Thermochemical Processing Of Biomass Research Articles

A Practical Approach to Using Energy Integration in the Simulation of Biomass Thermochemical Processes: Application to Supercritical Water Gasification

Solid biomass is usually simulated by decomposing it into a solid phase (carbon, ash, and sulfur) and a gas phase (water and diatomic molecules of H2, N2, O2, and Cl2) from the proximate and ultimate analysis before entering a reactor operating under chemical equilibrium when using Aspen Plus. However, this method prevents the use of energy integration for the feed stream from the system inlet to the reactor. This paper proposes an approach to solving this issue, considering biomass with both known and unknown chemical compositions; the latter involves the decomposition of biomass into complex molecular compounds. Different process arrangements were assessed to achieve a realistic simulation, and a sensitivity analysis was carried out to examine the effect of the concentration and heating upstream of the reactor, focused on supercritical water gasification (SCWG) of orange peel. This process is very energy-intensive, so the approach is useful for a better calculation of the energy requirement and exergy losses in a plant; these are usually and mainly related to the train of heat exchangers. In addition to this application to SCWG, this approach can be used for any other thermochemical process, such as gasification, pyrolysis, or combustion, and for any real biomass. Upon a base case study using a wet biomass of 10,000 kg/h with 90 wt.% water where the SCWG reaction takes place at 240 bar and 800 °C, if the temperature at the SCWG reactor inlet increases from 350 °C to 400 °C, the heat exchange increases by 57% from 4 MW and by 34% if the water content decreases to 70 wt.%, although more heat relative to the solid is saved.

A review on modelling of thermochemical processing of biomass for biofuels and prospects of artificial intelligence-enhanced approaches

Biofuels from lignocellulosic biomass converted via thermochemical technologies can be renewable and sustainable, which makes them promising as alternatives to conventional fossil fuels. Prior to building industrial-scale thermochemical conversion plants, computational models are used to simulate process flows and conditions, conduct feasibility studies, and analyse process and business risk. This paper aims to provide an overview of the current state of the art in modelling thermochemical conversion of lignocellulosic biomass. Emphasis is given to the recent advances in artificial intelligence (AI)-based modelling that plays an increasingly important role in enhancing the performance of the models. This review shows that AI-based models offer prominent accuracy compared to thermodynamic equilibrium modelling implemented in some models. It is also evident that gasification and pyrolysis models are more matured than thermal liquefaction for lignocelluloses. Additionally, the knowledge gained and future directions in the applications of simulation and AI in process modelling are explored.

Hydrochar Application Improves Growth and Intrinsic Water Use Efficiency of Populus alba, Especially during Hot Season

Hydrochar, carbon-rich material produced during the thermochemical processing of biomass, is receiving increased attention due to its potential value as soil amendment. It can increase agroforestry systems’ productivity through direct and indirect effects on growth and soil quality. Hydrochar may also directly help mitigate climate change by sequestering stable carbon compounds in the soil and perhaps indirectly through increased C uptake by trees. In this research, we aim to evaluate how the application of hydrochar produced by two feedstock types, Cynara cardunculus L. (Hc) residuals and sewage sludge (Hs), and in two different doses (3 and 6 kg m−2) could improve the growth and water use efficiency of Populus alba L., a fast-growing tree species largely used in agroforestry as bioenergy crops and in C sequestration. We considered five plants per treatment, and we measured apical growth, secondary growth, leaf area and intrinsic water use efficiency in each plant for the whole growing season from February to October 2022. Our results highlighted that hydrochar applications stimulate the growth and water use efficiency of plants and that the double dose (6 kg m−2) of both hydrochars, and particularly Hc, had positive effects on plant performance, especially during extremely hot periods. Indeed, the year 2022 was characterized by a heat wave during the summer period, and this condition allowed us to evaluate how plants, growing in soils amended with hydrochar, could perform under climate extremes. Our findings showed that the control plants experienced severe damage in terms of dried stems and dried leaves during summer 2022, while hydrochar applications reduced these effects.

