Development of a mechatronic sorting system for removing contaminants from wool

Automated visual inspection (AVI) systems have been extended to many fields, such as agriculture and the food, plastic and textile industries. Generally, most visual systems only inspect product defects, and then analyze and grade them due to the lack of any sorting function. This main reason rests with the difficulty of using the image data in real time. However, it is increasingly important to either sort good products from bad or grade products into separate groups usingAVI systems. This article describes the development of a mechatronic sorting system and its integration with a vision system for automatically removing contaminants from wool in real time. The integration is implemented by a personal computer, which continuously processes live images under the Windows 2000 operating system. The developed real-time sorting approach is also applicable to many other AVI systems

Capacitance Based Virtual Instrument Mass Flow Measuring System

The research program conducted at the MMU into the design and development of a Virtual Instrument ECT Imaging System is a continuation from preceding investigations conducted by the MMU into tomographic imaging. The rationale behind the MMU tomographic imaging system is a response to the need for a robust and flexible proprietary tomographic imaging system appropriate for large industrial systems. The MMU Virtual Instrument ECT Imaging System consists of capacitance sensor(s), capacitance measuring hardware and the National Instruments (NI) PXI modular data acquisition system on which runs NI’s LabVIEW graphical programming environment. The MMU tomographic imaging system is capable of high tomographic speed imaging from single and dual plane sensing arrays. The purpose of this MSc project is, by utilising the MMU Virtual Instrument ECT Imaging System, to design and develop a virtual instrument measurement system for the purpose of measuring mass flow and flow velocity. Evaluation of the virtual instrument measurement system is achieved by measuring the flow of polypropylene pellets through a vertical, hopper fed, gravity-conveyed flow system fitted with two axially spaced 8 electrode transducers. Pellet mass flow is determined from the averaged volumetric concentration of pellet materials present in the capacitance sensor placed in the upstream path of the pellet flow. Pellet velocity is determined by the cross correlation of the two random noise patterns generated by the pellets as it passes through the two capacitance sensors placed in the upstream and downstream path of the pellet flow. Results are presented which show the relationship between the actual measured mass flow and the mean volumetric concentration taken from the upstream sensor compared to the number of independent normalised capacitance measurements taken from the upstream sensor. Also presented are results which relate the accuracy of the measured flow velocity to the number of independent normalised capacitance measurements taken from the upstream and downstream sensors. The results presented show that as the number of independent normalised capacitance measurements taken from both the capacitance sensors are reduced, the electrostatic field distribution within the sensors becomes more inhomogeneous which has an adverse affect v on the measurement accuracy of mass flow. Conversely, by increasing the number of independent normalised capacitance measurements taken from both the capacitance sensors has a detrimental affect on the accuracy of flow velocity measurement. The results shown prove that the MMU Virtual Instrument ECT Imaging System is capable of individual accurate measurement of either mass flow or flow velocity. But, due to the limitations encountered with the current available hardware, simultaneous and accurate measurement of mass flow and flow velocity is impractical

METODY PARAMETRYCZNE W ROZWIĄZYWANIU PROBLEMU ODWROTNEGO DLA MONITOROWANIA PRZEPŁYWÓW MATERIAŁÓW SYPKICH

The article presents the parametrisation-based methods of monitoring of the process of gravitational silo discharging with aid of capacitance tomography techniques. Proposed methods cover probabilistic Bayes’ modelling, including spatial and temporal analysis and Markov chain Monte Carlo methods as well as process parametrisation with artificial neural networks. In contrast to classical image reconstruction-based methods, parametric modelling allows to omit this stage as well as abandon the associated reconstruction errors. Parametric modelling enables the direct analysis of significant parameters of investigated process that in turn results in easier incorporation into the control feedback loop. Presented examples are given for the gravitational flow of bulk solids in silos.Niniejszy artykuł przedstawia parametryczne metody rozwiązywania problemu odwrotnego w tomografii pojemnościowej na przykładzie monitorowania procesu przepływu materiałów sypkich przy użyciu tomografii pojemnościowej. Wybrane metody obejmują modelowanie probabilistyczne Bayesa, w tym przestrzenne i czasowe oraz metody Monte Carlo łańcuchów Markowa, a także parametryzację procesu z użyciem sztucznych sieci neuronowych. W odróżnieniu od klasycznych metod opartych na algorytmach rekonstrukcji obrazu parametryzacja pozwala na pominięcie tego etapu, a co za tym idzie brak dodatkowych błędów związanych z rekonstrukcją. Parametryzacja pozwala na bezpośrednią analizę istotnych parametrów badanego procesu, przez co łatwiejsze jest użycie tych wyników w pętli sprzężenia zwrotnego sterowania. Przykłady rozpatrywane w tekście są opisane dla procesu grawitacyjnego opróżniania materiałów sypkich przechowywanych w silosach

