Circuito de Control de Molienda 05_universite_laval_mr_desbiens

7/29/2019 Circuito de Control de Molienda 05_universite_laval_mr_desbiens

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Using Control for Adding ValueUsing Control for Adding Valueto Energy Efficiency of Mineralto Energy Efficiency of Mineral

Processing PlantsProcessing PlantsAndrAndr DesbiensDesbiens 11, Eduardo Nez, Eduardo Nez 11, Rene del Villar, Rene del Villar 22,,

DanielDaniel HodouinHodouin 22,, ricric PoulinPoulin 33

LOOP (Laboratoire dobservation et doptimisation des procds)LOOP (Laboratoire dobservation et doptimisation des procds)11 Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering

22 Department of Mining, Metallurgical and Materials EngineeringDepartment of Mining, Metallurgical and Materials Engineering

Universit Laval,Universit Laval, QuebecQuebec City,City, QuebecQuebec, Canada, Canada

33 Breton Banville etBreton Banville et assass..

MontMont--SaintSaint--HilaireHilaire, Quebec, Canada, Quebec, Canada

IntroductionIntroduction EnergyEnergyefficiencyefficiencyandand thethe mineralmineral processingprocessingplantsplants

ExampleExample ofofpressure forpressure for energyenergyeffciencyeffciency

TwoTwo approachesapproaches toto increaseincrease energyenergyefficiencyefficiency

OnOn--line dataline data processingprocessing

ProcessProcess observationobservation ProcessProcess controlcontrol

ProcessProcess optimizationoptimization

CaseCase studiesstudies ObservationObservation andand controlcontrol ofofaa grindinggrindingcircuitcircuit

ControlControl ofofaa grindinggrindingcircuitcircuit

Observation, control and optimization of electric arc furnacesObservation, control and optimization of electric arc furnaces

Optimization of anOptimization of an indurationinduration furnacefurnace

ConclusionConclusion

OUTLINEOUTLINE


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INTRODUCTIONINTRODUCTION -- EnergyEnergy efficiencyefficiency andandthethe mineralmineralprocessingprocessingplantsplants

Globalization

Environmentaland social

pressure forenergy efficiency

Energy costs

Internationalcompetition

Energy efficiency challengebecomes unavoidable.

Intensive

energyconsumers

Objectives:Reducing production costsIncreasing throughputIncreasing product quality

HydroHydro--Qubec:Qubec:

QuebecQuebec hydroelectricalhydroelectrical producer andproducer and

distributor.distributor.

Most extensive transmission systemMost extensive transmission systemin North America (32539 km).in North America (32539 km).

Pool up to 165Pool up to 165TWhTWh/year (93%/year (93%

hydroelectric).hydroelectric).

Offers financial assistance to largeOffers financial assistance to large--

power customers to reduce specificpower customers to reduce specific

energy consumption.energy consumption.

INTRODUCTIONINTRODUCTIONExampleExample ofofpressure forpressure for energyenergy effciencyeffciency


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First program:First program: Objective: to save 100Objective: to save 100 GWhGWh from 2003 to 2006.from 2003 to 2006.

Financial assistance budget: 8.5 M$.Financial assistance budget: 8.5 M$.

Customers must present their proposals.Customers must present their proposals.

They must agree to take measurements before andThey must agree to take measurements before andafter to show savings.after to show savings.

Payback period: 1 year.Payback period: 1 year.

Project completion: 18 months.Project completion: 18 months.

Customers must pay 25% of the total costs.Customers must pay 25% of the total costs.


Second program:Second program:

Financial assistance forFinancial assistance for

an energy consumption analysis at the industrialan energy consumption analysis at the industrial

site, orsite, or the demonstration that the firstthe demonstration that the first--timetime

implementation in Quebec of a new technologyimplementation in Quebec of a new technology

would result in energy savings.would result in energy savings.


