Browsing by Author "Vakkilainen, Esa"
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- Biomass conversion for energy purposes in large scale
School of Engineering | Master's thesis(2012) Kuparinen, KatjaBiomass use for energy purposes and fossil fuel replacement are recommendable measures because of environmental reasons and diversification of sources of energy. Biomass conversion extends the utilization possibilities of biomass and makes it easier to transport. Biomass can be converted by various methods to liquid, gaseous and solid biofuels. Biofuels can be used in heat and power production, as traffic fuels or they can be refined further to chemical products. Biomass is available almost around the world, but it is however a locally limited resource. Therefore large scale facilities often need to supply feedstock from a distance, even from foreign countries. In this study biomass use and conversion in large scale is examined. The target of the study is to find out and list the countries that use most biomass in industrial and transportation sectors. The aim is also to find out and list the largest plants converting biomass to energy products, and the origin of their feedstock. Most part of biomass use for energy purposes is residential use for heating and cooking in developing countries. The use in industrial and transportation sectors is mainly in industrialized countries. Biomass conversion in large scale is primarily located in industrialized countries. Most part of global ethanol production is located in the US and Brazil, whereas many large biodiesel plants locate in Europe. Wood pellets are produced mainly in North America and Europe, where woody biomass is plenty available. Gasification, torrefaction and pyrolysis technologies are still rarely used in industrial scale. Biomass transportation increases, but so far only a few large scale plants use imported feedstock apart from biodiesel plants. The products instead are traded, wood pellets especially from North America to Europe, biodiesel across the borders in Europe and ethanol mainly from Brazil across the world. - Mustalipeän polttomenetelmät Suomen soodakattiloissa
Helsinki University of Technology | Master's thesis(2004) Juvonen, TuukkaThe purpose of this work was to map the black liquor combustion practices in the kraft recovery boilers that are in operation at Finnish kraft pulp mills. Also an aim was to discover the unifying and the separating factors of the combustion methods by comparing liquor spray and combustion air feed parameters of different boilers. Data was collected from 14 recovery boilers that are located at 11 kraft pulp mills in Finland. The nominal furnace loadings, the emissions and the reduction efficiencies of these boilers were also studied. The nominal furnace loading was observed to be much higher in new and large boilers, than in old and small boilers. The furnace loading was also observed to increase with increasing specific furnace height and liquor dry solids content. The sulfur dioxide emissions are very low in all the boilers and there was not any specific factor that seemed to affect them. The nitrogen oxide emissions were observed to increase with increasing black liquor dry solids content. Black liquor combustion is very similar in all the recovery boilers studied. The dry solids content of the black liquor seemed to have the greatest effect on all the firing parameters. Stationary firing and splash plate nozzles are used in every boiler. The geometry of the nozzles and the liquor gun height vary, depending mainly on the boiler manufacturer. The liquor gun size was observed to increase with increasing boiler size and capacity. Also an increase in the dry solids content of the liquor seemed to increase the gun size. In all boilers the liquor firing temperature is much higher than the liquor boiling point, hence flashing occurs at the nozzles. The liquor firing pressures vary, but in large boilers the pressures are usually lower than in small boilers. The air feed models of the boilers are very similar when the liquor dry solids contents are similar. The proportion of the primary air was observed to decrease with increasing liquor dry solids. Also the reduction efficiency increased with decreasing primary air proportion. Because of differences in the air systems, there is a lot of variation especially in the secondary and tertiary air inlet velocities. - Development and Application of eLearning Software for Education in Energy Technologies
Helsinki University of Technology | Master's thesis(2002) Teir, Sebastian - Effect of biomass-based carbon capture on the sustainability and economics of pulp and paper production in the Nordic mills
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-01) Kuparinen, Katja; Lipiäinen, Satu; Vakkilainen, Esa; Laukkanen, TimoBioenergy with carbon capture and storage (BECCS) is one of the key negative emission technologies (NETs). Large-scale implementation of BECCS has been criticized of the associated increase in land use. The existing large Nordic pulp and paper production units enable BECCS deployment without additional land use, as they currently release large amounts of bio-based carbon dioxide (CO2). The application of BECCS in pulp mills has been found technically feasible in earlier studies. This study explores key factors that affect the propensity to invest in BECCS in different types of existing European pulp and paper mills. The results give fresh understanding on the effects of BECCS on the market price of pulp and paper products and the required level of incentives. Based on