Increase In Heating Value Research Articles

Biochar production from microalgae cultivation through pyrolysis as a sustainable carbon sequestration and biorefinery approach

Microalgae cultivation and biomass to biochar conversion is a potential approach for global carbon sequestration in microalgal biorefinery. Excessive atmospheric carbon dioxide (CO2) is utilized in microalgal biomass cultivation for biochar production. In the current study, microalgal biomass productivity was determined using different CO2 concentrations for biochar production, and the physicochemical properties of microalgal biochar were characterized to determine its potential applications for carbon sequestration and biorefinery. The indigenous microalga Chlorella vulgaris FSP-E was cultivated in photobioreactors under controlled environment with different CO2 gas concentrations as the sole carbon source. Microalgal biomass pyrolysis was performed thereafter in a fixed-bed reactor to produce biochar and other coproducts. C. vulgaris FSP-E showed a maximum biomass productivity of 0.87 g L−1 day−1. A biochar yield of 26.9% was obtained from pyrolysis under an optimum temperature of 500 °C at a heating rate of 10 °C min−1. C. vulgaris FSP-E biochar showed an alkaline pH value of 8.1 with H/C and O/C atomic ratios beneficial for carbon sequestration and soil application. The potential use of microalgal biochar as an alternative coal was also demonstrated by the increased heating value of 23.42 MJ kg−1. C. vulgaris FSP-E biochar exhibited a surface morphology, thereby suggesting its applicability as a bio-adsorbent. The cultivation of microalgae C. vulgaris FSP-E and the production of its respective biochar is a potential approach as clean technology for carbon sequestration and microalgal biorefinery toward a sustainable environment.

Effect of naphthalene addition to ethanol in distributed combustion

Naphthalene as a fuel additive to ethanol was examined in a swirl combustor with the objective to obtain efficient burning and ultra-low emissions using different heating value fuels. Naphthalene is a polyaromatic compound often regarded as a waste fuel that results in high levels of pollutants emission. The effectiveness of naphthalene as a fuel additive to ethanol on NO and CO emissions and stability was determined. The naphthalene concentration was varied from 0 to 0.4 mol/L in ethanol, corresponding to a heating value increase of 8.8% on a volumetric basis (or 5.7% on mass basis). Emissions data were reported for Colorless Distributed Combustion (CDC) using N2/CO2 dilution, at equivalence ratios (Φ) of 0.9 and 0.7. The data under normal fuel–air combustion conditions also reported, clearly showing the benefits of CDC. NO and CO emission below 1 and 6 ppm, respectively, were achieved under CDC conditions for each of the naphthalene-ethanol fuels examined. The results at both the equivalence ratios showed lower NO emission with increase in naphthalene concentration, which provided higher heating value fuel mixture. The CO emission was also low and remained negligibly unchanged with change in naphthalene concentration and equivalence ratio. The results show the use of naphthalene addition to ethanol for increased heating value fuel with ultra-low emissions and higher stability under distributed combustion conditions.

Effect of Soil on Fast Pyrolysis Products from Pine (Pinus taeda) Biomass

Abstract. Detrital soil contamination during wood harvesting cannot be avoided without a further cleaning step. The objective of the current study was to determine the effect of Piedmont soil on pinewood pyrolysis products. Ash content was varied at 0.56%, 1.16%, 2.77%, 4.40%, 6.87%, 8.35%, and 15.52% by adding soil to woodchips to mimic the highly soil-contaminated biomass that can be found in biorefineries. This study found that bio-oil yield decreased from 47.1% to 26.3% with an increase in ash content from 0.56% to 15.52%. However, the oxygen content of the bio-oil decreased and the carbon content increased, which led to an increase in heating value from 22.5 to 24.9 MJ kg-1. Inorganics in the soil aided in the catalytic cracking and dehydration reactions for bio-oil formation. A slight increase in the total acid number (106 to 117 mg KOH g-1) and water content (20.72% to 24.99%) was observed with more soil inclusion in the pyrolysis. The effect of soil on biochar O/C and H/C ratios was minimal even though the heating value decreased with an increase in soil content. This study showed that soil (4%wt to 7%wt) in the biomass assisted in deoxygenating the bio-oil and lowered the total mass yield while keeping the total energy yield almost constant. Keywords: Fast pyrolysis, Pinewood, Pinus taeda, Soil, Thermochemical conversion.

