Automation of silo logistics for bulk materials by SSB Wägetechnik

More capacity in the bulk goods warehouse of the Port of Duisburg

The family-owned company Karl Schmidt is a service provider for bulk goods logistics. Together with SSB Wägetechnik, the plant engineers have built a logistics centre for bulk goods from the chemical industry in the Port of Duisburg. The expansion of the facility, which was completed in January 2023, includes 40 silos. The bulk goods facility operates automatically from loading to bagging and labelling.

A modern logistics centre for bulk goods for the petrochemical industry is being built in the port of Duisburg. The location is of great importance for the plastics industry. Products are filled from containers into silos, stored and loaded onto trucks or repacked into bags as needed. The surrounding producers of chemical products also use the modern silo facility for the logistical distribution of their market flows.

Digital networking of bulk materials plants

The experts in the field of bagging, weighing and control technology from SSB, together with a large logistics company, have designed and built a plant that allows digital processing of the processes as well as a high degree of automation. The entire silo logistics system consists of several system components such as:

▪ Silo filling ▪ Silo discharge pusher
▪ Truck loading ▪ Container loading
▪ Big bag filling ▪ Bagging systems
▪ Palletising systems ▪ Pallet packaging systems
▪ Forklift operation to the warehouse.

Until now, there was no networking of these individual components. The machines or trades were operated by means of manual work orders. By digitally networking all the individual components, these processes can be monitored automatically and made even safer.

Arrangements made in the control technology

All components have modern control systems that are networked via TCPI protocols. A central master computer and modern operating and display monitors are installed at each individual workstation or machine. The plant now comprises 60 silos in the first expansion stage. All processes are largely automated. A control system networked via Ethernet works with TCPI, Profinet or Modbus as protocol and includes the following components:

Communication visualises every work step

Modern communication shows and visualises every work step at the operational level. The number plates of the trucks are read in automatically. For this purpose, each truck is detected by an induction loop at the entrance with barrier system and the camera is activated. The camera sends the photo to a server, which transmits the number plate to the silo control system. This is checked for plausibility according to the order and access is granted.

The loading scales and the loading bowls are positioned automatically and the driver recognises the position and the subsequent work steps via LED displays. The loading process is fully automatic. A mobile loading scale is positioned under the silo on an intermediate level. This scale pours the product into the loading bowl all the way to the truck. The loading scale consists of a weighing hopper and an emptying hopper. The scale requests the product from the silo and the silo slide opens. After weighing the individual bulk (usually 500 kg), the scale empties into the truck. A complete truck load consists of several weighings. The scales receive the total weight to be filled (usually 25,000 kg) from the central control system and process this in several weighings. The result of the total quantity is documented for calibration and transferred to the system. This avoids operating errors or even incorrect loading.

The filling process of the bagged goods or the big bag large containers also takes place in the silo system on an intermediate level. In this area, mobile bagging machines are installed that can reach every silo. Conveyor belts transport the filled and sealed bags to the palletising area. To achieve the best quality, each bag is checked for tight closure, accurate weight and metal contamination before being printed with the necessary data. The information such as batch number, product name, consecutive no., date, time, warnings, expiry date etc. can be printed as text and as bar or QR code. The print is checked for plausibility by means of a scanner.

A modern robot system palletises the bags onto the corresponding pallets. Signal columns or touch panels on the corresponding assemblies signal the previously described operating/error messages, such as metal detection, missing weights or bag breakage. Layer patterns and pallet stack heights can be freely programmed with the robot. The empty pallets, including the protective sheets, are separated from an empty pallet magazine and fed to the robot via shuttle systems.

The sequence of the individual components is interlocked via software programmes. The individual magazines or stockpiles are monitored via light barriers or other sensors. The completion of pallets is communicated to the following assembly. The full and finished pallets are also transported by shuttle to the packaging machine. A stretch hood machine fully automatically packs the pallet rainproof. The packed pallets can then be driven into the warehouse by forklift truck or AGV.

Control and management

All operating processes are monitored and visualised at a central control system. Product recipe management, order management and the warehouse management programme are connected to the control system via OPC server. The programme software for visualisation and sequence control is realised with Siemens Tia-Portal. Profinet is used for the interfaces to the individual machines, and the plant manufacturer uses OPC server interfaces for customer systems or connections, e.g. SAP. Due to the network structure, the plant can be operated or remotely controlled from any location.

Each machine has its own maintenance programme. The cycles are recorded and compared with the maintenance interval. In the central software, the individual maintenance cycles are programmed so that a required maintenance can be announced in time. This concept includes the integration of all sensors and machines.