Stability of the 13C column separation in industrial mode of operation
Based on the original cryogenic column conceived and built by National Institute for Research and Development of Isotopic and Molecular Technologies Cluj-Napoca, it is necessary to implement control algorithms for the industrial mode of operation of this equipment, in order to produce some chemical compounds with higher concentration in (13C), compounds asked in various domains. The present work deals with column efficiency analysis and stability in industrial mode of operation.
Robust Fractional Order Controllers for Distributed Systems
An important step in any control system design is to account for the fault tolerance desired for the system at an early stage of development. It is not enough to test the fault tolerance after the implementation, as the tuning possibilities may be insufficient to ensure tolerance for an unexpected fault, it is better to monitor at the design phase. The control research community is interested in fault tolerant control system design, but only specific applications are addressed. The present paper deals with such a fault tolerant control system for a complex chemical process, the (13C) isotope separation columns cascade. To ensure the robustness to uncertainties of the designed system, the controller is a fractional order type, tuned using the particle swarm optimization method. The simulation results were obtained using the TrueTime Matlab toolbox.
Preliminaries Regarding General Modeling of the Cryogenic Distillation with Application to ( 13 C) Iso
There are many domains of life, techniques, industry, environmental analysis and protection, where the heavier isotope are useful. The predominant isotope of the carbon is ( 12 C), with the natural abundance of 98.9%, but as tracer in many applica- tion is asked the ( 13 C) isotope, initially with the concentration of 1.1%. For industrial output and higher concentration, the method of the cryogenic distillation is a proper solution. The paper deals with the general analysis of the operation for the ( 12 C) isotope Generally, models are abstract structures based on "essen- tial" aspects of the reality and dedicated to a particular purpose. Here, worthy of mention are: design models, operational mod- els for steady-state operating points and for dynamic behavior and structural models, special for control. The operational models may be divided in qualitative models - here is the problem of isotope concentration - and quantita- tive models, based on: mass balance, component balance, en- ergy balance. These models are functions of the main variables: temperature, concentration and pressure distribution, density, holdup, etc. The production of the ( 13 C) isotope is based on a special case of distillation; cryogenic distillation. Distillation is a very common method used to separate two (ore more) components in a trayed or packed distillation col- umn. Cryogenic distillation columns are operated at extremely low temperatures (80-100 o K) to separate the desired compo- nent and to "waste" useless component. For a continuous pro- duction, it is necessary to divide the column in a stripping sec- tion - here the upper part - and in an enriching (rectifying) section. The material of isotope natural abundance is fed at an intermediate part (F) of the column. The depleted material (waste) is withdrawn at approximately the same rate like the feed flow rate (F) in the upper end of the column. The enriched material is withdrawn, usually at a much smaller rate (P), from the bottom end of the column. The separation achieved is less under condition of steady production (P) than it is at total re- flux (no withdrawal, infinite reflux). For a binary mixture, if (N) and (n) are the mole-fraction in the liquid phase and, respectively, in the gas, for a separating element, the "simple process separation factor" (1) is: