Research subject: This study focuses on the design and evaluation of a novel integrated system for simultaneous multi-generation production. The objective is to develop an efficient process capable of co-producing four outputs: electricity, heat, cooling, and pure carbon dioxide. The main innovation lies in the combined use of biogas produced from corn cob fermentation and a carbon capture unit with net-negative emission capability. Distinctive features of this design include thermal integration, such as utilizing recovered heat from gas turbine exhaust to supply energy to the carbon capture unit, and leveraging the cooling potential from the liquefied natural gas (LNG) process.
Research approach: The designed system comprises key components, including a gas turbine, a chemical carbon dioxide absorption unit, an Organic Rankine Cycle for waste heat recovery and additional power generation and a hot water boiler for heating supply. The system was simulated using Aspen HYSYS software. For a comprehensive performance evaluation, four parallel analyses were conducted on the system: energy analysis, exergy analysis, economic analysis, and finally, a sensitivity parametric analysis. The aforementioned parametric analysis was performed to examine the impact of key operational parameters on performance indicators and to propose improvement strategies.
Main results: Based on the simulation results, the overall energy efficiency of the process was calculated as 52.19%, the exergy efficiency as 40.59%, and the specific electrical efficiency as 41.96%. A major advantage of the system is approximately 34.1% fuel savings compared to separately producing the same products. From an economic perspective, the total system cost rate was estimated at $ 496 per hour, and the cost per unit product at $ 25.74/GJ. Exergy analysis also revealed that the total exergy destruction within the system equals 8694 kW. Key results from the parametric analysis indicated that increasing the combustion air temperature, due to reduced exergy destruction in the burner and heat exchanger E-100, leads to a significant improvement in all performance indicators. Consequently, with this increase, the energy efficiency, exergy efficiency, electrical efficiency, and fuel saving rate were enhanced to 0.6269, 0.4587, 0. 4720, and 0.4288, respectively.