Development of thermodynamically integrated processes for the efficient utilization of energy carriers (hydrogen and ethanol)

Abstract

Several integrated systems incorporating clean energy technologies have been proposed as potential solutions for the challenges posed by long-term energy concerns. One promising approach involves using hydrogen-containing industrial by-products and carbon dioxide from industrial exhaust gases. These gases can be purified and converted into liquid hydrogen or liquid methanol, efficient energy carriers, through advanced liquefaction methods. This process not only helps address environmental pollution but also minimizes energy wastage. By employing hydrogen purification techniques or alternative processes to extract hydrogen from industrial by-products, clean energy carriers like liquid hydrogen and methanol can be produced, aligning with the global imperative of achieving net-zero emissions targets. This study introduces three innovative integrated structures for fuel-based energy storage. The first method proposes an integrated structure to liquefy hydrogen using an ejectorcompression refrigeration cycle, cascade multi-component refrigerant cycle, and the Kalina power generation cycle. The excess heat generated during the hydrogen liquefaction process is effectively utilized by the Kalina power generation cycle. The refrigeration system is integrated with the main core configuration through composite and grand composite curves, optimizing refrigerant composition percentages and refrigeration cycle operating pressures to achieve the best possible match between cold and hot curves. The study also presents two novel integrated processes for methanol production. The first design focuses on a process that produces low-pressure and high-pressure fuel gases, aromatic compounds, electricity, and hot water as side products, with liquid methanol as the main product. This process includes hydrogen purification, methanol production, Organic Rankine (ORC), absorption-compression cycles (ACRC), and solar collectors. The ORC efficiently utilizes waste heat from the methanol reactor to generate power, while the ACRC provides cooling for the hydrogen purification cycle. The second design for methanol production outlines an environmentally friendly process utilizing hydrogen extracted from coke oven gas (COG) to react with carbon dioxide in a methanol reactor. The subsystems of this process include a CO2 capture unit for separating carbon dioxide from exhaust gases, a natural gas purification and liquefaction process to produce liquefied natural gas (LNG), hydrogen extraction from COG, and a methanol production cycle. Photovoltaic panels, customized to the geographical location, are employed to provide the required power. In the proposed methods of liquid methanol production, economic analysis is conducted using the Annualized Cost of the System (ACS), and the process undergoes multi-objective optimization through the implementation of the NSGAII algorithm. The decision-making methods, including fuzzy, TOPSIS, and LINMAP, are utilized to evaluate the optimum rate of return and prime cost of the main product. Sensitivity, energy, and exergy analysis are performed using Aspen HYSYS software V.10 and MATLAB code to comprehensively assess the process performance from a thermodynamic standpoint.

Date	22 Apr 2024
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Adrian Ilinca (Supervisor)