Pienitehoisen CHP-laitoksen verkkoonliityntä

Työn tavoitteena on pienitehoisen CHP-laitoksen verkkoonliitynnän suunnittelu. Laitos polttaa Einco Oy:n CFB-kuivurissa (Circulating fluidized-bed) termisesti kuivattua lietettä hönkäkaasujen kanssa Einco Oy:n CTC-reaktorissa (Constant temperature combustion). CFB-kuivuri ja CTC-reaktori on kytketty höyryvoimalaitosprosessiin, jonka turbogeneraattorista saadaan sähköenergiaa. Työssä on tutkittu nykypäivän hajautetun tuotannon pienvoimalaitoksen verkkoonliitynnän suojausvaatimuksia, sähkönlaatuvaatimuksia, suosituksia ja mahdollisen verkonhaltijan ohjeita sekä generaattorilaitteistojen ominaisuuksia. Generaattorilaitteistot ovat vierasmagnetoitu tahtigeneraattori tai itsemagnetoitu tahtigeneraattori, kestomagneettitahtigeneraattori tai verkkomagnetoitu epätahtigeneraattori. Lisäksi on tarkasteltu ja vertailtu generaattorilaitteistojen verkkoonliitynnässä tarvittavien eri automaatiolaitteiden ominaisuuksia. Verkkoonliitynnät on suunniteltu 400 kW generaattorilaitteistovaihtoehdoille kahdella tavalla: suoraan verkkoon kytkettynä ja taajuusmuuttajalla verkkoon kytkettynä. Työn päätuloksia ovat suunnitellut sähköliittymät sekä suojaus- ja ohjauspiirit, ensiö- ja toisiosuojaukset, toteutustason piirustukset ja automaation toimintaselostus. Lisäksi suunnitelluille automaatiokokoonpanoille on laskettu hankintakustannukset. Taajuusmuuttajan avulla verkkoon kytketty suoravetoturbogeneraattori on todettu teknisesti ja taloudellisesti toimivaksi.

Radiative Heat Transfer in Boiler Furnaces

Better models are needed for radiative heat transfer in boiler furnaces. If the process is known better, combustion in the furnace can be optimized to produce low emissions. It makes the process to be environmental friendly. Furthermore, if there is a better model of the furnace it can more fully explain what is happening inside the furnace. Using of the model one can quickly and easily analyze how it operates with bio fuels, moist fuels or difficult fuels and improve the operation. Models helps with better estimation of furnace dimensions and result in more accurate understanding of operation. Key component lacking in these models is radiative heat transfer in particle laden gases. If there are no particles than radiative heat transfer can be calculated approximately. There are two problems with current models when used with flow modeling. The first one is a need to account for a particle laden gas and the second one is an absence of a fast algorithm. Fast calculation is needed if radiative heat transfer calculation is done for a large CDF model. Computations slow down if time is required for calculating radiative properties over and over again. This thesis presents a band model for radiative heat transfer in boiler furnaces. Advantage is a quickness of calculation and account of particles in the process.

Calcination of aluminum hydroxide over pressure and residence time

This work investigates the possible effect of pressure and residence time to the reaction of aluminum hydroxide into aluminum oxide. Various pressurized conditions are used as well as the help of various residence times. The aim is to increase the conversion of the reaction with the use of different pressures and residence times. The tests were performed with a laboratory scale fluidized bed reactor at the Outotec R&D Center in Frankfurt. Additional test work such as particle size analysis and differential thermal analysis were also carried out. Some calcined samples were also characterized with X-ray diffraction at the University of Auckland to obtain a reaction pathway when using pressurized conditions. All of the results are then compared with previous results.

Kierrätyspolttoaineen käyttö leijupetikattilan konseptiin

Diplomityö tehtiin Rautjärven kunnassa sijaitsevalle M-real Simpeleen tehtaan voimalaitokselle. Voimalaitoksella on leijupetikattila ja se tuottaa prosessilämmön ja höyryn kartonki- ja paperikoneelle. Vuotuinen energiantuotanto on noin 115 GWh. Diplomityön tavoitteena oli tutkia kierrätyspolttoaineen käyttöä osana voimalaitoksen polttoainekonseptista. Voimalaitoksen biokattila on leijupetikattila, jossa poltetaan tehtaalta tulevaa kuorta ja lietettä sekä tehtaan ulkopuolisia puuperäisiä biopolttoaineita ja turvetta. Yksi työn päätavoitteista oli laatia voimassa olevan ympäristöluvan muutoshakemus, jotta kierrätyspolttoaineen käytölle saataisiin lupa. Suurten polttolaitosten päästöjen tarkkailu- ja raportointivaatimukset ovat uudistuneet viime vuosina paljon. Suurimpia muutosten aiheuttajia ovat Valtioneuvoston asetukset 1017/2002 ja 362/2003. Tässä työssä kuvataan uusien asetusten tuomia vaatimuksia itse kattilalle ja polttoaineen syötölle, jatkuvatoimisille mittalaitteille ja muille suoritettaville mittauksille. Uutena asiana on myös ilmapäästöjen seurantamittaukset ja -tapa, jolla tulokset ilmoitetaan. Mahdollisimman pieniin leijupetikattilamuutoksiin uskotaan pääsevän korvaamalla kierrätyspolttoaine REF1:llä 5 – 10 % turpeesta tai puupolttoaineista.

