Pyrolysis is often a first step in the incineration process, especially of the hazardous waste. One of examples of such installation is presented in the paper cylindrical pyrolysis chamber, applied in the incineration plant for medical waste. In the chamber the carbonisation of the waste takes place and the products, such as volatiles and carbonisate are burned in the cylindrical combustion chamber surrounding the pyrolysis chamber. Such configuration provides the heat transport from the flue gases to the carbonising material. To model the processes taking place in the pyrolysis chamber the energy and mass balance equations have been defined. The system of equations was solved for the exemplary material, such as wood sawdust, of a known thermophysical properties. Results are presented as diagrams of various parameters inside the two-dimension domain of the chamber.

Widely used CFD codes enable modelling of PC boilers operation. One of the areas where these numerical simulations are especially promising is predicting deposition on heat transfer surfaces, mostly superheaters. The basic goal of all simulations is to determine trajectories of ash particles in the vicinity of superheater tubes. It results in finding where on the surface the tube will be hit by particles, and what diameter and mass flow of the particles are. This paper presents results of CFD simulations for a single tube and a bundle of in-line tubes as well. It has been shown that available parameters like ash particle density, shape factor, reflection coefficients affect the trajectories in a different way. All the simulations were carried out with Fluent code of Ansys software.

The authors present a numerical study of a start-up of a boiler with a thick-walled element subjected to thermomechanical loading. The significance of calculations of real heat transfer coefficients has been demonstrated. Fluid dynamics, mechanical transient thermal and static structural calculations have been conducted in both separate and coupled modes. Strain-stress analyses prove that the effect of the heat transfer coefficient changing in time and place in comparison with a constant one as recommended by standards is the key factor of fatigue calculations.