Wireless Monitoring Improves Power Plant Operations

  It’s always gratifying to see an article get published that started out as a customer presentation at Emerson Exchange. Here’s an excellent case in point written by Robinson Castillo, a senior instrument and control engineer for Florida Power and Light (FPL), a subsidiary of NextEra Energy. What makes it even better is the way it illustrates a classic example of replacing a tedious manual operation with automation. The specific article, Wireless Monitoring Improves Power Plant Operations, was published in the June 2019 issue of Power, and discusses two examples, but we’re going to concentrate on just one. 

The tedious manual operation: sending operators to read mechanical pressure gauges on calibration gas tanks for continuous emissions monitoring systems, but let’s let Robinson explain the situation.

           At the FPL facility, the calibration gas cylinders were inspected by plant operators during their daily rounds. Duties included recording gas pressures in the daily shift log. If the pressure was lower than 300 psi, the operator replaced the cylinder with a full one located at the shack, and moved another full one from the central location to the specific shack.

 Sounds simple enough. Since the tank changing process is a manual operation, what’s wrong with reading the gauges manually? For starters, there are nine shacks around the plant each with four calibration gas tanks, which makes for a time-consuming process.

           The manual log process took about three man-hours per day, but inspections could be delayed or postponed if the operator was needed for higher-priority tasks or emergencies. In addition, the rounds were sometimes delayed by rain, lightning, and other issues. Therefore, shift logs were not always up to date. This is critical because if an analyzer calibration fails because there is no gas supply to the analyzers, its data is no longer valid, and the associated unit may be forced into an outage.

The last point is the key one: “…forced into an outage.” You know what outages cost—all because conditions did not allow an operator to read the gauge and act upon the information. The plant considered adding pressure transmitters to the 36 tanks, but wiring all these back to the control room and adding them to the plant’s Ovation DCS was considered too expensive. Plus, the operators liked having an easy-to-read local display if they needed to check status while in the plant. The facility already had a working WirelessHART network, so they found a simple means to solve the problem without adding any wiring: the Rosemount Wireless Pressure Gauge.

          Emerson’s Rosemount WPG has a 4.5-inch face for local visibility of status and pressure, and it transmits a WirelessHART data signal back to the gateway and the DCS. A gas-pressure-low alarm in the DCS was set to 300 psi as a priority one (red) alarm. When the alarm is seen, the control room operator instructs the outside operator to replace the cylinder, thus preventing calibration failure due to lack of available test gas. For this application, the WPG monitors pressures from 0–3,000 psi. Its data update rate frequency was set to once a minute to improve the battery lifespan to an estimated 10 years.

Robinson says that eliminating this routine task reduced the time spent on manual rounds, saving the facility $44,000 in labor costs per year. You can find more information like this and meet with other people looking at the same kinds of situations at Emerson Exchange and in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the Power and IIoT Groups, and other specialty areas for suggestions and answers.

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