Sensor & Network Technology

This scoping study was undertaken to assess various new sensor and network technologies now available for integrated plant systems. It involved a literature review and an investigation of the nature and performance of several combinations of modern sensor and network technologies in a coal preparation plant environment. The project ran for twelve months, and included two visits to the Tarong Coal Preparation Plant to test and demonstrate some of the newer sensor and wireless technologies.

As is common with most digital technology, sensor and network infrastructure costs are falling and reliability is improving. However, due to increasing technological capability and demand for productivity improvements, there is a greater incentive to increase the level of instrumentation and automation in coal preparation plants. This trend can only lead to more complex networking and data management systems and the challenge will be to produce efficient and practical system designs. This study attempts to identify and clarify key issues influencing the design and performance criteria used to select sensor and network technologies. This information is intended for plant operators interested in potential upgrades, retrofits or expansions of existing systems, and designers of new plant systems.

In general, the authors concluded that distinct technical advantages can be achieved by plant operators who take ownership of their network, its design and operation. Over the life of a plant, economic advantages can be achieved in servicing, upgrading and expansion of sensor installations by having a flexible and readily accessible network infrastructure. There is a broad diversity of equipment and design philosophies to choose from, and the following considerations have been identified as relevant to coal preparation plant situations:

• Just like any other process, network traffic requires management. To successfully manage such network traffic it is critical that plant operators understand the nature of their network and use appropriate technology.
• Industrial Ethernet is not yet the "universal fieldbus" that many perceive it to be. Whilst it can be used at the cell level (communication between computers and PLCs) conventional Fieldbuses should continue to be used for safety or time-critical control functions. However, it should be noted that this is a rapidly advancing field and new technologies should be examined as they appear on the market.
• Middleware products are able to bridge the gaps that exist between different technologies and vendors, but it is important that plant operators be aware of their limitations and suitability for different applications (i.e. object, message or event based middleware).
• New wireless systems work in the plant environment and offer many advantages over wired systems, however, they also introduce a new level of uncertainty in safety and security. New safety and security protocols will no doubt continue to be developed. Nevertheless, it is advisable to perform a rigorous risk assessment on each individual wireless application as part of the technology selection process.