Solvent vapor evolution during a transfer into a drum

Chemical Engineering general discussion Chemical Plant Design & Operations
#1

Are there any guidelines to estimate how much solvent vapor would be created when pouring a solvent into another container?

My initial approach is to assume the drum vapor space would establish the equilibrium partial pressure of the solvent and then that mix of solvent and air would be displaced at the same volumetric rate of the poured material. I don’t think this is representative of the actual solvent evolution rate because I think the pouring action will make more solvent vapor evolve.

Edit to clarify this scenario:
People bring satellite solvent waste containers to a 55 gallon drum that’s situated in a room next to the offloading dock. The room the drum is in has general ventillation (so some amount of recirc) and isn’t a classified space. The drum is filled using a funnel (linked below). The drum is closed when not being filled. I do not think the drum poses a fugitive emissions risk when closed, but during the filling I’m concenred about creating a transient flammable atmosphere.

I’m looking into options to make this a more closed-system type operaiton (or a once thru exhaust trunk), but at the moment I’m just being asked by EHS to see how close to the LEL does this operation get us to.

#2

Your approach is what I have seen done. Check with your EPA counterpart in the jurisdiction where the operation is/will be located.

#3

Your method should be the worst case analysis unless there is liquid spillage. You can almost eliminate emissions by piping the displaced air from the drum back to the headspace of the solvent tank, as they do with vapor recovery nozzles at gasoline filling stations.

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#4

I thought the method I described wouldn’t be the worst case because the motion of the liquid pouring into the drum would cause some solvent to aerosolize and create a spike in vapor phase concentration. Am I wrong in this assement of the fluid behavior?

#5

Yes, splash filling has more emissions than submerged filling.

#6

To close out this thread, I got the Ops folks to agree to move the 55 gallon drum outside under an awning so the EHS folks were satisfied that this removed the pertinent hazard. I’ve asked EHS to look into whether a respirator/breathing air hood would be best practice as well.

I didn’t find any info about how much worse evolved emissions from splash filling v.s. via dip-pipe to aid in the calcs.

#7

Once the air is saturated (at equilibrium solvent concentration) nothing can cause more solvent to evaporate. Simple splashing doesn’t really create any significant aerosols.
Almost all gasoline containers do not have separate air vents anymore. Air enters the dispensing can at the fluid nozzle so emissions during pouring are very small, although it seems difficult to avoid some spillage.