Kattilatekniikat biopolttoaineille alle 5 MW teholuokassa

Tässä kandidaatintyössä on tarkoituksena kertoa mahdollisista eri biopolttoaineista ja niiden polttamiseen kehitetyistä kattilatekniikoista alle 5MW:n kokoluokassa. Eri kattilatyyppejä esitellään ja vertaillaan niiden toiminta-arvojen ja investointihintojen perusteella. Lisäksi työssä esitellään näiden kattilatyyppien kotimaisia polttokattilavalmistajia ja -myyjiä tarkastellun tehoalueen rajoissa. Työssä käsitellään vain pienitehoisia biopolttoainekattiloita, jolloin kattilaratkaisut rajoittuvat lähinnä arina- ja leijukerroskattiloihin. Kaasutuskattilat rajattiin työn ulkopuolelle työn rajatun laajuuden takia. Kaasutuskattiloilla on myös Suomessa vähän ja niiden tarjonta on pientä. Kattiloista on pyritty selvittämään niiden paineluokat ja tuotetun veden tai höyryn lämpötila. Kattilavalmistajilta kerättiin tietoa kyselyillä ja internetsivujen avulla. Valmistajien ja toimittajien halukkuus kertoa omista tuotteistaan vaihteli jonkin verran. Tämän takia myös tiedon määrä tuotteista vaihtelee yrityksien välillä.

Leijukattilan savukaasujen loppulämpötilan hallinta

Nykyaikaista leijukattilaa voidaan ohjata ja säätää erilaisten säätöpiirien ja sekvenssien kautta erittäin tarkasti. Toiminnot on optimoitu parhaan hyötysuhteen saavuttamiseksi ja kunnossapitokustannusten minimoimiseksi. Tehokkaasta automaatiosta ja nykyaikaisista laitevalinnoista huolimatta leijukattiloissa on usein yksi osa-alue, jota ei pystytä hallitsemaan tehokkaasti. Useilla voimalaitoksilla savukaasu poistuu liian korkeassa lämpötilassa viimeiseltä lämpöpinnalta. Kun kattilahyötysuhdetta tarkastellaan epäsuoralla menetelmällä, savukaasuhäviö on merkittävin tekijä kaikista häviöstä. Tässä diplomityössä on etsitty mahdollisuuksia savukaasun loppulämpötilan hallintaan kattilan ajoarvojen muutoksella sekä lämpöpintoja muuttamalla. Tutkimus keskittyy Järvi-Suomen Voima Oy:n Ristiinan voimalaitokselle. Tutkimus on tehty yhteistyössä laitoksen omistajien Pohjolan Voima Oy:n, UPM-Kymmene Oyj:n sekä laitetoimittaja Valmet Oyj:n kanssa.

Leijukerroslämmönsiirtimien tukkeutuminen biovoimalaitoksessa

Leijukerroslämmönsiirtimien, eli hiekanpalautuspolvessa sijaitsevien tulistimien tukkeutuminen on ollut Kaukaan Voima Oy:n biovoimalaitoksen suunnittelemattomien seisokkien suurin syy vuodesta 2012 lähtien. Tulistimet tukkeutuvat kahdella tavalla. Nopeassa tukkeutumisessa tulistinkammion seinien kuonakerrostumat romahtavat yhtäkkiä tulistimen päälle tukkien sen. Tämä johtaa aina koko laitoksen alasajoon. Hitaassa tukkeutumisessa tulistinputkien pinnalle muodostuu vähitellen kerrostuma sekä tulistinputkien väliin jää suurempia kappaleita, jotka tukkivat tulistinta. Nopea tukkeutuminen johtuu tuhkassa olevien alkali-, eli kalium- ja natriumyhdisteiden synnyttämistä kerrostumista lämmönsiirrinkammion seinille. Hidas tukkeutuminen johtuu osittain myös alkaliyhdisteistä, mutta merkittävämpi aine tulistinputkien pinnalla olevassa kerrostumissa näyttää olevan kalsiumsulfaatti, joka tukkii tulistinta. Palavan aineen pääsy tulistinkammioon ilmanjakoasetuksista ja tulistinkammion rakenteesta johtuen aiheuttaa kerrostumien syntymisen. Kerrostumien syntymiseen johtavat syyt johtuvat monesta tekijästä ja yksiselitteistä aiheuttajaa on vaikea määritellä. Selvin yhteys on lietteen epätasaisessa poltossa ja turpeen käytössä. Nykyisillä lietteenkäsittelylaitteilla lietteen tasainen syöttö on vaikeaa ja se aiheuttaa ongelmia. Turpeen poltto biopolttoaineiden rinnalla pitää tulistimet puhtaampina. Muita todennäköisiä kerrostumia lisääviä syitä ovat puhtaan hiekan vähäinen syöttömäärä ja usean huonomman polttoaineen yhtäaikainen poltto.

