Search

Injection of gas–liquid sprays into gas–solid fluidized beds finds application in many industries. Effective mixing and distribution of liquid feed and solid bed material is paramount to ensure an efficient and profitable process. Despite its long-term use, the mechanism of liquid injection into gas–solid fluidized beds continues to raise questions and is only partially understood. This paper provides a thorough and up-to-date review of experimental and numerical investigations of gas–liquid sprays into gas–solid fluidized beds conducted over the past decades. Based on the surveyed literature, a phenomenological description of the prevalent mechanisms of gas–liquid injection under different operating conditions is presented. This review identifies suitable computational fluid dynamic models for simulating the mechanisms involved in gas–liquid–solid interactions along with recommendations for future numerical and experimental work.

The Selective Non-Catalytic Reduction process was investigated through experiments and modelling in a bench scale cyclone reactor. Outlet and internal profiles of NO and NH3 concentrations were measured at varying operating conditions. Cyclone inlet temperatures between 866 and 1023 °C were used, while the inlet NO concentration was kept at ~500 ppm. Gaseous ammonia was injected in the cyclone inlet, with nitrogen carrier gas. 60-69% NO reduction was achieved at inlet temperatures of 975-982 °C, and stoichiometric ratio NH3/NO β ≈ 1.6, with no ammonia slip. The main reaction zone was the inlet and upper cyclone chamber. The experiments was modelled using simple and detailed kinetics combined with simple reactor models and a compartment model suggested in this work. The qualitative trends of NO reduction and ammonia slip were predicted by the models. However, the ammonia slip was significantly over-predicted in most cases. The outlet concentrations were insensitive to choice of reactor model, while sensitive to temperature and kinetics. The compartment model quantitatively reproduced the cyclones NO concentration profiles, through its simplified representation of the cyclone flow and temperature gradients, while the NH3 profiles were only qualitatively predicted. The choice of bypass fractions showed a large influence on the ammonia profiles.

The Dense Discrete Phase Model coupled with an agglomeration model is developed and validated for the simulation of industrial cyclones with high solid loads. The performance of the model is influenced by sub-models, model parameters, and numerical parameters. To optimize the performance of the present CFD model, an extensive sensitivity analysis was performed, varying one sub-model or parameter at a time, and systematically assessing the effect on the results through comparisons with measured pressure drop and separation efficiency of a highly loaded pilot-scale cyclone. The investigation shows that the turbulence model and particle-particle restitution coefficient have the strongest influence. This study concludes with the recommendation of a set of sub-models, model parameters, and numerical parameters providing the best prediction of the hydrodynamics of large-scale highly loaded cyclones. In addition, the impact of some operating conditions on the performance of a large-scale highly loaded cyclone were examined.

Cracking of sugars to glycolaldehyde and other value-added oxygenates has shown potential in lab-scale fluidized beds with high yield and selectivity towards glycolaldehyde. In this work, a homogeneous gas-phase kinetics model for sugar cracking available in literature is adopted and implemented into the Computational Particle Fluid Dynamics (CPFD) framework in order to simulate sugar cracking in a pilot-scale circulating fluidized bed riser operated at conditions relevant for continuous production of glycolaldehyde in the industry. An Eulerian-Lagrangian approach is applied to model the three-phase flow where liquid feed droplets are injected into the hot gas-solid fluidized bed. A modified gas-to-liquid ratio dependent Rosin-Rammler droplet size distribution is proposed to accurately represent the gas-liquid jet in the simulation. Simulated temperature and pressure distributions are in good agreement with measured ones. Prediction of the yield of glycolaldehyde at 60.9 wt.%-C and other oxygenates using the the CPFD model corresponds closely to the results obtained from the same kinetic model implemented in an isothermal plug flow reactor model. This suggests that the CFB riser behaves essentially like a plug flow reactor, as hydrodynamic and thermal deviations from plug flow conditions do not have a considerable effect on the predicted yields. Comparing the model predictions to the measured yield of glycolaldehyde, a 50% overprediction is observed, suggesting that the hydrodynamic and cracking kinetics submodels need to be more closely coupled to more accurately predict the product yields, by means of e.g. heterogeneous cracking reactions.

Particulate matter (PM) generated by residential wood combustion is a major environmental concern in Europe. This study focuses on the influence of potassium chloride (KCl) on fine particle emissions from a modern wood stove. Wood logs with and without KCl impregnation were subjected to batch combustion and emission measurements. A bi-modal particle number-size distribution characterized by a nucleation mode and an accumulation mode was identified for all types of wood fuel. However, in the presence of KCl, a lower number emission of ultrafine particles and a higher number emission of larger particles (size ∼200–500 nm) were observed. In addition, the emission factor of condensed organic compounds (COC) increased with increasing KCl content, from 0.16 g/kg dry wood for normal wood (NW) to 0.48 g/kg dry wood for wood impregnated with the 2 mol/L KCl solution (HKW), most likely due to the facilitated heterogeneous condensation of semi-volatile hydrocarbons on pre-existing ash particles. In addition, the emission factor of soot particles also increased slightly when the KCl content was high, from 1.47 g/kg dry wood for NW to 2.23 g/kg dry wood for HKW.

