Fouling Tendency of Ash Resulting From Burning Mixtures of Biofuels

2005 ◽  
Author(s):  
Mischa Theis ◽  
Bengt-Johan Skrifvars ◽  
Mikko Hupa ◽  
Honghi Tran
Keyword(s):  
Flow Reactor ◽  
Chemical Interaction ◽  
Substrate Surface ◽  
Agricultural Waste ◽  
Pulp Mill ◽  
Considerable Change ◽  
Chemical Fractionation ◽  
Feed Composition ◽  
Linear Pattern ◽  
Fractionation Analysis

Specified mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor that simulates conditions in the superheater region of a biomass-fired boiler. Deposits were collected on an air-cooled probe that was inserted into the reactor at the outlet. For both mixtures, the deposition behaviour followed a non-linear pattern, which suggests that physico-chemical interaction between the ashes of the different fuels has taken place. The results indicate that it is possible to burn up to 30 wt-% bark (renewable biofuel and pulp mill waste) and up to 70 wt-% straw (renewable biofuel and agricultural waste) in mixtures with peat without encountering increased deposition rates in the reactor. The deposit composition was compared to the fuel ash composition using chemical fractionation analysis and SEM/EDX. While the composition of deposits obtained from pure fuels resembles the feed composition, a considerable change is observed in deposits obtained from mixtures. K and S compounds are attached to Si spheres and the substrate surface. The deposition rate is significantly lowered when removing K, S, Cl and Na in bark prior to burning by washing and mechanical/thermal dewatering.

Renewable Energy from Agricultural Waste

2018 ◽  
Vol 69 (6) ◽  
pp. 1363-1366 ◽  
Author(s):  
Stefania Daniela Bran ◽  
Petre Chipurici ◽  
Mariana Bran ◽  
Alexandru Vlaicu
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gas Chromatography ◽  
Continuous Flow ◽  
Laboratory Experiments ◽  
Fermentation Process ◽  
Flow Reactor ◽  
Agricultural Waste ◽  
Continuous Flow Reactor ◽  
Natural Support ◽  
Co2 Flow

This paper has aimed at evaluating the concentration of bioethanol obtained using sunflower stem as natural support, molasses as carbon source and Saccharomyces cerevisiae yeast in a continuous flow reactor. The natural support was tested to investigate the immobilization/growth of S. cerevisiae yeast. The concentration of bioethanol produced by fermentation was analyzed by gas chromatography using two methods: aqueous solutions and extraction in organic phase. The CO2 flow obtained during the fermentation process was considered to estimate when the yeast was deactivated. The laboratory experiments have highlighted that the use of plant-based wastes to bioconversion in ethanol could be a non-pollutant and sustainable alternative.

Deposition of Ceramic Films by A Novel Pulsed-Gas Mocvd Technique

1992 ◽  
Vol 271 ◽  
Author(s):  
Kenneth A. Aitchison ◽  
James D. Barrie ◽  
Joseph Ciofalo
Keyword(s):  
Gas Phase ◽  
Film Growth ◽  
Flow Reactor ◽  
Substrate Surface ◽  
Chemical Vapor ◽  
Film Deposition ◽  
Organic Chemical ◽  
Oxide Systems ◽  
Metal Organic ◽  
Mocvd Technique

ABSTRACTMetal-Organic Chemical Vapor Deposition (MOCVD) is a versatile technique for the deposition of thin films of metals, semiconductors and ceramics. Commonly used hot wall flow-reactor designs suffer from a number of limitations. Chemical processes occurring in these reactors typically include a combination of homogeneous (gas-phase) and heterogeneous (gas-surface) reactions. These complex conditions are difficult to model and are poorly understood. In addition, flow reactors use large quantities of expensive precursor materials and are not well suited to the formation of abrupt interfaces. We report here a novel MOCVD technique which addresses these problems and enables a more thorough mechanistic understanding of the heterogeneous decomposition pathways of metal-organic compounds. This technique, the low-pressure pulsed gas method, has been demonstrated to provide high deposition rates with excellent control over film thickness. The deposition conditions effectively eliminate homogeneous processes allowing surface-mediated reactions to dominate. This decoupling of gas-phase chemistry from film deposition allows a better understanding of reaction mechanisms and provides better control over film growth. Both single metal oxides and binary oxide systems have been investigated on a variety of substrate materials. Effects of precursor chemistry, substrate surface, temperature and pressure on film composition and morphology will be discussed.

