Abstract
The aerodynamics of fully turbulent jets supplied from rectangular slot-burners was modelled using the Reynolds Averaged Navier–Stokes (RANS) model. Three different turbulent models were considered, such as standard k-ε, RNG k-ε and Reynolds stress turbulence models. The recessed-type nozzle geometry was investigated to determine the effect of burner geometry on jet development. The slot-burner was based on physical models, which were designed to be representative of typical burner geometries found in tangentially-fired coal boilers. The study was validated against the physical models. The detailed flow field obtained from the simulations was used to explain the aerodynamic development of jets in such burners. It was found that the addition of a recess section to the nozzle geometry introduced significant changes to the flow due to complex pressure and mixing fields being set up inside the recess, which altered the jets once they exited into the open atmosphere.
Highlights
Combustion flames are found close to the nozzle area as combustion occurs in the main reaction zone in gas-fired and black coal-fired boilers [1,2,3,4,5]
The near-field aerodynamics are still important in entrainment and in confirming the jets spread in the centre of the reactor at the appropriate position and with adequate momentum to create the swirl required to stabilize the flame in the centre
The level of burning in the burner area is lower, since the aerodynamics is necessarily decoupled from the possessions of strong chemical processes and radiative heat transfer, leading to flame temperatures that vary the physical conditions of the flow [3]
Summary
Combustion flames are found close to the nozzle area as combustion occurs in the main reaction zone in gas-fired and black coal-fired boilers [1,2,3,4,5]. It is found that some burning happens just after the brown-coal burner jets This is due to the process of pyrolysis and devolatilization of the particles, though the behaviour of the turbulent characteristics is less important for combustion [6]. Stabilization in combustion in a tangentially-fired brown coal boiler [9,10,11,12] is accomplished by positioning the burner jets in the furnace walls, so as to induce a vortex in the central region of the boiler (Figure 1) in which the majority of combustion occurs. Burners located in a vertical plane, which commonly consists of a central or primary slot, injecting a Therefuel/air is significant between the jets. There is of significant separation slot-burner used in tangentially-fired furnaces by varying the jet velocity ratio in the presence between the jets.
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