Exergy analysis of propane dehydrogenation in a fluidized bed reactor: Experiment and MP-PIC simulation

Exergy can be used to evaluate energy utilization in chemical industry. Although the analysis of the energy consumption in the propane dehydrogenation (PDH) process is of great importance, there is hardly any study of energy or exergy analysis on this topic so far. Thus, the present study focusses on exergy analysis of the PDH process in a fluidized bed reactor (FBR) with both experimental and numerical methods. It is found that the operating temperature and weight hourly space velocity (WHSV) have a great influence on the exergy efficiency of each gas component and the total exergy efficiency. As the temperature increases from 830 K to 890 K, the conversion of propane increases and the total exergy efficiency of product gases increases from 99.06% to 99.66%. As the WHSV increases from 0.40 h(-1) to 1.00h(-1), the conversion of propane decreases and the total exergy efficiency of products gases decreases from 99.38% to 98.88%. Also, numerical predictions based on Multi-Phase Particle-in-Cell (MP-PIC) methodology for the PDH fluidized bed reactor are found to be in a very good agreement with experimental data. Based on the numerical predictions of the flow field, temperature field and gas species concentration distributions, detailed distributions of chemical and physical exergies and total exergy in the fluidized bed reactor are quantified. This has made possible to examine the effects of operating conditions on the exergy efficiency and to better understand physical and chemical phenomena occurring in the FBR. Moreover, the quantitative exergy analysis and exergy distributions in the FBR makes it possible to confidently decide on the right operating conditions and guide efforts to reduce sources of inefficiency in the existing PDH designs and evaluate their economics.