Reactive dissolution of sedimentary rocks in flue gas desulfurization : modeling and experimental investigation

Svavel förekommer i kol och olja och oxideras vid förbränning till svaveldioxid (SO2). Årligen utsläpps stora mängder svaveldioxid som åstadkommer sura regn, minskning av stratosfäriskt ozon och sjukdomar. Av dessa orsaker är det nödvändigt att minska utsläppen av svaveldioxid. Den teknologi som rör planering av reaktorer och processer för rökgasavsvavling (FGD) har utvecklats kraftigt och idag använder man olika typer av lösningar. De vanligaste alternativen för FGD är våtskrubber- och semitorra skrubbersystem (Spray Dry Scrubbers, SDS) och injektionsprocesser för absorbenter. SDS-processer har studerats bland annat av Ahlbeck [4] och Klingspor [5] och injektionsprocesser av Alvfors [6]. Kalksten, som i huvusak består av kalciumkarbonat, används i rökgasavsvavling på grund av sin förmåga att binda svavel i form av sulfatsalter. Den vanligaste rökgasavsvavlingsmetoden är våtskrubbning, där det sedimentära stenmaterialets upplösningshastighet är en av de faktorer som påverkar resultatet mest. Utvärdering av kalkstensreaktivitet är därför speciellt viktig vid planering och drift av anläggningar för rökgasavsvavling. Målsättningen med detta arbete var att modellera upplösningen av olika typers kalksten för att få en kvantitativ utvärdering av kvaliteten på de analyserade proverna. Därtill testades även karbonatbiprodukter från stålindustrin för att utvärdera möjligheter att använda andra råmaterial. Det transienta förloppet har analyserats, varvid upplösningshastigheten modellerades bl.a. i avseende på tid och pH. Under arbetets gång har antalet empiriska korrelationer minskats till fördel för fysikaliska modeller av diffusiva och konvektiva masstransportfenomen. En målsättning var att skapa en effektiv och snabb metod för att testa olika absorbenter för rökgasavsvavling under transienta förlopp. I arbetet användes PSD-analys, gjordes pH-mätningar och andra utvärderingar av de fysikaliska parametrar som ingår i beräkningarna. On-line mätningar för de icke-stationära variablerna tid och pH ger möjlighet att eliminera osäkerheter. Vissa modeller kan vara komplicerade. En modell för upplösningshastigheten med mer detaljerad utvärdering av parametrar och färre approximationer är därför nödvändig då man vill utvärdera reaktionshastigheten för fasta partiklar i sur miljö. Arbetet utfördes under fyra år och fem peer review-artiklar ingår i avhandlingen.

Sähkön ja lämmön yhteistuotanto haasteellisilla polttoaineilla

Maailman energian kulutuksen lisääntymisen ja ilmastonmuutoksen myötä energiantuotannossa joudutaan jatkuvasti sopeutumaan muuttuviin tilanteisiin ja haasteisiin. Polttoteknillisiä haasteita aiheuttavat pelto- ja kierrätyspolttoaineet ovat lisäämässä osuuttaan uusiutuvien polttoaineiden joukossa. Jotta kyseisiä haasteellisia polttoaineita pystytään hyödyntämään, täytyy niiden aiheuttamat ongelmat tuntea ja laitevalmistajien kehittää niiden hyödyntämiseen sopivaa tekniikkaa. Tässä diplomityössä käydään läpi tulevaisuudessa käytettävät polttoaineet, nykyiset päästörajat, kiinteiden polttoaineiden poltto- ja kaasutustekniikat sekä likaantumis-, kuonaantumis- ja korroosiomekanismit voimalaitoskattiloissa. Työssä tutkitaan, onko haasteellisten polttoaineiden käyttöön investoiminen järkevää ja mikä nykypäivän tekniikoista on kannattavin. Myös välitulistuksen, lauhdeperän ja apujäähdyttimen kannattavuuksia vertaillaan sähkön ja lämmön yhteistuotannossa. Tuloksiksi saatiin, että edullisten peltobiomassojen ja kierrätyspolttoaineiden käyttäminen, joko perinteisten polttoaineiden seassa tai pääpolttoaineena, on nykyhinnoilla perinteisiin polttoaineisiin verrattuna kannattavaa. Investoiminen kierrätyspolttoaineiden valmistuslaitteisiin maksimoi kierrätyspolttoaineista saatavaa hyötyä. Välitulistuksen todettiin soveltuvan huonosti vastapaineprosessiin, sillä siitä saatava sähköntuotannon lisäys on hyvin pieni. Lauhdeperän ja apujäähdyttimen vertailuissa huomattiin, että lauhdeperä on kannattava investointi, jos sähkön ja lämmön hintaero pysyy tarpeeksi suurena. Haasteellisilla polttoaineilla pystytään pienentämään kasvihuonepäästöjä ja korvaamaan fossiilisten polttoaineiden käyttöä.

