• Title/Summary/Keyword: Liquefaction process of natural gas

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Analysis of high efficiency natural gas liquefaction cycle with mixed refrigerant (고효율 혼합 냉매 천연 가스 액화 공정에 대한 고찰)

  • Baek, Seung-Whan;Hwang, Gyu-Wan;Jeong, Sang-Kwon
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.181-185
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    • 2008
  • The new concept for liquefaction of natural gas has been designed and simulated in this paper. Conventional liquefaction cycles are usually composed with Joule-Thomson valves at lower temperature refrigerant cycle. The new concept of natural gas liquefaction is discussed. The main difference with conventional liquefaction process is the presence of the turbine at low temperature of MR (mixed refrigerant) cycle. The turbine acts as expander but also as an energy generator. This generated energy is provided to the compressor which consumes energy to pressurize refrigerants. The composition of the mixed refrigerant is investigated in this study. Components of the refrigerant are methane, propane and nitrogen. Composition for new process is traced with Aspen HYSYS software. LNG heat exchangers are analyzed for the new process. Heating and cooling curves in heat exchangers were also analyzed.

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Development of partial liquefaction system for liquefied natural gas carrier application using exergy analysis

  • Choi, Jungho
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.10 no.5
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    • pp.609-616
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    • 2018
  • The cargo handling system, which is composed of a fuel gas supply unit and cargo tank pressure control unit, is the second largest power consumer in a Liquefied Natural Gas (LNG) carrier. Because of recent enhancements in ship efficiency, the surplus boil-off gas that remains after supplying fuel gas for ship propulsion must be reliquefied or burned to regulate the cargo tank pressure. A full or partial liquefaction process can be applied to return the surplus gas to the cargo tank. The purpose of this study is to review the current partial liquefaction process for LNG carriers and develop new processes for reducing power consumption using exergy analysis. The developed partial liquefaction process was also compared with the full liquefaction process applicable to a LNG carrier with a varying boil-off gas composition and varying liquefaction amounts. An exergy analysis showed that the Joule-Thomson valve is the key component needed for improvements to the system, and that the proposed system showed an 8% enhancement relative to the current prevailing system. A comparison of the study results with a partial/full liquefaction process showed that power consumption is strongly affected by the returned liquefied amount.

Investigation on Efficiency Improvement of the Nitrogen Expander Cycle : Natural Gas Liquefaction Process for LNG-FPSO (LNG-FPSO(Liquefied Natural Gas-Floating Production Storage and Offloading)용 질소 팽창 사이클의 효율 개선에 대한 연구)

  • Baek, Seung-Whan;Jeong, Sang-Kwon;Kim, Sun-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.7
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    • pp.442-447
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    • 2010
  • FPSO (Floating Production Strorage and Offloading) method for LNG industry is efficient and facile compared to onshore NG (Natural Gas) treatment facility. Five simple natural gas liquefaction cycles for FPSO are presented and simulated in this paper. SMR (Single Mixed Refrigerant) cycle, SNE (Single Nitrogen Expander) cycle, DNE (Double Nitrogen Expander) cycle, PNE (Precooled Nitrogen Expander) cycle, and PDNE (Precooled Double Nitrogen Expander) cycle are compared. Simple analysis results in this paper show that precooling process and adding an expander in the liquefaction cycle is an effective way to increase liquefaction efficiency.

Study on Simulation and Optimization of C3MR Liquefaction Cycle (천연가스 액화공정의 C3MR 냉동사이클의 공정모사와 최적화에 관한 연구)

  • Park, Chang Won;Cha, Kyu Sang;Lee, Sang Gyu;Lee, Chel Gu;Choi, Keun Hyung
    • Journal of the Korean Institute of Gas
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    • v.17 no.1
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    • pp.67-72
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    • 2013
  • The LNG liquefaction plant which have a higher value-added business in the LNG value chain takes about 35% of total cost. Liquefaction process is core technology of liquefaction plant. Almost all of cost which was consumed from the liquefaction plant, using for operation energy of liquefaction process. The cost can be reduced by increasing efficiency of liquefaction cycle. C3MR(propane pre-cooled, mixed refrigerant cycle) which liquefies NG using propane and MR cycle has the high efficiency, so C3MR is mostly used liquefaction process in LNG industry. In this study, process simulation and analysis were performed for C3MR process. C3MR process variables were found through this simulation and analysis, and then the process optimization was performed. It is considered that the results of process analysis, process variables and process optimization study can be utilized to develope new liquefaction process.

Study on the Improvement of Efficiency in Dehydration Process of LNG Liquefaction Plant Using Molecular Sieve (분자체를 이용한 LNG 액화 플랜트 탈수 공정의 효율성 향상에 관한 연구)

  • JONGHWA PARK;DONSANG YU;DAEMYEONG CHO
    • Journal of Hydrogen and New Energy
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    • v.35 no.1
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    • pp.105-113
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    • 2024
  • The natural gas dehydration process plays a central role in liquefying LNG. This study proposes two natural gas dehydration process systems applicable to liquefied natural gas (LNG) liquefaction plants, and compares and analyzes energy optimization measures through simulation. The fuel gas from feed stream (FFF) case, which requires additional equipment for gas circulation, disadvantages are design capacity and increased energy. On the other hand, the end flash gas (EFG) case has advantages such as low initial investment costs and no need for compressors, but has downsides such as increased power energy and the use of gas with different components. According to the process simulation results, the required energy is 33.22 MW for the FFF case and 32.86 MW for the EFG case, confirming 1.1% energy savings per unit time in the EFG case. Therefore, in terms of design pressure, capacity, device configuration, and required energy, the EFG case is relatively advantageous. However, further research is needed on the impact of changes in the composition of regenerated gas on the liquefaction process and the fuel gas system.

