Net Calorific Value Research Articles

Experimental Study on Properties of Syngas, Tar, and Biochar Derived from Different Gasification Methods

Biomass gasification technology is a clean and renewable energy utilization approach. Understanding the evolution of gasification product properties is crucial to achieving carbon neutrality goals. A fixed-bed reactor is employed for the biomass gasification with CO2 in this study. Various methodologies have been conducted to characterize the syngas, tar, and biochar produced from the electric gasification (EG) and microwave gasification (MG) of oak and corn stalk samples at different temperatures. When gasifying the same biomass at the same temperature, the syngas yield of MG is generally 3–7% higher than that of EG, and the difference increases with decreasing temperature. The biochar yield of MG is 3–6% higher than that of EG. EG produces more tar at 600–800 °C. The yield of syngas increases as the gasification temperature rises from 600 to 1000 °C, but that of tar and biochar falls. The syngas mainly comprises H2, CH4, CO, and CO2. MG produces 8–15% higher CO content and 2.5–3.5% higher H2 content than EG. This is due to different heating mechanisms. The net calorific value of syngas increases with temperature, reaching a maximum of 11.61 MJ m−3 at 1000 °C for syngas from corn stalk MG. When the temperature rises from 600 to 1000 °C, more primary tars are converted into polycyclic aromatic hydrocarbons (PAHs). At 900 °C, corn stalk biochar from MG has a maximum specific total pore volume (0.62 cm3 g−1), surface area (525.87 m2 g−1), and average pore diameter (4.18 nm). The intensities of the characteristic peaks of biochar functional groups decrease gradually. The heating method has little effect on the types of functional groups.

Towards Electricity from the Combustion of Agricultural Waste in Boilers with Low CO2 Emissions

To meet the growing energy needs of the world’s population, international governments have turned to biomass energy from agricultural waste as a form of renewable energy. To this end, this study is based on the experimental and practical determination of certain physicochemical properties of three agricultural residues (cocoa cortex, oil palm fibres and sugar cane bagasse) using approximate and structural analysis methods. Then, using a METERK electronic detector, the small quantities of CO2 emitted during combustion in 0.5 g boilers of each of these waste products used to produce energy (heat and/or electricity) were determined. The gross and net calorific values of these biomasses were also determined. Here are some of the results obtained for these three agricultural residues: variable moisture content (from 3.6% to 43.12%), variable organic matter content (from 76.12% to 90.31%), cellulose content (from 32.74% to 55.91%), lignin content (from 8.26% to 27.05%), variable net calorific values (from 6.581 kWh/kg to 10.461 kWh/kg) and low CO2 gas emissions (from 439 ppm to 447 ppm). This proves that these three agricultural residues are very good potential sources of energy that can be used as fuel in boilers to produce large quantities of heat that can be converted into electricity by turbines connected to alternators using electromagnetic induction phenomena. Finally, this work provides credible information for public and private decision-makers in the field of electricity production from the combustion of these agricultural residues in boilers.

Acquisition, Characterization, and Optimization of Distilled Bioethanol Generated from Fermented Carrot (Daucus carota) Residues

Bioethanol is a liquid biofuel produced from the digestion of biomass and usable waste of organic origin. The objective of this research was to obtain bioethanol from carrot (Daucus carota) residues of the Peruvian Chantenay variety, with a high content of lignocellulosic substances. The in-batch process method of enzymatic hydrolysis, with Aspergillus niger amyloglucosidase, and fermentation, with Saccharomyces cerevisiae yeast, was applied. The ferment was steam distilled and chemically characterized. The process was evaluated by controlling pH and enzyme/yeast mass ratio through the response surface optimization. The optimum conditions for the best values of TSS and % ethanol content for the distilled product were a time of 300 min, yeast/enzyme mass ratio of 24.0, and pH of 4.98. The results showed a significant decrease in sugars in the hydrolysis and fermentation stages, optimum alcohol content in the distilled product of 92.48% (v/v), lower organic compound content, and net calorific value of 23.82 MJ/kg, which is higher than those reported in the literature.

