Numerical simulation on biomass-pyrolysis and thermal cracking of condensable volatile component
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Qi, Guoli (ORCID:0000000194787710)↗
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Catalytic hot-gas filtration of biomass pyrolysis vapors
The present disclosure relates to a device that includes a filter element and a catalyst, where the filter element is configured to remove particulate from a stream that includes at least one of a gas and/or a vapor to form a filtered stream of the gas and/or the vapor, the catalyst is configured to receive the filtered stream and react a compound in the filtered stream to form an upgraded stream of the gas and/or the vapor, further including an upgraded compound, and both the filter element and the catalyst are configured to be substantially stable at temperatures up to about 500° C.
Magrini, Kimberly A.↗
Evaluation of Corrosion Susceptibility of Structural Steels in Biomass Derived Pyrolysis Oil
Biomass derived pyrolysis oil is a promising renewable energy source. Due to the variety of biomass feedstocks, the bio-oils could contain a wide range of organic constituents which would provide unique corrosive environments for structural materials. A preliminary work exposed different classes of steels and stainless steels to selected organic constituents of biomass pyrolysis oils and found that corrosion susceptibility, assessed using electrochemical impedance spectroscopy (EIS), was prominent in the steels with Cr lower than 11 wt.%. Although this result suggests stainless steels will resist corrosion by certain organic constituents, it may not be sufficient to predict the corrosion performance in real bio-oils. Therefore, this study attempted electrochemical measurements on Cr-alloyed steels and stainless steels directly exposed to a biomass derived pyrolysis oil. To overcome the low conductivity of bio-oils, a customized Luggin capillary was designed to minimize the ohmic path in bio-oils. The results of this work will be reported.
Jun, Jiheon↗
Chapter 29 - Pyrolysis of Lignocellulosic Biomass: Oil, Char, and Gas
Biomass pyrolysis is a technology that uses high temperatures to break down biomaterials like wood without completely burning them. Products include char, combustible gas, and vapors; the vapors can be condensed into a liquid with myriad uses. This chapter serves as a primer for the fundamental physics and chemistry involved in biomass pyrolysis, common reactor systems, and some reported uses for the products.
BIOMASS FUELS↗
Effect of particle characteristics, kinetics and transport phenomena on the prediction of particle mass loss and products yields during biomass fast pyrolysis
Here a low computational cost model for the pyrolysis of biomass anisotropic particles was used to study the effect of thermal conductivity of the particle, CRECK kinetic scheme implementation, intraparticle secondary reactions, heats of reaction, and advection on particle conversion prediction. The model considers a shrinking anisotropic cylindrical particle with biomass pseudo-components, the appearance of liquid intermediates, intra-particle mass and heat transport and secondary reactions of volatiles. The model was validated against oak and birchwood single particle experiments. More accurate predictions for mass loss evolution are found when considering the change of the particle thermal conductivity anisotropy with conversion and the temperature dependency of the thermal conductivities of the biomass and the gas phase, compared to ignoring these phenomena. The CRECK biomass pyrolysis reaction scheme provides insights into the effect of biomass composition on the evolution of the liquid intermediate phase allowing future studies about the presence of heavy compounds in the bio-oil and other phenomena such as aerosol ejection. Secondary intraparticle vapor phase reactions showed a negligible effect in volatiles conversion while heterogeneous reactions slightly overestimate its conversion. Heats of reaction and product advection are important for accurate prediction of particle mass loss.
09 BIOMASS FUELS↗
Using Chemical Reactor Models to Predict Fluidized Bed Pyrolysis Yields of Biomass Feedstocks
A detailed biomass pyrolysis kinetics scheme is implemented in reduced-order reactor models to predict chemical species yields from a fluidized bed reactor. The biomass composition in terms of cellulose, hemicellulose, lignins, and extractives are determined for several biomass feedstocks. Model results are compared to yields measured from a two-inch diameter bench-scale fluidized bed reactor operating at fast pyrolysis conditions. The reduced-order chemical reactor models compare favorably with the experimental measurements and capture trends in product yields due to biomass compositional effects such as high ash content. This work offers a computationally inexpensive approach to predict the quality of biomass pyrolysis products in a timely manner. Source code for the reactor models along with a biomass composition web tool are made available online for future scientific research efforts.
