Hygienic tank cleaning technology does its job where no eye can see it. However, it is of crucial importance to ensure the hygienic safety, sustainability and shelf life of food, beverages and pharmaceutical products, among many others. We put the spotlight on how this constantly evolving system component helps to achieve ever-increasing benefits for manufacturers, plant workers, consumers and the environment.

Some look like spaceships. Some like surrealistic tools or shiny toys of strange elegance and symmetry. Industrial tank cleaners surely rank among the most aesthetically pleasing components in processing systems ... or would if one could actually see them. Their real worth lies in what they do, and they do it in darkness, in hermetically sealed processing and storage tanks, containers, and fermentation vessels.

Long time ago, at the dawn of the food processing age, it was actually unclean containers and vessels that casually sparked yeast fermentation and gave us staple delights such as beer, wine, and sourdough bread. Ever since, however, it has been of premier concern to successful manufacturers to keep tanks and containers as clean as possible in order to ensure reliable product quality. In the case of products for human consumption, this means: hygienically or even aseptically clean.

Safety matters – and brand reputation

Safety matters – and brand reputation

Whether dairy products, wine or beer, toothpaste, pharmaceuticals or baking flour – safe and reproducible product quality is a key objective in the interest of manufacturers and consumers. Wherever products are processed or stored in tanks, silos or, for example, intermediate containers (IBC), residues that are not adequately cleaned can affect their safety and quality in many ways. This is why the cleanliness of tanks and other containers is strictly governed by regulations and guidelines from the FDA in the US, the EHEDG in Europe and other regulations around the world.

One major risk is the possibility of cross-contamination that can occur when one production batch follows another one with different product components. As consumers we are constantly asking for more variety to meet our different appetites and needs. This has led to a continuing explosion of products and product variants in today’s markets, which are often processed and stored in the same tanks. Residues from previous products can affect the taste or other properties of the next product or even render it poisonous. That might happen, for example, due to uncontrolled fermentation or chemical reactions, growth of bacteria or fungi or the transfer of allergens from one product to another.

If the product remains the same, there is still the risk that uncleaned residues will decompose or ferment, affecting the next batch in the tank. The discernible effect can be small, but global consumers tend to be increasingly critical of even the smallest deviations. Considering less precious goods like cellulose or paper sludge or even sewage, their tanks need to be cleaned as well to prevent product build-up, clogging, corrosion or hazardous foul gases.

All the risks of inadequate cleaning are multiplied in today's market environments due to the many repercussions that even a single faulty product batch can entail. The manufacturer can lose substantial quantities of corrupted product and can face significant costs to recall and recover faulty product. More importantly, the health of workers and consumers could be affected. Finally, the product and brand reputation will almost invariably suffer from any such incident, however small. Cleaning technology has therefore become an ever more important asset in the process planner’s toolbox.

Automated cleaning for healthier work conditions

For centuries, people had a good idea of the risks from unclean vessels, but all cleaning had to be done by hand in hazardous circumstances. In the past, service workers had to enter tanks and silos through the narrow manhole to clean the tank manually from the inside, sometimes assisted by a coworker to oversee the safety of both men. They had to handle add harsh cleaning fluids and potentially dangerous tank residues in a confined and obstructive space. It is clear why work health regulations of the US Occupational Safety and Health Administration and similar institutions elsewhere call for extreme caution.

Manual cleaning was made easier with the development of hand-controlled spray guns – still about the most effective way to clean the outside of tanks as well as stone walls, sidewalks or, for instance, decks of fishing vessels. But it was the development of automated cleaners, starting in the 1920s, that has brought efficiency and healthier working conditions to the task of cleaning the tank interior. Automated control of cleaning operations has also made it possible to dose the detergent fluid in exactly the amount required for the task – just as a modern household dishwasher uses resources better than rinsing by hand.

Tanks that can be automatically cleaned are usually made of stainless steel, and the cleaning system is mounted as centrally as possible to the tank wall or ceiling. Cleaning chemicals are mostly alkaline and acidic compounds, which can be re-used in cyclic CIP systems. Cleaning times and cleaning intervals can vary greatly, depending on the plant setup, the product and batch processing schedules, often recurring several times a day. Given that many operations have multi-tank storage farms, some tanks being over 20 meters high with an internal surface area of more than 100 square meters, we can truly call automated tank cleaners the “hidden champions” of industrial production.

