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Computational Analysis of Water Atomization in Spray Desuperheaters of Steam Boilers. A Thesis by Paul Bovat. Outline. Background Objectives Main Equations Model Main Results Conclusions Recommendations. Background. What is a desuperheater? What are the components?
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Computational Analysis of Water Atomization in Spray Desuperheaters of Steam Boilers A Thesis by Paul Bovat
Outline • Background • Objectives • Main Equations • Model • Main Results • Conclusions • Recommendations
Background • What is a desuperheater? • What are the components? • Common problem with desuperheaters • How is the problem corrected?
Objectives • Determine pressure drop across spray nozzles • Compare to industry standard • Determine final steam temperature • Determine droplet life • Determine full droplet evaporation location
Equations • Turbulent dissipation and kinetic energy equations • Energy equation • Equation for mass diffusion in turbulent flows
Particle inertia Equation (Lagrangianreference frame) • Spherical drag law coefficients • Equations for heat and mass exchange • Film Formation thickness equation
Atomizer spray half-angle • Secondary Break-up • Webber # • Droplet evaporation • Droplet lifetime
Model • ANSYS Fluent CFD • Realizable k-εturbulent model • Energy equation • Species model • Discrete Phase Model • Pressure Swirl Atomizer
Results • Pressure loss across then nozzle • 17% higher results between the empirical and computational results
Results • Desuperheater spray system • Inlet temp of desuperheater 650 deg F • Outlet temp of desuperheater 645.5 deg F • 4.5 deg F reduction in temperature • Total evaporation is ≈1.48ft
13.5 Results
Conclusion • Pressure drop across nozzle • Limitations of elements • Second Order Up-Wind • Desuperheater temperature • Temperature not regulated enough • Evaporated time is as designed
Recommendations • Re-run pressure drop analysis with more elements • Lower spray water temperature • Increase spray half angle