Thermochemical Conversion Systems Research Articles

Combustion and energy performance of non-commercial Corymbia and Eucalyptus wood for use in cogeneration systems in Brazil

The increased representation of biomass in the Brazilian energy matrix will contribute to reducing dependence on hydroenergy and mitigating negative impacts during increasingly frequent drought periods. However, given the changing climate, it is urgent to classify and select new genotypes for the expansion of energy plantations. The objective of this study was to evaluate the energy performance and combustibility of wood from Eucalyptus and Corymbia trees to support a knowledge-based and efficient use of such woods in thermochemical conversion systems. Eight species of Eucalyptus (Eucalyptus amplifolia, E. longirostrata, E. major, and E. urophylla) and Corymbia (Corymbia citriodora, C. variegata, C. henryi, C. torelliana), which are not generally used for energy purposes, were selected at 6 years of age from experimental plantations in southeastern Brazil. Wood basic density (WBD), ash content (AC), higher heating value (HHV), fuel value index (FVI), ignition (Di), flammability (Ci) and combustion (Si) indexes were determined. The wood of E. urophylla and C. torelliana presented showed the highest and lowest FVI, respectively. Regarding combustion indexes E. longirostrata had a higher combustion index (4.00 ×107 %2/(min2°C3)), flammability (1.49 %min−1/°C2) and ignition (4.39 % min−3) while C. variegata presented the lowest values. The FVI showed correlations with the combustibility of wood. Thus, this index can be used for the rapid and reliable classification of new genetic materials for energy forests in Brazil. E. urophylla and E. longirostrata woods demonstrated better energy performance and combustion indexes, making them the most suitable species for use in cogeneration systems and candidates for the expansion of energetic forests in Brazil.

Efficient Glucose Isomerization to Fructose using Photoregenerable MgSnO3 Catalyst with Cooperative Acid-Base Sites.

The isomerization of glucose to fructose plays a crucial role in the food industry and the production of biomass-derived chemicals in biorefineries. However, the catalyst used in this reaction suffers from low selectivity and catalyst deactivation due to carbon or by-product deposition. In this study, MgSnO3 catalyst, synthesized via a facile two-step process involving hydrothermal treatment and calcination, was used for glucose isomerization to fructose. The catalyst demonstrated outstanding catalytic performance, achieving a fructose equilibrium yield of 29.8 % with a selectivity exceeding 90 % under mild conditions owing to its acid-base interaction. Notably, spent catalysts can be regenerated by photoirradiation to remove surface carbon, thereby avoiding the changes in properties and subsequent loss of activity associated with conventional calcination regeneration method. This novel approach eliminates the energy consumption and potential structural aggregation associated with traditional calcination regeneration methods. The acid-base active sites of the catalyst, along with their corresponding catalytic reaction mechanism and photoregeneration mechanism were investigated. This study presents a demonstration of the comprehensive utilization of catalytic material properties, i. e., acid-base and photocatalytic functionalities, for the development of a green and sustainable biomass thermochemical conversion system.

Artificial intelligence methods for modeling gasification of waste biomass: a review.

Gasification is a highly promising thermochemical process that shows considerable potential for the efficient conversion of waste biomass into syngas. The assessment of the feasibility and comparative advantages of different biomass and waste gasification schemes is contingent upon a multifaceted combination of interrelated criteria. Conventional analytical approaches employed to facilitate decision-making rely on a multitude of inadequately defined parameters. Consequently, substantial efforts have been directed toward enhancing the efficiency and productivity of thermochemical conversion processes. In recent times, artificial intelligence (AI)-based models and algorithms have gained prominence, serving as indispensable tools for expediting these processes and formulating strategies to address the growing demand for energy. Notably, machine learning (ML) and deep learning (DL) have emerged as cutting-edge AI models, demonstrating exceptional effectiveness and profound relevance in the realm of thermochemical conversion systems. This study provides an overview of the machine learning (ML) and deep learning (DL) approaches utilized during gasification and evaluates their benefits and drawbacks. Many industries and applications related to energy conversion systems use AI algorithms. Predicting the output of conversion systems and subjects linked to optimization are two of this science's critical applications. This review sheds light on the burgeoning utility of AI, particularly ML and DL, which have garnered significant attention due to their applications in productivity prediction, process optimization, real-time process monitoring, and control. Furthermore, the integration of hybrid models has become commonplace, primarily owing to their demonstrated success in modeling and optimization tasks. Importantly, the adoption of these algorithms significantly enhances the model's capability to tackle intricate challenges, as DL methodologies have evolved to offer heightened accuracy and reduced susceptibility to errors. Within the scope of this study, an exhaustive exploration of ML and DL techniques and their applications has been conducted, uncovering existing research knowledge gaps. Based on a comprehensive critical analysis, this review offers recommendations for future research directions, accentuating the pivotal findings and conclusions derived from the study.

