Calorific Value Research Articles

Key Process of Ethanol Hydrogen Donor Promoting the Conversion of Organic Matter in Sludge to Bio-Oil

To develop clean energy utilization of sewage sludge, this study investigated the conversion behavior of organics and energy in supercritical sludge-ethanol system. The influence of liquefied parameters on products distribution, hydrogen supply process of ethanol for sludge liquefaction, migration of organics, and energy transformation were investigated. Results indicated that ethanol acted as both a solvent and a hydrogen donor. It providing H⋅ to promote organics dissociation for bio-oil production through radical reactions. Formation of new products in bio-oil such as C20H38O2 and C20H38O2 may be caused by H⋅ generated from -OH and -CH in ethanol. The increase in dodecanes and hexadecanes in bio-oil may be formed by recombination of smaller radicals such as HO·, H·, CH3⋅, CH3CH2⋅ from dissociation of ethanol and organics. Additionally, energy migration process indicated that higher temperatures increased carbon content in bio-oil from 40.88 to 48.92%, decreased oxygen content from 48.6 to 39.56%, and raised the calorific value of bio-oil from 29.63 to 30.11 MJ/kg. Besides, approximately 74.14% of sludge energy transferred to bio-oil, while about 71.94% of oxygen moved to bio-char, reducing the calorific value of bio-char to 0.03 MJ/kg. Notably, about 240.5kg of bio-oil can be produced from 1t of sludge, reducing net carbon emissions by 43.583kg, and presenting a sustainable alternative to fossil fuels. This study innovatively investigated the dual role of ethanol for sludge liquefaction, providing an efficient and sustainable method for energy recovery from sludge.

Combustion Characteristics and Performance of Nanoflower Structure AlB2@AP Energetic Composites

ABSTRACT Boron-based solids have garnered significant attention due to their high calorific value. However, during combustion, the formation of boron oxide (B₂O₃) on the surface hinders the interaction between the oxidizing components and the internal active boron (B), thereby limiting its reactivity and combustion efficiency. Modifying boron-based solids represents an effective strategy for overcoming the limitations associated with fuel energy release efficiency. In this study, a shell-structured AlB₂@AP composite was designed and fabricated utilizing etching and recrystallization methods. The structure comprises AlB₂ as the core, B as the middle shell, and AP as the embedded outer shell. The key strategy involves employing an etching process to augment the reactive surface area of boron on the aluminum diboride surface, while also coating it with ammonium perchlorate (AP) to enhance the composite particles. This innovative approach demonstrates that the etching method can effectively utilize the boron present in AlB₂. The composite particles were characterized and analyzed for morphology employing a scanning electron microscope and X-ray techniques. Thermal analysis indicated that the decomposition stage of AP facilitated the oxidation of etched AlB₂, moreover, as the AP coating content increased, the temperature at which vigorous reactions initiated occurred earlier. In combustion experiments, the maximum combustion temperatures of AlB₂@10AP, AlB₂@20AP, and AlB₂@30AP increased by 36.4%, 15.1%, and 3.8%, respectively. The combustion formulation prepared with elemental boron exhibited different characteristics. The average combustion temperatures increased by 33.1%, 23.4%, and 14.4%, respectively. The combustion durations were reduced by 60.8%, 33.7%, and 31.7%, respectively. AlB2@AP is anticipated to further enhance its applications in propellants, explosives, and pyrotechnics.