Computational modeling of multiphase fibrous flows for simulation based engineering design

This dissertation develops a modeling framework for predicting the behavior of fibrous bulk solids in pneumatic conveyance systems that are currently not possible with conventional computational models. The developed framework allows designers to computationally predict flow characteristics of fibrous bulk solids, which impacts pneumatic conveyance system performance. These performance characteristics include air and fibrous bulk solids velocity profiles, fibrous bulk solids concentrations, pressure loss, and general system behavior. The motivation for this research is to expand the capabilities of computational models within in the engineering design process, rather than relying solely on generalized experimental correlations and previous design experience. This framework incorporates the primary characteristics of fibrous biomass-based bulk solids including low density, large characteristic length, and non-spherical shape. The main features of the developed modeling framework are (1) the effects of the particle drag on the flowing air and (2) the resistive effects of the interconnected fibers between the particles. The models are implemented within a commercially available CFD solver package with user-defined functions. Velocity profiles, bulk solids concentration, and air pressure are modeled with the differential conservation equations for mass and momentum based on the Eulerian-Eulerian multiphase modeling approach. The inter-particle and the particle-air interactions result in momentum exchanges, and these exchanges are incorporated into the model through a series of externally defined user functions that account for the momentum exchange due to drag of the particles and the resistance of the connected fibers. These user-defined functions allow the user to set a series of parameters specific to the transported bulk solids and to the loading conditions. The model is applied to two specific studies, which include (1) cotton-air flow through a positive pressure pneumatic conveyance system and (2) biomass-air flow through a negative pressure (vacuum) conveyance system. The model parameters are chosen to match existing experimental data obtained from their corresponding lab tests

Flow measurement of pneumatically conveyed solids using intrusive electrostatic sensors

Particulate solids are commonly conveyed in industry by means of pneumatic pipelines. The particle flows often need to be controlled and maintained within certain bounds, but the development of instrumentation to monitor them remains a challenging area. A variety of techniques have been researched to measure various flow parameters. An overview of the existing technology is presented, along with advantages and limitations of each method. A detailed investigation is conducted into the use of electrostatic sensors with intrusive electrodes to measure the velocity of pneumatic particle flows. Previous work has been reported on the use of non-intrusive ring electrodes, but few studies of intrusive electrodes have been undertaken to date. Modelling, based on the finite element method, is used to determine the characteristics of the charge induced by solid particle flows onto intrusive electrodes. These are then compared with the properties of non-intrusive circular ring electrode elements. The effects of electrode intrusion depth are studied, and it is shown that whilst stability of the velocity measurements improves with intrusion depth, some types of flow are best measured using a particular intrusion that results in the most accurate average velocity reading. Electrode spacing, which must be close enough to allow a measurement to be taken but far enough to avoid unwanted interactive effects, is investigated, along with the effect of electrode cross sectional shape on sensor signals and the effect of common mode noise on cross correlation velocity measurement. This information is used in the development of a practical sensor system that uses embedded signal processing, which is then tested on laboratory and industrial flow rigs. The results are used to characterise the features of intrusive electrostatic sensors and their response to different flow conditions. Most significantly, intrusive electrodes are shown to be sensitive to localised flow regimes. Finally, suggestions on aspects of electrostatic sensors that would benefit from further development are discussed

Two-phase flow meter for determining water and solids volumetric flow rate in vertical and inclined solids-in-water flows

