Real-time Monitoring Picks Up Steam

Wireless devices help cut energy losses by detecting failed steam traps.

By Seán Ottewell, Editor at Large

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The wireless steam trap monitor (WSTM) from Cypress Envirosystems mounts non-invasively onto existing steam traps in minutes and uses a proven algorithm to detect trap failures, particularly expensive steam leaks. It has been designed to augment manual audits to detect failures in a timely manner.

One of its most successful applications has been at the main technology center of a major U.S. pharmaceutical company. The center includes a number of manufacturing buildings, each supplied with steam, chilled water and compressed air from a dedicated utility plant. Each building is responsible for its own energy consumption and is billed separately by the utility plant. Overall, the center houses more than 2,400 steam traps, many operating in hazardous locations where temperatures can reach up to 500°F.

The utility plant installed WSTMs to continuously monitor the steam system — to provide transparent accountability for each building and close the loop on energy reduction goals for the company as a whole. The payback on this project was under 12 months.

The WSTMs perform monitoring and diagnostics, and transmit health status wirelessly to a central server for trending, graphing, alarming and historization. Installing each WSTM takes less than half an hour and doesn't involve breaking seals, leak checks, or production downtime. Whether traps fail open or closed, the WSTMs provide alarm notification, enabling timely maintenance to increase safety and reliability in addition to saving energy.

The WSTM has a built-in "zero footprint" web-based user interface that enables any user on the company Intranet to view historical trends, graphs and alarms/notifications. It also provides comprehensive reports with an energy summary that shows steam loss and its associated cost for analysis and auditing — no new software or operator training is required, says Cypress.

Existing automation systems easily can integrate the WSTM data via open system interfaces. The pharmaceutical company uses OPC to bring the data into its Wonderware utilities management system; Cypress has a technology alliance with Invensys to ensure operability between its products and Wonderware software.

In a second application, a pharmaceutical company in New England has installed WSTMs on its 550 steam traps.

The company's traditional annual audit was taking about 140 man-hours, costing $20,000 and requiring a calendar month to complete. The pharmaceutical firm replaced all failed steam traps uncovered during the audit. However, before the next audit, around 15% of the traps would fail and start to leak. On average, it took six months before the leaks were detected, at a cost of $375,000 in lost steam.

Installation of the 550 WSTMs has reduced steam leakage by 95% and cut audit labor costs by 70%. Payback was achieved in less than a year.

"Although we are more focused on our healthcare market at the moment, we are absolutely considering the chemical industry and it's definitely a market that we want to grow into," says David Roberts, vice president of marketing.

A major food manufacturer based in the southeast U.S. also has benefited from wireless trap monitoring. The company had developed a preventive maintenance (PM) schedule for steam traps at a large plant that makes multiple product lines. It took a maintenance crew at least an hour to properly check each of the nearly 100 steam traps, which limited the PM to an annual exercise.

To meet its demand for automatic online monitoring of steam trap performance, together with real-time alerts to minimize the need for PM and energy losses, the company installed nine Rosemount 708 wireless acoustic transmitters from Emerson (Figure 2).

The plant already had a self-organizing wireless network for the Rosemount 3051S DP wireless flow meters it was using to monitor compressed air flow. Adding the non-intrusive wireless acoustic measurement devices was easy. "Wireless greatly reduces installation cost, and we use those savings to purchase more instrumentation to extend utility monitoring in our plant," notes the site's project engineer.

The nine transmitters were put on steam lines throughout the plant and integrated into the existing Smart Wireless Gateway, which communicates to a plant host. The acoustic transmitters monitor a variety of types of steam traps and work equally well on all of them, says Emerson; one transmitter even keeps tabs on a steam-driven pump to give early indication of problems. The network was easy to expand; the new transmitters just strengthened the mesh. There's a lot of concrete between the transmitters and the gateway and high EMF, but the wireless communications are strong and reliable, adds the company.

"Manual monitoring of temperature did not give us enough information to conclusively target a steam trap for replacement when we saw water-hammering," explains the project engineer. "But when we installed the wireless acoustic transmitter, we could tell immediately which steam trap was stuck." It was quickly fixed, and a trend of the new trap showed normal acoustics and temperature.

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