Key Benefits

  • Innovative design
  • Improved stone transfer
  • Flexibility

New and improved MCP Preheater design to enhance operations

We understand the importance of producing the highest quality lime at your site. Not only does your reputation depend on it, so too do those who use the lime you produce. We also understand the need to maximise the efficient use of power and fuel during the calcination process.

Our new and improved MCP Preheater delivers both lower capital costs and enhanced performance.


It starts the calcination process by using hot process gases from the rotary kiln to preheat the feed material prior to it entering the kiln.


Its design allows for the hot gases to be drawn around the full circumference at the cassette level, entering the cassette equally on all sides before being drawn up through the descending stone. This uniform gas distribution adds to its efficiency as does its shelf geometry.


In our MCP Preheater, the short feed shelf is continuously cleaning, which prevents material from stagnating. The longer length shelf in other models means that the hydraulic ram is unable to move the bottom stone bed. This results in crushed stones and flints continually building up and requires the machine to be shut down for cleaning. Our patented shelf geometry prevents this from happening and removes the possibility of a dead zone area.


Our MCP stone bed height is fully adjustable while in use in order to adapt the unit easily to different stone feed size ranges. Additional features also prevent adverse segregation in the stone bed in order to optimise gas distribution and heat transfer.


We offer an advanced hydraulic package for preheaters, featuring complete isolation from external factors such as dust and water contamination. Designed with functionality in mind, the hydraulic unit on our MCP Preheater is located at ground level which improves maintenance access.

Enjoy more flexibility and efficiency when producing pebble lime

Innovative design

Simplicity is key when it comes to fully functioning design. We have looked at every component carefully to bring in a multitude of improvements, which provide greater flexibility and efficiency. One key part of our design is the fully circumferential gas path for each cassette which provides equal heat transfer and low pressure drop. With a smaller shelf-to-roof dimension required, we were able to design a flat, short shelf in our MCP Preheater, which improves geometry and efficiency.


The round design of the cassettes eliminates the corners that encourage the formation of deposits.  In practice, the MCP cassette is essentially self-cleaning and periodic shutdowns for deposit removal can be avoided.

Improved stone transfer

The short shelf has numerous advantages over the longer feed shelves found in conventional preheaters. A longer shelf creates problems for the ram to move the bottom stone bed, which leads to a build-up of debris and clutter, known as a dead stone area, which then needs to be cleaned. However, a shutdown is required for the cleaning to take place.


Our shorter shelf allows the ram to move freely along the bottom stone bed and to continuously clean. As a result, less force is required to move stone around the shelf, which reduces hydraulic pressure and stone crushing. The decreased pressure means the hydraulic components continue to function seamlessly for longer and in better condition.


Having flexibility when producing pebble lime can make all the difference to your business. Our MCP Preheater permits you to adjust the stone bed even while it is in operation, which allows you to optimise the bed height for maximum heat transfer at minimum pressure drops.  The end results are lower specific power and fuel consumption for your rotary kiln system along with lower maintenance requirements.

Enhance performance and fuel efficiencies with our MCP Preheater

Our MCP Preheater has a wide range of features to enhance performance and help you to achieve efficiencies:

  • Individual symmetrical stone chimneys for uniform stone flow.
  • Adjustable stone bed depth.
  • Compact feed shelf to reduce crushing during stone transfer into the rotary kiln.
  • Flat non-load bearing preheater roof.
  • Full circumference for hot kiln gasses to enter the cassette.
  • Gas enters the cassette from all sides equally and exits the stone bed through a dedicated aspirator.
  • Stone chutes help reduce stone bin false air.
  • Central stone bin delivers stone uniformly to the individual cassettes.
  • Cassettes are symmetrical and constructed from refractory lined cylinder.
  • No corners in the cassettes to promote buildups.
  • Patented reverse distributor moves coarse stone to the cassette centre.
  • After reaching the ram level, hot precalcined stone is thrust out the fully annular stone discharge opening and onto the feed apron, before moving into the kiln.
  • Patented shelf geometry eliminates dead zone area.
  • Reduced wear on the hydraulic components and less fines generation.
  • Ultra-low ram pressure.
  • Each ram is powered by a hydraulic cylinder, which itself is controlled by a signal from an LVDT (linear variable displacement transducer).
  • LVDTs provide constant feedback on the exact ram position to the operator.
  • Ram hydraulic power unit has two pressure compensated variable displacement pumps, one operating and the other for stand-by.
  • The maximum system pressure is limited by a relief valve, which acts as a safety relief while a ram is stroking.
  • Two hydraulic accumulators are mounted on the ram supply head in order to reduce the pressure spikes in the hydraulic system.
  • Control of the limestone feed ram is regulated by the length of time elapsed between the start of the push stroke of one ram to the start of the next ram, which allows multiple rams to move simultaneously.
  • An alarm will sound if the ram does not reach the programmed position of the LVDT in a predetermined amount of time.


PDF (264KB)

Stories from FLSmidth