Evaluation of Biodegradable Waste Quality by Drying for exploring the Possibilities of a Potential Renewable Energy Source in Yangon City, Myanmar

Waste is biomass and it is also a type of renewable energy sources. Biodegradable waste to fuel could become an energy source potential to gain environmental and economic benefits in the years to come. To explore the opportunities of a potential renewable energy source from the biodegradable wastes in Yangon city of Myanmar, the study collected 12 different waste samples from the four districts of Yangon and evaluated the composition of the collected wastes. Then, the study assessed their moisture contents by Halogen Moisture Analyzer and dried 100 grams, 300 grams and 500 grams of waste samples by Binder Laboratory Heating and Drying Oven with fan circulation at 105°C. The study also analyzed the effect of moisture reduction in volume reduction, weight reduction and heating value increase of the biodegradable waste samples after drying. The results showed that 50% of moisture reduction could contribute approximately over 20% of volume reduction, 40% of weight reduction and 200% of heating value increase. Therefore, if drying could be conducted with a renewable source such as solar energy and a waste heat source from industrial sectors, the dried biodegradable wastes with higher heating values could be beneficial in the energy and environment sector of Yangon city. The objective of the study was to evaluate the biodegradable waste quality of Yangon city by drying for a future potential renewable energy source.

Process modeling for torrefaction of birch branches

This work presents a complete biomass torrefaction model for Norwegian birch branches. The model can provide detailed distribution of both the main and by-products from the torrefaction process. Reduction in mass and energy yields as well as increase in heating value of the torrefied biomass with increasing torrefaction temperature are observed. Simulation results show good agreement with available experimental data in the literature. Furthermore, the overall energy consumption and the process energy efficiency can be also estimated, which is essential for process up-scaling. It reveals that drying accounts for 76-81% of the total heat demand. More importantly, the process energy efficiency reduces with increasing temperature thus torrefaction at high temperatures is not advisable. The information obtained from the model is important for industrialization and commercialization of the torrefaction process.

Energy densification of animal waste lignocellulose biomass and raw biomass

The need to reduce carbon emissions has encouraged more research into use of biomass energy in place of coal. Biomass is carbon neutral; its use can therefore lower net emissions. Biomass can be upgraded to a fuel similar to coal by torrefaction. Different biomass have been torrefied but there is limited research in possible use of lignocellulose biomass from animal waste. This study aims to compare extent of energy densification of torrefied cow dung, corn cob and pine wood. They were dried, ground and sieved. Proximate and ultimate analysis was conducted. The samples were then torrefied at 200, 250 and 300 °C at 10 °C/min for 40 min. The resulting biochar were characterized using mass yield, higher heating value, energy yield and density. Biochar obtained at 250 °C were analyzed for elemental composition. Results were compared to Anglo bituminous coal and other torrefied biomass in literature. Corn cob and pine wood reached a maximum of 25.98 MJ/kg and 20.90 MJ/kg in heating value respectively whilst cow dung only increased to a maximum of 18.60 MJ/kg. Increase in heating value for corn cob was attributed to reduction in oxygen due to release of volatiles as well as water. This lowered the O/C ratio thereby densifying the fuel. The O/C and H/C ratio for corncob and wood moved towards that of bituminous coal unlike that of cow dung. Cow dung had a high inorganic composition so its heating value could not be upgraded as much as the other 2 biomass. Its use as a torrefaction raw material was therefore discouraged.

In-depth Study of Fuel Properties of Corn Residue (Cob, Stems/Leaves, and Husks) through the Torrefaction Process

Asian is the largest producer of corn, especially in the plateau areas. In Thailand, each year approximately five million tons of corn are harvested from the field. Its residue, e.g. stems/leaves and husks, are left in the field, whereas empty cobs are processed at the mills as by-product. Nowadays, empty cobs are used as low-grade fuel inefficiently in mills, and stems/leaves and husks are not used as fuel because of their poor fuel quality and its difficult to handle. This study emphasizes the improvement of corn residue, including empty cobs, stems/leaves and husks, for use as high-grade fuel via the torrefaction process. A series of torrefaction experiments was carried out in a laboratory-scale batch -type furnace at the temperature of 250, 300, and 350° C with the retention time of 30, 60, and 90 minutes in a nitrogen atmosphere. As torrefied stems/leaves and husks are brittle, the briquetting process was required. The fuel properties, e.g. heating value, moisture content, volatile matter, ash, and water-absorbability, of the torrefied corn residue were compared with raw residue. From the experimental results, it was clearly seen that the torrefied corn residue yields better fuel quality. The optimum torrefaction condition is at temperature of 300° C and the retention time of 30 minutes, at which the heating value increases from 17,734 to 27,474 kJ/kg for empty cob, 15,570 to 24,135 kJ/kg for stems/leaves, and 16,010 to 23,363 kJ/kg for husks. The increase in heating value results from the decrease in volatile matter from 78.22-87.99 %-wt. to 47.27-53.36 %-wt. and the increase in fixed carbon from 8.71-16.13 %-wt. to 37.87-48.70 %-wt. The density and compression strength of the briquettes of torrefied stems/leaves are higher than briquettes of residue without torrefaction. All of the torrefied corn residue was hydrophobic, which has less ability to absorb water according to the pore structure. The biochar from the corn residual can be used as premium feedstock for heating purposes with high heating value and low smoke.

