# Publication

International Conference
2013.12.04 14:08

# Kyu-Yeul Lee, Ju-Hwan Cha, Joon-Chae Lee, Myung-Il Roh, Ji-Hyun Hwang, "Determination of the Optimal Operating Condition of Dual Mixed Refrigerant Cycle at the Pre-FEED Stage of LNG FPSO Topside Liquefaction Process", Proceedings of ISOPE(International Society of Offshore and Polar Engineers) 2011, Maui, USA, pp. 151-158, 2011.06.19-24

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Abstract The dual mixed refrigerant (DMR) cycle, which pre-cools natural gas with the mixed refrigerants and then liquefies the natural gas with another set of mixed refrigerants, is well known for having the highest efficiency among the liquefaction cycles. Its possible application to LNG FPSO is also extensively investigated. In this study, the optimal operating conditions, such as the equipment's flow rate, pressure, temperature, and refrigerant composition per flow of the DMR cycle, were determined in consideration of power efficiency. To determine the optimal operating conditions, a mathematical model was formulated based on the mathematical model of the single mixed refrigerant (SMR) cycle with additional consideration of tees, phase separators, and common headers. In the mathematical model, the 227 operating conditions were defined as unknowns and 196 equality constraints related to the thermodynamics for the equipment were formulated. Further, the 15 given variables related to the natural gas, compressor efficiency and seawater coolers were used. This mathematical model can be regarded as the optimization problem, in which the number of unknowns is larger than the total number of equality constraints and given variables. To obtain the optimal operating conditions, the minimization of the required power for the compressors at the cycle was defined as an objective function. Moreover, set as design variables were the 16 operating conditions, such as flow rate, pressure, temperature and composition of the main and precooling refrigerant, natural gas temperature after precooling, and flow rate ratio for the tee. In addition, the temperature conditions for the equipment’s operation were used as inequality constraints. The optimal operating conditions were then obtained by using a hybrid optimization method that consists of the genetic algorithm (GA) and sequential quadratic programming (SQP). The calculation results show that the required power at the obtained conditions was decreased by 34.5% compared with that of the relevant patent obtained in 2001, and 1.2% compared with the corresponding value from the past relevant study carried out in 2008. 2011-06-19

Kyu-Yeul Lee, Ju-Hwan Cha, Joon-Chae Lee, Myung-Il Roh, Ji-Hyun Hwang, "Determination of the Optimal Operating Condition of Dual Mixed Refrigerant Cycle at the Pre-FEED Stage of LNG FPSO Topside Liquefaction Process", Proceedings of ISOPE(International Society of Offshore and Polar Engineers) 2011, Maui, USA, pp. 151-158, 2011.06.19-24

 제목+내용제목내용댓글이름닉네임아이디태그
1. Min-Chul Kong, Myung-Il Roh, In-Chang Yeo, Ki-Su Kim, Jeongyoul Lee, Jongoh Kim, Gapheon Lee, "A Detection Method of Objects with Text in Drawings Based on Deep Learning", Proceedings of ISOPE 2023, Ottawa, Canada, 2023.06.19-23

2. No Image 17Jun
by
in Conference Chairman

Mechanics & Collision I, ISOPE(International Society of Offshore and Polar Engineers) 2017, San Francisco, USA, 2017.06.25-30

3. Luman Zhao, Myung-Il Roh, Seung-Ho Ham, "Hardware-In-the-Loop Simulation for the Design and Testing of an Active Compensation System on an Offshore Supply Vessel", Proceedings of SUTTC 2016, Beijing, China, 2016.09.26-30

4. Luman Zhao, Myung-Il Roh, Seung-Ho Ham, "Hardware-In-the-Loop Simulation for a Heave Compensator of an Offshore Support Vessel", Proceedings of OMAE 2016, Busan, Korea, pp. 1-5, 2016.06.19-24

5. Luman Zhao, Myung-Il Roh, Seung-Ho Ham, "Anti-sway Control of the Crane on an Offshore Support Vessel Based on the Hardware-In-the-Loop Simulation", Proceedings of ISOPE 2017, San Francisco, USA, pp. 651-654, 2017.06.25-30

6. Luman Zhao, Myung-Il Roh, Hye-Won Lee, Do-Hyun Chun, Sung-Jun Lee, "A Collision Avoidance Method of Multi-ships Based on Deep Reinforcement Learning Considering COLREGs," Proceedings of ICCAS 2019, Rotterdam, Netherlands, pp. 85-88, 2019.09.24-26

7. Luman Zhao, Myung-Il Roh, Hye-Won Lee, "Control Design for an Unmanned Surface Vessel Based on Hardware-In-the-Loop Simulation", Proceedings of SUTTC(The Society for Underwater Technology Technical Conference) 2017, Haikou, China, 2017.11.23-24

8. Kyu-Yeul Lee, Seon-Ho Cho, Myung-Il Roh, "An Efficient Global-Local Hybrid Optimization Method Using Design Sensitivity Analysis", Proceedings of OptiCon 2000, Newport Beach, USA, pp. 1-13, 2000.10.26-27

9. Kyu-Yeul Lee, Sang-Uk Lee, Doo-Yeoun Cho, Myung-Il Roh, Seong-Chan Kang, Jung-Woo Seo, "An Innovative Compartment Modeling and Ship Calculation System", Proceedings of IMDC(International Marine Design Conference) 2003, Athens, Greece, 2003.05.05-08

10. Kyu-Yeul Lee, Myung-Il Roh, Sang-Uk Lee, Joong-Hyun Rhim, Seong-Chan Kang, Jong-Hyun Kim, Jeong-Youl Lee, "Development of a Hull Structural CAD System for an Initial Design Stage", Proceedings of PRADS 2004, Germany, pp. 98-105, 2004.09.12-17

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