Conceptual design and optimization of a hydrogen-powered aircraft with a dorsal tank layout

Abstract The application of hydrogen as a clean energy source is revolutionizing the aerospace industry, especially in the design and optimization of next-generation aircraft. In this study, a tubular-wing hydrogen-powered aircraft is designed based on a modified Boeing 737 configuration with a dorsal fuselage tank layout. During the design process, the fuselage was parametrically reconstructed to accommodate tanks of different sizes; Subsequently, a multidisciplinary optimization of the hydrogen aircraft was carried out with fuel consumption as the optimization objective. During the optimization process, dynamic mission profiles were introduced to make the fuel consumption calculation more accurate. Finally, this paper compares and analyzes the differences between kerosene-powered and hydrogen-powered aircraft. The results show that the hydrogen airplane has an increase in weight of about 10% and a decrease in lift-to-drag ratio of 1 to 2 units. To offset these effects, a hydrogen airplane would need to be designed with a larger aspect ratio and provide more thrust during flight. Nonetheless, the results also show that, because of the high calorific value of liquid hydrogen, the total energy consumption of the designed hydrogen aircraft is lower than that of a kerosene aircraft for the same range.

Characteristics of exhaust emissions from MGO–bioethanol fuel blend using a combustion chamber

We conducted combustion tests with marine gas oil (MGO) blended with bioethanol (BE) in ratios of 0%–30% to address International Maritime Organization air pollution regulations on exhaust gases emitted from ships and fossil fuel resource depletion and achieve carbon neutrality. We designed and manufactured a standard 1-ton combustion chamber, using an attached gun-type burner to analyze the exhaust gases of each sample under similar conditions. Compared to pure MGO (BE0), the oxygen content increased by approximately 1.91% at the maximum blend ratio (BE30), while carbon dioxide decreased by 1.39%. Nitrogen oxides were reduced by approximately 30%. Sulfur oxides were minimal (<0.03%), with MGO alone at approximately 0.08 ppm, confirming the superior quality of low-sulfur fuel. In all blends containing BE, no sulfur oxides were detected. Additionally, exhaust gas temperature decreased by 5.8%, and combustion efficiency decreased from 72.24% to 70.33%, a reduction of approximately 1.9%. This indicated that BE has a relatively lower calorific value; however, it provides a similar thermal output, with some reduction of exhaust emissions. A one-way ANOVA and post-hoc verification confirmed that with increased BE content, emission differences were significant ( p < 0.01 level in all areas). Through this study, it was confirmed that the use of eco-friendly fuels such as bioethanol has excellent effects on reducing exhaust emissions. It is analyzed that it would help solve global warming and air environment pollution problems. Therefore, it is determined that the future application of MGO-bioethanol blended fuel as an eco-friendly alternative fuel for ships holds significant potential, and positive outcomes are anticipated.

High-efficiency co-liquefaction of brominated epoxy resin and low rank coal in supercritical water: Waste recycling and products upgrading

With the acceleration of upgrading electronic information products, a large amount of electronic waste was generated. Brominated epoxy resins (BERs) are the main nonmetallic components of e-waste. The recycling of BERs has attracted people's attention due to their potential environmental risks. Low rank coal is difficult to efficiently utilize due to its high moisture content, oxygen content and low calorific value. This study developed an efficient co-liquefaction strategy for BERs and low rank coal by supercritical water (SCW) process. Under optimized conditions (temperature of 425 ℃, reaction time of 60min, solid-to-liquid ratio of 1:10g/mL, and BERs-coal mass ratio of 1:4g/g), the total conversion efficiency of co-liquefaction reached 56.76%. When the temperature was 325 - 425 °C, there was a positive synergistic effect between BERs and low rank coal co-liquefaction, and the highest synergy efficiency of 11.13% was reached at 400 °C. The introduction of BERs could significantly reduce the oxygenated compounds and the heteroatomic compounds in the liquefied oil products, improving the quality of oil products. The co-liquefaction promoted the production of phenolic chemicals and inhibited the cross-linking reaction of the decomposition products from low rank coal, and realized the synchronous conversion of BERs and low rank coal. The C-Br bond in the residue was significantly weakened after co-liquefaction. The oil products did not contain brominated organic compounds, also demonstrating the potential of the co-liquefaction process for debromination of BERs.

Olive mill wastewater treatment using coagulation/flocculation and filtration processes

Olive mill wastewater (OMWW), a pollutant resulting from the olive oil industry, poses a serious ecological challenge due to its high pollution load. This effluent is highly concentrated in chemical oxygen demand (COD), which is 200 times higher than that of sewage wastewater. Moreover, OMWW is characterized by a strong acidity, high content of fatty matter, and high concentration of phenolic compounds.In this study, coagulation/flocculation and filtration processes were investigated in order to decrease the pollution load of OMWW for potential reuse in olive orchard irrigation. First, two successive coagulation/flocculation steps were applied to a centrifuged OMWW. Lime and aluminum sulfate (alum) were used as coagulants by testing different concentrations in order to select optimal conditions. Then, the efficiency of various filtration systems using activated carbon and/or natural materials (olive stones, olive leaves, sand, celite, and gravel) was tested. pH, electrical conductivity (EC), total solid (TS), and COD were measured before and after each treatment step (coagulation or filtration). Five phenolic compounds were monitored before and after applying the selected treatment steps under optimal conditions. The quantification and valorization of the sludge derived from coagulation/flocculation were also performed.During the first coagulation/flocculation step, the results showed that the application of 8 g/L of lime combined with 7 g/L of alum allows the removal rates for EC, TS, and COD of approximately 10%, 41%, and 48%, respectively. While the application of 5 g/L of lime and 4 g/L of alum during the second coagulation/flocculation step allows for lower reductions rates for TS (37%) and higher reduction rates for COD (67%). In addition, the resulting sludge showed its potential usage as a solid alternative fuel with a calorific value of 3295.79 cal/g. Moreover, filtration using activated carbon and gravel was found to be the optimum filtration system. The reduction rates were 51%, 37%, and 26% for EC, TS, and COD, respectively.Finally, the combination of coagulation/flocculation and filtration allows the substantial elimination of the studied phenolic compounds with global reduction yields of 97% for vanillyl alcohol, 92% for tyrosol, and 91% for vanillic acid and p-coumaric acid.Besides, Mediterranean countries are suffering from water shortages and the majority of olive mill trituration units are known for their artisanal types thus facing economic challenges. This research suggests a practical treatment process and the final effluent can be used to irrigate olive orchards at a rate of 170 m3 per hectare.

PRODUCTION AND CHARACTERIZATION OF BIOBRIQUETTE FROM BIOMASS OF MANGO LEAF, SAW DUST AND RICE HUSK AS EFFICIENT ENERGY SOURCES FOR COOKING

The increasing demand for sustainable energy solutions has driven interest in alternative biomass sources for energy production. This study investigates the production and characterization of bio briquettes made from different biomass of mango leaves, sawdust, and rice huskusing limestone as binder. The objective is to evaluate the potential of these biomass materials as efficient energy sources for cooking. The bio briquettes were produced using a standard briquetting process, involving mixing, compaction, and drying. Various parameters including ultimate and proximate composition, calorific value, bulk density, hardness and durability as well as mechanical and combustion properties were analyzed to assess their performance. The results demonstrated that the bio briquettes exhibited high calorific values between 20753 to 20506 KJ/kg and high percentage of fixed carbon between 4.18 to 5.58 % which generally indicates good fuel performance.The results also indicated that the bio briquettes has low Sulphur content and high volatile matter content between 50.53 to 62.84 % an indication that they are ecofriendly and can easily burn to yield energy. The bio briquettes of mango leaves, sawdust, and rice husk not only leverages agricultural waste but also contributes to reducing dependency on non-renewable energy sources. This research underscores the potential of utilizing locally available biomass for sustainable energy solutions and offers insights into improving the efficiency of bio briquette production.

