When mineral processing separation results, for either constant or varying quality of the feed, can be approximated on the so-called Fuerstenau upgrading plots with the same one-fitting parameter a, then this parameter can be used as a selectivity indicator. If the equation has a form [...], where [...] stands for recovery of non-useful component in tailing while\ksi is the recovery of useful component in the concentrate, then at the same selectivity of upgrading (constant a) the increase of the useful component in the feed \alfa results in an increased amount of this component in both concentrate \beta and tailing [...] while the ratio of [...] to \beta is linearly dependent on \alfa when \epsilon is constant. Thus, at a constant selectivity a and constant \epsilon an increase in \alfa leads to a greater increase of the considered component in the tailing \theta than in the concentrate \beta.
Integrated gasification combined cycle systems (IGCC) are becoming more popular because of the characteristics, by which they are characterized, including low pollutants emissions, relatively high efficiency of electricity production and the ability to integrate the installation of carbon capture and storage (CCS). Currently, the most frequently used CO2 capture technology in IGCC systems is based on the absorption process. This method causes a significant increase of the internal load and decreases the efficiency of the entire system. It is therefore necessary to look for new methods of carbon dioxide capture. The authors of the present paper propose the use of membrane separation. The paper reviews available membranes for use in IGCC systems, indicates, inter alia, possible places of their implementation in the system and the required operation parameters. Attention is drawn to the most important parameters of membranes (among other selectivity and permeability) influencing the cost and performance of the whole installation. Numerical model of a membrane was used, among others, to analyze the influence of the basic parameters of the selected membranes on the purity and recovery ratio of the obtained permeate, as well as to determine the energetic cost of the use of membranes for the CO2 separation in IGCC systems. The calculations were made within the environment of the commercial package Aspen Plus. For the calculations both, membranes selective for carbon dioxide and membranes selective for hydrogen were used. Properly selected pressure before and after membrane module allowed for minimization of energy input on CCS installation assuring high purity and recovery ratio of separated gas.
This paper presents results of numerical investigation on a controllable airfoil flow separation phenomena practically applied in Formula One racing by a device called the F-duct. Separation is forced by air jets from slots located at different positions on the profile of the dual element wing and is intended to reduce aerodynamic drag. Slot position and the air jet velocity are the main parameters controlling the flow separation. The flow structure, surface pressure distribution, and the generated downwards lift and drag forces were investigated in this study. Two different flow separation structures have been recognised. Typically, wing stall is correlated with an increase in aerodynamic drag force. However, in the case of the finite wing with low aspect ratio, the induced drag is dominant and is proportional to the downforce. Therefore, flow separation on the wing increases the profile drag while simultaneously reducing the induced drag, resulting in a decrease in the total aerodynamic drag.
A comparative analysis of filtration performance of tangential and axial
inlet reverse-flow cyclone separators and vortex tube separators is
presented. The study showed that vortex tube separators are
characterized by a quality factor q several time higher
than tangential inlet reverse-flow cyclone separators. The cyclone
separators yield low separation efficiency and low filtration
performance at low air flow rates at low air volumes aspired by the
engine at low speed. One of the well-known and not commonly used methods
to improve separation efficiency is to apply electric field. An original
design of a vortex tube separator with insulators generating electric
field in the area of aerosol flow is presented. High voltage was applied
to the cyclone separator housing and its swirl vane. A special method
and test conditions were developed for cyclone separators with electric
field. Separation efficiency, filtration performance and pressure drop
across the cyclone separator in two different variants were determined.
The tests were carried out at five inlet velocity of cyclones υ0
= 1.75; 3.5; 7.0; 10.5; 14 m/s at an extraction rate of m0
= 10%, and at an average dust concentration in the inlet air of
s
= 1 g/m3. Using the electric field in the area of
a swirling aerosol stream resulted in an increase (over 12% – φc
= 96.3%) in separation efficiency at inlet velocity of cyclone ranging
from 1.75 to 3.5 m/s. An increase in separation efficiency at other
inlet velocity of cyclone is minor and does not exceed 3‒4%.
In this paper a 600 MW oxy-type coal unit with a pulverized bed boiler and a membrane-cryogenic oxygen separator and carbon capture installation was analyzed. A membrane-cryogenic oxygen separation installation consists of a membrane module and two cryogenic distillation columns. In this system oxygen is produced with the purity equal to 95%. Installation of carbon capture was based on the physical separation method and allows to reduce the CO2emission by 90%. In this work the influence of the main parameter of the membrane process – the selectivity coefficient, on the efficiency of the coal unit was presented. The economic analysis with the use of the break-even point method was carried out. The economic calculations were realized in view of the break-even price of electricity depending on a coal unit availability.
Paper presents the results of numerical modelling of a rectangular tube filled with a mixture of air and CO2 by means of the induced standing wave. Assumed frequency inducing the acoustic waves corresponds to the frequency of the thermoacoustic engine. In order to reduce the computational time the engine has been replaced by the mechanical system consisting of a piston. This paper includes the results of model studies of an acoustic tube filled with a mixture of air and CO2 in which a standing wave was induced.
