The End of It is the Beginning-Nagesh-India

8/9/2019 The End of It is the Beginning-Nagesh-India

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The End of it is the Beginning: End useEnergy Efficiency Improvements in Practice

J. Nagesh Kumar Director

National Productivity Council

Chennai, [email protected]


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Electrical energy losses: Power

plant to end-use


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Why focus on end use ?

Utilisation efficiency relatively less efficientthan generation and distributionMore scope for improvements in the enduse areaLess expensive as these can be achievedthrough low-cost or no-cost measures

Improvements achieved throughoperational modifications rather thanenhancing equipment efficiencies


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M anaging energy: The end use

analysis methodWhat is the purpose of the process step?Is there a better way of doing it?

How much energy is being used atpresent?How much energy should be used?

Where are the losses?What are the options to minimize thelosses?


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C ase Studies


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Case study 1: Reducing electrical energy consumptionin a Dyed Yarn Dryer: No spinning yarn this!

Dyed Yarn Drier

SuctionRadiator

Steam

6 Kg/cm 2

Roots Blower 1571 m 3

3000 mm WC22 Kw

Roots Blower 1620 m 3

2000 mm WC19 Kw

Suction

Steam 6 Kg/cm 2

Radiator


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D etails

The dyed yarn which is wet is to be dried.The yarn cheese are arranged in a fixtureand lowered into a closed vessel.A roots blower blows the air through asteam coiled heat exchanger and the hotair goes through the yarn cheese for

drying.The existing batch time for the process isfive hours


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Analysis

The first question was why five hours? Because it has been going on for the past

several years

How do we know that the yarn hasbecome fully dried? There are no direct methods for measuring

the dryness nor is there any indirect method.


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O utput of trialsTrial was performed on four batches to assess the drying

effectiveness with respect to time.The yarn was weighed at frequent intervals to find out

the moisture removed.The tests showed that the complete moisture removal

takes place two hours before the end of the batch (seeFig in next slide).This means that unnecessarily the blower is in operation

for additional two hours.By cutting down the drying time from five hours to two

hours, electrical energy saving of 82 kwh / batch wasaccrued.The economic benefits amounted to $10,000 per annum.The other benefits such as steam consumption reduction

and improved productivity will far outweigh financialbenefits resulting from electrical energy savings.


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Dyed yarn Drier (Moisture Removal vs Time)

1

1.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2:15 2:35 3:20 4:20 5:20 6:20 7:20

Time

C h e e s e

W e i g h

t ( k g s )

Cheese 1 Cheese 2 Cheese 3


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Case study 2: Steam savings leads to electricalenergy savings in boiler induced draft (ID) fan

A textile dye house had installed a 6TPH boiler fired byagro residue, namely coconut shell (Fig in next slide).A steam audit was performed and many steam

conservation measures such as condensate recovery,proper steam trapping, better drying techniques etc weredeployed.After the implementation of improvement measures it

was observed that the maximum steam requirement atany point of time was only 3 TPH.The boiler was running under part load condition leading

to very high amounts of excess air.


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R educed fuel and Fan power: Twinbenefits due to excess air reduction

Boiler

6 TPH10.75 Kg/cm2C oconut shell

fired

Hopper

C oconut shellcrusher

Economiser

D ustC ollector

Primary Air Fans

Secondary Air Fan

Induced D raftFan

D amper 14 %

9 %


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Trials and resultsThe damper of the I D fan was closed to an extent where the excessair was just optimum.The reduction in excess air resulted in fuel savings.But there was only a marginal reduction in fan power from 30 kW to26 kW.The fan was belt driven and was operating at 1181 R PM. The motor was operating at 1470 R PM.It was decided to reduce the fan R PM and keep the damper fullyopen.This was done by changing the motor pulley from 8 to 6 (fig in nextslide).

The damper was kept fully open.This resulted in a dramatic drop in motor power from 26 kW to 14kW because of the cubed relationship of speed versus power.The annual energy saving amounted to 96,000 kWh resulting ineconomic benefit to the tune of $10,000 per annum.


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Electrical Energy saving in Boiler ID fan byspeed reduction through pulley change

810

6 10

1470 RPM

1470 RPM

1181 RPM

882RPM

26 kW

14 kW


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Case study 3: Energy savings in pumps byreengineering the water treatment system

This is a case study about a chemical plant making organicperoxides.The plants requirement of D emineralised ( D M)water and raw water was met by a borewell pump.The borewell pump pumps the underground water to a raw water tank over the fire pump house about 10 meters height.The water from the raw water tank is forced through a pump to anaeration tank where supposedly iron content in water needs to beremoved.The water from the aeration tank is then pumped through a pressuresand filter for removal of suspended solids and stored in a filter

water tank.From the filter water tank a pump continuously pumps water to theplant and a part of it is taken to the D M plant for producing D M water (Fig in next slide).