Combustion and Energy Parameters of Grape Pomace/Skin Waste in Wine Production—Regent Variety Grafted onto Rootstocks

The study presents the potential use of winemaking residues, specifically grape pomace, for energy purposes. The pomace was obtained from the cultivation of the Regent grape variety on three different rootstocks—125AA, 161-49, and SO4—as well as a control group grown on its own roots. The research included determining the calorific value and combustion heat, conducting a technical and elemental analysis of the potential biofuel, as well as estimating emission indicators (CO, CO2, NOx, SO2, and particulate matter) and the theoretical volume of flue gases based on stoichiometric equations. The study revealed significant differences among the combustion heat, tested properties and calorific value, ash content, and the total volume of flue gases. The highest calorific value (17.7 MJ kg−1) and combustion heat (18.9 MJ kg−1) were obtained for pomace from the SO4SO4 rootstock, while the lowest values were observed in the control group (17.0 MJ·kg−1 and 15.8 MJ·kg−1, respectively). The highest ash content was also recorded for the SO4 rootstock (9.2%), with the lowest in the control group (6.7%). The control group exhibited the lowest CO2 emissions at 1390.50 kg·Mg−1, while the highest emissions were found in the pomace from the SO4 rootstock (1478.8 kg·Mg−1). Regarding the total flue gas volume, the highest volume was estimated for the pomace from the 125AA rootstock (7.8 m3·kg−1) and the lowest for the control group (7.3 m3·kg−1). The research demonstrated that grape pomace possesses favorable energy properties and could serve as a potential biofuel, contributing to the fuel and energy balance of agricultural production enterprises. The analyzed biomass exhibits properties similar to agrobiomass.

The Effect of Adhesive Ratio on the Quality of Charcoal Briquettes

This study used cassava stem charcoal and charcoal from forest fires mixed with tapioca adhesive at different ratios, the aim was to analyze the effect of different adhesive ratios on the quality of charcoal briquettes.Charcoal briquettes are formed using a 40 bar press machine with a pressing time of 10 minutes. The mixture of charcoal briquette raw materials uses a tapioca adhesive ratio of 2%, 4%, 6%, 8% and 10%.Testing is carried out to determine the quality, then analyzed and compared with the SNI 01-6235-2000 standard.The effect of adhesive ratio on adhesive quality was analyzed using a Completely Randomized Design (CRD). The test results show the following values:density 0.54 g/cm3, moisture content 4.97%, compressive strength 28.43 kg/cm2, volatile matter content 36.02%, ash content 6.36%, fixed carbon content 56.45% and calorific value 6,195 cal/gobtained from a 10% adhesive ratio. The adhesive ratio has a very significant effect on the water content, compressive strength and calorific value; has a significant effect on the density value; and has no significant effect on the volatile matter value, ash content and bound carbon content.The results of charcoal briquette testing mostly meet the standards according to SNI (No. 01-6235-2000)

Development of Dietetic Misti Dahi (Indian Yoghurt) Using Natural and Artificial Sweeteners

Dairy based sweetmeats usually contain high sugar with a high calorific value which in turn is linked to various non-communicable diseases. To reduce this high calorie content, sugar can be replaced in part or wholly by non-nutritive artificial sweeteners, as well as natural sweetener like honey. In the present study natural and artificial sweetener sources (honey and sucralose, respectively) were used to replace sucrose in part or completely to develop low calorie fat reduced misti dahi, an Indian yoghurt. Effect of sweeteners on setting time, proximate composition, microbiological quality and calorific value of mistidahi, and sensory quality were analysed as per the standard methods. Protein and total solids (TS) content decreased from 4.22 to 3.96% or 4.39 to 4.23% in honey or sucralose and from 24.20 to 21.99% in honey or 21.57 to 16.70% in sucralose, respectively with increase in honey or sucralose used to replace sucrose in mistidahi, while fat content was variable. Microbiological analysis revealed that with an increase in the content of honey, the total aerobic plate count (TAPC) of mistidahi tended to show an increase, while for sucralose containing samples a decreasing trend in TAPC in mistidahi was noted.

