Analysis, assessment and optimization of biomass mixed heavy-oil driven integrated gasification combined cycle for multigeneration

Abstract

There has been increasing interest in employing Integrated Gasification Combined Cycles (IGCC) using various biomasses and low-rank coals for producing multiple outputs. The most of the existing IGCC plants do not conserve the low-grade heat, use air separation unit and the presence of coal produces high amount of carbon based emissions. The production of syngas through gasification of renewable feedstocks, such as biomass, organic food waste and animal manure is an attractive option with less emissions. In this thesis, three novel multigeneration IGCC based on organic and refinery wastes are specifically developed for three sectors; community, food industry and refinery. The systems are simulated using Aspen (Plus) and results are validated through energy and exergy analyses, and research reported in the literature. The exergy analysis is performed with the help of Engineering Equation Solver (EES). The developed systems can be employed anywhere in the world with some modifications, however, the case studies are performed for Saudi Arabia for assessment. The Genetic Algorithm model is used to optimize the developed systems. A multi-objective optimization approach is applied to achieve the best performances of the developed systems. Three objectives function used in this study include; exergy efficiency, total cost and CO2 emissions. The developed systems are environmentally benign as the production of CO2 is low enough to meet the stringent environmental regulations. The energy and exergy efficiencies of the cold gas, overall, gas turbine and steam turbine for the proposed systems 1 are found to be 58.2% and 57.6%, 55.9% and 32.1%, 29.8% and 26.7%, 34.1% and 60.1%, respectively. The energy and exergy efficiencies of the cold gas, overall, gas turbine and steam turbine for the proposed systems 2 are found to be 62.1% and 61.4%, 57.9% and 33.3%, 29.2% and 25.9%, 33.7% and 61.7%, respectively. The energy and exergy efficiencies of the cold gas, overall, gas turbine and steam turbine for the proposed systems 3 are found to be 68.3% and 68.7%, 60.7% and 34.8%, 27.8% and 24.7%, 34.4% and 60.3%, respectively. The highest magnitude of exergy destruction occurs in combustion chamber. The electrical power output for system 1, system 2, and system 3 is found to be in the order of 461 MW, 433 MW and 466 MW, respectively.