Monitor machinery health

Monitoring the performance of plant equipment plays a vital role in preventing unplanned shutdowns. Mike Spear reports on how real-time asset management is now being extended to rotating machinery such as centrifugal pumps and motors.

Digital control systems have brought about something of a revolution in the monitoring and maintenance of control and instrumentation equipment. ‘Intelligent’ or ‘smart’ field devices can now all have their status monitored on-line, in real-time.

This diagnostic data is fed back into asset management systems, which turn the data into information for plant operators, maintenance engineers, and management. But until now, the ‘asset’ being managed has, by and large, been just the control and instrumentation hardware itself.

The condition monitoring of other process equipment, such as compressors and pumps, has tended to be left in the no-doubt capable hands of maintenance teams equipped with their own monitoring and analytical tools. The results of their diagnoses are then communicated to plant operators, off-line, and rarely in ‘real’ time.

At the European launch of the company’s ‘Smart Machinery Health Management’ technology in Paris last month, Emerson Process Management’s marketing product manager, Todd Reeves, presented research showing that 43% of plant incidents can be attributed to mechanical failure.

‘There are around 2500 machines in a typical process plant,’ he says, ‘of which 60% are motor-pump combinations. Operators often don’t realise their impact on plant equipment, and the effect of the process on machinery health. Up to half of equipment breakdowns can be related to poor operating practices.’

This was borne out by Emerson customer surveys that called for machinery health monitoring to be integrated into plant automation systems, so that operators can react more quickly to diagnostic results. Presented with customer comments such as ‘we need updates in less than 60 seconds if analysis results are to be acted upon by operators’, and ‘pumps can tear up in seconds and 4-20mA sensors can’t detect problems’, Emerson has responded with the new CSI 9210 machinery health transmitter.

As with the SIS safety instrumented system introduced last year, the CSI 9210 is an integral part of the company’s PlantWeb architecture, transmitting its diagnostic data over Foundation fieldbus to the DeltaV DCS where it can be viewed with the integrated asset management software, AMS Suite.

Reeves describes the launch of the CSI 9210 transmitter as ‘a breakthrough in the world of rotational machinery analysis. It’s the first device to deliver diagnostic information over open systems, rather than the proprietary systems of traditional condition monitoring systems.’

The initial release of the CSI 9210 is aimed at centrifugal pumps and their motors, particularly those operating at critical parts of the process. Although one transmitter monitors only one pump-motor combination, it handles a multitude of data from the equipment. There are six vibration sensor (accelerometer) inputs to monitor rotational performance, a motor flux sensor used to detect electrical defects, and four temperature sensors.

Data collection settings are based on the type of machine being monitored, but data processing — from data collection, through on-board Fast Fourier Transform analysis, and on to transmission over the fieldbus — is accomplished in under 25 seconds, which is sufficiently close to ‘real-time’ for most applications.

Traditional condition monitoring procedures, whether data is collected manually on site or over a proprietary computerised maintenance management system (CMMS), generally involve some degree of expert analysis of the spectral data generated by vibration sensors.

Emerson’s ‘expert’, however, is embedded within the CSI 9210 itself. Over 20 years’ worth of analysis expertise has been programmed into the transmitter, complete with fuzzy logic, neural network-based, problem solving capabilities. This embedded ‘analysis engine’ accurately identifies potentially damaging conditions such as pump cavitation, bearing degradation, excessive synchronous vibration, and motor overloading and overheating.

Results are communicated using the Foundation fieldbus protocol into the process automation system. For non-DeltaV users, an interface is available to communicate with non-FF host systems via Modbus RS 485.

When used with Emerson’s own PlantWeb architecture, however, the CSI 9210 delivers its analysis results in the form of PlantWeb Alerts, which categorise the warnings as ‘advisory’, ‘maintenance’, or ‘failed’. A specific ‘Machinery Health Value’ is also given along with recommendations for any necessary action. And unlike other CMMS systems, this information goes straight to the operators.

Reeves claims that ‘with this Machinery Health Value, we have effectively created a new process variable.’

Because the transmitter is an integral part of the PlantWeb network, its diagnostic information can also go to maintenance and management teams, as well as operations. Information targeted specifically at operators might include alerts about pump cavitation, an overheating motor, excessive vibration or severe bearing faults — all issues that could impact on the process unless dealt with quickly.

Maintenance staff would see this information as well, of course, but would also be privy to more long-term issues such as imbalance, misalignment, looseness, early bearing and motor defects, or poor lubrication.

‘The technology is aimed at bringing the two sides of operations and maintenance together,’ says Reeves, ‘so that they both know of impending problems at the same time, rather than maintenance having to beg operations for time to correct faults.’

Management, meanwhile, would receive aggregated information on unit and plant health, asset priorities, work order status, trends and reports. But the real benefit of Smart Machinery Health Management should be felt at the plant level.

According to John Rezabek, controls specialist for BP Chemicals, Lima, Ohio, which has had three units on field tests for the past year: ‘The CSI 9210 can alert our operators in real time when equipment problems start to manifest. If a change in upstream head, volatility, or composition results in increased flashing or cavitation, they can make adjustments to eliminate the problem.’

Although initially focused on pump applications, follow-ups — over the next two to three years, says Joe Podolsky, Emerson’s asset management director for Europe — will include transmitters for fans, rotary blowers, compressors and turbines.