Hey group,

Please provide me with all information available on the EFFECT OF ASH STICKING POINT ON TURBINE BLADES, your cooperation will be higly appretiated.

Thanks

Is this problem relating to the compressor section or the turbine section?

Most deposits go on evenly but come off randomly and can change the balance of a rotor (maybe this is what happened to generate your previous post)

However, there shouldn't be any deposits there in the first place.

What sort of fuel is used on the turbine: gas or liquid? Does the fuel quality meet OEM specs - if not, you might be seeing products of combustion adhering to the blades. This is equally true for a gas fuelled turbine where the fuel contains significant amounts of liquid (condensates etc) pointing to a potential fuel gas skid problem.

How often do you wash the engine? If the wash intervals are extended too far or the wrong wash fluid is used, the deposits are not fully cleaned off and continue to build up - making the compressor section inefficient and running hotter - this eats into the life of the hot path components increasing your overhaul costs.
Its probably worth carrying out a detailed borescope inspection before and after each wash just to see how effective this operation is

When you ask for the effects of ash sticking to the turbine blades - do you know where the ash is coming from? It might be worth analysing a sample. You should also check the effectiveness of the inlet air filtration system.

If the GT blades are air cooled, then the presence of ash sets up the possibility of having some of the air cooling holes getting blocked, causing the blades to overheat and shortening their lives.

The fuel used in the turbine is liquid fuel (Deisel), this problem relating to the turbine section, And about the fuel it is assumed to meet the OEM specs.
The ASH is coming from the fuel due to the stoppage of fuel additive dosing system in regular basis, the question is what are the hazards of stopping this fuel additive system permenantly which cause these ash particles to stick on the Turbine blades ?

Thank You very Much

How good is your assumption that the fuel meets OEM specs? I would suggest you got a fuel sample fully analysed by a competent lab.

Some of the more obvious hazards associated with stopping the dosing are as follows:

a) Blocking of air cooling passages
Already dealt with in my previous post

b) Fouling of blade surfaces:
This can act to reduce hot gas flow path making the engine run hotter for a given load: this in turn will give increase EGT and limit the engine load capacity.

c) The combustion products will go onto hot blades: at rest when the blades are cooled down, the combustion product coating may well come off in lumps (a different thermal expansion rate to the metal blades) making the turbine section unbalanced

Why do you want to turn of the additive dosing system?

Thanks for your help, the information provided to me by you was very useful .... any way I was thinking of isolating the additive dosing system because a problem occured with the fuel filters (short life) where the filters started to chock in short periods .

Great thanks for loay my colleague and all who may share us in solving ths problem, we prlace fuel filters daily fo our Gt's after it was monthly, isolation of fuel additive ( Turbotect 667), dosing rate is 50 ppm, tha amazing thing is that the fuel source is one
Im pointing out on fuel, but what analysis is to to do, what content in fuel may do this????

Really we still stuck ::::

Alllllll Thanks for allllll

So, in summary: without the additive, fuel filters last a month and with the additive they need to be changed daily?

And, without the fuel filters, you get ash (or some sort of combustion product) build up on the turbine blades.

Although you probably need to focus on why the filters are clogging up, can you explain how you know that without the additive you will get ash build up on the turbine blades?. Is this something you have witnessed youselves or is this what the additive sales rep says will happen if you don't use the additive?

You should get a blocked filter to an independent lab and request that they find out the nature of the material that is clogging up the filter and equally importantly, find out what sizes (or range of sizes) of particles are present. You might want to send samples of fuel, of additive and of fuel containing additive for analysis to see if this can help identify the source of any blocking material


There could be several things happening here:

a) by itself, the additive might be able to pass through the filter but reacts chemically with diesel to produce particles that are too big to go through

b) maybe the additive contains particles that are too big for the filter

c) possibly the additive (maybe in some sort of reaction with the diesel) chemically attacks the filter material causing it to block up.

d) Maybe the additive causes normally inert buildup in the internal fuel path to break off in lumps and clog the filters?


How long has this problem existed? Have you recently:

a) changed fuel supplier
b) started using the additive
c) changed additive supplier

You need to get as much info as you can and then try working with the filter supplier (or even call on the services of another supplier)

Thanks Light year
Problem is nearly 3 month old, answer is no for a,b,c. Dosing additive is commonly used since 3 years, it is recommended by the GT manufaturer to avoid fouling.

We cut a clogged filter to find a waxy material covered the mesh area like a nylon cover.

your comments are good,addetive is fully clean but i doupt in sort of reaction between fuel and additive to get this waxy deposites.

A lab has tested for bacterial effects, it was negative

Fuel is passing through separation, prefilter, then to then to filter BETA 22 micron(1000)ie 999 particles with 22 micron or greater is collected, is this filter more fine????? should we replace it???? who recommends another tested BETA value???

You might not know exactly what happened, but its hard to conclude anyone other than something changed in one of the elements 3 months ago (diesel quality, additive makeup or filter construction/material).

Again, you need to go to a lab to find out what the waxy material is (is it the filter material dissolving or is it something resulting from the fuel additive combination?)

Thanks very much for light year, it is really a fuel quality problem, I reported that.
Thank all