Physicochemical characterization, thermal analysis and pyrolysis kinetics of lignocellulosic biomasses

This paper compares and evaluates the physicochemical characterization and thermal analysis of different agricultural lignocellulosic biomasses namely: olive pomace (OP), argan shells (AS), date palm seeds (DS) and hydrochar (HC), obtained from the hydrothermal carbonization (HTC) of OP, in order to identify a good potential fuel for thermochemical conversion systems. Several physicochemical and thermal characterization methods were used. The aforementioned biomasses are mainly composed of cellulose, hemicellulose and lignin as shown by the FTIR and XRD analysis. From energy point of view, the hydrochar (HC) has the highest value of the higher heating value (HHV) (27.86 MJ/kg). These results make (HC) a very good candidate for thermochemical energy conversion technologies. Thereafter, thermal analysis (DSC and TGA) was conducted in an inert atmosphere to analyze the thermal behavior of the samples under well-defined thermal conditions. Right after, two kinetics models were used to estimate pyrolysis kinetic parameters (the activation energy (E) and pre-exponential factor (A)) of the four biomasses. Among those are, for example, olive pomace has (E = 200.104 kJ/mol; A = 7.14E + 21 s−1) and (E = 199.053 kJ/mol; A = 3.58E + 21 s−1) according to KAS and FWO models, respectively. Consequently, pyrolysis of (OP) requires less energy to occur, which promotes its energy performances.

Assessment of Rice Husk Biomass Potential for Power Generation in Pakistan

Rice husk is one of the utmost obtainable feedstock for renewable energy production and can contribute to resolving energy scarcity and environmental problems. Appropriate knowledge of the rice husk's physiochemical properties is essential for the approach of thermochemical conversion systems. The present study delivers data on proximate and ultimate analysis and heating values of rice husk collected from different regions of Sindh, Pakistan. Moisture content was found low ranging between 12.76% to 13.50% (Mean 12.98%), higher volatile matter in the range of 55.77% to 62.88% (Mean 61.19%) and ash particles of 14.50% to 16.48% (Mean 15.20%). The lower concentrations of nitrogen, 0.37% to 1.31%, (Mean 0.70%) and sulfur, 0.02% to 0.19%, (Mean 0.11%) environmentally deal with more appropriate fuel properties. The heating value of rice husk ranges varied from 5,276.33 to 6,237.13 Btu/lb (Mean 5,859.87 Btu/lb). The significant values of the rice husk samples indicated that the locally available renewable resources can be transformed into an extensive amount of energy products at a small level from active conversion techniques. Therefore, rice husk can be deliberated as appropriate fuel for energy generation and can be considered as an environmentally friendly and economically feasible fuel that helps to decline harmful pollutions.