Optimizing Syngas Production from Municipal Solid Waste Gasification: A Dual Reactor Fluidized Bed Study with Steam and CO2 as Gasification Agents

The escalating production of municipal solid waste (MSW) poses significant environmental and health hazards due to air, water, and soil pollution. Utilizing MSW as an energy source through gasification offers a promising solution to mitigate these impacts. This study investigates the gasification of MSW using a Dual Reactor Fluidized Bed, a thermal technology that converts solid substrates into usable gaseous fuels. The primary objective is to optimize the quality of the produced syngas by employing specific gasification agents, namely steam and CO2, and their mixtures. The research examines the effect of these agents on H2/CO ratios across a wide range of low operating temperatures, from 400°C to 700°C, using silica sand as a heat conduction medium between interconnected combustion and gasification reactors. The results demonstrate that the composition of syngas is strongly influenced by gasification temperature fluctuations. Increasing temperatures from 400°C to 700°C correlate with higher concentrations of CO and H2 in the syngas. The use of steam as a gasification agent yields H2 concentrations up to 25%, while transitioning from steam to CO2 leads to a substantial increase in CO composition, reaching 22.73%. Further analysis reveals that the H2/CO ratio decreases from 1,78 with steam and 0.64 with CO2, highlighting the crucial role of gasification agents in syngas quality. This study underscores the potential for optimizing syngas production from MSW by manipulating gasification temperatures and transitioning between different agents (steam, CO2, and their mixtures), resulting in an overall increase in the calorific value of the produced gas. These findings emphasize the opportunity to transform substantial environmental challenges associated with MSW into promising sustainable energy solutions through advanced gasification technologies.

Mathematical model for heat transfer during underground coal gasification process

Purpose. To develop a mathematical model of the “coal-gas” medium heat transfer during underground coal gasification to predict the combustion face advance velocity and the duration of gasification column mining. Methodology. To detect the temperature fields in the coal seam and gas, depending on the displacement length of the phase transition boundary, a boundary-value problem of mathematical physics has been developed. To solve this boundary-value problem, Boltzmann transformations, as well as methods for solving ordinary differential equations, are used. Newton-Raphson method, which has quadratic convergence, is used to find the roots of the transcendental equation. Findings. Tendencies in the formation of mathematical models when studying temperature fields around an underground gasifier have been analyzed, with highlighting their disadvantages. A mathematical model of heat transfer during underground gasification has been developed, taking into account the phase transition boundaries of the “coal-gas” medium. A computational experiment was conducted to determine the temperature of the phase transition boundary based on the length of the gasification column and the duration of the process. Originality. A mathematical model for heat transfer during coal gasification in the form of a boundary-value problem of mathematical physics, which consists of parabolic heat-transfer equations, the Stefan condition at the phase transition boundary, and the Dirichlet boundary conditions, has been constructed. As a result of solving the boundary-value problem, a self-similar solution has been obtained for the distribution of the coal seam and gas temperature fields, as well as the position of the phase transition boundary depending on the gasification duration and on the medium density, thermal conductivity coefficients, specific heat capacity of gas and coal, specific calorific value and temperature of coal combustion, initial coal temperature and constant temperature of the gasification process. The conducted analysis of numerical calculations provides a deeper understanding of the dynamics of underground coal gasification process and makes necessary corrections to achieve the maximum process efficiency. Practical value. A methodology for determining the displacement length of the phase transition boundary of the “coal-gas” medium has been developed, taking into account the change in the combustion face temperature along the gasification zone length depending on the duration of this process. Application of the methodology makes it possible to predict the time of mining the gasified coal column for drawing up a calendar plan for mining operations.

The Quality Test of Utilization of Palm Oil Solid Waste As a Raw Material For Refuse Derived Fuel (RDF) For Alternative Fuels.

