Biomass Steam Gasification Research Articles

Comprehensive experimental assessment of biomass steam gasification with different types: correlation and multiple linear regression analysis with feedstock characteristics

In order to reveal the correlation between gasification behavior and products with feedstock characteristics, the steam gasification of 13 biomasses was investigated using a thermogravimetric analyzer and a fixed-bed reactor. Meanwhile, a multiple linear regression was used to construct correlation models. The results showed that cellulose content and crystallinity had the greatest influence on pyrolysis reactivity, which was reflected that the cellulose content was strongly positively correlated with the pyrolysis reactivity (Pmax = 0.77), while the lignin content and cellulose crystallinity were opposite. H/C, O/C ratios and SiO2 content had the greatest influence on gasification stage. O/C were strongly negatively correlated with gasification reactivity (Pmax = −0.81). But correlations of K and Ca contents were much less than that of Si. Husk has the best gasification performance than straw and woody with highest H2 and total gas yield of 28.26 and 68.93 mmol·g−1. H2 concentration and yield were significantly affected by the cellulose crystallinity and the fixed carbon content with positively correlation (P = 0.69–0.85). CH4 and CnHm were also influenced by them, but the trend was opposite to that of H2. Cellulose content, followed by SiO2 content mainly affected CO and CO2 and negatively correlated with CO while positively with CO2.

Design and experimental study of solar-driven biomass gasification based on direct irradiation solar thermochemical reactor

Solar-driven biomass steam gasification is a promising technology to produce H2-rich syngas, meanwhile achieve flexible storage of renewable energy. However, the solar gasification application also faces numerous challenges, due to its involved complex chemical reaction characteristics and the inherent the multi-physics energy conversion processes. This work designs a novel direct irradiation solar gasification reactor, with the improved optical acceptance structure and reasonable test module, and the wheat straw particle is selected as experimental sample. Employing a 9 kWe high flux solar simulator, the maximum temperature of reaction bed in this prototype reactor reaches to 1260 °C, with the average solar flux of 1171.3 kW/m2. With adjustable radiation flux as experiment factor, under the highest total radiation of 3.35 kW, the molar fraction of H2 in the produced syngas is 47.1 % with the energy upgrade factor of 1.15, and the cellulose component completes decomposition. Increasing the mass flow rate of steam reduces the syngas output while raising the H2/CO ratio of the syngas. In addition, smaller biomass particle size facilitates the reaction, thereby improving the conversion efficiency of direct irradiation gasification. The investigation results provide a meaningful reference for the efficient utilization of abundant solar and biomass energy.

Thermodynamic investigation of biomass-steam gasification in converter vaporisation flue for synthesis gas production

Biomass gasification for hydrogen production is a highly promising technology for energy conversion and utilisation. This paper proposed a novel technology for the injection of biomass and steam into the flue of a converter vaporisation to produce hydrogen-rich syngas. The feasibility of hydrogen generation through gasification between biomass, steam, and carbon dioxide in the high-temperature flue gas was investigated based on the thermodynamic principle of Gibbs free energy minimisation. The influence of gasification parameters on the composition of syngas was also explored. The results indicate that in the gasification process, biomass and steam injected into the converter vaporisation flue can effectively inhibit the generation of by-products such as tar. As the steam volume increases, the volume fraction of hydrogen in the product also increases, while the concentration of carbon monoxide decreases. By adjusting the steam-to-biomass ratio, syngas with a hydrogen content exceeding 20% can be produced. At a reaction temperature of 1200 °C, with a steam addition of 5%, a biomass addition of 8 g/L, and a [Formula: see text] ratio of 3, the gas products are composed of 25% hydrogen and 67% carbon dioxide. The process has the potential to achieve a hydrogen yield of up to 90%, a syngas yield of 94%, and a CO2 conversion rate of 70%. Additionally, the lower heating value of the syngas is measured at 11.24 MJ/Nm3. The research results have confirmed the viability of the new technology, thus establishing a theoretical foundation for the industrial implementation of injecting biomass and steam into the converter vaporisation flue to produce hydrogen-rich syngas.

