I 100 % agree with Tom - the same relations apply top straw dividers - you can get a farm designed thing that can produce 10 tons pr hour for 1 hours a day for 40.000 € - and you have to pay 250000 € for a chipper that can deliver 7 tons pr hour 24/7/12.
Concerning the physiscs of how to press biomass through holes i disagree with you on the basic mechanisms you describe. If you measure the ration of Poisson for biomass with increasing moisture content you see an increase from 0,1-0,2 at 5 % dm to 1 at 50 % moist. You will also find that biomass with 45 % dm is vitually pumpable at high pressures but biomass at low moisturecontent are not. I think what is happening is that the water is leaving the back of the "plug" thus give raise to poissons ratio in the far end of the plug and thus giving force perpendicular to the direction of motion and thus getting stuck. Thus the reason for water decreasing the friction in biomass in channels is that the water takes up some of the force - the friction biomass-steel is almost independent of moisturecontent ________________________________________ Fra: [email protected] [[email protected]] på vegne af [email protected] [[email protected]] Sendt: 5. juni 2011 15:58 Til: Discussion of biomass pyrolysis and gasification Emne: Re: [Gasification] Sawdust in Fan TLUD On Sunday 05 June 2011 14:30:37 Thomas Koch wrote: > Yes it was a machine that created som puck like lumps out of straw - i > think you are right - you need something like 2-500 MPa to form a > stable densification in a very short time - thus if you have rollers > you will get enourmous dimensions on the axels and bearings . You ca > reduce this force if you increase the time - but then capacity drops. I suppose speed is more important in a mobile plant, to keep up with the harvest you'd need to process in the order of 50 tonnes/hour?? I could see the need for the diameter of the press wheels to be smaller than the sprocket which leads to chain drives above and below the press to spread the drive load around the periphery. > > Can you please explain the work of you mate once more for a viking > tyhat are not familiar with all the abreviations? (mc wbb ??) It was very simple trials to squeeze whole (short) logs through a steel plate with shallow conical holes drilled through it such that their edges overlapped to produce a knife like series of ridges. As fresh wood is full of water the forces necessary were too high to force the wood through and collapse the cell structure. If the wood was dry ( 10% moisture content on a Wet Weight Basis) then the wood could be comminuted by forcing it through the pate and producing a wholle wood pellet at the same time. It was not pursued as the throughput was low and it looked like abrasion would be an issue with keeping the die sharp. AJH _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/ _______________________________________________ Gasification mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
