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Study of pyrolysis and gasification of biomass from the self-organization perspective
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on the analysis of kinetics of i) low-temperature pyrolysis of gaseous hydrocarbons, ii) high-temperature steam gasification of char of wood pellets (>700oC), iii) high temperature pyrolysis of straw pellets in an atmosphere of argon and steam, and iv) high temperature pyrolysis of slices of transversally cut wooden sticks. The results of the kinetic measurements in the high-temperature cases are approximated using a least-square based optimization software, which was specially developed to analyse kinetics prone for deviation from the Arrhenius law.In the thesis a general analysis of the researched materials and kinetics of their pyrolysis and gasification is presented from the self-organization perspective. The energy transfer phenomena in both the pyrolysis and gasification processes of biomass are discussed with an emphasis on an analysis of basic phenomena involving the self-organized dynamics on fractal structures in the chosen biomass samples.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2015. , vi, 82 p.
Keyword [en]
pyrolisys, pellets, hydrogen, gasification
National Category
Metallurgy and Metallic Materials Energy Engineering Chemical Process Engineering
Research subject
Materials Science and Engineering; Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-162109ISBN: 978-91-7595-478-3 (print)OAI: oai:DiVA.org:kth-162109DiVA: diva2:796994
Public defence
2015-04-10, B1, Brinellvägen 23, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research Council
Note

QC 20150324

Available from: 2015-03-24 Created: 2015-03-20 Last updated: 2015-03-31Bibliographically approved
List of papers
1. Parameters of high temperature steam gasification of original and pulverised wood pellets
Open this publication in new window or tab >>Parameters of high temperature steam gasification of original and pulverised wood pellets
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2011 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, no 10, 2068-2074 p.Article in journal (Refereed) Published
Abstract [en]

Experiments on gasification of chars obtained from original and pulverised wood pellets were conducted in atmosphere of water steam and nitrogen under temperatures of 800, 900 and 950 degrees C. Molar flow rates of carbon containing product gases were measured and approximated using different models with respect to extents of carbon conversion in char of the pellets. Comparison of the random pore, grain and volumetric models revealed the best applicability for approximations of the random pore model. Apparent activation energies obtained as a result of application of the models to the data from experiments with char of original pellets were higher in comparison to those of pulverised pellets, except for a grain model. Approximations under 800 degrees C showed relatively big deviations from experimental data on the beginning of char gasification. This is attributed to catalytic effects from alkali metals in the pellets.

Keyword
Wood pellets, Char gasification, Random pore model, Grain model, Volumetric model
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-39004 (URN)10.1016/j.fuproc.2011.06.009 (DOI)000293932600036 ()2-s2.0-79960562564 (Scopus ID)
Funder
Swedish Research Council
Note

Updated from "Manuscript" to "Article". QC 20150320

Available from: 2011-09-07 Created: 2011-09-06 Last updated: 2017-12-08Bibliographically approved
2. Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles
Open this publication in new window or tab >>Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles
2012 (English)In: ISRN Mechanical Engineering, ISSN 2090-5122, E-ISSN 2090-5130, 207464Article in journal (Refereed) Published
Abstract [en]

Experimental research on the pyrolysis and gasification of randomly packed straw pellets was conducted with an emphasis on the reactive properties of the shrinking porous structure of the pellets. The apparent kinetics of such pyrolysis was approximated by the random pore, grain, and volumetric models. The best approximation results were obtained with the grain and random pore models. The self-organized oscillations of the pellet conversion rate during pyrolysis were observed. Two complementary explanations of the phenomenon are proposed.

