(140b) Liquid Level Systems for Process Control Education and Researches
AIChE Spring Meeting and Global Congress on Process Safety
2012
2012 Spring Meeting & 8th Global Congress on Process Safety
Education
Technology and Project-Based Learning in the Curriculum
Wednesday, April 4, 2012 - 2:00pm to 2:30pm
Process control is closely related with static and dynamic characteristics of processes. Experiments will improve the process control course. For this, experimental systems that are small and do not produce wastes are required so that they can be used in the class room. Several such systems are available for areas of mechanical engineering and electrical engineering. In the process control area, liquid level systems are adequate. However, most of liquid level systems available are too simple to illustrate various process static and dynamic characteristics (Astrom, K.J. and Ostberg, A.B., “A Teaching Laboratory for Process Control,” IEEE Control Systems Magazine, 6, 37-42, 1986). Recently Johanson (Johansson, K.H. “The Quadruple-Tank Process: A Multivariable Laboratory Process with an Adjustable Zero,” IEEE Trans. Control Systems Technology, 8, 456-465, 2000) proposed a liquid level system with four tanks, four manual valves, two actuators and two level sensors. This system can be made to have an unstable zero and is found to be very useful for process control education and researches. Several research papers have also been available (for example, Mercangoz, M. and Doyle III, F.J., “Distributed Model Predictive Control of a Four-Tank System,” J. Process Control, 17, 297-308, 2007).
In this work, a novel liquid level system which consists of changeable two tanks, one solenoid valve for the actuator and one level sensor is proposed. It is smaller and simpler than the previous ones. Most of process characteristics which are in process control textbook (Seborg, D.E., Edgar, T.F. and Mellichamp, D.A., Process Dynamics and Control, 2nd ed. Wiley, N.Y., 2004) are provided. They include
l Linear Element with 1st Order, 2nd Order, and so on.
l Integral Element
l Time Delay Element
l Inverse Response Element (Unstable Zero Element)
l S-shape Nonlinear Element (Mimic pH Process)
l Nonlinear Element having Input Multiplicity
l Nonlinear Element having Hysteresis (Mimic Ignition of Exothermic Reactor)
l Nonlinear Element with Limit Cycle Instability