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How to Understand the Cation Resin Lifespan

Posted by John Powalisz on 4/19/17 4:16 PM
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Cation resin can last a few days or several months, and it can be difficult to predict the lifespan even in ideal conditions. So how do you know if your resin is still functional at any given time? What does it take to prolong the life of resin – and how do you know when it’s time to refill or regenerate it? It all starts with understanding the cation resin lifespan and the many factors that affect it. Read on so you’ll never get caught with depleted resin again.

There are many factors that determine the life of cation resin. One of the key drivers in today’s market is that many utilities are changing chemistry control processes, which might include dosing amine or ammonia to control pH. These chemicals and their by-products directly impact cation resin. More ammonia or amine, the faster cation resin is spent.

How to Know Whether the Resin Gets Saturated?

The easy answer is when the color indicator is changed to a “straw brown” color. A more complex way to monitor this is to log and compare both specific conductivity (SC) and cation conductivity (CC) for the sample line. As both SC and CC increase together, the ion exchange resin will probably start to become depleted. It is important to keep the overall function of cation conductivity in mind because an increase in SC and CC can also indicate a more critical problem, which is what these measurements are meant to monitor!

How Long Until the Resin Needs to be Replaced?

Resin life is contingent on many factors, including the loading of the cations that the resin column is meant to capture. One of the more dramatic causes for resin to become spent or used-up is the over dosing of chemicals, such as amine or ammonia, in an AVT chemical treatment program. pH of the boiler is controlled by adding a mixture of chemicals, including amine or ammonia, and these items are captured by the resin columns. Overdosing of the chemical = depletion of resin.

Too high a flow rate can also decrease life of the resin. A typical flow rate thru the RC unit is about 200 cc/min. High-temperature samples near 50°C will also affect resin bed life. Other contaminants might also be in the system, which are captured by the resin column.

Resin life can range from a low of several days to a high of several months to half a year depending on plant chemistry control and other factors.

Is it Possible to Use Reagents to Extend the Lifespan of Resin?

No, there is no additive that can extend the life of resin. A resin bed is a collection of a special type of high-performance plastic beads that are used like a filter to capture cations. They’re very sensitive, especially in high-purity water like in a power plant.

Cation conductivity is often a critical measurement used to determine steam and condensate purity, as well as other samples that indicate if the plant is being damaged by out–of-control cycle chemistry and other problems. The plant chemist should have a thorough understanding of this measurement and how to effectively use cation resin.

Please note that this information is not exhaustive and is only a starting point for understanding the function of cation resin.

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Written by John Powalisz

John Powalisz, Industry Manager, 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.

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