Mass transfer and particleinteractions in granular systems and suspension flows

The purpose of this study was to investigate some important features of granular flows and suspension flows by computational simulation methods. Granular materials have been considered as an independent state ofmatter because of their complex behaviors. They sometimes behave like a solid, sometimes like a fluid, and sometimes can contain both phases in equilibrium. The computer simulation of dense shear granular flows of monodisperse, spherical particles shows that the collisional model of contacts yields the coexistence of solid and fluid phases while the frictional model represents a uniform flow of fluid phase. However, a comparison between the stress signals from the simulations and experiments revealed that the collisional model would result a proper match with the experimental evidences. Although the effect of gravity is found to beimportant in sedimentation of solid part, the stick-slip behavior associated with the collisional model looks more similar to that of experiments. The mathematical formulations based on the kinetic theory have been derived for the moderatesolid volume fractions with the assumption of the homogeneity of flow. In orderto make some simulations which can provide such an ideal flow, the simulation of unbounded granular shear flows was performed. Therefore, the homogeneous flow properties could be achieved in the moderate solid volume fractions. A new algorithm, namely the nonequilibrium approach was introduced to show the features of self-diffusion in the granular flows. Using this algorithm a one way flow can beextracted from the entire flow, which not only provides a straightforward calculation of self-diffusion coefficient but also can qualitatively determine the deviation of self-diffusion from the linear law at some regions nearby the wall inbounded flows. Anyhow, the average lateral self-diffusion coefficient, which was calculated by the aforementioned method, showed a desirable agreement with thepredictions of kinetic theory formulation. In the continuation of computer simulation of shear granular flows, some numerical and theoretical investigations were carried out on mass transfer and particle interactions in particulate flows. In this context, the boundary element method and its combination with the spectral method using the special capabilities of wavelets have been introduced as theefficient numerical methods to solve the governing equations of mass transfer in particulate flows. A theoretical formulation of fluid dispersivity in suspension flows revealed that the fluid dispersivity depends upon the fluid properties and particle parameters as well as the fluid-particle and particle-particle interactions.

Characterisation of Hydrophobic Nonfibrous Material and Its Removal From Pulp Suspension

Paperin ja kartongin kierrätys lisääntyy taloudellisten intressien ja ympäristöhygieenisten tavoitteiden takia jatkuvasti. Lisääntyvän kierrätyksen myötä myös paperin ja kartongin epäpuhtauksien määrä kasvaa, mikä huonontaa kierrätysraaka-aineen laatua. Tämän työn tarkoituksena on antaa perustietoa eräästä kartongin päällystyksessä käytettävästä hydrofobisesta materiaalista, epäpuhtaan kartongin kierrätyksestä sekä ongelmista, joita epäpuhtaan kartongin kierrätyksestä syntyy. Kierrätyskuidun fraktiointi on yksinkertainen prosessi aallotuskartongin, testilainerin ja taivekartongin valmistuksessa. Kierrätysprosessin ensisijaisia tehtäviä ovat kuidutus ja epäpuhtauksien poisto sekä näiden epäpuhtauksien vaikutusten eliminointi, jotta kierrätysmassan laatuvaatimukset täyttyvät. Lisääntynyt epäpuhtauksien määrä raaka-aineessa asettaa vaatimuksia lajitteluprosessin kehittämiseksi. Nykyaikaisilla kierrätyslaitoksilla ei pystytä käsittelemään ylettömiä määriä epäpuhtauksia. Epäpuhtaudet aiheuttavat ongelmia ajettavuuteen ja heikentävät tuotteen laatua kierrätysprosessissa. Epäpuhtauksien poistoon on olemassa useita teknisiä ratkaisuja, mutta minkään niistä ei ole todettu täysin poistavan kaikkia ongelmia. Työn kokeellisessa osassa kartongin päällystykseen käytettävää hydrofobista materiaalia analysoitiin erilaisin menetelmin. Tutkittiin myös erilaisten olosuhteiden vaikutusta tämän materiaalin poistoon.

