Experiment on In-situ Oxygen-lean Conditioning on Biomass Pyrolysis Volatiles

With regard to the distributed bio-char production technology that combusting pyrolysis volatiles for its heat resource, and aimed at eliminating charcoal particles, decreasing heavy components and increasing light components in pyrolysis volatiles, thereby improving the combustion characteristics of pyrolysis volatiles, by using an auger reactor for continuous pyrolysis of biomass and an oxygen-lean conditioning reactor for pyrolysis volatiles, with the stoichiometric air rate of combusting charcoal particles in pyrolysis volatiles as the basis, the experimental study on in-situ oxygen-lean conditioning on biomass pyrolysis volatiles was carried out. The influences of conditioning temperatures and air rates on the components of pyrolysis volatiles were analyzed. The experimental conditions were as follows: pyrolysis temperature of 550℃, biomass feeding rate of 527 g/h, pyrolysis residential time of 10 min, and the control temperature for charcoal tank was 250℃; the conditioning temperatures were 350℃, 400℃, 450℃ and 500℃, respectively, and the air rates were 20 mL/min, 40 mL/min, 60 mL/min and 80 mL/min, respectively. The results showed that the particle size of charcoal in the pyrolysis volatiles was 1~2 μm, and it was difficult to collect the particles at the conditioning temperature of 350℃ with air rate of 20 mL/min, in-situ oxygen-lean conditioning may eliminate the charcoal particles in pyrolysis volatiles; in-situ oxygen-lean conditioning had less influences on the gas components of pyrolysis volatiles, the changing rates of H2 and CO2 were all within ±5%, the influences were even weak for CO and CH4 whose changing rates were within ±2%; along with the elevating of conditioning temperature and the increase of the air rate, the contents of alkyl group chemicals in the heavy components of pyrolysis volatiles showed obvious decrease while the phenols showed evident increase, a little bit of increase in contents was found for the lower-content chemicals such as furans, alcohols, indenes and aldehydes. The contents of lower carbon compounds were increased while the higher carbon compounds were decreased; the relative contents of alkyl group, acids, ketones and phenols in light components of pyrolysis volatiles showed obvious changes, and the changes of phenols' absolute contents were not obvious due to their chemical stabilities, similar to that in the heavy components of pyrolysis volatiles, the lower carbon compounds in light components of pyrolysis volatiles had also shown increases. Due to the feasibility of eliminating the charcoal particles, decreasing heavy components and increasing light components in pyrolysis volatiles, in-situ oxygen-lean conditioning may improve the combustion characteristics of pyrolysis volatiles, the research results could be used as reference for distributed bio-char production which pyrolysis volatiles were combusted for pyrolysis. © 2017, Chinese Society of Agricultural Machinery. All right reserved.