Operation Of Industrial Processes Research Articles

Double loop iterative strategies for hierarchical control of industrial processes

Two novel hierarchical structures are presented which determine the optimum steady-state operation of interconnected industrial processes despite deficiencies in the mathematical model. The techniques are of an iterative type and involve the successive solution of system optimization and model parameter estimation problems, utilizing information feedback from the real process. The computational task of each iterative strategy is divided into two nested iterative loops. The inner loop involves model based computations only, while the outer loop requires measurements from the real process. It is shown that this model based double iterative loop strategy has an important practical advantage in that it reduces the required number of set point changes to real subprocesses in order to achieve optimality. The paper investigates the optimality and convergence conditions of the techniques and gives a simulation example to illustrate the methods.

Knowledge-Based Operation and Control of Industrial Batch Antibiotic Fermentation Process

In batch antibiotic fermentation plant, because fermentation process are usually sensitive to different kinds of disturbances and different operation conditions, which results in the antibiotic production beeing quite variable and uncertain. In this paper, the knowledge base of operation supervisory control and real-time aeration-agitation control are obtained by production experience, theoretical argument and historial data analysis combined with a deal of significant dynamic experiments. The knowledge system works in three ways, (1) combined with characteristic-recognition technique, the system is developed to assess the process situation using knowledge rule to deal with a variety of operation problems during the course of industrial batch process, (2) supervisory of the production performance deciding any change in the control strategy as well as operation (3) determine the satisfactory optimal aeration-agitation condition with adaption to the variations of oxygen demands during the course of fermentation as well as from batch to batch. As a consequence of successful implementation in a pharmaceutical factory, the knowledge-based system means that one can resolve problems in good time to control and operat this industrial fermentation system effectively which was previously inaccessible, the result shows the productivity is increased 7% and the energy cost is reduced 15%.

New model-based double-loop iterative strategy for integrated system optimization and parameter estimation of large-scale industrial processes

A novel hierarchical integrated system optimization and parameter estimation technique is described which determines the optimum steady state operation of an interconnected industrial process in spite of deficiencies in the model. The technique is iterative and involves successive solutions of system optimization and model parameter estimation problems, utilizing information feedback from the real process. Particular emphasis is given to a strategy where the coordination task is divided into two nested iterative loops, with the inner loop optimization containing a self-adaptive model. Derivatives of real process measurements required by the outer loop iteration are also used to update the model. New modifiers are introduced to cater for the output-dependent constraints. This model-based double-loop iterative strategy retains an important practical advantage in that it reduces the required number of set point changes to the real process. Optimality properties and convergence conditions are investigated. A simulation study is also presented.

Model Based Double Iterative Strategy for Integrated System Optimisation and Parameter Estimation of Large Scale Industrial Processes

A novel hierarchical structure is described which determines the optimum steady state operation of interconnected industrial processes inspite of deficiencies in the mathematical model. The technique is of an iterative type and involves successive solutions of system optimization and model parameter estimation problems, utilizing information feedback from the real process. Particular emphasis is given to a strategy where the coordination task is divided into two nested iterative loops. The inner loop involves model based computations only, while the outer loop requires measurements from the real process. It is shown that this model based double iterative strategy has an important practical advantage in that it reduces the required number of set point changes to real subprocesses in order to achieve optimality. The paper investigates the optimality and convergence conditions of the technique and gives a simple simulation example to illustrate the method.

An interpretation of kinetics in the electrohydrodimerization of acrylonitrile to adiponitrile

A mathematical analysis of published experimental data for the electrohydrodimerization of acrylonitrile to adiponitrile during constant current batch electrolysis is presented. The analysis accounts for the production of reported by-products propionitrile and trimer in five step reaction sequences. Overall four possible reaction sequences are proposed and tested against the experimental data. Solution of the simultaneous batch reaction equations is achieved using Runge-Kutta numerical integration methods and good agreement with experimental data is achieved for at least one reaction scheme. By approximating industrial process operation as a continuous stirred tank reactor the effect of current density and other parameters on product distribution is predicted. Yields obtained from this simulation are in reasonable agreement with published levels.

粉粒体層中に形成される疎充てん帯の固体壁に対する入反射条件について

In the design and operation of general industrial particulate processes, the elucidation on the mechanism of the formation of bulk density distribution can be taken to be one of the most urgent problems which should be solved. However, it has not yet been elucidated sufficiently. Then, in this paper, the reflection phenomena of a loose bulk density zone to a solid wall are noticed and fundamentally discussed. As a result, it is pointed out that the sum of the incidence angle and the reflection one to a solid wall should equal to that of the internal friction angle of the particulate material and the wall friction angle. That indicates the fundamental condition of incidence-reflection of a loose bulk density zone to a solid wall. And it is shown that this condition is consistent with the experimental results by X-ray radiographs of the reflected loose bulk density zone to a solid wall, formed in the experiments of plunger penetration. This fact can be taken to be an important information to the fundamental discussions of the bulk density distribution formed in such a vessel of particulate processes.