Purpose: To study the effect of timing of estrogen application on adipose tissue revascularization and immune regulation in rats given autologous fat transplantation.Methods: Ninety (90) healthy rats were selected for use in this study. The rats were randomly divided into a study group (n = 45) and control group (n = 45). After ovariectomy, the study group was given estrogen replacement therapy before autologous fat transplantation, while the control group was given estrogen replacement therapy after autologous fat transplantation. The rats were observed for 6 weeks after transplantation. Micro-vessel density, wet weight of transplanted fat, VEGF expression level, levels of M1 and M2 in macrophages, and macrophage infiltration rate were determined 40 days postautologous fat transplantation.Results: Forty days after autologous fat transplantation, microvessel density, wet weight of transplanted fat, expression level of VEGF and levels of M1 and M2 in macrophages were significantly higher in study group rats than in controls (p < 0.05). There was 80 % macrophage infiltration in the study group rats, while the corresponding control value (61 %) was significantly lower (p < 0.05).Conclusion: Estrogen treatment before autologous fat transplantation in rats is helpful for the revascularization of adipose tissue, enhances vascular regeneration, promotes the survival of adipose tissue after transplantation, and activates immune cells. It also promotes the production of immune factors, and improves immunoregulation in adipose tissue. Thus, this therapeutic strategy may be useful in clinical practice, but further clinical trials are required.

This study uses the Eulerian-Lagrangian multiphase particle-in-cell (MP-PIC) approach, adopted in the computational particle fluid dynamics (CPFD) code, Barracuda VR®, to simulate a cold-flow dual-circulating fluidized bed. The hydrodynamics is simulated using a novel segregated approach, in which the experimental solids circulation rate is specified as an input parameter. CPFD predictions of pressures and particle concentration distributions are compared with experimental results for varying bed material circulation rate of 76–153 kg/m2s and superficial gas velocity in the reactor riser from 3.3 m/s to 6.4 m/s. Overall trends in these quantities are well captured by the model. Detailed sensitivity studies of the reactor riser are carried out using a riser-only approach with a fixed bed mass inventory. Apart from the drag model selection, the pressure constant Ps and the exponent β of the MP-PIC particle stress model are found to have the greatest influence on the fluidization behavior and on the predicted solids flux.

The effect of gasification reactions on biomass char conversion under pulverized fuel combustion conditions was studied by single particle experiments and modelling. Experiments of pine and beech wood char conversion were carried out in a single particle combustor under conditions of 1473-1723 K, 0.0-10.5% O2, and 25-42% H2O. A comprehensive progressive char conversion model, including heterogeneous reactions (char oxidation and char gasification with CO2 and H2O), homogeneous reactions (CO oxidation, water-gas shift reaction, and H2 oxidation) in the particle boundary layer, particle shrinkage, and external and internal heat and mass transfer, was developed. The modelling results are in good agreement with both experimental char conversion time and particle size evolution in the presence of oxygen, while larger deviations are found for the gasification experiments. The modelling results show that the char oxidation is limited by mass transfer, while the char gasification is controlled by both mass transfer and gasification kinetics at the investigated conditions. A sensitivity analysis shows that the CO oxidation in the boundary layer and the gasification kinetics influence significantly the char conversion time, while the water-gas shift reaction and H2 oxidation have only a small effect. Analysis of the sensitive parameters on the char conversion process under a typical pulverized biomass combustion condition (4% O2, 13% CO2, 13% H2O), shows that the char gasification reactions contribute significantly to char conversion, especially for millimeter-sized biomass char particles at high temperatures.

An isothermal model is commonly used in computational fluid dynamics (CFD) modeling of biomass devolatilization in fluidized beds. However, the particle internal heat transfer, which is neglected by the isothermal model, influences significantly the devolatilization process for large biomass particles. To consider the effect of internal heat transfer, a heat-transfer-corrected isothermal model is introduced by comparing the differences between an isothermal model and a nonisothermal model. Two correction coefficients for external heat transfer, HT, and reaction rate, HR,i, were defined to correct the conventional isothermal model. The predictions of the heat-transfer-corrected isothermal model and the nonisothermal model were in good agreement with the experimental data for both thermally thick (Biot number, Bi ≥ 1.0) and thermally thin (Bi < 1.0) biomass particles, while the conventional isothermal model gave reasonable results only for thermally thin biomass particles. The heat-transfer-corrected isothermal model was further implemented in a CFD model to simulate biomass devolatilization in a batch bubbling fluidized bed. Compared to the conventional isothermal model, the heat-transfer-corrected isothermal model had similar computational efficiency, but it predicted a lower heating rate and a lower devolatilization rate, which were in good agreement with the observations from single-particle modeling.

The development and performance in practice of a commercial automatically controlled wood stove is described. The digital control system controls the three combustion air inlets individually, based on the combustion phase, measured flue gas temperature, measured O2 outlet concentration and desired room temperature. The control system ensured a well-controlled combustion cycle with respect to temperature and oxygen concentration, yielding improved thermal efficiency and minimized carbon monoxide emissions. A minimum in CO emissions was identified for the oxygen operation range 10–13% O2. The improved performance has been verified by field tests in 5 private homes, demonstrating more stable and optimal O2 concentrations and temperatures compared to manual operation. This resulted in significant lower CO concentrations (up to 27%) alongside higher thermal efficiency (up to 20%) when comparing manually and automatically controlled wood stoves. This new technology has a great potential for improving the stove efficiency/biomass utilisation and reducing the emissions of pollutants at low altitude close to private homes.

This study uses the Eulerian-Lagrangian multiphase particle-in-cell (MP-PIC) approach, adopted in the computational particle fluid dynamics (CPFD) code, Barracuda Virtual Reactor®, to simulate the injection of a gas–liquid spray into a gas–solid fluidized bed. The model accounts for evaporation of volatile liquid in the form of individually moving droplets and thin films distributed on the surface of the solid bed particles. Comparison with previously reported temperature measurements for varying spray nozzle gas-to-liquid ratios suggests that the model is capable of predicting the overall features of the gas temperature distributions within the injection region at injection velocities of less than 50 m/s. Locally observed discrepancies between experimental and simulated temperature profiles are likely related to the presence of wet particle agglomerates in the spray region, as suggested by a developed energy dissipation model that, combined with the MP-PIC model, predicts the location and extent of agglomeration in the fluidized bed.

