Indoor air quality at a waste incineration plant in Finland

Waste has been incinerated for energy utilization for more than a hundred years, but the harmful emissions emitted from the incineration plants did not begin to cause concern until the 1980s. Many plants were shutdown and the waste incineration plant in Kyläsaari Helsinki was one of them. In later years, new landfill regulations have increased the interest in waste incineration. During the last year, four new plants were taken into operation in Finland, Westenergy in Vaasa among them. The presence of dust has been observed indoors at Westenergy waste incineration plant. Dust is defined as particles with a diameter above 10 μm, while fine particles have a diameter smaller than 2.5 μm, ultrafine under 0.1 μm and nanoparticles under 0.05 μm. In recent years, the focus of particle health research has been changed to investigate smaller particles. Ultrafine particles have been found to be more detrimental to health than larger particles. Limit values regulating the concentrations of ultrafine particles have not been determined yet. The objective of this thesis was to investigate dust and particles present inside the Westenergy waste incineration facility. The task was to investigate the potential pollutant sources and to give recommendations of how to minimize the presence of dust and particles in the power plant. The total particle number concentrations and size distributions where measured at 15 points inside the plant with an Engine Exhaust Particle Sizer (EEPS) Spectrometer. The measured particles were mainly in the ultrafine size range. Dust was only visually investigated, since the main purpose was to follow the dust accumulation. The measurement points inside the incineration plant were chosen according to investigate exposure to visitors and workers. At some points probable leakage of emissions were investigated. The measurements were carried out during approximately one month in March–April 2013. The results of the measurements showed that elevated levels of dust and particles are present in the indoor air at the waste incineration plant. The cleanest air was found in the control room, warehouse and office. The most polluted air was near the sources that were investigated due to possible leakage and in the bottom ash hall. However, the concentrations were near measured background concentrations in European cities and no leakage could be detected. The high concentrations were assumed to be a result of a lot of dust and particles present on surfaces that had not been cleaned in a while. The main source of the dust and particles present inside the waste incineration plant was thought to be particles and dust from the outside air. Other activities in the area around the waste incineration facility are ground work activities, stone crushing and traffic, which probably are sources of particle formation. Filtration of the outside air prior entering the facility would probably save personnel and visitors from nuisance and save in cleaning and maintenance costs.