Chemical and kinetic factors related to hydrogen removal from aluminum

The available data on hydrogen solubility in aluminum are reviewed. Then a mathematical analysis of the kinetics of hydrogen removal is presented. A rather complicated general equation for the hydrogen removal in batch reactors is shown to reduce to more simple expressions for certain values of anew dimensionless group, Ψ/[pct H]. This “dimensionless hydrogen concentration” can be understood to represent the ratio of the ability of hydrogen to diffuse to bubbles during their ascent divided by the capacity of the purge gas to remove hydrogen. When ψ/[pct H] ≼ 0.1, diffusion of hydrogen in the metal is rate controlling. When ψ/Ipct H] 3> 1.0, the purge gas concentration is essentially at equilibrium with the melt, and thermodynamic limitations apply. The mathematical analysis has been used, together with available data on the diffusion coefficient of hydrogen and on mass transfer coefficients, to describe the operation of industrial processes. Then a theoretical analysis of vacuum treatment is presented. The vacuum is seen to remove partially equilibrium limitations found at atmospheric pressure.

Impact of technology transfer on process engineering in developing countries

AbsrracrImperfect o r total lack of any effective technology transfer was a major reason for the very limited usefulness of many post‐war aid programmes. The paper describes the more sensitive regions of oil refining, petrochemicals and industrial chemicals process design, plant installation and operation which bear on the success or failure of the transfer. The first requirement is a satisfactory availability of technical manpower. In sectors where there is a large investment per unit of production a good deal can ‘be left’ t o external engineering organizations but where, as in plastic fabrication, the investment of capital is low the demand on indigenous engineering and science skills will be higher. Some technologies, such as refrigeration or desalination are key ones for seeding the local development of engineering skills. Moreover, with manpower development in mind, the investment programme should be staggered to ensure integration with related sectors. Mechanical engineering is a key skill and plans to develop this in the educational system and investment programme of the receiving country should be part of the strategy. Two very important common failings are inattention to critical detail during the initial stages of a project and the fallacy that the process must be designed to minimize capital investment. Plant reliability in a hostile climate and with poor maintenance is a more important consideration than costs. The paper concludes with lists of critical off‐site and on‐site features and decisions needing attention in the design stage and gives useful guidelines for the selection of plant managers and staff.

Structural changes in iron operating in contact with polymers

1. Mechanical degradation of polymer molecule chains intensifies changes in the substructure of metals, promoting fragmentation of mosaic blocks and increasing the magnitude of lattice microstrains. 2. The degree of structural changes in metals operating in contact with polymers depends on the ambient atmosphere. 3. The degree of mosaic block fragmentation is different for metals in contact with various polymers. 4. Structural changes are accompanied by changes in mechanical properties of the metal surface layers: their microhardness increases and so does the degree of dispersion. 5. Polymers can be used as special lubricants in many industrial metal processing operations.

The Cricondentherm and Cricondenbar Pressures of Multicomponent Hydrocarbon Mixtures

Abstract A method is presented for the accurate calculation of the cricondentherm and cricondenbar pressures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain six and quite possibly any number of components including paraffins, isoparaffins, olefins, acetylenes, naphthenes and aromatics. The approach is similar to that used for calculating critical pressures and cricondentherm and cricondenbar temperatures. The critical pressure, the normal boiling point and the approximate vapor pressure behavior of each component are all that are required. A stepwise calculation procedure is necessary for mixtures containing more than two components. From an analysis of 22 binary systems and 118 mixtures, the average deviation of calculated cricondentherm pressures from reported values is 2.4 per cent. For nine multicomponent mixtures the average deviation is 1 per cent. Considering 19 binary systems and 108 mixtures, the average deviation of calculated cricondenbar pressures from reported values is 1.7 per cent. For 15 multicomponent mixtures, the average deviation is 2.2 per cent. Introduction A knowledge of the phase behavior in the critical region of multicomponent hydrocarbon mixtures is of value both in industrial processing operations and for the optimum operations of gas condensate reservoirs. Accurate methods of calculating the critical temperatures and critical pressures and cricondentherm and cricondenbar temperatures of multicomponent hydrocarbon mixtures are available in the literature. If the cricondentherm and cricondenbar pressures could be calculated with equal accuracy, the entire phase diagram of a multicomponent hydrocarbon mixture could be well approximated. The work of Etter and Kay is limited to systems containing the normal paraffins and has not been tested on systems containing a heavier component than heptane. In addition, the development of their multicomponent equations is based upon a limited number of mixtures containing from three to six components. Silverman and Thodos have considered systems containing both paraffinic and non-paraffinic hydrocarbons, but their correlation is limited to binary systems and is highly inaccurate for methane systems. Eilerts has done extensive work on the cricondenbar pressure; he has produced an excellent correlation for binary systems. However, his procedure for multicomponent mixtures is chiefly useful for highly complex mixtures requiring a knowledge of the vapor-liquid equilibrium behavior of the mixtures; he has not considered the cricondentherm pressure. The objective of this study was the development of an accurate and rapid method for the calculation of the cricondentherm and cricondenbar pressures of multicomponent mixtures containing all types of hydrocarbons and having a wide volatility range. The approach that was adopted is similar to that used by Grieves and Thodos for cricondentherm and cricondenbar temperatures and for critical pressures. However, methane systems had to be considered separately and a modified stepwise calculation procedure was utilized for the cricondentherm pressure. The correlations were developed in a manner similar to those for critical pressures and cricondentherm and cricondenbar temperatures. Based upon binary data reported in the literature it was observed that the ratios of cricondentherm and cricondenbar pressure to the pseudocritical pressure (molar average), pt/ppc and pp/ppc respectively, in two-component systems depended upon the mole fraction of this low-boiling component and upon the diversity in properties of the two components. A dimensionless boiling-point parameter T'b/Tb was chosen to represent the diversity in properties of the components. For a binary system, T't, is the molar average of the normal boiling points of the two components involved. SPEJ P. 240ˆ