Intensified chemical looping reforming processes with in-situ CO2 capture for high purity H2 production from non-fuel grade bioethanol

Abstract

This work presents the design and optimization of two intensified and eco-friendly schemes for high purity H2 production from non-fuel grade/undistiled bioethanol through detailed thermodynamic investigation using Aspen plus models. Both of them are chemical looping combustion (CLC) integrated processes; namely, sorption enhanced steam reforming (CLC-SESR) and sorption enhanced chemical looping reforming (CLC-SECLR). Further, the heat and power demand of these processes are met by integrating with heat recovery and steam generation, and power generation sections, thus making them energy-wise self-sustainable. Steady-state Aspen Plus models have been developed for both the schemes, and the processes are investigated thermodynamically to determine the optimal operating parameters through sequential parametric sensitivity analysis. The results demonstrated the efficacy of the proposed CLC-SESR and CLC-SECLR schemes in facilitating low temperature reforming of partially distilled bioethanol of 14 mole % (34.5% by vol.) concentration at 550 °C and 500 °C, respectively resulting in optimal H2 yield (H2Yield) of 97.38% and 82.45%, H2 purity (yH2) of 99.15% and 99.71 %, energy efficiency (η) of 39.47% and 37.30% along with CO2 capture efficiency (CO2Capture) of 99.13% and 99.58%, respectively. Further, reforming of undistilled bioethanol 5 mol% (14.6% by vol.) obtained directly from fermentation step, resulted in improved H2Yield, yH2 and CO2Capture of 99.92%, 99.63%, and 99.48% respectively for CLC-SESR and 83.31%, 99.91% and 99.71% respectively for CLC-SECLR, at the expense of slight decrease in η by ≈ 3% in both schemes. These results on comparison with the results of conventional steam reforming and chemical looping reforming with carbon capture demonstrate the outperformance of proposed schemes in terms of achieving more than 99% H2Yield, yH2 and CO2Capture at almost the same efficiency as of the conventional reforming schemes.