The concept of node function zone has been introduced into main combustion zone of the combustion system for coal-fired boilers.By using technologies of thick-and-thin pulverized coal burners as well as the wall-sticking air

the primary air injecting nozzles of two neighbouring levels have been designed

the injecting nozzles in lower level are thick burner at upper part and thin burner at lower part

whereas the injecting nozzles in upper level are thin burner at upper part and thick burner at lower part;the secondary air between two levels of primary air injecting nozzles is biased with primary air at a small angle

at the same time

the wall-sticking air is arranged at two sides of the central secondary air.By using the CFD numerical simulation software

the distribution of velocity field

temperature field

as well as O2 and CO concentration field over node function zone in the combustion process of pulverized coal has been calculated

and many functions

such as ignition and combustion stabilization

low emission of NO x

prevention of slagging and high-temperature corrosion etc.

being arranged to air compartments for pulverized coal and air.Results of application show that the utilization of low NO x combustion system in node function zone can make the concentration of NO x emission to be effectively reduced

at the same time

the combustible content in fly ash hasn ’ t substantially increased

and the slagging phenomenon being remarkablly improved.