43 resultados para Without Buffer Gas

em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland


Relevância:

30.00% 30.00%

Publicador:

Resumo:

Cutin and suberin are structural and protective polymers of plant surfaces. The epidermal cells of the aerial parts of plants are covered with an extracellular cuticular layer, which consists of polyester cutin, highly resistant cutan, cuticular waxes and polysaccharides which link the layer to the epidermal cells. A similar protective layer is formed by a polyaromatic-polyaliphatic biopolymer suberin, which is present particularly in the cell walls of the phellem layer of periderm of the underground parts of plants (e.g. roots and tubers) and the bark of trees. In addition, suberization is also a major factor in wound healing and wound periderm formation regardless of the plants’ tissue. Knowledge of the composition and functions of cuticular and suberin polymers is important for understanding the physiological properties for the plants and for nutritional quality when these plants are consumed as foods. The aims of the practical work were to assess the chemical composition of cuticular polymers of several northern berries and seeds and suberin of two varieties of potatoes. Cutin and suberin were studied as isolated polymers and further after depolymerization as soluble monomers and solid residues. Chemical and enzymatic depolymerization techniques were compared and a new chemical depolymerization method was developed. Gas chromatographic analysis with mass spectrometric detection (GC-MS) was used to assess the monomer compositions. Polymer investigations were conducted with solid state carbon-13 cross polarization magic angle spinning nuclear magnetic resonance spectroscopy (13C CP-MAS NMR), Fourier transform infrared spectroscopy (FTIR) and microscopic analysis. Furthermore, the development of suberin over one year of post-harvest storage was investigated and the cuticular layers from berries grown in the North and South of Finland were compared. The results show that the amounts of isolated cuticular layers and cutin monomers, as well as monomeric compositions vary greatly between the berries. The monomer composition of seeds was found to differ from the corresponding berry peel monomers. The berry cutin monomers were composed mostly of long-chain aliphatic ω-hydroxy acids, with various mid-chain functionalities (double-bonds, epoxy, hydroxy and keto groups). Substituted α,ω-diacids predominated over ω-hydroxy acids in potato suberin monomers and slight differences were found between the varieties. The newly-developed closed tube chemical method was found to be suitable for cutin and suberin analysis and preferred over the solvent-consuming and laborious reflux method. Enzymatic hydrolysis with cutinase was less effective than chemical methanolysis and showed specificity towards α,ω-diacid bonds. According to 13C CP-MAS NMR and FTIR, the depolymerization residues contained significant amounts of aromatic structures, polysaccharides and possible cutan-type aliphatic moieties. Cultivation location seems to have effect on cuticular composition. The materials studied contained significant amounts of different types of biopolymers that could be utilized for several purposes with or without further processing. The importance of the so-called waste material from industrial processes of berries and potatoes as a source of either dietary fiber or specialty chemicals should be further investigated in detail. The evident impact of cuticular and suberin polymers, among other fiber components, on human health should be investigated in clinical trials. These by-product materials may be used as value-added fiber fractions in the food industry and as raw materials for specialty chemicals such as lubricants and emulsifiers, or as building blocks for novel polymers.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The iron ore pelletizing process consumes high amounts of energy, including nonrenewable sources, such as natural gas. Due to fossil fuels scarcity and increasing concerns regarding sustainability and global warming, at least partial substitution by renewable energy seems inevitable. Gasification projects are being successfully developed in Northern Europe, and large-scale circulating fluidized bed biomass gasifiers have been commissioned in e.g. Finland. As Brazil has abundant biomass resources, biomass gasification is a promising technology in the near future. Biomasses can be converted into product gas through gasification. This work compares different technologies, e.g. air, oxygen and steam gasification, focusing on the use of the product gas in the indurating machine. The use of biosynthetic natural gas is also evaluated. Main parameters utilized to assess the suitability of product gas were adiabatic flame temperature and volumetric flow rate. It was found that low energy content product gas could be utilized in the traveling grate, but it would require burner’s to be changed. On the other hand, bio-SGN could be utilized without any adaptions. Economical assessment showed that all gasification plants are feasible for sizes greater than 60 MW. Bio-SNG production is still more expensive than natural gas in any case.

Relevância:

30.00% 30.00%

Publicador:

Resumo:

