Mathematical Modelling of Coal Char Reactivity in a Pressurised Entrained Flow Gasifier PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Mathematical Modelling of Coal Char Reactivity in a Pressurised Entrained Flow Gasifier PDF full book. Access full book title Mathematical Modelling of Coal Char Reactivity in a Pressurised Entrained Flow Gasifier by Gui-Su Liu. Download full books in PDF and EPUB format.
Author: Gui-Su Liu
Publisher:
ISBN:
Category : Coal
Languages : en
Pages : 474
Get Book Here
Book Description
Author: Gui-Su Liu
Publisher:
ISBN:
Category : Coal
Languages : en
Pages : 474
Get Book Here
Book Description
Author: Sung Z. Jiang
Publisher: Nova Publishers
ISBN: 9781594548239
Category : Science
Languages : en
Pages : 388
Get Book Here
Book Description
Combustion or burning is an exothermic reaction between a substance and a gas to release heat. Combustion normally occurs in oxygen (often in the form of gaseous O2 ) to form oxides, However, combustion can also take place in other gases like chlorine. The products of such reactions usually include water (H2 O) as well as carbon monoxide (CO) or carbon dioxide (CO2 ), or both. Other by-products, such as partially reacted fuel and elemental carbon (C), may generate visible smoke and soot. This book presents leading research from around the world in this frontal field.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 95
Get Book Here
Book Description
The overall objective of the current project was to investigate the high pressure gasification characteristics of a feed containing both coal and biomass. The two feed types differ in their ash contents and ash composition, particularly the alkali content. Gasification of a combined feed of coal and biomass has the potential for considerable synergies that might lead to a dramatic improvement in process economics and flexibility. The proposed study aimed to develop a detailed understanding of the chemistry, kinetics, and transport effects during high pressure gasification of coal-biomass blend feed. Specifically, we studied to develop: (a) an understanding of the catalytic effect of alkali and other inorganic species present in the biomass and coal, (b) an understanding of processing conditions under which synergistic effects of the blending of coal and biomass might be observed. This included the role of particle size, residence time, and proximity of the two feed types, (c) kinetics of high pressure gasification of individual feeds as well as the blends, and (d) development of mathematical models that incorporate kinetics and transport models to enable prediction of gasification rate at a given set of operating conditions, and (e) protocols to extend the results to other feed resources. The goal was to provide a fundamental understanding of the gasification process and guide in optimizing the configurations and design of the next generation of gasifiers. The approach undertaken was centered on two basic premises: (1) the gasification for small particles without internal mass transfer limitations can be treated as the sum of two processes in series (pyrolysis and char gasification), and (2) the reactivity of the char generated during pyrolysis not only depends on the pressure and temperature but is also affected by the heating rates. Thus low heating rates (10-50 °C/min) typical of PTGA fail to produce char that would typically be formed at high heating rates (~104 °C/sec), encountered in entrained flow gasifiers. The char morphology, also a function of the heating rate, would influence the transport rates during the char gasification phase. Thus, heating rate plays a critical role through which both, pyrolysis and char gasification, are interconnected. We utilized two complementary gasification experiments: PEFR (pressurized entrained flow gasifier) and PTGA (pressurized thermo-gravimetric analyzer). The PEFR allowed us to study gasification at pressures, temperatures, and heating rates relevant for coal-biomass gasifiers. The PTGA work was useful in understanding the basic chemistry of the evolution of various gaseous species during pyrolysis. These results helped improved our understanding of the chemistry and chemical changes during pyrolysis. The role alkali metals and other inorganics in char gasification using steam and/or CO2 was investigated. Finally, the mathematical models for char gasification without the transport effects were developed at commercial operating conditions.
