Determination Of Optimal Operating Conditions Research Articles

Determination of optimum operating conditions of an acidification reactor treating a chemical synthesis-based pharmaceutical wastewater

In this study, the optimum operating conditions of a lab-scale completely stirred acidogenic reactor treating a chemical synthesis-based pharmaceutical wastewater were determined. Individual effects of hydraulic retention time (HRT), organic loading rate (OLR) and pH on the degree of acidification were investigated at a mesophilic temperature (35 ± 1 °C), for HRT in the range 8–24 h, OLR up to 14 kg COD/m 3 d and pH in the range of 5.0–6.3. A maximum acidification level of 44% and COD removal efficiency of 13%, were obtained at an OLR of 13 kg COD/m 3 d at pH of 5.5 ± 0.1 with an HRT of 12 h. Under these conditions, acetic, propionic and n-butyric acids were found to be predominant volatile fatty acids in the acidogenic reactor.

Multi-objective optimization for chemical processes and controller design: Approximating and classifying the Pareto domain

In recent years, the development of multi-objective optimization techniques for simultaneously optimizing multiple and conflicting objectives have received wide attention in the literature. In this paper, three algorithms for generating the Pareto domain were studied for their efficiency to generate a well-defined Pareto domain as a first step in the development of a multi-objective optimization strategy. Twelve standard test cases, which have been used frequently in the literature, were considered along with two engineering problems, namely, the determination of optimum operating conditions for the production of gluconic acid and the determination of optimal tuning parameters for a PI controller. These multi-objective optimization problems were selected in order to evaluate the robustness and versatility of the algorithms studied. The results of three of these test cases and both engineering problems are presented. The results identify a robust optimization strategy that generates a Pareto domain using a dual population evolutionary algorithm and classifies it using net flow, a technique that incorporates the knowledge of an expert into the optimization routine.

Stochastic response surface optimization via an enhanced Nelder–Mead simplex search procedure

There is abundant literature on response surface methodology about how the Nelder–Mead simplex search (NMSS) procedure can be applied to the determination of optimum operating conditions for deterministic response surface functions. However, searching for the optima of stochastic functions seems a more realistic task for many practical situations. This is particularly true when the response surface functions have not been fitted or the physical models may not even exist, so gradient information is not available. In such cases, it might be interesting to employ simplex-search-type methods ‘on-line’ to sequentially optimize the actual response of interest. Toward that end, an enhanced NMSS is proposed in this article to explore the terrains of empirical (or experimental) optimization adaptively where the known response surface function incorporates additional white-noise errors. Internal modifications to basic operations in NMSS are made primarily according to some statistical process control statistics in estimating response variation and confidence bands for mean responses. A series of graphical illustrations are presented to give an insight into the way the new simplex-search-type approach accurately anchors the true optimum point in noisy environments. As evidenced by a wide variety of simulation studies on the published response functions, the new method proves to perform much better than two recent modifications of NMSS in solution quality achieved while applied to the stochastic response surface optimization problems.

Design of grinding factors based on response surface methodology

The presented paper describes a systematic methodology for empirical modelling and optimization of the plunge centreless grinding process. The assessment of microgeometric quality defining quantity is supported by post-process surface roughness measurements. The design of grinding factors is based on response surface methodology, which integrates a design of experiment, regression modelling technique for fitting a model to experimental data and basic optimization. Central composite response surface design has been employed to develop a second-order surface roughness model. The model has been fully constructed by determination of its structure and regression coefficients. The final goal of experimental study focuses on determination of optimum centreless grinding system set-up and operating conditions for minimization of surface roughness. The computer-aided single-objective optimization, solved by non-linear programming and genetic algorithm, is applied. The results of two different optimization approaches for determination of optimal operating conditions are compared. Finally, further research directions are presented.

