Importing hotwind to the direct-discharged chimney of flue gas desulphurization(FGD)

in which secondary dehydration device is installed

could lower the outlet moisture content and solve the problem of chimney rain effectively.In order to examine the influence of hotwind on the flow characteristics and optimize the structure of the chimney dehydration device to match the dehydration capacity and running resistance

discrete phase model

RNG k-ε double-equation turbulence model and component transport model based on calculation fluid dynamics (CFD)were adopted to build a hydrodynamic model to describe the flow field inside the chimney.The variation of temperature

velocity

pressure and moisture content in the chimney with and without hotwind and the optimal angle of blade of the rotating-stream tray were obtained by the numerical simulation.With hotwind added

the outlet temperature rises 3 K

outlet velocity is increased 0.6 m·s-1

outlet pressure is decreased 55 Pa

outlet moisture content is reduced 29 mg·m-3

and the optimal angle of blade is 45°.Compared with the angle of 42° in applications

the optimal angle makes the running resistance decrease 108 Pa with negligible increase in moisture content. The simulation results are in the range for practical use

verifying the rationality and feasibility of the simulation.The simulation provides theoretical bases for optimizing the internal structure of chimney and directing the sample locations in the project.