Author: Chin-Yung Wen
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 132
Get Book Here
Book Description
Author: United States. Department of Energy. Division of Fossil Fuel Utilization
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 164
Get Book Here
Book Description
Author: Brigham Young University. Chemical Engineering Department
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 32
Get Book Here
Book Description
Author: Brigham Young University. Chemical Engineering Department
Publisher:
ISBN:
Category : Coal gasification
Languages : en
Pages : 32
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
A research project was undertaken that had the overall objective of developing the models needed to accurately predict conversion rates of coal/biomass mixtures to synthesis gas under conditions relevant to a commercially-available coal gasification system configured to co- produce electric power as well as chemicals and liquid fuels. In our efforts to accomplish this goal, experiments were performed in an entrained flow reactor in order to produce coal and biomass chars at high heating rates and temperatures, typical of the heating rates and temperatures fuel particles experience in real systems. Mixed chars derived from coal/biomass mixtures containing up to 50% biomass and the chars of the pure coal and biomass components were subjected to a matrix of reactivity tests in a pressurized thermogravimetric analyzer (TGA) in order to obtain data on mass loss rates as functions of gas temperature, pressure and composition as well as to obtain information on the variations in mass specific surface area during char conversion under kinetically-limited conditions. The experimental data were used as targets when determining the unknown parameters in the chemical reactivity and specific surface area models developed. These parameters included rate coefficients for the reactions in the reaction mechanism, enthalpies of formation and absolute entropies of adsorbed species formed on the carbonaceous surfaces, and pore structure coefficients in the model used to describe how the mass specific surface area of the char varies with conversion. So that the reactivity models can be used at high temperatures when mass transport processes impact char conversion rates, Thiele modulus - effectiveness factor relations were also derived for the reaction mechanisms developed. In addition, the reactivity model and a mode of conversion model were combined in a char-particle gasification model that includes the effects of chemical reaction and diffusion of reactive gases through particle pores and energy exchange between the particle and its environment. This char-particle gasification model is capable of predicting the average mass loss rates, sizes, apparent densities, specific surface areas, and temperatures of the char particles produced when co-firing coal and biomass to the type environments established in entrained flow gasifiers operating at high temperatures and elevated pressures. A key result of this work is the finding that the reactivities of the mixed chars were not always in between the reactivities of the pure component chars at comparable gasification conditions. Mixed char reactivity to CO2 was lower than the reactivities of both the pure Wyodak coal and pure corn stover chars to CO2. In contrast, mixed char reactivity to H2O was higher than the reactivities of both the pure Wyodak coal and pure corn stover chars to H2O. This was found to be in part, a consequence of the reduced mass specific surface areas of the coal char particles formed during devolatilization when the coal and biomass particles are co-fired. The biomass particles devolatilize prior to the coal particles, impacting the temperature and the composition of the environment in which the coal particles devolatilize. This situation results in coal char particles within the mixed char that differ in specific surface area and reactivity from the coal char particles produced in the absence of the devolatilizing biomass particles. Due to presence of this "affected" coal char, it was not possible to develop a mixed char reactivity model that uses linear mixing rules to determine the reactivity of a mixed char from only the reactivities of the pure mixture components. However, it was possible to predict both mixed char specific surface area and reactivity for a wide range of fuel mixture rat os provided the specific surface area and reactivity of the affected coal char particles are known. Using the kinetic parameters determined for the Wyodak coal and corn stover chars, the ...
Author: L.Douglas Smoot
Publisher: Springer Science & Business Media
ISBN: 1475797214
Category : Science
Languages : en
Pages : 450
Get Book Here
Book Description
The use of coal is required to help satisfy the world's energy needs. Yet coal is a difficult fossil fuel to consume efficiently and cleanly. We believe that its clean and efficient use can be increased through improved technology based on a thorough understanding of fundamental physical and chemical processes that occur during consumption. The principal objective of this book is to provide a current summary of this technology. The past technology for describing and analyzing coal furnaces and combus tors has relied largely on empirical inputs for the complex flow and chemical reactions that occur while more formally treating the heat-transfer effects. GrOWing concern over control of combustion-generated air pollutants revealed a lack of understanding of the relevant fundamental physical and chemical mechanisms. Recent technical advances in computer speed and storage capacity, and in numerical prediction of recirculating turbulent flows, two-phase flows, and flows with chemical reaction have opened new opportunities for describing and modeling such complex combustion systems in greater detail. We believe that most of the requisite component models to permit a more fundamental description of coal combustion processes are available. At the same time there is worldwide interest in the use of coal, and progress in modeling of coal reaction processes has been steady.
Author: R.A. Durie
Publisher: Butterworth-Heinemann
ISBN: 1483162230
Category : Nature
Languages : en
Pages : 767
Get Book Here
Book Description
The Science of Victorian Brown Coal provides extensive information on Victorian brown coal, which is a major fossil fuel resource by any standard and constitutes about 97% of Victoria's recoverable energy reserves. Energy from brown coal has been the mainstay of the Victorian economy, providing low-cost electricity to the state grid, briquettes as a fuel for industry and town gas prior to the discovery of natural gas. Because of the unique properties of the coal, it has been necessary to develop an in-depth scientific knowledge of the coal and its behavior, as well as innovative technologies for its effective utilization. The economic benefit brown coal has provided to Victoria is demonstrated throughout the chapters. This book aims to provide the springboard for further research and lead to a new era in the development of value-added products and the more efficient utilization of this major resource. This text is a useful reference for students or individuals conducting research on fossil fuel energy, specifically on brown coals.
