Bed Height Research Articles

Pilot Study Examining Bed Angles and Heights During Ramped Position Intubation in the Emergency Department.

Ramped positioning during emergent endotracheal intubation has been associated with fewer peri-intubation complications, including a decrease in difficult intubations, esophageal intubations, pulmonary aspiration, and hypoxemia. However, the optimal bed angle and height for ramped position intubation have not been determined. Our objective was to examine the effect bed angle and height in the ramped position may have on laryngeal views during emergent intubation in the emergency department (ED). We performed a secondary analysis of prospectively collected quality improvement data on intubations from our ED. All adult medical intubations performed with ramped positioning in the ED over a 24-month study period (September 1, 2020, through August 30, 2022) were eligible. We compared laryngeal views using the percentage of glottic opening (POGO) score between ramp angles (≥30° and <30° from horizontal) and bed heights (relative to the intubator, including xiphoid or above, umbilicus or below, and between xiphoid and umbilicus). Of the 251 patients intubated during the study period, 201 were intubated in the supine position and 50 in the ramped position. Data forms were completed for 25 patients intubated using ramped position in the ED during the study period. The median ramp angle was 30° (interquartile range (IQR) 25, 40) with 16 (64%) subjects intubated at ≥30° and 9 (36%) subjects at <30°. The median POGO scores for bed angles ≥30° and <30° were 95% (IQR 79, 100) and 90% (IQR 75, 100), respectively. Bed heights varied, with four (16%) intubated at the xiphoid or above height, one (4%) at the umbilicus or below, and 20 (80%) between the xiphoid and umbilicus. The median POGO scores at each position were 95% (IQR 76, 100), 0% (IQR 0, 0), and 95% (IQR 79, 100), respectively. ED clinicians use a variety of bed angles and heights when intubating in the ramped position. More robust investigations are necessary to determine the optimal bed angle and height for ramped position intubation in the ED.

Full continuum approach for simulating plume-surface interaction in planetary landings

A high-fidelity computational framework for predicting the interaction of a rocket plume with a dust blanket in an almost vacuum ambient that represents the descent/ascend phase of planetary landing is developed. Compared to the existing continuum frameworks, the developed tool benefits from nonlinear-coupled constitutive relationships obtained using a method of moments approach to tackle the non-equilibrium effects in the rarefied condition. The two-phase flow is modeled in an Eulerian framework that allows for the simulation of a wider range of solid regimes compared to the Lagrangian counterpart. Simulations were conducted to analyze the cratering phenomena and regolith ejecta dynamics. Moreover, the vorticity growth rates were analyzed using a new vorticity transport equation (VTE) by including the bulk viscosity and multiphase terms to demonstrate the contribution of each term to the formation of counterintuitive festooned patterns on the surface owing to jet impingement. This analysis identified a new contributing mechanism responsible for the scour patterns. Although all the investigated terms in the VTE contribute to such patterns, the viscous term has more effect during the entire investigation period. Furthermore, studies on particulate loading, particle diameter, and bed height were conducted to highlight the role of these parameters on brownout phenomena and scour formation patterns. The simulation results depict that the generated vortex core beneath the nozzle is highly dependent on the diameter of the particles as well as the bed height: an increase in the height of the bed and particle diameter can lead to a more favorable brownout status.

Modeling and validation of coarse-grained computational fluid dynamics–discrete element method for dense gas–solid flow simulation in a bubbling fluidized bed

Computational fluid dynamics (CFD) combined with the discrete element method (DEM) are powerful tools for analyzing dense gas–solid flows. However, the computational cost of CFD–DEM will be unfeasibly great when simulating large-scale engineering applications with billions of particles. Accordingly, the coarse-grained (CG) CFD–DEM method is applied to solve this problem. This investigated method replaces several smaller particles with larger ones called parcels, aiming to reduce the number of particles and fully consider the collision of particles between composition parcels and the collision of particles within composition parcels. First, high-speed photography verifies the numerical simulation's reliability. Then, the CG CFD–DEM was used to analyze the transient spatial distribution, transient average velocity, pressure drop, bed height, and the mixing state of particles in a dense gas–solid fluidized bed. The CG CFD–DEM was also compared with the CFD–DEM results, which showed a good agreement with the calculation results and proved the accuracy and applicability of the method. Finally, the computation time of the CG CFD–DEM was evaluated, showing a significant decrease in computation time with an increasing coarse ratio (k). This investigation can provide theoretical reference for the numerical simulation of the CG CFD–DEM method in dense gas–solid flow.

