3 replies to this topic

[keby9vam]

Hi all,

I am curious to know if whether manual calculations are done for distillation in oil and gas industries as the incoming mixture might consists of 15+ components or do the engineers focus solely on simulating the distillation in a simulation software (like Aspen Hysys)?

Usually we are trained to do both at university level so that we can affirm our results in the manual and software calculations. But it would be tedious to do manual calculations for 15+ components in the oil and gas industry. Thank you.

Regards,

keby9vam

[Art Montemayor]

keby9vam:

Engineers are supposed to be taught and trained to function as practical scientists. Practicality and common sense are our prime characteristics. We get the job done in the safest, most economical, simplest, and fastest manner. To that end, you are correct in stating it would be tedious to do manual calculations for 15+ components in the oil and gas industry. That is why engineers designed a method to avoid that completely – we designed the computer to crunch out the numbers and do the simulation.

Once the basic science and the logical algorithm is worked out on how to proceed to resolve the design of a multi-component distillation column, the job is turned over to a very stupid computer that employs a program designed and written by engineers. It does all the number crunching, manipulations, and iterations. There is no reason why an engineer should waste time doing mundane, repetitive work.

HOWEVER, there is an important requisite before doing any computer design: the engineers responsible for the design have to be masters of the science and mathematics involved in setting up the computer program, feeding the data, and interpreting the results. The stupid computer is incapable of doing that. I still recall the first Fortran course I took in University in 1959. It was one of the first taught and I am glad I was able to learn the basics of just exactly where the human engineer fits in when putting together a complex design. Without your complete understanding of how the problem is supposed to be solved, you are lost as an engineer. No machine is going to “design” anything for you. YOU are the brains; the machine is the slave – or minion - waiting for instructions. If you give it the wrong instructions, it will carry them out and produce the wrong answer. That is why, in my opinion, it is vitally important for all Chemical Engineers to get manually involved in trying to calculate a 15+ component distillation problem. Only by doing it this way can you understand, appreciate, and be able to interpret the final solution produced by a computer. We may be practical in using the computer to do the mundane work, but that doesn't mean that we trust it to do our thinking for us. Our common sense prohibits that.

[PaoloPemi]

I agree with Art Montemayor,
one thing which makes me feel angry when discussing some results is a client asking "which software have you utilized ?" not which thermodynamics or any other question to test my capability to do the correct design, it's really frustrating :-(

[T.S.MURALI]

It is man who does the logic of programing and programs the logic. Manual method is the starting point always.

For example, you can do a fired heater calculation manually (example: Refer HandBook - Wallace) and also do it through HTRI. So also for Heat exchanger design.

What you do in an Excel format can be gotten from "software" output. So the manual method is the logic always, which paves the way.