The Fluid Structure Interaction Analysis of a Peristaltic Pump

The thesis work models the squeezing of the tube and computes the fluid motion of a peristaltic pump. The simulations have been conducted by using COMSOL Multiphysics FSI module. The model is setup in axis symmetric with several simulation cases to have a clear understanding of the results. The model captures total displacement of the tube, velocity magnitude, and average pressure fluctuation of the fluid motion. A clear understanding and review of many mathematical and physical concepts are also discussed with their applications in real field. In order to solve the problems and work around the resource constraints, a thorough understanding of mass balance and momentum equations, finite element concepts, arbitrary Lagrangian-Eulerian method, one-way coupling method, two-way coupling method, and COMSOL Multiphysics simulation setup are understood and briefly narrated.

Continuous Counter-current Solvent Extraction of Magnesium and Calcium from Lithium-rich Brine

Solvent extraction of calcium and magnesium impurities from a lithium-rich brine (Ca ~ 2,000 ppm, Mg ~ 50 ppm, Li ~ 30,000 ppm) was investigated using a continuous counter-current solvent extraction mixer-settler set-up. The literature review includes a general review about resources, demands and production methods of Li followed by basics of solvent extraction. Experimental section includes batch experiments for investigation of pH isotherms of three extractants; D2EHPA, Versatic 10 and LIX 984 with concentrations of 0.52, 0.53 and 0.50 M in kerosene respectively. Based on pH isotherms LIX 984 showed no affinity for solvent extraction of Mg and Ca at pH ≤ 8 while D2EHPA and Versatic 10 were effective in extraction of Ca and Mg. Based on constructed pH isotherms, loading isotherms of D2EHPA (at pH 3.5 and 3.9) and Versatic 10 (at pH 7 and 8) were further investigated. Furthermore based on McCabe-Thiele method, two extraction stages and one stripping stage (using HCl acid with concentration of 2 M for Versatic 10 and 3 M for D2EHPA) was practiced in continuous runs. Merits of Versatic 10 in comparison to D2EHPA are higher selectivity for Ca and Mg, faster phase disengagement, no detrimental change in viscosity due to shear amount of metal extraction and lower acidity in stripping. On the other hand D2EHPA has less aqueous solubility and is capable of removing Mg and Ca simultaneously even at higher Ca loading (A/O in continuous runs > 1). In general, shorter residence time (~ 2 min), lower temperature (~23 °C), lower pH values (6.5-7.0 for Versatic 10 and 3.5-3.7 for D2EHPA) and a moderately low A/O value (< 1:1) would cause removal of 100% of Ca and nearly 100% of Mg while keeping Li loss less than 4%, much lower than the conventional precipitation in which 20% of Li is lost.

Analysis of Phase Separator Design Criteria Using Computational Fluid Dynamics

Gravitational phase separation is a common unit operation found in most large-scale chemical processes. The need for phase separation can arise e.g. from product purification or protection of downstream equipment. In gravitational phase separation, the phases separate without the application of an external force. This is achieved in vessels where the flow velocity is lowered substantially compared to pipe flow. If the velocity is low enough, the denser phase settles towards the bottom of the vessel while the lighter phase rises. To find optimal configurations for gravitational phase separator vessels, several different geometrical and internal design features were evaluated based on simulations using OpenFOAM computational fluid dynamics (CFD) software. The studied features included inlet distributors, vessel dimensions, demister configurations and gas phase outlet configurations. Simulations were conducted as single phase steady state calculations. For comparison, additional simulations were performed as dynamic single and two-phase calculations. The steady state single phase calculations provided indications on preferred configurations for most above mentioned features. The results of the dynamic simulations supported the utilization of the computationally faster steady state model as a practical engineering tool. However, the two-phase model provides more truthful results especially with flows where a single phase does not determine the flow characteristics.

