Vibration mode of straw vibrating grate boilers has a comprehensive effect on the solid-phase combustion in the fuel bed and the homogeneous combustion in the freeboard

as well as on pollutant emissions. To improve boiler efficiency and reduce fuel consumption

this paper proposes optimization of vibration mode by means of the numerical simulation based on the developed multiple thermally thick particle (MTTP) grate combustion model. First

a model is built for the typical 130 t/h vibrating grate boiler

and issues like insufficient combustion of straw are reproduced by numerical simulation. Further

through numerical simulation

the basic reaction processes of layer combustion are clarified

the effects of vibration parameters in different combustion stages are revealed

and evolutions of CO

NOx and SO2 are analyzed in a grate vibration cycle. Finally

the optimization strategy in vibration mode is proposed and applied in an actual furnace

to evaluate the improvements in combustion efficiency and pollutant control. The results indicate that

in a bottom-ignited layer combustion mode

the residence time of fuel on the grate significantly influences the length of the ignition preparation zone at the front end

while the length of the flame propagation zone remains unchanged. With the time requirement for the ignition of fuel bed fulfilled

the application of a vibration mode with short intervals

high frequency

rapid ramp-up

and short duration contributes to coke block breaking and fuel burnout

and mitigates the adverse effects associated with concentrated pyrolysis and combustion. After applying the adjustment in vibration in an actual boiler

its steam production efficiency has been significantly improved

with substantial reductions in NOx and SO2 emissions. Optimization based on numerical simulation provides a new way to increase the profits of power generation and heat supply from straw combustion.