The use of palm oil solid waste as a raw material for refuse derived fuel (RDF) is a promising alternative to overcome environmental and energy problems. This study aims to test the quality of RDF produced from palm solid waste by paying attention to the composition of the mixture and treatment method through quantitative experimental methods, which are divided into two stages: processing and quality testing. The results showed that the average calorific value of RDF reached 4,216.75 cal/g, moisture content 10.76%, ash content 4.37%, volatile matter 58.11%, and fixed carbon 26.75%, all of which showed great potential as an alternative energy source. Although the RDF calorific value of palm solid waste is higher than the industry standard, the moisture content and ash content are still below international standards, and the calorific value is slightly below the SNI class 1 standard but higher than that of class 2 and 3. These findings indicate that RDF from palm oil solid waste has the potential to be a good quality alternative fuel.

PEMANFAATAN LIMBAH ORGANIK SEBAGAI ENERGI ALTERNATIF MENGGUNAKAN REAKTOR GASIFIKASI DOWNDRAFT

Organic waste from coconut shells, corn cobs, candlenut shells, and lamtoro wood is often found in the Gorontalo region. The gasification of organic waste has the potential to reduce organic waste and produce gas for various applications, including heating, power generation, and industrial raw materials. The research aims to determine the gas composition of the downdraft gasification process from organic waste from coconut shells, candlenut shells, corn cobs, and lamtoro wood, to determine the rate of fuel consumption, and to determine the calorific value. The method used is an experimental method. Test results using a downdraft gasifier reactor with 5 kg of fuel. The average H2 value obtained from the test results for coconut shells was 12.46%, candlenut shells 13.01%, corn cobs 9.3%, and lamtoro wood 15.95%, the highest H2 value from several of these samples was obtained from lamtoro wood with the highest percentage was 15.95%, the average O2 value obtained was coconut shell 8.86%, candlenut shell 6.37%, corn cob 2.61%, lamtoro wood 5.22%, the average CH4 value was shell coconut 7.88%, candlenut shell 4.05%, corn cob 8.03%, lamtoro wood 7.32%, average CO value for coconut shell 0.56%, candlenut shell 0.05%, corn cob 10 .71%, lamtoro wood 0.05% while the average N2 value obtained was 70.21% coconut shell, 76.49% candlenut shell, 69.25% corn cob, and 71.44% lamtoro wood. The findings compare four organic wastes as alternative energy using a downdraft gasification reactor. The conclusion from this research is that the best gas composition is from corncob organic waste with H₂, CH₄, and CO of 28.05%, the longest burning rate on corncob samples is 23.11 grams/minute and the highest calorific value test is on lamtoro wood samples with results reaching 4,340 cal/gram.

Energy Recovery from Municipal Sewage Sludge: Combustion Kinetics in a Varied Oxygen–Carbon Dioxide Atmosphere

Energy from municipal sewage sludge can be obtained by applying a thermal conversion method. In this study, the combustion kinetics of municipal sewage sludge were analyzed in an O2/CO2 atmosphere. Studies were conducted in different gaseous atmospheres consisting of varying proportions of oxygen and carbon dioxide. The participation of oxygen was as follows: 20, 40, 60, 80 and 100% vol. The experimental temperatures varied from 873 to 1273 K. The experimentally obtained results helped establish the basic kinetic parameters, such as the reaction order n, factor Ko and activation energy Ea of sludge grains. The values of the activation energy Ea and Ko were, respectively, 46 kJ/mol and 0.0127 mg/m2sPa. They show that the limiting factor of combustion is the diffusion of oxygen and that combustion reactions take place in the outer layer of the unreacted core. Therefore, sludge is promising for energy recovery because it has quite a high net calorific value (NCV) and a high gross calorific value (GCV). The GCV was 14.1 MJ/kg and the NCV was 12.8 MJ/kg. The experimental studies with a wide range of process parameters helped to create an array of apparent reaction rates as a function of the temperature and oxygen concentration, showing the significant effect of oxygen on the apparent reaction rate, in contrast to the effect of temperature.