Optimization of Operating Conditions in Rice Heat Blast Process for Chinese Rice Wine Production by Combinational Utilization of Neural Network and Genetic Algorithms

The rice heat blast process is a novel technique for gelatinizing raw starch. It uses heated air to replace steam for processing rice under high temperature fluidization in a short time period. This is a new technique for making rice wine with the characteristics of easy storage and zero water pollution. This study focused on three major performance indexes (starch gelatinization ratio, total fat content, and amino nitrogen content in the roasted rice), which largely affect the performance of the rice heat blast process and the rice wine quality. The relationship between these performance indexes and the corresponding operation variables were modeled by an artificial neural network (ANN) via learning sets of experimental data. Based on the ANN models obtained, genetic algorithms were used to optimize the operating conditions of the rice heat blast process. The results showed the power in determination of optimal operating conditions by the combinational utilization of artificial neural network and genetic algorithms.

Determination of optimum operating conditions based on energy requirements for particle coating in a dry process

This paper describes the method for determining the optimum operating conditions of equipment on dry coating processes based on the energy requirement for immobilizing the fine materials on the surface of coarser particles. In the model system consisting of the spherical copper particles (host particles) and the submicron-sized fine alumina particles (guest particles), the guests are immobilized by embedding onto the surface of the host with a high-speed elliptical-rotor-type powder mixer (HEM) to which Zirconia beads are added. The embedding process is approximated by the intruding process of the diamond indenter at the measurement of Vickers hardness of copper plate, and the energy required for embedding is estimated. We have found that both the allowable deformation of copper particles in a single compression by the rotor and the depth of embedding of alumina particles are important parameters in the determination of operating conditions (the rotor speed and the operation time). When the allowable deformation is set to be approximately 0.5% (corresponding to the strain in the intermediate region between the elastic and plastic ones of copper particle), the shape and size distribution of copper particles can be maintained throughout the coating process. Furthermore, the surface condition of coated particles can be controlled quantitatively by the depth of embedding.

Residence time and conversion in the extrusion of chemically reactive materials

AbstractTwin‐screw extruders offer improved control of the residence time distribution (RTD) and mixing in materials such as plastics, rubber and food. Based on the flow and the heat transfer characteristics obtained for a self‐wiping, co‐rotating twinscrew extruder, the residence time and chemical reaction are studied by tracking the particles. For normally starve‐fed twin‐screw extruders, the length of the completely filled section is calculated as function of the process variables using the coupling of the flow with the die. With a model of the solid conveying section, the RTD for the whole extruder is calculated for corn meal at different screw speeds and flow rates. The calculated variation of RTD with the screw speed and the flow rate yields good agreement with observations from many experiments. The variation of the fully filled section length, chemical conversion and mixing effectiveness are also obtained under different operation conditions. Most of the results are in qualitative agreement with experimental results and may be used as guidelines for extruder design and determination of optimal operating conditions.

Analysis of spectral regrowth of weakly nonlinear power amplifiers

Power amplifiers (PAs) are important components in a wireless communications system. Linearity and efficiency are two desirable but conflicting requirements, All PAs exhibit varying degrees of nonlinearity which causes spectral regrowth and adjacent channel interference. Based on the behavior model of the PA and statistics of the input, it is possible to analyze spectral regrowth in the output. Existing results assume that the input is Gaussian whereas our analysis does not. Analytical results on spectral regrowth are useful in finding optimal operating conditions of the PA so that maximum efficiency is achieved without violating the out-of-band emission requirement.

Equilibrium Theory for Pressure-Swing Adsorption. 4. Optimizations for Trace Separation and Purification in Two-Component Adsorption

This paper applies local equilibrium theory to analyze pressure-swing adsorption with short dimensionless contact times for systems with two adsorbable components present in trace amounts in an inert carrier gas. We are interested in finding optimal operating conditions for both separation and purification problems with nonlinear isotherms. We consider Langmuirian systems only; however, several concepts illustrated in this paper apply irrespective of the type of isotherm. By minimizing appropriate objective functions, at the periodic state and for the purification process, the purge step is found to be of short duration, corresponding to low volumetric purge-to-feed ratios and a high degree of incomplete regeneration. In the separation process, higher or lower degrees of regeneration may be appropriate depending on whether the goal is to enrich the purge in the impurities or to recover the light component as product.

