Main Shaft Incline Shaft Vent Shaft 116’ Adit 228’ Level 140’ Level Sensor # 1 Sensor # 2 94’ Adit Regulator 154’ Winze North American / Ninth U.S. Mine

North American / Ninth U.S. Mine North American / Ninth U.S. Mine Ventilation Ventilation

Symposium, June 2002, Kingston Symposium, June 2002, Kingston CanadaCanada

Main Shaft

Incline Shaft

Vent Shaft

116’ Adit 228’ Level

140’ Level

Sensor # 1

Sensor # 2

94’ AditRegulator

154’ Winze

MEASUREMENT OF AIRFLOW THROUGH MEASUREMENT OF AIRFLOW THROUGH

REGULATORS AND REAL TIME REGULATORS AND REAL TIME

INTEGRATED MONITORINGINTEGRATED MONITORING

MEASUREMENT OF AIRFLOW THROUGH MEASUREMENT OF AIRFLOW THROUGH

REGULATORS AND REAL TIME REGULATORS AND REAL TIME

INTEGRATED MONITORINGINTEGRATED MONITORING

Stewart GilliesStewart Gillies

The University of QueenslandThe University of Queensland

North American / Ninth US Mine Ventilation SymposiumNorth American / Ninth US Mine Ventilation SymposiumJune 2002, Kingston CanadaJune 2002, Kingston Canada 22

Outline of PresentationOutline of PresentationOutline of PresentationOutline of Presentation

IntroductionIntroduction Theory of RegulatorsTheory of Regulators Field Tests of RegulatorsField Tests of Regulators UQEM Real Time Mine Ventilation SystemUQEM Real Time Mine Ventilation System Trials of the UQEM SystemTrials of the UQEM System ConclusionsConclusions


THEORY OF MINE REGULATORS THEORY OF MINE REGULATORS

An artificial resistance (in the form of shock An artificial resistance (in the form of shock loss) or loss) or a large thin plate installed in a fluid a large thin plate installed in a fluid conduit with an orifice. conduit with an orifice.

When a difference in pressure exists between When a difference in pressure exists between the two sides fluid flows as shown.the two sides fluid flows as shown.

A

V1

P1

Ar V2

P2 Ac


Mathematical Modelling of Regulators Mathematical Modelling of Regulators

Irregularity in shape and symmetry and their Irregularity in shape and symmetry and their positioning in roughly square or rectangular positioning in roughly square or rectangular airways,airways,

Construction of the opening - louvres, sliding Construction of the opening - louvres, sliding door, window or curtain or placement of drop door, window or curtain or placement of drop boards, andboards, and

Uncontrolled air leakage.Uncontrolled air leakage.


C-Section (Drop Board Type) Regulator C-Section (Drop Board Type) Regulator


An Example of Louvre Regulator An Example of Louvre Regulator


Derivation of Regulator EquationDerivation of Regulator Equation

Bernoulli’s equation can be applied to both sides Bernoulli’s equation can be applied to both sides of the orifice to calculate the velocity and hence of the orifice to calculate the velocity and hence the airflow quantity.the airflow quantity.

A correction must be made for the contraction of A correction must be made for the contraction of the jet at the vena contracta. the jet at the vena contracta.

Velocity at the orifice is obtained with the Velocity at the orifice is obtained with the following equation:following equation:

221

12

N

PCV sc


Derivation of Regulator Equation (cont.)Derivation of Regulator Equation (cont.)

Airflow quantity through regulator is as follows.Airflow quantity through regulator is as follows.

where where CCcc is the coefficient of contraction is the coefficient of contraction (A(Acc/A/Arr))

AArr is orifice opening areais orifice opening area NN is is the ratio of the orifice and airway crossthe ratio of the orifice and airway cross

sectional area, (Asectional area, (Arr/A)/A) PsPs is the differential pressure across regulatoris the differential pressure across regulator is air densityis air density

rs

c AN

PCQ

21

12


FIELD TESTS OF REGULATORSFIELD TESTS OF REGULATORS

To verify airflow behaviour through a drop board To verify airflow behaviour through a drop board regulator. regulator.

