Spiromatic reuses lost dough with smart rework system

Every recipe is a new challenge

“A first challenge was cooling,” says Tom Windels, automation expert at Spiromatic. “Dough is a living product. And you want to pause that life. You must not cool too quickly or it will stop living. If you cool too slowly, it will still start to rise. And if you cool unevenly, your dough will partially rise. Fortunately, we already had a lot of experience in cooling liquids in heat exchangers.”

The second and biggest challenge was adding the semi-finished product again. “That’s not just a matter of pumping through. How much rework we add is different for each customer and even for each recipe. Nothing must change about the final product: taste, colour and other properties must remain absolutely the same. So we have to start determining how much rework each recipe can ‘tolerate’ based on customer testing. For that, we designed a mobile installation.”

“Scalability was also a hard nut to crack. At the lab scale, a process behaves differently than in an industrial context. There is quite a lot of complexity in the line, but it worked: the only limiting factor left is the size of the client’s building. As long as he can use all the rework within 48 hours, there is no limit to the size of our process.”

Smart control with PID Control

The heart of the system is a rugged PLC: the redundant SIMATIC S7-1516. “For small test rigs, smaller PLCs are sufficient. On large integrated projects, we used to use multiple PLCs to communicate with each other. That created a lot of overhead, making the whole thing increasingly complex. Siemens advised us to house the whole thing in one PLC and keep it redundant. It works perfectly that way.”

Spiromatics installation demands quite a lot from the PLC. “We constantly monitor quality with temperature sensors and viscosity measurements. It includes volumetric and mass flow meters, SIWAREX weighing modules, etc. The PLC processes all that data and automatically adjusts the process based on PID Control, a technology object in TIA Portal. That made integration a lot easier.”

“The PLC has to coordinate three processes simultaneously: creating the rework, controlled addition and cleaning the plant completely,” says Ludo Dejaeghere, CEO at Spiromatic. “Some customers run full-time, so then we have to clean parts of the plant while it continues to produce. Obviously, no cleaning agent should enter the production. That flexibility and modularity require a lot of computing power.”

The ultimate optimisation

The rework plant has been on the market for a year. More and more manufacturers are now avoiding up to 30% food waste. This reduces their raw material costs, but also CO₂ emissions in raw material production, transport and waste disposal. “For me, Spiromatic sets a new standard in the bakery world with this,” says Thomas Vermeir, account manager at Siemens. “What producer can still do without it? We are very proud to have collaborated on such a ground-breaking innovation.”

“We have been an OEM partner of Siemens for six years,” Ludo adds. “We are getting a lot of support and it has definitely helped to bring this project to fruition. It is also in this way that we like to work with our customers: in a partnership, where we look for solutions together. They have an enormously wide range of technology, but they still manage to be highly responsive. This is important because we also provide 24/7 support to our customers.”

The rework plant has already found its way to processors of pizza and pastries. There are many manufacturers on the market that are not yet using raw materials optimally. Yet Spiromatic is already working on its next project: reuse of baked goods. “It is still in its infancy, but eventually we also want to be able to reuse all baked products that do not meet the standard for whatever reason. That will reduce food waste much further.”