Energy and exergy analysis of entrained bed gasifier/GT/Kalina cycle model for CO2 co-gasification of waste tyre and biochar

Integrated gasification combined cycle (IGCC) is a power generation technology that partially oxidizes solid feedstocks to produce syngas, drives high-efficiency gas turbines (GT), recovers waste heat and uses it to generate electricity, etc. In this study, a new IGCC model for an entrained bed gasifier/GT/Kalina cycle for CO2 co -gasification was developed for the first time using Aspen HYSYS, and an energy and exergy analysis of this model was performed to provide decision makers with a comprehensive overview of whether the energy con-version system is designed to be sustainable from a variety of perspectives. The newly proposed integrated system was used to study the CO2/air gasification process of the biochar/waste tyre blend. Although entrained bed gasifiers have been modelled using different software and different fuels, no study on the Kalina cycle in-tegrated biochar/waste tyre co-gasification process using Aspen HYSYS has not been reported yet. In addition, most parametric studies on integrated Kalina combined cycles focus on the influence of the Kalina cycle or a few operating factors. However, in this study, the effects of a variety of gasification process operating conditions on the performance of the combined cycle are considered. The equivalence ratio (ER) for a high-efficiency integrated system ranged from 0.23 to 0.25, and the CO2 content in the gasifying agent was in the range of 5-7%. While increasing the waste tyre content in the feedstock enhances H2 production, operating the entrained bed gasifier at relatively low temperature is more efficient. Increasing the ammonia content in the working fluid also improves efficiency, and the inlet pressure of the Kalina turbine should be maintained at 28 bar to maximize performance. While the integration of the GT enables significant power generation, optimizing the operating conditions of the gasifier, which has the highest exergy dissipation, is critical to the performance of the integrated system.

Automated summary

This study developed a new integrated gasification combined cycle (IGCC) model for an entrained bed gasifier/GT/Kalina cycle using Aspen HYSYS, and conducted energy and exergy analysis to assess the sustainability of the system from various perspectives. The study focused on the CO2 co-gasification process of biochar/waste tyre blend, considering the effects of different gasification process operating conditions on the performance of the combined cycle. The study found that optimizing the operating conditions of the gasifier is critical to the performance of the integrated system.