Extraction of copper and zinc from naturally contaminated copper mine soils: Chemical fractionation analysis and risk assessment

2018 ◽  
Vol 25 (6) ◽  
pp. 1274-1284
Author(s):  
Jiu-hua Xiao ◽  
Jun Zhou ◽  
Zhao-hui Wang ◽  
Si-yue Li ◽  
Wei-chao Zhang ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Chemical Fractionation ◽  
Mine Soils ◽  
Copper Mine ◽  
Copper And Zinc ◽  
Fractionation Analysis

Direct Observations of the Growth of Sputtered Silver on Substrates of Graphite and Muscovite MICA

1976 ◽  
Vol 34 ◽  
pp. 648-649
Author(s):  
J. S. Maa ◽  
J. I. Lee ◽  
Thomas E. Hutchinson
Keyword(s):  
Surface Defects ◽  
Chemical Interaction ◽  
Early Stage ◽  
Ion Beam ◽  
Substrate Surface ◽  
Nucleation And Growth ◽  
Graphite Substrate ◽  
Short Period ◽  
Silver Islands

The nucleation and growth of sputtered thin films are controlled by several important factors such as nucleus mobility, substrate surface defects, substrate/ overgrowth chemical interaction, and residual gasses, which depend upon the properties of substrate-overgrowth materials and/or the deposition conditions. The effects of nucleus mobility and substrate surface defects on the nucleation and growth of in situ ion beam sputtered thin silver films have been investigated in detail using in situ electron microscopy. Silver has been sputter deposited on the basal plane of single crystal graphite substrate at temperatures ranging from 350°C to 500°C. The results obtained show that the deposition process in the case of silver on graphite is controlled by the nucleus mobility on the substrate surface. The silver islands with sizes of 20Å to 100Å at the early stage of growth are highly mobile on the graphite substrate. The migration of silver islands from one position to another occurs in a very short period of time and the distance of the island migration varies from less than 100Å to several hundred angstroms, as shown in Figure la and lb.

Cadmium Telluride Thin Films Grown By Atomic Layer Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
Arla Kytökivi ◽  
Yrjö Koskinen ◽  
Aimo Rautiainen ◽  
Jarmo Skarp
Keyword(s):  
Surface Roughness ◽  
Vapor Pressure ◽  
Flow Reactor ◽  
Substrate Surface ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Surface Development ◽  
High Vapor ◽  
Cdte Films ◽  
Cds Film

ABSTRACTPolycrystalline CdTe films up to 2 μm thick were grown by Atomic Layer Epitaxy (ALE) at 350–450°C. The growth was carried out in a lateral flow reactor, using the elements as source materials and 25 cm2 glass/ITO and glass/ITO/SnO2 as substrates. A growth of CdS film by ALE preceded the growth of CdTe.Profilometry, X-ray diffraction analysis and scanning electron microscopy were used to characterize the films.The relatively high vapor pressure of CdTe determined the upper limit of the processing window, while the small vapor pressure of Te2 set a practical lower limit of 390–400°C.The CdTe films were smooth up to 100–500 nm depending on the temperature and the substrate surface. Development of surface roughness was detected as the growth process proceeded. At the same time there was an increase of the effective surface area of the film, observed as a significant increase in the macroscopic growth rate. The greater surface roughness was also evident in the reduced degree of (111) orientation.The CdS/CdTe structure was investigated for its potential in solar cell applications.

