EFFICIENCY ENHANCEMENT FOR NATURAL GAS LIQUEFACTION WITH CO2 CAPTURE AND SEQUESTRATION THROUGH CYCLES INNOVATION AND PROCESS OPTIMIZATION By

Title of Document: Efficiency Enhancement for Natural Gas Liquefaction with CO2 Capture and Sequestration through Cycles Innovation and Process Optimization Abdullah Alabdulkarem, Doctor of Philosophy, 2014 Directed By: Professor, Reinhard Radermacher, Mechanical Engineering Liquefied natural gas (LNG) plants are energy intensive. As a result, the power plants operating these LNG plants emit high amounts of CO2. To mitigate global warming that is caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, the major challenge of implementing this CCS system is the associated power requirement, increasing power consumption by about 15-25%. Therefore, the main scope of this work is to tackle this challenge by minimizing CCS power consumption as well as that of the entire LNG plant though system integration and rigorous optimization. The power consumption of the LNG plant was reduced through improving the process of liquefaction itself. In this work, a genetic algorithm (GA) was used to optimize a propane pre-cooled mixed-refrigerant (C3-MR) LNG plant modeled using HYSYS software. An optimization platform coupling Matlab with HYSYS was developed. New refrigerant mixtures were found, with savings in power consumption as high as 13%. LNG plants optimization with variable natural gas feed compositions was addressed and the solution was proposed through applying robust optimization techniques, resulting in a robust refrigerant which can liquefy a range of natural gas