I know the water crisis appears to have abated somewhat in the Western Cape, but the price of municipal water, vastly increased to curb consumption, isn’t likely to drop anytime soon. To those cold store operators in the more water blessed areas of Southern Africa, the chances of a personal drought experience should not be underestimated. One thing is undeniable, most cold stores cannot do without substantial quantities of high quality water to cool the hot gas in their condensers.
Kevin Schlemmer of Cool Check made contact with me to comment on a previous article dealing with cold store water usage. He made the point that it can be reduced (in many cases quite simply) and is also a good indicator of refrigeration plant efficiency. His article is attached below. Readers are encouraged to make contact with Kevin directly for more information and assistance.
Is your cooling tower pouring water down the drain?
Top Five Practical Tips to Reduce Cooling Tower Water Losses:
by Kevin Schlemmer (MD), CoolCheck (Pty) Ltd, July, 2018
Did you know: Up to 80% of the water consumption at a typical logistics Cold Store operation is for the cooling towers? A medium size ammonia plant can easily consume 500,000 litres of water per month!
Myth: “My cooling towers’ water consumption cannot be reduced because that will negatively affect my refrigeration”
Fact: The water consumption is proportional to the efficiency of the refrigeration system. For example, improving the cooling system by 20% will reduce water consumption by 20%.
Fact: Over and above efficiency, there are many other areas where water losses are found on cooling towers. For example:
- Up to 40% of the water used by the tower will be dumped (bleed-off) by a typical water chemical treatment system. This bleed-off percentage is very often a function of hit-and-miss settings by the operator and needs to be checked regularly.
- Leaks in pipes and float regulators can be responsible for as much as 20% of the losses.
- Water sprayers, which are not functioning correctly, can over-spray and this water runs down the outside of the tower.
When it comes to water saving, one of the most underestimated areas is water-cooled refrigeration systems. The cooling towers connected to the chillers consume vast amounts of water. It is a common misconception that cooling towers “recycle” the water – the fact is the water is consumed!
The good news is that there are a number of things that can be done to reduce (optimise) this consumption. For the sake of this article, I will focus on things that can be done by the owner/operator of the refrigeration system. This does not replace the work done by the cooling service contractor, but rather complement it.
Top Tips:
- Refrigeration efficiency directly affects the water consumption. Improving system efficiency is equivalent to reducing water consumption. Make sure the chiller and cooling tower is regularly serviced and in good condition.
- Inspect the tower regularly (weekly). We see many operators that accept as “normal” that there is always a wet puddle or some standing water around the tower – this is not correct. Leaks must be identified and repaired. Here are some common culprits:
- Inlet screens at the bottom of tower: damaged, dirty, or not fitted properly will cause water to leak down the outside.
- The tower is over-filling. Check that the ball-float valve is adjusted correctly and not too close to the over-flow pipe.
- Leaking water pump seals and valves.
- Water droplets discharged out the top of the tower fan (referred to as drift). Directly under the fan is a drift eliminator, which is supposed to catch any water droplets and prevent the fan from blowing them in the air. Get your contractor to inspect the drift eliminator and the spray nozzles.
- Measure, measure, Measure! The single most powerful tool available to the owner/operator is to keep a logbook of the water consumption. Ideally, this should be recorded on a weekly basis. Creating a bar graph of the weekly consumption is useful to track trends.
CoolCheck has developed a useful logbook template for owner/operators. For a free copy, send an email to info@coolcheck.co.za with “Cooling Tower Logbook” in the subject line. For a free chiller water audit, please send an email with “Cooling Tower Water Audit” in the subject line to info@coolcheck.co.za.
Kevin Schlemmer – CoolCheck (Pty) Ltd
Tel: +27 21 591 1107
