Electrochemical Studies of WC-Flyash HVOF Coating Interface on SA209-T1 Steel under 3.5 NaCl Solution

In this present research, the coatings of SA209-T1 using high velocity oxygen fuel were employed for the application of boiler tubes. Due to the adaptation of corrosion easy in boiler material, the research of those properties is significant because of its criticality and functionality during the service time. A right coating was found and applied on the SA209-T1 surface against corrosive environments. Good corrosion resistance is achieved by WC-flyash coatings applied on SA209-T1 substrate. The 90% WC-10% flyash coatings were found to be more protective followed by SA209-T1 steel. WC-flyash covering was tracked down so that the covering is compelling to secure the SA209-T1 steel substrate. It is reasoned that the arrangement of NiO, Cr2O3, CoO, and NiCr2O4 could add to the advancement of consumption opposition in coatings. The steel of uncoated endured erosion as extraordinary stripping and spalling of the scale, which could be because of the development of Fe2O3 oxide scale unprotectively. This paper reveals the performance, applications, and development of 90wt.% WC and 10wt.% fly ash through HVOF coating in SA209-T1 for electrochemical corrosion studies at room temperature.

Failure of Boilers and Related Equipment

Failures in boilers and other equipment taking place in power plants that use steam as the working fluid are discussed in this article. The discussion is mainly concerned with failures in Rankine cycle systems that use fossil fuels as the primary heat source. The general procedure and techniques followed in failure investigation of boilers and related equipment are discussed. The article is framed with an objective to provide systematic information on various damage mechanisms leading to the failure of boiler tubes, headers, and drums, supplemented by representative case studies for a greater understanding of the respective damage mechanism.

Role of Organic and Eco-Friendly Inhibitors on the Corrosion Mitigation of Steel in Acidic Environments—A State-of-Art Review

Steel has versatile application in chemical, structure and construction industries owing to its mechanical properties. However, it is susceptible to corrosion in acid environments. Thus, it requires to protect the steel from corrosion. Different types of corrosion resistance steel, coatings and inhibitors are developed to mitigate the corrosion, but, inhibitor is the best remedies to control the corrosion of steel in acid condition. Moreover, organic and green inhibitors used in acid condition for descaling, acid pickling, pipelines, boiler tubes and oil-wells. Organic inhibitors reduce the dissolution of steel in acid but, it is hazardous, expensive and needs expertise to synthesize the inhibitor. Therefore, there is utmost required to study and compile the latest research about the eco-friendly corrosion inhibitors, which showed more than 90% corrosion inhibition efficiency. In the present study, I have reviewed the state-of-arts, and compile the latest development in organic and eco-friendly corrosion inhibitor used in acid environment as well as suggested about the future scope and role of green inhibitor for sustainable society, which is economical, less hazardous and readily available from the natural sources.

Failure investigation into the boiler tubes of power plant

Failure of tubes is a very critical problem in boilers. The current study describes the detailed investigation for failure of boiler tubes in the power plants. Different characterization techniques like; metallography/microscopy, hardness, chemical analysis, SEM/EDS were utilized to find out the actual cause of failure. The tubes were failed within one year of its service. It was concluded that the brittle fracture (rupture) of tubes was occurred due to over-heating caused the formation of thermally insulating thick iron oxide scale on the inner surface of the boiler tube. Evidence of hydrogen embrittlement of the boiler tube in the rupture region was also found. Insights of this investigation might be helpful for the prevention of this type of failures in future.

Heat transfer to a moving wire immersed in a gas fluidized bed furnace

The gasified fluidized bed has been looked at as a safer replacement for heat treatment of carbon steel wire traditionally heat treated using molten lead baths. Most of the research has been conducted on heat transfer to larger diameter boiler tubes immersed in gas fluidized beds used by the power generation industry. However, there has been a lack of research on small diameter cylinders and longitudinally moving wire in heat treating systems. In 2015, Tannas developed a correlation that confirmed that the correlation previously developed for static wire under-predicts the heat transfer rate at higher wire speeds. In addition, this earlier correlation did not account for varying fluidization rates and only assumed that Nu was independent of fluidization rate for Ug/Umf > 2.5. So, the work reported here is intended to develop a new correlation that accounts for both wire motion and fluidizing rate in fluidized bed.

Heat transfer to a moving wire immersed in a gas fluidized bed furnace

The gasified fluidized bed has been looked at as a safer replacement for heat treatment of carbon steel wire traditionally heat treated using molten lead baths. Most of the research has been conducted on heat transfer to larger diameter boiler tubes immersed in gas fluidized beds used by the power generation industry. However, there has been a lack of research on small diameter cylinders and longitudinally moving wire in heat treating systems. In 2015, Tannas developed a correlation that confirmed that the correlation previously developed for static wire under-predicts the heat transfer rate at higher wire speeds. In addition, this earlier correlation did not account for varying fluidization rates and only assumed that Nu was independent of fluidization rate for Ug/Umf > 2.5. So, the work reported here is intended to develop a new correlation that accounts for both wire motion and fluidizing rate in fluidized bed.

Application of Thermal Spraying Techniques Used for the Surface Protection of Boiler Tubes in Power Plants

Distinct methods of depositing the coatings are available according to the intended area of application with a sole objective to protect the surface of structural component like boiler, boiler tubes, and heat exchangers from any mechanical or chemical damage. The main benefit is to minimize the manufacturing cost of a new component and also its fabrication. Thermal spraying is the commonly used technique to tailor the surface properties with a cost-effective approach. The different techniques of thermal spraying such as plasma, HVOF, cold spraying, etc. were investigated and introduced. Although each of these processes has advantages, there are also certain disadvantages associated with them, which limit their application. In the chapter, different methods of depositing coating by thermal spray are discussed and compared. By developing advanced techniques and new coating materials, the life and efficiency of power plants can be enhanced in the future.