Investigation of the physical properties and environmental impact of lemongrass biobriquettes

At present, biobriquettes have become an attractive fuel option due to the increasing price of fossil fuels. However, the effective raw materials for biobriquettes require specific physical properties to obtain desired shapes and net calorific value. Therefore, the objective of this study was to explore a raw material with appropriate physical properties for biobriquettes. In this study, lemongrass was used as raw material for biobriquettes which formed by mixing with charcoal and a binder. The basic physical properties of biobriquettes, such as density, moisture content, net calorific value, ash content, volatile matter, and carbon content, were analyzed. Moreover, the net calorific value and the carbon content were determined to find the carbon dioxide (CO2) emission factor. The amount of CO2 emission when using lemongrass biobriquettes substituted for the conventional biomass sources was also determined. The results showed that the density varied depending on the pressure compaction conditions. Besides, the carbon content was successfully determined and reported. The average net calorific value under all compression pressures was reported. The net calorific value of lemongrass biobriquettes was higher than that of firewood and most agricultural wastes, with an average CO2 emission factor of 77,362 kgcarbon/TJ. Based on all the results obtained, it can be concluded that lemongrass biobriquettes produce a lower CO2 emission than firewood, most agricultural wastes, and charcoal; therefore, it is suitable as an alternative biofuel in the future.

Utilization of Brown Coal with Ceara Rubber (Manihot glaziovii) Binder for Biobriquettes

Based on the ultimate and proximate analysis, brown coal and ceara rubber (biomass) had low calorific values of 5,349 and 3,319 kcal/kg, respectively. The ceara rubber was not included in the food ingredient because it contained chemicals such as toxic cyanide acid. This research was conducted to utilize the biomass in biobriquettes that had added value and became a more environmentally friendly energy source compared to fossil fuels. The mixing ratio of the biobriquette was determined at various particle sizes. Biobriquette preparation included crushing, drying, size reduction, sieving, mixing, molding, and testing. The produced biobriquette was cylindrical with a diameter of 3 cm and pressing pressure of 7 metric tons. Biobriquette analysis included compressive strength tests, tests of density, tests of moisture, ash, and fixed carbon content, tests of the volatile matter, and tests of calorific values. These biobriquettes were expected to increase the selling value of low-rank coal and become one alternative to more environmentally friendly solid fuel for cooking purposes. Based on the research results, the best biobriquette had a particle size of 60 mesh. The result showed that the best particle size was on the mixing ratio of 3:2, with the net calorific value reaching 4,300.8 kcal/kg.

Comprehensive study of the kinetics of combustion and pyrolysis of petrochemical sludge: Experimentation and application of artificial neural network

Energy can be obtained from the pyrolysis and combustion of purified terephthalic acid (PTA) sludge which is produced during the treatment of PTA wastewater. In this study, the combustion and pyrolysis behaviors and kinetics of the sludge produced from the thermochemical treatment of PTA wastewater were analyzed under non-isothermal heating. It was found that reaction orders were in the range of 1–3 for oxidation/combustion. The reactions were exothermic, as indicated by the negative change in enthalpy. The phenomenon of auto gasification was observed during pyrolysis for three sludges. The analysis of the change of activation energy with the degree of conversion showed that several parallel reactions occurred at the beginning of the sludge decomposition during air combustion. The value of activation energy for CuSO4, FeCl3 and FeCl3 + CPAA sludge was 99.5 kJ/mol, 109 kJ/mol and 118.7 kJ/mol, respectively, for pyrolysis and 116.3 kJ/mol, 68.8 kJ/mol, and 127.9 kJ/mol, respectively, for combustion. These sludges are promising for energy recovery because they have a high net calorific value (NCV) and a high gross calorific value (GCV). The GCV was 22.4 MJ/kg, 19.8 MJ/kg, and 28.4 MJ/kg for CuSO4, FeCl3, and FeCl3 with CPAA, respectively and the NCV was 22.3 MJ/kg, 18.6 MJ/kg, and 27.3 MJ/kg for CuSO4, FeCl3, and FeCl3 with CPAA, respectively. The artificial neural network was used to validate the experimental results. The correlation coefficient between the expected and experimental results were 0.9945, 0.9980 and 0.9980 for CuSO4, FeCl3 and FeCl3 +CPAA sludge for pyrolysis, respectively and 0.9989, 0.9963 and 0.9968 for CuSO4, FeCl3 and FeCl3 +CPAA sludge for combustion, respectively. The developed ANN model successfully predicts the combustion and pyrolytic process for petrochemical sludge under specified conditions.

