In princip the real funnel is by-passed as the exhaust is re-directed from the old existing piping system to the "old funnel" through the scrubber system ,in this case beside the old funnel. How good a scrubber system really works I can,t tell. Some say it is good , other say it is problem laden. Can,t judge it as I never had one on a ship where I was.

Very confusion !!!

From smoke side - scrubber funnel, from no no gas flow- original funnel