Airflow quantity and pressure drop across the regulator Airflow quantity and pressure drop across the regulator were measured.were measured.

Airflow quantity through the regulators can also be Airflow quantity through the regulators can also be calculated in theory from pressure measurements.calculated in theory from pressure measurements.

Results compared with measured values and the Results compared with measured values and the reasons for significant differences investigated. reasons for significant differences investigated.


Comparison of measured and predicted Q Comparison of measured and predicted Q

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

0 5 10 15

Number of boar ds removed

Air

flo

w q

ua

nti

ty (

m3/s

)

Measured quantity

Predicted quantity


Reasons for the differences in QuantitiesReasons for the differences in Quantities

Error during measurement:Error during measurement: Small cross-sectional areaSmall cross-sectional area No-symmetrical condition and shapeNo-symmetrical condition and shape Leakage occurs due to gaps or holes between boards, Leakage occurs due to gaps or holes between boards,

regulator frame and the airway walls.regulator frame and the airway walls. Airflow quantity can be expressed as follows to Airflow quantity can be expressed as follows to

account for leakage.account for leakage.

where Qwhere Qll is the leakage quantityis the leakage quantity

lrs

c QAN

PCQ

21

12


Airflow Paths in RegulatorAirflow Paths in Regulator

Regulators can be treated as a set of two parallel Regulators can be treated as a set of two parallel airways namely:airways namely:

Regulator opening andRegulator opening and Leakage paths Leakage paths

Regulator opening Leakage path


Resistance of RegulatorResistance of Regulator

The total resistance of regulator (RThe total resistance of regulator (Rtt) can be modelled ) can be modelled to consist of the regulator opening resistance (Rto consist of the regulator opening resistance (Roo) and ) and the leakage path resistance (Rthe leakage path resistance (Rll).).

The regulator opening resistance (RThe regulator opening resistance (Roo) can be ) can be calculated from the derived formulacalculated from the derived formula

Where A is the airway cross sectional area.Where A is the airway cross sectional area.

)11

(2 222 AAC

Rrc

o


Resistance of RegulatorResistance of Regulator

When the regulator is in a fully closed condition, the air When the regulator is in a fully closed condition, the air flows through the leakage path only with resistance Rflows through the leakage path only with resistance Rl l

which can be empirically derived.which can be empirically derived.

Rl = 32.734e1.1631Ar

R2 = 0.3993

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

450.00

0 0.5 1 1.5

Regulator opening area (m 2)


Measured and Predicted Airflow QuantityMeasured and Predicted Airflow Quantity

0.00

2.00

4.00

0 5 10 15

No. of board rem oved

Air

flo

w q

uan

tity

(m

3/s

)

Measured quantity

Predicted quantity


Regulator Resistance vs Opening AreaRegulator Resistance vs Opening Area

Rt = 0.9998A r-1.3746

R2 = 0.9567

0.00

5.00

10.00

15.00

20.00

25.00

30.00

0.00 0.50 1.00 1.50

Regulator opening ar ea (m 2)

To

tal

res

ista

nc

e (

Ns

2/m

8 )


UQEM Regulator Characteristic CurvesUQEM Regulator Characteristic Curves

P = -5.4536Q2 - 48.117Q + 284.74

P = 17.490Q2

P = 7.27Q2

P = 3.84Q2

0

20

40

60

80

100

120

140

160

0.00 1.00 2.00 3.00 4.00 5.00

Air flow quant ity (m 3/s )

Pre

ss

ure

dr

op

ac

ros

s r

eg

ula

tor

(P

a)


Plan of UQ Experimental MineShowing locations of doors and sensors

Plan of UQ Experimental MineShowing locations of doors and sensors

Regulator

Doors

BA5 sensors

FloSonic sensor


VENTSIM – Real Time SimulationsVENTSIM – Real Time Simulations


VENTSIM - Remote Station Database InterfaceVENTSIM - Remote Station Database Interface


VENTSIM - Airway Edit InterfaceVENTSIM - Airway Edit Interface

Input of Remote Station Number


TRIALS OF THE UQEM SYSTEMTRIALS OF THE UQEM SYSTEM

Trial Scenarios:Trial Scenarios:

I.I. The inclined shaft door was open, and the The inclined shaft door was open, and the regulator in 116’ level set on fully open.regulator in 116’ level set on fully open.

