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Experimental Investigation on Energy Efficiency of Electrical Utilities in

Process Industries through Standard Energy Conservation Practices

Vyas Pareshkumar A,

Bhale Purnanad V.

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INTRODUCTION

• Surat textile cluster - @ 400 industries• Annual electricity consumption is 726 GWh,Gas consumption is 315

million SCM & Coal consumption is 2.3 million tones i.e. 1.2 million TOE (tons of oil equivalents) of energy use.

• Overall energy saving potential is 1.5 lakh TOE• Electrical and Thermal energy cost is 12 to 15 % of manufacturing

Cost. • Small And Medium Enterprise (SME’s) sector is characterised by

the use of outdated technologies.• As per BEE’s Study for SME Overall energy saving potential is @

72432 TOE i.e. 27.4 % of total energy consumption in SME’s• As an individual the SME’s may not have significant effect on

environment and resource use, but together they exert a substantial effect.

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Instruments used:• Electrical Portable Load Manager ALM 10• Hand held Ultrasonic flow meter

Focus area:• Air compressor system• Centrifugal pumping system

Energy Audit Activity:• Pre audit meeting• Familiarisation with manufacturing process and energy consuming

machineries• Review of manuals,maintenace records• Verification of calibration status of instruments, installation of

measuring instruments or other facilities

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PROCESS DIAGRAM

Grey Cloth

Jet M/c

Rotary M/c

Loop M/c

Washing Hydro

Stenter

Zero -Zero

Folding

Packing

(Printing Process)

(Drying & Color setting)

(Dyeing)

(Heat setting)

(Raw Material)

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WATER DISTRIBUTION SYSTEM

Overhead tank

Stenter M/c Printing M/c

Drums ,zero-zero M/c

Jet M/c Rotary M/c

Colour kitchen Office usePadding M/c

Supply pump

Bore well

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AIR DISTRIBUTION SYSTEM

Compressor 1 Compressor 2 Compressor 3

Stenter M/c Printing M/c Padding M/c

Rotary & Loop M/c Jet M/c Drum M/c

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ENERGY AUDIT ACTIVITY

Air compressor & Centrifugal pumping system :

Following data are collected with measuring instruments and calculations were made for Efficiency and Percentage air leakage.

• Input voltage,current,power factor – Measured with portable load analyser

• Running hours – Installed Running hour meter• Tank volume - measured and compared with available data• Discharge air pressure – Measured with calibrated pressure gauge• Actual tank filling time – Measured with calibrated stop watch• Actual head – measured with calibrated pressure gauge• Actual discharge – measured with Ultrasonic flow meter

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SNAPS

Modification of air distribution network & Installation of PID controller

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Installation of Auto moisture drain & Setting of new discharge set points

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T on Average on time (T) min

= 38

T off Average Off Time (t) min

= 28

% Air leakage =T/(T+ t) × 100

57.58

Annual cost of power for comp. no 3 (Rs)

= Unit rate× Annual power cons.

= 5.50 ×(674.3 × 26 × 12) = 1157098

Annual power loss due to leakages (Rs)

= Annual power cost × % Air leakage

= 666257

Power can be saved by plugging leakage in %

= 75%

Annual saving by leakage prevention(Rs)

Power saved by plugging 75 % leakage

= 499693

Investment required in plugging leakages (Rs)

= 50000

Payback in months = (Investment × 12) / savings = 1.2

AIR LEAKAGE TEST

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VOLUMETRIC EFFICIENCY MEASUREMENT

COMPRESSOR NO. = 1 2 3

Hp = 40 30 40

Motor RPM = 1440 1440 1440

Voltage = 410 412 414

Current = 43 35 45

Power Factor = 0.95 0.95 0.95

Power consumption per hour = [√3 x V x I x COSΦ]

= 29.01 23.73 30.65

Average working hrs = 24 12 22

Compressor RPM = 1440 1440 1440

Compressor Capacity (m3/min)

= 4.4 2.94 5.4

Tank Volume (m3) = 1.076 1.076 1.076

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Air pressure (Kg/cm2) = 6 7 4

Total air volume (m3) = (Tank Volume × Air Pressure)

= 6.456 7.532 4.304

Actual Tank filling time (Sec) = 105 162 52

Actual air generation (m3/min) = (Total Air Volume ÷ Actual Tank Filling Time) × 60

