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![Figure 1-2: The first published pneumatic conveying system [4].](profile/Chandana-Ratnayake/publication/37686963/figure/fig1/AS:669386482401285@1536605582669/2-The-first-published-pneumatic-conveying-system-4_Q320.jpg)
![Figure 1-3: A proposed setup of a pneumatic conveying capsule line [10].](profile/Chandana-Ratnayake/publication/37686963/figure/fig2/AS:669386482393098@1536605582829/3-A-proposed-setup-of-a-pneumatic-conveying-capsule-line-10_Q320.jpg)
Avhandling (dr.ing.) - Høgskolen i Telemark / Norges teknisk-naturvitenskapelige universitet The main objective of this investigation was to formulate a comprehensive scaling up technique for designing of pneumatic conveying systems by addressing the whole pipeline together with all accessories. Five different bulk materials together with five qual...
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... In order to get the best performance out of a pneumatic dryer, some operational limits need to be respectedfor instance, the exhaust air temperature must not be so low as to promote condensation of the moisture again owing to cooling in the cyclone. Furthermore, the pressure drop across the pipeline and the condition of the biomass (wet at first and dried subsequently) have to be determined precisely [34]. A challenge that a designer invariably encounters is the non-uniformity of the physical properties (size, shape, moisture content, etc.) of sawdust or biomass particles in general, which makes predictions about the transport through the dryer difficult, if not impossible [35]. ...
The supply-chain logistics – storage and transportation over long distances – and downstream processes in biofuel production are adversely impacted by the moisture content in the biomass feedstock. Most woody, herbaceous, low-cost biomass resources such as municipal organic solid wastes and forest residues have moisture content over 30% (of the wet-biomass mass). This makes them less amenable to thermochemical biomass-to-biofuel conversion technologies like pyrolysis and gasification. If pyrolyzed or gasified, the resulting biofuels have a higher moisture content, which truncates their calorific values. During storage, there is a loss of dry matter owing to a tendency to compost aerobically/anaerobically, which is detrimental to the quality of the biomass as a potential source of biofuel. Beyond that, fire hazards due to the spontaneous combustion of wet biomass are not uncommon, necessitating storage in a dry condition. However, drying high-moisture biomass is energy-intensive. The quality of the product and the efficiency of drying are affected by particle sizes and drying technologies adopted. Within this chapter, the authors focus on managing and controlling the moisture content of the biomass utilized in the biofuels sector by resorting to drying and torrefaction technologies. The chapter dwells on drying principles, models and media in drying systems, types of drying systems, mechanical dewatering and torrefaction, the impact of drying, dewatering, and torrefaction on the physical and chemical properties of the end-product, and techno-economic analysis of torrefaction.
... τ ij,g is the shear stress tensor of the gas phase, which is related to the gradient of velocity components. The shear stress tensor is given by: (4) Momentum conservation equation for the solid phase: ...
The stable transportation of pulverized coal in the vertical pipe is significant for the operation of the gasifier. There are few studies on the flow characteristics and flow pattern transition of particles in vertical pipes with small diameters. This paper has modeled and analyzed the flow characteristic of powder in dense-phase pneumatic conveying through 25 mm vertical pipe using CFD. Firstly, the grid independence is verified to determine the optimal mesh size. Then, the influences of different solid loading ratios (SLRs) and conveying velocities on particle flow characteristics, flow stability, and flow pattern transition are investigated. The results show that the flow pattern in the vertical pipe changes from annular flow to uniform flow at high SLR and low conveying velocity. Moreover, the evolution regulation of resistance characteristics under different conveying velocities is further revealed. Considering the conveying stability and economic benefit, the most suitable conveying velocity is 6 m/s.
... Based on review of study from [40], the same author proposed an expression for the calculation of the pressure drop in horizontal pneumatic transport systems developed using Blasius friction factor for gas flow. Most of the correlations analyzed in [50] are created by modifying the correlations considered in [34], and a large number of complex parameters led to the same general conclusion, that they are difficult to apply. The computational approach to pneumatic conveying provided constant progress in this field, but the basic physical parameters of the process must be better understood in order for this progress to make sense [6]. ...
... The computational approach to pneumatic conveying provided constant progress in this field, but the basic physical parameters of the process must be better understood in order for this progress to make sense [6]. Two models are used to calculate the pressure drop for five different materials and for five pipeline configurations [50]. One model is used for straight horizontal and vertical sections, and the other for elbows, valves and other pipeline sections. ...
