Thermodynamic analysis of a novel biomass polygeneration system for ammonia synthesis and power generation using Allam power cycle

The massive utilization of fossil energy in power generation section and chemical production industry causes serious environmental pollution and global warming issues. The bioenergy utilization is considered to be a feasible approach in the short term to meet the climate goals. A novel biomass based polygeneration system for power generation and ammonia synthesis was proposed in this study. The negative CO2 emission is achieved by incorporating Allam power cycle with internal carbon capture. The pressure swing adsorption (PSA) technology is adopted to separate the hydrogen for ammonia synthesis, and the remaining syngas is burned with pure oxygen in the Allam cycle to generate electric power, achieving the classified utilization of materials and simple and efficient capture of CO2. Comparing with the ammonia synthesis and the power generation reference systems, the proposed system omitted the processes with huge exergy destruction for the ammonia synthesis and the exergy destruction of the Allam cycle unit was also reduced through efficient heat integration. The thermodynamic performance is determined by the developed energy analysis models and the process simulation. The root cause of the thermodynamic benefits of this proposed system is revealed by the comprehensive exergy flow analysis. Results showed that the energy saving ratio of the polygeneration system is 7.61% comparing with the reference systems, and the exergy efficiency of the polygeneration system is 3.90% higher than reference systems.

Automated summary

A novel biomass based polygeneration system for power generation and ammonia synthesis was proposed in this study, achieving negative CO2 emission and efficient electricity generation through simple and efficient capture of CO2. Increased energy efficiency and reduced exergy destruction were obtained through effective heat integration and comprehensive exergy flow analysis.