When it comes to water saving, one of the most underestimated areas is water-cooled chillers. 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 amount of water consumed by the tower is relative to the amount of heat, which it receives from the chiller or other cooling process. A small to medium sized chiller can easily consume 5000 litres per day at the cooling tower.
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 chiller system. This does not replace the work done by the cooling service contractor, but rather complement it.
- Chiller 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.
- Using an old kettle with white calcium layer as an example, the cooling tower is evaporating water 24/7 and the salts and calcium stay behind in the system. This is controlled by “dumping” a percentage of the water to evaporate. The process is referred to as bleed-off or blow-down. Make sure the bleed-off water is set correctly. DO NOT simply close off the bleed-off – this will result is very high maintenance bills and ultimately damage to the chiller. Water treatment is a very important aspect and using a reputable service provider is key.
- Monitor, monitor, monitor! The single most powerful tool available to the owner/operator is to track the performance of the chiller and tower. This can be done by anyone even with a limited amount of technical knowledge. From experience, the best strategy is to make someone in the team responsible for this important element. This person will build up a feeling for the operation of the chillers and usually they will pick up even the smallest changes. Keep a logbook, which is updated daily and inspected weekly by the wine maker or technical manager. Recording keeping is only useful if actions are taken on the information. The following data should be tracked on a daily basis:
- If not already installed, make sure that a water meter is installed for the cooling towers. Either a single meter for all the towers combined or a meter per tower. The logbook must show the daily consumption. A sudden and sustained increase (say 20%) could be caused by a leak.
- On the chiller directly: most chillers will have thermometers installed on the inlet and outlet sides (i.e. the chilled water inlet/outlet and the condenser water (cooling tower water) inlet and outlet. As far as is practical, try to take these readings between noon and 5pm every day. The cold water supply (the colder of the readings) is useful for the winemaker as an indicator of the chiller performance. The cooling tower water temperature should run between 32’C and 40’C on the supply line to the tower.
- Daily maximum ambient temperature (the thermometer must not be directly exposed to the sun).
CoolCheck has developed a useful logbook template for owner/operators. For a free copy, send an email to firstname.lastname@example.org with “Wineland Chiller Logbook” in the subject line.
For a free chiller water audit, please send an email with “Chiller Water Audit” in the subject line to email@example.com.