Biomass Drying Research Articles

H2-Rich Gas Production from Gasification of Oily Sludge via Supercritical Water Technology: Synergy Effect of KOH, K2CO3, and Reaction Parameters

Yielding H2 as a sustainable gaseous fuel from oily sludge is of critical importance in mitigating the environmental effects linked with the usage of conventional fossil fuels. The deficiency in the drying of biomass has ensued to the exploration of supercritical water gasification (SCWG) as an effective method for harvesting H2-rich gas. This study utilized a combination of two alkali catalysts (KOH and K2CO3) in supercritical water to generate a H2-rich gas from a conventional oily sludge. The Box-Behnken design was utilized to assess the impact of different operational variables, including temperature (400-600°C), feed concentration (FC) (between 5 and 25 wt.%), residence time (RT) (15-45 min), and catalyst to feed mass ratios (FMR) (0-0.50). The maximum production of H2 at 3.22 mmolg-feed-1 was achieved under optimal conditions of 600°C, 32.76 min, and a KOH to FMR of 0.45 and K2CO3 to FMR of 0.28.

Systematic solvent selection enables the fractionation of wet microalgal biomass

Wet microalgal biomass was recently proposed as a feedstock to circumvent the energy-intensive drying step in biorefineries. However, solvents commonly applied to extract valuable target compounds from dried biomass are usually less effective when applied on wet biomass. In the present study, we investigated the potential of systematic solvent selection to increase pigment and lipid yields for the extraction of wet Phaeodactylum tricornutum biomass. The solvent selection was guided by a large-scale computational screening approach. Experiments revealed, that 2-butanol – a non-toxic, partially water-miscible solvent – extracted 99.4 wt% of lipids and 82.6 wt% of carotenoids from wet biomass. By using only 2-butanol and water as benign solvents, we developed a biorefinery approach that effectively fractionates wet microalgal biomass under ambient conditions into proteins, carbohydrates, carotenoids and lipids without the need for energy-intensive biomass drying.

Ionic Liquids toward Enhanced Carotenoid Extraction from Bacterial Biomass.

Carotenoids are high added-value products primarily known for their intense coloration and high antioxidant activity. They can be extracted from a variety of natural sources, such as plants, animals, microalgae, yeasts, and bacteria. Gordonia alkanivorans strain 1B is a bacterium recognized as a hyper-pigment producer. However, due to its adaptations to its natural habitat, hydrocarbon-contaminated soils, strain 1B is resistant to different organic solvents, making carotenoid extraction through conventional methods more laborious and inefficient. Ionic liquids (ILs) have been abundantly shown to increase carotenoid extraction in plants, microalgae, and yeast; however, there is limited information regarding bacterial carotenoid extraction, especially for the Gordonia genus. Therefore, the main goal of this study was to evaluate the potential of ILs to mediate bacterial carotenoid extraction and develop a method to achieve higher yields with fewer pre-processing steps. In this context, an initial screening was performed with biomass of strain 1B and nineteen different ILs in various conditions, revealing that tributyl(ethyl)phosphonium diethyl phosphate (IL#18), combined with ethyl acetate (EAc) as a co-solvent, presented the highest level of carotenoid extraction. Afterward, to better understand the process and optimize the extraction results, two experimental designs were performed, varying the amounts of IL#18 and EAc used. These allowed the establishment of 50 µL of IL#18 with 1125 µL of EAc, for 400 µL of biomass (cell suspension with about 36 g/L), as the ideal conditions to achieve maximal carotenoid extraction. Compared to the conventional extraction method using DMSO, this novel procedure eliminates the need for biomass drying, reduces extraction temperatures from 50 °C to 22 ± 2 °C, and increases carotenoid extraction by 264%, allowing a near-complete recovery of carotenoids contained in the biomass. These results highlight the great potential of ILs for bacterial carotenoid extraction, increasing the process efficiency, while potentially reducing energy consumption, related costs, and emissions.

