Coal Mills

Type - XRP 963

Make - C. E.

Capacity - 48 TPH(100MW)

Current - 50 amps

No. of Coal Mills - 8

Feeder Type - Gravimetric

Bunker Capacity - 800 T

Coal Mills and Coal Feeders

• Pulveriser consists of grinding chamber with a classifier mounted above it. The pulverising takes place in a rotating bowl in which centrifugal force is utilised to move the coal, delivered by the feeder, outward against the grinding ring.

• Gravimetric coal feeders is provided to supply coal to coal burners in boiler. Feed rate is controlled by combustion control.

LUBRICATION SYSTEM OF COAL MILL

• The Pulveriser design uses separate oil lubrication system for the main gear case drive and bearings and for each journal.

• It consists of motor driven oil pump, a duplex oil filter, a supply header and the necessary piping and valves to distribute the oil to the bearings.

• Two lube oil coolers are installed on both sides of the gear housing.

SEAL AIR SYSTEM

• Pulveriser uses seal air to surround bowl-hub to prevent hot air and coal dust from escaping to the atmosphere or contaminating the gear housing

• Feeder seal air system is used to prevent air and coal dust from escaping to the atmosphere

• 6 seal air fans (Two low capacity and one hi capacity each side)

COAL MILL PROTECTIONS

1.Emergency lockout operated2.PA header pressure lo-lo3.Seal air to PA header pressure low4.Lube oil pump tripping5.MDV (Mill Discharge Valve) closed6.Bowl DP high7.Coal air temp high

COAL MILL START PERMISSIVES

1.Pulveriser / feeder permit (Ignition Permit)2.Pulveriser temperature ok3.Feeder switch in remote4.PA permit 5.No pulveriser trip command6.Mill discharge valve open7.Cold air gate open8.Lube oil pressure ok9.Lube oil level adequate

COAL MILL ELECTRICAL SUPPLY

CM 5A/C/E/G - 6.6kV UNIT BUS 5ACM 5B/D/F/H - 6.6kV UNIT BUS 5BLOP 5A/B/C/D - EMERGENCY SWGR 5ALOP 5E/F/G/H - EMERGENCY SWGR 5B