Biomass Drying Research Articles

Production of lipids from microalgae Spirulina sp.: Influence of drying, cell disruption and extraction methods

The pretreatment operations (drying, cell disruption and oil extraction) of microalgae biomass to the lipids extraction are important steps to the product quality and production cost. In this study, the lipids from Spirulina were obtained by different methods of biomass drying (tray and spouted bed), cell disruption (microwave, autoclaving and milling) and solvent extraction (hot and cold). The average content of lipids extracted by the cold method, using polar solvents, was of 5.8 ± 0.6 g 100 g−1. The spouted bed drying with cell disruption by milling achieved the best performance with the hot extraction method. Under these conditions, the TBA value was of 0.57 ± 0.09 mgMDA kg−1. FT-IR spectra and thermal analysis indicated that the hot extraction resulted in a more purified lipid extract than the cold extraction. The Brimberg model showed the best fit to the lipid extraction kinetics and the activation energy in the best conditions was of 6.11 ± 1.41 kJ mol−1.

Microalgae cofiring in coal power plants: Innovative system layout and energy analysis

This paper investigates the smart integration of a 500 ha microalgae culturing facility with a large scale coal power plant (758.6 MWe): a fraction of the CO2 contained in the coal plant flue gases is used for the algal cultivation, a fraction of the low-temperature flue gas heat available is used for the biomass drying, finally the produced biomass is co-fired in the coal plant. The produced algal biomass represents approximately 1% of the boiler heat input.Through the solution of energy and mass balances of each plant component, the overall system performances in terms of net energy ratio (NER) and CO2 emissions reduction are obtained. The computed NER (1.92) guarantees an energy harvest almost twice the energetic cost needed to produce the microalgal fuel. The total CO2 emissions are reduced of approximately 0.48%, identifying microalgae cofiring as a solution able to reduce the environmental impact of electricity generation. A simplified economic analysis has allowed an estimate of the algal system investment cost (about 235 k€ ha−1) and of the levelized cost of electricity (LCOE) (554.4 € MWh−1). A set of sensitivity analyses is finally performed to investigate the influence of the initial hypotheses on the results.

Evaluation of sorghum hybrids for biomass production in central Italy

Two field experiments were carried out in 2005 and 2006 in central Italy in order to evaluate the biomass production and quality in eight sorghum hybrids, to define their biomass partitioning among leaves, panicles and stems and to identify which were the most adapted at early harvest. Sorghum showed a high potential in terms of biomass production in central Italy, with biomass dry yield of 25 t ha−1 in average, adopting low input in terms of irrigation and fertilization. The most productive hybrids were H133 (26.3 t ha−1) and H952 (25.9 t ha−1) among the biomass hybrids and SS506 (27.3 t ha−1) among the forage hybrids. The trends of dry weight and moisture content of biomass during the different hybrids growth cycles allowed to estimate the biomass production of each hybrids, hypothesizing an early harvest at 20 August with in-field drying of biomass. Early harvest reduced dry weight of biomass from 4.6% to 21.7%, depending of hybrids; SS506 and H128 showed to be the most adapted at early harvest. HHV and LHV of biomass showed average values higher in biomass hybrids (18.4 and 17.5 MJ kg−1 d.m.) than in forage hybrids (17.7 and 16.8 MJ kg−1 d.m.); while, ash content average values were lower in biomass hybrids (6.8% d.m.) than in forage hybrids (7.7% d.m.). The highest values of leaves + panicles partitioning in the forage hybrids increased ash content, reducing the quality of their biomass for thermal utilization; the biomass hybrids should be therefore preferable.

