Report on Energy Audit of Lao Cement Co.
1. Purpose
The PROMEEC project was started for the purpose of promotion of energy conservation in the
ASEAN countries. In the Lao PDR, the first audit was made in the hydro power station locatednear the Nam Ngum Lake in 2001, and the second audit was made in 2004 on the same site forfollowing up the first audit.
The past two audits were conducted in the energy generating side. This time a cement factory
was selected as a place of audit in the energy consuming side. The audit has two purposes;
one is an on‑the‑job training of audit technology to engineers in Lao PDR. The other isan information exchange and dissemination of acquired technologies among the ASEAN countries.
After the energy audit, seminar/workshop was held to share an experience acquired in theaudit with the engineers of Lao PDR, ASEAN countries.
2. Schedule
Oct.2, 2006

Am: Briefing of audit procedure, Interview and discussion

Oct.3

Am: Lecture on energy saving in cement factory
Pm: Grouping and walk‑through inspection

Oct.4

Am: Measurement and data gathering
Pm: Data analysis and discussion

Oct.5

Am: Reporting to factory management

Oct.6

Am/Pm: Seminar/workshop

3. Participants
Lao PDR:
4 government officials including
Mr. Khamso Kouphokham（Focal point, MEM, electrical engineer）
Mr. Xayphone Bounsou
ASEAN(ACE):
Mr. Ivan Ismed (Industrial Project Officer, PROMEEC)
Ms. Evangeline L. Moises (Chief, Information & Event Division)
Malaysia(PTM):
Mr. Zul Azri Hamidon (energy audit engineer, electrical)
Ms. Norazean Mohd. Nnor (technical assistant, electrical)
Japan(ECCJ):
Mr. Hideyuki Tanaka (coordinator)
Mr. Kokichi Takeda (electric expert)
Mr. Taichiro Kawase (heat expert)
Lao Cement Co.:1

20 engineers including
Mr. Thongchan Sounaphon（No.1 plant, deputy director）
Mr. Vichith Souvannarath（No.2 plant, deputy director）
4. Outline of factory
Lao Cement Co. is a state‑owned and situated in the city of Vang Vieng, 180km north ofVientiane, Lao PDR. Two kilns are built approximately 500 meter apart from in the same compound,which are substantially two plants in one factory.
No.1 plant

No.2 plant

Dec, 1994

Jan, 2002

90,000210,000

kiln type

shaft

NSP

fuel

coal

coal

employee244

294

construction
production capacity(ton/year)

5. Cement production
There are three companies (5 plants) of cement manufacturing in Lao PDR, which are composedof one state‑owned, one private and one joint venture of state and private. Total production
capacity in the nation is 600,000 ton/year in which Lao Cement Co. occupies 50% share. On
the contrary, national cement demand is 1,300,000 ton/year. The gap of demand and supply
is filled by an import, mainly from Thailand and China. Consequently, a principal goal of
the company is to keep a service factor of two plants as high as possible for attaining maximum
production of cement. It is quite remarkable that two plants achieve an operation of morethan 300 days per annum.
Two plants were constructed by Chinese contractors. Interestingly, main equipment such as
precalciner and coal burner, grate cooler are supplied by Japan, USA and Europe. In the No.2
plant, three Chinese engineers are now staying to give a technical advice in the area of
operation technology. Unfortunately a guidance in energy saving area is not implemented.
6. Energy conservation activity
Energy conservation activity was started after one of factory management participated in
the 2004 PROMEEC seminar held in Vientiane (*1). As an energy management in terms of fuelSEC and electric SEC is carried out, it is still a early stage where energy conservationis only a concern of limited number of managerial personnel in the factory and is not sharedby most of employees. An organizational provision has not yet made, for example, energy
conservation committee has not been organized and no energy manager are not appointed. A
small group activity such as Kaizen is not carried out(*3). A biggest interest of factory
management is a production, as indicated by the daily trend graph of cement production postedon the bulletin board.
*1: Mr. Vichith Souvannarath, deputy manager of plant no.2, took part in the 2004 PROMEEC