Kinetic Models of Wood Biomass Drying in Hot Airflow Systems

Kinetic Models of Wood Biomass Drying in Hot Airflow Systems

Briquette Production from Vineyard Winter Pruning Using Two Different Approaches

Worldwide, different strategies are being developed in order to ensure optimum conditions for the development and growth of economic competitiveness, as well as for increasing the quality of life and environmental protection. All these strategies are closely linked to the development and modernization of systems for producing energy from clean and renewable sources. In this context, the present paper presents the results of research regarding the evaluation of the sustainability of briquette production using biomass resulting from vine winter pruning as the raw material. An analysis of the scientific literature indicates that nearly 8 Mt of biomass would result from the over 7.4 million hectares of vine plantations in the world, biomass that could be valorized through densification in order to produce solid biofuels with a lower calorific value of more than 17 MJ/kg. This study examines the production of briquettes from vineyard winter pruning with consideration of two types of densification technologies: baling and natural drying of the tendrils, and collection, shredding, and artificial drying of the lignocellulose debris. The quality indices and energy consumption and energy efficiency of the briquettes were evaluated to determine their feasibility as an alternative fuel source. When designing the scientific endeavor, the following aspects were considered: defining the aim and objectives of the research; designing the research algorithm; collecting, preparing, and conditioning the biomass; conducting a chemical analysis of the briquettes; and evaluating the energy consumption and energy efficiency for producing the briquettes, taking into account two drying methods (natural and artificial drying). In the meantime, some specific laboratory equipment was designed and built for the artificial drying of biomass, evaluation of mechanical durability, measurement of energy consumption, etc. Analysis of the experimental data has led to the conclusion that the agricultural waste from vine pruning can constitute an important and sustainable source of energy in the form of briquettes that fulfill most of the requirements imposed by international standards.

Solar-biomass and dielectric drying of mace: An investigation on renewable and fourth generation drying technologies

This study aimed to dry mace under solar and microwave assisted convective drying system to assess the quality of end products and the process sustainability. Conventionally, mace is dried under sun and solar drying conditions due to its easiness and economic feasibility. However, owing to the harvest of nutmeg during monsoon season, drying of nutmeg and mace under alternate drying methods is adopted among the farmers and industrialists. Dielectric drying reduced the duration to 41.6 % with enhanced rate of drying. Moisture diffusivity values of solar-biomass and dielectric dried nutmeg mace were 2.30 -8 m2/s and 1.72 × 10-7 m2/s respectively. Instantaneous drying efficiencies under solar and microwave modes were in the range of 26.4 – 33.4 % and 32.5 – 41.2 %, respectively. The values of economic attributes indicated the benefit cost ratio of 2.4 and 1.9 and payback period of 1.6 and 2.1 years respectively, under solar and microwave drying conditions. The sustainability index and environment destruction coefficient was determined to be 1.54 and 1.10 and 1.86 and 2.41 respectively for solar biomass and microwave drying conditions. The exergy efficiency of the solar and microwave assisted drying of mace was observed to be 18.52 and 26.74 %, repectively Techno-economic feasibility studies on solar and dielectric dried nutmeg mace suggested that solar-biomass dehydration is more economically viable than dielectric drying for the industrial scale dried mace production.

Determination of biomass drying speed using neural networks

The difficulty of measuring the drying rate of biomass under hot air convection conditions due to the influence of multiple factors, such as environmental conditions and material properties; and the problems associated with the variability of desiccation curves under changing conditions makes the use of mass transfer models based on diffusion and convection generally quite inaccurate. The research proposes the use of neural networks to determine the average drying speed (g removed water in unit of biomass material (kg) in unit time (s)), highlighting its ability to handle complex and variable data, as well as its adaptability and robustness. After 62 iterations, the R2 of the training process reached values of 0.93. Subsequent validation provided an R2 of 0.88. The mean square error was less than 10−3 g dryed water kg−1 biomass s−1. Traditional mass transfer models applied to drying processes were compared with experimental data. It has been proven that the values of the convection coefficient in mass transfer are overestimated when obtained from the Sherwood number. Values of this coefficient applied to wood are 30 times lower due to capillary phenomena and electrostatic forces between the material and the water particles.

