Thermal and stress analyses of a novel coated steam dual pipe system for use in advanced ultra-supercritical power plant (original) (raw)
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International Journal of Pressure Vessels and Piping, 2020
Improving the energy efficiency of power plants by increasing steam operating temperature up to 700 � C can be achieved using novel engineering design concepts such as coated steam pipe systems. This paper presents an optimised design for a novel coated dual pipe system to be used in advanced ultra-supercritical power plant. The approach developed in this study uses a combination of an optimisation algorithm and FE simulation, based on the reduction of the hoop stress at top coat/bond coat interface generated by the thermal and mechanical stresses. This allows determination of the optimum dimensions and material properties of the system. A unified viscoplastic model which combines a power flow rule with non-linear anisothermal evolution of isotropic and kinematic hardening has been used for the thermo-mechanical analysis of the coated dual pipe system under the cyclic loading. The results of the optimisation show that the value of the hoop stress at the top coat/bond coat interface is reduced significantly, compared with that in the baseline model. Finally, the potential technical challenges and future works for the proposed steam dual pipe system are discussed.
Reducing steam transport pipe temperatures in power plants
Energy, 2019
A cycle analysis has been applied to a model of a advanced ultra-supercritical steam plant with novel steam pipes. The transfer pipes proposed incorporate internal thermal coatings and are externally jacketed to enable cooling. This enables higher temperature working steam, while keeping the pipe wall temperature below the acceptable limit for more conventional steel alloys and avoiding the need to use higher cost austenitic stainless steels and nickel base alloys. The baseline design had a superheat temperature of 700 • C and a reheat temperature of 720 • C. A thermal coating thickness of 2.8 mm is sufficient to keep the wall temperatures of the steam transfer pipe after the supercritical boiler below 600 • C. For the transfer pipe located after the reheater a thicker coating or less ambitious reheat temperature is required to achieve acceptable pipe wall temperatures. Whereas subcritical plant has a calculated cycle efficiency of 42.1%, the elevated temperature and pressure in a customary ultra-supercritical steam boost cycle efficiency to 52.2%. Modifying this design with a thermal barrier lowers the cycle efficiency to 51.4%, still appreciably better than for subcritical plant. Alternative plant cooling arrangements might improve pipe temperatures but have minimal impact on overall cycle efficiency.
High Temperature Materials and Processes, 2008
The elastic, inelastic deformation and stress distribution pattern of a seventeen years service exposed primary superheater tube in a 120 MW boiler of a thermal power plant have been evaluated by using both analytical and numerical techniques. The commercial finite element computer code ANSYS was used for stress analysis. The methodology is a valuable design tool for development of new boiler tubes as well as for considering the effects of numerous operating variables on creep life. The health of the tube was also assessed based on microstructure, hardness and a few conventional creep tests carried out at 500°C at various stress levels (40-177 MPa). Results revealed that there was not much variation in the microstructure and hardness of the service exposed tubes compared to the virgin material. Creep deformation behavior of the service exposed and virgin tubes of the same material at 40 MPa reveal that deterioration of the creep properties fall within the 20% scatter band, which is well within the specified limits of ASTM standard. The service exposed primary superheater tube is thus in a good state of health.
Stress Analysis Evaluation and Pipe Support Type on High-Pressure and Temperature Steam Pipe
International Journal of Mechanical Engineering Technologies and Applications
The design and analysis of piping systems are critical in the power and process industries. The steam pipe is one of the main requirements for the plant to be installed. High-pressure and high-temperature steam pipes in the piping system are critical lines that need to be subjected to stress analysis. This study aims to evaluate the stress and the effect of using pipe supports on the stress in the piping system. Stress analysis is needed to ensure that the piping system that is designed is safe and does not exceed the allowable stress under operating conditions. Data analysis used ASTM A335-P11 as a pipe material with a design pressure of 65 bars and a design temperature of 480 °C. Stress analysis was carried out using CAESAR II software, which refers to ASME B31.3 process piping standards and codes. The findings revealed that the type of support chosen, such as the gap and distance of pipe support, has a significant impact on the stress value in the piping system. The results of th...