Syttyminen ja palamisen eteneminen partikkelikerroksessa

Syttymistä ja palamisen etenemistä partikkelikerroksessa tutkitaan paloturvallisuuden parantamista sekä kiinteitä polttoaineita käyttävien polttolaitteiden toiminnan tuntemista ja kehittämistä varten. Tässä tutkimuksessa on tavoitteena kerätä yhteen syttymiseen ja liekkirintaman etenemiseen liittyviä kokeellisia ja teoreettisia tutkimustuloksia, jotka auttavat kiinteäkerrospoltto- ja -kaasutus-laitteiden kehittämisessä ja suunnittelussa. Työ on esitutkimus sitä seuraavalle kokeelliselle ja teoreettiselle osalle. Käsittelyssä keskitytään erityisesti puuperäisiin polttoaineisiin. Hiilidioksidipäästöjen vähentämistavoitteet sekä kiinteiden jätteiden energiakäytön lisääminen ja kaatopaikalle viennin vähentäminen aiheuttavat lähitulevaisuudessa kerrospolton lisääntymistä. Kuljetusmatkojen optimoinnin takia joudutaan rakentamaan melko pieniä polttolaitoksia, joissa kerrospolttotekniikka on edullisin vaihtoehto. Syttymispisteellä tarkoitetaan Semenovin määritelmän mukaan tilaa ja ajankohtaa, jolloin polttoaineen ja hapen reaktioissa muodostuva nettoenergia aikayksikössä on yhtäsuuri kuin ympäristöön siirtyvä nettoenergiavirta. Itsesyttyminen tarkoittaa syttymistä ympäristön lämpötilan tai paineen suurenemisen seurauksena. Pakotettu syttyminen tapahtuu, kun syttymispisteen läheisyydessä on esimerkiksi liekki tai hehkuva kiinteä kappale, joka aiheuttaa paikallisen syttymisen ja syttymisrintaman leviämisen muualle polttoaineeseen. Kokeellinen tutkimus on osoittanut tärkeimmiksi syttymiseen ja syttymisrintaman etenemiseen vaikuttaviksi tekijöiksi polttoaineen kosteuden, haihtuvien aineiden pitoisuuden ja lämpöarvon, partikkelikerroksen huokoisuuden, partikkelien koon ja muodon, polttoaineen pinnalle tulevan säteilylämpövirran tiheyden, kaasun virtausnopeuden kerroksessa, hapen osuuden ympäristössä sekä palamisilman esilämmityksen. Kosteuden lisääntyminen suurentaa syttymisenergiaa ja -lämpötilaa sekä pidentää syttymisaikaa. Mitä enemmän polttoaine sisältää haihtuvia aineita sitä pienemmässä lämpötilassa se syttyy. Syttyminen ja syttymisrintaman eteneminen ovat sitä nopeampia mitä suurempi on polttoaineen lämpöarvo. Kerroksen huokoisuuden kasvun on havaittu suurentavan palamisen etenemisnopeutta. Pienet partikkelit syttyvät yleensä nopeammin ja pienemmässä lämpötilassa kuin suuret. Syttymisrintaman eteneminen nopeutuu partikkelien pinta-ala - tilavuussuhteen kasvaessa. Säteilylämpövirran tiheys on useissa polttosovellutuksissa merkittävin lämmönsiirtotekijä, jonka kasvu luonnollisesti nopeuttaa syttymistä. Ilman ja palamiskaasujen virtausnopeus kerroksessa vaikuttaa konvektiiviseen lämmönsiirtoon ja hapen pitoisuuteen syttymisvyöhykkeellä. Ilmavirtaus voi jäähdyttää ja kuumankaasun virtaus lämmittää kerrosta. Hapen osuuden kasvaminen nopeuttaa syttymistä ja liekkirintaman etenemistä kunnes saavutetaan tila, jota suuremmilla virtauksilla ilma jäähdyttää ja laimentaa reaktiovyöhykettä. Palamisilman esilämmitys nopeuttaa syttymisrintaman etenemistä. Syttymistä ja liekkirintaman etenemistä kuvataan yleensä empiirisillä tai säilyvyysyhtälöihin perustuvilla malleilla. Empiiriset mallit perustuvat mittaustuloksista tehtyihin korrelaatioihin sekä joihinkin tunnettuihin fysikaalisiin lainalaisuuksiin. Säilyvyysyhtälöihin perustuvissa malleissa systeemille määritetään massan, energian, liikemäärän ja alkuaineiden säilymisyhtälöt, joiden nopeutta kuvaavien siirtoyhtälöiden muodostamiseen käytetään teoreettisella ja kokeellisella tutkimuksella saatuja yhtälöitä. Nämä mallinnusluokat ovat osittain päällekkäisiä. Pintojen syttymistä kuvataan usein säilyvyysyhtälöihin perustuvilla malleilla. Partikkelikerrosten mallinnuksessa tukeudutaan enimmäkseen empiirisiin yhtälöihin. Partikkelikerroksia kuvaavista malleista Xien ja Liangin hiilipartikkelikerroksen syttymiseen liittyvä tutkimus ja Gortin puun ja jätteen polttoon liittyvä reaktiorintaman etenemistutkimus ovat lähimpänä säilyvyysyhtälöihin perustuvaa mallintamista. Kaikissa malleissa joudutaan kuitenkin yksinkertaistamaan todellista tapausta esimerkiksi vähentämällä dimensioita, reaktioita ja yhdisteitä sekä eliminoimalla vähemmän merkittävät siirtomekanismit. Suoraan kerrospolttoa ja -kaasutusta palvelevia syttymisen ja palamisen etenemisen tutkimuksia on vähän. Muita tarkoituksia varten tehtyjen tutkimusten polttoaineet, kerrokset ja ympäristöolosuhteet poikkeavat yleensä selvästi polttolaitteiden vastaavista olosuhteista. Erikokoisten polttoainepartikkelien ja ominaisuuksiltaan erilaisten polttoaineiden seospolttoa ei ole tutkittu juuri ollenkaan. Polttoainepartikkelien muodon vaikutuksesta on vain vähän tutkimusta.Ilman kanavoitumisen vaikutuksista ei löytynyt tutkimuksia.