Combined refractance window and far infrared radiation drying of Spirulina platensis biomass: Drying behavior, moisture and thermal diffusivity, and biochemical characterization

A 2 mm thin layer of wet Spirulina platensis biomass was dried using two methods: refractance window drying (RW) and combined RW and FIR drying (RWF). The effect of drying temperature (40–60 °C) and proximity to FIR heaters (5 and 10 cm) was evaluated on falling rate drying characteristics. The moisture (Deff) and thermal (α) diffusivity coefficients were obtained in the range 1.728 × 10−8 to 5.289 × 10−9 and 1.322 × 10−8 to 4.169 × 10−9 m2 s−1, respectively (R 2, 0.921–0.984). RW drying at ≥50 °C caused loss of color, phytopigments, and lipid peroxidation. At 40 °C, RW drying led to a long drying period (300.50 ± 3.53 min), poor drying rate (0.039 ± 0.002 g-H2O/min), lowest Deff and α (5.289 × 10−9 and 4.169 × 10−9 m2 s−1), and chlorophyll loss (32.2%). Combined RW and FIR drying at 40 °C and 5 cm proximity (RWF40-5cm) reduced drying time (15.1%), increased drying rate (27.8%), improved α (15%), and Deff (14.9%). RWF40-5cm dried biomass showed excellent retention of color (ΔE = 4.64 ± 1.32), protein (93.8%), γ-linolenic acid (90.1%), chlorophyll (87.9%), and phycocyanin (86.7%) from freeze-dried biomass (FD). Low-temperature RWF40-5cm drying could be a potential alternative to freeze-drying for effective and safe drying of heat-sensitive Spirulina platensis biomass.

Design and development of hybrid solar–biomass drying system: An innovative approach

Design and development of hybrid solar–biomass drying system: An innovative approach

Energy and GHG emissions assessment for biochar-enhanced advanced biofuels value chains

Biochar has an enormous potential to store carbon in the long-term. Differently than BioEnergy Carbon Capture and Storage (BECCS) technologies, biochar incorporates biogenic carbon in a solid form that offers multiple benefits as carbon sink, soil improver or for advanced materials production. The present study proposes an innovative approach, where carbon sequestration through biochar is obtained through the integration of slow pyrolysis with fast pyrolysis in decentralised biorefining systems, and then converted producing drop-in fuels from pyrolysis oil hydrotreating or gasification and Fischer-Tropsch (FT) synthesis. The scope is either to achieve negative GHG emissions assigned to advanced biofuels, or to export the generated carbon credit for the carbon markets (i.e. outside the biofuels carbon intensity). The innovative concept entails process integration and optimisation for the different stages of biomass drying, conversion and upgrading into biofuels in a way to reduce fossil-based inputs, applying a full value chain approach. Methodological choices for the assumptions on life cycle emissions calculation are discussed, evaluating the environmental performances by comparing the new concept to traditional biofuels value chains. Using a tailored lifecycle accounting methodology, this paper demonstrates that high GHG emissions savings can be achieved. The improved scenario shows how the carbon sequestration with biochar further reduces the carbon intensity up to –4.2 gCO2e MJ−1 for pyrolysis oil-based fuels, and to −20.2 gCO2e MJ−1 for FT-based fuels: this demonstrated that carbon negative sustainable biofuels can be obtained. The study demonstrates that an integrated biorefinery of 100 MW capacity can deliver additional 13.3 and 6.8 ktons of CO2e of GHG savings of per year, from drop-in fuels made of hydrotreated pyrolysis oil and FT synthesis, respectively.

