Really interesting idea, it could really speed up fermentation if you could brew in the pb, and then pressure transfer off into a corny or similar
You still need the time it takes for the beer to clear, I like 3 weeks minimum, so long as you have plenty of barrels - you are using one whilst other are clearing. I only brew 40 pints a week ( i told my gp I drink 28 units a week - as i like a couple of bottles of wine and a few whisky's the missus must be drinking a lot of it, either that or i have some leaks
) but with 5 barrels and 1 corny i am able to maintain a constant supply of 3 different beers all well cleared.
For my lager I still primary ferment in air locked tub, then give it 3 weeks in pressure barrel with 90g sugar, keeping the pressure at 5 psi ( they are old barrels it's plenty) .
I brim fill the corny with water and blow out with co2 so it is pretty free of o2. Then transfer the beer to the corny putting the pressure into the barrel up to 15psi (helps stop the disolved co2 being knocked out during transfer) which when equal in both vessels beer stops flowing. Then i connect the gas connections of both vessels together as my pb is higher than the corny gravity eventually does the rest whist maintaining nice amount of gas in the beer.
I do it because the dip tube of the corny is right at the bottom which i like as it leaves only about a tablespoon full of beer behind (a Yorkshireman through and through) but would be picking up sediment if all the secondary fermentation had been in the corny, plus the corny gets to travel around a bit so its nice to have it sediment free. Also it's nice that the corny is allways available for dispensing, stick it's insulating jacket on with half a dozen icepacks in and it gives lovely cold lager even outside in the sun when Mrs Bucket here is having one of her
candle sun lit soiree's.
When i can justify the cost, i will buy another corny they are brilliant and easy to clean take plenty of pressure and last forever, high resale value so when fed up of cleaning out kegs will probably work out no more expensive than plastics.. Saying that, to me the plastic barrels compliment them and will be sticking to both.