5 replies to this topic

[rishirga]

Hi all

 

I am new to this forum.

 

I want to calculate LNG buffer tank cooling down rate and time before to start LNG transfer into the tank. Cooling down temp need to set up -130.C AND I was told that total cooling down time will vary from 10-12 hrs. Any suggestions will be highly appreciable.

 

Regards

 

Rishi

 

 

Edited by rishirga, 05 October 2015 - 12:47 AM.

[Bobby Strain]

And, why do you need to do this?

 

Bobby

[rishirga]

Hi Bobby

 

I need to calculate cooling down rate per hour (mean how much temp will reduce in a hour)  along with required Qty of LNG for cooling down before to start transfer LNG into LNG carrier. Before to start loading operation, LNG buffer tank need to cool down through LNG spray which might take 10-12 hr or less.

 

Thanks

 

Rishi

[rishirga]

Hello All

 

I did some kind of calculations for time required to cool down the LNG tank before to start loading process for LNG carrier.

 

Attached is calculation sheet. Normal cooling down time is recommended 12-15 hr depends on site conditions, however my calculation results are showing more time and I am bit confuse whether I am on right track or not.

 

Your comments are highly appreciable.

 

Thanks

 

Rish

Attached Files

•  LNG Cool down-1.xlsx   12.45KB   622 downloads

[breizh]

Hi,

 

At first :

Something is weird in your calculation : Heat transfer coefficient .

Probably you should search (engine)  in this forum similar calculation performed on vertical tank .

Good luck.

Breizh

Edited by breizh, 05 October 2015 - 02:16 AM.

[rishirga]

Hi Breizh;

 

Thank you for your comment and suggestions. You time is highly appreciable indeed.

 

There will be a lot of factors coming into play. Based on filed operations what I have seen that there should not a drop of 10 c per hour, so calculation supposed to based on dT= 1 hr. But unable to set up the calculations.

 

After, I suppose to find, how much liquid LNG I suppose to pump into tank to extract the heat because liquid LNG will first absorb the heat and evaporate to gas without change in temp means latent heat of vaporization then further this evaporated vapor will further absorb hear and reach certain temp.

 

I do have this process in mind which works logically at field. The calculation which you were referring through search engine on this forum might not the same which I am trying to set up.

 

Your further suggestions are most welcome.

 

rish