Marble waste derived hydroxyapatite: Low-cost adsorbent for the defluoridation of drinking water

Synthesis of hydroxyapatite (Hap) powder using waste marble powder resource was conducted in a pilot plant scale setup for its application in the defluoridation of drinking water. During synthesis, process parameters such as temperature, process time and pH were optimized so as to obtain good quality hydroxyapatite (MA-Hap LR) products. MA-Hap LR powder was characterised using FTIR, XRD which confirmed formation of purer form of Hap when synthesized at 72 °C having a crystallite size of 43.87 nm and surface area of 24.66 m2/g. SEM and TEM studies of MA-Hap LR indicated rod like morphology similar to pure Hap. The powder was pelletized via the extrusion-spheronization technique in a pelletizer using Polyvinyl alcohol as the binder. Pellets of varying size ranges (2–3 mm) were studied for their fluoride adsorption capacity. Continuous column experiments were conducted to optimize column operational parameters like inlet flow rate, input fluoride concentrations, pellet size, and bed height for maximum fluoride removal. The column fluoride adsorption capacity was obtained at 1.21 mg/g for 10 mg/L input fluoride concentration, bed height 25 cm, 1 LPH flow rate, and processed 28.5-bed volumes at a maximum adsorbent exhaustion rate of 7.4 g/L. Adsorbent regeneration studies indicated that MA-Hap LR72 pellets could be reused for three cycles. The eluent concentration required for the regeneration of exhausted pellets was optimized at 1 M NaOH, confirmed by FTIR and SEM studies of the pellets. The treated water quality was within the acceptable limits for parameters such as pH, alkalinity, hardness and TDS according to WHO and BIS regulations which describe the utility of hydroxyapatite prepared from waste marble powder as a good defluoridation agent for practical drinking water treatment applications.

Design and economic analysis of a pre-treatment process of coffee husks biomass for an integrated bioenergy plant

The beneficiation of coffee produces a large amount of bio-waste, indicating that new policies need to be put into place to address the residues efficiently. Recent studies have shown that coffee husk, particularly, has significant potential for generating electricity but requires a pre-treatment step for efficient thermochemical conversion. Since information about the viability of a pre-treatment process is urgent and necessary and remains insufficient, this study aims to design and perform the economic analysis of a pre-treatment plant of coffee husks, which includes drying, comminution, and densification stages. Drying kinetics experiments were conducted at the laboratory scale to estimate the drying time for the dryer design. A methodology was proposed to encompass equipment design, use of utilities, investment, and total plant costs toward a definition of the optimal operating condition. The economic decision criteria were the net present value (NPV), the payback time (P), and the internal rate of return (IRR). The influence of the drying conditions was analyzed through the leveled cost of production per mass of the briquette (LCM). The results show that the bed height and air inlet temperature were the drying variables with the greatest influence on the design and economics of the plant. The lowest LCM values were obtained for higher values of air temperature, bed height, and biomass flow rate. Economic decision criteria indicated that the project is viable, with an NPV in the range of 28 to 98 million dollars, 166%–574% IRR, and a payback period of 7 months and 7 days.

A Mathematical Simulation of Copper and Nickel Ions Separation Using Prepared Nanocellulose Material.

Environmental risks can arise from the existence of heavy metals in wastewater and their land disposal. To address this concern, a mathematical technique is introduced in this article that enables the anticipation of breakthrough curves and the imitation of copper and nickel ion separation onto nanocellulose in a fixed-bed system. The mathematical model is based on mass balances for copper and nickel and partial differential equations for pore diffusion in a fixed bed. The study evaluates the impact of experimental parameters such as bed height and initial concentration on the shape of the breakthrough curves. At 20 °C, the maximum adsorption capacities for copper and nickel ions on nanocellulose were 5.7 mg/g and 5 mg/g, respectively. The breakthrough point decreased with increasing solution concentration at higher bed heights, while at an initial concentration of 20 mg/L, the breakthrough point increased with bed height. The fixed-bed pore diffusion model showed excellent agreement with the experimental data. The use of this mathematical approach can help alleviate the environmental hazards that arise from the presence of heavy metals in wastewater. The study highlights the potential of nanocellulose as a material for membrane technology, which can effectively address these risks.

