Installation of Auxilliary ventilation system and Duct leakage complete ppt

1. Installation of auxiliary ventilation system&DUCT LEAKAGE
SUBMITTED BY-
23152021-Nitesh Ku. Shah
SUBMITTED TO -
Dr. Tarun Verma
DEPARTMENT OF MINING ENGINEERING

2. CONTENTS
 Introduction
 Installation
 Equipment selection & Design procedures
 What is duct & its type
 Reason for leakage of duct
 Installation practices
 Design and operational considerations
 Consequences
 Preventive measures
 References

3. INTRODUCTION
 An auxiliary fan is used in the mines for the ventilation of
development headings, for narrow workings in coal and for
stone drifts which are carried in advance of the normal
ventilating current.
 Axial flow fans are better than centrifugal fans for auxiliary
ventilation.
 Install the fan to avoid air recirculation.
 Installation should be a sufficient distance outside the actual
heading it is intended to ventilate.

4. INSTALLATION
Here are some tips for installing auxiliary ventilation systems:
 The forcing fan should be placed on the intake side, while the
auxiliary exhausting fan should be on the return side of the drift.
 The minimum distance between the fan and the corner of the
drift road to be ventilated should be 5 meters.

5. Cont…
For 90-degree bends, a spiral duct must be used.
Use cables or wires to hang flexible ducting straight at
the back, using eyebolts, pins, or bolts.
Ensure maintenance of ducting condition.
Small auxiliary fans usually don't have volume control to
keep them light, but big ones might have inlet vanes or
dampers to adjust airflow.

6. Cont…
 Metal parts of an auxiliary fan setup must be grounded to
prevent sparks that could ignite methane.
 The air flow needed from an auxiliary fan depends on gas
emissions. Generally, it should be about 7m³ per minute per
square meter of the working face.
 Auxiliary ventilators are smaller than boosters and are used in
mines for shafts, tunnels, and narrow spaces where bratticing
isn't possible.

7. EQUIPMENT SELECTION
When selecting fans and ducts for an auxiliary ventilation system,
designers must consider key factors, like:
1. Compliance with Company and Government Regulations for Fan
Systems
• Ensure fan follows company and government rules.
• Consider noise levels and state/federal laws.
• Consider potential gas presence in the area.
• Noise from fans can affect work efficiency.
• Use equipment to reduce noise to meet rules or laws.

8. Cont…
2. Efficiency of the System: Auxiliary fans need power which raises
ventilation costs. So, continuous use needs efficient fans; pricier
but efficient ones are worth it. Duct type matters for energy
efficiency.
3. Standardization of Equipment: Mine wants consistent ducts and
fans for simpler inventory and designs.
It also helps to ensure that equipment and spare parts are
available when needed.

9. Cont…
4. Interface with Other Ventilation Circuits in the Mine: Designer
must consider how extra fans affect mine airflow. They might add
doors or other controls for proper ventilation, whether fans are
on or off.
5. Leakage, Return Air, and Compressibility Considerations: For
longer ventilation pipes, consider leaks, air loss, and tube
compression. Short pipes usually ignore these, but they matter
for longer ones.

10. DESIGN PROCEDURES
- Step 1 - Air leakage estimations: Leakage may be assumed to
range between 20% and 30%. Calculate the flow required at the
fan using: Qfan = Qface/(1 - leakage).
- Step 2 - Ventilation system selection: Selection based on heading
type, length, cross-sectional area, development method, re-entry
times, and cost.
- Step 3 - Airflow resistance calculations: The contribution of each
component of the column to the head loss must be determined.
Atkinson's equation can be used to estimate the friction head loss
in the duct.

11. Cont…
- Step 4 – Fan sizing: Fan curves analyzed to match head and
flow requirements. Selection based on total pressure,
determining blade pitch and motor size.

12. WHAT IS DUCT
 In underground mine ventilation, ducts are pathways for
airflow.
 They distribute fresh air and remove harmful gases and dust.
Ducts are made of durable materials and require regular
maintenance.
 They play a crucial role in keeping miners safe and
maintaining air quality underground.

13. TYPES OF DUCT
Two types of duct are commonly used, the flexible ducts and the
rigid ducts
 Flexible Ducts
 Flexible ducting is much easier to store, transport and install than
rigid ducting.
 They are cheaper in initial cost, but have shorter life.
 Earlier, flexible ducting was made from rubberized cotton fabric,
but this material was inflammable and was easily torn. Now,
flexible ducting may be made from terylene, rayon or nylon
coated with P.VC

14. Cont…
 They are conveniently used in shorter headings up to a distance
of 300m.
 Flexible ducts are very suitable in curved Headings.

