So, let's do some maths:
- Q's CD is 4s
- W's CD is 14s --> you need 3 refunds at least (and you have 2 seconds left to wait, minus the time you took to cast the 3 spells)
- E's CD is 7s --> you need 2 refunds
You can get the 3 refunds for W by doing : W-Q-E-Q-W- and loop.
Also, I never played Ryze, but theoretically, you can also use your R somewhere in your combo to get another refund, if you are not quite exactly at the right amount of refund.
And I did my maths at 0% CDR. If you are above 0% CDR, you still need the same amount of refunds (because your Q refunds less, but your other CDs are also shorter, so it cancels out), but the 2 final seconds after 3 refunds for W are not exactly 2 seconds.
Then, you'll need a real Ryze player advice for the subtleties such as: with which spells should you begin your comboes (I'm pretty sure there are some variations according to the circumstances), when you should use your R exactly, etc. I simply made basic calculations and theory crafting.