Determination of the Optimal Operating Condition of the Hamworthy Mark I Cycle for LNG-FPSO (LNG-FPSO에의 적용을 위한 Hamworthy Mark I Cycle의 최적 운전 조건 결정)

  • Cha, Ju-Hwan;Lee, Joon-Chae;Roh, Myung-Il;Lee, Kyu-Yeul
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.5
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    • pp.733-742
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    • 2010
  • In this study, optimization was performed to improve the conventional liquefaction process of offshore plants, such as a LNG-FPSO(Liquefied Natural Gas-Floating, Production, Storage, and Offloading unit) by maximizing the energy efficiency of the process. The major equipments of the liquefaction process are compressors, expanders, and heat exchangers. These are connected by stream which has some thermodynamic properties, such as the temperature, pressure, enthalpy or specific volume, and entropy. For this, a process design problem for the liquefaction process of offshore plants was mathematically formulated as an optimization problem. The minimization of the total energy requirement of the liquefaction process was used as an objective function. Governing equations and other equations derived from thermodynamic laws acted as constraints. To solve this problem, the sequential quadratic programming(SQP) method was used. To evaluate the proposed method in this study, it was applied to the natural gas liquefaction process of the LNG-FPSO. The result showed that the proposed method could present the improved liquefaction process minimizing the total energy requirement as compared to conventional process.

Performance Characteristics of Natural Gas Liquefaction Process using Liquid-gas Heat Exchanger (액-가스 열교환기를 적용한 천연가스 액화공정 성능 특성)

  • Yoon, Jung-In;Yoo, Sun-Il;Oh, Seung-Taek;Lee, Ho-Saeng;Lee, Sang-Gyu;Choi, Keun-Hyung
    • Journal of the Korean Institute of Gas
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    • v.13 no.6
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    • pp.44-48
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    • 2009
  • In this paper, two different types of natural gas liquefaction cycle with 2 staged compression were designed and simulated to develop liquefaction process which is the core technology in the Industry of natural gas liquefaction plant. These include the cascade cycle with inter-cooler which is consisted of propane, ethylene and methane cycle. One of these is that liquid-gas heat exchanger is applied to between methane and ethylene cycles, and another is that liquid-gas heat exchanger is added to between ethylene and propane on the above process. Also, these cycles are compared with two staged cascade process using an inter-cooler. The COP of process2 is shown about 14.0% higher than that of process1, respectively. Also, the yield efficiency of LNG improved comparing with process1 with 11.5% lower specific power.

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Characteristics of cryogenic liquefaction cycle using two stage compression type (2단 압축 방식을 적용한 초저온 액화 사이클 특성)

  • Oh, Seung-Taek;Lee, Ho-Saeng;Yi, Gyeong-Beom;Yoon, Jung-In;Lee, Sang-Gyu
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.556-560
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    • 2009
  • In this paper, two different types of natural gas liquefaction process are simulated and designed for secure a competitiveness in the industry of natural gas liquefaction plant. These processes are based on basic cascade process, and one of these is improved with two staged intercooler and the other is modified two staged intercooler. These processes are compared characteristics of performance with basic process. COP of cascade process with two staged intercooler and modified two staged intercooler showed about 13.74% and 21.64% higher than basic process, and yield efficiency of modified process improved comparing with the basic process by 25.93% lower specific power, respectively.

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Basic Design of 36 MTD Class Natural Gas BOG Re-Liquefaction System (36 MTD급 천연가스 BOG 재액화 플랜트 기본설계)

  • Ko, Junseok;Park, Seong-Je;Kim, Ki-Duck;Hong, Yong-Ju;Koh, Deuk-Yong;Kim, Hyobong;Yeom, Hankil
    • Transactions of the KSME C: Technology and Education
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    • v.1 no.1
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    • pp.99-105
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    • 2013
  • In this paper, we carried out the basic design of 36 MTD natural gas BOG re-liquefaction system to recover the generated natural gas during performance test of LNG pump and natural gas compressor. The re-liquefaction process of natural gas is designed to have 1500 kg/h of liquefaction rate with reverse Brayton refrigeration cycle. With the designed process, the variation of liquefaction rate is calculated for various inlet conditions of feed gas. From results, the liquefaction rate is more sensitive for inlet temperature than gas composition. The specifications of equipments such as gas blower, natural gas compressor, cryogenic heat exchanger and nitrogen compander are determined on the basis of the designed process. The requirement of power consumption and cooling water are also determined through the basic design.

Case Studies for Optimizing Energy Efficiency of Propane Cycle Pressure Levels on C3-MR Process (C3-MR 공정의 프로판 사이클 압력 레벨에 따른 에너지효율 최적화를 위한 사례연구)

  • Lee, In-Kyu;Tak, Kyung-Jae;Lim, Won-Sub;Moon, Il;Kim, Hak-Sung;Choi, Kwang-Ho
    • Journal of the Korean Institute of Gas
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    • v.15 no.6
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    • pp.38-43
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    • 2011
  • Natural gas liquefaction process runs under cryogenic condition, and it spends large amount of energy. Minimizing energy consumption of natural gas liquefaction process is an important issue because of its physical characteristics. Among many kinds of natural gas liquefaction processes, C3-MR(Propane Pre-cooled Mixed Refrigerant) process uses two kind of refrigerants. One is the propane as the pure refrigerant(PR) and the other is the mixed refrigerant(MR). In this study, to find the optimal compressing level, propane cycle is simulated on different pressure level. The case study result shows relationship between energy consumption and pressure level. As a result, the conclusion is that at a higher pressure level, process consumes lower energy. At 5 pressure-levels, energy consumption is 23.7% lower than 3 pressure-levels.