scholarly journals Kinetics of Hydrothermal Inactivation of Endotoxins

2010 ◽  
Vol 77 (8) ◽  
pp. 2640-2647 ◽  
Author(s):  
Lixiong Li ◽  
Chris L. Wilbur ◽  
Kathryn L. Mintz
Keyword(s):  
Linear Models ◽  
Flow Reactor ◽  
Feed Water ◽  
Content Type ◽  
Linear Pattern ◽  
Log Reduction ◽  
Microbial Survival ◽  
Weibull Models ◽  
Modified Weibull ◽  
Log Linear

ABSTRACTA kinetic model was established for the inactivation of endotoxins in water at temperatures ranging from 210°C to 270°C and a pressure of 6.2 × 106Pa. Data were generated using a bench scale continuous-flow reactor system to process feed water spiked with endotoxin standard (Escherichia coliO113:H10). Product water samples were collected and quantified by theLimulusamebocyte lysate assay. At 250°C, 5-log endotoxin inactivation was achieved in about 1 s of exposure, followed by a lower inactivation rate. This non-log-linear pattern is similar to reported trends in microbial survival curves. Predictions and parameters of several non-log-linear models are presented. In the fast-reaction zone (3- to 5-log reduction), the Arrhenius rate constant fits well at temperatures ranging from 120°C to 250°C on the basis of data from this work and the literature. Both biphasic and modified Weibull models are comparable to account for both the high and low rates of inactivation in terms of prediction accuracy and the number of parameters used. A unified representation of thermal resistance curves for a 3-log reduction and a 3Dvalue associated with endotoxin inactivation and microbial survival, respectively, is presented.

scholarly journals Chemical Fractionation Of Cu And Zn And Their Impacts On Microbial Properties In Slightly Contaminated Soils

2013 ◽  
Vol 3 (1) ◽  
pp. 20-25 ◽  
Author(s):  
Liu Aiju ◽  
Wang Honghai ◽  
Gao Peiling ◽  
Xu Hong-zhi
Keyword(s):  
Correlation Analysis ◽  
Contaminated Soils ◽  
Residual Fraction ◽  
Chemical Fractionation ◽  
Agricultural Field ◽  
Microbial Properties ◽  
Soil Microbial ◽  
Fractionation Analysis ◽  
Soil Microbial Properties ◽  
Cu And Zn

Chemical fractionation of Cu and Zn in bulk soil and its effects on soil microbial properties were determined in Cu and Zn contaminated soils (Cu: 35.57~46.37 mg·kg-1, Zn: 74.33~127.20 mg·kg-1) sampled from an agricultural field in outskirts of Zibo, China during the month of September, 2011. A sequential extraction technique (SET) was used for metals chemical fractionation analysis in soils and a correlation analysis was applied to determinate the effects of metal on soil microbial properties. Chemical speciation showed that Cu and Zn were mostly present in the residual fraction and their concentrations in the most labile fraction (acid soluble fraction) were the lowest in the investigated soils. However, the correlation analysis indicated that the labile forms of Cu/Zn, such as its acid soluble, reducible or oxidizable fractions, were usually significantly negatively correlated with the tested microbial activities at 0.05 or 0.01 probability levels. These results indicate that the metal labile fractions could exert an inhibitory effect on the soil microbial parameters even in the minor contaminated soils. Int. J. Agril. Res. Innov. & Tech. 3 (1): 20-25, June, 2013 DOI: http://dx.doi.org/10.3329/ijarit.v3i1.16045

The Occurrence of Inorganic Elements in Various Biofuels and Its Effect on the Formation of Melt Phases During Combustion

2002 ◽  
Author(s):  
Sharon Falcone Miller ◽  
Bruce G. Miller
Keyword(s):  
Circulating Fluidized Bed ◽  
Chemical Fractionation ◽  
State University ◽  
Pennsylvania State University ◽  
Cfb Boiler ◽  
Fuel Blends ◽  
Liquid Phases ◽  
Fractionation Analysis ◽  
Equilibrium Calculations ◽  
Significant Concentration

