Method and arrangement for torrefaction with controlled addition of cooling liquid to the torrefied material
AssigneeValmet Power AB
InventorPeter Björklund
Life of this patent
Estimating the term…
Abstract
The improved method and arrangement are for cooling torrefied lignocellulosic material. By adding water in controlled amounts to the torrefied material in a grinder at exit from a roaster the entire volume of torrefied material could be cooled down to a temperature well below the critical temperature without increasing the water content of the final product.
Claims19
A method at producing torrefied products which are burnable to produce thermal energy, in which method a lignocellulose biomass material (W) is used as a starting material for the torrefied products and which method comprises the steps of:
- passing lignocellulose material (W) through a roaster in which the lignocellulose material is subjected to a temperature in the range of 180° C.-400° C. in an inert atmosphere which is substantially free from oxygen such that the lignocellulose material becomes torrefied;
- passing the torrefied material from the roaster to a mill,
- a cooling liquid is added to the torrefied material at least in one position between the roaster and the exit of the mill such that the cooling liquid is mixed in the torrefied lignocellulose material during the grinding, and
- passing the torrefied lignocellulose material and mixed cooling liquid to a separator where steam is separated thereby cooling the torrefied material simultaneously, and subsequently passing the cooled torrefied lignocellulose material to a pelletizing machine.
An arrangement for transforming lignocellulose material to a torrefied product that is usable to produce thermal energy, the arrangement comprising:
- a roaster vessel in which the lignocellulose material is torrefied;
- a mill connected to and following the roaster and a feeder to feed torrefied material from the roaster to the mill, said roaster vessel and said mill containing an inert treatment gas phase,
- an inlet conduit for liquid is connected to at least one position between the roaster exit and the exit of the mill such that a cooling liquid is feedable into feeder and/or directly into the mill to be mixed with the torrefied material, and
- a separator is located after the mixing of cooling liquid such that steam is separated from the torrefied material before the cooled torrefied material is sent to a pelletizing machine.
Dependencies are inferred from the claim text.