gabriel aryvalo

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 Leadergabriel.arevalo@same.cl