Solid Mass Flow Rate Research Articles

Effect of resistance components on solid mass flow rate of the pneumatic conveying system

In pneumatic conveying systems, a stable and controlled solid mass flow rate is essential for industrial plant design. This study examined the influence of resistance component sizes and shapes on dense-phase pneumatic conveying, which demonstrated that structural variations significantly alter system pressure distribution and the solid mass flow rate. Notably, the analysis showed that the ratio of the orifice plate pressure drop to the total conveying pressure drop is related to the resistance component structure. Consequently, the solid mass flow rate can be controlled by adjusting the structure of the resistance components. Moreover, the structure characteristics of the resistance components are engineered to enhance gas velocity within the pipeline, thereby effectively mitigating the risk of clogging. The relationship between the ratio of the orifice plate pressure drop to the total conveying pressure drop and the solid mass flow rate was established by introducing the concept of effective pressure drop. Based on this relationship and Beverloo law, a model for solid mass flow rate was developed, which can predict the solid mass flow rate well by providing errors mostly within ± 10 %. This study offers a valuable reference for the optimizing of resistance components design in pneumatic conveying systems.

The erosion rate prediction for the elbow in shale gas gathering and transportation system: RSM and GA-BP-ANN modeling

Elbow erosion caused by sand mixed in shale gas is a significant issue faced by shale gas gathering and transportation systems, posing a serious threat to the safe and stable production of shale gas. In this paper, the factors affecting elbow erosion in the shale gas gathering and transportation system are identified. The computational fluid dynamics (CFD) two-way coupling Euler-Lagrange method is used to investigate the single-action of various parameters on particle trajectory, erosion morphology, and maximum erosion rate, including pipe inner diameter, pipe R/D ratio, pipe bending angle, pipe bending orientation, solid particle velocity, solid particle size, and solid particle mass flow rate. Subsequently, the response surface methodology (RSM) is employed to quantitatively explore the synergistic interactions between these factors that affect the maximum erosion rate of the elbow, and a surrogate model for simple and rapid evaluation of the maximum erosion rate for elbows at the engineering level is proposed. Finally, the backpropagation artificial neural network (BP-ANN) optimized by genetic algorithm (GA) is used to train the samples obtained by Latin hypercube sampling (LHS) in the multi-factor range. By comparison, the RSM surrogate model and the GA-BP-ANN model reveal a favorable level of agreement with the experimental data, while considering various influential factors. It is important to note that each method possesses distinct advantages, limitations, and specific application environments. This research can provide quantitative references for preventing and controlling erosion within the shale gas gathering and transportation system.

Flow irreversibility versus wear of elbow-reducer connection with gas-solid two-phase flow: A numerical study via CFD-DEM coupling method

In industry sectors, such as power, petroleum, and natural gas production, many fluids contain solid particles in gas/liquid-solid two-phase flows. Thus, resistance and wall erosion, which mainly occur at pipe resistance components, such as elbows and reducers, should be considered in the design of conveying pipelines. To examine the interaction of two resistance components, the flow irreversibility versus wear of an elbow-reducer connection with a gas–solid two-phase flow were studied via the CFD–DEM coupling method. The studied connection structures include a reducer at the elbow downstream with distances of 0, 1, and 3 pipe diameters, and a reducer at the elbow upstream with distances of 0, 1, and 3 pipe diameters. Results show that turbulence and wall entropy generation are main reasons for the total entropy generation and flow irreversibility, which are mainly distributed in the interior wall of the elbow and the pipe. The reducer located downstream of the elbow has a good inhibition effect on the fluid with a separation phenomenon. The total entropy generation and maximum erosion rate for the elbow-reducer connections are lower than that for the reducer-elbow connections. Moreover, influences of solid particle mass flow rate and particle size on partial entropy generations, including mean, turbulent, and wall entropy generations, and wall erosion were comparatively analyzed. The simulation results can provide a reference for the design of pipelines to reduce energy consumption and pipeline wear.

