Yeast fermentation leaves tank residues that are not optimally easy to clean – the residues can be sticky and not be fully water soluble. This makes it difficult for breweries to clean fermentation tanks and ensure the necessary protection and purity of the product. High water consumption can be a major problem for them. One leading German brewery recently turned to GEA for help. In a recent upgrade project to equip the fermentation tanks with optimally adequate cleaners, GEA was able to achieve substantial water savings.
For many years, the brewery had used spray balls to clean the interior of its fermentation tanks. These static cleaners are a common solution for many kinds of tanks, but one with significant disadvantages when the task is more difficult: The sprays of static cleaners are not concentrated and generate little mechanical pressure on the soiled surface. Moreover, the sprays do not directly impact every spot – some areas of the tank interior are only cleaned by rundown water. More water and more time must be spent to achieve safe cleaning results.
Consequently, in that particular brewery a standard 10-minute cleaning cycle with spray balls would end up consuming more than 52,000 L water. This substantially affected the company’s freshwater intake as well as its wastewater bill. In addition, the brewery needed to apply more heat and greater amounts of cleaning agents then necessary to clean the tanks.
Making beer – a sticky business that makes tank cleaning difficult.
Approaching the most efficient cleaning configuration
To support the brewers’ quest for a more sustainable cleaning solution, the GEA team tested several orbital cleaners. This cleaner type is designed for higher soling grades with sticky residues in process tanks and storage containers. Orbital cleaners with multiple nozzles in controlled motion produce a sophisticated, high-impact 3D matrix that covers the entire surfaces of the tank interior.
After comparisons between several orbital cleaner variants, the GEA team installed two OC200 orbital cleaners in the brewery’s fermentation tanks, each with three 14-mm nozzles operating at 7 bar. This resulted in high-impact cleaning during a shortened 7-minute cycle with a greatly reduced water intake of just 11,200 L.
But there remained one further avenue of improvement to explore: Switching to the 12-mm nozzles meant once more increasing the mechanical impact produced by the system, which succeeded in reducing the flow rate to an optimum 9,100 L – less than a fifth of the original water intake.
Dynamic Sinner’s Circle
Further effects of improved mechanical impact
When configuring the most effective cleaning solutions, GEA engineers illustrate the interdependence of cleaning factors with the “Dynamic Sinner’s Circle”. The sizes of the different areas in the circle, representing mechanical impact vs. temperature, amount of chemical cleaning agents and necessary cleaning time, will ¬vary in percentage from application to application, depending on how best to achieve the targeted cleaning result.
The typical effects of increased mechanical impact to the plant operator’s advantage were demonstrated by GEA’s recent upgrade project at the German brewery: Using the high-impact configuration of two OC200 orbital cleaners with three 12-mm nozzles, the customer company was able to minimize the use of heat and chemicals as much as the water intake, as now all areas of the tank benefit from the mechanical effect of direct impact and do not rely on water rundown.
The right cleaner for the right task
Soiling classification systems determine the mechanical cleaning power required for effective cleaning. We have defined four soiling classes to describe the degree of mechanical force that should be used and the recommended type of cleaners.
Soiling Class I – Rinse cleaning
Easy cleaning conditions Water-soluble products with little or no tank adhesion Recommended: Static Cleaners
Soiling Class II – Low impact cleaning
Moderate cleaning conditions Water-soluble pro ducts with low adhesion Recommended: Free Rotating Cleaners
Soiling Class III – Medium impact cleaning
Difficult cleaning conditions Stubborn residues with medium tank adhesion Recommended: Slow Rotating Cleaners
Soiling Class IV – High impact cleaning
Highly difficult cleaning conditions Encrusted or dry products with high adhesion Recommended: Orbital Cleaners and Index Cleaners