Improving sustainability and operating costs

At the GEA Cleaning Technology Competence Center in Buechen, Germany, experts are constantly expanding the variety of cleaner types used in industry today for different products, soiling classes and application environments. All tank cleaners must maintain safety and quality, but they also need to become more and more efficient and sustainable in operation – otherwise powerful cleaning technology would no longer pay off despite its worth for the product and process. The question that engineers keep coming back to is: Which factors influencing cleaning performance can be further improved to increase sustainability, save resources and reduce costs?

The so-called dynamic Sinner's circle shows how five main factors of efficient cleaning – mechanical efficiency, temperature, cleaning agents, water consumption and cleaning time – work together. Enlarging any one section in the circle makes the others smaller, indicating potential savings. “In practice, our engineers focus on one factor, on improving the mechanical efficiency of cleaning solutions,” explains Jana Zimpel, Product Sales Manager at GEA’s Competence Center in Buechen. “Every advance made there enables plant operators to save valuable time for processing and to reduce the consumption of energy, water and chemicals according to their economic and ecological priorities.”

Every advance made there enables plant operators to save valuable time for processing and to reduce the consumption of energy, water and chemicals according to their economic and ecological priorities.”- Jana Zimpel, Product Sales Manager, GEA Cleaning Technology

Sinner's circle

The areas of mechanical improvement are highly diverse. “Through innovative design, modern cleaners are able to harness shear forces and other assisting cleaning effects to increase cleaning efficiency,” Senior Product Sales Manager Chris Lawton at GEA points out. “Liquid flows, nozzle sizes, rotation speeds and spray matrix, when combined with cleaning times, are all key factors we can optimize for a given product process or tank size.”

Liquid flows, nozzle sizes, rotation speeds and spray matrix, when combined with cleaning times, are all key factors we can optimize for a given product process or tank size.”- Chris Lawton, Senior Product Sales Manager, GEA Cleaning Technology

A related goal in the interests of plant operators is to extend the service life of tank cleaners. For this purpose, GEA uses hydrodynamic bearings instead of ball bearings, as the latter are subject to much greater wear and tear and can also contaminate the product through abrasion. In addition, GEA consultants offer advice to their customers on establishing preventive maintenance programs, which make sure that seals and other wear parts are replaced in time before problems can occur.

A breakthrough modular concept

Among the many types of tank cleaners, orbital cleaners are a kind of benchmark for powerful technology and have been further developed by GEA several times. Properly configured for the task, orbital cleaners can handle the toughest jobs, such as dried and sticky residue and even yeast, glue, resin or fermentation products, etc. Equipped with meticulously selected nozzles and nozzle carriers, the cleaner rotates in a 3D matrix around a vertical and a horizontal axis and thus reaches every single surface point in the tank in a highly controlled, highly powerful manner.

Current developments by GEA include the successful initiative to combine all the key equipment options for orbital cleaners in a single, modular model. This modular concept has been realized for the first time in GEA’s orbital cleaner OC200. All key components on this orbital cleaner can be quickly interchanged. Three different nozzle carriers meet every requirement regarding insertion openings, flow and soiling levels. Eight nozzle diameters can be selected to optimize flow, cycle time and spray projection. Having all these options at hand, achieving longer dwell times for higher cleaning intensity is no problem.

Longer sprays can be produced for very tall or very wide tanks, such as flour silos or brewing tanks in big operations. Tall tanks can also be cleaned from the bottom up, inverting the usual mode of operation. Self-cleaning nozzles, pointed backwards, prevent product build-up on the cleaner.

This innovation offers a new level of flexibility to process operators, making it easier for them to plan and devise exactly the right equipment option for their specific task and to adapt their cleaner to new and different process requirements at any later point in time. Thanks to the optimized mechanical impact, cleaning times and fluid consumption can be optimized even further, saving valuable resources.

Personal expert support – an underrated factor

It is characteristic of the concealed nature of tank cleaning that system planners, implementers and operators understand other areas of processing technology much better than tank cleaners. They are – and should be – mostly focused on improving their product, the processing stages directly related to this, and their expected revenue. As a result, configuring ideal tank cleaning equipment is very much a matter of partnership between companies, and between persons.

At GEA, Jana Zimpel confirms that a vital part of her team’s work is providing the customer with process knowledge. “Understanding the individual needs and requirements is very important for us”, she explains. “In good collaboration we are able to support the customer as a specialist with the optimum component while they are more focusing on the whole process. We share our knowhow, we train staff and support the operators on site so that our customers achieve safe, sustainable and cost-efficient cleaning processes.”

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