Comprehensive Study of Crystal Growth from Solution

Crystal growth is an essential phase in crystallization kinetics. The rate of crystal growth provides significant information for the design and control of crystallization processes; nevertheless, obtaining accurate growth rate data is still challenging due to a number of factors that prevail in crystal growth. In industrial crystallization, crystals are generally grown from multi-componentand multi-particle solutions under complicated hydrodynamic conditions; thus, it is crucial to increase the general understanding of the growth kinetics in these systems. The aim of this work is to develop a model of the crystal growth rate from solution. An extensive literature review of crystal growth focuses on themodelling of growth kinetics and thermodynamics, and new measuring techniques that have been introduced in the field of crystallization. The growth of a singlecrystal is investigated in binary and ternary systems. The binary system consists of potassium dihydrogen phosphate (KDP, crystallizing solute) and water (solvent), and the ternary system includes KDP, water and an organic admixture. The studied admixtures, urea, ethanol and 1-propanol, are employed at relatively highconcentrations (of up to 5.0 molal). The influence of the admixtures on the solution thermodynamics is studied using the Pitzer activity coefficient model. Theprediction method of the ternary solubility in the studied systems is introduced and verified. The growth rate of the KDP (101) face in the studied systems aremeasured in the growth cell as a function of supersaturation, the admixture concentration, the solution velocity over a crystal and temperature. In addition, the surface morphology of the KDP (101) face is studied using ex situ atomic force microscopy (AFM). The crystal growth rate in the ternary systems is modelled on the basis of the two-step growth model that contains the Maxwell-Stefan (MS) equations and a surface-reaction model. This model is used together with measuredcrystal growth rate data to develop a new method for the evaluation of the model parameters. The validation of the model is justified with experiments. The crystal growth rate in an imperfectly mixed suspension crystallizer is investigatedusing computational fluid dynamics (CFD). A solid-liquid suspension flow that includes multi-sized particles is described by the multi-fluid model as well as by a standard k-epsilon turbulence model and an interface momentum transfer model. The local crystal growth rate is determined from calculated flow information in a diffusion-controlled crystal growth regime. The calculated results are evaluated experimentally.

Ash Particle Erosion on Steam Boiler Convective Section

In this study, equations for the calculation of erosion wear caused by ash particles on convective heat exchanger tubes of steam boilers are presented. Anew, three-dimensional test arrangement was used in the testing of the erosion wear of convective heat exchanger tubes of steam boilers. When using the sleeve-method, three different tube materials and three tube constructions could be tested. New results were obtained from the analyses. The main mechanisms of erosionwear phenomena and erosion wear as a function of collision conditions and material properties have been studied. Properties of fossil fuels have also been presented. When burning solid fuels, such as pulverized coal and peat in steam boilers, most of the ash is entrained by the flue gas in the furnace. In bubbling andcirculating fluidized bed boilers, particle concentration in the flue gas is high because of bed material entrained in the flue gas. Hard particles, such as sharp edged quartz crystals, cause erosion wear when colliding on convective heat exchanger tubes and on the rear wall of the steam boiler. The most important ways to reduce erosion wear in steam boilers is to keep the velocity of the flue gas moderate and prevent channelling of the ash flow in a certain part of the cross section of the flue gas channel, especially near the back wall. One can do this by constructing the boiler with the following components. Screen plates can beused to make the velocity and ash flow distributions more even at the cross-section of the channel. Shield plates and plate type constructions in superheaters can also be used. Erosion testing was conducted with three types of tube constructions: a one tube row, an inline tube bank with six tube rows, and a staggered tube bank with six tube rows. Three flow velocities and two particle concentrations were used in the tests, which were carried out at room temperature. Three particle materials were used: quartz, coal ash and peat ash particles. Mass loss, diameter loss and wall thickness loss measurements of the test sleeves were taken. Erosion wear as a function of flow conditions, tube material and tube construction was analyzed by single-variable linear regression analysis. In developing the erosion wear calculation equations, multi-variable linear regression analysis was used. In the staggered tube bank, erosion wear had a maximum value in a tube row 2 and a local maximum in row 5. In rows 3, 4 and 6, the erosion rate was low. On the other hand, in the in-line tube bank the minimum erosion rate occurred in tube row 2 and in further rows the erosion had an increasing value, so that in a six row tube bank, the maximum value occurred in row 6.