Bioenergy potential from crop residue biomass resources in Ethiopia

Using crop statistics (2020–21), publicly accessible data, standard procedures and literature, this study estimates the bioenergy potential of crop biomass residues in all regions of Ethiopia. The assessment considered 44 different types of residues from 30 different crops grown in Ethiopia. The country generates 69 569–105 522 kt y−1 gross crop residue biomass, of which 42 621–72 194 kt y−1 (or 61–68% of gross) are estimated as recoverable for bioenergy production. Amongst all the eleven regions, Oromia produces the highest amount of recoverable crop residue (45%) at region level. Cereals produce the highest recoverable crop residue (80%), followed by fruit crops (8%). Maize (36%) and sorghum (29%) are the two crops that produce the highest recoverable residue amongst all the crops. The estimated 559–1144 PJ y−1 bioenergy potential for Ethiopia from recoverable crop residue varies by region and ranges from 0,15 to 0,37 PJ y−1 (Afar) to 254–521 PJ y−1 (Oromia). Decentralized energy planning using crop residues in Ethiopian regions is expected to benefit from the produced data, which will help the country's overall growth in renewable energy. Biological and thermo-chemical conversion systems that are now in various stages of demonstration, commercialization, development, and research can convert biomass into energy. Performing research and development, establishing a database for local biomass resources, and developing a unified bioenergy unit and policy with all stakeholder's participation and engagement are all critical aspects of Ethiopia's sustainable bioenergy sector. Furthermore, value chain analysis of biomass feedstock, capacity building and awareness creation, and decentralized models development are all important for the country's bioenergy development.

Coal gasification process driven by concentrated solar radiation for carbon neutralization: Reaction and energy characteristics

Solar-driven gasification products for chemical feedstock are one of the effective means to utilize coal in a low-carbon and resourceful way. However, few studies on the reaction and energy characteristics are based on experimental data of concentrated solar coal gasification. This study designed a novel experimental solar radiation gasification thermogravimetric device. An energy model of a solar radiation dish thermochemical conversion system was also developed. Compared to indirect radiation, direct radiation has a 10 % higher carbon conversion rate, an increased energy upgrade factor (up to 0.86), and a 38.5 % increase in energy conversion efficiency. Furthermore, we investigate direct radiation-catalyzed gasification to assess the effects of different types and ratios of catalysts. The results showed that the catalytic effect of K2CO3 was better than that of Na2CO3, which would improve the energy conversion efficiency by 4.8 %. For K2CO3, the efficiency was increased by 14.1 % through increasing the doping ratio from 5 % to 10 %. Meanwhile, this study analyzed the reaction kinetics of direct radiation-catalyzed gasification. Finally, we constructed a solar concentrating radiation dish thermochemical conversion system model based on the experimental data. We found that the system energy efficiency in the direct radiation form was 15.3 % higher than that in the indirect radiation form; besides, adding the catalyst in the direct radiation form increased the energy efficiency by 23.8 %. We also found that the gasifier exergy efficiency in direct radiation catalyst gasification was 29.7 %, and that of indirect radiation gasification was 7.23 %. The monthly solar exergy distribution follows the solar radiation closely. The results guide the chemical process of solar thermal conversion.

Development and Comparison of Thermodynamic Equilibrium and Kinetic Approaches for Biomass Pyrolysis Modeling

Biomass pyrolysis is considered as a thermochemical conversion system that is performed under oxygen-depleted conditions. A large body of literature exists in which thermodynamic equilibrium (TE) and kinetic approaches have been applied to predict pyrolysis products. However, the reliability, accuracy and predictive power of both modeling approaches is an area of concern. To address these concerns, in this paper, two new simulation models based on the TE and kinetic approaches are developed using Aspen Plus, to analyze the performance of each approach. Subsequently, the results of two models are compared with modeling and experimental results available in the literature. The comparison shows that, on the one hand, the performance of the TE approach is not satisfactory and cannot be used as an effective way for pyrolysis modeling. On the other hand, the results generated by the new model based on the kinetic approach suggests that this approach is suitable for modeling biomass pyrolysis processes. Calculation of the root mean square error (RMS), to quantify the deviation of the model results from the experiment results, confirms that this kinetic model presents superior agreement with experimental data in comparison with other kinetic models in the literature. The acquired RMS for the developed kinetic method in this paper varies within the span of 1.2 to 3.2 depending on temperature (400–600 °C) and various feedstocks (pine spruce sawdust, bagasse, wood bark, beech wood and paddy straw).

