Research

14 pages, 3906 KiB

Open AccessArticle

Determination of the Kinetic Parameters of Thermal Degradation and Hydrodemetallization of a Mixture of the Heavy Fraction of Low-Temperature Coal Tar and Coal Shale

by Murzabek Baikenov, Dariya Izbastenova, Akmaral Sarsenbekova, Nazerke Balpanova, Almas Tusipkhan, Zukhra Khalikova, Nazym Rakhimzhanova, Elena Kochegina, Balzhan Tulebaeva and Gulzhan Taurbaeva

Energies 2024, 17(7), 1766; https://0-doi-org.brum.beds.ac.uk/10.3390/en17071766 - 08 Apr 2024

Viewed by 273

Abstract

The laws of thermal degradation of the mixture of the heavy fraction of low-temperature coal tar and coal shale were investigated using dynamic thermogravimetry. The kinetic characteristics of the process were determined using various methods, including the Ozawa–Flynn-Wall, Friedman, non-parametric kinetics and Šesták–Berggren [...] Read more.

The laws of thermal degradation of the mixture of the heavy fraction of low-temperature coal tar and coal shale were investigated using dynamic thermogravimetry. The kinetic characteristics of the process were determined using various methods, including the Ozawa–Flynn-Wall, Friedman, non-parametric kinetics and Šesták–Berggren methods. It is shown that coal shale initiated changes in the kinetic parameters and decomposition rate of the heavy fraction of coal tar. It was found that a 13% content of coal shale in the mixture led to the maximum rate of weight loss of the heavy fraction of coal tar. A hydrodemetallization kinetic model of the mixture of the heavy fraction of low-temperature coal tar and coal shale is proposed. The kinetic parameters of the hydrodemetallization process were determined; in addition, the rate constants at various temperatures were estimated. The study shows that the distribution of trace elements in the hydrogenate from the initial mixture and in the hydrogenate from the solid residue was characterized by relatively low values of reaction rate constants. The maximum microelement distribution rate was achieved in the hydrogenate solid residue. Energy indicators of activation processes indicated that hydrodemetallization at low temperatures is advantageous from an energy point of view. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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14 pages, 2623 KiB

Open AccessArticle

Optimization of Coal Production Based on the Modeling of the Jig Operation

by Agnieszka Surowiak, Tomasz Niedoba, Mustapha Wahman and Ahmad Hassanzadeh

Energies 2023, 16(4), 1939; https://0-doi-org.brum.beds.ac.uk/10.3390/en16041939 - 15 Feb 2023

Cited by 1 | Viewed by 1049

Abstract

This paper presents the jig operating properties of the selected final parameters of the hard coal concentrate. The quality parameters of the product, such as the yield and ash content, were evaluated in terms of the technical and hydrodynamic parameters of the jig’s [...] Read more.

This paper presents the jig operating properties of the selected final parameters of the hard coal concentrate. The quality parameters of the product, such as the yield and ash content, were evaluated in terms of the technical and hydrodynamic parameters of the jig’s operation. The research program included a series of experiments in which the efficiency and the amount of hutch water were changed. The variables selected and analyzed were divided into two categories, i.e., one related to the characteristics of the concentrate produced, and the other to the characteristics of the jig operation. Models were built for narrowed particle size fractions based on concentrate yield and ash content in the concentrate. In addition, a multidimensional analysis was performed, considering variables such as machine throughput, which was determined by the flow rate of the material, the amount of hutch water, the quality of the concentrate, and the amount of concentrate, as well as the accuracy of the jig operation expressed by the imperfection. Two main parameters were taken into account for modeling the operation to examine their significance of influence on the final responses in terms of the possibility of adjusting the value of independent settings of the jig operation. The presented approach to modeling the operation of the jig can be extended by considering the impact of other parameters, taking into account the variability of the final effect, as long as it is allowed under the industrial conditions of machine operation and the assumed production requirements. The approach presented in this paper is a new technique, which was not found in the literature. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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17 pages, 1635 KiB

Open AccessArticle

Evaluation of the Effects of Coal Jigging by Means of Kruskal–Wallis and Friedman Tests

by Tomasz Niedoba, Agnieszka Surowiak, Ahmad Hassanzadeh and Hamid Khoshdast

Energies 2023, 16(4), 1600; https://0-doi-org.brum.beds.ac.uk/10.3390/en16041600 - 05 Feb 2023

Cited by 3 | Viewed by 1349

Abstract

Coal beneficiation processes are often based on gravitational enrichment techniques. Therefore, various types of jigs are often used in this area. A number of factors determine the quality of the final product. Therefore, proper and systematic monitoring of such a process is necessary. [...] Read more.

