Re: Can this puzzle be solved?
Well, the first thing that strikes me is: will the PCs know what the goal and the rules are? The angle of lighting the brazier is not something that most players would think of when lighting one, so that might make it harder for them to figure it out, unless you're specifically asking them what angle they're lighting it from. Also, I'd strongly suggest having the goal noted somewhere, even if it's in riddle form, just to make sure they know that they're supposed to light all of the brazers.
The second thing I thought of is: how long will this take to solve? What I'd do is work out how many moves are needed to solve the puzzle, if you do it perfectly. Then estimate how many moves the players are likely to actually take (you know your group, so you'll have a better guess on this number than I will). Then multiply it by how many minutes they're likely to argue over each move. If you end up with more than an hour, I'd look into simplifying the puzzle, as you don't want your players to get too bogged down in it, and in my experience an hour trying to solve a puzzle is really frustrating.