Biomass Conversion and Biorefinery

, Volume 4, Issue 1, pp 1–14 | Cite as

Biomass heat pipe reformer—design and performance of an indirectly heated steam gasifier

  • Jürgen KarlEmail author
Original Article


Indirectly heated dual fluidized bed (DFB) gasifiers are a promising option for the production of syngas, in particular in the small- and medium-scale range. The application of so-called heat pipes solves the key challenge of indirectly heated gasifiers—the heat transfer into the gasifier's reformer part. Performance, technical challenges, and solutions for the so-called biomass heat pipe reformer are discussed, and the development of the last 10 years is summarized. An equation for the heat pipe reformer's cold gas efficiency is presented. The equation applies for any dual fluidized bed gasifier and indicates that the efficiency of the combustion process dominates the cold gas efficiency of any directly or indirectly heated allothermal steam gasification system.


Biomass Allothermal gasification Heat pipes 


a, amin

(Stoichiometric) air demand (kilogramsair/kilogramfuel)


Fuel-to-bed material ratio (kilogramsbed material/kilogramfuel)


Specific heat (kilojoules per kilogram per Kelvin)


Lower heating value (kilojoules per kilogram)


Molar enthalpy (kilojoules per kilomole)


Heat of reaction (kilojoules per kilomole)


Heat of evaporation (kilojoules per kilomole)

\( \overset{\cdot }{m} \)

Mass flow (kilograms per second)

\( \overset{\cdot }{n} \)

Molar flow (kilomoles per second)

\( {\tilde{M}}_{{}_i} \)

Molar mass (kilograms per kilomole)

m, n

Molar fraction of hydrogen and oxygen in the fuel (–)

\( \overset{\cdot }{Q} \)

Energy flow, heat demand, heat flux (kilowatts)

\( \overset{\cdot }{q} \)

Specific heat demand (–)

\( \varDelta {\overset{\cdot }{Q}}_{\varDelta \mathrm{h},\mathrm{r}} \)

Heat of reaction for the endothermal gasification reactions (kilowatts)

\( \varDelta {\overset{\cdot }{Q}}_{\varDelta \mathrm{h},\mathrm{v}} \)

Heat of evaporation for the evaporation of the fuel's moisture (kilowatts)

\( \varDelta {\overset{\cdot }{q}}_{\varDelta \mathrm{h},\mathrm{r}} \)

Specific heat of reaction for the endothermal gasification reactions (–)

\( \varDelta {\overset{\cdot }{q}}_{\varDelta \mathrm{h},\mathrm{v}} \)

Specific heat of evaporation for the evaporation of the fuel's moisture (–)

s, smin

(Stoichiometric) steam demand (kilogramssteam/kilogramfuel)


Temperature (Kelvin)


Moisture content of fuel (kilogramswater/kilogramfuel)


Char content (kilogramschar/kilogramfuel)

Greek letter


Cold gas efficiency (–)


Combustor efficiency (–)


Excess air ratio (–)


Excess steam ratio (–)


Stoichiometric coefficient (–)


Char conversion rate (–)





