Screw Reactor Research Articles

Experimental study of the wall particle motion in a screw reactor

Screw reactors are gas/solid systems widely employed in industrial applications. Understanding the local powder mixing within these reactors is crucial, particularly at the reactor wall where wall/solid heat transfer occurs. This study proposes a non-invasive measurement method utilizing optical devices to assess wall particle motion. Two techniques for evaluating the particle motion are compared: a simple visual tracking method and particle image velocimetry. Both methods yield similar results, demonstrating consistent wall particle motion across the tube periphery during experimentation. The influence of operational and geometric parameters has been investigated, revealing that filling degree, powder flowability, and screw geometry significantly impact wall particle motion. Symbolic regression has been employed to derive dimensionless models that effectively predict experimental data. These models can be utilized to forecast wall particle motion, serving as a valuable tool for screw conveyor design.

Comparative assessment of biochar produced from waste biomass in laboratory furnace and industrial screw reactor systems

Biochar is rapidly gaining traction as a commercially viable carbon dioxide removal (CDR) technology that can be applied globally at various scales. However, the vast majority of published research studies have involved laboratory experiments conducted in an inert environment under well-controlled conditions of heating rate, maximum temperature and residence time. To expand the biochar industry within the next decade as a CDR platform, there is a need to understand differences between biochar produced under “ideal” laboratory conditions versus those generated using the same feedstocks in continuous, industrial scale systems. In the present work, biochar was produced from widely available organic waste feedstocks, including mixed cafeteria food waste, blended coffee grounds and chaff, grape pomace and wood pellets, using both a laboratory furnace operated in a nitrogen environment, and a continuously operated commercial system capable of processing up to ∼1 t/day of dry feedstock. High quality biochar (H:C < 0.7) was obtained for all feedstocks converted by both systems, however high variability in volatiles and decomposition rates was observed in the thermogravimetric analysis (TGA) results for industrial scale biochar. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed similar morphologies and surface chemistries in both laboratory and industrial scale samples, in agreement with reported literature data. Based on this initial comparative assessment, we conclude that commercially available thermochemical systems have potential as localized organic waste valorization technologies to produce high quality biochar. We identified important control variables that have the greatest effect on the resulting biochar. Despite the reported differences between biochar materials derived from the same feedstock, key properties critical for soil amendment and remediation applications (i.e., H:C, surface area, %Corg, etc.) are reasonably consistent between laboratory and continuously fed equipment typical of commercial-scale systems. Thus, biochar materials obtained from well-controlled laboratory experiments conducted in a pure nitrogen atmosphere can be reasonably representative of biochar produced from the same feedstocks using industrial scale equipment.

Performance Improvement of Flow Rate of Spiral Chip Feeder in Domestic Cattle Manure monitor Making Machine

The abstract outlines a study focused on the stability and effectiveness of a screw feeding mechanism designed for the outlet of pulping material in a screw reactor. This reactor functions as a continuous system where material is transported and mixed by a screw (augur). The study emphasizes the importance of operational conditions in influencing the process outcomes. To efficiently understand and optimize the system, the researchers employed modelling techniques, which are often quicker and more cost-effective than conducting experiments. The paper provides a comprehensive list of modelling approaches, both validated by experiments and theoretical, that is applicable to various aspects of screw reactor operation. Additionally, the study delves into new product development, specifically shaping a conical screw feeding reactor along with its shaft and flights design. A crucial aspect analyzed is the radial force effect on the flight surface during spiral rotation. Structural engineering techniques were employed to ensure the sustainability of the design, with validation results confirming its effectiveness. Keywords: Screw, Radial Force, Pulping Material

Screw reactor design for potato peel pretreatment using the steam explosion

In this article we can observe the scanning by the literature for the pretreatment of steam explosion applied to lignocellulose biomass. A comparison of the chemical and physical characterization of potato peel as a lignocellulose biomass. Besides, the innovative design of a continuous reactor for the potato peel steam explosion process is shown, with specific temperature and pressure conditions on a pilot scale, detailing its parts. Finally, a finite element analysis was performed where stress results were obtained from the reactor material, severity factor, structural analysis and thermal analysis, providing a panorama of the reactor’s behavior with the conditions specific.