Management of Nitrogen Oxides Reduction Project in a Cement Plant

The main aim of this study was to develop the project management framework model which would serve as the new model to follow for upcoming projects at the Lappeenranta cement plant. The other goal was to execute the SNCR (selective non catalytic reduction) project successfully so that the nitrogen oxides emissions are below the stated emission limit when the new emission limit comes into effect beginning in July, 2008. Nitrogen oxides, project management aspects, SNCR and the invested system are explained in the theory part. In the practical part of the study, the SNCR project in the Lappeenranta cement plant was executed and the findings were documented. In order to reach the aim of this study, a framework of project management was made. The framework is based on the executed SNCR project, previous projects in the cement plant and on the available literature relating to the subject matter. The developed project turned out to be successful.

Future trends of Finnish cement based construction

The construction material sector, as a capital intensive industry, is highly vulnerable to rapid fluctuations in the economic cycles. In Finland this was witnessed especially during the late 2000s, as in 2007 and 2008 the demand for several construction materials exceeded their supply and right after this, in 2009 the demand collapsed fast as a result of an international recession. These factors brought about the need to study the future trends of the market place of the commissioning company, Finnsementti Oy. As reliable short term market forecasts for the sector are difficult to compose, the study concentrates primarily in examining and identifying the trends that are likely to affect the Finnish cement industry, and as an extension, the concrete industry in a frame of 10 to 15 years. The study’s scope comprehends also the examination of the domestic construction sector, as it represents the end user industry of both cement and concrete. These motives for the study produce the research problem, which is to conduct a trend analysis for cement based building in the Finnish market area in the 2020s. The theoretical frame for composing a trend analysis in the case of this study is twofold. This is due to the fact that both, the macro and micro environments of the examined industries are studied. The main methods used are the PESTE-model (macro) and Porter’s five forces model (micro). The study applies a qualitative approach and the data is gathered by interviewing a group of experts from the cement, concrete and construction industries. The result of the paper is an overall trend analysis for the Finnish cement based building sector, which is based on ‘sub trend analyses’ concerning four identified sub-sectors of the Finnish construction industry. The results are a combination of findings from these sub-sectors and the analyzed data that deals with the studied sector’s macro and micro environment. The conclusions provide an overall picture of the examined sectors’ potential future as a whole and by defined sub-sectors of the construction industry. The recognition of future trends in different areas of the construction industry can be applied as a means for an industry actor’s decision making and in estimating the types of construction that are likely to grow or decline. Finally, based on the analyzed data and conclusions, the commissioning company is provided with a brief SWOT analysis, that provides additional tools for decision making and planning processes regarding the future.

Characterization of fiber and vessel elements in pulp suspension images

The thesis is related to the topic of image-based characterization of fibers in pulp suspension during the papermaking process. Papermaking industry is focusing on process control optimization and automatization, which makes it possible to manufacture highquality products in a resource-efficient way. Being a part of the process control, pulp suspension analysis allows to predict and modify properties of the end product. This work is a part of the tree species identification task and focuses on analysis of fiber parameters in the pulp suspension at the wet stage of paper production. The existing machine vision methods for pulp characterization were investigated, and a method exploiting direction sensitive filtering, non-maximum suppression, hysteresis thresholding, tensor voting, and curve extraction from tensor maps was developed. Application of the method to the microscopic grayscale pulp images made it possible to detect curves corresponding to fibers in the pulp image and to compute their morphological characteristics. Performance of the method was evaluated based on the manually produced ground truth data. An accuracy of fiber characteristics estimation, including length, width, and curvature, for the acacia pulp images was found to be 84, 85, and 60% correspondingly.

