9 replies to this topic

[panduru]

What is a Retort

As a piece of process equipment, what should I understand by Retort?

From the process as well as mechanical design standpoint, how does a Retort differ from other kinds of vessels? I have not come across this term in mechanical design references so far, possibly by oversight. But I feel it is more of a chemical engineer's usage.

Any references for further reading will also be greatly appreciated. Thanks.

[gvdlans]

From Wikipedia (http://en.wikipedia.org/wiki/Retort)

A retort is a rather primitive laboratory glassware used for distillation or dry distillation of substances. In the latter case in many cases where the absence of air is required. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated. The neck acts as a condenser, allowing the evaporated vapors to condense and flow along the neck to a collection vessel placed underneath. In industrial applications it is an airtight vessel in which substances are heated for a chemical reaction producing gaseous products to be collected in a collection vessel or for further precessing.




As far as I know retorts are not used anymore in modern laboratories.

[panduru]

Thank you, gvdlans.

But I was referring not to laboratory glassware. I meant process equipment used in chemical industry.

Also, my interest is from the design point of view, not the functional.

Any ideas are most welcome.

[gvdlans]

Maybe you missed the following part:

"In industrial applications it is an airtight vessel in which substances are heated for a chemical reaction producing gaseous products to be collected in a collection vessel or for further processing."

[Art Montemayor]

panduru:

I've seen your query in Eng-Tips on the same question and I failed to reply because you didn't state what you are going to design and what is your scope of work. The term "retort" is not only primitive - as gvdlans correctly points out - but it is not even used by chemists themselves anymore. I believe I know why you are asking and what you have been assigned or propose to do, so I'll express my experience related to such terms.

I've worked in projects related to companies that were originally started by Chemists - around the start of the last century - and I can still recall the difficulty we young chemical engineers had with the chemist's idea of how to apply laboratory findings to an industrial environment. Basically, before there were enough Chemical Engineers to make an impact and difference in the chemical processing business, Chemists took what they used in the laboratory and simply scaled it up (made it bigger) and used the same terms they knew. Chemists are not engineers and Chemical Engineers do not think like Chemists - regardless of what Mechanical & other engineers believe. However, we lived through an era that had to tolerate a lot of ridiculous names for processes and equipment simply because that's what we found embedded in the industry around the early 1900's. Today the terms used are more descriptive and well-understood amongs all engineers. Engineers have taken over now and the Chemists have gone back to the laboratory where they excel.

Any term - such as "retort" - can mean whatever it is that you want it to mean. Today, in a modern chemical processing environment it could mean literally anything. You have not told us what it is that you propose to do, so I don't know specifically what you want to build. You have picked the word "retort" - and it could mean a mix kettle, a batch reactor, a decanter, a sparging vessel, a 2-phase separator, etc., etc. There are no universal or "standard" definitions for terms used in industry - no matter what anyone says. There is no Systeme International for naming equipment. What, specifically, do you mean by "design point of view"? Sooner or later you're are going to have to define the functionality of the vessel you propose - otherwise it is not engineering; it would be artistic. You see, Chemical Engineers have a very organized method of classifying processes and operations. We have Unit Operations (wherein physical changes take place) and Unit Processes (where chemical changes take place). Depending on what is taking place, we design the equipment appropriately.

Why would you suggest or inquire whether the vessel is hemispherical in shape. Chemical engineers would never use a hemispherical vessel, in my experience, unless they definitely needed the functionality of a spherical shape or its characteristics - like for example:

1. You need to "digest" raw materials with constant mixing under pressure and agitation - without an external powered agitator;

2. You require the inherent strength the sphere gives you in order to carry out a process under internal pressure;


I have used a spherical vessel to comply with the above scope input in order to extract Furfural from corn cobs and oat hulls. We called it a "digester". I would not recommend this method unless there was no other alternative. It is expensive to build, operate, and maintain. You can build any sphere out of two hemispheres if it conforms to the internal volume you require.

Why is it that persons who post these type of general questions want to receive a specific answer when they do not funish specific basic data. Hell, NO basic data has been furnished at all in this case! Why do I get the feeling that this is a secretive and very arcane vessel that is being discussed and we can't be given any data? A retort can be cylindrical, ellipsoidal, or spherical. I've had a retort that was cylindrical - but I doubt that it's the same applicatiion that you are dealing with or proposing.

Perhaps if you tell us ALL of the story and ALL of the facts and data, we might just be able to not only answer your query but help you out also.

[u]

[panduru]

Thank you, Art, for the detailed response.

Since you have taken kind interest, let me put the things in the right perspective.

The term "retort" was used in a design request by the user. I have designed various kinds of process equipment according to the guidelines of ASME BPV Code/ API/ TEMA etc., but never before come across this term, after leaving school, that is. What wiki says is precisely what we learned in school.

It was intended to clarify if a certain kind of vessel or equipment is either technically or informally referred to as a retort. That was the reason for the post.

In the posting of gvdlans, he quotes from wiki: It consists of a spherical vessel. So it was clear that any industrial retort, if there exists such a thing, must be construed as consisting of two hemi-spherical parts.

Since you seem to be emphatic that no such thing really exists, at least by that name, it must be concluded that the user's requirement was stated incorrectly.

Most importantly, as a MechE, I was not interested in the functional designation, rather the structural class of the equipment (ref to it could mean a mix kettle, a batch reactor, a decanter, a sparging vessel, a 2-phase separator, etc., etc. and We called it a "digester")

It is very interesting to note your remark: A retort can be cylindrical, ellipsoidal, or spherical. I've had a retort that was cylindrical - precisely what was it that prompted you to call that particular piece a retort? Why did you refer to it as such?

Honestly, I am still trying to understand the usage of the term by ChemEs! However, if the term is not likely to occur any more in future usage, there would be no reason for me to be interested it.

Thank you very much again, Art, I look forward to your continued mentoring. Regards.

[joerd]

This could simply be a translation issue, if your customer is not a native English speaker. As we all know, one word can mean many things, and can therefore have a number of translations. So your customer could have picked up an old or non-technical dictionary, and came up with retort - not meaning anything other than "vessel".

[panduru]

Thank you, Joerd, sounds entirely plausible though it never occurred to me.

[sgkim]

Hi visitors,

I once read "Retorts" were used for the simple fractionation of gasoline, kerosene,etc ..from crude oils long time ago, those have been changed nowadays to multi-staged continuous crude and vacuum distillation columns. The shape of the "industrial scale" retort was just like the same as the labware. In chemical indudtry, presently, the term no longer exists. Rotary kilns or cookers are sometimes called as "Roaster" or "Retort".

In food industry or hospitals, however, the word "retort" is still used, but the meaning of it is "high pressure cooker" or "high temperature sterilizer".

You can find various kinds of RETORTs here: http://images.google...?q=retort&hl=en

sgkim