COC - cycle of concentration in cooling water
COC or the cycle of concentration is a abbreviation or term used for the usage of cooling water. This figure specifies how often the fresh water is used, prior the blow down or bleed off from the cooling tower. In detail this means, in a cooling water system there are cooling towers where some of the cooling water is evaporated. By this evaporation, the water is cooled down using the effect of evaporation chill. The fresh water which is added to the cooling tower contains a certain amount of minerals. These minerals can not evaporate with the water, but they stay back in the cooling water. Over time the cooling water gets a higher concentration of minerals. As these minerals will lead to scaling or fouling in the system, the water has to be replaced. This is done by the so called blow down or bleed off, where part of the higher concentrated cooling water is drained from the system and replaced by feed water, which holds less minerals and so brings down the concentration in the cooling water.
The cycle of concentration specifies the relation in between the concentration of minerals in the feed water with the concentration of minerals in the cooling water. So assumed the feed water has 100 TDS and the cooling water has 400 TDS, the COC will be 4.
Cooling Tower, Cooling water treatment, Water savings due to higher COC.