2

seminar, when he raised a question and acquired information on the electric SEC in
the Japanese cement industry.
*2: SEC means Specific Energy Consumption, expressed as energy used per unit product(typically kWh/ton of cement).
*3: The so called Kaizen in Japan is called as KAISEN in Lao PDR. They said in the past
the JICA expert visited a factory and gave a guidance on Kaizen activity.
7. Outline of energy audit work
Taking into consideration that one of audit purpose is on‑the‑job training (OJT) ofparticipant engineers, and Malaysian engineers are joining the audit team, it is agreed
that responsibility of audit work is put on the local team composed of engineers of Laogovernment, Lao Cement co. and Malaysian energy conservation center (PTM). The audit work
was implemented according to the following steps;
Lecture on cement manufacturing process and its energy saving measures
Briefing on audit items, data gathering and measurement procedures
Organization of audit team (grouping and leader selection)
Data gathering and measurement work
Data analysis and preliminary reporting to factory management
In the first two steps, team members had a lecture on audit technology and a briefing with
distribution of necessary documents prepared by ECCJ experts as a starting material. Kiln
heat balance, prevention of air leakage and variable speed control of big rotatingmachineries are selected as an audit target.
After a discussion among Mr.Khamso of focal point, factory and Malaysian PTM, the audit
team were organized. Most works in data gathering and measurement were conducted bythemselves without an assistance of ECCJ experts. As for data analysis, after all, ECCJ
experts conducted, but later in the seminar/workshop, one representative of audit team madea presentation on the result of audit.
8. Results of energy audit
1) Kiln heat balance and estimation of maximum production capacity
A kiln heat balance was taken in order to calculate kiln gas loading flowing through units
and to estimate maximum production capacity of the existing kilns. Kiln heat balance isuseful for understanding what determines an energy consumption and where energy saving
opportunity is located. The heat balance calculation was made on the EXCEL program preparedby ECCJ experts as shown in attached documents (Attachment 2). Various data necessary forrunning the EXCEL program were collected by looking at the operation log and making ameasurement in the plants. Due to lack of available time, all data could not be gathered,for which assumed data were postulated. Therefore, the result is not guaranteed, but which
way to go may be told. If more accurate answer is desired, more actual data should be collected.

3

In some cases, a consultation with process contractor is recommended. For the reference,a detail description of the EXCEL program is attached separately (Attachment 1).
Estimation of maximum production capacity is made on the assumption that production capacity
is roughly proportional to gas loading flowing through units. The Japanese data was employed
as a target of gas loading data. Maximum production capacity was estimated to be 266 ton/din plant no.1 and 988 ton/d in plant no.2, while present production capacity is respectively
230 ton/d and 780 ton/d.
Principal Data Collected
Item

unit

Plant no.1

Plant no.2

shaft

NSP

t/d

370

1200

wt% on wet RM

140Clinker (t/d)

‑

230

780

Coal rate (t/d)

t/d

44

122

kcal/kg

5600

5600

degC

200

320

%

‑

10

vol%

5

6

Kiln typeDry raw material (dry RM)
Water content in wet raw material

Low heat value of coal
Exhaust gas temp at kiln or preheater exit
Vent gas fraction in cooler
O2 in exhaust gas

Heat Balance of Plant no.2
Heat Input
Heat of combustion of fuelSensible heat of fuelSensible heat of wet raw material
Sensible heat of combustion air

Heat Output
873.8
0
0
0

Heat for clinkering
Sensible heat of clinker at cooler exit
Sensible heat of cooler exhaust ventHeat for evaporating water in raw
material
Sensible heat of kiln or preheater
exhaust gas
Sencible heat of cooler vent gas
Radiation heat on kiln surface
Radiation heat on preheater surface
Radiation heat on cooler surface
Unaccountable heat losses
Input total
873.8
Output total
Base of temperature : ambient air temperature
Base of heat amount : kcal per kg of clinker (kcal/kg‑cl)
Clinker cooler : grate cooler

470.0
19.2
0
0
167.4
7.3
30.4
8.0
4.0
167.5
873.8

Estimated maximum production capacity
Plant no.1

Plant no.2

Kiln type

Shaft

NSP

Gas rate in Lao Cement Co.(m3N/kg‑cl)

1.91

1.71

4

Design capacity (t‑cl/d)

200

700

Actual capacity (t‑cl/d) @ 2006.10.3
Estimated max capacity (t‑cl/d)

230
266

780
988

Gas rate in Japan (m3N/kg‑cl)

