5168

4842

كارشناسي ارشد

تبديل انرژي

اصفهان:دانشگاه صنعتي اصفهان،دانشكده مكانيك

1388

شانزده،93ص.:مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محمدرضا سليم پور

علي اكبر عالم رجبي

25/2/89

احمدرضا عظيميان،احمد صابونچي

مهندسي مكانيك

ID4842

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Performance Improvement of a Combined Cycle for Exergy and Energy Recovery of Liquefied Natural Gas Mohammad Ali Zahedi Mohammadali zahedi@gmail com 2 22 2009 Department of mechanical engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mohammad Reza Salimpour Email Salimpour@cc iut ac ir Abstract The effective utilization of the cryogenic exergy associated with liquefied natural gas LNG vaporization is important In liquefied natural gas LNG during regasification can be used from available cold energy to recover exergy and production of electric power Liquefied natural gas LNG is known as a clean energy source which is commonly used as domestic and industrial fuel for combustion LNG is composed of 85 99 methane by mole fraction a few percent ethane and propane depending on its production site Since moisture and sulphur are contained in crude natural gases they should be removed during the liquefying preprocess In this project efficiency of open brayton cycle increases as step by step that would be made to four cycles Energy equilibrium equations and exergy equilibrium equations of each component in the any four power cycles are established and taken some operating parameters as key parameters influences of these parameters on thermal efficiency and exergy efficiency of the all power cycles were analyzed The results of four cycles are compared with together and finally a combined cycle is suggested that can recover heat loss of low temperature and uses LNG cold energy as well A novel combined power cycle is proposed which utilizes LNG in different ways to enhance the power generation of a power plant In addition to the direct expansion in the appropriate expander LNG is used as a low temperature heat sink for a middle pressure gas cycle which uses nitrogen as working fluid Also LNG is used to cool the inlet air of an open Brayton gas turbine cycle This cycle with LNG directly expanding consisting of a middle brayton cycle with nitrogen as working fluid and a power cycle of combustion gas is proposed to recover cryogenic energy of LNG These measures are accomplished to improve the exergy recovery of LNG In order to analyze the performance of the system the influence of several key parameters such as pressure ratio of LNG turbine the ratio of the mass flow rate of LNG to the mass flow rate of air pressure ratio of different compressors LNG pressure and inlet pressure of nitrogen compressor on the thermal efficiency and exergy efficiency of the offered cycle is investigated Finally the proposed combined cycle is optimized on the basis of first and second laws of thermodynamics In this project is tried without increasing of component cycle efficiency increases and extra air to control open brayton turbine inlet temperature is used The goal of this study is to show how to implement the concept of thermo economy to this cycle and also how to estimate the entering costs to the final cycle Cost balances and auxiliary equations are applied to all components in the cycle A benefit rate parameter is introduced and so the final cycle is optimized on base of this parameter hence cost rate and benefit rate is

محمدرضا سليم پور

علي اكبر عالم رجبي

احمدرضا عظيميان،احمد صابونچي