CaO-based sorption-enhanced steam gasification of biomass for high purity H2 production: a modeling approach

CaO-based sorption-enhanced steam gasification of biomass for high purity H2 production: a modeling approach

A DFT study on catalytic cracking mechanism of tar by Ni or Fe doped CaO during biomass steam gasification

The presence of byproduct tar seriously reduces the efficiency and syngas quality in the biomass gasification process. The current understanding of CaO-catalyzed tar cracking mainly depends on experimental findings and conjecture about CaO properties. However, there is a significant lack of simulation studies that explore the conversion mechanism at the molecular level. In this work, the reaction mechanism of tar catalytic cracking on Ni or Fe doped CaO was studied using density functional theory simulation. The benzene, phenol and toluene were chosen as the tar model compounds to determine the influences of Ni and Fe on the adsorption characteristics of CaO surface. CaO doped with Ni and Fe increases its electron affinity and electron conductivity from 4.99 to 9.21/5.58 eV-1. It also enhances the interactions between the d-orbitals of Ni/Fe atoms and the p-orbitals of O atoms. The C-H activation of ·CH3 is the most kinetically and energetically feasible first step. The Ni-doped CaO and Fe-doped CaO decrease the energy barriers by 15.7 % and 21.7 %, respectively, compared with undoped CaO. Ni enhances the surface adsorption capacity for ·H radicals to form OH* at the O top site, whereas Fe promotes the stabilization of ·H radicals at the Ca-O vacancy. Through the enhancement of chemical adsorption capacity, improvement of electronic properties, introduction of electron reorganization and orbital hybridization, low-energy shift of energy levels, and generation of new energy states (from -0.85 to -1.64/-3.05 eV), the surfaces of Ni-doped CaO and Fe-doped CaO provide a favorable electronic environment for the tar catalytic cracking, which improves the reaction efficiency and selectivity.

Advancing hydrogen generation: Kinetic insights and process refinement for sorption-enhanced steam gasification of biomass utilizing waste carbide slag

Sorption enhanced steam gasification of biomass (SESGB) presents a promising approach for producing high-purity H2 with potential for zero or negative carbon emissions. This study investigated the effects of gasification temperature, CaO to carbon in biomass molar ratio [CaO/C], and steam flow on the SESGB process, employing carbide slag (CS) and its modifications, CSSi2 (mass ratio of CS to SiO2 is 98:2) and CSCG5 (mass ratio of CS to coal gangue (CG) is 95:5), as CaO-based sorbents. The investigation included non-isothermal and isothermal gasification experiments and kinetic analyses using corn cob (CC) in a macro-weight thermogravimetric setup, alongside a fixed-bed pyrolysis-gasification system to assess operational parameter effects on gas product. The results suggested that CO2 capture by CaO reduced the mass loss during the main gasification as the [CaO/C] increased. The appropriate temperature for SESGB process should be selected between 550 and 700 °C at atmospheric pressure. The appropriate amount of sorbent or steam could facilitate the gasification reaction, but excessive addition led to adverse effects. Operational parameters influenced the apparent activation energy (Ea) by affecting various gasification reactions. For each test, Ea at the char gasification stage was significantly higher than that at the rapid pyrolysis stage. The addition of CS notably increased H2 concentration and yield, while sharply reducing CO2 levels. H2 concentration initially rose and then fell with greater steam flow, peaking at 76.11 vol% for a steam flow of 1.0 g/min. H2 yield peaked at 298 mL/g biomass with a steam flow of 1.5 g/min, a gasification temperature of 600 °C and a [CaO/C] of 1.0. Increasing gasification temperature remarkably boosted the H2 and CO2 yields. Optimal conditions for the SESGB using CS as a sorbent, determined via response surface methodology (RSM), include a gasification temperature of 666 °C, a [CaO/C] of 1.99, and a steam flow of 0.5 g/min, under which H2 and CO2 yields were 464 and 48 mL/g biomass, respectively. CSSi2 and CSCG5 demonstrated excellent cyclic H2 production stability, maintaining H2 yields around 440 mL/g biomass and low CO2 yields (∼60 mL/g biomass) across five cycles. The study results offer new insights for the high-value utilization of agroforestry biomass and the reduction and resource utilization of industrial waste.

