Viewpoint: what can be learnt from the ‘Lego principle’

Shorter production runs and increasingly varied requirements from the same plant: these are the volatile market demands that more and more process manufacturers and operators must adjust to.

The solution is plants based on the ‘Lego principle’ of modular automation, where users can easily add modules or switch them off to match shifting requirements.

Process plants have traditionally been tailored to a respective task – for instance, throughput of a specific liquid at x quantity per time unit.

The mechanical design of the plant is then geared towards meeting this specification over its projected life cycle, with corresponding process automation centrally controlled via a single plant management system.

The ‘Lego principle’ of modular automation [means] users can easily add modules or switch them off to match shifting requirements

Changes or optimisations are therefore challenging, not to mention maintenance and servicing, where continuous processes might have to be completely shut down.

But as the market increasingly demands shorter product development times and customised products – particularly in the biotech/pharma, food and beverage, and water treatment sectors – a fundamental shift in the design and engineering requirements of process plants is required.

In a water treatment plant, for example, the operator must deal with wildly fluctuating water consumption and supply, not to mention increasingly polluted water.

Moving on

The traditional design for a water filtration plant includes valves, pumps, tanks, filters, sensors and pipes. The components for actuating the field devices are installed in a control cabinet, and a valve manifold and I/O racks are connected to a central controller, with visualisation and connectivity to the management system via a fieldbus.

Today, plants of this type can be modularised by breaking down the process and defining modules for each sub-process with all the mechanical and automation components required for standalone operation.

The control cabinet components and ‘central intelligence’ (process application software) are divided up so that each module has its own controller, remote I/O components and pneumatic actuators.

Digitisation and networking enable these autonomous, intelligent modules at the field level to be connected simply and reliably with a master control system, while also providing communication between them – in the same way Lego bricks click together to form a solid, but nonetheless reconfigurable and adaptable structure.

In water treatment skids in different configurations can be created and combined, depending on the application.

Digitisation and networking enable these autonomous, intelligent modules at the field level to be connected simply and reliably with a master control system

Pump skids, with their low level of complexity, require only a few valve slices in the pneumatic section of a valve terminal; filter module skids need analogue inputs and outputs for pressure monitoring.

More complex modules, such as CIP (clean-in-place) skids, require further automation modules, such as analogue inputs for temperature measurement or a controller for the proportional technology.

The skids operate autonomously and are extremely reliable, communicating continuously with the master controller managing the overall system. Costs for wiring are comparatively low, and since the modules are transportable, they enable water production to be started up rapidly.

For original equipment manufacturers (OEMs), the modular concept also makes it possible to produce volumes of uniform modules or even produce skids for stock, delivering economies of scale in both production and assembly.

At the same time, process end users can serve and respond to their markets more quickly, with the right production quantities.

This is where the worlds of the process industry and manufacturing industry intersect – with Industry 4.0-enabled flexible production processes helping maintain the competitiveness of process industries in ever more volatile markets.

• Kai Feller is product manager, process automation at Festo