Nitrogen compounds in pressurised bed gasification of biomass and fossil fuels

Research output: ThesisDissertation (TU Delft)


Abstract Fossil fuels still dominate the energy supply in modern societies. The resources, however, are depleting. Therefore, other energy sources are to be exploited further within this century. Biomass is one of the practically CO2 neutral, renewable contributors to the future energy production. Nowadays many modern, high efficiency (combined) power and heat producing systems using biomass are or become commercially available. One promising route to efficient power and heat supply is the Integrated Gasification Combined Cycle. This cycle is particularly of interest for medium to larger scale installations. Pressurised operation of the gasifier offers the advantage of smaller process equipment, including that for the necessary downstream gas cleaning. Also, the work needed to compress the gas for gasturbine use will be much smaller or not needed at all.High temperature gas filtration offers the benefit of increased overall efficiencies of the power and heat producing cycle. This integrated gasification technology, however, is still in a stage of development and demonstration.When instead of absorption gas cleaning, high temperature, dry gas filtration is applied, nitrogen compounds, like ammonia (NH3) and hydrogen cyanide (HCN), are not dissolved in the absorption liquid. As a result NOx emissions in gas turbine combustors are produced. NOx is known for its negative effects on the health of humans and animals and acidification of soil and water. Therefore, increasingly stringent emission restrictions are imposed on this component. Both coal and biomass contain nitrogen in their chemical structure and in gasification processes this so-called fuel bound nitrogen is converted to a large extent into NOx precursors.This PhD thesis assesses the experimental and theoretical work which was performed to study the behaviour of nitrogen compounds during air blown pressurised stationary fluidised bed gasification of biomass and brown coal, followed by high temperature ceramic gas filtration. Gasification experiments have been performed using a 1.5 MWthermal pilot plant situated in Delft and a smaller scale test rig at the university of Stuttgart. Under the pressurised fluidised bed gasification conditions studied, the main fuel bound nitrogen component produced is NH3, whereas HCN is formed to a minor extent (only a few percent of the fuel bound nitrogen). In cooperation with TU Eindhoven, small-scale fuel characterization experiments have been carried out to obtain model parameters for the gasification process. These form the input basis of a gasifier model that has been validated with measurements at the pilot facilities.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Delft University of Technology
  • Hein, KRG, Supervisor
  • Moulijn, J.A., Advisor
Award date7 Feb 2005
Place of PublicationDelft, The Netherlands
Print ISBNs90-8559-028-0
Publication statusPublished - 2005


  • authored books
  • Diss. prom. aan TU Delft


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