Preheater Operation
In response to industry pressure for improved capitol costs and better performance, FLSmidth has developed the MCP™ Preheater to provide a truly novel design delivering the best of both annular shaft preheaters and individual chimney preheaters.
In the MCP™ Preheater, hot gases leaving the kiln are drawn around the full circumference at cassette level. Gas enters the cassette from all sides equally due to the unique MCP™ Preheater geometry. From here the gas is drawn up through the descending stone. The gas exits the stone bed and moves through a dedicated aspirator.
In the MCP™ Preheater, each ram defines a distinct cassette, or chimney, for solids and gas to interact. Unlike the FCP, the MCP™ Preheater’s cassettes are symmetrical and constructed from a refractory lined cylinder – rather than refractory walls & columns. Also the cassettes penetrate the flat roof offset from the back wall and adjacent cassettes. This creates a full circumference for hot kiln gasses to enter the cassette, ensuring uniform gas distribution.
The stone bin is separate from the preheating area, necessitating stone to flow through chutes to the preheating zone. These stone chutes serve as restrictions to help reduce stone bin false air. Upon a ram stroke, stone moves from stone bin periphery to a stone chute. From here the stone is directed to and discharged to the preheating zone. Stone is delivered to the cassette on the centerline to help with uniform stone distribution. Stone moves counter-current to hot kiln gasses effecting preheating and precalcining. When stone reaches the cassette bottom, it spills out at its angle of repose into adjacent ram stone piles, the back wall, and feed apron. This configuration establishes a free gas path to the full cassette circumference. Upon reaching the ram level, hot precalcined stone is pushed out the fully annular stone discharge opening and onto the feed apron. From here it is pushed into the kiln.