Fuzzy analytic hierarchy process (FAHP) for multi-criteria selection of microalgae harvesting and drying processes

Microalgae are considered to be a promising source of biomass compared with first and second generation feedstocks. However, the high energy requirement for harvesting and drying of the algal biomass poses challenge to commercialization due to implications on both carbon footprint (CF) and cost. In this work, we propose a systematic methodology for the multi-criteria evaluation of alternatives for the harvesting and drying processes. A fuzzy analytic hierarchy process (FAHP) approach is used, where the pairwise comparison of the multiple criteria and alternatives were done to prioritize the best harvesting and drying method within the fuzzy bounds of the value judgment that satisfies the consistency index. FAHP also allows the degree of confidence of the expert to be quantified. A case study of four alternatives each for the harvesting and drying process is used to demonstrate the process. Technology capability, cost and environmental impacts (comprised CF, land footprint and water footprint) are identified as the selection criteria for harvesting and drying process, respectively. Results show that flotation is the best alternative for harvesting process, while sun drying is the best among the drying alternatives. Sensitivity analysis is used to give insights on the robustness of the decision model and enables the understanding of critical criteria that would significantly influence the ranking of the alternatives. The proposed FAHP approach therefore can effectively deal with the uncertainty of judgment in the decision-making process in the evaluation of microalgae harvesting and drying processes.

Microwave drying characteristics of microalgae (Chlorella vulgaris) for biofuel production

Algal biofuels serve as a promising alternative energy source for liquid fuels. However, one of the bottlenecks in the conversion of microalgae to biofuels is the drying process. A moisture content of at most 10 % is desired for algal biomass prior to oil extraction to maximise biofuel yield. Conventional means of drying results to longer drying time and uneven drying of algal biomass. This study investigated the drying characteristics of microwave for microalgae (Chlorella vulgaris). Three microwave intensity levels (300, 600, and 900 W) were considered to dry 10, 20, and 30 of algal mass. Page model gave a better fit on the moisture ratio with time of microwave drying than the exponential model. Furthermore, the specific energy requirement was computed, and a relationship was found between moisture ratio with power and mass. Fourier transform infrared spectroscopy results showed significant reduction of infrared signal intensities of the functional groups present in the algae after drying at higher microwave power level. It was concluded that the 20 W/g microwave drying setting gave a lower specific energy requirement with good quality of remaining high lipid content qualitatively. Furthermore, it was recommended to use gas chromatography mass spectroscopy to further quantify the algal lipids and other functional groups.

Algal biomass and diesel emulsions: An alternative approach for utilizing the energy content of microalgal biomass in diesel engines

The use of algal biomass for the production of sustainable biofuels has attracted significant interest due to the fast reproduction rates and high lipid content of many microalgal species. However, existing methods of extracting algal cellular lipids are complex and expensive, with regards to both energy input and economic costs. This work explores an alternative method of utilizing the energy content of microalgae through the preparation of wet algal biomass slurry/fossil diesel emulsions containing up to 6.6% wt/wt algae biomass, using a specific surfactant combination, for direct injection diesel engine combustion of microalgae without prior biomass drying or lipid extraction.A high lipid containing green microalgae, Chlorella sorokiniana, was used to produce algal biomass for the study. The preparation of wet algal slurry/diesel emulsions from algae grown under standard conditions, and also those under conditions intended to increase cellular lipid content or growth rates was investigated, and in all cases a surfactant pack of Span80, CTAB and butanol was found to produce a stable emulsion. A correlation between the engine work produced during combustion of the emulsions in a modern direct injection compression ignition and the lower heating value of the wet slurry emulsions was found, with no evidence of individual algae cells persisting to the engine exhaust. Engine exhaust emissions of nitrogen oxides (NOx) and particulate matter were lower for all of the wet algal slurry/diesel emulsions relative to a reference fossil diesel tested under similar conditions, while in the case of the emulsion prepared from algal biomass to which a flocculating agent had been added, emissions of carbon monoxide (CO) were found to increase significantly.

