Alkali emissions characterization in chemical looping combustion of wood, wood char, and straw fuels

Chemical looping combustion of wood pellets (WP), wood char (WC), and straw pellets (SP) was conducted in a 60 kW CLC pilot with ilmenite and braunite oxygen carriers (OCs). Alkali emissions were investigated with impactor-based and surface ionization detector (SID) measurements. Particle size distributions for WP and WC fuels were dominated by coarse particles formed by refractory species. For SP fuel, the distribution was bimodal with a distinct fine particle mode formed by nucleation of volatile ash species. Thermodynamic modelling of stable alkali species at 800 \ub0C predicted that high KOH(g) and lower concentrations of KCl(g) are stable for WP and WC fuels. For SP fuel, equilibrium K species were dominated by condensed-phase K species, followed by KCl(g), and KOH(g). Modelling of fuel-OC interactions showed that ilmenite decreases equilibrium levels of KOH(g) and KCl(g). Braunite impacted only KOH(g) levels. Impactor sample leachate analysis showed that for WP-braunite operation, the leachate contained KCl, NaCl, KOH, and NaOH, in decreasing order. For WC-ilmenite operation, the samples contained KOH and KCl. For SP fuel, most detected alkalis were KCl. For most cases, speciation of impactor samples qualitatively agreed with modelling predictions. Impactor and SID alkali measurements showed reasonable agreement for WC-braunite and SP-braunite tests

English

Educational field can take advantage of the improvements of Automatic Speech Recognition (ASR), since we can apply ASR algorithms in non-ideal conditions such as real classrooms. In the context of [name deleted to maintain the integrity of the review process], conceptual networks are studied. The networks relate key concepts used by the teacher in his/her discourse. In the present study, quantitative metrics are provided, such as centrality measures and PageRank, which can be used to analyse the conceptual networks. With a case-study design, two teachers’ classes are described quantitatively and qualitatively using the metrics, suggesting that PageRank could be a good metric to find differences in teachers’ discourse. Finally, we discuss about the potential of this kind of analysis

Development of chemical looping combustion technology for bio-CCS application

Carbon capture and storage (CCS) is acknowledged as an important technology in cost-efficiently achieving the required greenhouse gas emission reductions this century. Combining biomass combustion with CCS (Bio-CCS; BECCS) offers the possibility of “negative” CO2 emissions. In the latest IPCC assessment, bio-CCS was found to have an important role to play in climate change mitigation. Many scenario models were not able to achieve the necessary reduction in greenhouse gas concentration in the atmosphere to 450 ppm CO2eq by 2100 if key technologies, such as bioenergy, CCS, and their combination were limitedly available (IPCC, 2014). Chemical looping combustion (CLC) is a new technology being developed that could be promising both for biomass combustion and as a bio-CCS application. In chemical looping combustion, the fuel is oxidized in two separate reactors with solid metal oxide particles, called “oxygen carriers”, transporting the oxygen between the two reactors. In the air reactor, the metal oxide particles react with the oxygen in air, after which the particles are transported to the fuel reactor, where they react with the fuel. It is expected that high-temperature corrosion problems can be significantly reduced in a bio-CLC reactor as compared to a conventional biomass furnace. This is because heat will be extracted mainly in the exothermic air reactor, in which there will be no alkali compounds present and very little fly ash. This should in turn allow the use of higher steam parameters in comparison to conventional biomass combustion, which would improve the power generation efficiency. In order to test and verify the benefits of bio-CLC, a new dual fluidized bed (DFB) test rig applicable for biomass was converted into a 10-50 kWth scale bio-CLC test rig. The test rig is located at VTT’s new piloting centre Bioruukki in Finland and consists of a circulating fluidized bed (CFB) air reactor interconnected with a bubbling fluidized bed (BFB) fuel reactor. A set of tests is currently being carried out using ilmenite as oxygen carrier and wood pellets as fuel. The main objectives are to study and optimize operation and process parameters for CLC using biomass-based fuels with both high and low volatile contents. In addition, deposit formation and corrosion will be evaluated in order to evaluate the possibility for improving power generation efficiency by using enhanced steam parameters. The research is carried out in the framework of two research projects: the Carbon Capture and Storage R&D Program (CCSP) with financial support from Tekes - the Finnish Funding Agency for Innovation, and Nordic Energy Research’s flagship project ”Negative CO2 Emissions with Chemical Looping Combustion of Biomass”

