Frequently Asked Questions:
What is the typical improvement for an upgrade?
Around 35% increase in capability. This usually translates to a 2° to 4° F improvement in circulating water temperatures.
What else can be done to improve my tower's performance?
Improving a tower’s performance falls into two categories. Either the fill’s heat transfer capability must be improved or the water circulating over the tower must be exposed to more air. We choose the first alternative which is to improve fill capability. We have a proven, effective, and relatively inexpensive methods for making large improvements with our fill designs.
The other category usually means that the fan horsepower must be raised or another cell must be added. We find this us usually not cost effective, and saddles the user with higher on-going O&M costs; raising the fan horsepower to expose the water to more air usually means replacing all the mechanical equipment (the fans, gears, drive shaft couplings, and of course motors) to handle the higher horsepower. In addition, the air flow only varies as the cube root of the change in horsepower. For example, changing the fan motor horsepower from 150 HP to 200 HP is a 33% increase in horsepower and energy usage, but the increase in air flow will only be the cube root of that 33%, or 10%. Adding a cell to a large industrial tower can easily be $1 million when the cost of the cell, the basin extension, the new wiring and controls, and the new piping are factored in. The percent improvement will be the number of cells including the add cell divided by the number of original cells.
We do not recommend mixing crossflow and counterflow cells because hydraulic imbalance results in lower than anticipated cooling performance.
I recently replaced my splash fill for another splash fill. Can you still upgrade the tower?
Yes, we work with all types of splash fill. There is usually not a great difference between the performance of one splash fill versus another and our upgraded performance gains do not change much even though the splash fill may change
What size tower is a good candidate?
Most industrial sized towers are good candidates. They will usually be field erected, and at least 25 feet from the basin curb to the fan deck. Package towers that are built in the factory or rooftop towers that support a chiller facility are not usually large enough for our designs. 10,000 GPM is also a good minimum size.
What operational changes do I have to make?
If you are operating your towers well with good water quality control, then little needs to be done. For most towers a biocide program is already part of their water quality control program, and this is normally adequate assuming it is maintained
What does an increase in capacity mean?
As defined by Cooling Technology Institute (CTI), cooling tower capacity refers to a tower’s ability to cool a certain amount of water at design water and air temperatures. The higher the capacity, the greater the amount of water that can be cooled and still meet design temperatures. For example, if a plant has towers and one has a 10% higher capability then it will have the same temperatures as the other tower while cooling 10% more water than the other tower. A similar CTI procedure is used when determining the capacity increase (upgrade) needed to attain colder water at no change in water rate. In other words, what would a tower’s theoretical increase in size have to be in order to realize the same cold water temperature attained by an upgrade? For example, if an upgrade of ours achieved a 33% increase in capability for a 6 cell tower, then that tower would be operating as if it had 8 cells instead of 6
How does your design minimize ice formation?
Ice usually forms out near the louvers of crossflow towers where splashing and cold ambient air mix. We flood this area with heavier than normal water flow to take advantage of the film fill we place out in that area. The heavy water flow is retained in the fill packs which eliminates most splashing even in windy conditions. This heavy flow which is trapped in the film fill has been an effective measure for reducing ice formation in the upper and lower portions of the tower
I have an older counterflow tower with film fill already installed. Can I upgrade it?
Yes, but it depends on your tower’s current operating condition.
What about repairing a tower?
Repairs can be made while the tower is being upgraded. These include replacing framing members, repairing the distribution system, patching holes in the siding and fan deck, etc. We can also work on the mechanical equipment. Repairs are fairly simple and do not take a lot of skill, so it is not a market we aggressively try to enter. However, any repairs included as part of our upgrade are very competitively priced.
What can you provide to make a tower operate quietly?
A variation on one of our designs lets us cover the entire air inlet area with film fill which practically eliminates any water splashing near the louvers. Besides eliminating splashing near the louvers, the film fill acts as a sound barrier to any splashing taking place inside the tower which further decreases a major source of sound from a tower. Many new towers today have a large inlet area where the water rains down into the basin from heights of up to 18 feet. This is the main source of noise on ground level.
Who installs the upgrade?
Phelps Engineering Company provides the labor which mostly comes from local sources. Phelps provides its own supervision to ensure the installation proceeds properly and on schedule. We prefer to work with our own labor suppliers since we trust their work and they are familiar with our designs.
What do you do to minimize debris from reaching the pumps while working on the tower?
When working on crossflow towers we can temporarily install a finer pump screen mesh if the existing mesh is too large or is broken. We also normally remove any floating debris as part of the daily clean-up. Any cutting of lumber or film fill is done outside of the tower. Chainsaws are not normally used to cut the film fill since it is normally cut with knives which reduces the smaller pieces of PVC from reaching your pumps. A temporary cold water basin cover can be installed at an additional cost, if desired.
How do you work on the tower if my valves leak?
Not many flow control valves are capable of shutting off without dripping a little. This amount of water can be directed to where the crew is not working. It is possible to block the valve outlet while work is taking place. If needed, non-functioning valves can be replaced while the tower is running.
Does the tower have to be out of service for an upgrade?
No, normally Phelps works on the tower while it is in operation. We do this by working on the tower one cell at a time while the remainder of the tower stays in operation. Crossflow towers permit the upgrade of ½ cell at a time, if needed. We can work during a turnaround or outage, but it is not normally necessary.
What do you do about fall prevention?
Phelps Engineering has worked in plants having very stringent safety policies. Fall protection is always a priority and we have developed special procedures for meeting the most difficult of requirements. The inside of a cooling tower resembles a scaffold and offers many suitable tie-off points.
If desired, who independently tests the tower?
There are several test agencies who conduct these tests. The tests are conducted according to the Cooling Technology Institute test code, ATC-105. We will provide you with their contact information if needed.
How does the guarantee work?
The guarantee is based on the tower’s performance. A penalty is assessed based on the percentage performance shortfall, should it occur. Our designs have always met or exceeded their design goal.