Pneaumatic wood powder transport

(not verified)
Posted in: , on 25. Apr. 2007 - 12:53

I am working on a project where I am optimising a woodpowder transportation system, That will pneumatically transport the wood powder from a belt feeder that consists of cells through a hose to a powder burner.

the belt is 100 mm wide and the dimensions of each cell is 3*5*100 mm.The belt is covered and we are blowing from one side of the belt and there is an exit on the other side.

For the specific wood powder it doesn't seems to work very well. The powder from "cookies" that remains in the cells on the belt. depending on the airflow 5-50 % of the powder remains. The target is that all of it will blow of or at least 99 %

The Sieveing analysis of the powder shows the following:

> 1 mm 0 %

0,71-1 mm 5 %

0,5-0,7 mm 20 %

0,25-0,5 mm 37 %

0,125-0,25 mm 20 %

< 0,125 mm 18 %

The moisture content is 6 % and the material is a mixture of pine and fir with no additives.

the target airflow is about 100 l/min (7,5 kg/h) for a powder massflow of 15 kg/h. that gives a solid to air ratio of 2. (Which seems to be possible with other types of wood powder). At the moment we need to use a solid to air ratio <0.5 to get 95 % of the powder from the belt.

The airflow passes through approx 2 cells at the same time which should give an air velocity of about 55 m/s (at 100l/min)when passing the cells.

Anyone that has any suggestions of how to improve the system? how should we blow? All ideas or are more than welcome or suggestions of resources.

thanks Martin

Sawdust Handling

Posted on 28. May. 2007 - 04:18

Hi Martin,

Seems like you must be the expert on using wood flour as an energy source.

In West Australia we used sawdust from the mills. The product was delivered to a bunker by 20 ton tip trucks. It was reclaimed using Redler scraper conveyors, cross fed with a multiple discharge screw conveyor, and injected into the fire boxes by steam.

We had 5 marine steam boilers serving the Hollywood Hospital. To trim the stockpile we provided a trapeze suspended scraper conveyor. For control we used mercury tilt switches. This was well before the days of PLCs.

It was certainly an advance on using men with shovels to stoke the boilers. Later on the boilers were converted to diesel fuel. the cost of maintenance and labour was too high with sawdust.

Regards - Sgt John.rz