how to save energy through enhanced automation

8/14/2019 How to Save Energy through Enhanced Automation

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Standards

Certification

Education & Training

Publishing

Conferences & Exhibits

How to Save Energy Through Enhanced Automation

AIChE Spring Meeting2008Douglas WhiteEmerson ProcessManagement


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2 2008 Emerson Process Management

Speaker

Doug White

Principal Consultant and VicePresident, APC Services

Advanced Applied Technologies

Process Systems and SolutionsEmerson Process Management

Many years experience designing, justifying, installing andcommissioning advanced real timecomputer applications in the process

industries.


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Natural Gas Prices

Natural Gas Prices (Henry Hub)

0

2

4

6

8

10

12

14

Jan-93 Jan-95 Jan-97 Jan-99 Jan-01 Jan-03 Jan-05 Jan-07 Jan-09

Date

$ / M M B T U

Forecast


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Process Energy Usage

27.238.8Styrene

2.12.9Ethylbenzene

5.07.1EG

4.36.2EO

2.84.0PVC

6.69.4EDC

4.76.7Polyethylene

5.07.1Ethylene

Chemicals

5.57.9Cement Production

20.329.0Integrated Pulp/Paper Mill3.14.4Petroleum Refining

Value; 10% EnergyReduction; $/ Ton

($7/ MMBTU)Process Energy;

MM BTU/ Ton

L a r g e s t C o

n t r o l l a b

l e C o s t

i n M o s t

P l a n t s !


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Session Objective

Present some case studies of the many ways thatautomation, advanced automation and assetmanagement can save energy in process plants


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Outline

How is energy used in process plants?

How can automation help save energy?

How do we implement an energy reduction program?


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PurchasedSteam

ProcessHeating/CoolingPurchased

Fuel

PurchasedPower

ProcessSteamDrives

ExportPower

ExportSteam

Export

Fuel

ProcessElectricDrives

ProcessFired

Equipment

ProcessSteamGenerated

ProcessDirect Fuel

Usage

CentralPower

Production

Central

SteamProduction

General Process Site Energy Flow

ProcessMisc Electric

Usage

Power PlantProcess and

Offsites

Raw MaterialAs Fuel


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PurchasedSteam


Fuel

PurchasedPower

ProcessSteamDrives

ExportPower

ExportSteam

Export

Fuel


ProcessFired

Equipment


ProcessDirect Fuel

Usage

CentralPower

Production

Central

SteamProduction

Average Chemical Site Energy Flow


Usage


Offsites

Raw MaterialAs Fuel

63%

37% 4%

32%

22%

1%

18%

27%

%-Equivalent BTU basis (Including losses) on total input


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PurchasedSteam


Fuel

PurchasedPower

ProcessSteamDrives

ExportPower

ExportSteam

Export

Fuel


ProcessFired

Equipment


ProcessDirect Fuel

Usage

CentralPower

Production

Central

SteamProduction

Integrated Pulping Paper Mill Energy Flow

Process/ FacMisc Electric

Usage


Offsites

Raw MaterialAs Fuel

50%

42%

8%29%

25%

62%

5%


4%


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PurchasedSteam


Fuel

PurchasedPower

ProcessSteamDrives

ExportPower

ExportSteam

Export

Fuel


ProcessFired

Equipment


ProcessDirect Fuel

Usage

CentralPower

Production

Central

SteamProduction

Oil Refinery Energy Flow


Usage


Offsites

Raw MaterialAs Fuel

64%

25%

10%

1%

15%

5%

34%

44%


6%


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Reducing Plant Energy Costs

Reduce Usage Individual Equipment

Improve Efficiencies Boilers, Heaters, kilns Maximize Useful Recovery - Preheat

Minimize Losses Cooling water Minimize Motor Losses

Unit Savings Optimize Process Unit Operations

Distillation/ Fractionation Maximize Waste Heat Recovery Minimize waste/ off spec

Site/ Multi Unit Savings Minimize Steam Losses and Downgrading Switch of steam drives for electric or vice versa Seasonal effects

Reduce Cost of Production and Purchase Fuel Substitution Generation Maximization Boiler and Turbine Allocation Electric Purchase Optimization

Automation and Advanced Automation are the keys to effective operation and minimum ongoing energy usage


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Process Industry Energy Saving Primary Targets

Fired Heaters

Distillation/ Fractionation

Central Power and Steam Production


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How can Automation Reduce EnergyUsage?


