Mixing device and flue gas channel provided therewith

Abstract: Mixing device for mixing of a first and second gas stream comprising within a housing at least one deflection body causing the gas streams to be radially deflected within the housing; and a nozzle device for introduction of the second gas stream, arranged rotational symmetric to axis of the housing.

Description: The present invention relates to the mixing of fluida and in particular to a mixing device with a deflection body for the mixing of two fluid streams. It has now been found that when deflecting a gas-stream of different gases the gases are mixed thoroughly, in particular radial diffusers provide evenly mixing of gas streams as described in DK Patent No. 169,823 and PCT/DK/9500200. Accordingly, this invention provides a mixing device for mixing of a first and second gas stream comprising within a housing 2 at least two deflection bodies arranged in series along the longitudinal axis 10 of the housing 2, the deflection bodies being formed as radial diffuser elements 4, 6, 8 with a curved guide baffle 14a, 14b, 14c and a juxtaposed curved stagnation baffle 16a, 16b, 16c, the curved guide baffle 14a, 14b, 14c being centrally connected to a cylindrical gas inlet end 12a, 12b, 12c for the entrance of the gas stream, and being concave in the gas flow direction, the cylindrical inlet end 12a of the curved guide baffle of the first diffuser element 4 being connected to the inlet 22 of the housing, the curved stagnation baffle 16a of the first diffuser element 4 having a nozzle device 26 arranged centrally rotationally symmetrical to the axis 10 of the housing 2 for the entrance of the second gas stream 24 each curved stagnation baffle 16a, 16b, 16c being convex in the gas flow direction and juxtaposed the curved guide baffle 14a, 14b, 14c to form a conduit 28 between the two baffles allowing for radial transfer of the gas streams to the outlet ends 18a, 18b, 18c, the mixing action of the device taking place by alternative volume constrictions and expansions on sequential transfer through each successive radial diffuser element. The mixing device according to the invention is in particular useful when installed in flue or waste gas channels provided with a catalytic compartment for the treatment of off-gases, wherein a reactant gas or a spray of reactive particles in liquid or solid phase is admixed with the off-gas for the catalytic treatment of the gas. In those applications the combined silencing and mixing effect of the mixing device advantageously reduces the overall dimensions of the channels and pressure drop of the gas, when compared to channels with separate silencing and mixing equipment. Accordingly, the invention further includes an off-gas channel provided with one or more catalyst beds for the catalytic treatment of off-gas in presence of a reactant gas, wherein the off-gas channel further comprises a mixing device of the above described type for the silencing and mixing of the off-gas and the reactant gas prior to introduction into the catalyst bed. In the following description a specific embodiment of the invention is described in further detail with reference to the drawing in which the sole Figure shows a mixing device with radial diffuser elements arranged in series. The mixing device comprises within cylindrical housing 2 three radial diffuser elements 4, 6, 8 arranged in series along axis 10 within housing 2. Radial diffuser elements 4, 6, 8 consist each of a cylindrical inlet end 12a, 12b and 12c, respectively, connected to curved guide baffle 14a, 14b, 14c and a curved stagnation baffle 16a, 16b, 16c, which causes partial flow stagnation of a gas stream and leads the gas stream radially to outlet ends 18a, 18b and 18c as indicated by arrows. An incoming off-gas stream 20 is introduced in the mixing device through inlet 22 in housing 2 and passed to inlet 12a of the first radial diffuser 4. Prior to radial diffusion of the gas stream the stream is admixed with a reactant gas from tube 24. Reactant gas 24 is introduced into gas stream 20 through nozzle 26 arranged centrally on stagnation baffle 14a. The mixed gas stream is then passed radially through conduct 28 between guide baffle 14a and stagnation baffle 16a to outlet ends 18a. The mixed gas stream is further sequentially introduced into diffuser elements 6 and 8. By passage through the above described mixing device, the reactant gas is mixed thoroughly with the off-gas stream and withdrawn as a homogeneous gas stream at outlet end 32 of the mixing device.

Claims: Mixing device for mixing of a first and second gas stream comprising within a housing (2) at least two deflection bodies arranged in series along the longitudinal axis (10) of the housing (2), the deflection bodies being formed as radial diffuser elements (4), (6), (8) with a curved guide baffle (14a), (14b), (14c) and a juxtaposed curved stagnation baffle (16a), (16b), (16c), the curved guide baffle (14a), (14b), (14c) being centrally connected to a cylindrical gas inlet end (12a), (12b), (12c) for the entrance of the gas stream, and being concave in the gas flow direction, the cylindrical inlet end (12a) of the curved guide baffle of the first diffuser element (4) being connected to the inlet (22) of the housing, the curved stagnation baffle (16a) of the first diffuser element (4) having a nozzle device (26) arranged centrally rotationally symmetrical to the axis (10) of the housing (2) for the entrance of the second gas stream (24) each curved stagnation baffle (16a), (16b), (16c) being convex in the gas flow direction and juxtaposed the curved guide baffle (14a), (14b), (14c) to form a conduit (28) between the two baffles allowing for radial transfer of the gas streams to the outlet ends (18a), (18b), (18c), the mixing action of the device taking place by alternative volume constrictions and expansions on sequential transfer through each successive radial diffuser element. Mixing device according to claim 1, wherein the housing is provided within a section of an off-gas channel. Off-gas channel for the catalytic treatment of an off-gas being provided with a mixing device according to claims 1 and 2.

Inventors: SONDERGAARD KRISTIAN, SONDERGAARD, KRISTIAN
Applicants: TOPSOE HALDOR AS, HALDOR TOPSOE A/S
Application year: 1998
Main classification: B01F5
IPC codes: F01N3, F01N1, B01F5, B01F3