In 2010, a large-scale project for construction of five new world-class resorts was launched in the Northern Caucasus Federal District. One of the problems for ski resorts is occasional and unpredictable snow falling out. Several days without a snowfall in the height of the season can result in huge losses and deterioration of the resort reputation.
A technical assignment for a pump station for feeding of snowmaking machines was developed by Rosengineering. Pumps were required that would operate with high pressure, heavy feeding and with a possibility for wide-range control. The difficulty was that the water contained fine particles (sand). Therefore, the pump equipment department was assigned with not an easy task to select pumps capable of creating high pressure and heavy feeding, with wide range of control, and equipped with a sealing resistant to sand. The use of standard face seal was unacceptable. The problem could be solved by using a graphite-cord seal but it can not keep pressure as low as 64 bar, not to mention 100.
The solution was to use a special seal in the pumping section that is designed for pressure of up to 100 bar and at the same time protected from sand and fine inclusions. This seal was based on graphite cord in a reinforced casing.
However, the problem with the sealing was not the most difficult. According to the first calculations, the motor power would exceed 335 KW. Motors of such power inevitably start to produce a huge amount of heat when changing their speed that results in overheating and damages. Moreover, if the speed is reduced, the lubricating layer stops to form in the motor bracket that leads to even greater loads and heating.
We decided to use electric motors of a special design with closed bracket and increased number of heat-removing fins on the casing. Such design allows using an electric motor with a frequency converter and changing the pump parameters.