Water treatment for the chiller system generally includes the following filtration steps.
- Filtration and Ultrafiltration Processes.
- Ion exchange and water softening.
- Addition of chemicals.
- Reverse osmosis systems.
Water Treatments for Chillers
The precise treatment processes fluctuate depending on the cooling tower’s needs, the state of the circulation, and the feed water. Next, we will explain the basic steps mentioned above.
Filtration and Ultrafiltration:
- Filtration is a process required to remove impure substances, such as organic matter and suspended solids, from the feed water.
- It is more effective to use filtration systems at the initial stage, as the eradication of suspended particles upstream can maintain the safety and efficiency of membranes and ion exchange resins against fouling
Ion exchange for water softening:
- If the water contains large amounts of hardness, there are certain treatments available to remove it.
- Water softening systems are effective at removing ions that cause water to increase in hardness.
- Typically, these ions tend to be magnesium, calcium, and iron ions which are selected and removed.
- Ion exchange resins provide a similar function by replacing these hardening ions with non-hardening ions, such as sodium ions.
Addition of chemicals:
- At this stage, chemicals such as anti-acid bicarbonates and other inhibitors are usually added to prevent the build-up of scale deposits.
- Fortunately, pretreatment can decrease the number of chemicals required during this stage, which is preferable since many of these chemicals are expensive.
Reverse Osmosis Systems:
- Reverse osmosis systems remove virtually all unwanted dissolved solids by filtering the feed water using high-quality semi-permeable membranes.
- The reverse osmosis process is incredibly efficient at producing ultrapure water for consumption or use in a variety of applications and is often the backbone of any well-designed water purification system.
Why is it essential to treat chiller water?
- While many problem areas can affect chiller performance, perhaps the biggest culprit is the contamination of its heat transfer surfaces.
- If a chiller’s tubes become covered or clogged with scale, sediment, or biological growth, their ability to transfer heat is significantly reduced.
- The rate at which this fouling occurs is highly dependent on the quality of the water in the system, but even a thin layer of contamination can significantly reduce overall efficiency.
- Chemical water treatment helps prevent this buildup of contaminants on heat transfer surfaces.
- Open systems, such as condenser water systems, that include a cooling tower require an ongoing chemical water treatment program.
- Closed systems generally require only a one-time chemical treatment.
- Concentration levels of water treatment chemicals that are too low, or that do not match the conditions encountered, will be ineffective.
- The wrong chemicals or concentrations that are too high can damage internal components.
- Even with a good water treatment program, the cleaning of chiller condenser tubes will be necessary.
- With a brush, annual cleaning can remove mud buildup, biological growth, and any loose material.
- If there is a buildup of scale on the tubes, it will usually need to be removed by a chemical cleaning process.
