Improving the hot corrosion resistance of boiler tube steels by detonation gun sprayed coatings in actual boiler of thermal power plant

2019 ◽  
Vol 66 (4) ◽  
pp. 394-402
Author(s):  
Vikramjit Singh ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Power Plants ◽  
Thermal Power ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Detonation Gun ◽  
Sprayed Coatings

Purpose This paper aims to investigate the hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings, deposited on T11, P91 boiler steels by detonation gun spray coating (D-Gun) process to enhance high temperature corrosion resistance. Design/methodology/approach Hot corrosion studies were conducted in secondary super heater zone of boiler at 900 °C for 10 cycles on bare and D-Gun coated steel specimens. The microhardness and porosity values of as-sprayed coatings were measured before exposing the specimens in the boiler environment. Each cycle consisted 100 h of heating in the boiler environment followed by 20 min of cooling in air. The weight change measurements were performed after each cycle to establish the kinetics of corrosion using thermogravimetric technique. X-ray diffraction, SEM techniques were used to analyze the corroded specimens. Findings Uncoated boiler steel experienced higher weight loss. The Cr3C2-NiCr coating was found to be more protective than Ni-Cr coating. The phases revealed the formation of oxide scale on coated specimens, mainly consist of nickel and chromium, which are reported to be protective against the hot corrosion. Originality/value There is very limited reported literature on hot corrosion behavior of Ni-Cr and Cr3C2-NiCr coatings deposited on the T11 and P91 substrates by detonation gun (D-gun) spray technique. T11 and P91 alloy steels have been chosen for this study because these two alloys are used to manufacture boiler tubes used in Indian thermal power plants.

Characterization and hot corrosion behavior of D-gun sprayed Cr2O3-75% Al2O3 coated ASTM-SA210-A1 boiler steel in molten salt environment

2017 ◽  
Vol 64 (5) ◽  
pp. 515-528 ◽  
Author(s):  
Amita Rani ◽  
Niraj Bala ◽  
C.M. Gupta
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Molten Salt ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Degradation Mechanism ◽  
Effective Diffusion ◽  
Boiler Steel ◽  
Content Type ◽  
Scanning Electron

Purpose Hot corrosion is the major degradation mechanism of failure of boiler and gas turbine components. The present work aims to investigate the hot corrosion resistance of detonation gun sprayed (D-gun) Cr2O3-75 per cent Al2O3 ceramic coating on ASTM-SA210-A1 boiler steel. Design/methodology/approach The coating exhibits nearly uniform, adherent and dense microstructure with porosity less than 0.8 per cent. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of bare and coated boiler steel in molten salt environment (Na2SO4-60 per cent V2O5) at high temperature 900°C for 50 cycles. The corrosion products are analyzed by using X-ray diffraction, scanning electron microscopy (SEM) and field emission scanning electron microscope/energy-dispersive analysis (EDAX) to reveal their microstructural and compositional features for elucidating the corrosion mechanisms. Findings During investigations, it was found that the Cr2O3-75 per cent Al2O3 coating on Grade A-1 boiler steel is found to be very effective in decreasing the corrosion rate in the molten salt environment at 900°C. The coating has shown lesser weight gains along with better adhesiveness of the oxide scales with the substrate till the end of the experiment. Thus, coatings serve as an effective diffusion barrier to preclude the diffusion of oxygen from the environment into the substrate boiler steel. Research limitations/implications Therefore, it is concluded that the better hot corrosion resistance of the coating is due to the formation of desirable microstructural features such as very low porosity, uniform fine grains and the flat splat structures in the coating; as compared to the bare substrate under cyclic conditions. Practical implications This research is useful for coal-fired boilers and other power plant boilers. Social implications This research is useful for power generation plants. Originality/value There is no reported literature on hot corrosion behavior of Cr2O3-75 per cent Al2O3 coating deposited on the selected substrates by D-gun spray technique. The present work has been focused to study the influence of the Cr2O3-75 per cent Al2O3 coating developed with D-gun spraying technique on high temperature corrosion behavior of ASTM-SA210-A-1 boiler steel in an aggressive environment of Na2SO4-60 per cent V2O5 molten salt at 900°C under cyclic conditions.