Model-based study of a chemical-looping combustion process

Chemical-looping combustion (CLC) is a novel combustion technology with inherent separation of the greenhouse gas CO2. The technique typically employs a dual fluidized bed system where a metal oxide is used as a solid oxygen carrier that transfers the oxygen from combustion air to the fuel. The oxygen carrier is looping between the air reactor, where it is oxidized by the air, and the fuel reactor, where it is reduced by the fuel. Hence, air is not mixed with the fuel, and outgoing CO2 does not become diluted by the nitrogen, which gives a possibility to collect the CO2 from the flue gases after the water vapor is condensed. CLC is being proposed as a promising and energy efficient carbon capture technology, since it can achieve both an increase in power station efficiency simultaneously with low energy penalty from the carbon capture. The outcome of a comprehensive literature study concerning the current status of CLC development is presented in this thesis. Also, a steady state model of the CLC process, based on the conservation equations of mass and energy, was developed. The model was used to determine the process conditions and to calculate the reactor dimensions of a 100 MWth CLC system with bunsenite (NiO) as oxygen carrier and methane (CH4) as fuel. This study has been made in Oxygen Carriers and Their Industrial Applications research project (2008 – 2011), funded by the Tekes – Functional Material program. I would like to acknowledge Tekes and participating companies for funding and all project partners for good and comfortable cooperation.

Kierrätyspolttoaineiden käyttö leijukerrospoltossa vetykaasun kanssa

Tämä diplomityö on tehty Leppäkosken Energia Oy:n ja Kemira Chemicals Oy:n yhteisyritys FC Energia Oy:lle. FC Energia Oy suunnittelee rakentaa uutta bio-vetyvoimalaitosta Sastamalaan. Voimalaitoksella tuotettaisiin Kemira Chemicals Oy:n ylijäämävedystä ja biopolttoaineista sähköä, kaukolämpöä ja prosessihöyryä. Ympäristölupaa on haettu hakkeen, turpeen ja kierrätyspuun poltolle vetykaasun kanssa. Voimalaitoksen kattilan toiminta perustuu kuplivaan leijukerrostekniikkaan. Diplomityössä selvitettiin, mitä muutoksia kierrätyspolttoaineiden käyttö vaatii leijukerrospoltossa verrattuna hakkeen ja turpeen polttoon. Kierrätyspolttoaineena käytetään hyvälaatuista kierrätyspuuta. Kierrätyspuun käytössä sovelletaan jätteenpoltto-asetusta. Jätteenpolttoasetus määrää tiukemmat päästöjen raja-arvot rinnakkaispoltolle kuin hakkeen ja turpeen poltolle sekä jatkuvatoimiset savukaasujen mittauslaitteet. Rinnakkaispolton hiukkasmaisten päästöjen tiukempi raja-arvo vaatii tehokkaamman sähkösuodattimen. Lisäksi kierrätyspuuta käytettäessä tulistimen materiaaliin tulee olla kestävämpää, mikä aiheuttaa huomattavan lisäinvestoinnin. Työn päätavoitteena oli selvittää, onko kierrätyspuun käyttö taloudellisesti kannattavaa. Oletetulla kierrätyspuun hinnalla 10 €/MWh kierrätyspuuta polttavan voimalaitoksen takaisinmaksuaika on sama kuin haketta polttavan laitoksen ja vuoden lyhyempi kuin turvetta polttavan laitoksen. Tulokseksi saatiin, että rinnakkaispoltto käyttö on taloudellisesti kannattavaa hakkeenpolttoon nähden jos kierrätyspuun hinta on alle 11,2 €/MWh. Kierrätyspuun polttoon liittyy toiminnallinen riski, koska vastaavanlaisia rinnakkaispolttolaitoksia ei ole aiemmin rakennettu.

