How the top particle size of the solid lumpy waste derived fuel,which is fed in different type of pre-calciner [e.g. vessel type (FLS designed) and duct type(KHD designed)] will be decided and logic behind it?
Michael Clark
For an FLS Hot-Disk the only limitation would be the inlet chute dimensions. For a Pyroclon then the size would have to be sufficiently small for the waste derived fuel to be suspended in the gas stream passing through the precalciner duct, i.e. lumps of material must not fall out of the gas stream and accumulate in the bottom of the duct.
Raj Sahu
Respected Sir,
Many thanks for your valuable response.In Hot-Disk technology we have flexibility in selection of top size of waste derived fuel.If we want to fire waste derived fuel in our existing precalciner system which are of FLS designed conventional vessel type, where gas velocity in the typical range of 5 - 7.5 m/s and KHD Pyroclone duct type calciner design where gas velocity in the typical rage of 15-18m/s.In my view material feed top size depend on the gas velocity. In FLS desiged precalciner top size will be different than KHD designed duct type calciner where gas velocity is higher.Your view in the matter.
With kind regards,
R.M.Sahu
wilfredzieri
Theoretical the particle size should be sufficient small for the particle not to fall through the orifice into the kiln inlet chamber. This again is influenced by th specific weight and shape of the particcle as well as the gas velocity in the orifice.
Based on our experience we normally recommend a max. particle size of 50 mm for 3.dimensional and 80 m for 2-dimensional (sheeting,foil) material.
However in practice we noticed always 3D material to fall through the orifice even with such sizing.
Other important factor on optimised combustion of alternative fuel is position of feed point to reduce formtion of CO which is a combination of particle size, mixing efficiency and Oxygen content all of which can be influenced by proper design.