Thermal History and Stress State of a Fresh Steam-Pipeline Influencing its Remaining Service Life
2011
The service lift of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh- and reheated steam, depend on the exhaustion rate of the material Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a phi 324 x 36 pipe bend element of afresh steam-pipeline, made of steel class ICr0.3Mo0.25V, after 160.000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.
Thermal Science, 2011
The service life of thick-walled power plant components exposed to creep, as is the case with pipelines of fresh-and reheated steam, depend on the exhaustion rate of the material. Plant operation at elevated temperatures and at temperatures below designed temperatures all relates to the material exhaustion rate, thus complicating remaining life assessment, whereas the operating temperature variation is a most common cause in the mismatching of real service and design life. Apart from temperature, the tube wall stress is a significant variable for remaining life assessment, whose calculation depends on the selected procedure, due to the complex pipeline configuration. In this paper, a remaining life assessment is performed according to the Larson-Miller parametric relation for a 324×36 pipe bend element of a fresh steam-pipeline, made of steel class 1Cr0.3Mo0.25V, after 160.000 hours of operation. The temperature history of the pipeline, altogether with the pipe bend, is determined based on continuous temperature monitoring records. Compared results of remaining life assessment are displayed for monitored temperature records and for designed operating temperature in the same time period. The stress calculation in the pipe bend wall is performed by three methods that are usually applied so to emphasize the differences in the obtained results of remaining life assessment.
AN OVERVIEW OF STRESS ANALYSIS OF HIGH-ENERGY PIPELINE SYSTEMS USED IN THERMAL POWER PLANTS
A typical high-energy piping systems consists of the main steam, reheat (hot and cold) and boiler feed pump (BFP). The initial design of the system is based on elastic analysis to ensure that the stresses and deflections fall within established code limits. The important reason for analyzing the piping is that many power plants were built before (40 to 50 years) computer analysis techniques were available. The main aim of piping stress analysis is to check the design, which will allow simple and economical piping supports and provide flexibility to the piping system for thermal expansion. The piping stress analysis is carried out using CAEPIPE software. By using this software we can evaluate stresses, stress ratios, flange condition, support loads, element forces and displacements at each node. In this paper, only the maximum and minimum displacement results are tabulated.
Materials for ultra-supercritical coal-fired power plant boilers
2006
The efficiency of conventional fossil power plants is a strong function of the steam temperature and pressure. Research to increase both has been pursued worldwide, since the energy crisis in the 1970s. The need to reduce CO 2 emission has recently provided an additional incentive to increase efficiency. The main enabling technology in achieving the above goals has been the development of stronger hightemperature materials. Extensive R&D programs have resulted in numerous high strength alloys for heavy section piping, and tubing needed to build boilers. The study reported here is aimed at identifying, evaluating and qualifying the materials needed for the construction of the critical components of coal-fired boilers capable of operating with 760 1C (1400 1F)/35 MPa (5000 psi) steam. The economic viability of such a plant has been explored. Candidate alloys applicable to various ranges of temperature have been identified. Stress rupture tests have been completed on the base metal and on welds to a number of alloys. Steamside oxidation tests in an autoclave at 650 (1200 1F) and 800 1C (1475 1F) have been completed. Fireside corrosion tests have been conducted under conditions simulating those of waterwalls and superheater/reheater tubes. Weldability and fabricability of the alloys have been investigated. The capability of various overlay coatings and diffusion coatings have been examined. This paper provides a status report on the progress achieved to date on this project.
International Journal of Engineering Research & Technology (IJERT), 2018
The aim of this study was to analyze the transfer of steam in an insulated piping through different types of dielectric layers as an insulating materials covered for a Mild steel tube by the method of theoretical and finite element analysis The results shows that in general impermeable materials offer better protection against hot steam, the conduction of heat from the steam to the insulating material is depends on the thermal conductivity and the insulation thickness. The mild steel piping and thermal insulation are designed to with stand thermal stress.