Adsorption of Atrazine from Synthetic Contaminated Water Using a Packed-Bed Column with a Low-Cost Adsorbent (Moringa oleifera Lam.)

Atrazine (ATZ) is an herbicide used for increased food production due to its weed and pesticide control capacity in different crops. However, ATZ is a chemical compound that is harmful to the environment and human health, and, unfortunately, it has been detected in surface and groundwater. Therefore, the aim of this paper was to perform the adsorption of Atrazine from a synthetically contaminated water sample using a packed-bed column with a low-cost adsorbent prepared from Moringa oleifera Lam. seeds. The synthesized adsorbent presented an increase in the surface specific area (SBET) of 37% in comparison with the in natura material. The effects of the peristaltic pump flow rate (Q), concentration of the ATZ inlet ([ATZ]inlet) solution, and bed height (H) were studied, with the highest percentage of ATZ removed through the adsorption column (50, 0%) obtained with a packed-bed column with H = 13 cm bed height, Q = 1 mL/min, [ATZ]inlet = 2.0 mg/L, pH = 5.0, a breakthrough time of 25 min, and a saturation time of 420 min. The logistic model was used to best fit the experimental data with an R2 &gt; 0.99, and the Bohart–Adams, Thomas, and Yoon–Nelson models were used to explain and analyze the obtained effects in the continuous adsorption of ATZ. Therefore, the Moringa oleifera Lam. seeds provided a low-cost adsorbent for the continuous adsorption of the herbicide Atrazine in a packed-bed column.

Separation of lead from aqueous phase by cucumber peel in column bioreactor: A phenomenon of interaction between biological and chemical system and its ecological importance

This research work represents a holistic approach of separation of aqueous lead through dynamic adsorption on cucumber peel in fixed bed column bioreactor and highlights the biological perspective of mode of interaction between adsorbent and adsorbate. Additionally attempt has been made to elucidate the importance of this process in preservation of aquatic ecosystem. The study illustrates influence of design parameters, periodic surveillance of generated effluents, statistical and mathematical model analyses of results and desorption. The findings exhibited a direct association between quality of treated effluent and speed of the feed solution, feed concentration and height of the fixed bed. Lead removal percentage was at its best (99.25%) at 8 cm bed height, 20 mL min−1 (0.9 L h−1) flow rate and 50 mg L−1 feed concentration whereas adsorption capacity reached its peak (300.26 mg g−1) when feed concentration was doubled up to 100 mg L−1. Time bound monitoring confirmed concentration of lead in treated effluents remained within satisfactory level. Adsorbed lead was recovered up to ∼95%. Experimentation with actual industrial effluents demonstrated that lead removal percentage remained in the range of 99.97–99.46% and 99.96–99.17% up to the entire phase of bioreactor operation. In summation proper combination of design parameters of column bioreactor played important role in generating superior quality effluent, multiple reuse of the bioreactor bed was dependent on proper eluant treatment and practicability of the study was ascertained by its ability to maintain concentration of lead in actual industrial effluents within permissible limit for prolonged duration.

