1 Booster Fans - Some considerations for their usage in underground coal mines S. Gillies, C. Slaughter, F. Calizaya and H. W. Wu 13th United States/North.

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Booster Fans - Some Booster Fans - Some considerations for considerations for

their usage in their usage in underground coal underground coal

minesminesS. Gillies, C. Slaughter, F. S. Gillies, C. Slaughter, F.

Calizaya Calizaya and H. W. Wu and H. W. Wu

13th United States/North American Mine Ventilation Symposium, 13th United States/North American Mine Ventilation Symposium, 13-16 June 2010 13-16 June 2010

Booster Fans in Parallel - Inlet End

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IntroductionIntroduction In a coal mine environment a booster fan is an In a coal mine environment a booster fan is an

underground ventilation device installed in the underground ventilation device installed in the main airstream (intake or return) to handle the main airstream (intake or return) to handle the quantity of air circulated by one or more quantity of air circulated by one or more working districts. working districts.

It is installed to operate in series with a main It is installed to operate in series with a main fan and boost the air pressure of the passing fan and boost the air pressure of the passing ventilation air. ventilation air.

To accomplish this objective, the fan is installed To accomplish this objective, the fan is installed in a permanent stopping. in a permanent stopping.

It is equipped with airlock doors and It is equipped with airlock doors and interlocking devices between main and booster interlocking devices between main and booster fan controls. fan controls.

It incorporates a monitoring system to assess It incorporates a monitoring system to assess continuously the operating conditions of the fan.continuously the operating conditions of the fan.

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IntroductionIntroduction

A NIOSH funded study is being A NIOSH funded study is being undertaken by the University of Utah undertaken by the University of Utah and the Missouri University of Science and the Missouri University of Science and Technology (Missouri S&T) with and Technology (Missouri S&T) with objectives to investigate the objectives to investigate the conditions under which booster fans conditions under which booster fans could be used safely and efficiently in could be used safely and efficiently in underground coal mines. underground coal mines.

Booster fan usage is very common in Booster fan usage is very common in many metal/non-metal mines and their many metal/non-metal mines and their usage experience can assist safe usage experience can assist safe introduction to US coal mines.introduction to US coal mines.

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IntroductionIntroductionSpecifically, the study is directed at: Specifically, the study is directed at: Examining when booster fans become an attractive Examining when booster fans become an attractive

and economically viable solution in coal mines due and economically viable solution in coal mines due to increases in air requirements at higher to increases in air requirements at higher production rates, increases in extent and depth of production rates, increases in extent and depth of workings and where mines are developed under workings and where mines are developed under environmentally sensitive areas,environmentally sensitive areas,

Collecting reliable information on airway Collecting reliable information on airway resistances and flow requirements typical in large resistances and flow requirements typical in large US coal mines, and simulating possible booster fan US coal mines, and simulating possible booster fan influence.influence.

Collecting fan performance data typical in US coal Collecting fan performance data typical in US coal mines where the use of booster fans could be mines where the use of booster fans could be contemplated,contemplated,

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

Developing a booster fan selection method to assist Developing a booster fan selection method to assist the ventilation engineer at the planning stage.the ventilation engineer at the planning stage.

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Approaches Adopted Approaches Adopted The use of booster fans to assist in the The use of booster fans to assist in the

ventilation of either individual panels or the ventilation of either individual panels or the entire mine is not common in coal mines due, entire mine is not common in coal mines due, normally, to the ease of installing additional normally, to the ease of installing additional shafts or larger surface fans compared to the shafts or larger surface fans compared to the operational problems and cost associated operational problems and cost associated with installation of underground booster fans.with installation of underground booster fans.

However, with significant increases in However, with significant increases in volumetric requirements at higher production volumetric requirements at higher production rates, increase in block geometry and depth rates, increase in block geometry and depth of workings together with mines being of workings together with mines being developed under environmentally sensitive developed under environmentally sensitive areas, booster fans become a more attractive areas, booster fans become a more attractive and economically viable solution.and economically viable solution.

Various safety considerations need to be Various safety considerations need to be implement with introduction of booster fans.implement with introduction of booster fans.

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Background Background Booster fans were first used in coal mines in the Booster fans were first used in coal mines in the

United Kingdom in the early 1900’sUnited Kingdom in the early 1900’s Currently, booster fans are used in coal mines in Currently, booster fans are used in coal mines in

several countries including the United Kingdom, several countries including the United Kingdom, Poland, and Australia (Jobling et al, 2001).Poland, and Australia (Jobling et al, 2001).

The purpose of booster fans is to overcome a The purpose of booster fans is to overcome a fraction of the mine’s frictional losses in a fraction of the mine’s frictional losses in a similar manner to surface fans overcoming all similar manner to surface fans overcoming all losses within a mine.losses within a mine.

