×
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

Removing everything but hydrocarbons from gas stream
3

Removing everything but hydrocarbons from gas stream

Removing everything but hydrocarbons from gas stream

(OP)
Hi all,

I am beginning work on a new project for hydrocarbon gas recovery.
Basically, my client wants to take a stream of gas containing those hydrocarbons: propane, i-butane, n-butane, i-pentane, n-pentane, propanol, dimethyl-etherher and acetone, all in varying proportions.
This stream will be saturated with moisture and might contain nitrogen and other impurities, the objective is the eliminate everything from it except the HC, anyone has suggestions on how to do this?
Regards,
 

RE: Removing everything but hydrocarbons from gas stream

Membrane type of Separators.
Cheers,
gr2vessels

RE: Removing everything but hydrocarbons from gas stream

google Advanced extraction technologies.  Carbon Coconut shells) based PSA (nitrotech).  

RE: Removing everything but hydrocarbons from gas stream

(OP)
Thanks you very much for your input, i'm contacting manufacturers right now to see how it can be integrated in the process!
If anyone else has suggestions, i'm listening!    :)
Regards,

RE: Removing everything but hydrocarbons from gas stream

good luck,
 

RE: Removing everything but hydrocarbons from gas stream

danyduclos:

Define what you mean by hydrocarbons. I would define propanol, dimethyl-ether and acetone as hydrocarbons. That just leaves nitrogen and "other impurities" to remove. Is that correct?

Or is your definition of hydrocarbons simply the alkanes?

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

 

RE: Removing everything but hydrocarbons from gas stream

(OP)
Milton,

Yes you are correct, basically i want to remove nitrogen, oxygen if any and other impurities from the gas. what I want to keep are propane, i-butane, n-butane, i-pentane, n-pentane, propanol and acetone. I might also have dimethyl-ether in the gas stream.

Regards,

RE: Removing everything but hydrocarbons from gas stream

.
danyduclos:

If you want to remove the nitrogen and oxygen and retain the hydrocarbons you listed, then it could be done by low-temperature distillation using a turboexpander as is commonly done in a demethanizer to recover natural gas liquids (NGL) from raw natural gas (after removing any water vapor, CO2 and H2S).

Here is a schematic diagram of a demethanizer:



Of course the above design is for demethanizing and would have to be modified to fit your situation.
  

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

 

RE: Removing everything but hydrocarbons from gas stream

your gonna need a whole lot more equipment if you want to get rid of the N2. and temperatures a lot colder.

RE: Removing everything but hydrocarbons from gas stream

Hi, dcasto:

Agreed. Lower temperatures and more equipment will be needed to remove nitrogen (as compared to a natural gas demethanizer) ... but the principle is the same. In other words, low temperature distillation could do the job.

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

 

RE: Removing everything but hydrocarbons from gas stream

How much oxygen is present?

The order of treatment would be

O2 oxidation - using a catalyst
CO2 removal - amine unit
dehydration - TEG unit or molecular sieve
refrigeration 1 - removes heavier hydrocarbons
refrigeration 2 and distillation - cold enough to condense all but the nitrogen

This has been done in the past.

 

RE: Removing everything but hydrocarbons from gas stream

(OP)
What i can do is purge the system with nitrogen before the start of production so there would be nothing but nitrogen and hydrocarbons in the gas.
Is it possible to use sieves to remove the VOC and then to liquefy the hydrocarbon gas by compression at around 100 psig, then all that would still be gas would be nitrogen?

RE: Removing everything but hydrocarbons from gas stream

Liquefying at 100 Psig is going to require near-cryo temperatures.  You're going to require CO2 removal followed by mole sieve for water extraction.  This is starting to sound expensive.

RE: Removing everything but hydrocarbons from gas stream

(OP)
The gases i have in the mix are basically butane, pentane, propane; those gases don`t need cryo to get liquefied at 100 psi...

RE: Removing everything but hydrocarbons from gas stream

at -40F, you could still lose 10% of the propane with the N2.

RE: Removing everything but hydrocarbons from gas stream

(OP)
Dcasto,

Do you mean that the propane `bonds' with the N2?

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