Production and characterization of wood biochar from energetic forests by pyrolysis in a horizontal screw reactor

Production and characterization of wood biochar from energetic forests by pyrolysis in a horizontal screw reactor

Platform chemicals recovery from spent coffee grounds aqueous-phase pyrolysis oil

Spent coffee grounds (SCG) are a valuable biogenic waste diffused on a global scale, containing a significant amount of extractives. The aim of this study is to characterize the pyrolysis oil fractions, under various process conditions, targeting their potential applications as biofuels and source of valuable chemicals. Pyrolysis tests were carried out in the range of 400–550 °C with a laboratory-scale screw reactor and a two-step solvent extraction process, was conducted for the aqueous bio-oil phase. The results showed that heavy organic bio-oil resulted in a carbon rich biofuel, with a carbon content of up to 63 % (w/w) and HHV up to 34.8 MJ/kg. Chloroform was selective in extracting xantines (68–74 % of the peak area), furans, phenols, and fatty acids from the aqueous phase, while the ethyl acetate extract was abundant in p-benzoquinone (70–83 % of the peak area), a key-player chemical for the petrochemical industry. The residual unextracted water phase is very rich in organic acids i.e. acetic, propionic, and formic-whose concentration is in the range 47 g/L and 87.9 g/L. The results of this study outline how solvent extraction is a promising technique for extracting valuable chemicals to improve the economic potential of spent coffee grounds pyrolysis-based biorefinery.

Defatted spent coffee grounds fast pyrolysis polygeneration system: Lipid extraction effect on energy yield and products characteristics

Spent coffee Grounds (SCG), residues after coffee brewing, are a biowaste diffused on a global scale rich of valuable extractives. Pyrolysis is an efficient process to valorize SCG energy content into biofuels. This study aims to experimentally investigate the impact of lipid extraction and conversion to biodiesel on energy yield of pyrolysis products. Microwave-assisted lipid extraction method was employed, and a two-step transesterification process was considered for conversion into biodiesel. Fast pyrolysis of defatted spent coffee grounds (DSCG) was performed with a 300 g/h screw reactor at the temperatures 400 °C and 550 °C. The results show an important impact of pyrolysis temperature on energy distribution of the pyrolysis products. The energy content of the organics from DSCG pyrolysis is very high (up to 32 MJ/kg) and the oxygen content is significatively reduced to 26%. Non-condensable gas composition is enriched of hydrogen and methane with temperature rise. Biodiesel energy contribution significantly improve the energy yield of the pyrolysis system, leading to a more than 10% increase of the energy efficiency at a 550 °C, while a limited increase of 4% in the case of 400 °C. This study outlines how lipids extraction significantly increases the economic potential of SCG pyrolysis-based polygeneration energy system.

Modelling of powder hydrodynamics in a screw reactor

Screw reactors are largely used devices in the industry. Very few studies focus on the powder hydrodynamics in screw reactors. The overflow point, a filling degree value when the powder passes over the shaft, was determined for different conditions and a dimensionless model was fitted to predict this parameter. The residence time distribution (RTD) has been measured with a pulse injection of salty powder. The influence of operating conditions and geometry parameters on the RTD has been studied. It appeared that the Hausner ratio, the pitch length and the filling degree mostly influence the RTD shape. Two models for the RTD have been compared: the compartment model was the most accurate and has one parameter of adjustment. A dimensionless model was developed and fitted with 51 experimental RTD results, predicting the RTD shape. The dimensionless model predicts with good accuracy other experimental data from the literature.

Correction: Continuous flow solvent free organic synthesis involving solids (reactants/products) using a screw reactor

Correction for ‘Continuous flow solvent free organic synthesis involving solids (reactants/products) using a screw reactor’ by Brijesh M. Sharma et al., Green Chem., 2019, 21, 5639–5646, https://doi.org/10.1039/C9GC02447F.

Direct amidation of acids in a screw reactor for the continuous flow synthesis of amides.

A simple and efficient solvent-free protocol for continuous flow synthesis of amides at room temperature is developed using easily available starting materials. N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC.HCl) was used as the reagent for the formation of an amide bond without using any metal catalyst or additives. A jacketed screw reactor when operated over a residence time of 30 300 s helped achieve almost complete conversion. This approach is extended for the synthesis of 36 derivatives and 2 bioactive molecules using different substrates having different aliphatic mono and di-acids as well as aromatic acids, including aromatic hetero-acid compounds and phenyl hydrazine. The target amide was scaled up to 100 g with an average 90% yield.

