Thermal Study and Emission Characteristics of Rice Husk Using TG-MS.

Rice husks are a by-product that is generated in large quantities in Spain. However, they are not used efficiently. One of their possible applications is its thermal use in power generation equipment. For that purpose, it is important to know the characteristics of rice husks and their thermal behavior, as well as their possible pollutant emission to the atmosphere with respect to its thermal use as a biofuel. In this work, the thermal characteristics of rice husks and their thermal behavior were studied by using thermogravimetry and mass spectroscopy for two different atmospheres (oxidizing and inert). This way, the thermal profiles and the main characteristics were studied, as well as the emission of possible pollutants to the atmosphere, such as CO2, CH4, NO2, NH3, SO2, and H2S. Moreover, three different methods (FWO, KAS, and Starink) were used to carry out a thermal analysis, in order to obtain the main thermal parameters such as activation energy. The results of the analysis predicted that rice husks could be used as biofuel in industrial thermal equipment based on its acceptable calorific value, good thermal characteristics, and low gas emissions both in oxidizing and inert atmosphere (although they have a high ash content).

A Review of Pellets from Different Sources.

The rise in pellet consumption has resulted in a wider variety of materials for pellet manufacture. Thus, pellet industry has started looking for alternative products, such as wastes from agricultural activities, forestry and related industries, along with the combination thereof, obtaining a broad range of these products. In addition, the entry into force of EN ISO 17225 standard makes wood pellet market (among other types) possible for industry and household purposes. Therefore, wastes that are suitable for biomass use have recently increased. In this study, the main characteristics of ten kinds of laboratory-made pellets from different raw materials were analyzed. Thus, we have focused on the most limiting factors of quality standards that determine the suitability for biomass market, depending on the kind of pellet. The results showed considerable differences among the analyzed pellets, exceeding the limits established by the standard in almost all cases, especially concerning ash content and N and S composition. The requirements of the studied standard, very demanding for certain factors, disable the entry of these densified wastes in greater added value markets.

Control of several emissions during olive pomace thermal degradation.

Biomass plays an important role as an energy source, being an interesting alternative to fossil fuels due to its environment-friendly and sustainable characteristics. However, due to the exposure of customers to emissions during biomass heating, evolved pollutants should be taken into account and controlled. Changing raw materials or mixing them with another less pollutant biomass could be a suitable step to reduce pollution. This work studied the thermal behaviour of olive pomace, pyrenean oak and their blends under combustion using thermogravimetric analysis. It was possible to monitor the emissions released during the process by coupling mass spectrometry analysis. The experiments were carried out under non-isothermal conditions at the temperature range 25-750 °C and a heating rate of 20 °C·min⁻¹. The following species were analysed: aromatic compounds (benzene and toluene), sulphur emissions (sulphur dioxide), 1,4-dioxin, hydrochloric acid, carbon dioxide and nitrogen oxides. The results indicated that pollutants were mainly evolved in two different stages, which are related to the thermal degradation steps. Thus, depending on the pollutant and raw material composition, different emission profiles were observed. Furthermore, intensity of the emission profiles was related, in some cases, to the composition of the precursor.

Analysis of Pelletizing of Granulometric Separation Powder from Cork Industries.

Cork industries generate a considerable amount of solid waste during their processing. Its management implies a problem for companies that should reconsider its reuse for other purposes. In this work, an analysis of pelletizing of granulometric separation powder, which is one of the major wastes in cork industries and which presents suitable properties (as an raw material) for its thermal use, is studied. However, its characteristic heterogeneity, along with its low bulk density (which makes its storage and transportation difficult) are restrictive factors for its energy use. Therefore, its densified form is a real alternative in order to make the product uniform and guarantee its proper use in boiler systems. Thus, the cork pellets (from granulometric separation powder) in the study met, except for ash content specification, the specifications in standard European Norm EN-Plus (B) for its application as fuel for domestic use.

Thin layer drying kinetics of by-products from olive oil processing.

The thin-layer behavior of by-products from olive oil production was determined in a solar dryer in passive and active operation modes for a temperature range of 20-50 °C. The increase in the air temperature reduced the drying time of olive pomace, sludge and olive mill wastewater. Moisture ratio was analyzed to obtain effective diffusivity values, varying in the oil mill by-products from 9.136 × 10(-11) to 1.406 × 10(-9) m(2)/s in forced convection (m(a) = 0.22 kg/s), and from 9.296 × 10(-11) to 6.277 × 10(-10) m(2)/s in natural convection (m(a) = 0.042 kg/s). Diffusivity values at each temperature were obtained using the Fick's diffusion model and, regardless of the convection, they increased with the air temperature. The temperature dependence on the effective diffusivity was determined by an Arrhenius type relationship. The activation energies were found to be 38.64 kJ/mol, 30.44 kJ/mol and 47.64 kJ/mol for the olive pomace, the sludge and the olive mill wastewater in active mode, respectively, and 91.35 kJ/mol, 14.04 kJ/mol and 77.15 kJ/mol in natural mode, in that order.

Combustion analysis of different olive residues.

The Thermogravimetric Analysis (TGA) techniques and concretely the study of the burning profile provide information that can be used to estimate the behaviour of the combustion of carbonous materials. Commonly, these techniques have been used for the study of carbons, but are also interesting for the analysis of biomass wastes, due to the different species present on the wastes affect directly to its thermal properties. In this work, techniques of thermal analysis have been applied to compare the behaviour of different wastes coming from olive oil mills. From these results, it is remarkable that the Concentrated Olive Mill Waste Water (COMWW) presents more unfavourable conditions for its combustion.