While making biochar in lab or workshop using systems like muffle furnace or fixed bed pyrolyser or other pyrolyser systems, the nitrogen gas inlet (inert gas) should be placed within the pyrolysis reactor (like in picture B) or outside of the reactor in the furnace space (like in picture A)?
Also, the vapor outlet should be directly connected to the pyrolysis reactor (like in picture B) or just to the furnace (like in picture A)?
Thank you so much for your answers.
Dear Dr Farhad Khorsandi ,
The set up in Figure B is the correct way to carry out pyrolysis. The aim of using nitrogen (Helium or Argon will also suffice) is create an inert environment and purge out evolved gases (condensable and non condensable gases) so that the feedstock undergoes pyrolysis as opposed to combustion (oxidising environment).
That said, the set up in Figure A will also undergo pyrolysis, however the mass yield of biochar will be lower with higher ash compared to the biochar from Figure B. For comparison, you can carry out the experiments under both conditions and you will be able to confirm this.
Hope this helps. Best regards,
BBN
Dear Dr. Nyakuma
Thank you so much for your very helpful answers.
Good luck and wishing you all the best
Dear Farhad Khorsandi,
is the lid movable or fixed to the container? How much biomass do you put inside? You can write down the stoichiometric equation for combustion of your biomass and, knowing the amount of biomass inside the container, you can calculate the amount of O2 required to fully combust it. Using the ideal gas equation you can than convert the mass of oxygen required into volume (example for rice husk provided here: Article Improved Gasification of Rice Husks for Optimized Biochar Pr...
). Finally you can compare the calculated volume of O2 required for full combustion with actual amount available. If the actual amount available is say
Dear Robert, Greetings and thank you so much for the very helpful and technical answer. In such small scale muffle furnace set up, the lids are removable and usually about 100-200 g of feedstock is used to make biochar (for research purpose only). I've doubted if for such small amounts purging would be really necessary or not, but for research purpose and creating the ideal environment, it might be justifiable. However, I agree with you that in practice it would be economically feasible in a commercial setting.
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