Quantification of Proteins and Cells: Luminometric Nonspecific Particle-Based Methods

New luminometric particle-based methods were developed to quantify protein and to count cells. The developed methods rely on the interaction of the sample with nano- or microparticles and different principles of detection. In fluorescence quenching, timeresolved luminescence resonance energy transfer (TR-LRET), and two-photon excitation fluorescence (TPX) methods, the sample prevents the adsorption of labeled protein to the particles. Depending on the system, the addition of the analyte increases or decreases the luminescence. In the dissociation method, the adsorbed protein protects the Eu(III) chelate on the surface of the particles from dissociation at a low pH. The experimental setups are user-friendly and rapid and do not require hazardous test compounds and elevated temperatures. The sensitivity of the quantification of protein (from 40 to 500 pg bovine serum albumin in a sample) was 20-500-fold better than in most sensitive commercial methods. The quenching method exhibited low protein-to-protein variability and the dissociation method insensitivity to the assay contaminants commonly found in biological samples. Less than ten eukaryotic cells were detected and quantified with all the developed methods under optimized assay conditions. Furthermore, two applications, the method for detection of the aggregation of protein and the cell viability test, were developed by utilizing the TR-LRET method. The detection of the aggregation of protein was allowed at a more than 10,000 times lower concentration, 30 μg/L, compared to the known methods of UV240 absorbance and dynamic light scattering. The TR-LRET method was combined with a nucleic acid assay with cell-impermeable dye to measure the percentage of dead cells in a single tube test with cell counts below 1000 cells/tube.

Oxidation rates of carbon and nitrogen in char residues from solid fuels

Computational fluid dynamics (CFD) modeling is an important tool in designing new combustion systems. By using CFD modeling, entire combustion systems can be modeled and the emissions and the performance can be predicted. CFD modeling can also be used to develop new and better combustion systems from an economical and environmental point of view. In CFD modeling of solid fuel combustion, the combustible fuel is generally treated as single fuel particles. One of the limitations with the CFD modeling concerns the sub-models describing the combustion of single fuel particles. Available models in the scientific literature are in many cases not suitable as submodels for CFD modeling since they depend on a large number of input parameters and are computationally heavy. In this thesis CFD-applicable models are developed for the combustion of single fuel particles. The single particle models can be used to improve the combustion performance in various combustion devices or develop completely new technologies. The investigated fields are oxidation of carbon (C) and nitrogen (N) in char residues from solid fuels. Modeled char-C oxidation rates are compared to experimental oxidation rates for a large number of pulverized solid fuel chars under relevant combustion conditions. The experiments have been performed in an isothermal plug flow reactor operating at 1123-1673 K and 3-15 vol.% O2. In the single particle model, the char oxidation is based on apparent kinetics and depends on three fuel specific parameters: apparent pre-exponential factor, apparent activation energy, and apparent reaction order. The single particle model can be incorporated as a sub-model into a CFD code. The results show that the modeled char oxidation rates are in good agreement with experimental char oxidation rates up to around 70% of burnout. Moreover, the results show that the activation energy and the reaction order can be assumed to be constant for a large number of bituminous coal chars under conditions limited by the combined effects of chemical kinetics and pore diffusion. Based on this, a new model based on only one fuel specific parameter is developed (Paper III). The results also show that reaction orders of bituminous coal chars and anthracite chars differ under similar conditions (Paper I and Paper II); reaction orders of bituminous coal chars were found to be one, while reaction orders of anthracite chars were determined to be zero. This difference in reaction orders has not previously been observed in the literature and should be considered in future char oxidation models. One of the most frequently used comprehensive char oxidation models could not explain the difference in the reaction orders. In the thesis (Paper II), a modification to the model is suggested in order to explain the difference in reaction orders between anthracite chars and bituminous coal chars. Two single particle models are also developed for the NO formation and reduction during the oxidation of single biomass char particles. In the models the char-N is assumed to be oxidized to NO and the NO is partly reduced inside the particle. The first model (Paper IV) is based on the concentration gradients of NO inside and outside the particle and the second model is simplified to such an extent that it is based on apparent kinetics and can be incorporated as a sub-model into a CFD code (Paper V). Modeled NO release rates from both models were in good agreement with experimental measurements from a single particle reactor of quartz glass operating at 1173-1323 K and 3-19 vol.% O2. In the future, the models can be used to reduce NO emissions in new combustion systems.