1.65

1.35

note1 : This is a trial calculation where many data are assumed. The result should be a reference
before a detail study.
note2 : m3N is a cubic meter at the normal condition, ie, 0℃ and 1 atm.
2) Prevention of air leakage
Examples of leakage‑prone area are grate cooler, connecting or moving part of kiln
surrounding, suspension preheater, grinding mill and electro‑static precipitator. Wherever
it may occur, any leakage causes an increase of power consumption of gas fans. Leakage
occurring in cooler or kiln may increase fuel consumption. As a plant becomes old,
possibility of air leakage rises high. Early detection of air leakage is important. In orderto detect a leakage, the most reliable method is a measurement of oxygen content in thesuspicious area. In the audit, oxygen content could not be measured because of a failureof oxygen meter. Oxygen content is an important data not only in air leakage detection but
also as a crucial variable in heat balance calculation.
3) Variable speed control of big rotating machineries
Rotating machineries eat a large portion of electric power in cement manufacturing plant.
In many cases, unduly large‑sized machines are installed and consumes electric power
wastefully. Even if machines are properly designed, in case that plant load is light, fanenergy is spent in vain for making up for dissipated energy in valve throttling.
Whether fan energy consumption is relevant or not is understood by monitoring an openingof gas damper and/or by measuring an electric current (ampere) of fan motor.
Data collected per the above are shown in the following table;
Fan
no.
(*3)

service

Designampere(Ad)

DesignVoltage
(Vd)

G6
G14
G15
G16
G17
G23
K1
K2
B26
E13
F23

cement mill EP fan
grate cooler fan〃〃〃
primary air fancoal mill fan〃
raw mill fan
raw mill EP fan
IDF fan

214.8
102.6
70.6
85
86
56.8
102.5
201
53.4
214.8
62.7

380
380
380
380
380
380
380
380
380
380
6000

5

Design kW(nameplate)(*1)(1041)
55
37
45
45
21.6
(46.5)(87.8)(41.6)(1041)
630

Actualampere(Aa)

Elecsaving(kWsaving)

DamperOpening
(%)

188
73
54
48
60
24
56
113
29
180
51

62
31
18
32
26
0
75
145
39
0
0
∑428

38
73
61
60
56
100
50
78
42
100
100(*2)

*1 : ( ) means design kW is estimated by the following equation;
Design kW = head(Pa)x flow rate(m3/min)/60000/fan efficiency*2 : F23 is speed‑controlled by fluid coupler.
*3 : G23 is roots blower, and others are all centrifugal fans.
In general, when variable speed control is applied, energy saving amount is estimated bycomparing an actual operating point with a design operating point on the fan performance
curve. Unfortunately any performance curve except for F23 was not provided by the factoryside. Therefore an ampere method was employed as an estimation method. This method has anadvantageous simplicity at the expense of accuracy. Energy saving amount is given by thefollowing equation;
Elec saving = design kW x {1‑(actual ampere/design ampere)^3}/fan efficiency x motor efficiency,where efficiencies are assumed to be 0.7 for fan and 0.8 for motor.
If annual operating duration is 300 days,
annual saved electric power = 428 x 300 x 24 = 3,081,600 kWh
9. Recommendations to Lao Cement Co.
1) Maximization of cement production
As described in the previous section, the existing plants has been estimated to have apotential of 15% to 26% more cement production although there is a problem of estimation
accuracy. A trial run is strongly recommended with the aim of maximization of cement
production. It is noted that the trial run should be implemented by increasing production
step by step and identifying bottleneck points in every step. In addition, gas loading in
the kiln should be evaluated by taking a heat balance.
2) Feasibility study of variable speed control
As discussed in the previous section, several fans are operated at the conditions of damper
throttling, and hundred millions of kWh of electric power are dissipated. The mosteconomical way of reducing the power loss is an application of variable speed control,
especially inverter technology. If it is successfully applied, electric SEC may decrease
by approximately 13 kWh/t‑clinker (*4). A feasibility study should be started soon.
*4 : 428 kW x 24 h / 780 t‑clinker/d = 13.1 kWh/t‑clinker
3) Air leakage management
As mentioned before, air leakage may cause an increase of energy consumption. The mosteffective way of detecting air leakage is an oxygen measurement. Purchase of portable oxygen
meter is strongly recommended. Zirconia type oxygen sensor is recommended because ofreasonable price and long life with sufficient accuracy. The approximate equation is used
for calculating an amount of air leakage, as described in Attachment 3.

