New graphite seal optimises kiln performance

January 5, 2015 Morten Hansen

Designed for fast installation on any kiln, FLSmidth’s new kiln graphite seal reduces ID fan power consumption


Energy efficiency and low maintenance is essential to optimal kiln performance. The new FLSmidth kiln graphite seal reduces the need for maintenance and optimises the operation pressure stability by preventing false air entering the system.

FLSmidth provides a highly effective kiln seal that utilises carbon graphite. The seal, which fits any kiln, uses a staggered arrangement of overlapping graphite blocks [1] held in place by a wire rope system to ensure an efficient seal against the outer air casing [3]. The arrangement allows the graphite blocks to move independently with the radial movement of the kiln without the graphite blocks getting stuck or damaged. The locking plates [4] on the rear flange [2] is a key design feature that prevents false air from entering the kiln system.

  Each module is designed to be pre-assembled before installation

The inlet seal air casing is designed to handle back spillage, directing it to the hopper for collecting in the bin.

Trial assembly of the modular frames and thorough inspection of geometrical tolerances of the flanges in the workshop ensures the highest product quality standards.

Watch the graphite seal intro video to learn more about functionality and benefits >>

Designed for predictable, low maintenance
A visual inspection can reveal whether maintenance is required. When it is necessary, the wire rope system and modular frame enables quick replacement of the graphite blocks, while specially shaped distance spacers [5] prevent the need to dismount the flanges.

The wire rope system is comprised of counterweights and independent rope systems covering each row of graphite blocks. The ropes grip the graphite blocks tightly in place while also allowing for movement caused by kiln runout, ovality and expansion. This design allows for radial movement of up to +/-50mm and axial movement of approximately 300-400 mm.

The need for spare parts is limited, as the graphite blocks and wire ropes are interchangeable between the inlet and outlet seals. Furthermore, the graphite blocks’ self-lubricating properties significantly reduce the wear of the sealing components. Typically, the expected wear on the graphite blocks is 5-8 mm per year, resulting in a long lifetime.

The wire rope is designed to run for a full production campaign, but as an added preventative measure, the seal’s locking system will hold the graphite blocks in place in the unlikely event of wire failure.

“Visual inspection of the sealing during operation is easy. We have easy access to graphite seal blocks and we can change these without cooling down the kiln completely if necessary. That is a huge advantage. Furthermore, any back spillage from the inlet is effectively handled and lead to the ground.”

Technical Project Manager, NCC Egypt

Fast, cost-effective installation on all kilns
The new graphite seal can be fitted on any type and size of kiln – not just FLSmidth kilns. The graphite seal modular concept is designed to fit to the existing casing and cooling mantle without the need for modifications.

Installation of the graphite seal typically takes seven to ten days. A large amount of pre-assembly can take place before installation. This is made possible by the seal’s modular design.

FLSmidth’s inlet and outlet graphite seal has been retrofitted on a non-FLSmidth kiln at NCC Egypt.

Inlet and outlet seals
Two types of kiln graphite seals are available. The kiln inlet seal is designed to provide the interface between the kiln and preheater and the kiln outlet seal interfaces the kiln and the cooler.

Both seals are designed to help maintain optimal kiln operating conditions and to minimise the loss of expensive energy.

Read more about the kiln graphite seal here>>

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