09 BIOMASS FUELS↗
Process Model-Based Validation of the Intensification of Biomass Fast Pyrolysis in a Fluidized Bed via Autothermal Operation
A model for the fluidized-bed pyrolysis of biomass is extended to enable the simulation of intensified autothermal operation. In this system, partial oxidation of char and pyrolysate species replaces an external heat source to supply the enthalpy of pyrolysis, greatly increasing the throughput of a given fast pyrolysis reactor. Oxidation reactions are compiled from CRECK and other literature sources and extended to cover the species found in pyrolysis products, including a derivation of the catalytic effect of ash on char combustion from experimental studies at Iowa State University (ISU). Results indicate a roughly 3-fold increase in biomass throughput for a given reactor volume at the pilot scale with minimal loss of valuable products, in agreement with published data from the 3 × 10 -2 m 3 reactor operated by ISU. Additionally, a proposal for a 250 ton/day commercial-scale biomass pyrolysis reactor is analyzed, showing that the same size reactor operated by heating the fluidizing gas externally would have only one-tenth the capacity; if operated by heating the sand externally, the sand would need to circulate at an impractical 0.7 bed volume per minute rate to maintain a 250 ton/day biomass throughput.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Analysis of Tar and Oil Derived from Pyrolysis and Copyrolysis of Waste Plastics and Biomass
Pyrolysis has been proposed as a potential technology for managing the growing volume of plastic waste generated worldwide. Co-pyrolysis of plastic waste with biomass is a promising technology for generating fuel and chemical products. However, this process generates tar as a waste product. The chemical properties of this tar have yet to be thoroughly analyzed. Further, this study presents the results of gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) of oil and tar obtained from the pyrolysis of pure plastics including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polystyrene (PS), and plastic-biomass mixtures. GC–MS analysis revealed the presence of C 7 –C 37 carbon-containing hydrocarbons, which include alkanes and alkenes as the dominant products. FTIR data revealed the presence of various functional groups, including alcohols, aldehydes, ketones, and carboxylic acids, indicating the complexity of the pyrolysis and copyrolysis oil obtained from waste plastics and biomass. TGA data show that tar from all four plastics has a higher decomposition rate, suggesting the presence of heavier hydrocarbons compared with their corresponding oils. This research will be of interest to researchers looking to advance the study of plastic and biomass waste management.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Modeling Heat Transfer and Reaction Kinetics of Biomass in Pyrolysis Feeding Systems
Biomass feedstocks can be used to produce low carbon-intensity chemicals and liquid fuels by displacing fossil-fuel sources. Pyrolysis is the thermal decomposition of biomass in the absence of oxygen and can be used to produce crude biofuels. A typical feeding mechanism for pyrolysis reactors is by lock hopper followed by a horizontal auger feeder. Particle agglomeration and plugging of the auger screw are regularly occurring phenomena that is detrimental to the process since it results in the need for periodic inspection and cleaning. The underlying mechanisms leading to agglomeration and plugging are unclear, but a working hypothesis is that heat from the reactor raises the temperature of the biomass in the feeder to the point at which preliminary decomposition reactions occur and produce "sticky" products. Using principles of heat and mass transfer, we derived one-dimensional differential equations for heat flow from the pyrolysis reactor through the auger feeder. Temperature profiles were solved from the system of one-dimensional differential equations using the shooting method. Subsequently, we used the temperature profiles as a one-way coupling to a reaction model for the biomass in the feeder. Kinetic models were adopted from the literature and used to predict the formation of intermediates, products, char, extractives, and metaplastics as well as phase changes along the auger feeder. Species were identified that correlated with softening of the biomass, causing it to become sticky and plug the feeder. We will discuss the details of this work, our findings, and the direction of future work that includes fully coupled transport and reaction-kinetics simulations.
