Simulated Gas Research Articles

Extensive Experimental Characterization with Kinetic Data for the Gasification Simulation of Solid Biofuels

In this study, biomass–specific gasification data is experimentally collected for numerical simulations of fixed–bed reactors. Since biomass properties vary, it is crucial to have characteristic biomass data. Extensive data is collected to determine an appropriate description of specific biomass behavior, including basic data (e.g., heating value, size, densities, ultimate and total analysis etc.), biomass pyrolysis and heterogeneous gasification reaction data. Heterogeneous reactions were comparatively investigated in the forms of powder, particles, and a fixed–bed. The powder was investigated in depth with CO2, O2, and H2O (gas fraction 5–20 vol.%; temperature CO2, O2 and H2O, respectively, at 730–790 °C, 360–405 °C, 720–780 °C), while particle reactions and fixed–bed reaction were only studied with CO2. A model description for a fixed–bed batch reactor was applied, modified, and compared to experimental fixed–bed batch reactor results. This study concludes that determining the appropriate characteristic particle size and parameters for the porous structure of specific biomass char is essential for simulation based on preliminary biomass characterization. Therefore, in future investigations, the description for biomass-specific differences between powder, single particles, and bulk of biomass char may be of greater focus, also taking into consideration O2 and H2O.

Aspen plus simulation model of municipal solid waste gasification of metropolitan city for syngas production

It is apparent that the population, in general, is increasing and this rise in population increases both the waste production and energy requirements. The main objective of this study to tackle the increasing demand for energy and recycling waste into energy. We will be using Waste to Energy (WTE) technique to convert MSW into energy such as bio-fuel, Hydrogen-rich gas or Syngas. The model of simulation of steam gasification of MSW used in this study is based on ASPEN PLUS. Temperature, the ratio of steam to MSW, and the ratio of air to MSW have all been adjusted in a wide range. For the production of syngas, the impact of carbon conversion efficiency (CCE) and cold gas efficiency (CGE) has been studied. The results showed that by increasing the temperature from 700 °C to 1300 °C the H2 concentration increased from 37 to 51 mol%, CO concentration increases from 35 to 40 mol% and CO2 concentration decreases from 5 to 0.025 mol%. CGE also decreases from 95 to 82% while CCE increases from 80 to 85%. By increasing the steam to MSW ratio from 0.05 to 0.8 mass fraction the H2 concentration increased from 34 to 44 mol% but is maximum at 0.35 at which it is 53 mol%, CO concentration decreases from 43 to 16 mol% and CO2 concentration increases from 0.025 to 8.5 mol%. CGE and CCE also decreases from 94 to 45% and 90 to 44% respectively.And lastly by increasing the air to MSW ratio from 0.01 to 0.5 mass fraction the H2 concentration decreases from 47 to 39 mol% but peaks at 0.05 at which it is 48 mol%, CO concentration decreases from 41 to 31 mol% and CO2 concentration increases from 0.085 to 3.5 mol%. CGE and CCE also decreases from 92 to 55% and 87 to 70% respectively. To compare our data with the base case we have kept temperature at 900 °C S/MSW ratio at 0.11 and air/MSW ratio at 0.05 and it is concluded that our simulation is inline with the base case as our results are off by just 1–3% in terms of yield.

Numerical simulation of plasma gasification of oil-based drilling cuttings

In this paper, ASPEN PLUS commercial software is used to simulate the plasma gasification process of oil-based drilling cuttings, and the numerical simulation results are analyzed in detail. The conclusions can provide theoretical guidance for subsequent experiments and practical engineering applications. A set of reactor models suitable for gasification of such substances was established by using Gibbs? free energy minimization principle, and the accuracy of the model was verified by comparing the numerical simulation results with the experimental results. In this model, the effects of plasma torch power, air equivalent ratio, moisture content of feed, and the amount of CO2 added on the gasification results were simulated. Through systematic analysis, the optimal gasification parameters are determined output power of plasma torch is 27.5 kW, air equivalent ratio is 0.26, moisture content of feed is 6%, and the amount of CO2 added is 6 kg per hour.