Excavation-drier method of energy-peat extraction reduces long-term climatic impact

Climatic impacts of energy-peat extraction are of increasing concern due to EU emissions trading requirements. A new excavation-drier peat extraction method has been developed to reduce the climatic impact and increase the efficiency of peat extraction. To quantify and compare the soil GHG fluxes of the excavation drier and the traditional milling methods, as well as the areas from which the energy peat is planned to be extracted in the future (extraction reserve area types), soil CO2, CH4 and N2O fluxes were measured during 2006–2007 at three sites in Finland. Within each site, fluxes were measured from drained extraction reserve areas, extraction fields and stockpiles of both methods and additionally from the biomass driers of the excavation-drier method. The Life Cycle Assessment (LCA), described at a principal level in ISO Standards 14040:2006 and 14044:2006, was used to assess the long-term (100 years) climatic impact from peatland utilisation with respect to land use and energy production chains where utilisation of coal was replaced with peat. Coal was used as a reference since in many cases peat and coal can replace each other in same power plants. According to this study, the peat extraction method used was of lesser significance than the extraction reserve area type in regards to the climatic impact. However, the excavation-drier method seems to cause a slightly reduced climatic impact as compared with the prevailing milling method.

Utilizing hemicelluloses – the first step : controlled extraction with hot water

Människor utnyttjar ofta kemi mångsidigt i sitt vardagliga liv utan att närmare tänka på detaljerna. Nuförtiden kan man framställa en ökande mängd av produkter ur förnybara råmaterial och en av de mest mångsidiga nybara råmaterialet i Norden är barrträd. Den lyriska lägerelden eller spiselden och möbler av ved samt papper är en väsentlig del av vardagen. Också livsmedel och läkemedel kan innehålla föreningar ur ved. Ved som råmaterial består av tre huvudkomponenten: cellulosa, som är uppbyggd av druvsockermolekyler är en långkedjad, oförgrenad polymer; lignin, som sammanhåller fibrerna i vedmaterialet som lim samt hemicellulosor, som ofta är uppbyggda av olika sockerarter och är en förgrenad polymer. Följaktligen består vedmaterialet av 70 % socker. I detta arbete har vi koncentrerat på i hemicellulosa och dess extraktion ur gran, samt bestämning av hemicellulosans egenskaper. Den slutliga målsättningen i forskningen var att skapa nya produkter ur gran. Forskning i extraktionens hemligheter eller hur hemicellulosa kan effektivt extraheras i den önskade formen kräver nya typers experimentellasanläggningar och experiment samt matematisk modellering. Den långkedjade hemicellulosan är lämplig för att användas t.ex. i skyddshinnor eller i livsmedel. Medel- och småmolekylär hemicellulosa kan användas som utgångsämne för framställning av bränslen, smörjmedel, sockersyror och alkoholer, av vilka xylitol är mest känd för alla pga hälsobefrämjande effekter. Det är utomordentligt viktigt ur miljöns och energiekonomins synvinkel att sträva efter effektivering av utnyttjandet av den värdefullaste och största naturtillgången, skogen i vårt land, med alla möjliga sätt. Resultaten av denna forskning utnyttjar avsevärt den växande, nya, på skogen baserande biobaseradeindustrin, som framställer nya spetsprodukter samt skapar nya arbetsplatser. ----------------------------------------------------- Ihmiset hyödyntävät usein huomaamattaan kemiaa monipuolisesti jokapäiväisessä elämässä. Nykyään kasvava määrä tuotteista kyetään valmistamaan uusiutuvista raaka-aineista ja yksi monipuolisimmista uusiutuvista luonnonvaroistamme pohjolassa ovat havupuut. Tunnelmallinen nuotio tai takkatuli ja puiset huonekalut sekä paperi ovat olennainen osa arkea. Myös elintarvikkeet ja lääkkeet voivat sisältää puusta peräisin olevia yhdisteitä. Puu materiaalina koostuu rakenteeltaan pääosin kolmesta osasta; selluloosasta, joka on rypälesokerista koostuva pitkäketjuinen haaroittumaton polymeeri, ligniinistä, joka toimii puun koossa pitävänä liima-aineena ja hemiselluloosasta, joka on useista eri sokereista rakentunut haaroittunut polymeeri. Näin ollen puusta 70 % on sokeria. Tässä työssä olemme keskittyneet hemiselluloosaan ja sen uuttamiseen kuusesta, sekä ominaisuuksien kartoittamiseen. Tutkimusaiheen lopullinen tavoite on luoda uusia tuotteita kuusesta. Uuton salojen tutkiminen eli miten hemiselluloosa saadaan tehokkaasti uutettua halutunlaisena vaatii uudenlaisia koelaitteistoja ja kokeita, sekä matemaattista mallintamista. Suurikokoinen hemiselluloosa on sopivaa käytettäväksi esimerkiksi suojakalvoissa tai elintarvikkeissa. Keskikokoista ja pienimolekyylistä hemiselluloosaa voidaan käyttää lähtöaineena valmistettaessa polttoaineita, voiteluaineita, sokerihappoja ja sokerialkoholeja, joista xylitoli on terveysvaikutustensa vuoksi kaikille tuttu. Niin ympäristömme kuin myös energiataloutemme kannalta on ensiarvoisen tärkeää pyrkiä kaikin keinoin tehostamaan maallemme arvokkaan, sekä luonnonvaroistamme yhden suurimman, metsän, vastuullista hyödyntämistä. Tämän tutkimuksen tulokset hyödyntävät merkittävästi maahamme nousevaa uutta metsään pohjautuvaa biojalostusteollisuutta, joka valmistaa uusia huipputuotteita sekä luo työpaikkoja.

