1 reply to this topic

[lee1706]

Dear All,
I am trying to calculate LNG boil off rate in the LNG Carrier.
I have found several articles which used ASPEN HYSYS Dynamic for LNG boil off rate calculations.

I am trying to simulate with following condition as stated article "Minimizing Boil-Off Losses in Liquefied Natural Gas Transportation"
- Tank Type : Sphere
- Volume : 36,250m3
- Tank filling : 98%
- Overall U : 0.6 kJ/h·m2 · °C
- Composition : 90% methane and 10% ethane
- Ambient Temp. : 25 °C
- Tank Temp. and Pressure : -163°C, 101.3kPa

But I cannot have have similar value to the value on "Minimizing Boil-Off Losses in Liquefied Natural Gas Transportation"

I do not know why.

I am wondering whether method I tried is correct.
First try, I input overall U, Ambient Temperature in Rating ==> Heat Loss ==> Simple.

 

Second try, I input energy duty in design Tab ==> Parameters. I calculated dUTY(Heat Ingress) by multying Overall heat transfer area(5297m2), Overall U (0.6 kJ/h·m2 · °C), Delta T(188).

Anyone please let me know which of the above method is correct?

Anyway the result from both method was not matched with value shown on article.

I attach both simulation files (hsc file zip.). And attach article I referred. I made red mark on the article(4,5,7,8 page).

Please shed me light.

Edited by lee1706, 08 February 2018 - 10:50 PM.

[serra]

you may test your results with a different method,

there are  papers discussing how to estimate boil-off without a simulator...

see for example

https://hrcak.srce.hr/file/161548

I have adopted a similar procedure with Excel solving directly VLE, Energy balance (H) and  fluid properties with Prode and GERG 2008 model,

you could follow a similar path with Aspen Hysys...