Would you be taking any measures to increase surface area/exposure? Calculating an exact time would be pretty complicated but could offer guesses.
It depends on how much carbonation you want. If you max out you brite tank at 15 psi at 50 degrees you will have 2.3 volumes of carbonation. Most beers are carbed to 2.5-3 volumes. You should be able to carb it With the stone in less than 2 days. Just start at 1-2 psi and increase the psi 1 psi every 3-4 hours.
there is another trick brewers use if you need to carbonate quickly and dont mind wasting a little extra CO2... (or sometimes a LOT extra)
chill the beer to as cold as you can, and bubble CO2 thru the stone in the bottom of the tank. there is a bit of math that takes into account head pressure on the stone, depth of the stone, etc, but basically you vent CO2 out of the top of the tank after it bubbles up thru. this way you can keep bubbling from the bottom wihtout the pressure building at the top and slowing the bubble stream coming from the stone. more bubbles = more surface area = faster CO2 dissolving.
some people vent the head pressure in the tank to zero (ambient). while others use a spunding-type valve that just keeps a minimum differential pressure and vents off the excess. the latter method wastes slightly less gas, and, depending on the differential, can carbonate even quicker.
Interesting. I wonder how much effort it would be for a homebrewer to build a re-circulating system to re-capture the CO2 that comes out in the headspace and pump it back in.
Sorry to be a nay sayer, but i don't think this is going to happen...the cost and complexity would outweigh a lot of C02.
there is another trick brewers use if you need to carbonate quickly and dont mind wasting a little extra CO2... (or sometimes a LOT extra)
chill the beer to as cold as you can, and bubble CO2 thru the stone in the bottom of the tank. there is a bit of math that takes into account head pressure on the stone, depth of the stone, etc, but basically you vent CO2 out of the top of the tank after it bubbles up thru. this way you can keep bubbling from the bottom wihtout the pressure building at the top and slowing the bubble stream coming from the stone. more bubbles = more surface area = faster CO2 dissolving.
some people vent the head pressure in the tank to zero (ambient). while others use a spunding-type valve that just keeps a minimum differential pressure and vents off the excess. the latter method wastes slightly less gas, and, depending on the differential, can carbonate even quicker.
Sorry to be a nay sayer, but i don't think this is going to happen...the cost and complexity would outweigh a lot of C02.