14 research outputs found
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Spent coffee grounds as a renewable source of energy: an analysis of bulk powder flowability
The main use for spent coffee grounds (SCG) produced in the soluble coffee industry is thermal energy generation in the industry itself. The SCG are processed using operations that are strongly dependent on powder flow behavior. In this study, we evaluated two classical flowability indices of non-consolidated SCG powders: the angle of repose (AoR), and the Hausner ratio (HR). The influences of the mean particle diameter, particle size distribution (PSD), and water content on the AoR and HR values of SCG were analyzed for powders with a mean particle size range of 225–550 μm. For powders with a mean particle size close to 350 μm and for mixtures containing more than 40% fine particles, the HR (>1.35) and AoR (>45°) values were characteristic of poor flowability. The AoR was sensitive to the powder PSD, and powders with similar mean particle sizes had higher AoR values when the PSD was larger. For powders with water contents up to 50%, the flowability indices were not greatly affected by the water content. A modified linear-mixture packing model was used to predict the packed bed void fractions for binary and ternary mixtures of the three base powders. The model was used to construct a ternary diagram to estimate the HR values of the mixtures. An equation was fitted to correlate HR and AoR. The proposed diagram and the equation provide insight into flow behavior and could be used for process design of industrial plants that handle SCG
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Segregation of formulated powders in direct compression process and evaluations by small bench-scale testers
Powder segregation can cause severe issues in processes of pharmaceutical drugs for control of content uniformity if the powder is likely to be free or easy flowing. Assessing segregation intensity of formulated powders in a process is challenging at the formulation stage because of the limited availability of samples. An advanced segregation evaluation using small bench-scale testers can be useful for formulation decisions and suggestions of operation conditions in the process, which has not been practically investigated before. In this study, eight formulations (two co-processed excipients blended with one active pharmaceutical ingredient at different ratios) were used for the segregation study on two types of bench-scale testers (air-induced and surface rolling segregation tester), and a pilot simulation process rig as a comparative study. The results show that segregation measured on the bench-scale testers can give a good indication of the segregation intensity of a blend if the segregation intensity is not more than 20%. The comparison also shows that both the bench-scale testers have a good correlation to the process rig, respectively, which means either segregation tester can be used independently for the evaluation. A linear regression model was explored for prediction of segregation in the process
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Evaluation of segregation of pharmaceutical formulations in direct compression process
The phenomenon of powder segregation during the direct compression process can pose a significant challenge in controlling of content uniformity in blended powders, particularly when the powder exhibits characteristics of being free-flowing or easily flowing. Evaluating the level of segregation in powders at early formulation stage faces a significant challenge due to the scarcity of available samples. The utilisation of small bench-scale testers for an advanced segregation evaluation can provide valuable insights for making formulation decisions and recommendations for operational parameters in a process that has not been extensively studied previously. This study utilized a total of eight formulations, each consisting of a combination of two co-processed excipients blended with one active pharmaceutical ingredient at varying concentrations. The objective of the study was to investigate the phenomenon of segregation using two different types of bench-scale testers, namely the air-induced segregation tester and the surface rolling segregation tester. Additionally, a pilot simulation process rig was employed to conduct a comparative analysis. The findings indicate that the assessment of segregation on bench-scale testers can effectively serve as an indicator of the level of segregation within a blend for a process, if the segregation intensity does not exceed 20%. The comparison also demonstrates that both the bench-scale testers exhibit a strong correlation with the process rig, indicating that any segregation tester can be utilised autonomously for the purpose of evaluation. The study investigated the use of a linear regression model to predict segregation in the process
Biomarkers for the assessment of chlorpyrifos effects on earthworms and on soil functional parameters
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Densification behavior of dry spent coffee ground powders: experimental analysis and predictive methods
The knowledge of bulk properties and densification behavior of Spent Coffee Ground (SCG) powders can be useful in handling such powders through the typical processing units of the soluble coffee industries. In this paper we measured the bulk densities of SCG mixtures with mean sizes from 225 to 550 μm as a function of tapping and tested a number of selected equations to predict the densification behavior of these mixtures. Densification kinetics of SCG powders was found to be overwhelmingly driven by the mass fraction of fines in the mixture. The equations proposed by Kawakita and Ludde (1971), Knight et al. (1995) and Mallol et al. (2008) predicted well the variation of bulk density of SCG powders throughout tapping. Nevertheless, the Kawakita and Ludde's equation is recommended as the most suitable because the fitted parameters in this equation could be correlated to the powders' mean size and Hausner ratio. Besides, three methods to predict the densification curves were proposed. In the first method, the powders' mean diameter is used to predict the densification kinetics and in the second the angle of repose and the loose bulk density of the samples are used. Finally, the third method is based on coupling the densification equation to the Modified Linear-Mixture Packing Model. The three approaches led to predictions of bulk density with deviations <10% in comparison to the experimental data and can be recommended to estimate the densification kinetic behavior of industrial SCG powders
