Low-quality Fuels Research Articles

Aluminosilicate Clay Minerals: Kaolin, Bentonite, and Halloysite as Fuel Additives for Thermal Conversion of Biomass and Waste

The current focus on renewable energy sources and the circular economy favors the thermal conversion of low-quality fuels, such as biomass and waste. However, the main limitation of their usability in the power sector is the risk of slagging, fouling, ash deposition, and high-temperature corrosion. These problems may be avoided or significantly mitigated by the application of aluminosilicate clay minerals as fuel additives. In this paper, the three most commonly occurring aluminosilicates are reviewed: kaolin, halloysite, and bentonite. Their application has been proven to minimize combustion-related problems by bonding alkalis in high-melting compounds, thus increasing ash melting temperatures, reducing ash deposition tendencies, and decreasing the particulate matter emission. Due to excellent sorption properties, aluminosilicates are also expected to fix heavy metals in ash and therefore decrease their emissions into the atmosphere. The application of aluminosilicates as fuel additives may be a key factor that increases the attractiveness of biomass and other low-quality fuels for the power sector.

Systematic homogenization of heterogenous biomass batches – Industrial-scale production of solid biofuels in two case studies

Biomass is a heterogeneous material with respect to its chemical composition due to different plant species and components as well as the potential content of impurities. Especially in the production of large fuel batches heterogeneous chemical compositions are a challenge with respect to the required compliance with fuel standards and emission thresholds during utilization. This can be avoided by fuel pre-treatment and systematic homogenization during fuel production. For this reason, the study analyses the effects of biomass leaching in combination with homogenization of biomass batches on industrial-scale. Within two case studies, low-quality herbaceous biomasses, i.e. foliage and wheat straw were pretreated and homogenized in quantities ranging from 8 to 51 tons. In the first case study, foliage was first leached, then mixed with sawdust and homogenized by separating batch parts with high ash content, followed by systematic recombination of the batches. In the second case study, homogenization of straw pellets (untreated and leached) was attempted by a layering approach during bagging. Both case studies (i) confirm earlier findings that critical fuel components can be substantially reduced by leaching (i.e. reduction of ash content MV by 45 w-%) but indicate that material agitation during leaching is necessary; (ii) underscore that systematic homogenization is necessary for fuel batches consisting of materials from different origins and reduce i.e.-the ash content RSD by 48%, and (iii) demonstrate that even low-quality fuels from herbaceous biomass assortments can comply with the requirements of fuel standards if dedicated fuel pretreatment is employed.

Juridical Review on the Mandatory Biodiesel Program for Maintaining National Energy Security in Indonesia

Indonesia commits to reducing emissions by 29% (unconditional) or 41% (conditional) in 2030, which can be achieved by encouraging the use of new and renewable energy (NRE) by 23% in 2025 while realizing national energy security. A biofuel development plan through a mandatory biodiesel program and green fuel utilization is the main priority to reduce fossil fuel consumption and achieve the energy mix target. As of January 1, 2020, through the mandatory biodiesel program, biodiesel utilization reached 30% (B30) for all diesel engine sectors, which is the highest biodiesel blending program in the world. However, the gap between government policies with emission regulation and existing vehicle technologies in this country might provide challenges in strengthening the sustainability of mandatory biodiesel programs. This study used a normative juridical method to assess the policy and enhance the regulation of the mandatory biodiesel program by obtaining library materials, theories, concepts, principles, and existing rules related to the law perspective. An appropriate and consistent energy mix policy, including its long-term strategy to increase biofuel utilization and maintain a mandatory biodiesel program, is needed to achieve a reducing emissions target. It is essential to strengthen and clarify the policy and road map. The vehicle technology and fuel quality were also crucial for enhancing emission regulation and eliminating low-quality fuels, maintaining a sustained biodiesel program, and achieving national energy security.