statistical data, the marginal carbon dioxide credit (€ per ton CO2) to make BECCS profitable was derived. The results show that the required level of credit greatly depends on the mill type and details and that the feasibility of BECCS does not clearly correlate with the economic performance or the measured efficiency of the mill. The most promising mill type, a market kraft pulp mill, would find BECCS profitable with a credit in the range of 62–70 €/tCO2 and a credit of 80 €/tCO2 would decrease pulp production costs by 15 €/tproduct on average if 50% of CO2 emissions was captured. The EU Emission Trading System (ETS) is the main policy instrument to achieve the climate targets related to fossil energy use, but does not yet contemplate bio-based emissions. - Energy Efficiency Analysis of the Refining Unit in Thermo-Mechanical Pulp Mill
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-03-17) Talebjedi, Behnam; Laukkanen, Timo; Holmberg, Henrik; Vakkilainen, Esa; Syri, SannaA refining model is developed to analyses the refining process's energy efficiency based on the refining variables. A simulation model is obtained for longer-term refining energy analysis by further developing the MATLAB Thermo-Mechanical Pulping Simulink toolbox. This model is utilized to predict two essential variables for refining energy efficiency calculation: refining motor-load and generated steam. The conventional variable for presenting refining energy efficiency is refining specific energy consumption (RSEC), which is the ratio of the refining motor load to throughput and does not consider the share of recovered energy from the refining produced steam. In this study, a new variable, corrected refining specific energy consumption (CRSEC), is introduced and practiced for better representation of the refining energy efficiency. In the calculation process of the CRSEC, recovered energy from the refining generated steam is considered useful energy. The developed model results in 160% and 78.75% improvement in simulation model determination coefficient and error, respectively. Utilizing the developed model and hourly district heating demand for CRSEC calculation, results prove a 22% annual average difference between CRSEC and RSEC. Findings confirm that the wintertime refining energy efficiency is 27% higher due to higher recovered energy in the heat recovery unit compared to summertime. - Energy modeling of a refiner in thermo-mechanical pulping process using ANFIS method
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-10-01) Talebjedi, Behnam; Khosravi, Ali; Laukkanen, Timo; Holmberg, Henrik; Vakkilainen, Esa; Syri, SannaIn the pulping industry, thermo-mechanical pulping (TMP) as a subdivision of the refiner-based mechanical pulping is one of the most energy-intensive processes where the core of the process is attributed to the refining process. In this study, to simulate the refining unit of the TMP process under different operational states, the idea of machine learning algorithms is employed. Complicated processes and prediction problems could be simulated and solved by utilizing artificial intelligence methods inspired by the pattern of brain learning. In this research, six evolutionary optimization algorithms are employed to be joined with the adaptive neuro-fuzzy inference system (ANFIS) to increase the refining simulation accuracy. The applied optimization algorithms are particle swarm optimization algorithm (PSO), differential evolution (DE), biogeography-based optimization algorithm (BBO), genetic algorithm (GA), ant colony (ACO), and teaching learning-based optimization algorithm (TLBO). The simulation predictor variables are site ambient temperature, refining dilution water, refining plate gap, and chip transfer screw speed, while the model outputs are refining motor load and generated steam. Findings confirm the superiority of the PSO algorithm concerning model performance comparing to the other evolutionary algorithms for optimizing ANFIS method parameters, which are utilized for simulating a refiner unit in the TMP process. - Energy Utilisation in Kraft Pulp Mills
Helsinki University of Technology | Master's thesis(2007) Nieminen, MarkusIn recent years, the operating environment of the pulp and paper industry has become more challenging because of uncertainties regarding the price and availability of energy. Energy provides a considerable potential to reduce operational costs. There are basically three ways to improve the energy efficiency of a pulp mill; by decreasing the energy consumption of pulping processes, increasing the energy production of the recovery boiler and power boiler or improving the energy procurement. This thesis concentrates on reviewing pulp mills' energy consumption per ton of pulp produced. The aim of thesis was to define the energy consumption of a modem pulp mill and estimate the limits within the consumption vary in different departments. In addition, the variables affecting the consumption for each department are discussed. Energy consumption data from books, reports, Pöyry Forest Industry's internal database and data obtained by interviewing experts are combined into figures for illustrating the consumption in selected mill departments. The actual mill data consists of 26 mills, which are located in Europe, South-America and North-America. In general, the energy consumption of pulp mills has decreased significantly since the 1970s. In some departments, the consumption has, however, increased. Modern recovery boilers consume more steam and electricity because of increased preheating and higher feedwater