are necessary for the recooling of cooling water heated up by frequency convert- ers and induction furnaces. There are 3 types of cooling towers used in direct combination with induction furnace systems (look pages before).
a) Dry cooling towers, which work like vehicle radiators with cooling vanes and high air volumes, can be used in central and northern Europe. Relevant heating equipment and ventilator covers must be provided for extremely low temperatures. In order to ensure the maximum supply temperature for fre- quency converters of 34 °C, supplementary coolers are used which operate from the municipal water supply.
b) Closed cooling towers, which work like dry cooling towers, but which at air temperatures above the maximum supply temperature also use spray water to provide the required cooling performance.
These two types of cooling towers are connected directly to the system com- ponents to be cooled, for recooling without water/water-exchangers. No water consumption occurs with “a”. For “b” however, the water that evapo- rates must be replaced.
c) Open cooling towers, in which a water/water-exchanger must necessarily be used, have spray nozzles, which atomise all the cooling water and then cool it down by means of the air flow through the tower. This water then cools the system water down to the required supply temperature in the water/water- exchanger. These systems are very efficient, although they do have the disad- vantage of “water consumption”, which may be up to 5% of the hourly throughflow over a 24-hour period.