Continuous fixed-bed adsorption of reactive azo dye on activated red mud for wastewater treatment-Evaluation of column dynamics and design parameters

Continuous adsorption of Remazol Brilliant Blue (RBB) dye in water onto sulfuric acid activated red mud (CATRM) in a fixed bed column was investigated. Breakthrough curves were obtained experimentally by varying the bed height (Z), influent flow rate (Q), and dye concentration(C0). The adsorption efficiency in the removal of RBB was favored at lower C0, higher Z, and lower Q. The maximum adsorption capacity of the activated red mud bed in the column was obtained at C0 = 70mg/L, Z = 8cm, and Q = 5mL/min and found to be 106mg/g. Important parameters of column dynamics and design such as mass transfer zone (MTZ) and length of unused bed (LUB) were evaluated from the breakthrough curves. The MTZ and LUB have varied with varying Z, which indicated the existence of nonideal conditions. Thomas model was found to be valid to predict the column dynamics and the model parameters were evaluated. Bed depth service time (BDST) model parameters were evaluated to facilitate the determination of packed bed height for the design of packed bed adsorption column. The bed could be regenerated with NaOH solution with desorption efficiency decreasing from 83.8 to 55.72% from the first to third cycle. A fixed bed of CATRM can be effectively used for continuous dye removal from industrial wastewater.

Computational fluid dynamics study of hydrogen production by sorption enhanced steam ethanol reforming process in fluidized bed

As a renewable resource, hydrogen plays a pivotal role in the energy transition of the current world. A promising route for hydrogen production is the sorption enhanced steam ethanol reforming (SE-SER), which is characterized by the complex multi-scale characteristics. This paper aims to explore the hydrodynamic (e.g., gas and solid flux, solid dispersion and velocity) and thermodynamic (e.g., particle temperature and heat transfer coefficient) characteristics on the micro-level together with the effect of operating parameters on the SE-SER performance. Accordingly, the reactive multiphase particle-in-cell (MP-PIC) model has been developed under the Lagrangian manner for studying the SE-SER process in the bubbling fluidized bed. In this model, it is assumed that uniform temperature appears inside the particle, and particles with similar properties are packed into a parcel to reduce computational cost. This model has been well validated with experimental data. The results indicate that along the bed height, the solid temperature decreases while the heat transfer coefficient increases. H2 and CO2 have similar distribution in the bed, mainly accumulating in the upper part of the reactor. Enlarging the ratio of H2O to C2H6O in the gas mixture promotes the yields of H2 and CO2. The relationships between key particle variables are explored. It is found that increasing the slip velocity enlarges the particle heat transfer coefficient, and large particle Reynolds number mainly appears with small solid volume fraction. The explored results provide valuable insights into deeply understanding complex multiphase flow and optimizing actual operation of the SE-SER field.

Effect of Dolomite Addition on The Performance of Palm Oil Mill Fly Ash for Methylene Blue Adsorption

The use of palm oil mill fly ash (FA) as a low-cost adsorbent is one of the solutions for handling FA waste. In this study, the addition of dolomite is expected to improve the adsorbent performance. The aim of this study was to investigate the optimum FA-dolomite adsorbent composition and operating conditions for methylene blue adsorption. Different parameters were studied to optimize adsorption process such as the amount of dolomite, methylene blue flow rate, bed height and number of trays. FA-dolomite was converted into nano-adsorbent by sol-gel method which was coated on zeolite surface. Nano-adsorbents were characterized by XRF, FTIR, XRD and SEM. The adsorption capacity was tested by Spectrophotometer UV-Vis. XRF characterization showed that FA had the highest SiO2 content of 58.15%, while dolomite contained CaO of 52.72%. FTIR characterization detected the groups of Si-O-Si, Si-O-Al, Ca-O and Si-O. XRD characterization showed the average crystalline size of FA-dolomite 2% adsorbent was 28.56 nm and SEM characterization showed fine pores on the adsorbent surface. The highest adsorption efficiency obtained at FA-dolomite 2% was 97.364% and the lowest obtained at FA-dolomite 8% was 13.16% with a flow rate of 500 ml/h, adsorbent height of 9 cm and 3 trays. The greater the amount of dolomite added, the absorption efficiency decreases.