Feasibility of sustainable reusability of Ni/char catalyst for synthetic gas production via catalytic steam gasification

Ni/char catalyst is one of the most promising catalysts for enhancing gas production, particularly syngas from catalytic steam gasification of biomass. In the current study, one unmodified (Ni/MMchar) and two modified catalysts (Ni/NaMMchar and Ni/NaAceMMchar) were utilized to investigate the reusability potential of Ni/char catalyst for catalytic steam gasification of bamboo in a two-stage fixed-bed reactor including the changes in catalyst characteristics. N2 adsorption-desorption by BET, scanning electron microscope connected with energy-dispersive X-ray spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses were utilized for examining their characteristics. The findings indicated that the three catalysts could maintain the reusability potential in catalytic steam gasification of bamboo for twice cycles. The syngas reduction percentages in the second cycles of the catalysts ranged between 11.0 and 22.8 %. H2/CO ratios of all spent catalysts lined in the range of 4.10 − 2.45. The low heating values of syngas products were in the range of 8.83–8.19 MJ/Nm3. Considering the catalyst characteristics, the increasing cycles of catalyst operations induced carbon deposition, resulting in the reduction of specific surface areas. SEM-EDS images of the used catalysts appeared the coke layer and the Ni metal sintering on the surfaces. The uses of catalysts encouraged the transformation of Ni metal active site into NiO, Ni2O3 and Ni3C forms. These phenomena were the major causes of catalyst deactivation. The changes in the characteristics and catalyst activity controlled the gasification reactions, resulting in the catalyst deactivation and gaseous products.

Process Integration of Hydrogen Production Using Steam Gasification and Water-Gas Shift Reactions: A Case of Response Surface Method and Machine Learning Techniques

An equilibrium-based steady-state simulator model that predicts and optimizes hydrogen production from steam gasification of biomass is developed using ASPEN Plus software and artificial intelligence techniques. Corn cob’s chemical composition was characterized to ensure the biomass used as a gasifier and with potential for production of hydrogen. Artificial intelligence is used to examine the effects of the significant input variables on response variables, such as hydrogen mole fraction and hydrogen energy content. Optimizing the steam-gasification process using response surface methodology (RSM) considering a variety of biomass-steam ratios was carried out to achieve the best results. Hydrogen yield and the impact of main operating parameters were considered. A maximum hydrogen concentration is found in the gasifier and water-gas shift (WGS) reactor at the highest steam-to-biomass (S/B) ratio and the lowest WGS reaction temperature, while the gasification temperature has an optimum value. ANFIS was used to predict hydrogen of mole fraction, 0.5045 with the input parameters of S/B ratio of 2.449 and reactor pressure and temperature of 1 bar and 848°C, respectively. With the steam-gasification model operating at temperature (850°C), pressure (1 bar), and S/B ratio of 2.0, an ASPEN simulator achieved a maximum of 0.5862 mole fraction of hydrogen, while RSM gave an increase of 19.0% optimum hydrogen produced over the ANFIS prediction with the input parameters of S/B ratio of 1.053 and reactor pressure and temperature of 1 bar and 850°C, respectively. Varying the gasifier temperature and S/B ratio have, on the other hand, a crucial effect on the gasification process with artificial intelligence as a unique tool for process evaluation, prediction, and optimization to increase a significant impact on the products especially hydrogen.