pressure. The excess energy generated is manifold compared to the increase in consumption. Many environmental technologies such as electrostatic precipitators and aerated waste water treatment plants, also increases the demand for electricity. A departmental-level comparison between mills can be misleading, because the boundaries between departments are vague and not well defined; departmental consumptions may be combined or they may include additional equipment. This applies in particular to electricity consumption, because electrical switchgear centres are not department-specific. Hence, it is important to know the reasons behind the energy consumption and understand how changes in energy consumption in one process area affect other areas. Departmental-level improvements may result in drawbacks at mill level. The median heat consumption for the selected mills is 11.9 GJ/ADt and the median electricity consumption 667 kWh/ADt. In a new pulp mill, the heat consumption is lower (under 10 GJ/ADt), but the electricity consumption is about the same (670 kWh/ADt). - Evaluating the constraints and benefits of integrating biofuel production to a kraft pulp and paper mill
Helsinki University of Technology | Master's thesis(2007) Suomi, Outi - Evaluation of technologies and profitability of an integrated forest biorefinery
Helsinki University of Technology | Master's thesis(2008) Runsala, JussiTyön kirjallisuusosassa on esitelty biodieselin valmistuksen eri prosessivaiheet ja vertailtu erilaisia teknologisia ratkaisuja prosessivaiheisiin. Lisäksi on pyritty pohtimaan niitä mahdollisuuksia, haasteita ja ongelmia, joita biodieselin valmistuksen integrointi sellutehtaaseen sisältää. Työn kokeellisessa osassa laskettiin energia- ja massataseet integroidulle biojalostamolle. Tarkoituksena oli selvittää, onko biodieselin valmistuksen integrointi sellutehtaaseen teknisesti ja taloudellisesti kannattavaa. Tasetietoihin perustuen biodieselin valmistusprosessin laitteisto mitoitettiin ja investointikustannus laskettiin. Myyntitulot ja muut taloudelliset hyödyt laskettiin, kuten myös prosessin muuttuvat ja kiinteät kustannukset. Näiden tietojen perusteella tehtiin kannattavuuslaskelmat. Investoinnin kannattavuutta kuvaaviksi tunnusluvuiksi valittiin takaisinmaksuaika ja sisäinen korko. Taselaskut osoittivat, että biodieselin valmistuksessa syntyy huomattavia määriä ylimääräistä lämpöenergiaa. Tämän energian hyödyntäminen on tehokkaan prosessin kannalta erittäin tärkeää. Integroinnin toteuttamiseen löydettiin kaksi tehokasta tapaa, joissa lämpö saadaan hyödynnettyä. Ensimmäinen vaihtoehto on korvata sellutehtaan biopolttoaineella toimiva lämpökattila suhteellisen suurella biodieselin valmistusprosessilla, jolloin ylimääräinen lämpöenergia korvaa alkuperäisen kattilan energian tuotantoa. Jos alkuperäisellä tehtaalla on alikuormitettu lauhdeturbiini, on toisena vaihtoehtona integroida pienempi biodieselin valmistusprosessi tehtaaseen ja käyttää ylimäärä lämpö lauhdeturbiinissa. Investointikustannus biodieselin valmistusprosessille, joka tuottaa noin 70 000 tonnia Fischer-Tropsch nesteitä vuodessa, on noin 300 milj.euroa. Integroimattomalle laitokselle kustannus on noin 30 % suurempi. Tase- ja talouslaskut osoittivat integroinnin muiltakin osin erittäin kannattavaksi verrattuna itsenäiseen biodieselin valmistukseen. Integroidun prosessin sisäinen korko vaihtelee 6- 10 prosenttiin ja takaisinmaksu aika 8 - 10 vuoteen, riippuen integrointitavasta, raaka-aine kustannuksista, ja sähkön ja tuotteen hinnasta. Tuotteen myyntihinnalla huomattiin olevan erittäin suuri vaikutus toiminnan kannattavuuteen ja jo suhteellisen pienikin muutos ylöspäin voi nostaa biodieselin valmistuksen kannattavuutta erittäin merkittävästi. - Impact of structural changes on energy efficiency of Finnish pulp and paper industry
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2019-09-26) Kähkönen, Satu; Vakkilainen, Esa; Laukkanen, TimoA key challenge in prevention of global warming is how to increase energy efficiency, to be able to deal with increased fossil CO2 emissions from rising energy usage. Increasing energy efficiency will decrease energy usage and is in a key role in emission mitigation. The focus is the pulp and paper industry, which is energy-intensive. Development of industrial energy efficiency has been studied before but the role of industrial transformation is still mostly unknown. The knowledge must be improved, to be able to predict future developments in the most effective way. In this research, impact of various production unit closures and start-ups on energy efficiency of the Finnish pulp and paper industry were studied utilizing statistical analysis. Results indicate that about 20% of the Finnish pulp and paper industry energy efficiency improvement between 2011 and 2017 is caused by the major structural changes. The rest, 80% of the progress, was mainly due to improved technology and more optimal operational modes. Additional findings suggest that modern mill start-ups have a significantly greater potential to reduce energy consumption than old mill closures. - Principles and Modelling of Hazardous Waste Incineration for Slagging Rotary Kiln System
Helsinki University of Technology | Licentiate thesis(1998) Sillanpää, Timo - Superheated steam drying of kraft black liquor, development of an alternate kraft recovery process
Helsinki University of Technology | Master's thesis(1997) Dorasamy, Narainsamy - Soodasulan ominaisuuksien ja sen vaihtoehtoisten jäähdytysmenetelmien tarkastelu
Helsinki University of Technology | Master's thesis(1995) Laine, Jerri