Reducing auxiliary power of a fluid bed boiler island

The aim of this thesis is to find and analyze different methods which reduce fluid bed boilers’ auxiliary power consumption. The objective is to examine the effects and feasibility of these methods. The literature part explains how fluid bed boilers work and what are the main sources of auxiliary power consumption. Designs and operation of these equipment are presented. The literature part also discusses the basics of auxiliary power consumption reduction and introduces four low pressure drop constructions. The experimental part inspects six different methods. Effects of these methods on the auxiliary power consumption are calculated and their impacts on the operation of the boiler are modeled. Calculations show that reasonable changes can reduce fluid bed boiler’s auxiliary power consumption by 2,1-10,2 %. Biggest reductions come from lower air coefficients, smaller bed a-level pressures and lower primary/secondary air –ratios. Models showed no problems with the smaller bed a-level pressures. With the lower air coefficients and smaller primary/secondary air –ratios the models showed a significant increase in the carbon monoxide levels.

Variable-speed-drive-based detection methods for problems in fluid handling systems

Fluid handling systems account for a significant share of the global consumption of electrical energy. They also suffer from problems, which reduce their energy efficiency and increase life-cycle costs. Detecting or predicting these problems in time can make fluid handling systems more environmentally and economically sustainable to operate. In this Master’s Thesis, significant problems in fluid systems were studied and possibilities to develop variable-speed-drive-based detection methods for them was discussed. A literature review was conducted to find significant problems occurring in fluid handling systems containing pumps, fans and compressors. To find case examples for evaluating the feasibility of variable-speed-drive-based methods, queries were sent to industrial companies. As a result of this, the possibility to detect heat exchanger fouling with a variable-speed drive was analysed with data from three industrial cases. It was found that a mass flow rate estimate, which can be generated with a variable speed drive, can be used together with temperature measurements to monitor a heat exchanger’s thermal performance. Secondly, it was found that the fouling-related increase in the pressure drop of a heat exchanger can be monitored with a variable speed drive. Lastly, for systems where the flow device is speed controlled with by a pressure measurement, it was concluded that increasing rotational speed can be interpreted as progressing fouling in the heat exchanger.