scholarly journals A Slag Management Toolset for Determining Optimal Coal Gasification Temperatures

2016 ◽  
Vol 16 (4) ◽  
pp. 233-241
Author(s):  
Kyei‐Sing Kwong ◽  
James P. Bennett
Keyword(s):  
Coal Gasification ◽  
Scientific Basis ◽  
Slag Viscosity ◽  
Fluid Temperature ◽  
Operational Conditions ◽  
Temperature Range ◽  
Slag Chemistry ◽  
Operational Temperature ◽  
Optimal Temperature Range ◽  
Coal Slag

AbstractGasifier operation is an intricate process because of the complex relationship between slag chemistry and temperature, limitations of feedstock materials, and operational preference. High gasification temperatures increase refractory degradation, while low gasification temperatures can lead to slag buildup on the gasifier sidewall or exit, either of which are problematic during operation. Maximizing refractory service life and gasifier performance require finding an optimized operating temperature range which is a function of the coal slag chemistry and viscosity. Gasifier operators typically use a slag’s viscosity-temperature relationship and/or ash-fusion fluid temperature to determine the gasification temperature range. NETL has built a slag management toolset to determine the optimal temperature range for gasification of a carbon feedstock. This toolset is based on a viscosity database containing experimental data, and a number of models used to predict slag viscosity as a function of composition and temperature. Gasifier users typically have no scientific basis for selecting an operational temperature range for gasification, instead using experience to select operational conditions. The use of the toolset presented in this paper provides a basis for estimating or modifying carbon feedstock slags generated from ash impurities in carbon feedstock.

Lumped Parameter Modeling of a Magnetorheological Fluid Clutch

2006 ◽  
Author(s):  
John C. Ulicny ◽  
Daniel J. Klingenberg ◽  
Anthony L. Smith ◽  
Zongxuan Sun
Keyword(s):  
Mathematical Model ◽  
Physical Properties ◽  
Magnetorheological Fluid ◽  
Input Current ◽  
Fluid Composition ◽  
Fluid Temperature ◽  
Temperature Range ◽  
Lumped Parameter ◽  
Lumped Parameter Modeling ◽  
Fan Speed

A lumped-parameter mathematical model of an automotive magnetorheological (MR) fluid fan clutch was developed. This model is able to describe the average fluid temperature, average clutch temperature, and output fan speed as a function of time, input current, and fluid composition. The model also reproduces numerous features of fan operation observed experimentally and revealed a mechanism for some observed cases of hysteresis. However, it fails to capture certain other features which lead us to conclude that phenomena which are not included in the model, e.g., sedimentation and re-suspension, are important to the clutch behavior. In addition, the results indicate that certain physical properties need to be measured over a larger temperature range in order for the model to better predict the clutch behavior.

Electrically, Thermally, and Mechanically Anisotropic Gels with a Wide Operational Temperature Range

2021 ◽  
pp. 2110177
Author(s):  
Van Tron Tran ◽  
Md. Tariful Islam Mredha ◽  
Yoonseong Lee ◽  
Mitsugu Todo ◽  
Hongyun So ◽  
...  
Keyword(s):  
Temperature Range ◽  
Operational Temperature

scholarly journals Germination of Ocotea pulchella (Nees) Mez (Lauraceae) seeds in laboratory and natural restinga environment conditions

2009 ◽  
Vol 69 (3) ◽  
pp. 935-942 ◽  
Author(s):  
LA. Pires ◽  
VJM. Cardoso ◽  
CA. Joly ◽  
RR. Rodrigues
Keyword(s):  
Soil Moisture ◽  
Soil Moisture Content ◽  
Weibull Model ◽  
Limiting Factors ◽  
Base Temperature ◽  
Temperature Range ◽  
Optimal Temperature Range ◽  
Dry Soil ◽  
Moisture Conditions ◽  
Temperature Water