Novel technology for preparation of optically active chemicals

Asymmetric synthesis using modified heterogeneous catalysts has gained lots of interest in the production of optically pure chemicals, such as pharmaceuticals, nutraceuticals, fragrances and agrochemicals. Heterogeneous modified catalysts capable of inducing high enantioselectivities are preferred in industrial scale due to their superior separation and handling properties. The topic has been intensively investigated both in industry and academia. The enantioselective hydrogenation of ethyl benzoylformate (EBF) to (R)-ethyl mandelate over (-)-cinchonidine (CD)-modified Pt/Al2O3 catalyst in a laboratory-scale semi-batch reactor was studied as a function of modifier concentration, reaction temperature, stirring rate and catalyst particle size. The main product was always (R)-ethyl mandelate while small amounts of (S)-ethyl mandelate were obtained as by product. The kinetic results showed higher enantioselectivity and lower initial rates approaching asymptotically to a constant value as the amount of modifier was increased. Additionally, catalyst deactivation due to presence of impurities in the feed was prominent in some cases; therefore activated carbon was used as a cleaning agent of the raw material to remove impurities prior to catalyst addition. Detailed characterizations methods (SEM, EDX, TPR, BET, chemisorption, particle size distribution) of the catalysts were carried out. Solvent effects were also studied in the semi-batch reactor. Solvents with dielectric constant (e) between 2 and 25 were applied. The enantiomeric excess (ee) increased with an increase of the dielectric coefficient up to a maximum followed by a nonlinear decrease. A kinetic model was proposed for the enantioselectivity dependence on the dielectric constant based on the Kirkwood treatment. The non-linear dependence of ee on (e) successfully described the variation of ee in different solvents. Systematic kinetic experiments were carried out in the semi-batch reactor. Toluene was used as a solvent. Based on these results, a kinetic model based on the assumption of different number of sites was developed. Density functional theory calculations were applied to study the energetics of the EBF adsorption on pure Pt(1 1 1). The hydrogenation rate constants were determined along with the adsorption parameters by non-linear regression analysis. A comparison between the model and the experimental data revealed a very good correspondence. Transient experiments in a fixed-bed reactor were also carried out in this work. The results demonstrated that continuous enantioselective hydrogenation of EBF in hexane/2-propanol 90/10 (v/v) is possible and that continuous feeding of (-)-cinchonidine is needed to maintain a high steady-state enantioselectivity. The catalyst showed a good stability and high enantioselectivity was achieved in the fixed-bed reactor. Chromatographic separation of (R)- and (S)-ethyl mandelate originating from the continuous reactor was investigated. A commercial column filled with a chiral resin was chosen as a perspective preparative-scale adsorbent. Since the adsorption equilibrium isotherms were linear within the entire investigated range of concentrations, they were determined by pulse experiments for the isomers present in a post-reaction mixture. Breakthrough curves were measured and described successfully by the dispersive plug flow model with a linear driving force approximation. The focus of this research project was the development of a new integrated production concept of optically active chemicals by combining heterogeneous catalysis and chromatographic separation technology. The proposed work is fundamental research in advanced process technology aiming to improve efficiency and enable clean and environmentally benign production of enantiomeric pure chemicals.