Computational model of a Calcium-looping fluidized bed calcination reactor with imposed concentrated solar irradiance

The Calcium-looping process is a promising option for thermochemical energy storage in concentrating solar power plants. A crucial element of this process is the solar calcination reactor, where the endothermic reaction of CaCO3 calcination occurs with formation of CaO and CO2. The solar energy that is chemically stored in the reaction products can be retrieved by the exothermic reaction of CaO carbonation when needed. In this article, a new computational model is developed for the solar calcination reactor in this Calcium-looping process. The calcination reaction takes place in the riser of a continuous circulating fluidized bed that corresponds to an absorber tube exposed to concentrated solar radiation, which allows the reaction chamber to be indirectly heated. A core-annulus heat transfer model and a modified version of the Kunii–Levenspiel fluid dynamics model are used. In contrast to previous models found in the literature, the change in the mass flow rate of the species and in the density of the phases due to the reaction is considered. Simulation studies are performed with a fixed and imposed concentrated solar irradiance on the reactor wall, which varies in both the axial and angular directions. Wall conduction in the angular direction is also considered. The results show that nearly complete calcination can be achieved with a reactor of 4 m of height. A sensitivity analysis with respect to the model parameters and inlet conditions shows that the calcination conversion is mostly affected by the solids mass flow rate and the bed temperature at the inlet.

A novel method for evaluation of spatial characteristics in a gas solid separation fluidized bed

This study investigates the complex spatial characteristics of a gas-solid dense-phase fluidized bed for a separation system. A custom-designed perspex bed, equipped with multi small holes and different distributors, was used to explore gas-solid suspension characteristics. The results show that there is a certain spatial heterogeneity in the density of the gas-solid separation fluidized bed. The spatial heterogeneity of gas-solid fluidized beds is characterized by global and local dependence. An empirical model that predicts the relative solid mass flow rate was proposed. GeoDetector technology (including a factor detector, interaction detector, risk detector, and ecological detector) was first introduced to quantify the spatial characteristics of a gas-solid fluidized bed. The influence of each factor on the spatial heterogeneity of particle solid mass flow rate follows the order: axial position > gas velocity > radial position > air distributor. The interactive relationship between variables on the spatial characteristics of gas-solid separation fluidization shows a nonlinear enhancement.

Estimating the chemical composition of municipal solid waste using the inverse method

This research aims to perform and implement an inverse solution method in waste-to-energy power plants for carrying out solid waste analysis without sampling. For this purpose, a simple simulated experiment is defined to evaluate the stability and accuracy of the method, which is investigated by adding random errors to the results of the direct problem conducted by the Monte Carlo method. The inverse problem solution procedure is solved by obtaining data categories for measuring parameters. In addition, the coefficient matrix is created and the linearization method is employed. By assuming a 0.5 percent nitrogen content in municipal solid waste, the number of unknown parameters is reduced, and the problem is solvable. The regularization method is applied to obtain the stability of the answer. The procedure is done for a municipal solid waste analysis with different regularization parameters. The mean value error and variance of the obtained solution from each analysis are evaluated and the acceptable range for regularization parameters is determined. Also, the identified matrix parameters between 1 and 100 are examined in the constant regularization parameter, and the acceptable parameters are determined. The error in validation by simulated experiment for carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste is 1.47, 3.81, 0.91, 0.22, 7.32, and 1.57 percent, respectively. In the next step, the developed procedure is applied to the Aradkooh waste-to-energy power plant in Tehran, Iran. The operating data are gathered from the power plant, and the municipal solid waste composition is estimated. Results indicate the feasibility of the proposed method, and the municipal solid waste composition and mass flow rate can be predicted indirectly by the flue gas analysis and some other measurements without needing to sample the municipal solid waste. According to the results, the carbon, oxygen, hydrogen, sulfur, moisture, and ash content of municipal solid waste in the Aradkooh power plant is 21.13, 41.96, 5.70, 0.01, 25.06, and 5.63 percent, respectively. Further, the mass flow rate of municipal solid waste and air are 0.53 and 2.5 kg per second. Finally, the sensitivity of the estimated municipal solid waste composition to errors is evaluated by error analysis.

Numerical simulation on gas-solid flow characteristics in a high-density countercurrent fluidized bed particle solar receiver

The application of solid particles in the next-generation concentrated solar power station could reduce the Levelized Cost of Energy further. As a key energy conversion device, existing particle solar receivers still have different shortcomings. The high-density countercurrent fluidized bed (CCFB) particle solar receiver may provide a promising technical solution because of its feasibility and its thermal transportation characteristics. However, the hydrodynamics of the CCFB particle solar receiver is very difficult to investigate through experimental methods. In this study, a computational particles fluid dynamics model is established to investigate the gas–solid flow characteristics in the CCFB particle solar receiver, which is validated by the experimental solid mass flow rate obtained from a cold mold CCFB particle solar receiver. The solid holdup distribution, axial particle velocity and characteristics of bubbles are obtained accordingly. The results show that the present model can capture the entire process from bubble formation to bursting. Meanwhile, the solid holdup distribution and axial particle distribution are related to the upward bubbles, both of which present an asymmetrical distribution for the bubble existing region. However, the holdup distributions present a symmetrical distribution similar to the packed bed for the non-bubble region. The results could make up for the deficiency of the experiments effectively and reveal the high-density gas–solid countercurrent flow mechanism comprehensively.

