3 replies to this topic

[KeJoSa2010]

Hello,

 

I found what I feel is an issue with Aspen Flare Analyzer. Starting in v7.3 Aspen added the ability for users to specify gauge pressures into the program. I noticed that for some reason whenever I would specify an atmospheric pressure in absolute units and then change over to gauge units I would see a negative backpressure at the flare tip. Apparently the atmospheric pressure used for the gauge pressure calcs in the Flare System Analyzer is hard coded as 14.696 psia. I spoke with Aspentech about this issue and I got the following response.

 

"The definition of atmospheric pressure is fixed for gauge pressure calculation. There is no option to change it in Flarenet. What you input under Options is the outlet pressure. If you simulate a pipe network, which has a different outlet pressure than 1 atm, you will specify that specific outlet pressure in this field.

As Flarenet is mainly for flare system, the name of the field is given “Atmospheric pressure” instead of “Downstream pressure” or “Outlet Pressure”.

So, when the actual atmospheric pressure is less than the hard coded atmospheric pressure, then the gauge pressure will be negative at the flare tip.

If you have your input psia data based on a different atmospheric pressure definition, you need to convert them by using standard atmospheric pressure definition."

 

Anyway, I advised them that this is an issue that should be fixed as it may be a source of confusion. I think when users enter an atmospheric pressure they are expecting that pressure to be used in gauge pressure calcs.

 

Also, after looking into this issue further I understand that there are many issues users are having with version 7.3 and above.  I have heard that some people are sticking with v7.2 unti Aspen can fix some of the issues.  I am hoping someone can give me some insight into some of the issues that are associated with v7.3+...I have been using v8.0 for some time now and am starting to worry that there are issues I am not aware of.

 

Thanks

Edited by KeJoSa2010, 16 July 2013 - 03:36 PM.

[Alexsandres]

KeJoSa2010,

 

I've faced similar problem when simulating V7.3. Mass flow (in kg/hr or lb/hr) is another issue. It was okay when I run with default unit, but it became weird when I changed into another unit, and calculation result became unacceptable.

 

I still prefer V7.2.

[OffshoreProcessEngineer]

Another problem I came across with Aspen Flare Analyzer 7.3 was - I am not able to copy and paste the mole fractions of the components from HYSYS or any other spreadsheets which I used to do in previous versions of FlareNet like Ver.7.0.

[Propacket]

Same terrible problem with me. It has made me highly doubtful about the software.