Waste Slag Management with help of Air Blaster in CFBC Boiler

Abstract: This research paper addresses the issue of excess ash content in CFBC boilers when lower quality fuel, such as the lower or upper layer of lignite, is supplied. The increase in ash content leads to the continuous draining of bed ash and often results in the restriction of bed material flow in the furnace inlet pipe to the slag cooler. While this may not have a significant impact on the required load in normal conditions, it can severely affect the unit's load capacity in the case of poor-quality coal. The paper proposes a solution for waste slag management using air blasters in 135 MW CFBC boiler, which can effectively prevent the choking of inlet pipes and ensure uninterrupted operation at the required load capacity. The implementation of this solution has the potential to significantly improve the operational efficiency and reliability of CFBC boilers, particularly when using lower quality fuels.

Novel Design for Rotary Burner for Low-Quality Pellets

The burning of low-quality fuels causes several problems in the operation of combustion equipment, which can negatively affect the equipment’s efficiency. The possibilities for the burning of pellets made from low-quality raw materials are limited mainly by the fusibility of the ash, which settles and melts on the surfaces of the burner, gradually causing it to clog. Smelted ash also causes a decrease in heat transfer efficiency, which negatively affects the overall efficiency of the heat source. A possible solution is provided by burners with a rotating combustion chamber, where the contact time of the molten ash with the walls of the burner is shortened, and thus there is no significant melting of the ash in the burner. This manuscript is dedicated to summarizing the current state of development of burners with a rotary chamber, presenting a novel design for such a burner, and providing an analysis of that design. To conclude, the results of experimental measurements on a classic burner and a burner with a rotary chamber are presented, including a comparison and evaluation mainly in terms of emissions. The novel-designed rotary burner achieved a higher heat output than the retort burner, but a similar thermal efficiency. The rotary burner produced 32.5% lower CO emissions, 12.5% higher NOx emissions, 23% lower OGC emissions, and 44.7% higher PM emissions in comparison with a retort burner under the same conditions. This novel rotary burner concept could, after optimization, be a suitable option for efficient combustion of alternative biofuels.

Study on the Cumulative Effects of Using a High-Efficiency Turbocharger and Biodiesel B20 Fuelling on Performance and Emissions of a Large Marine Diesel Engine

The marine sector represents probably the most powerful segment of international transport. Most ships use diesel engines for propulsion. Pollutant emission regulations with their continuous decline of acceptable limits put huge pressure on engine manufacturers. The use of low-quality fuels makes the marine sector a significant contributor to global pollution. The present study shows how turbocharger operating parameters and replacing diesel fuel with biodiesel B20 (20% oil and 80% diesel volumetric fractions) affect the performance, efficiency and pollutant emissions of a four-stroke diesel engine ALCO V16 251F for marine application. A combustion model developed with the AVL BOOST software was used to perform calculations using diesel fuel and biodiesel B20 for different turbocharger characteristics and injection timings. The model was calibrated against experimental data measured on a tested engine at the application site using diesel fuel and operating in a stationary condition of full load at 600, 700 and 800 rpm engine speeds. The results show that the cumulative effects of using an improved turbocharger associated with B20 fuelling under optimized injection timings could provide reductions of 45% for soot and 5% for NOx, while maintaining the same engine performance obtained with diesel fuel operation.

Investigation of oxidation and hot corrosion behavior of molybdenum coatings produced by high-velocity oxy-fuel coating method

Thermal spray coatings methods are frequently used in automotive, aerospace, and marine vehicles. The most obvious damage mechanisms of coating systems, which are exposed to many damages during use, are high-temperature oxidation and corrosion. While the oxygen element coming from the atmosphere creates the high-temperature oxidation damage in the coating systems, the molten salts such as Na2SO4 and V2O5 coming from low-quality fuels constitute the high-temperature hot corrosion damage mechanism. In this study, its behavior against high-temperature oxidation and hot corrosion damage mechanisms was investigated by coating Molybdenum (Mo) on a 316 L stainless steel substrate with the High-Velocity Oxy-Fuel technique, which is an innovative thermal spray coating method. Both damage mechanisms were carried out isothermally at 650 °C. Oxidation tests were carried out for 5, 25, and 50 h, while hot corrosion tests were carried out for 1, 3, and 5 h. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), Elemental mapping, and Energy Distribution Spectroscopy (EDS) analysis was performed on molybdenum-coated samples before and after both tests. The results obtained were evaluated and discussed in light of the literature.

