Wireless increasing process data flow

Manufacturers understand the benefits of acquiring more data about their production processes but face the frustration, as much industrial capital equipment was not instrumented for today’s needs when purchased.

Process plant that can benefit from monitoring includes – ovens, boilers, compressed air systems, refrigeration plant, motors and pumps. However, such equipment and its associated control systems have often been acquired piecemeal over a long period of time and there is often no overall centralised view of equipment status or performance.

In the process industries typical applications include plant condition and process monitoring, energy monitoring and environmental monitoring. Production managers need to increase the data gathered from such equipment in a flexible manner as it may not be clear at the outset which are the important parameters or the optimum locations on the equipment for taking measurements.

Wireless sensor networks can provide insight into overall operations and arm operations personnel with instant information to better track status, improve advance warning and alarm notifications, and reduce failures and downtime. They can also dramatically cut the cost and time required to retrofit monitoring in all types of situations and their flexibility and scalability guarantees the long term value of any investment.

This is particularly true of compressed air systems, which provide one of the most expensive utilities used in most plants and for which overall efficiency assessment and management has previously been very difficult to accomplish.

In one example, a large US-based paper mill worked with its electricity supplier and National Grid to install a SensiNet wireless mesh netwrok to monitor the efficiency of its compressed air system. Electrical energy used by the 120kW motors driving the compressors, header pressure, air flow from headers and end-of line pressures were all monitored.

The additional data allowed insight into both demand side problems, such as leakage, faulty equipment and deferred maintenance, and supply-side problems such as over-pressurisation, partial loading, ineffective duty cycles and equipment size mismatches.

Overall, the gain in system efficiency after remedial measures was 30% giving a 3-5 month payback on the system’s installed cost. In addition, monitoring was now in place to ensure that the system continued to run and be maintained in an optimal manner. Later, the simple addition of extra flow metering in the system provided greater insight into operating practices and the opportunity for further improvements.

In an advanced UK accelerated composting plant the incoming material is processed in 3-metre diameter, 30m-long rotating drums for primary composting before being fed into similar but shorter steam-heated drums for sterilisation. It is essential, both to comply with legislation and to ensure efficient use of steam energy, to monitor the temperature of the drum contents during the sterilisation stage and store the readings for later audit.

Although many methods had been tried, including other forms of wireless and manual data collection with paper forms, it was not until a SensiNet wireless mesh sensor network was installed that the problem was solved.

The system reads data every minute through its wireless Pt100 sensing nodes mounted on the drums and feeds it via mesh nodes and a wireless gateway into the Wonderware plant management system via Modbus TCP. Operators are now able to monitor process conditions real time while data is stored automatically for compliance reporting.

Energy management is another subject of increasing focus for companies in all type of industries and businesses. Reasons include the spiralling cost of energy and legislative mandates as well as the desire by many companies now to do their bit for the environment and understand their carbon footprint.

However, in many cases older manufacturing plants and commercial buildings, and the process and environmental management equipment that is within them, simply are not fitted with enough monitoring sensors to give the data needed.

In another scenario, a company running large baking ovens realised the potential savings available to them by closer monitoring of gas consumption. Wireless installation is estimated at around half the cost of an equivalent wired solution and would be significantly less disruptive in the sensitive environment of a food plant.

Nick Baker is director of Adaptive Wireless Solutions Ltd, a Great Missenden, UK-based supplier of industrial and commercial monitoring systems. Tel: +44 870 850 7997