Design and Simulation of a Multi-Channel Biomass Hot Air Furnace with an Intelligent Temperature Control System

Timely and effective drying of agricultural products is crucial for ensuring the quality and yield of grains. Biomass drying enhances energy utilization and reduces energy pressure. To this end, a novel multi-channel circulating biomass hot air furnace was designed to provide precise control of the heat source for grain drying, thereby improving the efficiency and quality of the drying process. The combustion process utilizes a multi-channel combined air supply to ensure complete combustion of biomass pellet fuel. During the heat exchange process, heat exchange plates isolate hot and cold areas, discharging combustion exhaust, while ensuring a pure air output. Using rapeseed as the drying subject, a temperature controller based on adaptive fuzzy PID was designed, targeting the biomass hot air furnace’s heat exchange system for modeling and verifying the model with the step response method. Model simulations were conducted in Matlab’s Simulink module using both adaptive fuzzy PID and traditional PID controllers, for a given signal. The settling times for the conventional PID and fuzzy PID were 445 s and 364 s, respectively, with overshoots of 20.1% and 6.3%, showing that the fuzzy PID controller performed better in terms of control performance. The validation tests showed that both control methods could maintain the temperature within ±5 °C. Compared to traditional PID control, the adaptive fuzzy PID control achieved a precision of ±3 °C. At the target temperature of 90 °C, the error was reduced to 3.7%, with a stabilization time of 1014 s. The use of fuzzy PID control exhibited better dynamic response characteristics, meeting the drying needs of rapeseed. This study provides a theoretical basis for the structural design and control system design of biomass hot air furnaces.

Solar biomass hybrid drying and quality evaluation of Eryngium foetidum in an innovative newly developed solar dryer

A novel solar-biomass powered hybrid drying system has been developed for studying the drying kinetics, and quality of long coriander (Eryngium foetidum), a medicinal spice. The experiments were carried out in biomass and hybrid energy modes. The findings of each method were compared with open sun drying. Freshly procured leaves of Eryngium foetidum with initial moisture content of 85.15 % (wet basis) was reduced to 9.5 % (wet basis). The biomass and hybrid drying system took 5 h and 8 h to obtain required final moisture. Non– linear regression method was implemented in this study for determining the drying behaviour of Eryngium foetidum. Seven empirical models were selected for determining the drying behaviour of Eryngium foetidum. Medilli model showed the highest R2 and lowest RMSE, χ2 values for both biomass mode (0.9945, 0.02748, 0.00055) as well as hybrid mode (0.9975, 0.01952, 0.00043) respectively. The overall drying efficiency was found out to be 31 % during hybrid mode and 24.22 % during biomass mode of drying. Quality analysis was performed on the final dried product through colour analysis and microbial testing. The colour retention was found out to be better in hybrid mode compared to biomass mode. Microbial analysis revealed that the total plate counts were within permissible limit. There was no growth of yeast and mould observed in both hybrid and biomass mode.

Optimizing Biomass Pre-Treatment Technologies for BBJP Plants in Indonesia: A Multi-Criteria Decision Making Approach