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INTRODUCTIONINTRODUCTION -- TwoTwo approachesapproaches totoincreaseincrease energyenergy efficiencyefficiency

ApproachApproach 2:2:

OnOn--line dataline data processingprocessing:: judiciousjudicious onon--line useline use ofofprocessprocess sensorssensors andand largelarge operationoperation databasesdatabases..

ApproachApproach 1:1: ReplacingReplacingexistingexistingequipmentequipmentwithwith more efficientmore efficient

onesones..

InstallingInstallingnewnewequipmentequipment aimingaimingatat reducingreducing

specificspecific energyenergyconsumptionconsumption ofofexistingexistingprocessesprocesses..

ONON--LINE DATA PROCESSINGLINE DATA PROCESSING

Process

Actuators

Sensors

ObservationMeasurements

Quality

information

Control

Manipulatedvariables

Optimization

Setpoints

Knowledge aboutthe process

Knowledge aboutthe process

Measurements + knowledge = Possibility to automatically, continouslyand adequately manipulate actuators to achieve a specific objective.


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ONON--LINE DATA PROCESSINGLINE DATA PROCESSINGProcessProcess observationobservation

Process

Actuators

Sensors


Qualityinformation

Control


Optimization

Setpoints


Quality

information

ToTo seesee thethe processprocess states, tostates, to obtainobtain aa betterbetter picturepicture

ofofthethe processprocess.. ToTo detectdetect operationoperation problemsproblems,, abnormalabnormal

performances, etc.performances, etc.


FaultFault detectiondetection andand isolation:isolation:

RapidlyRapidlydetectdetect andand physicallyphysicallylocalizelocalize problemsproblems

suchsuch asas sensorsensor biaises,biaises, leaksleaks, etc., etc.

AllowAllowrapidrapid correctionscorrections reducingreducingbadbad

consequencesconsequences onon thethe production.production.

DataData reconciliationreconciliation::

ImprovesImproves thethe qualityqualityofofnoisynoisymeasurementsmeasurements..

MakesMakes themthem consistentconsistentwithwith processprocess knowledgeknowledge

suchsuch asas massmass andand energyenergyconservationconservation lawslaws..


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ObserversObservers::

SoftSoft sensorsensor algorithmsalgorithms..

TheyTheyinferinfer signalssignals thatthat cannotcannot bebe measuredmeasured..

TheThe availabilityavailabilityofofthesethese signalssignals cancan improveimprove thethe

plantplant operationoperation..

ProcessProcess observation:observation:

EvenEven ififnono automaticautomatic actions areactions are takentaken, a, a betterbettervisionvision allowsallows engineersengineers toto modifymodifyequipmentequipment oror

changechange operationoperationwhenwhen requiredrequired..

ONON--LINE DATA PROCESSINGLINE DATA PROCESSINGProcessProcess controlcontrol

Process

Actuators

Sensors


Qualityinformation

Control


Optimization

Setpoints

Manipulated

variables

Qualityinformation

Set

points

Control

ToTo maintainmaintain thethe measuredmeasuredvariablesvariables atat selectedselected setsetpoints bypoints byautomaticallyautomaticallyandand constinuouslyconstinuouslymanipulatingmanipulatingthethe actuatorsactuators..

MakesMakes useuse ofoffeedbackfeedbackandand feedforwardfeedforward..


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DisturbancesDisturbances ((suchsuch as changes inas changes in thethe oreorepropertiesproperties) must) must bebe quicklyquicklyrejectedrejected..

ProvidesProvides stabilizationstabilization aroundaround thethe set pointsset points andand aadecreasedecrease ofofthethe processprocessvariabilityvariability..

ONON--LINE DATA PROCESSINGLINE DATA PROCESSINGProcessProcess controlcontrol

Fineness

Duration

F

A

B

C

spAspB

spC

SmootherSmoother operationoperation..

LessLess costlycostlyoperationoperation ((eveneven ififset points areset points are notnot

changedchanged).).

