Sharif Digital Repository

Plantwide control plays a significant role in both industrial and academic fields. In this work, two plantwide control methodologies, “Self-Optimiaing Control (SOC)” and “Integrated Framework of Simulation and Heuristic (IFSH)”, have been applied on toluene hydrodealkilation process. Consequently, the performance of each methodology has been evaluated and compared due to the same process disturbance scenarios.The results are as follows: Although self-optimiaing control includes lots of optimization efforts, dynamic performance of the plant dose not exhibit notable differences. Therefore, Integrated framework of simulation and heuristic methodology is preferable for hydrodealkilation... 

One of the main challenges in managing flow batteries usage is estimating their state of charge. Since The concentration of ions in the battery indicates the battery's charge and, on the other hand, the sensors for measuring the concentration are expensive, observers should be used to estimate the concentrations of the ions in the battery. This work is done by measuring the cell voltage, and finally, using the mathematical model of the battery, the amount of concentrations and state of charge is calculated. In this work, a vanadium flow battery was initially modeled accurately and mechanistically using COMSOL software to replace an actual flow battery in subsequent studies. Also, two... 

Two-phase fluid flow physics in porous media is applied in various fields. Studies have shown that wettability and surface tension, which represent fluid-rock and fluid-fluid interactions, have a significant effect on the dynamics of the immiscible displacement. Although the effects of wettability and surface tension on the macroscopic behavior of fluid flow are known, there is less understanding of it at the micro scale. Considering the essential role of wettability and surface tension in various fields, this project seeks to investigate the effects of wettability and surface tension on the movement and distribution of fluids and the dominant displacement mechanisms within the porous media... 

Multi-Scale finite volume (MSFV) method have been developed and applied for multiphase flow in porous media. The most important advantage of MSFV method is its computational efficiency. In this thesis we apply and implement this method to porous media simulation. Then, computational parameters such as coarsening ratio, effect of threshold on adaptive computation and different boundary conditions for computing basis functions are investigated. The two difficulties of sMSFV method are problems with high permeability contrast and problems with high course grid aspect ratio which are considered. In standard MSFV (sMSFV) method reduced boundary condition is used to determine the basis and... 

In this thesis, a typical dynamic model of syngas fermentation, refered as hybrid method for biofuels production, coupled with a distillation column is developed in SimDFBA. The bioreactor is simulated in MATLAB/Simulink by using Clostridium ljungdahlii acetogenic micro-organism metabolic network. Bioreactor modeling is accomplished with a bubble column reactor in both liquid and gas phases, while the separator was simulated with ASPEN. PDE equiations of bioreactor modeing are dicretized to ODE equation by using QUICK scheme of finite volume method. A new econometric optimization study for outlet gas purification through a pressure swing adsorption unit to recycle relatively pure hydrogen is... 

Wettability alteration is the main mechanism for enhancing oil recovery in carbonate reservoirs during low salinity or engineered water flooding (LS/EWF), though it is a complex process due to the high heterogeneity of rock. During LS/EWF, wettability alteration occurs as a result of electrochemical interactions at the interface between carbonate rock and brine. One of the most critical factors affecting these interactions, and the wettability alteration process, is the presence of anhydrite impurities in the carbonate rock. Therefore, the success of LS/EWF in carbonate reservoirs lies on understanding the role of impurities like anhydrite from both geochemical and dissolution perspectives.... 

In this thesis we are about to simulate and control an MTBE production unit which use membrane instead of azeotropic distillation tower. At first an MTBE Production Unit with two distillation towers in separation part is simulated whit traditional method. One of these distillation towers is azeotropic. Then azeotropic distillation tower is replaced with membrane.After simulation the unit with best process indicators is selected. The goal is minimization of fixed and operating costs.In the next stage the best control loops in each unit is selected. The unit with best control indicators is determined. Control indicators are load rejection and set point tracking. All units have been simulated... 

Optimization always has been a major industrial field of study. Optimization is the process of finding the best result based on some events. In design, construction and maintenance of any kind of engineering system ,engineers must take a lot of decisions in the case of management or engineering at different levels in order to minimize the attempts to reach the optimum conditions and obtain the maximum profit on the other side. high speed of processing and litle time for calculations by using computers is very common nowadays which is caused in many improvements in optimization approaches. In this thesis some different classical optimization methods have been applied on Williams-Otto reactor... 

Artificial immune systems (AIS) constitute a novel area of bio-inspired computing. Biological models of the natural immune system, in particular the theories of clonal selection, immune networks and negative selection, have provided the inspiration for AIS algorithms. Moreover, such algorithms have been successfully employed in a wide variety of different areas, but have not been applied for chemical processes yet. One important part of the immune systems is lymphatic system. Clonal selection is one of the few algorithms that belong to the family of AIS techniques. Clonal selection algorithm is the computational implementation of the clonal selection principle. In this project, we have... 

In batch cooling crystallization, the crucial control problem is to design a temperature trajectory which produces a desired crystal size distribution. Here, a completely different solution is presented. Designing model-based controller for crystallizer has two steps; first step is determining optimal temperature trajectory which is some kind of feedforward control, second step is adding feedback controller (with manipulated variable of jacket temperature or cooling flow) to track the set-point (determined in first step) and rejecting possible disturbances. Traditionally, determining optimal temperature of crystallizer is done by using calculus of variations of distributed system. In this... 

