Because of the competitive nature of snowmaking, and the increasing number of suppliers introducing new product developments, it is important for the smaller operator with an existing system to be aware of his own system’s capabilities, and how these may be affected by new developments. He may not be in the market for a “total system,” but in some cases the operating efficiencies of the existing system can be improved.
For example, during the past summer a client requested a general system survey and engineering report, with recommendations regarding improvements. This system contained electric compressors supplemented by portable diesel compressors. On the basis of the general engineering analysis it was determined that the volumetric capacity of the air system aftercooler was grossly undersized relative to the total volumetric capacity of both the electric and the portable compressors.
In addition, it was established that water and entrained oil suspension was being introduced into the air distribution system, probably partially due to the portable diesel compressors, with the result that the heat-transfer surfaces of the aftercooler were fouled to the point where heat-transfer efficiency was reduced to virtually zero. In a situation like this, even if the aftercooler had been properly sized, the reduction in heat-transfer efficiency would have basically eliminated the effectiveness of the aftercooler.
The recommendation was for minor piping modifications that would result in a system in which all air discharging from both the electric compressors and the portable diesel compressors would feed into a receiver tank which was mounted outside of the control building. This configuration provided the dual benefit of pre-cooling the compressed air as well as removing some of the moisture and entrained oil from the compressed air prior to its passage through the air system aftercooler.
In addition to this piping modification, it was recommended that a new and properly sized air system aftercooler-cum-moisture separator assembly be installed. Finally, in conjunction with this installation, it was recommended that piping system modifications be completed that would enable the operator to back-wash the internal surfaces of the tube bundle in the moisture separator, without removing the moisture separator from the actual piping system. In this way, the operator is able to flush the internal surfaces of the tube bundle in the aftercooler as frequently as is considered necessary, on a routine preventive maintenance schedule.
The cost of these modifications amounted to less than $10,000.00, and the most tangible result is that with the cleaner, dryer air throughout all sections of the mountain distribution system, the operator is now able to get the same number of snowmaking units on-stream at an ambient temperatures of 20-deg., that he used to be able to get on-stream at ambient temperatures of zero.
In another instance it became apparent that the air system aftercooler-moisture separator was properly sized to handle the capacities of the system, but was not being used as effectively as it could have been. In a great number of air system installations it has been found that the moisture separator of the aftercooler assembly is dependent on manual blow-down procedures for removal of condensed moisture and entrapped oil. In this type of situation dependence on the human element increases the probability of inefficient operation. For example, when the moisture separator is not blown down regularly moisture and oil suspension accumulates in the moisture separator to the point where it is carried into the mountain distribution piping.
It was recommended that the drain piping on the moisture separator be equipped with an automatic float trap-type discharge device, which continuously and automatically drains the condensed water and oil suspension from the moisture separator. This float trap installation also included a manual bypass system to enable service to the float trap without having to shut down the system.
In conjunction with this float trap assembly it was recommended that a sight-glass be incorporated into the moisture separator. All moisture separators come equipped with fittings to be used for integration of sight-glass assemblies. If the float trap is not functioning properly and water and oil suspension begins to accumulate in the moisture separator this condition is visually apparent in the sight glass. Then the manual bypass can be put on-stream, and the float trap can be removed from the system for service. This installation, including materials, amounted to less than $200.00, and can be considered cheap insurance against introduction of water and oil contaminants into the mountain distribution piping.
Finally, it is important that the components can be operated properly. On more than one occasion it has been established that air system pressures are allowed to drop as low as 65 psi at the compressor discharge. Consequently, the air pressure at the snowmaking unit might be as low as 50 psi, and the snowmaking equipment will not function at peak efficiency.
Besides being inefficient, low operating pressures will generally create conditions in which oil contamination is drawn from the actual compressor chamber into the distribution system. When a compressor is designed for operation with discharge pressures of 100-110 psi, it is recommended that snowmaking operation be carefully controlled so that air pressure does not drop below 90 psi at the compressor. This will help to minimize problems associated with the suction of oil contaminants into the air system, especially in conjunction with rotary screw compressors, in which the compression is dependent on an oil seal.
In summary, the operator should not be complacent with respect to his esisting system.
There is every reason to believe that periodic system inspection, completed with the idea of assessing the existing operating characteristics and evaluating the applicability of new product development, would result in a continuously effective system.