97/03730 Development of regenerable copper-based sorbents for hot gas desulfurization

The implementation of hot gas cleanup systems heavily depends on the development of regenerable sorbents for removal of sulfur-containing species (mainly H{sub 2}S) from the fuel gas stream at elevated temperatures (i.e., >350 C) from levels of several thousand ppm down to a few ppm, over many sulfidation/regeneration cycles. In addition, these sorbents must have high sulfur capacity, good sulfidation kinetics, good mechanical strength, and good chemical and structural stability over multicycle testing. Zinc-based sorbents, such as zinc titanates, are the leading contenders for hot gas desulfurization. However, these sorbents have been shown to suffer from zinc volatilization at elevated temperatures, resulting in sorbent deterioration and losses through attrition, loss of reactivity, leading to increasing sorbent replacement costs and overall cost of electricity. Copper-based sorbents do not suffer from volatilization problems due to the high melting point of the metal. However, bulk copper oxide is easily reduced to elemental copper in a reducing fuel gas environment, which in turn results in insufficient level of desulfurization. Fortunately, the sorbent desulfurization performance can be greatly enhanced by combining copper oxide with other oxides to minimize or prevent sorbent reduction during the sulfidation stage. This paper reports on research conducted to-date on themore » development of copper-based sorbents for hot coal gas desulfurization. The results of packed-bed experiments carried out for the determination of optimum operating conditions and for the evaluation of the long-term durability and regenerability of selected copper chromite sorbents are presented and discussed.« less

Feasibility of Be Analysis For Geologic Materials Using Epma

Microanalytical techniques for the analysis of beryllium using the electron probe have been evaluated for Be metal, Be-rich silicate minerals, and three Be-rich synthetic silicate glasses. Despite difficulties typical of ultra-light element analysis in geologic materials, quantitative data for Be may be obtainable through careful analytical measurements, determination of optimal operating conditions, and consideration of parameters such as sample orientation and beam-induced migration.Analyses for Be were obtained using a layered synthetic microstructure “crystal” (Mo/B4C) on the JEOL 8900 electron microprobe at the USGS, Denver, Colorado. The optimum accelerating voltage for Be detection was determined to be 8kV (Fig.l). Beryllium analyses in glass and mineral phases were successful using a beam current of 30nA and a 50 μm beam diameter. Due to low count rates, peak counting times of 10 minutes (beryl) and 30 minutes (glass) were required in order to achieve reasonable counting statistics and detection limits.

Effect of Glass Lubricant Behavior on the Surface Quality of Extrudates in Glass-Lubricated Hot Extrusion

In glass lubricated hot extrusion, the behavior of the glass lubricant is quite sensitive to process conditions and die design. The use of improper conditions can lead to surface defects. The typical thickness of the glass film is very small (∼ 40 microns), making measurement difficult and numerical analysis of lubricant behavior impractical. A mathematical model for glass lubrication is presented which enables an analysis of the effects of processing conditions on the thickness, flow stability and supply of lubricant over the stroke of the extrusion press. Correlations are drawn between predictions of lubricant thickness and flow stability and experimental observations of extrudate surface quality. Thus, this model can be used in the determination of optimum operating conditions for glass lubricated hot extrusion.

Maximum power density analysis of an irreversible Joule - Brayton engine

A performance analysis based on a power density criterion has been carried out for an irreversible Joule - Brayton (JB) heat engine. The results obtained were compared with those of a power performance criterion. It is shown that design parameters at maximum power density lead to smaller and more efficient JB engines than an engine working at maximum power output conditions. Due to irreversibilities in the heat engine, the power and thermal efficiency will reduce by a certain amount, however the maximum power density conditions still give a better performance than at the maximum power output conditions. The analysis demonstrated in this paper may provide a basis for the determination of optimal operating conditions and the design parameters for real JB heat engines.