Biomass woodchip tracking by image analysis in a model of a fixed bed combustor

Energy sector sustainability is one of the main concerns in the recent years. Biomass, in form of woodchips, is interesting for direct combustion in external combustion cycles (e.g. supercritical CO2 Brayton cycles) due to the opportunity of using low quality and low environmental impact fuels. In this study, a direct combustion system working with biomass woodchips is investigated by means of an image analysis technique. The system is made up by a screw conveyor and a fixed bed, where the woodchips are processed. The analysed device operates in cold-condition, and woodchips are partially coloured according to their dimensional class to be traced once these reached the bed surface. A proper algorithm was developed to identify the particles size, define and detect macroparticles centres, and evaluate the main particles motion pattern by comparing the centre positions during time. The results were particularly useful to understand potential inefficiencies of the combustion system due to an uneven woodchips distribution. In addition, the results achieved with the proposed test rig and the adopted methodology can also be used to validate results from Discrete Element Modelling (DEM) simulations.

Aerodynamic Characteristics of the Combustion Process of Sawdust in a Vortex Furnace with Counter-Swirling Flows

The aim of this work is to study the working processes of burning the low-quality fuels, namely, the saw dust in the swirling-type furnaces with an opposite twisted motion of the air. The goal was achieved using the physical and mathematical modeling of the flows interaction. The article presented the results of numerical study of aerodynamic characteristics of burning the saw dust in the swirling-type furnace with the opposite twisted air flows. For the research, the facility was used for the saw dust burning with the air supply into the lower and upper zones of burning. The most essential result of the work was modeling of the working process at the ratio of the flows of the primary air and secondary air without the fuel admixture, equal to 0.2. The tangential rate of the flow changed according to the horizontal sections from 3-5 m/s to 40-42 m/s and with respect to the furnace height from 51 m/s to 30 m/s. The average angular rate of the mixture changed relatively the furnace height in the ranges of 171-500 l/s to 100—300 l/s. The significance of the results obtained consists in determination of the possibility of increasing the efficiency of the work of the furnace facilities at the expense of the introduction of the primary and secondary air flows. In this situation, the optimal ratio of consumptions of primary and secondary air was 0.2. Thus, in this work the consumption of primary air was 1.285 kg/s, the consumption of the secondary air was 0.255 kg/s.

Spatio-Temporal Modelling of the Change of Residential-Induced PM10 Pollution through Substitution of Coal with Natural Gas in Domestic Heating

Air pollution has been one of the most critical urban problems. Urban energy networks are among the major sources of air pollution, particularly in highly populated urban areas. Residential heating, which is the primary cause of particulate matter (PM) emissions, contributes to the problem through the use of low-quality fuels, such as coal. Natural gas, although a fossil fuel, is a modern, relatively clean, and more efficient alternative in residential energy use, which helps to reduce particulate matter emissions. Coal was widely used in residential heating in İzmir, Turkey, whereas natural gas is a relatively new alternative which started to be used domestically in 2006. Switching from coal and other highly polluting fossil fuels to natural gas in urban energy distribution network has contributed to the alleviation of air pollution in the city in the past decade. Spatiotemporal analyses of the PM10 concentrations, and their relation to the natural gas investments, have been conducted in geographical information systems (GIS). The spatial distribution of the change in PM10 levels has been modeled with ordinary kriging for the 2010–2011 and 2018–2019 winter seasons. Interpolated PM10 surfaces show that there is a significant decrease in the emissions throughout the city in the overall, while the highest levels of decrease are observed in the southern part of the city. Overlaying the interpolated PM10 surfaces and the natural gas pipeline investments enables the demonstration of the mutual relationship between the change in emission levels and the energy distribution network. Indeed, the spatial distribution of the pollution concentrations appears to be parallel to the natural gas investments. The pipeline investments were intensive during the 2010–2018 period in the southern districts when compared the rest of the city. The use of natural gas in residential heating contributed to the decrease in PM10 emissions.