DEM simulation of biomass pyrolysis in a novel interconnected screw reactor

Abstract A novel interconnected screw reactor was proposed to convert biomass to bio-oil and bio-char in this study. This reactor is expected to achieve direct heating of pyrolysis feedstocks and increase the reactor processing capacity through the recycling of biochar between the inner and outer screw. Here, we simulated the biomass particle flow and reaction process in this interconnected reactor by an extended discrete element method (DEM), the effect of char circulation on the reactor temperature distribution and the product yields are investigated. The results show that the char circulation increased the heating rate of biomass. At the inner and outer screw speed of 10 rpm and 1 rpm, the char circulation can reach 5.15 kg/h and the average temperature of biomass under the char circulation is about 30 °C higher than that without char circulation. The reaction simulation results show that at 500 °C, the yield of char, bio-oil and non-condensable gas are 18.9%, 40.6% and 40.5% respectively. The predicted product yields of char, bio-oil and non-condensable gas are also in good agreement with the experimental measurements.

Importance of residence-time control of industrial screw-conveying reactors: Application to dilute-acid hydrolysis of biomass

Horizontal screw reactors are utilized in biorefineries for acid-catalyzed hydrolysis of xylan, which is a multi-step chemical reaction requiring accurate residence-time control. However, it is difficult to obtain online analytical measurement of reactant species. A residence-time distribution (RTD) is exhibited whose characteristics influence species yields. Sensitivity of product yield to RTD was investigated to understand the relative importance of operating control vs. inherent reactor dispersion. We find that reactor operation using a commonly used theoretical residence-time relationship can result in substantial yield losses. Instead, a model that accounts for the actual reactor RTD provides much improved results. The dispersion caused by reactor conditions only slightly hinders achieving theoretical optimal xylose yield (less than 3% yield loss for coefficient of variation less than 0.35), provided a validated RTD model is used to target the desired mean residence-time. In contrast, neglecting to account for the RTD by using the simplistic theoretical calculation results in xylose yields that are as much as 16% lower than the theoretical maximum.

Evaluation of weight loss and high heating value from biomasses during fungal degradation by NIR spectroscopy

Lignocellulosic biomasses have some characteristics that hinder their use as fuel. Further, the biodegradation processes that can occur during storage can affect their energy properties. Torrefaction can improve their energy properties while reducing the impacts of storage. Near-infrared (NIR) spectroscopy could be a promising tool to estimate changes to biomass properties during storage. A series of waste feedstocks, including: sugarcane bagasse, coffee husk, eucalyptus, and pine were torrefied at 290 °C in a screw reactor, over 5, 7.5, 10, 15, or 20 min. Then, raw and torrefied biomasses were submitted to leaching and to white and brown-rot fungi, to simulate storage conditions. The weight loss (WL) due to fungal degradation after 2, 4, 8, and 12 weeks was measured and the high heating value (HHV) of all biodegradation steps, including raw and torrefied samples after leaching, were determined. All the samples were analysed by NIR spectroscopy and chemometric models were then developed. Firstly, partial least squares for discriminant analysis (PLS-DA) models successfully classified the four different residual biomasses into raw and torrefied forms according to fungal decomposition. Secondly, partial least squares regression (PLSR) models showed potential utility in an industrial context as a standardized continuous method to predict the HHV during biomass storage steps. While, PLSR models did not present good accuracy when estimating WL resulting from fungal degradation, they can be useful for screening during decision making. Further studies are required to improve and develop more efficient models to predict the fungal degradation level of stored biomasses. For exemple, in considering the class of torrefied biomasses, the model could show better predictive capacity due to less variability in the data. These results highlight the potential of NIR spectroscopy as a simple, fast, and efficient tool to analyze the degradation process over time. Such a rapid and non-destructive characterization tool could be very useful in industry to assess biomass property changes during storage.

