Results of Energy Audit
in Lao Vang Vieng Cement Co.

Oct. 6, 2006
The Energy Conservation Center, JapanTaichiro KAWASE

Data collection for Taking a Heat Balance ofCement Kilns

Major Data Collected
Itemunit

Kiln type

Factory 1

Factory 2

shaft

NSP

Dry raw material (dry RM)

t/d

370

1200

Water content in wet raw
material

wt% on wet
RM

140Clinker

t/d

230

780

Coal rate

t/d

44

122

Low heat value of coalkcal/kg

5600

5600

Exhaust gas temp at kiln orpreheater exit

degC

200

320

Vent gas fraction in cooler%-10O2 in exhaust gas

vol%510Heat Balance Table of Factory 1 (Shaft Kiln)
Heat Input

Heat Output

Heat of combustion of fuel1067.5Heat for clinkering

470.0

Sensible heat of fuel0

Sensible heat of clinker at cooler exit

16.3

Sensible heat of wet raw material0

Sensible heat of cooler exhaust vent0

Sensible heat of combustion air

0Heat for evaporating water in raw
material

141.5

Sensible heat of kiln or preheater
exhaust gas

107.1

Radiation heat on kiln surface

7.8

Radiation heat on preheater surface

0

Radiation heat on cooler surface0

Unaccountable heat losses

324.8

Output total

1067.5

Input total

1067.5

Base of temperature : ambient air temperature
Base of heat amount : kcal per kg of clinker (kcal/kg-cl)
Clinker cooler : internal cooler

Heat Balance Table of Factory 2 (NSP Kiln)
Heat Input

Heat Output

Heat of combustion of fuel873.8

Heat for clinkering

470.0

Sensible heat of fuel0

Sensible heat of clinker at cooler exit

19.2

Sensible heat of wet raw material0

Sensible heat of cooler exhaust vent0Sensible heat of combustion air0Heat for evaporating water in raw
material0

Sensible heat of kiln or preheater
exhaust gas

179.0

Sencible heat of cooler vent gas

5.0

Radiation heat on kiln surface

30.4

Radiation heat on preheater surface

8.0

Radiation heat on cooler surface

4.0

Unaccountable heat losses

158.2

Output total

873.8

Input total

873.8

Base of temperature : ambient air temperature
Base of heat amount : kcal per kg of clinker (kcal/kg-cl)
Clinker cooler : grate cooler

Estimation of Maximum Production Capacity

Kiln typeGas rate in Lao (m3N/kg-cl)
Design capacity (t-cl/d)
Actual capacity (t-cl/d)@ 2006.10.3
Estmated max capacity (t-cl/d)
Gas rate in Japan (m3N/kg-cl)

Factory 1
Shaft
1.86200230

Factory 2
NSP
1.74
700
780

259
1.65

1005
1.35

Note : This is a trial calculation where many data are assumed. The
result should be a reference before a detail study.

Recommendations to Lao Vang Vieng
CementEnergy Management System
AspectOrganization

Monitoring

Major Activity
Accountability

Employee education (awareness)

Organization

EE&C promotion committee
Appoint an energy manager

Monitoring

Data recording & sharing by allemployees

TargetingSpecific energy consumption (SEC)
Key efficiency parameters (O2%)

Technology
Operation &maintenance(O&M)

Technical review (energy audit)
House keeping

Product yield (avoid off-spec product)
Preventive maintenance (avoidunscheduled shutdown)Monitoring of SEC & Key Variables
SectionMonitored Item

Unit

Raw Mill

SEC = Electric Power / Raw
Material Charge(kWh/kg-raw mat’l)

Clinker
Burning

SEC = Fuel / Clinker production
O2% of Kiln Exhaust Gas(kcal/kg-cl)(%)

Cement MillSEC = Electric Power / Cement
Production(kWh/kg-cement)

Recording of SEC on a Graph
Grinding Ball Management
SEC should bemonitored daily, andwhen SEC arrives atcertain level, grinding
balls is compensated.

Raw mill SEC

Ball diameter shrinks astime passes due toerosive effect. This leads
to gradual increase ofraw mill SEC.

Addition of Grinding Balls(kWh/kg-mat’l)Filling level of grinding
balls is also important ingrinding efficiency.
Optimum level of fillingshould be maintained.

Oct.2

Oct.9

Oct.16

Oct.23

Oct.30

Monitor raw mill SEC daily and add grinding balls in right timing→ 10% energy saving expected

Nov.6

Air Leakage Measurement
possible air leakage

combustion airfuelcoolingairstackEP

O2

preheaterrawmill
O2

Air leakage may bringabout an increase ofboth fuelconsumption and fanpower consumption.

O2

kiln

coolerF

O2

Air leakage occurred in kiln andpre-heater increases fuelconsumption in order for heating
leaked cold air up to processtemperature.

However, air leakage in EPand raw mill does notnormally increase fuelconsumption, but it
increases required powerof fan motor.

Energy Saving Measures in Cement Factory
Raw material section

Clinker burning section

Finishing section

First step

1)Selection of raw materials2)Management of particle
fineness3)Management of grindingmedia1)Prevention of unscheduled
shutdown
2)Selection of fuel3)Prevention of leakage

1) Management ofparticle fineness2) Management ofgrinding media

Secondstep

1)Replacement of fan rotor2)Improvement oftemperature and pressure
control system
3)Improvement of mixing &homogenization system
4)Installation of closed circuit
mill (separator)

1)Use of industrial waste(waste tire, etc)
2)Heat recovery of pre-heater
exhaust gas and cooler
exhaust gas (drying of raw
material and generation ofelectricity)
3)Replacement of cooler dust
collection from multiclone toEP

1)Installation ofclosed circuit mill(separator)
2)Installation of feed
control system

Third step1)Conversion from wetprocess to dry process2)Replacement of ball or tube
mill by vertical roller mill
3)Pneumatic transfer of raw
material to mechanicaltransfer1)Conversion of fuel frompetroleum to coal2)Conversion of SP to NSP
3)Conversion of planetary
cooler to grate cooler

1)Use of industrial
waste (slag, pozzolan)