Suspension esikäsittelyn vaikutus kiintoaineen laskeutumisnopeuteen

Laskeutus on yksinkertainen ja teollisuudessa paljon käytetty erotusmenetelmä. Laskeutusta käytetään yleisimmin metalliteollisuudessa ja jätevesienkäsittelyssä. Laskeuttimen erotustehokkuutta voidaan parantaa esikäsittelemällä laskeutettavaa suspensiota. Laskeutusta on tutkittu hyvin laajasti teollisuudessa, koska laskeutus on menetelmänä helposti toteutettava ja energiatehokas. Työn kirjallisuusosassa käsitellään perusteet kiintoaineen laskeutumisesta fluidissa, tutustutaan laskeuttimiin ja esitellään suspension esikäsittelymenetelmät. Työn kokeellisessaosassa tutkitaan esikäsittelymenetelmien vaikutusta kalsiumkarbonaattilietteen laskeutumisnopeuteen. Tutkittavia esikäsittelymenetelmiä työn kokeellisessaosassa ovat flokkulaatio, lämpötilan ja pH:n muuttaminen. Laskeutuskokeet suoritettiin tilavuusosuudella 10 % olevalla kalsiumkarbonaattilietteellä. Tutkimuksen tarkoituksena oli tutkia tutkittavien esikäsittelymenetelmien vaikutusta lietteen laskeutumisnopeuteen ja löytää optimiolosuhteet työssä käytettävän kalsiumkarbonaattilietteen laskeutumisessa. Koetuloksista havaitaan, että flokkulaatio ja lämpötilan muuttaminen vaikuttavat tehoikkaimmin lietteen laskeutumisnopeuteen. Flokkulaatio ja lämpötilan kohottaminen lisäävät huomattavasti kiintoaineen laskeutumista. Lisätutkimusta tarvitaan laajemmalta pH alueelta optimiolosuhteiden löytämiseksi. Lisäksi jatkotutkimuksia eri flokkulanteilla tarvitaan lisää, jotta voidaan löytää paras flokkulantti laskeutumisprosessin tehostamiseksi.

Karta öfver Degerhamn och trakten deromkring med husbyggnader tillhörige Ölands Cement Aktiebolag

Kartta kuuluu A. E. Nordenskiöldin kokoelmaan

The Possibility of Greenhouse Gas Mitigation in Ethiopian Cement Industry

Cement industry significantly associated with high greenhouse gas (GHG) emissions. Considering the environmental impact, particularly global warming potential, it is important to reduce these emissions to air. The aim of the study is to investigate the mitigation possibility of GHG emissions in Ethiopian cement industry. Life cycle assessment (LCA) method used to identify and quantify GHG emissions during one ton of ordinary portland cement (OPC) production. Three mitigation scenarios: alternative fuel use, clinker substitution and thermal energy efficiency were applied on a representative gate-to-gate flow model developed with GaBi 6 software. The results of the study indicate that clinker substitution and alternative fuel use play a great role for GHG emissions mitigation with affordable cost. Applying most energy efficient kiln technology, which in turn reduces the amount of thermal energy use, has the least GHG emissions reduction intensity and high implementation cost comparing to the other scenarios. It was found that the cumulative GHG emissions mitigation potential along with other selected mitigation scenarios can be at least 48.9% per ton of cement production.

Design of traction transmission and suspension systems for an omni-directional mobile robot

This project aims to design and manufacture a mobile robot with two Universal Robot UR10 mainly used indoors. In order to obtain omni-directional maneuverability, the mobile robot is constructed with Mecanum wheels. The Mecanum wheel can move in any direction with a series of rollers attached to itself. These rollers are angled at 45º about the hub’s circumference. This type of wheels can be used in both driving and steering with their any-direction property. This paper is focused on the design of traction system and suspension system, and the velocity control of Mecanum wheels in the close-loop control system. The mechanical design includes selection of bearing housing, couplers which are act as connection between shafts, motor parts, and other needed components. The 3D design software SolidWorks is utilized to assemble all the components in order to get correct tolerance. The driving shaft is designed based on assembled structure via the software as well. The design of suspension system is to compensate the assembly error of Mecanum wheels to guarantee the stability of the robot. The control system of motor drivers is realized through the Robot Operating System (ROS) on Ubuntu Linux. The purpose of inverse kinematics is to obtain the relationship among the movements of all Mecanum wheels. Via programming and interacting with the computer, the robot could move with required speed and direction.