64) Management of grinding media
Grinding efficiency is heavily dependent on diameter and charged volume of grinding media.
Ball diameter shrinks as time passes due to erosive force, which results in a gradualdegradation of electric SEC in the raw mill. Electric SEC should be monitored daily, andwhen SEC arrives at a certain level, grinding balls are charged up to normal level. At thesame time, filling level of grinding balls is also important in maintaining an acceptableefficiency. The following graph is useful for the monitoring purpose.

5) Establishment of energy management system
An energy management system (EMS) is proven to be effective in the developed countries.
Major components of EMS are shown in the following table;
Components
Organization

Activity
Organization

Monitoring

Accountability
Monitoring
TargetingTechnology

Evaluation

Operation &maintenanceHouse keeping

ExamplesEnergy conservation promotion committee
Appointment of energy manager
Employee education(awareness)
Data recording & sharing by all members
Specific energy consumption (SEC)
Key efficiency indicators (ex. O2%)
Technical review
Energy audit
Product yield(avoid off‑spec product)
Preventive maintenance(avoid unscheduled
shutdown)

As a first step, the following activities should be started because it does not cost somuch.
‑ energy conservation promotion committee‑ appointment of energy manager‑ employee education (attendance to seminar/workshop)‑ data monitoring and reporting
In order to make successful, strong involvement and support of factory management areimportant.

7

10. Attachments
1) Calculation procedure of heat balance
2) Result of heat balance calculation for Plant no.1
3) Result of heat balance calculation for Plant no.2
4) Estimation of amount of air leakage

8

Attachment 1

Example of heat balance calculation* Computer data are written in red.

1Plant : Lao Cement Co. No.2 plant
Boundary of Heat Balance:

Collected data and assumptions:
Materials and products
Cement production(t/d) : 811
Clinker production(t/h): 811/24/1.04 = 32.5
Yield of clinker (fraction to raw material) : 0.62
Raw material (dry base) (t/h) : 32.5/0.62 = 52.4
Water content in raw material (% on wet RM) : 0%
Raw material temp (℃) : 30
Raw material specific heat (kcal/kg‑RM/K) : 0.192
Clinker temperature at cooler exit (℃) : 130
Clinker specific heat (kcal/kg‑cl/K) : 0.192
Coal burning in kiln and precalciner
Fuel kind : coal
Low heat value of coal(kcal/kg) : 5600
Coal temperature (℃) : 30
Coal specific heat (kcal/kg/K) : 0.300
Coal consumption in kiln burner (kg/h) :1820
Coal consumption in precalciner (kg/h) :3250
O2% in kiln burner combustion gas : 3
Combustion air temperature (℃) : 30
Suspension preheater
Exhaust gas temperature (℃) : 320
O2% in exhaust gas : 6

1

Exhaust gas specific heat (kcal/m3N/K) : 0.338
Clinker cooler
Clinker vent gas temperature at cooler exit (℃) : 200
Fraction of cooler vent gas (%) : 10
Radiation losses from hot surfaces
Area(m2)

Temp(℃)

Emissivity

Kiln

500

150

0.95

Preheater

400

80

0.95

Cooler

200

80

0.95

Miscellaneous data
Ambient temperature (℃) : 30
Ambient air specific heat (kcal/m3N/K) : 0.310

Calculation of components in heat balance table
Heat input:
heat of combustion of coal(kcal/kg‑cl)= total coal(kg/h)*low heat value of coal(kcal/kg)/clinker prod(kg‑cl/h)= (1820+3250)*5600/32500 = 873.8
sensible heat of coal (kcal/kg‑cl)= total coal (kg/h)*spec heat of coal(kcal/kg/K)*(coal temp‑amb temp)( ℃ )/clinker
prod(kg‑cl/h)= (1820+3250)*0.3*(30‑30)/32500 = 0
sensible heat of raw material(kcal/kg‑cl)= raw material(kg/h)*spec heat of raw material(kcal/kg/ ℃ )*(raw material temp‑ambtemp)( ℃)/clinker prod(kg‑cl/h)= 52400*0.192*(30‑30)/32500 = 0
air ratio at burner = 21/(21‑O2 at burner) = 21/(21‑3) = 1.17
theoret air,A0 (m3N/kg‑coal)= 0.241*LHV(MJ/kg)+0.56 = 0.241*(5600/1000*4.186)+0.56 = 6.21
theoret combust gas, G0 (m3N/kg‑coal)= 0.216*LHV(MJ/kg)+1.67 = 0.216*(5600/1000*4.186)+1.67 = 6.73
1ry combust gas(m3N/h)= 1ry coal(kg/h)*(G0+A0*(air ratio at burner‑1))= 1820*(6.73+6.19*(1.17‑1)) = 14163
2ry combust gas(m3N/h)= 2ry coal(kg/h)*(G0+A0*(air ratio at burner‑1))= 3250*(6.73+6.19*(1.17‑1)) = 25292
1ry combust air (m3N/h) = 1ry coal (kg/h)*A0 *air ratio at burner= 1820*6.19*1.17 = 13180
2ry combust air (m3N/h) = 2ry coal (kg/h)*A0 *air ratio at burner= 3250*6.19*1.17 = 23537
total combust gas(m3N/h)

