Boil-off rate in crogenic tanks
Boil-off rate in crogenic tanks
(OP)
Can anybody tell me what does "Boil-off rate is 0.25%" mean. doe sit mean that the vapor produced will have a volume of 0.25% of the total LNG capacity or is it the volume of the LNG that get vaporized. a quick respense is greatly appreciated





RE: Boil-off rate in crogenic tanks
The "Boil off rate" usually refers to the amount of liquid vaporized by heat leaking into the tank per unit time. So in your case o.25% of the liquid will be boiled off per unit time. Usually the time is per day, but your percentage is much lower than those shown by Air Liquide for their tanks so I think your unit of time might be hour.
Anyway it indicates that to maintain the same pressure in the tank you need to vent at least this amount of equivalent liquid or vapor. Less and you will build pressure, more will result in a drop in pressure in the tank, unless you have a vaporizer.
Regards
StoneCold
RE: Boil-off rate in crogenic tanks
RE: Boil-off rate in crogenic tanks
The heat leak can usually be calculated by taking the % boil-off (volumetric), then assuming pure methane with a heat of vaporization around 220 BTU/lb, and whatever the density of the methane is at tank conditions. With these you can calculate the BTU/hr
RE: Boil-off rate in crogenic tanks
RE: Boil-off rate in crogenic tanks
will it it fair to say that the heat of vaporization for pure methane under standard conditions (i.e. 60F and 1 atm) can be used for this calculation.
Again thank you everybody for their inputs. looking forward to hearing from you guys