Process simulation and environmental impact assessment of different cases in hydrothermal catalytic bio-jet fuel production

Considering the operation and environmental impact of HCJFP (hydrothermal catalytic jet fuel production) process system with corn stalk as raw material, it met the current demand for green energy and carbon neutralization. Therefore, this work aimed to establish an assessment system of available energy and environmental impact under the basic and optimization process through exergic analysis and life cycle assessment (LCA). The commercial simulation software (Aspen Plus for chemical production simulation and eBalance for LCA analysis) was used to model the production and optimization scheme of 2 t/day corn stalk HCJFP. Results showed that global warming was the main environmental impact of HCJFP, and gypsum produced in the process also needs attention. In the process of waste gas and residue combustion, different kinds of pollutants had a significant impact on the utilization of available energy and LCA results of the system, especially the direct combustion of lignin, which failed to be effectively utilized. Therefore, two lignin utilization methods were proposed for higher efficient energy utilization compared to the direct combustion of lignin in case 1. In case 2, lignin was gasified in high temperature by steam to obtain hydrogen, which was used in the hydrogenation process; Lignin in case 3 was depolymerized in liquid phase with hydrogen donor solvent ethanol, high temperature, and pressure to obtain hydrocarbon fuel. According to the optimization scheme and evaluation model, the result showed that although the additional lignin utilization unit increases the complexity of the process, the utilization of hydrogen production as a by-product in case 2 reduced the production cost and avoided the waste of high-quality available energy, while case 3 partially converted the carbon dioxide generated by combustion into carbon in liquid fuel, which was conducive to reducing the carbon emissions of the system.

Automated summary

This study aimed to establish an assessment system for the energy and environmental impact of hydrothermal catalytic jet fuel production (HCJFP) using corn stalk as raw material. Exergic analysis and life cycle assessment (LCA) were used to evaluate the basic and optimization processes. The results showed that global warming and gypsum production were the main environmental impacts of HCJFP. Different pollutants significantly affected the utilization of available energy and LCA results, particularly the direct combustion of lignin. Two lignin utilization methods were proposed for higher efficient energy utilization. The optimization scheme indicated that the utilization of hydrogen production as a by-product and the conversion of carbon dioxide into carbon in liquid fuel were beneficial for reducing the carbon emissions of the system.