= 3.69 2.79 4.97

Required tank filling time (sec) = (Total Air Volume ÷ Compressor Capacity) × 60

= 88.04 153.71 47.82

% Efficiency = (Actual air generation ÷ Compressor Capacity) × 100

= 83.84 94.89 91.97

Existing specific power consumption (m3/min per kWh)

= Actual air generation ÷ power consumption per hour

= 0.127 0.118 0.162

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Proposed specific power consumption. (m3/min per kWh)

= compressor capacity ÷ Power consumption per hour

= 0.152 0.124 0.176

Power loss per day (kWh) = (100-eff/100) × power consumption per hr × avg. working hrs

= 112.48 14.56 54.18

Power loss per day ( Rs) = Power loss per day (kWh) × cost of power (Rs)

= 618.62 80.09 298.00

Annual power loss (Rs) = 193011 24989 92975

Investment (Rs) = 20000 0 0

Payback in months = (Investment (Rs) x 12 ) ÷ (Annual power loss (Rs))

= 1.24 0 0

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Set up of old and new transfer and supply pump

OLD PUMP 1

OLD PUMP 2

OLD PUMP 3NEW PUMP IN SUMP SUMP

SUMP

OLD PUMP 2

OLD PUMP 1

NEW PUMP

SNAPS :

CENTRIFUGAL PUMPING SYSTEM

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• Pump No. = 1 2 3• Rated motor efficiency = 0.8 0.8 0.8• Hp = 10 10 10• RPM = 2800 2800 2800• Measured voltage = 409 408 407• Measured current = 14 10.3 10.2• Existing pump running hours = 2 14 24• Calculated input kW / hr [√3 x V x I x cosΦ] = 9.8 7.2 7.1• Pump input kW / hr = calculated input kW / hr × rated motor eff.

= 7.85 5.76 5.69• Actual head (m) = 24 24 24• Measured flow (m3/hr) = 48 38 25• PROPOSED FLOW(m3)= 115• AFTER UNIT / HR = 11• AFTER WORKING HR = 11

Transfer pump

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Present water discharge per day = measured flow (m3/hr) × existing pump running hrs

= 96 532 600

Existing pump efficiency (%) = 0.4 0.431 0.286

Hydraulic power = Q (m3/s) × Total head, hd - hs (m) × Density (kg/m3) × g (m2/s) ÷ 1000

Electrical input power = Pump shaft power ÷ Motor efficiency

Pump shaft power = Hydraulic power ÷ Pump efficiency

Proposed minimum pump efficiency (%)

= 0.7

Existing overall efficiency (%) = existing pump efficiency × rated motor efficiency

= 0.32 0.34 0.23

Proposed overall efficiency (%) = Proposed minimum pump efficiency × Rated motor efficiency

= 0.56

Existing specific power consumption (m3/kW)

= (measured flow m3) ÷ calculated input kW / hr

= 4.89 5.27 3.51

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Existing unit consumption per day

= calculated input kW / hr × existing pump running hrs

= 19.64 100.88 170.84

Total unit consumption = 19.60 +100.94 +171.36 = 291.36

Afterunit consumption/day (single pump)

= after unit kW/hr × after pump running hrs

= 121

Saving in unit/day = 291.36 – 121 = 170.36

Saving achieved per day (Rs)

= Saving in unit/day × Price per unit (Rs)

= 170.36 X 5.5 = 936.96

Annual Saving (Rs) = 936.96 × 26 ×12 = 292332.70

Investment required (Rs) = 35000

Payback in months = (Investment required (Rs) × 12 ) ÷ Saving per year

= 1.44

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RESULTS AND DISCUSSION

Air compressor system :• Three nos. Air compressors• PID controller is installed and different air pressure setting is set.• Air distribution network rearranged.• Automatic moisture drain valve installed• Air leakages arrested.

Centrifugal Pumping system :• Instead of Three nos 10 hp ; 24 meter head; Different discharge

capacity Transfer pump, One Single Energy efficient 10 hp;20 meter head;100 m3/hr capacity pump installed.

• Instead of Two nos 10 hp ; 22 meter head; Different discharge capacity Supply pump, One Single Energy efficient 3 hp;6 meter head;100 m3/hr capacity pump installed.