Optimisation and scale-up of batch chemical reactors: Impact of safety constraints

This work presents a methodology in order to determine the operating conditions simultaneously optimising the chemical yield and considering the safety aspect. The aim is to determine time evolutions of the reacting mixture temperature and the feed rate of reactants which not only define a maximal efficiency but also involve an adequate generated heat which can be removed by the cooling system. The problem is converted into a non-linear programming problem which is solved by standard Non Linear Programming. The methodology is validated on an industrial synthesis of a pharmaceutical product which presents high exothermicity. Results show the influence of the safety and economical constraints on the determination of optimal operating conditions. Especially, when no constraints are considered, the optimal solution is to operate batch-wise. When the generated heat is limited, the reactant has to be introduced according to a specified feed-rate profile. Experiments carried-out in a 1 litre pilot plant reactor confirm the optimisation results. This reactor is equipped with a control methodology based on temperature control through pressure which allows to remove a large amount of heat through the condenser. Then, scale-up to a 8 m 3 glass-line jacketed reactor shows the relevance of the constrained optimisation approach.

Modeling and Optimization of a Tunnel Crape Dryer

ABSTRACT A mathematical model of a tunnel dryer for the dehydration of grapes is presented and applied to the determination of optimal operating conditions of the dryer. The dryer is of semi-batch structure, operating with trucks and trays. The cycle period is determined by meeting appropriate quality specifications for the final product. The nominal conditions were evaluated bv suitably minimizing. the total fuel demand, expressed as fuel consumption to production capacity, under some constraints regarding the production rate of the dryer and the maximum permissible air temperature. An nominal air humidity value was evaluated suggesting a minimum cycle period value for the production capacity and fuel demand. The nominal conditions required operation of the dryer on the maximum permissible air temperature. The optimum operation was evaluated by maximizing the total profit resulting from the operation of the dryer. The optimization variables were temperature and humidity of the drying air stream. A charte...

Phase inversion: a method for separation of fine liquid-liquid dispersions

The present study concerns the separation of fine liquid-liquid dispersions having mean droplet diameters between 20 and 100 μm by phase inversion. A theoretical model based on gravity separation is proposed. Two modes of operation of the settling device are studied: without and with bed formation. The results are compared with the theoretical predictions. As can be seen, good operating conditions always lead to high separation efficiencies and all droplets having diameters above 40 μm can be practically removed. It is shown that the bed formation allows one to increase throughput and efficiency considerably and that in this mode of operation the difference between predicted and obtained separation efficiencies is negligible. Relationships are given which allows the determination of optimal operating conditions, leading to high efficiencies.

Study of the fouling of inorganic membranes by acidified milks using scanning electron microscopy and electrophoresis. II. Membrane with pore diameter 0·8 μm

SummaryThe functioning of an inorganic microfiltration membrane (Membralox-SCT) with an average pore diameter of 0·8 μm, used for processing milk, acidified milk and lactic coagulum, was studied using dynamic and static conditions. Milk processing (pH 6·62) gave acceptable rates of protein retention but at low flow rates. Study of the effect of operating parameters during microfiltration of coagulum led to determination of optimal operating conditions leading to satisfactory performance and adequate retention rate. The results are explained using a model of the formation and development of internal and external fouling of a mineral membrane. Observations using scanning electron microscopy related to the pH of milk were used to verify the model by showing that internal fouling occurred only when the pH was higher than 5·50. This internal fouling was closely linked with the physicochemical state of milk proteins. Indeed, the fouling particles visualized at the alumina grains of the membrane support changed progressively from individual micelles (pH 6·62) to a chain or clustered structure (pH 5·60). Electrophoretic study confirmed this observation and showed that casein was present in milk permeates (pH 6·62) but not in coagulum permeates (pH 4·40).

Experimental determination of optimum operating conditions of a superconducting interferometer

A superconducting interferometer (SQUID) behaves as a nonlinear impedance, the value of which changes periodically when an linearly increasing flux is applied to it. Conditions of utilization of this device, when stimulated by an rf flux to obtain maximum sensitivity, where studied and were found to satisfy the relation k2Q≃1 and 2πLsic/φ0≃1. Experimental results show that the signal response increases as √f and the sensitivity obtained at 245 MHz is 4 × 10−5 φ0 Hz−1/2.

