GRD Journals | Global Research and Development Journal for Engineering | Emerging Research and Innovations in Civil Engineering (ERICE - 2019) | February 2019
e-ISSN: 2455-5703
State Feedback Controller for LNG Storage Tank System using Pole Placement Method 1Dashrath
S. Panchal 2Devesh P. Soni 3Dipesh H. Shah 1 P.G. Scholar 2 3 Department of Civil Engineering Department of Instrumentation and Control Engineering 1,2,3 Sardar Vallabhbhai Patel Institute of Technology Vasad, India Abstract In this paper seismic control problem is discussed for an extra-large Liquefied Natural Gas (LNG) storage tank using smart baseisolation. The seismic forces are reduced by isolating LNG tank from ground through laminated isolation bearing made from natural rubber. Magneto-rheological (MR) dampers are installed to control the excessive displacement of LNG tank system. The MR dampers are commended by state feedback controller designed using pole placement method. The efficacy and effectiveness of derived control algorithm are presented and compared with uncontrolled system for past three earthquake ground motion. The simulation results showed that the state feedback control strategy is more effective in reducing the structural responses as compared to uncontrolled system. Keyword- State Feedback Control, Magneto - Rheological Damper, Pole Placement Method __________________________________________________________________________________________________
I. INTRODUCTION Our industrialized world is characterized by increase in energy demand. As the demand of energy increases, more and even larger size of LNG storage tanks is required. Recently, implementations of seismic isolation and energy dissipation systems have been extended to liquid storage tanks, especially large capacity liquefied natural gas (LNG) storage tanks, in order to improve their performance during earthquakes. The volumes of these tanks are very large and have capacities of about 160,000 m 3. The modern LNG tank as shown in Figure 1(a) consists of an inner steel tank, which contains the LNG, and an outer concrete tank that encases and protects the inner tank. Insulation is placed between the two tank walls. The LNG storage tanks are generally used in a typical LNG chain (shown in Figure 1(b)) which consists of Extraction, Transportation and Re-gasification. Natural gas is a fossil fuel composed primarily of methane (typically, at least 90%) and small quantities of nitrogen, oxygen, carbon dioxide, sulphur compounds. The liquefaction process that produces LNG removes any oxygen, carbon dioxide, sulphur compounds, and water. At atmospheric pressure natural gas liquefies for storage when temperature is approximately about -161.52°C. LNG receiving terminals and re-gasification facilities store LNG before its re-gasification for pipeline transportation.
Fig. 1 (a): Schematic View of modern LNG Tank
Fig. 1 (b): LNG Chain: Extraction, Transportation and Regasification
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