Modeling of a Two-Bed Reactor for Low-Temperature Removal of Nitrogen Oxides in Nitric Acid Production

In this study, the modeling of the low-temperature catalytic abatement of NOX and N2O from tail gases in a weak nitric acid plant utilizing a single-pressure 0.716 MPa system was performed. A one-reactor concept assumes that in the first bed, NOX is reduced by ammonia on a commercial vanadia–alumina catalyst, and in the second bed, N2O is decomposed on a proprietary nickel–cobalt catalyst. The kinetics of N2O decomposition on a Cs/Ni0.1Co2.9O4 catalyst was experimentally studied in an isothermal flow reactor. The reaction rate constants were determined by varying the residence time and temperature; these data formed the basis for modeling kinetics and heat and mass transport in an adiabatic reactor in which the low-temperature mitigation of nitrogen oxides occurred. Taking into account the given spatial limitations inside the reactor and the allowable temperatures, the layer heights were evaluated to ensure a residual NOX and N2O content of less than 50 ppm. Catalyst loading using layers in a commercial reactor was estimated for the tail-gas flow rates of 46,040–58,670 m3/h. Simulations showed that the optimum inlet temperature was 260 °C; in this case, the NOX and N2O conversion targets were achieved in the range of 46,040–58,670 m3/h while adhering to catalyst bed height and outlet temperature limitations.

Kinetics models of hydrogen sulphide adsorption from hydrogel biochar derived from empty fruit bunch (EFB)

This research aims to investigate the detailed state of adsorption kinetics modelling and research on the application of hydrogen sulfide adsorption by hydrogel derived from empty fruit bunch (EFB), the determination of the kinetics parameters, and the comparison between models in a selection of the best-fit model.The kinetics modelling used are pseudo-first-order and pseudo-second-order models. The correlation coefficient was used to evaluate the suitability of the equation R2. After obtaining the results, the comparison was made by comparing the R2 of each model. The pseudo-second-order model has a higher value of correlation coefficient, R2, making it the most suitable kinetics model for adsorption systems.The R2 for pseudo-first-order on the effect of dry bed height was 0.8814, whereas its effect on powder bed height was 0.9537, and that of the wet bed height was 0.9607. Meanwhile, the R2 for pseudo-second-order on the effect of dry bed height was 0.89, on the effect of the powder bed height was 0.99, and on the effect of the bed height of wet was 0.99, the highest among kinetic models. Based on the results, the pseudo-second-order model best describes the adsorption of hydrogen sulfide (H2S) by hydrogel biochar.The kinetics modelling used are pseudo-first-order, and pseudo-second-order models for hydrogen sulfide adsorption by hydrogel originating from empty fruit bunches (EFB).Based on the results, the pseudo-second-order model best describes the adsorption of hydrogen sulfide (H2S) by hydrogel biochar. Kinetic studies are important in understanding the reactions and design of the process.The authenticity results of this article were found to be 17% similar. The novelty of this paper is the kinetics study of the new adsorbent developed based on EFB to adsorb H2S.

Pyrolysis of low-value waste Trapa natans peels: An exploration of thermal decomposition characteristics, kinetic behaviour, and pyrolytic liquid product

The current work seeks to maximise the bio-oil yield by optimizing the experimental conditions and process parameters for the pyrolysis of water chestnut peels (WCP). The pyrolysis process was carried out in a stainless steel reactor to produce the pyrolysis product. The kinetic analysis was carried out using the model-free techniques such as Ozawa-Flynn-Wall (OFW), Vyazovkin (VZK), and Kissinger-Akahira-Sunose (KAS), while the thermal degradation profile was measured using a thermogravimetric analyzer (TGA) at dynamic heating rates (10, 15, and 20 °C min−1). Additionally, Gas Chromatography (GC) was used to study the non-condensable gases, whereas biochar was characterized according to its physicochemical properties. The results of the kinetic analysis exhibited that utilising the KAS, OFW, and VZK, the average apparent activation energies of WCP were obtained to be 344.37, 337.10, and 325.10 kJ mol−1, respectively. The thermal pyrolysis results revealed that the highest bio-oil yield (42.20 wt%) was achieved at 600 °C temperature, 25 °C min−1 heating rate, and 6 cm bed height. According to GC results, the hydrocarbon levels increased as the temperature increased. Biochar's suitability for usage in various industrial applications was validated by the findings of its characterization.