Investigation of gasification reactions and H2/CO ratio analysis for rice husk air gasification simulation

The syngas generated during gasification process is used for industrial process heat, power generation and chemical feedstock production. Gas composition, H2/CO and CO/CO2 ratios are the deciding factors for producer gas end-use. In the present work, rice husk air gasification simulation is carried out by non-stoichiometric equilibrium model using Gibbs free energy minimization by FactSage 6.3 software. Influence of gasification reactions and effect of temperature, equiv?alence ratio on gas composition was studied. The analysis was carried out to study the effect of operating conditions on producer gas heating value and gasification efficiency at various H2/CO ratios. Increase in temperature improves H2 and CO formation in water gas reaction and reduction of H2 formation was observed in water gas shift reaction due to endothermic behavior change. For all the values of the equivalence ratio, ?, an increase in temperature reduces the H2/CO and enhances the CO/CO2 ratio due to higher CO formation. For a particular, ?, value, maximum gas heating value and gasification efficiency were obtained at low H2/CO ratio.

Numerical simulation of biomass gasification in fluidized bed gasifiers

Numerical simulation of biomass gasification in fluidized bed reactors faces several challenges including proper modeling of the physical and chemical processes involved in the gasification and numerical stiffness of the two-phase dense particle flow problem. In this paper, the multi-phase particle-in-cell (MP-PIC) model coupled with a recently developed distribution kernel method (DKM) and a new one-step pyrolysis model are employed to investigate biomass gasification in two lab-scale fluidized bed gasifiers (FBGs). The results are evaluated by comparing with the results from the Particle Centroid Method (PCM) and experimental measurements. The performance of DKM is shown to improve the robustness of the model and the new pyrolysis model is shown to improve the sensitivity of the yields of gasification products to operating temperature. The simulation results using the new pyrolysis model agree well with the experimental data under different gasification conditions. The model is shown to be able to capture the trend of gas products with respect to variations of steam/biomass ratio (SR) and operating temperature (Tr). The mechanisms of the formation of gas products are analyzed based on the numerical results. By increasing the SR and Tr, the production of H2 and CO2 is shown to increase while the production of CO and CH4 to decrease. It is shown that varying the steam/biomass ratio in the range of 0.8∼2.0 has a minor effect on the pyrolysis process and heterogeneous reactions, while homogeneous reactions are significantly affected, leading to changes in the final composition of the gas products. Varying the gasifier temperature Tr has on the other hand a crucial effect on the pyrolysis process and as such a significant impact on the gasification products and carbon conversion.

Simulation of sorption-enhanced gasification: H[formula omitted]O staging to a circulating fluidised bed gasifier to tailor the producer gas composition

Sorption-enhanced gasification (SEG) is an advanced gasification technology for biofuel and biochemical synthesis processes. The SEG process allows tailoring of the producer gas composition for different synthesis processes by adjusting the temperature of the gasifier. Conventionally, the solids circulation rate from the combustor to the gasifier has been used to tailor producer gas composition. In this study, H2O staging is investigated in a circulating fluidised bed (CFB) gasifier as an alternative approach. The H2O staging can be used to decrease the riser temperature locally to enhance the main chemical reactions. The H2O staging as gas and liquid phases were considered in this study. Also, reactor cooling was combined with the staging. A validated one-dimensional CFB gasifier model was used to investigate the process. The simulation results indicate that H2O staging and cooling enhance the gasifier’s limestone carbonation and water-gas shift reactions. Thus, allowing to tailor the producer gas composition directly by adjusting the gasifier’s operating parameters. The methods investigated increase flexibility for operating the SEG CFB gasifier and the reactor system. Understanding different operation methods of the process and their impact on the system’s operation enables more flexible use and design of the gasification process.

Optical Properties of Coal after Ex-Situ Experimental Simulation of Underground Gasification at Pressures of 10 and 40 bar

Coal gasification experiments were carried out in a reactor used to simulate underground coal gasification (UCG) processes under ex situ conditions at pressures of 10 and 40 bar. Changes in the optical properties of the organic matter were analyzed and the influence of temperature on coal during the UGC process was subsequently determined. The values of the true maximum reflectance determined for the gasification residue at pressures of 10 and 40 bar, and at distances of 0.75 and 1.75 m, reached a level corresponding to semi-graphite. Furthermore, it was found that the values of the true maximum reflectance and bireflectance decrease with increasing distance from the reactor chamber inlet. In addition, the results show that, regardless of the pressure used during the experiment, the temperature influence on the coal decreased with increasing distance from the reactor chamber inlet. The true temperatures operating during the experiment were higher than those recorded by the thermocouples, regardless of the pressure used. However, it was found that the distance at which the influence of temperature on the coal is still marked during the gasification process depends on the pressure used in the experiment. For example, in the case of the experiment at a pressure of 10 bar, the estimated distance is approximately 60 m, while for a pressure of 40 bar, it is approximately 35 m. These results can, and should, be taken into account for the planning of an UGC process.

