Alternative biomass makes up a considerable portion of the waste from biomass processing in forestry and agriculture. The aim of this work was to create pellets from several sources of alternative biomass, e.g., lawn clippings, corn husks, linden leaves, and pine needles, which were compared to pure wood pellets. Analysis of the fuel properties focused on their chemical composition, thermogravimetric analysis, calorific values, and ash melting temperatures. The power and emission parameters of the fuels were determined via an automatic pellet boiler. The primary issues in the combustion of the alternative biomass types were low calorific values, increased emissions, high ash contents, and low ash melting temperatures. The two primary options for solving these problems are the production of fuel mixtures with wood or the use of new combustion technologies. This work also dealt with the combustion of alternative biomass via a rotary burner. The results showed an increase in the ash content of the alternative biomass, which also led to the burner occasionally going out due to clogging with the accumulation of ash and sintering. Based on the results, only pellets from pine needles and corn husks can be recommended for further use.
Combustion of biomass-based solid fuels is becoming increasingly popular, especially in small heat sources. A major problem in the combustion of biomass is the increased production of emissions and especially the solid component of PM particles. Currently, the most used solution to this problem is the application of electrostatic chimney separators, which innovations are discussed in our article. Two models of electrostatic precipitators were constructed in this work. The aim of this work was to compare the use of a standard single-pipe chimney electrostatic precipitator with a newer four-pipe variant. Eight measurements were performed on both devices with and without the use of an electrostatic precipitator, on the basis of which the separation efficiency was evaluated for both variants. The results of the measurements showed the initial value of the average PM production in the one-pipe variant decreased from 1012 to 416 mg.m−3 when using the separator, while in the use of the four-pipe variant it decreased from the starting value 342 to only 152 mg.m−3. These results show that the improvement of the classic single-pipe separator by increasing the number of tubes significantly reduced the production of PM emissions and increased the separation efficiency from 66 to 85%.
Bio-waste is a source of energy-rich material. Therefore, it can be used in further processes and efficiently utilized. Further processes of waste utilization include compressing them to pellets. However, this type of pellet often has a low bulk density, high ash content, low ash melting temperature, and low calorific value. This research dealt with the energy properties of peanut and pistachio nut shells that were pure or mixed with spruce sawdust in half proportion and compressed into pellets. As a continuation of previous research, the properties of these pellets prepared were measured and compared with pure spruce pellets and with pellets from walnut shells. The tested shell pellets had calorific values similar to wood pellets from spruce. However, mixing nut shells with spruce solved the problems of high ash content and low ash melting temperatures. The amount of wood present in the pellets resulted in increased ash melting temperatures and decreased the ash content.
One of the most important issues in choosing a heating system is the question: What kind of fuel can be burned in given heating system.Modern automatic solid fuel boilers are often specialized only on a narrow range of suitable pellet materials.Pellets from cheaper sources are also beginning to appear on the market.However, many burners are unable to burn these new types of pellets without significant burning problems.The article deals with the influence of the proper construction of the burner on the smoothness of the combustion process and the smooth operation of the combustion equipment.The results of the experiments document the continuity of the combustion plant in the combustion of less quality pellets containing bark using more modern combustion technologies.In fact, less quality pellets cause the formation of ash sinters which cause the continuous combustion process to be interrupted, resulting in fluctuations in equipment performance and the onset of thermal discomfort.The results showed no problem with burning even when making sinters, but also showed a fluctuation in performance and the need for manual control, especially when heating or clogging the supply pipe.They also showed significant damage to pellets in the worm feeder section.These problems, therefore, ultimately require further research to ensure complete, seamless operation.
Agricultural and other residues are promising renewable energy sources. However, they can cause problems in combustion processes. One of these problems is also low ash melting temperatures. Except, the ash melting behavior can be impacted by many factors, such as ash preparation or used atmosphere. This article deals with comparing different atmosphere conditions during measurements of ash melting temperatures of three agricultural pellets: alfalfa, straw, and hay. The first one was oxidizing with compressed air and nitrogen. The second atmosphere was reduced with the air purge, and the last was only reduced, consisting of 60% carbon monoxide and 40% carbon dioxide. Differences between individual atmospheres were none, up to 9.8%. The most significant differences have appeared between oxidizing and reducing atmospheres. In general, the oxidizing atmosphere presents a less expensive way. More attention should be paid to the use of oxidizing atmosphere for applications in heat sources mainly due to its similarity to the combustion process. However, it would be suitable to realize more comprehensive research regarding ash preparation in different ways and with using of different types of fuel.
The fundamental problem of the modern society is the waste of resources and our ever-increasing need for energy. A new trend in the EU's green policy in decreasing carbon footprint and ensuring the energy self-sufficiency of the member states is leading us to look for alternative types of fuels. Stocks of fossil fuels are dwindling and there is no point in burning them to release energy for heating or to transport materials over long distances if local resources can be used. Our goal was to follow new trends in the development of new combustion materials with regard to the transport prices of individual types of fuels focusing on the use of renewable energy sources such as alternative forms of biomass. In our research, was compared three types of fuel such as natural gas, mixed wood chips and brown coal lignite in terms of transportation and processing prices with regard to their combustion properties. The research results clearly show the paradox that alternative biomass in the form of wood chips has the lowest processing costs but the highest transport cost. However, due to the close availability of the raw material, biomass price was still the cheapest only 0,0275 €/kWh. This price calculation proves that alternative biomass can be used as an effective and ecologic replacement for fossil coal in many EU thermal power plants.
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.
At the present, the numerical techniques, such as computational fluid dynamic (CFD) is useful engineering tool for design and optimization process. The CFD gives a possibility to predict the combustion phenomena. This article deals with biomass combustion simulation by using the Eddy Dissipation Concept (EDC) model. The Eddy Dissipation Concept (EDC) model is an extension of the Eddy Dissipation model to include detailed chemical mechanisms in turbulent flows. It assumes that reaction occurs in small turbulent structures. For mathematical simulation was used 3D model, which consist of combustion chamber with retort burner and flue gas tract with baffles used for capturing of particulate matter. The model has three types of air inlet and one outlet on the end of the chimney. In the results, you can see temperature, velocity and particle profiles of this model. Based on the results can be concluded that the baffles placed in the flue gas tract can be useful for separation of particulate matter in the small heat source, such as a stove.
The correct course of the combustion process has a great influence on several output parameters. In addition to the impact on the performance and efficiency of the device, the impact on the formation and properties of gaseous emissions and solid residue is particularly noticeable. The solid combustion residue, in particular in the form of ash, remains trapped as the final product after combustion in the incinerator or may be released to the outside environment. Improperly, combustion can form two negative extremes. The first extreme is the formation of too fine dust particles of ash and solid pollutants escaping into the air as dangerous emission substances for human and other organism’s health. The second is the failure to burn larger pieces of fuel or sinter them into clumps, which can subsequently damage the combustion device or reduce the efficiency of combustion. This article aims to examine the various factors influencing the impact of combustion in different types of combustion plants on the properties of the resulting solid fuel residues and further possibilities of their use and effects on the environment.
