Hot corrosion of alloy 617 OCC in simulated coal ash environment encountered in USC power plants

2020 ◽  
Author(s):  
P.R. Hari ◽  
N. Arivazhagan ◽  
M. Nageswara Rao ◽  
A.H.V. Pavan
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Coal Ash ◽  
Alloy 617

Behaviour of Alloy 617 OCC Under Hot Corrosion Conditions Encountered in Boilers in A-USC Power Plants

2019 ◽  
Vol 72 (6) ◽  
pp. 1511-1514 ◽  
Author(s):  
P. R. Hari ◽  
N. Arivazhagan ◽  
M. Nageswara Rao ◽  
A. H. V. Pavan
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Alloy 617

Hot Corrosion of Alloy 617 OCC in Simulated USC Power Plant Environment

2018 ◽  
Vol 941 ◽  
pp. 1748-1753 ◽  
Author(s):  
N. Arivazhagan ◽  
P.R. Hari ◽  
M. Nageswara Rao ◽  
A.H.V. Pavan
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Corrosion Behaviour ◽  
Metal Loss ◽  
Gas Mixture ◽  
Degradation Mechanisms ◽  
Fireside Corrosion ◽  
Alloy 617 ◽  
Plant Environment ◽  
Inconel 617

Alloy 617 OCC, a variant of INCONEL 617 with optimised chemical composition, has been produced in India for manufacture of superheater and reheater tubing in boilers operating in advanced ultrasupercritical (A-USC) power plants. The tubing encounters intense hot corrosion conditions during service. The present study deals with hot corrosion behaviour of 617 OCC in A-USC environment. The environment occurring in A-USC plants was simulated in the laboratory by exposing the material coated with a mixture of salts at 700°C in a flowing gas mixture. For use in A-USC boiler technology, the metal loss due to fireside corrosion of the material should be less than 2 mm in 200,000 hours. The loss obtained in the present study was nearly 5 times this value. The corrosion processes were studied using SEM/EDAX, XRD and thermogravimetry. The degradation mechanisms coming into play, disqualifying the material for use in A-USC plants, would be discussed.

scholarly journals Influence of the Size of Coal Ash FAU Zeolites Used as Dopants on the Sensing Properties of Nb2O5 Thin Films

2020 ◽  
Vol 2 (1) ◽  
pp. 3
Author(s):  
Katerina Lazarova ◽  
Silviya Boycheva ◽  
Marina Vasileva ◽  
Denitza Zgureva ◽  
Tsvetanka Babeva
Keyword(s):  
Thin Films ◽  
Power Plants ◽  
Thermal Power ◽  
Coal Ash ◽  
Reflectance Spectra ◽  
Sensing Properties ◽  
Volatile Organic ◽  
Coating Method ◽  
Reflectance Measurements

In this study, solid waste from coal combustion in thermal power plants (TPPs) was used for the synthesis of zeolite Na-X samples. They were prepared by the long-term alkaline atmospheric conversion of coal ash collected from the electrostatic precipitators in the TPP “AES Galabovo”. When used in the form of thin films/layers, the optical detection of volatile organic compounds (VOCs) is possible due to a change in their reflectance spectra and color. In order to improve the sensing properties of synthesized zeolites, they were wet milled for 60 s and both milled and unmilled zeolites were used as dopants for the niobium oxide matrix in the form of thin films deposited by the spin-coating method on a silicon substrate. The surface morphology and structure of both zeolite powders were studied by scanning electron microscopy, while their size was determined by dynamic light scattering (DLS) spectra. Optical constants (refractive index, n, and extinction coefficient, k) and the thickness of the films were calculated from reflectance measurements. The change in the reflection coefficient ∆R of the films was determined from measured reflectance spectra prior to and after exposure to probe acetone molecules. An increase in the reaction of the films with milled zeolites to acetone, compared to the samples with unmilled zeolites, is demonstrated.

