Page 22 - Critical Control flipbook_Neat

COAL MILL EXPLOSION

Critical Controls

Hazardous Areas Management Damper, Fan and Mill System Trip

Minimize ignition source by having certified equipment with corresponding Early detection of change prevents the formation of an explosive

protection level in the classified hazardous zones. atmosphere by stopping fans and the coal mill, as well as tripping and isolating
the baghouse by slam shutting the dampers.

Hazardous Area
Risk Assessment
Inspections
• Area/zone
clarifi cation
drawing End-to-end trip
• Explosion testing
protection • Sensor/detector
documentation • Control system
(PLC)
• Actuator/
3m end-element

3m
3m 3m 3m o
3m
3m
3m 3m 3m C
3m

CO

O and CO analyser
2
Trip fans and damper system
Pulverized coal
silo
Fine coal spillage
Ensure good
housekeeping

DANGER

NO ENTRY
NO HOT AUTHORISED
WORKS AREA PERSONNEL ONLY

Zone 20

Explosion Vents and Fire Fighting

Zone 22
Prevent primary or secondary explosion; limit the extent of damage and further

propagation if fire starts.

Inertization Self-closing

Automatic initiation of the inertization sequence at the coal mill system upon

detection of trip limits in temperature and/or CO level.

Self-closing

Alarm and
Trips

N /CO tank
2 2

Inputs
o C Pulverized coal silo

Pulverized coal
silo
CO Bar

Control system

Manual isolation valves

Actuated valve Regularly practise
Fire hose reel Fire hydrant Fire pump emergency drills © 2022 Holcim