Booster fans may, for example, be located in Booster fans may, for example, be located in individual gate roads to boost panels or in main individual gate roads to boost panels or in main return headings to boost the entire mine circuit. return headings to boost the entire mine circuit. It is the second application that is likely to It is the second application that is likely to become more common.become more common.

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Advantages of Booster Advantages of Booster FansFans

Reduced intake to return pressure Reduced intake to return pressure differentials and hence reduced leakage and differentials and hence reduced leakage and need for airlocks; need for airlocks;

Reduced surface fan pressures, allowing Reduced surface fan pressures, allowing existing installations to remain in place; existing installations to remain in place;

As an alternative to avoid potentially more As an alternative to avoid potentially more expensive options such as shafts, additional expensive options such as shafts, additional headings or prohibitively large surface fans; headings or prohibitively large surface fans; and and

As a method to be used to boost single As a method to be used to boost single panel(s) rather than the whole mine to panel(s) rather than the whole mine to minimise regulation and hence mine minimise regulation and hence mine resistance.resistance.

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Advantages (cont.)Advantages (cont.) Use of booster fans can lead to lower Use of booster fans can lead to lower

operating electricity power costs as operating electricity power costs as they augment mine fan power and do they augment mine fan power and do not destroy energy as occurs with use not destroy energy as occurs with use of mine regulators. of mine regulators.

As such they are a better alternative to As such they are a better alternative to regulators for balancing or controlling regulators for balancing or controlling airflow through mine parallel splits. airflow through mine parallel splits.

They may extend life of mine fan duty They may extend life of mine fan duty as they augment mine fan power. as they augment mine fan power.

Their introduction allows deferral of Their introduction allows deferral of installation of a new ventilation shaft or installation of a new ventilation shaft or other major capital facility.other major capital facility.

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Disadvantages of Booster Disadvantages of Booster FansFans

Monitoring of their off/on status is required Monitoring of their off/on status is required particularly in gassy atmospheres. Automatic particularly in gassy atmospheres. Automatic shut off is required if the main fans stop to shut off is required if the main fans stop to avoid underground recirculation.avoid underground recirculation.

Shut off of either main surface or booster fans Shut off of either main surface or booster fans can trigger a requirement of withdrawal of all can trigger a requirement of withdrawal of all miners to the surface whether the shut off is miners to the surface whether the shut off is caused by an electronic fault or a serious caused by an electronic fault or a serious system failure. system failure.

Their use in a gassy atmosphere may require Their use in a gassy atmosphere may require flame-proof electrics or placement of electric flame-proof electrics or placement of electric motors in intake air. This may necessitate use motors in intake air. This may necessitate use of extended drive shafts from intake to return of extended drive shafts from intake to return air sides of a bulkhead. air sides of a bulkhead.

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Disadvantages (cont.)Disadvantages (cont.) Capital cost of booster fans will certainly be Capital cost of booster fans will certainly be

greater than cost of regulator installation. greater than cost of regulator installation. If used in a gassy atmosphere the fan must If used in a gassy atmosphere the fan must

be designed with anti-sparking be designed with anti-sparking characteristics. This means using stainless characteristics. This means using stainless steel rotor and blades and that the most steel rotor and blades and that the most commonly used axial fan impeller material, commonly used axial fan impeller material, aluminum, cannot be used. aluminum, cannot be used.

The layout of parallel intake and return The layout of parallel intake and return airways in collieries does not usually lend airways in collieries does not usually lend itself to the use of boosters. Most colliery itself to the use of boosters. Most colliery panels comprise multiple intake airways and panels comprise multiple intake airways and multiple returns in parallel. If one fan is used multiple returns in parallel. If one fan is used all return air to be boosted must be directed all return air to be boosted must be directed to one single airway. to one single airway.

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Disadvantages (cont.)Disadvantages (cont.) Colliery roadways are usually wide openings Colliery roadways are usually wide openings

with limited vertical dimensions. This shape with limited vertical dimensions. This shape does not lend itself to the accommodation of a does not lend itself to the accommodation of a large fan and therefore, a considerable amount large fan and therefore, a considerable amount of site preparation and removal of roof material of site preparation and removal of roof material is usually required.is usually required.

Competent stoppings are required where high Competent stoppings are required where high air pressures occur downstream of fans to air pressures occur downstream of fans to reduce leakage of return air into intakes and reduce leakage of return air into intakes and avoid recirculating flows. avoid recirculating flows.

