Why the ideal layout for a soft drinks mixing line is a circle

Producers usually split the intake lines for a mixer between wet and dry ingredients to keep them separate. This results in multiple lines and the need for a lot of handling equipment. A separate dry line may be needed for each bulk powder ingredient. The problem is that dry lines cannot be cleaned in the conventional way with water and chemicals using CIP (cleaning-in-place). And cleaning with compressed air is not sufficient to maintain food safety. Separate lines are often a requirement of food regulations to reduce the risk of contamination between different powders. So a producer may need to invest in a number of pneumatic or screw conveyors depending on the number of bulk powders to be mixed into a batch. Thus the cost of equipment to discharge powders into a batch mixer can easily escalate.

To complicate matters still further, powders may be subject to ATEX regulations due to the risk of explosion when discharging them.

Lines for liquid ingredients also become costly if discharging these liquids requires the purchase of additional pumps. Running costs also increase by more pumps using more energy and requiring more maintenance.

Intake from several dosing points in a loop

This is the typical scenario a soft drinks producer faces. However, there is an ingenious solution based on the revolutionary concept of a recirculation loop and our new Tetra Pak^® Mixer RJCI 4X. This new mixer has been specifically designed for the batch mixing of powder and liquid ingredients in the soft drinks industry. The Ingredient Loop Extension is an option with this new generation of radial jet mixer. Anywhere along the loop, a feeding-in point can be placed equipped with an injector, which is relatively small and less expensive than a pump. The injectors work by vacuum for the intake of both liquids and powders into the batch mixer via hydraulic conveying. The actual mixing takes place not just in the 3,000-litre tank of Tetra Pak Mixer RJCI 4X but in the hydraulic pipeline of the whole loop as the product recirculates again and again until it is ready mixed.

Now dry lines can be cleaned by CIP

One of the big advantages of the recirculation loop is for dry ingredients. No separate lines are needed. All ingredients, both wet and dry, feed directly into the recirculation loop. The complete loop can be cleaned at intervals with caustic soda using a conventional CIP unit. Therefore high hygienic standards can be maintained with no risk of cross-contamination from one powder ingredient to another. The cleaning problem associated with conventional conveying lines for powder ingredients can therefore be avoided.

Distribution of powder dust over a wide area of a plant with conventional solutions creates a bigger explosion protection area. In contrast, with the layout flexibility offered by the Ingredient Loop Extension, a dedicated ATEX room can be created in the plant to isolate the risk of explosion when discharging powders. In this way, all the open spaces of the plant may not need to be equipped to meet ATEX standards.

How the loop works

“Based on years of experience, we have perfected the technique for maintaining the pressure in the loop. We have created close to a complete vacuum,” explains Denis Steffen, Deputy Design Engineering Manager at Tetra Pak Processing Equipment AG in Switzerland where the Business Stream Soft Drinks (formerly Miteco) is based. “There is always sufficient suction at the injector no matter where it is placed in the loop. Each injector has an on/off function. By disabling an injector when it is not in use, energy can be saved and pressure can be maintained. All the energy can be used for efficient mixing.”

Tetra Pak has a long history of innovation in soft drinks processing and the patented injector is just one example. Our new Tetra Pak Mixer RJCI 4X also has a number of patented features.

The loop system has been installed successfully in the UK and US at major soft drinks manufacturers. This proven system known as Ingredient Loop Extension (ILE) saves producers purchasing, installing and maintaining a range of additional equipment such as pumps and conveyors. All that extra equipment becomes unnecessary when the ingredients are fed in directly to the loop via an injector. And in future, you can go on adding new ingredient feeding-in points to the loop as your needs change for discharging ingredients. With the challenge of dosing multiple ingredients, the best layout for soft drinks mixing in batch production is not linear, but circular. So stay in the loop!