Enhancing the catalytic H2 production performance of magnetic Ni-Fe2O3-C catalyst in biomass steam gasification using electromagnetic induction heating

In this study, a novel magnetic Ni-Fe2O3-C catalyst combined with electromagnetic induction heating in biomass steam gasification was proposed to enhance H2 production. Better catalytic performance for H2 production was observed with the Ni-Fe2O3-C catalyst under induction heating, resulting in an increase in H2 yield from 735.1 to 2271.2 mL/g-biomass (a 209.1 % enhancement). SEM, TGA and XRD analysis demonstrated a significant decrease in coking deposition, caking, and particle agglomeration of the Ni-Fe2O3-C catalyst under induction heating, while maintaining more active sites. Importantly, the benefits of induction heating were also applicable to different magnetic catalysts like Ni-Al2O3-C, Ni-ZrO2-C, and Ni-MgO-C. Experimental results revealed a logarithmic correlation between the increase in H2 yields due to induction heating and the magnetic saturation (Ms) of the catalysts. The Ni-Fe2O3-C catalyst, with a high Ms of 50.9 emu/g, showed the highest catalytic activity for H2 production under induction heating in this study.

H2-enriched gaseous fuel production via steam-gasification of biomass by using lime-based sorbents

The main objective of the present study was to compare the catalytic activity of selected limestones (Göynük, Dikmen, Polatlı Yolu, Kınık Tüneli and Köserelik) in terms of H2-rich syngas production from biomass gasification. In order to achieve this goal, an ASPEN plus-based model for biomass gasification integrated with carbonation reaction was developed. Tar formation was also considered and the gasification process was carried out based on Gibbs free energy minimization. A combined effect of temperature (600-710 °C), steam/biomass ratio, S/B (0.58-1.58), and limestone/biomass ratio, L/B (0-2.0) on gas composition, H2 yield (HY) and gas yield (GY) was also studied. An increase in both S/B and L/B was beneficial for H2 enrichment. The CO2 content declined sharply from 16.83 vol% to 10.28 vol% with increasing L/B from 0 to 1.5; however, a marginal reduction in CO2 content was observed with further increase in L/B. The highest HY (51.01 g/kg) was produced with Dikmen followed by Göynük, Polatlı Yolu, Kınık Tüneli and Köserelik. The results also showed that the limestone samples with high CaO content in general exhibits a better H2 production capacity than limestones with low CaO content. To the best of our knowledge, no simulation study has been presented to compare the catalytic activity of different limestones in terms of H2 production.

Revealing the nitrogen migration mechanism during pyrolysis and steam gasification of biomass: A combined ReaxFF MD and DFT study

The biomass pyrolysis/gasification technology takes advantages of high efficiency and carbon neutrality, which is promising for high value-added products fabrication. However, biomass possesses relatively high amount of N especially for seaweeds and municipal sludge wastes, and the lack of N migration mechanism has resulted in emission of N-containing pollutants and limited its industrial application. In this work, a simulation investigation combining reactive force field molecular dynamic and density functional theory calculations was performed to study the conversion mechanisms of N-containing species in the pyrolysis/gasification of biomass processes. The glutamic acid and cellulose were selected as the model compounds of N-containing and typical compositions of biomass, respectively, and six models containing multiple mass ratios of glutamic acid to cellulose and steam to feedstock were constructed. The results show that the majority of nitrogen in the original model is converted towards NH3-N (62%) during glutamic acid pyrolysis by direct cleavage, hydrogen capture, deamination, and decarboxylation. The presence of cellulose effectively inhibits the decomposition of NH3 at high temperature range, thereby increasing the yield of NH3-N (up to 70%) and restraining the conversion of nitrogen into mesomolecules. The introduction of H2O provides a substantial amount of •H radicals, which facilitates the conversion of nitrogen into NH3-N. During DFT calculations, eight reaction pathways for the formation of N-containing products were proposed on the basis of distribution of pyrolysis products. The glutamic acid cleavage reaction achieves the lowest energy barrier, and the deamination of glutamic acid towards a ternary cyclic ether is found to be the most feasible pathway for the NH3 production. This work can provide theoretical support for nitrogen pollutants mitigation during pyrolysis and steam gasification of biomass processes.