Coal beneficiation processes are often based on gravitational enrichment techniques. Therefore, various types of jigs are often used in this area. A number of factors determine the quality of the final product. Therefore, proper and systematic monitoring of such a process is necessary. The present work examined the effect of the hutch water amount and the amount of processed coal (system capacity) on the yield and ash grade in individual density–size fractions. A statistical method in the form of the Kruskal–Wallis test and the Friedman test was used to evaluate the process. These tests were proposed as universal and reliable alternatives to classical analysis of variance (ANOVA) analysis. The performed analysis allowed for the determination of what process conditions should be selected in order to obtain certain effects. Therefore, it allowed us to apply certain combinations of hutch water amount, system capacity and particle characteristics to maximize the expected effects. The application of statistical analysis methods in the form of Kruskal–Wallis and Friedman tests to evaluate process efficiency creates new possibilities to monitor and optimize the jigging process in both context of amount and quality of final product and is very important not only for mining enterprise but also from an environmental point of view. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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15 pages, 3356 KiB

Open AccessArticle

Stamp-Charged Coke-Making Technology—An Empirical Model for Prediction of Coal Charge Density for Stamp Charging Coke Oven Batteries

by Michał Rejdak, Grzegorz Gałko, Marcin Sajdak and Aleksandra Wieczorek

Energies 2022, 15(24), 9440; https://0-doi-org.brum.beds.ac.uk/10.3390/en15249440 - 13 Dec 2022

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Abstract

Coke-making technology utilises two systems for charging the coke oven chambers with coal—a stamp-charged system (stamp-charging) and a gravity charged system (top charging). The presented study examines the impact of selected coal properties on the effectivity of the stamping operation by measuring the [...] Read more.

Coke-making technology utilises two systems for charging the coke oven chambers with coal—a stamp-charged system (stamp-charging) and a gravity charged system (top charging). The presented study examines the impact of selected coal properties on the effectivity of the stamping operation by measuring the bulk density of the obtained stamped coal cake. An empirical mathematical model was developed that allows the forecasting of the coal cake density based on the most frequently assessed coal parameters, such as volatile matter, ash, moisture and particle size parameters, as well as the stamping operation parameter—cumulative stamping energy. The obtained results showed that the density of the stamped coal cake increases with the increase in the stamping energy (53.3 kg/m³ increase, for increase in natural logarithm value of 1), RRSB specific coal particle diameter d′ (6.4 kg/m³ increase, for each 0.1 mm increase in d′), ash content (8.9 kg/m³ increase, for 1% point increase) and moisture content (4 kg/m³ increase, for 1% point increase), and decreases with the increase in volatile matter content (3.82 kg/m³ decrease, for 1% point increase). Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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11 pages, 2660 KiB

Open AccessArticle

Transport Efficiency of a Homogeneous Gaseous Substance in the Presence of Positive and Negative Gaseous Sources of Mass and Momentum

by Bogusław Ptaszyński, Zbigniew Kuczera, Piotr Życzkowski and Rafał Łuczak

Energies 2022, 15(17), 6376; https://0-doi-org.brum.beds.ac.uk/10.3390/en15176376 - 01 Sep 2022

Cited by 1 | Viewed by 704

Abstract

In this article, a theoretical mathematical model of gas flow through a duct in the case of local mass and momentum sources and sinks is presented. The continuity equation and motion equation with one-dimensional, density-stable gas flows were used to create this model. [...] Read more.

In this article, a theoretical mathematical model of gas flow through a duct in the case of local mass and momentum sources and sinks is presented. The continuity equation and motion equation with one-dimensional, density-stable gas flows were used to create this model. The size of sources and sinks and their locations have an effect on the size of gas stream flows in the duct, gas energy losses, and the parameters of the mechanical source energy that is causing the flow. In the traditional approach to describing the gas flow in the duct, the concept of resistivity and the equivalent resistance of the conduit is used. In the case of flow in the duct with local mass and momentum sources and sinks, the transport resistance depends on a bigger number of parameters than the concept of specific resistance usage. The location and size of the source flux or mass and momentum sinks and the fan work (suction, blowing) were taken into account in the presented model. The model gives the opportunity to determine the mechanical energy losses and efficiency of gas transport in the duct. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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20 pages, 6912 KiB

Open AccessArticle

Coal Modeling Investigations in International Collaboration in the Light of Bibliometric Analysis of the Problem

by Agnieszka Saramak and Daniel Saramak

Energies 2022, 15(16), 6040; https://0-doi-org.brum.beds.ac.uk/10.3390/en15166040 - 20 Aug 2022

Cited by 2 | Viewed by 911

Abstract

The article concerns an analysis of records registered in Web of Science (WoS) database related to the problem of coal modeling. All publications registered in the WoS from the time period 1951–2021 were analyzed, mostly in terms of international collaboration, merit content and [...] Read more.

