Air carrier Captain reported experiencing severe turbulence on approach to DEN.

Narrative

On the initial approach phase into DEN; we were vectored to fly a visual approach to 16L. The vectors we were given by ATC where quite tight to the FAF. At that point we were experiencing moderate turbulence; and we were having a hard time slowing down as the speed was fluctuating 20kts up and down. We requested additional vectors northbound as I anticipated not being able to be configured and stable in accordance with the FOM stabilized approach criteria. On the turn to intercept the localizer 16L we started experiencing heavier turbulence progressively getting worse second by second. The airplane got into a 30 degree right bank and the autopilot automatically disconnected. There was constant abrupt changes in attitude with very high speed fluctuations. At this point I was hand flying and as soon as I had the aircraft stabilized I re-engaged the autopilot. The severe turbulence event lasted about 15 seconds. Subsequently we configured the aircraft for landing; and landed successfully. No aircraft limitations were exceeded. The aircraft did not sustain any structural damage. No injuries on board.