Rats can be a nuisance. The operator of a large grain storage facility in the port of Hamburg knows this only too well. He has therefore set more than 130 traps on the company premises. In the past, there was only one way to determine their success: An employee had to undertake a time-consuming inspection round every day. This is now a thing of the past: the rat traps are now monitored using a sensor.

This example shows the many ways in which the digitalization of existing plants via an IIoT infrastructure can optimize process safety, machine uptime and operating costs (OPEX). Given the scale of many production facilities, the transformation is a huge task, and not just in technical terms. It also has an economic aspect that goes beyond the costs of change. According to the Federal Statistical Office, the gross capital expenditure of companies in Germany amounts to more than 870 billion euros (as of 2022). A considerable proportion of CAPEX is accounted for by the "sensory organs" and "nerve cords" of the processes: the instrumentation for measuring, controlling and regulating. In the course of automation, companies have realigned this area at great expense and requested increasingly powerful devices from measurement technology manufacturers. As processes were increasingly operated at the upper limit, ever more precise and robust sensor technology was required. With the onset of digitalization, the life cycle of many devices of this generation is far from exhausted. The desire to make full use of such quality is understandable. However, if each new instrument were only replaced at the regular replacement interval, a digital transformation could only be achieved in stages.

Third-party integration and scalability

With this in mind, measurement technology manufacturer Wika has developed the concept of customer-specific reverse digitization. It is based on the current status regardless of the origin of the components (third-party integration) and is scalable. The concept starts at the sensor level. After all, this is where all data is generated along the entire value chain, on the basis of which future business decisions are made. An inventory shows which instrumentation can be made smart and which needs to be replaced.

The majority of measuring points are now equipped with electronic devices, most of which have a standard analog signal such as 4...20 mA. Their output is now converted into a digital signal using so-called bridge units. "Bridges" are optionally available with power supply, battery operation and/or ATEX approval and can therefore be easily integrated into existing processes. With the help of such units, even purely analog measuring devices, which are indispensable as a back-up in critical processes, will be integrated into a digital structure in the future.

Connectivity with LPWAN standards and hybrid gateways

The bridges connected to the sensors transmit the data signals to gateways or directly to a central data pool. This raises the question of connectivity, which also enables bidirectional communication. Experience has shown that LPWAN solutions with battery-operated devices require the least effort. They can be used for all measured variables, with the exception of flow: flow instrumentation usually has to process huge volumes of data and therefore requires a corresponding power supply. In this case, a battery-powered solution would only allow short downtimes.

The LPWAN standard that comes into question depends on the respective application and the topographical conditions. Wika, for example, relies on mioty, Lorawan and NB-IoT in order to be flexible and to be able to bridge distances of up to 30 kilometers. Different standards can be bundled into one system using hybrid gateways. Ethernet is by no means ruled out for data transmission either. Mobile radio standards are an option, especially for exchanges with supra-regional transport units. All data flows via the network system either into a cloud or into a customer's own on-premise server. There, it is validated and processed using appropriate tools and visualized on a dashboard for condition monitoring, predictive maintenance, risk management, energy control and similar tasks as a basis for decision-making.

Risk and alarm management

The operator of the grain silo with attached logistics center in the port of Hamburg, whose digital transformation was implemented by Wika using the reverse concept, focuses on risk and alarm management. Grain is handled almost exclusively by ship on a daily basis. The suction hose at the jetty for loading and unloading the freighters operates at a capacity of 250 tons per hour. Reliable monitoring of negative and positive pressure is essential for smooth operation. In the event of a fault, the sensor system triggers a shutdown to prevent a backlog. Another crucial control function concerns the conveyor belts integrated into the loading and distribution process. Temperature sensors monitor their ball bearings to protect them from overheating.

The establishment of an IIoT infrastructure also opens up additional opportunities: The operator of the grain silo, for example, has optimized its loading management by using a tide forecast for the harbour basin. This allows him to determine the best time for his suppliers' ships to dock. Because every minute counts: Half an hour of berthing time costs 10,000 euros.