This paper will validate two basic concepts of numerical models for
prediction of pressure change along the transport pipeline in the case of
long distance and high capacity lignite ash pneumatic conveying. Application
of various friction factor correlations and variation of given parameter,
led to the total of fourteen different numerical models and program codes in
FORTRAN. The input data for numerical models are based on comprehensive
experimental research of high capacity and long distance Kolubara lignite
fly ash pneumatic conveying system within 620 MWe thermal power plant unit
under operating conditions. Numerical simulation results are validated
against experimental data and subjected to statistical analysis methods.
The functional dependence obtained by the least squares method was evaluated
using mean squared deviation and correlation ratio. The predicted pressure
changes show the best agreement, with the measured decrease of pressure
amplitudes along the transport pipelines, for the model based on the
momentum balance of air-ash mixture flow and friction factor cor-relation
given by Dogin and Lebedev for the parameter A = 1.4∙10-6. This model
achieved the best correlation ratio of 93.99% for Pipeline 1 and 91.33% for
Pipeline 2, as well as the best mean squared deviation of 9.58% for Pipeline
1 and 13.66% for Pipeline 2. Also, the fanning friction factor values are
fully consistent with previously examined cases available in the
literature. Numerical simulation model can be used for prediction of the
ash pneumatic conveying capacity and pressure drop for the specified
transport pipeline.
... Terdapat 2 jenis Pneumatic conveying system berdasarkan kepadatan material yang diangkut atau dipindahkan yaitu Dilute phase conveying system untuk material cair dan Dense phase conveying system untuk material padat (Chandana Ratnayake, 2005); (Cai, L.,2014);. Perbedaan material cair dan padat bukan berdasarkan jenis material yang diangkut, tetapi dilihat dari perbandingan komposisi material dan udara pada pipa penghantar. ...
Portable vacuum grain conveyor (PVGC) work as transporting grain materials such as grain, wheat, sorghum, corn and its kind using air media. The advantages of this machine are that it can move material quickly, the material does not fall in the transportation process, it can move from the bottom to the top or vice versa, it does not require a feed hopper, and the machine can move places. How the PVGC machine works by utilizing the suction and thrust of a vacuum blower. The seed material is sucked in by the input hose and then into the cyclone to separate the air and seed material. Air from the cyclone enters the vacuum blower through the input hole and is blown into the output line to push the material falling from the cyclone through the rotary airlock. Seed material out through the output hose is directed to the desired place. Performance testing of the PVGC engine includes noise, the air suction speed of the input hose and the thrust speed of the output hose, the engine capacity, and thermal testing. The highest noise test results in the electric vacuum blower motor was 95.5 dBA ±1, the air suction speed at the input hose was 38 m/s ±3, the air thrust speed at the output hose was 44 m/s ±2, the capacity of the PVGC machine could transport IR64 of grain type with weighing 88 kg/minute. The hottest component was in the vacuum blower with a temperature of 52.50C.
... The research community has made considerable efforts to document pneumatic conveying through experimental measurements and imaging techniques [5][6][7]. However, valuable information about seed velocity, seed distribution, and other qualities of interest are more readily available through numerical simulation approaches, such as computational fluid dynamics (CFD) [8]. Continuum models based on CFD are selected depending on the desired level of detail and available computation power. ...
... Processes 2020, 8 phase. Details regarding input parameters and the coupling of the solid phase (seed and walls) and fluid phase (air) are described in the following sections. ...
... This type of detailed data recording is one of the advantages of computer simulation techniques. Referring to the work of Kalman et al. [39] Processes 2020, 8,1597 8 of 16 provides a means of comparison for the particle flow characteristics between the proposed simulation and current empirical models. Kalman et al. [39] described a three-zone model that correlates the Reynolds number and Archimedes number to the type of granular material flow regime. ...
Air seeding equipment consists of various machine components that rely on pneumatic conveying of seeds (granular material) for its operation. However, studying air seeder dynamic features in detail is difficult through experimental measurements. A simulation was performed to study seed motion in a horizontal tube section of an air seeder distributor system. The simulation incorporated two-way coupling between discrete element modeling (DEM) and computational fluid dynamics (CFD). Simulated particles were assigned material properties corresponding to field peas. Air velocity was assigned values of 10, 15, 20, and 25 m/s. The solid loading ratio (SLR) in this study included values between 0.5 and 3 to describe typical seed metering rates used in air seeding. The different pneumatic conveying conditions were studied to determine their overall effect on the average seed velocity and seed contact force. The simulation was validated through the comparison of average seed velocity data from the literature and current pneumatic conveying theory. The effect of SLR on the average seed velocity was found to be not significant for the simulated SLR values. The CFD-DEM simulation was able to capture seed collisions between seeds and the surrounding boundaries. The seed contact force increased with the air velocity, and the number of seed collisions increased with the SLR.