2

= 1ry combust gas(m3N/h)+2ry combust gas(m3N/h) = 14163+25292 = 39455
total combust air (m3N/h)= 1ry combust air(m3N/h)+2ry combust air(m3N/h) = 13180 + 23537 = 36717
sensible heat of total combust air (kcal/kg‑cl)= total combust air(m3N/h)* spec heat of air(kcal/m3N/ ℃ )*(comb air temp‑ambtemp)( ℃)/clinker prod(kg‑cl/h)= 36717*0.310*(30‑30)/32500 = 0Heat output:
heat of clinkering(kcal/kg‑cl)= heat of calcine(kcal/kg‑cl)‑heat of sinter(kcal/kg‑cl)= 570‑100 = 470
sensible heat of leaving clinker(kcal/kg‑cl)= spec heat of clinker(kcal/kg‑cl/℃)*(clinker temp‑amb temp)(℃)= 0.192*(130‑30) = 19.2
CO2 from calcine(m3N/h)= Clinker prod(kg‑cl/h)*0.27(m3N/kg‑cl) = 32500*0.27 = 8773
air ratio at preheater exit = 21/(21‑O2% at preheater exit) = 21/(21‑6) = 1.40
total combust gas rate at preheater exit(m3N/h)= total coal(kg/h)*(G0+A0*(air ratio at preheater exit‑1))= (1820+3250)*(6.73+6.19*(1.40‑1)) = 46731
water vaporized(m3N/h)= dry raw material(kg/h)*water cont(%)/(100‑water cont(%))*22.4/18= 52400*0/(100‑0)*22.4/18 = 0
preheater exhaust gas(m3N/h)= total combust gas rate at preheater exit(m3N/h)+CO2 from calcine(m3N/h)+water
vaporized(m3N/h)= 46731+8773+0 = 55504
sensible heat of preheater exhaust gas(kcal/kg‑cl)= preheater exhaust gas(m3N/h)*spec heat(kcal/m3N/ ℃ )*(preheater exhaust temp‑ambtemp)/clinker prod(kg‑cl/h)= 55504*0.338*(320‑30)/32500 = 167.4
cooler vent gas(m3N/h)= (preh exhaust gas(m3N/h)‑1ry combust gas(m3N/h))*vent gas%/100= (55504‑14163)*10/100 = 4137
sensible heat of cooler vent gas(kcal/kg‑cl)=coolerventgas(m3N/h)*spec

heat

of

air(kcal/m3N/K)

*

(vent

gas

temp‑amb

temp)(℃)/clinker prod(kg‑cl/h)= 4137*0.338*(200‑30)/32500 = 7.3
heat coeff of convection, hc(kcal/m2/h/K)= 2.236*(surface temp‑amb temp)^0.25= 2.236*(150‑30)^0.25 = 7.40
heat coeff of radiation, hr(kcal/m2/h/K)= 4.876*emissivity*((surface temp+273)/100)^4‑((amb temp+273)/100)^4)/(surface temp‑amb
temp)= 4.876*0.95*(((150+273)/100)^4‑((30+273)/100)^4)/(150‑30) = 9.11