Use of response surface methodology to optimize triclosan adsorption on alumina pillared clays in a fixed-bed column for applications in solid-phase extraction

Fixed-bed column studies are generally conducted to consider possible applications in water-purification processes. In this work, three synthetic alumina pillared interlayered clays (Al-PILC) were analyzed in fixed-bed column studies for use as sorbents for solid-phase extraction (SPE) for the first time. Adsorption processes were studied for triclosan (TCS), which is an emerging pollutant (EP) that has been shown to have several health effects. Breakthrough curves were investigated by varying process parameters such as bed height (0.25–0.75 cm), inlet TCS concentration (20–60 mg/cm3), and flow rate (0.5–3 cm3/min). Bohart-Adams, Bed Depth Service Time (BDST), and Thomas models were satisfactory applied to the results obtained for fixed-bed columns. The adsorption of TCS was successfully optimized for use in SPE for the three adsorbents studied using response surface methodology with a Box–Behnken design (RSM-BBD). The models developed were adequate for the experimental data (95% significance level), with high regression parameters (98.9–99.1). The optimum values for TCS adsorption on the fixed-bed column were 378.04, 367.78, and 378.93 mg (amount of adsorbent packed into the column), 0.5 cm3/min (flow rate), 4.24, 3.96, and 3.85 (pH), and 2.56, 1.93, and 1.13 mg/dm3 (inlet TCS concentration) for Al-PILCAE, Al-PILCBE, and Al-PILCCM, respectively. From these results synthetic Al-PILC are effective and promising sorbents that can be used for analytical purposes in SPE, and that RSM-BDD is an effective and reliable tool for evaluating and optimizing the adsorption conditions for emerging contaminants in a fixed-bed column system.

In-situ desulfurization using porous Ca-based materials for the oxy-CFB process: A computational study

Within circulating fluidized bed (CFB) processes, gas and solid behaviors are mutually affected by operating conditions. Therefore, understanding the behaviors of gas and solid materials inside CFB processes is required for designing and operating those processes. In addition, in order to minimize the environmental impact, modeling to reduce pollutants such as SOx emitted from those processes is essential, and simulation reproduction is necessary for optimization, but little is known. In this study, the gas and solid behaviors in a pilot-scale circulating fluidized bed combustor were investigated by using computational particle fluid dynamics (CPFD) numerical simulation based on the multiphase particle-in-cell (MP-PIC) method under oxy-fuel combustion conditions. In particular, the combustion and in-situ desulfurization reactions simultaneously were considered in this CPFD model. Effect of fluidization number (ULS/Umf) was investigated through the comparison of particle circulation rates with regards to the loop seal flux plane and bed height in the standpipe. In addition, the effects of parameters (temperature, Ca/S molar ratio, and particle size distribution), sensitive indicators for the desulfurization efficiency of limestone, were confirmed. Based on the cycle of the thermodynamic equilibrium curve of limestone, it is suggested that direct and indirect desulfurization occur simultaneously under different operating conditions in CFB, creating an environment in which various reactions other than desulfurization can occur. Addition of the reaction equations (i.e., porosity, diffusion) to the established simple model minimizes uncertainty in the results. Furthermore, the model can be utilized to optimize in-situ desulfurization under oxy-CFB operating conditions.

Research on the Quality Improvement and Consumption Reduction of Iron Ore Agglomeration Based on Optimization

In order to increase agglomeration production and improve its quality while reducing energy consumption, a new intelligent blending method has been established at Ansteel to optimize its sinter blends. The statistical model of the ore blending results shows that (1) a blending ratio of 47.2% Ore A and 52.8% Ore C corresponded to the best sinter yield of 72.44%. (2) From the viewpoint of sinter reducibility, sinter basicity should not be less than 1.98 when the proportion of Ore A in the blend is more than 35%. Due to the low mixing efficiency of disc pelletizers, Ansteel has therefore gone through a massive technical transformation at Sinter Plant 3 to replace its 16 existing disc pelletizers with one drum granulator. Since the installation of the drum granulator, the standard deviation has decreased from 1.517 to 0.7332 for total Fe (T.Fe) and from 0.146 to 0.0956 for basicity. In the case of the drum granulator, the standard deviation for sinter T.Fe and basicity were 0.6926 and 0.05449, respectively, as compared to 0.8902 and 0.2033 for the disc pelletizers. In addition, a single lattice method is proposed to optimize the particle-size distribution of the coke breeze to further improve sinter quality and reduce fuel consumption. The lattice method indicated that the optimum coke breeze to achieve maximum sinter tumble strength should consist of approximately 57.20%: −1 mm, 25.63%: 1–3 mm, 11.17%: 3–5 mm, and 6.00%: &gt;5 mm particles. Given the international trend of increasing bed depth, Ansteel has successfully achieved a bed height of 1050 mm or more under its blend conditions, which typically contain 75% concentrates. Finally, some new iron ore agglomerations research is discussed.

