Print page

Print page

Why don't ethanol producers use multiple effect distillation to remove ethanol from fermentation broth?

Q: Why don't ethanol producers use multiple effect distillation to remove ethanol from fermentation broth? Energy costs in processing cellulosic beers (with ethanol concentrations around 3%) must surely be holding the industry back, and MED could help. I am expecting that it is a practical issue of heat exchanger fouling, but is there more to it than that?

A: I am afraid I don’t know the answer to your question.  I do know that fixed valve trays are use in the Beer Stills because of the fouling.  I am not familiar with the heat integration schemes use by the industry.  However, Dan Summers (Dan.summers@sulzer.com) and Mark Pilling of Sulzer Chemtech USA (mark.pilling@sulzer.com), Dr. Izak Nieuwoudt of Koch-Glitsch (izak.nieuwouldt@kochglitsch.com), Dr. Michael Schultes of Raschig Jaeger Technologies (mschultes@raschig.de), and Henry Z. Kister of Fluor Enterprises Inc. ( henry.kister@fluor.com) may be able help you.

Here are more of the latest questions on: Distillation

Is there a guideline for setting the height of the conical section of a column?
I have designed a column with two sections of different diameters (enriching section 1,900 mm and stripping section 3,500 mm). Is there any rule or guideline to be followed to set the height of conical section of column between these two diameters? Presently I have considered height of conical section as 500 mm approx (equivalent to one manhole) between these two diameters.

Is vacuum distillation best to recover iso amyl alcohol and manufacturing esters?
I'm planning to set up a distillation unit for distilling fusel oil to recover iso amyl alcohol and manufacturing esters from it. I've been suggested to go for vacuum distillation through use of watering pump and reboiler of falling film evaporator type. The column will be about 10m high having a diameter of 0.6m. Is this the right way to go? Which packing should I consider? Will vacuum distillation break the azeotrope formed between water and ethanol?

Is there a good way to calculate the height of stage in a distillation column?
I'm working on a distillation column for a six-part multi-component distillation column. It contains structured packing. I estimated about eight stages with a model and came up with approximately the same answer with pseudo-McCabe-Thiele. I was careful to pick the correct heavy key and light key. Then, I realized I did not have a good way to calculate the height of stage. The model, like most, only tells you the number of stages not the height of stage or Z, the final height of theoretical packing.

Kister would say 1-3 feet as an assumption (based on gas resistance), or I could estimate it using a KG or KL. Empirical data would help.

I assume that the oil, a collection of C10+, would pose the greatest resistance, which makes calculating an H stage even more difficult. The feed is trace water, toluene and oils.

Any advice or reference that might be useful in solving this dilemma?

How do I calculate the void space in a column?
How do I calculate the void space in a column? Actually we are putting ½-inch balls in a 14-inch pipe. Height of packing will be 3 inches. Above the ½-inch balls we will put ¼-inch balls and the packing height will be the same (3 inches). How many balls can I put in the column?

How does a water draw off vessel work?
I need to design water draw off vessel. How does a water draw off vessel work?

Back to Ask the Experts