Experimental simulations of methane-oriented underground coal gasification using hydrogen - The effect of coal rank and gasification pressure on the hydrogasification process

This paper presents a series of surface experimental simulations of methane-oriented underground coal gasification using hydrogen as gasification medium. The main aim of the experiments conducted was to evaluate the feasibility of methane-rich gas production through the in situ coal hydrogasification process. Two multi-day trials were carried out using large scale gasification facilities designed for ex situ experimental simulations of the underground coal gasification (UCG) process. Two different coals were investigated: the “Six Feet” semi-anthracite (Wales) and the “Wesoła" hard coal (Poland). The coal samples were extracted directly from the respective coal seams in the form of large blocks. The gasification tests were conducted in the artificial coal seams (0.41 × 0.41 × 3.05 m) under two distinct pressure regimes - 20 and 40 bar. The series of experiments conducted demonstrated that the physicochemical properties of coal (coal rank) considerably affect the hydrogasification process. For both gasification pressures applied, gas from “Six Feet” semi-anthracite was characterized by a higher content of methane. The average CH4 concentration for “Six Feet” experiment during the H2 stage was 24.12% at 20 bar and 27.03% at 40 bar. During the hydrogasification of “Wesoła" coal, CH4 concentration was 19.28% and 21.71% at 20 and 40 bar, respectively. The process was characterized by high stability and reproducibility of conditions favorable for methane formation in the whole sequence of gasification cycles. Although the feasibility of methane-rich gas production by underground hydrogasification was initially demonstrated, further techno-economic studies are necessary to assess the economic feasibility of methane production using this process.

CFD-DEM Simulation of Particle Fluidization Behavior and Glycerol Gasification in a Supercritical Water Fluidized Bed

In this study, a mathematical model of hydrogen production from glycerol gasification in supercritical water was established based on the CFD-DEM method. The fluidization process of a supercritical water fluidized bed and the effects of bed height and feed structure on particle distribution and residence time of feedstock were analyzed. Additionally, the temperature field in the fluidized bed, the reaction rate distribution of each reaction and the influence of wall temperature on gas yields were also studied. The simulation results show that the bubble channel is easy to form along the wall at one side of the feed inlet. When the initial bed height is high, and the double symmetric feed inlet structure is used, the residence time of the feedstock is prolonged. The pyrolysis of glycerol mainly occurs in the middle and lower part of the fluidized bed reactor, and the reaction rate of the water gas shift reaction and methanation reaction are highest near the outlet, and a high wall temperature is conducive to the glycerol gasification.

Numerical simulation of double chemically reacting particles moving in hot O2/CO2 atmospheres

The entrained-flow gasifier operates with large numbers of discrete particles, and an individual particle has an impact on the reactions of the particles nearby. Therefore, taking the double particles as an example to explore the conversion process offers a reference for developing sub-models that available for reactor-scale gasification simulation. In this study, a CFD-based model was developed to describe the reaction of double coal char particles in O2/CO2 atmospheres. The influence of Reynolds number and oxygen mole fraction on the flame morphology evolution, the Stefan flow, and the carbon consumption rate were discussed to understand the conversion of the double particles. The results show that the severe reaction area around the double particles gradually migrates towards the front of particle 1 with the increase of oxygen mole fraction, and the area of high-temperature zone decreases multi-modally with the increase of both factors. Reynolds number is the main factor affecting mass transfer. The overall carbon consumption rates of the double particles grow linearly with the increase of the oxygen mole fraction, and the rate of particle 1 is greater than that of particle 2. The Reynolds number has a greater effect on intensifying the difference between the carbon consumption rates of the double particles.

Fully resolved direct numerical simulation of single coal particle gasification in supercritical water

Supercritical water gasification is a promising technology in the context of carbon neutrality, since it converts coal into hydrogen and easily-captured CO2. A fully resolved direct numerical simulation of single particle gasification in supercritical water is conducted in this paper in order to investigate process details at particle scale. To handle the shrinking reactive particle, a directional ghost-cell immersed boundary method is used with a general Robin-type boundary condition at the interface. Detailed flow field and interphase heat/mass transfer near the reactive coal particle are revealed and compared with standard non-reactive cases – used for validation. They are found to be significantly affected by the combined effect of the reaction-induced Stefan flow, particle shrinking, species generation or destruction, and reaction heat release. The chemical processes are then studied with special attention on the gas-phase reaction time-scale. This study delivers a detailed understanding of coal particle gasification in supercritical water, and provides a first successful test of efficient numerical methods needed for large-scale supercritical water gasification simulations.

