Needing to install a substantial production and storage capacity for flake ice, a Danish processor went to KTI-Plersch Kältetechnik GmbH in Germany with the challenge of supplying a plant that would meet its particular needs, while also meeting demanding hygiene standards.
The size of the resulting storage unit, with 15×4.50 metre dimensions and a 4 metre height, presented challenges of its own, and the KTI team installed ice plants in containers next to the outside wall of the building, taking up none of the factory’s interior space.
“The ice plant was too large for the factory, so it had to be sited outside the building,” said Michael Walleter, director of Sales and Marketing at KTI-Plersch Kältetechnik GmbH.
“At the same time, we needed to carefully plan the 40-metre feed distance from ice production and storage to the four ice dosers, since the dosers can only take about 150kg of ice at a time, and every metre of distance reduces the flexibility of supply.”
A further challenge was the design of the machinery itself, since the ice has to be hygienically pristine at all times. That meant leaving as few hard-to-clean corners and gaps as possible. The ice plant produces 1.5 to 2mm thick ice flakes, which are liable to clump due to air humidity, and to partial melting and refreezing, so KTI also had to pay attention to keeping the humidity and temperature in the ice storage at a constant low level.
Once ice clumps, it is no longer properly dosable, losing the low volume and high surface area that are the major advantages of flake ice in providing high cooling efficiency.
“We solved the problem of lack of space inside the building by installing the machinery in standard shipping containers,” explained Michael Walleter. “This approach, made it possible to stack the ice maker, which can turn out 100 tonnes a day, and the associated 90-tonne storage unit with KTI’s proprietary ice rake system, on a steel structure next to the outer wall of the factory. The ice conveyors and distributors under the ceiling inside the building are thus easily accessible. As a result, no inside space is used, and the ice can be sent to the dosers quickly.”
He commented that for the remaining ice feed distance, the interaction with ice storage still had to be carefully controlled.
“For this we developed an intelligent control system that makes sure there is always enough ice, while preventing it from staying unused in the transportation system for too long. The choice of suitable screw conveyors, which are lubricated exclusively with food-safe grease, and the lack of a hopper ensures that the ice flakes will not clump or get contaminated on the way from storage to the fish shipping containers.”
To meet hygienic production and storage requirements, KTI chose stainless steel for almost all of the components coming into contact with the ice.
“The construction of a stainless steel tank inside the ice storage was a big challenge,” he explained.
“Since there is a moving rake to keep the ice evenly distributed, there couldn’t be any cross-struts. We still needed to provide for the stability and evenness of the walls. Many metal fabricators turned the job down, so we had to make the tank ourselves.”
Hygienic and energy efficient
The antibacterial properties of the stainless steel and its imperviousness to cleansers virtually preclude any contamination of the ice, while making cleaning easier. In constructing the system, ground welded seams were used to minimise dead spaces, while components that are difficult to clean, such as drives for the moving rakes, were enclosed in housings. Another feature minimising the risk of contamination is an automatic lubricant dispenser for the regular lubrication of moving parts with food-safe grease.
To optimise energy efficiency through the entire process, KTI also installed a pre-chiller that cools the supplied fresh water to 5°C, before it is made into ice reducing the freezing unit’s energy requirement and resulting in substantial savings.
“As a refrigerant for ice production we use ammonia (NH3), which is environmentally unproblematic and available in basically unlimited quantities. In combination with an economiser and the pre-chiller, this improves energy efficiency by about 10% over comparable plants,” Michael Walleter said.
The storage was comprehensively insulated and KTI used its unique patented Air Channels. These form an insulating layer between the inner and outer walls of the container, through which cold air constantly flows. This holds the temperature inside the storage at a constant -7°C, preventing gradual warming and thawing of the ice. This technical outfitting of the ice storage ensures that once produced, the ice can be stored with no problems for several days, and then delivered and dispensed.
“Overall, installation of the entire ice supply parallel to the ongoing construction of the factory went ahead rapidly and was problem-free, since we had preassembled all of the machinery in-house, eliminating the need to do much of the work at the site,” he explained.
“So after delivery of the containers to the factory site by truck, we just had to put them together and connect the lines and cables. There was almost no interference with the customer’s operations, and installation time was reduced from three or four months to about six weeks.”