Assessment of Rice Husk Biomass Potential for Power Generation in Pakistan

Rice husk is one of the utmost obtainable feedstock for renewable energy production and can contribute to resolving energy scarcity and environmental problems. Appropriate knowledge of the rice husk's physiochemical properties is essential for the approach of thermochemical conversion systems. The present study delivers data on proximate and ultimate analysis and heating values of rice husk collected from different regions of Sindh, Pakistan. Moisture content was found low ranging between 12.76% to 13.50% (Mean 12.98%), higher volatile matter in the range of 55.77% to 62.88% (Mean 61.19%) and ash particles of 14.50% to 16.48% (Mean 15.20%). The lower concentrations of nitrogen, 0.37% to 1.31%, (Mean 0.70%) and sulfur, 0.02% to 0.19%, (Mean 0.11%) environmentally deal with more appropriate fuel properties. The heating value of rice husk ranges varied from 5,276.33 to 6,237.13 Btu/lb (Mean 5,859.87 Btu/lb). The significant values of the rice husk samples indicated that the locally available renewable resources can be transformed into an extensive amount of energy products at a small level from active conversion techniques. Therefore, rice husk can be deliberated as appropriate fuel for energy generation and can be considered as an environmentally friendly and economically feasible fuel that helps to decline harmful pollutions.

Recent advances of hybrid solar - Biomass thermo-chemical conversion systems

Solar biomass hybridization is a promising energy technique for efficient utilization while mitigating the disadvantages associated with both biomass and solar energy source. In conventional concentrating solar power (CSP) systems, the contribution of solar energy is relatively low, merely supplementing the system with low/medium temperature air/steam. This paper aimed to emphasize the improvement of solar heat share, particularly in the topping cycle of the hybrid system. The solar aided processes, either directly generating superheated air/steam or direct gasification are thermodynamically favorable at very high temperatures, in excess of 800 °C. Unfortunately, this temperature is unattainable in conventional CSP systems using molten salt. Accordingly, the integration of solar power tower (SPT) with solid particle fluidized system in a beam down configuration has been proposed for the hybrid solar-biomass systems. Studies of such integration system presented challenges in terms of operating temperature, continuous supply/syngas production and scaling of reactor, particularly for circulating fluidized bed (CFB). The selection of solid particle and gas flow rate are among the governing parameters for high operating temperature and effective utilization of solar heat. The development of high temperature hybrid solar-biomass system is anticipated for higher solar-to-fuel conversion efficiencies, minimizing the direct combustion of biomass and reduce the emission of greenhouse gas (GHG) emissions.

Water leaching for improving fuel properties of pongamia Pod: Informing process design

Pongamia seedpods are recognized as a potential feedstock for sustainable aviation fuel production due to the relatively high oil content of the seeds. Pongamia pods are byproduct residues available after seed separation. Pods have high chlorine and potassium content that may be problematic in thermochemical energy conversion systems. Leaching experiments were performed to remove inorganic constituents of pods and thereby reduce the potential for fouling, slagging, and agglomeration. A 23 factorial design determined the impacts of process operating parameters (i.e. rinse water temperature (25 °C vs. 75 °C), rinse duration (10 min vs. 2 h), and particle size (<2 mm vs. whole pod)) on the composition and physicochemical properties of the pods and the water. The higher heating value of the pods was found to increase from 16 to 18–19 MJ/kg after leaching, while the ash content was reduced from 6.5% to as low as 2.8%wt, with significant removal of sulfur (S), chlorine (Cl), and potassium (K). The chemical oxygen demand, non-purgeable organic carbon, and total nitrogen of the post-experiment leachates were all found to increase with the rinse water temperature and rinse duration but decrease with the increase of particle size. Leached pods were further processed via torrefaction and the targeted mass and energy yields, ~70% and 85%, respectively, were reached at a process temperature of 270 °C. The S, Cl, and K contents of the leached, torrefied pods were found to be lower than that of the raw pods. The reuse of leachate on successive batches of fresh pods showed that ash removal efficiency was reduced after three cycles, although some removal was possible through 15 cycles.