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.

An investigation of corrosion resistance of HVOF coated ASME SA213 T91 boiler steel in an actual boiler environment

2017 ◽  
Vol 64 (5) ◽  
pp. 499-507 ◽  
Author(s):  
Varinder Pal Singh Sidhu ◽  
Khushdeep Goyal ◽  
Rakesh Goyal
Keyword(s):  
Corrosion Resistance ◽  
Original Research ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
Boiler Steel ◽  
Content Type ◽  
Boiler Environment ◽  
Spraying Process ◽  
Minimum Resistance

Purpose This paper aims to use the high-velocity oxy fuel (HVOF) spraying process for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91 to study the corrosion resistance of these coatings in an actual boiler environment. Design/methodology/approach The HVOF spraying process was used for depositing 93(WC–Cr3C2)–7Ni, 75Cr3C2–25NiCr, 83WC–17CO and 86WC–10CO–4Cr coatings on ASME SA213 T91. All the coatings obtained are found to be uniform, dense and having thickness between 200 and 250 μm. All the coatings were exposed in an actual boiler environment at 900°C temperature for 10 cycles. Each cycle consisted of 100 h heating followed by 1 h cooling at ambient conditions. X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy techniques were used to analyse corrosion products. Findings All the coated samples were found to be having higher corrosion resistance than the uncoated samples. Among coated specimens, 93(WC–Cr3C2)–7Ni coating has shown maximum and 75Cr3C2–25NiCr coating has shown minimum resistance to corrosion. Originality/value This paper is original research.

Evaluation of the corrosion behavior of AZ31 magnesium alloy with different protein concentrations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yucong Ma ◽  
Mohd Talha ◽  
Qi Wang ◽  
Zhonghui Li ◽  
Yuanhua Lin
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Energy Dispersive Spectrometer ◽  
Inhibitory Effect ◽  
Corrosion Process ◽  
High Concentration ◽  
Content Type ◽  
Atomic Force

Purpose The purpose of this paper is to study systematically the corrosion behavior of AZ31 magnesium (Mg) alloy with different concentrations of bovine serum albumin (BSA) (0, 0.5, 1.0, 1.5, 2.0 and 5.0 g/L). Design/methodology/approach Electrochemical impedance spectroscopy and potential dynamic polarization tests were performed to obtain corrosion parameters. Scanning electrochemical microscopy (SECM) was used to analyze the local electrochemical activity of the surface film. Atomic force microscope (AFM), Scanning electron microscope-Energy dispersive spectrometer and Fourier transform infrared spectroscopy were used to determine the surface morphology and chemical composition of the surface film. Findings Experimental results showed the presence of BSA in a certain concentration range (0 to 2.0 g/L) has a greater inhibitory effect on the corrosion of AZ31, however, the presence of high-concentration BSA (5.0 g/L) would sharply reduce the corrosion resistance. Originality/value When the concentration of BSA is less than 2.0 g/L, the corrosion resistance of AZ31 enhances with the concentration. The adsorption BSA layer will come into being a physical barrier to inhibit the corrosion process. However, high-concentration BSA (5.0 g/L) will chelate with dissolved metal ions (such as Mg and Ni) to form soluble complexes, which increases the roughness of the surface and accelerates the corrosion process.