ONON--LINE DATA PROCESSINGLINE DATA PROCESSINGProcessProcess optimizationoptimization

Process

Actuators

Sensors


Qualityinformation

Control


Optimization

SetpointsSet

points

Optimization

ToTo automaticallyautomaticallyselectselect thethe set points byset points byoptimizingoptimizingaa costcost functionfunction:: minimizationminimization ofofenergyenergyconsumptionconsumption,,

maximizingmaximizingprofits,profits,

etc.etc.


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ONON--LINE DATA PROCESSINGLINE DATA PROCESSINGProcessProcess optimizationoptimization

VeryVeryflexibleflexible tooltool:: SelectionSelection ofofthethe costcost functionfunction..

AdditionAddition ofofconstraintsconstraints suchsuch asas takingtakingintointo accountaccount

energyenergyconsumptionconsumption regulationsregulations..


AddedAddedvalues forvalues for energyenergysavingssavings..

ForFor severalseveral plants,plants, nono oror littlelittle newnewequipmentequipment

neededneeded..

SeveralSeveral additionaladditional benefitsbenefits::

BetterBetter knowledgeknowledge ofofthethe plant.plant.

ProductProduct qualityqualityrespectingrespectingmoremore oftenoften thethe specificationsspecifications..

ThroughputThroughput increaseincrease..

EasierEasier--toto--operateoperate plantplant thusthus more effective usemore effective use ofof

personnel.personnel.

DecreaseDecrease inin thethe maintenancemaintenance costscosts..


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EnergyEnergysavingssavings areare oftenoften underestimatedunderestimated becausebecausethethe plantplant unitsunits areare consideredconsidered separatelyseparately..

ExampleExample:: thethe optimizationoptimization ofofaa flotationflotation plantplant

DoesDoes notnot procureprocure anyanyrealreal energyenergysavingssavings..

May have importantMay have important energeticenergetic impacts onimpacts on subsequentsubsequent

processingprocessing((mealmeal extractionextraction andand smeltingsmelting).).

PlantPlantwisewise evaluationevaluation shouldshould bebe performedperformed

((howeverhowever, a, a difficultdifficult tasktask).).

Water

Pumpbox

Ball mill

Feed

Rod mill

Water

CASE STUDIESCASE STUDIES -- ObservationObservation andandcontrolcontrol ofofaa grindinggrinding circuitcircuit

Kidd CreekKidd Creekgrindinggrinding circuit control:circuit control:

Objectives (noneObjectives (none relatedrelated toto energyenergy):):

IncreaseIncrease plantplant throughputthroughput ((notnot an issue 2an issue 2 yearsyears laterlater).).

PreventPrevent pumppump boxbox levellevel andand cyclonecyclone overflowoverflowdensitydensityupsetsupsets..

StabilizeStabilize

productproduct qualityquality..


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DesignDesign basedbased on aon a phenomenologicalphenomenological simulatorsimulator((DynafragDynafrag).).

DynafragDynafragrequiredrequired toto bebe calibratedcalibrated: 3: 3 samplingsamplingcampainscampains..

Data reconciliation revealed some abnormalData reconciliation revealed some abnormaloperating conditions such as extremely high milloperating conditions such as extremely high millcirculating load ratios (CLR) (around 1800%).circulating load ratios (CLR) (around 1800%).

1800% CLR: 36501800% CLR: 3650 t/ht/h of pulp at the cyclone feedof pulp at the cyclone feed(250 HP for pumping)(250 HP for pumping)

500% CLR: 1154500% CLR: 1154 t/ht/h of pulp at the cyclone feedof pulp at the cyclone feed(55 HP for pumping)(55 HP for pumping)

1800% CLR: a pulp residence time within the mill1800% CLR: a pulp residence time within the mill

of about 0.5 minute.of about 0.5 minute.

500% CLR: 2 min residence time.500% CLR: 2 min residence time.

In other words: a lot more energy was spent inIn other words: a lot more energy was spent in

pumping a huge circulating load to achieve verypumping a huge circulating load to achieve very

little grinding.little grinding.