Effect of drying method on the adsorption isotherms and isosteric heat of passion fruit pulp powder

The sorption behavior of dry products is generally affected by the drying method. The sorption isotherms are useful to determine and compare thermodynamic properties of passion fruit pulp powder processed by different drying methods. The objective of this study is to analyze the effects of different drying methods on the sorption properties of passion fruit pulp powder. Passion fruit pulp powder was dehydrated using different dryers: vacuum, spray dryer, vibro-fluidized, and freeze dryer. The moisture equilibrium data of Passion Fruit Pulp (PFP) powders with 55% of maltodextrin (MD) were determined at 20, 30, 40 and 50 ºC. The behavior of the curves was type III, according to Brunauer's classification, and the GAB model was fitted to the experimental equilibrium data. The equilibrium moisture contents of the samples were little affected by temperature variation. The spray dryer provides a dry product with higher adsorption capacity than that of the other methods. The vibro-fluidized bed drying showed higher adsorption capacity than that of vacuum and freeze drying. The vacuum and freeze drying presented the same adsorption capacity. The isosteric heats of sorption were found to decrease with increasing moisture content. Considering the effect of drying methods, the highest isosteric heat of sorption was observed for powders produced by spray drying, whereas powders obtained by vacuum and freeze drying showed the lowest isosteric heats of sorption.

Kiertoleijupetikattilateknologia ja sen matemaattinen mallinnus energiantuotantoprosessissa

Työn teoreettisessa osuudessa tehdään katsaus kiertoleijupetiteknologian eri osa-alueisiin: leijupedin virtausdynamiikkaan, hiukkaserottimeen ja kiintoaineen palautusmekanismiin. Myös teknologian historiaa ja muita käyttötarkoituksia energiantuotannon ohella käydään läpi. Termodynamiikkaa sekä lämmönsiirron ja voimalaitosprosessien teoriaa käsitellään mallinnuksessa tarvittavilta osin. Mallinnusosiossa käydään läpi kiertoleijupetihöyrykattilan matemaattisen mallin tekoprosessia. Malli perustuu yleisesti saatavilla oleviin yhtälöihin ja korrelaatioihin. Mallintaminen koostuu höyrykattilan jakamisesta lämpöpintoihin ja niiden mitoittamisesta. Mallissa esitetään myös näkemys siitä, miten lämpö siirtyy savukaasuun ja miten petimateriaalin kierto tapahtuu tulipesässä.

Vigor and field emergence in "high oleic" sunflower seeds, in southeast of Buenos Aires province

Sunflower crop was based, as yet, on high linoleic cultivars, but in the last years request for oil with higher content of oleic acid has increased, due to their dietary characteristics. At the beginning, high oleic cultivars were used to be sown in warm regions, but then the concern about growing it in temperate areas, as the south-east of Buenos Aires Province, was posed. In this region, early sowings are recommended, so that grain filling matches with a period of appropriate hydric and light conditions, as to result in greater yields. However, early sowings are limited by low soil temperature, that delays seedling emergence, resulting in heterogeneous stand establishment. The aim of this work was to evaluate seed performance of four high oleic cultivars in the southern area of Buenos Aires Province, by means of vigor tests and field trials. Germination, cold, tetrazolium viability, tetrazolium viability with cold, accelerated ageing tests and three field sowings at different soil temperatures were performed. Data were analyzed by Anova using generalised linear models, and tests and cultivars were contrasted among themselves. Similar seedling emergence under optimal and suboptimal temperatures for high oleic and high linoleic cultivars was recorded. The success of seedling establishment does not appear to be related to the acidic composition of seeds.