Utilization of used bleaching clay in pellet fuel production with torrefied oil palm fronds

Torrefaction oil palm fronds was studied as a renewable biomass resource for efficient and sustainable pellet fuel production. Employing microwave heating during torrefaction, the process optimized the conditions to enhance the fuel properties. At 300 °C for 40 minutes, the torrefied oil palm fronds exhibited a remarkable rise in net calorific value to 23 MJ/kg, accompanied by a substantial increase in fixed carbon content to 46%. These enhancements signify a significant boost in energy content and carbon richness, which is crucial for cleaner and greener energy solutions. Comparing pellet fuels derived from raw and torrefied biomass, a striking difference in calorific values was observed. While raw biomass pellets reached 12.24 MJ/kg, their torrefied counterparts achieved an impressive 18.40 MJ/kg. This undeniable advantage highlights the effectiveness of torrefaction in elevating energy output. To optimize the composition of the pellet fuel, an ideal mass proportion of torrefied oil palm fronds and used bleaching clay was identified as 70:30. This blend resulted in the highest recorded calorific value, further endorsing the viability of the approach. In conclusion, torrefaction at 300 °C for 40 minutes proved to be a potent technique for enhancing oil palm fronds as a valuable source of pellet fuel. These findings underscore its potential to revolutionize renewable energy production, promoting sustainability and mitigating environmental impact.

Development of alternative fuel for cement industries: The case of Messebo cement factory in Ethiopia

The cement industry is struggling with dwindling fossil fuel resources and environmental issues related to climate change. This sector is known for its high energy consumption and generates significant CO2 emissions, accounting for 19% of global thermal energy consumption and 7% of CO2 emissions. For this reason, Cement industries are seeking to replace traditional energy sources with alternative fuels. This study aims to investigate and optimize alternative fuels, evaluating their chemical and physical properties, energy output, production capacity, effect on clinker quality, and impact on combustion flue gas emissions. The study shows that the alternative fuels meet or exceed the minimum international standard of 14 MJ/kg for net calorific value. Therefore, they could replace up to 40% of South African coal in the clinker pre-calcining process. Using alternative fuels such as P. j wood, P. j leaf, P. j charcoal, used tire, and optimized fuels could potentially reduce CO2 emissions by 2%, 9%, 9%, 21%, and 17% respectively. Therefore, policy makers and companies should strongly consider adopting these recommended alternatives.

Energy value of silver fir (Abies alba) and Norway spruce (Picea abies) wood depending on the degree of its decomposition by selected fungal species

Negative environmental impacts related to climate change and social pressure to raise the rotation age of forests contribute to the quality deterioration of harvested wood, including its decomposition by fungi. This paper presents the results of laboratory experiments investigating the decomposition of Norway spruce (Abies alba) and silver fir (Picea abies) wood by selected species of decay fungi: Hericium flagellum and Bondarzewia mesenterica (causing white rot) as well as Rhodofomes roseus (causing brown rot). The decay process affects wood density, elemental composition, net calorific value, as well as the amount and price of the energy contained in the wood. Wood density was measured conventionally using an electronic caliper and laboratory balance. Energy parameters were determined using elemental analyzer and combustion calorimeter. Wood decay was found to adversely affect energy content per unit of wood at a given volume, thus leading to higher prices per unit of energy. Over the 120 days of the experiment, wood parameters were not affected considerably by Hericium flagellum or Bondarzewia mesenterica. Of the three examined fungal species, Rhodofomes roseus caused the highest weight loss of wood and the greatest decrease in its oven-dry density (spruce - a decrease from 409 to 214 kg m−3; fir - a decrease from 420 to 306 kg m−3), unfavorably reducing energy content per 1 m3 of wood (spruce – decrease by 3.8 GJ m−3; fir – decrease by 2.3 GJ m−3) and raising the unit price of energy.

