Alumina Ceramic By Bmw Steels Ltd.

Alumina Ceramic










Wear Resistance by Alumina Ceramic in
Coal Mill Pulverizer and Pipe Line Erosion is caused by pressurized
air which carries entrained abrasive solid coal particles, impinging
on a surface. When the angle of impingement is less than 30 deg, the
wear produced is closely analogous to abrasion. When the angle of
impingement is more than 30 deg to the surface, particle from mill
internals is dislodged by impact erosion.
Alumina Ceramics are used in a very
broad range of wear resisting surfaces and for the repair of wear
resisting surfaces of coal mills. Indeed, these alumina liners do
provide the best solution for giving the desired performance.

A study was conducted for erosion
pattern of coal mill internals due to coal flow in vertical spindle
pulverizers in PC Boilers. The coal and air mixture makes a number of
turns before it reaches the Multiple Port Outlet. The changes in
direction of flow cause the majority of coal particles to accumulate
in the "Red marke" portion of the pulverizer as under:










Accumulated coal particle has abrasive
wear mechanism, basically same as machining, grinding, polishing or
lapping that we use for shaping materials. Two body abrasive wear
(coal dust and mill internals) occurs when one surface (coal- harder
than the metal mill internals) cuts material away from the mill body
and internal, this mechanism very often changes to three body
abrasion as the wear debris then acts as an abrasive with coal dust
on mill internal surfaces. This abrasion can be reduced to great
extent by fixing Alumina Ceramic Liners on high coal accumulation
areas.

Based on the above study BMW has
developed Alumina Ceramic Lined Mill internals, Multiple Port Out
Let, Mill Discharge Valves, Coal flow Orifices, Coal Pipe and Bends.
These are elaborated under the specific sections.