Technoeconomic analysis of continuous biodrying process in conjunction with gasification process at pulp and paper mills

ABSTRACTIn the biorefinery context, thermochemical processes have attracted a significant attention in recent years. Such processes generally consist of three main steps: pretreatment, thermochemical treatment, and post-treatment. In these developing processes, drying and feeding of biomass feedstock remain a significant and costly challenge. The moisture content of biomass feedstock must be decreased to an economic level at pretreatment step otherwise it has to have a detrimental effect on the process efficiency and quality of products. This work addresses the drying of biomass feedstock using novel but practical technology, called biodrying. It is a green technology that offers an opportunity for biomass drying without using an external heat source or fossil fuels, since drying energy is generated through exothermic microbial activity in the biomass that enhances the drying rate. This paper focuses on technoeconomic assessment of continuous biodrying technology integrated to gasification-based biorefinery and investigates the conditions that make such novel technology viable in conjunction with gasification process. Fixed capital investment and operating cost of different biodrying scenarios were estimated as M$4.3–21 and M$0.85/y–3.6/y, respectively, and potential benefits (sludge landfilling cost, energy savings, and carbon credit) from integration of the continuous biodrying system in gasification process implemented in pulp and paper mill were calculated, and ultimately economic performances of the scenarios were assessed. Furthermore, the viable biodrying conditions were specified as 4-day residence time and the major viability risk was found to be bound moisture of biomass.

Comprehensive techno-economic analysis of wastewater-based algal biofuel production: A case study

Combining algae cultivation and wastewater treatment for biofuel production is considered the feasible way for resource utilization. An updated comprehensive techno-economic analysis method that integrates resources availability into techno-economic analysis was employed to evaluate the wastewater-based algal biofuel production with the consideration of wastewater treatment improvement, greenhouse gases emissions, biofuel production costs, and coproduct utilization. An innovative approach consisting of microalgae cultivation on centrate wastewater, microalgae harvest through flocculation, solar drying of biomass, pyrolysis of biomass to bio-oil, and utilization of co-products, was analyzed and shown to yield profound positive results in comparison with others. The estimated break even selling price of biofuel ($2.23/gallon) is very close to the acceptable level. The approach would have better overall benefits and the internal rate of return would increase up to 18.7% if three critical components, namely cultivation, harvest, and downstream conversion could achieve breakthroughs.

Performance of an effectively integrated biomass multi-stage gasification system and a steel industry heat treatment furnace

The challenges of replacing fossil fuel with renewable energy in steel industry furnaces include not only reducing CO2 emissions but also increasing the system energy efficiency. In this work, a multi-stage gasification system is chosen for the integration with a heat treatment furnace in the steel powder industry to recover different rank/temperature waste heat back to the biomass gasification system, resulting higher system energy efficiency.A system model based on Aspen Plus was developed for the proposed integrated system considering all steps, including biomass drying, pyrolysis, gasification and the combustion of syngas in the furnace. Both low temperature (up to 400°C) and high temperature (up to 700°C) heat recovery possibilities were analysed in terms of energy efficiency by optimizing the biomass pretreatment temperature.The required process conditions of the furnace can be achieved by using syngas. No major changes to the furnace, combustion technology or flue gas handling system are necessary for this fuel switching. Only a slight revamp of the burner system and a new waste heat recovery system from the flue gases are required.Both the furnace efficiency and gasifier system efficiency are improved by integration with the waste heat recovery. The heat recovery from the hot furnace flue gas for biomass drying and steam superheating is the most promising option from an energy efficiency point of view. This option recovers two thirds of the available waste heat, according to the pinch analysis performed. Generally, depending on the extent of flue gas heat recovery, the system can sustain up to 65% feedstock moisture content at the highest pyrolysis temperature studied.

Quantification based on dimensionless dendrometry and drying of residual biomass from the pruning of orange trees in Bolivar province (Ecuador)

AbstractIn this work, a new approach to evaluating the amount of residual biomass obtained from orange trees based on normalization of variables is proposed for Bolivar province, Ecuador. So far, several models to quantify the amount of residues obtained from pruning have been proposed from dendrometric and cultivation variables, such as height, crown diameter, stem diameter, area per plant, yield, and age. However, the high dispersion of their values, caused by uncontrolled conditions, gave models with a low‐medium coefficient of determination. The aim of this work has been to develop several models in order to predict wet available biomass using dimensionless dendrometric parameters from height, diameter and height of the crown, and the stem height. They improved the coefficients of determination to 0.94 for the global mathematical model. The drying process of pruned materials has also been analyzed. Residual biomass with 50% initial moisture content was dried outdoors on cement and agricultural soil until it reached constant moisture content. Models used to describe the drying process of agricultural products were employed to fit the observed data of the drying process of orange tree chips. Among the tested models, the Midili and Page models were those that best fitted the observed data in the drying process. The information offered by these equations is of vital importance because they help estimate the amount of biomass that is generated in a given area, and the implementation geographic information system (GIS) maps. In addition, logistic algorithms can be applied. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd

Bed Agglomeration during the Drying of Mallee Leaf in Fluidized Bed

Drying of mallee leaf was carried out in a laboratory fluidized-bed reactor in air at 120–250 °C for 15 min. Surprisingly, bed agglomeration takes place even during drying. The bed agglomeration yield (YAP), which is the mass of bed agglomerates expressed as the percentage of the total mass of all samples collected from the bed, increases from 5.2% at 120 °C to 17.3% at 250 °C. Similar to those that took place during biomass pyrolysis, the interaction between biomass and sand bed particles during biomass drying can also be quantified using sand loading (SL), which is the mass of sand sticking to the biomass particles in the bed (to form bed agglomerates) normalized to the total mass of biomass fed. SL during biomass drying also follows a similar generic equation (SL = KR-0.5) as previously reported for biomass pyrolysis for 15 min, where K is analogous to the Arrhenius equation and R is the biomass feed to sand ratio (i.e., the ratio between the total accumulated mass of biomass fed and the total mass of ...

Computer-aided process engineering for environmental efficiency: Industrial drying of biomass

ABSTRACTThe idea of taking into account environmental impact criteria in the process design becomes a necessity for both the industry and governments, due to increased binding regulations. Moreover, to address the issue of integrating sustainable processes, environmental impact must be weighed and balanced against other concerns, such as economic performance, product quality, and long-term sustainability. Therefore, this study introduces a methodology for environmental impact minimization and optimization of multiple conflicting criteria. A general eco-design method for biomass drying process is proposed. The main target is to develop an assessment computer-aided process engineering tool that compares environmental impacts of different operating conditions and fuel types to support decision-makers for an improved compliance to environmental criterion and sustainability.

The Use of High Moisture Sewage Sludge In The Chp Unit Integrated With Biomass Drying And Gasification

Abstract The paper presents the evaluation of the possibility of the use of a biomass with high moisture content in a cogeneration plant with gas piston engine. The dried sewage sludge-derived syngas is used as a fuel. Sewage sludge are characterized by about 70 wt% of moisture content after the dewatering process. The drying process which is applied as the next step requires great amount of energy. For this reason the thermal integration of the drying process with a piston engine which produce a significant amount of waste heat is proposed. The legal situation of the sewage sludge treatment is briefly explained. The thermodynamic analysis of the cogeneration plant based on the gas piston engine integrated with drying and gasification units was conducted. The models of individual components of the system were developed using Engineering Equation Solver and MS Excel software. The maximum moisture of the fuel acceptable for the autonomic operation of the plant is calculated. The influence of the plant’s scale for the acceptable moisture content in the biomass is studied. The analyzes revealed, that the waste heat from the engine is not sufficient for the drying unit. The operation of cogeneration plant requires an additional source of energy or drying the sewage sludge in an independent installation to moisture content about 50-55%.

Three-dimensional full-loop simulation of a dual fluidized-bed biomass gasifier

A three-dimensional CFD model was developed to simulate the full-loop of a dual fluidized-bed biomass gasification system consisting of a gasifier, a combustor, a cyclone separator, and a loop-seal. This full-loop simulation includes the chemical kinetic modeling of biomass drying and pyrolysis, heterogeneous char reactions, and homogeneous gas-phase reactions. In the model, the gas phase is described using Large Eddy Simulation (LES) and the particle phase is described with the Multiphase Particle-In-Cell (MP-PIC) method. The simulation was performed using the GPU-accelerated computing and the simulation results were compared with the gas composition and temperature measurements from a pilot-scale biomass gasification power plant (1MWth, 6tonsbiomass/day). The independence of the accuracy of the model on mesh resolution and computational particle number was determined. The impacts of the particle size distributions (PSD) and drag models on the reactive flows were also investigated.