The germination response of Ocotea pulchella (Nees) Mez seeds to light, temperature, water level and pulp presence is introduced. The laboratory assays were carried out in germination chambers and thermal-gradient apparatus, whereas the field assays were performed in environments with distinct light, temperature and soil moisture conditions within a permanent parcel of Restinga forest of the Parque Estadual da Ilha do Cardoso, Cananéia, São Paulo. The seeds do not exhibit dormancy, they are non photoblastic, and a loss of viability in dry stored seeds can be related to a decrease in water content of the seed. The presence of the pulp and the flooded substratum influenced negatively the germination of O. pulchella seeds tested in the laboratory. Otherwise, light and temperature probably are not limiting factors of the germination of O. pulchella seeds in the natural environment of Restinga. The optimum temperature range for germination of Ocotea pulchella seeds was 20 to 32 ºC, the minimum or base temperature estimated was 11 ºC and the maximum ranged between 33 and 42 ºC. The isotherms exhibited a sigmoidal pattern well described by the Weibull model in the sub-optimal temperature range. The germinability of O. pulchella seeds in the understorey, both in wet and dry soil, was higher than in gaps. Germination was not affected by fluctuations in soil moisture content in the understorey environment, whereas in gaps, germination was higher in wet soils. Thus, the germination of this species involves the interaction of two or more factors and it cannot be explained by a single factor.

Measurement and Prediction of Low-Rank Coal Slag Viscosity

1984 ◽  
pp. 195-209 ◽  
Author(s):  
ROBERT C. STREETER ◽  
ERLE K. DIEHL ◽  
HAROLD H. SCHOBERT
Keyword(s):  
Low Rank ◽  
Slag Viscosity ◽  
Low Rank Coal ◽  
Coal Slag

scholarly journals Calcium‐Bearing Minerals Transformation during Underground Coal Gasification

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 708 ◽  
Author(s):  
Liu ◽  
Ma
Keyword(s):  
Coal Gasification ◽  
Ternary Phase Diagram ◽  
Energy Dispersive Spectrometer ◽  
Coal Ash ◽  
Scientific Basis ◽  
Experimental Results ◽  
Underground Coal Gasification ◽  
Morphological Transformation ◽  
Reaction Conditions ◽  
High Calcium

Calcium‐bearing minerals are one of the main typical minerals in coal and coal ash. In the process of coal thermal conversion, calcium‐bearing minerals undergo different morphological transformation in which the reaction temperature, pressure, and atmosphere are important factors affecting their transformation. The reaction process of underground coal gasification (UCG) could be clearly divided into pyrolysis, reduction, and oxidation and the typical calcium‐bearing minerals are expected to indicate the actual reaction conditions of UCG. A high‐calcium coal, Zhundong coal, was used in this research. The products of UCG were prepared and the minerals were identified by X‐ray diffraction (XRD) and a scanning electron microscope coupled with an energy‐dispersive spectrometer (SEM‐EDS). The thermodynamic calculation was used to assist in understanding the transformation behaviors of calcium‐bearing minerals. The experimental results show that the calcium‐bearing mineral is gradually converted from gypsum (CaSO4·2H2O) in the raw coal into anhydrite (CaSO4) during the pyrolysis process. In the reduction stage, anhydrite reacts with the reducing gas (CO) to produce oldhamite (CaS), and the oldhamite is stably present in the reduction ash. During the oxidation process, oldhamite is first transformed into CaSO4, and then CaSO4 is converted into CaO. Finally, CaO reacts with Al2O3 and SiO2 to produce gehlenite (Ca2Al2SiO7) at 1100 °C. As the oxidation temperature rises to 1400 °C, gehlenite is transformed into the thermodynamically stable anorthite (CaAl2Si2O8). With the further progress of the reaction, anorthite will co‐melt with iron‐bearing minerals above 1500 °C. The ternary phase diagram of SiO2–Al2O3–CaO system proves that anorthite and gehlenite are the typical high‐temperature calcium‐bearing minerals when the mole fraction of SiO2 is higher than 0.6. Moreover, the gehlenite is converted to anorthite with the temperature rise, which is consistent with experimental results. This study provides a scientific basis for understanding the UCG reaction conditions.

