Energy and exergy investigation of two modified single mixed refrigerant processes for natural gas liquefaction. (2nd September 2020)

• Record Type: Journal Article
• Authors: Nikkho, Sepehr; Abbasi, Mojgan; Zahirifar, Jafar; Saedi, Morteza; Vatani, Ali
• Is Part Of: Computers & chemical engineering. Volume 140(2020)
• Publication Date: 2020-09-02
• Subjects: Single mixed refrigerant process -- Exergy -- Energy -- Optimization -- Liquefied natural gas; Δtmin, superheat specified degree of superheat temperature (°C) -- Δtmin, specified specified minimum temperature approach (°C) -- Δtsup degree of superheat -- Δtmin minimum temperature approach -- SMR single mixed-refrigerant -- LK low key -- HK heavy key -- C compressor -- P pump -- HX heat exchanger -- VLV pressure valve -- SEP vapor/liquid separator -- MIX stream mixer -- GA genetic algorithm -- AC cooler -- COP coefficient of performance -- SPC specific power consumption -- NG natural gas -- LNG liquefied natural gas; Chemical engineering -- Data processing -- Periodicals; 660.0285
• DOI: 10.1016/j.compchemeng.2020.106854
• Languages: English
• ISSNs: 0098-1354

Abstract

Highlights: Two KSMR processes are investigated via specific power consumption and total exergy destruction rate analysis. The specific power consumption of the KSMR process is reduced to 0.221 kWh/kg LNG. Optimization through exergy function resulted in 11.24% decrease in avoidable exergy destruction rate in compressors compared with the optimization via power function. The second law efficiency of the process is enhanced up to 47.51%. The process with minimum exergy destruction rate and power consumption is reported. Abstract: Liquefaction processes consume a high amount of energy, and any attempt to achieve lower energy consumption and higher exergy efficiency would lead to a remarkable enhancement in the process efficiency. In the present study, two mini-scale modified single mixed refrigerant processes for natural gas liquefaction are simulated. The specific power consumption and total exergy destruction rate are optimized using the genetic algorithm tool. As a result of the energy optimization of the base case process, the specific energy consumption and the total exergy destruction rate are reduced by 19.4% and 25.4%, respectively. On the other hand, the maximum total exergy efficiency of 47.51 % is obtained through the exergy optimization of the process. The results related to the process configuration with a pump shows a higher exergy efficiency. Moreover, the minimum specific power consumption of 0.221 kWh/kg LNG is obtained through the optimization of the exergy destruction rate function.