Micro-gasification: Cooking with gas from biomass - Amper

Micro-gasification: Cooking with gas from dry biomass
b) Ring-die presses
In a ring-die the die is in a ring/drum shape and moves against fixed ‗rollers‘. This is normally
used for bigger machines with outputs starting at 200 kg per hour. Ring-die presses
are normally more expensive than smaller flat-die presses, but can achieve usually higher
outputs per hour, as there are many more holes in the outside walls of the drum-shaped
ring die than in a flat sheet-style die. Most industrial-size pelletising plants use ring-dies.
Ring-die press: the die is fixed and the rollers move,
thus pressing the feedstock through the lateral holes.
Source: Reed/Bryant, Densified Biomass p. 9
HERA – GIZ Manual Micro-gasification Version 1.01 January 2011
Ring-die press from AgriconSA in action
(Photo Christa Roth)
The choice for the appropriate pelletising equipment is highly dependant on the material
specification of the envisaged feedstock and the envisaged scale of operation. Hardly any
experience on the topic has been gathered so far, thus it is difficult to make recommendations.
Many small-scale pelletisers seem nowadays to be made in China. The life-span of
the Chinese dies is not well known yet, but expected to be the most vulnerable part. Pelletisers
often need to be combined with hammermills or other sizing equipment to bring the
feedstock to the right size.
Ecoworxx in Germany have started in 2010 to produce an ‗all-in-one‘ pelletiser with an included
grinder http://www.ecoworxx.de/index_en.html. The machine seems promising for
initial trials. Required electricity input is only 3 KWh, but tri-phase. Some manufacturers in
the USA also have single-phase equipment running on 220 V e.g.
http://www.pelletpros.com/id68.html or http://www.buskirkeng.com/.
On the African continent the only currently known manufacturer of pelletising equipment
with self-regulating feed-options to avoid clogging of material is Agricon in South Africa.
Their machinery is designed for less-skilled users for handling. They make larger-scale robust
ring-die equipment focusing on agricultural uses.
For further information see http://www.agricon-pelleting.co.za/.
91