Influencia del tipo de abonado en la capacidad térmica de biomasas de cultivos tradicionales (chopo y chirimoya) y de nueva implantación (quinoa)diferencias termogravimétricas en su comportamiento térmico bajo diferentes atmósferas de calentamiento

Abstract

Given the current state of alarm and uncertainty regarding the burning of fossil fuels as the main source of energy, global policies and agreements are focused on limiting their use in order to reduce their consumption and their pollutant emissions by up to 55% by 2050, compared to 1990. In this context, biomass is a renewable and carbon neutral energy source that must continue to be researched and developed. Thus, this doctoral thesis evaluates the thermal behaviour of several lignocellulosic biomass sources. Specifically, the main objective is to study and establish comparative energy recoveries between a forest energy crop of Populus sp. and different residues from the proliferating cultivation of two species: quinoa (Chenopodium quinoa Willd.) and custard apple (Annona cherimola Mill.). Regarding poplar energy crop, a four-year-old plot composed of approximately 1400 specimens divided into four Populus sp. clones (UNAL, I-214, AF-2 and AF-8) was used. In addition, this crop was divided into three different fertilization treatments: CONTROL (without fertilization), BIOSOLIDS (organic fertilization using sludge from a wastewater treatment plant) and MUD (organic fertilization with sludge from a dairy industry). The thermochemical processes studied were combustion, pyrolysis, and gasification. Globally, it was possible to verify that each of the thermal processes revealed better thermal behaviour for a different treatment/clone. The elemental, proximal and calorific value analyses of this biomass concluded that poplar biomass has optimal properties as a fuel (HHV value close to 20 MJ/kg). In addition, the analysis of the thermogravimetric profiles showed similarities between combustion and gasification processes, showing a different pattern in pyrolysis process. The thermal indexes corroborated this trend, showing highest values for combustion, followed by gasification and pyrolysis. Concerning quinoa, the practical non-existence of studies that that provided a value to the inedible part of the plant (husk and aerial biomass) induced its energy recovery. The thermochemical processes of combustion and pyrolysis were applied, in both cases under three heating rates: 10, 20 and 40 K/min. The elemental, proximal and calorific value analyses showed better fuel properties of the aerial biomass (HHV = 15,41 MJ/kg) with respect to the husk (HHV = 12,70 MJ/kg). The thermogravimetric profiles and the thermal indexes obtained were influenced by the thermochemical process used and by the temperature variation and biomass composition. The best results were achieved through the combustion of aerial biomass under rapid heating ramps (40 K/min). These data were reconfirmed by thermal indexes and statistical analysis. Finally, the farming of custard apple. In addition to providing the desired cherimoya pulp, leaves a considerable amount of waste in the form of pruning Wood remains and seeds after the industrial processing of the fruits, both suitable for energy recovery. Two cultivation plots under different fertilization were used: M1, with traditional mineral fertilizer; and M2, with organic fertilizer from cow manure. The thermochemical process carried out was combustion, under four different heating rates: 5, 10, 20 and 40 °C/min. Regardless of the fertilizer used, the seeds presented better fuel properties (HHV = 24,78 MJ/mol) than the pruning Wood (HHV = 19,33 MJ/mol). However, the thermogravimetric profiles revealed that while seed samples were only influenced by the temperature variation, the Wood samples were also influenced by the applied fertilizer. This influence of the fertilizer used on the thermal behaviour of custard apple residues was corroborated, in turn, by the kinetic indexes, with the organic fertilizer decreasing the activation energies of all the samples, especially those of the seeds.