NO Formation Tendency Characterization for Biomass Fuels

2005 ◽  
Author(s):  
Jukka Konttinen ◽  
Mikko Hupa ◽  
Sirpa Kallio ◽  
Franz Winter ◽  
Jessica Samuelsson
Keyword(s):  
Fluidized Bed ◽  
Large Scale ◽  
Small Scale ◽  
Volatile Components ◽  
Fluidised Bed ◽  
Fluidized Bed Combustion ◽  
No Emission ◽  
Biomass Waste ◽  
No Formation ◽  
Air Staging

When a solid fuel, such as coal, biomass or a mixture of these fuels, enters a hot fluidized bed, the volatile carbon and nitrogen compounds are released, while some nitrogen and carbon remains in the solid char. Volatile nitrogen can form reactive species such as NH3, HCN and tar-nitrogen. These can react in the presence of oxygen to NO (and some N2O). Some part of volatile nitrogen is always reduced to N2. During combustion of the char residue, some part of the char-nitrogen forms NO (or N2O) and the rest is converted to N2. Usually the standard fuel analysis is not enough to allow for accurate NO emission predictions in large scale fluidized bed combustion. This paper presents NO formation tendency characterization results from novel laboratory measurements in a small-scale fluidised bed combustor. The laboratory results of this paper give a good insight into the distribution of fuel nitrogen between reactive and non-reactive (N2) volatile components and char-nitrogen. A NO formation tendency database is formed based on the results, including data on biomass-, waste-, peat- and coal-type fuels. The combustion test results show that the cumulative conversion of fuel nitrogen to NO under lean, non-staged fluidized bed combustion is 20–50% (850°C with O2 in excess). For biomass and peat, nearly all reactive nitrogen (forming NO) is released from the fuel during pyrolysis. NO formation during char combustion is significant with coal. With the help of the database, a reasonable estimate of the maximum non-staged NO emission in fluidized bed combustion can be obtained. Normally, air staging is utilized to reduce NO emissions. Effects of air-staging can be studied by means of modelling. In case of a BFBC boiler, the data can be used as input in the design or modelling of air staging for freeboard. For CFBC, the data can be used as input in the NO prediction where the once formed NO is further reduced by char carbon.

Analysis and Comparison of Biochar From Pilot Scale Downdraft Gasifier

2015 ◽  
Author(s):  
Tejasvi Sharma ◽  
Yunye Shi ◽  
Guiyan Zang ◽  
Albert Ratner
Keyword(s):  
Large Scale ◽  
Pilot Scale ◽  
Proximate Analysis ◽  
Small Scale ◽  
Volatile Components ◽  
Composition Analysis ◽  
Reduction Zone ◽  
Downdraft Gasifier ◽  
Porosity Analysis ◽  
Corn Grains

Gasification is incomplete combustion of solid fuel that results in the production of vapor, often referred to as syngas or producer gas, char, and tar. When this process is applied to biomass, the resulting char, referred to as biochar, is produced and has been shown to enhance soil fertility and crop growth. As part of a broader effort, this work examines how the gasification process impacts the biochar generated through downdraft gasification. In contrast to previous publications, which only focused on the syngas compositions, this research paper expands the analysis to the composition of the biochar produced in the gasification systems. In a large-scale gasifier, corn grains at about a 15% moisture level are inserted into a pilot scale downdraft gasifier from the top. In this system, both air and fuel move in the same direction. The air entering the setup is controlled using a damper. Corn grains entering the gasifier pass through a drying zone where the moisture content in it is removed. The dry corn then passes through a combustion and pyrolysis zone, followed by a reduction zone. The high temperature present at the bottom in the reduction zone cracks any tar present in the syngas produced. This syngas exits from the bottom of the gasifier. The char produced has a residence time from half an hour to several hours. About 20% of the fuel that’s inserted in the gasifier is converted to biochar. An ultimate and proximate chemical composition analysis, BET porosity analysis, and an SEM image analysis were carried out on the biochar produced from this system. From the SEM analysis, a surface area of 2.38 m2/g was obtained. From the ultimate and proximate analysis, it was observed that the biochar had higher carbon content and a lack of volatile components compared to other reported biochars and levels similar to activated carbon. From the BET porosity analysis, both small scale and large-scale pores were observed but quantified comparison with other biochar is still on going. Porosity is known to be an important factor in biochar effectiveness as a soil amendment.

scholarly journals Research in the fluidized bed combustion in the Laboratory for thermal engineering and energy - Part B: Achievements in technology implementation