Fuels from oils and fats: Recent developments and perspectives

Fats and oils continue to be the main feedstock for alternative transport fuels, especially for FAME (biodiesel) production. Nevertheless, hydrotreated vegetable oils (HVO), which are mixtures of alkanes, are also established as a commercial fuel. This review describes recent developments in FAME and HVO production and utilization, including microbial oil use. However, the use of unmodified plant oil as fuel or their corresponding engine and emission tests are not discussed. Recent developed catalysts are described for FAME production, including heterogeneous catalysts, such as super acids, ion‐exchange resins, and other green catalysts produced from biomass. Bio‐catalytic approaches using soluble or immobilized enzymes are at the early commercialization stage. Since HVO production technology is based mainly on current mineral oil industry processing methods, the scientific literature is not as extensive as that of FAME production. The main reaction routes of HVO are a combination of hydrogenation, decarboxylation, decarbonylation, hydroisomerization, and cracking under high pressure and temperatures, using supported and unsupported heterogeneous metal catalysts. Recent reports have highlighted the potential use of non‐food oils, such as microalgae lipids, but industrial significant progress has not occurred, leading to some disillusionment with this approach. Therefore, a clear strategy should be developed for upstream and downstream processes with parallel evaluation of life cycle assessment (LCA). In addition, energy intensive steps of biomass drying and solvent extraction should be avoided by using intelligent technologies, such as in situ processing of wet biomass.Biodiesel and hydrotreated vegetable oils today are the most important alternative diesel fuels in the transport sector. They are produced from the same feedstock, namely oil and fat containing biomass. There has been a shift from food sources to waste material like used cooking oil and animal fat residues as well microbial oils. The latest developments in new feedstock sources, process technologies as well as life cycle assessment and future perspectives are discussed.

Assessment of drying temperature of sugarcane bagasse on sorption of reactive blue 5G dye

We studied the effect of drying temperature of sugarcane bagasse (SB) on sorption of reactive blue 5G (RB5G) dye to test whether SB is a suitable biosorbent for industrial dye removal. First we assessed a set of SB characteristics that could influence the sorption capacity of dried biomass. Kinetic drying of the SB biomass was measured at different drying temperatures, ranging from 30 °C to 80 °C. We used a static gravimetric method to perform equilibrium moisture sorption experiments at drying temperatures of 35–65 °C. In addition, we measured activation energy and net isosteric heat of sorption. SB biomass was characterized as a heterogeneous low-porous and hygroscopic material, with a series of functional groups on its surface. A Lewis thin-layer model best represented the kinetic drying data. In addition, moisture diffusion into the SB biomass was characterized by a rate-controlling step in the drying process. Equilibrium moisture sorption data showed the expected effects of temperature controlling the sorption capacity and a multilayer sorption process. A sigmoidal sorption isotherm data was best represented by a BET model. A high energy demand is required for moisture removal from biomass as suggested by the measured isosteric heat of moisture sorption. Drying temperature did not influence the RB5G adsorption capacity of bagasse, therefore any drying temperature in the range of 30 °C to 80 °C could be used to make this material feasible as an industrial adsorbent.

Techno-economic optimization of the subcritical fluid extraction of oil from Moringa oleifera seeds and subsequent production of a purified sterols fraction

Moringa oleifera tree is found in many tropical areas, and its seed contains up to 40% of good quality edible oil where sterols are also present. In this work a techno-economic study encompassing the coproduction of oil and sterols from M. oleifeira seeds was accomplished using the RSM–COM approach. The oil is produced by subcritical fluid extraction (SFE) while the purification of the associated sterols is accomplished by a patented technology based on distillation.Besides the expenses and investment associated to the SFE, the respective costs and investment for the preliminary drying of biomass and final separation of sterols from bulk oil were also taken into account. Under optimized extraction pressure and time of 350bar and 1.3h, respectively, oil cost was estimated to be 2.76 € kgoil−1 for a SFE unit comprising two extractors of 1m3 capacity. For the coproduction of sterols with 89.4wt.% purity, the minimum costs were 5.60 € kgsterols−1. The overall annual production under optimum conditions was 558.9tons of oil and 1.9tons of sterols, leading the whole integrated process to a net income of 15.87M€year−1. In conclusion the proposed combined process is feasible, and this essay opened the way to exploit M. oleifera by subcritical fluid extraction under the scope of biorefinery premises.

