Design of ternary signals for MIMO identification in the presence of noise and nonlinear distortion

A new approach to designing sets of ternary periodic signals with different periods for multi-input multi-output system identification is described. The signals are pseudo-random signals with uniform nonzero harmonics, generated from Galois field GF(q), where q is a prime or a power of a prime. The signals are designed to be uncorrelated, so that effects of different inputs can be easily decoupled. However, correlated harmonics can be included if necessary, for applications in the identification of ill-conditioned processes. A design table is given for q les 31. An example is presented for the design of five uncorrelated signals with a common period N = 168 . Three of these signals are applied to identify the transfer function matrix as well as the singular values of a simulated distillation column. Results obtained are compared with those achieved using two alternative methods

Bilinear control of a binary distillation column.

Bilinear systems are an attractive alternative to the traditional linearisation approach for many chemical plant items. Techniques for the identification and control of discrete time bilinear systems were examined and developed. The performance of four reccursive identification methods was compared for a discrete bilinear system with white noise contamination of the output. Reccursive least squares methods gave the best performance for a number of criteria. A reccursive maximum likelihood gave similar performance to standard reccursive least squares despite having double the computational requirements. A design method for a discrete time, globally asymptotically stabilising, optimal controller with a quadratic performance function was developed based on the solution to the algebraic matrix Riccati equation. The controller design was successfully and safely applied to both simulated and pilot scale, constant volume, heated tank systems and a simulated binary distillation column. Application of the discrete-time, bilinear controller to the heated tank system gave good control over the full operating range. Conventional linear and PID controllers, while accurate near the tuning point, were unable to cope when away from this region. The linear controller gave large steady state offset, while the PID controller suffered from stability problems. A method of deadtime compensation, based on a discrete time bilinear model of the system, reduced deadtime induced overshoot after set point changes or disturbances, however, steady state offset resulted, due to the amplification of errors in the model. The discrete bilinear controller gave good, safe, control of a simulated binary distillation column. A reduction in steady state offset was observed when compared to a linear optimal regulator with similar weighting matrices. The weakly bilinear nature of the distillation simulation did not threaten the stability of either the linear regulator or a PID controller with static decoupling. Versions of both the linear regulator and bilinear controller with added integral action gave almost identical performance. The presence of integral action dominated the system response. Significant improvements in control and safety may be achieved for strongly bilinear systems such as the constant volume heated tank. For systems which display weak bilinearity, such as the distillation simulation, the bilinear controller may improve the steady state performance, eliminating the need for controllers with integral action in some applications

Nonlinear Model Predictive Control Of A Distillation Column Using Hammerstein Model And Nonlinear Autoregressive Model With Exogenous Input.

Turus penyulingan adalah unit proses penting dalam industri penapisan petroleum dan kimia. Ia perlu dikawal hampir dengan keadaan-keadaan pengendalian yang optima demi insentif- nsentif ekonomi. Distillation column is an important processing unit in petroleum refining and chemical industries, and needs to be controlled close to the optimum operating conditions because of economic incentives

Distillation

The purpose of this book is to offer readers important topics on the modeling, simulation, and optimization of distillation processes. The book is divided into four main sections: the first section is introduction to the topic, the second presents work related to distillation process modeling, the third deals with the modeling of phase equilibrium, one of the most important steps of distillation process modeling, and the the fourth looks at the reactive distillation process, a process that has been applied successfully to a number of applications and has been revealed as a promising strategy for a number of recent challenges

Implementation Of Internal Model Control (IMC) In Continuous Distillation Column.

Distillation columns have been widely used in chemical plants for separation process. The high nonlinearity and dynamic behavior of the column make them hard to control

Development of Pilot Plant for Bio-Ethanol Processing

The paper outlines achievements obtained in developing a pilot bio-ethanol plant at the Department of Chemical and Mining Engineering (CME), University of Dar es Salaam. The pilot plant consists of: 30 L inoculums tank; 1,700 L fermenter; 1,500 L/day distillation column; and ancillary equipment. The prototype is a platform intended to be used for technology demonstration and research by graduate and undergraduate students studying the production of bio-ethanol using traditional and non-traditional raw materials like coffee mash, cashew fruit, and sisal inulin. The equipment has been developed using locally available engineering resources and the distillation column with 18 sieve tray measures 0.5m diameter 7 m high operates at atmospheric pressure. The condenser is cooled by 15 o C chilled water from utility lines and the reboiler is powered by 63 kW boiler installed at CME. Although the system includes biological, chemical and mechanical engineering details, only the important design issues are presented. A MATLAB code was developed forestimating the number of theoretical plates using the Mc Cabe-Thiele method. The water- ethanol vapour liquid equilibrium VLE data was obtained using relative volatilities estimated by Antoine equations for vapour pressure. The process design was done using various simulation packages and custom programs like Microsoft Excel for mass balance,Microsoft Visio for process and instrumentation (P&I) diagram AutoCAD software for mechanical engineering drawings. After performing hydraulic leak tests, the prototype was tested using blackstrap molasses 80 o brix which was prepared for fermentation using ilution and inoculums formulations developed in Microsoft Excel for water dilution, yeastand nutrients like (NH 4 ) 2 SO 4, KH 2 PO 4, MgCl 2. A batch mash boiling test conducted on the column showed that the response of tray temperatures exhibited first-order delay behavior with an average lag of 17 minutes and a delay of 50 -65 minutes depending on tray distance from the reboiler. Due to lack of feedback control equipment specifically on-linecomposition analyzers and suitable actuators, continuous control of ethanol composition could not be undertaken. It is planned to procure pertinent control hardware during the next phase of the project. However the batch test gave initial ethanol purity of 80% which decreased as the ethanol content in the still was continuously depleted

Optimisation of Mono-Ethylene Glycol Regeneration Chemistry and Corrosion Inhibition Strategies

This research studies the optimisation of mono-ethylene glycol (MEG) regeneration chemistry and various corrosion inhibition topics related to natural gas pipelines. MEG, used for the inhibition of natural gas hydrate formation, is regenerated to facilitate its reinjection with operational issues often arising during the industrial regeneration process. Research was undertaken to solve several issues identified in industry including optimisation of separation processes, improved corrosion inhibition strategies and development of chemical/physical data relevant to MEG systems