Effect of Paper Sludge and Dendromass on Properties of Phytomass Pellets

Energy usage of spruce with waste face masks and spent coffee grounds as fuel in a pellet boiler

It is necessary to reduce dependency on fossil fuels for heating and waste generation, while also utilizing the energy potential of waste materials. One possibility is to create fuel pellets where waste makes up a small proportion so that the properties of the wood are not significantly altered with. This article investigates the energy usage of pellets containing spent coffee grounds (5 % or 10 %) and waste face masks (5 % or 10 %), with spruce sawdust as the primary input material (80 % or 90 %). The elemental, thermogravimetric, calorific value, mechanical durability, emission and performance characteristics, and ash melting temperatures of the pellets were evaluated during the experiment. The results were compared with respect to pure spruce sawdust pellets and the specified limit values for wood pellets in commercial and residential applications as specified in ISO 17225 [18]. Both tested samples met the element content limit (N, S, Cl, As, Cd, Cr, Cu, Pb, Hg, Ni, and Zn) for the highest quality grade (A1). No significant amounts of harmful elements were detected. The samples also complied with the limits of moisture content, ash content, and net calorific value (also known as lower calorific value). All samples met the emission limits in their respective classes (3, 4, or 5) according to STN EN 303-5+A1 [35]. However, the samples failed to meet the limit values for mechanical durability and ash melting temperatures. Despite this, the manufactured pellet samples represent a suitable fuel product for combustion purposes as a more sustainable thermal energy fuel.

The energy assessment of COVID-19 medical waste as a potential fuel

The COVID-19 pandemic has caused huge health and economic damages. Various protective face masks, such as single-use, cotton, and the most widespread FFP2 or KN95 masks, are used to prevent the spread of this virus. However, these face masks are usually packaged in plastic packaging, which increases the amount of plastic waste. Plastic gloves are also often used in the connection of the pandemic. All this leads to a large production of protective equipment, but their use contributes to the increase of this type of waste, which presents a new challenge in waste management. This article investigates a complete element analysis of these mentioned materials and observes potential harmful substances. Further, pellets, as a potential fuel for combustion or pyrolysis purposes, were produced with the content of 5% and 10% of face masks. FFP2 were firstly separated from ear straps and wires, then disintegrated, added to spruce sawdust, and compressed into pellets. A series of experiments were realized and aimed at elemental, thermogravimetric, and calorific value analyses of produced pellets. Based on the results, it can be concluded that the presence of face masks FFP2 in pellets increases the content of carbon, hydrogen, and nitrogen, volatile matter, and calorific values, but decreases the content of fixed carbon. According to elemental analysis of produced pellets, no significant amounts of harmful elements were found.

Analyses of Pellets Produced from Spruce Sawdust, Spruce Bark, and Pine Cones in Different Proportions

A lot of residual biomass has energy value and can be used for further applications through suitable treatments, such as pelletization. This treatment can improve properties, mainly energy density, but can also lead to problems due to their low ash melting temperatures, high ash content, and the formation of harmful compounds during combustion. This article deals with the energy potential of pellets produced from spruce sawdust, spruce bark, and pine cones in different proportions. The impact of cone and bark contents on pellet properties was also observed. The energy properties of the produced pellets were measured, such as the contents of carbon, hydrogen, nitrogen, moisture, volatile, fixed carbon, and ash, as well as calorific values and ash melting temperatures. Based on the results, it can be concluded that the addition of pine cones and spruce bark to spruce sawdust mainly affected the contents of nitrogen and ash and melting temperatures. Despite this, all produced pellets met the standard EN ISO 17225-2 for the content of nitrogen, ash, and also lower calorific value at least B quality. However, only three pellet samples of five met this standard for A2 and B quality for ash melting behavior. Therefore, they present an alternative fuel with interesting energy potential.

Analysis of Diagnostic Methods and Energy of Production Systems Drives

This article deals with solving the urgent scientific problem of the diagnostics of drives of technological robotized workplaces with support of sensors. The dependence of diagnostic parameters on the technical state of drives of automated technological systems, which is of great economic importance for industrial enterprises, is being investigated. Diagnostic models have been developed based on sensory systems to diagnose drive models of technological robotized workplaces. The use of these models may also include monitoring systems in which it is possible to build a system for identifying detected changes. These systems identify many contradictory changes and thereby reduce the false alarm frequency of monitoring sensory systems. Numerous methods for solving technical diagnostics problems are often based on methods based on mathematical models describing work processes, as well as on spectral analysis of measured parameters, such as vibrations, noise, and electric current. A fuzzy inference system for assessing the technical condition, a system for estimating the residual resource of drives, and asystem for calculating diagnostic intervals based on fuzzy knowledge have been developed. Based on the historical trend of the diagnostic parameters, the intelligent diagnostic system determines the current technical condition of the actuator and predicts future technical condition changes, determines the remaining service life and the time intervals for diagnostics. The analysis of the time spent on planned preventive maintenance of technological equipment makes it possible to conclude that, after the modernization of equipment in 2018, the repair time was reduced from 350 h to 260 h per year (26%). Since 2019, there is a tendency to increase repair time by 30 h each year.

A Similarity Model of the Cooling Process of Fluids during Transportation

This article presents a description of a novel method for the identification of a decrease in the temperature of a liquid medium transported by railroad tank cars. No exact analytical solution exists for this phenomenon; therefore, the authors of this article have prepared a mathematical expression for the cooling process of the transported fluid by applying a dimensional analysis, which facilitated the identification of the dimensionless criteria using the relevant dimensional parameters. A functional dependence between the criteria can be identified through a physical or numerical experiment. In this case, a database of the results from a detailed numerical model was used; however, its disadvantage is that the calculation takes much longer than in a simpler similarity model. The output of the similarity model was a function of the average temperature of the fluid at a time applicable to various alternatives in the geometrical, physical, and boundary conditions. The standard deviation of the difference between the temperatures predicted by the similarity model and those calculated by the numerical simulation Tmod − Tsim represented 4.8% relative to the simulated fluid temperature.