×
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

Composition of slop tank at proposed compressor station

Composition of slop tank at proposed compressor station

Composition of slop tank at proposed compressor station

(OP)
Hello, and thanks for your time and feedback.

I am recent graduate working on design of a compressor station that will compress and dehy well gas for entry to a pipeline.
I have simulated the process in HYSYS and after saturating with water, separation, compression, cooling, and the dehydration unit: all the liquid dumps recycle back to the inlet separator and the liquids from the bottom of this separator are sent to atmospheric slop tank.
The composition I am getting for this liquid drain to slop tank is 98 mol% water. A co-worker told me this is wrong; he said too much water, that it will likely be around 60-70% water. I am not sure where I have made a mistake in HYSYS or if HYSYS is just not capable of simulating this process correctly.

I reviewed the stream and it is 99% liquid at the stream conditions. Coming from the separator it is ~100psig to the 0psig tank, so it will flash.
The 1% that is vapor is 77 mol% c1 and c2.
Is it possible that my simulation is correct and sum of the liquids (condensed underground from well, condensed on compressor skid scrubbers, open drains, glycol contactor drains, after separator drains)could be 98 mol% water in the liquid phase to the slop tank?

The MW of gas from well is ~77. 74%C1 and 13%C2. We will compress the gas to 1175 psig.
For now I assumed the gas left the well at 120F, 60psig.
With a flow of 35MMSCFD I calculated I would be sending liquids to the slop tank at a rate of 75 barrels per day. Does this seem reasonable?
Currently I am trying to size a VRU and would need this info to proceed.

Please give feedback so that I may learn where my thought process is good or bad.

Thank you.

RE: Composition of slop tank at proposed compressor station

The simulator result is most probably correct, and this is a reflection of what happens in theory. In actual practice, perfect light phase - heavy phase liquid fraction separation occurs only for clean fluids. In most other cases, with gunky corrosion inhibitors, suspended solids, and with emulsions caused by strong shear effects as liquids go through high pressure letdown valves, poor L-L phase separation effects can be a nightmare for plant operations. So your co worker may be telling you what actually happens in the field.

Liquid phase fraction separation is made all the more difficult by the inability of the interface LT to "find " the interface due to an emulsion band that would develop in the 3 phase slops drum in these cases. Using a bucket and weir type internals arrangement helps to reduce the mal effects of the interface LT, as would a double overweir design also.

Even if you use more complicated internals as suggested, to be cautious, you may still want to deliberately let some light phase condensate leak into the water phase exit line to reflect field experience at this slops drum. In Pro II, there is a feature to allow a desired light phase entrainment rate into the heavy phasein a 3 phase separator. This will then help to derive a gas rate for VRU design that is more inline with what your co workers would expect.

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


Resources

White Paper - Understanding Critical Specifications for Dynamic Metrology Applications
Different types of metrology have different critical specifications to consider when determining which actuator technology to use. This white paper goes into detail on the demands of dynamic metrology applications as they apply to the selection of precision linear motion control components and systems. In addition, the relevance of Moore's Law is examined in the context of the industry. Download Now
White Paper - Permanent Non-Welded and Cold Bent Piping Solutions
Commonly used welded piping connections come with skilled labor, validation, inspection, and long commissioning times, as well as the workplace hazards associated with welding. Non-welded permanent mechanically attached fittings offer a viable alternative to welded piping systems that greatly reduces the time to commission piping systems through reductions in many of the time-consuming steps required in welding. Download Now
White Paper - Take Mobile Hydraulic Systems to a New Level
The introduction of digital ecosystems connecting electronic control hardware and software to the Cloud is catalyzing a new era of mobile machine and equipment design innovation. This is enabling OEMs across industries to develop customized solutions that digitally integrate hydraulic and machine controls with the Internet of Things (IoT). Download Now
White Paper - The Evolving Landscape of Commercial Battery-Powered Trucks
What’s driving the evolving landscape of truck electrification? What are the barriers, motivators and strategies for accelerating the electric transition? What insights and resources are available for today’s design engineers working to achieve industry disruption and evolution? For answers to these and other pertinent questions, read this white paper. Download Now

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