Towards the thermal utilisation of non-tyre rubbers – Macroscopic and chemical changes while approaching the process temperature

• Non-tyre rubbers may build sticky surfaces at the temperature of the fuel feeding path.
• The extensive fragmentation starts at about 240 °C.
• The release of volatile products occurs in two distinct temperature ranges.
• Most of the chlorine- and nitrogen-containing compounds are released below 400 °C.
• The duration of the complete volatile release is several minutes under FBC conditions.

This paper presents important changes in the basic fuel properties of non-tyre rubber wastes during heating from ambient to the temperature of the thermal conversion reactor. Experiments were carried out on both macroscopic and chemical processes occurring throughout the sample path. Special emphasis was put on the possible utilisation of non-tyre rubber wastes in Fluidised Bed Conversion units. The results show that some potential fuels studied may build sticky surfaces in the fuel feeding paths while all the samples undergo extensive fragmentation. Thermogravimetry/mass spectrometry experiments demonstrate that the volatile production occurs in two distinct temperature ranges characterised by the limits of about 150–350 °C and 350–550 °C. The gas chromatographic analysis shows that most of the chlorine- and nitrogen-containing compounds are formed in the first temperature range of pyrolysis and these products are released from the additives of the rubber samples. The duration of devolatilisation is 1.5–2.5 min under the normal fluidised bed combustion of 50 mm rubber particles. Considering the results achieved, the possible ways of practical applications is also formulated in this paper.