A comparative review on photo and mixotrophic mode of algae cultivation: Thermochemical processing of biomass, necessity of bio-oil upgrading, challenges and future roadmaps

Availability of renewable biomass for the production of bioenergy is need of hour as fossil-based energy consumption has led to both environmental and health problems. Algae biomass gains advantages over other biomasses (agriculture, sewage, forest, sludge, municipal waste) due to their availability, biomass generation in wastewater and negative carbon dioxide emission. In this review paper, we have explored the algae biomass cultivation routes, thermochemical conversion and upgradation of algal biomass. Photo bioreactors (tubular, bag, flat panel, etc) are preferred for microalgae cultivation in association with raceway open ponds for liquid hydrocarbons production. Algae biomass are processed through hydrothermal liquefaction (Temperature range of 220–320 °C, time of 60 min, pressure of 5–20 bar), pyrolysis (Temperature range of 320–420 °C) and co-liquefaction. The commonly upgradation techniques are catalytic cracking, hydrodeoxygenation, etc. Hydrodeoxygenation was performed to nullify the oxygen content of bio-oil, since in adverse case the bio-oil with higher content causes corrosion and coke formation in combustion engines. The algae biofuel production cost depends upon the conversion techniques and upgrading processes. Further in future this review provides strong base for exploring the aqueous phase obtained from thermochemical process for bio-hydrogen production via photo-catalytic reforming processes.

Metal oxide rich char from muffle furnace and retort heated reactor treated cow bone

The high energy cost of thermochemical processing of biomass wastes into valuable products has necessitated the usage of alternative biofuel powered reactor like top lit updraft (TLUD) retort heated reactor. The suitability of TLUD retort heated, self regulating reactor as alternative to the conventional muffle furnace was explored in cow bone carbonization in this study. High-temperature treatments of cow bone (TCB) were carried out in conventional muffle furnace option (TCB 1) and TLUD retort heated reactor (TCB 2). For comparison, cow bone was treated at higher temperature (500 o C) for 120 min using a conventional method, designated TCB 1, while the same was treated in a self regulating retort heated reactor powered by combusting biomass with peaked temperature of 462.7 o C and the combustion time of 90 min. The properties of the samples TCB 1 and TCB 2 were studied using SEM, XRD, BET, BJH, XRF-EDS, and DFT. In the final analysis, results of TCB 1 and TCB 2 were found competitively comparable in their physiochemical properties and the presence of additional minerals and elements. The present study reveals an economical and effective material recovery route for the preparation of adsorbents and precursors of compounds and elements. • Metallic oxide rich char was produced via compared thermal treatments from cowbone waste. ii. Muffle Furnace and retort heated reactor at differential conditions were used. iii. Physicochemical properties were elucidated and low cost retort treated means were found better.

Development of a Small-Scale Electricity Generation Plant Integrated on Biomass Carbonization: Thermodynamic and Thermal Operating Parameters Study

Biomass has been known as a source of energy with a thermochemical process that produces heat and can be converted further into electricity. However, thermal energy losses are a huge problem during combustion. To overcome this problem, a system based on organic Rankine cycle (ORCs) was developed to recover and utilize them to generate electricity. The proposed ORCs include an evaporator, a turbine, a condenser, and a pump coupled with a biomass carbonizing system to create a promising technology for small-scale electricity generation. In this work, a thermodynamic modelling equation based on energy and exergy balances was briefly expressed for each subcomponent of the system. A case study with R134a as the working fluid is being investigated to validate the system’s performance. In addition to the effects of R134a on temperature at the turbine exit, the suitable operating pressures has been specially adopted from several valid journals that focused on the effects of a wide range of possible operating pressure on the working fluid characteristics, which have a significant effect on the system performance. Finally, the theoretical analysis shows that the turbine work is profitable at an inlet pressure of 5 bar and an outlet pressure of 2 bar. This system is recommended to be integrated into the thermochemical biomass process. Recommendations have been made for the future development of small-scale biomass-fuelled power generation systems. This study shows that the thermal losses of the biomass thermochemical processes can be theoretically recovered in the form of electricity by using ORC efficiently.

