The invention (US patent application 14/093,431, the patent to be issued shortly) relates to heat engines and, more specifically, to positive displacement internal combustion engines, and is particularly concerned with very large rotary internal combustion engines fueled by solid particulate fuels like coal dust. The engines are primarly destined to drive electric current generators, and intended to replace large steam turbines bringing at least 50% overall efficiency typical for large Diesel engines (in comparison with ~40% overall efficiency of typical steam boiler-steam turbine assembly) to power generation industry, thus making the power generation industry substabtially more enviroment-friendly. The engine according to the instant invention has a body 1, and only one major moving part, namely an eccentric shaft 2 acted upon directly by combustion gases, with cylinders encompassing the shaft eccentrics, which are suitably sealed using primary 3 and secondary 41, 42 sealing elements; in particular, the engine comprises no elements executing reciprocating motion, and is naturally balanced. Moreover, also the gas forces acting upon the shaft can be balanced (only the driving moment of gas force remains unbalanced), which renders the shaft bearings almost load-free like in the case of turbines. Both these two last features render the engine capable of revolving very quickly. The engine also features self-cleaning capability, i.e. ability to eaisly expell unburned solid particulates. Thus the invention solves the problem of building very large internal combustion positive displacement engines capable of revolving with very large rotational speeds (e.g. 3000-3600 rev./min, like steam turbines) and developing very large outputs (2000 MW and more), as well as problems of fueling internal combustion engines by solid particulate fuels, and removing unburned solid residues from combustion chamber of internal combustion engine. The invention provides the optimal form for the two stroke rotary engine of unique simplicity, strength and compactness, and sealing as simple and robust as that of the ordinary piston engine.