Developing a free-fall reactor for rice straw fast pyrolysis to produce bio-products

Recently, the world energy demand is increasing due to the growing world population. Accordingly, many research works are directed toward the new resources of renewable energy in order to compensate the shortage in petroleum based products. The use of biomass as a source for renewable energy is of growing importance. One of the most problematic agriculture wastes in Egypt is rice straw which is generated in huge amounts over a limited harvesting period. In this study the main objective is to develop and design a new rice straw fast pyrolysis reactor that improves some inefficiencies in traditional reactors while maintaining high bio-oil yields. To accomplish this target, a laboratory scale plant with a free-fall reactor was designed to avoid lack of moving parts; Compared it with other plants, the designed under investigation plant has the advantage of simple design. Two basic principles were combined in the design of the free-fall reactor; the first principle dealt with the particle heating rate, while the second considered the particle’s free-fall velocity. Based on this developed and designed free-fall reactor, the fast pyrolysis process of rice straw was carried out at temperatures ranging from 450 °C to 700 °C. The obtained bio-products from this process are liquid bio-oil, bio char and non-condensable gases. The characterization and chemical composition of the bio-oil and non-condensable gases were determined, respectively. It was concluded that the above mentioned free-fall reactor can be used for producing useful bio-products from rice straw and sharing to solve the most problematic agriculture waste. Keywords: Fast pyrolysis, Rice straw, Free fall reactor, Pyrolysis product