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FTWater

FC

LT

LC

Pump box

Ball mill

SP

SP

DC

SP

Feed

Water

SC

WT

M

RFC

FT

SPSP

Rod mill

DT

DT

DC

SP

Because of equipment and objectives changes, difficult toBecause of equipment and objectives changes, difficult to

quantify the energetic and metallurgical improvements.quantify the energetic and metallurgical improvements.

Total costs: around 0.2 M$.Total costs: around 0.2 M$.

Revenue improvements: conservativelyRevenue improvements: conservatively

estimated to 1 M$/annum.estimated to 1 M$/annum.


CASE STUDIESCASE STUDIESControlControl ofofaa grindinggrinding circuitcircuit

ToquepalaToquepala grindinggrinding circuit control:circuit control:

The rodThe rod--mill discharge is distributed to 3 parallel ballmill discharge is distributed to 3 parallel ball--

mills using a threemills using a three--way splitter.way splitter.

The operator decides the splitter palettes position.The operator decides the splitter palettes position.

Level of 3 sump boxesLevel of 3 sump boxes

controlled withcontrolled with

variable speed pumps.variable speed pumps.


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CASE STUDIESCASE STUDIESControlControl ofofaa grindinggrinding circuitcircuit

Results:Results:

Better stability of the circuit operation, particularly of theBetter stability of the circuit operation, particularly of thethree ball mills.three ball mills.

Tonnage increase from 245.7Tonnage increase from 245.7 t/ht/h to 253.6to 253.6 t/ht/h (2 % to 4%).(2 % to 4%).

Slightly finer product.Slightly finer product.

Reduction inReduction in monthly energy consumption from 1607750 kWh to 1528797 kWh.monthly energy consumption from 1607750 kWh to 1528797 kWh.

specific energy from 9.20 kWh/t to 8.42 kW/t (8% to 10%specific energy from 9.20 kWh/t to 8.42 kW/t (8% to 10%decrease).decrease).

A greater availability of operators.A greater availability of operators.

Total gains/year : 4.9 M$Total gains/year : 4.9 M$ If applied to the 8 lines of the concentrator: savings wouldIf applied to the 8 lines of the concentrator: savings would

be 8 x 900000 kWh/year.be 8 x 900000 kWh/year.

CASE STUDIESCASE STUDIES -- Observation, control andObservation, control andoptimization of electric arc furnacesoptimization of electric arc furnaces

Electric arc furnaces:Electric arc furnaces:

Consume a large amount of energy in ferroalloy and steelConsume a large amount of energy in ferroalloy and steel

industries.industries.

No direct measurement of how the energy is used inside theNo direct measurement of how the energy is used inside the

furnace is made.furnace is made. OnOn--line information about the internalline information about the internal behaviorbehavior of the furnace:of the furnace:

the arc signature (voltagethe arc signature (voltage--current characteristic at the tip of thecurrent characteristic at the tip of the

electrode).electrode).

Observation of the arc signature gives the possibility to inferObservation of the arc signature gives the possibility to infer

strategic variables such as length, stability, symmetry, dynamicstrategic variables such as length, stability, symmetry, dynamic

resistance and power dissipation of the arc.resistance and power dissipation of the arc.


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CASE STUDIESCASE STUDIES -- Observation, control andObservation, control andoptimization of electric arc furnacesoptimization of electric arc furnaces

Objectives:Objectives: Optimization of the energy usage.Optimization of the energy usage.

Reduction of the production costs.Reduction of the production costs.

Arc signature system combined to control have been testedArc signature system combined to control have been testedand installed on submerged arc furnaces and long arc furnacesand installed on submerged arc furnaces and long arc furnaceswith foamy slag.with foamy slag.

Typical results for submerged arc furnaces:Typical results for submerged arc furnaces: 5 % reduction of the specific consumption (5 % reduction of the specific consumption (MWh/tMWh/t).).

Increase of operating power and thus 25% increase of the productIncrease of operating power and thus 25% increase of the productionionrate.rate.

