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Talk delivered at MITCON Course April 1,2005

Energy Audit ing

Rangan Banerjee

Energy Systems EngineeringIIT Bombay

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Need for Energy Management

Renewables – In general , not yet cost-effective

Capital Scarcity- Payment Crisis of Subsidised Energy Sectors

Gestation Period for New Power plants Least Cost Planning

Energy Management – Transition fuel

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Importance of Energy Conservation

Energy Conservation Act 2001 – Setting upof the Bureau of Energy Efficiency (March2002)

Standards and Labelling Energy Conservation Fund

Designated Consumers- Energy audits by accredited auditors

Certified energy managers

Norms and standards of energy consumption

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Energy Cost in Chemical Industry

12% of manufacturing cost. Real growth in energy bill higher than real

growth in raw material, sales.

Higher energy prices –competitivedisadvantage (compared to US, UK, Brazil,France)

Electricity accounts for 44% of fuel mix. Electricity price increasing at higher rates

than other fuels (10% per year real growth).

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EC Company Policy

Many companies declared EC policy , inresponse to a request by EnergyManagement Centre for example

Reliance : Our mission is to be the lowest specific energy consumer

in the industry we operate in

To maximise the use of renewable fuels and low energy level fuels in our operations Mukesh Ambani

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Energy Conservation Opportunities

Design Stage – Efficient process design

Efficient equipmentdesign/ selection

Efficient Utility Systemdesign

Operating Decisions-

Energy Auditing Operating Strategies

Retrofit equipment

Replaceequipment/processes

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What is an energy audit?

Audit – financial connotation –examination with an intent to verify

Energy audit – coined in the 70’safter the oil shocks

An energy audit is a study of a plant

or facility to determine how and where energy is used and identify methods for energy savings

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DEFINE AUDIT OBJECTIVES

QUESTIONNAIRE

REVIEW PAST RECORDS

WALK THROUGH / PLANT FAMILIARISATION

DATA REQUIREMENTS

MEASUREMENTS / TESTS

COMPUTE MASS / ENERGYBALANCES

ENUMERATE ENERGYCONSERVATION OPPORTUNITIES

EVALUATE ECOs

PRIORITISE RECOMMENDATIONS

DATAANALYSIS

INSTALLMEASURES

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P a r a m e t e r S u b - T y p e In s t r u m e n tsT e m p e r a t u r e C o n ta c t ty p e T h e r m o c o u p le s

e . g . (K t y p e C h r o m e l -A lu m e l )- 2 0 0 t o 1 3 0 0 º C

R e s i s ta n c e T e m p e ra t u r eD e t e c t o r s ( R T D s ) 0 t o 1 5 0 º CS u c t io n P y ro m e t e r

N o n - c o n t a c tt y p e

R a d ia t io n P y ro m e t e r sT w o c o lo u r o p t ic a l p y r o m e t e r s

F l o w F ix e d a r e a ( O r i f ic e , V e n tu r i )V a r ia b le a re a (R o t a m e t e r )P i to t s ta t ic tu b eH o t w ir e a n e m o m e te r

N o n - i n v a s i v e U lt r a - s o n i c f lo w m e t e r

D o p p le r m e te r sF lu e g a sa n a l y s i s

Z ir c o n iu m o x id e o x y g e ns e n s o r sP a r a m a g n e t ic a n a ly s is fo ro x y g e n

F u e l c e l ls f o r C OP o w e r 3 - P h a s e c la m p o n m u l t im e te r

( 3 w a t t m e t e r m e t h o d )R P M C o n t a c t

N o n - c o n t a c tT a c h o m e t e r

T o t a l d i s s o l v e ds o l i d s C o n d u c t iv i ty m e t e r sL i g h t i n g L u x m e te r

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Operating Length

Radiation Shield φ27 mm

Thermocouple junction

Water inlet

Aluminum Shield

φ 43 mm

Water outlet

Suction

Line

Gases

Suction Pyrometer

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Data Sources

Electrical line Diagram P & I Diagram

Steam Distribution Diagram Nameplate Ratings

Manufacturers Catalogs (Major eqpt) Logsheet data (Typical days)

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11 kV CPP1 11 kV CPP 2

11/6.6 kV Trf-1 11/6.6 kV Trf-2

6.6 kV CB 6.6 kV CB

BUS COUPLERMCC-1 MCC-26.6/0.44 kV Trf-3

HT Motor loadsHT Motor loads

LT Loads

Schematic of Electric Supply network

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Sankey Diagram

Mass and Energy Balances for aprocess

Relative magnitudes- quantification of energy flows

Design Balance /Operating Balance

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Block Diagram for a Cement Plant

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Sankey Diagram for a Cement Plant

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Energy Efficiency• Determine end-use profile of plant load

• Motors (80% of load), lighting, heating

• Breakup of motor load for a Chemical plant

Others

(15.9 %)Conveyors

(5.5 %)

Centrifuges

(1.3 %)

Agitators

(12.7 %)

Compressors

(1.3 %)

Fans

(11.9 %)

Pumps(51.3 %)

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Energy Conservation

Opportunities

Housekeeping/Monitoring

Additional Equipment

Equipment Replacement/Efficient Equip.

Operating Strategies

Process Integration/Networking Process Changes

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Typical Audit SummaryOPTION ANNUAL SAVINGS

ENERGY MONEY(Rs.)

