Experimental Research On Biomass Pyrolysis Carbonization

Under the dual pressure of energy reserve shortage and environmental pollution, development and utilization of biomass drew widespread attention. In spite of incomparable advantages, there are still many obstacles for large scale usage of biomass, such as difficult to collect, perishable, low energy density,difficult to transport and store, seasonal production and other issues. How to use biomass resources with low-cost and high efficiency is a hot spot in current research. As an efficient usage way of biomass, pyrolysis carbonization can transform biomass into biomass charcoal, gas and biomass oil, which is of high value-added. Easy to realize industrial production and low cost make pyrolysis carbonization a cutting-edge technology in biomass utilization field. In this paper,sawdust, rice husk and leather scraps were chosen as materials to research pyrolysis carbonization systematically.Firstly, industrial analysis, elemental analysis and heat of raw material were measured, and pyrolysis characteristics of the materials under different heating rates were studied with TG-FTIR under a nitrogen atmosphere. The results showed that compared with coal, biomass appeared low calorific value and high volatile content.TGA results also showed that in the range of 5~50℃/min, heating rate has little effect on total weight loss of biomass samples. With the data obtained by TG, kinetic parameters of three materials were calculated with Kissinger method, results showed that activation energy of leather scrap is 82.7049kJ/mol,higher than that of saw dust and rice husk。Based on previous studies, experiments of biomass pyrolysis with different final pyrolysis temperature were carried on a self-built fixed-bed bench under nitrogen atmosphere. The results showed that, of the three kinds of charcoal, saw-dust charcoal appeared the best with a fixed carbon content of 75.89% and ash content of 16.35%;ash content in rice husk charcoal could reach 28.94% and fixed carbon content is64.52%; charcoal of leather scraps is the poorest, with a ash content of 65.02%, fixed carbon content of 30.67%. What’s more, charcoal of leather scraps is difficult to use due to existence of chromium. Yield of saw-dust charcoal is 29.9%, while rice husk and leather scrap charcoal had a yield of 32% and 33.8%Compared with fixed-bed, fluidized bed has many advantages, so pyrolysis of saw-dust on fluidized bed were studied. As leather scraps charcoal is difficult to use,experiments on combustion of leather scrap were studied. Finally, simulations wereconducted with Aspen Plus to make an extended forecasts. The results showed that:with reasonable operating conditions, fixed carbon content of saw-dust charcoal obtained from fluidized bed could reach 71.28%, but the charcoal yield from fluidized bed is only 21.6%, calorific value of gas can reach 3234.8kJ/Nm3. Leather scraps were stable and fully combusted in fluidized bed. Results got from simulation were similar with those got from experiments.