Production of Biofuels by Fischer Tropsch Synthesis

Production of biofuel via biomass gasification followed by Fischer Tropsch synthesis is of considerable interest because of the high quality of fuels produced which do not contain sulphur and are free of carbon dioxide. The purpose of this Master’s thesis is to study feasibility production of biofuels integrated with Fischer Tropsch process using Aspen Plus simulation. The simulation results were used to size process equipment and carry out an economic evaluation. The results show that lowering the reactor temperature from 1000 oC - 850 oC and raising the water gas shift temperature from 500 oC - 600 oC can improve overall gas efficiency, which in turn leads to better production of ultra clean syngas for the Fischer Tropsch synthetic reactor. Similarly, the Fischer Tropsch offgas is converted into a gas turbine for power production, and finally biodiesel is produced as fuels for transportation.

Initial development and gas exchange of Talisia subalbens (Mart.) Radlk. under different shading conditions

Ecophysiological studies under semi-controlled conditions in nurseries and greenhouses are essential to enable the use of native species to recover degraded areas and for commercial planting. Talisia subalbens (Mart) Radlk, 'cascudo', is a native fruiting species of the Cerrado on the verge of extinction. The ecophysiological performance of this species was evaluated in nursery conditions under different levels of shading (full sunshine, 30%, 50% and 70%). Initial growth, biomass allocation, gas exchange and chlorophyll content of the plants were analyzed. Full sunshine cultivated plants showed a higher accumulation of total, shoot, and root dry biomass. There was no significant difference in the root/shoot ratio among the treatments. Seedlings cultivated under full sunshine and 30% shading showed higher values for height, basal diameter, and leaf area. Differences in stomata conductance and photosynthesis rate were not observed among the different shading levels. Plants cultivated under 70% of shading had higher contents of chlorophyll a, b, and total. During the initial phase with higher levels of radiation were fundamental for the development of T. subalbens seedlings.

GAS EXCHANGE IN YOUNG PLANTS OF Tabebuia aurea(Bignoniaceae Juss.) SUBJECTED TO FLOODING STRESS1

ABSTRACT The Paratudo (Tabebuia aurea) is a species occurring in the Pantanal of Miranda, Mato Grosso do Sul, Brazil, an area characterized by seasonal flooding. To evaluate the tolerance of this plant to flooding, plants aged four months were grown in flooded soil and in non-flooded soil (control group). Stomatal conductance, transpiration and CO2 assimilation were measured during the stress (48 days) and recovery (11 days) period, totalling 59 days. The values of stomatal conductance of the control group and stressed plants at the beginning of the flooded were 0.33 mol m-2s-1 and reached 0.02 mol m-2 s-1 (46th day) at the end of this event. For the transpiration parameter, the initial rate was 3.1 mol m s-1, and the final rate reached 0.2 or 0.3 mol m-2 s-1 (47/48 th day). The initial photosynthesis rate was 8.9 mmol m-2s-1 and oscillated after the sixth day, and the rate reached zero on the 48th day. When the photosynthesis rate reached zero, the potted plants were dried, and the rate was analyzed (11th day). The following values were obtained for dried plants: stomatal conductance = 0.26 mol m-2 s-1, transpiration rate = 2.5 mol m-2 s-1 and photosynthesis rate = 7.8 mmol m-2 s-1. Flooded soil reduced photosynthesis and stomatal conductance, leading to the hypertrophy of the lenticels. These parameters recovered and after this period, and plants exhibited tolerance to flooding stress by reducing their physiological activities.

