Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 121 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 117-119).

The ever-increasing quantity of by-products generated from burning coal in the production of electricity has brought about the need for new areas of utilization. This study examined the use of FGD gypsum and fluidized bed combustion ash along with Class F fly ash in the production of low-energy, 100% by-product cement blends. The cement blends used the advantageous properties of the by-product materials to create cementing properties rather than energy intensive clinker used in ordinary portland cement. The FGD gypsum was converted to hemihydrate which rapidly hydrated to provide the cement with early strength gains, whilst the fluidized bed combustion ash reacted with the Class F fly ash to form pozzolanic cementitious phases which provided the longer-term compressive strength and possibly resistance to weathering. The rate of compressive strength gains and minimizing detrimental expansion were two properties of particular interest in the study. Chemical admixtures were used to improve the compressive strengths of the cement mortars and decrease their solubility.

De-inking sludge generated from pulp and paper industry is considered hazardous since it may contain heavy metals such as Cd, Cr, and Pb. Hence, the de-inking sludge needs to be treated before being disposed of. Sludge combustion is a proven disposal technology, which generates fly ash containing a portion of the heavy metals that may leach out under uncontrolled conditions. The aim of this thesis is to implement a new multi-zone temperature combustion technique (Low-High-Low temperature combustion, LHL) to help contain and immobilize the heavy metals within fly ash particles. During the LHL, the waste will be initially fed into a low-temperature zone (<1100 K) and then subjected to the high-temperature treatment (~1480 K) that will be followed by another low-temperature zone (~1100 K). / This dissertation describes the detailed design and construction of a novel pilot-scale combustion facility, called the Multi-Mode Combustion Facility (MCF), used as a multidisciplinary research tool for investigating the thermal remediation of contaminated solid residues. The MCF is capable of operating in two different modes: Fluidized-Bed combustion mode (FBC) and Single burner furnace mode (SBF). However, this project focuses on the FBC mode (minimum fluidization velocity of 0.42 m/s and bed temperature of 1073 K). / This research compares the combustion characteristics of de-inking sludge obtained in the LHL and in the conventional combustion techniques. The following properties of particulates were studied: morphological evolution of solid particles, structural porosity, metals interactions with fly ash particles, and leachability. / The LHL's final supermicron spherical fly ash went through a molten phase with submicron particles attached to the fly ash particles surfaces. Thus, reducing its porosity to 19%. However, the amorphous final fly ash obtained in the conventional technique reveals 32% porosity. It was found that the physical characteristics of the final LHL's fly ash are the main cause for the reduced heavy metals leachability rates of 0.18, 0.046, and 0.92% for Cd, Cr, and Pb, respectively. The conventional technique had 53.28, 16.79, and 5.20% of Cd, Cr, and Pb respectively, leaching out due to the high porosity percentages. In conclusion, the LHL technique allows for controlling the heavy metals emission from FBCs, while using a waste to energy approach and maintaining environmentally acceptable gas emission levels.

A comprehensive model, previously developed and tested for prediction of behavior of continuous fluidized bed combustors is extended to incorporate NOx formation and reduction reactions and applied to the simulation of METU 0.3 MWt Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) burning lignites with high volatile matter in their own ashes. The predictive accuracy of the model was assessed by comparing its predictions with measurements taken previously on the same rig. Favorable comparisons are obtained between the predicted and measured temperatures and concentrations of gaseous species along the combustor. Results show that determination of partitioning of coal nitrogen into char nitrogen and volatile nitrogen, and release of volatile nitrogen along the combustor are found to be the most important parameters that affect NOx formation and reduction in bubbling fluidized bed combustors. The system model proposed in this study proves to be a useful tool in qualitatively and quantitatively simulating the processes taking place in an atmospheric fluidized bed combustor.

Includes bibliographical references. / [210] leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis presents two advanced modelling studies which address some unresolved fluidized bed combustion (FBC) issues. In the first study, finite element methods are used to solve a transient continuum/percolation model of a single porous char and its surrounding boundary layer so as to generate temperature, O2,CO2, CO pressure and porosity distributions for over 100 different FBC conditions. In the second study, a new discrete approach for the determination of the diffusion coefficients of the fluid-solid system is described and used, based on moecular dynamics and percolation concepts. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1996

The new Canadian laws on CO2 emissions aim to lower the emissions of coal-fired power plants down to those of natural gas combined cycle units: 420 kg CO2/MWeh. In order to meet these requirements, calcium looping and two process variants are investigated through process simulations using Aspen Plus V8.2. The combination of calcium looping and chemical looping combustion, replacing the required air separation unit, is a way to reduce the energy penalty of the capture process. The addition of copper as an oxygen carrier in two different process configurations is compared to calcium looping and shown to reduce the efficiency penalty from 7.8% to 4.5% points but at the price of circulations rates up to about 3800 kg/s. The other improvement path studied is the implementation of calcium looping to a pressurized fluidized bed combustion unit. The pressurized carbonator acts as a reheater for the gas turbine and operating the carbonator at temperatures up to 798°C results in a reduction of the energy penalty from 5.1% to 3.1% points.

No description available.

