Historically, power plants, especially those running on coal, operated on a base load system, staying active almost continuously except during planned outages for maintenance. We are talking about months and months of constant operations.  With the rise of combined cycle natural gas plants plus clean energy/Renewable energy plants that reduce demand on the traditional grid, the need for flexibility in energy production has caused these plants to adopt a more cyclical operations approach. This means plants come online, meet demand, and then shut down as necessary, a stark contrast to the operations in the past.

Why Traditional DO Analyzers Are Problematic

Relying on amperometric or galvanic sensors, older analyzers operate much like a simple battery. As electric charge wears out a battery, exposure to oxygen wears out the sensors. Once a base-loaded plant got up and running, because oxygen saturation was low, e.g. 5 ppb (parts per billion), the sensors could last a reasonable amount of time before needing replacement.

As increased cycling became prevalent, all bets were off. When plants cycle up, oxygen levels spike exposing the sensors to increase stress. Instead of lasting a year or two, sensors would only last a month or two because the more oxygen they confront, the sooner they deplete. Along with shorter lifespans, plants expose themselves to potentially inaccurate readings increasing risk of damage.

Two Reasons Why this Matters for Plant Operators

The enhanced obsolescence of traditional galvanic sensors is problematic on two levels. First, the maintenance is time consuming. This is not like replacing the battery in your TV’s remote control. You have to replace a membrane and re-electrolyte a probe which involves potassium chloride. It’s one thing to go through this process, which calls for a skilled technician once a year yet quite another to be doing this every other month.

Additionally, among all the mission critical tasks required for operations, analyzer probe calibration tends to fall to the bottom of the list. Because the traditional galvanic sensor is designed to operate in an always-on, low oxygen saturation environment, they tend to read low. This becomes problematic when worn out sensors fail to read higher saturation levels. For example, a Pennsylvania power plant using a traditional analyzer was reading at .5 ppb.  Upon calibration, the reading was really 5ppb. The plant dodged a bullet because if the saturation was at 10ppb, it could have resulted in some serious damage.

Simply put – galvanic sensors are more costly and riskier.

The Luminescent Advantage

This is where  luminescent technology takes center stage. Unlike conventional sensors, this technology capitalizes on light pulses to detect oxygen concentration. This means no membranes, no toxic chemicals and no relentless recalibrations. It eliminates the maintenance burdens of traditional sensors, presenting a near-zero maintenance solution. At it’s best, a traditional galvanic sensor will need yearly replacements. Not so with luminescent technology which can run for twice as long without needing to be touched.

But the advantages do not end there. In addition to reliability, luminescent technology ensures accuracy and immediacy – which is crucial when a plant comes back on line. And remember, that is happening more often today. As plants power up, operators want to get readings as soon as possible to validate safe operations. A galvanic sensor needs 10 – 20 minutes of cycling before delivering accurate readings. A Luminescent analyzer will deliver accurate readings in 1 – 2 minutes. That is a 10x efficiency gain.

One final consideration for today’s power plants, many operators are using corrosion (i.e. rust) fighting chemical treatments that introduce oxygen into their systems. In such an environment, accurate dissolved oxygen readings are more important than ever to ensure balanced water chemistry is maintained.

Are You Ready for LDO?

If you’re ready to experience the Waltron advantage, learn more about our Luminescent Dissolve Oxygen Product Line or contact us schedule a product demonstration. Choose Waltron for reliability, precision, and unmatched expertise.

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