×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• 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.

# Boil off gas pressure build-up

## Boil off gas pressure build-up

(OP)
There is an insulated container of 100 m3 capacity which is 95% full with LNG (MM 16.4 kg/kmole) at -160 degC, saturated and at near ambient pressure (~0.2 barg). The heat ingress to the container develops 0.3 vol%/day of boil-off gas, resulting in the pressure inside the container to increase over time.

How do I calculate the pressure build-up after 1 day, 2 days, after x days, etc. before it reaches the PSV set point of 10 barg? Assume that no LNG is transfered out of / into the container during this time.

Thank you!

### RE: Boil off gas pressure build-up

Student post / question?

For starters just use the ideal gas law, just remember to work in absolute pressure and absolute temperature. You can prob assume gass temp is close to -160. Volume of gas to vol of liquid use 600:1.

Let us know how it goes.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Boil off gas pressure build-up

You can model this easily on the Depressure routine in Hysis or Simsci - Pro II.

### RE: Boil off gas pressure build-up

this heat & mass balance can be solved by hand calculation or in Excel...
For fluid properties look in tables (as suggested by LittleInch) or use some process library or maybe Nist database...

### RE: Boil off gas pressure build-up

Yet another first time poster who vanishes into the ether.....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

#### 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.

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:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!