Predicting metal temperature of Re-Heater tubes of a typical super 1 critical utility boiler using CFD technique 2 (original) (raw)
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Applied Thermal Engineering, 2019
Deployment of renewables introduces new regimes of large scale boiler operation. The units are required to operate at flexible rather than baseload mode. One of the requirements is to reduce the minimum load of the existing boilers which adds thermal stress to pressure parts. Significant operational issue is the local overheating of the heat exchangers material due to lower steam flow rates and poor heat dissipation conditions. The problem is particularly intensified in low-pressure reheaters. The current paper demonstrates a novel computational method of predicting tube metal temperature of specific reheater platens. The proposed numerical procedure incorporates coupling of CFD simulations of the boiler fire side with 1-D pipe flow model in the heat exchanger. Simulation results are compared to measurement data. The numerical method can be used to make decision on the modification strategy of the reheater design to achieve uniform temperatures of the tube metal in each platen by restriction orifices adjustment.
Thermal Analysis of Superheater Platen Tubesin Boilers
Superheaters are among the most important components of boilers and have major importance due to this operation in high temperatures and pressures. Turbines are sensitive to the fluctuation of superheaterstemperature;therefore even the slightest fluctuation in the outlet vapor temperature from the superheaters does damage the turbine axis and fins. Examining the potential damages of combustion in the boilers and components such as the superheaters can have a vital contribution to the progression of the productivity of boiler, turbine and the power plant altogether it solutions are to be fund to improve such systems. In this study, the focus is on the nearest tube set of superheaters to the combustion chamber.These types of tubes are exposed to a wide range ofcombustion flames such that the most heat transfer to them is radiation type.Here, the 320 MW boiler of Isfahan power plant (Iran), the combustion chamber, 16 burners and the platensuperheater tubes were remodeled by CFD technique. The fluid motion, the heat transfer and combustion processes are analyzed. The two-equation turbulence model of k-εis adopted to measure the eddy viscosity. The eddy dissipation model is used to calculate the combustion as well as the P-1 radiation model to quantify the radiation. The overheated zones of superheater tubes and the combustion chamber are identified in order toimprove this problem by applying the radiation thermal shields and knees with porous crust which are introduced as the new techniques.
Failure investigation of secondary super-heater tubes in a power boiler
Engineering Failure Analysis, 2009
The super heater is heart of any boiler system main duty of which is to supply desired amount of steam regularly at rated temperature and pressure. Frequent tube failure in super heaters is found to be crucial problem which is directly related with boiler operation, performance and design parameters. Aim of this paper is to predict possible causes of super heater tube failure. It deals with the failure investigation of secondary super heater tube panel of SA213-T11 grade steel. The primary observations made with visual inspection and then metallurgical investigation has been carried out by microstructure analysis. The temperature distribution on the tube walls of the super heater is analyzed using computer aided engineering tools. From CFD results and metallurgical examination, localized overheating was seen in failed region of super heater tubes. High erosion areas were also seen from computational fluid dynamics. The uneven temperature distribution over the super heater tubes leads to localized overheating, chilling and development of excessive thermal stresses. This analysis is carried out using multiphysics environment which is very useful tool for analysis of many industrial systems like heat exchangers, chillers, cyclones etc.
THE 4TH BIOMEDICAL ENGINEERING’S RECENT PROGRESS IN BIOMATERIALS, DRUGS DEVELOPMENT, HEALTH, AND MEDICAL DEVICES: Proceedings of the International Symposium of Biomedical Engineering (ISBE) 2019
Indonesian electricity demand increased an average 8.3 % every year, from 236 TWh in 2017 to 480 TWh in 2026, this causes the state-owned electricity generation company looking for efficient, reliable, economical and clean power plant. Hence various Steam Power Plants (PLTU), and other power plants are built with the latest technology as part of the national strategic program of 35,000 MW by the Indonesian government. The construction of a USC power plant in western Java can also overcome power unbalances that could potentially result in blackout electrical power in the electricity Java grid system. The state-owned electricity generation company is managing a project for the construction of the PLTU USC 2 x 1000 MW in Banten, so the authors need to observe the flue gas flow characteristics and heat transfer process of the boiler with the latest technology. Steam Generators with the latest technology of this kind will be increasingly developed in Indonesia and other countries in the future. The boiler data generally refers to the feasibility study, bidding document and documents related to the PLTU that is currently in a construction project, this thesis uses a numerical approach to Computational Fluid Dynamic (CFD) to obtain the characteristics of flue gas flow and heat transfer from flue gas to the boiler tube on the superheater and modeling the heat transfer process from the flue gas to the tube boiler and the distribution of the regulation in various conditions that will be used as a reference evaluating the boiler detail design Ultra Super Critical Coal-Fired Power Plant (USC CFPP) , This research results obtained the highest temperature in the superheater tube 1 is at 30 degree on tube 4 and the lowest on tube 5 at 120 degree. In superheater tube 2, the highest temperature on tube 5 at 30 degree and the lowest on tube 5 at 210 degree flue gas velocity at the inlet around the superheater 1 tube lower than at the outlet side Conversely in the area around the superheater 2 tube, the inlet side velocity is higher than the outlet side, due to the boiler nose.
