How digital instruments are helping make industrial processes smarter

Since the appearance of smart instrumentation in process and power plants in 1983, ongoing advances in sensor and microprocessor technology have provided users with a steadily growing store of information. 

Smart instruments in the field measure or directly affect single or multiple plant variables, contain a microprocessor for processing data, and are commercially available “off the shelf.” These instruments include not only sensors for measurements and communications, but also actuators, valves, motor variable speed drives, and other control equipment. They allow operators and engineers to gain more useful information about the process and the device itself.

Today’s plant engineers and operators have access to such functions as power management, maintenance systems, process automation, asset optimisation, and safety systems. Standards such as NAMUR NE107 are steadily improving the Human Machine Interface (HMI), making it easier to commission, configure, and manipulate instrument parameters.

Benefits of smart instruments

With the introduction of intelligent instruments in fieldbus networks, process engineers can now access an increasing array of data that can be used to optimise process performance.  Remote configuration and calibration, detailed process variables data and diagnostics are all available at a fraction of traditional costs, without compromising informational value.

The development of bus communications has drastically increased the amount of transmissible information. Also, bidirectional communication of digital information can take place between a field device and a system, and between field devices.

To make the most of communication improvements and to satisfy more advanced needs, big changes are taking place within field devices, especially those with wireless capabilities.

Opening new paths with wireless

Potentially valuable information acquired by process instruments is often left stranded in the field that could otherwise be utilised if a communications pathway back to the host control system was available. Many instruments have a built-in HART communication protocol normally used during instrument commissioning. With the arrival of WirelessHART wireless adapters, cost-effective and secure communication to remote condition monitoring applications can now be achieved.

By having a wireless communication pathway, plant assets can be maximised, and unplanned plant shutdowns reduced, with both helping to reduce costs and maximise productivity.

In addition to the measured value, status and alarm messages provide valuable information about plant conditions as well as the reliability of the measured values.

Multivariable transmission

As bus communication supports multivariable transmission, an instrument can transmit multiple data such as control signals, limit signals, and valve opening signals via a single cable. In this way, measurement and control capabilities can be expanded to simultaneously measure variables such as pressure, temperature and flowrate. With such information made available, outside forces such as environmental effects can be compensated for and process control becomes quicker and more efficient. 

Asset management

Equipment uptime for continuous production represents an important factor in improving process plant productivity and overall profitability. Smart instruments can play a key role in optimising the maintenance function toward this end.

The operating conditions of critically important rotating machinery can also be monitored. Permanently installed sensors make it possible to communicate vibration information continuously. Vibration levels of support machinery can also be measured periodically in the field by plant personnel using portable equipment.

Furthermore, a complete picture of operating conditions can be provided by data processing via health management software. The ability to overlay frequencies, and match fault frequencies to peaks, allows trained personnel to efficiently analyse the data. Alarm reports enable decision makers to quickly evaluate a situation and take appropriate action to prevent a breakdown.

Summary

There still remains a long way to go before the benefits of field-based intelligence are fully realised throughout the process industries. However, growing pressure from all the key areas impacting on business today, from tough trading conditions and health and safety issues to energy costs and environmental concerns, are all driving plant operators to look for ways to work smarter. Intelligent instrumentation can help them do that.