Effect of torrefaction on physiochemical characteristics and grindability of stem wood, stump and bark

In this work, Norway spruce stem wood, stump and bark were torrefied in a bench scale tubular reactor at 225, 275 and 300°C with two residence times (30 and 60min). Effect of torrefaction on general properties, chemical composition, grindability and microstructure and morphology of biomass samples were studied. An increase in heating value and fixed carbon content of the torrefied biomass was observed for increasing torrefaction temperature and residence time. Chemical compositions of torrefied biomass samples considerably changed with increase of torrefaction severity. For the stem wood and stump, the relative hemicellulose content significantly decreased from respectively 42.3% and 29.8% to less than 1% after torrefaction at 300°C for 60min. The hemicellulose content of untreated bark decreased from 27.5% to 0.14% after torrefaction at the same conditions. Additionally, the cellulose content of the torrefied bark drastically decreased already to half the initial value at a torrefaction temperature of 275°C, with only trace amounts left in the 300°C torrefied products. The grindability of stem wood and stump were substantially improved after torrefaction treatment. The energy required for grinding stem wood and stump torrefied at 225°C decreased to respectively 87 and 70kWh/ton, which are less than 50% of the energy needed for grinding the untreated samples. For raw bark, much less grinding energy is required compared to those for raw stem wood and stump, and torrefaction has minor effects on the grindability of bark. The ground torrefied biomass samples have much smaller particles than those of the untreated ones. SEM analysis results show that particles from ground torrefied samples lose their fibrous structure with decrease of length-to-diameter ratios, compared to untreated biomass samples. It explains the shift in particle size distribution curves towards smaller particles as obtained from the sieving tests.

Ku 대역 고출력 고효율 Radial Combiner에 대한 연구

We have studied a combiner that can withstand high power while minimizing insertion loss in high frequency band. In particularly, because the output power that can be output per unit elements is much lower in the Ku band and above than in the low frequency band , it is necessary to combine many semiconductor elements in order to make a high power SSPA. A planar combiner such as a microstrip, as the number of elements to be combined increases, the insertion loss increases proportionally, resulting in a reduction in the overall system efficiency and an increase heating value also. The planar combiner also have some problems due to the low power handling rate. To improve these problems, we proposed a Cavity Radial Combiner. A Ku band 16-way Cavity Radial Combiner was fabricated and measured. As a result, it was tested 14dB return loss and over 94.5 % output combining efficiency in design band.

1-3-3 低品位炭素資源の改質を伴う自然発火性抑制法の開発(1-3 褐炭、改質,Session 1 石炭・重質油等)

1-3-3 低品位炭素資源の改質を伴う自然発火性抑制法の開発(1-3 褐炭、改質,Session 1 石炭・重質油等)

Assessing biodiesel production from sewage sludge-derived bio-oil

Abstract The undesirable properties of pyrolysis bio-oil such as high fractions of oxygenated and nitrogenated compounds, high viscosity, and high instability, limit its usage for transportation and energy applications. In this work, the upgrading of sludge-derived bio-oil using nickel-modified HZSM-5 catalyst was explored to determine the effects of temperature, ethanol to bio-oil mass ratio and reaction time on sewage sludge-derived (SSD) biodiesel yield and the degrees of denitrogenation and deoxygenation. The SSD biodiesel yield was found to be decreasing when the reaction temperature was increased, while the nitrogen and oxygen removal were both improved. Increased yield and deoxygenation were also observed at higher ethanol amounts, while denitrogenation was enhanced at longer reaction time. The optimum conditions for SSD biodiesel production (temperature – 258.5 °C, ethanol to bio-oil mass ratio – 2.50, reaction time – 3.23 h) were determined using response surface methodology and obtained the following results: 67.2% biodiesel yield, 20.4% degree of denitrogenation, and 33.6% degree of deoxygenation. Catalytically upgrading the bio-oil from sewage sludge into biodiesel resulted in better properties and quality and an increased heating value of 39.97 MJ/kg, generally comparable to commercial biodiesel.

