Effect of Fuel Additives on Agricultural Straw Pellet Quality (original) (raw)
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Waste and Biomass Valorization, 2018
The aims of the study were (a) the determination of the physicochemical characteristics of properties of pellets made of shredded residue from hay, wheat straw, and their blend at a ratio of 50:50, and (b) the determination of a mathematical model of pellet durability, using a response surface method. Tests were conducted according to applicable standards. As a result of thermal changes during the pressure agglomeration process, the material moisture content of pellets had slightly decreased versus raw three biomasses by 0.50% w.b. (wet basis) to a final value within the range of 5.56-5.87% w.b. The pellet properties of the blend were not adequately represented by the arithmetic mean of their components. Pellets made of hay, straw, and their blend, had DM (DM-dry matter) specific densities of 1034, 974, and 1102 kg m −3 , respectively. The densities showed correlation with calorific values (r = 0.637), which were in the range of 16.07-17.00 MJ kg −1. The pellet durability coefficient correlated negatively with particle size and biomass moisture content. On the basis of previous conclusions, a non-linear mathematical model was formulated to account for the pellet durability coefficient relative to pellet moisture, and the relation of particle sizes and specific density to pellet bulk density.
Impact of using additives on quality of agricultural biomass pellets
Engineering for Rural Development, 2018
The benefits of biofuels, compared to traditional fuels, target higher energy security, lower environmental impact, financial savings and socioeconomic benefits related to the rural sector. The concept of sustainable development embodies the idea of inter-connectivity and balance between economic, social and environmental concerns. Materials with lignocellulosic structure (wood, straws, stalks, etc.) represent important renewable energy resources. Their main disadvantage consists in the fact that they have very low bulk density, which leads to difficulties in the process of handling, transport, storage, respectively increased production costs. Besides this, high variations of moisture in the material can generate difficulties in the operation and adjustment of processes within the installations where they are used. These drawbacks can be improved by drying and densifying the material at very high pressures, thus obtaining solid biofuels with a uniform structure, such as pellets. Quality attributes of pellets can be influenced by using different additives and binders in the production process. Changes in the recipes used can lead to increased yields and also to improved product quality (in terms of density, inferior calorific value, durability, etc.). The paper presents a series of experimental researches conducted on pellets obtained from agricultural biomass, with and without using additives in the recipes, determining the influence of these additives on the quality of pellets used for energy purposes.
Experimental trials to make wheat straw pellets with wood residue and binders
Biomass and Bioenergy, 2014
Crude glycerol, bentonite, lignosulfonate, and softwood residue (wood residue) were investigated in this study as binders for biomass fuel pellets for thermochemical conversion to enhance pellet quality for transportation and storage. The mass fraction of water of the wheat straw and the wood residue used for pelleting were 0.0676 and 0.0949, respectively. Wheat straw with crude glycerol, bentonite, lignosulfonate, wood residue, and pretreated wood residue with crude glycerol were compressed in a single pelleting unit at a temperature of 95 C. The specific energy consumption, density, dimensional stability, tensile strength, calorific value, ash content, and chemical composition of the pellets made were determined. Results showed that the specific energy consumption for wheat straw pelletization significantly decreased with the addition of lignosulfonate, bentonite, wood residue, and pretreated wood residue with crude glycerol. With the addition of binders chosen in this study, the tensile strength of wheat straw pellets was improved with values ranging from 1.13 to 1.63 MPa. There was a significant increase in the higher heating value (17.98 MJ kg À1 to 18.77 MJ kg À1) when crude glycerol, wood residue, and pretreated wood residue were used as binders. The addition of both pretreated and non-pretreated wood residue significantly decreased the ash content of wheat straw pellets.
An Assessment of the Energetic Properties of Fuel Pellets Made by Agricultural Wastes
2020
In this study, it is aimed to produce pellets for use as solid biofuel from corn production wastes. Palletization of the biomass material increases volumetric heat value, reduces transport and storage costs, improves combustion properties, reduces emissions of particulate emissions, and produces a biofuel of the same size and shape. For this purpose, corn stalks were milled with a hammer mill and pellets were produced in an automatic feed pelletizing machine. Pellets produced from corn waste; hardness resistance, water absorption resistance, moisture content, ash content, equivalent moisture content, gas emission values released in the combustion result and calorific values which are important indicators of energy content have been determined. The upper calorific value of maize pellets with an average length of 17.28 mm and a diameter of 6.26 mm was determined to be 18.11 MJ/kg. The CO2, NO and NOx emission values of pellets from corn stalks were measured as 4.7 ppm, 38 ppm and 40 p...
Investigation of additives in combustion of wheat straw pellets in a small scale boiler
Journal of Renewable and Sustainable Energy
Crop residues could provide a local, sustainable, and low-cost solid fuel alternative to woody biomass for heat supply in the agricultural community. However, utilization of crop residues on a small scale is associated with increased pollutant emissions, as well as ash-related operational problems. There is ongoing research on fuel conditioning measures, such as fuel leaching, fuel blending, and using mineral additives, as a manner to mitigate these issues. The purpose of this study is to investigate the applicability of additives in the combustion of crop residues under everyday conditions. To this end, wheat straw pellets were combusted in a 30 kW boiler with and without additives (kaolinite and MgO, 2 wt. % and 4 wt. %). Carbon monoxide (CO) and particulate matter (PM) emissions have been monitored during combustion experiments, as well as changes in bottom ash behavior and composition. The results have shown that additives slightly decrease the heating value of the fuel (3%-6%). During experiments with additized wheat straw pellets, higher emissions of CO were observed. Combustion of pure not additized wheat straw pellets resulted in a PM emission of 568 mg/Nm 3 , which decreased with additives. Both researched additives increase the four characteristic ash deformation temperatures.