Determination of Kinetic and Thermodynamic Parameters of Pyrolysis of Coal and Sugarcane Bagasse Blends Pretreated by Ionic Liquid: A Step towards Optimization of Energy Systems

Pyrolysis behavior of ionic liquid (IL) pretreated coal and sugarcane bagasse (SCB) blends through thermogravimetric analysis (TGA) was studied. Three blends of coal and SCB having 3:1, 1:1, and 1:3 ratios by weight were treated with 1-ethyl-3-methylimidazolium chloride ([Emim][Cl]) at 150 °C for 3 h. Untreated and IL treated blends were then analyzed under pyrolytic conditions in a TGA at a constant ramp rate of 20 °C/min. Kinetic and thermodynamic parameters were evaluated using ten Coats-Redfern (CR) models to assess reaction mechanism. Results showed that the untreated blends followed a definite pattern and were proportional to the concentration of SCB in the blends. IL treated blends exhibited a higher average rate of degradation and total weight loss, indicating that IL had disrupted the cross-linking structure of coal and lignocellulosic structure of SCB. This will enhance the energy generation potential of biomass through thermochemical conversion processes. The lower activation energy (Ea) was calculated for IL treated blends, revealing facile thermal decomposition after IL treatment. Thermodynamic parameters, enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), revealed that the pyrolysis reactions were endothermic. This study would help in designing optimized thermochemical conversion systems for energy generation.

Spent tea waste as a biomass for co-gasification enhances the performance of semi-industrial gasifier working on groundnut shell

An effective utilization of agricultural waste as an energy source for decentralised power generation and thermal applications can meet the increasing energy demand in rural areas. A substantial number of thermo-chemical conversion systems are used for this purpose; nevertheless, it is significant to improve their efficiency to widen the implementation of this technology for various applications. Groundnut shell is one of the popular agricultural wastes available in many countries like India. Due to its low bulk density and physical nature co-gasification of this feedstock with another biomass is not popular. However, a high carbonaceous powdery biomass like Spent Tea Waste (STW), a waste after brew tea can be suitably mixed with groundnut shell along with some moisture to accomplish this task. To prove this strategy an experimental study has been conducted at various combinations of these two types of biomass as feedstock in a 115 kWth semi-industrial type gasifier, and its performance parameters are studied for possible operating conditions of the gasifier. The observations show that the wet STW can maintain a uniform consistency, when mixing both the biomasses until its composition is 40% of the blend. The results show that the increase in hydrogen composition, calorific value and cold gas efficiency is in the ranges of 9.9–21.5%, 4.1–10.4% and 3.9–9.9% respectively as compared to groundnut shell. Besides, the maximum calorific value of producer gas is 6.68 MJ m−3.

Kinetic study and pyrolysis: GC/MS products analysis of Spirulina platensis cultivated under a different growing medium

Microalgae have a great potential to produce biofuels, but the cost is still too high mainly due to the biomass production. Mixotrophic cultivation has been pointed as microalgae cultivation mode for biomass/bioenergy production with lower cost. The proposals of this work were to cultivate S. platensis in autotrophic and mixotrophic medium using molasses as source of organic carbon and investigate the thermal behavior of obtained biomass by means of thermogravimetric analysis and pyrolysis (Py-GC/MS). The kinetics models proposed by Flynn and Wall and model-free kinetic were used to determine the activation energy. These data are important to projection of design, operation and modeling of thermochemical conversion system for microalgae. The use of molasses as supplement in culture medium for the growth of S. platensis was a good way to increase the biomass productivity and decrease the protein content. The Flynn–Wall and model-free kinetic methods were adequate to calculate activation energy on the conversion range of 0.20 to 0.80. The activation energies were 168–229 kJ mol−1 (Flynn and Wall), 177–238 kJ mol−1 (model-free kinetic) for mixotrophic biomass and 174–220 kJ mol−1 (Flynn and Wall), 181–229 kJ mol−1 (model-free kinetic) for autotrophic biomass. The compositions of volatile compounds produced by S. platensis biomass pyrolysis were different due to cultivation method that influenced the composition of biomass. Hydrocarbons, oxygenated and nitrogenated compounds were produced with different quantities. The volatile compounds content of phenols, oxygenated and nitrogenated increased and non-aromatic and aromatic hydrocarbons content decreased for pyrolysis of mixotrophic biomass. However, the mixotrophic cultivation has a great influence on the microalgae biomass production and should be a factor considered in thermal degradation project for microalgae.