Production of magnesium carbonates from serpentinites for CO2 mineral sequestration : optimisation towards industrial application

Global warming is one of the most alarming problems of this century. Initial scepticism concerning its validity is currently dwarfed by the intensification of extreme weather events whilst the gradual arising level of anthropogenic CO2 is pointed out as its main driver. Most of the greenhouse gas (GHG) emissions come from large point sources (heat and power production and industrial processes) and the continued use of fossil fuels requires quick and effective measures to meet the world’s energy demand whilst (at least) stabilizing CO2 atmospheric levels. The framework known as Carbon Capture and Storage (CCS) – or Carbon Capture Utilization and Storage (CCUS) – comprises a portfolio of technologies applicable to large‐scale GHG sources for preventing CO2 from entering the atmosphere. Amongst them, CO2 capture and mineralisation (CCM) presents the highest potential for CO2 sequestration as the predicted carbon storage capacity (as mineral carbonates) far exceeds the estimated levels of the worldwide identified fossil fuel reserves. The work presented in this thesis aims at taking a step forward to the deployment of an energy/cost effective process for simultaneous capture and storage of CO2 in the form of thermodynamically stable and environmentally friendly solid carbonates. R&D work on the process considered here began in 2007 at Åbo Akademi University in Finland. It involves the processing of magnesium silicate minerals with recyclable ammonium salts for extraction of magnesium at ambient pressure and 400‐440⁰C, followed by aqueous precipitation of magnesium in the form of hydroxide, Mg(OH)2, and finally Mg(OH)2 carbonation in a pressurised fluidized bed reactor at ~510⁰C and ~20 bar PCO2 to produce high purity MgCO3. Rock material taken from the Hitura nickel mine, Finland, and serpentinite collected from Bragança, Portugal, were tested for magnesium extraction with both ammonium sulphate and bisulphate (AS and ABS) for determination of optimal operation parameters, primarily: reaction time, reactor type and presence of moisture. Typical efficiencies range from 50 to 80% of magnesium extraction at 350‐450⁰C. In general ABS performs better than AS showing comparable efficiencies at lower temperature and reaction times. The best experimental results so far obtained include 80% magnesium extraction with ABS at 450⁰C in a laboratory scale rotary kiln and 70% Mg(OH)2 carbonation in the PFB at 500⁰C, 20 bar CO2 pressure for 15 minutes. The extraction reaction with ammonium salts is not at all selective towards magnesium. Other elements like iron, nickel, chromium, copper, etc., are also co‐extracted. Their separation, recovery and valorisation are addressed as well and found to be of great importance. The assessment of the exergetic performance of the process was carried out using Aspen Plus® software and pinch analysis technology. The choice of fluxing agent and its recovery method have a decisive sway in the performance of the process: AS is recovered by crystallisation and in general the whole process requires more exergy (2.48–5.09 GJ/tCO2sequestered) than ABS (2.48–4.47 GJ/tCO2sequestered) when ABS is recovered by thermal decomposition. However, the corrosive nature of molten ABS and operational problems inherent to thermal regeneration of ABS prohibit this route. Regeneration of ABS through addition of H2SO4 to AS (followed by crystallisation) results in an overall negative exergy balance (mainly at the expense of low grade heat) but will flood the system with sulphates. Although the ÅA route is still energy intensive, its performance is comparable to conventional CO2 capture methods using alkanolamine solvents. An energy‐neutral process is dependent on the availability and quality of nearby waste heat and economic viability might be achieved with: magnesium extraction and carbonation levels ≥ 90%, the processing of CO2‐containing flue gases (eliminating the expensive capture step) and production of marketable products.

Puu- ja turvetuhkan hyötykäyttökelpoisuuteen vaikuttavat tekijät pienillä polttolaitoksilla

Energiantuotannossa syntyvä tuhka voi olla laadultaan hyvin vaihtelevaa ja laadunvaihtelulle on haastavaa löytää yksiselitteistä syy-seuraussuhdetta. Ympäristönsuojelulainsäädäntö ja taloudelliset intressit ohjaavat tuhkantuottajia etsimään tuhkalle sopivia hyötykäyttökohteita, ja sen vuoksi tuhkan laatuun ja hyötykäyttökelpoisuuteen vaikuttavia tekijöitä on tarpeen selvittää. Tässä diplomityössä on tutkittu pienissä, alle 50 MW:n polttolaitoksissa syntyvää tuhkaa. Tavoitteena oli selvittää, kuinka tuhkan hyötykäyttökelpoisuuteen voidaan vaikuttaa. Tutkimuksen kohteena oli polttoainekoostumuksen, poltto-olosuhteiden ja tuhkan jälkikäsittelyn vaikutus tuhkassa olevien haitta-aineiden pitoisuuksiin ja liukoisuuksin. Työhön sisältyi myös aiemmin tehtyjen tuhka-analyysien tarkastelu sekä tuhkakokeet kahdella kohderyhmään kuuluvalla laitoksella. Työssä todettiin lentotuhkan haitta-ainepitoisuuksien ja -liukoisuuksien olevan keskimäärin korkeampia kuin pohjatuhkan vastaavien, ja että tyypillisesti arinakattilan tuhkien haitta-aineet ylittävät useammin hyötykäyttökelpoisuuden raja-arvoja kuin kuplaleijupetikattilan tuhkien. Lisäksi havaittiin metsätähdehaketuhkan kelpaavan useammin hyötykäyttöön kuin rankahaketuhkan.