Place, publisher, year, edition, pages
Hindawi Publishing Corporation, 2012
Keyword
pyrolisys, straw pellets, steam gasification
National Category
Energy Engineering
Research subject
Chemical Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-162107 (URN)10.5402/2012/207464 (DOI)
Note

QC 20150324

Available from: 2015-03-20 Created: 2015-03-20 Last updated: 2017-12-04Bibliographically approved
3. Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis
Open this publication in new window or tab >>Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis
2013 (English)In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 106, 253-261 p.Article in journal (Refereed) Published
Abstract [en]

Measurements of temperature in the proximity of wood pellets (8 mm diameter) and thin wooden stick slices (5 cm diameter and 5 mm thickness) were conducted to estimate the effects of mixing between the evolving volatiles and hot steam (T > 700°C) flowing around the particles. Measurements of mass loss of the slices were conducted to estimate the apparent kinetic parameters of their pyrolysis. A simple kinetic model of the process (type II by Pyle and Zaror (1984) [20]) was investigated. The experiments showed a plateau-like part in the graphs of temperature measured in the proximity to the samples. The existence of this plateau-like part agrees with the general data of calorimetric measurements of pyrolysis, which show extensive energy consumption in the beginning of an active production of volatiles. A hypothesis regarding feedback on the process due to the micro-expansion and mixing of volatiles in the convective boundary layer is discussed.

Keyword
Convective boundary layer, Joule-Thomson effect, Pyrolysis
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-118315 (URN)10.1016/j.fuproc.2012.08.005 (DOI)000314191800032 ()2-s2.0-84870525224 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20130214

Available from: 2013-02-14 Created: 2013-02-14 Last updated: 2017-12-06Bibliographically approved
4. Prospective side effects of the heat and mass transfers in micro-porous structure of char during intermediate and final stages of the high-temperature pyrolysis
Open this publication in new window or tab >>Prospective side effects of the heat and mass transfers in micro-porous structure of char during intermediate and final stages of the high-temperature pyrolysis
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2013 (English)In: Nonlinear Phenomena in Complex Systems, ISSN 1561-4085, E-ISSN 1817-2458, Vol. 16, no 3, 287-301 p.Article in journal (Refereed) Published
Abstract [en]

The general problem of a decrease of activation energy for reactions of thermal decomposition in ligno-cellulosic materials in the end of the high-temperature pyrolysis has been discussed. Experiments emphasizing the differences between the starting, intermediate and final stages of the process were conducted. A hypothesis to solve the problem from the point of view of a fundamental fractal theory was formulated. The conclusions of the discussions related to the hypothesis gave a description of new experiments to prove the fundamental theory on diffusion processes with naturally or artificially created conditions for self-organization.

Keyword
Char, Fractal structure, Micro-porosity, Pyrolysis, Scaling, Self-organization
National Category
Energy Engineering
Identifiers
urn:nbn:se:kth:diva-139915 (URN)2-s2.0-84887599022 (Scopus ID)
Note

QC 20140116

Available from: 2014-01-16 Created: 2014-01-15 Last updated: 2017-12-06Bibliographically approved
5. Mechanically assisted low temperature pyrolysis of hydrocarbons
Open this publication in new window or tab >>Mechanically assisted low temperature pyrolysis of hydrocarbons
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2014 (English)In: Proceedings of the XVII International Conference Foundations & Advances in Nonlinear Science, September 29 - October 3, Minsk 2014, 2014Conference paper, Published paper (Refereed)
Abstract [en]

We report experimental setups and conditions leading to pyrolysis (cracking) of such gaseous hydrocarbons as methane, mixed propane and butane, at the temper-atures of the heater below 200oC. The process was mechanically assisted by putting the substances being decomposed into a dynamic interaction with the tin and bismuth alloy. The alloy had periodically changing phase state thus creating fractal interfaces between its surface and the gases. Interaction of the gases with mechanically produced fractal surfaces of the alloy made possible gas decomposition even at lower temperatures of the heater (150oC). At this temperature the heater couldn't melt the alloy in the heated volume with the gas.

Keyword
hydrogen, Sn:Bi alloy, fractals, pyrolysis
National Category
Energy Engineering
Research subject
Chemical Engineering; Energy Technology
Identifiers
urn:nbn:se:kth:diva-162105 (URN)
Conference
XVII International Conference Foundations & Advances in Nonlinear Science, September 29 - October 3, Minsk 2014
Note

QC 20150323

Available from: 2015-03-20 Created: 2015-03-20 Last updated: 2015-03-24Bibliographically approved

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