System Identification and IMC-Based PID Control of a Reactive Distillation Process: A Case Study of n-Butyl Acetate Production

2017 ◽  
Vol 31 ◽  
pp. 104-119 ◽  
Author(s):  
Abdulwahab Giwa ◽  
John Olusoji Owolabi ◽  
Saidat Olanipekun Giwa
Keyword(s):  
Transfer Function ◽  
Pid Control ◽  
Butyl Acetate ◽  
Closed Loop ◽  
Reactive Distillation ◽  
Research Work ◽  
Absolute Error ◽  
Distillation Process ◽  
Function Model ◽  
Input Variables

The identification of a reactive distillation system for the production of n-butyl acetate from the esterification reaction between acetic acid and n-butanol has been carried out in this research work. In order to achieve the aim of the research work, a prototype plant of the process was developed using ChemCAD from which dynamics data were generated upon applications of step changes to the reboiler duty and the reflux ratio, which were the input variables of the system. Thereafter, the transfer function of the process, later represented in Simulink environment, was formulated using the dynamics data and with the aid of MATLAB. The simulation of the transfer function model of the system was also carried out for open loop by applying step changes unto the input variables using the developed Simulink model of the system. Thereafter, the closed-loop control system developed also in Simulink environment was simulated by applying step changes to the set-point variable, which was the bottom mole fraction of n-butyl acetate. The results obtained from the simulation of the prototype plant of the reactive distillation process showed ChemCAD to be a powerful tool for steady state and dynamics prototype plant development. Furthermore, good representation and stability were also observed to exist in the system from the formulation and the simulation of the transfer function model of the process, which were carried out with the aid of MATLAB/Simulink. Moreover, the selection of appropriate closed-loop time constant contained in the tuning parameter formulas of IMC-based control system showed that the value suggested by Rivera et al. [1] was very good for this system, compared to those of Chien and Fruehauf [2] and Skogestad [3], because it could give closed-loop dynamic response with comparatively very low values of integral squared error (ISE), integral absolute error (IAE) and integral time absolute error (ITAE) for both proportional-integral (PI) and proportional-integral-derivative (PID) control systems. In addition, the comparison made between the IMC-based tuning approach and other ones (Cohen-Coon, Tyreus-Luyben and Ziegler-Nichols) considered in this work made it known that IMC-based tuning technique was the best among all those considered because its ISE, IAE and ITAE were found to be the lowest for both PI-and PID-controlled cases simulated.

Dynamic Simulation of a Reactive Distillation Process for n-Butyl Acetate Production Using CHEMCAD

2017 ◽  
Vol 30 ◽  
pp. 154-166 ◽  
Author(s):  
Abdulwahab Giwa ◽  
Saidat Olanipekun Giwa
Keyword(s):  
Acetic Acid ◽  
Steady State ◽  
Dynamic Model ◽  
Dynamic Simulation ◽  
Butyl Acetate ◽  
Reactive Distillation ◽  
Esterification Reaction ◽  
Reflux Ratio ◽  
Distillation Process ◽  
Input Variables

The dynamic simulation of a reactive distillation process developed with the aid of CHEMCAD for the production of n-butyl acetate has been carried out in this research work. Originally, the by-product of the process was water. The developed model of the system was first simulated for steady state using a reflux ratio of 3 and a reboiler duty of 1.4 kW in order to have initial values for the mole fractions of the components involved. The model was converted to a dynamic type by activating the “Dynamics” in the “Convergence” tab of the “Run” menu of CHEMCAD. The dynamic model of the system was run using different (positive and negative) step changes applied to the input variables, which were reflux ratio and reboiler duty, of the process. The results obtained from the steady-state simulation showed that only n-butyl acetate and unconverted acetic acid were existing in the reboiler section of the column initially. The dynamic simulation of the process showed that the system was a stable one because it could get settled after some running time of its dynamic model for all the step changes in the two input variables considered. It was also discovered from the simulations carried out that the dynamic responses of the system to negative step changes in reflux ratio were smoother than those obtained when positive step changes were applied to the same input variable. Moreover, the applications of negative step changes to the reboiler duty resulted in decreases in the mole fractions of n-butyl acetate present in the bottom section of the column while the applications of positive changes to the same reboiler duty gave rise to increases in the mole fraction values of the desired product that was collected through the reboiler section of the column. It was discovered from the results obtained that the higher the reboiler duty of the system that was applied in the production of n-butyl acetate from the esterification reaction involving acetic acid and n-butanol, the faster the system was approaching its dynamic steady state.