The aim of this thesis research work focused on the carbonate precipitation of magnesium using magnesium hydroxide Mg(OH)2 and carbon dioxide (CO2) gas at ambient temperature and pressure. The rate of dissolution of Mg(OH)2 and precipitation kinetics were investigated under different operating conditions. The conductivity and pH of the solution were inline monitored by a Consort meter and the solid samples gotten from the precipitation reaction were analysed by a laser diffraction analyzer Malvern Mastersizer to obtain particle size distributions (PSD) of crystal samples. Also the Mg2+ concentration profiles were determined from the liquid phase of the precipitate by ion chromatography (IC) analysis. Crystal morphology of the obtained precipitates were also investigated and discussed in this work. For the carbonation reaction of magnesium hydroxide in the present work, it was found that magnesium carbonate trihydrate (nesquehonite) was the main product and its formation occurred at a pH of around 7-8. The stirrer speed has a significant effect on the dissolution rate of Mg(OH)2. The highest obtained Mg2+ concentration level was 0.424 mol L-l for the 470 rpm and 0.387 mol L-1 for the 560 rpm which corresponded to the processing time of 45 mins and 40 mins respectively. The particle size distribution shows that the average particle size keeps increasing during the reaction as the CO2 is been fed to the system. The carbonation process is kinetically favored and simple as nesquehonite formation occurs in a very short time. It is a thermodynamically and chemically stable solid product, which allows for a long-term storage of CO2. Since the carbonation reaction is a complex system which includes dissolution of magnesium hydroxide particles, absorption of CO2, chemical reaction and crystallization, the dissolution of magnesium hydroxide was studied in hydrochloric acid (HCl) solvent with and without nitrogen (N2) inert gas. It was found on the dissolution part that the impeller speed had effect on the dissolution rate. The higher the impeller speed the higher the pH of the solution, although for the highest speed of 650rpm it was not the case. Therefore, it was concluded that the optimum speed of the stirrer was 560rpm. The influence of inert gas N2 on the dissolution rate of Mg(OH)2 particles could be seen based on measured pH, electric conductivity and Mg2+ concentration curves.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Selostus: Glysiinin ja alaniinin vaikutus CR1aa-liuoksessa viljeltyyn kumulussolullisen ja -soluttoman naudanalkion kehitykseen

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Selostus: Insuliinin vaikutus naudan blastokystien tuottamiseen in vitro kemiallisesti tunnetussa liuoksessa