In this thesis, a reduced model of a distributed one-dimensional Solid Oxide Fuel Cell (SOFC) system is presented. Consequently the reduced model is used to estimate the states of the exact model. The reduced model is derived using the exact solution of the distributed model and implementing the Karhunen-Loève-Galerkin procedure. To achieve an exact solution of the distributed model, method of lines is used. In the method of lines, accuracy of the solution depends on the number of grid points. To increase the accuracy, the number of grid points should be increased which will lead to a high order dynamic model. Such a model is not suitable for state estimation, optimization or control... 

There is many Nonlinear process in industry which are not control able with classic control methods. Model predictive control is a very useful method of control for nonlinear processes.
The nonlinearity of polymerization reactors are considerable in modeling, simulation, dynamic study and control .Design of free radical polymerization in continues reactors are very populated in industries.in this thesis modeling of free radical polymerization for polyvinyl acetate in industrial scale is studied for dynamic behavior studies of CSTR and design of Model predictive control system for the CSTR.
One of the important challenges in control system for this reactor is the existence of delay... 

this is one of the most widely used is the weighted residual method. The advantages of this method is likely to reach an appropriate solution is (in this project collocation method for solving systems of differential equations is used). After solving steady-state model with the lowest number of variables come to turn the control measures, including non-linear design of a Kalman Filter incentives that could be the orthogonal modulation system (which requires less computational time and good accuracy) as a representative of the system in the state estimation, optimization and control system used. In the end, offering a range of control methods such as multivariate linear and nonlinear... 

Selecting an appropriate control structure is an important subject in the design of control systems. Distillation column is one of the most popular and widely used unit operations in industry which complete understanding of its operability and controllability is one of the most important issues in the process control engineering. The present work studies the method of Output Controllability Index for nonlinear systems and compares it with Relative Gain Array and Condition Number. By using this index, the extent of intrinsic controllability of a process can be identified quantitatively in the absence of any controller. Also, the controllability of the process can be stated numerically or... 

Recently experiences in chemical processes approved that periodic operation for some of the processes (e.g. ion exchangers, activated sludge tanks, etc) were being successful. The performance and/or effectiveness of process due to periodic changes in the systems input, such as concentration, feed or coolant temperature and other possibilities, typically express whether in term of yield or selectivity improvement. Though, prominent issue in this type of dynamical control problem is optimal frequency and amplitude in the cycle. Supporting mathematics, include two main approaches: (1) the Hamilton-Jacobi approach based on the maximum principle and (2) a frequency domain approach using second... 

In this work, a model was presented for an MCFC fuel cell with internal reforming and combustion chamber. The model consists of mass and heat transfer equations beside the chemical and electrochemical reaction rate equations. Velocity distribution due to reactions and temperature distribution along the cell is considered. The model has been simulated in steady state form using finite difference method in MATLAB package environment accompanied by the analysis of the dynamic behavior of cell using method of lines in Simulink environment. Simulation results have been validated with experimental data extracted from literature. The last part of the work concerns with sensitivity analysis of some... 

The purpose of this project is to study the interactions between process design and process control in a gas transmission pipeline. A part of gas pipeline in two conditions is considered, 1: The gas pipeline that has nominal structure and 2: the one with optimal structure by using an economic objective function that considers the capital and operation cost. To aim this object, by creation of an interface to communicate decision variables between MATLA (as an optimizer and controller engine) and Aspen HYSYS (as a pipeline simulator) is attempted to design and then control the pipeline with to control algorithms PI and MPC. Finally the interaction between process design and process is... 

In recent years, fuel cells have been proposed as an alternative option to conventional energy conversion systems. Fuel cell is an electrochemical system that can convert chemical energy to electrical energy without combustion. High efficiency, low temperature performance, poor pollution, good reliability, flexibility in the production potential, low start-up time and high life expectancy are the major advantages of this system. The most important barriers to the use of fuel cells are high cost polymer membrane and using expensive platinum catalysts. Modeling of fuel cells in general will meet two objectives. The first, due to the complexity of the processes taking place within the cell,... 

High efficiency and low-emission fuel cells have the capacity to replace fossil fuels for energy supply concerns. Solid oxide fuel cells operate in relatively high temperature and have power plant applications. Hence, they are acquainted to be coupled with cycle gas turbine to reduce the cost and increase the overall system efficiency. The control of these hybrid systems is so important. Due to the system nonlinearity and having more than one controlled variable, its control with classic methods would be difficult. The model based predictive control is used as an alternative to mitigate these difficulties. In addition to their high performance, their extension to the multivariate case would... 

In recent years, due to the development of smart wells, optimization of waterflooding by injection/production rate control has receivedsome interests. We can postpone breakthrough time and increase the sweep efficiency by using inflow control valves (ICV). Due to complexity of reservoirs, existence of constraints and numerous influencing parameters, we need a robust and suitable optimization approach to overcome such problems. In this thesis, model predictive control (MPC) is chosen to be our optimization approach. MPC is suitable for constrained multi variable functions. Genetic algorithm is was chosenas optimizer. Eclipse reservoir simulator was used for reservoir simulation. Eclipse input...