Investigation of regeneration cycles with different catalysts on steam gasification of biomass

In this work, agricultural biomass waste was gasified in a two-zone tubular reactor in the presence of steam. Firstly, during preliminary experiments the effect of temperature in the 1st and 2nd reactor zone, as well as the influence of catalysts and steam/raw material ratio was investigated, then the reusability of catalysts was also studied during ten regeneration cycles. Based on the preliminary results, in the 1st reactor zone a lower temperature was used (400 °C), where the yield of carbon dioxide was ∼55 %, which has a positive effect on numerous reactions, also it can be converted to carbon monoxide with proper catalysts with in-situ process. Regarding the temperature, it is important to be mentioned that a significant difference was observed in the yield of synthesis gas at 700 °C thus, the experiments were carried out using 700 °C in the 2nd reactor zone. A natural (Clinoptilolite) and a synthetic zeolite (ZSM-5), a mesoporous alumina (Al2O3) and a carbon dioxide capturing carrier (CaO) were selected and impregnated with nickel for further use and for enhancing the yield of synthesis gas and hydrogen during the gasification process. The utilization of catalysts helped the in-situ reduction of carbon dioxide while their performance in the gasification process during the regeneration cycles was also investigated. Henceforward, the tested Ni/ZSM-5, Ni/Al2O3 and Ni/Clinoptilolite, reduced the amount of carbon monoxide from the 5th regeneration cycles, while the amount carbon dioxide with the four mentioned catalysts was decreased by 15–35 mmol/g raw material, compared to the results obtained during thermal degradation.

Model-Based Predictive Control of a Solar Reactor

The present paper deals with the modelling and control of a solar reactor designed to produce syngas, by exploiting concentrated solar power. A model of the reactor based on the thermodynamic equilibrium is developed. Two model-based predictive control strategies are proposed: the first strategy (MPC strategy 1) aims to maintain the reactor's temperature at its nominal value whereas the second strategy (MPC strategy 2) aims to maintain the reactor's temperature at its nominal value, while maximizing the use of solar energy. Finally, these strategies are compared to a reference strategy, which is based on a combination of a rule-based controller and an adaptive PID controller with optimized gains. The robustness of the MPC controller to forecast errors is also studied by testing different DNI forecasting models. Parts of this paper were published as journal articleKarout, Y.; Curcio, A.; Eynard, J.; Thil, S.; Rodat, S.; Abanades, S.; Vuillerme, V.; Grieu, S. Model-Based Predictive Control of a Solar Hybrid Thermochemical Reactor for High-Temperature Steam Gasification of Biomass. Clean Technol. 2023, 5, 329-351. https://doi.org/10.3390/cleantechnol5010018

Hydrogen production from biomass steam gasification: Experiment and simulation

In pine chips gasification experiment, at 700 °C and 15 % H2O, with the mass ratio of Ca90Fe10/B to 1.5, the H2 yield is 210.50 mL/g. The H2 yield improves by 2.39 times and the tar yield decreases by 16 % compared to without CaO. In the pine chips gasification simulation with the system's own thermal equilibrium, at 700 °C, the heat release of Ca90Fe10 adsorption of CO2 is 56.91 MJ/h for Ca90Fe10/B mass ratio of 1.5, and the required O2 inflow is 1.9 kg/h, the molar flow of H2 is 0.58 kmol/h. To achieve material circulation, 0.5 kg/h of CH4 is added to the calciner for combustion to satisfy heat absorption of CaCO3 to regenerate CaO, which consumes 2.0 kg/h of O2. The whole cycle O2 consumption is 3.90 kg/h, which is 1.02 kg/h less than without CaO, and the H2 yield has increased by 1.35 times.

