LIMESTONE CRUSHING PLANT LOAD MANAGEMENT

Jaco Snyman

2012-08-15

CEMENT MANUFACTURING

ENERGY USAGE OF THE CEMENT MANUFACTURING

INDUSTRY Industry consume 30 – 70% of total energy Malaysia & Iran: 12 – 15% of industrial energy

used for cement manufacturing Energy source: 75% Fossil fuel, 25% Electrical

Ocean

ia

Others

Europe

Japan USA CIS

Africa

Other A

merica

India

Cembureau

Others

AsiaChina

0%10%20%30%40%50%60%

Glo

bal c

emen

t pr

oduc

tion

ELECTRICAL ENERGY USAGE OF CEMENT PLANTS

Typical 110 – 120 kWh per ton of cement produced

3%

35%

24%

38%

Crushers

Raw mills

Pyro-processing

Finnishing mills and packaging

ENERGY SAVINGS – PREVIOUS STUDIES

No comprehensive review on energy usage & savings up to 2012

Recent studies estimate: Grinding energy can be reduced with 10 – 20%

by increasing mill efficiency & schedules. Waste heat from pyro processing can be used

to increase efficiency with 2 - 10%.

ENERGY SAVINGS – CRUSHING PLANTS

Why? Global cement production of 3.5 Gtons (2011)

translates to estimated global crusher energy consumption of 12 282 GWh.

10% saving = 102 MW Daily energy efficiency Very limited studies on crushing plants

1.52.02.53.03.54.0

Year

Wor

d Pr

oduc

tion

[Gt]

CASE STUDY - OVERVIEW OF THE CRUSHING PLANT

Operate according to production requirements 2x 50kton Stock piles, one loaded and one

reclaimed

0200400600800

10001200140016001800

Time of day

Pow

er [k

W]

REDUCING ENERGY COST OF THE CRUSHING PLANT

1. Determine required stock-pile levels using: Present stock levels (raw meal, clinker &

cement) Sales forecast

2. Optimise crusher running schedule to: Avoid running during Eskom peak periods Maintain minimum required stock Accommodate optimised maintenance

schedules

3. Update proposed daily, weekly and monthly schedules on a daily basis

RESULTS - ENERGY0:

001:

002:

003:

004:

005:

006:

007:

008:

009:

0010

:00

11:0

012

:00

13:0

014

:00

15:0

016

:00

17:0

018

:00

19:0

020

:00

21:0

022

:00

23:0

0

0

200

400

600

800

1000

1200

Actual Proposed

Time of day

Ele

ctri

cal

Po

wer

dem

and

[kW

]

Proposed and actual baseline for April 2012

RESULTS - STOCK20

12-0

4-01

2012

-04-

0220

12-0

4-03

2012

-04-

0420

12-0

4-05

2012

-04-

0620

12-0

4-07

2012

-04-

0820

12-0

4-09

2012

-04-

1020

12-0

4-11

2012

-04-

1220

12-0

4-13

2012

-04-

1420

12-0

4-15

2012

-04-

1620

12-0

4-17

2012

-04-

1820

12-0

4-19

2012

-04-

2020

12-0

4-21

2012

-04-

2220

12-0

4-23

2012

-04-

2420

12-0

4-25

2012

-04-

2620

12-0

4-27

2012

-04-

2820

12-0

4-29

2012

-04-

30

0

10000

20000

30000

40000

50000

Actual Proposed

Date

Stoc

k pi

le le

vel [

kt]

CONCLUSION

Savings not realised due to: Unexpected equipment failure Unexpected sales & lack of confidence in

proposed schedules Negative attitude from personnel

Average peak time saving of 1.2 MW possible in this study

Global saving of 102MW possible, 50% in China

Address challenges to realise potential savings

QUESTIONS ?