A hybrid multiphase model (Dense Discrete Phase Model, DDPM) coupled with an agglomeration model and a sub-grid drag model was developed for simulation of industrial-scale cyclones with high solid loading. The model is validated by experimental results of pressure drop and separation efficiency from a pilot-scale cyclone with a diameter of 1.6 m. Key trends such as improvement in separation efficiency and reduction in pressure drop of cyclone due to an increase in particle load are well captured by the model. It is concluded that including the agglomeration model is crucial in particular in cases involving very fine particles (d

A hybrid multiphase model (Dense Discrete Phase Model, DDPM) coupled with a k-ω sst turbulence model, which includes gas-solid heat exchange was developed for the simulation of industrial-scale cyclone preheaters operating under high solid loadings. The model results are validated by experimental measurements from an industrial cyclone preheater with a diameter of 1.6 m, with respect to the pressure drop, gas and particle exit temperature, local gas velocity profiles, measured using the LDA, and gas temperature profiles, measured using thermocouple and FTIR. Reasonable agreement between the data from experiments and simulations was obtained. In addition, the major trends, such as changes in the pressure drop, overall heat transfer rate, and flow pattern, caused by the changes in the operating parameters can be captured accurately by the model.

The mixing and segregation behaviour of binary solid mixtures has been extensively studied through various experiments, while accurate CFD simulations are difficult to achieve due to process complexity and a lack of reliable constitutive relations. In this study, CFD simulations of a dense fluidized bed with glass and polystyrene particles were performed in order to identify a universal set of simulation parameters and models for simulating binary mixtures with different mixed and segregation behaviour. Through a comparison to experimental data, it was found that the EMMS drag model coupled with the Ma‐Ahmadi solid pressure and radial distribution models predicted more a reasonable axial distribution of solid phases than the Syamlal O´Brien drag model coupled with the Lun et al. solid pressure and radial distribution models. The increase in the solid‐solid drag further improved the simulation results.

The preparation of furans from catalytic conversion of corn stover is investigated in H2O–THF (tetrahydrofuran) co-solvent system, and the effects of Bronsted acids (H2SO4, HCl, HNO3) combined with alkali metal cations (Li+, Na+, K+) are studied systematically. It is found that the effect of individual acid in promoting the summary yield of 5-hydroxymethylfurfural (HMF) and furfural (FF) can be ordered as Cl− > SO42− > NO3−. When combined with a salt, the anion effect can be ranked in SO42− > Cl− > NO3−, both for the HMF yield and the summary yield of furans. Based on the best anion of SO42−, the impacts of the combined cations can be finely ranked as Na+ > K+ > Li+. For the system with Cl−, it ranks in K+ > Li+ > Na+ for the HMF yield or the summary yield of furans. The performance of NO3− is so poor that no liquid product can be detected when any alkali metal cations is combined with HNO3. The performance of H2SO4/Na2SO4 is the best among 9 tested combined catalysts, and the yield of HMF and FF from corn stover conversion under optimized conditions are 76% and 81% respectively.

Char and soot characterizationwas performed on samples obtainedfrom pilot-scale entrained flow gasification of coal bio-oil slurry(CBS) and coal/water slurry (CWS) at different operating conditions.The compositions and gasification reactivity of char and soot havebeen investigated to reveal the difference of CBS and CWS slurries.The results show that both char and soot obtained from CBS gasificationcontain alkali and alkaline earth metals which come from the bio-oil.These CBS char and soot alkali-containing samples exhibit higher gasificationreactivity than those from CWS gasification. For CBS gasification,soot has higher gasification reactivity compared with char. The gasificationreactivity may be caused by the catalytic effect of KCl and K2SO4 existing in char and soot. The reactivity ofchar and soot is also influenced by the gasification conditions (suchas H2O/C ratio), and high CO2 gasification reactivityis observed for chars exposed to high H2O/C ratios in theentrained flow reactor.

The disposal and utilization of antibiotic mycelial dreg (AMD), which has been identified as a hazardous waste in China, are a serious concern because of the residual antibiotic and huge annual output. Pyrolysis is a promising technology to treat AMD. However, the pyrolysis of AMD is not studied in an adequate degree, particularly no attention has been paid to the release and distribution of the phosphorus in AMD during pyrolysis. Therefore, the present work studied the pyrolysis of AMD more comprehensively. The influence of pyrolysis temperature on product yields and characteristics, together with the release and distribution of nitrogen and phosphorus, and the antibiotic residue in products, were investigated. The results suggested that residual antibiotic was eliminated after pyrolysis. Nitrogen was mainly contained in the biochar and liquid products, while phosphorus was mainly retained in the biochar. Liquid products were characterized by abundant oxygen and nitrogen-containing compounds, while biochar was featured of both abundant nitrogen and inorganic phosphate groups. Pyrolysis temperature showed a significant effect on product yields and characteristics, and a low pyrolysis temperature is recommended considering the recycling of nitrogen and phosphorus. The disposal of AMD through pyrolysis conforms to the principles of AMD disposal.