Virtual Special Issue of Recent Research Advances in China: Thermochemical Processing of Biomass and Solid Wastes

Virtual Special Issue of Recent Research Advances in China: Thermochemical Processing of Biomass and Solid Wastes

Process Intensification through Directly Coupled Autothermal Operation of Chemical Reactors

Summary Autothermal operation of a chemical reactor involves coupling exothermic and endothermic chemical reactions for the purpose of thermal management without resorting to external energy sinks or sources. Often this is accomplished through regenerative or recuperative heat exchange between spatially or temporally separated exothermic and endothermic reactions. However, it is also possible to directly couple these reactions simultaneously within the same reactor volume, eliminating the heat-transfer bottleneck that characterizes much of chemical manufacture. It is not widely recognized that directly coupled autothermal operation allows dramatic process intensification. This perspective defines autothermal operation and contrasts it with conventional heat transfer for thermal management of chemical processes. The intensification and cost savings that can be achieved are quantified, and the implications to modular chemical process intensification are presented. Guidelines are proposed for designing directly coupled autothermal processes. Diverse examples are presented. Several challenges to expanding the field are critically discussed.

Effects of biochar on soil fertility and crop productivity in arid regions: a review

Biochar, carbon-rich materials produced during the thermochemical processing of biomass, are receiving increased attention given their potential value as soil amendments. Biochar are formed through pyrolysis processes—heating to several hundred degrees Celsius under oxygen-limited environments—and both the source feedstock and the reaction conditions affect the quality of the resulting chars. Biochar can enhance soil physical and chemical properties and increase agricultural systems’ productivity through direct and indirect effects on crop growth and soil quality. Biochar also may directly help mitigate climate change by sequestering stable carbon compounds in the soil and perhaps indirectly through increased C uptake by trees. As the world faces growing challenges from soil degradation and climate change, biochar application to soils represents a potential pathway forward. Although a large volume of literature exists regarding the use of biochar under favorable climatic conditions, information regarding biochar applications in semiarid and arid climates has been more limited. Evidence of greater water holding capacity and reduced infiltration suggests these materials have potential to improve the productivity of such lands and provides a basis for considering its wider application in the arid environments such as Saudi Arabia. Challenges and limitations for biochar use on a mass scale are also briefly discussed. To move this technology forward, crop and soil scientists should involve economists and agricultural extension educators in studies that consider economic as well as biophysical implications for biochar’s application on a mass scale.

Modelling of thermochemical energy recovery processes for switchgrass (Panicum virgatum)

ABSTRACT The thermochemical processing of biomass is gaining increasing importance as the global drive towards energy and environmental sustainability continues. The aim of this study was to model the pyrolysis, in-line stream reforming and air gasification of switchgrass (Panicum virgatum) using ASPEN Plus v8.8. For the pyrolysis process, a temperature of 450°C was predicted to give a pyrolysis yield of 70.2 wt% bio-oil, 19.8 wt% char and 9.9 wt% syngas. At an optimum steam reforming temperature of 700°C, 1 atm pressure and 10 kg/kg steam-to-feed ratio the composition of the product stream was 70.23 mol% H2, 27.98 mol% CO2, 1.79 mol% CO and trace CH4. At these conditions, a theoretical feed of 10 kg/hr biomass and 100 kg/hr steam was predicted to yield 11.21 wt% synthesis gas (70% H2 rich) besides other by-products. At an optimum gasification temperature of 700°C, 1 atm pressure and 0.6 kg/kg air–fuel ratio the composition of the product stream was 47.68 mol% H2, 13.95 mol% CO2, 36.53 mol% CO and 1.83 mol% CH4. Thermochemical processing was observed to be an excellent means of harnessing the energy content of the biomass to obtain more important products.

Hydrogen Production from Steam Reforming of Acetic Acid as a Model Compound of the Aqueous Fraction of Microalgae HTL Using Co-M/SBA-15 (M: Cu, Ag, Ce, Cr) Catalysts

Hydrogen production derived from thermochemical processing of biomass is becoming an interesting alternative to conventional routes using fossil fuels. In this sense, steam reforming of the aqueous fraction of microalgae hydrothermal liquefaction (HTL) is a promising option for renewable hydrogen production. Since the HTL aqueous fraction is a complex mixture, acetic acid has been chosen as model compound. This work studies the modification of Co/SBA-15 catalyst incorporating a second metal leading to Co-M/SBA-15 (M: Cu, Ag, Ce and Cr). All catalysts were characterized by N2 physisorption, ICP-AES, XRD, TEM, H2-TPR, H2-TPD and Raman spectroscopy. The characterization results evidenced that Cu and Ag incorporation decreased the cobalt oxides reduction temperatures, while Cr addition led to smaller Co0 crystallites better dispersed on the support. Catalytic tests done at 600 °C, showed that Co-Cr/SBA-15 sample gave hydrogen selectivity values above 70 mol % with a significant reduction in coke deposition.

