Case Study

Cooling Tower Water

Industry
Food & Beverage

Site
Northgate, QLD, Australia

Application
Concentrator Cooling Tower Water Filtration

Problem Description
Customer was seeking a solution to major corrosion issues they had identified under bio film and scale deposits in their cooling systems. Chemical water treatment was confirmed as a main contributor to corrosion rates.
Side stream filtration was identified as a primary measure to address scale and bio film buildup, and thus reduce corrosion rates.
The cooling tower system consists of two towers with balanced sumps, a system flow rate of 83 LPS and a total system water volume of approximately 8,000 L.
The towers are located in the vicinity of a dirty and dusty fruit and vegetables unloading area.
The cooling tower system contained a significant amount of dirt. In only some weeks, a 15 cm thick layer of dirt had accumulated at the bottom of the sump. This dirt provides a food source and protected environment for the development of bacteria. It also contributes to the formation of scale, and accelerates corrosion in the entire system.

Imatech Solution
Imatech installed a 230 LPM Zero Gravity Filters - Easy Clean 3-Pod” self-cleaning filter, with 75 micron filter elements, to continually remove environmental dirt and other non-dissolved solids from the tower water.
The combination of flow rate and micron rating is designed to deliver a solids removal rate which slightly exceeds the solids ingress - resulting in an increasingly cleaner system.
The filter discharge was equipped with a sweeper nozzle system to direct as much of the contamination solids to the filter suction inlet, and thus keep the sumps as clean as possible.

The Results
The ZGF filter operates 24/7 without requiring any maintenance bar the 6-monthly and 12 monthly preventative inspections.
The water in the system is kept clean and build-up of deposits of dirt no longer occurs.
Corrosion coupons have been installed as part of this system to monitor the continued improvements in corrosion rates for stainless steel, mild steel and copper alloy.
In cooperation with the non-chemical VRTX water treatment system, the ZGF filters deliver - Very Good” Corrosion Rates which are consistently at 3 mpy or less for Mild and Stainless Steel, and 0.3 mpy or less for Copper Alloy.

The continuous removal of suspended solids leads to cleaner systems and considerably reduced deposits, resulting in lower risk of bacterial growth and energy savings through better heat exchange efficiency.

In comparison with chemical treatment, this treatment system of VRTX and ZGF can save up to 10 million Litres of water as it can operate at higher cycles of concentration.
Elimination of chemicals from the water treatment protocol contributes to the improvement of the corrosion results, and delivers approximate savings of A$15,000 per year.

Combined with the water savings, valued at around A$10,000 per year, the system delivers direct cost savings of A$25,000 per year for this tower system. Savings associated with better system performance (energy) and longer system life (corrosion) have not even been considered.