2019 ◽  
Vol 23 (Suppl. 5) ◽  
pp. 1655-1667
Author(s):  
Borislav Grubor ◽  
Dragoljub Dakic ◽  
Stevan Nemoda ◽  
Milica Mladenovic ◽  
Milijana Paprika ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Technology Implementation ◽  
Liquid Fuels ◽  
Thermal Engineering ◽  
Fluidized Bed Combustion ◽  
Biomass Waste ◽  
Technology Application ◽  
Wide Range ◽  
Combustion Technology ◽  
Bed Agglomeration

Paper gives a review of the most important results of extensive and wide-ranging research program on R&D of fluidized bed combustion technology in the Laboratory for Thermal Engineering and Energy of the VINCA Institute of Nuclear Sciences. Paper presents detailed overview of R&D activities from the beginning in the second half of the 1970's up to present days. These activities encompass applied research achievements in the field of characterization of limestones and bed agglomeration and sintering and modeling of overall processes during fluidized bed combustion, all of which have facilitated the R&D of the fluidized bed combustion technology. Attention is also given to steady-state combustion testing of a wide-range of fuels (coals, liquid fuels, biomass, waste solid and liquid materials, etc.) in our fluidized bed combustor and development of original methodology for testing the suitability of fuels for fluidized bed combustion, as well as specific achievements in the area of technology application in Serbia.

scholarly journals Atmospheric fluidized bed combustion for small scale market sectors. Final report

1997 ◽  
Author(s):  
R.A. Ashworth ◽  
D.A. Plessinger ◽  
T.M. Sommer ◽  
H.M. Keener ◽  
R.L. Webner
Keyword(s):  
Fluidized Bed ◽  
Small Scale ◽  
Final Report ◽  
Fluidized Bed Combustion

scholarly journals A scalable Euler–Lagrange approach for multiphase flow simulation on spectral elements

2019 ◽  
Vol 34 (3) ◽  
pp. 316-339 ◽  
Author(s):  
David Zwick ◽  
S Balachandar
Keyword(s):  
Multiphase Flow ◽  
Fluidized Bed ◽  
Large Scale ◽  
Message Passing Interface ◽  
Flow Simulation ◽  
Small Scale ◽  
Ghost Particle ◽  
Dense Particle ◽  
Wide Range ◽  
Individual Particles

Multiphase flow can be difficult to simulate with high accuracy due to the wide range of scales associated with various multiphase phenomena. These scales may range from the size of individual particles to the entire domain of interest. Traditionally, large scale systems can only be simulated using averaging approaches that filter out the locations of individual particles. In this work, the Euler–Lagrange method is used to simulate large-scale dense particle systems in which each individual particle is tracked. In order to accomplish this, the highly scalable spectral element code nek5000 has been extended to handle the multiple levels of multiphase coupling in these systems. These levels include what has been called one-, two-, and four-way coupling. Here, each level has been separated to detail the computational impact of each stage. A binned ghost particle algorithm has also been developed to efficiently handle the challenges of two- and four-way coupling in a parallel processing context. The algorithms and their implementations are then shown to scale to 65,536 Message Passing Interface (MPI) ranks in both the strong and weak limits. After this, validation is performed through simulation of a small-scale fluidized bed. Lastly, a large-scale fluidized bed is simulated with 65,536 MPI ranks and is able to capture the unique physics of the onset of fluidization.

LES for NO Prediction in a Propane-Air Turbulent Flame

2007 ◽  
Author(s):  
Sreebash C. Paul ◽  
Manosh C. Paul ◽  
William P. Jones
Keyword(s):  
Large Scale ◽  
Turbulent Flame ◽  
Combustion Process ◽  
Thermal Reaction ◽  
Small Scale ◽  
Governing Equations ◽  
Flamelet Model ◽  
Eddy Simulation ◽  
No Formation ◽  
Large Eddy

Formation of nitric oxide (NO) in a model cylindrical combustor is investigated by applying Large Eddy Simulation (LES) technique. Gaseous propane (C3H8) is injected through a circular nozzle attached at the centre of the combustor inlet and preheated air with temperature of 773K is supplied through the annulus surrounding of the nozzle. The non-premixed combustion process is modelled via conserved scalar approach with laminar flamelet model, while in NO formation model, the extended Zeldovich (thermal) reaction mechanism is taken into account through a transport equation for NO mass fraction. In LES the governing equations are filtered using a spatial filtering approach to separate the flow field into large scale eddies and small scale eddies. The large scale eddies are resolved explicitly while the small scale eddies are modelled via Smagorinsky model.

Representation of a small-scale nozzle for gas–liquid injections into a fluidized bed on a large-scale grid

2014 ◽  
Vol 62 ◽  
pp. 117-124
Author(s):  
Konstantin Pougatch ◽  
Martha Salcudean ◽  
Kevin Reid ◽  
Jennifer McMillan
Keyword(s):  
Fluidized Bed ◽  
Large Scale ◽  
Small Scale ◽  
Large Scale Grid ◽  
Scale Grid
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