LNG冷能最適化利用之研究

The Optimum Study of Using LNG Cold Energy

陳文湖(Wen-Hu Chen)

指導教授 ： 李魁鵬

國立臺北科技大學/機電學院/冷凍空調工程系所/碩士(2006年)

摘要

本論文以LNG接收站與電廠為一體建設，分析液化天然氣冷能最適化的利用，規劃LNG冷能應用於空氣液化系統、儲冰系統、氣渦輪機進氣冷卻系統及TCA冷卻系統，將總能利用達到最大化，以符節能原則。
依熱力學第二定律，利用NIST軟體分析系統可用能情形，將可用能輸出率與可用能輸入率的比值定義為可用能效率，以此定義作為系統最佳化的目標函數，利用規劃求解找出最佳化設計值。經求解發現LNG運轉於空氣液化系統出口溫度230K，儲冰系統出口溫度246K，氣渦輪機進氣冷卻系統出口溫度270K，TCA出口溫度473K，具有LNG冷能最大的可用能效率44.45%，整體效率達74.25%。利用單位可用能及單位LNG流量下，規劃求解進行最小化成本分析，LNG運轉於空氣液化系統出口溫度為174K，儲冰系統出口溫度為241K，氣渦輪機進氣冷卻系統出口溫度為264K，TCA出口溫度473K，可獲得最小的單位成本63.43單位成本。
LNG 冷能應用所獲得的功轉換成電費，利用成本與節省電費可計算回收年限，回收年限為1.36年，值得投資。LNG冷能最適化研究提供有效而重要的設計準則， LNG接收站與電廠為一體建設系統設計參數對最大可用能效率之影響亦在文中加以討論，可提供設計者參考。

關鍵字

液化天然氣

並列摘要

In order to get maximum of LNG cold energy and save energy, this subject study the optimum of using LNG cold energy based on the LNG received station and power plant co-construction to map out a system of using LNG cold energy in the purifier nitrogen, storge energy, inlet air cooling of gas turbine and TCA system.
According to the second law of thermodynamic, energy includes exergy and anergy. This paper uses Thermodynamic and Transport Properties of Refrigerant Version 6.02 NIST software to analysis system exergy to get the exergy efficiency, which is defined the best target function and uses programming method to look for the target design value.
By the Excel linear programming calculation, this research showed the maximum exergy efficiency of using LNG cold energy is 44.45% and total exergy efficiency reaches 74.25% , while LNG operate in 230K of the outlet of the purifier nitrogen and 246K of the outlet of the storge energy and 270k of the outlet of the inlet air cooling of gas turbine and 473K of the outlet of the TCA system.
From the excel programming method, this paper find the lowest cost 63.43 by unit exergy and unit flow of LNG while LNG is operated at the optimal temperature 174K of the outlet of the purifier nitrogen and 241K of the outlet of the storge energy and 264k of the outlet of the inlet air cooling of gas turbine and 473K of the outlet of the TCA.
From the saving energy to transform electric pay, this equipment fee will be back about 1.36year. It is worth to invest. This optimum study of using LNG cold energy provides an effective principal for designer who wanted to use LNG cold energy in the LNG received station and power plant co-generation

並列關鍵字

LNG ； EXERGY

參考文獻

[3] Energy and Conditioning Department, University of Genoa,Via all Opera Pia 15 A 16145 Genoa ,Italy , G.Bisio ,L.Tagliafico “On the recovery of LNG physical exergy by means of a simple cycle or a complex system”.

[4] Wang Qiang ，Li Yanzhong , Wang Jiang “Analysis of power cycle based on cold energy of liquefied natural gas and natural gas and low-grade heat source “中國交通大學低溫工程學系。

[6] Coral Gables ,FL 33124 USA Hongtan Liu ,Lixin You“Characteristics and applications of the cold heat exergy of liquefied natural gas” , Department of Mechanical Engineering , University of Miami.

[7] T.S.Kim及S.T.Ro，”Power augmentation of combined cycle power plants using cold energy of liquefied natural gas” ，韓國漢城大學Turbo and Power Machinery 研究中心。

[1] ”能源政策白皮書” ，經濟部能源局。