No heat transfer in SS wiper after running crude with sugars

I am at a loss for this one, was hoping someone in the community might have some insight.

A friend of mine ran some sugary crude through their distillation unit despite my warning. As expected it caked up their unit to which I recommended water and alconox flushes until it comes out clean. 20 or so flushes later and still having problems. Even with main body at 200C and internal condenser at 70C they have trouble making distillate (vac = 50mtorr). We have verified all the gauges are reading correctly. Our only thought is that there is so much caked on sugar preventing heat transfer.

Any recommendations for solvents that might work to clean the unit? Maybe distilled vinegar?

Try acid. Hot 5% phosphoric loosens up sugars pretty well followed by detergent.

Thanks for the recommendation! Will give it a shot.

lots of water flushes the best way to get the detergent out afterwards?

Yep. Alconox doesn’t leave much residue so 3 rinses normally does it. I recommend checking pH of the last rinse to make sure all the acid comes out

We were recommended and had success with a caustic cleaning solution used in the brewing industry. We did a wash with that, then 2-3 washes with distilled water, then a wash with ethanol. Cleared things up pretty well on our system. Only warning is if you do this too often you will need to repassivate your stainless more often.

Yeah we were hoping to avoid heavy duty acids and bases but don’t really see many other options at this point. It doesn’t really matter how long the unit lasts if it doesn’t distill anything!

Will do. They have some mother liquor that gets flushed through after cleaning just in case anything was left behind.

It’s not too big a deal honestly. The acid and base wash solution is usually reusable 10+ times. The lye for the base wash is dirt cheap and phosphoric is pretty inexpensive too

For sure, pretty cheap solutions. Just want to confirm no implications for Teflon wiper blades right?

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Nope, PTFE is super chemically resistant, acid and base aren’t gonna do anything to it

Fantastic! Thank you for the help! Ill report back in a couple days if we can get it back up and running

Sometimes the wiper blades get damaged, so if cleaning doesn’t fix it check the blades

@broken_glassware is correct;

Chunks of burned sugar can be harder than Teflon unfortunately…so you might should open the damn thing and inspect the wiper anyway…


…the column is 15 ft tall. Need a crane to do that

I’m surprised that much washing wouldn’t have got rid of it by now. Have you actually opened it up to confirm there is sugar remaining?

No given its size, opening it up is a serious challenge

Might want to invest in a sight glass or inspection port at some point

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Well I’m going to have to recommend you get some equipment to take care of that because one day or another you’re going to have to

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Sounds like you might should own one of those.

Try methanol