Improved Adaptive Neuro-Fuzzy Inference System Using Gray Wolf Optimization: A Case Study in Predicting Biochar Yield

Abstract This paper presents an alternative method for predicting biochar yields from biomass thermochemical processes. As biochar is considered a renewable and sustainable energy source, it has received more attention. Several methods have been presented to predict biochar, such as neural network (NN) and least square support vector machine (LS-SVM). However, each of them has its own drawbacks, such as getting stuck in a local optimum, which occurs in NN, and lack of uncertainty and time complexity, as in LS-SVM. Therefore, this paper avoids this limitation by using a hybrid method between the adaptive neuro-fuzzy inference system (ANFIS) and gray wolf optimization (GWO) algorithm. The proposed method is called ANFIS-GWO, which consists of two stages. In the first stage, GWO is used to learn the parameters of ANFIS using the training set. Meanwhile, in the second stage, the testing set is used to evaluate the performance of the proposed ANFIS-GWO method. Three experiments were performed to assess the performance of the proposed method. The first experiment used a set of UCI (University of California, Irvine) benchmark datasets to evaluate the effectiveness of ANFIS-GWO. The aim of the second experiment was to evaluate the performance of the proposed ANFIS-GWO method to predict biochar yield from manure pyrolysis. The third experiment aimed to estimate the values of input parameters of pyrolysis that maximize biochar production. The obtained results were compared to those of other methods, such as ANFIS using gradient descent, practical swarm optimization, genetic algorithm, whale optimization algorithm, sine-cosine algorithm, and LS-SVM. The results of the ANFIS-GWO method were >35% of the standard ANFIS and also better than those of other methods.

CFD modelling of biomass gasification with a volatile break-up approach

Gasification thermochemical processes of biomass in a 20 kW downdraft gasifier are investigated using a robust two-dimensional (2D) computational fluid dynamics (CFD) modelling method. The model includes all the four zones of the gasifier namely drying, pyrolysis, oxidation and reduction. A step-by-step approach is proposed to evaluate the composition of different gas species as a result of the volatile break-up during gasification. However, selecting suitable chemical reactions for the CFD modelling becomes challenging as the commonly used reactions in kinetic study showed discrepancy in predicting the synthesis gas compositions. A revised set of chemical mechanisms is therefore proposed in the study and the robustness of the approach is examined with results validated against data from literature. The study reports how the air equivalence ratio (ER) affects the gasifier temperature and also the composition of producer gases. The model is then applied to investigate the syngas production of various biomass feedstocks sourced from Scottish agricultural sites.

Bi-objective optimization of biochar-based carbon management networks

Abstract Biochar is the carbon-rich solid product derived from thermochemical processing of biomass. Its application to soil can sequester atmospheric carbon, leading to negative net emissions, while also improving agricultural yield. Biochar-based carbon management networks thus have the potential for scalable contributions to climate change mitigation efforts. However, it is necessary to allocate biochar of suitable quality to appropriate sinks, based on contaminant tolerance limits of soil. In this work, the network is modelled as a bi-objective mixed integer linear programming model, with profit and carbon sequestration as the objective functions. The model calculates the optimum allocation of biochar such that their prescribed limits for the contaminants are met. A Philippine case study is solved under different scenarios to illustrate the practical use of the developed model. The results provide useful insights for the rational decision-maker to arrive at the most preferred solution among the Pareto optimal choices. Comparison of the two scenarios substantiate the significance of unique sequestration factor as an additional parameter in the model to account for the interactions between the soils and biochars so that the maximum sustainable potential of biochar in climate change mitigation can be properly assessed.

