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!

*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

wax and hydrate issues

wax and hydrate issues

wax and hydrate issues

Dear all,

  Just got a question about blowdown system. My system is to blowdown well stream (345 barg, 10 oC, 0.6 m3) to atmosphere pressure during choke maintainence. The outlet temperature is around -82 oC. The wax cloud point is 42 oC. Could the wax and hydrate be an issue in this case? Thanks in advance.


RE: wax and hydrate issues

I struggled with the same question on your interesting problem and my thinking is this.

Yes, hydrate and wax formation are very much a concern because of the high pressure and resulting large temperature drop in normal blowdown cases. With normal I mean large volume systems requiring blowdown. From a thermodynamic point of view the outlet temperature will be  very cold as you predicted. However, your system volume of 0.6 m3 is quite small and should depressure quickly, while the outlet gas temperature would increase quickly from the intial -80°C temp. The relative small gas volume may not have enough mass to create a hydrate or wax plug.  Also, the relative hot piping system can have a lot of mass that needs to cool down and will work to your advantage and slow the hydrate/wax formation down. It is hard to tell what exactly is going to happen, but I believe if you blow down the system down slowly you may not have a problem at all.

Only experience would tell you the real story. If in doubt, utilize a two-stage blowdown and preheat the gas in the intermediate pressure stage to keep it out of the hydrate/wax formation region.

I am very much interested in hearing more about this from other engineers with more field experience. Hydrates and wax plugs can set-up fast, but they do require a bit of time to develop.


RE: wax and hydrate issues

I've heard of a russian engineer trying to use ultrasound to dislodge and melt any wax/hydrate crystals that may appear.

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! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close