Flushing, rinsing and cooling offer myriad options for saving water

Water is the most important raw material for the beverage industry. In many places, however, water resources are under pressure from global warming and pollution. And so, beverage makers are seeking ways to use this “blue gold” more efficiently. This article explains how they can reduce their water needs and why thermal energy plays a significant role.

Quite a lot – or should we say quite a little – is possible when it comes to water consumption in beverage production, reports Norbert Ottmann of Krones’ sustainability consulting service: “Our most ambitious customers in the CSD arena are setting consumption targets of 1.3 or even 1.1 liters of water per liter of beverage produced.” And that number includes the liter or so of water that goes into the drink itself. That means the remaining water budget for the line is calculated with very narrow margins.

At present, the average water consumption in most beverage plants is still above these “best in class” targets. While it’s true that water supply has been a major consideration in some regions since time immemorial, most companies have until recently focused primarily on energy consumption. But that is changing now. For example, in its latest benchmarking study, the Beverage Industry Environmental Roundtable, a coalition of 17 global beverage companies, reports that its members have been increasingly turning their attention to efficient and sustainable water use.

Where can we make adjustments?

The question arises, then: How can we reduce water consumption in beverage production? This article looks at potential for savings in filling and in process technology. Solutions for water treatment can be found in a separate article, here. And sustainability concepts for water use in the brewery specifically are discussed here.

An especially high volume of fresh water goes into the processes of flushing, rinsing and cooling. As a result, these areas offer potential for savings at several points: Beverage makers may be able to flush or rinse less, reuse the rinse/flush water, recover heating and cooling energy and use it elsewhere, or recycle process water in a cooling cycle instead of simply running it down the drain. Each company will have to weigh these options individually to determine which ones are feasible and make economic sense in their operations. And Krones’ sustainability experts can help with that decision-making. Applying their knowledge of the machines and how they work together, Krones’ sustainability specialists analyze water flows along the line or in the entire factory to identify possible places where savings can be achieved. They work with the customer to then develop specific solutions to permanently reduce consumption.

Water savings can be accomplished right out of the gate, in the production planning stage – because the longer each individual production cycle runs, the less frequently pipes need to be cleaned for a product change. The flushing procedures themselves are another excellent point for fine tuning. In essence, the objective here is to prevent any carry-over of aromas or allergens from one product to the next. “There is always room for improvement when it comes to flushing the system,” says Katja Enzmann, who is responsible for thermal processes and sustainability in process technology at Krones. “We draw on our knowledge and experience to deliver actionable advice,” she says, emphasizing that “Ultimately, the customer will determine how much flushing water is necessary to accomplish the level of assurance they need to prevent allergen or flavor migration.”

Saving water at the machine level

Bottle washer:

In returnable lines, the bottle washer offers considerable potential for water savings. There, PET or glass bottles run through a hot caustic solution and are then rinsed and cooled with fresh water at the discharge. For every half-liter beer bottle, this process typically uses one-fifth of a liter of water, of which just less than half is for rinsing away the caustic. There are, basically, two factors influencing water consumption: The cleaner the caustic can be kept, by using microfilters for example, the less water will be needed for rinsing.

Likewise, water consumption will drop if the bottles don’t need to be cooled as much. Thus, one potential measure would be to opt for warm filling, which would allow for a higher discharge temperature from the bottle washer. The temperature of the caustic is another parameter that can be adjusted for water savings, as bottle washer specialist Alexander Weyers explains: “Depending on the product and line in question, some customers are able to lower the temperature of the caustic a bit and thus save on cooling water. At Krones, we are also working on cleaning processes that are specially adapted to lower caustic temperatures.”

*The cleaning process offers several possibilities for saving water.*

Another option is to extract heat from the caustic – and thus from the bottles – before they reach the discharge. With the help of a heat pump, that thermal energy can then be put to use elsewhere in the line. In the world’s warmer regions, it makes sense to lower the temperature of the fresh water so that the same cooling effect can be achieved with less water overall. “Sometimes, a company will have excess cooling energy elsewhere in the line, which we refer to as ‘cold for free’. It can be used for this purpose. Alternatively, we can look at whether it’s worthwhile to invest in a cooling tower or – if the ambient temperature is very high – in a water chiller, although that will, in turn, push up energy consumption,” explains sustainability consultant Norbert Ottmann. “The most important thing you have to be clear about is that everything is interconnected,” stresses Alexander Weyers: “The main point of caustic filtration is to extend the service life of the caustic. In some cases, it also results in reduced fresh water consumption. For instance, if it takes less water to cool the bottles than it takes to get them clean. In that case, it makes sense to think about using a filter, to further reduce the amount of water needed to achieve the necessary level of clean.”

