Cutting the cost of tower pack-fill

A common problem with cooling tower internal packing over time is that they develop scale which decreases the tower’s effectiveness.

Cooling tower internal packing needs to be inspected and cleaned regularly. Traditionally, the packing has to be removed, but this is costly. Here, we discuss how Biochemica Water has developed an alternative strategy to clean packs without removing them.

Due to Health and Safety regulations, cooling tower internal packing needs to be inspected on a regular basis and, depending on the level of fouling, cleaned to prevent scale and the potential growth of legionella bacteria. Traditionally cooling tower packing has been removed to be cleaned but this process is becoming increasingly costly.

A common problem with cooling tower internal packing over time is that they develop deposits such as iron and calcium (often referred to as scale). These deposits lead to decreased heat transfer efficiency within towers, which decreases the effectiveness of the tower in the process, and increased biofilm formation (this is linked to legionella growth).

Because of the risks involved with scale development on cooling tower internal packing, the Health & Safety Executive (HSE) recommends that cooling tower internal packing is removed at least annually and preferably every six months. The logistics of this can prove costly, which is why people are looking at alternative strategies to clean their cooling tower internal packing.

Foam cleaning

Because of the high costs involved in cleaning cooling tower internal packing, Biochemica Water spent a lot of time developing alternative strategies in order to offer cost effective solutions to their customers. The solution was a foam cleaning technology specifically for cooling tower internal packing. The Biochemica Water cooling tower foaming range is designed to clean the internal packing, without having to remove it, by dissolving the scale deposits and disinfecting the cooling tower surfaces. This alternative strategy will extend the packing life.

The Biochemica Water cooling tower foaming technology works in a rather simple way, cutting out any need to physically remove the internal packing. The treatment foam is generated and applied through a foam generator fitted with a foam lance and course foam nozzle that will travel into the packing.

The foam generator and lance are specially chosen by Biochemica Water as they are adapted to produce wet, clingy foam in conjunction with the Biochemica Water range of pack cleaning chemicals. This type of foam is produced so that it will travel down the packing and react with scale deposit as it drains through to the sump.

The rate in which the chemicals travel through the packing are dependant on the stage of cleaning and it can be controlled by adjusting the wet or dry nature of the foam and by the addition of higher concentrations of surfactant and rheology modifier. For example, if a post clean disinfection is taking place a dry, dense foam is most suitable as it allows slow travel through the packing which allows greater contact time for the disinfection chemicals on the cleaned packing surfaces.

The Biochemica Water foam cleaning technology is applied using a seven-step method as shown below:

  1. Pre-clean and disinfection
  2. Pre and post endoscopic analysis and pictorial evidence must be recorded
  3. Foam the packing
  4. Rinse the packing thoroughly with de-foaming and neutralising chemicals.
  5. Inspect the packing to verify the process has been effective.
  6. Debris removal – this is only possible when a tower sump can be physically drained to allow removal of debris from the tower sump.
  7. Post clean disinfection.

Cleaner benefits

So why use Biochemica Water cooling tower foam cleaning technologies?

Well, obviously, because it is a more cost-effective strategy to cleaning cooling tower internal packing, avoiding any costs associated with physically removing the packing and associated health and safety risks with removing the plastic packing. Because Biochemica Water foam cleaning technologies can be used to clean internal packing in situ, the costs are reduced due to the reduction in man-hours needed to remove the packing. Along with this is the fact that foam cleaning technologies reduces the cooling tower down time in a shut down.

Now, the reduction in cost is all well and good but does this effect the quality of the clean? Not at all. The Biochemica Water cooling tower foam cleaning technologies are proven to significantly improve cooling tower efficiency. This is done by the effective removal and reduction of scale and biofilm. An improvement in water distribution within the cooling tower is also noticeable after the effective use of Biochemica Water cooling tower foam cleaning technology.

From an environmental point of view, using Biochemica Water cooling tower foam cleaning technologies is much more environmentally friendly than the traditional method of cleaning. When removing cooling tower internal packing for cleaning, it is common to damage some of the packing. How is that bad for the environment? Internal packing is made from plastic, so when it is damaged it is sent to landfill. The same can be said for heavily soiled packing which is also sent to landfill. Biochemica Water cooling tower foam cleaning technologies significantly reduces the risk of damage to the internal packing and is also effective at cleaning heavily soiled packing meaning a reduction in plastic packing being sent to landfill.

Conclusion

To summarise, it is important now more than ever for companies to reduce costs in an uncertain economy, especially in the UK after Brexit. Site managers are having to be intelligent about how they can reduce costs without effecting any processes significantly. Removing cooling tower internal packing for cleaning may seem like an area where money can’t be saved but, in fact, it is becoming increasingly costly to do so. More companies need to find alternative solutions such as the Biochemica Water cooling tower foam pack cleaning technologies which will reduce time spent in shut down, reduce waste to landfill and in effect reduce costs.

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Filtration & Separation, p54-55 November/December 2018