Abel Adekanmi Adeyi

Application of Model Predictive Control to Renewable Energy Development via Reactive Distillation Process

Reactive distillation is a process that combines chemical reaction and separation in a single piece of equipment (distillation column). The process has a lot of benefits especially for those reactions occurring at conditions suitable for the distillation of the process components, and these result in significant economic advantages. However, owing to the complexities resulting from the integration of reaction and separation, its control is still a challenge to process engineers because it requires a control method that is robust enough to handle its complexities. Therefore, in this work, model predictive control (MPC) has been applied to a reactive distillation process used for developing a renewable energy known as biodiesel. The control algorithm of the MPC was formulated with the aid of MPC toolbox of MATLAB/Simulink in which the closed-loop models of the process were developed and simulated. The analysis of the results obtained from the simulations carried out for the optimization of the tuning parameters revealed that, among the tuning parameters considered, integral absolute error of the control system was less affected by the control horizon because its p-value was greater than 0.05 based on 95% confidence level. Furthermore, the simulation of the closed-loop system of the process using model predictive control tuned with control horizon of 11, prediction horizon of 18, weight on manipulated variable rate of 0.05 and weight on output variable of 2.17, which were the optimum parameters obtained using Excel Solver, showed that the system was well handled by the controller under servo control because it was able to get settled at desired mole fractions within 60 min. However, the settling time recorded in the case of regulatory control system of the process with the same controller was found not to be encouraging. Therefore, it is recommended that further work should be carried out on this subject matter in an attempt to obtain tuning parameters that will make the settling time of the closed-loop system of the process under regulatory control simulation very reasonable.

Control of a Reactive Distillation Process Using Model Predictive Control Toolbox of MATLAB

This research work has been carried out to investigate the application of the Model Predictive Control Toolbox contained in MATLAB in controlling a reactive distillation process used for the production of a biodiesel, the model of which was obtained from the work of Giwa et al.1. The optimum values of the model predictive control parameters were obtained by running the mfile program written for the implementation of the control simulation varying the model predictive control parameters (control horizon and prediction horizon) and recording the corresponding integral squared error (ISE). Thereafter, using the obtain optimum value of 5 and 15 for control horizon and prediction horizon respectively as well as a manipulated variable rate weight of 0.025 and an output variable rate weight of 1.10, various steps were applied to the setpoint of the controlled variable and the responses plotted. The results given by the simulations carried out by varying the model predictive control parameters (control horizon and prediction horizon) for the control of the system revealed that optimizing the control parameters is better than arbitrary choosing. Also, the simulation of the developed model predictive control system of the process showed that its performance was better than those used to control the same process using a proportional-integral-derivative (PID) controller tuned with Cohen-Coon and Ziegler-Nichols techniques. It has, thus, been discovered that the Model Predictive Control Toolbox of MATLAB can be applied successfully to control a reactive distillation process in order to obtain better performance than that obtained from a PID controller tuned with Cohen-Coon and Ziegler-Nichols methods.

Kinetics and Isotherm Studies of Liquid Phase Adsorption of Cationic Dye onto Chitosan Synthesized from Crab Shells

The use of cheap and eco-friendly adsorbents studied as an alternative to activated carbon for removal of dyes from wastewater is the focus of this paper. Chitosan, which was produced from food industry waste (crab shells), was synthesized, characterized and utilized as adsorbent to remove cationic dye, basic blue, from wastewater by adsorption. Characteristics of the synthesized chitosan biosorbents was established using scanning electron microscope (SEM), and Fourier Transform Infra-Red (FTIR) spectroscopy. Experiments were conducted in batch forms to investigate the effects of contact time, initial dye concentration and adsorbent dosage. Kinetic and isotherm analysis of the adsorption process were also carried out. The results obtained revealed that removal efficiency of the chitosan was increased as the contact time and chitosan biosorbent dose were increased, but a decrease with increasing initial concentration of basic dye was observed. The pseudo-second order reaction model was found to describe the biosorption process best, with chemisorption as the rate limiting step. The maximum colour removal efficiencies of chitosan at dosage of 4 g for time duration of 90 min was found to be 91.88% of the dye from a solution of 80 ppm. The pseudo-second order kinetic model was also seen to agree very well with the dynamic behaviour of the adsorption of basic blue on chitosan under different contact time, initial dye concentrations and adsorbent dosages. The dynamic behaviour of adsorption of basic blue onto chitosan has the model fitness in the following order: pseudo-second order > Elovich model > pseudo-first order. The Elovich equation was found to be the best fit equilibrium isotherm for the sorption of basic blue onto chitosan based on linearized correlation coefficient. Moreover, the equilibrium isotherm has its model fitness to be in the order of Elovich model > Langmuir model > Freundlich model.

Cascade PID Control of a Reactive Distillation Process for Biodiesel Production: A Comparison with Conventional PID Control

The combination of chemical reaction and distillation, which is analogous to inserting a chemical reactor into a distillation column, is a phenomenon that can be accomplished using a single piece of equipment known as a reactive distillation column, and the phenomenon is, thereby, referred to as reactive distillation process. Because of this combination, a lot of benefits such as improving reaction conversion, suppressing side reactions and utilizing heat of reaction for mass transfer operation can be achieved. However, this combination has made the control of this process a little bit challenging because of some disturbances that normally affect its smooth running. Therefore, cascade control method, being a type that can be used to handle any disturbance before it affects the main process, is applied in this work to carry out the control of a biodiesel reactive distillation process using proportional-integral-derivative (PID) control algorithm. The responses of the process towards the applications of step changes to the input variable (reboiler duty) of the process revealed that it was stable because it could attain steady states. Also, the closed-loop simulations showed that cascade PID controller was better for the control of the process than the conventional PID controller owing to the fact that the responses of the cascade PID control system, upon the application of step changes to the set-point value of the controlled variable, were found to get to the desired setpoint faster and in a better way than those of the conventional PID control system. Moreover, the superiority of the cascade PID controller over the conventional one was demonstrated by the estimation of the integral absolute error (IAE) and integral squared error (ISE) of the cascade control system, which were obtained to be less than those of the conventional PID control system.

Inferential Control of Fuel Additive Purity via Reactive Distillation Process

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.

Comparative Bioremediation of Diesel Oil Bearing Soil by Pseudomonas aeruginosa and Pseudomonas fluorescence

The quality of life on earth is directly linked to the overall quality of the environment. The natural ecosystem encompasses all living and non-living things existing on earth naturally. It is an environment that interacts with all living species, but which may be contaminated with diesel a derivative of hydrocarbons. Diesel spills contaminate both aquatic and terrestrial environments. To prevent the environmental and health risks of this, remediation needs to be advanced. Bioremediation, degradation by microbes, is one of the suitable methods for cleaning diesel contamination. In the present work, the biodegradation of diesel oil contaminated soil has been investigated comparatively with Pseudomonas aeruginosa and Pseudomonas fluorescence coupled with fertilizer as essential nutrients. Based on observations carried out in 18 days, Pseudomonas aeruginosa alone as well as in the presence of essential inorganic nutrients was found to exhibit higher remediation potential in degrading soil contaminated with diesel oil than Pseudomonas fluorescence.