The South African informal sector’s socio-economic exclusion from basic service provisions: A critique of Buffalo City Metropolitan Municipality’s approach to the informal sector

This study explores the exclusion of informal micro-enterprises from the provision of basic urban infrastructure services in Duncan Village in East London, South Africa. It focuses on the informal food sector, which is dominated by women who are often held back from participating in economic activities that are more productive, as well as from social and political functions. Basic urban infrastructures, such as trading shelters with water and electricity connections provided by municipalities, are often expensive and most informal street traders find it difficult to access them. This study examines the energy struggles of the informal street food sector and its engagement with local government on issues of inclusivity on policies regulating the sector. In-depth, semi-structured interviews and focus groups were conducted with 40 participants in the informal street food sector in Duncan Village. The findings reveal the lack of energy transition in the informal street food sector, because of its heavy reliance on low-quality fuels. Unreliable and expensive energy services force informal street food enterprises into using a limited range of energy sources. The findings also reveal that the relationship between the municipality and the informal street traders is one of exclusion and negligence. It is therefore suggested that government needs to recognise and value the informal sector and livelihoods of those involved in this sector, to take into account their needs, and engage with them when designing and implementing policies that regulate the sector.

Analysis of technological potential for utilization of waste aviation lubricating materials

The object of research is technologies for waste aviation oils and lubricants recycling and utilization. The work is devoted to the analysis of the current state and the assessment of the technological potential in the field of processing and disposal of aviation lubricants. The current state and dynamics of the market for the production and consumption of aviation lubricants are considered. The main properties and functions of aviation oils and lubricants are analyzed, the main technical requirements for them are formulated. A complex of physical and chemical processes that occur in lubricants during their operation and long-term storage, and lead to a loss of their quality, is considered. It is shown that the main factors of quality deterioration are high-temperature destruction, oxidation, polymerization and condensation of hydrocarbons, mixing with fuel, and pollution with inorganic compounds. The main ecological as well as economic problems associated with the aссamulation of waste lubricants are considered, their negative impact on the components of the environment and human health is described. So, the main negative effects are associated with their improper storage, discharge into water bodies or soils, as well as with their burning and the formation of toxic emissions. On the basis of this, the need for the development and implementation of integrated technologies for the disposal of waste lubricating materials is shown. The main directions, methods and technologies that are used for their utilization are presented. So, depending on the composition, quality and properties of waste lubricants, technologies for restoring their quality, processing technologies using them as raw materials for the production of similar petroleum products, technologies for obtaining low-quality fuels for stationary equipment based on them can be used. It is shown that the development and application of effective technologies for the disposal of used lubricants has a number of positive effects: minimization of the negative impact on the environment, savings and expansion of oil resources for the production of commercial petroleum products, and, as a result, saving money.

The application of hierarchical clustering to analyzing ashes from the combustion of wood pellets mixed with waste materials.

Air pollution constitutes the greatest environmental threat to human health in the European Union. In Poland, the emission of particulate matter and harmful gases originating from local coal based boiler plants and the combustion of fuels in residential heating appliances is a considerable source of air pollution. The combustion of fuel in home furnaces is inefficient due to the use of cheap fuels of low heating parameters and the frequent addition of waste. For the purpose of the research, deciduous tree wood pellets were selected as the basic fuel with the admixture of plastic waste, rubber, waste paper, wood residues, diapers, textile waste, multi-material packaging, construction waste, biomass and alternative fuel (RDF). Examining ash samples to confirm the practices of combusting or co-combusting waste materials in heating appliances is considered to be one of the most reliable detection methods; however, the results of direct research require further data processing. The application of hierarchical clustering analysis to the obtained results arranged into a matrix enabled in a simple way to demonstrate the similarities between the examined samples of fuel and the samples of fuel mixed with waste materials in the parameters space as well as to analyze the similarities among the measured parameters (the content of particular elements in ash) in the space of the examined samples. The application of chemometric methods for the purpose of identifying the combusted fuels, and, in particular the co-combusted waste complements the currently used monitoring tools which control the use of low quality fuels or the combustion of waste of different origin.