Reduction of chemical oxygen demand of vinasse using sugar cane bagasse ash geopolymer

The aim of this study was to determine the use of sugar cane bagasse ash geopolymer (SCBAG) as an adsorbent for organic compounds to reduce the chemical oxygen demand (COD) of vinasse. The effects of solid loading, time and temperature on batch adsorption were investigated, while the effects of bed height and flow rate were investigated through column studies. The adsorption of organic compounds onto SCBAG could be modelled well using the Langmuir isotherm and pseudo-second-order kinetics. The maximum batch adsorption capacity was 738 mg/g at 298.15 K after 5 h of adsorption. The column studies showed that the highest COD reduction of 81% could be achieved using a flow rate of 2.5 ml/min and a bed height of 13 cm. These conditions gave a dynamic uptake of 107 458 g and a breakthrough time of 600 min. The column adsorption could be best described using the Bohart–Adams model, giving a correlation coefficient of 0.98, a Bohart–Adams rate constant of 3.05 × 10−8 l/(mg min) and a saturation concentration of 6.93 × 107 g/l. The SCBAG could be regenerated and be used as an adsorbent in three cycles without significant loss in adsorption capacity.

Optimization of the esterification of oleic acid and ethanol in a fixed bed membrane reactor by response surface method

In this study, the kinetics of the esterification reaction of oleic acid (OA) and ethanol enhanced by dehydration using a fixed bed coupled pervaporation (PV) technology was studied, as well as the effects of the various factors’ interactions on the conversion rate of OA. The influences of ethanol/OA molar ratio, catalytic bed height, feed speed and reaction temperature on the conversion rate of OA were respectively investigated. The response surface method (RSM) and Box-Behnken design (BBD) are combined to optimize the experimental scheme. The results showed that the conversion rate of OA reached peak of 99.32 % when the molar ratio of ethanol/OA was 9:1, the catalytic bed height was 150 mm, the feed speed was 0.2 ml/min, and the reaction temperature was 80℃. Compared with the esterification reaction without PV, the conversion rate of OA was increased by 12.69 %. Through the kinetic model, the esterification reaction rate constant k1 (30.447), the reaction activation energy Ea1 (36.665 kJ/mol), the preexponential factor A1 (7.889), the pervaporation process activation energy Ea2 (15.788 kJ/mol), and the preexponential factor A2 (3.548) could be counted. To our surprises, the H-type cation exchange resin (H-CER) still showed high catalytic activity after six cycles.

Dimensioning Air Reactor and Fuel Reactor of a Pressurized Chemical Looping Combustor to Be Coupled to a Gas Turbine: Part 1, the Air Reactor

This paper provides a simple methodology for the design of the air reactor of a chemical looping combustor to optimize its characteristics when it is employed connected to a turbo expander to produce power. The design process, given a certain objective (e.g., electric power) defines the reactor specifics, namely height and diameter, taking into account the following aspects: solids inventory of the air reactor; gas velocity; air reactor transport disengaging height (TDH); solids concentration profile along the reactor height, dense bed height; freeboard height; pressure drop depending on air reactor injectors design and configuration. The total air reactor height was about 9.5 m, while the diameter was about 1.8 m. The total inventory was about 10,880 kg; while the circulation rate in the air reactor was about 110 kg/s. The operating pressure and temperature were, respectively, 12 bar and 1200 °C. The average velocity of the gases inside the reactor was about 4 m/s. The fluidization regime resulted to be comprised between turbulent and fast fluidization. Further work must be directed into the estimate of the pressure drop of the reactor, which will affect the plant efficiency in a considerable way.