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On the performance of a spouted bed type device for feeding spent coffee grounds to a circulating fluidized bed reactor
Using solid biomass wastes as feedstocks for industrial generation of renewable energy is appealing to meet company's energy demands with environmental awareness; however, maintain continuous feeding of wastes to reactors remains a challenge in processing. In this study, the performance of a non-mechanical spouted bed (SB) feeder was evaluated for handling dry and moist spent coffee ground (SCG) powders to a circulating fluidized bed reactor. A comprehensive experimental study was carried out to investigate the effects of operating variables and air inlet nozzle configuration on the solids circulation rates and pressure profiles. Using a convergent nozzle at the air inlet improved feeding stability compared to a conventional orifice air inlet. The circulation rates could be varied from 3.0 < WS < 11.0 g/s by adjusting the air flowrate and the entrainment length. Although SB performance was affected by the powder's flowability, the feeder operation was rather stable, with fluctuations less than 20% in WS. Moreover, WS could be accurately predicted from pressures measured at the feeder and riser. The SB showed enhanced flexibility in handling SCGs with different properties compared to a non-mechanical L-valve. It suggests that SBs might be an appealing alternative to feed waste biomass powders into reactors in a continuous mode
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Characterization of a pressurized feeder for biomass injection into gas-solid systems
Injection of biomass powders into multiphase reactors is a challenging task that may impact the process yield and limit the operation due to the feeder’s blockage or unstable flow. A horizontal pressurized gas-solid feeder is characterized in this study to inject a batch of biomass powders of different diameters into cold-flow model operating under single phase, and multiphase fixed and fluidized regimes. The gas-solid hydrodynamics in the injection line is investigated for different operating conditions, using a fast camera with acquisition rate of 3000 images/s. Stable injections are performed in a wide range of solids fluxes, and under different solid concentration flow conditions. The operation map for the feeder is produced, and the phenomena that produce difficulty of stable injection are discussed. Ultimately, this type of solids injector is useful for feeding powders into lab-scale reactors for mixing and kinetic studies and might be also scaled-up for treating waste biomass powders into pilot-to-industrial scale reactors under batch or semi-continuous operations
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Medical suction pump controller - Certificate of Registration of Design No 360064-001
Design Medical Suction Controllers suit many applications. High Vacuum Suction Units are used in Operating Theatres, Intensive Care Units, A&E Departments, and Ward Areas. The controller can set the vacuum level between zero and the full vacuum pipeline. Low Vacuum Suction Units are used in Pediatric departments; the controller can set the vacuum level between zero but not exceeding (-150mmHg). Thoracic Suction Units are used where Abdominal or Pleural cavity drainage is required; the controller can set the vacuum level between zero but not exceed (-53mmHg)
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On the design of conical hoppers for spent coffee grounds: moisture content and particle-size effects
Spent coffee ground (SCG) is a food waste with promising potential for reuse in pilot-to-industrial scale processes provided that storage and handling issues are overcome. Here some key bulk and flow properties of SCGs were determined with FT4 rheometer, for powders with different particle-size distribution (249.1 ≤ dV ≤ 583.1 μm) and moisture content (2.8% ≤ MC ≤ 62.5%). These properties were used to evaluate the design of mass-flow silo hoppers following the classical Jenike theory. The SCGs flowability worsened by decreasing dV and increasing MC, with indexes between 1.09 ≤ HR ≤ 1.92 and 2.5 ≤ FF ≤ 15.0. The minimum hopper inclination and outlet diameter ranged from 9.9° to 17.1° and 0.40–1.00 m. A sensitivity analysis for the hopper design was performed, and a densification equation was coupled to Jenike's method to ease future hopper designs for SCGs with different properties. Ultimately, the results showed that careful consideration must be given to dV and MC to design effective devices to handle SCGs
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Feeding spent coffee grounds into reactors: TFM simulation of a non-mechanical spouted bed type feeder
Due to the increasing coffee production, Spent Coffee Grounds’ (SCGs) generation has grown dramatically, hence appropriate management of this solid biomass waste is imperative. SCGs can be used as feedstocks for renewable energy and fuel generation provided that a stable feeding of powders to reactors is maintained. Recently, a non-mechanical spouted bed feeder proved itself an excellent alternative in feeding SCGs to a pilot-scale circulating fluidized bed reactor. Nonetheless, further studies are necessary for the feeder’s implementation in commercial applications. Here the feeding of SCGs with the spouted bed feeder is addressed by using Computational Fluid Dynamics. Firstly, a Two-Fluid Model (TFM) is validated against experimental data, and then the effects of five operating and design parameters were analyzed aiming at improving the handling of SCGs. The solids flowrate (WS) in the reactor could be stably controlled from 4 to 30 g/s depending on the settings. The feeder performance is enhanced by operating it under high gas flowrate (Q), high entrainment length (z), and high mass of solids in the feeder (HS). Using feeders with low cone angle (γ) or reactors with large diameter (DR) increases WS, which is appealing for the operation of medium-to large-scale units. The proposed TFM is a cost-effective tool for implementing spouted bed feeders in commercial applications. With the feeder coupled to the process, SCGs are treated continuously in the reactor for energy generation, thus reducing the disposal problems associated with this waste and improving the management of SCGs globally