Aspentech - Power Plant Optimization

©2000 AspenTech. All Rights Reserved.

Power Plant Optimization

2©2000 AspenTech. All Rights Reserved.

Why Focus On Energy / Utilities?

• Energy is the single largest operating expense after raw materials in the process industries

• “The best spend less than 50% on total energy cost compared to the worst.” (Solomon)

• Deregulation has opened up new opportunities / threats

• Linked to CO2 / NOX / SOX

• Energy costs are rising in some regions


Energy Optimization Goals

• Minimize Operating Costs / Maximize Profit while:– Meeting electrical, steam, hydrogen and offgas

demands– Honoring operating/equipment constraints– Honoring contract constraints– Environmental concerns (NOx, CO, etc.)


Site Wide Energy SystemPower Import/Export

ProcessA

ProcessB

ProcessC

ProcessD

Fuel

ProductSide-ProductFeed

ProductFeedSide-Product

Energy System

WaterSystem

GasSysteme.g.H2

Production System

Fuel Import/Export Water

WasteWater

Emissions (CO2, SOx, NOx)

• Combined production and energy system analysis is required• Interactions between energy - water and off-gas system considered• Constraints from out of site bound should be considered


Utility System Operation Challenges

Which boilers should I use and at what load should I run these boilers?Which boilers should I use and at what load should I run these boilers?

Is it economic to run my steam turbine generator?Is it economic to run my steam turbine generator?

What drives should I use for the BFW pump?

What drives should I use for the BFW pump?

At what load should I run the GTG?At what load should I run the GTG?

What is the lowestoperating cost?

What is the lowestoperating cost?

What fuels should I use and how much should I purchase –what contract?

What fuels should I use and how much should I purchase –what contract?

How much electricity should I purchase, how much could I sell and at what price?

How much electricity should I purchase, how much could I sell and at what price?

How much steam do I need to provide today, tomorrow, next week? How does Actual compare to Plan?

How much steam do I need to provide today, tomorrow, next week? How does Actual compare to Plan?

How is my equipment performing? When should I shut down for maintenance?

How is my equipment performing? When should I shut down for maintenance?

• Many decisions to be made under many constraints• How can we consider all aspects simultaneously?• Many decisions to be made under many constraints• How can we consider all aspects simultaneously?


Optimization Pyramid

OpenOpen--LoopLoopAdvisoryAdvisory

SystemSystem

ClosedClosed--Loop OptimizationLoop Optimization

Multivariable ControlMultivariable Control

Control & AutomationControl & Automation

InstrumentationInstrumentation


SystemSystem






Life Cycle Energy Management


Lessons Learned

• Find the benefits1. What is 1% of your energy bill?2. What is your complexity and flexibility?3. Can you estimate the performance of the equipment?

• Get the benefits1. One time effort is not enough2. You must deal with whatever pushes away from the optimum3. Measurements are important4. Automation is the key to continued benefits


Aspen Utilities Solution Overview

Tariffs

Operational Constraints

Plant Demands

Closed Loop Optimization• Load distribution• Multiple objective functionsO

PER

ATI

ON

S TO

OL

Tariffscenarios

Seasonalvariations

Changes in demande.g. site expansion

What-if Analysis• Turbine/ boiler on/off decisions • Tariff selection• Optimize Investment options• Significant changes in demands• Changes in fuel supply

STRA

TEGIC

TOO

L

DCS

Multi-variable Predictive Control

On-line Open Loop Decision

Making

On-line Open Loop Decision

Making

Lowest Cost Scheme

Lowest Cost Scheme

On-line Closed Loop OptimizationOn-line Closed

Loop Optimization

Lowest Cost Operation

Lowest Cost Operation


Strategic Solution - Advisory

• Solution Integrated/Consistent with Operation Solution

• Long-term Issues– Contract Selection/Negotiation– Capital Investment

• Short-medium term issues– Equipment selection optimization (on/off decisions)– Maintenance– Performance monitoring

• Optimization– MILP solver with multi-period optimization capability - can include

process production planning– Off-line decision making / On-line decision support


Demand Forecast

Considering steam demand profile behavior into optimization

Time

Steam DemandT/hr

0 hours 48 hours

Do not start a new turbineSwitch turbine 2 on


Contract Optimization

Time

Gas DemandM3/hr

Jan April Oct DecJuly

8000 hr Average(determined at end of year)

Peak Load

demands subject to incidental gas price (planned upfront)

Middle Load

Base Load

HUG contract value(planned up front)

Electricityuse

230

25 gld/kWh

2.5 gld/kWh[MWe]

225

180

Chronological year

Peak load

Middle loadTransport boundary

Base load

Gas Contract Structure

Elect. Contract Structure

Electricity Contract

0

20

40

60

80

100

1200:00

1:00

2:00

3:00

4:00

5:00

6:00

7:00

8:00

9:00

10:00

11:0012:00

13:00

14:00

15:00

16:00

17:00

18:00

19:00

20:00

21:00

22:00

23:00

Jan. - Mar.Apr.-Jun.SepJul.-Aug.Oct-Dec.


Contract optimization

Jan

GasM3/hr

Jan DecOne profile for each header Consumer gas & electricity requirement

SteamT/hr

Dec

Elect.MWe

Jan Dec

Iterations(new tariff constants)

N-1 and equipment operational constraints

Alternative fuel availability

Gas & elect.bill for selected contract

GasM3/hr

Jan Dec

ElectMWe

Jan Dec

Past ProfileOptimized Profile

Site wide gas and electricity demands

Utilities Optimizer


Operations Solution – Closed Loop

• Tightly Integrated Package– Advanced Process Control - DMCplus– Real Time Optimization –AspenPlus Optimizer– Proven Reliability

• Integrated Goals– Tie line control– Constraint handling– Boiler, turbine load allocation– Performance Monitoring


Operations – Closed Loop

• AspenPlus Optimizer calculates optimal operation for current state of process utilizing a rigorous model of process– Buy/Sell (within constraints) – Turbine/boiler loading

• DMCplus implements optimization targets and handles constraints and changes in demands and process between optimization solutions


When Do You Need RTO ?