Pasteurizer:

In the pasteurizer, thermal energy is the main source of potential for water savings. There are essentially two situations in which cooling from outside the system is necessary. If there is a stoppage, any containers in the pasteurization zone would be exposed to the heat for too long. For that reason, the hot zones will be cooled, usually with water and less frequently with a coolant. Instead of being discharged to the drains, the resulting warm water can be collected, cooled and reused. The second scenario in which external cooling is necessary is when the line is being emptied. Normally, the heat coming off the containers that are leaving the pasteurizer is used to pre-warm the cold containers entering. However, if there are no cold containers entering the machine, this option isn’t available and the warm bottles must be cooled. Here, too, we can save water by running the warm process water through a chiller for reuse in a closed loop instead of simply discharging it down the drain.

Process technology:

Cooling the vacuum pumps is another way to save water. An example of this can be found in CSD production, on the Contiflow mixer. Here, deaerated water is blended with the ingredients for a desired beverage recipe and then carbonated. Fresh water cools the continuously operating vacuum pumps. Instead of being discharged down the drain, the resulting warm process water can be circulated in a closed loop to an external cooling medium and back again for reuse. This solution becomes even more elegant if, instead of a separate coolant, the deaerated cold product water is used as the cooling agent in the heat exchanger. That would reduce water consumption from roughly 270 liters per hour to around ten liters per hour. In thermal product treatment – more specifically, in warm deaeration – the vacuum pumps must likewise be cooled. And the same approach can be used to save water.

Which measures can be retrofitted?

Heat pumps for recovery at the pasteurizer and bottle washer
VapoChill cooling tower
Fresh water pressure regulator for the bottle washer
Summer/winter switch for the bottle washer (spray volume linked to the temperature of the fresh water)
Circulation of the cooling water for the vacuum pump in the Contiflow and on the warm deaeration unit during thermal product treatment
EquiTherm Coldfill for cold filling beverage cans

Exchanging heat and cooling energy throughout the line

Looking at the entire line reveals even more potential for water savings, explains Norbert Ottmann: “In theory, you can optimize each part of the line individually. But when you bring together several different stand-alone modules, they complement each other. The resulting synergies make the whole far greater than the sum of its parts.” Usually, that means capturing heat or cooling energy at one point and using it somewhere else in the line. This, in turn, can also yield water savings, as described above. These concepts are typically tailormade and developed in consultation with the customer.

Examples of synergies that save water

Warmer filling in the brewery: Thermal energy from the bottle washer is used to pre-warm the beer. Less water is needed to cool the bottles at the bottle washer discharge. In addition, warmer filling temperatures mean less condensation forms on the filled containers.
A brewery project in a very warm region uses the cold beer as a cooling medium. The result is a series of synergies that save water, for example in the bottle washer.
Cold filling CSDs: Because condensation forms on the filled bottles (which are a cold eight to ten degrees Celsius), the bottles must be warmed prior to labeling. Krones’ EquiTherm Coldfill can help with this. A heat pump captures the cooling energy from the mixer and brings it up to a higher temperature for use in the bottle warmer. Besides yielding considerable energy savings, this also decreases water consumption on the chiller by up to 60 percent.
In a canning line, the rinser is one of the biggest water consumers. However, because the process does not significantly impact the quality of the rinse water, this water lends itself extremely well to reuse, for instance as process water for the pasteurizer, in the can spraying system or for the conveyor lubrication system. Up to 90 percent of the rinse water can be treated and reused, thereby reducing the line’s fresh water consumption by up to 50 percent.
In some cases, the pasteurizer needs to have an additional cooling zone at the discharge in order to bring the containers down to the required temperature. Instead of dispersing the released heat into the environment by way of an evaporative cooling tower, a heat pump can be used to send it back into the pasteurizer. That reduces consumption of both primary energy and water on the machine. Whether such a solution makes sense will depend on the relationship between the infeed and discharge temperatures of the containers.