The challenges of energy consumption and environmental sustainability are pronounced in the dynamic landscape of contemporary industries driven by Industry 4.0 technologies. Indonesia, heavily reliant on fossil fuels, charts a course toward a clean energy future with a National Energy Transition Roadmap for Net Zero Emission by 2060. This transition involves innovative strategies such as biomass co-firing and waste utilization in Solid Recovered Fuel (SRF) plants, known as Bahan Bakar Jumputan Padat (BBJP) plants. To optimize these BBJP plants, this study employs Multi-Criteria Decision Making (MCDM) methodologies, specifically the Analytical Hierarchy Process (AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), to evaluate and select pre-treatment technologies. Criteria include capacity, conversion process, waste type, electricity consumption, operational ease, land requirement, and investment cost. Comparing bio-drying, thermal drying, and mechanical drying, AHP ensures consistent criterion weights, with TOPSIS ranking bio-drying as the most favorable, followed by thermal and mechanical drying. The study acknowledges global waste management challenges and introduces a mobile-modular containerized BBJP/SRF plant model, addressing installation, maintenance, scalability, and adaptability issues. While recognizing challenges, especially in pre-treatment processes, the research emphasizes the need for efficient and cost-effective solutions. Practical implications include enhanced decision-making in biomass drying, identification of technology advantages and disadvantages, and a commitment to address challenges for sustainable implementation. The study contributes to Indonesia's energy transition discourse, advocating the pivotal role of BBJP plants in balancing Industry 4.0 demands and environmental protection, providing insights for stakeholders and decision-makers in advancing sustainable waste-to-energy initiatives.

Effect of Biomass Drying Temperature on The Characteristics of Gas Produced by Fluidized Gasifier Bubbling Reactors

Biomass is an alternative fuel that can be used and one of the technologies to utilize biomass is gasification. This study aims to determine the effect of biomass drying temperature on the characteristics of the gas produced by the Bubbling Fluidized Bed Gasifier Reactor. This research uses 3 variations of drying temperature on biomass fuel, namely 70 ˚C, 90 ˚C, and 110 ˚C. The results showed that the higher the biomass drying temperature, the higher the temperature distribution. The highest temperature distribution is found in fuel with P 110 ˚C with a temperature distribution of 592.266 ˚C and the lowest distribution occurs in fuel with P 70 ˚C with a temperature distribution of 498.64 ˚C.

Life-cycle assessment of microalgae liquid biofuel production in biofilm cultivation system via conversion technologies of transesterification, hydrothermal liquefaction and pyrolysis

Biofilm seems to be an ideal cultivation system for microalgae liquid biofuel conversion technologies due to the advantage of high biomass concentration. However, research on the biofilm cultivation system for microalgae liquid biofuel producing were limited. In this study, a life-cycle assessment was conducted for microalgae liquid biofuel production in this system via three conversion technologies: transesterification, hydrothermal liquefaction and pyrolysis. The result shows that scenario hydrothermal liquefaction seems to be the most feasible technology to produce liquid biofuel in biofilm system because only hydrothermal liquefaction achieved positive energy and environment benefits with a net energy ratio of 0.87 and Greenhouse gas emissions of −39.91 g CO2-eq MJ−1. For transesterification and pyrolysis, the net energy ratio (2.18 and 2.06) were larger than 1, while Greenhouse gas emissions (3.28 and 59.25 g CO2-eq) were greater than 0. This indicated that these scenarios exhibited negative energy and environment benefits due to heavy use of chemicals and high energy consumption during biomass drying process, respectively. Additionally, according to the sensitivity analysis, bio-crude mass yield exhibited a more significant impact on the energy and environment loads for scenario hydrothermal liquefaction than the other factors.

Extraction of neutral lipids and phospholipids from marine biomasses using subcritical and supercritical fluids

Supercritical carbon dioxide (scCO2) and subcritical dimethylether (DME) were used to extract lipids from partially to fully dry marine biomass - whole jack mackerel (WJM), Hoki frames and heads (HFH), and Greenshell mussel meat (GSM). scCO2 gave a lower extraction yield of total lipids from GSM (42%) compared to WFH and HFH (86 - 88% yield) due to the higher concentration of phospholipids present in GSM. DME gave a higher extraction yield of total lipids and phospholipids than scCO2 for all marine biomass types. Phospholipid yield from GSM using DME was dependent on moisture content of the feed marine biomass and decreased with decreasing moisture content. Our results suggested that phospholipid extraction yield can be optimised by partly drying biomass to 30 - 50% moisture prior to extraction. DME extracts contained good levels of omega-3 fatty acids with minimal hydrolytic phospholipid degradation, thus providing a potential processing technology option to recover them from marine biomass.