Ruokohelven käytön lisääminen Joensuun voimalaitoksen kattilassa – käytettävyys, hyötysuhde ja taloudellisuus

Ruokohelpi soveltuu ympäristöystävällisyyden ja korkean lämpöarvon vuoksi hyvin energiantuotantoon. Fortumin Joensuun voimalaitoksella ruokohelpi on syötetty kattilaan tähän asti pääasiassa pääpolttoaineisiin, turpeeseen tai hakkeeseen seostettuna pieninä energiaosuuksina. Pääpolttoaineisiin verrattuna ruokohelvellä on alhaisempi irto- ja energiatiheys, korkeampi klooripitoisuus ja kattilaa likaavampi tuhka, mikä asettaa rajoitteita sen käytön lisäämiselle voimalaitoksella. Alhaisesta irto- ja energiatiheydestä johtuvan holvautumisen sekä tukoksien lisääntymisen ja Joensuun voimalaitoksen nykyisten kuljettimien kapasiteettiongelmien vuoksi ruokohelven osuuden lisääminen suuremmaksi kuin 5 % polttoaine-energiasisällöstä on riskialtista ja edellyttää täten investointia erilliseen ruokohelven käsittely- ja syöttöjärjestelmään. Yksi vaihtoehto on murskata ruokohelpipaalit joko sähkökäyttöisellä, puolikiinteällä ja nopeakäyntisellä Haybuster H1130 tilt -murskaimella tai kiinteällä ja hidaskäyntisellä Raumaster-murskaimella ja ohjata ruokohelpisilppu joko pitkän mekaanisen kuljettimen ja sen perässä olevien lyhyiden pneumalinjojen tai pelkkien pitkien pneumalinjojen kautta suoraan kattilapesään. Työssä tutkitut investoinnit ovat taloudellisesti sitä kannattavampia mitä enemmän ruokohelpeä voidaan vuositasolla polttaa voimalaitoksella. Ruokohelven käyttömäärää voimalaitoksella kannattanee lisätä kuljetusmatkaa pidentämällä. Investointien valinta ei ole itsestäänselvyys. Nopeakäyntinen murskain on hidaskäyntistä murskainta edullisempi investointi, tosin hidaskäyntisen murskaimen käyttövarmuus on parempi kuin nopeakäyntisen murskaimen. Kattilan käytettävyyden kannalta ruokohelven käytön lisääminen edellyttää kattilan palamistekniikan analysointia laskennallisesti virtausmallinnuksella ennen kuin lopullisia päätöksiä investointien suhteen voidaan tehdä.

A Development and Application of a Three-Dimensional Model for a CFB Gasifier

The developing energy markets and rising energy system costs have sparked the need to find new forms of energy production and increase the self-sufficiency of energy production. One alternative is gasification, whose principles have been known for decades, but it is only recently when the technology has become a true alternative. However, in order to meet the requirements of modern energy production methods, it is necessary to study the phenomenon thoroughly. In order to understand the gasification process better and optimize it from the viewpoint of ecology and energy efficiency, it is necessary to develop effective and reliable modeling tools for gasifiers. The main aims of this work have been to understand gasification as a process and furthermore to develop an existing three-dimensional circulating fluidized bed modeling tool for modeling of gasification. The model is applied to two gasification processes of 12 and 50 MWth. The results of modeling and measurements have been compared and subsequently reviewed. The work was done in co-operation with Lappeenranta University of Technology and Foster Wheeler Energia Oy.

Combustion properties of biomass residues rich in phosphorus

Tillgången på traditionella biobränslen är begränsad och därför behöver man ta fram nya, tidigare outnyttjade biobränslen för att möta de uppställda CO2 emissionsmålen av EU och det ständigt ökande energibehovet. Under de senare åren har intresset riktats mot termisk energiutvinning ur olika restfraktioner och avfall. Vid produktion av fordonsbränsle ur biomassa är den fasta restprodukten ofta den största procesströmmen i produktionsanläggningen. En riktig hantering av restprodukterna skulle göra produktionen mera lönsam och mer ekologiskt hållbar. Ett alternativ är att genom förbränning producera elektricitet och/eller värme eftersom dessa restprodukter anses som CO2-neutrala. Målsättningen med den här avhandlingen var att studera förbränningsegenskaperna hos några fasta restprodukter som uppstår vid framställning av förnybara fordonsbränslen. De fyra undersökta materialen är rapskaka, palmkärnskaka, torkad drank och stabiliserat rötslam. I studien används ett stort urval av undersökningsmetoder, från laboratorieskala till fullskalig förbränning, för att identifiera de huvudsakliga utmaningarna förknippade med förbränning av restprodukterna i pannor med fluidiserad bäddteknik. Med hjälp av detaljerad bränslekarakterisering kunde restprodukterna konstateras vara en värdefull källa för värme- och elproduktion. Den kemiska sammansättningen av restprodukterna varierar stort jämfört med mera traditionellt använda biobränslen. En gemensam faktor för alla de studerade restprodukterna är en hög fosforhalt. På grund av de låga fosforkoncentrationerna i de traditionella biobränslena har grundämnet hittills inte ansetts spela någon större roll i askkemin. Experimenten visade nu att fosfor inte mera kan försummas då man studerar kemin i förbränningsprocesser, då allt flera fosforrika bränslen tränger in på energimarknaden.