Agglomeration is one of the main challenges for combustion and gasification of biomass in fluidized beds. Bed agglomeration is related to K species present in biomass. Understanding the role of different types of K species on formation of agglomerates at different conditions can reveal the mechanisms of biomass ash induced agglomeration. Extensive experiments are conducted in a laboratory scale fluidized bed reactor, using mixtures of quartz sand and K species, including KCl, K2SO4 and K2CO3, to study the agglomeration mechanisms. The effects of gas composition, including air, H2– and H2O– containing gas are investigated. The morphology and elemental analyses of the agglomerate samples are examined by SEM/EDS analysis. Thermodynamic equilibrium calculations are performed for verifying the proposed mechanisms. The results show that the role of various forms of potassium salts on agglomeration in fluidized beds is different. Gas composition also has strong impact on the agglomeration tendency. In the air and H2-containing gas, defluidization of KCl in a sand bed is caused by the melt of KCl. However, KCl reacts with SiO2 to form K-silicates in the H2O-containing gas, which results in a lower defluidization temperature. No defluidization is observed for K2SO4 in the presence of oxygen or water. However, K2SO4 decomposes and reacts with SiO2 to form K-silicates, causing defluidization at 850 °C in the H2-containing gas. In the air, H2– or H2O-containing gas, K2CO3 would react with SiO2 to form potassium silicates and KOH may be additionally formed in the H2– and H2O-containing gas. The possible mechanisms of agglomeration of various potassium salts at different conditions are discussed.

In this study, the flow characteristics of Geldart A particles in a bubbling fluidized bed with and without perforated plates were simulated by the multiphase particle-in-cell (MP-PIC)-based Eulerian–Lagrangian method. A modified structure-based drag model was developed based on our previous work. Other drag models including the Parker and Wen–Yu–Ergun drag models were also employed to investigate the effects of drag models on the simulation results. Although the modified structure-based drag model better predicts the gas–solid flow dynamics of a baffle-free bubbling fluidized bed in comparison with the experimental data, none of these drag models predict the gas–solid flow in a baffled bubbling fluidized bed sufficiently well because of the treatment of baffles in the Barracuda software. To improve the simulation accuracy, future versions of Barracuda should address the challenges of incorporating the bed height and the baffles.

Agglomeration is one of the operational problems in fluidized bed combustion of biomass, which is caused by interaction between bed materials (e.g. silica sand) and the biomass ash with a high content of potassium species. However, the contribution of different potassium species to agglomeration is not fully understood yet. In the present work, the reaction between K2CO3 and silica sand has been studied extensively by thermogravimetric analysis. The reacted samples were analyzed by SEM-EDX to reveal the reaction mechanism. The results indicated that the reaction occurs in a solid-solid phase already at temperatures around 700°C. The reaction rate increases with increasing temperature, but decreases with an increase of CO2 partial pressure. Using smaller particle size and well mixed solid reactants results in an increased reaction rate. It is observed that the reaction initiates in the contact area between K2CO3 and silica sand, forming a thin product layer. The layer acted as a reactive media further reacting with K2CO3 and silica sand. The results provide a basis for understanding of potassium induced agglomeration process in fluidized bed biomass combustion.

Four iron ores including limonite, siderite, hematite and magnetite are examined for their catalytic effects on coal pyrolytic products. Experiments were conducted at a pyrolyzer combined with gas chromatography/mass spectrometry (Py-GC/MS). The results show that limonite has the highest catalytic activity for light aromatic formation as a result of the conversion of aliphatic hydrocarbons and oxygenates. The total peak area of light aromatics such as benzene, toluene, ethylbenzene, xylene, and naphthalene (BTEXN) has increased by 52% after the catalysis of limonite. The good performance of limonite can be attributed to its large surface area. Multi-cycle tests were conducted over limonite to get the knowledge of its stability. The effect of valence state of iron is discussed by making comparison of the performances between the limonite and the reduced limonite. It is found that the reduced limonite has a more reactive catalytic activity for light aromatics production. Coal effect is also studied.

The influence of potassium chloride (KCl) and potassium hydroxide (KOH) on the formation of benzene and soot in fuel-rich oxidation of methane was investigated experimentally using a flow reactor at atmospheric pressure and temperatures ranging from 1273 to 1673 K. The methane inlet concentration was kept constant at 2 vol.% (nitrogen balance), while the C/O ratio was 2 or 5. The potassium salt was fed into the main gas flow at a comparatively high concentration of around 1000 ppm. The onset of formation of acetylene and benzene was around 1373 K. The addition of both potassium salts was found to promote formation of acetylene and benzene at temperatures below 1523 K. This effect was most pronounced at a high C/O ratio of 5 and in the presence of KOH, but diminished at temperatures above 1523 K. A detailed chemical kinetic model was used to interpret the experimental results and was found to be able to partially reproduce the promoting effect of KOH. According to the model, the addition of KOH facilitates the buildup of OH radicals through the rate controlling reaction KOH + M ⇌ K + OH + M. The promotion of the radical pool favors the formation of active intermediates including methyl and vinyl radicals, both of which play an important role in the major benzene formation pathways under the conditions investigated. Particle analysis using SMPS showed a net increase in the volume concentration of soot and a shift of the particle size distribution towards larger diameters in the presence of KOH, but no quantitative difference was observed for the mass of carbonaceous materials collected on filters.

Gasification is a promising technology to dispose antibiotic mycelial dreg (AMD) which is a typical pharmaceutical hazardous bio-waste. However, the gasification of AMD is rarely studied. Since char gasification is the key step in the gasification process, the present work focused on the steam gasification of char. The influence of inorganic elements inside AMD char (mainly P, K and Ca) on the char gasification reactivity is investigated. Particularly, the effect of P on char gasification reactivity was deeply studied, and the co-effect of P, K and Ca on char gasification reactivity was firstly studied and explained. The obtained results suggested that P can deactivate the catalytic function of K and Ca on char gasification by forming K-phosphates and Ca-phosphates. The existence form of P can affect its inhibitory effect on K and Ca, and the pyrophosphate P had a stronger inhibiting effect than orthophosphate P. The deactivation of P on K is related to the ratio of K to P, and the bigger the ratio of K to P the less the deactivation of P on K. The existence of Ca can effectively eliminate the deactivation of P on K by reacting with P to form more stable Ca3(PO4)2.