Flow characteristics and flow rate prediction of pulverized coal through a regulation valve

• The optimum valve sweeping gas fraction was determined. • Control characteristics of the regulation valve were studied. • Limit operating conditions of the regulation valve were defined. • A semi-empirical model was established for pulverized coal flow rate prediction. In this paper, experiments of dense-phase pneumatic conveying of pulverized coal were carried out in an industrial-scale system to study the control characteristics of the regulation valve and to predict the solid mass flow rate. Firstly, effects of valve sweeping gas on conveying stability and solid mass flow rate were investigated and the optimum valve sweeping gas was determined. Second, effects of valve opening on pressure distribution and solid mass flow rate were investigated by conducting experiments at different conveying pressure drops and different valve openings. A good linear relationship between the valve pressure drop ratio and the valve opening was found, and as the valve opening increased from 13 % to 70 % the solid mass flow rate increased gradually. Limit operating conditions of the regulation valve including flow blockage and control failure were consequently determined and analyzed. Finally, a robust model was established to predict the solid mass flow rate by introducing the valve sensitivity coefficient into the traditional pressure drop ratio model. The model can predict the solid mass flow rate well by providing errors mostly within ± 10 %. This study will provide certain reference for solid mass flow rate regulation in the dry coal gasification process.

Numerical investigation of lateral aeration effect on gas-solid flow and particle mixing in spouted bed with different base angles

A comprehensive study using computational fluid dynamics integrated with discrete element method was carried out on spouted beds with different geometries to investigate effects of employing secondary jet inlets with lateral injection to eliminate particle accumulation. Spouted beds with various base angles of 180, 120, 90 and 60 degrees were modelled and studied. In order to quantify the influences of utilizing secondary jet inlets, the hydrodynamics including particle flux, bed circulation time, air volume fraction and active particles in the cyclic flow were analyzed. Plus, qualitative and quantitative analysis on mixing characteristics of the beds was executed. Results indicated that addition of jets decreases the air volume fraction in the spout channel by a significant margin and therefore, more solids mass flow rate in the spout. This ensues a reduction in the bed circulation time and a promotion in the particle flux. Mixing characteristics were also developed in all geometries and the maximum value of mixing was intensified in higher velocity of the lateral aeration.

Hydrodynamic characteristics in the full-loop circulating fluidized bed under load regulation. Part 2: Simulation

The key to improving the load regulation ability of circulating fluidized bed (CFB) units lies in the profound understanding of the hydrodynamic characteristics in the circulation loop. However, most experimental investigations are confined to the pressure and solid volume fraction measurements. To gain insight in the mass balance of the circulation loop under load regulation, the computational particle fluid dynamics (CPFD) method was applied to simulate the dynamic behavior of a CFB test rig at different ‘load’ change rates. After verifying the numerical model with the related experimental data, the transient profile of the solid inventory and solid mass flow rate was investigated. The results showed that the change in the solid inventory mainly happened in the riser and standpipe. In addition, the solid mass flow rate at different axial elevations showed distinctchangepatterns after an initial period of simultaneously increasing or decreasing.

Thermal Management of Solar Photovoltaic Cell by Using Single Walled Carbon Nanotube (SWCNT)/Water: Numerical Simulation and Sensitivity Analysis

Despite the attractiveness of Photovoltaic (PV) cells for electrification and supplying power in term of environmental criteria and fuel saving, their efficiency is relatively low and is further decreased by temperature increment, as a consequence of absorption of solar radiation. In order to prevent efficiency degradation of solar cells due to temperature increment, thermal management is suggested. Active cooling of solar cells with use of liquid flow is one of the most conventional techniques used in recent years. By use of nanofluids with improved thermophysical properties, the efficiency of this cooling approach is improvable. In this article, Single Walled Carbon Nano Tube (SWCNT)/water nanofluid is used for cooling of a PV cell by considering variations in different factors such as volume fraction of solid phase, solar radiation, ambient temperature and mass flow rate. According to the findings, use of the nanofluid can lead to improvement in performance enhancement; however, this is not significant compared with water. In cases using water and the nanofluid at 0.5% and 1% concentrations, the maximum improvement in the efficiency of the cell compared with the cell without cooing were 49.2%, 49.3 and 49.4%, respectively. In addition, sensitivity analysis was performed on the performance enhancement of the cell and it was noticed that solar radiation has the highest impact on the performance enhancement by using the applied cooling technique, followed by ambient temperature, mass flow rate of the coolants and concentration of the nanofluid, respectively. Moreover, exergy analysis is implemented on the system and it is noticed that lower ambient temperature and solar radiation are preferred in term of exergy efficiency.