Graphical Pinch Analysis for Planning Biochar-Based Carbon Management Networks

Biochar is a potentially scalable negative emission technology (NET). The negative net flow of carbon is achieved sequentially via photosynthesis which fixes atmospheric carbon into biomass, followed by thermochemical processing of biomass into biochar which converts the bulk of the fixed carbon into stable or recalcitrant form, and finally by the application of the resulting biochar to soil. In addition, this process can result in additional carbon offsets through favorable modification of soil by reducing fertilizer requirement, as well as other secondary benefits. On the other hand, biochar is typically contaminated with traces of organic (e.g., dioxins) and inorganic impurities (e.g., salts) that are detrimental to soil quality. The presence of such impurities and the capacity of the receiving soil to tolerate their presence put an upper limit on the amount of biochar that can be added without causing adverse environmental effects. Thus, scaling up biochar-based systems requires the planning of a carbon management network (CMN) consisting of biochar sources (i.e., production facilities) and biochar sinks (i.e., receiving tracts of land). In general, such CMNs need to be operated so as to maximize system-wide carbon sequestration without exceeding the tolerance limits of the biochar sinks. This paper proposes a graphical pinch analysis approach to planning such biochar-based CMNs. The applicability of the methodology is illustrated using a hypothetical case study.

Thermal decomposition of rape straw: Pyrolysis modeling and kinetic study via particle swarm optimization

The aim of this work is to implement an efficient and robust optimization approach for parameter estimation of pyrolysis kinetic model to study the pyrolysis of a typical agricultural residue. Thermogravimetric profiles of rape straw were obtained at a wide heating range of 10, 20, 30 and 40°C/min in an inert atmosphere of nitrogen and the thermal decomposition process was studied in detail. First, three different kinetic methods (Friedman, KAS and OFW) were applied for activation energy determination. The activation energies ranged from 191.16kJ/mol to 264.31kJ/mol. Then, the reaction mechanism and pre-exponential factor were analyzed by using the generalized master-plots method. It is found that at conversion level higher than 0.4 the rape straw decomposition was governed by 3-D diffusion model and it tended to high order reaction model at lower conversion. Finally, a multi-component parallel reactions scheme incorporated into the Particle Swarm Optimization (PSO) technique was presented to determine kinetic parameters. The kinetic triplets and other stoichiometric parameters were optimized against profiles for heating rates of 20 and 30°C/min. The optimized activation energy value is 156.41kJ/mol, 211.26kJ/mol and 57.84kJ/mol for hemicellulose, cellulose and lignin, respectively. These results are in conformity with results reported in previous literatures. Meanwhile, the obtained pre-exponential factors values also lie in the reasonable range of lnAi=25.32–39.14ln/s according to intrinsic transition-state theory. Furthermore, cross-validated results show that the optimized parameters can be applied not only to conditions where they were obtained, but also to conditions beyond (10 and 40°C/min), indicating that the derived results are appropriate to simulate and predict rape straw pyrolysis under various heating rates, which will be useful for further design and sizing of biomass thermochemical process reactors.

Mixing and segregation in fluidized bed thermochemical conversion of biomass

Fluidized bed thermochemical conversion of biomass (combustion, gasification, pyrolysis) displays a long record of successes, spanning from lab- to industrial scales, and stems out as the most viable pathway for the exploitation of biogenic fuels, either alone or in combination with fossil fuels. In spite of its diffusion, there are still open design and operational issues that are largely related to segregation and mixing of solid and gas phases in fluidized beds and effectiveness of multiphase contacting patterns. The common claim of fluidized beds being well stirred/well controlled environments for heterogeneous and gas-phase reactions falls short when applied to processing of biomass fuels.This study aims at providing a comprehensive framework of fundamental phenomena affecting mixing/segregation of phases during thermochemical processing of biomass and of their interlinks. The basic processes include patterns and kinetics of biomass devolatilization, particle and volatile matter (VM) segregation along and across the reaction chamber, particle attrition/fragmentation and generation of fine particulates, the diversity of gasification patterns and rates, as related to chemical composition and morphology of the parent biogenic fuels. Segregation brings about important consequences in terms of temperature uniformity, of proper control of heterogeneous and gas-phase reaction pathways, of ash behaviour, of pollutant emissions, of plant operability and dependability. Measures to counteract segregation, including pre-processing of biomass and/or appropriate control of bed hydrodynamics, will also be surveyed from the fundamental and applied standpoints.