Single-Phase Flow Model of a Screw Reactor for Decontamination of Radioactive Graphite Waste Using Surface Gasification

A screw reactor is a promising apparatus for decontaminating radioactive graphite waste by uniform gasification under ambient air. However, developing the design equation for a screw reactor is difficult due to the reactor’s fundamentally intricate gas and solid interactions. In this study, we performed three-dimensional computational fluid dynamics simulations to predict and characterize the graphite particles that flow through the screw reactor and are thermally gasified. This was done using the Eulerian single-fluid approach coupled with the experimentally established kinetic model for graphite gasification. The numerical results show that the counter-rotating flow, generated along the rotating screw of the reactor by the relative motion of the reactor wall to the rotating screw, mixes particles spatially and reduces their axial velocity. The diameter of the feed graphite particles can be reduced by as much as 28% depending on the screw rotating velocity and the temperature of the reactor shell, according to the conducted numerical calculations. These numerical simulations can be used to provide proper operating parameters for the laboratory-scale screw reactor by which to decontaminate radioactive graphite waste by gasifying the radiocarbons, together with a part of the graphite matrix, on the surface of the graphite particles.

Experimental investigations on sugarcane bagasse pyrolytic oil production from flash pyrolysis using a rotary screw reactor

AbstractA rotary screw pyro‐oil reactor was designed for powdery biomass for a feeding capacity of 40 kg h−1 with a moisture content of &lt;10%. The pyro‐oil reactor temperature was maintained at 450–550 °C. The pyro‐oil vapors produced were quickly drafted out of the reactor for quenching to yield 16–24 L h−1 from 40 kg h−1 of biomass feed. The flash‐pyrolysis technique, which is capable of directly turning biomass into a liquid fuel, was used to produce liquid fuel (bio‐oil). It was carried out at a pressure at 0.03 bar and at a medium temperature of about 550 °C. The flash‐pyrolysis technique converts the entire biomass matter, excluding the ash. In this method the powdery biomass is converted into three components: bio‐oil (the yield is typically 70% on an energy basis, a powdery biomass feed at a moisture content of 10%); pyrolysis gas (typical yield 14%) and char (typical yield 16%). The temperature of the fixed bed was adjusted in the experiment, but the other variables remained constant, such as the amount of feed, the pyrolysis time of the gas product, the reactor pressure and the bed height. A biomass particle size range of 1–3 mm and a biomass residence time of 20 s in the reactor resulted in optimal bio‐oil production of 70%. This work demonstrated how precise pyrolysis mechanism processes and bio‐oil yields can influence the maximal reaction temperature in the 450–550 °C range. The performance analysis reveals that the fixed bed reaction temperatures of biomass rapid pyrolysis give reliable control over the bio‐oil reactor type and size. This paper provides an overview of the design and thermochemical liquefaction process used to convert powdered biomass to biofuel. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Study of the kinetics of carboxymethyl cellulose synthesis in a screw reactor

The object of research is the reactor for the synthesis of carboxymethyl cellulose. An important indicator of the quality of sodium carboxymethyl cellulose, which determines the field of its application, is the degree of polymerization. However, obtaining a product with a specific parameter under industrial conditions is associated with a number of difficulties. Therefore, important research tasks are the development of a mathematical model of the kinetics of carboxymethyl cellulose synthesis, experimental studies to determine the rate constants of synthesis reactions, modeling of a screw reactor for the synthesis of carboxymethyl cellulose, and computer studies. When studying the kinetics of reactions of carboxymethyl cellulose, one of the possible approaches was to use a quasi-homogeneous model, which is widely used in modeling processes on a catalyst grain. This approach is used to describe and analyze individual stages; however, a number of difficulties arise in heterogeneous reactions of cellulose. In the course of these reactions, the properties of the solid phase change and the processes, respectively, are unsteady in time. The reaction does not take place on the surface of hard particles, but in the entire volume of the fibers. The concentration and reactivity of cellulose hydroxides, water, and products formed during the reaction remain approximately constant; therefore, the use of a quasi-homogeneous model is quite acceptable and does not cause additional mathematical difficulties. As a result of these experiments, according to the obtained integral curves, the method of least squares was used to find the constants. To determine the values of the kinetic constants, an experiment was carried out in an integral isothermal reactor. During the experiments, the degree of substitution of carboxymethyl cellulose and the concentration of free alkali were measured. As a result of numerous implementations of the search task, the values of the constants and activation energies were obtained. This kinetic modeling approach can be used in the synthesis of other cellulose ethers. The rate constant of the synthesis reaction depends on the process conditions. Using the proposed approach to describing the interaction of cellulose with a reagent, the reaction mixture considered as a quasi-homogeneous system can be described using a single-phase flow model.

