LP gas vaporization rates
LP gas vaporization rates
(OP)
I have three 1,000 gallon LP tanks that cannot supply my 1.2 million BTU/HR load demand under 0 to -10 degree F conditions. It is my intent to add as many 1,000 gallon tanks as needed to ensure adequate gas supply. The tanks will be manifolded with two-stage regulation. My only reference states that one half-full 1,000 gallon tank will supply an intermittent withdrawal rate of 525,000 BTU/HR if there is no tank frosting, and that this value should be reduced to 1/4 the intermittent rate for continuous loading. My questions are, 1) how do I evaluate tank frosting, 2) what constitutes continuous loading, and 3) how do I evaluate the tank level (fullness)?





RE: LP gas vaporization rates
RE: LP gas vaporization rates
Continuous would, in my opinion, be LP requirement for more than a short period of time. For a few minutes, you could pull quite a higher rate from the tank but for longer periods, you'd want to use the lower rating (if the LP load was lasted for 1/2 an hour, I'd say that was a 'continuous' load).
The problem is that you are not gaining enough ambient heat to vaporize the LP gas so you can draw it off. 1.2 MMBTU/hr works about to about 60 lbs/hr. To vaporize that, you'd need about 3.2 kW of heat entering your tank(s). You could try putting heat tape on the bottom part of the tank with an inch of insulation and using that heat to vaporize the LP you need. It's a fair chunk of heat tape I realize since this stuff is usually rated for a few watts per foot but you can get higher outputs. One thing is you want to make sure you have a relief valve on the tanks (I'm pretty sure you do and this isn't enough heat to overload them).
For telling the level in the tank, I've heard of a tape you put on your barbeque tank. When you pour hot water on it, the portion on the metal above the liquid warms up more than the metal below the liquid level and you got a colour change. You could check with your LP supplier for more information.
RE: LP gas vaporization rates
I suggest to talk to a local LPG loading station designer for the details. They can design and provide all the required materials.
I hope that this helps you.
Ibrahim
RE: LP gas vaporization rates
RE: LP gas vaporization rates
But this user is talking about roughly 60 lb/hr of LP. Electric trace heating of the tank is going to be less expensive and much less complicated to maintain than an pump and vaporizer system. At the end of the day, it's just so many BTUs/hr to vaporize the LP, the question is how to get that heat into the liquid.