Recovering Oil by Retorting a Nuclear Chimney in Oil Shale*

Abstract A method is proposed for recovering oil by retorting oil shale shattered by deep underground nuclear explosions. Because most of the oil will be obtained from chunks of oil shale with maximum dimensions exceeding 1 ft, retorting times of up to several weeks are needed for complete recovery. A study of the heat economy of the retorting process in an underground nuclear chimney suggests that the nuclear detonation itself and the subsequent controlled combustion of residual carbon in retorted oil shale will provide ample energy. The proposed method is shown to be thermally efficient. A 5-ft diameter, 12-ft high aboveground batch retort has been constructed for the experimental retorting of mixtures of oil shale particle sizes. Low rates of air and recycle gas, low-retorting temperatures and slow combustion front advance have characterized its operation. In spite of imperfect mist-separating equipment, recoveries of about 60 percent of Fischer assay have been obtained. The particle size distribution of 30 gal/ton oil shale has not been appreciably altered by the retorting. The operating conditions of a nuclear chimney retort will be defined by the recycle gas-to-air ratio and the overall rate of gas injection. Determination of optimum operating conditions will be complicated by the large number of factors involved. However, the proposed technique appears to be a promising one for recovering the oil from thick, deep, oil shale deposits. Introduction The possibility of using nuclear explosions to produce bulk permeability in large masses of oil shale removes a major technical obstacle to oil recovery by in-situ retorting. This article presupposes the feasibility of making a nuclear chimney in oil shale, and is directed at the techniques of retorting the shale in such a chimney. DEFINITIONS (Many petroleum engineers are unfamiliar with the subject of this article. Following are definitions of terms that may be new to the reader. For a more comprehensive discussion of underground nuclear explosion technology, see Refs. 1 through 5.)Retorting of oil shale - Conversion by heating of kerogen, the waxy organic matter contained in oil shale, to a liquid very similar to petroleum; vapors and gases are also produced in retorting. In-situ retorting of oil shale - Retorting of oil shale without first mining it; ordinarily this is impractical due to low heat conductivity and low bulk permeability of oil shale deposits. Oil shale grade - Volume of organic liquid produced by retorting oil shale, divided by the weight of the raw (unretorted) sample. The modified Fischer assay is the standard procedure for measuring grade, which is commonly expressed in gallons per ton. Bulk permeability or fracture permeability - Average permeability of a large mass of material including the effect of fractures (for example, as opposed to the permeability that would be measured on a core sample). Underground nuclear explosion - A nuclear explosion buried so deeply in the ground that there is no dynamic venting of gases created by the detonation. Nuclear breaking - Fracturing and fragmenting of large volumes of rock by the explosive force of underground nuclear detonations, and the concomitant increase in bulk permeability of this rock. Introduction of such permeability into oil shale deposits may make in-situ retorting practical. Nuclear chimney - The roughly cylindrical region produced by an underground nuclear explosion that is filled with rock fragments. A fractured (but not fragmented) region surrounds the chimney (Fig. 1). Chimney collapse - The process by which a nuclear chimney is formed. Energy yield - A measure of energy released in a nuclear explosion (usually expressed in kilotons, equivalent to thousands of tons of TNT). One kiloton is more precisely defined as 10(12) calories. JPT P. 727ˆ

Determination of Optimum Operating Conditions in Atomic Absorption Spectroscopy

A statistical technique for the simultaneous study of response to several variables has been used in the estimation of “optimum„ operating conditions for the element Calcium in atomic absorption spectroscopy. The method is based on “response surface„ exploration, originally due to G.E.P. Box. This technique has several advantages over the traditional method of varying “one factor at a time.„ Direct estimates of the magnitude of the effects of changes in each instrumental variable are obtained, together with estimates of the interactions between two or more variables. The method leads to the efficient estimation of “optimum„ operating conditions, i.e., those levels of the instrumental variables at which percent transmission is a minimum and also the estimation of alternative levels of the several variables at which transmission can be maintained at a minimum. The results showed that, for the estimation of Ca, the four variables air pressure, air flow, gas flow, and “height above the blue cone„ are compensating in the sense that departure from minimum transmission due to change in one variable can be compensated by a suitable change in the other variables. In the absence of a theoretical solution to the problem of estimating “optimum„ operating conditions, it would seem that this method is the best available at the present time.