... With the increase of computer power and advancement of commercial modeling software, computational fluid dynamics (CFD) technique is gradually becoming an attractive tool to study turbulent gas-particle flow problems. CFD has the capacity of providing the "microscopic" or "local" information, for instance, the maximum and minimum gas and particle velocity, local particle concentration and individual particle trajectory [13]. Another feature of CFD approach is the graphical presentation of the flow geometry, velocity, pressure, erosion pattern and particle concentration fields. ...
... The m s increases with increasing V s for blockage boundary at fixed P t and d s value. Furthermore, as shown in Fig. 7, V s , in turn, can be divided into three stages according to the amplification trend of the curves: slow growth stage, rapid growth stage and medium growth stage, and at each stage, the greater V s corresponds to the greater amplification of m s (Ratnayake 2005). Due to the fact that under the disturbance of porous medium, the flow state, corresponding to the rapid growth stage in the medium air velocity zone, may be undergoing a transition from laminar flow to turbulent flow, leading to the significant increase in particle carrying capacity for air. ...
Borehole sealing is the significant measure for improving coalbed methane (CBM) drainage effect. Based on the technology of using particles to seal the air-leakage fractures around drainage borehole, the deposition and blockage characteristics of particles in the coal (rock) broken zone were experimentally investigated under the gas–solid two phase flow conditions, and the porosity formed by the filled glass beads with different particle sizes (3 mm, 4 mm, 5 mm and 6 mm) in the porous medium zone was used to simulate the broken fractures around boreholes in this paper. The results showed that the particle mass flow rate increased with the inlet air velocity for blockage boundary, and the change trend could be divided into three stages: slow growth stage, rapid growth stage and medium growth stage with the increase of inlet air velocity. Furthermore, the relationship between inlet air velocity and particle loading ratio for blockage boundary in the porous medium displayed a scoop-shaped curve: with increasing inlet air velocity, the particle loading ratio decreased at first and then increased rapidly, subsequently increased slowly, which is different from the existing research. In addition, the effects of conveying pressure and particle size of porous medium on the blockage boundary were also studied. The research work is beneficial to engineering applications of the sealing technology.
... The granular solids transportation by the pneumatic system was introduced in 1920 [11]. This system was introduced in cement and coal industry in the1930s [13]. Since 1930-1960s remarkable efforts were done in the promotion and improvement of pneumatic conveying efficiency in Japan, Germany, and USA [14]. ...
This paper covers the application of the cross-correlation method for measuring the velocity of solid particles. Capacitive electrodes are used as primary sensors to measure the time required by the solid particles to cover a known distance between the electrodes. The capacitive variations of both the electrode sensors are stored in computer synchronously for offline estimation of the velocity of the solid particles. Single glass marble is used as a solid particle to conduct the performance in the lab for its good signal to noise ratio (SNR) and vivid graphs. Matlab R2018a is used as a programming tool to perform the cross-correlation algorithm. The distance between the sensors is adjusted optimally. The results were realistic to ensure the correctness of the system.
... However, a consider number of researchers (Jones & Williams, 2003;Mallick, 2009;Pan & Wypych, 1992;Segmaier, 1978;Weber, 1981) have also applied this expression to predict the pressure drop of densephase pneumatic conveying systems. Ratnayake (2005) has implied that Eq. (1) can estimate the pressure drop in pneumatic conveyors with good accuracy especially for short pipeline lengths. ...
This research was devoted to establishing a dimensionless model for estimating mixture friction factor based on the Buckingham Theorem. An experimental test-rig with conveying pipeline of 40 mm I.D was designed, assembled and used to collect the data needed to model the mixture friction factor. Experiments were carried out in four levels of slot depths (0, 0.35, 0.55 and 0.9 mm), three levels of air pressure (100, 200 and 300 kPa) and three pipeline lengths (3, 6 and 9 m). Conveying tests with three particulate materials of mung bean, corn, and polyethylene pellets were completed using three replications. Static air pressure across the conveyor, mass flow rate of discharge solids and inlet air mass flow rate were measured during the tests.
The model developed can estimate the mixture friction factor within the range of variables studied. The comparison between predicted and measured mixture friction factor showed no significant difference. According to values of , RMSE, reduced chi- square and MRD parameters, mixture friction factor modelling of the pneumatic conveyor had good accuracy.
Other results showed that the mixture friction factor was 65% less than that of pipelines with inner trapezoidal slots studied earlier, therefore lower upstream pressure was required for dense phase pneumatic conveying of particulate materials in the new conveyor.
The developed model showed acceptable error in predicting pressure drop from the experimental data.
... Inaccuracy in the prediction of acceleration pressure drop signifies its basis of its contribution in total pipeline pressure drop [20,21]. Two modest cases of pipeline have been compared to observe the contribution of acceleration pressure drop in total pipeline pressure drop. ...