Bed material




Combustion chamber




Flue gas


Heat pipe






Sensible heat





Dual fluidized bed


Combined heat and power


Absorption enhanced reforming


Heat pipe reformer


Biomass heat pipe reformer


Moving bed gasification


Substitute natural gas


  1. 1.
    Hofbauer H, Rauch R, Bosch K, Koch R, Aichernig C (2003) Biomass CHP plant guessing—a success story. In: Bridgwater AV (ed) Pyrolysis and gasification of biomass and waste. CPL Press, Newbury, pp 371–383Google Scholar
  2. 2.
    Pfeifer C, Koppatz S, Hofbauer H (2011) Steam gasification of various feedstocks at a dual fluidised bed gasifier: impacts of operation conditions and bed materials. Biomass Conversion and Biorefinery 1(1):39–53CrossRefGoogle Scholar
  3. 3.
    Kern S, Pfeifer C, Hofbauer H (2012) Synergetic utilization of biomass and fossil fuels: influence of temperature in dual fluidized bed steam co-gasification of coal and wood. International Journal of Environmental Science and Development 3(3):294–299CrossRefGoogle Scholar
  4. 4.
    Paisley MA, Overend RP (2002) The SILVAGAS process from future energy resources—a commercialization success. In Biomass for energy, industry and climate protection, Proceedings of the 12th International Conference on Biomass, Amsterdam, The Netherlands, pp 975–978Google Scholar
  5. 5.
    van der Meijden CM, Veringa HJ, Rabou L (2010) The production of synthetic natural gas (SNG): a comparison of three wood gasification systems for energy balance and overall efficiency. Biomass Bioenergy 34(3):302–311CrossRefGoogle Scholar
  6. 6.
    Göransson K, Söderlind U, Zhang W (2009) Preliminary test on the allothermal gasifier at Mid Sweden University, 17th European Biomass Conference and Exhibition, Hamburg, GermanyGoogle Scholar
  7. 7.
    Poboß N, Swiecki K, Charitos A, Hawthorne C, Zieba M, Scheffknecht G (2012) Experimental Investigation of the absorption enhanced reforming of biomass in a 20 kWth dual fluidized bed system. Int J Thermodyn (IJoT) 1:53–59. doi: 10.5541/ijot.321 Google Scholar
  8. 8.
    Fang M, Wang Q, Yu C, Shi Z, Luo Z, Cen K (2005) Development of gas steam and power multi-generation system. In Proceedings of the 18th International Conference on Fluidized Bed Combustion, Toronto, Ontario, CanadaGoogle Scholar
  9. 9.
    Corella J, Toledo M, Molina G (2007) A review on dual fluidized-bed biomass gasifiers. Ind Eng Chem Res 46:6831–6839CrossRefGoogle Scholar
  10. 10.
    Jüntgen H, van Heek KH (1975) Gasification of coal with steam. Nucl Eng Des 34:59–63CrossRefGoogle Scholar
  11. 11.
    Jüntgen H, van Heek KH (1981) Kohlevergasung. Verlag Karl Thiemig, München (in German)Google Scholar
  12. 12.
    Gokarn AN, Mühlen H-J (1995) Catalysis of coal gasification by Na lignosulfonate. Fuel 74(1):124–127CrossRefGoogle Scholar
  13. 13.
    Lee JM et al (1998) Catalytic coal gasification in an internally circulating fluidized bed reactor with draft tube. Appl Therm Eng 18:1013–1024CrossRefGoogle Scholar
  14. 14.
    Kubiak H, Schröter H, Sulimma A, van Heek K-H (1983) Application of K2CO3 catalysts in the coal gasification process using nuclear heat. Fuel 62(2):242–245CrossRefGoogle Scholar
  15. 15.
    Mansour M (1989) et al. Pulse-enhanced indirect gasification for black liquor recovery. In: Preprints of the 1989 International Chemical Recovery Conference, Ottawa, Canada, pp. 217–221Google Scholar
  16. 16.
    Metz T (2000) Betriebsverhalten eines Pulsbrenners, dipl. th., TU München (in German)Google Scholar
  17. 17.
    Williams RH, Larson ED, Katofsky RE, Chen J (1995) Methanol and hydrogen from biomass for transportation. Energy Sustain Dev 1(5):18–34CrossRefGoogle Scholar
  18. 18.
    Karl J, Schmitz W, Hein D (2001) Allothermal gasification in fluidized bed gasifiers. In M. Kwauk, J. Li, W.-Ch. Yang (Ed.) Fluidization X, Proc. of the 10th Eng. Found. Conf on Fluid., UEF, New York, 2001Google Scholar
  19. 19.
    Dunn PD, Reay DA (1994) Heat pipes, 4th edn. Pergamon-Press, OxfordGoogle Scholar
  20. 20.
    European Patent, Device for the gasification of carbonaceous feedstock, EP000001187892B1Google Scholar
  21. 21.
    Metz T (2007)Allotherme Vergasung von Biomasse in indirekt beheizten Wirbelschichten, Fortschr.-Ber. VDI Reihe 6, Nr. 554, VDI-Verlag, DüsseldorfGoogle Scholar
  22. 22.
    Metz T, Kuhn S, Karellas S, Stocker R, Karl J, Hein D (2004) 10.05.2004 Experimental results of the biomass heatpipe reformer. 2nd World Conference and Technology Exhibition on Biomass for Energy, Industry and Climate Protection, Rome, ItalyGoogle Scholar
  23. 23.