15. Cont….
 Rigid Ducts
 Rigid ducts of round section are commonly used for all
permanent installations.
 They can be made of steel, aluminium, plywood, fibre-glass-
reinforced plastic or high- density polythene.
 Aluminum ducts are lightweight and smooth but costly, prone to
damage, and less suitable for mines due to their D-shape.
 Steel ducts are favored in mines and tunnels for their durability
and longevity, serving as a preferred permanent solution

16. Fig. Rigid Duct
Steel rigid duct

17. REASON FOR LEAKAGE OF DUCT
 Damage: Ducts can get holes or cracks from wear and tear,
corrosion, or impacts.
 Poor Installation: If ducts aren't installed well or sealed properly,
they're more likely to leak.
 High Pressure: Underground conditions, like high pressure from
ventilation systems, can stress ducts, causing leaks.
 Ground Movements: Shifting ground can put strain on ducts,
leading to damage and leaks.
 Lack of Maintenance: If ducts aren't regularly checked and fixed,
small issues can become big leaks over time.

18. FACTORS
Leakage of air from ducting is affected by the following factors:
 Ducting material characteristics
 Quality of installation
 Number of joints
 Total length of ducting
 Pressure differences between the inside and outside of the
ducting
 Diameter of the ducting

19. INSTALLATION PRACTICES
Tube Installation and Maintenance in Mines
 Importance of proper installation and maintenance for system
efficiency.
 Leakage should not exceed 10% of initial flow volume.
 Poor installation and maintenance practices can lead to leakage
above 50%.
 Installation procedures include hanging support cable and tubing
straight and tight.
 Use of fan adaptors to connect duct to fan to prevent leakage.

20. Cont…
 - Duct couplings, tight clamps and clips are used to assure good
duct connection and avoid leakage.
 - Flexible ducts hang from hooks on messenger cables, while
steel ducts use chains. Hooks can also attach directly to bolts,
straps, and screens for support.
 - To prevent damage from mobile equipment, suspend ducting as
high as possible against the back, especially at intersections and
low-laying areas.

21. DESIGN AND OPERATIONAL CONSIDERATIONS
Fan Installation and Operational Aspects
 Fan installation should ensure sufficient air supply to prevent
recirculation.
 Fan installation should prevent contamination of air with toxic
fumes and dust.
 Fan's capacity should not exceed half of the air passing in the
airway where it is installed.
 When installing fans in series, a gap of approximately 15 cm is
common to prevent column collapse.

22. Cont…
 Sizing the ventilation column should consider drift size and
equipment size.
 Fans should be turned off during blasting to prevent impeller
blade damage.

23. CONSEQUENCES
 Safety Hazard: Leakage can accumulate harmful gases like
methane, carbon monoxide, or dust particles, it is unsafe for
miners' health.
 Reduced Efficiency: Leakage can compromise ventilation system
effectiveness, affecting airflow distribution and removing
contaminants.
 Increased Energy Costs: Leaks in ducts increase energy
consumption and operational costs.
 Environmental Impact: Leaked substances may have
environmental consequences outside the mine, especially if
released into the atmosphere or nearby water sources.

24. PREVENTIVE MEASURE
 Regular Checks: Check ducts often for holes.
 Fix Leaks Promptly: Seal any holes found.
 Use Good Materials: Use strong materials for ducts.
 Monitor Systems: Keep an eye on ducts for leaks.
 Train Staff: Teach workers to spot and report leaks.
 Emergency Plans: Have plans ready for leaks or system failures.

25. Example
Problem:- In an underground mine, a ventilation duct with a diameter of
1 meter has developed a leak of 0.02 square meters in area. The
airflow velocity in the duct is 5 m/s. Calculate the volume of air lost per
second due to this leak, and also find actual quantity of duct deliver.
Solution:-

26. Cont….
let's find the volume of air lost per second due to the leak:
Volume of air lost per second through the leak (Vloss):
Given that the leak area is 0.02 square meters, and the airflow
velocity is 5 m/s, we can calculate the volume of air lost per
second through the leak using the formula:
So Actual quantity of duct deliverable is 3.927-0.1=3.827

27. REFERENCES
 Elements of mining and technology: by D.J.Deshmukh
 Mine ventilation and air conditioning: by Howard L. Hartman
 Mine Environment and ventilation: by G.B. mishra
 Auxiliary ventilation operation practices E. De Souza Department
of Mining Engineering, Queen’s University, Kingston, Canada.
 A Comparison of Air Leakage Prediction Techniques for Auxiliary
Ventilation Ducting Systems A.D.S. Gillies and H.W.Wu University
of Queensland, Brisbane ZLD 4072, Australia.

28. Thank You!