Wyniki wyszukiwania - BazTech

1

Ścieki jako źródło ciepła odpadowego – studium przypadku

Żogała A., Darul H., Głodniok M., Zawartka P.

Inżynieria Ekologiczna

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2016

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Nr 49

208--212

PL

W artykule opisano możliwość wykorzystania ścieków oczyszczonych z miejskiej oczyszczalni ścieków jako dolnego źródła ciepła odpadowego. Przedstawiono i obliczono teoretyczne możliwości odbioru ciepła z uwzględnieniem metody pośredniej oraz bezpośredniej. Analizę przypadku w ujęciu wariantowym przeprowadzono na przykładzie miejskiej mechaniczno-biologicznej oczyszczalni ścieków Ruptawa należącej do Jastrzębskiego Przedsiębiorstwa Wodociągów i Kanalizacji (woj. Śląskie, miasto Jastrzębie).

EN

The paper describes the possibility of using treated wastewater from municipal waste water treatment plant as a waste heat source. Presented and calculated theoretical possibilities of receiving heat takes into account the indirect and direct method. A variant case study was carried out on the example of municipal mechanical and biological wastewater treatment plant Ruptawa belonging to Jastrzębskie Przedsiębiorstwo Wodociągów i Kanalizacji (voivodship Silesia, Jastrzębie City).

2

Problemy technologiczne i środowiskowe związane z termiczną konwersją osadów ściekowych

Żogała A.

Inżynieria Ekologiczna

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2016

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Nr 46

109--120

PL

Artykuł przestawia przegląd najczęściej spotykanych problemów technologicznych i środowiskowych związanych z termicznym przekształcaniem osadów ściekowych. W pracy omówiono takie zagadnienia jak m.in. wpływ zawartości wilgoci i substancji mineralnej na właściwości paliwowe osadów, problem emisji zamieszczeń i zagospodarowania stałej pozostałości po konwersji, ryzyko wystąpienia zjawiska korozji. Przedstawiono również zbiorczą charakterystykę najważniejszych metod termicznej konwersji osadów ściekowych, wraz z omówieniem wad i zalet każdej z nich.

EN

Overview of the most common technological and environmental problems connected with thermal conversion of sewage sludge was presented in the article. Such issues as the influence of content of moisture and mineral matter on fuel properties of sludge, problem of emission of pollutants, problem of management of solid residue, risk of corrosion, were described. Besides, consolidated characteristic of the most important methods of thermal conversion of sewage sludge, with their advantages and disadvantages, was presented in the paper.

3

CFD simulations of influence of steam in gasification agent on parameters of UCG process

Żogała A., Janoszek T.

Journal of Sustainable Mining

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2015

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Vol. 14, iss. 1

2--11

EN

Underground coal gasification (UCG) is considered to be a perspective and constantly developing technology. Nevertheless it is a very complex and technically difficult process, which results depend on many variables. Mathematical models enable detailed analysis of UCG process - for example - give possibility of prediction of syngas composition depending on applied gasification medium. In practice, mixtures of oxygen, air and steam are the most frequently used as converting agents. Steam is injected to the reactor in order to obtain combustible components. Nevertheless higher concentrations of steam create a problem of reduction of temperature in reactor. This issue of amount of steam in reacting system was analyzed in given paper. Computer simulations were used as test method applied in presented work. Calculations were carried by using Computational Fluid Dynamics (CDF) method and Ansys Fluent software. Changes in outlet concentrations of syngas components (CO, CO2, CH4, H2O, H2), in relation with time of process, were presented. Composition of product gas, its heating value and temperature of process were also examined (on outlet of rector) in function of content of steam in gasification agent (which was mixture of O2 and H2O). Obtained results indicated a possibility of conduct of stable gasification process (with predictable characteristic of gas). The simulation also demonstrated a possibility of deterioration of conditions in real reactors as a results of applying of too high amounts of steam.

4

Equilibrium simulations of coal gasification – factors affecting syngas composition

Żogała A.

Journal of Sustainable Mining

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2014

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Vol. 13, iss. 2

30--38

EN

Purpose: Coal gasification is complex technology, which results depend on many variables, connected among others with fuel, the converting agent and the process itself. The paper aims to analyze, by means of simulations, the influence of the following factors – temperature, pressure, characteristic parameters of coal and gasifying agent, on the composition and heating value of the obtained syngas. The other aim of this paper is the determination of gasification efficiency (based on the definition of cold gas efficiency) for various process conditions. Methods: Computer simulations were used as the research method for the work presented. An equilibrium model, based on the stoi-chiometric method with four independent reactions, was formulated and used in this paper. This model was implemented in Mathematica software. The influence of temperature (in a range from 500 to 1500°C), pressure (changed from atmospheric to 35 atm), three types of gasifying agent (mixtures of air, pure oxygen and steam) and the composition of four Polish coals (lignite and three hard-coals) on syngas parameters were analyzed in this paper. Results: Concentrations of CO2, CO, CH4, H2O, H2, N2 in the equilibrium syngas, for the chosen temperature, pressure and parame-ters of the fuel and converting agent were the results of the simulations carried out. Subsequently, the lower heating value and process efficiency for each syngas composition was calculated. Practical implications: The simulations indicated the thermodynamic limits of gasification and allowed for the formulation of the general principles ruling this process. Results presented in this paper may be useful in the preliminary optimization and analysis of coal gasification. They also can be a point of reference for more advanced simulations. Originality/ value: This paper presents own results obtained from equilibrium simulations of coal gasification. The author implemented a mathematical model, based on the method of Deringer and Traustel, presented earlier in literature, to carry out the calculations.