Metanolin tuotanto biomassasta

Tämä työ käsittelee eri tapoja, joilla biomassasta voidaan valmistaa metanolia. Työssä käydään läpi eri valmistusreitit sekä tarkastellaan biomassaa raaka-aineena. Työhön on myös koottu joidenkin maailmalla tehtyjen tutkimusten aine- ja energiataseita. Tutkimusten pohjalta mietitään onko metanolin tuotanto liikennepolttoaineeksi tällä hetkellä taloudellisesti tai energiatehokkuudeltaan järkevää. Metanolia voidaan valmistaa biomassasta pääsääntöisesti viidellä eri tavalla. Ensimmäinen tapa on kaasuttaa biomassaa, jolloin tuotetaan raaka-kaasua. Raaka-kaasusta jalostetaan synteesikaasua, josta voidaan metanolisynteesillä valmistaa metanolia. Toinen tapa metanolin valmistamiseksi on liittää tuotanto sellunkeiton yhteyteen. Tällöin raaka-aineena olisi selluprosessissa syntyvä mustalipeä, josta metanoli voidaan erottaa. Kolmas mahdollinen valmistusprosessi on biomassan mädätys. Mädätyksessä syntyy biokaasua, josta jalostetaan synteesikaasuaja siitä edelleen metanolia. Neljäs keino metanolin valmistamiseksi biomassasta on pyrolyysi. Puun pyrolyysissä puu kuumennetaan nopeasti hapettomissa tai rajallisen hapensaannin olosuhteissa. Prosessissa syntyvästä pyrolyysiöljystä voidaan erottaa metanolia tislaamalla. Viides mahdollinen reitti metanolin valmistukselle on Fischer¬–Tropsch-synteesi. Biomassasta saatu synteesikaasu johdetaan FT-synteesiin, jossa katalyyttisesti saadaan hiilivetyjen ohella tuotettua metanolia. Biopolttoaineiden kuten metanolin valmistusprosesseja tutkitaan ja kehitetään jatkuvasti, sillä uusiutumattomat energianlähteet eivät riitä loputtomasti ja niiden aiheuttamia hiilidioksidipäästöjä halutaan vähentää. Tällä hetkellä tuotantoteknologiat eivät ole vielä tarpeeksi kehittyneet, jotta tuotanto saataisiin vastaamaan kulutusta. Metanolia ei kuitenkaan vielä voida käyttää sellaisenaan liikennepolttoaineena, joten metanolin markkinat ainakin vielä ovat sillä saralla varsin kapeat.

Simulation and optimization of IGCC technique for power generation and hydrogen production by using lignite Thar coal and cotton stalk

The purpose of this study was to simulate and to optimize integrated gasification for combine cycle (IGCC) for power generation and hydrogen (H2) production by using low grade Thar lignite coal and cotton stalk. Lignite coal is abundant of moisture and ash content, the idea of addition of cotton stalk is to increase the mass of combustible material per mass of feed use for the process, to reduce the consumption of coal and to increase the cotton stalk efficiently for IGCC process. Aspen plus software is used to simulate the process with different mass ratios of coal to cotton stalk and for optimization: process efficiencies, net power generation and H2 production etc. are considered while environmental hazard emissions are optimized to acceptance level. With the addition of cotton stalk in feed, process efficiencies started to decline along with the net power production. But for H2 production, it gave positive result at start but after 40% cotton stalk addition, H2 production also started to decline. It also affects negatively on environmental hazard emissions and mass of emissions/ net power production increases linearly with the addition of cotton stalk in feed mixture. In summation with the addition of cotton stalk, overall affects seemed to negative. But the effect is more negative after 40% cotton stalk addition so it is concluded that to get maximum process efficiencies and high production less amount of cotton stalk addition in feed is preferable and the maximum level of addition is estimated to 40%. Gasification temperature should keep lower around 1140 °C and prefer technique for studied feed in IGCC is fluidized bed (ash in dry form) rather than ash slagging gasifier

