CRJ200 FLT CREW REPORTS FAN VIBRATION AT FL270 WHILE FLYING IN ICING CONDITIONS WITH ENGINE ANTI-ICE ON. VIBRATION EVENTUALLY SUBSIDES AT FL240.

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DURING THE CLB WE WENT THROUGH SEVERAL LAYERS OF CLOUDS AND FOLLOWED THE PROPER PROC FOR ANTI-ICE; IN FACT THE ANTI-ICE WAS TURNED ON WELL BEFORE THE DEFINITION OF 'ICING CONDITIONS.' STILL INTO THE CLB FROM FL250 TO CRUISE OF FL270; WE ENCOUNTERED ANOTHER LAYER OF ICING CONDITIONS. WING/COWL ANTI-ICE ON DUE TO ICE MESSAGE IT SEEMED LIKE LIGHT-MODERATE ICE FORMING ON THE WINDSHIELD WIPERS. AFTER 3-5 MINS THE R ENG VIB AMBER RING CAME UP WITH THE N1 VIB GOING FROM 3.3-3.5. I REQUESTED THAT THE FO DECLARE AN EMER. I TURNED THE AUTOPLT OFF; THEN ASKED THE FO TO HAVE THE FLT ATTENDANT BE SEATED AND PUT THE ACFT INTO A DSCNT TO FL240. I ASKED THE FO TO PERFORM THE QRH FOR AN N1 FAN VIB. AFTER LEVELING OFF AND OUT OF ICING CONDITIONS THE PROB STILL EXISTED. I REALIZED THE FO READ THE WRONG QRH PROC; N2 CORE. I PUT THE ACFT AUTOPLT ON IN ORDER TO RECTIFY THE SITUATION AND THEN READ THE RIGHT QRH PROC; N1 FAN VIB. IT TOOK THE ENG FROM 5-6 MINS TO CLR. I HAD THE FEELING THAT THE COWL ANTI-ICE ON THAT ENG WAS NOT WORKING CORRECTLY. ATC ASKED US IF WE WOULD LIKE TO DIVERT TO ZZZ AND I ASKED IF THEY COULD STAND BY. I CALLED DISPATCH AND ALSO SPOKE WITH MAINT. THE WX IN ZZZ HAD SEVERAL LAYERS OF VISIBLE MOISTURE. I RECEIVED THE WX FOR ZZZ1 AND ZZZ2 AND FLYING E WAS THE BEST OPTION. THE ENG INDICATIONS WERE ALL NORMAL; THEREFORE WE DECIDED TO CONTINUE EBOUND TO STAY CLR OF ICING CONDITIONS. A MAINT WRITE-UP WAS PUT IN THE LOGBOOK UPON ARR.