• High degree of non-linearity.– Can be fundamentally modeled.

• Frequent disturbances.– Correct time scale.– Changing economics and plant constraints.

• Significant degrees of freedom with substantial benefits.– Sufficient application scope.


AspenPlus Optimizer

• Closed Loop Real Time Optimization

• Based on fundamental non-linear models

• Frequent optimization cycles – Model calibrated to plant each run (parameters updated)– Uses current economics and constraints– Cycle times of ~5 minutes

• Handles complex Constraints

• Handles tier pricing

• Consistency with APC and Strategic Model

• Facilitates performance monitoring


Closed Loop Optimization Sequence

Full Plant Measurements

LINE-OUT PERIOD

WAITPLANT STEADY?

MEASUREMENTVALIDATION

PARAMETERCALCULATIONS

OPTIMIZATIONCALCULATIONS

IMPLEMENT OPT.SETPOINTS

NO

NO

Selected PlantMeasurements

Selected PlantMeasurements &Controller Limits

PLANT STEADY?

1 MINUTE

1 MINUTE

Controller Limits

Control and Opt. Status Info

Prices


Closed Loop Optimization Benefits

Time (Minutes)

Uni

tPro

fitab

ilify

($) major disturbance/ price change

actual unit profit

potential unit profit

RTO Implementations


0

0.005

0.01

0.015

0.02

0.025

1999/7/1

1999/7/15

1999/7/29

1999/8/12

1999/8/26

1999/9/9

1999/9/23

1999/10/7

1999/10/21

1999/11/4

1999/11/18

1999/12/2

1999/12/16

1999/12/30

2000/1/13

2000/1/27

2000/2/10

2000/2/24

2000/3/9

2000/3/23

Foul

ing

Fact

or [m

2hC

/kca

l]

250

270

290

310

330

350

370

390

410

Out

let T

emp.

of E

xhas

t Gas

[C]

ボイラー汚れ係数１ m 2hC /kcal ボイラー汚れ係数２ m 2hC /kcal ボイラー汚れ係数３ m 2hC /kcal ボイラー排ガス温度Ｃ

Temp. of Exhaust Gas

Fouling of 1st Super heater

Fouling of 2nd /3rd Super heater

Outage of Plant

-Strong correlations between Boiler Fouling and Outlet Temp. of Exhaust Gas

- Assumed the fouling was removed by Thermal shock at the outage of Plant

Analysis & Management of Boiler Fouling

Fouling in Economizer


DMCplus

• Dynamic multivariable control– Moves multiple variables simultaneously – Controls multiple variables simultaneously

• Operates at a scheduled high frequency– Typically 15 sec. in utilities plant

• Reduces variability in key variables

• Honors constraints

• Automatically handles reconfiguration of equipment and control system


Benefits of DMCplus

APCEconomic Optimum

Operating Region

Equipment Constraints

Temperatures

Steam Demands

Power DemandReserve Requirements

Condensate Supply

Operator'sPreferredOperating

Region


64

66

68

70

72

74

76

0 240 480 720 960time [min.]

220

240

260

280???

? ???

Power Generation

Control Start

Exhaust Steam FlowrateUpper Limits

Pow

er G

ener

atio

n [M

WH

/H]

Exha

ust S

team

Flo

wra

te[T

/H]


Aspen Utilities Growing Customer Base

WorkshopWorkshop Implementation

DSM, DSM, Geleen Geleen (Netherlands)(Netherlands)

1998

Titan, MalaysiaTitan, Malaysia1999

Huntsman, TexasHuntsman, Texas

BP Chemicals, HullBP Chemicals, Hull

CepsaCepsa, Spain, Spain

JSR, JapanJSR, Japan

BP BP Bulwer Bulwer Island, Island, AustraliaAustralia

2000

CelaneseCelanese((66 sitessites -- WWWW))

Irving Oil, Irving Oil, NewfoundlandNewfoundland

Samsung, KoreaSamsung, Korea

2001BP Texas CityBP Texas City

GE PlasticsGE Plastics((55 sitessites -- WWWW))

EniPowerEniPower((22 sites sites -- ItalyItaly ))

BP Chemicals BP Chemicals BelgiumBelgium

Sasol, Sasol, SasolburgSasolburg

2002


Utilities Management & Optimization• Benefits

− Significant benefits possible− 1.5-5% reduction in site-wide energy bill

− Provides a consistent approach for all the utilities related management and operations issues− Consistent decision making from contracts to operation

• AspenTech Approach− Systematic project approach - Energy Workshop

Complete Solution

Software Technology Transfer

Project Services+ + =


Optimization Pyramid


SystemSystem






SystemSystem






CONTROL

STRATEGIC DECISIONS

CLOSED-LOOP OPTIMIZATION

To be successful you need to do all aspects well !!


Clients Include:

Most Major Chemical CompaniesMost Major Olefins ProducersMore than 1,000 successful projectsMore than 300 full plant onlineoptimization applications

Business Breakdown

Olefins32.5 %

Refining48.6 %Polymers

Air SeparationSpecialty ChemPower

Other 18.9 %

Most Major Oil Companies

AspenTech is the World Leader in APC & Optimization

PROVEN integration with all leading DCS platforms including:

Yokogawa, Bailey, Foxboro, ABB, Honeywell, Fisher-Rosemount

Thank You

Aspentech - Power Plant Optimization

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