×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

How to transform teoritical into real number of trays

How to transform teoritical into real number of trays

How to transform teoritical into real number of trays

(OP)
Is there someone who can give me a detailed explanation how to transform teoritical into real number of trays for atmosheric tower fed with the effluent from H OIL reactors (hydrocracking of vacuum residue). The feed is described by a definite number of pseudo components. Is it possible to use the O'Connell formula Eoc = 0.492*(μl*ά)^ -0.245. In this case concerning for example section for separating high atm gasoil(HAGO) from atm residue (AR) which of the pseudo components, describing the two above fractions must be characterized? I mean to know their liquid viscosity and relative volatility in order to solve O'Connell's correlation. My idea is to seperate them so that 5% boiling from AR to be  360 C and 95% boiling from HAGO to be 370 C  

RE: How to transform teoritical into real number of trays

biofan:

You have not described your problem or explained your question well enough. There really is no reliable equation for converting theoretical distillation trays into actual distillation trays.

Fractionation Research Inc. at http://www.fri.org/ has been developing such data for various tray types and various types of distillation at various pressures and temperatures for over 50 years. They are a non-profit research organization and access to their data is limited to their member companies.

You might try contacting them to see if such data as you need is available and what it would cost to get saccess to that data.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

RE: How to transform teoritical into real number of trays

Stupid me for asking, but...

If the number of theoretical trays is always expected to be different than the number of actual trays, is there something about the "theory" that needs review?

Regards,

SNORGY.

RE: How to transform teoritical into real number of trays

SNORGY:

As they say, "no question is stupid".

A theroretical tray is a tray that is theorectically 100% efficient. Actual trays are not 100% efficient ... their efficiency is a function of the trsy type (bubble cap or sieve or etc.), the distillation temperature and pressure, the components of the liquid being distilled, etc., etc.

Research such as FRI performs using different trays at different temperatures and pressures and for different liquids ... in a fairly large-scale demonstration distillation column is what is required to determine tray efficiencies.

Alternatively, if one can find an actual commercial scale column using the same type of tray and distilling a similar liquid, data from that column can be used to determine the efficiency.

If you cannot obtain access to FRI data. the best bet is to contact some well-known tray manufacturers who have had experience with a similar distillation column and have them do your column design. In fact, that is always a good idea ... rather than trying to "do it yourself".

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

RE: How to transform teoritical into real number of trays


Isn't the planned ASTM distillation overlap between the HAGO and the UCB a bit too narrow ?  

RE: How to transform teoritical into real number of trays

(OP)
I just want to understand how designers as a whole, once they have determined the theoritical number of trays convert them into real. Thank you for the answers.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources