Exergy analysis of a pilot-scale reactor using wood chips

A pilot size reactor has been tested to examine the suitability of the design for effective gas generation. The qualitative assessment of a reactor is considered to be one of the selection criteria for the thermochemical conversion. The pyrolysis reactor is subjected to operate for the temperature histories of 32–400 °C and 33–600 °C, respectively. The chemical exergy and the thermal efficiency are calculated for both operating ranges. The thermal efficiency of the reactor is found to be 46.32%; whereas the chemical exergy of the raw gas is 75.77% while pyrolysing at 600 °C, which is relatively 17% higher than that obtained at 400 °C. The additional burden on the thermal system due to the moisture has reduced the thermal efficiency of the reactor by 5.85% at 600 °C, whereas it is 6.22% for carrying out thermal decomposition at 400 °C. The gas yield for the given reactor is decreased by 0.77% while operating at 400 °C, whereas the char yield is increased by 6.73%. The proposed design is more efficient for higher temperature regimes and for dried biomass. The lumped system analysis is adopted to determine the loss for the transient condition. The heat transfer in the transient condition is measured for the fixed bed of biomass by the Biot and the Fourier numbers. The external heat transfer controls the overall rate of reaction. The intraparticle temperature is homogenous throughout the process though it may depend on the external heat condition. Furthermore, the various losses encountered during pyrolysis make the system energy-intensive. The objective of this work is to provide a clean generation of energy, which can be attained by improving exergetic content of the reactor.