Study on the initial pyrolysis kinetics of strained polycyclic hydrocarbons

Strained polycyclic hydrocarbons are one of the most important classes of high-energy density fuels. In this work, the thermodynamics and initial pyrolysis kinetics of five strained polycyclic hydrocarbons, which are isomers of JP-10 and are linearly aggregates of two cyclopropyl rings and one cyclobutyl ring, were investigated using quantum chemical computations. The initial pyrolysis reactions include ring bond breaking and bridge bond breaking. The ring bond breaking reactions include a diradical pathway which is the direct C-C bond breaking to produce a diradical and an isomerization pathway involving concert bond breaking and H-atom transfer, and the bridge bond breaking reactions lead to two radicals. Our potential energy calculation shows that the ring bond breaking reactions are much more energetically favorable than the bridge bond breaking reactions, which can be neglected in the initial pyrolysis process of strained polycyclic hydrocarbons. The rate constants of the ring bond breaking reactions were computed using variational transition state theory (VTST) or transition state theory (TST). Our calculated results demonstrated that ring bond breaking reactions of the three-membered ring are competitive with that of the four-membered ring. The studied reactions are divided into classes depending on the size of the rings (three- or four-membered ring) and the types of the carbon atoms of the breaking C-C bond (Cs-Cs, Cs-Ct, Ct-Ct and Cq-Cs). Reaction rate rules are established for each class, which are useful for the mechanism generation for analogous strained polycyclic hydrocarbons. Thermodynamic properties including net calorific values per mole, gravimetric net heat of combustion and impulse time of our studied strained polycyclic hydrocarbons are higher than those of JP-10. A comparison of the initial pyrolysis kinetics of our studied strained polycyclic hydrocarbons with the isomer JP-10 indicates that these compounds may be easier to pyrolyze.

Analysis of Resource Potential of Emergent Aquatic Vegetation in the Curonian Lagoon of the Baltic Sea

This paper presents results of an aquatic vegetation resource potential assessment. The study is aimed at assessing the perspective of biotechnological approaches to reducing the biogenic pollution of water bodies by the removal of aquatic vegetation. The article analyzes the dominant species of aquatic vegetation in the Curonian Lagoon, and their productivity and resource potential. It was established that the concentrations of protein and fat in the biomass of four dominant plants are extremely low, making it impossible to speak of their values in terms of biomass processing. Based on elemental composition, we can conclude that the biomass of Phragmites australis should have a high calorie content because it has a high carbon and hydrogen content (49.6% and 7.1%, respectively), resulting in a high energy value. Synchronous thermal analysis revealed that the maximum energy values of biomasses of Phragmites australis and Scirpus lacustris have a net calorific value of 12.62 and 12.55 MJ/kg, respectively. At the same time, the biomass of these plants has a low ash content (around 6.6–7.6%) and a low sulfur content (less than 0.41%). An analysis of the composition of aquatic vegetation biomass samples allowed us to establish that, given the permissible collection time (no earlier than September), the search for directions in the utilization of aquatic vegetation should focus on processing cellulose with the production of crystalline cellulose, biochar, or biofuel via anaerobic digestion. The removal of the excess biomass of aquatic vegetation (Phragmites australis) will allow the reduction of the nitrogen and phosphorus load in the water body by 140 kg/ha and 14 kg/ha, respectively.

Study of the Briquetting Process of Walnut Shells for Pyrolysis and Combustion

Walnut shells can be used as fuels in power plants directly or as biochars obtained by pyrolysis or torrefaction. They are an example of clean waste biomass which shows a low ash content and a high Net Calorific Value, making them excellent for energy recovery in industrial and non-industrial applications, such as in bakeries, restaurants, and homes. Their main inconvenience is their low bulk density. Densification is a possible solution that reduces the costs of transportation, handling, and storage. In this work, after the characterization of the walnut shells, briquettes were obtained using a hydraulic piston press briquette machine under different conditions to find the best quality without the need for previous grinding for pelletizing. This method features easy operation and maintenance, and the briquette shape could be adapted as desired. The quality of the briquettes was measured through their density and durability. After fixing a compaction pressure to obtain acceptable briquettes, the factors affecting their quality were studied: operating temperature, moisture content, and the presence of small amounts of walnuts. Good quality briquettes were obtained with a compaction pressure of 66 MPa, with densities around 1040 kg/m3, and durabilities higher than 94% when the process was carried at 140 °C. The greatest increase in durability was observed between briquettes obtained at room temperature and those obtained at 80 °C. The presence of small amounts of walnuts, common after the shelling process, improved the durability. Although water is necessary, briquettes obtained from biomass with only 1% of moisture showed better durabilities. Therefore, walnut shells are suitable for obtaining good quality briquettes according to the specifications of solid biofuels established in the standards, without the need for any pretreatment.