In this work we provide a method for approximating the separable numerical range of a matrix. We also recall the connection between restricted numerical range and entanglement of a quantum state. We show the possibility to establish state separability using computed restricted numerical range. In particular we present a method to obtain separability criteria for arbitrary system partition with use of the separable numerical range.
The process of enrichment in a jig has usually been described and analysed using particle density as a separation feature. However, a degree of particle loosening in the jig bed is affected by, inter alia, the terminal particle free settling velocity which in turn is affected by the size, density and shape of a particle. Therefore, the terminal particle settling velocity clearly characterises the feed transferred to a jig for the enrichment process. Taking the comprehensive particle geometric (particle size and shape) and physical properties (particle density) into account comes down to the calculation of the terminal particle settling velocity. The terminal particle settling velocity is therefore a complex separation feature which comprises three basic particle features (particle density, size and shape). This paper compares the effects of enrichment of coal fines in a jig, for two cases: when the commonly applied particle density is separation feature and for the particle settling velocity. Particle settling velocities were calculated in the selected three particle size fractions: –3.15+2.00, –10.00+8.00 and –20.00+16.00 mm based on the industrial testing of a jig for coal fines and detailed laboratory tests consisting in determining particle density, projective diameter and volume and dynamic particle shape coefficient. The calculated and drawn partition curves for two variants, i.e. when particle density and particle settling velocity were taken into account as the separation argument in selected particle size fractions, allowed to calculate and compare separation precision indicator. With the use of a statistical test, the assumption on the independence of random variables of the distribution of components included in the distribution of the particle settling velocity as a separation feature during enrichment in a jig was verified.
The paper presents the experimental study of a novel unsteady-statemembrane gas separation approach for recovery of a slow-permeant component in the membrane module with periodical retentate withdrawals. The case study consisted in the separation of binary test mixtures based on the fast-permeant main component (N2O, C2H2) and the slow-permeant impurity (1%vol. of N2) using a radial countercurrent membrane module. The novel semi-batch withdrawal technique was shown to intensify the separation process and provide up to 40% increase in separation efficiency compared to a steady-state operation of the same productivity.
This paper analyses the real behaviour of the fluid in the channels of a three-end membrane module. The commonly accepted mathematical model of membrane separation of gas mixtures in such modules assumes a plug flow of fluid through the feed channel and perfect mixing in the permeate channel. This article discusses the admissibility of accepting such an assumption regarding the fluid behaviour in the permeate channel. Throughout analysis of the values of the Péclet number criterion, it has been demonstrated that in the industrial processes of membrane gas separation, the necessary conditions for the perfect mixing in the permeate channel are not met. Then, CFD simulations were performed in order to establish the real fluid behaviour in this channel. It was proved that in the permeate channel the fluid movement corresponds to the plug flow, with the concentration differences at both ends of the module being insignificant. In view of the observations made, the admissibility of concentration stability assumptions in the mathematical models for the permeate channel was discussed.
The coal fed to gravity enrichment consists of coals coming from different deposits and exploitation fronts. These coals differ in quality parameters, especially the amount of gangue (stone) changing over time. This results in the instability of work, especially jiggers, which have a relatively low accuracy assessed by probable scattering or imperfection rates. This deteriorates the quality of the concentrate obtained, the quality parameters of which change over time. The improvement of jiggers work would be possible by averaging the feed. This process is practically impossible due to the failure to design such a node during plant construction, which are, in most cases, directly related to the shaft. In the article, the authors propose to solve the process of averaging the feed before directing it to the enrichment process in jiggers by introducing its deshaling in vibratory- air separators of the FGX type.
The paper presents a simulation analysis of four control systems of the raw coal feed to a jig: stabilization of the volumetric flow of the feed, stabilization of the feed tonnage, stabilization of the feed flow with the additional measurement of the feed bulk density or the additional measurement of ash content in the feed. Analysis has been performed for the first and second compartments of a jig. The aim of the feed control was to stabilize the mass of the bed in the zone where the material stratifies; the mass may change due to changes in the washability characteristics of the feed. Such control should result in stable conditions in which material loosens during subsequent media pulsation cycles; stabilizing conditions minimizes the dispersion of coal particles in the bed. The best results have been achieved for the system of feed control where the ash content was measured in the first compartment, and for feed tonnage control in the second compartment.
CO2 emission from combustion fossil fuels is considered as the primary factor in the global warming. Different methods for separation CO2 from combustion flue gases are extensively used across the world. The aim of this study is to analyze the most important technological solutions of CO2 separation. For this reason chemical absorption, physical absorption, adsorption approach, membrane filtration and cryogenic process were researched. Concluding, selection of the right method for carbon dioxide capture separation is a complex issue and a range of technological and economic factors should be taken into consideration prior to application on the industrial scale.