In the event of some emergency situations such In the event of some emergency situations such as an underground fire or serious roof fall, it as an underground fire or serious roof fall, it may become critical to control the fan. This may become critical to control the fan. This requires remote surface control equipment. requires remote surface control equipment. There must also be proper warning devices on There must also be proper warning devices on the surface to indicate a stoppage of the the surface to indicate a stoppage of the booster fanbooster fan

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Regulatory Approaches for Regulatory Approaches for use of Booster Fans in Coal use of Booster Fans in Coal

Mines Mines In the US the use of booster fans in coal mines is In the US the use of booster fans in coal mines is prohibited based on a fear that the operation of a prohibited based on a fear that the operation of a booster fan installation could not be adequately booster fan installation could not be adequately controlled from outside the mine and could lead to controlled from outside the mine and could lead to abnormal recirculation conditions or other potential abnormal recirculation conditions or other potential hazardous situations (Kennedy, 1999). hazardous situations (Kennedy, 1999). No other major coal mining country appears to have No other major coal mining country appears to have this ban.this ban. With the use of available technologies booster fan With the use of available technologies booster fan installations are being operated in a controlled and safe installations are being operated in a controlled and safe manner, as can be seen in Britain and Australia.manner, as can be seen in Britain and Australia. Economic considerations alone mean that use of Economic considerations alone mean that use of booster fans should be considered as part of a complete booster fans should be considered as part of a complete economic assessment of existing or proposed ventilation economic assessment of existing or proposed ventilation designs.designs.

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Underground Positioning of Underground Positioning of Booster Fans in Coal Mines Booster Fans in Coal Mines

The use of booster fans in installations ofThe use of booster fans in installations of Fans in the mains returns, Fans in the mains returns, Fans in the panel returns and Fans in the panel returns and Fans that allow for recirculation of Fans that allow for recirculation of uncontaminated return air into the intake. uncontaminated return air into the intake.

Of the systems studied, the most Of the systems studied, the most prevalent is the use of booster fans in the prevalent is the use of booster fans in the main returns.main returns.

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Ventsim: Example of Booster Ventsim: Example of Booster Fan in Mains: Relative Pressure Fan in Mains: Relative Pressure

Across StoppingsAcross Stoppings

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Alternatives to Use of Alternatives to Use of Booster FansBooster Fans

Booster fans are installed under Booster fans are installed under certain circumstances when a mine is certain circumstances when a mine is short of air. Alternatives approaches short of air. Alternatives approaches are are Excavation of additional shafts,Excavation of additional shafts, Use of additional parallel airways to Use of additional parallel airways to reduce mine resistance, reduce mine resistance, Increase duty of surface fans.Increase duty of surface fans. Reduce mine leakage and increase Reduce mine leakage and increase efficiency.efficiency.

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Booster Fan Study StepsBooster Fan Study Steps To simulate booster fan behavior in at least To simulate booster fan behavior in at least

two deep and/or extensive U.S. coal mines, two deep and/or extensive U.S. coal mines, To examine two existing non-US coal mines To examine two existing non-US coal mines

where booster fans are used regularly. where booster fans are used regularly. To install a booster fan system with To install a booster fan system with

monitoring at the Missouri S&T monitoring at the Missouri S&T Experimental Mine. Experimental Mine.

To conduct air pressure/ quantity surveys at To conduct air pressure/ quantity surveys at the University of Utah’s coal mine the University of Utah’s coal mine ventilation model to determine critical ventilation model to determine critical parametersto avoid unwanted recirculation. parametersto avoid unwanted recirculation.

To develop a fan selection algorithm for To develop a fan selection algorithm for underground coal mines. underground coal mines.

To summarize the basic requirements for To summarize the basic requirements for the safe operation of booster fans. the safe operation of booster fans.

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Proposed Booster Fan Test Proposed Booster Fan Test Arrangement at Missouri S&T Arrangement at Missouri S&T

Experimental MineExperimental Mine

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AcknowledgementsAcknowledgements

The authors would like to acknowledge the The authors would like to acknowledge the National Institute for Occupational National Institute for Occupational Safety and Health (NIOSH)Safety and Health (NIOSH) for providing for providing financial support for this project. We would financial support for this project. We would also like to express our gratitude for also like to express our gratitude for Jürgen Jürgen BruneBrune, NIOSH Office of Mine Safety and , NIOSH Office of Mine Safety and Health Research, and Health Research, and Mike NelsonMike Nelson, , University of Utah Mining Engineering University of Utah Mining Engineering Department Chair, for their advocacy in Department Chair, for their advocacy in developing this project. The authors also developing this project. The authors also acknowledge the assistance of acknowledge the assistance of Various Mine Various Mine Managers and EngineersManagers and Engineers for supporting for supporting the study.the study.