30% reduction in the amount of corrective loads to stabilize the30% reduction in the amount of corrective loads to stabilize thefurnace.furnace.

The signature is used to support operation, anticipate and preveThe signature is used to support operation, anticipate and preventntproblematic situations.problematic situations.

CASE STUDIESCASE STUDIESOptimization of anOptimization of an indurationinduration furnacefurnace

IndurationInduration furnace:furnace:

PC

V3

V2

V1

P6

P

P4

P2 P1

P0

T8 T7 T6

T4T5 T2 T1

T

Fm,PC Fm ,C2Fm,C1

Fp

T10

T3

T9

V4

P5

P

V5

P7 P3

P T

T11

T12

ogT

opT

UD DD Cooking 1 Cooling 2Cooling 1Cooking 2PC

V3

V2

V1

P6

Pi

P4

P2 P1

P0

T8 T7 T6

T4T5 T2 T1

Ti

Fm,PC FmFm

F

T10

T3

T9

V4

P5

Pi

V5

P7 P3

Z

Pi T i

T11

T12

gT

T

igFgF


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Optimization criterion must reflect precisely the producer objeOptimization criterion must reflect precisely the producer objectives:ctives:

to maximize the net revenue, i.e. the product value minus theto maximize the net revenue, i.e. the product value minus theproduction costs; may lead to a minimization of the total consumproduction costs; may lead to a minimization of the total consumededenergy, but not necessarily.energy, but not necessarily.

to maximize the production rate at constant energy consumption;to maximize the production rate at constant energy consumption;leads to the minimum energy consumption per ton of pellet producleads to the minimum energy consumption per ton of pellet produced,ed,but not to the minimal total energy consumption.but not to the minimal total energy consumption.

to maximize the product quality (to increase the product value)to maximize the product quality (to increase the product value) atatconstant production rate; will not be optimal for energy consumpconstant production rate; will not be optimal for energy consumption,tion,except if the total energy consumption is constrained at a predeexcept if the total energy consumption is constrained at a predefinedfinedvalue.value.

to find, at constant production rate and product quality, theto find, at constant production rate and product quality, thedistribution of consumed energy between the coke addition, the tdistribution of consumed energy between the coke addition, the threehreeburner zones and the five fans, which minimized the energy cost.burner zones and the five fans, which minimized the energy cost.

etc.etc.


the total energy per ton of product does not much varythe total energy per ton of product does not much vary

the total fuel consumption can widely varythe total fuel consumption can widely vary

the maximum profit (run 7) is not necessarily a goodthe maximum profit (run 7) is not necessarily a goodcriterion to maximize energy efficiencycriterion to maximize energy efficiency

111105100101103110108Normalized profits ($)

100.9101.3100.7100.6100101.0100.5Energy index per ton

0.8180.6740.8200.8200.8580.8200.820Total fuel (kg/s)

110103100101104109107Production rate index0, 5, 950, 6, 940, 5, 954, 10, 860,13, 870, 5, 954, 10, 86Fuel (%) at PC, C1, C2

ConstrConstrMaxMaxMaxConstrConstrPellet quality

OptOptOptNomOptOptNomFuel distribution

OptMinNomNomOptNomNomFuel consumption

OptNomOptOptNomMaxMaxProduction rate

7654321Simulation run


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CONCLUSIONCONCLUSION

ProcessProcess observation, controlobservation, control andand optimizationoptimization:: increaseincrease thethe energyenergyefficiencyefficiency,,

provideprovide severalseveral additionaladditional benefitsbenefits,,

oftenoften requirerequire nono oror littlelittle newnewequipmentequipment..

ThroughThrough thethe implementationimplementation,, thethe plant personnelplant personnelwillwill

mostmost likelylikelydiscoverdiscover problemsproblemswithwith equipmentequipment oror

operationoperation..

Thank you!

11th IFAC Symposium on

Automation in MMM Processing

2007

Qubec City, Canada

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Circuito de Control de Molienda 05_universite_laval_mr_desbiens