Improving the energy effectivity of biomass drying for utilisation in energy systems by combining convective and contact drying

The article deals with reducing the energy consumption of biomass drying before combustion in energy plants. The combination of traditionally used convective hot air drying and less applies contact drying is analyzed. To determine the basic drying characteristics, the experiments on a contact dryer and a convective hot air dryer were carried out with wet wood chips. A heat balance model of a system with serial connection of a convective air dryer and a contact dryer was compiled. In the model, the utilization of condensation heat from the waste vapor leaving contact drying to preheat the drying air for convective drying was considered. Based on these results, the system could be optimized to achieve the lowest energy consumption, drying time, and dryer sizing. This solution can significantly improve the energy efficiency of drying moist biomass before combustion from 3.29 and 2.76 MJ per kg of evaporated water for only convective drying and only contact drying, respectively, to 1.48 or 1.33 MJ per kg of evaporated water, depending on the order of the dryers in their connection.

Experimental and techno-economic analysis of solar-assisted heat pump drying of biomass

Drying enhances the attributes of biomass, such as storability and heating value. In regions with low solar radiation, solar drying has demonstrated limited economic viability. Hybrid systems, combining solar drying with a stable heat source such as a heat pump, present an opportunity to improve drying performance and achieve cost savings, especially with time-variable electricity pricing. To quantify this potential, we constructed an experimental drying system in Finland, incorporating an air-source heat pump and solar thermal collectors for drying woody biomass. Experimental work, consisting of 316 h of operation in varied conditions, evaluated the performance of the hybrid drying system. Subsequently, we developed data-driven models to estimate drying rates and power consumption in both hybrid and solar operation modes. Finally, these models were integrated into a techno-economic optimization model to assess the economic feasibility of the concept through hourly simulations. Hybrid drying experiments resulted in a significantly improved average drying rate (33.0 kg/h ± 5.4 kg/h) compared to solar drying (9.0 kg/h ± 3.2 kg/h) with a 45% increase in specific electricity consumption. The experimental work also revealed limited operating flexibility in colder temperatures due to an exponentially increasing preheating time (up to 4.2 h at 0 °C). With techno-economic modelling, the simulations yielded a simple payback time of 7.5 years for a commercial-scale drying system without investment subsidies. Applying an optimized operating strategy, system operation shifted on average from hybrid mode (96–33%) to solar mode (3–36%) and inactive state (1–31%) with an increased electricity price level, highlighting the need for advanced operation planning. Commercial deployment should prioritize use cases with high value increase through drying or obtaining compensation from avoided biogenic CO2 emissions through drying, as these two parameters were shown to have the greatest impact on the investment payback time.

Optimization of the Air Distribution in a Biomass Grate-Fired Furnace

This study utilized a combination of FLIC(1D3.2C) and FLUENT(2021R2) software to optimize the primary air distribution along the grate and the performance of a straw briquette combustion furnace of a 7 MW unit in China used to produce hot air for drying grain. Three air distribution modes, namely front-enhanced, uniform, and rear-enhanced modes, were analyzed to determine their effect on the flue gas components above the grate, the temperature field in the furnace, and the nitrogen oxide concentration at the furnace outlet. The results of the calculations showed that the NOx emissions for the front-enhanced, uniform, and rear-enhanced modes were 133.5 mg/Nm3, 104.4 mg/Nm3, and 76.6 mg/Nm3, respectively. It was found that the rear-enhanced mode can expand the biomass drying, devolatilization, and combustion zone, thus improving the furnace combustion performance and decreasing NOx emissions. These findings can provide useful guidance for optimizing biomass chain-grate-firing furnaces.

Energy and exergy efficiencies analysis of microwave drying of orange pomace biomass

Energy and exergy efficiencies analysis of microwave drying of orange pomace biomass