This work investigates the interactions in NOX chemistry during biomass co-combustion in a continuous lab-scale bubbling fluidized bed reactor. Co-combustion experiments were performed at air staged and unstaged conditions, and the gas composition in the flue gas and within the reactor was measured. The used biomass fuels were straw, sunflower husk, sewage sludge, and sunflower seed. Based on the NO concentration in the flue gas, straw-sunflower husk and straw-sunflower seed co-combustion were additive, while co-combustion of straw and sewage sludge revealed a synergy effect. The main cause was the presence of sewage sludge ash, which could catalyse the formation of NO from NH3 and HNCO, and possibly HCN. The catalytic effect of the ash increased with lower ash preparation temperature and better mixing of the ash with straw. During straw-sewage sludge co-combustion, the NH3 initially released from sewage sludge favoured the reduction of NO, while at later stages, when a significant amount of ash accumulated in the bed, the catalytic oxidation of NH3 to NO was dominant. Compared to air unstaged conditions, the NO emission was reduced and the impact of ash on the nitrogen chemistry was less pronounced at air staged conditions.

Conversion of furfural to 2-methylfuran over Cu/Al 2 O 3 , Ni/Al 2 O 3 and Ni-Cu/Al 2 O 3 catalysts were investigated with formic acid as a hydrogen donor. Ni/Al 2 O 3 showed a high catalytic activity but a moderate selectivity to 2-methylfuran. Contrarily, Cu/Al 2 O 3 showed a low catalytic activity but a high selectivity for carbonyl reduction. Over the bimetallic catalysts Ni-10%Cu/Al 2 O 3 , by increasing Ni content, more furfural was converted with the reduction of carbonyl primarily. The effect of reaction solvent and the fraction of formic acid were also studied. The result showed that isopropanol solvent could contribute to the formation of furfuryl alcohol with 96% selectivity through the transfer hydrogenation process. Formic acid could decompose to H 2 and CO 2 , remarkably promoting the hydrogenolysis of furfuryl alcohol to 2-methylfuran. Finally, 100% conversion and 92 mol% yield of 2-methylfuran could be obtained over 10%Ni-10%Cu/Al 2 O 3 . It was attributed to the synergic effect of Ni-Cu metals, with increased affinity for carbonyl reduction.

Phenolic-oil can be upgraded by etherification with methanol to decrease the polarity and acidity of the product oil. However, alkoxy phenols have an inhibiting effect to the etherification of alkyl phenols in the phenolic mixture. So, it is very important to produce alkyl phenols with high selectivity and extremely low content of alkoxy phenols, through a catalytic pyrolytic process. Herein, the effects of HZSM-5, NaY, and KH 2 PO 4 /AA (KH 2 PO 4 loaded on activated Al 2 O 3 ) on the pyrolysis of corn straw fermentation residue are investigated, for producing alkyl phenols high efficiently. KH 2 PO 4 /AA is found to be the best catalyst in promoting the formation of alkyl phenols and in inhibiting alkoxy phenols. Under the catalysis of KH 2 PO 4 /AA, the tar yield increases with rising temperature, and reaches to the maximum tar yield of 13.7% at 500 °C, and then declines with further increasing temperature. The tar obtained under optimized reaction conditions, nearly consists of 50% of alkyl phenols and over 23% of aliphatic hydrocarbons with zero content of alkoxy phenols. K 3 Al 2 (PO 4 ) 3 is generated from the solid phase reaction between KH 2 PO 4 and Al 2 O 3 , through which alkoxy phenols can be high selectively adsorbed and activated, and thus leads to the formation of alkyl phenols.

In-situ hydrodeoxygenation of phenol with aqueous hydrogen donor over supported Ni catalyst was investigated. The supported Ni catalysts exerted very poor performance, if formic acid was used as the hydrogen donor. Catalyst modification by loading K, Na, Mg or La salt could not make the catalyst performance improved. If gaseous hydrogen was used as the hydrogen source the activity of Ni/Al2O3 was pretty high. CO2 was found poisonous to the catalysis, due to the competitive adoption of phenol with CO2. If formic acid was replaced by methanol, the catalyst performance improved remarkably, with major products of cyclohexanone and cyclohexanol. The better effect of methanol enlightened the application of the supported Ni catalyst in in-situ hydrodeoxygenation of phenol.

In situ hydrodeoxygenation of phenol with liquid hydrogen donor over three supported Pd, Pt, and Ru catalysts was investigated. The method of incipient wetness impregnation was used to load the three noble metals on the support of MCM-41, which is a cylindrical mesoporous material with a hierarchical structure. The in situ hydrodeoxygenation of phenol was conducted at 280 degrees C, under pressures from saturated vapor of solvent and compressed initial N-2 with gas products. Among the three catalysts, Ru/MCM-41 was found to be the best one, with highest phenol conversion of 73.9% and deoxygenation degree of 72.2%. The performance of Ru/MCM-41 increased with increasing theoretical loading amount of Ru and with reduction temperature. However, when the reduction temperature reached to 500 degrees C, or the Ru theoretical loading amount increased to 15 wt%, the activity of Ru/MCM-41 decreased reversely. Through the characterizations by small-angle XRD, wide-angle XRD, H-2-TPR, and SEM analysis, the reason for the deteriorated performance of Ru/MCM-41 under high reduction temperature or high Ru loading amount was deduced as the collapse of MCM-41 structure and severe overlaps of Ru atoms. Hydrogen donors were also tested, and formic acid was found in best performance owing to its fast decomposition rate and high productivity of hydrogen. Though an increased feed ratio of formic acid to phenol could improve the hydrodeoxygenation potential of phenol, much simultaneously generated CO. from decomposition of formic acid might occupy active sites of the catalyst and led to a decreased growth rate of phenol conversion. (C) 2017 Elsevier B.V. All rights reserved.

