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Modeling of Water Injection into the Desuperheater of Steam Generator

Setareh, Milad | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44868 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saidi, Mohammad Hasan
  7. Abstract:
  8. One of the most important equipment in a power station is desuperheater which its operation has effect on power station performance and efficiency.It is necessary to identify and evaluate the most important factors that have effect on its performance. Using desuperheater cause that the temperature of exhausting superheat steam of boiler decreases to the desired quantity. If the temperature of superheat steam is very high, it will cause burning of superheater pipes that is very dangerous.Steam is used for two purpose of power generating and operational process. Unfortunately these applications have different requirement. In power generating for maximizing efficiency, turbine needs high temperature and superheat steam, while process usage needs lower temperature near saturation point. So if the superheat steam is used for process usage, it's tempreture should be decreased so the necessity for using desuperheater is determined.When Steam is in contact with water it will be converted in to desuperheat and cause that the injected water evaporate. Desuperheater injects cool water in the form of pony spray for optimal evaporation. These little droplets accelerate transformation of heat between water and steam. The objective of this thesis is modeling of venturi desuperheater, evaluating the impact of size of drops diameter and desuperheater pipe diameter on the temperature of desuperheat steam. At first a review on the different type of desuperheater and their functionalities is done . Then the equations of continuous phase (superheat steam) and discrete phase (water drops) is stated and then boundary conditions, coupling of equations to each other is explained. The equations are written in Eulerian-Lagrangian approach and then a method for solving discrete phase equations is stated. Modeling is done using Fluent software and meshing of model is done in ICEM software environment. The results of this project show that increasing input pipe diameter, venturi nozzle diameter and venturi terminal diameter cause that the maximum length of droplets evaporation decrease. Also increasing the temperature of droplets, increase the velocity of drops’s injection and droplets amount of maximum length of drops evaporation
  9. Keywords:
  10. Pipe Diameter ; Eulerian-Lagrangian Approach ; Continuous Phase ; Dispersed Phase ; Desuperheater ; Venturi Tubes

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