Inferential Control of Fuel Additive Purity via Reactive Distillation Process

2018 ◽  
Vol 37 ◽  
pp. 127-140 ◽  
Author(s):  
Abdulwahab Giwa ◽  
Edmund Iniyemi Yibo ◽  
Abel Adekanmi Adeyi
Keyword(s):  
Transfer Function ◽  
Mole Fraction ◽  
Pid Controller ◽  
Closed Loop ◽  
Reactive Distillation ◽  
Fuel Additive ◽  
Reflux Ratio ◽  
Transfer Function Model ◽  
Function Model ◽  
Product Temperature

In this work, the control of the mole fraction of a fuel additive being produced in a reactive distillation column has been carried out using proportional-integral-derivative (PID) control. The fuel additive considered in this case was isopropyl alcohol, which was produced from the reaction between propylene and water. To accomplish the work, a ChemCAD model of the process was first developed and simulated to convergence before it was converted to dynamic type from which the dynamic responses of the system were generated and used, with the aid of MATLAB, to develop a transfer function model having the reboiler duty, the reflux ratio and the temperature of the bottom product as the input, the disturbance and the output variables of the process, respectively. The obtained transfer function model was used to develop the open-loop and the closed-loop Simulink models of the process that were also simulated. The closed-loop simulation was carried out with the objective of achieving a fuel additive product with a mole fraction of 0.97, and this was done using a PID controller that was applied inferentially via the product temperature. The results obtained showed that the control of the fuel additive mole fraction could be achieved inferentially, with PID controller tuned with Cohen-Coon and Simulink approaches, using product temperature.

Steady-State Modelling and Simulation of a Reactive Distillation Process for n-Butyl Acetate Production Using CHEMCAD

2017 ◽  
Vol 29 ◽  
pp. 70-80 ◽  
Author(s):  
Abdulwahab Giwa ◽  
Saidat Olanipekun Giwa
Keyword(s):  
Acetic Acid ◽  
Steady State ◽  
Mole Fraction ◽  
Butyl Acetate ◽  
Reactive Distillation ◽  
Esterification Reaction ◽  
Reflux Ratio ◽  
Distillation Process ◽  
Condenser Section ◽  
Steady State Simulation

This work has been carried out to demonstrate the application of a process simulator known as CHEMCAD to the modelling and the simulation of a reactive distillation process used for the production of n-butyl acetate, with water as the by-product, from the esterification reaction between acetic acid and n-butanol. The esterification reaction, which is generally an equilibrium type, was modelled as two kinetic reaction types in the reaction section of the column used, which had 17 stages with the middle section (stages 6 – 12) being the reaction section. A reflux ratio of 3 and reboiler duty of 78 kJ/min as well as 30 mL/min of each of the reactants with 99% molar purity were used for the simulation of the column. The results obtained revealed that the developed model was a valid one because there was a very good agreement between the results and the theoretical knowledge of a distillation column based on the fact that the desired (which was the heavy) product (n-butyl acetate) was found to have the highest mole fraction in the bottom section of the column while the by-product of the process (water) was discovered to have a mole fraction higher than that of n-butyl acetate in the top (condenser) section of the column. Therefore, CHEMCAD has been applied to the steady-state simulation of the reactive distillation process used for the production of n-butyl acetate from the esterification reaction of acetic acid and n-butanol successfully.

Dynamics and Control of Instrumented Harmonic Drives

1995 ◽  
Vol 117 (1) ◽  
pp. 15-19 ◽  
Author(s):  
H. Kazerooni
Keyword(s):  
Transfer Function ◽  
Closed Loop ◽  
Research Work ◽  
High Ratio ◽  
Output Shaft ◽  
Harmonic Drive ◽  
Dynamics And Control ◽  
Radial Forces ◽  
And Control ◽  
Stationary Component

Since torque in harmonic drives is transmitted by a pure couple, harmonic drives do not generate radial forces and therefore can be instrumented with torque sensors without interference from radial forces. The installation of torque sensors on the stationary component of harmonic drives (the Flexipline cup in this research work) produce backdrivability needed for robotic and telerobotic compliant maneuvers [3, 4, 6]. Backdrivability of a harmonic drive, when used as torque increaser, means that the output shaft can be rotated via finite amount of torque. A high ratio harmonic drive is non-backdrivable because its output shaft cannot be turned by applying a torque on it. This article first develops the dynamic behavior of a harmonic drive, in particular the non-backdrivability, in terms of a sensitivity transfer function. The instrumentation of the harmonic drive with torque sensor is then described. This leads to a description of the control architecture which allows modulation of the sensitivity transfer function within the limits established by the closed-loop stability. A set of experiments on an active hand controller, powered by a DC motor coupled to an instrumented harmonic drive, is given to exhibit this method’s limitations.