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

Modelling of calciner in post-combustion carbon capture process

Climate change has given an impetus to research and developed new technologies to reduce significantly carbon dioxide emissions in energy production in the developed countries. The major pollution source, fossil fuels, will be used as an energy source for many decades, which provides the demand for carbon capture and storage technologies. Over recent years many new technologies has been developed and one of the most promising is calcium-looping in post-combustion carbon capture process, which use carbonation-calcination cycle to capture carbon dioxide from the flue gas of a combustion process. First pilot plant for calcium-looping process has been built in Oviedo, Spain. In this study, a three-dimensional model has been created for the calciner, which is one of the two fluidized bed reactors needed for the process. The calciner is a regenerator where the captured carbon dioxide is removed from the calcium material and then collected after the reactor. Thesis concentrates in creating the calciner 3D-model frame with CFB3D-program and testing the model with two different example cases. Used input parameters and calciner geometry are Oviedo pilot plant design parameters. The calculation results give information about the process and show that pilot plant calciner should perform as planned. This Master’s Thesis is done in participation to EU FP7 project CaOling.

Production of Mg(OH)2 from Mg-silicate rock for CO2 mineral sequestration

Sequestration of carbon dioxide in mineral rocks, also known as CO2 Capture and Mineralization (CCM), is considered to have a huge potential in stabilizing anthropogenic CO2 emissions. One of the CCM routes is the ex situ indirect gas/sold carbonation of reactive materials, such as Mg(OH)2, produced from abundantly available Mg-silicate rocks. The gas/solid carbonation method is intensively researched at Åbo Akademi University (ÅAU ), Finland because it is energetically attractive and utilizes the exothermic chemistry of Mg(OH)2 carbonation. In this thesis, a method for producing Mg(OH)2 from Mg-silicate rocks for CCM was investigated, and the process efficiency, energy and environmental impact assessed. The Mg(OH)2 process studied here was first proposed in 2008 in a Master’s Thesis by the author. At that time the process was applied to only one Mg-silicate rock (Finnish serpentinite from the Hitura nickel mine site of Finn Nickel) and the optimum process conversions, energy and environmental performance were not known. Producing Mg(OH)2 from Mg-silicate rocks involves a two-staged process of Mg extraction and Mg(OH)2 precipitation. The first stage extracts Mg and other cations by reacting pulverized serpentinite or olivine rocks with ammonium sulfate (AS) salt at 400 - 550 oC (preferably < 450 oC). In the second stage, ammonia solution reacts with the cations (extracted from the first stage after they are leached in water) to form mainly FeOOH, high purity Mg(OH)2 and aqueous (dissolved) AS. The Mg(OH)2 process described here is closed loop in nature; gaseous ammonia and water vapour are produced from the extraction stage, recovered and used as reagent for the precipitation stage. The AS reagent is thereafter recovered after the precipitation stage. The Mg extraction stage, being the conversion-determining and the most energy-intensive step of the entire CCM process chain, received a prominent attention in this study. The extraction behavior and reactivity of different rocks types (serpentinite and olivine rocks) from different locations worldwide (Australia, Finland, Lithuania, Norway and Portugal) was tested. Also, parametric evaluation was carried out to determine the optimal reaction temperature, time and chemical reagent (AS). Effects of reactor types and configuration, mixing and scale-up possibilities were also studied. The Mg(OH)2 produced can be used to convert CO2 to thermodynamically stable and environmentally benign magnesium carbonate. Therefore, the process energy and life cycle environmental performance of the ÅAU CCM technique that first produces Mg(OH)2 and the carbonates in a pressurized fluidized bed (FB) were assessed. The life cycle energy and environmental assessment approach applied in this thesis is motivated by the fact that the CCM technology should in itself offer a solution to what is both an energy and environmental problem. Results obtained in this study show that different Mg-silicate rocks react differently; olivine rocks being far less reactive than serpentinite rocks. In summary, the reactivity of Mg-silicate rocks is a function of both the chemical and physical properties of rocks. Reaction temperature and time remain important parameters to consider in process design and operation. Heat transfer properties of the reactor determine the temperature at which maximum Mg extraction is obtained. Also, an increase in reaction temperature leads to an increase in the extent of extraction, reaching a maximum yield at different temperatures depending on the reaction time. Process energy requirement for producing Mg(OH)2 from a hypothetical case of an iron-free serpentine rock is 3.62 GJ/t-CO2. This value can increase by 16 - 68% depending on the type of iron compound (FeO, Fe2O3 or Fe3O4) in the mineral. This suggests that the benefit from the potential use of FeOOH as an iron ore feedstock in iron and steelmaking should be determined by considering the energy, cost and emissions associated with the FeOOH by-product. AS recovery through crystallization is the second most energy intensive unit operation after the extraction reaction. However, the choice of mechanical vapor recompression (MVR) over the “simple evaporation” crystallization method has a potential energy savings of 15.2 GJ/t-CO2 (84 % savings). Integrating the Mg(OH)2 production method and the gas/solid carbonation process could provide up to an 25% energy offset to the CCM process energy requirements. Life cycle inventory assessment (LCIA) results show that for every ton of CO2 mineralized, the ÅAU CCM process avoids 430 - 480 kg CO2. The Mg(OH)2 process studied in this thesis has many promising features. Even at the current high energy and environmental burden, producing Mg(OH)2 from Mg-silicates can play a significant role in advancing CCM processes. However, dedicated future research and development (R&D) have potential to significantly improve the Mg(OH)2 process performance.

