Scheme of chemical water treatment
for open-circuit cooling system
Cooling systems in circulations are the type where cooling water is taken from the immediate environment (from the water stream, lake or any other kind of watercourse). The water turns its path only once in the cooling system and then it comes back. In the past this was the cheapest way of cooling in locations which were rich in cooling waters and thus resulted in its relative frequent use. In terms of investment such process was quite simple, undemanding and no problems occurred if the water characteristics were not such as to cause formation of deposits or sediments in the system.
Today, environmental regulations and taxes are directing us to use close water cooling systems, thus the cooling systems in circulation are rarely built. They can be accepted conditionally if ecological criteria and technical requirements allow performance of such way of water cooling. Although the problem there is the need to prepare the entire circulation of water. When ecological taxes were introduced the economic viability was questionable for such systems, since the operating costs are relatively high especially if pollution of cooling water occurs during the cooling process.
In the cooling cycle some problems occur mainly because of some particles which deposit in installations and devices. And there can be problems with microbiology, deposits, sediments and corrosion as well.
Bigger particles can be removed by means of mechanical filters. In the market today we can find various methods of mechanical filtration, f. e. self rinsing filters with cartridges.
Depositing and accumulating of smaller particles, of which removal by means of filtration would be too expensive, and formation of bio films is best prevented by constructional solutions. This can be done by eliminating of areas with too low velocity of water current. Dosing of biocides into the cooling water is absolutely unacceptable. Occasional sanitation is possible, but it requires suspending the part of the system which is being cooled. Problems with corrosion and deposits can be solved by adding phosphate preparations. However we need to pay a careful attention to the level of dosing if we don?t want to cause negative impacts on the environment.
