Abstract An experimental test of built-in combined cyclone used by industrial CFB boilers was conducted on a cold test rig.Discussed in this paper are some of the main factors influencing the efficiency of cyclone and the optimum structure of the cyclone obtained from the orthogonal test.As an integrated part of the waterwall

this cyclone has a simple structure

small volume and higher operational reliability.It is very suitable to the medium and small industrial CFB boilers that burn low-grade fuels.With such a built-in combined cyclone

CFB boiler is able to realize cyclic burning of coarse particles while finishing the burnout of combustible gas.