scholarly journals Sulphur and vanadium-induced high-temperature corrosion behaviour of different regions of SMAW weldment in ASTM SA 210 GrA1 boiler tube steel

2020 ◽  
Vol 39 (1) ◽  
pp. 256-260
Author(s):  
Ravindra Kumar ◽  
Vinay Kumar Tewari ◽  
Satya Prakash
Keyword(s):  
High Temperature ◽  
Weld Metal ◽  
Power Plants ◽  
Corrosion Behaviour ◽  
Thermal Power ◽  
High Temperature Corrosion ◽  
Tube Steel ◽  
Low Grade ◽  
Shielded Metal Arc Welding ◽  
X Ray

AbstractCorrosion at elevated temperature is a serious problem in running thermal power plants because of the use of low-grade fuels that contain substantial amounts of sulphur, vanadium, sodium etc. This article reports the high-temperature corrosion of weld metal and heat-affected zone (HAZ) of shielded metal arc-welding (SMAW) weldment in GrA1 steel in a molten salt (Na2SO4–60% V2O5) environment at 900°C under cyclic conditions. The thermogravimetric technique was used to observe the kinetics of corrosion. The corrosion products formed on weld metal and HAZ of SMAW welded steel were characterized by scanning electron microscopy with energy dispersive X-ray analysis (EDX) and X-ray diffraction pattern. Weld metal was found to oxidize at a higher rate than those of HAZ due to the presence of sodium and sulphur in the inner oxide scale as confirmed by EDX, and this leads to high corrosion rate (in terms of weight gain).

High temperature corrosion behaviour of aluminised FC 25 cast iron using pack cementation

2019 ◽  
Vol 66 (2) ◽  
pp. 236-241 ◽  
Author(s):  
Somrerk Chandra-Ambhorn ◽  
Neramit Krasaelom ◽  
Tummaporn Thublaor ◽  
Sirichai Leelachao
Keyword(s):  
Cast Iron ◽  
High Temperature ◽  
Corrosion Behaviour ◽  
Mass Gain ◽  
High Temperature Corrosion ◽  
Pack Cementation ◽  
X Ray Diffraction ◽  
Content Type ◽  
X Ray ◽  
Seat Insert

Purpose This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy. Design/methodology/approach Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation. Findings The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation. Originality/value Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts.

Experimental Analysis of Hot Corrosion Behaviour of some Composite Coatings on Boiler Steel at Elevated Temperature

2021 ◽  
Vol 41 ◽  
pp. 43-54
Author(s):  
Prince Puri ◽  
Khushdeep Goyal ◽  
Rakesh Goyal ◽  
Bal Krishan
Keyword(s):  
Hot Corrosion ◽  
Power Plants ◽  
Corrosion Behaviour ◽  
Composite Coatings ◽  
Thermal Power ◽  
Tube Steel ◽  
X Ray Diffraction ◽  
Boiler Steel ◽  
Boiler Tube Steel ◽  
Silicon Tube

Hot corrosion is the main reason of failure of boiler tubes used at high temperature in thermal power plants. This paper is an attempt to investigate the effect of different composite coatings on boiler tube steel in corrosive environment of Na2SO4 – 60%V2O5 at 900°C for 50 cycles. The coatings have been deposited with high velocity oxy fuel process. The samples were exposed to hot corrosion in a Silicon tube furnace at 900°C for 50 cycles. The kinetics of corrosion behaviour were analysed by the weight gain measurements after each cycle. Corrosion products were analysed with weight change statistics, X-ray diffraction, and scanning electron microscopy. It is found that 100Cr3C2 composite coatings provided the higher resistance to corrosion as compared to other types of coatings. Cr carbide layer was formed on the surface and these layers provided the protection from hot corrosion.

