scholarly journals Kinetics of the σ Phase Precipitation in Respect of Erosion-corrosion Wear of Duplex Cast Steel

2014 ◽  
Vol 14 (1) ◽  
pp. 17-20 ◽  
Author(s):  
A. Brodziak-Hyska ◽  
Z. Stradomski ◽  
C. Kolan
Keyword(s):  
Flue Gas ◽  
Cast Steel ◽  
Strengthening Mechanism ◽  
Operating Conditions ◽  
Solid Particles ◽  
Corrosion Wear ◽  
Phase Precipitation ◽  
Σ Phase ◽  
Erosion Corrosion ◽  
Kinetics Of

Abstract The examined material comprised two grades of corrosion-resistant cast steel, namely GX2CrNiMoN25-6-3 and GX2CrNiMoCuN25-6-3- 3, used for example in elements of systems of wet flue gas desulphurisation in power industry. The operating conditions in media heated up to 70°C and containing Cl' and SO4 ions and solid particles produce high erosive and corrosive wear.The work proposes an application of the σ phase as a component of precipitation strengthening mechanism in order to increase the functional properties of the material. The paper presents the results of examination of the kinetics of σ phase precipitation at a temperature of 800°C and at times ranging from 30 to 180 minutes. Changes in the morphology of precipitates of the σ phase were determined using the value of shape factor R. Resistance to erosion-corrosion wear of duplex cast steel was correlated with the kinetics of sigma phase precipitating.

Eutectoid Decomposition of δ-Ferrite in Ferritic-Austenitic Duplex Cast Steel - Structural and Morphological Study

2012 ◽  
Vol 706-709 ◽  
pp. 2314-2319 ◽  
Author(s):  
D. Dyja ◽  
Z. Stradomski ◽  
Cezary Kolan ◽  
Grzegorz Stradomski
Keyword(s):  
Annealing Temperature ◽  
Volume Fraction ◽  
Cast Steel ◽  
Optical Microscope ◽  
Rapid Progress ◽  
Phase Precipitation ◽  
X Ray ◽  
Σ Phase ◽  
Δ Ferrite ◽  
Surface Development

The influence of time and temperature of ageing on the σ-phase morphology in ferritic-austenitic cast steel have been investigated in this study. The morphology and quantity of the σ-phase were analyzed by using optical microscope, X-ray diffractometry, scanning electron microscope and image analysis, respectively. The annealing temperature has a significant influence on the morphology, volume fraction and the dynamics of σ-phase precipitation. Surface development of the σ-phase decreases from R=4.3, for the cast steel annealed at 700°C to R=2.4 for the cast steel annealed at 900°C, and the volume fraction Vvσ from 50.8% to 26.5%, respectively. The most rapid progress of δ → σ + γ’ transformation was observed at 800°C.

scholarly journals Phase stability and kinetics of σ-phase precipitation in CrMnFeCoNi high-entropy alloys

2018 ◽  
Vol 161 ◽  
pp. 338-351 ◽  
Author(s):  
G. Laplanche ◽  
S. Berglund ◽  
C. Reinhart ◽  
A. Kostka ◽  
F. Fox ◽  
...  
Keyword(s):  
Phase Stability ◽  
High Entropy Alloys ◽  
Phase Precipitation ◽  
Σ Phase ◽  
High Entropy ◽  
Kinetics Of

Could biomass-fueled boilers be operated at higher steam temperatures? Part 3: Initial analysis of costs and benefits

TAPPI Journal ◽  
2014 ◽  
Vol 13 (8) ◽  
pp. 65-78 ◽  
Author(s):  
W.B.A. (SANDY) SHARP ◽  
W.J. JIM FREDERICK ◽  
JAMES R. KEISER ◽  
DOUGLAS L. SINGBEIL
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Superheated Steam ◽  
Black Liquor ◽  
Simulation Software ◽  
Operating Conditions ◽  
Costs And Benefits ◽  
Steam Generation ◽  
Fireside Corrosion ◽  
Corrosion Resistant

The efficiencies of biomass-fueled power plants are much lower than those of coal-fueled plants because they restrict their exit steam temperatures to inhibit fireside corrosion of superheater tubes. However, restricting the temperature of a given mass of steam produced by a biomass boiler decreases the amount of power that can be generated from this steam in the turbine generator. This paper examines the relationship between the temperature of superheated steam produced by a boiler and the quantity of power that it can generate. The thermodynamic basis for this relationship is presented, and the value of the additional power that could be generated by operating with higher superheated steam temperatures is estimated. Calculations are presented for five plants that produce both steam and power. Two are powered by black liquor recovery boilers and three by wood-fired boilers. Steam generation parameters for these plants were supplied by industrial partners. Calculations using thermodynamics-based plant simulation software show that the value of the increased power that could be generated in these units by increasing superheated steam temperatures 100°C above current operating conditions ranges between US$2,410,000 and US$11,180,000 per year. The costs and benefits of achieving higher superheated steam conditions in an individual boiler depend on local plant conditions and the price of power. However, the magnitude of the increased power that can be generated by increasing superheated steam temperatures is so great that it appears to justify the cost of corrosion-mitigation methods such as installing corrosion-resistant materials costing far more than current superheater alloys; redesigning biomassfueled boilers to remove the superheater from the flue gas path; or adding chemicals to remove corrosive constituents from the flue gas. The most economic pathways to higher steam temperatures will very likely involve combinations of these methods. Particularly attractive approaches include installing more corrosion-resistant alloys in the hottest superheater locations, and relocating the superheater from the flue gas path to an externally-fired location or to the loop seal of a circulating fluidized bed boiler.

