Broken Shimano FD-R453
Looks like The FD-R453 is a non-series (i.e. it does not get the 'Tiagra', '105' etc label) component. I believe it's roughly equivalent to Tiagra in quality though. 

Any Shimano 3x9 front derailleur is going to work, Tiagra 4500 series - which is not current but is probably available, Sora 3400 or 3500 series also. The Sora FD-3030-B looks right.