Structural, thermal and energetic properties of Andean-pseudocereal flours with high nutritional values

Structural, thermal and energetic properties of quinoa, kiwicha and kañiwa native Andean-pseudocereal flours have been studied. Moisture, protein and fat contents and also metallic and semi-metallic levels were, in general, within of the range values reported in the literature. Empirical formulas of quinoa, kiwicha and kañiwa flours have been determined as CH1.87O0.81N0.06S0.0015, CH1.90O0.82N0.05S0.0019 and CH1.76O0.73N0.06S0.0017, respectively. The elemental carbon concentration (Cflour) in organic matter follows the trend, Ckañiwa (45.6%) > Ckiwicha (43.2%) ≈ Cquinoa (43.3%), which reflects the greater structural similarity between the quinoa and kiwicha flours, with respect to kañiwa flour. Regarding thermal and energetic properties: (i) in the temperature range of 261.15–343.15 K, we found no significant differences among the specific heat capacities of the three flours, which are ranged between 1.3 and 1.9 J g−1 K−1; (ii) the organic matter decomposition temperature (Tdec) followed the trend, Tdec,kañiwa (489.8 ± 1.6 K) > Tdec,kiwicha (479.1 ± 1.5 K) ≥ Tdec,quinoa (477.1 ± 1.5 K) indicating a greater thermal stability range of kañiwa flour; (iii) the gelatinization temperatures and also the gelatinization enthalpy of kañiwa flour (4.3 ± 1.6 J g−1) were lower than corresponding thermal gelatinization parameters of quinoa and kiwicha flours; and (iv) the standard massic energy of combustion (− Δcu°) or its associated net calorific value (qNCV) of kañiwa flour (18.77 ± 0.15 kJ g−1 or 4487 ± 36 kcal kg−1) was slightly greater than for kiwicha (18.47 ± 0.11 kJ g−1 or 4415 ± 26 kcal kg−1) and quinoa (18.60 ± 0.16 kJ g−1 or 4445 ± 39 kcal kg−1) flours. Taking into account the associated uncertainties, qNCV trend is similar to the Cflour and Tdec trends. Accordingly, our results indicate a greater range thermal stability and greater net calorific value for kañiwa flour than for kiwicha and quinoa flours.

Calorific Value of Zea mays Biomass Derived from Soil Contaminated with Chromium (VI) Disrupting the Soil’s Biochemical Properties

One of the major challenges faced by contemporary agriculture is how to achieve better yields of crops and, consequently, higher biomass, even in unfavorable environmental conditions. This challenge corresponds to the assumptions of sustainable development, wherein it is envisaged that plant biomass should be used on a large scale for heat generation or conversion of biofuels. Keeping pace with observed trends, the following study was conducted in order to determine the effect of Cr(VI) on the net calorific value of Zea mays, to assess the impact of this element on soil enzymatic activity, and to identify the effectiveness of compost and humic acids in alleviating possible negative effects of Cr(VI) toxicity. These aims were pursued by setting up a pot experiment, in which soil either uncontaminated or contaminated with increasing doses of Cr(VI) of 0, 15, 30, 45, and 60 mg Cr kg−1 d.m. was submitted to biostimulation with compost and the preparation HumiAgra, a source of humic acids, and cropped with Zea mays. The plant height, yield, and net calorific value of the aerial parts of maize, as well as its root yield, were determined. Additionally, the activity of seven soil enzymes and the values of the impact indices of compost and HumiAgra relative to the analyzed parameters were determined. It was found that Cr(VI) decreased the amount of energy obtained from the plants by decreasing maize biomass, and additionally by distorting the biochemical balance of the soil. Dehydrogenases, urease, and arylsulfatase proved to be particularly sensitive to this element. It was demonstrated that HumiAgra was more effective than compost in mollifying the adverse effects of Cr(VI) on the activity of soil enzymes and, consequently, on the biomass of Zea mays.

