Development and assessment of a fast pyrolysis reactor for bio-oil, syngas and bio-char production from biomass residues

• Main Author: Razzaque, Md Abdur
• Published: University of Nottingham 2016
• Subjects: 660
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686880

Design, development and assessment of a Fluidized Bed Reactor (FBR) is a very complex process, where enormous empirical correlations; charts and graphs; lot of parameters, assumptions, unit operations are involved, straight forward design equations and design data are limited, and generally the operation of the system requires many adjustments. The improved design of FBR with high coefficient of performance (COP), low energy consumption, high yield and environmentally friendly (low emission) is the target. The scope of the study is to design and fabrication of a lab scale fluidized bed fast pyrolysis system with throughput capacity of 1 kg of dry biomass per hour which includes a bubbling fluidized bed reactor, 2 cyclone separators in series, 4 condensers in series operating between temperatures of 600-300; 300-200; 200-125 and 125-40˚C to selectively condense alkanes, phenols, aromatics, indene, methyl-indene, benzene, toluene, methyl–naphthalene, esters, acids, alcohols, ketones; 2 heaters (1 pre- and 1 primary), an auger feeder with hopper and controller, blowers and rig structure. A 3-D simulation was performed to facilitate the mounting of different unit operations, instruments and control panels with sufficient maintenance and manoeuvring accessibilities yet compact structure with low structural footprints. The rig is having the dimensions of 2204X2750X1100mm (L x H x W) and suitable for batch operation to produce about 650 gm bio-oil, 150 gm non-condensable and 200 gm bio-char from 1kg of dry biomass pyrolysis. The rig is manually operated, however the data acquisition and logging systems are digital and has provision of scrubbing exhaust gas, and an online analyser has been installed to measure and monitor lower hydrocarbons including hydrogen concentrations and Lower Explosive Limit (LEL) in the exhaust gas. Four types of biomass such as Empty fruit bunch (EFB), Urban tree shavings (UTS), Saw dust Broga (SDB) and Saw dust Semenyih (SDS) were pre-treated with aqueous acidic (H2SO4) and alkaline (NaOH) solutions to find the percentage of solids extraction with varying liquid-solid ratios, acid/alkali concentrations, reaction temperatures and retention time. For pyrolysis operation, UTS was selected among the four biomass samples with a set of pre-treatment parameters (4.81 wt. % H2SO4, 15:1 liquid-solid ratio, 4hr retention time, 70˚C, 100rpm agitation speed) that maximizes bio-oil production. Pyrolysis in a batch tubular furnace at 600˚C with nitrogen flowrate of 30 ml/min resulted in bio-oil yield of 39.43% and 27.67%, and char yield of 38.07% and 30.73% from raw and pre-treated UTS respectively. The semi-batch pyrolysis results were compared with biomass pyrolysis results from the batch pyrolysis rig operations. The catalytic upgrading of the bio-oil to liquid fuel in a batch reactor is ongoing research work. The contribution of this research can be summarised as the successful design, fabrication, testing and operation of a Fluidized Bed System to produce fuel from biomass in batch pyrolysis. Characterization of the feedstock to get the optimum operation condition of the designed FBR to get the best yield out of the system and evaluation of the performance characteristics (Mass and Energy Balance) of the system. Characterization of the products (bio-oil, bio-char and syngas) following standard methods having results comparable with literature.