3

radiation loss on kiln surface(kcal/kg‑cl)=(hc+hr)(kcal/m2/h/K)*surfacearea(m2)*(surface

temp‑amb

temp)( ℃ )/clinker

prod(kg‑cl/h)= (7.40+9.11)*500*(150‑30)/32500 = 30.4
heat coeff of convection, hc(kcal/m2/h/K)= 2.236*(preheater surface temp‑amb temp)^0.25= 2.236*(80‑30)^0.25 = 5.94
heat coeff of radiation, hr(kcal/m2/h/K)= 4.876*emissivity*((preheater surface temp+273)/100)^4‑((amb temp+273)/100)^4)/(surface temp‑amb temp)= 4.876*0.95*(((80+273)/100)^4‑((30+273)/100)^4)/(80‑30) = 6.57
radiation loss on kiln surface(kcal/kg‑cl)= (hc+hr)(kcal/m2/h/℃)*surface area(m2)*(preheater surface temp‑amb temp)(℃)/clinker
prod(kg‑cl/h)= (5.94+6.57)*400*(80‑30)/32500 = 8.0
heat coeff of convection, hc(kcal/m2/h/K)= 2.236*(cooler surface temp‑amb temp)^0.25= 2.236*(8‑30)^0.25 = 5.94
heat coeff of radiation, hr(kcal/m2/h/K)= 4.876*emissivity*((cooler surface temp+273)/100)^4‑((amb temp+273)/100)^4)/(surface
temp‑amb temp)= 4.876*0.95*(((80+273)/100)^4‑((30+273)/100)^4)/(80‑30) = 6.57
radiation loss on cooler surface(kcal/kg‑cl)= (hc+hr)(kcal/m2/h/K*surface area(m2)*(surface temp‑amb temp)(℃)/clinker prod(kg‑cl/h)= (5.94+6.57)*200*(80‑30)/32500 = 4.0
Key parameters:
exhaust gas rate per kg‑cl = preheater exhaust gas(m3N/h)/clinker prod(kg‑cl/h)= 55504/32500 = 1.71
specific fuel consumption (kcal/kg‑cl)= total coal(kg/h)*LHV of coal(kcal/kg)/clinker prod(kg/h)= (1820+3250)*5600/32500 = 873.8

4

Attachment 2 Result of Heat Balance Calculation for Plant no.1
Page‑1 (input data)
Heat Balance Calculation (Lao Cement Plant no.1 shaft kiln/overall balance)

1. Precondition
1.1 Preheater (or kiln) charge
1) Charge rate(dry base)2) Water content of dry raw material
3) Water content of raw material
1.2 Clinker
1) Yield of clinker
2) Clinker output
3) Temperature
4) Heat for clinkering5) Specific heat6) Cement production
1.3 Coal to kiln
1) Kind
2) Low heat value3) Temperature4) Consumption4-1) Coal consumption in Factory 14-2) Coal used in raw mill dryer
Dryer efficiency
Amount of water vaporized =Clinker/clinker yield*water cont/(100-water cont)5) Specific weight6) Specific heat
1.4 Fuel gas to kiln
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat
1.5 Coal to calciner
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific weight6) Specific heat
1.6 Fuel gas to calciner
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat
1.7 Exhaust gas at preheater outlet
1) Temperature
2) O2 content3) Specific heat4) CO2 originated from clinkering reaction
1.8 Exhaust gas at clinker cooler outlet
1) Temperature
2) O2 content3) Specific heat
1.9 Radiation heat from kiln surface
1) Average temperature2) Surface area
3) Convection coefficient4) Radiation coefficient5) Emissivity
1.10 Radiation heat from preheater surface
1) Average temperature

Date
Factory
Kiln

2006/10/3
1
Shaft

units
t/h
wt% on dry charge
wt% on wet charge

data
15.5
2
14

Remarks
limestone+clay+silica+iron-ore
estimated
log datat/h℃
kcal/kg-cl

0.62
9.6
115
470

t/d

0.192
240

constant
cement production/24/1.04
measure or log data
heat of calcination (570 kcal/kg-cl) - heat ofsintering (100 kcal/kg-cl) = 470 kcal/kg-cl
constant
operation target

kcal/kg
℃

coal
5600
30

constant
log data

kg/h

%

1772
1833
61
50

kg/h
kcal/kg/K

317
1
0.25

log data

constant
constant

natural gas
kcal/m3N℃
m3N/hkcal/m3N/K

kcal/kg℃
kg/h
kcal/kg/K

constant
log
log
constant
coal
5600
30
1
0.3

constant
log data
log data
constant
constant

natural gas
kcal/m3N℃
m3N/hkcal/m3N/K℃%
kcal/m3N/K

constant
log
log
constant
200
5
0.338
0.27

℃
%

measure or log datameasure or log data
constant
constant (0.27 m3N/kg-cl)
measure or log
measure or log
constant

℃
m2

70
150
6.5
6.3
0.95

measure or log
constant
constant
constant
constant℃

70

measure or log

5Page‑2 (calculation)

