Condenser Discussion

[FranzVon]

Hello Everyone,

This is my first post so if this discussion already exists or its under the wrong topic/category please let me know.

I would like to start a discussion about solvent recovery regarding the types of condensers. Personally I care more about my vacuums health because that will be more expensive to fix compared to buying more solvent. I found a great article/web page describing the types of condensers and the proper use for each. If anyone cares to check it out, let me know if you agree/disagree with anything in the article.

Does anyone have experience with any of the not as common condensers like Fredrichs or the crazy looking Hartzler condenser?

Link: Types of Condensers | Hobby Chemistry

Thanks,
Franz

[Soxhlet]

Use a condenser appropriate for your process, protect your vacuum pump with a cold trap. Also use a chemical rated pump when distilling solvent.

[cyclopath]

How does one determine which condenser is appropriate for my processes?

When I started this game I’d just buy the biggest one i could afford. That eventually led to an empirical understanding of some of the variables involved in appropriately sizing a condenser. I learned the importance of the temperature of the coolant when my first production still started spitting fumes in early July. The 50ft garden hose out in the parking lot was now preheating my cooling water to about 40C!. I could solve the problem by upping the flow, but throwing metered water down the drain as the dry season started didn’t sit well.

Which got me playing with air/liquid style condensers. Where I again just reached as high as my budget allowed, purchased a SS cooling coil from the local brew store, and added fans till I had joy. Not my best work, but it got the job done.

Turns out there is a ton of well established math on the subject (doh!)…

If you’re condensing for solvent recovery, then the most important thing to remember is that all the heat you put in, you also have to take out.

@TheGratefulPhil has been kind enough to work the math for both the heating and the condenser sides of the equation.

Optimizing Processes with Engineering Fundamentals

There are several details here that can drastically alter the calculations. First, we can either assume that the ethanol vapor entering the condenser is at its boiling point or needs to be cooled to its boiling point before it can condense. Next, will we be running at atmospheric pressure or at vacuum. I have taken the liberty of assuming that the condenser duty is calculated for condensing ethanol at its boiling point and at atmospheric pressure. This simplifies things. Now, calculate the hea…

Ethanol recovery maths

Ahhhh, now I can size that pump! So, if you ONLY need 50 kW of heat duty to warm your extract to the boiling point of ethanol you can use the following equation for the water used to heat: Q = mc(Th-Tc) We know Q = 50kW = 50 kJ/s = 50000 J/s m = mass flow rate of water (g/s) C = Heat capacity of water = 4.184 J/g*K Th = 60C = 333 K Tc = 35C = 308 K m = 478 g/s. Let’s assume 500 g/s Water’s density = 1 g/mL 478 mL/s = 1,720 L / hr of water flowing through your boiler. You were basicall…

The folks selling you your heating or chilling should also be able to solve the math for you, or look it up in tables…but that assumes you’re purchasing from someone who does heaters/chillers as their primary business. Which is probably a good idea anyway, as anyone else is just playing middleman, and will likely charge you more for the same (or even wrong) system.

Thanks for upping my game!!!

[Soxhlet]

Appropriate in the sense that graham condenser shouldn’t be used for a horizontal condenser, nor would it make a good reflux condenser.