Towards clean palm oil processing: Integrated ammonia production from empty fruit bunch and palm oil effluent

Abstract

In this study, we design and evaluate a highly efficient energy system for performing an integrated conversion of empty fruit bunches (EFB) to H2 that is stored in the form of ammonia (NH3). The biomass undergoes processes that include supercritical water gasification (SCWG) for H2 production and H2 chemical storage using the Haber-Bosch process to produce NH3. Exergy recovery by heat integration is employed to increase the efficiency of the system. First, EFBs are gasified with steam in the SCWG process to produce H2-rich syngas and to completely remove the pre-drying requirement. Subsequently, a syngas chemical looping (SCL) process involving three reactors is used to produce H2 that is subsequently converted to NH3 by the Haber-Bosch process. Theoretically, the integrated process can achieve a high EFB-to-NH3 conversion efficiency that exceeds 15% with a H2 conversion efficiency of 76.2% and an overall maximum syngas-to-H2 conversion efficiency of 46.3% with 100% CO2 capture capability. Compared to traditional EFB conversion processes, this process can theoretically achieve higher efficiency, and it can improve waste utilization in palm oil processing plants by incorporating exergy recovery and heat integration into the system.