Effects of temperature on growth of north-east Pacific moon jellyfish ephyrae, Aurelia labiata (Cnidaria: Scyphozoa)

2005 ◽  
Vol 85 (3) ◽  
pp. 569-573 ◽  
Author(s):  
Chad L. Widmer
Keyword(s):  
Good Condition ◽  
Bell Diameter ◽  
Optimal Temperature ◽  
Moon Jellyfish ◽  
Poor Condition ◽  
Temperature Range ◽  
North East ◽  
East Pacific ◽  
Optimal Temperature Range ◽  
Effects Of Temperature

The effects of ten different water temperatures on the growth of newly released ephyrae of Aurelia labiata were explored. Ephyrae grown at 21°C showed the greatest growth, increasing in bell diameter from about 4.0 mm to 14.5 mm in 14 days and remained in good condition for the duration of the experiment. Ephyrae subjected to other temperatures grew at different rates. Ephyrae maintained at 8°C gradually decreased in size during the experiment, shrinking in bell diameter from about 4.0 mm to 3.8 mm by day 14, but remained in apparent good condition. Ephyrae reared at 22.5°C and above everted their bells, were in poor condition, and were unable to feed or swim effectively by about day ten. In this study the optimal temperature range for rearing A. labiata ephyrae was 12°C—21°C, which corresponds with the reported range for this species.

Applicability of Pump Models for Varying Operational Conditions

2003 ◽  
Author(s):  
Heikki O. J. Kauranne ◽  
Jyrki T. Kajaste ◽  
Asko U. Ellman ◽  
Matti T. Pietola
Keyword(s):  
Rotational Speed ◽  
Operating Conditions ◽  
Fluid Temperature ◽  
Limited Information ◽  
Operational Conditions ◽  
Axial Piston Pumps ◽  
Pump Construction ◽  
Temperature And Pressure ◽  
Axial Piston ◽  
Type Pressure

It is commonly known that the characteristics of a fluid power pump depend on pump type, pressure, rotational speed and displacement. But in addition to these, also all the other parameters or factors associated with the operating conditions may have a significant effect on the characteristics. The most important of these are the pump construction and size, operating point temperature and the characteristics of the oil, which also depend on temperature and pressure. The aim of this study is to show the effects that the varying operational conditions have on the characteristics of a axial piston pump, to compare the measured characteristics with other published characteristics of axial piston pumps and to study the capability of pump models to represent these characteristics. The results include information of the effects of fluid temperature, type of fluid and the setting value of the displacement on the pump characteristics along with the effects of pressure and rotational speed. The sensitivity of the pump to each of the parameters is discussed. The effect of limited information of pump characteristics on the reliability of simulation results is studied using the Schlo¨sser models.

Temperatures for seedling emergence of tropical perennial grasses

2017 ◽  
Vol 68 (5) ◽  
pp. 493
Author(s):  
M. K. Egan ◽  
S. P. Boschma ◽  
S. Harden ◽  
C. A. Harris ◽  
C. Edwards
Keyword(s):  
Seedling Emergence ◽  
Perennial Grasses ◽  
Sowing Time ◽  
Rhodes Grass ◽  
Temperature Range ◽  
South Wales ◽  
Optimal Temperature Range ◽  
Digitaria Eriantha ◽  
Chloris Gayana ◽  
Rainfall Region

A growth-cabinet study was conducted to determine the optimum temperature range for seedling emergence of seven tropical grasses commonly sown in the frost-prone, summer-dominant rainfall region of inland northern New South Wales. The grasses were Bothriochloa bladhii subsp. glabra (forest bluegrass) cv. Swann, Bothriochloa insculpta (creeping bluegrass) cv. Bisset, Chloris gayana (Rhodes grass) cv. Katambora, Digitaria eriantha (digit grass) cv. Premier, Panicum coloratum var. makarikariense (makarikari grass) cv. Bambatsi, and Megathyrsus maximus (panic) cvv. Gatton and Megamax 059. Six constant temperatures were used, ranging from 10°C to 35°C in 5°C increments. Katambora Rhodes grass was the only grass to emerge at 10°C; seedlings of all grasses emerged at temperatures >10°C. Optimal temperature range for emergence varied between species, falling into three groups: low (Bisset creeping bluegrass 16−22°C); intermediate (Premier digit grass 21−32°C, Swann forest bluegrass 23−31°C, Megamax 059 panic 23−35°C, Gatton panic 24−32°C); and high (Bambatsi makarikari grass 24−35°C, Katambora Rhodes grass 24−35°C). The temperature range at which 50% of optimum emergence occurred was 12−14°C for Katambora Rhodes grass, Bisset creeping blue and Premier digit, and 17−18°C for the panic grasses, Swann forest bluegrass and Bambatsi makarikari grass. These temperatures provide options for sowing earlier in spring or later in summer–autumn and may assist development of sowing time options in new environments and provide insight into competition between species.

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