Quantitative characteristics of fruits and seeds of Pouteria pachycarpa Pires - Sapotaceae

Pouteria pachycarpa is a tree species, found in the Brazilian Amazon and Bolivia whose wood has been exploited from the native forest. The present research describes the quantitative characteristics of fruits and seeds and quantifies the seed germination of this species. The fruit and seed color were characterized and measurements taken of the mass, length, diameter and number of seeds per fruit, the seed length, width and thickness, the germination percentage, abnormal seedlings and dead seeds. Sowing was carried out on a substrate containing sand and sawdust (1:1), in four replications of 50 seeds. The predominant fruit and seed colors were vivid yellowish orange (9YR) and dark grayish brown (6YR), respectively. Fruit mass, length and diameter ranged from 37.7 to 192.4g, 41.3 to 87.3mm and 39.7 to 71.7mm, respectively. Fruits had from two to seven seeds, and 42.6% were damaged by insects. Seed length, width and thickness ranged from 22.4 to 35.2mm, 9.7 to 15.5mm and 5.5 to 10.8mm, respectively. Seedling emergence began 18 days after sowing. Maximum germination, 86%, was recorded 33 days after sowing. The germination curve was sigmoid, similar to the majority of species. The percentage of abnormal seedlings and dead seeds were 3% and 11%, respectively. Both fruits and seeds show great variation in quantitative characteristics and the germination is slow and non-uniform.

Methods of overcoming dormancy in Schizolobium amazonicum Huber ex Ducke (Leguminosae - Caesalpinioideae) seeds

Seed dormancy is a frequent phenomenon in tropical species, causing slow and non-uniform germination. To overcome this, treatments such as scarification on abrasive surface and hot water are efficient. The objective of this study was to quantify seed germination with no treatment (Experiment 1) and identify an efficient method of breaking dormancy in Schizolobium amazonicum Huber ex Ducke seeds (Experiment 2). The effects of manual scarification on electric emery, water at 80ºC and 100ºC and manual scarification on wood sandpaper were studied. Seeds were sown either immediately after scarification or after immersion in water for 24h in a sand and sawdust mixture. Germination and hard seed percentages and germination speed were recorded and analyzed in a completely randomized design. Analysis of germination was carried out at six, nine, 12, 15, 18, 21 and 24 days after sowing as a 4x2 factorial design and through regression analysis. Treatment means of the remaining variables were compared by the Tukey test. Seed germination with no treatment started on the 7th day after sowing and reached 90% on the 2310th day (Experiment 1). Significant interaction between treatments to overcome dormancy and time of immersion in water was observed (Experiment 2). In general, immersion in water increased the germination in most evaluations. The regression analyses were significant for all treatments with exception of the control treatment and immersion in water at 80ºC. Germination speed was higher when seeds were scarified on an abrasive surface (emery and sandpaper) and, in these treatments, the germination ranged from 87% to 96%, with no hard seeds. S. amazonicum seeds coats are impermeable to water, which hinders quick and uniform germination. Scarification on electric emery followed by immediate sowing, scarification on sandpaper followed by immediate sowing and sowing after 24h were the most efficient treatments for overcoming dormancy in S. amazonicum seeds.

Seed anatomy and germination of Phoenix roebelenii O'Brien (Arecaceae)

The objective of this study was to investigate the morphology, anatomy and germination behaviour of Phoenix roebelenii seeds. Biometric data were obtained by measuring 100 seeds extracted from recently harvested fruits and air-dried for one day. Four replications of 50 seeds each were previously treated with Vitavax-Thiran and then put to germinate in Sphagnum sp. in plastic trays at room temperature. Morphological details of the seeds were documented with the help of a scanning electronic microscope and then drawings were made with the help of a clear camera coupled to a stereomicroscope. Permanent lamina containing embryo sections were prepared to study its anatomy. The mean dimensions of the seeds were: length of 10.32mm, width of 5.21mm and thickness of 3.91mm. The weight of one thousand seeds was of 151.1g and the mean number of units.kg-1 was 6,600. Germination started between 27 and 58 days after sowing. The seeds are of the albuminous type, the endosperm is hard and the embryo (which is not clearly differentiated) occupies a lateral and peripheral position. During seed germination, seedling protrusion begins with the opening of an operculum, through which the cotyledon petiole is emitted with the embryonic axis at its tip. The portion of the cotyledon petiole that remains inside the seeds acts as a haustorium for the absorption of nutrients from the endosperm. The plumule emerges through a rift in the posterior part of the cotyledon. Secondary roots are observed to grow from the anterior part of the primary root.

