Results 1 - 10 of 189
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[en] The paper analyses the influence of measuring errors of the operation parameters (flows, temperatures, pressures, and concentrations) in the experimental determination of the mass and heat transfer coefficients. Data obtained on experimental plants for hydrogen isotopes separation, by hydrogen distillation and water distillation, and calculus model for errors propagation are presented. The results are tabulated. The variation intervals of transfer coefficients are marked graphically. The study of the measuring errors is an intermediate stage, extremely important, in experimental determination of criterion relation coefficients, specific relations for B7 structured packing. (authors)
[en] The paper reports and analysis of the influence of errors in measuring the temperature and isotopic concentrations in experimental determination of mass and heat transfer coefficient. The calculation model for this coefficient is presented as well as the result obtained from an experimental installation of water distillation. The experimental distillation column of an 108 mm inner diameter was filled with an B ordered packing up to a 14 m height. In such a column temperature, vapor concentrations, pressures and reflux rates were measured in 12 points. A table with measured and calculated values is given. Large errors in this quantities made lead to either sub- or super evaluation of the packing performances. Under-evaluation may lead to investment cost increases while super-evaluation may lead to a production capacity decrease
[en] Due to the low pressure drop that it introduces, the structured packing is often used in the case of distillation under vacuum and of the mixture separation when the desired component is found in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of HTU calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data. (authors)
[en] Chromatography has been established as the method of choice for the separation and purification of optically pure drugs which has a market size of about 250 billion USD. Single column chromatography (SCC) is commonly used in the development and testing phase of drug development while multi-column Simulated Moving Bed (SMB) chromatography is more suitable for large scale production due to its continuous nature. In this study, optimal performance of SCC and SMB processes for the separation of optical isomers under linear and overloaded separation conditions has been investigated. The performance indicators, namely productivity and desorbent requirement have been compared under geometric similarity for the separation of a mixture of guaifenesin, and Tröger's base enantiomers. SCC process has been analyzed under equilibrium assumption i.e., assuming infinite column efficiency, and zero dispersion, and its optimal performance parameters are compared with the optimal prediction of an SMB process by triangle theory. Simulation results obtained using actual experimental data indicate that SCC may compete with SMB in terms of productivity depending on the molecules to be separated. Besides, insights into the process performances in terms of degree of freedom and relationship between the optimal operating point and solubility limit of the optical isomers have been ascertained. This investigation enables appropriate selection of single or multi-column chromatographic processes based on column packing properties and isotherm parameters.
[en] In this work, direct numerical simulation of incompressible gas flow through a complex geometrical structure of Raschig rings is performed. The bed structure is obtained in a separate simulation in which Raschig rings are added one by one and fall freely into a cylindrical container until mechanical equilibrium is reached. The gas is injected at the top of the container, flows through a packed layer of randomly oriented rings, then leaves the container at the bottom. The flow equations are solved with the use of classical second order solver and projection method for structured regular grid and the complexity of domain geometry is handled by a variant of immersed boundary technique. The model allows to study the characteristics of the flow within the bed, pressure distribution in particular, and can be applied to development and validation of simplified approaches. The simulations are performed for various grid resolutions and the results show good convergence to grid independent solution, especially for lower gas velocities. The obtained dependence of total pressure drop on the inlet velocity is in reasonable agreement with the literature data but the demand for grid resolution significantly increases with the gas velocity.
[en] The use of the ionizing radiation for application in plastic packaging, to improve some of properties and for radiation sterilization, has been gaining popularity in the packaging industry. As a consequence of the irradiation, plastic packaging materials can undergo some chemical and physical alterations in their basic function, mainly concerning the protection characteristics. Since changes in physical properties of irradiated packaging films reflect radiation-induced chemical changes in molecular structure, in this work, an investigation was performed by Ftir analysis of LDPE film before and after radiation. Film samples were irradiated with doses between 0 Gy and 100 kGy, at room temperature and in the presence of air. The results showed alterations in the molecular structure, according to the absorbed radiation dose. (author)
[en] Bubble column reactor belongs to the general class of multiphase reactors in which gas come in contact with liquid. This reactor purposely used to mix the two phases or substances where the gas is dispersed into the column from the bottom and rises within the liquid and escapses from the upper liquid surface. Throughout the design and development phase, the reactor design specifications were identified to meet the experimental requirements for hydrodynamics study in a bubble column using the high-speed camera, industrial radiotracer, and radioactive particle tracking techniques. This bubble column reactor design comes with six different type of sparger design for various mixing pattern optimization. The design methodology structured as design development process, conceptual design selection process, detailed design specifications, product fabrication, and final product testing. This versatile reactor is developed to overcome the problems faced in understanding hydrodynamics behavior of using different types of sparger design, leading to design optimization for better mixing and blending efficiency in multiphase flow investigations. This study has demonstrated that the newly quadrilateral bubble column reactor is ready to be used for the various types of laboratory assessment including industrial radioactive experiments. (author)
[en] The design of horizontal cylindrical vessels and their supports are often conducted using the standards and design codes exist, that in general the resulting cylindrical shells have a thickness determined by the maximum circumferential stress. As the maximum circumferential stress governs the design of these vessels, we can adopt it as a mathematical model of a horizontal beam on supports so that such simplification does not compromise the validity of the results. This work will discuss the behavior of vessels supported by saddles. Through the design of supports by saddles, get some possible configurations, such that we will opt to study the supports by saddles with reinforcement rings, where one of the constraints imposed by the standard and the design codes is that the contact angle between the vessel and the saddles have a minimum value determined. This analysis focuses on the behavior of the multiple saddles supports which are anchored to a rigid foundation. With the aim to study the seismic saddle supports, which are an essential part of the pressure vessel installed in horizontal, under seismic loading conditions (with one of the saddles is constrained in three directions and the other three saddles with restrictions in two directions and free only in axial direction of pressure vessel), will hold a study that addresses the issue through analytical calculations and numerical method such that it is possible to compare the results. (author)