Analysis of the Physical and Chemical Composition of Sludge from the Water Treatment Plant

The properties and composition of the sludge generated in water treatment systems depend primarily on the type and composition of the water to be treated, the treatment methods, and the type and doses of chemical reactants. The sludge produced in the water treatment plant (WTP) under study follows the technological processes of coagulation, flocculation, sedimentation, and filtration. The analyses aimed to characterize the sludge in terms of its physico-chemical properties and classify it in terms of its potential discharge into the river and management. Four series of sediment tests were conducted over a calendar year (March, June, September and December), analysing selected parameters using various test methods, including the X-ray crystallography (XRF) method. The publication's authors showed that the sediment consists mainly of sand, clay, and silt particles with grain sizes ranging from 0.001 mm to 1 mm. Silica (53.78%), alumina (23.58%), calcium oxide (8.28%), iron (III) oxide (5.61%), and potassium oxide (2.36%) represent the main chemical constituents present in the sediment. The authors characterized the sediment in terms of the content of biogenic compounds: various forms of phosphorus and nitrogen, organic compounds – determined as total organic carbon (TOC), selected metals, and the content of individual elements (carbon, hydrogen, oxygen, nitrogen, sulfur). In addition, the sludge samples were also characterized in terms of calorific value, ash content, water content, and heat of combustion. Discharging WTP sludge into rivers, ponds, and lakes or storing dewatered sludge is an environmentally unfriendly form of disposal for this type of waste. The authors see the possibility of conducting further research on using WTP sludge in wastewater treatment, removing heavy metals from aqueous solutions, producing cement and construction materials, and recovering or recycling.

Simulation of Dynamic Characteristics of Supercritical Boiler Based on Coupling Model of Combustion and Hydrodynamics

To accommodate the integration of renewable energy, coal-fired power plants must take on the task of peak regulation, making the low-load operation of boilers increasingly routine. Under low-load conditions, the phase transition point (PTP) of the working fluid fluctuates, leading to potential flow instability, which can compromise boiler safety. In this paper, a one-dimensional coupled dynamic model of the combustion and hydrodynamics of a supercritical boiler is developed on the Modelica/Dymola 2022 platform. The spatial distribution of key thermal parameters in the furnace and the PTP position in the water-cooled wall (WCW) are analyzed in a 660 MW supercritical boiler when parameters on the combustion side change under full-load and low-load conditions. The dynamic response characteristics of the temperature, mass flow rate, and the PTP position are investigated. The results show that the over-fire air (OFA) ratio significantly influences the flue gas temperature distribution. A lower OFA ratio increases the flue gas temperature in the burner zone but reduces it at the furnace exit. The lower OFA ratio leads to a higher fluid temperature and shortens the length of the evaporation section. The temperature difference in the WCW outlet fluid between the 20% and 60% OFA ratios is 11.7 °C under BMCR conditions and 7.4 °C under 50% THA conditions. Under the BMCR and 50% THA conditions, a 5% increase in the coal caloric value raises the flue gas outlet temperature by 32.7 °C and 35.4 °C and the fluid outlet temperature by 6.5 °C and 9.9 °C, respectively. An increase in the coal calorific value reduces the length of the evaporation section. The changes in the length of the evaporation section are −2.95 m, 2.95 m, −2.62 m, and 0.54 m when the coal feeding rate, feedwater flow rate, feedwater temperature, and air supply rate are increased by 5%, respectively.

Optimasi Peningkatan Karakteristik Crude Palm Oil (CPO) sebagai Bahan Bakar Diesel

Indonesia is one of the largest palm oil-producing countries in the world, significantly contributing to global palm oil needs. The use of palm oil as fuel is generally achieved through the biodiesel manufacturing process; however, this process remains costly and thus less economical. Additionally, the primary obstacle in using crude palm oil (CPO) is its high viscosity, which can cause blockages in the fuel injector channels of diesel engines. Therefore, modifications are necessary to enhance the characteristics of CPO so that it can be used directly as diesel engine fuel. This can be achieved through heating and the addition of 2-EHN additives. This study aimed to optimize the characteristics of CPO using Response Surface Methodology (RSM) to determine the optimal combination of temperature and 2-EHN concentration. The optimal point was identified at a temperature of 50°C and a 2-EHN concentration of 2%. The results of the CPO characteristic test showed a viscosity of 4.45 CSt, a density of 0.884 g/ml, a cetane number of 56.9, and a calorific value of 9314 kcal/kg

