You've done the right thing by placing the eggs in their own tank.
You will need to keep a small airstone near the eggs to ensure they get some water circulation.
Keep the airstone going VERY slowly. This will replicate the fanning action of the parents, they they normally use to look after their eggs.
By the way, is their a reason you removed the parents? Were they eating the eggs?
I have bred Angels on a number of occassions, and although I've heard some of them will eat the eggs, mine never did. In fact they turned out to be excellent parents and looked after the young when they were free swimming.
I would definitely consider hatching some brine shrimp after your baby angels are free swimming (Usually about 5 days after they hatch). You don't need to feed then until they start to swim around and look for food.
Once they start to swim, try to given them a minimum of 2 times per day (between 3 to five feedings per day at regular intervals is even bettter and they will grow faster).
Also the babies can be quite delicate at this time, so small (10%) water changes every couple of days helps to keep the water healthy.
Some of the babies will survive on the powdered food, but you will lose quite a few due to starvation.
Congratulations of the breeding and please let us know how your new "family" is doing ..