Roadside waste can be considered as a potential biomass source for biochar technology in the present scenario. However, the heterogeneous nature of such wastes is the major concern to be best fit as raw material for pyrolysis process. It would be great to know about the major precautions cum pre-conditioning of such waste during the pyrolysis process. Because most of these wastes contain aromatic structures which might led to massive production of PAHs like species.
Looking forward for potential suggestions....
Dear Rishikesh Singh,
First, I would pay attention to lignocellulosic composition. Lignin is, possibly, responsible for PAHs emissions. So IR analysis could be suitable for rapidly identify aromatic compounds in your raw material.
Another important aspect would be the heating rate and the heat transfer in particles. Therefore, within a sensitive range, I would choose the slowest heating rate possible.
Greetings from Spain!
Dear Rishikesh,
Firstly you must need to classified and characterize the wastes, to clearly understand their composition by using different characterization techniques.
Second part is make some lab scale experiments for determining the PAHs emission potential of individual and heterogeneous mixture of the waste. Or You may try to find this information by review of literature's.
And, application field is also important factor which need your attention before waste pyrolysis (biochar preparation).
For PAHs emission minimization during pyrolysis of lignocellulosic waste, Sergio Nogales make really a good suggestion.
Your welcome for any future concerned or discussion in details.
With best regards.
Thank you Dr. Sergio Nogales and Dear Sandeep Kumar. I appreciate your suggestions and kind greetings.
With your suggestions, it is obvious that I have to take initial drying, grinding and then initial structural and functional group analysis. And the slow pyrolysis can be a better option to proceed for heterogeneous wastes.
Thank you once again.
You need to take care of the actual pyrolysis temperature in order not to get emissions of generated (and not destroyed) unwanted pyrolysis products
Thank you Prof. Lars Carlsen.
The suggestions revealed that the low temperature pyrolysis would be beneficial for such materials.
Thank you All once again.
Temperature is a determining factor in the composition of the gases, vapors and liquids generated fro pyrolysis, being richer in hydrogen with elevated temperatures. Secondary decomposition products are also of concern at higher temperatures. Cellulosic wastes like those collected from roadside are usually rich with lignocellulosic components and frequently result in the generation of relatively large amounts of CO2. Products like methanol, methane, ethane, and acetaldehyde are usual products.... You may refer to
Journal of Analytical and Applied Pyrolysis (Impact Factor: 3.07). 04/1988; 13(3):233. DOI: 10.1016/0165-2370(88)80025-1
and
Thermochimica Acta (Impact Factor: 2.11). 04/2013; DOI: 10.1016/0040-6031(86)85295-9
Regards
PAH generation and final concentration in the biochar is rather depending on the process conditions and the reactor set up and not the fuel itself. So you need to take care to avoid the condensation of (possibly) tar loaded syngas on the biochar streams produced. In our lab we use a counter current flow of N2 or Ar that flushes the syngas away from the solid biochar (in the case of a pyrolyser) or we harvest the char from the hot parts of a fluidized bed gasification unit, before the mix of syngas and biochar cools down. Yes, I agree we the above comments on taking care of the pyrolysis temperature, but the main principle is, avoid syngas condensing on biochar.
Thank you Dr. Lydia Fryda for your critical insight on my query. It would be really helpful for me to consider during the pyrolysis process.
Agree with Lydia : avoiding condensation of syngas is important in all pyrolysis but especially so for your feedstock. Cold spots in the reactor and/or blockages are usually the culprits. Post-production procedures with demonstrated effectiveness in reducing mobile compounds from biochar (including PAHs) include thermal treatment and water leaching. Longer retention times at higher temperatures might work.
See attached for more information
Article Germination Tests for Assessing Biochar Quality
Article Toxicity of biochars after polycyclic aromatic hydrocarbons ...
Conference Paper Rescuing biochar: Pre - application techniques to enhance pl...
Thank you Dr. Nigel Gale for your suggestion and the literatures attached.
Regards,
Rishikesh
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