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Description hp m3/min % volumetric efficiency

Specific power consumption (kwh/m3)

Annual power loss ( Rs)

Investment required (Rs)

Pay back period (months)

Air compressor # 1

40 4.4 83.84 7.62 193011 20000 1.24

Air compressor # 2

30 2.94 94.89 7.08 24989 0 0

Air compressor # 3

40 5.4 91.97 9.72 92975 0 0

Energy-Saving Measures

Investment (Rs) Annual Savings (Rs)

Simple Payback Period (Months)

Expected Lifetime (operating hours)

Improve Efficiency of Compressor #. 1

20000 193011 1.24 14400

Stop Air Leakages in Department.

50000 499693 1.20 Req. Regular Maintaince

Total 70000 692704

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CENTRIFUGAL PUMPING SYSTEM

Description

hp Head (meter)

Flow (m3/hr)

Current (amp)

Input kW/hr

% Efficiency % overall Efficiency

Transfer pump # 1

10 24 48 14 7.85 40.0 32

Transfer pump # 2

10 24 38 10.3 5.76 43.1 34

Transfer pump # 3

10 24 25 10.2 5.69 28.6 23

Energy saving measure

Investment (Rs)

Annual savings (Rs)

Simple Payback

Expected lifetime (operating hrs)

Replace Transfer pump 1,2 and 3by single Energy efficient pump

35000 292332 1.44 14400

Total 35000 292332

Transfer pump :

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Supply pump

Description

hp Head (meter)

Flow (m3/hr)

Current (amp)

Input kW/hr

% Efficiency

% overall Efficiency

Supply pump # 1

10 22 42 10.5 5.26 50 40

Supply pump # 2

10 22 45 10.2 5.13 55 44

Energy saving measure

Investment (Rs)

Annual savings (Rs)

Simple Payback

Expected lifetime (operating hrs)

Replace supply pump 1 and 2 by single Energy efficient pump

30000 230000 1.57 14400

Total 30000 230000

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SUMMARY OF IMPLEMENTED RESULTS

Steps taken Saving In Units (kWh / Year

Actual investment (Rs)

Energy cost saving per year (Rs)

Pay back (month)

Single Energy efficient pump of 3 HP ; 6 meter head ; 100 m3/hr discharge capacity is installed (supply pump)

41817 30000 230000 1.57

Single mono sub pump of 10 hp ;20 meter head ;100 m3/hr discharge capacity is installed (transfer pump)

53152 35000 292332 1.44

PID controller is installed; Different air pressure setting is set for three different compressors. Air line network rearranged (common header ) Automatic moisture drain valve also installed

134400 180000 821338 2.67

Total 229369 245000 1343670

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REFERENCES

[1] http://www.business-standard.com/india/news/energy-effeciency-plan-for-smes-ingujarat/399670/

[2] Guide book for National Certification Examination for Energy Managers and Auditors. “General aspects of energy management and audit. www.beeindia.nic.in

[3] Kapur, Shilpi , Plannet Earth , Fiscal reforms, SMEs'hope , Date: 10 October 2011, http://www.teriin.org/index.php?option=com_featurearticle&task

[4] Ali,Hasanbeigi ,China Energy Group,Energy Analysis Department, Environmental Energy Technologies Division “energy- efficiency improvement opportunities for the textile industry”,E.O. Lawrence Berkeley National Laboratory,Washington, DC Resource Dynamics Corporation

[5] Facts air distribution,”druckluft effizient’,07 compressed air facts,www.druckluft-effizient.de.

[6] Kaya D, Phelan P, Chau D, Sarac HI. Energy conservation in compressed-air systems. International Journal of Energy Research 2002;26:837–49.

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[7] Galitsky C, Worrell E. Energy efficiency improvement and cost saving opportunities for the vehicle assembly industry. Lawrence Berkeley National Laboratory 2008 [LBNL-50939-Revision].

[8] U.S. DOE. Minimize compressed air leaks; 2010, Available online at: http://www.energystar.gov/ia/business/industry/compressed_air3.pdf [Accessed:24.09.11].

[9] Saidur R, Rahim NA, Hasanuzzaman M. A review on compressed-air energy use and energy savings. Renewable and Sustainable Energy Reviews 2010;14:1135–53

[10] PS (Plant Support). Compressed air ultrasonic leak detection guide; 2010,Available online at: http://www.plantsupport.com/download/UCAGuide.pdf[Accessed 24.09.11].

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It is never too late to practice energy modesty and efficiency otherwise …

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