Pasteurisation reinvented

To put it simply, a classic canning line looks like this: Its individual machines – filler, pasteuriser, packer, etc. – are interconnected by means of wide bulk conveyors, on which the cans jostle several lanes deep. Bulk conveyors form the basis for operating the entire line. Most of the time, the containers are spaced out as they travel along the conveyor belt, and at one point or another buffering sections are integrated. In this way, the conveyor serves to ensure an even container distribution if there is a stoppage in the line. Each machine possesses its own control system. Back-up switches at the conveyor emit a signal that informs this control system if the belt leading to the next machine is filling up and the machine must be stopped.

The underlying principle works all right but there is one snag: The requisite equipment has a huge footprint because the wide, rather slow-running bulk conveyors and the buffer sections alone need a lot of space. What is more, the conveyors leading to the single- or double-deck pasteuriser are relatively long which increases the risk of containers falling over. 

The line layout with the new LinaFlex eSync presents an entirely different picture: The cans race along a narrow, single-lane conveyor in a close-packed flow on a comparatively short bend from the filler to the pasteuriser and from there to the packer. The conveyor does not include a single buffer section. On the contrary: The belts are always completely filled, and the number of cans between the individual machines is kept constant. 

Pasteuriser acts as buffer for the entire line 

Instead, the buffer for the wet end is hidden inside the tunnel pasteuriser, whose design has been completely reinvented. On each of the decks, a newly developed infeed system ingeniously distributes the cans darting into the machine in single file onto the wide, very-slow-running pasteuriser belt. At the machine’s end, a discharge system guides the cans back onto fast-running single-lane conveyors. The clever bit of this system is located directly upstream: Still inside the LinaFlex eSync machine, a separate variable-speed conveyor that is directly connected to the pasteuriser belt and running faster than the pasteuriser itself creates a free space that can be filled if needed. That provides two buffer sections located one above the other in the double-deck pasteuriser (and one in the single-deck machine) in a minimum of space. 

The ratio of the two belts’ speeds determines the extent to which the buffer is filled, says Niels Clausen, one of the product managers, who has been involved in the development work for the LinaFlex eSync from the very beginning. He goes on to explain: “Normally, we run the buffer belt about ten times faster than the pasteuriser’s conveyor. That makes for about ten per cent of buffer occupancy when operating at its rated capacity. If that speed is reduced, the buffer gets filled up.” 

To put it another way: Thanks to this dynamic line buffer, the speed of the buffer unit inside the pasteuriser can be matched to that of the other machines – no matter where there is a hiccup in the line. “If the filler’s output decreases, the pasteuriser and its buffer dynamically respond to the altered conditions and stabilise the system at the new output level. Here, the integrated speed control makes for energy-efficient adjustment of the line’s speed,” says Clausen. “Conversely, the substantially larger buffer capacity provided in a minimised space enables line users to effectively cope with any malfunctions occurring downstream, at the packer, for example.” 

Single-lane transport lets the line breathe 

One of the key innovations is the use of single-lane container transport throughout the line – and the high speeds that permits. A completely new development is the divider for the double-deck pasteuriser. As its name implies, it splits up the fast, single-lane flow of containers arriving at the machine, passing them on to the feed unit of either the upper or the lower deck. The pasteuriser’s infeed and discharge are equally sophisticated designs that perfectly handle the transitions between the wide, slow-running belt inside and the high-speed single-lane conveyors outside the pasteuriser. All in all, the narrow belts take up much less room than bulk conveyors. It is considerably easier to access the individual components of the line, and the distance between filler and pasteuriser is significantly shorter. 

Yet another advantage provided by single-lane transport is the lower back-up pressure exerted on the cans’ sidewalls. On conventional bulk conveyors, cans may be subject to forces of up to roughly 16.5 kilograms while the force acting on the cans in single-lane transport is only about six kilograms. The risk of mechanical damage, such as dents or scratching on cans with low or no internal pressure, is thus substantially reduced. That in turn makes it possible to use lighter cans with thinner walls, which saves material and upgrades the package’s sustainability. 

Taking an entirely fresh approach to energy-efficiency: thermal and electrical optimisation 

“The overriding goal driving innovation in our development work for the LinaFlex eSync was definitely sustainability,” explains Niels Clausen. So numerous energy-saving functions that have already proved their worth in the past are available as optional extras. One of the key elements is heat recovery: By selectively circulating the water between the heat-up and cooling zones, a large amount of the energy used is recovered. The larger the surfaces available for heat recovery, the higher the efficiency. Mind you, larger surfaces mean more space is required. A possible alternative here is to optimise recovery by using several smaller zones, without increasing the machine’s length.

Moreover, the Recu-Switch function enables companies to use outer pasteurising sections as additional recovery zones at need. That is particularly effective when there is a great difference between the pasteurisation units (PUs) needed for the various products. 

Another highlight is dynamic speed control, which enables the machine to be run energy-efficiently even at partial load. Standard-installed insulation of the pasteurising sections for reducing heat losses serves as the perfect complement. Insulation of the recovery zones is available as an optional extra – the ideal choice for maximising energy savings. The low-pressure-optimised spraying nozzles require only small pumps with low power consumption. 

The water management system has likewise been designed for boosting efficiency: Small tank volumes not only reduce the energy required for heating and cooling the tanks but also the amount of water needed for cleaning them. 

A separate cooling module available as an optional extra makes it possible to cool products down to lower temperatures – roughly close to the dew point. Thanks to an integrated heat pump, the heat released in the process can be directly used for heating the pasteurising zones or fed into a plant-wide heating grid. This system achieves a COP (coefficient of performance) value of around 2.7 and an efficiency level of 85 per cent, thus constituting an especially sustainable solution. Customers can freely choose where to install the heat exchangers, whether right next to the pasteuriser, on a platform, in the basement or on the hall’s roof.

“When considering all these options, we also factored in the various amortisation times involved in each case,” says Clausen. He goes on to explain: “Since costs for water and primary and secondary energy are different in each region and each country, we’ve drawn up a flexible concept, so we can offer all customers around the globe the best possible solution.”

Reference project – LinaFlex eSync at DICO Drinks 

The pasteuriser’s prototype has been up and running at the can-filling company DICO Drinks in Hückelhoven, North Rhine-Westphalia, since July 2023. The line is rated at 95,000 containers per hour and was erected right next to its conventional counterpart running at the same speed. “The difference between the two lines’ footprint is striking,” says Sven Breitfeld, Head of Production at DICO Drinks. “It impressively illustrates the new system’s efficiency.” The dynamic buffer in the pasteuriser provides a buffering capacity of three minutes on just six square metres. 

The LinaFlex eSync was created jointly by specialists from every Krones Group division involved in this comprehensive development (partly research) project, all of them experts in their chosen fields: filling, pasteurising, packing and conveyor system technology, and simulation. Just like all these people joined their efforts to invent the best possible solution, their development is now paving the way towards joining all machines in the line for optimum interaction.