Implementation of modular plant structures in greenfield and brownfield applications

The introduction of the Module Type Package (MTP) in the process industry is progressing, as evidenced by the first successful industrial applications. Nevertheless, potential users need to familiarise themselves intensively with the standard in order to fully exploit its advantages. Especially in the context of brownfield applications, the various scenarios can lead to confusion. This overview shows the various realisable implementation options for modular systems in greenfield and brownfield applications. 

Advantages in the greenfield 

In the greenfield sector, where plants are built completely modularly, the MTP concept offers numerous advantages such as a fast market launch, short repair times and economically viable batch size 1 production. Such systems consist of individual process equipment assemblies (PEAs or modules), which guarantee maximum flexibility and low engineering costs thanks to MTP-compliant interfaces. A packaged AML file describes all functionalities, control elements, communication aspects and the structure of the modules. The superimposed Process Orchestration Layer (POL) uses this information to largely automate the manufacturer-independent integration of the modules, which enables plug-and-produce behaviour. This includes tag mapping and the generation of standardised user interfaces, while the orchestration of functionalities is carried out manually. 

Use in the brownfield 

The MTP concept can also be used in existing systems (brownfield). Here, the functionality of the POL is often integrated into existing SCADA or control systems (DCS). A software update enables existing systems to integrate MTP modules via plug-and-produce and thus improve expandability. This hybrid architecture combines the advantages of both worlds and can be expanded step by step. Time-consuming integration using mapping tables and additional control code development are no longer necessary. Modules can be integrated independently of the control system and replaced quickly to minimise downtimes. The module size is variable and can be adapted to different application scenarios, such as the integration of complex analysers in process analysis technology (PAT).

Flexibility within the modules 

It is often required that modules are designed flexibly so that individual functional equipment assemblies (FEAs) can be connected or removed without reprogramming the controller. These FEAs can be IP67 remote I/O stations with sensors and actuators or smart devices that are connected directly to the module via Ethernet APL. A firmly defined pool of compatible FEAs enables their flexible integration, even during operation. Various approaches are used at module level to support this flexibility: 

1. Customised MTPs: For each configuration, there is a specific MTP that precisely maps the functionalities offered. However, this is only practicable for a manageable number of configurations. 

1. Operating screens for FEAs: FEAs are represented by dedicated operating screens, with one main operating screen and one additional operating screen for each FEA. However, this method can lead to confusion and requires manual screen changes.

MTP gateways and hubs 

A classic brownfield application is the subsequent MTP conformity of an existing process skid. This can be achieved by integrating an additional controller as an MTP gateway, which maps the existing module to the MTP model. Data is exchanged via Ethernet or ADS interfaces so that controllers can be extended with MTP functionality or devices can be integrated via serial interfaces. 

In the MTP hub approach, several modules are realised on one controller, each of which implements a specific process logic in conformity with MTP. This architecture enables flexible integration of the modules, which makes economic and technical sense, especially with many small modules. The various PLC runtimes can be interconnected in the real-time system in order to realise proprietary interlock or safety logic between the modules. 

Conclusion 

By combining the different approaches and the flexible use of MTP hubs and gateways, both greenfield and brownfield systems can be designed efficiently and flexibly. This enables rapid adaptation to changing requirements and minimisation of downtimes, which increases competitiveness in the process industry.