5

Critical analysis of underground coal gasification models. Part II: Kinetic and computational fluid dynamics models. Literary studies and comparison of models

Żogała A.

Journal of Sustainable Mining

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2014

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Vol. 13, iss. 1

29--37

EN

Purpose Underground coal gasification, as a complex and technically difficult process, in many aspects requires the support provided by computer simulations. There are a lot of mathematical models of UCG, some of them are concentrated with the forecast of syngas composition. The most important may be divided into three groups: equilibrium, kinetic and CFD models. The purpose of this work was the detailed critical analysis of more advanced approaches (than equilibrium considerations) applied in simulations of the coal conversion process – both kinetic and based on computational fluid dynamics. The other aim of this paper was the comparative analysis of the most important models of underground coal gasification. Methods Literary studies, concerned with the features and mathematical description of kinetic and CFD models of coal gasification, were used as the research method applied in the work presented. Compilation of the kinetic parameters of gasification reactions was an important part of this article. For that purpose the analysis of Polish and foreign papers, monographs and university handbooks was undertaken. Results Critical analysis of kinetic and CFD models of coal gasification (together with their mathematical formulation) was the result of considerations presented in this article. Kinetic equations were shown separately for pyrolysis, homogenous and heterogeneous reactions. In the case of CDF models, except for the presentation of the conservation equation, the most important methods of modeling turbulence are described (for the reason that this phenomenon may have significant inflence on the final results). Practical implications The work presented describes practical issues connected with kinetic and CFD models, focusing on their capabilities, drawbacks and possible application problems. Originality/ value This paper presents state of art in the field of coal gasification modeling using kinetic and computational fluid dynamics approach. The paper also presents own comparative analysis (concerned with mathematical formulation, input data and parameters, basic assumptions, obtained results etc.) of the most important models of underground coal gasification.

6

Critical analysis of underground coal gasification models. Part I: Equlibrium models – literary studies

Żogała A.

Journal of Sustainable Mining

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2014

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Vol. 13, iss. 1

22--28

EN

Purpose Underground coal gasification is a very difficult process due to changes in the parameters over time and within the space of the reactor and a variety of phenomena that occurs there. Consequently, it is necessary to create appropriate mathemati-cal models, which simplify the optimization and forecast of future results (especially final gas properties). The purpose of this work was the detailed critical analysis of the simplest coal gasification simulations methods, based on thermodynamic calculations of the process. These models, called equilibrium models, can be divided into two groups: stoichiometric and non-stoichiometric. The other aim of this paper was to characterize various engineering methods used in the calculation of equilibrium gasification processes. Methods Literary studies, concerned with general aspects of underground coal gasification modeling and the modeling of coal gasi-fication in the manner of equilibrium calculations, were used as a research method applied in presented work. Results The critical analysis of equilibrium models of coal gasification and the characterization (including mathematical formulation of process, range of required parameters, rate of convergence of calculations and methodology of searching solutions) of stoichiometric and non-stoichiometric methods were results of numerous considerations presented in this article. Practical implications The work presented describes practical issues connected with equilibrium models – their advantages, limitations and possible problems (for example with the determination of required constants) and potential applications (preliminary analysis, point of reference to more complex simulations etc.). Originality/ value This paper presents state of the art in field of equilibrium coal gasification modeling. This article is also attempt to elaborate on the most important problems connected with thermodynamic models of coal gasification.

7

Czynniki wpływające na skład chemiczny i wartość opałową gazu uzyskiwanego w procesie podziemnego zgazowania węgla

Żogała A., Kabiesz J., Iwaszenko S.

Przegląd Górniczy

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2013

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T. 69, nr 6

89--95

PL

Gaz wytwarzany w procesie PZW może mieć wiele zastosowań pod warunkiem, że zostaną spełnione wymagania dotyczące jego parametrów – składu chemicznego i wartości opałowej. Proces powinien być prowadzony w taki sposób, by w efekcie końcowym uzyskać gaz o jak największej zawartości składników palnych – CO, H2 oraz CH4, przy jak najmniejszej zawartości tzw. balastu. Ostateczny skład gazu syntezowego jest wypadkową wielu różnych parametrów złoża, paliwa a przede wszystkim samego procesu. W artykule scharakteryzowano efekt oddziaływań różnych czynników zgazowujących, temperatury i ciśnienia na końcowy rezultat procesu zgazowania. Omówiono wpływ składu chemicznego paliwa na możliwość wytworzenia dodatkowych komponentów gazu (jak związki S i N). Pokazano ponadto, jak na wartość opałową wytwarzanego gazu wpływają parametry złoża, które należy brać pod uwagę podczas projektowania georeaktora. Zaakcentowano także sensowność prowadzenia obliczeń modelowych w celu ułatwienia optymalizacji procesu.

EN

Syngas from underground coal gasification can have many applications in the future providing that the requirements of its parameters – chemical composition and heat value are met. The process should be performed in a way which allows to obtain the highest amount of combustible compounds – CO, H2, CH4 and the lowest amount of non-combustible components in the resulting gas. The final composition of syngas depends on many parameters of coal bed, fuel and, above all, the process itself. This paper presents the influence of different gasifying agents, temperature and pressure on the final result of gasification process. The impact of fuel chemical composition on the possibility of generation additional substances (like nitrogen and sulphur components) was described as well. The influence of coal bed parameters (which should also be taken into account during the development of underground gasification coal reactor) on heat value was described. It was shown that modelling calculations are crucial to simplify the optimization of the process.