# How to calculate the required airflow to dry a batch of sawdust?

Sawdust has to be dried while in storage waiting to be processed.

The time window for the drying is 12 to 36 hours.

The storage room is 20m x 20m x7m (L x W x H).

The sawdust is stored on 300m2 of the 400m2 available. It is placed on tent vented steel sheets at 0.5m above ground.

This gives a sawdust volume of 100m3 and an aproximate weight of 21000kg. Sawdust humidity 50%. I would like to take it as low as possible in the available time window. Let's say 30% would be acceptable. 20% would be great.

What airflow has to be provided from under the vented steel sheets in terms of volume, temperature and humidity?

I was thinking to use tubes to distribute the air under the steel sheet. The air in will be matched with roof fans taking the air out. I would like to have a rough idea so I know with what equipment to start.

• What heat source will you use? Any agitation for your saw dust bed? Design review re. dust explosion hazard?
– mart
Commented Jan 30, 2017 at 11:01
• Your limiting factor will be the sawdust getting trapped in the vent screens from the flow of air but as much air flow as possible, updraft will allow fluidised bed operation. Temperature needs to be kept below 451 degF to prevent flash point and lower to minimise polymerisation but otherwise as hot as you can afford. The dryer the air the better, fresh ambient at a minimum (no recycle of air, just exit heat recovery) but previously dehumidified air would be best. Commented Feb 2, 2017 at 8:59
• Your questions is rather open ended but you are trying to remove a lot of water. 21000*.5 - 21000*.2 = 6300kg of water. Here is a paper that may offer clues on how much energy you will need in the end. - scholarworks.uark.edu/cgi/… Commented Feb 2, 2017 at 9:08