Ultra-low calorific gas combustion in a gradually-varied porous burner with annular heat recirculation

Experimental studies on premixed combustion of ultra low calorific gas (LCG) in an axial and radial gradually-varied porous media burner with annular for heat recirculation were conducted. The effect of firing rate for different heating value of low calorific gas on temperature profiles, flames stability and CO emission was studied. The flame stability limits increased while the CO emission decreased with the increase of heating value of LCG. The flame located near the front of the inner tube at the upper flame stability limit and the corresponding temperature profiles decreased along the flow direction. The flame location moved from the upstream to the downstream with the increase of firing rate, and the corresponding temperature profiles of upper flame stability limits were much uniform than that of lower flame stability limit. The combustion and flow characteristics could be improved by using an annular heat recirculation, and an ultra-low calorific gas of 1.4 MJ/m3 can burn in the present porous burner.

Characterization of cold densified rice straw briquettes and the potential use of sawdust as binder

This study investigated the effect of particle size, pressure and mold diameter on the physical characteristics of rice straw briquettes. The briquettes were prepared utilizing a manually operated piston-press cold densification system and analyzed in terms of initial density, stable density, density ratio, compaction ratio, percentage of volume change, shatter index and energy consumption. Reduction of mold diameter significantly (p<0.05) improved briquettes stable density and reduced compaction pressure requirement. Particles of <2.5mm or 0.1–150mm, pressure≥27.6MPa and mold diameter of ≤51mm should be used to prepare cold densified rice straw briquettes of higher stable density and durability. Interestingly, the briquettes of 0.1–150mm particles showed significantly (p<0.05) higher shatter index of >0.90 even at lower pressure at a cost of stable density. The use of sawdust as binding material at 3:1 and 1:1 mixing ratios increased briquettes stable density>600kg/m3, improved shatter index significantly (p<0.05), increased heating value by 6–7.2%, and reduced ash content from 13.61% to 10.3% and 6.93%, respectively. The energy consumed for briquette preparation accounted 5.6–7.5% and 11.1–13% of the energy which was stored in rice straw briquettes for large and small mold respectively.

Karakteristik Fisik Bahan Bakar Alternatif Campuran Minyak Jarak (CJO)-Minyak Cengkeh

Crude jatropha oil (CJO) is non edible oil that made up of triglycerides. That molecules due to CJO has high viscosity and low evaporation rate. Blending with more viscous and more volatile fuel can reduce it. In this study, CJO was blended with clove oil (CO) in many precentagesi.e. 5%, 10%, 15% and 20%. The basic fuel properties such as viscosity, heating value, and flash point were measured in accordance ASTM D445, ASTM D240, ASTM D93 respectively. The results indicate that the viscosity and the flash point decrease while the heating value increase with an increase of concentration of clove oil. Thoseproperties have been improved because molecular interaction between eugenol and triglyceride makes molecule movement more active than before.

Impact of torrefaction and low-temperature carbonization on the properties of biomass wastes from Arundo donax L. and Phoenix canariensis

The impact of torrefaction and low-temperature carbonization on the properties of biomass wastes from Arundo donax L. and Phoenix canariensis was studied. Thermal treatments were performed at temperatures from 200°C to 350°C during 15 to 90min and temperature was the parameter that more influenced mass and energy yields as well as biochar composition. Torrefaction reduced moisture, volatile matter, O/C and H/C ratios of the biomass, while increasing heating value, ash content and fixed carbon. For torrefaction at 250°C or higher temperatures grindability of the biochars was significantly improved. The low volatile matter contents and high ash contents of these biochars restricts their use as solid fuels but they can be valorized otherwise. Raw biomasses and the biochars torrefied at 200°C could remove methylene blue from an aqueous solution, in fast adsorption test with a contact time of only 3s, with efficiencies higher than 50%.

Pyrolysis of municipal solid waste in a fluidized bed for producing valuable pyrolytic oils

In order to recover valuable pyrolytic oils, mixed municipal solid waste was pyrolyzed in a fluidized bed reactor. Results showed that liquid products yielded among 38.4–56.5 wt% and separated into water-soluble phases and organic phases. Moisture was concentrated in the water-soluble phases (39.4–57.3 wt%), making them low in carbon content and heating value. On the other hand, the higher carbon content and lower oxygen content of organic phases make their heating value (27.5–32.1 MJ/kg) and quality higher than bio-oils. Water-soluble phases mainly included acids, carboxylics, phenols, and sugars, which could be used as chemical feedstocks and substantial fuel. Organic phases mostly contained aromatics and phenols and could be used as fossil fuels directly or as chemical materials. Heavy metals of Cd and Pb were proved to be poor in both water-soluble phases and organic phases. As for Zn, it was found to be higher in the water-soluble phases at 450 and 550 °C with quartz sand as bed material than that in crude oils. However, Zn content in organic phases was comparable to crude oils. High-aluminum bauxite and attapulgite as bed materials increased heating value of water-soluble phases and organic phases respectively, and both performed well in reducing the Zn content of water-soluble phases. This work proved that it was an operative way to produce valuable pyrolytic oils by pyrolysis of mixed municipal solid waste.