Logging wastes from sustainable forest management as alternative fuels for thermochemical conversion systems in Brazilian Amazon

Logging wastes of tropical species managed sustainably in the Brazilian Amazon are promising for replacing fossil fuels. However, their use in local energy systems is challenging concerning many mixed-species with unknown properties. This study focuses on the energy characterization of the logging wastes from twenty commercial Amazon species harvested in a sustainable management plan and their energy equivalence to fossil fuels. The wood species were grouped by principal component analysis according to their basic density, moisture content, maximum moisture content, heating value, energy density, and chemical composition. Basic density (0.525–0.895 g cm−3), energy density (9.4–16.8 GJ m−3), ash (0.3–2.5%), and total extractives (1.8–17.9%) showed wide interspecific variations. On the other hand, the carbon content (49.2–52.4%), total lignin (30.2–38.1%), fixed carbon (16.5–22.0%), volatile matter (76.7–82.8%), and higher heating value (19.1–20.9 MJ kg−1) varied less among species. D. excelsa, M. elata, P. altissium, and G. glabra wastes surpassed conventional planted species for bioenergy applications. The logging wastes formed four groups with similar properties aiming at energy systems. The fuelwood value index ranked wastes of D. excelsa wood as the most promising for bioenergy. Finally, D. excelsa wood wastes presented the largest mass of CO2eq fixed in 1 m3 of logging wastes (1,687 kg), meaning that the use of 1 m3 of these wastes would mitigate the emission of 1,687 kg of CO2eq.

Lab-scale pyrolysis and hydrothermal carbonization of biomass digestate: Characterization of solid products and compliance with biochar standards

Carbonization of anaerobic digestion digestate from an Italian plant fed with local feedstock was investigated by slow pyrolysis (SP) and hydrothermal carbonization (HTC); the properties of pyrochar and hydrochar were compared and framed into the International guidelines for soil improvers/amendments in agriculture. Experiments were carried out in newly designed thermochemical conversion systems, with the aim of generating the original data necessary for future scale-up and for evaluating the characteristics of the product versus existing biochar market standards. SP was carried out in a paddle pyrolysis reactor at 500 °C for 1 h, while several HTC experiments were performed in a custom-made test bench, investigating the influence of temperature (200–250 °C) and time (0.5–3 h) on hydrochar properties. Both processes were run in batch mode. SP showed lower char yield (33.1%w/w db), while the maximum hydrochar yield was obtained at 200°C-0.5 h (72.6%w/w db). Most char properties fall within the thresholds set by biochar standards. The Carbon content was slightly higher for pyrochar (64.3%w/w db) than hydrochar (62.9%w/w db at 250°C-3 h). The specific area was rather low for both chars; however, pyrochar area (23.10 m2 g−1), was one order of magnitude higher than hydrochar. The ash content of pyrochar was nearly twice the hydrochar, while O/C and H/C ratio of the former were lower.The HTC aqueous phase was also characterized in terms of inorganics concentration and organic composition. In average, the concentration of the former increased with reaction severity: more than 50 compounds were identified and 20 quantified. Acetic acid was the most abundant (up to 3.26 g l−1).

Solid Biofuel Characterization and Ash Properties of Acacia Mangium

Acacia Mangium is a common industrial planted woody biomass in the tropical and subtropical climates. As an economically viable, agroforestry beneficial and environmentally sustainable bio-energy form, it has the potential to generate heat for thermochemical conversion systems. This article provides a comprehensive evaluation of its characteristics, physiochemical properties, ash composition and transformation phenomena. In accordance with the ISO/DIN guides for solid fuels, the standard methods were applied. The results of analyses solid biofuel showed the significant calorific value (19-20 MJ/kg); high volatile matter, relatively low ash content; and a low S content. X-ray analyskjhgis detected high values of Ca, K, Fe, Al and Si the ash-forming elements. Ash softening and fusion phenomena were observed, with heat generated continuously at constant rates (maintained at 550 ± 10 °C for 120 minutes and practically at 850 ± 10 °C for 240 minutes). The first signs of deformation were recorded at a temperature of approximately 1220 °C, with the melting point reached at 1310 °C, which was an advantage for a woody solid biofuel.

