Technical and Economic Analysis for Production of Bio- ammonia from African Palm Rachis

Abstract

The 95% of ammonia destined for fertilizer production via Haber-Bosch process comes from natural gas. This process is preceded by a series of stages, in which methane available in natural gas is reformed to syngas (a gas mixture consisting of H2, CO2, CO, CH4 and H2S). The stage of syngas production represents a bottleneck from the economic point of view. The natural gas availability and its commercial cost imply a high commercial price on fertilizer which in turn increases the cost per hectare of crop. Currently, gasification technology has caught attention as a waste treatment technology due to its capacity to transform large volumes of biomass into syngas with low retention time. Therefore, this study aimed to evaluate techno-economically the bio- ammonia production from syngas obtained by gasification of African palm Rachis. The study was conducted by process simulation using Aspen Tech software. The process was simulated from the collection of the raw material to conversion of synthesis gas into ammonia. The simulation comprises a pretreatment stage to obtain an optimum particle size for biomass, a stage of gasification to convert Palm rachis into Syngas, a stage of heat recovery for steam production, a gas shift (WGS) reactor to increase the concentration of hydrogen into syngas, an acid gas remover unit (AGR) to avoid poisoning of catalysts; and the final stage of Bio ammonia synthesis; this simulation was validated based on data reported in the literature. The technical analysis measured the complexity of the new process in terms of equipment and the efficiency of the proposed operations. On the other hand, economic analysis evaluated the profitability to adapt the process to the biomass. According to results, 1,630,000 metric tonnes (Mt) of palm Rachis per year produced a syngas with a concentration hydrogen of 99% which yielded 35,755 Mt yearly of Bio ammonia. It could be inferred that highest reactor conversion was 20% at a temperature of 360°C and 250 bar pressure. It was observed that the return of investment (ROI) of 13.2% was higher than the discount rate of 12% which it demonstrates the economic viability of the project. However, The ROI value was high sensitive to the cost and availability of raw materials.