Thermogravimetric analysis of biowastes during combustion

Effect of alkali and alkaline earth metal species on the combustion characteristics of cattle manures

This study investigates the effects of alkali and alkaline earth metal (AAEM) species on the combustion characteristics of cattle manures (CM). Different AAEM species (K, Na, Ca, and Mg) were mixed with CM and deashing CM (D-CM) samples. The combustion characteristics of raw and char samples were compared. The effects of AAEM species on CM char were analyzed based on the structural characteristics of the char sample. Results show that K and Na exert a positive effect, and this effect varies depending on the addition amount. Ca and Mg also exhibit a positive effect, but this effect does not change with the addition amount. The positive effect of K, Na, and Ca is related to the decrease in graphitization degree and increase in specific surface area. However, the positive effect of Mg is negligible. In conclusion, CM can be mixed with fuels containing K or Na in an appropriate ratio. The amount of Ca to be mixed with fuels has no specific requirement, whereas that of Mg to be mixed with fuels should be controlled.

This study investigates the effects of alkali and alkaline earth metal (AAEM) species on the combustion characteristics of cattle manures (CM). Different AAEM species (K, Na, Ca, and Mg) were mixed with CM and deashing CM (D-CM) samples.

Thermogravimetric characterization of dairy manure as pyrolysis and combustion feedstocks

Thermogravimetric analysis was used to examine the thermal behavior of dairy manure as a pyrolysis and combustion feedstock. Nitrogen and air were used as purging gases to analyze the pyrolysis and combustion reactions, respectively, and heating rates of 20°C min(-1), 40°C min(-1) and 60°C min(-1) were applied. An Arrhenius model was used to estimate the kinetic parameters (activation energy, reaction order and pre-exponential factor). Results showed four steps for both the pyrolysis and the combustion reactions, with the second step being the most critical one and during which most thermal decomposition of cellulose, hemicelluloses, starch and protein occurred. Thermochemical reactions were determined mainly by temperature. Heating rate influenced the start and the end of the thermal conversions. The activation energies for the two major reaction zones were 93.63 kJ mol(-1) and 84.53 kJ mol(-1) for pyrolysis, and 83.03 kJ mol(-1) and 55.65 kJ mol(-1) for combustion. Knowledge of the thermal behavior of dairy manure provides guidelines for future energy utilization.

Co-firing of coal and manure biomass: a TG-MS approach

Manure is a rich organic waste which, apart from its traditional use as a fertilizer, could be used as a bioenergy feedstock. In this sense, its utilization as a sole fuel or its co-combustion together with coal would be a choice for the management of this sort of biowaste. However, little is known about the behavior of this biowaste when submitted to high-temperature energy-conversion processes. Thus, the separate combustion of swine manure and coal and their co-combustion (10% dried weight of manure) were studied by simultaneous TG/MS dynamic runs. TG-MS analysis was successfully used as an easy rapid tool to assess the combustion of manure, alone or together with coal. Furthermore, non-isothermal kinetic analysis showed that the Arrhenius activation energy corresponding to the combustion of the blend (125.8-138.9 kJ/mol) was only slightly higher than that of manure (106.4-114.4 kJ/mol) or coal (107.0-119.6 kJ/mol).

Digestion of cattle manure: thermogravimetric kinetic analysis for the evaluation of organic matter conversion

Anaerobic digestion of cattle manure was studied under thermophilic and mesophilic conditions with the purpose of evaluating the effect of temperature on the quality of the final digestate. Non-isothermal thermogravimetric kinetic analysis was applied for assessing organic matter conversion of biological stabilization. The mathematical approximation proves to be a useful tool for evaluating the differences attained during biological degradation. The anaerobic digestion of the organic substrate resulted in a reduction of the activation energy value obtained from the different applied kinetic models. Results obtained from thermal kinetic analysis were in accordance with those from the monitoring of the anaerobic digestion process. The higher values of methane yield reported for the mesophilic digestion in comparison to that of the thermophilic indicated a greater capability of the former process in the utilization of substrate and thus a higher conversion of organic matter which can be quantified by the activation energy value.

Thermogravimetric analysis of giant sensitive plants under air atmosphere

The aim of this work is to utilise thermal analysis to study the thermal degradation of giant sensitive plants (Mimosa pigra L.) or Mimosa under oxidative environment. Thermogravimetric method was used under air sweeping in dynamic conditions at the heating rates of 10, 30, and 50 degrees C/min, from room temperature to about 725 degrees C. Starting with dehydration step between 30 and 150 degrees C, the main thermal decomposition process under air showed two distinct degradation zones, corresponding to devolatilisation step between 200 and 375 degrees C and combustion step around 375-500 degrees C. Kinetic parameters in terms of apparent activation energy and pre-exponential factor were determined. Comparison was made against other biomass materials. Mass loss and mass loss rates were strongly affected by heating rate. It was found that an increase in heating rate resulted in a shift of thermograms to higher temperatures. As the heating rates increased, average devolatilisation and combustion rates were observed to increase while the activation energy showed slight increase.