Numerical Simulation Of Semi-coke Reburning In The Grate-fired Furnace

Domestic operation of the grate-fired furnace is generally low thermal efficiency, highcoal consumption, as one product of the Layer combustion boiler, semi-coke is of a highburning value, it can be used to reburn by send into the furnace, this can be a new method ofenergy consumption reducing during the furnace operation.On the basis of reduction of existing layer combustion boiler’s simulation results andproject data, The thesis put forward a new method to describe fire grate combustion, that treatthe wind speed and air volume parameters as independent controllable variables respectively,by writing the corresponding user-defined functions, finally the simulation results should becompared with existing simulation results, engineering data repeatedly. The result indicatesthat the simulation method can achieve high accuracy, the results can provide the effectivereference for engineering operation.This paper take FLUENT as the simulation platform, combining self-programming, setSZL20-1.57-AII boiler as the example, research the feasibility of semi-coke’s reburningproposal, as well as the necessary reburning conditions for the stability of primary combustion.The results shows that: when feed grain is of1mm to4mm size and below2kg/s flow, theprimary combustion of the combustion chamber basic not affected by reburning, with a goodenergy saving effect. On the premise of guarantee of the stability of the primary burning,research on the major wind speed, air volume and excess air coefficient which may influencecarbocoal combustion efficiency, the result shows that: when the major air volume in theposition of a2.9m~4.0m distance to furnace door, the feeding and reburning get the highestefficiency; When air chamber excessive coefficient α is between1.5and1.6, the reburningefficiency is the largest, can amount to68.3%; When the major wind speed after the5.1mdistance point to the stoker, furnace’s mainstream area will form gas phase vortex of largescale and high thermal efficiency, which can effectively improve burnout rate, it can be ashigh as77.6%; This paper also compare the fore-send and back-send type boiler chamber, andthe results show that the fore-send is of high efficiency, good burning stability, etc prominentadvantages, the fore-send boiler chamber should be the first chioce in a reburning plan.