Hidrojen Üretimi için Üç Adımlı Cu-Cl Termokimyasal Sistemin Enerji ve Ekserji Analizi

Thermochemical cycle systems produce hydrogen without the release of greenhouse gases using heat and electrical energy from renewable energy sources. In this study, the energy and exergy analyses of designed high-temperature Cu-Cl thermochemical conversion system are performed. Parametric studies are carried out by examining the analyses according to different reference temperature values and reaction temperatures. The exergy rates and exergy destruction rates for each step of cycle, and also the exergy efficiency of system are investigated. The energy and exergy efficiencies of Cu-Cl thermochemical cycle at a reference ambient temperature of 25 °C are found as 55.41% and 66.09%, respectively. In addition, the maximum exergy destruction in the investigated system occurred in the hydrogen production step.

Miniature Biomass Conversion Unit for Learning the Fundamentals of Heterogeneous Reactions through Analysis of Heat Transfer and Thermochemical Conversion

HighlightsA miniaturized thermochemical conversion system has been designed, manufactured, and optimized.Five laboratories can be performed with the system, incorporating heat transfer and reaction engineering phenomena.Educational materials to deploy the system in the classroom, including worksheets and solutions, are provided.Pyrolysis, combustion, and gasification exercises are shown with reaction visualization and product validation.Abstract. We describe a simple new miniaturized thermochemical module (MTM). Special considerations are needed to make the MTM useful not only for studying biomass conversion but also for providing safe classroom learning opportunities for heat and mass transfer and heterogeneous reaction engineering students and for training new researchers. The MTM consists of a quartz reactor wrapped with a Kanthal resistance wire and a silvered concentric annular glass shield for retaining thermal energy, placed in a protective Plexiglas viewing case. Safety is considered for use by new research trainees and within the classroom. We demonstrate MTM usage through five laboratory exercises beginning with an experimental design to determine operating modes to establish thermochemical conversion temperatures. Heat transfer skills are developed with the aid of a first-order differential heat transfer model and fractional factorial design. Thermochemical conversion is demonstrated and products are validated for pyrolysis, gasification, and combustion. The combustion laboratory also offers significant insight into reaction versus mass transfer-controlled regimes and for modeling heat transfer. Discussion is provided on the utility of the system for demonstrating heat transfer, kinetic, and mass transfer concepts, with applications across the engineering curriculum. Keywords: Combustion, Education, Gasification, Heat transfer modeling, Miniature thermochemical module, Pyrolysis.

Tar content and composition during a low-temperature steam gasification of rice husks

The research work extends our recent empirical knowledge on the rice husks, a carbonaceous solid material. This solid biofuel option was characterized with a potential net heating value of 16–17 MJ/kg, significant high ash deformation temperature recorded above 1450 °C, capable and considerable for thermochemical conversion systems. An experimental performance on a dual fluidized bed steam gasifier using rice husks pellets was carried out at a low temperature between 600 and 650 °C and fuel power of 100 kWth. Pure steam was used as a gasification agent in fluidization at a steam to fuel ratio of 1.2 kg/kg on dry basis. Calcite with mainly CaCO3 in composition was used as bed material for the reactor. Tar content and composition in the product gas stream were analyzed with a gas chromatograph coupled with mass spectrometer (GC–MS). Significant high amounts of total GC–MS tar components (without benzene, ethylbenzene, and xylene) and gravimetric tar (higher molecular tar) were detected at 29.44 and 17.82 g/m3 on dry basis. Benzene content was, respectively, presented on a value of 9 g/m3 on dry basis. Obtained products consisted of relevant amount of phenol and heterocyclic aromatic tars (class 2). The specific composition of common and additional analytes presented in GS–MS tar was summarized for better understanding of tar formation and reduction phenomena of rice husk gasification.