Apparatus and method for introducing a first fluid into the flow path of a second fluid and use of such an apparatus

An apparatus for mixing a first fluid into a flow path of a second fluid, said apparatus comprising:

• a chamber, which encloses the flow path and exhibits a first inlet for receiving the second fluid, a second inlet arranged downstream of the first inlet for receiving the first fluid, as well as an outlet arranged downstream of the second inlet for discharging a mixture of the first fluid and the second fluid, said flow path extending from the first inlet to the outlet and said second inlet opening into the flow path, a throttle body, which is pivotally arranged inside the chamber for controlling the flow area of the flow path;
• and pivoting means, for pivoting the throttle body for said controlling of the flow area, the pivoting means being adapted to pivot the throttle body, so that the flow area decreases with a decreasing flow rate of the second fluid and increases with an increasing flow rate of the second fluid in order to maintain a flow velocity of the second fluid at the second inlet within a predetermined range, wherein the throttle body comprises a flap that has a first end that is pivotally arranged at the chamber and a second end that is free, the free end being directly adjacent the second inlet so that the flap maintains the flow rate of the second fluid at the second inlet in a desired range.