Kinetic models comparison for non-isothermal steam gasification of coal–biomass blend chars

Abstract

The non-isothermal thermogravimetric method (TGA) was applied to a bituminous coal (PT), two types of biomass, chestnut residues (CH) and olive stones (OS), and coalbiomass blends in order to investigate their thermal reactivity under steam. Fuel chars were obtained by pyrolysis in a fixed-bed reactor at a final temperature of 1373 K for 30 min. The gasification tests were carried out by thermogravimetric analysis from room temperature to 1373 K at heating rates of 5, 10 and 15 K min -1 . After blending, no significant interactions were detected between PT and CH during co-gasification, whereas deviations from the additive behaviour were observed in the PT-OS blend.However, for the two coal-biomass blends, the gasification behaviour resembled that of the individual coal, as this component constituted the larger proportion of the blend. The temperature-programmed reaction (TPR) technique was employed at three different heating rates to analyze noncatalytic gas-solid reactions. Three nth-order representative gas-solid models, the volumetric model (VM), the grain model (GM) and the random pore model (RPM) were applied in order to describe the reactive behaviour of the chars during steam gasification. From these models, the kinetic parameters were determined.The best model for describing the reactivity of the PT, PT-CH and PT-OS samples was the RPM model. VM was the model that best fitted the CH sample, whereas none of the models was suitable for the OS sample.

Catalytic characteristics of the pyrolysis of lignite over oil shale chars

“…Evolved gases from TGA passed through a heated transferred line, which heated to 215°C in order to prevent the condensation of gases, into a beam conforming flow cell for the FTIR to collect the spectra characteristics in the range of 4000-1000 cm À1 IR absorption band to 6 cm À1 resolution [14]. Duplicate experiments for each test were performed in order to test the reproducibility of the results.…”

“…For this purpose, the combined TG-FTIR technique was employed to dynamically record the species ejected from the thermal degradation of lignite over oil shale char and thereby derive the catalytic effect of oil shale char. Two model-free methods were used to determine the kinetic parameters which represent the pyrolysis of ignite [14]. Furthermore the oxygen functional groups, minerals composition, inorganic oxides and selected trace metals (Co, Cu, Cr and Zn) may affect the catalytic activity and are also studied here [13].…”

A comprehensive study on co-pyrolysis of bituminous coal and pine sawdust using TG

“…Therefore, it might be preferable to utilize biomass in conjunction with coal for combustion and gasification [3]. Co-gasified coal and biomass can be considered a potential fuel base for gasification and offer the advantage of a reduction in CO 2 emissions, and even a net reduction if CO 2 capture is incorporated as part of the process [4,5]. In addition, use of biomass could contribute to the reduction of fossil fuel dependency [6].…”

Emprego de análise térmica e forno tubular de queda livre (DTF) para estudar a eficiência térmica de carvões minerais, bagaço de cana-de-açúcar e suas misturas

“…É interessante Na literatura alguns autores observaram interações entre carvão e biomassa durante processos térmicos realizados em diferentes tipos de reatores (Vhathvarothai et al, 2013;Yuzbasi e Selçuk, 2011;Nimmo et al, 2010;Fermoso et al, 2010;Edreis et al, 2013;Kazanç et al, 2011;Idris et al, 2010). Eles afirmaram que os efeitos de sinergismo podem ocorrer devido à elevada quantidade de material volátil presente na biomassa dado pela alta reatividade.…”

“…A alta reatividade de algumas biomassas, devido ao seu alto conteúdo de material volátil e maior razão molar de hidrogênio/carbono (H/C) do que o carvão sugere que os efeitos sinérgicos possivelmente ocorrem quando misturado com carvão (Fermoso et al, 2010, Edreis et al, 2013 . No entanto, estes efeitos podem depender dos parâmetros operacionais utilizados (Krerkkaiwan et al, 2013 …”