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Variability Potential Energy Savings

Example Heater Stack O2 Variability

2

3

4

5

6

7

8

9

10

11

12

8:00 9:00 10:00 11:00 12:00 13:00 14:00

Time

O2, %

0

100

200

300

400

500

600

700

800

Fuel Gas

Flow

Target


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Energy Savings Through Automation Target Areas

MassCont

DensFF

O2

PITC

FuelGas

PI

FI

DraftControl

FC3-5

FT3-5

Bottoms

FC3-5FC3-5

FT3-5

Bottoms

Device,

Loop

Equipment

ProcessUnit

Site- Wide


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Saving Energy Automation Examples

Better ControlValve Performance

ImprovedMeasurements

FC3-5

FT3-5

FC3-5FC3-5

FT3-5

Improved Loop/ Multi-loopControl Performance


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Component Heating Values

1184032010Butane

1204024320Propane

1241016820Ethane

132809520Methane

339103020Hydrogen

Heat of Combustionkcal/ kg (gross)

Heat of Combustionkcal/ NM3 (gross)

Component

Fuel Gas ComponentHeating Value

Control Fuel Flows By Mass Instead of Volume


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Energy Savings From Improved Measurements

Hydrogen Plant

Objective: Control S/C ratio as close to 3.2 as possible but avoid going belowDisturbance: Fuel gas C1 77 85%; C2 6.8 15; N2, CO also fluctuate

Test: Normal orifice plus GC max error 0.2; MMI max error 0.02

Benefits: Moving 0.2 ratio closer to limit worth 8 BTU/SCF of H2;

80 MMSCFD plant; $7 MM BTU gas $1.6 MM per year

Ref: MMI WP_00724Mass Measurement


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Energy Losses Through Bypassing

14.30.4

6.80.25

3.20.14

Heat LossIncrease -%

F1 /(F1+ F 2)

TC TC

Reference:Shinskey;

Energy ConservationThrough Automation

Fuel

F2

F1

TC


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MassCont

DensFF

O2

PITC

FuelGas

PI

FI

DraftControl

Improved Multi-Loop

Control AdvancedControl

Improved PerformanceMonitoring

Improved Diagnostics

Energy Savings Equipment Level


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Steam System Control Issues

PIC3

PIC4 PIC2

FIC2 FIC1

PIC1

750 psig

50 psig

Condensate

TGA

TGBUsers

Vent

Vent

PRC1

0 4500 9000 13500 18000Sec

745.0748.0751.0754.0757.0

psig

Mean=750.814 3Sig=3.242FRC1

0 4500 9000 13500 18000Sec

300.0305.0310.0315.0320.0

mlb/hr

Mean=212.955 3Sig=6.987

Objective:Maximum

Flow to TGA

Problem:Pressure

Instability in

Header Limited Flowto TGA


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Steam System Diagnosis Valves and Tuning

5%

220 sec

PRC 1 OP

4800 5200 5600 6000 6400

Sec

52.00

54.00

56.00

58.00

60.00%Out

Mean=56.0123 3Sig=9.381

Sec

FRC2

4800 5200 5600 6000 6400Sec

209.6

213.7

217.8

221.8

225.9mlb/hr

Mean=114.983 3Sig=19.7

5%

220 sec Flow controller to TGBhas 5% deadband;

induces limit cycle inpressure

Correction:Fix TGB turbine

governor/steam valve

Tune controllers assystem not

individually

PRC1

4800 5200 5600 6000 6400Sec

748.3

749.5

750.6

751.8

752.9psig

Mean=650.814 3Sig=3.242

Estimated value of increased flow to TGA - $3000/ day


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Fired Heater Controls


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Combustion Control


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Heater/ Boiler Combustion Control Savings

$/ Yr Savings

100 MM BTU/ Hr $7/ kSCF Gas400 F Stack Gas Rise

$0

$100,000

$200,000

$300,000$400,000

$500,000

$600,000

2 3 5 7 10

% O2

$/ Yr


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Typical Heater APC Package

FIC101

H306

FIC102

TI069

TIC

361

FIC361

TI071

CO

CombustionControl

HIC353D

PIC359D

TIC362D

AIC354D

AIC356D

O2

FIC103

TI069

(Up to 4)

FIC104

TI070

TI073

TI

072

TI043

TI075

TI067

MPC Block

FuelDemand

Air Demand

PIC357D

PassBalance


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Excuses For Not Improving Heater Controls

Damper/ Air controls are not reliable Answer: Add positioners to dampers, with feedback to

control system; Analyze and fix controller problems

Dont have online analyzer/ cant maintain them Answer: Analyzers are cheaper and more reliable

particularly mass flow meters. With higher fuel costs, theyare well justified.