Corrosion behavior of new type Co-based superalloys with different Ni contents

2017 ◽  
Vol 35 (6) ◽  
pp. 455-462 ◽  
Author(s):  
Bo Gao ◽  
Lei Wang ◽  
Yang Liu ◽  
Xiu Song ◽  
Shu-Yu Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Hot Corrosion ◽  
Corrosion Layer ◽  
Corrosion Process ◽  
Corrosion Properties ◽  
Oxidation Processes ◽  
Ni Content ◽  
Ni Addition ◽  
New Type

AbstractThe corrosion properties of γ′-strengthened Co-xNi-Al-W-Cr (where x=15, 20, 25, and 30 at.%) superalloys were investigated in the mixture of 75 wt.% Na2SO4+25 wt.% NaCl at 900°C. The results showed that the corrosion behavior is associated with both sulfuration and oxidation processes. It was demonstrated that increasing the addition of Ni effectively promoted the formation of continuous Al2O3 scales, so that the hot corrosion resistance could be improved. When Ni content is more than 20 at.%, a large amount of Ni3S2 precipitates during the corrosion process. Sulfuration can destroy the integrity of the corrosion layer and increase the activity of oxygen. In this way, the internal oxidation of the alloys becomes more serious. Therefore, it is recommended that the optimum Ni addition is about 20 at.% for new type Co-Ni-Al-W-Cr superalloys.

Investigation of mechanical and corrosion behavior of laser hybrid weld joint of 2205 duplex stainless steel

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Chuanbo Zheng ◽  
Cheng Zhang ◽  
Xiao Yong Wang ◽  
Jie Gu
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Duplex Stainless Steel ◽  
Base Metal ◽  
Corrosion Behavior ◽  
Welded Joints ◽  
Two Phase ◽  
Content Type ◽  
2205 Duplex Stainless Steel ◽  
Laser Hybrid

Purpose Duplex stainless steel is composed of equal amounts of austenite and ferrite, which has excellent corrosion resistance and strength. However, after the metal was welded, the ratio of austenite and ferrite in the joint is unbalanced, and secondary phase precipitates are produced, which is also an important cause of pitting corrosion in the joint. Design/methodology/approach This paper aims to study the mechanical and corrosion behavior of welded joints, by adjusting the welding parameters of laser hybrid welding, dual heat sources are used to weld 2205 duplex stainless steel. The two-phase content of different parts of the welded joint is measured to study the influence of the ratio of the two-phase on the mechanical and corrosion properties of the joint. Findings The ratio of austenite and ferrite in different welded joints has an obvious difference, and from top to bottom, the austenite content decreased gradually, and the ferrite content increased gradually. The harmful phases are precipitated in the middle and lower part of the joint. The strength of welded joints is slightly lower than that of base metal. At the same time, the fracture analysis shows that some ferrite phases are affected by the precipitate in the grain and produce quasi-cleavage fracture. The corrosion results show that the corrosion resistance of the welded joints is lower than that of the base metal, and the concentration of chloride ions affects the corrosion resistance. Originality/value In this paper, the authors use the influence of different welding processes on the two-phase ratio of the joint to further study the influence of the microstructure on the corrosion resistance and mechanical properties of the weld.

“Building as machine”: mental image of combined cycle power plants workers

Facilities ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohammad Rezaee ◽  
Seyed Rahman Eghbali
Keyword(s):  
Data Collection ◽  
Power Plants ◽  
Thermal Power ◽  
Mental Image ◽  
Careful Analysis ◽  
Combined Cycle ◽  
Collection Method ◽  
Content Type ◽  
Environmental Threats ◽  
Data Collection Method

Purpose This paper aims to interpret the workers’ perception of combined cycle power plants through visual qualities. Design/methodology/approach In this qualitative research landscape image, the sketching technique is applied as a data collection method to extract participants’ mental images by asking them to draw sketches. The resulted sketches besides obtained verbal and written data were analyzed and coded in three stages to explain the workers’ perception. Visual qualities were studied as a mean which made it possible to interpret the workers’ perception of their workplace. Findings Careful analysis of the gathered data and the emerged concepts via open coding identify four axial categories of the concepts forming the workers’ perception of the power plants: “inconsistency with nature,” “emphasis on function and product,” “health and environmental threats” and “interpretation of the built form as a mass instead of space.” These four categories support the core category of the proposed theory which is “perceiving building as the machine.” This phrase explains how workers perceive power plants as machines, not as supportive and lively environments. This is followed by consequences, “precedence of building over human” is prominent among them. Originality/value In the relevant body of literature, visual impact and visual perception of conventional thermal power plants are largely missed, as well as visual relation to environment focusing on a single building or groups of adjacent buildings. This paper covers both areas via asking for sketches as a data collection method, in addition, to interview the participants to clarify their mental image of the work environment.