Recurrent Neural Network based Soft Sensor for Monitoring and Controlling a Reactive Distillation Column

2017 ◽  
Vol 13 (3) ◽  
Author(s):  
Gaurav Kataria ◽  
Kailash Singh
Keyword(s):  
Neural Network ◽  
Recurrent Neural Network ◽  
Distillation Column ◽  
Butyl Acetate ◽  
Closed Loop ◽  
Reactive Distillation ◽  
Dynamic Network ◽  
Open Loop ◽  
Soft Sensor ◽  
Esterification Reaction

Abstract For the real time monitoring of a Reactive Distillation Column (RDC), a Recurrent Neural Network (RNN) based soft sensor has been proposed to estimate the bottoms product composition of the RDC for the synthesis of n-Butyl Acetate using esterification reaction. This soft sensor acts as a measuring element in a closed loop involving a PI controller for the direct control of the RDC’s product concentration. The RNN acts as a dynamic network, which works on the sequential input data and output data with a recurrent connection. While using the RNN based soft sensor in the open loop, it has been observed that the sensor estimated the composition of butyl acetate in the bottoms with such an accuracy that it can be used for the control purpose. Closed loop results demonstrated that the system has been showing precise controlled results and soft sensor is showing small prediction Mean Square Error (MSE) when disturbances in feed flow rate and set point changes are introduced.

scholarly journals Comparing the Effectiveness of Feedback and Load Compensation Techniques in Controlling the Disturbed State of Nominal-T Configuration

2017 ◽  
Vol 2 (7) ◽  
pp. 48
Author(s):  
Thomas Olabode Ale
Keyword(s):  
Transfer Function ◽  
Transmission Line ◽  
State Space ◽  
Research Work ◽  
Phase Lag ◽  
Transfer Function Model ◽  
Function Model ◽  
Load Compensation ◽  
Unit Impulse ◽  
Compensation Technique

Stability of Power system is the ability of a system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with most system variables bounded so that practically the entire system remains intact. This research work stated clearly the effectiveness of the feedback and load compensation techniques in stabilizing a disturbed state of a medium transmission line using a Nominal-T configuration network. In order to achieve the set objectives, Osogbo - Akure transmission line data was obtained from Akure 132kV transmission substation.  This configuration was modeled into transfer function and state space models, the compensator circuit which happens to be the phase lag circuit was also modeled. The transfer function model contained the line parameters extracted from this transmission substation logbook. A state space model was obtained from the transfer function model with a code written in MATLAB environment. The effectiveness of these compensation techniques were compared. The result revealed that load compensation technique offered a perfect compensation to unit step disturbance and unit impulse disturbance. While feedback compensation technique provides perfect compensation to unit impulse disturbance only.

Study on Pilot Transfer Function Model Gain of Closed-Loop Pilot-Vehicle System

2013 ◽  
Vol 706-708 ◽  
pp. 1038-1041
Author(s):  
Lin Li ◽  
Jun Xu ◽  
Fu Lei Zheng
Keyword(s):  
Steady State ◽  
Transfer Function ◽  
Calculation Method ◽  
Closed Loop ◽  
Reference Value ◽  
Transfer Function Model ◽  
Function Model ◽  
Specific Calculation ◽  
Pilot Model ◽  
Vehicle System

Based on the analysis of pilot handling behavior characteristics, this paper establishes the pilot transfer function model. According to the characteristics of closed-loop pilot-vehicle system and the relationship between pilot and flight quality, the specific calculation method of pilot model steady state gain was given. Take the aircraft roll angle manipulation for example, and simulate the pilot's manipulation of aircraft of dynamic process. The results show that: the pilot model steady state gain calculation method is simple and feasible, and have a certain reference value for the analysis of closed-loop pilot-vehicle system.

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