Application of volumetric expanders in small vapour power plants used in distributed energy generation – Selected design and thermodynamic issues

Air pollution with dust is particularly noticeable in winter. This problem is visible especially in those living areas in which furnaces fed by low-quality fuels are used for heating houses and flats. One of the possible ways of limiting the number of used furnaces may be heating and powering of the housing estates and villages by specially designed combined heat and power (CHP) steam (or vapor) power plants. To be competitive to other heating technologies these systems should be cheap, reliable and easy to operate. Therefore, their design should be as simple as possible. Steam or organic Rankine cycle (ORC) energy conversion systems utilizing simple volumetric expanders, which can be applied for distributed power generation are meeting these conditions. The article presents literature review as well as selected thermodynamic and design issues concerning these systems. Literature review gave an outlook on the modeling, experiments, operating conditions and possible configurations of steam and ORC CHP systems. Then, model of the CHP system was implemented in computer software. Thanks to the positive technical features and ability to operate with wet gas the screw machine was selected as the system’s expander. Selected experimental data obtained from the literature review were used for system modeling. Especially the operating conditions of the selected expander (i.e., maximum mechanical power, maximum inlet pressure, expansion ratio and internal efficiency) were assumed based on the experimental results, technical data and information reported in different papers. Expander’s operating conditions and technical data (in particular the value of maximum working fluid pressure allowable at the inlet to the expander) were the basis for pre-selection of working fluids which are possible to apply in the modelled system and selection of the heat source thermal parameters. Modeling was proceeded for different conditions and the results show that depending on the operating conditions and applied working fluid electric power output of the CHP system ranges between 1570 and 2511 kWe (for heat source temperature of 200 °C) and between 1583 and 2631 kWe (for heat source temperature of 150 °C). However, not only maximum power output should be considered as the selection criteria of the system design and working fluid choice. The other important criteria are related to maximization of the obtained electric power, minimization of the vapor pressure at the outlet of the vapor generator and at the inlet to the expander, minimization of the working fluid flow, minimization of fuel consumption and maximization of the temperature of the working fluid at the outlet of the expander. The modeling results show that from all cases studied the ORC CHP power plant utilizing screw expander, using MD2M as working fluid and featuring the electric power of 1570 kWe fed by rapeseed oil is the best possible solution if technical assessment criteria are taken into consideration. Such a system can cover the heating demands of ca. 9615 flats.

Revisiting Energy Consumption-economic Growth Hypothesis: Do Slope Heterogeneity and Cross-sectional Dependence Matter?

In this paper, the long-term nexus between energy consumption and economic growth is investigated using a panel data of 80 countries from World Bank data base for the period 1970 to 2017. In order to check for the issues of endogeneity, slope heterogeneity, and cross-sectional dependence present in errors of panel data, the study applied cross-sectional augmented autoregressive distributed lag (CS-ARDL) and cross-sectional augmented distributed lag (CS-DL) models to examine the long-term impact of energy consumption on economic growth. The empirical results revealed that energy consumption has a positive and significant long-run effect on economic growth and that cross-sectional dependence, slope endogeneity and heterogeneity are issues that should be on the watch when dealing with panel data of developing and developed countries’ analysis. Furthermore, the outcomes indicated that the impact of energy consumption on economic growth is stronger in less developed countries than in advanced economies. Technological progressions that give rise to the advancement of clean and efficient energy and substitution of low-quality fuels with high quality fuels are some of the possible channels that weaken the link between energy consumption and economic growth in advanced economies. Importantly, from a policy perspective, based on the study findings, energy conservation policies aimed at promoting environmental quality may worsen economic growth in developing countries, thereby adversely affecting their long-run economic growths.

Effect of protogenetic alkali sulfates on the hydration and hardening of cement with different tricalcium aluminate content

The reaction of protogenetic alkali sulfates including arcanite (K2SO4), thenardite (Na2SO4) and aphthitalite (K3NS4) with calcium aluminate have a great influence on cement hydration and hardening. Considering the increased protogenetic alkali sulfates with the widespread use of rotary kilns and low-quality fuels during cement production, the effect of alkali sulfates under different dosages of C3A on hydration heat evolution, initial setting time, compressive strength, volume stability and hydration product were studied. The results show that protogenetic alkali sulfates combined with C3A have unfavorable effects on setting time, compressive strength, and linear expansion ratios by dry and water curing. The effect is negatively correlated with [Na2Oeq]·[C3A]/[SO3]2 molar ratio of cement. The [Na2Oeq]·[C3A]/[SO3]2 molar ratio <0.5 contributes to a lower reduction of strength and volume stability. Through the evaluation of 28-day compressive strength by forty types of cements, it is proposed the [Na2Oeq][C3A]/[SO3]2 molar ratio can evaluate the function of protogenetic alkali sulfates combined with C3A in cement and provide guidance of the improvement on cement properties.