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Distillation Controls


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FCLC

FC

TC

FC

LC

Feed, F20,000 BPD

$50/ Bbl

Bottoms, B< 5 %C4 ; $70/ Bbl> 5%C4; $50/ Bbl

Distillate, D< 5%C5 ;$45/ Bbl> 5%C5; $38/ Bbl

Reflux,R

Reboiler,

E$36/ Bbl FOE

PC

AC

Typical Distillation Column

AR


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Distillation Column Control Savings

Cost Per Year Excess Reflux

20000 BPD Stabilizer Column$10/ MM BTU Steam

$0$100,000$200,000$300,000$400,000$500,000$600,000$700,000

5 10 25 50

% Excess Reflux

$/ Yr


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Column Pressure Effect

Relative Reboiler Cost Per Year Column Pressure Effect

20000 BPD Stabilizer

0%

20%

40%

60%

80%

100%

120%

100 120 140 160 180 200

Pressure, PSIA

Basis: Constant SeparationModeled With ChemSepPeng Robinson Equation of State


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Energy Savings Site Wide

Site Energy/ Utility Management

Steam System Control

Fuel System Control


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Energy Management and OptimizationSystem


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Plant Utility Systems Many Opportunities for Savings

MPS

HPS

Many interactingdecision variables

Large number of constraints

Unit 1 Unit 2

Unit 5

HRSG

DeminPlant

Condensate

LPS

BFW

FG

FB1FB1 FB2FB2 FB3FB3 WHB1WHB1 GT1GT1WHB2WHB2

ST1ST1 ST2ST2

Make-Up

PRVPRV

PRVPRVUnit 4

Vent

Vent

Vent

Unit 3


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Optimizer Decisions

Which boiler(s) should I run? What load? How much electricity should I produce? Buy? Sell?

Is it economic to run the steam turbine? Which fuel should I buy? How much? Should I be using more steam drives or more electric

drives? When will efficiency gain from maintenance balance

the cost of shut down for this equipment? How does my actual compare with plan corrected to

standard conditions?


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Unit 2Unit 1

LPS

ST1ST1 ST2ST2PRVPRV

PRVPRVDemin

Plant

Condensate

Make-Up

Unit 5Unit 3 Unit 4

HRSG

MPS

GT1GT1FB1FB1

HPS

BFW

FG

FB2FB2 FB3FB3 WHB1WHB1 WHB2WHB2

Full Utility Optimization

Many interactingdecision variables

Large number of constraints


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Overall Energy Optimization Strategy

Continuously Calculate Production Costs Over Load Range withCurrent Fuel Mix

Incorporate Constraints on All Equipment Decisions Made Through Rule Based Logic Boiler Load Allocation

Distribute Steam Production Based on Cost and Constraints

Turbine Load Allocation Distribute Steam for Minimum Cost with Constraints

Tie-Line Control Control Electrical Purchase Based on Economic Decision and

Constraints


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Boiler Load Allocation


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Load Allocation

50,000 75,00025,000Boiler Load, lb/hr

Boiler Efficiency

No. 1

No. 2

No. 3

80

85

90How to provide 200 kpph steam?

LoadMost

Efficient

Equal

Loads

MinimumCost

No. 4


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Energy Savings via Site Energy Balance

Blow-Down

Make-Up

Power

Fuel

1600 psia; 940 F

Flue Gas;200 F

200 psia

Steam;

125 psia

Condensate

1000 KW384pph

384pph

24,393kBTU/ hr

19200 pph

20,200pph

0kBTU/hr

Make-Up

Blow-

DownPower

Fuel

1600 psia; 94 0 F

Flue Gas;200 F

200 psia

Steam;

125 psiaCondensate

1000 KW271pph

271pph

18510kBTU/ hr

13550 pph

10,100pph

3754kBTU/hr 9600 pph

Reference: Kinney;Energy Conservation inProcess Industries

Nave calculation, value 125 psia steam reduction =

1000 x (1031 Btu/ lb ( Hv) 0.7(eff))x $7/MMBtu (Fuel) =$10.31 per klb

Actual site value 125 psia steam reduction =$4.08 per klb

i l S


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Typical Energy Management SystemBenefits

1 3 % Overall site utility costsavings!


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Example

Utilities Example Biomass Power


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Utilities Example Biomass Power Boiler

Paper mill 160k PPH Fluidized-bed Boiler Fuels:

Sludge Wood waste Tires Fuel gas

Incentives: Maximize use of cheap fuels (Tires & Wood) Burn all the sludge to minimize land fill Maximize steam production

S lid F l C i i C l


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Solid Fuel Composition Control

Sludge Presses

M

Sludge Bin

M

SludgeRecoveryHopper

VSM

HCSilo 1

Bark Yard

VSM

HC

FC

FC

WS WS

RSP RSP

WS

SolidFuel Bin

FC

HC

RSP

HCRSP

SludgeTarget

BarkTarget

Tire DerivedFuel (TDF)

VSM

Solid

Fuel ToBoiler

TDFTarget

Silo 2

FC

B il C t l


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Boiler Control

Boiler

Lance Burners (16)