scholarly journals Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1267
Author(s):  
David Längauer ◽  
Vladimír Čablík ◽  
Slavomír Hredzák ◽  
Anton Zubrik ◽  
Marek Matik ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Combustion ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Product Analysis ◽  
Coal Combustion Products ◽  
X Ray ◽  
Wide Range ◽  
Silica Alumina

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al2O3, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

High-temperature corrosion behaviour of plasma sprayed Gd2SrAl2O7 coatings by V2O5 at 700-1200ºC

2021 ◽  
pp. 110032
Author(s):  
Jieyan Yuan ◽  
Shujuan Dong ◽  
Jianing Jiang ◽  
Longhui Deng ◽  
Xueqiang Cao
Keyword(s):  
High Temperature ◽  
Corrosion Behaviour ◽  
High Temperature Corrosion ◽  
Plasma Sprayed

scholarly journals Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants: Part II—Effect of Environment and Outlook

2019 ◽  
Vol 28 (8) ◽  
pp. 1789-1850 ◽  
Author(s):  
Esmaeil Sadeghi ◽  
Nicolaie Markocsan ◽  
Shrikant Joshi
Keyword(s):  
High Temperature ◽  
Thermal Spray ◽  
Power Plants ◽  
High Temperature Corrosion ◽  
Thermal Spray Coatings ◽  
Current Status ◽  
Comprehensive Overview ◽  
Biomass Waste ◽  
Corrosion Resistant ◽  
Spray Coatings

Abstract High-temperature corrosion of critical components such as water walls and superheater tubes in biomass/waste-fired boilers is a major challenge. A dense and defect-free thermal spray coating has been shown to be promising to achieve a high electrical/thermal efficiency in power plants. The field of thermal spraying and quality of coatings have been progressively evolving; therefore, a critical assessment of our understanding of the efficacy of coatings in increasingly aggressive operating environments of the power plants can be highly educative. The effects of composition and microstructure on high-temperature corrosion behavior of the coatings were discussed in the first part of the review. The present paper that is the second part of the review covers the emerging research field of performance assessment of thermal spray coatings in harsh corrosion-prone environments and provides a comprehensive overview of the underlying high-temperature corrosion mechanisms that lead to the damage of exposed coatings. The application of contemporary analytical methods for better understanding of the behavior of corrosion-resistant coatings is also discussed. A discussion based on an exhaustive review of the literature provides an unbiased commentary on the advanced accomplishments and some outstanding issues in the field that warrant further research. An assessment of the current status of the field, the gaps in the scientific understanding, and the research needs for the expansion of thermal spray coatings for high-temperature corrosion applications is also provided.

scholarly journals Experimental study of the thermochemical treatment of the low-grade coal prior to boiler combustion at coal-fired power station

2019 ◽  
Vol 109 ◽  
pp. 00119
Author(s):  
Volodymyr Yemelianenko ◽  
Vitalii Pertsevyi ◽  
Oleksandr Zhevzhyk ◽  
Iryna Potapchuk ◽  
Oleksandr Lutai
Keyword(s):  
Experimental Study ◽  
Power Plants ◽  
Thermal Power ◽  
Thermochemical Treatment ◽  
Gas Pressure ◽  
Pulverized Coal ◽  
Time Range ◽  
Low Grade ◽  
Boiler Furnace ◽  
Coal Fuel

Analysis of the perspectives of the coal fuel for thermal power plants is carried out. The necessity of the experimental study for temperature measurement in the boiler furnace. The results of the experimental study are presented: temperature change over time at the burner outlet for different constant pressure value of the backlighting gas, dependence of the temperature at the burner outlet from the backlighting gas pressure for constant concentration value of pulverized coal in coal-air mixture, dependence of the temperature at the burner outlet from the concentration of pulverized coal in coal-air mixture for constant value of the backlighting gas pressure, temperature measurements for constant backlighting gas pressure value, constant value of the concentration of pulverized coal in coal-air mixture when plasmatron is switched and operates for some time range. The results of the study could be applied to the solid fuel treatment for different thermal units.

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