Advancements in supercritical (SC), ultrasupercritical (USC), and advanced USC coal-fired power plants have been achieved through the development of enhanced materials utilized in advanced steam ...cycles and through the deployment of advanced emission control systems. These are referred to as high-efficiency low-emission (HELE) technologies, which may solve numerous issues associated with coal-based power generation. There is a clear global transition from subcritical to advanced power plant types and significant R&D work on HELE technologies. Therefore, this comprehensive review covers the latest HELE technology deployment in major coal-consuming countries and their R&D roadmaps to advance HELE technologies. In spite of the various advantages of HELE technologies, there have been numerous technical challenges relevant to achieving the HELE steam conditions and deploying low emission control technologies in the HELE systems. Hence, this review covers the technical challenges and the relevant recent research by using various coal combustion test facilities. The current focus for the progression from USC boilers to advanced USC boilers is a successful demonstration of the developed high-performance alloys under the advanced steam conditions. This review covers the current status of research and development of advanced USC (A-USC) materials and challenges based on the major material research programs.
The main objective of this work is to evaluate the oxidation behavior of super heater material which is used in the High temperature application such as super critical boiler. High temperature ...application operates at elevated temperature range above 700 °C and 750 °C. At elevated temperature, oxidation occurs surface of metal which leads to failure of material. This turns the metal to corrode which interrupts and decrease its functionality of plant. Hence, the selective super heater material (SS316) is selected for this work. High temperature oxidation behavior is analysed by testing the material in tubular furnace in air environment at 700 °C and 750 °C. The material is tested in the tubular furnace by arranging the specimen in an order like without coating of metal surface, second one is with Aluminium oxide coating of metal surface and third one is Chromium oxide coating of metal surface. After that the tested specimens are characterized by SEM, EDAX. From that results suitability of the metal for high temperature application in power plant is recommended.
This paper overviews the effects of some precipitates in Fe-Ni base boilers materials. The volume fraction of these precipitates is usually below 10% for maintaining the microstructure stability and ...manufacture ability. They appear in a number of morphologies, but all of them improve the creep strength when they exist in small size. For the alloys serviced below 650°C, the strengthening precipitates disperse within the matrix and maintain their diameter below 100 nm during long time exposure. For the alloys serviced above 650°C, the strengthening precipitates are normally larger than 100 nm in equivalent diameter. They may experience long growth duration and thus keep their size below 500 nm. Meanwhile, the precipitates may improve creep strength when they are dispersed over the grain boundaries.
Erosive high-temperature wear in boilers is one of the main causes of downtime and one of the principal engineering problems in these installations. This article discusses the use of FeBSiNb ...amorphous coatings synthesized by arc spraying to improve elevated-temperature erosion resistance for boiler applications. The influence of test temperature, velocity, and impact angle on material wastage was revealed using air solid particle erosion rig. The experimental results showed that moderate degradation of the coating was predominant at lower impact velocity and impact angles, while severe damage arose for higher velocities and impact angles. The erosion behavior of the coating was sensitive to test temperature. The erosion rates of the coating decreased as a function of environment temperature. The relationship between microstructure and erosion resistance of the coating was also analyzed in details. The FeBSiNb coating had excellent elevated-temperature erosion resistance at temperatures at least up to 600 °C during service.
There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to ...detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.
Wire arc spraying is an economically attractive thermal spray process that is especially interesting for the protection of large-scale parts or constructions. This study presents the results of the ...development and investigation of a number of cored wires based on the Fe-Cr-Al system with minor addition of alloying elements (B, Mn, Ni, Si, Ti, Mg, etc.). The microstructure of the coatings, their electrochemical behavior, and isothermal oxidation performance over a temperature range of 20-700 °C were investigated. Erosion resistance at elevated temperatures was determined with a laboratory test unit under test conditions that have simulated the work conditions in fossil-fuel-fired boilers. It was established that the oxidation resistance and the gas-abrasive wear resistance of arc-sprayed coatings depend mostly on the coating microstructure and homogeneity of element distribution rather than on the general alloying level and microhardness of the coating. A new parameter for coating characterization, namely, the coefficient of chemical microheterogeneity,
K
CMH
, is introduced to quantify this influence. Formation of the coating microstructure at elevated temperatures and its influence on the protection ability of the coating are discussed.
A great contribution to CO
2
emissions comes from coal fired power generation. Combination of carbon capture sequestering technologies with sustainable biomass conversion constitutes a decisive boost ...in limiting rise in global temperature. Co-firing alternative materials with pulverized coal and using oxy-fuel combustion conditions (oxy-fuel co-combustion) is a very attractive process for power industry. Materials with both high mechanical properties and high environmental resistance are required by such advanced combustion systems. One approach to improve high-temperature oxidation/corrosion resistance is to apply protective coatings. In the present work, low and high Cr content Fe-based alloys have been deposited in order to investigate the influence of Cr content on coating protective performance in oxy-fuel co-combustion conditions. Grade 91 steel has been assumed as reference substrate. Effect of Al enrichment on coating environmental resistance has also been analyzed. Activities have been performed within the framework of Macplus Project (Integrated Project co-founded by the European Commission under the 7th Framework Program in the Energy area).
The accelerating effect of heavy metal compounds on the corrosive attack of boiler components like superheaters poses a severe problem in modern waste-to-energy plants (WTPs). Coatings are a possible ...solution to protect cheap, low alloyed steel substrates from heavy metal chloride and sulfate salts, which have a relatively low melting point. These salts dissolve many alloys, and therefore often are the limiting factor as far as the lifetime of superheater tubes is concerned. In this work the corrosion performance under artificial salt deposits of different coatings, manufactured by overlay welding, thermal spraying of self-fluxing as well as conventional systems was investigated. The results of our studies clearly demonstrate the importance of alloying elements such as molybdenum or silicon. Additionally, the coatings have to be dense and of a certain thickness in order to resist the corrosive attack under these severe conditions.
A shear punch test is a very useful small specimen test method for evaluating the mechanical properties of in-service components, in view of the requirements of small size sample material. This paper ...presents the results of shear punch tests on five grades of steels used in boiler construction, along with the correlation with yield stress and ultimate tensile stress obtained ASTM standard specimens. The design of the shear punch fixture and procedure to carry out the shear punch test is also highlighted.
In energy conversion facilities such as boilers and pyrolysis reactors that burn waste, fossil fuel, biomass and other materials, many corrosion factors, such as gas temperature and fluctuations in ...gas temperature, the condition of deposits, and gas composition, influence the high‐temperature corrosion rate of materials in a complex manner. In order to evaluate the corrosion behavior and corrosion life time of materials rapidly and accurately, a temperature gradient corrosion test (TGT) was developed and applied to waste incineration environments.
The TGT with thermal cycle was carried out without corrosive deposits in order to investigate the basic effect of gas temperature and fluctuation on corrosion behavior, especially in terms of the stability of protective oxide layers. As a result, it was clarified that gas temperature enhances the environmental factors such as the deposition rate of ash and penetration of corrosive species, while thermal cycle mainly enhances material factors such as the breakdown of protective scales.
Furthermore, three application case studies of TGTs for corrosion life estimation were carried out with a comparison between TGT and field corrosion data. From these studies, a good correspondence of corrosion rates between TGTs and field tests was obtained. This correspondence of corrosion rate was explained by the breakdown of the protective oxide layer and the penetration of corrosive species in a corrosion front.
The reproducibility and applicability of TGTs in the evaluation of the corrosion life time of materials were clarified based on the consideration of various corrosion mechanisms.