FC

Load Burners (4)

FC

TI A-F

TC

HS M HSMAsh Screws (2)

Primary AirBlower

Air Preheater

TI

To ID Fan

PC

RSP

Fuel Gas

SecondaryAir Blower

FC

FCOverfire

Air Ports(18)

CombustionControl

To AshHanding

NCAvg

To ID Fan Speed Control

Solid Fuel

FC

Solid Fuel

FC

B il P C t l I


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Boiler Process Control Issues

Varying water in sludge Long delay & lag times (20 60 minutes) to

change fuel composition Fuel composition time constants are a

function of fuel bin level

Solid fuel composition in fuel bin isunknown

Bed temperature constraints (max & min) Multiple operators controlling same unit Different operating philosophy used by each

shift



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Sludge Presses

M

Sludge Bin

M

SludgeRecoveryHopper

VSM

HCSilo 1

Bark Yard

VSM

HC

FC

FC

WS WS

RSP RSP

WS

SolidFuel Bin

FC

HC

RSP

HCRSP

SludgeTarget

BarkTarget

Tire DerivedFuel (TDF)

VSM

Solid

Fuel ToBoiler

MPC BlockTDFTarget

Silo 2

PredictedBTU

Content

Boiler Control


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Boiler Control

Boiler

Lance Burners (16)

FC

Load Burners (4)

FC

TI A-F

TC

HS M HSMAsh Screws (2)

Primary AirBlower

Air Preheater

TI

To ID Fan

PC

RSP

Fuel Gas

SecondaryAir Blower

FC

FCOverfire

Air Ports(18)

CombustionControl

To AshHanding

NC

MPCOutputs

Avg

To ID Fan Speed Control

Solid Fuel

FC

Solid Fuel

FC


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Power Boiler Sludge

0

1020

30

4050

60

1 2 / 2

0 / 0 0

1 / 9 / 0

1

1 / 2 9

/ 0 1

2 / 1 8

/ 0 1

3 / 1 0

/ 0 1

3 / 3 0

/ 0 1

4 / 1 9

/ 0 1

T P H

SLDG

Key

Current Average

New Average

Max Sustainable


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Power Boiler Bark Fuels

05

101520253035

4045

1 2 / 2

0 / 0 0 1 /

9 / 0 1

1 / 2 9

/ 0 1

2 / 1 8

/ 0 1

3 / 1 0

/ 0 1

3 / 3 0

/ 0 1

4 / 1 9

/ 0 1

T P H

BARK

Key

Current Average

New Average

Max Sustainable

Power Boiler APC Benefits


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Power Boiler APC Benefits

Difference inHourly Costs

Power Boiler & (Savings)

Natural Gas $2.22

Sludge Disposal ($23.04)

Sludge Ash Disposal $9.18

TDF $0.46

TDF Ash Disposal $0.00

Waste Wood $26.91

W Wood Ash Disposal $0.77

Total $16.50

Package BoilersDisplaced Natural Gas ($98.42)

Net Savings, $/Hr ($81.92)

Total Savings

$56k / mo

$672k / yr

Project Justified:

Replacement of requiredpneumatic instruments

DCS Hardware / Software

APC Tools Turnkey Engineering Services


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Issues in Evaluating Plant Energy Usage

Unit energy usage depends on production rate

Unit energy usage variance dependent on productionrate

Need to correct to standard unit conditions


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Unit Energy Usage

Throughput - % Max Capacity

0 10050

EnergyUsageBtu

SpecificEnergyUsageBtu /Bbl

Energy Usage - Example


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Energy Usage Example

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00Production

T/Hr

MMBTU/Hr

Unit Energy Usage


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gy g

Throughput - % Max Capacity

0 10050

SpecificEnergyUsageBtu /Bbl

x

x

x

xx

x

x

x

x

x

x

x

x

x

x

x

x

x

x

xx

x

x

x

x

xx

x

x

ConfidenceLimits

VarianceIncreases at

Lower Rates

Unit Energy Usage - Example


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gy g p

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00

Production

M M B T

U / T o n

Excuses for Doing Nothing


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g g

Not enough manpower - Too busy doing other things

Our plant is special analysis based on other sitesdoesnt apply

We run our plant well already, there wont be any bigsavings found

Ostrich - (If we find something obvious,

management will ask why we didnt find it before)

Summary


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y

Energy is the largest controllable cost in processoperation its efficient production and use are keys to

plant profitability

Automation and Advanced Automation are keys toeffective use and management of energy in the plant

Implementation of a program to save energy requires adisciplined approach to evaluation and analysis

Questions? Comments?


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Q

[email protected]

More material on subject:http://www.emersonprocess.com/solutions/services/aat

how to save energy through enhanced automation

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