A case study for cooling tower application:
A food processing plant in Arizona had a chemical reduction goal and maintenance problems with the facility’s cooling tower and heat exchangers. The towers are located ground level, and in a position where seasonal dust storms blow dirt and particles into the towers and the cooling tower media became heavily scaled over time, thus greatly affecting efficiency. The facility also utilized a large amount of biocide to keep the bacterial growth and algae under control. As a result, periodic cleaning (with the associated downtime) and most important, differential pressure readings in the facility’s plate heat exchangers, necessitated an increase in maintenance work
Industrial Water Innovations Cooling Tower Conditioning System, installed in early 2017 and shortly after, the facility was able to stop all use of biocides and the cooling towers and heat exchangers are now operating at optimum efficiency.
This particular cooling tower only operates Monday to Friday. Every Monday, the cooling tower starts up again with a larger micro count and, depending on the weather, more debris in the basin than the previous week.
A micro count analysis performed before start of operations on Monday, rendered the below results:
Coliform: 320 (CFU/ml), Aerobic: >10,000 (CFU/ml), ORP: 217mV, Temperature: 63F
The results of the micro count analysis after only 1 day of the system running (Tuesday)
Coliform: 7 (CFU/ml), Aerobic: 2,100 (CFU/ml), ORP: 217mV, Temperature: 63F
Note: The only chemical used in the cooling tower is corrosion inhibitor due to the extensive network of steel pipes in the facility.
The basin blowdown set point for the tower is set at 2600uS. The cooling tower basin is maintained by the conditioning system at values around 800 to 900 uS, and peaks of up to 2300uS when weather conditions are not favorable. The blowdown set point is seldom if ever reached.
The cooling tower basin and filter media, conditioned by the system. Scale has dropped off, the water is completely translucent and free of cloudiness, no odors are perceived and no algae growth has been observed anywhere in the tower. Return piping with directional jets, adjusted to prevent stagnant areas and particle build up.
The plate heat exchangers were previously cleaned every 4-12 weeks, accomplished by total disassembly, removal of gaskets, acid cleaning in a recirculation tank, and reassemble with new gaskets. This involved about 16-24 hours plus the cost of materials. Since the installation of the conditioning system, we have reduced this to an annual cleaning consisting of separation in place, low pressure hose off the plates, and re-compress. This is now accomplished in less than 4 hours and no material cost.
Engineering Manager – Tucson Plant
The facility’s cooling tower was originally installed in 2002. Industrial Water Innovations system went online in early 2017, and the facility has noted the following:
The cooling tower has not reached a blowdown set point in many months. This has resulted in a 90% reduction in water waste and saved chemical corrosion inhibitor.
Eliminated all bacterial and algae growth without the use of biocide chemical. A savings of $25,000 per trimester.
Eliminated the required maintenance for the tower basin. A full day for a crew of 3 cleaning the tower basin once a year.
Observed differential pressure readings in the plate heat exchangers have been stable for months and have not had to do any maintenance. A savings of 48 hours on maintenance activities and associated production downtime to maintain the heat exchanger. This was every 3 months and now it is a once a year activity.
There is a noticeable break down of previously formed hard scale deposits, which are now falling into the tower’s basin where the system catches them and filters them out.
Progressively, the cooling tower fill is becoming cleaner over time. It is expected that the yearly cleanup of the media would not be necessary.
Maintenance on the cooling tower and heat exchangers has been practically eliminated or significantly reduced.
The heat exchanger was opened for inspection of the plates 10 months after installation of the conditioning system. These pictures, taken as soon as it was opened and had not been maintained or washed yet, show the condition of both sides of the plate. Our client noted they are extremely clean and the small amount of hard water deposits on them flake off easily when touched.
High pressure wash and acid bath was not required to clean them.
Before the installation of the conditioning system, the facility maintained the plate heat exchanger every 3 months by dipping the plates in acid to aid in the removal of calcium deposits. With the conditioning system online, the maintenance was done after 10 months of continuous operation and the small deposits found were easily washed off with a low pressure water hose eliminating the need for acid.
The facility is able to save not only money and maintenance hours, but increase their employee safety by eliminating the need of handling dangerous chemicals and their storage.
There is a gradual and continuous improvement observed in the cooling tower fill conditioned by the system. Most of the scale has dropped off and continues to improve the condition of the fill and particle build up. Any free particles drop in the basin where they are captured by the system.