Felipe Calizaya Miles Stephens

2010

UTILIZATION OF BOOSTER FANS IN UNDERGROUND

COAL MINES

Stewart Gillies

Univ. of Utah, Salt Lake City, UT

Missouri Univ. of S&T, Rolla, MO

Introduction

Project Objectives

Utilization of Booster Fans

U of U Coal Mine Model

M S&T Experimental Mine

Summary

Outline

INTRODUCTION

Booster Fan:

1)An underground fan installed in the main air stream to handle the quantity of air circulated through a section

2)Installed in a permanent bulkhead and equipped with a set of airlock doors and fan monitors

3)A properly sized and sited booster fan can be used to create safer work conditions and allow the extraction of minerals from great depths

Introduction

Section A

Section B

Booster FanSurface

FanRegulator

Stopping

Intake

A booster fan decreases main fan pressure & leakage It requires a fan monitoring system

Introduction

Transducer List

M1 Smoke

M2 CO

M3 Air velocity

M4 Diff. pressure

M5 Vibration

M6 Temperature

Project Objectives

Investigate the conditions under which booster fans can be safely used in U/G coal mines

Monitor the performance of booster fans in a laboratory model and an experimental mine

Develop a booster fan selection method

Educate/Train M.S. & Ph.D. students in advanced mine ventilation

Utilization of Booster Fans

In the U.S., booster fans may be used in metal and non-metal underground mines

They are not allowed in U/G coal mines, except in anthracite mines (CFR 75.310)

Currently, booster fans are used in a number of coal mines in Australia, United Kingdom, Poland, India, others

In western U.S. mines, coal is extracted from seams covered with more than 1000 m of overburden, with increased gas and heat flow rates

Ventilation Problems in Coal Mines

In most cases, high pressure main fans are used to supply the required quantities of air to the face

Booster fans can be used to assist main fans in overcoming these adverse conditions

High pressure High air leakage

Planning Example

100 K

120 Kcfm

80 K

Main Fan

Heading

GOB

83 K

Case 1: Determine the fan size(Single- Fan System)

P = 10 in.w.g

Q = 699 kcfm

Planning Example

100 K

120 Kcfm

80 K

Main Fan

Heading

GOB

83 K

P = 7.2 in.w.g

Q = 663 kcfm

Booster Fan

Case 2: Determine the best combination of fan pressures

Main Fan

P = 2.2 in.w.g

Q = 576 kcfm

Booster Fan

Solutions to Sample Problem

1. Single Fan System

Main Fan

H, in.w.g Q, kcfm Power, HP

10.0 698.8 1101.2

2. Two Fan System

Main Fan 7.2 662.7 751.9

Booster Fan 2.2 576.1 199.7

Total Power: 951.6 HP

Total Power: 1101.2 HP

Net Power Saving: 150 HP

The University of Utah’s Coal Mine Model

Model used to study leakage through “stoppings”

U of U Coal Mine Model

This is a 14.6-cm diameter ductwork configured in a common U shaped ventilation system

The intake and return drifts are joined by five cross-cuts (four stoppings and a face)

The system is powered by a 3 kW centrifugal fan equipped with a variable frequency drive

The U of Utah’s Coal Mine Model

Perforated gate valves used to represent stoppings

A Leakage Flow Test

Objective: to study leakage flow through stoppings in a laboratory model

A test is conducted by installing a set of “stoppings” in the model & running the fan

Air pressure measurements (Hs & Hv) are conducted. Then, these are use to calculate leakage flow quantities

Test Results

Total Percent Leakage = 42 %

SIMULATED MINE LEAKAGEStopping Size #1

Fan Setting - 1500 Pa

3.28

2.99

2.87 2.85

2.60

2.80

3.00

3.20

3.40

A B C D

Stopping Location

Leak

age

Qua

ntity

, m3 /m

in

Q (fan) = 28.6 m3/min

Q (face) = 16.6 m3/min

Future Work

This model will be upgraded to include a booster fan, a gas injection system, and a set of ventilation monitors.

Carbon dioxide will be used to simulate the gas generated at the face

Objective: to determine the conditions under which flow recirculation can be avoided

Booster Fan (3 kW)Main Fan (5kW)

Return

Inlet

1.2 mRegulator

?Gas Source

ΔH Ventilation MonitorsCO2

4.5 ftB

GateIn

Out

Reg

.F

AC

E

1-ft

B

Gate

.

In

Out

Ble

eder

1.5 ft9.0 ft

The U of Utah’s Booster Fan Model

Simulated Mine Gob

The Missouri S&T Experimental Mine

The Missouri S&T Experimental Mine is a limestone mine, located outside Rolla, MO

The mine is accessed by two adits and has three raises to surface

It is ventilated by a 30 kW Joy axial fan(Fan duty: Q = 23.6 m3/s @ Ps = 1,000 Pa)

The Missouri S&T Experimental Mine Map

D

D

Initial Plans:

The Missouri S&T Experimental Mine

Upgrade the main fan system

Install two booster fans in bulkheads

Install an electronic monitoring system (To monitor: press, quantity, vibration, bearing T)

Collect data to determine optimal placement of booster fans

Summary

The U of Utah and the Missouri University are investigating the conditions under which booster fans can be used in U.S. U/G coal mines

• Ventilation surveys in two non-U.S. coal mines where B-Fans are used regularly

The project includes:

• Ventilation surveys in two deep and/or extensive U.S. coal mines

Questions?

R

R

DD

R

R

DD

392 Pa751 Pa

Ma

ing

ate

4N

R

R

Main Surface Fan 282 m3/s @ 1054 Pa

50 m3/s

54 m3/s

Borehole Fan 12 m3/s @ 4500 Pa

37 m3/s

R

6 m3/s

X

DD

DD

X

D

DXD

Twin Boosters @ 472 rpm 220 m3/s @ 800 Pa

1154 Pa

Booster Fans at Peabody Energy’s North Goonyella Coal Mine, Australia

Booster Fans at Peabody Energy’s North Goonyella Coal Mine, Australia

Main Fan Duty:

Twin centrifugal fans installed in the main return Each fan powered by a single 600 kW motor Central bypass to maintain ventilation when fan is off

Q = 600,000 cfm @4.2 in.w.g.

Booster Fans’ Duty: Speed: 472 rpm

Q = 465,000 cfm @ 3.2 in.w.g.

Booster Fans at Peabody Energy’s North Goonyella Coal Mine, Australia

Summary

This project also includes:

• Monitor the performance of booster fans in a laboratory model and an experimental mine

• The development of an efficient booster fan selection program

• Training of six graduate students in advanced mine ventilation

Questions?Questions?