Filtration FAQ

What are the benefits of filtration?

Suspended solids are the most common and one of the more troublesome contaminants in cooling water. The cooling tower acts as an air-scrubber and constantly adds solids to the cooling water. This increases the cost of chemical water treatment because increased suspended solids requires additional chemicals for treatment. Like any treatment program, if not properly controlled this will also result in increased energy costs. Increased chemical treatment costs, increased chiller head pressure, and a greater need to the clean tower basin all result from poor control of suspended solids.

The benefits to cooling water filtration are:

• Less energy Consumption, quantified by measuring changes in condenser approach temperatures.
• Fewer chemicals are required when suspended solids are removed from the cooling system.
• Less downtime by reducing the time needed to clean the tower basin, tower fill and condenser tubes.
• Less downtime can be the greatest savings of all if plant production is impacted.

 Does filtration increase my water costs?

 The Electric H20 filters can use city water or system water in backwashing mode. If system water is used (recommended) the amount of backwash only reduces the amount of bleed in the cooling system. Backwash can be adjusted to optimize the bleed/backwash relationship to avoid additional water consumption.

 How can I quantify the savings?

• First, an analysis of the suspended solids in the cooling water can be performed using a particle count of a cooling water sample. Then a second sample can be taken after the filtration system has been installed to provide a reasonable comparison. Electric H20 can select the filtration media based on the kind of contaminant in your water and the results of the water analysis or particle count.
• Energy can be quantified by establishing a baseline. Determine the condenser approach temperature and running hours for the prior cooling season and track the increase in the condenser approach temperature over the course of the cooling season. Your chiller manufacturer or Electric H2O can assist with this calculation through a comprehensive software modeling program. Savings introduced by the filter can then be quantified by measuring the condenser approach temperature for the cooling season after the improvements have been made.
• Reduced chemicals in the water treatment program are also a benefit. You may be able to reduce chemical treatment expenses by as much as 20%. This is dependent upon your contract and the level of suspended solids in the cooling water.
• The EH20 staff is experienced in water treatment and can recommend improvements that may include other aspects of cooling water treatment besides filtration. A third eye or opinion is always healthy.

How do I determine which filter to use?

Filtration can be accomplished using several different methods. Often the application will dictate how much filtration is required. Media filtration, where 97% of the solids are removed down to a 0.5 micron level, can be achieved through side-stream filtration. This level of filtration will remove most of the contaminants in the cooling water and will provide the greatest benefit. We recommend selecting a filtration system that is designed for a flow rate 5-10% of the cooling water recirculating rate or by calculating total cooling water system volume and dividing by either 60 or 48. This will determine the appropriate system turnover.

Separators are also useful filtration technologies in cooling water treatment. They are physically smaller than media filters and can be installed on a side-stream loop or full-stream loop. Separators remove particulate based on specific gravity and particle size.  Efficiency is less than that of a media filter, but separators are effective in removing the visible particulate found in the tower. Consult your Electric H20 representative for a comprehensive comparison of the two types.