The changing approach to on-line gas turbine compressor cleaning

The way operators approach on-line gas turbine compressor cleaning has changed significantly over the past 20-25 years.

Operating practices, industry changes and reliability concerns have all played their parts, and we’re looking back to see what’s changed and whether these changes are for the better.

How has online gas turbine compressor cleaning changed?

Over the past couple of decades, online gas turbine compressor washing has evolved, and it’s a good time to look critically at current practices and see if they’re fit for the industry in its current form. 

Historically, many gas turbines operated in baseload service and on-line washing programmes were more common. Then, deregulation in the late 1990s and early 2000s led to:

• Many combined cycle plants built in 1999-2004, creating overcapacity in the US
• Reduced baseload operation in many regions
• Operators believed off-line cleaning could be completed during downtime
• Online cleaning was no longer a priority

During this time, operators also became increasingly cautious about using detergent during on-line gas turbine compressor cleaning due to concerns about:

• Blade liberations
• Compressor damage
• Downstream contamination

Many operators stopped using detergents for on-line washing, converting to water washes instead; some insurance companies would not insure on-line detergent cleaning programmes; and OEMs did not support on-line detergent washing on certain turbine models.

Greater reliance was placed on off-line washes, with on-line cleaning reduced or stopped.

How do operators clean gas turbine compressors today?

Now, looking at today’s operations, many gas turbine operators are influenced by the ingrained practice of conducting infrequent and/or water-only online washes. Indeed, newcomers to the industry know no different. 

Many OEMs also still recommend water-only washes, but cleaning technology has progressed, and it is worth reconsidering this practice and looking at the bigger picture of how washes are carried out.

For example, whether you choose to use a cleaning chemical or not, spray distribution and blade coverage is critically important to achieving your cleaning goals. 

Optimising on-line washes – nozzle technology 

Field observations on some GE units suggested that during on-line water washing:

• Airflow pushed water toward the bellmouth
• Centre/root sections of blades appeared less effectively treated
• Coverage across the compressor face could become uneven

Historical images also showed:

• “Streaking” patterns during on-line washing
• Cleaner blade tips compared to root sections
• Evidence of uneven spray distribution

Whether you’re using water alone or a cleaning chemical, full blade coverage during online washing is essential, and that’s down to:

1. Nozzle design
2. Nozzle location
3. Spray trajectory

Thankfully, wash nozzle technology has come a long way from earlier models, which left visible gaps in spray zones and “scalloping” effects between nozzles. Importance has been placed on nozzle positioning and atomisation of cleaning fluid to ensure full coverage, resulting in better cleans.

This article looks deeper into the importance of blade coverage and spray distribution. 

Summary

Over the past 20-25 years, there has been a shift away from

a) frequent online washes and

b) using cleaning chemicals for online washes.

However, we’ve also become more aware of the importance of full blade coverage and how nozzle technology is key to this.

With an increase in fuel costs, operators also want to maximise productivity and are looking at how cleaning can help achieve this.

At Rochem FYREWASH®, we specialise in gas turbine compressor cleaning and are here to help you plan and implement optimum cleaning for industry leading, cost-effective results. If you’re interested in finding out more, please get in touch.

References

Rochem FYREWASH

https://www.sciencedirect.com/science/article/abs/pii/S0306261912001109 [Accessed 8/6/26]