The article concerns an analysis of records registered in Web of Science (WoS) database related to the problem of coal modeling. All publications registered in the WoS from the time period 1951–2021 were analyzed, mostly in terms of international collaboration, merit content and research areas. It appeared that international scientific cooperation on this topic is differently considered, depending on the country. The leader in terms of the number of documents remains China, while the highest citation counts were gained by research teams, with the USA as the leader. Several sub-categories within research areas could be also divided on the basis of key words, while the most popular topic is connected with energetical aspects of coal utilization. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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14 pages, 2073 KiB

Open AccessArticle

Influence of Local Gas Sources with Variable Density and Momentum on the Flow of the Medium in the Conduit

by Bogusław Ptaszyński, Rafał Łuczak, Zbigniew Kuczera and Piotr Życzkowski

Energies 2022, 15(16), 5834; https://0-doi-org.brum.beds.ac.uk/10.3390/en15165834 - 11 Aug 2022

Viewed by 772

Abstract

In this article, the analysis of mechanical energy changes in a gas medium flow with stable and variable density was presented. To determine the energy losses, the various sources of momentum and mass were used, which had an influence on air flow through [...] Read more.

In this article, the analysis of mechanical energy changes in a gas medium flow with stable and variable density was presented. To determine the energy losses, the various sources of momentum and mass were used, which had an influence on air flow through the conduit in the system without heat exchange with the environment. The occurrence of varying density gas flow in the conduit (caused by local inflow of mass and momentum) in inclined pipes generates a natural depression–internal mechanical energy. The local momentum sources can facilitate or hinder the gas flow through the conduit. This phenomenon often appears in the network of underground mine workings and in ventilation and air conditioning installations. The characteristic for gas flow through a pipe or mining excavation is the equivalent aerodynamic resistance, the value of which is influenced by the mass and momentum of local sources. This value determines the facilitation or difficulty in gas transport through a section of conduit in relation to the mass stream of the medium. In this article, the dependency of mass flow and gas momentum with different densities on the value of the gas medium flow resistance in the conduit was analyzed. On the basis of the obtained results, the loss of mechanical energy and energy efficiency of flows were determined. In this work, two cases of fan work in suction and blowing modes were analyzed. For these examples, a gas inflow with three different mass streams, a density higher than the main stream density, and with a zero momentum value for this stream was modeled. Ten cases of mass inflow sources were considered. The results of the gas mass flow calculation through the fan

{\dot{m}}_{w}

and gas

{\dot{m}}_{0}

and the coefficient of transport efficiency are graphically presented in the paper. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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18 pages, 2722 KiB

Open AccessArticle

Application of the ARMA Model to Describe and Forecast the Flotation Feed Solids Flow Rate

by Jarosław Joostberens, Aurelia Rybak, Joachim Pielot and Artur Dylong

Energies 2021, 14(24), 8587; https://0-doi-org.brum.beds.ac.uk/10.3390/en14248587 - 20 Dec 2021

Cited by 2 | Viewed by 1560

Abstract

The flow rate of solids is subject to random disturbances of the changing feed and can significantly affect the quantitative and qualitative parameters of the coal flotation products. This quantity can be described as a stochastic process. The paper presents the results of [...] Read more.

The flow rate of solids is subject to random disturbances of the changing feed and can significantly affect the quantitative and qualitative parameters of the coal flotation products. This quantity can be described as a stochastic process. The paper presents the results of the solids flow rate model for coal flotation identification calculations, treated as a disturbance to the process. This is an innovative approach to modelling those quantitative parameters of the flotation feed that are measurably available and whose random changes have a significant impact on the enhancement process under industrial conditions. These include the volumetric flow rate of the feed and, in particular, concentration of solids in the feed. Therefore, it is suggested that random changes of these two parameters of the feed should be mapped using a model of one quantity—the flow rate of solids. This solution is advantageous because this quantity, as a quantitative parameter of the feed, has a significant impact on the course of the coal flotation process. The model is necessary in the process of designing an automatic control system through simulation tests. It allows us to generate a data string simulating random changes to this quantitative parameter of the feed. On this basis, in the simulation model, the correct functioning of the automatic control system is tested, the task of which is to compensate the influence of this disturbance. To determine the empirical model of the feed solids flow rate, measurement data obtained during the registration of the solids concentration and volumetric flow rate of the feed were used in four consecutive periods of operation of an industrial facility of one of the Polish coal processing plants. The time courses of the solids flow rate in the feed were described by ARMA (autoregressive–moving-average model) means, and the two-stage least squares method was used to estimate the model parameters. The results of the identification and verification of the designated model showed the correctness of adopting the third-order ARMA model, with parameters a₁ = −1.0682, a₂ = −0.2931, a₃ = 0.3807, c₁ = −0.1588, c₂ = −0.2301, c₃ = 0.1037, and variance σ²_ε = 0.0891, white noise sequence ε_t, determined on the basis of a series of residuals described by the fifth-order model. It has been shown that the identified model of the flow rate of solids of the feed to flotation as disturbances can be used to develop a predictive model that allows forecasting the modelled quantity with a prediction horizon equal to the sampling period. One-step forecasting based on the determined predictor equation was found to give results consistent with the recorded values of the solid part flow rate of the feed and the extreme values of the prediction error are within the range from −1.08 to 2.90 kg/s. Full article

(This article belongs to the Special Issue Factor Analysis and Mathematical Modeling of Coals)

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