Analyzing temperature distribution in pyrolysis systems using an atomic model

Abstract

Pyrolysis is a complex energy conversion reaction due to the multiple stages of the process, the interaction of kinetics, mass and heat transfer and thermodynamics. The feedstock, temperature, heating rate, residence time, and reactor design are only a few factors that might impact the final product during the pyrolysis process. This study focuses on the temperature analysis of pyrolysis with sheep manure as feedstock, which includes reactor, pipes and condenser. The examination of the temperature distribution within a pyrolysis system can contribute to the preservation of product quality, the maintenance of heat balance, and the enhancement of energy efficiency. Based on the analysis, the degradation temperature of sheep manure is between 210–500 ℃. Consequently, it is crucial to control the reactor temperature at a desirable temperature that aligns with the degradation temperature of sheep manure. To ensure optimal condensation and maximize bio-oil yield, it is also necessary to control the condenser temperature. This study aims to determine the characteristics of temperature changes in pyrolysis systems using atomic models. The atomic model was built in OpenModelica using the Modelica language. The atomic model was validated with experiment, and it was found that there was a significant difference in reactor temperature. Complex processes occur in the reactor where pyrolysis occurs and various factors can impact the temperature of the reaction. The temperature in the multistage condenser gradually decreases by 1–3 ℃. In the principle of condensation, this temperature drop is considered less than optimal because the cooling fluid in the pyrolysis condensation system is air coolant, which is entirely reliant on ambient temperature. The accuracy of the atomic model is evaluated using error analysis and the mean absolute percentage error (MAPE). A value of 13.6% was calculated using the MAPE. The atomic model can be applied because this value is still within the tolerance range.