A review of solid particles mass flow rate measuring methods: screening analytic hierarchy process for methods prioritization

A review of solid particles mass flow rate measuring methods: screening analytic hierarchy process for methods prioritization

Study on solid-liquid transition behaviors of cohesive powders and predict the critical arch-breaking gas flow rate

Cohesive powders cannot flow freely in the silo and even behave like solid, which brings a great challenge to the powder handling process. Aeration is an effective method used to break the arch structure formed above the silo outlet and to promote the powder flow. However, it is difficult to determine the solid-liquid transition behaviors and to predict the critical arch-breaking gas flow rate in the aerated discharge systems. In this paper, cohesive powders including alumina (Al2O3), pulverized coal (COAL) and calcium carbonate (CaCO3) were used as experimental materials. Powder flow properties were characterized by conducting shear test, permeability test, and aerated discharge experiment. Unconfined yield strength of powders under zero pre-consolidated stress was obtained based on using a linear extrapolation procedure of shear parameters. Aerated discharge characteristics of cohesive powders were determined and, the critical condition corresponding to the transition from solid-like to liquid-state and the stable condition distinguishing the funnel flow pattern and mass flow pattern were defined, respectively. The Brown and Richards model, and the flow/no-flow criterion of Jenike were modified to describe the powder flow state and to predict the solid mass flow rate under the action of aeration by introducing the positive gas pressure gradient. A logical algorithm was proposed to predict the critical arch-breaking gas flow rate by assuming the same gas distribution coefficient under different aeration conditions. As a precondition, the critical solid mass flow rate was calculated by an iterative algorithm giving the same order of magnitude of that from the experiment, which was further related to the stable solid mass flow rate and the powder permeability index. This simplification provided us with satisfactory results for all the powders producing errors generally less than 30%, a more easy-to-operate method to determine the critical arch-breaking gas flow rate.

Application of oscillation flow to horizontal gas–particle two-phase flow

The purpose of this study is to apply the oscillation flow induced by a combination of a circular cylinder and non-uniform soft fins to gas–solid two-phase flows to reduce the transport gas velocity and power consumption in a horizontal pipe. In order to evaluate the oscillation flow, several different sizes of square and circular cylinders are used to combine four pieces of soft fins with non-uniform lengths, which are mounted on the horizontal central plane in front of the particle supply. The test pipe comprises a horizontal acrylic pipe with a length of 5 m and an inside diameter of 80 mm. Spherical polyethylene particles with an average diameter of 2.3 mm and density of 978 kg/m3 were used as the test particles. The average gas velocity was 9–16 m/s, and the solid mass flow rate was 0.11–0.51 kg/s. It is found that the combination of a circular cylinder or square cylinder of L = 10 mm with non-uniform soft fins causes the lowest pressure drop and highest velocity fluctuation in the oscillation flow based on single-phase flow (gas only) measurement. Compared to conventional gas–solid two-phase flows, the reduction in the minimum transport velocity, pressure drop, power consumption, and additional pressure drop were obtained using a combination of a circular cylinder with non-uniform soft fins. This combination provides the highest reduction rates in the minimum conveying velocity and an additional pressure drop by approximately 10.0% and 34.1%, respectively. Based on particle image velocimetry measurements, the time-mean particle velocity and particle fluctuating velocity of a circular cylinder with non-uniform soft fins were higher than those of conventional flows near the bottom part of the pipe, thus easily accelerating and suspending particles near the pipe bottom, even at lower gas velocities.