Investigation of Pellet Properties Produced from a Mix of Straw and Paper Sludge
Applied Sciences, 2020
Global energy consumption is increasing every year, and, despite their many negative impacts, fossil fuels are a major source of energy, but their reserves are gradually depleting. One of the promising but underutilized resources is plant biomass (phytomass). The main problem of plant biomass combustion is the low melting temperature of ash, but there are also problems with corrosion of heat exchangers and clogging of heat-exchanging surfaces. This work is concerned with the production of straw pellets in order to increase the melting temperature of ash by adding an additive. The paper sludge contains substances that can increase the melting point of ash and was therefore added to the pellet samples. This additive was mixed with straw in ratios from 90:10, 80:20 and 70:30 (straw/paper sludge). The use of paper sludge showed positive effects on increasing the melting temperature of the ash samples. The deformation temperature of the ash has already risen from 1020 to 1260 °C after th...
Pelletization, a form of densification, increases bulk density and improves the convenience and accessibility of biomass feedstock due to the uniform shape and size. Pretreatment of biomass enhances the breakdown and accessibility of the cross-linking lignin, which acts as a binding agent. In this study, pelletization of radio frequency-alkaline and steam explosion pretreated barley straw was performed. Three levels of temperature (70 o C, 80 o C, and 90 o C), five levels of the mass ratio of biomass to NaOH solution (1:4, 1:5, 1:6, 1:7, and 1:8), one hour equilibration time, biomass screen size of 1.6 mm, 1% NaOH concentration, and 20 min residence time in the radio frequency chamber were used for the radio frequency-alkaline pretreatment. Three levels of steam temperature (140 o C, 160 o C, and 180 o C), three levels of moisture content of 8%, 30%, and 50% (mass fraction of total mass), and 5 min and 10 min exposure to steam were tested for the steam explosion pretreatment.
Journal of Agricultural Engineering, 2010
The increased consumption of solid biomass for energy production has raised a number of technical problems that are mainly related to the variability of the chemical-physical characteristics of feedstocks. The low melting temperature of their inorganic fraction is the main cause of these problems. In this work analysis and comparison of the thermal behaviour of ash from 20 different feedstocks highlighted that biomass materials with the same origin share similar qualitative and quantitative characteristics. A feedstock from a starch group, corn grain, was tested for the effects of four mineral additives (MgO, CaO, Ca- CO3, and SiO2) on ash deformation temperature. MgO and CaO seemed to be the most effective, raising ash melting temperature and enhancing the thermal behaviour of the feedstock. The results of supplementation of the initial corn grain, wheat straw and sunflower cake biomass demonstrated that the amount of additive to be used is a function of biomass type and can depend...
Research experience from the use of different additives in wood-fuel pellet production
International Journal of Energy Production and Management
The use of wood-fuel pellets has increased significantly worldwide in recent years, especially in the United Kingdom. If wood-fuel pellets should continue to be a successful biofuel at the energy market, the pellet production industry has to reduce the production cost, since it is a low-margin business. Further, improved pellets regarding storability and strength of the pellets are crucial to manage the overseas transportation that causes material losses. In addition, the industry tries to produce pellets from a broader raw material base and at the same time satisfy the customer requirements while producing a sustainable product. The wood-fuel pellet industry has the possibility to meet all these criteria; however, it also has the potential for improvements. Using additives in pellet production is one way to meet the criteria. In conclusion, it is necessary to do the research that systematically investigates the consequences of using additives for wood-fuel pellets, and this work presents a compilation of results and experiences from more than 20 different additive studies and the test bed for pellet production research at Karlstad University-a pellet production unit adapted for additives studies. Additives, with an admixture of up to 2% (wt.), have been tested in the NewDeP (New Development for Pellet Technology) pilot plant for pellet production at Karlstad University. The research has focused on the electricity consumption, the physical and mechanical properties of the pellets, and the CO 2 equivalents emitted during production. The results showed that the additives Wetland grass, Algae, Turpentine and Lignin decreased the electricity consumption in the pellet press but unfortunately also decreased the durability. The additives Resins, Molasses, White sugar, Native potato starch and Oxidized potato starch increased the durability of the pellet but showed almost no change in the electricity consumption. However, Oxidized corn starch, Spent sulphite liquor and Native wheat starch as additives increased the mechanical properties while it decreases both the electricity consumption and the climate impact, hence a Win-Win-Win situation.
Factors affecting pellet quality and energy analysis of pelleting process
Agricultural biomass residue such as barley, canola, oat and wheat straw has the potential to be used for sustainable production of bio-fuels and offset greenhouse gas emissions. The biomass substrate must be processed and handled in an efficient manner in order to reduce industry's operational cost as well as meet the requirement of raw material for biofuel production. Biomass has low bulk density, making it difficult and costly to store and transport in its native loose form.