Syngas conversion to ethanol over a mesoporous Cu/MCM-41 catalyst: Effect of K and Fe promoters

Transportation fuels such as ethanol can be obtained through thermochemical processing of biomass. Interest in the development of more selective catalysts for the conversion of biomass-derived syngas (H2+CO) to ethanol is increasing in both academia and industry. In this work, we have evaluated the performances of K and Fe as metal promoters of a mesoporous Cu/MCM-41 catalyst and their effects on the product selectivity and especially on ethanol formation. The metal loading was 29wt.% Cu, 2wt.% Fe and 1.6wt.%K. The catalysts were tested at 300°C, 20bar and gas-hourly-space-velocities in the range of 1500–30000mlsyngas/gcat h; under these conditions the syngas conversion level was between 2 and 11%. The non-promoted Cu/MCM-41 catalyst showed interesting selectivity toward oxygenated compounds, mostly methanol. The addition of K as promoter increases the selectivity toward methanol even more, while the addition of Fe as promoter favors the formation of hydrocarbon compounds. When both K and Fe as promoters are incorporated into the Cu/MCM-41 catalyst, the reaction rate to oxygenated compounds is notably increased, especially for ethanol. The space time yield for ethanol for the Cu/MCM-41 catalyst is 0.3×10−5 carbon-mol/gcath which increases to 165.5×10−5 carbon-mol/gcath for the Cu-Fe-K/MCM-41 catalyst. From XPS analysis, the Cu-Fe-K/MCM-41 catalyst was found to have the following atomic composition: Cu0.34Fe0.08K0.08Si1.00. The promoting effect of both K and Fe, may be related to an increased reaction rate toward CO non-dissociation and CO-dissociation paths, respectively, which is beneficial for the ethanol formation. Further catalytic results, catalyst characterization and discussion of results are presented in this work.

A thermal decomposition study of pine wood under ambient pressure using thermogravimetry combined with synchrotron vacuum ultraviolet photoionization mass spectrometry

As pyrolysis is the initial step involved in thermochemical processes of biomass, understanding of the pyrolytic behavior of biomass is crucial to biomass thermochemical conversions. This work presents a new facility for studying the pyrolysis behavior of solid fuels. The experimental setup contains a thermogravimetry system connected with a home-made reflectron time-of-flight mass spectrometer via a single-stage molecular beam sampling interface, and a tunable vacuum ultraviolet (VUV) light generated from synchrotron source is used for soft photoionization. Evolution of the gaseous products of pine wood pyrolysis was examined at a heating rate of 20°C/min in a nitrogen environment at atmospheric pressure. Experiments were performed at the photon energies of 10.0, 10.5 and 11.0 eV, and mass spectra of gaseous products were recorded by the time-of-flight mass analyzer every five seconds. Species with the mass range of m/z 20–220 are presented and possible formation pathways of typical products are discussed.

Synthesis of Ethanol from Syngas over Rh/MCM-41 Catalyst: Effect of Water on Product Selectivity

The thermochemical processing of biomass is an alternative route for the manufacture of fuel-grade ethanol, in which the catalytic conversion of syngas to ethanol is a key step. The search for novel catalyst formulations, active sites and types of support is of current interest. In this work, the catalytic performance of an Rh/MCM-41 catalyst has been evaluated and compared with a typical Rh/SiO2 catalyst. They have been compared at identical reaction conditions (280 °C and 20 bar), at low syngas conversion (2.8%) and at same metal dispersion (H/Rh = 22%). Under these conditions, the catalysts showed different product selectivities. The differences have been attributed to the concentration of water vapor in the pores of Rh/MCM-41. The concentration of water vapor could promote the water-gas-shift-reaction generating some extra carbon dioxide and hydrogen, which in turn can induce side reactions and change the product selectivity. The extra hydrogen generated could facilitate the hydrogenation of a C2-oxygenated intermediate to ethanol, thus resulting in a higher ethanol selectivity over the Rh/MCM-41 catalyst as compared to the typical Rh/SiO2 catalyst; 24% and 8%, respectively. The catalysts have been characterized, before and after reaction, by N2-physisorption, X-ray photoelectron spectroscopy, X-ray diffraction, H2-chemisorption, transmission electron microscopy and temperature programmed reduction.