Operational principle
Metso cooling towers provide an efficient solution for hazardous applications that cannot be feasibly cooled with water. These include cooling materials with high amounts of sulfuric acid (>160 g/l), chloride, fluoride, and precipitating solids, such as gypsum. The solution is fed from the top of the tower through pressurized nozzles, with the cooling air flowing upwards countercurrently to the solution. The air flow is generated by a fan located in the lower section of the tower. The cooled solution is collected from the bottom of the tower and fed to the subsequent process phase through piping or via a launder.
Process applications
A common use of the cooling tower is in the cooling of spent electrolytes in a zinc electrowinning solution circulation. In this application, the cooling tower's efficiency is clearly displayed – in fact, it has been shown that two to three older towers can be replaced with just one cooling tower. The cooling towers can also be used in gypsum removal and chloride removal circuits in zinc refineries.
Outside of the zinc industry, the cooling towers can, for example, be used for gypsum removal before solvent extraction and for the cooling of solutions in gold autoclave circuits to control process solution temperatures. With gypsum removal, considerable savings may be achieved through reduced maintenance and increased uptime.
Maintenance
Metso cooling tower maintenance is in a class of its own. A unique accessible top platform enables maintenance of demister elements during cooling tower operation by isolating the demister channels. This online maintenance principle increases the availability of the cooling tower, ensuring more stable cooling performance. For nozzle maintenance, the tower needs to be halted, but because the nozzles are easily accessible from the top of the tower, cleaning or replacement can be carried out quickly before continuing operation.
Towers are equipped with a curtain that prevents gypsum precipitation on the tower walls. The curtain moves with the airflow, minimizing gypsum precipitation on the curtain.
