Hi Everyone,
I get this question a lot: How big should my heater / chiller be if I want to recover X lbs/min.
Because this question is frequently asked around here–I decided to make a quick spreadsheet and take a snip for you all to see.
There are two segments: one for butane, one for propane. The “desired” mass flow (shown in lbs/min) is the leftmost column of the data. The next is the amount of heat required to heat the LPG from its temperature when it enters collection to its boiling point temperature. The next is the amount of energy required to boil that desired mass flow. The next is the sum of these two values. The final column is this amount of energy if it was transferred with 75% efficiency.
Basically, if you’re sizing a heater for solvent recovery, my recommendation is to use the value under @75% efficiency.
Keep in mind, the values for heat capacity and latent heat vary over pressure/temperature regimes–so this is an ESTIMATE.
Love, Phil
13 Likes
How about this one Phil,
How many lbs of dry ice to recovery 1lb of butane? I know there are a ton of other factors involved to get an accurate number, but what about the potential of the dry ice without any other environmental factors involved.
3 Likes
Dry Ice has Enthalpy of sublimation of 571kJ/kg.
If we’re interested only in the condensing of the gas that’s just been evaporated we only need to look at the Required Power for Boiling column.
I’m gonna throw economy in there just cause—let’s assume dry ice is $1/lb
@ 1lb/min for Butane, you will lose 0.005 kg/s of dry ice (about 18kg/hr or 40lbs/hr)
This means every hour you’re paying $40 for dry ice only. And for each shift $320. If you run 300/365 days a year that’s equivalent to $96,000.
@ 3lb/min for Butane, you will lose 0.015 kg/s of dry ice (about 55kg/hr or 122lbs/hr)
This means every hour you’re paying $122 for dry ice only. And for each shift $976. If you run 300/365 days a year that’s equivalent to $292,800.
This is why you buy a chiller that’ll do the same work but last for 10 years. It pays for itself in no time.
P.S. FOR BUTANE ONLY, you can buy a Huber chiller that will condense about 6 lbs/min for $38,500
https://www.growinglabs.com/products/huber-cs-chillers?gclid=EAIaIQobChMIpqSB6Net7QIVif_ICh1EiwAtEAQYASABEgIs3fD_BwE
8 Likes
one should recycle more of that cold before it goes into the evaporator.
4 Likes
That’s good info! Finding a good cls chiller for less that can condense that much butane would be a challenge for sure.
1 Like
Have you have good results using cold gas? I feel like since gas is such a poor conductor of heat, the heat transfer is minimal (but not negligible)
Maybe bubbling the gas through something?
1 Like
take the cold while it’s liquid
3 Likes