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Suolahappo kuuluu peruskemianteollisuuden tuotteisiin ja on monen eri kemianteollisuuden tuotteen raaka-aine, jota ilman tuotantoprosessi keskeytyy. Suolahapontuottajia on vain muutama Suomessa ja näiden tuottajien varassa toimii lukuisia jatkojalostusteollisuuslaitoksia. Työssä lähdettiin kehittämään suolahapontoimitusvarmuutta logistiikan keinoin. Toimitusvarmuutta haluttiin kehittää sesonkivaihteluiden ja tuotantokatkosten aikana. Työssä etsitään sopiva sesonkivarastointikapasiteetti ja varmuusvarastotaso sekä järkevä sijainti varastolle. Varastointia kehitetään kuljetukset ja tuotannon luonne huomioiden. Työn alussa esitellään yritys ja tuotantoprosessi. Tämän jälkeen analysoidaan kysyntätietoja ja kasataan ongelmat toimitusvarmuudessa. Näiden pohjalta lähdetään kehittämään teoriapohjaisia ratkaisuvaihtoehtoja, jonka jälkeen ne sovelletaan yritykselle sopivaan muotoon. Työn tuloksena saatiin esitys varastointitarpeesta sekä siitä aiheutuvista kustannuksista. Työssäesitetään myös järkevä varaston sijainti ja soveltuva kuljetuskäytäntö tähän varastoon.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this thesis is to reveal how the laser cutting parameters influence lasercutting of particleboard, HDF and MDF. The literature review introduces the basic principle of CO2 laser, CO2 laser equipment and its usage in cutting of wood-based materials. The experimental part focuses on the discussion and analysis ofthe test data and attempts to draw conclusions on the influence of various parameters, including laser power, focal length of the lens and cutting gas, on the cutting speed and kerf quality. The tested materials include various thicknesses of particleboard, HDF and MDF samples. A TRUMPF TLF2700 HQ laser equipment was used for the experiments. To obtain valid data, the test samples must be completely cut through without any bonding of wood fibre. The maximum cutting speed is linear dependent on the laser power in thecondition that the other parameters are constant. For each thickness of a specific material type, there is a minimum laser power for cutting. Normally, the topand bottom kerf widths increase with the enhancement of laser power. There may be a critical laser power which can generate the minimum cross-sectional kerf width. Lens of larger focal length may achieve higher cutting speed. As the focal length becomes larger, the top kerf width tends to increase while the bottom andcross-sectional kerf widths to the opposite. Of all cutting gases, oxygen can help achieve higher cutting speed. The gas pressure of nitrogen does not seem to have strong influence on the cutting result. Generally, 2 bar air is more preferable for higher cutting speed. For particleboard and MDF samples of larger thickness than 12 mm, 2 bar argon can be used to reach remarkably higher cutting speed than the 5 bar. Generally, the 190.5 mm lens can produce smallest total kerf width. The kerf sides of thicker samples are darker than the thinner ones. The sample darkness tends to be lower as laser power increased. 63.5 mm lens seemed tocause more darkness than other lens. 5 bar cutting gases can produce less dark side kerfs than 2 bar ones. Oxygen normally causes darker kerfs than other gases. No distinct differences were found between nitrogen and argon.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Nowadays the used fuel variety in power boilers is widening and new boiler constructions and running models have to be developed. This research and development is done in small pilot plants where more faster analyse about the boiler mass and heat balance is needed to be able to find and do the right decisions already during the test run. The barrier on determining boiler balance during test runs is the long process of chemical analyses of collected input and outputmatter samples. The present work is concentrating on finding a way to determinethe boiler balance without chemical analyses and optimise the test rig to get the best possible accuracy for heat and mass balance of the boiler. The purpose of this work was to create an automatic boiler balance calculation method for 4 MW CFB/BFB pilot boiler of Kvaerner Pulping Oy located in Messukylä in Tampere. The calculation was created in the data management computer of pilot plants automation system. The calculation is made in Microsoft Excel environment, which gives a good base and functions for handling large databases and calculations without any delicate programming. The automation system in pilot plant was reconstructed und updated by Metso Automation Oy during year 2001 and the new system MetsoDNA has good data management properties, which is necessary for big calculations as boiler balance calculation. Two possible methods for calculating boiler balance during test run were found. Either the fuel flow is determined, which is usedto calculate the boiler's mass balance, or the unburned carbon loss is estimated and the mass balance of the boiler is calculated on the basis of boiler's heat balance. Both of the methods have their own weaknesses, so they were constructed parallel in the calculation and the decision of the used method was left to user. User also needs to define the used fuels and some solid mass flowsthat aren't measured automatically by the automation system. With sensitivity analysis was found that the most essential values for accurate boiler balance determination are flue gas oxygen content, the boiler's measured heat output and lower heating value of the fuel. The theoretical part of this work concentrates in the error management of these measurements and analyses and on measurement accuracy and boiler balance calculation in theory. The empirical part of this work concentrates on the creation of the balance calculation for the boiler in issue and on describing the work environment.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In bubbly flow simulations, bubble size distribution is an important factor in determination of hydrodynamics. Beside hydrodynamics, it is crucial in the prediction of interfacial area available for mass transfer and in the prediction of reaction rate in gas-liquid reactors such as bubble columns. Solution of population balance equations is a method which can help to model the size distribution by considering continuous bubble coalescence and breakage. Therefore, in Computational Fluid Dynamic simulations it is necessary to couple CFD and Population Balance Model (CFD-PBM) to get reliable distribution. In the current work a CFD-PBM coupled model is implemented as FORTRAN subroutines in ANSYS CFX 10 and it has been tested for bubbly flow. This model uses the idea of Multi Phase Multi Size Group approach which was previously presented by Sha et al. (2006) [18]. The current CFD-PBM coupled method considers inhomogeneous flow field for different bubble size groups in the Eulerian multi-dispersed phase systems. Considering different velocity field for bubbles can give the advantageof more accurate solution of hydrodynamics. It is also an improved method for prediction of bubble size distribution in multiphase flow compared to available commercial packages.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Diplomityössä tutkitaan kolmea erilaista virtausongelmaa CFD-mallinnuksella. Yhteistä näille ongelmille on virtaavana aineena oleva ilma. Lisäksi tapausten perinteinen mittaus on erittäin vaikeaa tai mahdotonta. Ensimmäinen tutkimusongelma on tarrapaperirainan kuivain, jonka tuotantomäärä halutaan nostaa kaksinkertaiseksi. Tämä vaatii kuivatustehon kaksinkertaistamista, koska rainan viipymäaika kuivausalueella puolittuu. Laskentayhtälöillä ja CFD-mallinnuksella tutkitaan puhallussuihkun nopeuden ja lämpötilan muutoksien vaikutusta rainan pinnan lämmön- ja massansiirtokertoimiin. Tuloksena saadaan varioitujen suureiden sekä massan- ja lämmönsiirtokertoimien välille riippuvuuskäyrät, joiden perusteella kuivain voidaan säätää parhaallamahdollisella tavalla. Toinen ongelma käsittelee suunnitteilla olevan kuparikonvertterin sekundaarihuuvan sieppausasteen optimointia. Ilman parannustoimenpiteitä käännetyn konvertterin päästöistä suurin osa karkaa ohi sekundaarihuuvan. Tilannetta tutkitaan konvertterissa syntyvän konvektiivisen nostevirtauksen eli päästöpluumin sekä erilaisten puhallussuihkuratkaisujen CFD-mallinnuksella. Tuloksena saadaan puhallussuihkuilla päästöpluumia poikkeuttava ilmaverho. Suurin osa nousevasta päästöpluumista indusoituu ilmaverhoon ja kulkeutuu poistokanavaan. Kolmas tutkittava kohde on suunnitteilla oleva kuparielektrolyysihalli, jossa ilmanvaihtoperiaatteena on luonnollinen ilmanvaihto ja mekaaninen happosumun keräysjärjestelmä. Ilmanvaihtosysteemin tehokkuus ja sisäilman virtaukset halutaan selvittää ennen hallin rakentamista. CFD-mallinnuksella ja laskentayhtälöillä tutkitaan lämpötila- ja virtauskentät sekä hallin läpi virtaava ilmamäärä ja ilmanvaihtoaste. Tulo- ja poistoilma-aukkojen mitoitukseen ja sijoitukseen liittyvät suunnitteluarvot varmennetaan sekä löydetään ilmanvaihdon ongelmakohdat. Ongelmakohtia tutkitaan ja niille esitetään parannusehdotukset.