Mine ventilation fan specification and evaluation
This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and the operating conditions are discussed. Over the anticipated life of a mine’s ventilation system, the operating requirements will invariably change. Operating duties that define the range of the ventilation requirements need to be established. Apart from achieving planned operating pressure and volume range, consideration should be given to fan performance flexibility to meet unplanned changes in operating conditions. Operating conditions affect the type of equipment, materials of construction, and equipment design.
The paper proceeds to discuss common operating challenges such as vibration, parallel operation, mechanical failure, erosion and corrosion, and deficient fan performance. Vibration problems generally fall into one of two categories, namely, aerodynamic vibration or mechanical/structural vibration. Some typical causes of vibration are reviewed. When two or more fans are operating in parallel, all fans need to be capable of stable operation. Conservative engineering practices and standards are recommended to avoid premature mechanical failures. Erosion and corrosion can shorten the equipment life and result in unsafe operating conditions. Factors, which negatively affect fan performance, such as flow conditions and erosion, are reviewed. Apart from identifying the potential operating problems, likely causes and remedies are given.
Topics such as fan type, layout configuration, system effects, accessories, fan rating practices, quality assurance, and fan testing are discussed. Physical site constraints help determine the most appropriate layout configuration which can introduce fan system effect losses. Invariably, fans are supplied with accessories. The losses associated with these accessories should be the responsibility of the fan supplier. Fans ought to be rated in terms of generally accepted standards and practices. An objective is to purchase equipment of appropriate quality for its intended use. A case is made for factory-performed mechanical and performance testing.
The paper concludes with suggestions on what should be covered when evaluating different fan options and suggestions on the verification of supplier claims and guarantees. Before a comparative aerodynamic evaluation is possible, all performance requirements need to be consistently interpreted by all parties. An illustrative comparative aerodynamic performance analysis example of two operating points for two suppliers is given. In many instances, the cost of energy consumption over the life of the fan is more than the equipment’s initial capital cost. An illustrative comparative power analysis example is given. Conclusions based on these analyses are discussed.
Initial capital cost tends to be the easiest cost to calculate and evaluate. The initial capital costs are not only the equipment cost but also the installation and commissioning costs. Maintenance costs are seldom considered when specifying and evaluating ventilation equipment; yet, over the life of the equipment, these costs are significant. Typically, fans and associated equipment are not considered part of a mine’s production equipment, however, their reliability can have an effect on the mine’s production. A case is made for the degree of operational flexibility to be part of the equipment evaluation process.
There are many relatively inexpensive features that can be designed into fans to improve the fan life, ease of installation, and equipment maintainability. In selecting a vendor, a proven track record, qualifications, and experience in the design and manufacture of similar equipment are important factors to consider. To effectively evaluate a project, a weighting system is beneficial.