Municipal waste disposal, pollution optimization and generation of green energy like electricity are the serious issue of the developed and developing cities throughout the world. With the growing population and digitalized lifestyle, the municipal waste is also increasing. Municipal waste now a day's includes paper, plastics, wrapping boxes etc. These contain high calorific value which is almost half of the high grade coal. Proper thermal treatment of these municipal wastes can be utilized to energy generation along with industrial and hospital steam supply. In this work we are proposing a thermo-geometric analysis to design a riserdowncomer circuit under a stipulated steam generation rate for a typical municipal waste fired boiler (MWFB). The boiler is running on the thermosyphon principle and powered by the municipal waste firing. A numerical model is developed focusing on the two phase thermosyphon which will solve the thermo-geometric design issue associated with the municipal waste fired boiler (MWFB). Appropriate heat transfer and pressure drop correlations have been employed in the model. The critical heat flux condition and tube burnout issue, complex two phase flow are considered and handled by homogeneous averaging concept in this work.