VIABILITY

WASTE HEAT RECOVERY

(FLUE GASES)

3.4 MW

19.3 Mus

- 105,500Nm3

2.9 CR

I : 8.9 CR

SPP 3.1 YR

IRR 40 %

NPV 15.8 CR

TOP GAS HEAT

RECOVERY

2.7 MW

16.2 MUS

2.4 CR

I : 6 CR

SPP 2.5 YR

IRR 40 %

NPV 14.7 CR

AUTO

Y-Δ- Y

97,000 kWh 1.45 LAKHS

I : 1.26 LAKHS

SPP < 1 YR

SPEED CONTROL

F.D. FAN

1,704,000 kWh 26 LAKHS -

FRP BLADES – COLLING

TOWER

11,100 kWh 0.17 LAKHS

I : 0.53 LAKHS

SPP 3.2 YRS

COOLING WATER –

OPERATIONS

1,125,000 kWh 17 LAKHS -

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Practical Difficulties

Data Insufficiency Data Inconsistency

Incomplete Evaluation of Options

Changes in ExternalEnvironment

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Top Gas

360oC

940oC1100

o

C

FLUE GAS

AIR

40oC

NG

FLUE GAS

To Chimney

286oC80oC FEED GAS

570oC

630o

C50o

CFUELHBI

BRIQUETTING

M/C

SHAFT

FURNACE

140MW

SCR

UBBER

REFORMER

62 MW

RECUPERATOR

38 MW

IRON OXIDE +

PELLETS REFORMED

GAS

Schematic of HBI Plant

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AIRTILES

OIL

EXHAUST

AIR

BURNER AIR

OIL

RAPID COOLING

COOLING

EXHAUST

BLAST

Schematic of

Glost Kiln in

Tile Factory

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IT/hr

400 kg/hr 400 kg/hr

DG1

DG2

DG3

1000kVA

1000kVA

WASTE

HEAT

BOILER1

WASTE

HEAT

BOILER2

VARS

12oC

400TR

QR 7oC

1.8 T/hr

8ATA

BOILER 1 BOILER 2

1000kVA

Exhaust gases

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Total Load Curve of IIT

2 5 10 k VA

19 0 0 k VA

0

500

1000

1500

2000

2500

3000

1 2 3 4 5 6 7 8 9 10 1112 13 14 15 16 17 18 1920 21222324

Time h o u rs

Working da y

Non working da y Average pow er factor of the dayWork ing day-0.96

Non-w orking day-0.97

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MAXIMUM DEMAND

Variation of Maximum Demand

For year 2000-01

30802900 2840 2780

2960 28803120

2928

25002800

2640

3040

0

1000

2000

3000

4000

A p r ' 0

0

M a y ' 0 0

J u n ' 0 0

J u l ' 0

0

A u g ' 0

0

S e p ' 0 0

O c t ' 0

0

N o v ' 0 0

D e c ' 0 0

J u n ' 0 1

F e b '

0 1

M a r ' 0

1

Month

M a x i m u m D e m a n

d ( k V A )

Contract

demand

3000 kVA

75 % CD

2250 kVA

Penalty paid by

IIT

For year 2000-1

Rs.38400

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Power Factor Correction

P- Act ive Power (kW)

S - A p

p a r e n t P o w e r

( k V A )

Q- React ivePower

(kVAr)

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POWER FACTOR IMPROVEMENT

AUTOMATIC POWER FACTOR CORRECTION0.95 to 0.99

Reduction in MD- 107 kVA/month

Annual Saving -Rs.3.85 lakhs

Cost of the APFC unit – Rs. 2.5 lakhs

(with 150 kVAr capacitor units)Simple Payback Period - 8 months

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Departmental Connected Load by

End-use

Laboratory

31%

Air

Conditioning

32%

Pumping

Load7%

Lighting

16% Fan

4%

Computer

7%

Others

3%

Total 4300 kW

connected load

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ENERGY EFFICIENT LIGHTING

Group Control – Master Switch outsideclassrooms

Common Area Lighting – Photocells forgroup switching

Tubelights – Electronic Ballasts for high

duty cycle tubesEfficient tubelights (26 W)

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Duty Cycle of TubelightsNumber of Tubelights vs Hours of Operation

277

8785

759

577

414

1196

706

354

340

0 200 400 600 800 1000 1200 1400

H o u r s o f O p e r a t i o n

Number of Tubelights

4-

4

6

8

10

12

14

16

18

18+

l

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Harmonic Restraint Electronic

Ballasts

THD <5 %

Conventional

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FTL Options

Electronic Ballast – Consumption 2-3 Winstead of 12-15 W as replacements whenfailure ,Incremental Rs 700, Duty cycle (14

hours or more), Rs 200/yr saving Efficient slim tube –26 W (10 W saving),

Investment Rs 780 – Try out a few for high

duty cycle

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Duty Cycle of Fans

69

148

135

54111

543

287135

59

0 100 200 300 400 500 600

H o u r

s o f O p e r a t i o

n

Number of Fans

4-

468101214

161818+

Electronic Regulators for high

duty cycle on replacement

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METERINGDigital meters at 25 locations

(Depts/pumping stns/Main Building) withmeter reader (Rs. 1.5 lakhs for meters)

or Automatic metering and Energy balancing

through networking

at 25 locations (Rs. 10 lakhs app.)Billing to Departments

Norm Establishment (after initial data collection)

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References

Witte, Schmidt, Brown, Industrial EnergyManagement and Utilisation, HemispherePubl,Washington,1988

S.Khurana, R.Banerjee, U.N.Gaitonde, AppliedThermal Engineering,Vol22, p485-494,2002

E. Worrell,Potential for Improved IndustrialEnergy Use and Materials,Ultrecht,1994

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