Modeling of biofuel pellets torrefaction in a realistic geometry

Low temperature pyrolysis also known as torrefaction is considered as a promising pretreatment technology for conversion of biomass into a solid biofuel with enhanced properties in terms of lower moisture and volatile matter content, hydrophobicity and increased heating value. A thermal treatment leads to a non-uniform temperature field and chemical reactions proceeding unevenly within the pellets. However the temperature is assumed to be uniform in the pellets in the majority of models. Here we report on the model of single pellet biomass torrefaction, taking into account the heat transfer and chemical kinetics in the realistic geometry. The evolution of temperature and material density in the non-stationary thermo-chemical process is described by the system of non-linear partial differential equations. The model describing the high-temperature drying of biomass pellet was also introduced. The importance of boundary effects in realistic simulations of biomass pellets torrefaction is underlined in this work.

Comparison of liquid and vapor hydrothermal carbonization of corn husk for the use as a solid fuel

The effect of the phase during the hydrothermal carbonization (HTC) of corn husks was studied to determine whether liquid water or water vapor was the more suitable reaction medium, as well as if the HTC process could produce a solid fuel (hydrochar) from green corn husks that was comparable to coal. Using liquid water for the HTC process produced a hydrochar with an increased heating value (27.66MJkg−1) compared to using water vapor (25.46MJkg−1). HTC using liquid water removed 90% of the potassium contained in raw corn husk, whereas the water vapor HTC treatment removed 58%. The liquid water treated hydrochar contained a 29% decrease in ash content compared to the water vapor hydrochar. Using a TGA-FTIR analysis the liquid treated hydrochar demonstrated a more coal-like combustion in terms of mass loss and heat production, compared to the vapor treated hydrochar.

Torrefaction of biomass stalk and its effect on the yield and quality of pyrolysis products

Torrefaction is a promising pretreatment technology for biomass and its pyrolysis products upgrading. In this study, the effect of torrefaction temperature (220, 250 and 280°C) on the fuel properties of cotton stalk was investigated. And then pyrolysis experiments of torrefied cotton stalk were performed using a fixed-bed pyrolysis reactor. The effect of torrefaction on the yield and quality of pyrolysis products was also discussed. The results show that after torrefaction, the grinding performance and hydrophobicity of cotton stalk are improved, and the number of functional groups containing oxygen is decreased. Compared with the dried cotton stalk, oxygen content of torrefied cotton stalk reduce greatly while carbon content and heating value increase. The pyrolysis results show that the yield of bio-oil decreases, while the yield of biochar rapidly increases with increased torrefaction temperature. Torrefaction has little effect on the chemical composition of biochar. However, it has important effect on the quality of non-condensable gas and bio-oil. It enhances CH4 and H2 formation and increases the heating value of non-condensable gas. For bio-oil, it reduces acids but increases phenols content. In addition, the water content of bio-oil deceased obviously, leading to a noticeable increase in the heating value of bio-oil.

Solid state co-fermentation as pretreatment of lignocellulosic palm empty fruit bunch for organic acid recovery and fiber property improvement

Batch co-fermentation of lignocellulosic fiber from oil palm empty fruit bunch (EFB), and pig manure (PM) was carried out in anaerobic leach bed reactors under intermittent flushing mode to improve organic acid production and fiber fuel property. Higher PM addition (%PM), long fermentation time (FT), and long leachate flushing interval (FI) showed positive impacts on hydrolysis yield and acidification yield leading to a higher total volatile fatty acid production. Their relationships were described using multivariate models through three-dimensional response surface plots. Volatile solids release from the EFB fiber after 60-day treatment improved by 6.9 times when %PM and FI increased from 0% and 12 h to 50% and 48 h, respectively. Mild acids produced were able to remove as high as 56.9% of hemicellulose and leach 83.5 ± 4.0% of potassium (K) off the fiber. This also resulted in the increased heating value and lowered K content that could minimize slag formation when used in combustion. Addition of PM also supplemented plant nutrients to the EFB digestate. This study demonstrated that co-fermentation could be one of the pretreatment methods to recover valuable products from EFB and help ease its subsequent transformations.