The aim of this study is to explore the inconsistencies between right liver volume as measured by imaging and the actual anatomical appearance of the right lobe. Five healthy donated livers were studied. The liver slices were obtained with hepatic segments multicolor-infused through the portal vein. In the slices, the lobes were divided by two methods: radiological landmarks and real anatomical boundaries. The areas of the right anterior lobe (RAL) and right posterior lobe (RPL) on each slice were measured using Photoshop CS5 and AutoCAD, and the volumes of the two lobes were calculated. There was no statistically significant difference between the volumes of the RAL or RPL as measured by the radiological landmarks (RL) and anatomical boundaries (AB) methods. However, the curves of the square error value of the RAL and RPL measured using CT showed that the three lowest points were at the cranial, intermediate, and caudal levels. The U- or V-shaped curves of the square error rate of the RAL and RPL revealed that the lowest value is at the intermediate level and the highest at the cranial and caudal levels. On CT images, less accurate landmarks were used to divide the RAL and RPL at the cranial and caudal layers. The measured volumes of hepatic segments VIII and VI would be less than their true values, and the measured volumes of hepatic segments VII and V would be greater than their true values, according to radiological landmarks. Clin. Anat., 2017. © 2017 Wiley Periodicals, Inc.

The mineral carbonation of phosphogypsum offers many advantages in sequestering CO2, solving the pollution problem of phosphogypsum stacking, and manufacturing high value-added chemical products with low energy consumption and cost. Using the Aspen Plus process simulation software, this work simulates a novel process for the mineral carbonation of phosphogypsum with ammonia under increased CO2 pressure. This process is divided into five sections, namely, pre-carbonation, enhanced carbonation, flash separation, gas phase absorption, and (NH4)2SO4 fertilizer production. With its large-scale application, this new process allows the sensitivity analysis of many operation conditions, identifies the optimal conditions for reducing the ammonia and energy consumption of (NH4)2SO4 fertilizer production, and achieves a high carbonation conversion with a fast reaction rate. The optimal conditions (6 bar enhanced carbonation pressure, 1 bar flash pressure, 38 °C ammonia absorption solution temperature, 1.05 ammonia excess ratio, 1.024 CO2 excess ratio, and 0.94 mass ratio of water to gypsum) yield the highest carbonation conversion, ammonia utilization ratio, and enhanced carbonation temperature of 99.9%, 95.2%, and 138.5 °C, respectively, all of which can help achieve a fast carbonation reaction rate.

A three-dimensional CFD model was developed to simulate the hydrodynamics in a pilot-scale dual fluidized bed system for biomass gasification. The system includes a fast fluidized bed (FFB) for char combustion, a cyclone separator, two loop-seals, and a bubbling fluidized bed (BFB) for biomass gasification. A comparison of a hybrid EMMS drag model (i.e. the EMMS/matrix drag model for FFB, and the EMMS/bubbling drag model for BFB) proposed in this paper and the Gidaspow drag model was carried out at air and steam gasification conditions. The solid circulation rate, solid inventory distribution, and the pressure distribution predicted by the hybrid EMMS drag model were in better agreement with experimental data. The effect of solid inventory on hydrodynamics was evaluated by using the hybrid EMMS drag model. The results indicate that the solid circulation rate and its fluctuation increased with increasing solid inventory. In the simulated system, the operating stability was reduced when the solid inventory was increased to 200 kg due to “choking” phenomenon.

A key component in the atmospheric leaching of metal sulfides is the oxidation of sulfide to either elemental sulfur or hexavalent sulfur. The final oxidation state of sulfur significantly influences the economic viability of a leaching process because of its effects on oxygen consumption, acid generation, and surface passivation. Thus, in the process of developing new leaching technologies, it is important to both characterize and quantify the sulfur oxidation products. In this work, a new method based on Simultaneous Thermal Analysis (STA) is established for the quantification and thermal characterization of elemental sulfur in chalcopyrite leach residues. The STA method refers to the simultaneous application of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The DSC measurements yield information on phase transformation, which can be used to identify the sulfur allotropes. The linear relationship between the melting enthalpy of β‑sulfur determined by DSC and the sulfur content determined by TGA is expediently used to quantify the unknown sulfur content in leach residues.

Fluidized beds (FB) are widely applied to gasification of biomass due to its advantages of high fuel flexibility and conversion. However, bed agglomeration induced by the high content of alkali compounds can have strong impact on the operation of a FB gasifier and may lead to defluidization and unscheduled plant shutdown in severe cases. Agglomeration at high temperature, such as combustion and gasification, is mainly attributed to the presence of molten phase, i.e. the low melting point alkali containing compounds originated from biomass. During gasification, the alkali species in biomass can be transformed into gaseous phase, such as KCl and KOH vapor, and condensed phase, such as K2SO4 aerosols and K-silicates particles, depending on the local conditions. The interactions of the alkali species with bed materials (mainly SiO2) may result in the formation of molten phase, causing agglomeration. However, the agglomeration tendencies and mechanisms during biomass gasification with different gasification agents are still not fully understood.In this work, the agglomeration behaviors of different types of biomass during gasification are studied in a lab-scale fluidized bed reactor. The impact of the composition of biomass, e.g. types of biomass, and the operational conditions, such as temperature and gasification agents (steam and CO2), are studied. The different agglomeration mechanisms are revealed based on SEM-EDX analyses of the agglomerate samples and chemical equilibrium calculations.