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Fire pump house

Raw water tank

Pressure

sandfilter

Filter water tank

Aeration tank

BorewellPump11kW

DM plant

DMwater tank

Filter water to plantDM water to plant

Raw water pump10 m 3/hr, 50 m5.5 kW

Filter water pump10 m 3/hr, 50 m5.5 kW

DM water pump

7.5 m3/hr, 36.5 m

3.7 kW

WTP effluent pump10 m 3/hr, 50 m5.5 kW

Water supply and distribution


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Analysis, improvements and resultsA Why, why analysis was made to question the need for each stepin the treatment process.The treatment scheme was designed for intake from a nearby river which had iron content.But the analysis of the existing borewell water showed iron contentbelow detectable levels.Thus the aeration process itself became redundant.Also an analysis of suspended solids over a period of time showedlevels well within the tolerable limits, thus leading to the eliminationof pressure sand filter.In the modified scheme the water from raw water tank directly is fed

to the filter water pump thus eliminating the operation of two pumps.Moreover the filter water pump was fitted with a variable speed drivewith a pressure controller leading to further energy savings.Because of these modifications the treatment scheme becamesimpler leading to an savings of 10 kW.The annual energy savings is of the order of 80,000 kWh with an

economic benefit of $8000 per annum.


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Case study 4: Energy savings in EffluentTreatment Plant (ETP) aeration blower A chemical plant consisted of a number of batch processes and thisled to an effluent discharge which was varying in volume as well asload.The aeration tank of the effluent treatment plant had a roots blower (Fig in next slide) which was discharging air continuously at1000m3/hr drawing a power of 22kW.O

n an analysis of ETP it was observed that the maximum air required at any point of time was only 650 m3/hr.The blower speed was first reduced to deliver 650 m3/hr.This resulted in a savings of 7 kW.Further to meet the fluctuating loads, a D issolved O xygen sensor was installed with a feedback to a variable frequency drive

connected to the blower motor.The motor speed automatically gets adjusted to meet the desiredoxygen levels for aeration.The installation of a variable frequency drive enhanced the savingsby 4 kW. The annual energy savings was 90,000 kWh with anannual economic benefit of $9000.The investment for the DO sensor and the variable frequency driveis paid back within a month.


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Effluent treatment system


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Case study 5: Energy savings inFume extraction system

In a plant manufacturing abrasives and grinding wheels, dust extraction inthe operating environment is of prime importance.In one particular area, the resinoid plant, five machining operations aremade on the bonded abrasives leading to dust emissions.The plant has installed a common dust collector system with a 22 kW fan for extracting the dust.Since the fan and dust collectors are installed outside the plant, the fan iscontinuously operating even if no operations are there on the machines.Also it was observed that not more than two operations are made at anygiven time (Fig in next slide).The fan was drawing 16 kW of power In the modified system pneumatically actuated dampers were provided in

the individual ducts of each machine.These were interlocked with the machine motors. If a machine is switchedoff the dampers will automatically close.Also a variable speed drive was incorporated to the dust extraction fanmotor which will reduce the fan speed with respect to exhaust air volumehandled.The average power drawn now was only 7 kW.

The saving of 9 kW resulted in an annual energy savings of 75,000 kWhwith an economic benefit of $7500.


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Regulate with dampers in each equipment22 kW dust collector fan in Resinoid plant

C o n

i c a l

d g e r

D r y

d i s c

B l o w

b o o

t h

2 2 e d g e r

2 2 l a t h e

Existing:N o dampersSuction remainseven when M/cnot operating

Proposed:Provide dampersSuction only in M/csoperatingO perate fan withvariable speed drive

P neumaticallyactuated dampers

VariableS peed Drive


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C onclusionsFrom our experience of carrying out more than 200

energy audits in different sectors, we have unearthed asaving potential of 20 % on an average in any typicalindustry.

With simple housekeeping and no investment measuresalone, up to 10 % of energy can be saved.The case studies presented here illustrate the need to

dig deeper into the final use, driven equipmentperformance and finally into the motor if substantialbenefits are to accrue in an energy efficient program.The investments needed with such an approach will be

far less leading to financially attractive energy savingprojects

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The End of It is the Beginning-Nagesh-India