Effects of potassium silicate on corrosion behavior of dacromet coating

2019 ◽  
Vol 66 (6) ◽  
pp. 819-826
Author(s):  
Khashayar Tabi ◽  
Mansour Farzam ◽  
Davood Zaarei
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Automobile Industry ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Corrosion Current ◽  
Potassium Silicate ◽  
Coated Steel ◽  
Content Type ◽  
New Information

Purpose Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. The purpose of this paper is to study the corrosion behavior of dacromet-coated steel. Design/methodology/approach Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and salt spray were carried out. SEM was used to study the morphological appearance of the surface. Findings The EIS behavior indicated that solvent-cleaned dacromet-coated steel sealed with potassium silicate showed that the corrosion current density was 2.664E − 5 A.cm2 which was reduced to 8.752E − 6 A.cm2 and the corrosion rate, which was 2.264E − 2 mm.year−1, was reduced to 7.438E − 3 mm.year−1 in NaCl 3.5 wt.per cent. EIS was used in NaCl 3.5 wt.%, and the Bode plot characteristics showed that the corrosion protection of solvent-cleaned, dacromet-coated steel was enhanced when sealed with potassium silicate. The EDS results of salt-sprayed, solvent-cleaned samples after 10 days indicated that the main corrosion products are composed of SiO2, ZnO and Al2O3. Research limitations/implications The detection of Li element in EDS was not possible because of the device limitation. Originality/value The current paper provides new information about the sealing properties of potassium silicate and its effects on the corrosion resistance of dacromet coating, which is widely used in many industries such as the automobile industry.

Measuring output-based technical efficiency of Indian coal-based thermal power plants

2019 ◽  
Vol 13 (1) ◽  
pp. 175-206 ◽  
Author(s):  
Sushama Murty ◽  
Resham Nagpal
Keyword(s):  
Technical Efficiency ◽  
Power Plants ◽  
Thermal Power ◽  
Efficiency Index ◽  
Productive Efficiency ◽  
Environmental Efficiency ◽  
Content Type ◽  
Indian Coal ◽  
First Time ◽  
Production Approach

Purpose The purpose of this paper is to measure technical efficiency of Indian thermal power sector employing the recent by-production approach. Design/methodology/approach The by-production approach is used in conjunction with data from the Central Electricity Authority (CEA) of India to compute the output-based Färe, Grosskopf, Lovell (FGL) efficiency index and its decomposition into productive and environmental efficiency indexes for the ITPPs Findings The authors show that given the aggregated nature of data on coal reported by CEA, CEA’s computation of CO2 emissions through a deterministic linear formula that does not distinguish between different coal types and the tiny share of oil in coal-based power plants, the computed output-based environmental efficiency indexes are no longer informative. Meaningful measurement of environmental efficiency using CEA data is possible only along the dimension of the coal input. Productive efficiency is positively associated with the engineering concept of thermodynamic/energy efficiency and is also high for power plants with high operating availabilities reflecting better management and O&M practices. Both these factors are high for private and centrally owned as opposed to state-owned power-generating companies. The example of Sipat demonstrates the importance of (ultra)supercritical technologies in increasing productive and thermodynamic efficiencies of the ITPPs, while also reducing CO2 emitted per unit of the net electricity generated. Originality/value This paper uses the by-production approach for the first time to measure technical efficiency of ITPPs and highlights how the nature of the Indian data impacts on efficiency measurement.

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