Under-grate pressure climbing above its operating band asks a clean diagnostic question: is the bed too deep, is clinker bridging or jammed, or is the kiln rushing material into the cooler faster than the grate can move it through? Each cause has a different fix. Bed depth needs grate-speed and kiln-speed coordination; bridging needs visual inspection at the kiln nose; a kiln rush needs upstream stabilisation. Treating high under-grate pressure as a single problem misses which of the three actually moved.
Why this matters in the clinker cooler
Under-grate pressure is the cooler's load-cell on the bed. A sustained rise stresses the air supply system — fans work harder, motor amps rise, ducts and seals see fatigue at design discontinuities — and the operator's response options narrow because adding more air becomes expensive in fan power before it becomes effective in cooling.
Left uncorrected, high under-grate pressure also accelerates grate plate wear: each cycle of the grate moves more material against more resistance, and plate clearance grows faster. The sequence — high pressure leading to faster wear leading to worse air distribution leading to higher pressure — is one of the most reliable ways to shorten a cooler campaign.