A clog-resistant inlet structure for introducing a particulate solids-containing and/or solids-Forming gas stream to a gas processing system. The structure is composed of a gas-permeable wall enclosing a gas flow path, and an outer annular jacket circumscribing the gas-permeable wall to define an annular gas reservoir therebetween. The clog-resistant inlet structure is constructed, arranged, and operated so as to introduce a gas into the annular gas reservoir during the flow of the particulate solids-containing and/or solids-forming gas stream to a gas processing system through such inlet structure at a pressure sufficient to combat the deposition or formation of solids on the interior surface of the gas-permeable wall. The inlet structure may further optionally include a downstream annular section in which the wall surface bounding the gas stream is blanketed with a falling liquid film, to combat solids deposition or formation on the blanketed wall surface.