Gas Turbine Cleaning

[Uncleburt]

I recently became aware of Carboblast cleaning on gas turbines. I have been reading about different materials used in CarboBlasting, the one that seems to be most popular is using walnut shells as the medium. Could someone suggest a website where I could find out more information about CarboBlasting and some procedures on the best ways to perform it? I have been looking around but am only finding vendor sites that do not offer much background.
Thanks!

 

[pmover]

the gas turbine mfg will gladly provide you the needed information for online cleaning of afc (axial flow compressor). walnut shells are a favorite material. by the time the walnut shells get to hot section, they are thoroughly burned (consumed) such that they do not impact the turbine hot section. i am not aware of any impact to lo-NOx combustors when online cleaning is accomplished, but that confirmation should come from the mfg.

good luck!
-pmover

 

[irishal]

I carboblasting still common? I know the carbo blast system on my plant was decommissioned quite some time ago. We now use a liquid detergent injected into the turbine inlet.

 

[toothless]

My understanding is that using solid materials (such as walnut shells, rice, or other material) to clean the compressor is a discontinued practice. The material sometimes took off the protective coatings and other material made its way through cooling passages and plugged small holes.

Walnut shells DO work to clean the turbine, but are you willing to risk it?

We use D/I water for on-line washing.

 

[Adam01]

Use detergents and demin water if you have a wash system installed. We have used Carbo blast on our machines but only use online and offline water wash now because of the risk to blocking cooling holes. If you dont have a wash system installed then walnut shells are probably the only option for you (other than pulling the rotor and hand cleaning). You may find it difficult to get a supply of carbo blast because of the loss of favour. We bought the last batch from John Brown Egineering in Scotland. They got swallowed up by GE. European Gas Turbines also supplied us some but they are now GE or Alstom. Why dont you google it.

 

[Uncleburt]

We havent had too much success with water washing this unit and it has been derated by 40% already due to surging at base load. Water washing only had significant effects on the first few stages of the compressor, therefore we wanted to test the shells for cleaning improvement. We were able to get several hundred pounds of walnut shells and are going to run it through the unit this morning. I was mainly just looking for suggestions on procedure on CarboBlasting. From what I have seen though, it is pretty straight forward; run at base load, dispense shells into intake and (hopefully) watch compressor performance increase.

 

[rmw]

I was trained to do it that way many years ago. We just went into the filter enclosure and began to heave handsfull of walnut shells into the compressor inlet.

The downfall has been mentioned already. The fine particles that are generated can and will clog small passages that compressor discharge air has to pass through.

You may want to check with your OEM or even check the manual. There may be specific users of compressor discharge or bleed air that need to be closed off during cleaning with this method.

I seem to remember that rice hulls are also suitable for this procedure if this is the only method of cleaning that you can do.

rmw