, including at least crucial process parameter under minimum operating mode and maximum duty PFD data；
    2）It is determined as the variable of final products flow：Low oxygen product flow LPOG, low-pressure nitrogen product flow LPNG, argon Gas product flow ArG, liquid nitrogen product flow NL；Liquid oxygen product flow OL；These variables are as process operator varying duty process The desired value of middle setting；
    3）It is determined that crucial intermediate variable：AIRtot enter ice chest air capacity, NLeq liquefying powers, AIRturb expanded airs amount, NGturb expansions nitrogen quantity, HPAIR pressure-airs amount, HPALhp High pressure liquid air amounts；These crucial intermediate variables are used for calculating finally The set point of PID controller；
    4) PID controller of participation Automatic load change is determined：Air mass flow is controlled by adjusting main compressor inlet guide vane FIC1294, pressure-air amount HPair FIC7418, the dirty nitrogen flow FIC1213 of regeneration, dirty nitrogen pressure PIC1626, high pressure Lean solution backflow FIC1557, the top of tower in regulation of liquid air FIC1556, regulation medium pressure column hypomere and lower pressure column upper end reflux ratio The liquid nitrogen reflux FIC1558 of reflux ratio and purity, oxygen-enriched liquid air liquid level LIC1601, low-pressure nitrogen flow FIC1520, elevated pressure nitrogen Throughput FIC1501, low oxygen flow FIC1510, argon flow amount FIC1540, liquid nitrogen gas product flow FIC1630, The thick liquid argon flows of FIC1704, medium pressure nitrogen gas to evaporator of pure argon column flow FIC1731, crude argon column oxygen-enriched liquid air liquid level LIC1701；
    5）Step 2 is obtained by fitting）With step 3）It is between middle parameter, with step 3）Middle variable is dependent variable, step 2）In Variable is the fitting function of independent variable；
    6）Step 3 is obtained by fitting）With step 4）It is between middle parameter, with step 4）Middle variable is dependent variable, step 3）In Variable is the fitting function of independent variable；
    7）For the work point data under same technological parameter difference operating mode, by polynomial function come each operating point mould of interpolation Type, obtain the varying duty linear change track of the technological parameter；Wherein business-critical needs to go to correct with component, and liquid level needs to limit Make within the specific limits, so that the product that device produces after stabilization converts on the premise of air separation unit stabilization, purity are up to standard Load；
    8）The startup of Automatic load change and stopping needs meeting some requirements；
    9）According to the difference of flow, above parameter can increase or decrease.
  2. 2. the Automatic load change control method according to claim 1 for air separation unit, it is characterised in that：
    Described step 5）In, the functional relation of independent variable and dependent variable is as follows：
    AIRtot=func (LPOG, OL), it is fitted to obtain function by the parameter value of AIRtot, LPOG, OL under different operating modes,
    The oxygen content of crude argon column charging is used for correcting AIRtot；
    Revised functional relation is that AIRtot*=func (LPOG, OL)+AIC1716 wherein AIC1716 corrections are +/- the 10% of AIRtot design discharges；
    NLeq=func (NL, OL, FIC1704) characterizes the ability of production fluid product；
    AIRturb=func (AIRtot, NLeq) maintains overall ice chest balance；
    NGturb=func (AIRtot, NLeq) maintains overall ice chest balance；
    The pressure-air amount that HPair=FIC7418 production low oxygens need；
    It is into ice chest air capacity that air capacity and pressure-air amount sum are pressed in MPair=AIRtot-HPair；
    Liquid is obtained after the expansion of HPALhp=HPair-FIC1556 pressure-airs, partly enters medium pressure column, another part enters low Press tower；The flow of lower pressure column is removed in regulation, and to maintain the reflux for comparing, this strand of liquefied air flow is adjusted the charging of lower pressure column by FIC1556 Valve FV1556 is controlled；HPALhp is only intermediate variable, is not involved in varying duty；
    In described step 6, thick liquid argon flow RSP [FIC1704]=func (AIRtot)；
