Kolmetz.com Cooling Tower Monitoring 10 Page 3
1. Introduction
Most of the water employed for industrial purposes is used for cooling a product or process. The
availability of water in most industrialized areas and its high heat capacity have made water the
favored heat transfer medium in industrial and utility type applications. Direct air cooling is
finding increasing use, particularly in water deficient areas but is still far behind water in total
numbers of applications and total heat transfer loading.
During recent years, the use of water for cooling has come under increasing scrutiny from both
environmental and conservational points of view and as a result, cooling water use patterns are
changing and will continue to do so.
From the conservational point of view, many systems pass cooling water through the plant
system only once and return it to the watershed. This creates a high water withdrawal rate and
adds heat to the receiving stream. On the other hand, cooling towers permit reusing water to
such a large extent that most modern evaporative cooling systems reduce stream withdrawal
rates by over 90% compared to once through cooling. This substantially reduces the heat input
to the water streams but not to the environment, since the heat is transferred to the air.
From the environmental point of view, the particulates from the drift loss, blowdown from the
cooling towers and the Volatile Organic Compounds (VOC) and Hazardous Air Pollutants
(HAPs) that would leak from the heat exchangers into the cooling water systems and then be
emitted to the adjacent areas need to be controlled. Especially in environmentally sensitive
areas, the leakage of VOC and HAPs into cooling water systems has caused a great concern and
may require hydrocarbon leakage monitoring by the regulatory agencies.