Evaluation of Different Oxygen Carriers for Chemical Looping Reforming of Toluene as Tar Model Compound in Biomass Gasification Gas: A Thermodynamic Analysis

A thermodynamic study on a toluene chemical looping reforming process with six metal oxides was conducted to evaluate the product distribution for selecting an appropriate oxygen carrier with thermodynamic favorability towards high syngas yield. The results show that a suitable operation temperature for most oxygen carriers is 900 °C considering syngas selectivity and solid C formation whether the toluene is fed alone or together with fuel gas. The syngas selectivity of all oxygen carriers decreases with the increasing equivalence ratio, but the decrease degrees are quite different due to their different thermodynamic natures. With the increasing amounts of H2 and CO, the syngas selectivity for various oxygen carriers correspondingly decreases. The addition of CO2 and H2O(g) benefits reducing the solid C formation, whereas the addition of CH4 leads to more solid C being produced. Under the simulated gasification gas atmosphere, a synergetic elimination of solid C and water–gas shift reactions are observed. In terms of syngas selectivity, Mn2O3 possesses the best performance, followed by CaFe2O4 and Fe2O3, but NiO and CuO exhibit the lowest performance. BaFe2O4 presents a high H2 selectivity but a very poor CO selectivity due to the formation of BaCO3, which has a high thermodynamic stability below 1200 °C. Nevertheless, Mn2O3 is more likely to form solid C than feeding toluene alone and has a lower melting point. Considering syngas selectivity, carbon deposit and melting point, CaFe2O4 exhibits the highest performance concerning the tar chemical looping.

Destruction of biomass tar model compound in a rotating gliding arc plasma catalytic system: Contribution of typical transition metals in Ni-based bimetallic catalyst

In this work, the destruction of toluene as a biomass tar model compound has been investigated in a rotating gliding arc (RGA) plasma catalytic system focusing on understanding the contribution of typical transition metals (Fe, Co, Cu) in Ni-based bimetallic catalyst. Investigations were conducted to elucidate their synergy with plasma under simulated gasifier gas (SGG) to destruct toluene and their effect on value-added benefits such as the enhanced heat content of the reacted producer gas. Results showed that the N2 environment offered better performance than the SGG environment, especially at high tar concentration, due to a more abundance of N2 excited species. The loading of Ni on the Al2O3 catalyst remarkably enhanced the tar conversion from 80.7% to 93.1%. Except for the NiFe, the bimetallic catalysts improved conversion and reduced specific energy consumption (SEC). Primarily, the NiCu catalyst provided a maximum tar conversion of up to 94.3% and significantly enhanced the heat content of the producer gas by 29% from that of the SGG. The minimum SEC of 64.5 kWh/kg was achieved by the NiCo, which also showed the best sintering resistance. In the 24-hour plasma-catalytic operation, NiCu and NiCo showed excellent stability with only a slight drop in the tar conversion (∼94% to ∼ 91%) after 10–12 h. Analysis of by-products indicated back spillover of OH and O, which could help clean the metal surface. Thermogravimetric analysis of the spent catalyst indicated that the coke deposited is likely composed of the aromatic compounds of boiling point in the range of 100 °C to 300 °C.

INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION

Link for citation: Ermolaev D.V., Daminov A.Z. Influence of the oxidizer on the formation and purification efficiency of acid gases produced during asphaltene gasification. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2022, vol. 333, no. 4, рр. 215-223. In Rus.
 The relevance of the study is determined by the need to understand the influence of the oxidizer on the formation of acid gases (CO2, H2S, COS and CS2) during thermal decomposition of high-viscosity hydrocarbons. This is important for predicting the purification efficiency of the produced gasification products and estimating the economic costs. The aim: using the simulation to study the effect of an oxidizer in the form of steam on the composition and properties of asphaltene gasification products obtained from natural bitumen, as well as to determine the cleaning efficiency depending on the amount of steam and the absorbent based on NaOH water-alkaline solution. Object: asphaltene of natural bitumen of Ashalchinskoe field of the Tatarstan Republic (Russia), oxidizer in the form of steam, the value of which varied from 0,1 to 1 depending on the amount of asphaltene. Methods: simulation of asphaltene gasification and acid gas absorption taking into account influence of an oxidizer in a form of steam with regard for basic chemical kinetics, ultimate analysis and TGA. Simulation results of gasification and absorption showed that steam used as an oxidizer during asphaltene gasification has a significant influence on the composition and properties of gasification products, as well as on the purification of syngas. With the increase of steam, a parabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2. The calorific value of syngas decreases from 11,3 to 7,2 MJ/m3 and the cold gas efficiency increases from 53,4 to 62,5 % due to growth of syngas yield. As the amount of steam increases, the amount of absorbent decreases and the purification efficiency of acid gases rises. Thus, the amount of absorbed CO2 increases by 20,7 % while the absorbent decreases by 6,7%. At the same time the amount of absorbed H2S increased by 0,39 % with decrease of NaOH by 40,9 %.

Study of increasing thermodynamic efficiency and hydrogen amount in the process of solid fuels and biomass gasification

The effect of fuel composition such as hard coal and biomass in fluidized bed on the thermodynamic efficiency of three gasifier types, low heating value (LHV) and syngas composition was studied by simulation in CFD program. The paper presents various small gasification systems with fluidized bed of water-coal mixture and water-biomass mixture both with oxygen (air) and without oxygen. The work presents the extended mathematical model of gasification process taking into account also 13 kinetic chemical reactions enabled to apply them in CFD program. The chemical model is based on surface reactions given in the model of Equivalent Reactor Network (ERN) in Ansys Energetico. Simulation of gasification of different reactor designs enabled to obtain the mass concentration of chemical compounds in the syngas which influenced on thermodynamic efficiency and LHV. Additionally, heating of the gasifier walls by electrical system without air gives higher mass ratio of hydrogen (15%) and carbon monoxide (75%) in the syngas than in the oxidized gasification system. The simulation tests showed high thermodynamic efficiency, taking into account the exergy above 80%, both for the oxygen gasification of hard coal-slurry and biomass as well as for the externally heated gasifier without the supply of oxygen. The highest thermodynamic efficiency 90.5% was obtained during gasification of energy willow in the oxidation reactor due to the large difference in LHV of syngas and fuel. Obtaining the maximum possible mass ratio of H2 in syngas and a high thermal efficiency for the OXGR system from the gasification of subbituminous coal dust occurs at a ratio C/O2 = 0.314 and at almost stoichiometric ratio of C/H2O = 0.63. In the case of gasification of biomass in the form of finely ground energy willow in the OXGR system, these ratios were respectively: O2/C = 1.82 and C/H2O = 0.47. While maintaining the almost stoichiometric ratio C/H2O = 0.75, resulting from the water-gas shift reaction, low heating value of the syngas for the analysed gasification systems was over 25 MJ/kg. The paper shows comparison of mass fractions of CO, H2, H2O, H2S, CO2, O2, CH4, tar and other chemical compounds in the syngas. Application of the gasification reactor with external heated walls and without oxygen inflow produces the syngas without tar and volatile species in comparison to the systems with additional oxygen supply. In oxidized reactors the syngas contains a large amount of CO2 about 25–30% of total mass.

Process simulation and optimization of groundnut shell biomass air gasification for hydrogen-enriched syngas production

In this study, a detailed steady-state equilibrium simulation model was designed using ASPEN Plus software to analyze and assess the efficiency of the groundnut shell biomass air gasification process. The developed model includes three general stages: biomass drying, pyrolysis, and gasification. The predicted results are quite similar to those found in the literature, which is consistent with simulation results being validated against experimental data. The effect of different operating parameters, like the gasification temperature, gasification pressure, and the equivalence ratio (ER), on the syngas composition and H 2 /CO ratio is investigated using sensitivity analysis. The findings of the sensitivity analysis revealed that raising the temperature preferred H 2 and CO production, whereas increasing the pressure has favored CO 2 and CH 4 production. Increasing the ER value also boosted CO and CO 2 yield. Moreover, in an effort to optimize the amount of H 2 generated within the process, the sensitivity analysis was used to evaluate the simultaneous effect of operational parameters on the molar fraction of H 2 . To maximize H 2 as a desired product, the following operating parameters were achieved: gasification temperature of 894 °C, gasification pressure of 1 bar, and ER of 0.05, resulting in an H 2 molar fraction of 0.64. • A new approach of pyrolysis/gasification process is developed for H 2 production. • Groundnut shell biomass gasification process is studied under relevant condition. • Gasification model is developed using Aspen Plus software. • Sensitivity analysis of operating condition on the process performance is studied. • Optimum operating condition to maximize syngas production have been determined.