Big problem, little answer: overcoming bed agglomeration and reactor slagging during the gasification of barley straw under continuous operation

Defluidisation as a result of reactor bed agglomeration is a global challenge associated with the gasification of lignocellulosic biomass waste, specifically its high inorganic content. The use of conventional water leaching has been scrutanised for the removal of inorganic constituents from barley straw, a highly abundant waste feedstock with high ash content. The resulting pre-treated material was subsequently gasified at 750 oC and 850 oC under continuous flow, where it was found that bed agglomeration as a result of the ash melting induced mechanism can be eliminated, as visuallised by SEM and EDX studies. Here, the presence of eutetic mixtures result in the fusing of a SiO2 rich bed material that cause a sudden pressure drop in the reactor, resulting in a forced shutdown. Leached barley straw was found to effectively solve this issue and sustained gasification for a long period of time, as well as limiting inorganic based decoration on the surface of bed material grains after reaction. Additionally, leaching was found to enhance the production of low carbon fuel gases where an improved product yield of 31.9%vol and 37.3%vol for CO and CH4 was observed at 850 oC, as compared to untreated equivalent

English

We propose a method that automatically describes teacher talk. The method allows us to describe and compare classroom lessons, as well as visualizing changes in teacher discourse throughout the course of a lesson. The proposed method uses a machine learning model to infer topics from school textbooks. Certain topics are related to different contents (e.g. kinematics, solar system, electricity), while others are related to different teaching functions (e.g. explanations, questions, numerical exercises). To describe teacher talk, the machine learning method measures the appearance of the inferred topics throughout each lesson. We apply the proposed method to a collection of transcripts from physics lessons, as well as discussing the potentialities of integrating the proposed method with other kinds of automatic and manual classroom lesson descriptions

Investigation of biomass alkali release in a dual circulating fluidized bed chemical looping combustion system

Chemical looping combustion (CLC) of biomass is a promising technology for power generation with integrated carbon capture. In CLC, alkali content of biomass poses potential issues of bed agglomeration, as well as heat exchanger fouling and corrosion. The fate of biomass alkalis was investigated in a dual-interconnected circulating fluidized bed CLC system. Experiments were conducted in oxygen carrier aided combustion (OCAC) and CLC modes. Ilmenite and braunite oxygen carriers and three biomass fuels (wood pellets, wood char, straw pellets) were tested. Flue gas alkali emissions in the air reactor (AR) and fuel reactor (FR) were measured with a surface ionization detector (SID). Results showed that CLC operation yields gas-phase alkali emissions that are up to 15 times higher than in comparable OCAC operation. Results analysis concluded that increased alkali emissions in CLC arise from the steam atmosphere in the FR, whereby steam accelerates the decomposition of alkali compounds in the biomass. Retention of alkalis in the condensed phase was found to be >97% for ilmenite and >92% for braunite CLC operation. Up to 60?80% of the retention was attributed to fuel ash formation. The residual retention was attributed to absorption of alkalis by the oxygen carriers. Absorption likely occurred mainly through formation of alkali manganates and silicates in braunite, and formation of alkali silicates, aluminosilicates, manganates, and titanates in ilmenite. Gas-phase alkali emissions in the AR, although less than in the FR, were found to occur due to combustion of unconverted fuel carried over from the FR to the AR

