Capacitor discharge time

Hello,
would any one remind me of how to calculate the discharge time of a capacitor? I am trying to integrate an AC to DC, the cap is right after the rectifier, I want to know if the load is so much, how big of a cap should I use to keep the voltage constant.
Examp:
24V AC, my load is 1Amp, how do I work out the cap size to keep the output at above 22V constant?

Thanks.

the formula is: c = [ ( I load x t ) / ripple ]

c = cap in uF
I = load current
t = time interval between charge pulses ( 0.0083 mS for full-wave rectified 60Hz )

ripple is allowed ripple in output ( about 2% is OK ) say 12V x 0.02 = 0.24v for RMS peak this would give 0.24 x 2.82, or 0.68V

this gives:

c= [ ( I load x 0.00830 ) /0.68 ]


hope this helps