BIOMASS FUELS↗
Mathematical Modeling of Multi-Phenomena Anisotropic Systems: Ejection of Primary Aerosols during the Fast Pyrolysis of Biomass
This study introduces a novel particle model for biomass fast pyrolysis, incorporating an anisotropic cylindrical particle to address mass and energy transport coupled with aerosol ejection, which previous models have overlooked. The main contribution lies in developing a model that considers aerosol generation in anisotropic cylindrical particles for the first time, addressing bubbling dynamics and bursting within the liquid phase. The population balance equation describes bubble dynamics and aerosol formation, capturing phenomena like nucleation, growth, coalescence, and bursting. The model employs the method of moments with bubble volume as an internal variable, substantially reducing computational costs by eliminating dependence on this variable. Results highlight the significant impact of anisotropy and particle size on aerosol ejection: smaller, less elongated particles experience faster heating, quicker conversion, and the increased accumulation of the liquid intermediate phase. Specifically, 1 mm diameter particles yield higher concentrations of metaplast and bio-oil aerosols, exceeding 15%, compared to concentrations below 11% for 3 mm particles. This model provides insights into aerosol structure (volume, surface area), aiding in understanding aerosol reactivity at the reactor scale.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Evaluation of Experimental and Predicted Vapor-Liquid Equilibrium Data for Systems Relevant to Biomass Fast Pyrolysis and Catalytic Upgrading
The experimental vapor-liquid equilibrium (VLE) data for the binaries relevant to the catalytic fast pyrolysis of biomass have been collected and analyzed using the NIST-COSMO-SAC and NIST-modified UNIFAC models. The existing inconsistencies in the experimental data and the predicted values are discussed. For VLE with furan derivatives, PTxy data are normally reported, and the predicted values are in good agreement with them. For phenolic compounds, the gas phase compositions are available for only 36 % of the points, most results originate from a few laboratories, and each system has been typically studied in a single laboratory. The binaries are identified where more experimental VLE data are required to evaluate quality of the existing experimental and predicted results.
09 BIOMASS FUELS↗
Optimization of Hydrogen Production from Pyrolysis of Biomass Waste [Poster]
We developed an CFD aided ML-based tool for rapid assessment and optimization of different compositions of biomass in a fluidized bed reactor. First, we use CFD to simulate fluidized bed reactors with known inlet biomass mixtures and obtain corresponding syngas yields. A lumped kinetic mechanisms represents the conversion of cellulose, hemicellulose, and lignin, as well as subsequent cracking of tars into non-condensable gases (H 2 , CO, CO 2 , CH 4 ). We use Bayesian analysis/optimization to obtain the ideal operational and mass flow conditions for hydrogen production.
08 HYDROGEN↗
Accelerating Catalyst Development for Biofuel Production through Multiscale Catalytic Fast Pyrolysis of Biomass over Mo2C
Advanced catalytic materials play an enabling role in producing renewable fuels and chemicals from biomass, thereby helping meet the global climate-change goals set forth by the Intergovernmental Panel on Climate Change. Herein, we present a multiscale approach to accelerate the catalyst-process development cycle for catalytic fast pyrolysis (CFP) of biomass over Mo2C. Mo2C has been shown to possess co-localized acidic and metallic sites and exhibit high activity for deoxygenation of biomass pyrolysis model compounds. However, critical knowledge gaps remain regarding the effectiveness of this catalyst for CFP of whole biomass. We address these knowledge gaps and demonstrate that Mo2C is effective at deoxygenating biomass-pyrolysis products in the presence of H2 but that it undergoes rapid selective and non-selective deactivation. The knowledge gaps addressed from this integrated study, targeting appropriate experiments across scales and feed types, enabled identification of critical modifications for advancing the CFP catalyst-process development cycle.
biofuels↗
Deactivation by Potassium Accumulation on a Pt/TiO 2 Bifunctional Catalyst for Biomass Catalytic Fast Pyrolysis
Biomass-derived feedstocks bring significant challenges to the longevity of the catalysts used for their conversion, and alkali metals, for example, K, in the feedstock have been widely ascribed as one of the important factors causing catalyst deactivation. To address this challenge, it is critical to understand the mechanism of catalyst deactivation caused by K accumulation to guide the improvement of catalysts and processes and the development of catalyst regeneration strategies. In this work, we report a deep understanding of the impact of K on a bifunctional Pt/TiO 2 catalyst, which is an efficient catalyst for the ex situ catalytic fast pyrolysis of biomass. We simulated the K-poisoning of Pt/TiO 2 catalysts by purposely loading different amounts of K (100-6000 ppm by weight) on the catalysts. A series of characterization approaches, including scanning transmission electron microscopy, Fourier transform infrared spectroscopy, and chemical titration, were combined with a kinetic assessment of multiple probe reactions to elucidate the mechanism of Pt/TiO 2 deactivation by K accumulation. At low K loadings (<800 ppm), K preferentially poisons the strong Lewis acid sites, leading to significantly reduced activity for acid-catalyzed alcohol dehydration. However, acetone condensation is less sensitive to the poisoning of strong Lewis acid sites. Reactions that occur on Pt sites or at the metal-support interface, including alkene hydrogenation, m-cresol hydrodeoxygenation (HDO), and CO oxidation, were not impacted. At high K loadings (>800 ppm), K starts to accumulate on the Pt-TiO 2 interfacial area, poisoning the interfacial active sites for HDO and CO oxidation reactions. We further found that the poisoning of the Pt/TiO 2 catalyst by K is reversible, and water washing can successfully remove the accumulated K and recover the activities for both alcohol dehydration and m-cresol HDO reactions.