Utilization of non ferrous metals in boiler combustion environment

The made research is focused on possibility of application of non ferrous metals in boiler pressure parts as a substitute of currently used ferrous-base alloys. The main issue was to define resistive ability of some perspective non ferrous metals to chlorine induced corrosion. Experimental study was performed using simultaneous thermal analysis (STA) in the temperature range of 400-700 °C. The chloride induced corrosion was simulated by mixtures of metal samples with potassium chloride treated by synthetic air. The advantage of synergetic effect of non ferrous alloys compare to single metals is shown due to the obtained data from conducted thermal balance tests.

Current status of the waste-to-energy chain in the County of North Savo, Finland

The aim of this report is to describe the current status of the waste-to-energy chain in the province of Northern Savonia in Finland. This work is part of the Baltic Sea Region Programme project Remowe-Regional Mobilizing of Sustainable Waste-to-Energy Production (2009-2012). Partnering regions across Baltic Sea countries have parallelly investigated the current status, bottle-necks and needs for development in their regions. Information about the current status is crucial for the further work within the Remowe project, e.g. in investigating the possible future status in target regions. Ultimate result from the Northern Savonia point of view will be a regional model which utilizes all available information and facilitates decision-making concerning energy utilization of waste. The report contains information on among others: - waste management system (sources, amounts, infrastructure) - energy system (use, supply, infrastructure) - administrative structure and legislation - actors and stakeholders in the waste-to-energy field, including interest and development ideas The current status of the regions will be compared in a separate Remowe report, with the focus on finding best practices that could be transferred among the regions. In this report, the current status has been defined as 2006-2009. In 2009, the municipal waste amount per capita was 479 kg/inhabitant in Finland. Industrial waste amounted 3550 kg/inhabitant, respectively. The potential bioenergy from biodegradable waste amounts 1 MWh/inhabitant in Northern Savonia. This figure includes animal manure, crops that would be suitable for energy use, sludge from municipal sewage treatment plants and separately collected biowaste. A key strategy influencing also to Remowe work is the waste plan for Eastern Finland. Currently there operate two digestion plants in Northern Savonia: Lehtoniemi municipal sewage treatment sludge digestion plant of Kuopion Vesi and the farm-scale research biogas plant of Agrifood Research Finland in Maaninka. Moreover, landfill gas is collected to energy use from Heinälamminrinne waste management centre and Silmäsuo closed landfill site, both belonging to Jätekukko Oy. Currently there is no thermal utilization of waste in Northern Savonia region. However, Jätekukko Oy is pretreating mixed waste and delivering refuse derived fuel (RDF) to Southern Finland to combustion. There is a strong willingness among seven regional waste management companies in Eastern Finland to build a waste incineration plant to Riikinneva waste management centre near city of Varkaus. The plant would use circulating fluidized bed (CFB) boiler. This would been a clear boost in waste-to-energy utilization in Northern Savonia and in many surrounding regions.