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Improved Air Quality Alternativeswithin EW Tankhouse by ImprovingBackground VentilationJorge Mella, Cristian Martínez, Pablo Stuado, Gabriel ArévaloR&D Team, SAME Ltda.
1. SAME Holding2. Problem Description3. Objectives4. Methodology5. Results / Conclusions
SAME
• General Ventilation• Dust Control• Gas Control
• Acid Mist ControlSystems• Composite Materials
Acid Mist Extraction and Abatement System
Local exhausting system:• High Energy Hoods®• Ducting system• SAME wet scrubber
Hoods washing system. Background ventilation• Natural/assisted ventilation
Problem Description
Must exhaust fugitive emissions• Cathodes harvesting• Momentary loss of hoods efficiency.
Fugitive emissions
Harvesting
Problem Description
Problem Description
1. Is it possible to improve the number of air renewals perhour?
2. Is natural background ventilation dependant onenvironmental conditions?
If yes, how to make background ventilation moreenvironmentally independant?
Problem Description
1. Decrease head losses on gravitational fans
2. Ensure more homogeneous ventilation within EW tankhouse
3. Assisted natural ventilation to obtain more stable ventilation(less prone to environmental effects)
Air ejectors as an alternative for assisted naturalventilation
Objectives
• Boundary conditions measurement campaign
• CFD model based on actual conditions
• Suggest background ventilation improvements basedon results
• Quantify improvements (CFD model based on improvedscenario)
SAME
Results
Temperature measurements (IR camera) at tankhouse walls and hoods surface
Results
Louvers inlet air velocity measurement
Results
EW tankhouse simplified geometrical model (left) and geometry meshing (right)
Results
Streamlines within EW tankhouse volume
Results
Louvers Average speed (measurements)[m/s]
Average speed (CFD)[m/s]
West 1.65 1.52
North 1.31 1.59
East 1.42 1.43
Area Volume[m³]
ContinuousGrav. Fan flow
[m³/s]
SegmentedGrav. Fan flow
[m³/s]
Roof louvers flow[m³/s]
Renewals/h
CathodesHandlingArea
90000 68.94 0 97.3 6.6
Cells Area 105000 137.2 64.2 0 6.9
Whole EWTankhouse 195000 206.1 64.2 97.3 6.8
Results
• Background ventilation day/night dependancy• Gravitational fans head loss• Misuse of fresh air due to air flow
inhomogeneity
Results
• CFD model for day time conditions agrees with measured temperature/air velocitymeasurements.
• During daytime, in the order of 6.8 renewals per hour are generated within EWtankhouse. However, renewals per hour are not homogenoeus, mainly because ofnatural convection.
• During nighttime, measured air velocities at louvers show that renewals per hourdrop to ~50% compared to daytime.
• It is recommended using assisted natural ventilation in order to guarantee samerenewals per hour between daytime/nighttime.
• It is proposed to improve air flow homogeneity within EW tankhouse, avoidingfresh air misuse (short circuits).
Conclusions
Aerodynamic shape leads to ~50%improvement in exhaust air flow capability.
Improvements Results
Case Average temperatureat 1.5 [m] from cells level
[°C] (°K)
Standard deviation(spatial fluctuations)
[°C]
Base 28.59 (301.59) 0.57
1 28.86 (301.86) 0.83
2 28.09 (301.09) 0.27
More homogeneous air flowwithin EW tankhouse
Improvements Results
Floor blockageas simple as usingrubber sheets (old belts)
Air ejectors working principle
Improvements Results
Air ejectors applied to gravitational fans (5:1 air flow ratio)
Improvements Results
Air ejectors applied to improved gravitational fans (8:1 air flow ratio)
Improvements Results
2
21
e
mm
V
PK
Preliminary manifold design (singular head losses coeff. K=1.8)
Improvements Results
Optimized ejectors manifold (K=1.04)
Improvements Results
Air ejectors induced air flow ratio v/sexhaust-to-ejectors area ratio.
21 / CAACQQ
psp
s
Improvements Results
Centrifugal fan P-Q curve (left). Optimized air ejectors flow ratio, based oncentrifugal fan performance (right)
Improvements Results
~15%
Renewals per hour gain v/s natural renewals per hour
Improvements Results
I. Summary of different improvements tested in this study:
• Gravitational fans with aerodynamic deflectors.• More homogeneous air flow by imposing local floor blocked-off regions.• Air ejectors for driving assisted natural ventilation.
II. Gravitational fans exhaust air flow enhanced ~50% by using aerodynamic deflectors.
III. Notoriously more homogenoeus air flow by using partial floor blockage atwalkways.
IV. It has been probed that air ejectors can be successfully used for driving assistednatural ventilation within EW tankhouses.
• Less dependancy between daytime/nighttime.• More homogeneous exhaust air flow (compared to stacks/axial fans).• ~25% less energy consumption compared to using axial fans.• Easy setup and maintenance (all mechanical equipment at floor level).• Can be started only at hours with poor natural ventilation.
SAME
Thank YouQuestions?
(For further information, visit us during postersession at the end of this presentation)
Ph.D. Gabriel Arévalo – R&D Team [email protected]