Evaluation of the heating of broilers in shed by means of gas hoods and underfloor heating

This study was conducted to evaluate and compare the behavior of the heating inside poultry shed through gas hood and underfloor heating. The experiment was conducted in poultry shed belonging to the Federal Institute of Education, Science and Technology of Triângulo Mineiro Region, Uberlândia city – state of Minas Gerais (MG), Brazil. The dimensions of the shed are 24 meters long and 9.6 meters wide and with a ceiling height of 3.2 meters. The temperature was measured with an optical thermometer of Minipa brand, MT 350 model. It was used, to the analysis of temperature behavior, the public domain software FEMM 4.2, which uses finite elements techniques, with data collected from two lots. Underfloor heating is made using hot water flowing through a serpentine type system, which is installed below the bed; this hot water is from solar heaters. An energetic and economic assessment of the warming shed for raising chickens was realized. From the results obtained with the simulations, it may observe that the heating through the floor provides a more homogeneous distribution of temperature when compared with the hood heating. The flow of heat is upwards supplying, thus, the greatest need of heating of the bird, which is the pectoral part.

Motores de reacción modernos por turbinas de gas

This Bachelor’s thesis investigates the different types of jet engines used nowadays, their performance and applications. The thesis includes a general study of dynamics of fly, engine thermodynamics and contamination.

Corporate Social Responsibility in the Oil and Gas Industry: Environmental Management Systems as a Source of Sustainable Development

The environmental aspect of corporate social responsibility (CSR) expressed through the process of the EMS implementation in the oil and gas companies is identified as the main subject of this research. In the theoretical part, the basic attention is paid to justification of a link between CSR and environmental management. The achievement of sustainable competitive advantage as a result of environmental capital growth and inclusion of the socially responsible activities in the corporate strategy is another issue that is of special significance here. Besides, two basic forms of environmental management systems (environmental decision support systems and environmental information management systems) are explored and their role in effective stakeholder interaction is tackled. The most crucial benefits of EMS are also analyzed to underline its importance as a source of sustainable development. Further research is based on the survey of 51 sampled oil and gas companies (both publicly owned and state owned ones) originated from different countries all over the world and providing reports on sustainability issues in the open access. To analyze their approach to sustainable development, a specifically designed evaluation matrix with 37 indicators developed in accordance with the General Reporting Initiative (GRI) guidelines for non-financial reporting was prepared. Additionally, the quality of environmental information disclosure was measured on the basis of a quality – quantity matrix. According to results of research, oil and gas companies prefer implementing reactive measures to the costly and knowledge-intensive proactive techniques for elimination of the negative environmental impacts. Besides, it was identified that the environmental performance disclosure is mostly rather limited, so that the quality of non-financial reporting can be judged as quite insufficient. In spite of the fact that most of the oil and gas companies in the sample claim the EMS to be embedded currently in their structure, they often do not provide any details for the process of their implementation. As a potential for the further development of EMS, author mentions possible integration of their different forms in a single entity, extension of existing structure on the basis of consolidation of the structural and strategic precautions as well as development of a unified certification standard instead of several ones that exist today in order to enhance control on the EMS implementation.

