Pooya Lahijani

Gasification of palm empty fruit bunch in a bubbling fluidized bed: A performance and agglomeration study

Gasification of palm empty fruit bunch (EFB) was investigated in a pilot-scale air-blown fluidized bed. The effect of bed temperature (650-1050 °C) on gasification performance was studied. To explore the potential of EFB, the gasification results were compared to that of sawdust. Results showed that maximum heating values (HHV) of 5.37 and 5.88 (MJ/Nm3), dry gas yield of 2.04 and 2.0 (Nm3/kg), carbon conversion of 93% and 85 % and cold gas efficiency of 72% and 71 % were obtained for EFB and sawdust at the temperature of 1050 °C and ER of 0.25. However, it was realized that agglomeration was the major issue in EFB gasification at high temperatures. To prevent the bed agglomeration, EFB gasification was performed at temperature of 770±20 °C while the ER was varied from 0.17 to 0.32. Maximum HHV of 4.53 was obtained at ER of 0.21 where no agglomeration was observed.

CO2 gasification reactivity of biomass char: catalytic influence of alkali, alkaline earth and transition metal salts.

This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3-7 wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5 wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5 wt% Na loaded char was calculated as 151.46 kJ/mol which was 53 kJ/mol lower than that of un-catalyzed char.

Microwave-enhanced CO2 gasification of oil palm shell char

CO2 gasification of oil palm shell (OPS) char to produce CO through the Boudouard reaction (C + CO2 ↔ 2CO) was investigated under microwave irradiation. A microwave heating system was developed to carry out the CO2 gasification in a packed bed of OPS char. The influence of char particle size, temperature and gas flow rate on CO2 conversion and CO evolution was considered. It was attempted to improve the reactivity of OPS char in gasification reaction through incorporation of Fe catalyst into the char skeleton. Very promising results were achieved in our experiments, where a CO2 conversion of 99% could be maintained during 60 min microwave-induced gasification of iron-catalyzed char. When similar gasification experiments were performed in conventional electric furnace, the superior performance of microwave over thermal driven reaction was elucidated. The activation energies of 36.0, 74.2 and 247.2 kJ/mol were obtained for catalytic and non-catalytic microwave and thermal heating, respectively.

Co-gasification of tire and biomass for enhancement of tire-char reactivity in CO2 gasification process

In this investigation, palm empty fruit bunch (EFB) and almond shell (AS) were implemented as two natural catalysts rich in alkali metals, especially potassium, to enhance the reactivity of tire-char through co-gasification process. Co-gasification experiments were conducted at several blending ratios using isothermal Thermogravimetric analysis (TGA) under CO2. The pronounced effect of inherent alkali content of biomass-chars on promoting the reactivity of tire-char was proven when acid-treated biomass-chars did not exert any catalytic effect on improving the reactivity of tire-char in co-gasification experiments. In kinetic studies of the co-gasified samples in chemically-controlled regime, modified random pore model (M-RPM) was adopted to describe the reactive behavior of the tire-char/biomass-char blends. By virtue of the catalytic effect of biomass, the activation energy for tire-char gasification was lowered from 250 kJ/mol in pure form 203 to 187 kJ/mol for AS-char and EFB-char co-gasified samples, respectively.

Ash of palm empty fruit bunch as a natural catalyst for promoting the CO2 gasification reactivity of biomass char

Palm empty fruit bunch ash (EFB-ash) was used as a natural catalyst, rich in potassium to enhance the CO2 gasification reactivity of palm shell char (PS-char). Various EFB-ash loadings (ranging from 0 to 12.5wt.%) were implemented to improve the reactivity of PS-char during CO2 gasification studies using thermogravimetric analysis. The achieved results explored that the highest gasification reactivity was devoted to 10% EFB-ash loaded char. The SEM-EDS and XRD analyses further confirmed the successful loading of EFB-ash on PS-char which contributed to promoting the gasification reactivity of char. Random pore model was applied to determine the kinetic parameters in catalytic gasification of char at various temperatures of 800-900°C. The dependence of char reaction rate on gasification temperature resulted in a straight line in Arrhenius-type plot, from which the activation energy of 158.75kJ/mol was obtained for the catalytic char gasification.

Fluidized Bed Gasification of Palm Empty Fruit Bunch Using Various Bed Materials

Gasification of palm empty fruit bunch was investigated in a pilot scale air-blown fluidized bed. Silica sand and calcined dolomite were used as the bed materials. The gasification performance was assessed at the bed temperature range of 650 to 850°C. Maximum heating value of 4.48 and 5.33 MJ/Nm3, gas yield of 1.62 and 1.68 Nm3 gas/kg, carbon conversion of 82.5 and 83%, and cold gas efficiency of 50.1 and 58.9% were, respectively, achieved for sand and dolomite at 850°C. Although the quality of producer gas improved at high temperatures, bed agglomeration, however, was observed as the major issue above 800°C for silica sand.

Air gasification of oil palm waste over dolomite in a fluidized bed

Air gasification of oil palm empty fruit bunch was carried out in a fluidized bed gasifier. Calcined dolomite was used as the catalytic bed material. The effect of bed temperature (650--1050 °C) on the quality of the producer gas was examined. During the gasification experiment, a producer gas with improved quality was obtained at high temperatures, but agglomeration of the bed material was realized as the major concern at temperatures above 850 °C. Thus, the temperature was reduced and the quality of the product gas was assessed through a set of experiments designed by response surface methodology. The bed temperature (T = 650--850 °C) and equivalence ratio (ER = 0.18--0.28) were selected as the 2 process variables. The experimental results were reasonably fitted to the developed model. The optimum conditions were T = 850 °C and ER = 0.22 at which the HHV = 5.39 (MJ/m3) could be attained without any agglomeration of the bed material.