The Monitor

Production Process Insights

Can one out-of-service analyzer cause an unscheduled power plant shutdown?

Posted by Paul Williams on 5/25/16 3:31 PM
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The answer is yes.

Power generation plants rely on demineralized and deionized water to maintain required levels of water purity during process operations. Managing the water supply is critical under normal operating conditions, as well during outages. This ultrapure water is kept in demineralized water storage tanks, often referred to as demin tanks.

Excess silica can cause a plant shutdown

One plant in the western U.S. experienced an issue with silica leaking into its demin tank because the plant’s analyzer was not working properly. If silica carries over into the steam, it can cause severe damage to the steam turbine.

The plant was using demin trailers instead of the standard demin tanks, and experienced a silica breakthrough in the trailer. A silica breakthrough is when silica levels rise very high – for example, 6 ppb can rise to 6 ppm very quickly, which can cause damage. While the plant had a silica analyzer connected to the demin trailer, but it was not in service and therefore not monitoring. With the analyzer out of service, the plant did not have alternate working procedures in place to monitor the silica levels. Additionally, as part of the perfect storm, a shutoff actuator valve had been installed to shut off demin water flow to the plant in case of silica leakage, but the valve also was not working.

Because of these issues, and to prevent further damage, the plant had to shut down for several days, which cost hundreds of thousands of dollars in lost work time and production.

Prevent unscheduled plant downtime

No plant should have to undergo unscheduled downtime due to loss of online instrumentation functionality. As a result of this experience, this plant now relies upon a Sentry® service agreement for monthly maintenance performed by factory-trained and authorized service technicians. Regular maintenance ensures analyzers are calibrated and safely operating at peak performance with adequate levels of reagents.

Dedicated local service technicians will inspect the condition of components, clean, repair or replace wearable parts, replenish reagents and other consumables, and test sample flow and filter systems, as well as coordinate the ordering of consumables and reagents so you have them on hand for continued smooth operation.

Sentry service can include regularly scheduled preventative maintenance; troubleshooting; safety inspections; analyzer calibration, verification and certification; installation or retrofitting of an individual analyzer, component or complete system; startup and commissioning of new sampling systems and new plants; system shutdown or startup; training and consulting; and/or parts and consumables.

Application information courtesy of Chad Smith, Sentry service technician.

Background information from Power magazine.

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Topics: Power

Written by Paul Williams

Paul Williams is Sentry Aftermarket Products and Service Manager. The aftermarket business encompasses three distinct operating units that provide technical maintenance services, installation and retrofit, product fulfillment and technical support. Williams relies on his 25-plus years of experience for strategic partnership development, market expansion and branding, with an unwavering focus on customer success.

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