Failure analysis and retrofitting of superheater tubes in utility boiler
The extreme spray water mass flow rate deviation was observed to occur in the middle temperature superheater of Sahand 2 Â 325 MW Power Plant utility boiler, which severely affected its economic performance and safe operation. Boilers operating in these conditions led to failure in superheater tubes at the same place for two consecutive times in a three year span. Thus, the failure analysis of superheater tubes by investigating the visual inspection, chemical, scale and creep analysis was carried out. The brittle failure occurred in the superheater tubes after the fuel was changed from natural gas to heavy oil. Failure analysis showed that tubes were suffering from long term overheating which was instigated by high spray water flow rate. In order to rectify the boiler operating conditions, some modifications were applied in the boiler unit 1 and operating parameters on this boiler were compared with boiler unit 2. The results showed that the 8.33% reduction in heating surface area corresponds to 52.84 and 17.80% reduction in spray water mass flow rate for capacities equal to 300 and 260 MW, respectively.
IJERT-Failure Investigation of Secondary Super Heater using CFD/CAE Technique
International Journal of Engineering Research and Technology (IJERT), 2013
https://www.ijert.org/failure-investigation-of-secondary-super-heater-using-cfdcae-technique https://www.ijert.org/research/failure-investigation-of-secondary-super-heater-using-cfdcae-technique-IJERTV2IS100188.pdf The super heater is heart of any boiler system main duty of which is to supply desired amount of steam regularly at rated temperature and pressure. Frequent tube failure in super heaters is found to be crucial problem which is directly related with boiler operation, performance and design parameters. Aim of this paper is to predict possible causes of super heater tube failure. It deals with the failure investigation of secondary super heater tube panel of SA213-T11 grade steel. The primary observations made with visual inspection and then metallurgical investigation has been carried out by microstructure analysis. The temperature distribution on the tube walls of the super heater is analyzed using computer aided engineering tools. From CFD results and metallurgical examination, localized overheating was seen in failed region of super heater tubes. High erosion areas were also seen from computational fluid dynamics. The uneven temperature distribution over the super heater tubes leads to localized overheating, chilling and development of excessive thermal stresses. This analysis is carried out using multiphysics environment which is very useful tool for analysis of many industrial systems like heat exchangers, chillers, cyclones etc.
Annals of Nuclear Energy, 2014
Trusted predictions of critical heat flux (CHF) value are essential for safe operation of boilers, steam generators and nuclear power reactors. Prediction techniques are numerous but they are mostly limited to uniformly heated tubes. There are separated effects on CHF, such as axial and radial heat flux distributions that have not been taken much attention. These effects are encountered during operation of boilers/steam generators and nuclear reactors. The present work is aimed at providing detailed analysis for experimental and numerical techniques used in CHF predictions focusing on non-uniform axial and circumferential heating profiles. For this purpose, heat transfer characteristics in case of CHF and heat transfer and wall boiling modeling are also clearly described. In addition, a detailed description of numerical models used in the predictions of the two phase flow characteristics is also presented followed by addressing most of the numerical work done for predictions of CHF in literature. Due to new challenges presented by the non-uniform heating in axial and circumferential directions, research work pertaining to analysis of CHF predictions in real systems for non-uniform heating profiles in both axial and circumferential directions is also presented.
Theoretical development of a thermal model for the reheater of a power plant boiler
Applied Thermal Engineering, 2007
A three-dimensional numerical model for simulating flow and heat transfer in the reheater of a boiler is presented. The aim is to describe, as well as possible, the geometry of the reheater and to be able to perform different mass flows of steam along each of the tube serpentines. The model thus makes it possible to calculate the temperature of the tube surfaces along the reheater. The porosity concept is employed, along with empirical correlations for the convective heat transfer coefficient and the radiation heat transfer coefficients. The radiation equations consider most of the radiative effects of the gas: ash content, triatomic gases, type of fuel and temperatures, tube layout and distances and temperatures of other radiative surfaces. The model is proposed with a view to using the measured values of velocities, temperatures and gas composition in the reheater as boundary conditions. The equations are solved using a general purpose computational fluid dynamics (CFD) code in conjunction with specific calculations for the source terms.