Assessing outdoor air quality and public health impact attributable to residential black carbon emissions in rural China

Black carbon (BC) is a significant component of particulate matter (PM) that relates to air pollution, climate forcing, and further implications for public health. BC is predominantly released from the combustion of solid fuels. Combustion of low-quality fuels in rural China may induce severe respiratory and cardiopulmonary health outcomes for residents, which have however been inadequately assessed. One major reason for the limited understanding is the lack of a high-resolution inventory. An improved method of estimating the BC-associated public health burden is needed. This work quantified premature mortalities due to residential BC emissions in rural China. Domestic BC emissions at 1×1 km resolution were compiled based on previous field investigation, which were further configured for air quality simulation. A chemistry transport model, WRF–CMAQ v5.2, was employed for simulating BC concentrations. The consequent premature mortalities were quantified by a BC-specific concentration-response function (CRF) derived from an epidemiological study. Results show that residential combustion of solid fuel in rural China emitted 648.0 Gg (95%CI: 361.0–965.9) BC in 2014, after dispersion, accounting for 51.8% of annual mean ground-level BC concentration in China. Such impact was most severe in North and Northeast China, and the Sichuan Basin. The further investigation estimated 171,000 (95%CI: 69,000–387,000) premature mortalities that were attributable to exposure to rural residential BC. These findings reveal the major contribution of rural residential BC emissions to air pollution formation and public health impacts. Our findings are anticipated to provide useful information for enacting the next-stage environmental strategy for the residential sector in China.

Bharat Stage IV to VI -Challenges and Strategies

Bharat stage VI emission norms are the sixth stage for vehicular emissions in India. The BS-VI emission norms are much needed for a country such as India to keep the pollution in check. BS-VI norms are stricter and more restrictive in terms of BS-IV norms allowing for cleaner air and also less pollution in the process. The new BSVI emission norms would require both the automobile sectors as well as oil companies to make advancements and changes to their respective products. For the best results and for the better performance of the car the BSVI based engines will have to run on BSVI fuel. The new generation modern engines which are running on low-quality fuels will emit more toxic gases compared to that generated by the BSIV engines. The modern age engine blueprints usually require low Sulphur content to maintain a strong performance. This research aims at comprehending information on a new perspective of understanding the concept and how helpful it will be in understanding the shift from BHARAT STAGE IV TO VI for various stakeholders. Followed by strategies adopted by top five Indian based car manufactures.

An Externally Fired Micro Combined-Cycle, with Largely Adjustable Steam Turbine, in a CHP System

This work stems from the idea of demonstrating the feasibility of using micro combined plants for the simultaneous generation of electrical and thermal energy, by external combustion of low quality fuels. In particular, this study is aimed at acquiring the knowledge necessary for the development of a small power plant consisting of a micro gas turbine and an innovative steam micro-turbine. The topping cycle is carried out with a micro gas turbine coupled with a heat exchanger and an external combustor, in which biomass is burned. For the bottoming cycle an impulse turbine has been adopted, characterized by a variable section nozzle, capable of expanding widely variable steam flow rates, with small efficiency losses. For the purpose of an immediate display of proportions, dimensions and assembly possibilities, 3D printing of a turbine scale model was also made.

Quality assessment of gas produced from different types of biomass pellets in gasification process

Gas from the gasification of pellets made from renewable sources of energy or from lower-quality fuels often contains a number of pollutants. This may cause technical difficulties during the gas use in internal combustion gas engines used for energy and heat cogeneration. Therefore, an adequate system of gas cleaning must be selected. In line with such requirements, this paper focuses on the characterization and comparison of gases produced from different types of biomass during gasification. The biomass tested was wood, straw, and hay pellets. The paper gives a detailed description and evaluation of the measurements from a fix-bed gasifier for the properties of the produced gases, raw fuels, tar composition, and its particle content before and after the cleaning process. The results of elemental composition, net calorific value, moisture, and ash content show that the cleaned gases are suitable for internal combustion engine-based cogeneration systems, but unsuitable for gas turbines, where a different cleaning technology would be needed.