Numerical Study on the Steam Gasification of Biomass in a 100 kW Dual Fluidized Bed Gasifier

Numerical Study on the Steam Gasification of Biomass in a 100 kW Dual Fluidized Bed Gasifier

Hydrogen-Rich Syngas Production via Dry and Steam Reforming of Methane in Simulated Producer Gas over ZSM-5-Supported Trimetallic Catalysts

This study investigated the production of hydrogen-rich syngas from renewable sources using durable and efficient catalysts. Specifically, the research focused on steam methane reforming (SRM) and dry methane reforming (DRM) of simulated producer gas from biomass steam gasification in a fluidized bed reactor. The catalysts tested are ZSM-5-supported nickel-iron-cobalt-based trimetallic catalysts in different ratios, which were prepared via the wet impregnation method. Synthesized catalysts were characterized using XRD, BET, H2-TPR, and SEM techniques. The results of the SRM with the simulated producer gas showed that the 20%Ni-20%Fe-10%Co/ZSM-5 trimetallic catalyst, at a gas hourly space velocity (GHSV) of 12 L·h−1·g−1 and reaction temperature of 800 °C, achieved the highest CH4 conversion (74.8%) and highest H2 yield (65.59%) with CO2 conversion (36.05%). Comparing the performance of the SRM and DRM of the simulated producer gas with the 20%Ni-20%Fe-10%Co/ZSM5 at a GHSV of 36 L·h−1·g−1 and 800 °C, they achieved a CH4 conversion of 67.18% and 64.43%, a CO2 conversion of 43.01% and 52.1%, and a H2 yield of 55.49% and 42.02%, respectively. This trimetallic catalyst demonstrated effective inhibition of carbon formation and sintering, with only 2.6 wt.% carbon deposition observed from the thermo-gravimetric analysis of the used catalyst from the SRM of the simulated producer gas, thus promoting the potential of the ZSM-5-supported trimetallic catalysts in methane reforming.

Hydrogen-rich syngas production and insight into morphology-kinetics correlation for furfural residue steam gasification in a bubbling fluidized bed

Biomass steam gasification technology has attracted considerable interest for its potential of low-cost and high-efficiency in hydrogen production. However, there is still a large knowledge gap regarding morphology-kinetic correlation. To avoid the technical difficulties of thermogravimetric analysis and fixed bed studying steam gasification kinetics, this work pursues the design and building of a visualized bubbling fluidized bed with an online analysis system. According to the morphology evolution of biomass real-time observed by a high-speed camera, the shrinkage ratio during high-temperature gasification in a fluidized bed has been first deduced. Moreover, based on accurate monitoring of the gas products releasing behavior, multiple kinetic models were applied to evolve the activation energy at different carbon conversion efficiencies (CCE). The results showed that the synergistic regulation of steam concentration and temperature achieved a high H2/CO ratio (2.46) and H2 yield (869.5 L/kg). A comparative analysis of the coupling relationship between shrinkage ratio, activation energy and CCE successfully separated the volatile precipitation and char gasification processes. It was also revealed that the shrinkage rate peaked at the transition from pyrolysis to char gasification (20 % CCE). At CCE below 20 %, the reaction mechanism tended towards a nucleation and growth mechanism. As CCE reached 20 %, the reaction form shifted. Subsequently, the chemical reaction mechanism controlled the main reaction, and the average apparent activation energies of H2, CO2 and CO were 86.76, 31.27 and 39.90 kJ/mol, respectively. This work provides new insights and a theoretical basis for understanding and modeling the biomass steam gasification process in fluidized beds.

