Operation & Maintenance of Power Plants
Water treatment systems for cooling towers
New controlling technology enhances process efficiency and profitability of water treatment systems in cooling towers.
La nueva tecnología de control mejora la eficacia de los procesos y la rentabilidad de los sistemas de tratamiento de agua en las torres de refrigeración.
Neuartige Steuerungstechnologie erhöht Prozesseffizienz und Rentabilität von Wasseraufbereitungsanlagen in Kühltürmen.
Fig. 1. The mxControl 8620 is capable of processing up to four analogue, two RTD, and eight digital inputs as well as five relay and four digital transistor outputs and four optional analogue outputs – a total of 23 I/O (model dependent) – simultaneously.
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ater treatment systems in cooling towers are dynamic entities that are subject to numerous factors like varying operating and
environmental conditions, seasonal alteration in water chemistry, and compliance with tightening environmental regulations. Securing the requested water quality requires continuous control of source water, and permanent surveillance of the treatment process. At the same time, analysis requirements and compliance with environmental provisions create a growing need for analysis recording and transmission of relevant data concerning water output and quality. Te automation of water treatment systems reduces costs. It increases productivity, saves water and energy, and minimises the risk of chemical overfeed or underfeed while simplifying compliance with environmental standards. Water treatment systems for cooling towers can be controlled manually when water quality and operating conditions are consistent. Samples then have to be taken regularly by technicians,
who analyse the process conditions before determining the ratio between the supply of fresh water and chemicals required. Tey adjust the pH, ORP (oxygen reduction potential), conductivity, alkalinity, hardness, corrosion and other factors. Tese steps require in-depth experience as well as time and manpower. Sometimes however, the initial conditions may not be simple enough: high personnel costs, scarce and expensive water resources, and inconsistent water quality may create a need for more than manual chemistry control. Tis is where multi-parameter transmitters have recently established themselves. Tey are used as inline signal conditioners, sending analogue inputs to PLCs (programmable logic controllers). However, as global competition increases for water treatment OEMs (original equipment manufacturers), these companies are driving their suppliers to incorporate multiparameter transmitters into single-platform, multifunction flexible controllers – reducing controller and instrumentation costs in some cases by as much as 50 per cent as well as saving water and chemical costs.
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