The speciality chemicals market is demanding ever-more adapted products. Processes need to be developed quickly, and production facilities designed as flexibly as possible. At the same time, they should consume minimal energy and raw materials to keep the CO2 footprint light. One approach to meet all these objectives is modular production.
Modular production has been a major research and development focus over the past decade. Recently, the German initiative ENPRO, funded by the German Ministry for Economic Affairs and Climate Actions (BMWK), showed that modularisation and accompanying digitalisation could bring reductions in energy consumption of as much as 3 TWh for the German process industry alone. Technology company Merck have consequently announced a project to go modular with their chemical production project MPS.
So why is so much effort being put into the development and implementation of modular plants, and how can it help the process industry in its transition to sustainable production? Modularity by itself does not lead to more efficient processes. However, the flexibility it creates opens opportunities to implement efficient new technologies without a complete redesign of a complex process. Another important factor is scalability.
Flexibility through standard modules
By using standard modules, more flexible production is possible. The modules can be combined to suit the respective process and can be quickly integrated into the automation through the interface. In the planning phase, the requirements are formulated and suitable modules are identified in a module database. This database can consist of the already existing module park, but also contain available modules from suppliers. Even if only some of the required process steps can be mapped using existing modules, a partially modular structure can still save a considerable amount of time in plant planning, construction and automation and thus shorten the time-to-market. The repeated use of equipment also offers significant cost advantages. A method for the selection of the right modules for a given process has been developed in the ENPRO project SkaMPi.
Modules in process development
If standard modules are used, correspondingly smaller and scalable continuously operated equipment can be used in process development. Continuous processes are usually much more efficient than batch processes. A pilot phase is necessary to transfer batch results from the laboratory to a continuous process. It is costly and, therefore, often avoided, resulting in production processes being run in inefficient batch modes. With the use of continuously operated laboratory equipment, this pilot phase can be significantly reduced or even completely eliminated. New, efficient, and scalable process technologies have been and still are being developed in ENPRO projects.
A “printer driver” for modules
Two essential aspects play together in modularisation. The process equipment must be subdivided into modules, and the automation technology needs a modular structure. In combination, this results in a paradigm shift in process development away from unit operation based engineering to services provided by modules. Instead of individually integrating the feed valves, the temperature control unit, the stirrer and the required sensor technology into the automation of a stirred tank, there is a kind of printer driver for the module – the Module Type Package (MTP). The MTP interface provides the “mixing” service, which receives the parameters of the mixing process from the so called process orchestration layer. The control of the individual components of the module is encapsulated in the service supplied by the module manufacturer.
The conductor for the modular process plant
The process orchestration layer coordinates the interaction of the individual modules and integrates the modules into the overall plant. In this way, new modules can be quickly integrated into an existing plant, as only one element needs to be added in the automation system. Even the integration into the user interface is simplified by the MTP, as the elements to be displayed are included. The design of the visualisation is specified by the control system to achieve a uniform look and feel. For this to work, standardised data exchange formats are required, such as the XML-based DEXPI format for describing the module structure.
How to get the process data
Since the process steps are encapsulated in the services of the modules, the question arises how the process data can be made available for other Industry 4.0 applications, for example advanced analytics. The answer is the NAMUR Open Architecture (NOA), which makes this data available via a second channel, without affecting the process control.
Costs of modular systems – a strategic decision
With modular systems, processes can be developed more quickly and the use of continuous apparatus ensures high efficiency. This results in a noticeable cost advantage – but only over the operating time of the equipment.The initial investment costs are higher than with conventional plant design. If the modules shall be reused, they cannot be designed for specific parameters, but must cover a larger parameter space. These costs are amortised by repeated use of the modules and the design can be reused as well. Investment costs, however, are credited to the current project and not to optional processes that may be possible in the future. This requires a strategic decision for the concept of the modular plants to enable the implementation independent of individual projects.
Over time, further cost advantages will also arise, because if a module park is gradually built, the production site will become more flexible.
On the automation level, it is much more complex to define possible services for the MTP than to program a basic operation once. However, the services are provided by the module supplier. They can reuse the programming service for similar modules, which relativises the cost on his side. Nevertheless, there is a shift of the programming effort from the operator to the supplier.
The leap into comprehensive application
A large number of suppliers already offer equipment with MTP. The major automation suppliers have also integrated MTP functionality into their systems and pilot projects at users’ sites have been implemented. From these initial approaches, it is now necessary to shape the modular production of the future.