Multiphase flow can be defined as the simultaneous flow of a stream of two or more phases. Solids-in-water flow is a multiphase flows where solids and liquid are both present. Due to the density differences of the two phases, the results for such flow is often to have non-uniform profiles of the local volume fraction and local axial velocity for both phases in the flow cross-section. These non-uniform profiles are clearly noticeable in solids-in-water stratified flow with moving bed for inclined and horizontal pipelines. However in many industrial applications, such as oil and gas industry, food industry and mining industry, multiphase flows also exist and it is essentially important to determine the phase concentration and velocity distributions in through the pipe cross-section in order to be able to estimate the accurately the volumetric flow rate for each phase. This thesis describe the development of a novel non-intrusive flow meter that can be used for measuring the local volume fraction distribution and local axial velocity distributions of the continuous and discontinuous phases in highly non-uniform multiphase flows for which the continuous phase is electrically conducting and the discontinuous phase is an insulator. The developed flow meter is based on combining two measurement techniques: the Impedance cross correlation ICC technique and the electromagnetic velocity profiler EVP technique. Impedance cross correlation ICC is a non-invasive technique used to measure the local volume fraction distributions for both phases and the local velocity distribution for the dispersed phase over the pipe cross-section, whilst the electromagnetic velocity profiler EVP technique is used to v measure the local axial velocity profile of the continuous phase through the pipe cross-section. By using these profiles the volumetric flow rates of both phases can be calculated. A number of experiments were carried out in solid-in-water flow in the University of Huddersfield solids-in-water flow loop which has an 80 mm ID and an approximately 3m long working section. ICC and EVP systems were mounted at 1.6 m from the working section inlet which was inclined at 0 and 30 degree to the vertical. The obtained result for the flow parameters including phase volume fraction and velocity profiles and volumetric flow rates, have been compared with reference measurements and error sources of difference with their reference measurements have been identified and investigated

In-line powder flow behaviour measured using electrostatic technology

Within solid-dose manufacturing processes, powder flow and powder triboelectrification are critical to the quality of the final product. Off-line testers do not simulate the shear and packing conditions that a powder would experience in-process and may be unreliable in predicting in-line flow and charging properties, which are key components to successful formulation and process design. In this work, a dual-electrode, electrostatic powder flow sensor (EPFS) was used to obtain electrostatic signals that were generated in response to the pattern of flow of pharmaceutical powders in two density modes: The first being powders in lean phase flow, generated by free-fall of the powder from the outlet of a screw-feeder. The second being dense phase flow, through either 19.1 mm Ii.Dd. stainless-steel pipe or at the outlet of a tablet-press hopper. Powders were selected from a range of low to high cohesivity so as to study the effect of powder cohesion on the flow pattern. Electrostatic signals were then analysed by three distinct signal processing methods (RMS signal averaging, cross correlation, and Fast-Fourier-Transform) with a view to determining certain characteristics of powder flow, i.e. mass flow rate; cohesivity; and triboelectrification. In the first application a calibration was attempted to establish the link between the root-mean-square (RMS) of the electrostatic signal and the mass flow, as determined by the accumulation of mass on a balance placed below the screw-feeder (in the case of lean phase application) and the 19.1 mm i.d. pipe (in the case of dense phase application). In both cases it proved unsuccessful, owing to the instability in the electrostatic signal (i.e. its dependence on factors other than mass flow, for example inherent and induced charge fluctuations and moisture content). An alternative method for determining mass flow rate was proposed based on the second signal processing method, which involved the cross-correlation of signal from both sensors to determine the free-fall velocity. This method might work in future applications if combined with a suitable technique for determining the powder density. In the second application, a Fast-Fourier-Transform (FFT) of the electrostatic signal to yield an FFT spectrum was used to establish whether this technique could determine aspects of powder cohesivity. A correlation in rank order of cohesivity was observed between the ratio of the summed or averaged amplitudes at the three principle frequencies to the summed or averaged of the baseline components respectively, and the cohesivity of the powders, as determined by off-line powder rheometry assessments of dynamic flow and bulk properties. In the third application, the RMS signal normalised to the powder mass flow rate was used to study the time-dependent powder charging behaviour, which is induced by the transportation of the powder within the screw feeder. Characteristic relative charging profiles were obtained for each powder, which in some cases were coupled to charge-induced adhesion of the powder to the equipment. In the last application, the RMS signal generated from the EPFS sensor located at the outlet of the hopper on a rotary tablet press was used to interrogate the dense-phase intermittent-flow resulting from the dosing of the tablet die. Those more cohesive powders gave a larger RMS signal at the lower electrode (relative to the upper electrode) whereas less cohesive powders had similar RMS signals at each electrode. While the exact explanation of this effect is currently unknown these results suggest that the technique might be useful in the determination of die filling as a function of the input material characteristics. In summary, this work has provided some insight into the potential applications of EPFS for in-line measurement of powder flow and charging characteristics. Future work should focus on (i) developing an integrated sensor with an independent measurement of density to yield the powder mass flow using an inferential approach, (ii) co-use of techniques (such as Faraday-cup and charge decay analysers) to validate the in-line charging behaviour, (iii) further exploration of the significance of the signal amplitude difference at the tablet press hopper outlet in on the characteristics of the tablet compact