Influence of disinfestation and osmotic conditioning on the germinating behavior of australian royal palm (Archontophoenix alexandrae)seeds

The technique of Osmotic Conditioning, which consists of partial and controlled hydration of the seeds, has obtained success with various species of seeds, increasing the germinating span and tolerance to the adverse conditions of the environment, and has also reduced the time elapsed between sowing and the emergence of the plants. Associated to ideal storage conditions, the treatment has increased the performance of the seeds of tropical wood species. Aiming at studying the germinating environment and the effect of osmotic conditioning on the germination of seeds of the Australian Royal Palm tree, two experiments were performed. The first one evaluated the effect of disinfestation of the seeds of the Australian Royal Palm tree with NaClO. The treatments applied were: 0.5% sodium hypochlorite, exposure periods of 5, 15, 30, 45, 60, 90, 120 and 240 minutes, and the fungicide Captan, as control. The treatments with NaClO did not differ in relation to the final percentage of germination and to the germination speed index, and did not differ from the treatment control. The second test evaluated solutions with the following osmotic potentials: 0.0MPa (pure water), -0.4MPa, -0.6MPa and -0.8MPa, exposed for the periods of 10 and 20 days. The final percentage of germination did not differ among the treatments. The seeds hydrated in pure water for a period of 20 days showed a germination speed index significantly superior to the other treatments, and they did not show significant differences among themselves.

Germination, initial growth and cotyledon protein content of bean cultivars under salinity stress

Excess salts in the root zone inhibit water uptake by plants, affect nutrient uptake and may result in toxicities due to individual salts in the soil solution. Excess exchangeable sodium in the soil may destroy the soil structure to a point where water penetration and root aeration become impossible. Sodium is also toxic to many plants. Beans (Phaseolus vulgaris L.) are consumed as protein source in northeastern Brazil, although little is known about common bean cultivar tolerance to salinity. The germination of bean cultivars under salt stress was studied. The cultivars 'Carioca' and 'Mulatinho' were submitted to germination test in a germinator at 25ºC, at the Seed Analysis Laboratory of the Brazilian Agricultural Research Corporation unit in the Semi- Arid region (Embrapa Semi Árido), Petrolina, Pernambuco State. These seeds were germinated on "germitest" papers imbibed in distilled water or in 10, 50, 100 e 200 mol.m-3sodium chloride (NaCl) solutions. At the first and second counts of the germination test, normal seedlings were counted, measured, weighed and dried, supplying data for vigor, total germination, fresh matter weight and dry matter weight and seedlings length. Total protein was quantified in cotyledons at 3, 6 and 9 days after sowing. The results indicated that the NaCl content influenced seed germination and concentrations above 50 mol.m-3 decreased germination and seedling growth.

Drying and germination of cupuassu (Theobroma grandiflorum (willd. Ex Spreng.) K. Schum.) seeds

The objective of this study was to verify the effect of drying on germination of cupuassu (Theobroma grandiflorum (Willd. ex Spreng) K. Schum.) seeds. Desiccation was in forced air oven, with temperature ranging from 23 to 33ºC. Sowing was carried out at 0.5cm of depth in plastic trays in sand and sawdust mixture (1:1), previously sterilized in hot water (100ºC), during 2h. Seeds were left to germinate in a laboratory with no temperature and relative humidity control, under natural light. It was quantified the seed moisture content, in four replications of 10 seeds; the germination percentage, performed during 30 days, with daily counts of the number of germinated seeds; the germination speed index; and number of days to the germination onset. The experimental design was completely randomized with four replications of 25 seeds. The reduction of moisture content from 58.6 to 37.8% did not affect seed germination and germination speed index; however, they were affected when moisture content was reduced to values below 30.7%. It was observed that only when moisture content was 16.1% seeds demanded more days to begin germination. Cupuassu seeds are classified as recalcitrant and they can be desiccated up to 37.8% with no reduction on germination.