Poplar wood chip storage: Effect of particle size and breathable covering on drying dynamics and biofuel quality

Used as alternative energy sources, solid biofuels have the advantage of simultaneously reduce fossil fuel dependence and mitigate climate changes by reducing greenhouse gas emissions. Biomass storage and handling play a key role for wood fuel quality assessment: in particular, the presence of covering systems influences biomass drying process and factors leading to bulk compaction (e.g. reduced particle size) negatively affect woody biomass preservation till final use. To study the effect that particle size and covering have on biofuel quality, Short Rotation Forestry (SRF) poplar trees were harvested and chipped by means of a Claas Jaguar 890 operating machine equipped with a “GBE-1” header for SRF. The chipping procedure was carried out in March 2009 using on the same header both the standard chipping drum and a special on purpose drum designed by CRA-ING to obtain coarser particles. The chipped biomass was subsequently stored in stacks on a paved surface for a 120 days period to evaluate: i) effect of particle size on uncovered stacks drying dynamic and fuel quality, ii) effect of the presence of non-woven tarp on drying and fuel quality of biomasses standardly chipped with the conventional drum. Coarser stack was found to have a less prompt dehydration and, at the end of the storage period, have less energy and dry matter loss. In case of biomass chipped with the conventional drum, at the end of the storage period the effect of covering ended up in wood fuel with significantly higher heating value.

ENERGY ANALYSIS OF LIPID EXTRACTION OF Scenedesmus sp. PRODUCED IN PILOT SCALE

he production of biodiesel from lipids extracted from microalgae biomass is a promising approach to biofuels. However, this approach is still not commercialized because of the high costs of processes associated with, for example, time consumption and / or biomass drying with intense energy usage. However, it was not possible to show extraction methods among the lipids existing in the literature, which could be applied specifically to the extraction of lipids from the microalgae Scenedesmus sp. from the large-scale wet biomass, which is the current challenge faced by the Center for Research and Development of Sustainable Energy Auto (NPDEAS). Therefore, in this study, the possibility of avoiding the drying process, and extracting lipids directly from humid biomass, using the saponification method, was tested and compared with conventional Bligh and Dyer extraction (B & D). This study introduced the cultivation of microalgae Scenedesmus sp. compact tubular photobioreactors 12 m3 in area 10 m2 (8 x 5 x 2 m). The classical method of lipid extraction from microalgae - B & D - brings many pigments and polar lipids that exist in the biomass and the conversion rate was only 65-66%, whereas the recovery of fatty material in the wet biomass by the saponification method showed high conversion rate (90-95%). Therefore, the saponification process showed a high recovery of fatty acids that can be easily converted into biodiesel by esterification, and it was shown that the stage of drying the biomass can be removed without losing the fatty acids. In relation to the energy usage in the process, it was shown that drying the biomass for extraction of fatty acids uses more energy than that produced in the final product, biodiesel, showing that the removal of fatty acids of the wet biomass is of strategic importance to the viability of microalgae biodiesel.

Simulation study of improved biomass drying efficiency for biomass gasification plants by integration of the water gas shift section in the drying process

This paper examines thermochemical biomass conversion plants that produce synthesis gas that can be converted into synthetic fuels. Biomass requires forced drying before torrefaction or gasification to increase the heating value of the feed, an energy consuming step that weighs heavy in the energy balance of the plant. This paper shows that decreasing the humidity of the admitted drying air greatly improves the efficiency of the biomass drying. It is possible to reduce the humidity of the air by passing the air on a water adsorbent solid such as activated alumina. The alumina loaded with water can then be regenerated with waste heat, but more efficiently by using synthesis gas and convert the adsorbed water to hydrogen in the water gas shift section. The energy saved in the improved drying step amounts to 2–8% of the total fuel consumption of the plant, depending on the ambient conditions.