An apparatus and a method for achieving progressive reduction of flue gas is disclosed. Accordingly, an aspect of the present invention is to provide an apparatus comprising of an orifice chamber having an inlet pipe for receiving the flue gas, a flow region defined downstream of an exit of the inlet pipe and having at least a first section and a second section, and an outlet pipe to disperse a pressure reduced flue gas. The first section defined downstream of the inlet pipe has a flow developer means and at least one auxiliary orifice plate. The second section defined downstream of the first section has a plurality of orifice plates spaced apart along a flow length of the second section.