II.II. The inclined shaft door was open, and the The inclined shaft door was open, and the regulator was set 1/5 open with 12 boards regulator was set 1/5 open with 12 boards

III.III. The inclined shaft door was open, and the The inclined shaft door was open, and the regulator set on fully closed.regulator set on fully closed.


Schematic of UQEM Ventilation SystemSchematic of UQEM Ventilation System

116’ Adit

Main Shaft

Inclined Shaft

Vent Shaft

154’ Winze

228’ Level

Dead Man’s Pass

D

DD

Reg 94’ Adit

BA5 Sensor

Flo sonic

BA5 Sensor

D Vent doors X Measuring Stations


Accuracy of Trial ResultsAccuracy of Trial Results

Ventsim monitoring system predicts changes with Ventsim monitoring system predicts changes with reasonable accuracy although some differences in reasonable accuracy although some differences in quantities were larger than 10%.quantities were larger than 10%.


Constraints of the System – Transition TimeConstraints of the System – Transition Time

Changes Time

Regulator fully open to 12 boards Regulator 12 boards to fully closed Regulator fully closed to fully open Inclined shaft door open to closed Inclined shaft door closed to open

70 seconds 36 seconds 84 seconds 72 seconds 75 seconds

The transient period in UQEM is short and therefore is The transient period in UQEM is short and therefore is not of great significance in interpreting the network not of great significance in interpreting the network system. However, in large-scale mines, the period can be system. However, in large-scale mines, the period can be up to 10 minutes or more.up to 10 minutes or more.


Updating of Ventilation Simulation ModelsUpdating of Ventilation Simulation Models

The trial demonstrated the importance and necessity The trial demonstrated the importance and necessity of updating simulation models after changes. of updating simulation models after changes.

The three scenarios were examined for how the The three scenarios were examined for how the network reacted to the input of a real time fixed network reacted to the input of a real time fixed quantity in terms of maintenance of model accuracy quantity in terms of maintenance of model accuracy without a change to the regulator/door R valuewithout a change to the regulator/door R value

Based on air quantity observations it is not necessary Based on air quantity observations it is not necessary to make adjustment to the regulator/door R in the to make adjustment to the regulator/door R in the model as % error is no more than 5%. model as % error is no more than 5%.

However when comparing the predicted pressure However when comparing the predicted pressure drops across regulators, significant need for drops across regulators, significant need for adjustment was found. adjustment was found.


CONCLUSIONSCONCLUSIONS

Efforts to mathematically model some operating Efforts to mathematically model some operating mine regulators have been described. mine regulators have been described.

Theoretical calculations to predict airflow quantity Theoretical calculations to predict airflow quantity through regulators based on measured pressure through regulators based on measured pressure drop are inadequate due to leakage, geometry etc. drop are inadequate due to leakage, geometry etc.

It is necessary to quantify the resistance of the It is necessary to quantify the resistance of the leakage path based on regulator opening area and leakage path based on regulator opening area and then recalculate the total resistance of the then recalculate the total resistance of the regulators. regulators.


CONCLUSIONS Cont.CONCLUSIONS Cont.

An investigation was undertaken as to whether the An investigation was undertaken as to whether the Real Time Airflow Monitoring system can Real Time Airflow Monitoring system can accurately detect changes in a ventilation network accurately detect changes in a ventilation network and identify constraints.and identify constraints.

The system was able to detect changes and to The system was able to detect changes and to predict the changes accurately. predict the changes accurately.

Limitations caused by transient period delays have Limitations caused by transient period delays have been examined. been examined.

It is important to update the simulation models It is important to update the simulation models based on real time data.based on real time data.

Documents

Main Shaft Incline Shaft Vent Shaft 116’ Adit 228’ Level 140’ Level Sensor # 1 Sensor # 2 94’ Adit Regulator 154’ Winze North American / Ninth U.S. Mine