Transesterification of biodiesel from kapok seed oil (ceiba pentandra) using a natural heterogeneous katalyst (rice husk activation)

Biodiesel as a renewable energy source can be produced by a chemical reaction between vegetable oil or animal fat and short-chain alcohol such as methanol, ethanol or buthanol and is supported by a catalyst. This process is called transesterification. From an environmental point of view, the use of biodiesel has several advantages such as reducing carbon dioxide emissions, being non-toxic and biodegradable. Kapok seed oil has potential for exploitation, particularly as a raw material for the manufacture of biofuel. Kapok seeds (Ceiba pentandra) have the potential to be used as a feedstock for biodiesel because their oil content is quite high, around 18-25% oil. The controlled combustion of rice husks produces ash containing high purity amorphous silica. Amorphous silica can be obtained from RHA (rice husk ash) when rice husk is burned at a temperature of 700°C, and it is transformed into crystalline silica when burned at a temperature above 850 °C. This silica has many applications as a filler, adsorbent, catalyst support, star gel component and source for the production of premium silicon and its compounds. The aim of the research is to determine the transisterification process of biodiesel from kapok (Ceiba pentandra) seed oil. using a natural heterogeneous catalyst in It is an activated rice husk. The method used was the preparation of kapok seed samples and the extraction of sokhlet. Determination of free fatty acids (FFA) in kapok seed oil, activation of rice husk, manufacturing of biodiesel from kapok seed with addition of rice husk H2SO4 as catalyst. The characteristics of the biodiesel produced are Density: 859.88572 kg/m3 (SNI: 7182:2015) = 850-890 kg/m3), Viscosity: 2.45824 cSt (SNI: 7182:2015) = 2.3 – 6, 0 cSt, Calorific value: 7,374.5322 cal/g (SNI: 7182; 2015) = 7,100 -11,000 cal/ g, Devil's number: 48 (ASTM: D6751) = 47. Meanwhile, GC-MS with the highest values at all reaction times, namely Hexadec anoic acid, methyl ester (C17H34O2), methyl tetradecanoate (C15H30O2) and 9 - Octadecenoic acid (Z), methyl ester (C19H36O2) . The functional group found in kapok seeds is –OH.

Energy Quality of Corn Biomass from Gasoline-Contaminated Soils Remediated with Sorbents

Soil contaminated with petroleum-derived products should be used to cultivate energy crops. One such crop is Zea mays. Therefore, a study was performed to determine the suitability of Zea mays biomass obtained from gasoline-contaminated soil for energy purposes. The analysis included determining the heat of combustion and calorific value of the biomass, as well as the content of nitrogen, carbon, hydrogen, oxygen, sulfur, and ash in the biomass. Additionally, the suitability of vermiculite, dolomite, perlite, and agrobasalt for the phytostabilization of gasoline-contaminated soil was evaluated. It was found that the application of sorbents to gasoline-contaminated soil significantly reduced the severe negative effects of this petroleum product on the growth and development of Zea mays. Gasoline contamination of the soil caused a significant increase in ash, nitrogen, and sulfur, along with a decrease in carbon and oxygen content. However, it had no negative effect on the heat of combustion or calorific value of the biomass, although it did reduce the energy production from Zea mays biomass due to a reduction in yield. An important achievement of the study is the demonstration that all the applied sorbents have a positive effect on soil stabilization, which in turn enhances the amount of Zea mays biomass harvested and the energy produced from it. The best results were observed after the application of agrobasalt, dolomite, and vermiculite on gasoline-contaminated soil. Therefore, these sorbents can be recommended for the phytostabilization of gasoline-contaminated soil intended for the cultivation of energy crops.