Kinetics of coal and char oxycombustion studied by TG–FTIR

A kinetic study of the oxy-combustion of chars obtained from two Polish steam coals was conducted. A comparative study was focused on the data analysis concerning oxy-combustion of coal chars collected from two thermobalances, which differed in construction, design of crucibles, sample size and gas flow direction. The influence of individual factors such as temperature, O 2 concentration, the dimensions of the crucibles and the dimensions of the char bed on the reaction rate was analysed. On the basis of these results, a global kinetic model was elaborated showing the influence of all factors, particularly mass transfer conditions, on reaction rates. The developed model can be extended to other mass transfer conditions or fluidised bed conditions and can be applied to other fast reactions to ensure they occur in the chemical reaction kinetics control regime during TG tests. It was concluded that the gas-solid fuel contact characteristics are crucial for the measured reaction rate and for the interpretation of kinetic data.

Section: Introductionmentioning

confidence: 99%

“…It is well known that kinetic parameters should be obtained under a chemical reaction-controlling regime [5,6,13,14,[17][18][19], which is important for the study of oxy-combustion kinetics.…”

Section: Introductionmentioning

confidence: 99%

Limitation of thermogravimetry for oxy-combustion analysis of coal chars

Babiński

Ściążko

Ksepko

2017

“…Under the CCS approach, the CO 2 would be captured from power plants and, afterward, injected into geological formations to lock up the gas for decades [1]. Up to date, there are three technological pathways considered as the more efficient for CO 2 capture from coal-derived power generation: post-combustion capture with amine-based systems [2], solid sorbents based on calcium oxide [3,4], membranes and ionic liquids; precombustion technologies with integrated gasification combined cycle (IGCC) and sorbents for chemical looping [5][6][7]; and finally, the oxy-fuel combustion technology [8,9].…”

Section: Introductionmentioning

confidence: 99%

Experimental study on kinetics of coal char–CO2 reaction by means of pressurized thermogravimetric analysis

Tomaszewicz

Ściążko

2017

Comprehensive kinetic studies were performed to establish the validity of many kinetic expressions that describe the behavior of char samples during pressurized gasification toward CO 2 . The gasification experiments were carried out isothermally in a high-pressure thermogravimetric analyzer (TG-HPs, TA Instruments, USA). Two char samples derived from Turów lignite B and Janina sub-bituminous C were used for the studies. The models that were employed are regarded as the most popular: the volumetric (VM); the modified volumetric (MVM); the grain (GM); the random pore (RPM); and the Langmuir-Hinshelwood model. The models were validated at 850, 950, and 1050°C, and at CO 2 pressures of 0.4, 1, 11, and 21 bar. The effects of temperature and pressure were significant and increased the reaction rate. The calculated values of activation energy were similar for the various models employed and ranged from 169 to 212 kJ mol -1 for the Turów sample and 182 to 238 kJ mol -1 for the Janina coal char sample. The GM, RPM, and MVM fit the experimental data well, in contrast to the VM and LH models.

“…In addition, the connection of thermogravimetric analysis with the spectroscopic methods like FTIR or/and QMS permits to identify all volatile components which are released during heating. It helps to define the mechanism of decomposition of materials or their degradation kinetics [4][5][6][7][8]. The literature describes the thermal behavior and the mechanism of decomposition of many compounds like polymers [9][10][11][12][13][14][15], salts of metals [16][17][18][19][20], proteins [21,22], monomers, terpenes, esters, raw products, or others [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and thermal behavior of linear neryl diesters in inert and oxidative atmosphere

Worzakowska

Ścigalski

2013

The studies on the synthesis and thermal properties of linear neryl diesters were presented. The linear neryl diesters can be successfully obtained during butylstannoic catalyzed esterification process. The final conversion of nerol and carboxylic groups was higher than 95 % using a stoichiometric molar ratio of reagents in mild conditions. The high yield products were prepared after longer time than previously studied geranyl diesters. It was directly connected with the steric hindrance and lower susceptibility of nerol to esterification process than geraniol. The TG/FTIR/QMS studies proved that the thermal properties and decomposition mechanism of neryl diesters differ considerably in inert and oxidative atmosphere. The diesters were thermally stable up to 200°C in inert atmosphere. Their decomposition was run as a one-step process. The analyses of the volatile products emitted during their pyrolysis indicated on the ester and O-neryl bonds cleavage. It resulted in the formation of monoterpene hydrocarbons, cyclic acid anhydrides, ketones, or aldehydes. However, the studied compounds were less thermally stable in air than in helium. Their decomposition happened in two steps. The first step ranges from 185-228°C to almost 326-380°C with mass loss above 88 %. The formation of acyclic or alicylic monoterpene hydrocarbons, cyclic acid anhydrides, ketones, alkenes, alkanes, carbon dioxide, and water was expected. It indicated on the asymmetrical distrupt of the bonds, partial oxygenation, and decarboxylation of emitted gaseous fragments. The second step of decomposition was observed in temperatures ranges from 380 to above 560°C. In this step carbon dioxide and water were mainly emitted. It was the result of the oxidation of the residue formed during the fist step.