The behavior of using oxygen carriers as bed material in a fluidized bed combustion was investigated in this work when methane, air and carbon monoxide, air are used as fluidizing gases. More specifically, conversion rate, unsteadiness and gas composition was investigated and it was found that the conversion rate of carbon monoxide and methane are higher when oxygen carriers are used as bed material compared to silica sand and that the highest conversion rate was for oxygen carriers with high oxygen transport capacity and high reactivity towards the gaseous fuel. And it was also found that unsteady concentration profiles were present for all oxygen carries when methane was used but only for manganese when carbon monoxide was used which indicates that low reactivity towards a gaseous fuel triggers unsteadiness. In addition to this ilmenite and F6MZ1100 was defluidized when carbon monoxide was used and no decrease in reactivity between oxygen carrier and oxygen was observed. The experiment was performed in a laboratory scale fluidized bed reactor were 4 different bed materials was used, manganese ore, ilmenite, F6MZ1100, silica sand and each batch used 15g of particles, a particle size of 125-180µm, a total flowrate of 900ml/min and a changing Air-fuel equivalence ratio to simulate a fuel lean and a fuel rich mixture. And in addition to this the particles were exposed to an alternating reducing and oxidizing condition to test reactivity between oxygen carrier and the used gaseous fuels. / Beteendet av syrebärare som bäddmaterial i en fluidiserad bäddförbränning har undersökts när en blandning av kolmonoxid,luft och metan,luft har använts som fluidiseringsgaser genom att utvärdera bränsle omvandlingsgraden, ostadigheter i rökgassammansättningen, rökgassammansättningen och arbetet visar att omvandlingsgraden av kolmonoxid och metan är högre när syrebärare används som bäddmaterial jämfört med när kiselsand används. Och högsta omvandlingsgraden var för syrebärare med hög syretransport kapacitet och hög reaktivitet med det gasformiga bränslet och det observerades även att ostadighet i rökgassammansättning är beroende av bränsletyp. När metangas användes fanns ostadigheter för samtliga bäddmaterial men endast för Mangan när kolmonoxid användes vilket indikerar att låg reaktivitet mellan flyktgaser och syrebärare utlöser ostadighet i rökgassammansättningen. Utöver detta uppstod fluidiseringsproblem för Ilmenit och F6MZ1100 när kolmonoxid användes vilket resulterade i partiell passering av fluidiseringsgaser genom reaktorn och utöver detta observerades inte någon minskad reaktivitet mellan syrebärarna och syre under experimentet. Experimentet utfördes i en fluidiserad bädd reaktor i laboratorieskala där 4 olika bäddmaterial testades, Manganmalm, Ilmenit, F6MZ1100 och Kiselsand och i varje experiment användes 15g partiklar med partikelstorleken 125-180μm och med ett total flödet på 900 ml/min. Och för att testa effekten vid olika blandningar av bränsle och luft ändrades luft-bränsle förhållandet så att bäddmaterialet exponerades för syreöverskott och syreunderskott och utöver detta exponerades även syrebärarna för omväxlande oxidation och reduktion för att utvärdera reaktiviteten mellan syrebärare och det gasformiga bränslet.

Reclaimed surface mined soils in Appalachia are typically infertile and must be amended for optimum vegetative growth. Fluidized bed combustion residue (FBCR), a by-product of coal-fired power plants, has high levels of Ca, S, Zn, Fe, and Al, and 50% of the neutralizing capacity of limestone. Three treatments were applied to three replicated .81 ha reclaimed mine pastures: control (no amendment), 6760 kg FBCR/ha, and 3380 kg limestone/ha. Based on forage availability, six steers were rotationally grazed on pastures receiving each treatment. Steers were weighed and blood samples collected at 14-d intervals and all animals were sacrificed for tissue sampling at the end of the 114-d trial. Amendment with FBCR or limestone increased soil pH (P < .05) above control levels. Forage yield and steer gain were not significantly affected by treatment. Forage samples collected during the trial indicated that FBCR and limestone amendments elevated forage ash, Ca, Mg, S, Cu and Ca:P ratio (P < .05). Cellulose and NDF were depressed in forage grab samples collected from FBCR- and limestone-amended pastures. The forage sampled the following spring was lower in hemicellulose, Zn, un and Ni; and higher in ash, Ca, S, the Ca: P ratio in the FBCR- and limestone-amended pastures. Mean serum mineral levels of steers were not affected by pasture treatment. The blood packed cell volume was higher in cattle grazing FBCR-amended pastures. Liver levels of Fe, H, Hi and Na were lower in cattle on pastures amended with FBCR or limestone. Bile levels of Mn were depressed in cattle grazing FBCR~ and limestone-amended pastures. The level of Cu in the liver and serum was at deficiency levels and was not detectable in bile, regardless of treatment. Higher kidney levels of Ca, Hg and P were recorded for steers grazing FBCR- and limestone-amended pastures. Hair Zn was higher in cattle grazing the FBCR- and limestone- treated pastures. Rib Cr and long bone Cd levels were lower in animals grazing the limestone- and FBCR-treated pastures. This study suggests that FBCR amendment enhances nutrient quality of forage and mineral status of animals at least as well as limestone application to acidic reclaimed mine pastures. / Ph. D. / incomplete_metadata

Bibliography: 208-218.