Fw: GAS-L: Nitrogen in wood

["Tom Miles" <tmiles@trmiles.com>]

Forwarded to the list:

 

From: W.deJong@wbmt.tudelft.nl

Sent: Tuesday, September 04, 2001 4:16 AM

Subject: Re: GAS-L: Nitrogen in wood

Dear Jim,

you wrote:
> Does anyone have any data on the percentage of nitrogen typically
> found in wood, and what affects this percentage, e.g. age of tree,
> soil conditions, nutrients available etc.?

Typical Nitrogen contents in wood (clean core material) are ca. or less than 0.1 %. When bark is present, values can increase to about 0.6%. Needles and leaves even contain more bound Nitrogen till values of about 1%. A database for fuel compositions of a broad range of fuels can be found at the ECN site:

http://www.ecn.nl/phyllis/

you wrote:
> Where is this nitrogen in the wood, e.g. in the ash, or as part of a
> molecule in the wood structure?

Nitrogen is mainly in the form of proteins, alkaloids (wood cell matter) and in the green
matter (leaves e.g.) as chlorophyl, which is a magnesium- containing pyrrole derivative.

you wrote:
> How much of the nitrogen forms ammonia and cyanide in a gasification
> process, and what influences this?

In fluidised bed gasification processes a large amount of the fuel bound Nitrogen is converted into ammonia: for bottom fed fluidised bed gasifiers in the range of ca. 50 to almost 100% for biomass. HCN formation is only a few %. It depends on the air stoichiometry (or: equivalence ratio) applied. It also seems that fuel feeding position has a significant influence on the fuel bound Nitrogen partitioning, in such a way that top fed fluid bed gasifiers show lower fuel_N to NH3 conversions. The background of this phenomenon would be that the initial flash pyrolysis of the fuel particle takes place in different environments: reducing and oxidizing for top fed and bottom fed systems respectively.

A study was published in fuel recently by KTH with work performed by a Delft University MSc student from our institute:

Vriesman, P., Heginuz, E. and Sjöström, K. (2000) Biomass gasification in a laboratory –scale AFBG: influence of the location of the feeding point on the fuel-N conversion, Fuel, Vol. 79, pp. 1371-1378.



Also, the fuel oxygen content has been reported to influence Nitrogen partitioning, especially phenolic OH-groups in the fuel structure could increase the conversion of nitrogen to NH3. Literature on this subject e.g. :

Hämäläinen J.P., Aho, M.J. and Tumavuori, J.L., (1994) Formation of nitrogen oxides from fuel_N through HCN and NH3: a model-compound study, Fuel, Vol. 73, pp. 1894-1898.


Further work related to fluidised bed gasification, also one including from our institute (in the framework of my PhD thesis work), not exhaustive but useful, e.g.:

de Jong, W., Unal, Ö, Hoppesteyn, P.D.J., Andries, J. and Hein, K.R.G. (2001) Pressurised gasification of biomass and fossil fuels in fluidised bed gasifiers, hot gas cleanup using ceramic filters and pressurised product gas composition. In Bridgwater, A.V. (Ed.): Progress in Thermochemical Biomass Conversion, pp. 473-487.

Van der Drift, A., Van Doorn, J. and Vermeulen, J.W. (2001)
Ten Residual biomass fuels for circulating fluidized-bed gasification, Biomass&Bioenergy, Vol. 20, pp. 45-56.

Leppälahti J. & Koljonen T. (1995) Nitrogen evolution from coal, peat and wood during gasification: literature review. Fuel Processing Technology, Vol. 43, pp. 1-45.



best regards,

Wiebren de Jong.

> Regards,
>
> Jim Bland
>
> Enecon Pty. Ltd.
> 35 Whitehorse Rd., Deepdene VIC 3103, Australia
> PO Box 555, Deepdene DC VIC 3103, Australia
> Tel: +61-3-9817 6255
> Fax: +61-3-9817 6455
> www.enecon.com.au
>
>
>
> -
> Gasification List Archives:
> http://www.crest.org/discussion/gasification/current/
>
> Gasification List Moderator:
> Tom Reed, Biomass Energy Foundation, Reedtb2@cs.com
> www.webpan.com/BEF
> List-Post: <mailto:bioenergy@crest.org>
> List-Help: <mailto:bioenergy-help@crest.org>
> List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
> List-Subscribe: <mailto:bioenergy-subscribe@crest.org>
>
> Sponsor the Gasification List: http://www.crest.org/discuss3.html -
> Other Gasification Events and Information:
> http://www.fsec.ucf.edu/bioam/
> http://solstice.crest.org/renewables/biomass-info/gasref.shtml
> http://solstice.crest.org/renewables/biomass-info/
>
>


------- End of forwarded message -------
Wiebren de Jong, MSc. TU Delft Faculty of Mechanical Engineering & Marine Technology Section Thermal Power Engineering (EV) Mekelweg 2 NL-2628 CD Delft The Netherlands Telephone: +31 15 2786751 Mobile: +31 6 51236425 Telefax: +31 15 2782460 e-mail at home: wkdejong@kabelfoon.nl e-mail general: wiebrendejong@hotmail.com