(328b) Application of Dynamic Heat Exchanger Design in Natural Gas Liquefaction Process

Authors: 
Fazlollahi, F., Brigham Young University
Safdari, M. S., Chemical Engineering Department, Brigham Young University, Provo, UT 84602, USA
Saeidi, S., School of Chemical Engineering, Amirkabir University of Technology (Tehran Polytechnic), No. 424, Hafez Avenue, 15914, Tehran, Iran
Baxter, L. L., Brigham Young University
The paper discusses transient Aspen HYSYS modeling and optimization of two natural gas liquefaction processes and identifies the rate-limiting components during load variations. The optimized model for both processes provides details for comparison. Novel flowrate variations included in this investigation drive transients responses of all units, especially compressors and heat exchanger. Heat exchangers commonly represent the most sensitive components to transients. This sensitivity decreases when using new heat exchanger designs and control methods. Model-predictive control (MPC) responses compare favorably with results using traditional controls. Transient efficiency graphs for both designs illustrate improvements during model predictive control. These new controls and designs optimize natural gas (NG) consumption and liquefied natural gas (LNG) production.