The formation of nitrogen oxides (NO and N2O) during raw and demineralized biomass char combustion and the reduction of NO over biomass char were investigated. The biomass fuels were pine wood, straw, waste wood, bran, dried distillers grains with solubles (DDGS), and sunflower seed. Fixed-bed combustion experiments were performed at 800 °C in 10 vol % O2, while NO reduction experiments were conducted at temperatures from 800 to 900 °C and NO inlet concentrations from 400 to 1500 ppmv. The chars were characterized by means of inductively coupled plasma emission spectroscopy, Brunauer–Emmett–Teller, scanning electron microscopy and energy-dispersive X-ray, and X-ray photoelectron spectroscopy. The conversion of char-N to NO decreased with an increase in the initial char-N content, partly explained by the increased inherent conversion of char-N to N2O. The reduction of NO over char exhibited no correlation to the surface functionalities and content of nitrogen and oxygen at the investigated conditions. The NO reduction reactivity was strongly dominated by the content and association of ash-forming elements in the chars. The NO reduction reactivity of pine wood, waste wood, and straw chars correlated reasonably well with the (K + Ca)/C molar ratio, while the chars with a high phosphorous content, i.e., bran, DDGS, and sunflower seed chars, differed by showing a significantly lower reactivity. The inhibition effect of phosphorous on NO reduction reactivity was likely caused by the formation of less catalytically active potassium species (such as KPO3) in biomass char.

The combustion characteristics of Huadian oil shale and its semicoke are comparatively studied using a thermobalance (TB) and a drop-tube furnace (DTF). It is found that the ignition mechanism of oil shale and semicoke is hetero-homogeneous and heterogeneous, respectively. Drop-tube furnace experiments with both oil shale and semicoke show that the carbon (C) conversion proceeds almost simultaneously with the particle burnout, while the hydrogen (H) conversion is faster and that of nitrogen (N) and sulphur (S) slower than the particle burnout. The kinetic behavior of semicoke combustion is analyzed by drop-tube furnace experiments based on the first-order reaction model, and the kinetic model with known pre-exponential factor Aa 26.3 g.cm-2 S-1.atm-1 and apparent active energy E-a (65.8 kJ/mol) is obtained.

Catalytic etherification of phenolic oil with methanol was investigated to decrease the polarity and acidity of the product oil. The catalyst KH2PO4/activated alumina (AA) provided the best performance due to its excellent dehydration and anti-coking property. When catalyzed by KH2PO4-AA, the content of aryl ethers increased with rising temperature during the early stage but decreased at 500 degrees C. Alkoxy phenols had an inhibiting effect on etherification of alkyl phenols due to adsorption competition. Aryl ethers were mostly generated from alkyl phenols, while alkoxy phenols also contributed by simultaneous conversion to dialkoxybenzenes and diphenols, with a higher selectivity to diphenols. This explained the reduced alkoxy phenols and more generated alkyl phenols and aryl ethers at 350 degrees C.

Coal/bio-oil slurry (CBS) is a new partial green fuel for bio-oil utilization. CBS reacts with gasification agents at high temperatures and converts into hydrogen and carbon monoxide. This paper provides a feasibility study for the gasification of CBS in an atmospheric entrained flow reactor for syngas production. Experiments have shown that CBS can be successfully processed and gasified in the entrained flow reactor to produce syngas with almost no tar content and low residual carbon formation. High reactor temperature and steam/carbon ratio is favourable for H 2 production. At 1400 °C with steam/carbon ratio of 5, the syngas components are similar with that in equilibrium. A synergistic effect exists between coal and bio-oil in coal/bio-oil slurry gasification which might be caused by the catalysis effect of alkali metals and alkaline earth metals in bio-oil.

Low-grade natural iron ore, limonite, is proposed as an inexpensive catalyst to increase the light liquid production from coal pyrolysis. Experiments were conducted at a pyrolyzer combined with gas chromatography/mass spectrometry (Py–GC/MS). It is found that limonite favors the formation of light aromatic hydrocarbons, while the aliphatics and oxygenated compounds in tar are significantly reduced. Tests with model compounds (C19 alkane and o-cresol) indicate that the increased light aromatics could result from the conversions of either oxygenated compounds or aliphatics promoted by limonite. Gaseous products are determined with online gas chromatography (GC). A strong correlation between COx and light aromatics is revealed in the catalytic pyrolysis process, indicating that COx could be seen as an index of light aromatic formation. There is a maximum value for the yield of liquids when the temperature is increased, which is quite different from the tests without limonite. It is postulated that pyrolytic ...

The ash fusion characteristics are important parameters for thermochemical utilization of biomass. In this research, a method for measuring the fusion characteristics of biomass ash by Thermo-mechanical Analyzer, TMA, is described. The typical TMA shrinking ratio curve can be divided into two stages, which are closely related to ash melting behaviors. Several characteristics temperatures based on the TMA curves are used to assess the ash fusion characteristics. A new characteristics temperature, Tm, is proposed to represent the severe melting temperature of biomass ash. The fusion characteristics of six types of biomass ash have been measured by TMA. Compared with standard ash fusibility temperatures (AFT) test, TMA is more suitable for measuring the fusion characteristics of biomass ash. The glassy molten areas of the ash samples are sticky and mainly consist of K-Ca-silicates.

