Model-based estimation and control of interface level in a two-phase vertical decanter: A case study of palm-oil/water system

• Published in: Computers & chemical engineering 2018-01, Vol.108, p.372-381
• Main Authors: Chonwattana, Wirachai, Panjapornpon, Chanin, Tawai, Atthasit, Dechakupt, Tanawadee
• Format: Article
• Language: English
• Subjects: Advanced process control; Input/output linearization; Interface estimation; Model-based control; Palm-oil/water separation; Two-phase vertical decanter
• ISSN: 0098-1354; 1873-4375
• DOI: 10.1016/j.compchemeng.2017.10.022

[Display omitted] Separation of two immiscible liquids by a decanter is an important unit operation widely used in petrochemical processes. However, fluctuations in the feed stream create a difficulty in achieving the desired product by such a unit due to the limitations of interface detection and entrainment of heavy phase into a light phase. This research proposes techniques for estimating and controlling the interface position. The interface position is calculated by using information from an ultrasonic sensor and a pressure transducer. An input/output linearizing controller is applied to control the interface position and total liquid height by adjusting the outflows of each liquid phase. A real-time estimator predicts the feed fraction that cannot be measured directly. The proposed method is evaluated through servo and regulatory tests with a bench-scale palm‐oil/water decanter. The experimental results show that the developed method forces outputs to desired setpoints effectively despite the presence of feed disturbances.