Decision Making on Liquefaction Ratio for Minimizing Specific Energy in a LNG Pilot Plant

Abstract

Natural gas liquefaction is a highly energy-intensive process due to its cryogenic operation. Therefore, a major concern in designing and optimizing natural gas liquefaction processes is the enhancement of energy efficiency. A liquefaction ratio in the natural gas liquefaction process affects the specific energy consumption, which is the energy consumption per unit mass of liquefied natural gas (LNG). However, most of the previous research has not considered the liquefaction ratio of the natural gas. This study focuses on minimizing specific energy consumption of a LNG plant considering the liquefaction ratio. To analyze the effects of the liquefaction ratio, four different cases are set and the optimizations are performed. The objective function to be minimized includes the total energy consumption and specific energy consumption. The result of minimizing total energy consumption converges on the lower bound of the liquefaction ratio, but the result of minimizing specific energy consumption converges between the lower and upper bound. This shows that the total energy minimization does not always have the same meaning as the specific energy minimization when the liquefaction ratio is not fixed. Through this analysis, the relationships between the energy consumption and the liquefaction ratio are found. As the result of the optimization, the optimal compression ratio, temperature, intermediate pressure, and refrigerant flow rate are found, and the specific power was reduced by 16.40% over that of the LNG pilot plant design while yielding the natural gas liquefaction ratio of 86.9%.

Synthesis characterization and luminescence studies of 100MeV Si8+ ion irradiated sol gel derived nanocrystalline Y2O3

“…Sol-gel derived materials have diverse applications in optics, energy, space, electronics, bio sensors, medicine (e.g. controlled drug release), reactive material and chromatography [8].…”

Strategies for Process and Size Selection of Natural Gas Liquefaction Processes: Specific Profit Portfolio Approach by Economic Based Optimization

“…In the C3MR process, pure and mixed refrigerants are used to liquefy the natural gas. Figure describes a process flow diagram of the C3MR process. Propane (C3) is used as the pure refrigerant to precool the natural gas and to cool the mixed refrigerant by means of a multistage refrigeration cycle.…”

“…Each pressure level of the pure refrigerant cools down the natural gas and the mixed refrigerant by multistage heat exchange. The cold mixed refrigerant is compressed by successive multi stage compressors, and it liquefies the natural gas . Generally, the mixed refrigerant in the C3MR process contains nitrogen, methane, ethane, and propane as its component.…”

Case Studies for SMR Natural Gas Liquefaction Plant by Capacity in Small Scale Gas Wells through Cost Analysis

“…이러한 극저온 공정의 특 성상 천연가스 액화공정은 매우 에너지 집약적이다 [4]. 따라서 에너지 최소화는 천연가스 액화공정 설계 및 최적화의 가장 주요 고려사항 중 하나이며, 천연가 스 액화공정의 에너지 효율 최적화를 위한 연구들이 전 세계적으로 활발히 진행되고 있다 [5]. 그러나 천연 가스 액화공정의 비용 최적화에 대한 연구는 상대적 으로 미미한 실정이다.…”