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Study of pyrolysis and gasification of biomass from the self-organization perspective
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
KTH Royal Institute of Technology, 2015. , s. vi, 82
Nyckelord [en]
pyrolisys, pellets, hydrogen, gasification
Nationell ämneskategori
Metallurgi och metalliska material Energiteknik Kemiska processer
Forskningsämne
Teknisk materialvetenskap; Kemiteknik
Identifikatorer
URN: urn:nbn:se:kth:diva-162109ISBN: 978-91-7595-478-3 (tryckt)OAI: oai:DiVA.org:kth-162109DiVA, id: diva2:796994
Disputation
2015-04-10, B1, Brinellvägen 23, KTH, Stockholm, 10:00 (Engelska)
Opponent
Handledare
Forskningsfinansiär
Vetenskapsrådet
Anmärkning

QC 20150324

Tillgänglig från: 2015-03-24 Skapad: 2015-03-20 Senast uppdaterad: 2015-03-31Bibliografiskt granskad
Delarbeten
1. Parameters of high temperature steam gasification of original and pulverised wood pellets
Öppna denna publikation i ny flik eller fönster >>Parameters of high temperature steam gasification of original and pulverised wood pellets
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2011 (Engelska)Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 92, nr 10, s. 2068-2074Artikel i tidskrift (Refereegranskat) 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.

Nyckelord
Wood pellets, Char gasification, Random pore model, Grain model, Volumetric model
Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-39004 (URN)10.1016/j.fuproc.2011.06.009 (DOI)000293932600036 ()2-s2.0-79960562564 (Scopus ID)
Forskningsfinansiär
Vetenskapsrådet
Anmärkning

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

Tillgänglig från: 2011-09-07 Skapad: 2011-09-06 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
2. Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles
Öppna denna publikation i ny flik eller fönster >>Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles
2012 (Engelska)Ingår i: ISRN Mechanical Engineering, ISSN 2090-5122, E-ISSN 2090-5130, artikel-id 207464Artikel i tidskrift (Refereegranskat) 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.

Ort, förlag, år, upplaga, sidor
Hindawi Publishing Corporation, 2012
Nyckelord
pyrolisys, straw pellets, steam gasification
Nationell ämneskategori
Energiteknik
Forskningsämne
Kemiteknik; Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-162107 (URN)10.5402/2012/207464 (DOI)
Anmärkning

QC 20150324

Tillgänglig från: 2015-03-20 Skapad: 2015-03-20 Senast uppdaterad: 2017-12-04Bibliografiskt granskad
3. Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis
Öppna denna publikation i ny flik eller fönster >>Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis
2013 (Engelska)Ingår i: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 106, s. 253-261Artikel i tidskrift (Refereegranskat) 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.

Nyckelord
Convective boundary layer, Joule-Thomson effect, Pyrolysis
Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-118315 (URN)10.1016/j.fuproc.2012.08.005 (DOI)000314191800032 ()2-s2.0-84870525224 (Scopus ID)
Forskningsfinansiär
Vetenskapsrådet
Anmärkning

QC 20130214

Tillgänglig från: 2013-02-14 Skapad: 2013-02-14 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
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
Öppna denna publikation i ny flik eller fönster >>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 (Engelska)Ingår i: Nonlinear Phenomena in Complex Systems, ISSN 1561-4085, E-ISSN 1817-2458, Vol. 16, nr 3, s. 287-301Artikel i tidskrift (Refereegranskat) 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.

Nyckelord
Char, Fractal structure, Micro-porosity, Pyrolysis, Scaling, Self-organization
Nationell ämneskategori
Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-139915 (URN)2-s2.0-84887599022 (Scopus ID)
Anmärkning

QC 20140116

Tillgänglig från: 2014-01-16 Skapad: 2014-01-15 Senast uppdaterad: 2017-12-06Bibliografiskt granskad
5. Mechanically assisted low temperature pyrolysis of hydrocarbons
Öppna denna publikation i ny flik eller fönster >>Mechanically assisted low temperature pyrolysis of hydrocarbons
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2014 (Engelska)Ingår i: Proceedings of the XVII International Conference Foundations & Advances in Nonlinear Science, September 29 - October 3, Minsk 2014, 2014Konferensbidrag, Publicerat paper (Refereegranskat)
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.

Nyckelord
hydrogen, Sn:Bi alloy, fractals, pyrolysis
Nationell ämneskategori
Energiteknik
Forskningsämne
Kemiteknik; Energiteknik
Identifikatorer
urn:nbn:se:kth:diva-162105 (URN)
Konferens
XVII International Conference Foundations & Advances in Nonlinear Science, September 29 - October 3, Minsk 2014
Anmärkning

QC 20150323

Tillgänglig från: 2015-03-20 Skapad: 2015-03-20 Senast uppdaterad: 2015-03-24Bibliografiskt granskad

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