In large systems, the dissipation of process or ambient heat generated by manufacturing, power generation and food processors often is accomplished by cooling towers. These structures facilitate the transfer of heat through the use of water.
5 Trends Driving the Need for Cleaner Water in Cooling Applications
Five trends are driving the need for high efficiency submicron filtration for process cooling:
- Water reuse and green initiatives (condenser and makeup water).
- Data center and semiconductor demand for high quality water.
- Requirements for improved cooling efficiencies.
- Demands for reduced maintenance and operational costs.
- Requirements for the creation of risk-assessment programs.
For many cooling tower systems, fine suspended solids in the cooling water are the cause of inefficacies. In addition to decreasing heat transfer efficiency, the suspended solids also can pose a health risk. These fine solids originate from the facility’s process, piping, atmosphere or makeup water source, or from the system’s internal biological growth.
During the cooling process, the cooling water absorbs large volumes of airborne particulate, acting as an air scrubber and filtering the surrounding air. With time, these fine particles can build up and settle within the system, adversely affecting cooling performance while reducing the life of wetted subcomponents.
Typically, 85 percent of the suspended solids in cooling water and hot water loops are smaller than 5 microns in size. Scientific studies have shown that these fine particles tend to be the adherent contaminants causing fouling of the cooling tower water, chilled water and heat exchangers. Such contamination reduces cooling system efficiency. High volumes of fine suspended particles will not always be eliminated solely with the use of a chemical program; therefore, fine filtration is an important addition.
High efficiency removal of fine particles and suspended solids can help reduce maintenance and operating costs.
The Cost of Working with Dirty Water
The presence of fine suspended and dissolved solids, in high volumes, can be harmful to a cooling tower and water loop, affecting the performance of the entire system. Fine particulates under 5 microns in size aid in contributing to the following challenges:
- Component clogging. This causes irregular distribution of the water across the cooling tower.
- Heat transfer inefficiencies. This require increased energy and water, driving costs upward.
- Scaling, fouling and bacterial growth such as Legionella. These cause quick degradation of components, resulting in early replacement, increased maintenance costs and health concerns.
- Unscheduled shutdowns and cleaning. These lead to increased operating costs.
- Early replacement of components (valves, pumps or heat exchangers, for instance).
- Increased and accelerated corrosion.
A high efficiency media filtration system can optimize water treatment efforts in several ways. Traditional sand filters lack fine-filtration capabilities and have relatively low capacities. High efficiency media filters offer submicron performance, higher flow, a compact design/footprint, automated operation and a low cost of operation.
A vertically oriented, stacked system can double the filtration capacity within the same equipment footprint.
High Efficiency Submicron Performance. The effectiveness of a high efficiency media filtration system lies in its use of microsand media coupled with crossflow filtration. These features allow the filters to capture particles under 1 micron in size.
Higher Flow. Crossflow technology enables optimization of the media bed. This improves filtration capacity and allows the design of a horizontal vessel. For instance, with a single 36" vessel, the horizontal design is capable of treating a flow of up to 1,090 gal/min. The filtration velocity through the media bed is faster than sand filters at 25 gal/min/ft² (60 m/hr) while delivering high water quality.
Lower Cost of Operation. An important consideration for any filtration system is the overall operating cost. This type of high efficiency filtration system potentially reduces operating costs in several ways. It can:
- Minimize water consumption by the filter. The filter requires up to 50 percent less water during backwash when compared to traditional multimedia filtration systems.
- Achieve energy savings in heat transfer applications by helping prevent the formation of sediment and biofilm. This leads to greater heat exchanger efficiency.
- Improve the effectiveness of the chemical treatment by reducing total suspended solids.
- Reduce maintenance costs. A high efficiency filtration system requires little human intervention with few maintenance tasks.
Automated Operation. A high efficiency filtration system provides an automated experience along with maintenance reminders and a user-friendly interface. These features help simplify operating and maintaining the system.
High efficiency media filters offer submicron performance, high flow, a compact design and automated operation.
Compact Footprint. The use of microsand media yields a filtration system that requires less media. This allows the system to achieve high levels of efficiency with a smaller footprint. (With some designs, the filtration system is up to 80 percent smaller and lighter in weight than multimedia filters.) In addition, some designs allow for customization to better suit the application. One such customization is a vertically stacked system, which increases the filtration capacity within the same footprint. A lightweight, compact filter design also provides shipping savings and can reduce on-site infrastructure costs.
In conclusion, high efficiency removal of fine particles and suspended solids can reduce maintenance and operating costs while improving the bottom line. A water filtration system should help meet growing production goals and water reuse objectives.