A major concern in thermal conversion of biomass encountered in fluidized beds is bed agglomeration, which may result in de-fluidization, leading to unscheduled downtime and additional costs. Biomass fuels, especially herbaceous plants, often contain significant amounts of silicon, potassium and calcium, which may form viscous melts that adhere on the surface of the colliding bed particles and bind them to form agglomerates. In this paper, studies were made to understand the behavior of inorganic elements (mainly K, Si and Ca) on agglomeration and de-fluidization of alkali rich bed-material samples under non-oxidizing conditions in a bench-scale fluidized bed reactor set up. The de-fluidization studies involved measurements with sand and pure potassium salts (KCl and K 2 CO 3 ) as well as with bed material samples obtained from a 6 MW Low Temperature Circulating Fluidized Bed (LTCFB) gasifier using straw as a fuel. It was seen that in sand + KCl agglomerates, the sand particles were bound by KCl melts. Only very limited chemical reaction was observed between KCl and the sand particles and no presence of silicate melts in the agglomerates. For sand + K 2 CO 3 mixtures and for LTCFB bed material samples, agglomeration could be attributed to viscous silicate melts formed from reaction of inorganic alkaline and alkali earth species with silica from the bed particles. A mathematical model that addresses the de-fluidization behavior of alkali-rich samples was developed based on the experiments performed in the bench-scale fluidized bed reactor as well as on results from literature. The model was then used to predict the de-fluidization behavior of alkali-rich bed material in a large-scale LTCFB gasifier.

Fluidized beds have been widely applied to gasification and combustion of biomass. During gasification, a high temperature is preferable to increase the carbon conversion and to reduce the undesirable tar. However, the high temperature may lead to a severe agglomeration problem in a fluidized bed. Understanding of the agglomeration in various atmospheres is crucial to optimize the design and operation conditions. This study focuses on the effects of gases on agglomeration tendency with different types of biomass, including corn straw, rice straw, and wheat straw. The biomass ash samples are mixed with quartz sand and fluidized by the gas mixtures of N2/CO2, N2/H2, and N2/steam or by air. At 550 °C, the bed temperature is increased at the rate of 3 °C/min until defluidization occurs. In this way, the defluidization temperature can be determined, which represents the agglomeration tendency. The agglomerates are analyzed by scanning electron microscopy–energy-dispersive X-ray spectrometry (SEM–EDS) for morph...

Bio-oil from pyrolysis of biomass is an important renewable source for liquid fuel and/or for chemicals. However, the application of bio-oil was severely restricted due to its high viscosity, acidity, and low heating value. Hence, it is necessary to upgrade the bio-oil for deoxygenation or for chemicals by catalytic reactions. In this paper, the catalytic behaviors of SAPO-34, ZSM-5, and Y zeolite on pyrolysis of cellulose were investigated via pyrolyzer combined with gas chromatography and mass spectrometer (Py-GC/MS) method in Py-mode. The results showed that ZSM-5 and Y zeolite could promote the conversions of oxygen-containing components to gases, water, aromatics, and phenols. Comparatively, more gas and water were generated under the catalysis of Y zeolite at lower temperatures, while at temperatures above 700°C, the effect of ZSM-5 became more distinct; aromatics were more generated under the catalysis of ZSM-5, while Y zeolite exerted a more distinct role in promoting the formation of phen...

Hydrodeoxygenation of phenol, as model compound of bio-oil, was investigated over Pd catalysts, using formic acid as a hydrogen donor. The order of activity for deoxygenation of phenol with Pd catalysts was found to be: Pd/SiO 2 > Pd/MCM-41 > Pd/CA > Pd/Al 2 O 3 > Pd/HY ≈ Pd/ZrO 2 ≈ Pd/CW > Pd/HSAPO-34 > Pd/HZSM-5. The good performance of Pd/SiO 2 is owing to its proper pore structure and large specific surface area. The high level of Bronsted acid sites in SiO 2 also favors the deoxygenation of phenol.

Dual fluidized bed (DFB) reactor is one of promising ways for biomass gasification. In this work, an integrated system is designed to produce multi products, i.e., liquid fuel and electricity using biomass as feedstock. The system consists of four main sections, i.e. Gasification, CO2 capture, F-T synthesis, Power Generation. HRSG unit is applied to recover the sensible heat and produce steam, and the heat and electricity demanded by this system are produced by itself. The simulation is conducted in Aspen Plus and the results are verified with the literature and industrial data. Carbon chain analysis, energy analysis and green degree method are applied to evaluate the mass conversion, energy utilization and environmental influence of the system, which presents a clear description of the whole system. Furthermore, CO conversion of DFB reactor has a significant influence on oil production. The results show that 39.7% (HHV) of biomass energy is stored in products, 24.0% (HHV) in liquid fuel and 15.7% (HHV) in electricity. The energy efficiency comparison between several integrated systems is also given.

The synthesis of anisole by vapor phase methylation of phenol with methanol over activated alumina (AA) supported catalysts was investigated in a fixed bed reactor. KH2PO4/AA gave the best performance among the eight tested catalysts. The catalyst was prepared by loading KH2PO4 on AA and then calcining at the optimized temperature of 700 °C for 8 h. In the vapor phase reaction, the level of anisole yield (LAY) has a maximum at 400–450 °C when the temperature varied from 300 to 500 °C, which decreased slightly with increasing WHSV and increased distinctly with increasing mole fraction of methanol. On comparing O-methylation and C-methylation of phenol, a low temperature, high WHSV (short residence time), and a low methanol concentration over the KH2PO4/AA catalyst with higher K contents were found to increase anisole selectivity by O-methylation of phenol. The reaction routes to the major products and the catalytic mechanism were suggested, and a ‘K-acid’ bifunctional process may be a critical factor to the formation of anisole.