Numerical Simulation of Erosion Characteristics and Residual Life Prediction of Defective Pipelines Based on Extreme Learning Machine

Aiming to solve the problem that the residual life of defective elbows is difficult to predict and the prediction accuracy of a traditional extreme learning machine (ELM) is unsatisfactory, a genetic algorithm optimization neural network extreme learning machine method (GA-ELM) that can effectively predict erosion rate and residual life is proposed. In this method, the input weight and hidden layer node threshold of the hidden layer node is mapped to GA, and the input weight and threshold of the ELM network error is selected by GA, which improves the generalization performance of the ELM. Firstly, the effects of solid particle velocity, particle size, and mass flow rate on the erosion of elbow are studied, and the erosion rates under the conditions of point erosion defect, groove defect, and double groove erosion defect are calculated. On this basis, the optimized GA-ELM network model is used to predict the residual life of the pipelines and then compared with the traditional ELM network model. The results show that the maximum erosion rate of defect free elbow is linearly correlated with solid particle velocity, particle size, and mass flow rate; The maximum erosion rate of defective bend is higher than that of nondefective bends, and the maximum erosion rate of defective bend is linearly related to mass flow rate, but nonlinear to solid particle flow rate and particle size; the GA-ELM model can effectively predict the erosion residual life of a defective elbow. The prediction accuracy and generalization ability of the GA-ELM model are better than those of the traditional ELM model.

Static and dynamic characteristics of rotary kiln reactor during processing of biomass and municipal solid waste

The behavior of five types of material (wood pellets, agro pellets, over-sieve fraction (OSF), willow chips and alder chips) in rotary kiln reactor was tested. Basing on the obtained experimental results, the empirical mathematical models were validated to predict mean residence time (MRT). The best fitted correlation generated mean absolute error at level of MAE = 9.4%. Regarding dynamic characteristics, the simplified approach of “first-order + dead time” was successfully applied to model the dynamic characteristic of rotary kiln reactor in terms of solid phase mass flow rate. The characteristic parameters of dynamic model, i.e. τ, min and Θd, min, were determined for every case. Time constant, τ, was in the range of 5.8–34.3 min, whereas dead time, Θd, was in the range of 0.001–73.2 min. Finally, a simplified model to estimate the time (i.e. 3 × τ + Θd) necessary to obtain steady-state conditions in terms of mass flow rate in rotary kiln reactors was proposed.

Statistical analysis of fuidized dense phase conveying of fine particles

Pressure drop in fluidized dense phase pneumatic conveying of fine particles depends upon parameters such as air or solid mass flow rate, pipe diameter or length. For pipeline layouts with definite dimensions, correlations presented by several researchers can be used to predict pressure drop with greater accuracy. However, while estimating pressure drop for an alternative pipeline configuration, majority of these correlations exhibit substantial errors. Straight-line pressure drop was modelled using the response surface methodology in Minitab software under the design of experiment method. On the response straight line pressure drop, a multiple regression model was developed with input parameters such as air mass flow rate, solids mass flow rate, pipeline length, pipeline diameter, particle diameter and solid loading ratio. The experimental data available as input parameters is used to develop a pressure drop correlation and subsequently applied to predict pressure drop for different pipeline configurations ±15% error margin.

Efficiency analysis of citrus waste biomass valorization using rotary dryer

Citrus residue is a large-scale agro-industrial biowaste that can become a source of renewable energy through drying. Drying demands high power consumption due to the low energy efficiency of this process in the industries. In this work, the energy performance of the drying process in a semi-industrial rotary drum of 2.7 m length and 0.45 diameter was analyzed. The main objective was to find the operational condition for the lowest energy consumption and also the highest energy, drying and exergetic efficiencies. The experiments were performed under different solid mass flow rates (0.2 and 0.4 kg/min) inlet air velocities (1 and 2 m/s) and temperatures (135, 145, and 155 °C). The average energy efficiency was 13.1% with 25.1% of drying efficiency, 37291.3 kJ/kg of specific energy consumption, and 37.3% of exergy efficiency. The results showed that the drying technique can be an interesting alternative to add value to the citrus residue.

Determining the Solids Mass Flow Rate in a Gas–Solids Riser Using an Integral Momentum Balance

Determining the Solids Mass Flow Rate in a Gas–Solids Riser Using an Integral Momentum Balance

Particle flow regime in a swirling pneumatic conveying system

Particle fluidization is crucial for pneumatic conveying, combustion, and material drying. In this study, a swirling generator was designed to investigate the effect of the swirling flow on the flow regimes of pebble particles in a vertical pipe, and four different sizes of pebble particles were experimentally evaluated. Experiments were performed to investigate the effect of the axial flow and swirling flow on the flow regime, pressure drop, and suspension height of particles in a vertical pipe. The results indicated that the swirling flow has a significant effect on the particle flow regimes in a vertical pipe when the solid mass flow rate and inlet airflow velocity are constant. The swirling flow reduces the pressure drop and increases the particle fluidization in a vertical pipe, and it lifts the particles only when the inlet airflow velocity is higher than the particle velocity for the choking condition.