الفهرس 
CHAPTER ONE - INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
There has been continuous evolution of LNG liquefaction processes to meet the ever-increasing demands of plant capacity and cost reduction. The objective of the presented thesis is to study the effect of retrofitting or expansion of an existing Damietta propane pre-cooling mixed refrigerant LNG process by adding a nitrogen expander cycle to sub-cool the LNG which commercially named AP-X cycle (Licensed by Air Products and Chemicals Incorporation) thus the LNG sub-cooling activity is shifted from the main cryogenic heat exchanger to a separate nitrogen expander sub-cooling cycle which considered very efficient at providing cold refrigeration. The presented modification gives the liquefaction process an important advantage as the power split between propane, mixed refrigerant and nitrogen refrigeration cycles is flexible and can be manipulated by changing the temperature range of the three refrigerant loops. The simulation of the existing and modified cycles was conducted using aspen HYSYS simulator version-8 with best practice equation of state. The simulation results show that the total power saving after operating the existing conventional cycle with AP-X operating mode represents 8.33% of the total consumed power that was necessary to the conventional cycle due to reduction of the volumetric flow rate of propane by 21.85% and mixed refrigerant by 40.86%. The total power saving will be utilized to increase LNG production considering that not to exceed the plant design margin. The LNG production increased by 12% more than the existing cycle which leads to a reasonable annual revenue.