The Monitor

Production Process Insights

Unreliable Chemical Feed? The Solution Might be Easier than You Think

Posted by AJ Percival on 6/14/19 8:36 AM


Temperature is one of the most critical parameters to control when sampling in a power plant, and accurate and reliable measurements are essential for operational excellence. Incorrect measurements can result in unreliable data that can lead to safety issues and costly equipment damage.

The Electric Power Research Institute (EPRI), American Society of Mechanical Engineers (ASME), and the International Association of the Properties of Water and Steam (IAPWS) require online continuous analysis of all parameters that are critical to minimizing corrosion and deposit formation in the boilers or turbines of power plants.

Most power plants don’t have staff trained in chemistry at the plant 24/7 to monitor these critical steam and water cycle parameters. Instead, a steam and water analysis system (SWAS) delivers the real-time, accurate results they need to operate safely and effectively.

Within these systems, heat exchangers are used to cool steam and water so they’re safe to handle, sample or measure. When a heat exchanger is used to cool a representative sample within a process for accurate analysis, it’s known as a sample cooler. Power plants use sample coolers to condition steam and water samples for accurate chemical analysis per guidelines and regulations.

But if temperatures are off, samples analysis is off, leaving the power plant vulnerable to safety risks and expensive damage plant equipment.

Case study: Inconsistent temperatures lead to unreliable chemical feed in power plant

A power plant in the southern United States discovered inaccurate on-line water instrumentation was being caused by inconsistent temperatures, leading to a lack of trust in the plant’s ability to control the automatic chemical feed.

Not being able to automatically control the chemical feed can cause over- or under-feed. This can damage boilers and turbines and lead to costly downtime and repairs or major safety issues, such as flow accelerated corrosion (commonly referred to as FAC) in steam piping. 

redesigned swas for reliability and cost savings

The resolution to these issues was to redesign the existing SWAS as a replacement was not in the budget and update the piping and instrumentation diagram to match. This included all new sample conditioning products, such as sample coolers, Back Pressure Regulator/Relief Valves (BPRVs), and VRELs for precise control of flow and pressure, Thermal Shutoff Valves (TSVs) and Temperature Control Units (TCUs).

Proper project planning ensured there were no surprises during installation and implementation of the redesigned system and its new components.

With the updated sample system and analyzers, the power plant was able to reliably automate its chemical feed and achieve significant savings on chemicals, while preventing costly repairs.

Proper sampling knowledge and experience can mean saving big

As this plant discovered, quality sampling and analysis are critical for monitoring power plant chemistry.

If your plant’s sampling system needs an inspection, it’s critical to have an experienced team evaluate and address all your sampling issues. Retrofit services can help improve your efficiency of a single sampler or an entire sampling system. By protecting plant assets, we help you confidently ensure the safety of your plant operators and maintain uninterrupted production. When the monitoring is accurate and contamination is prevented the result is more precise water and steam chemistry and fewer chemistry-related failures caused by corrosion and contamination.

Learn how Sentry ProShield Install and Retrofit services can help your facility.

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Topics: Power, Steam & Water

Written by AJ Percival

Picture of AJ Percival
A.J. Percival spent 12 years in the Sentry service group as a technician, training manager, and team manager before transitioning to the Regional Sales Manger role for the Western US in early 2020. He uses his field experience to guide customers to real world solutions for steam and water systems specific to their plants.