Heat Balance Calculation (Lao Cement Plant no.1 shaft kiln/overall balance)
2. Heat balance table
No. Itemkcal/kg-cl
Input heat
I1
Heat of combustion of fuel1032.1=(kiln+precal)*LHV/rm charge/cl yield/1000
I2
Sencible heat of fuel0.0=(kiln+precal)/charge*fuel SG*fuel Cp*(fuel temp-amb temp)/1000
I3
Sensible heat of wet raw material
I4
Sensible heat of combustion air
Total
1032.1

O1
O2
O3
O4

O5

O6
O7
O8
O9

Output heat
Heat for clinkering
470.0
Sensible heat of clinker at cooler exit Qcl out
16.3=Cl Cp*(cl temp-preh exhaust)
Sensible heat of cooler exhaust vent
=G*Cp*(tin-tout)
Heat for evaporating water in raw material=kg-water/kg-cl*539kcal/kg-water
17.7
Water amount in raw material = w/(100-w)/clinker yield
0.03
Sensible heat of kiln or preheater exhaust gas
109.7=(comb gas+decomposed+water evap'ed)*Cp*(tin-tout)/clinker rate
m =21/(21-O2)
1.31
LHV(MJ/kg-fuel)23.44
A0 =0.241*LHV+0.56
6.2
G0 =0.216*LHV+1.67
6.7
Comb gas, G = (G0+(m-1)*A0)*fuel rate
15371
Decomposed CO2 = 0.270*cl-kg
2596
Water vaporized = dry material*1000*w/(100-w)*22.4/18
394
Exhaust gas rate (m3N/kg-cl)
1.91
Radiation heat on kiln surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Radiation heat of preheater surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Radiation heat on cooler surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Unaccountable heat losses
Total

%

Remarks

100.0
0.0

100.0

45.5
1.6

1.7
10.6

gas l oadi ng( m3N/kg-cl )

7.8

0.8

0.0

0.0

0.0

0.0

410.5
1032.1

39.8
100.0

6

f uel SEC
( kcal /kg-cl )Attachment 3 Result of Heat Balance Calculation for Plant no.2
Page‑1 (input data)
Heat Balance Calculation (Lao cement co. Plant no.2 / overal balance)

1. Precondition
1.1 Preheater (or kiln) charge
1) Charge rate(dry base)2) Water content , w3) Raw material specific heat4) Raw material temperature
1.2 Clinker
1) Yield of clinker
2) Clinker output
3) Temperature
4) Heat for clinkering5) Specific heat6) Cement production
1.3 Coal to kiln (1ry burner)
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat6) O2%
7) Combustion air temperature
1.4 Fuel gas to kiln
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat
1.5 Coal to calciner
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat
1.6 Fuel gas to calciner
1) Kind
2) Low heat value3) Temperature4) Consumption5) Specific heat
1.7 Exhaust gas at preheater outlet
1) Temperature
2) O2 content3) Specific heat4) CO2 originated from clinkering reaction
1.8 Exhaust gas at clinker cooler outlet
1) Temperature at front2) Temperature at end
3) O2 content of precal combust gas4) Specific heat
1.9 Radiation heat from kiln surface
1) Average temperature2) Surface area
3) Convection coefficient4) Radiation coefficient5) Emissivity
1.10 Radiation heat from preheater surface
1) Average temperature2) Surface area
3) Convection coefficient4) Radiation coefficient5) Emissivity

Date
Factory
Kiln

2006/10/3
2
NSP

units
t/h
wt% on wet charge
kcal/kgK
℃

data
52.4
0
0.192
60

Remarks(limestone+clay+silica+iron-ore)estimated
constant
estimatedt/h℃
kcal/kg-cl

0.62
32.5
130
470

kcal/kgK
t/d

0.192
811

constant
cement production/24/1.04
estimatedheat of calcination (570 kcal/kg-cl) - heat ofsintering (100 kcal/kg-cl) = 470 kcal/kg-cl
constant
production target

Coal
5600
30
1820
0.3
3
30

kcal/kg℃
kg/h
kcal/kgK℃

actual of LCC
log data
log data
constant
estimatednatural gas
constant
log
log
constant

kcal/m3N
℃
m3N/h
Coal
5600
30
3250
0.3

kcal/kg℃
kg/h
kcal/kgK

actual of LCC
log data
log data
constant

natural gas
kcal/m3N℃
m3N/hkcal/m3NK

constant
log
log
constant℃%
kcal/m3NK

320
6
0.338
0.27

log data
log data
constant
constant (0.27 m3N/kg-cl)

