Effect of the addition of different waste carbonaceous materials on coal gasification in CO2 atmosphere

YesIn order to evaluate the feasibility of using CO2 as a gasifying agent in the conversion of carbonaceous materials to syngas, gasification characteristics of coal, a suite of waste carbonaceous materials, and their blends were studied by using a thermogravimetric analyser (TGA). The results showed that CO2 gasification of polystyrene completed at 470 °C, which was lower than those of other carbonaceous materials. This behaviour was attributed to the high volatile content coupled with its unique thermal degradation properties. It was found that the initial decomposition temperature of blends decreased with the increasing amount of waste carbonaceous materials in the blends. In this study, results demonstrated that CO2 co-gasification process was enhanced as a direct consequence of interactions between coal and carbonaceous materials in the blends. The intensity and temperature of occurrence of these interactions were influenced by the chemical properties and composition of the carbonaceous materials in the blends. The strongest interactions were observed in coal/polystyrene blend at the devolatilisation stage as indicated by the highest value of Root Mean Square Interaction Index (RMSII), which was due to the highly reactive nature of polystyrene. On the other hand, coal/oat straw blend showed the highest interactions at char gasification stage. The catalytic effect of alkali metals and other minerals in oat straw, such as CaO, K2O, and Fe2O3, contributed to these strong interactions. The overall CO2 gasification of coal was enhanced via the addition of polystyrene and oat straw

Comparative study of the gasification of coal and its macerals and prediction of the synergistic effects under typical entrained-bed pulverized coal gasification Conditions

This research is focused on the gasification performance of coal and its corresponding macerals as well as on the interactions among macerals under typical gasification conditions by Aspen Plus modeling. The synergistic coefficient was employed to show the degree of interactions, while the performance indicators including specific oxygen consumption (SOC), specific coal consumption (SCC), cold gas efficiency (CGE), and effective syngas (CO + H2) content were used to evaluate the gasification process. Sensitivity analyses showed that the parent coal and its macerals exhibited different gasification behaviors at the same operating conditions, such as the SOC and SCC decreased in the order of inertinite > vitrinite > liptinite, whereas CGE changed in the order of liptinite > vitrinite > inertinite. The synergistic coefficients of SOC and SCC for the simulated coals were in the range of 0.94–0.97, whereas the synergistic coefficient of CGE was 1.05–1.13. Moreover, it was found that synergistic coefficients of gasification indicators correlated well with maceral contents. In addition, the increase in temperature was found to promote the synergistic coefficients slightly, whilst at an oxygen to coal mass ratio of 0.8 and a steam to coal mass ratio of 0.8, the highest synergistic coefficient was obtained

Kinetic study and synergistic interactions on catalytic CO2 gasification of Sudanese lower sulphur petroleum coke and sugar cane bagasse

In this study the effects of iron chloride (FeCl3) on the CO2 gasification kinetics of lower sulphur petroleum coke (PC) and sugar cane bagasse (SCB) via thermogravimetric analyser (TGA) were investigated. The FeCl3 loading effects on the thermal behaviour and reactivity of CO2 gasification of PC were studied. The possible synergistic interaction between the PC and SCB was also examined. Then the homogeneous model or first order chemical reaction (O1) and shrinking core models (SCM) or phase boundary controlled reactions (R2 and R3) were employed through Coats–Redfern method in order to detect the optimum mechanisms for the catalytic CO2 gasification, describe the best reaction behaviour and determine the kinetic parameters. The results showed that the thermal behaviour of PC is significantly affected by the FeCl3 loading. Among various catalyst loadings, the addition of 7 wt% FeCl3 to PC leads to improve the PC reactivity up to 39% and decrease the activation energy up to 22%. On the other hand, for char gasification stage of SCB and blend, the addition 5 wt% FeCl3 improved their reactivities to 18.7% and 29.8% and decreased the activation energies to 10% and 17%, respectively. The synergistic interaction between the fuel blend was observed in both reaction stages of the blend and became more significant in the pyrolysis stage. For all samples model R2 shows the lowest values of activation energy (E) and the highest reaction rates constant (k). Finally, model R2 was the most suitable to describe the reactions of non-catalytic and catalytic CO2 gasification

Characterization of Libyan metakaolin and its effects on the mechanical properties of mortar

Environmental concerns, stemming from high-energy demands and CO2 emission associated with cement manufacture, have brought about pressures to reduce cement consumption through the use of supplementary cementitious materials (SCMs). Besides addressing environmental concerns, the incorporation of SCMs in cement bound materials and concrete can modify and improve specific concrete properties. Metakaolin (MK) in an important SCM which can enhance the performance of cementitious composites through its high pozzolanic reactivity. This study was carried out to characterize the materials and to assess the effect of Libyan metakaolin (LMK) on the mechanical properties including the compressive strength of cement mortar. LMK was produced by calcining kaolinite clay at 700°C for 2 h. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis / Thermo-Gravimetric analysis (DTA/TG) and Fourier Transform Infrared Spectroscopy (FTIR) s were performed on the raw and calcined kaolinite powders. Seven mixes were prepared with different LMK replacement percentages (0.0 to 30%), by weight of cement, and a constant water binder ratio (w/b) of 0.5. The specimens were cured for 3, 7, 28, 56 and 90 days. At the end of each curing period, the specimens were tested for compressive strength. The results confirm the transformation of kaolinite clay into metakaolin and the pozzolanic reactivity of the produced LMK and conforms to ASTM requirements in this respect. The study confirms that LMK could be effectively used in reducing cement content up to 30% by weight without compromising compressive strength of the cement mortar.peer-reviewe