Biopolttoaineen rinnakkaispolton kannattavuustarkastelu hiilipölypolttokattilassa Martinlaakso 2:ssa

Euroopan unionin asettamat tavoitteet kasvihuonepäästöjen vähennykselle johtavat vih-reämpään teknologiaan. Tämä diplomityö on teoreettinen tutkimus, joka käsittelee biopolt-toaineen rinnakkaispolton kannattavuutta Vantaan Energian Martinlaakso 2:sen hiilipöly-polttokattilassa. Työssä perehdytään viiteen eri biopolttoainevaihtoehtoon, joita tarkastellaan viidessä eri skenaariossa, jotka vastaavat: 10, 20, 30, 40 ja 50 % biopolttoaineen osuutta kattilassa tuo-tetusta energiasta. Skenaarioissa on pohdittu tarvittavia investointikustannuksia ja muutos-töitä hiilipölypolttokattilassa. Tutkimuksessa on huomioitu myös uusi isojen laitosten pääs-töjä koskeva direktiivi, kattilan oletettava käyttöikä sekä biopolttoaineiden tuet. Saaduista arvioista on lopuksi laskettu vuosittainen polttoainekohtainen kustannusarvio ja investoin-nin kannattavuusarvio. Tuloksista voidaan päätellä, että sahanpurun mahdollisimman suuri hyötykäyttö on kannat-tavaa. Mikäli halutaan käyttää suuria määriä biopolttoainetta, (yli 20 % tuotetusta energias-ta) ei sahanpuru ole varteenotettava vaihtoehto huonon saatavuutensa johdosta. Tällöin hakkeen kaasutuslaitos olisi paras ratkaisu, mutta laitoksen kannattavuus riippuu tulevista energiatuista. Ilman energiatukia sahanpurun hyötykäyttö on ainoa kannattava investointi.

Porous silicon optical filters in gas sensing applications

In this thesis, the gas sensing properties of porous silicon-based thin-film optical filters are explored. The effects of surface chemistry on the adsorption and desorption of various gases are studied in detail. Special emphasis is placed on investigating thermal carbonization as a stabilization method for optical sensing applications. Moreover, the possibility of utilizing the increased electrical conductivity of thermally carbonized porous silicon for implementing a multiparametric gas sensor, which would enable simultaneous monitoring of electrical and optical parameters, is investigated. In addition, different porous silicon-based optical filter-structures are prepared, and their properties in sensing applications are evaluated and compared. First and foremost, thermal carbonization is established as a viable method to stabilize porous silicon optical filters for chemical sensing applications. Furthermore, a multiparametric sensor, which can be used for increasing selectivity in gas sensing, is also demonstrated. Methods to improve spectral quality in multistopband mesoporous silicon rugate filters are studied, and structural effects to gas sorption kinetics are evaluated. Finally, the stability of thermally carbonized optical filters in basic environments is found to be superior in comparison to other surface chemistries currently available for porous silicon. The results presented in this thesis are of particular interest for developing novel reliable sensing systems based on porous silicon, e.g., label-free optical biosensors.

IT Investment Portfolio Management Over Joint Ventures: Case Study in a Multinational Oil & Gas Company

With information technology (IT) playing an increasing important role in driving the business, the value of IT investment is often challenged because not all of those investment decisions are made in a reasonable way or aligned with business strategies. IT investment portfolio management (PfM) is an effective way to prioritize and select the right IT projects to invest in, by taking all the project proposals into consideration as a whole, based on their business value, risks, costs, and interrelationships. There are different decision models to prioritise projects, and the Analytic Hierarchy Process (AHP) is one of the most commonly-used methods and is discussed in this master thesis. At the same time, there are IT projects on different levels for a multinational company, from global to local. For instance, many of them are probably proposed by joint ventures on local level. In the oil & gas industry, joint ventures are often formed especially in the area of the upstream (exploration & production). How to involve those projects into the IT investment PfM approach of the parent company is a challenge, because the parent company cannot make the decisions on its own. It needs to prioritize all projects in an adequate way, communicate with JVs and influence them. Also, different control levels on JVs need to be considered. This paper hence attempts to introduce a tailored approach of IT investment PfM for a multinational oil & gas company to address the issues around JVs.