Foam vs Fouling: What Actually Drives Outage Duration?

Responsible gas turbine compressor maintenance includes regular, effective cleaning. However, have you ever thought much about the cleans you carry out and whether they could be more efficient?

It’s important to get your equipment back up and running as quickly as possible to maintain productivity, so it’s useful to understand what impacts cleaning outage time. The next step is to consider whether you can reduce outage time without compromising on the end result. This is where we can help.

What drives outage duration?

During off-line cleaning, the gas turbine compressor is shut down and isolated. After this soak wash, the cleaning solution is drained away, a sample is analysed, and a repeat wash is carried out if necessary.

It’s true that the severity of gas turbine compressor fouling impacts how long a wash takes, but it is not the only factor. Fouling determines how much cleaning is required, but foam levels dictate rinse time.

It’s important to thoroughly rinse away foam before getting the gas turbine compressor back on-line.

Therefore, outage duration is determined by a combination of:

• Severity of fouling
• Foam levels i.e. rinse time

Both factors are important, but the latter is often underrated. Understanding what is affecting total wash time is the first step in cutting it down.

Cleaning heavily fouled compressors

A heavily fouled compressor requires more energy to deliver the same output. Internal volume is reduced, which affects efficiency, and there is also greater potential for malfunction.

When combating heavy gas turbine compressor fouling during an offline wash, your equipment will likely require longer initial rinsing with cleaning solution. This gives the chemicals longer contact time to penetrate, dislodge and dissolve deposits.

Foam is an important part of cleaning as it increases the surface area covered by the cleaning chemicals and the duration of contact allowing for more effective foulant penetration. However, excess foam takes a long time to rinse, so the right balance of foam levels is essential.

How to reduce outage time

In an effort to reduce outage time due to excess foam removal, some operators double dilute their cleaning chemicals. While this does cut down on foam production it also impacts cleaning effectiveness and is not recommended. In the short term, the process compressor is back up and running quicker but the compromise is long term cleanliness and there is a likelihood that you will face another, unscheduled off-line wash in the near future and/or you’ll shorten the lifespan of your equipment.

The better alternative is to attempt fouling prevention and carefully choose an effective process compressor cleaning chemical which produces appropriate levels of foam for a thorough clean without requiring excessive rinsing.

Examples of how foam affects rinse time

Operators often report exceeding the minimum rinse pulses indicating a need to flush away excess foam. This shows us that long rinse durations are frequently driven by foam removal and not simply the severity of fouling alone. From the table, it’s clear to see the impact on rinse durations and rinse pulses required by switching to a low foam detergent.

Get in touch

Understanding what is driving outage time during off-line gas turbine compressor maintenance helps you make informed decisions, which can save time and money. While many operators presume fouling is the only factor, foam levels play a significant part.

We specialise in cleaning chemicals and equipment for gas turbine compressors, and our range of FYREWASH® products is specially designed to target foulants without generating excess foam. We have a range of chemicals to choose from and are here to help if you have any questions about which is best for your site. with our friendly, knowledgeable team to find out more.

References: all data supplied by Rochem.