Convective drying of mango stone for use as biomass

Mango stone is an interesting biomass by-product with a considerable net calorific value. Mango production has significantly risen in the last few years, meaning that mango waste has increased as well. However, mango stone has a moisture content of about 60% (wet basis) and it is very important to dry the samples for using them in electrical and thermal energy production. In this paper, the main parameters involved in the mass transfer during drying are determined. Drying was carried out in a convective dryer through a set of experiments based on five drying air temperatures (100 °C, 125 °C, 150 °C, 175 °C and 200 °C) and three air velocities (1 m/s, 2 m/s and 3 m/s). Drying times ranged between 2 and 23 h. The drying rate was calculated from the Gaussian model whose values ranged from 1.5·10−6 to 6.3·10−4 s−1. Effective diffusivity was obtained as an overall parameter in the mass diffusion for each test. These values were found between 0.71·10−9 and 13.6·10−9 m2/s. The activation energy was calculated from the Arrhenius law for each test, made at different air velocities. These values were 36.7, 32.2 and 32.1 kJ/mol for 1, 2 and 3 m/s, respectively. This study provides information for future works on design, optimization and numerical simulation models in convective dryers for standard mango stone pieces according to industrial drying conditions.

The Impact of Nutshell Biochar on the Environment as an Alternative Fuel or as a Soil Amendment

Walnut, pistachio, and peanut nutshells were treated by pyrolysis to biochar and analyzed for their possible usage as fuels or soil fertilizers. All the samples were pyrolyzed to five different temperatures, i.e., 250 °C, 300 °C, 350 °C, 450 °C, and 550 °C. Proximate and elemental analyses were carried out for all the samples, as well as calorific value and stoichiometric analysis. For sample usage as a soil amendment, phytotoxicity testing was performed and the content of phenolics, flavonoids, tannin, juglone, and antioxidant activity were determined. To characterize the chemical composition of walnut, pistachio, and peanut shells, lignin, cellulose, holocellulose, hemicellulose, and extractives were determined. As a result, it was found that walnut shells and pistachio shells are best pyrolyzed at the temperature of 300 °C and peanut shells at the temperature of 550 °C for their use as alternative fuels. The highest measured net calorific value was in pistachio shells, which were biochar pyrolyzed at 550 °C, of 31.35 MJ kg-1. On the other hand, walnut biochar pyrolyzed at 550 °C had the highest ash share of 10.12% wt. For their use as soil fertilizers, peanut shells were the most suitable when pyrolyzed at 300 °C, walnut shells at 300 and 350 °C, and pistachio shells at 350 °C.

Evaluating the Potential of Renewable Energy Sources in a Full-Scale Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Wastewater in Ghana

Wastewater management remains a major challenge in developing countries due to the lack of adequate infrastructure, making the need for economically viable and efficient technologies that can be sustained by emerging economies imperative. The upflow anaerobic sludge blanket (UASB) reactor represents an efficient and low-cost technology that produces by-products from which valuable resources can be recovered. This study assessed the energy recovery potential in the form of electricity from biogas and sludge by-products produced by a full-scale UASB reactor. Biogas production rate and composition were monitored to determine the biogas energy recovery potential. Dehydrated sludge from sludge drying beds was likewise quantified and characterised for its elemental composition, immediate composition, gross calorific value and net calorific value to estimate sludge energy recovery potential. The average daily biogas production was found to be 611 ± 275 Nm3/d, with 65% methane in the biogas output. Average sludge dry matter production was determined to be 358.24 TS kg/d. The net energy recovery potential was estimated to be 534.1 MWh/yr, 36% more than the yearly energy demand (392.7 MWh/yr) of the entire plant. Conservative energy recovery at a UASB-based municipal wastewater treatment facility could serve as a self-supply energy option to support its operations.

Valorization of Sugarcane Bagasse for Hydrogen-Rich Gas Production using Thermodynamic Modeling Approach

Hydrothermal gasification also known as supercritical water gasification (SWG) has been considered a promising approach for converting wet biomass such as sugarcane bagasse into high-quality syngas. This study presents the thermodynamic modeling of the hydrothermal gasification of sugarcane bagasse using Aspen Plus. The effects of process parameters on the composition and yield of product gases were also investigated. It was found that the effect of temperature and biomass concentration were significant in the production of hydrogen-rich gas, while less impact was observed with pressure. The hydrogen gas (H2) produced with the highest mole fraction (56.70 mol%) and yield (103.26 kmol/kg) was obtained at 750°C and low biomass concentration of 10 wt%, while the lowest yield (1.52 kmol/kg) and mole fraction (2.45 mol%) of H2 were obtained at 450°C and high biomass concentration of 50 wt%. Findings from this study also showed that the highest net calorific value (17.55MJ/kg) was reached at 450˚C and 50 wt% of biomass concentration. This study would help to consolidate research on hydrothermal gasification of sugarcane bagasse and optimization of experimental processes and also serve as an important benchmark in the utilization of biomass as a clean energy source for future projects.

