kw-sst model is used. steady RANS case, 3D model, mesh has been validated.

First cold flow without particles is converged. 

Then two type of particles are injected;  DPM iteration interval 1000 still does not work.

if just injecting coal particles, cold flow with particle will converge.

biomass particle's density is half of coal particle's density.

I will try to only inject biomass particles to test whether it converges.

converged cold flow without particle, as expected

diverged cold flow with two types of particles,