℃
℃
%

863
200
21
0.338

measure or log
measure or log
constant

℃
m2

150
500
7.40
9.10
0.95

measure or log
constant
constant
constant
constant

℃
m2

80
400
5.95
6.58
0.95

measure or log
constant
constant
constant
constant

7

Page‑2 (calculation)
Heat Balance Calculation (Lao cement co. Plant no.2 / overal balance)
2. Heat balance table
No. Itemkcal/kg-cl
Input heat
I1
Heat of combustion of fuel873.8=(kiln+precal)*LHV/rm charge/cl yield/1000
I2
Sencible heat of coal
0.0=(kiln+precal)/charge*fuel SG*fuel Cp*(fuel temp-amb temp)/1000
I3
Sensible heat of wet raw material
9.3
I4
Sensible heat of combustion air
0.0
Total
883.1

O1
O2
O3
O4

O5

%

Remarks

98.9
0.0

f uel SEC
( kcal /kg-cl )98.9

Output heat
Heat for clinkering
470.0
Sensible heat of clinker at cooler exit Qcl out
19.2=Cl Cp*(cl temp-preh exhaust)
Sensible heat of cooler exhaust vent
=G*Cp*(tin-tout)
Heat for evaporating water in raw material=kg-water/kg-cl*539kcal/kg-water
0.0
0.00
Water amount in raw material = w/(100-w)/clinker yield
Sensible heat of preheater exhaust gas
167.4=(comb gas+decomposed+water evap'ed)*Cp*(tin-tout)/clinker rate
1.40
m =21/(21-O2) at preheater exhaust
LHV(MJ/kg-fuel)
23.44
6.21
A0 =0.241*LHV+0.56
G0 =0.216*LHV+1.67
6.73
Combustion gas, G = (G0+(m-1)*A0)*fuel rate
46731
Decomposed CO2 = 0.270*cl-kg
8773
0.0
water vaporized = dry material*1000*w/(100-w)*22.4/1
1.71
Exhaust gas rate (Nm3/kg-cl)

53.2
2.2

0.0
19.0

gas l oadi ng( m3N/kg-cl )Q5-1 Sensible heat of exhaust venting gas from clinker cooler
Fraction of cooler vent gas (%)
m =21/(21-O2) at kiln burner(Preheater exhuast - kiln burner G0)*vent gas fraction

7.3
10
1.17
4137

0.8

O6

29.6

3.4

7.5

0.8

3.8

0.4

178.3
883.1

20.2
100.0

O7
O8
O9

Radiation heat on kiln surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Radiation heat of preheater surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Radiation heat on cooler surface=(hc+ε*hr)*A*delT/(cl kg*1000)
Unaccountable heat losses
Total

constant

total exhaust gas(m3/min)2009

1ry air(m3/min)
2ry air (m3/min)

244
815

estimated

8

Attachment 4

Estimation of amount of air leakage

Legend:C: coal firing rate (kg/d)

LHV : low heating value of coal (MJ/kg‑coal)O2 at gas

: oxygen content in the gas (vol%)O2 at burner : oxygen content in the combustion gas at burner (vol%),
typical value is 3% to 5%.
A0 : theoretical air rate (m3N/kg‑coal)
G0 : theoretical gas rate (m3N/kg‑coal)m: air ratio (‑)

A at gas : actual air rate in the gas (m3N/kg‑coal)
A at burner : actual air rate at burner (m3N/kg‑coal)
G at gas : actual gas rate in the gas (m3N/kg‑coal)
G at burner : actual gas rate at burner (m3N/kg‑coal)⊿air : air leakage (m3N/h)
Calculation:
m at gas = 21/(21‑O2 at gas)m at burner = 21/(21‑O2 at burner)
A0 = 0.241*LHV+0.56
G0 = 0.216*LHV+1.67
A at gas = A0 x m at gas x c / 24 (m3N/h)
A at burner = A0 x m at burner x c/24 (m3/h)
G at gas = G0 + (m at gas ‑ 1) x A0 x c/24 (m3N/h)
G at burner = G0 + (m at gas ‑ 1) x A0 x c/24 (m3N/h)⊿air = A at gas ‐ A at burner (m3N/h)9