Investigation on Co-combustion characteristics and NOx emissions of coal and municipal sludge in a tangentially fired boiler

Using the current coal-fired power plant to treat sludge with large annual production is an efficient sludge treatment method. Nevertheless, the majority of the previous studies concentrated on sludge co-firing with low blending ratio and moisture content in utility boiler. Further analysis and discussion are necessary regarding the impact of sludge with high blending ratio and high moisture content on co-firing performance as well as the potential interactions between high moisture content sludge and coal during the co-firing process. The simulation results of the verified computational fluid dynamic (CFD) model can be regarded as numerical experiments. In the present research, CFD was used to analyze the co-firing characteristics of municipal sludge and coal in a 600 MW tangentially fired utility boiler. The impacts of sludge moisture content, blending ratio, blending strategy, and secondary air (SA) distribution on co-combustion characteristics and NOx emissions were investigated, and their potential synergistic effects were assessed. The co-firing of coal and sludge has little impact on the furnace outlet temperature while potentially lowering NOx emissions, provided that the net calorific value of the feeding of the mixture of sludge and coal is kept constant. The reduction of sludge moisture content can significantly improve co-combustion performance, but it also facilitates NOx production. Blending sludge from the position of the medium-upper burners can reduce the number of layers needed to burn the sludge in practical coal-fired boiler. Furthermore, the SA distribution has a major impact on the furnace outlet flue gas temperature and NOx content. The shrunk-middle type is the optimum scheme for SA distribution. This study contributes to a deeper knowledge of the actual co-firing of sludge and coal in the utility boiler and provides a possible theoretical foundation for the widespread, clean, and effective use of sludge.

The Preparation of a Carbonaceous Adsorbent via Batch Pyrolysis of Waste Hemp Shives

The study focuses on the two-stage process of the thermal treatment of waste hemp shives aimed at obtaining a carbonaceous adsorbent. In the first stage, pyrolysis was carried out in a retort apparatus, which, at temperatures in the range of 450–850 °C, provided approximately 22.6–29.9% of the solid residue, 31.6–34.0% of the condensate, and 38.5–43.4% of gas with respect to the charge. The organic part of the condensates showed the net calorific value of 30.8–31.3 MJ kg−1, which makes it well suited for energy purposes. In the separated pyrolysis gases, GC-TCD-FID determined only five compounds, namely carbon dioxide, carbon monoxide, hydrogen, methane, and ethane, which together accounted for 98.5–99.8% of the gas volume. The remainder was composed mainly of ethene, propane, and propene. The highest net calorific value (14.7–14.8 MJ m−3) was exhibited by the gas collected in the range of 450–650 °C, which can be advantageously used for energy purposes. Non-activated solid pyrolysis residues had relatively low specific surface areas (BET), with the highest value determined being 294 m2 g−1. Therefore, they were activated by steam in a separate apparatus in the temperature range of 740–900 °C. The activation apparatus operated with a batch reactor of similar design to the pyrolysis retort. The activation increased the specific surface area of the pyrolysis residues up to the maximum of 915 m2 g−1. This study discusses the significant trends in specific surface area and total pore volume caused by a combination of different pyrolysis and activation temperatures. Better results were generally obtained for residues pyrolyzed at lower temperatures and then activated at high temperatures. The structure of the activated products mostly contained pores with a diameter of < 6 nm. Their development was mainly facilitated by the activation temperature of 850 °C, resulting in the relative presence of these pores in the range of 57.9–59.1%. All activated products were also characterized by an increased proportion of 20–80 nm pores, which formed, however, approximately one-third in comparison with the pores < 6 nm. Last but not least, the study also discusses the effect of activation conditions on the process loss of the product.