09 BIOMASS FUELS↗
Advancements and challenges in the production of low-carbon fuels via catalytic fast pyrolysis of biomass through refinery integration and co-product generation
Creating pathways to renewable fuels, chemicals, and materials through improved catalyst formulations and integrated process development.
Yung, Matthew M.↗
Machine Learning Reduced Order Model for Cost and Emission Assessment of a Pyrolysis System
Biomass pyrolysis is a promising approach for producing economic and environmentally-friendly fuels and bioproducts. Biomass pyrolysis experiments show that feedstock properties have a significant impact on product yields and composition. Scientists are developing detailed chemical reaction mechanisms to capture the relationships between biomass composition and pyrolysis yields. These mechanisms can be computationally intensive. In this study, we investigate the use of a machine learning reduced order model (ROM) for assessing the costs and emissions of a pyrolysis biorefinery. Here, we developed a Kriging-based ROM to predict pyrolysis yields of 314 feedstock samples based on the results of a detailed chemical kinetic pyrolysis mechanism. The ROM is integrated into a chemical process model for calculating mass and energy yields in a commercial-scale (2000 tonne/day) biorefinery. The ROM estimated biofuel yields of 65 to 130 gallons per ton of dry biomass. This results in biofuel minimum fuel-selling prices of $2.62 to $5.43 per gallon and emissions of -13.62 to 145 kg of CO 2 per MJ. The ROM achieved an average mean square error of 1.8e-20 and a mean absolute error of 0.53%. These results suggest that ROMs can facilitate rapid feedstock screening for biorefinery systems.
09 BIOMASS FUELS↗
Corrosion Susceptibility of Cr–Mo Steels and Ferritic Stainless Steels in Biomass-Derived Pyrolysis Oil Constituents
In this work, to better understand and evaluate the corrosion performance of candidate structural steels and ferritic stainless steels for production, transport, and storage of biomass pyrolysis oils, corrosion studies were conducted in selected organic constituents of bio-oils, including catechol, formic acid, and their mixtures as well as lactobionic acid, using electrochemical impedance spectroscopy. R 2 , the resistance against corrosion reaction, was obtained by fitting measured impedance spectra into an equivalent circuit. The values of R 2 were then used to assess corrosion resistance of the steels in each organic constituent and mixture. Type 410 and 430 stainless steels were resistant to corrosion in all tested organic constituents, while 2.25Cr-1Mo steel was not. 9Cr-1Mo steel was corrosion resistant in catechol but not in the other mixtures that contained organic acids. On the basis of the results of this work, it is suggested that the corrosion resistance against organic acids is attributed to formation of a Cr-rich passive film that requires stainless steels with critical Cr levels in excess of approximately 11 wt %. In catechol-only solution, lower levels of Cr intermediate between that of 2.25Cr-1Mo steel and 9Cr-1Mo steel appeared sufficient.
36 MATERIALS SCIENCE↗
Investigation of Biomass Fouling on Screw Feeder in Preconversion of Pyrolysis
Biomass is a source of renewable energy and can undergo thermochemical processes to be converted into gaseous and liquid fuels. Thermal decomposition-induced biomass fouling on the screw feeder is a major challenge in preconversion of pyrolysis, leading to plugging of the feed line. Here, this work intends to gain fundamental understanding of the biomass fouling phenomena across the heat gradient on the screw feeder via a combination of materials characterization and thermal simulation. An actual screw feeder that failed because of biomass fouling was examined to reveal the deposit’s morphology, composition, and mechanical properties. Thermal simulations were developed for both the screw feeder and the wood particles being transported using a combined analytical and numerical approach. The simulated temperature profiles correlated well with the deposit observations, based on which potential mitigations were proposed from both the operation and screw design perspectives and supported by preliminary experimental validation.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