Spectrum, Volume 12, Number 20

Highlights include: 1994 was the first year in which any member of the University community could be awarded the 30 year honor. Last year. Registrar Douglas Bohn and Professor Maria Toiriera were handed medals for their service. This year Professor of Mathematics Raoul DeVilliers and Professor of Art Virginia Zic will receive 30 year medals -- Twelve faculty members, representing all disciplines, have become involved in a new Writing Advisory Board. Director of Freshman Communications Dr. Alison Warriner formed the board with the future of writing instruction at Sacred Heart University in mind. The Writing Advisory Board is currently discussing options to bring a writing-across-the-curriculum (WAC) program to SHU --Four professors take sabbatical: professors will be involved in projects designed to enhance their effectiveness as university faculty. Associate Professor of philosophy, Dr. Edward A. Papa, in his eighth year with the University will be writing. Dr. Gary L. Rose, professor of political science, will be completing his fourth book The American presidency under siege. After 29 years with the University, Associate Professor of biology. Dr. Carol Schofield will undertake the task of redesigning the University’s anatomy and physiology laboratories, using a multi-media interactive approach to learning. Ninth year history professor Dr. Thomas Curran will be involved in several research projects. His primary focus will be on revising his dissertation, “Education and Society in Republican China,” which deals with the changing status of intellectuals --Professor Jonathan Matte makes Math magnificent

Initialization of the JYFLTRAP system

The IGISOL facility has been moved into a new location at the acceleration laboratory of the University of Jyväskylä. The superconducting magnet that is part of the JYFLTRAP system has been re-energized. In this thesis a commissioning of the Penning trap apparatus JYFLTRAP is described. This involves a precise alignment of the structure of the trap along field lines of strong solenoid field. The alignment was completed successfully with a special alignment device. In addition, some improvements were done for the Penning traps and transfer line from RFQ cooler, and a buncher to the injection of Penning traps was built during this project.Jyväskylän yliopiston IGISOL-ryhmän laboratorio on muutettu fysiikan laitoksen kiihdytinlaboratorion sisällä uusiin tiloihin. IGISOL-laitteistoon kuuluu 7 Teslan suprajohtava solenoidi, joka laboratorion muuton yhteydessä on ensin kytketty pois päältä ja sitten käynnistetty uudelleen. Suprajohtava solenoidi ja sen sisällä olevat kaksi Penningin loukkua ovat osa JYFLTRAPiksi nimettyä loukkujärjestelmää. Tässä tutkielmassa esitellään toimenpiteet, jotka tehtiin Penningin loukku -laitteiston käyttöönottoa varten. Solenoidin käynnistämisen jälkeen sen sisällä oleva tyhjiöputki linjattiin tarkasti samansuuntaiseksi magneettikentän kenttäviivojen kanssa. Linjaukseen käytettiin erityisesti tähän tarkoitukseen suunniteltua linjauslaitetta. Penningin loukkuihin tehtiin muutamia parannuksia, ennen kuin ne laitettiin tyhjiöputkeen solenoidin sisälle. Lisäksi suihkulinja radiotaajuuskvadrupolilta Penningin loukkujen injektiopuolelle rakennettiin tämän projektin aikana

Asiakastyytyväisyystutkimus pankki X:lle

Tutkimuksen tavoitteena oli selvittää toimeksiantaja pankin sen hetkistä asiakastyytyväisyyttä ja pyrkiä löytämään toimintaan kehitysideoita. Tässä opinnäytetyössä ohjaavina tutkimuskysymyksinä olivat: ’’Miten tyytyväisiä pankki X:n asiakkaat ovat saamaansa asiakaspalveluun?’’ ja ”Mitä kehitysehdotuksia asiakkaat esittävät?” Tutkimuksessa käytettiin kvantitatiivista tutkimusta ja asiakastyytyväisyyskysely toteutettiin paperisella kyselylomakkeella ja puhelinkyselyillä. Tutkimuksen tulokset osoittautuivat hyvin positiivisiksi. Tuloksista voidaan päätellä, että asiakkaat ovat tyytyväisiä kyseisen pankin henkilökuntaan ja palveluun. Kehitysehdotuksina keskeisinä esiin nousi palvelun saatavuus liittyen aukioloaikoihin ja toimihenkilöiden suorien puhelinnumeroiden saatavuuteen