Optimization of Algae Residues Gasification: Experimental and Theoretical Approaches

Abstract Gasification is one of the thermochemical pathways of biomass conversion that produces synthesis gas, tar, and char. This study aims to convert algal residues via gasification at different operating conditions; temperature, equivalence ratio, and biomass loading. The study was carried out in 3 steps; (1) testing the outcomes of temperature and loading effects on synthesis gas yield, (2) experimental optimization of gasification via Design Expert, and (3) theoretical optimization of gasification via Aspen Plus simulation. Temperature and equivalence ratio highly influenced synthesis gas composition, while loading demonstrated less effect on the synthesis gas composition. The experimental and simulated gasification outcomes were compared to obtain optimized conditions that produce high H2 and CO yields. The data were validated using root mean square error. The optimized temperature, loading, and equivalence ratio were found for both algal residues that produced 36.38 and 13.28mol% of H2 and CO, respectively for lipid extracted algae (LEA) and 47.99 and 26.05mol% of H2 and CO, respectively for fucoidan extracted seaweeds (FEA). There was a considerable variation between experimental and simulated data due to the simulation and experimental limitations. The average Carbon Conversion Efficiency values were 66.36 and 80.42% for LEA and FES, respectively, denoting that LEA produced less carbon-containing products, while FES produced more carbon-containing products. In conclusion, LEA gasification yielded more H2 while FEA produced more CO.

Carbon Aerogel-Supported Iron for Gasification Gas Cleaning: Tars Decomposition

Tar removal from gasification gases is a determinant step to guarantee the operational feasibility of gasification-to-chemicals/energy systems. However, this is a very complex process requiring catalytic materials to proceed under reasonably low temperatures and to convert the tars into fuel gases (i.e., CHx). The use of Fe-based catalysts for application has been reported before, however, there are still unsolved questions related to its stability and interaction with some species of gasification gases. Therefore, we evaluated carbon-supported Fe for the decomposition of tar using simulated gasification gases, and toluene, naphthalene, and benzene as models for tar. The effects of temperature (565 < T < 665 °C) and co-feeding CO on the catalytic activity and stability were inspected at laboratory and bench scales. The activity of catalysts for decomposing tars was in the following order: benzene > toluene e > naphthalene. Moreover, there was evidence validating a reversible elemental step toluene⇔benzene over the Fe surface. The characterization of the spent catalysts evidenced the oxidation of the active phase and the carbon deposition on the surface. The formation of FexOy caused a marked loss of activity. Conversely, the carbides were stable and still active for tar decomposition.

Numerical simulation of gasification of a shrinking char particle in supercritical water

The technology of supercritical water gasification provides a promising way for clean and efficient utilization of coal for hydrogen production. Char conversion is the rate-determining step of the gasification process, and the development of char particle size and shape directly affects the drag force, heat transfer and particle conversion characteristics in a supercritical water gasifier. Thus, a 2D transient CFD-based model was developed in this work to describe the conversion of a shrinking char particle in supercritical water, and the dynamic mesh method was used for particle surface tracking. 0.1 and 1 mm sized char particles were gasified at 873 to 1023 K, and the char conversion was obviously restrained by heat and mass transfer with the increase of particle size and temperature. The effect of convection was then studied with Reynolds number varying from 0 to 200. Convection effectively promoted the char conversion by enhancing the heat and mass transfer, and meanwhile, irregular development of particle shape was caused by the uneven temperature and supercritical water distribution on the particle surface. Owing to the special high concentration of supercritical water which ensured relative uniform distribution of supercritical water all the time, the irregular shape development was not obvious even at high Reynolds number. Moreover, the wake vortex formed at high Reynolds number promoted the fluid mixing, and an inflection point with the minimum carbon consumption rate appeared on the downstream side.

Simulation of steam gasification of halophyte biomass for syngas production using Aspen Plus®

Simulation of steam gasification of halophyte biomass for syngas production using Aspen Plus®