Interaction of hot corrosion and creep in Alloy 617

2016 ◽  
Vol 66 ◽  
pp. 373-384 ◽  
Author(s):  
Amin Homaeian ◽  
Mostafa Alizadeh
Keyword(s):  
Hot Corrosion ◽  
Alloy 617

Influence of Hot Corrosion on Local Mechanical Properties of HVOF Sprayed Coating Based on NiCrBSi Alloy

2015 ◽  
Vol 662 ◽  
pp. 123-126
Author(s):  
Jan Schubert ◽  
Zdeněk Česánek ◽  
Olga Bláhová
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Operating Temperature ◽  
Steam Turbines ◽  
Alternative Technologies ◽  
Before And After ◽  
Nicrbsi Coating ◽  
Mechanical And Microstructural Properties ◽  
Sprayed Coating ◽  
Areas Of Protection

Ongoing increase in demands on efficiency of power plants and other facilities leads to increased interest of new progressive materials and technologies. One of the modern methods which lead to enhancement of surface properties is application of coatings on surface of components composed of less quality materials. Commonly used methods protecting components are based on some form of heat treatment. The current pressure on increasing operating temperatures for enhanced performance of steam turbines caused elevation of operating temperature at limit of the applicability of commonly used protections. From this reasons the demand for using an alternative technologies which would provide such a desired protection rises rapidly. One of the key areas of protection in such environment is protection against hot temperature corrosion. Possible solution can be found in application of coatings based on alloys and cermets prepared by HVOF technology. This paper examines local mechanical and microstructural properties of NiCrBSi coating after exposition to extremely severe hot corrosion environment. Furthermore, the nanoindentation measurements of NiCrBSi coating were performed before and after the corrosion test. In this case the mixture of salts composed from 59% Na2(SO)4 with 34.5% KCl and 6.5% NaCl was used. Temperature of test was set on 525°C and 575°C. Duration of exposition to hot corrosion environment was 168 hours in autoclave.

scholarly journals Leaching Characteristics of Low Concentration Rare Earth Elements in Korean (Samcheok) CFBC Bottom Ash Samples

2019 ◽  
Vol 11 (9) ◽  
pp. 2562 ◽  
Author(s):  
Lai Tuan ◽  
Thriveni Thenepalli ◽  
Ramakrishna Chilakala ◽  
Hong Vu ◽  
Ji Ahn ◽  
...  
Keyword(s):  
Rare Earth ◽  
Power Plants ◽  
Circulating Fluidized Bed ◽  
Bottom Ash ◽  
Coal Ash ◽  
Low Grade ◽  
Fluidized Bed Combustion ◽  
Basic Characteristics ◽  
Mass Volume ◽  
Circulating Fluidized Bed Combustion

Coal-derived power comprises over 39% of the world’s power production. Therefore, a mass volume of coal combustion byproducts are generated and shifted the extra burden onto the economy and environment. Circulating fluidized bed combustion (CFBC) has been found to be a clean and ultimate technology for Korea’s coal-fired power plants to have effective power generation from low-grade imported coal with reduced emissions. Efforts have been made to broaden the utilization of CFBC coal ash, and to promote sustainable development of CFBC technology. Investigations provided numerous evidences for coal ash to be a potential deposit for rare earths reclamation. However, the basic characteristics and the methods of rare earth mining from the CFBC bottom ash lack detailed understanding and are poorly reported. This study highlighted an insight of the CBFC bottom ash with respect to REEs concentration. Moreover, agents were tested as a means for leaching REEs from Samcheok CFBC bottom ash. The leaching tests were performed in relation to variations in concentration, time and temperature. The results were applied to identify suitable processes to leach REEs from the ash and clarify the potential valuation of CFBC bottom ash. The leaching conditions attained by ANOVA analysis for hydrochloric concentration, temperature, and time of 2 mol L−1, 80 °C, and 12 h, were found to provide a maximum extraction of yttrium, neodymium and dysprosium of 62.1%, 55.5% and 65.2%, respectively.

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