The Monitor

Production Process Insights

Maximizing Cycle Chemistry with Smart Analyzer Alarms

Posted by John Powalisz on 3/9/22 8:15 AM
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In a steam and water analysis system (SWAS), alarms can frequently turn into a nuisance for operations and maintenance personnel. Over time, plant personnel can become desensitized, leading them to distrust analyzer data or not act when chemistry events arise. This can leave a power plant vulnerable to chemistry-related failures that could cause downtime and negatively impact production. Smart alarms help address these issues by monitoring cycle chemistry, identifying chemistry events in real-time, and allowing chemists to take proper actions to correct conditions. These smart analyzer alarms help steam and water operators improve their response time to critical chemistry events.

GuardSA Smart Alarms

Smart chemistry alarms have evolved from a hotly anticipated new technology to practical reality, and an increasing number of power generators are implementing the technology to manage alarms better. “Logic for Smart Chemistry Alarms” from EPRI was published in 2017, and since then, approximately 23 power plants have implemented smart alarm technology.

Sentry’s GuardSA™ Smart Chemistry Alarms support this transition by monitoring the signals generated by online chemistry parameter analyzers to provide real-time intelligence about what’s happening in the plant and what steps need to be taken to resolve the chemistry event or analyzer issue.

The application interprets the analyzer signals using EPRI smart chemistry alarm logic and only triggers when actionable chemistry events occur. In conjunction with those intelligent alarms, the application provides intelligent analyzer trouble alarms signifying when a critical analyzer has an actionable issue. GuardSA smart alarms provide operator guidance on the nature of the problem and customized troubleshooting advice without Chemist involvement for swift action.

Two implementations of GuardSA Smart Alarms

Most of these plants have chosen to build the logic into their existing Distributed Control System (DCS), with four plants opting for the GuardSA stand-alone package.

Two recent installations illustrate how different plants can quickly implement Sentry GuardSA alarms to continuously monitor chemical feeds and prevent a pH excursion or biofouling event that could shut down production.

The plants include:

  • A two-on-one, gas-fired combined-cycle unit with two boilers and one steam turbine
  • A coal-fired, supercritical unit with one boiler

In both cases, the standard GuardSA unit was configured with the plant type, boiler, and feedwater chemistry, then populated with the system samples and corresponding analytic measurements. Each system was customized based on the individual operating characteristic set points and levels associated with the built-in EPRI Smart Chemistry Alarm logic.

The systems are connected to the system output in MW or boiler pressure signals to provide a permissive or “go” command. This facilitates keeping the system quiet and ready without sounding alarms during shutdowns or cycling operations. GuardSA is also configured to provide a general alarm output to check the system. In regular operation, the unit will only deliver alarms that need attention in the case of an event.

Smart chemistry alarms are helping both of these plants:

  • Reduce nuisance alarms
  • Provide specific cycle chemistry insight
  • Deliver clear and actionable guidance when chemistry events happen

In addition, operators plan to use the chemistry event alarms as a training tool, using the advanced trending and analyzer historian functions built-in and tied to the chemistry event logic. Operators can use the system to look at an alarm (active or not), see the related analyzers and values, event guidance, and current and historized analyzer data within the event window to see a comprehensive picture of the system’s chemistry status. Located near the SWAS, operators can even relate all of this data to the actual field instruments leading to other operational insights.

In today’s data-enriched power plant, intelligent chemistry alarms like GuardSA quickly become the go-to tool for system-wide chemistry insights, helping bridge the gap between chemists and operators.


Simplify cycle chemistry monitoring, reduce errors and protect assets with Sentry Equipment GuardSA Smart Chemistry Alarms. Contact us at +1-262-567-7256, or complete our online contact form for more information.


Written by John Powalisz

Picture of John Powalisz
John Powalisz, Director of International Sales, is dedicated to sharing his technical expertise and knowledge of sampling equipment and systems in power plants, refineries, chemical and food processing facilities garnered from more than 19 years with the company. John has worked with clients worldwide to help them to comply with regulations and optimize processes by applying proper sampling hardware and techniques. While he is well-versed in all Sentry products and applications, he is particularly focused on the food and beverage and power generation markets as well as emerging market development.