    Air total amount FIC1294=func (AIRtot)+IA, wherein IA instrument airs flow, generally definite value；
    Dirty nitrogen flow FIC1213=func (AIRtot)；
    Dirty nitrogen pressure PIC1626=func (AIRtot, LPNG)；
    Liquid air FIC1556=func (AIRtot)；
    Lean solution backflow FIC1557=func (AIRtot)；
    Liquid nitrogen reflux FIC1558=func (AIRtot, MPNG)；
    Oxygen-enriched liquid air liquid level LIC1601=func (AIRtot), wherein upper and lower spacing high and low alarm when being industrial design is set Fixed point；
    Low pressure nitrogen flow FIC1520=LPNG；
    Medium pressure nitrogen throughput FIC1501=func (AIRtot)；
    Low pressure oxygen flow FIC1510=LPOG；
    Argon flow amount FIC1540=ArG；
    Liquid nitrogen flow FIC1630=NL；
    Thick liquid argon flow FIC1704=func (AIRtot)；
    FIC1731 = func(FIC1704)；
    LIC1701=func (AIRtot), wherein upper and lower spacing high and low alarm settings point when being industrial design；
    Air expander air mass flow FIC1530=AIRturb；
    The road flow FIC1502=NGturb of low-pressure nitrogen 1；
    Participate in the constituent analysis measuring point of amendment：Oxygen content, crude argon column middle part oxygen content, forward direction compensation in the middle part of lower pressure column；
    Top exit is thick liquid argon（CAL）, thick liquid argon is admitted to pure argon column K11, and thick liquid argon flow is according to the air for entering ice chest Total amount calculates, and is corrected by the purity analyzer AIC1705 output valves in argon column stage casing；
    RSP[FIC1704]* = func(AIRtot) + AIC1705；
    AIC1705 extent of amendment is +/- 20 % of the maximum mixed traffic of thick liquid argon, because the response time of argon column is longer, So the PID adjustment for participating in component analysis amendment should be slow.
  3. 3. the Automatic load change control method according to claim 1 for air separation unit, it is characterised in that：
    Described step 7）In, operation rate：0.2%/min ~ 0.33%/min, and every 3 ~ 5 minutes 1% loads of change；Device Operation can be according to the demand of gas and fluid product come adjust automatically, by the stream for setting final products under a certain operating mode Amount, according to material balance, the conservation of energy come the anti-crucial intermediate parameters released under the operating mode, including：Enter ice chest air capacity, swollen Swollen air capacity, expansion nitrogen amount, middle pressure air capacity, pressure-air amount, High pressure liquid air amount, liquefying power；So as to further calculate The flow gone out on critical workflow pipeline, the liquid level of critical container；It is corresponding so as to adjust to go control valve aperture by PID controller Flow, liquid level these key parameters so that the product that produces after stabilization of device is before air separation unit is stable, purity is up to standard Put conversion load；
    Described step 8）In, the entry condition of Automatic load change is：
    A) related PID control is in auto state；
    B) air separation unit is stable；
    C) ice chest air capacity is entered in normal range (NR)；
    D) gas oxygen product yield is in normal range (NR)；
    E) analyzer for participating in amendment is switched to corresponding analysis measuring point；
    F) PID controller of amendment is participated in auto state；
    After meeting above-mentioned condition, control system picture can show that " permission Automatic load change " is prompted, and click on " Automatic load change manually Put into button "；
    The stop condition of Automatic load change is：
    A) air separation unit stops；
    B) enter ice chest air capacity to overrun；
    C) gas oxygen product yield overruns；
    D) " Automatic load change releasing button " is clicked on manually.
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CN114484263A (en) * 2022-01-07 2022-05-13 首钢京唐钢铁联合有限责任公司 Automatic load changing method and system for nitrogen-oxygen liquefaction device
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CN117537573A (en) * 2023-11-13 2024-02-09 广州广钢气体能源股份有限公司 Intelligent control method, system, equipment and storage medium for air separation device

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