Large-scale synthesis of functional tungsten oxide with controlled oxygen-deficiency by a continuous screw reactor

Oxygen-deficient tungsten oxide is one of the promising materials for broad applications due to its enhanced characteristics owing to the oxygen-deficiency. Development of a mass production process is crucial in consideration of the increasing demand of this material in industrial purposes. A continuous screw reactor was employed to the production of oxygen-deficient tungsten oxide. The effects of hydrogen concentration and the reduction time on the composition of products were investigated. The maximum WO2.72 mole fraction of 0.95 was achieved by optimum hydrogen concentration and reduction time. X-ray Photoelectron Spectroscopy (XPS) spectra of the products indicated the introduction of oxygen-deficiency. Anisotropic crystal growth in the (010) direction is found in the cross-section observation by Scanning Electron Microscope (SEM). The displacing value from High-Resolution Transmission Electron Microscope (HR-TEM) demonstrated the existence of WO2.72. The reaction kinetic was investigated by thermogravimetric analysis. Estimated activation energy supported the results from the continuous process. This work suggests the promising process for the large-scale production of functional materials.

Pyrolysis of Forestry Waste in a Screw Reactor with Four Sequential Heating Zones: Influence of Isothermal and Nonisothermal Profiles

Woody biomass waste (Pinus radiata) has been pyrolyzed in a laboratory-scale continuous pyrolysis plant, formed by two reactors connected in series: one continuous auger reactor, where the pyrolysis process is performed, and a tubular reactor for vapors upgrading, where the thermal treatment of the pyrolysis vapors occurs to promote further cracking. The pyrolysis reactor has four different heating zones that allows programming different temperature profiles. An extensive and detailed thermal study has been performed using temperatures covering the range from 300 °C to 900 °C in regimes of scaling temperature profiles and isothermal profiles. Both the peak temperature and the heating rate affect the pyrolysis fraction yields, as well as products composition. Higher temperatures result in higher gas yield and lower solid and liquid yields. Increasing the temperature also increases the fixed and elemental carbon contents of the charcoal obtained, and decreases its volatile matter and the hydrogen and oxygen contents. Concerning gas fraction, the share of CO and hydrogen rises with the temperature. The increase of temperature gives rise to heavier liquids with more polycyclic compounds and less monocyclic compounds. The changes in the composition of the charcoal and gas products are more prominent between 300 °C and 700 °C. Compared to nonisothermal experiments, isothermal experiments enhance the production of gases, to the detriment of solid and liquids, but do not affect product composition.

Combustion and emission characteristics of diesel engine fueled with nanocatalyst and pyrolysis oil produced from the solid plastic waste using screw reactor

In recent years, the concerns of non-biodegradable mixed plastic waste have been growing and resulting in strengthening of technologies devoted to convert waste into energy. This study examined the technique to extract plastic oil from mixed plastic, non-biodegradable waste. Further, the mechanical characteristics of plastic pyrolysis oil were done. Pyrolysis method was used to extract the oil from plastic waste with screw reactor and the chemical compounds and the characterization of this oil was analyzed. The Fe2O3 doped Al2O3 was dispersed to enhance the quality of Waste pyrolysis oil (PO) by ultrasonication. The performance and emission characteristics of various fuels at different load conditions were analyzed by conducting a series of tests in single cylinder 4 stroke water cooled diesel engine. The benefit of the addition of 25 ppm of Fe2O3 doped Al2O3 in PO was represented graphically. A series of tests was conducted for various brake mean effective pressure of 1.3 bar, 2.6 bar, 3.9 bar and 5.2 bar for the test blends, PO (neat pyrolysis oil) and P25A (25% PO+ 75% diesel with 25 ppm of Al2O3). From the procured results, the addition of the novel nanoparticles increases the production of brake power by 35% with reduced emission of 45% and 60% of HC and CO2 respectively. On the other hand, the NOx emission was reduced by 15% and 9 % than the neat plastic oil and diesel fuel. Further, the usage of the pyrolysis oil at 25% generated the positive effects on both combustion and emission compared to neat PO.

Numerical Simulation of Thermal and Mass Behaviors During Pyrolysis Homogeneous Reaction Within a Screw Reactor

Numerical Simulation of Thermal and Mass Behaviors During Pyrolysis Homogeneous Reaction Within a Screw Reactor