Kinetics of phase precipitation in Al-Mg-Si alloys subjected to equal-channel angular pressing during subsequent heating

2021 ◽  
pp. 160583
Author(s):  
N.R. Bochvar ◽  
O.V. Rybalchenko ◽  
N. Yu. Tabachkova ◽  
G.V. Rybalchenko ◽  
N.P. Leonova ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Phase Precipitation ◽  
Angular Pressing ◽  
Subsequent Heating ◽  
Kinetics Of

Influence of the spray drying operating conditions on the estimated drying kinetics of emulsion single droplets and the properties of microencapsulated chia oil

2021 ◽  
Vol 383 ◽  
pp. 302-317
Author(s):  
M. Gabriela Bordón ◽  
Noelia P.X. Alasino ◽  
Vanina Martínez ◽  
Regina Gauna Peter ◽  
Ramiro Iturralde ◽  
...  
Keyword(s):  
Spray Drying ◽  
Drying Kinetics ◽  
Operating Conditions ◽  
Single Droplets ◽  
Kinetics Of ◽  
Chia Oil

Investigation of the different particle size dust releases from rigid filter candles during pulse-jet cleaning

2021 ◽  
pp. 095440622110179
Author(s):  
Xin Luan ◽  
Zhongli Ji ◽  
Longfei Liu ◽  
Ruifeng Wang
Keyword(s):  
Particle Size ◽  
Critical Role ◽  
Operating Conditions ◽  
Solid Particles ◽  
Dust Particles ◽  
Cleaning Efficiency ◽  
Term Operation ◽  
Cleaning Performance ◽  
Experimental Apparatus ◽  
Pulse Jet

Rigid filters made of ceramic or metal are widely used to remove solid particles from hot gases at temperature above 260 °C in the petrochemical and coal industries. Pulse-jet cleaning of fine dust from rigid filter candles plays a critical role in the long-term operation of these filters. In this study, an experimental apparatus was fabricated to investigate the behavior of a 2050 mm filter candle, which included monitoring the variation of pressure dynamic characteristics over time and observing the release of dust layers that allowed an analysis of the cleaning performance of ISO 12103-1 test dusts with different particle size distributions. These results showed the release behavior of these dusts could be divided into five stages: radial expansion, axial crack, flaky release, irregular disruption and secondary deposition. The cleaning performance of smaller sized dust particles was less efficient as compared with larger sized dust particles under the same operating conditions primarily because large, flaky-shaped dust aggregates formed during the first three stages were easily broken into smaller, dispersed fragments during irregular disruption that forced more particles back to the filter surface during secondary deposition. Also, a “low-pressure and long-pulse width” cleaning method improved the cleaning efficiency of the A1 ultrafine test dust from 81.4% to 95.9%.

Kinetic model for calcium sulfate α-hemihydrate produced hydrothermally from gypsum formed by flue gas desulfurization

2015 ◽  
Vol 48 (3) ◽  
pp. 827-835 ◽  
Author(s):  
Mingliang Tang ◽  
Xuerun Li ◽  
Yusheng Shen ◽  
Xiaodong Shen
Keyword(s):  
Flue Gas ◽  
Calcium Sulfate ◽  
High Performance ◽  
Transformation Process ◽  
Flue Gas Desulfurization ◽  
Synthesis Process ◽  
Stable Phase ◽  
Hydrothermal Conditions ◽  
Simple Method ◽  
Kinetics Of

Modeling of the kinetics of the synthesis process for calcium sulfate α-hemihydrate from gypsum formed by flue gas desulfurization (FGD) is important to produce high-performance products with minimal costs and production cycles under hydrothermal conditions. In this study, a model was established by horizontally translating the obtained crystal size distribution (CSD) to the CSD of the stable phase during the transformation process. A simple method was used to obtain the nucleation and growth rates. A nonlinear optimization algorithm method was employed to determine the kinetic parameters. The model can be successfully used to analyze the transformation kinetics of FGD gypsum to α-hemihydrate in an isothermal batch crystallizer. The results showed that the transformation temperature and stirring speed exhibit a significant influence on the crystal growth and nucleation rates of α-hemihydrate, thus altering the transformation time and CSD of the final products. The characteristics obtained by the proposed model can potentially be used in the production of α-hemihydrate.

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