The Pennsylvania State University is performing a feasibility analysis on installing a circulating fluidized bed (CFB) boiler at Penn State’s University Park campus for cofiring multiple biofuels and other wastes with coal. Twenty feedstocks are being considered. Chemical fractionation analysis was performed on eleven of the fuels. It is the objective of this paper to present the results of characterizing selected biomass fuels via chemical fractionation. The chemical analysis of the fuels is then used to determine the net ash composition of possible fuel blends and their propensity to form liquid phases during combustion based on thermodynamic modeling. The FactSage equilibrium calculations suggest that a cofire of biofuels with an appropriate non-fouling coal should not pose any problems in a CFB system given that the coal makes up a majority of the thermal input. FactSage consistently predicted K2Si4O9(l) to be present at 1171K with biofuels having low aluminum levels and significant concentration of alkali earth elements. Only 10% of K2O present in a system was enough to result in the formation of K2Si4O9(l) at equilibrium that could compromise a CFB system.

Effects of Oxygen on Diamond Growth

1989 ◽  
Vol 162 ◽  
Author(s):  
Stephen J. Harris ◽  
Anita M. Weiner
Keyword(s):  
Gas Phase ◽  
Mole Fraction ◽  
Flow Reactor ◽  
Substrate Surface ◽  
Pyrolytic Carbon ◽  
Diamond Growth ◽  
Mass Spectral ◽  
Gas Phase Chemistry ◽  
Oxygen Addition ◽  
Phase Chemistry

ABSTRACTIn situ mass spectral measurements of the gas composition at the substrate surface were made during filament-assisted diamond growth. The input gases were various mixtures of CH4, O2, and H2 chosen in order to discern the effects of oxygen addition on diamond formation and growth. The gas phase chemistry was modeled as a 1-dimensional flow reactor, and the measured and calculated species mole fractions were in good agreement. The model was then used to estimate mole fractions of several atomic and radical species which could not be measured. We find that addition of O2 has only a small effect on the radical mole fractions. However, O2 can reduce the effective initial hydrocarbon mole fraction, which is important because higher quality diamond is grown at lower initial hydrocarbon mole fraction. Most importantly, perhaps, O2 addition leads to the formation of sufficient gas phase OH to remove non-diamond (pyrolytic) carbon from the film. Thus, O2 addition allows diamond films to be grown under composition and temperature conditions which otherwise would produce largely non-diamond carbon.

scholarly journals Methods of statistical analysis stationary kinetic model ideal mixing cell

2019 ◽  
Vol 80 (4) ◽  
pp. 133-137
Author(s):  
V. M. Zarochentsev ◽  
T. V. Kondratenko ◽  
A. K. Makoeva
Keyword(s):  
Statistical Analysis ◽  
Kinetic Model ◽  
Simulation Model ◽  
Flow Reactor ◽  
Mutual Influence ◽  
Chemical Interaction ◽  
Model Identification ◽  
Ideal Mixing ◽  
Perfect Mixing ◽  
Statistical Analysis Method

The article describes the statistical analysis method of the stationary kinetic model of perfect mixing cell which can be applied to devices using spatial combination of perfect mixing cells. A simulation model of interaction of two substances in a continuous-flow reactor of perfect mixing and graphs of chemical interaction of the substances is elaborated. A parametric simulation model identification method of least squares is conducted. The adequacy of the model obtained using the F-test and the hypothesis of heterogeneity of variances of random processes and functions is evaluated. The possible intervals of the linear zed equation coefficients using t-test are significance estimated coefficients are determined for the chosen form of the equation. The obtained values of the possible intervals are caused by in the stochastic factors simulation model by and mutual influence of deviations of different parameters. The calculation results are shown in Example 1 and Example 2. The relative error for output concentration was more than 10%. Therefore averaging over five repeated observations at each point in order to reduce the dispersion was performed. The averaged values of the parameters are suitable for the simulation and analysis processes. The results of research can be used for the development of mathematical modeling methods and analysis in fixed-chemical processes occurring in solutions.

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