Anaerobic Digestion Facility Ventilation

[m2e]

I'm working on the ventilation design of an anaerobic digestion building.

Here's the description:
- Building volume: about 400000 cu.ft.
- The building is attached to the digestion chambers, and the chambers can be accessed from inside the building.
- The digestion chambers contains methane gas, but is normally enclosed.
- Two 200hp diesel wheel loader are operated in the building to load the organic load in and out of the chambers
- The chambers are positively pressurized.

What's your opinion of these:
1. the NFPA classification & ventilation rate?
2. the ventilation rate for the two diesel wheel loader?
3. Positive or negative pressurization of building?

Thanks

 

[ccjersey]

If this is going to be a "dry" anaerobic digestion facility with the wheel loaders used to both load and unload the units, you will need some very effective methods of scavenging the digester units atmosphere before opening them and then keeping the gasses being released from the contents as it is removed from reaching an explosive/poisonous/hypoxic/hypercarbic condition. The wheel loaders would not add a lot to the ventilation requirement in that situation. Operating at other times would require some consideration of ventilation.

If the loaders are moving the contents outdoors keeping any kind of pressurization in the building will be impossible while that operation is going on. I'm thinking the best bet would be lots of airflow through the building into the digester units and out the far end whenever they are open.