1. Computational Analysis of Water Atomization in Spray Desuperheaters of Steam Boilers
A Thesis by Paul Bovat

2. Outline Background Objectives Main Equations Model Main Results
Conclusions
Recommendations

3. Background What is a desuperheater? What are the components?
Common problem with desuperheaters
How is the problem corrected?

4. Objectives Determine pressure drop across spray nozzles
Compare to industry standard
Determine final steam temperature
Determine droplet life
Determine full droplet evaporation location

5. Equations Turbulent dissipation and kinetic energy equations
Equation for mass diffusion in turbulent flows

6. Particle inertia Equation (Lagrangian reference frame)
Spherical drag law coefficients
Equations for heat and mass exchange
Film Formation thickness equation

7. Atomizer spray half-angle
Secondary Break-up
Webber #
Droplet evaporation
Droplet lifetime

8. Model ANSYS Fluent CFD Realizable k-ε turbulent model Energy equation
Species model
Discrete Phase Model
Pressure Swirl Atomizer

9. Model

10. Results Pressure loss across then nozzle
17% higher results between the empirical and computational results

11. Results

12. Results Desuperheater spray system
Inlet temp of desuperheater 650 deg F
Outlet temp of desuperheater deg F
4.5 deg F reduction in temperature
Total evaporation is ≈1.48ft

13. Results
13.5

14. Results

15. Conclusion Pressure drop across nozzle Desuperheater temperature
Limitations of elements
Second Order Up-Wind
Desuperheater temperature
Temperature not regulated enough
Evaporated time is as designed

16. Recommendations Re-run pressure drop analysis with more elements
Lower spray water temperature
Increase spray half angle