Pyrolysis of palm oil solid waste using helical screw fluidized bed reactor / Khan Muhammad Qureshi

Khan Muhammad , Qureshi (2021) Pyrolysis of palm oil solid waste using helical screw fluidized bed reactor / Khan Muhammad Qureshi. PhD thesis, Universiti Malaya.

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Abstract

Biomass pyrolysis processes for bio-oil production were commonly done using batch, semi-continuous or continuous process. However, past studies have shown many concerning issues in regard to the use of batch process such as high residence time, product inconsistencies across batches, high labor cost and difficulty in industrial scale up. Therefore, a quantitative study was performed using slow and fast pyrolysis mode over novel Helical Screw Fluidized Bed Reactor (HSFBR) stainless-steel (CS309) with an internal diameter of 228 mm and total length of 1,524 mm using palm shell (PS) for bio-oil production. The stainless-steel (CS309) helical screw has a total length of 1,550 mm including 6 flights a pitch distance of 95.25 mm and an external diameter of 203.2 mm. Accordingly, this research aims to investigate the performance of novel HSFBR with some desired outcomes: high particle dynamics, heat transfer rate, feed rate, effect of temperature, pyrolysis time and vapor residence time with high liquid and low biochar yield with improved properties. The torque was optimized to 50 rpm with slow heating rate of 10°C/min to achieve 500°C without involving any inert gas. The maximum quantity of organic phase with lower oxygen content and biochar products were obtained with 51.6 wt.% and 26.6 wt.%, respectively. The further experiments were performed with low, medium and high heating rates from 75 to 275°C/min at 50 rpm torque to achieve the reaction temperature of 500°C without involving any inert gas. Present study showed the major improvement in formation of organic yield was basically linked with increasing heating rate. The maximum bio-oil yield of 72.84 wt.% with HHV of about 44.41 MJ/kg was achieved at heating rate of 275°C/min, which is compatible with the diesel fuel HHV (45 MJ/kg). The parametric results also showed that the temperature and the feed rate had significant effects on pyrolytic products. When pyrolysis temperature was increased from 400 to 650oC the yields of bio-oil and biochar were decreased while iv gas yield was increased. In addition, on increasing feed rate from 3 to 25 g/min the bio-oil and gas yield were increased, while biochar yield was decreased. The effect of particle size, pyrolysis time and vapor residence time showed the optimum bio-oil yield obtained at 2 mm particle size, 30 min pyrolysis time and 0.25s vapor residence time with (72.11 wt.%), (72.40 wt.%) and (73.86 wt.%), respectively at 500oC. In addition, 10 mm particle size also showed an acceptable bio-oil yield of 71.23 wt.% which saved the costs of biomass grinding and size reduction time. The optimum value of HHV for fuel properties of bio-oil (organic phase) at 0.25 mm particle size, 30 min pyrolysis time and 0.25 vapor residence time were found 42.80, 43.02 and 43.14, respectively. The qualitative and quantitative evaluation of pyrolytic products (organic phase and by-product biochar) strongly suggests their significance in liquid and solid fuel applications. These findings of novel HSFBR reactor technology ranked well for biomass material and have provided a good understanding when it was used in pyrolysis modes slow medium and high heating rate.

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