    Gallmetzer G et al (2012) The agnion heatpipe-reformer—operating experiences and evaluation of fuel conversion and syngas composition. Biomass Convers and Biorefinery 2(3):207–215CrossRefGoogle Scholar
  24. 24.
    Ahrenfeldt J, Thomsen T, Henriksen U, Clausen L (2013) Biomass gasification cogeneration—a review of state of the art technology and near future perspectives. Appl Therm Eng 50:1407–1417CrossRefGoogle Scholar
  25. 25.
    Lettner F, Haselbacher T, Timmerer H, Leitner P, Suyitno, Rasch B (2007) Latest results of Cleanstgas—clean staged biomass CHP. 15th European Biomass Conference & Exhibition, Berlin, Germany 1035–1039Google Scholar
  26. 26.
    Neubauer Y (2011) Strategies for tar reduction in fuel-gases and synthesis-gases from biomass gasification. Journal of Sustainable Energy & Environment Special Issue 67–71Google Scholar
  27. 27.
    Hauth M, Lerch W, König KH, Karl J (2011) Impact of naphthalene on the performance of SOFCs during operation with synthetic wood gas. J Power Sources 196(17):7144–7151CrossRefGoogle Scholar
  28. 28.
    Biollaz SMA, Hottinger P, Pitta C, Karl J (2009) Results from a 1200 hour test of a tubular SOFC with woodgas. 17th European biomass conference & exhibition, Hamburg: ETA Florence 635–638Google Scholar
  29. 29.
    Karellas S, Karl J, Kakaras E (2008) An innovative biomass gasification process and its coupling with microturbine and fuel cell systems. Energy 33:284–291CrossRefGoogle Scholar
  30. 30.
    Karl J, Karellas S. Highly efficient SOFC systems with indirect gasification. Proceedings 6th European Solid Oxide Fuel Cell Forum, Lucerne, 2004, vol. 2, S. 534–545 Google Scholar
  31. 31.
    Pfeifer C, Puchner B, Hofbauer H (2009) Comparison of dual fluidized bed steam gasification of biomass with and without selective transport of CO2. Chem Eng Sci 64:5073–5083CrossRefGoogle Scholar
  32. 32.
    Karl J (2008) Distributed generation of substitute natural gas from biomass. In: Proceedings 16th European biomass conference and exhibition; Valencia p. 2515–2519Google Scholar
  33. 33.
    Gröbl T, Walter H, Haider M (2012) Biomass steam gasification for production of SNG—process design and sensitivity analysis. Appl Energy 97:451–461CrossRefGoogle Scholar
  34. 34.
    Kienberger T, Mair S, Karl J (2010) Fixed-bed methanation of biogeneous syngas, ideas for the decentralized approach, from research to industry and markets: Proceedings of the 18th European Biomass Conference, S. 1840–1847Google Scholar
  35. 35.
    Karellas S, Panopoulos KD, Panousis G, Rigas A, Karl J, Kakaras E (2012) An evaluation of substitute natural gas production from different coal gasification processes based on modeling. Energy 45:183–194CrossRefGoogle Scholar
  36. 36.
    Baumhakl C, Kienberger T, Karl J (2012) Substitute natural gas (SNG) from coal and lignite—methanation of synthesis gas from allothermal gasification. Proceedings of the 37th International Conference on Clean Coal & Fuel Systems, Clearwater, Florida, 3.6.2012-7.6Google Scholar
  37. 37.
    Gomez-Barea A, Leckner B (2010) Modeling of biomass gasification in fluidized bed. Prog Energy Combust Sci 36:444–509CrossRefGoogle Scholar
  38. 38.
    Kuhn S (2007) Funktions- und Betriebssicherheit eines druckaufgeladenen Wirbelschichtvergasers. PhD thesis, TU München (in German)Google Scholar
  39. 39.
    Karl J, Hein D (2002) Performance characteristics of the biomass heatpipe reformer. Proc. of the 12th European Conf. on Biomass for Energy, AmsterdamGoogle Scholar
  40. 40.
    German patent (2011) DE 10 2008 055 947 84Google Scholar
  41. 41.
    German patent application (2010) DE 10 2009 017 854 A1Google Scholar
  42. 42.
    Basu P (2006) Combustion and gasification in fluidized beds. CRC Press, Boca RatonCrossRefGoogle Scholar
  43. 43.
    Karellas S, Karl J (2007) Analysis of the product gas from biomass gasification by means of laser spectroscopy. Opt Lasers Eng 45:935–946CrossRefGoogle Scholar
  44. 44.
    Reschmeier R, Karl J (2013) Kinetik der Pyrolyse von Holzwürfeln in Wirbelschichten, 26. Deutscher Flammentag - VDI Bericht Nr 2161:727–731 (in German)Google Scholar
  45. 45.
    Karellas S, Kakaras E, Papadopoulos T, Schäfer C, Karl J (2008) Hydrogen production from allothermal biomass gasification by means of palladium membranes. Fuel Process Technol 89:582–588CrossRefGoogle Scholar
  46. 46.
    de Atkins P, Paula J (2007) Physikalische Chemie, 4th edn. Willey-VCH, WeinheimGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Lehrstuhl für EnergieverfahrenstechnikFriedrich-Alexander-Universität Erlangen-NürnbergNurembergGermany

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