Simulation of the deoxygenated and decarburized biomass cascade utilization system for comprehensive upgrading of green hydrogen generation

Steam gasification of biomass is of great significance for achieving efficient hydrogen-rich syngas production. However, the yield and the quality of H2 in the product require further improvements. In this study, a strengthened biomass cascade utilization system via synergistic deoxygenation and decarburization is investigated. The system is composed of a deoxygenated and decarburized gasification reactor and a deoxidizer and decarburizer material regenerator. In the gasification reactor, a series of deoxidizer and decarburizer materials, CaO-Fe (Ca: Fe > 1.0), are applied for accomplishing high-quality hydrogen production; In the regenerator, the deoxidizer and decarburizer material is regenerated (CaCO3+ Ca2Fe2O5→CaO–Fe) with released gas utilization. The effects of gasification temperatures, Ca/Fe, H2O/C, and (CaO + Fe)/B mole ratios are evaluated by Aspen Plus, achieving comprehensive optimization of the parameters. The H2 yield reaches 68.16 mol s−1 kg−1 biomass and the H2 concentration is up to 93.58 vol%, which increases by 254.45 % and 109.87 % compared with the results without deoxygenation and decarburization. Additionally, the deoxidizer and decarburizer material can be completely regenerated via released gas reduction, thereby ensuring the consistent looping of the entire system. This paper sheds light on the synergistic deoxygenation and decarburization methodology for biomass-to-hydrogen generation, which provides a robust guidance for further experiments in the future.

High quality syngas production from catalytic steam gasification of biomass with calcium-rich construction waste

High quality syngas was produced by steam gasification of biomass waste with catalyst derived from disposable calcium-rich construction waste after calcination (C-CCW) at high temperature. The effects of biomass gasification parameters including operating temperature, catalyst loading amount and biomass varieties on characteristics of biomass steam gasification were studied. Experiment results indicate that the total gas yield of produced gas derived from steam gasification of corn stalk increased markedly with elevated reaction temperature and catalyst loading amount. Addition of C-CCW on biomass significantly promoted the decomposition of tar in syngas during steam gasification resulting in higher gas yield and better gas quality. The considerable H2 yield (29.70 mmol/g-biomass), CO yield (4.14 mmol/g-biomass), CH4 yield (3.40 mmol/g-biomass), and H2/CO mole ratio (7.17) were achieved after steam gasification of corn stalk with 10.0 wt% C-CCW at 750 °C. There were significant differences in steam gasification performance of different biomass samples owed to the properties of biomass feedstock. Distinct saturation capacities of C-CCW loading amount were observed for enhancing gasification and eliminating tar during steam gasification of diverse biomass feedstocks. C-CCW appeared to have comparable catalytic effect to that of pure CaO and therefore could be an alternative of calcium-containing catalyst.

Numerical investigation on the influence of immersed tube bundles on biomass gasification in industrial-scale dual fluidized bed gasifier

Immersed tubes play a pivotal role in enhancing fluidization quality within fluidized beds by effectively disrupting bubbles. However, the effect of such internals within a large-scale gasification apparatus remains unclear. Consequently, this study focuses on numerically simulating biomass steam gasification within an industrial-scale dual fluidized bed gasifier that features immersed tube bundles using the multiphase particle-in-cell method. In this method, particles with identical properties are grouped, and the interparticle collisions are model via the solid stress to improve computational efficiency. The numerical model has been well verified with experiment in terms of bed pressure drop, solid recirculation and chemical reactions. Some main conclusions are shown as follows. Immersed tubes significantly alter the motion of gas and particles in the gasifier. The presence of immersed tubes can ameliorate solid entrainment and avoid excess particles escaping from the gasifier. The asymmetrical structure of the gasifier results in asymmetrical distribution of gas temperature and gas species. Increasing the number of immersed tubes slightly enhances particle temperature near the loop seal outlet. The radial biomass dispersion coefficient and axial sand dispersion coefficient decrease about 40.9 % and 28.9 % when increasing the immersed tube number from three to nine. The results provide enhanced understanding of the role of immersed tubes in altering gas-particle interactions and fluidization dynamics in industrial-scale fluidized bed gasifier.