Radiative heat transfer in three-dimensional inhomogeneous, nongray and anisotropically scattering participating media was investigated by using REM2 method. The accuracy of the method was verified by benchmark comparisons against the solutions of Monte Carlo and YIX methods in the case of three-dimensional inhomogeneous media and in the case of three-dimensional media composed of nongray CO2 gas and carbon particles with strong anisotropically scattering. The ray effect and the influences of radiation element division and spectral discretization were examined. The present predictions of heat flux, flux divergence and emissive power were found to be in good agreement with those by Monte Carlo and YIX methods. As an example of an application of engineering interest, radiative heat transfer in a boiler model with non-isothermal, nongray, and anisotropically scattering media is numerically studied. The distributions of radiative heat flux and flux divergences in the boiler furnace are obtained. It is found that larger heat fluxes appear at the wall near the flame and larger heat flux divergences exist around the boundary of the flame. The effect of particle radiation is small in the region downstream the flame.