‘An average 46,500KW power plant gas turbine with normal fouling and showing just a 3% power decrease and 1% heat rate increase can suffer a loss of performance costing more than $500,000 every year.’
Fouling refers to the accumulation of unwanted material on solid surfaces causing an undesirable roughness. In a gas turbine compressor this means deterioration in the aerodynamic form of the aerofoil blades and annulus surfaces, resulting in reduced air flow, lower efficiency and a lower pressure ratio.
These losses of performance are indicated by a decrease in power output and an increase in heat rate which means lost profits and increased environmental damage.
TYPES OF FOULING
The worst fouling problems are caused by mixtures of liquids and oils or generally hydrocarbons, which deposit on the blades and form an oily film which catches dry particulate matter. This could be caused by the burnt fuel exhausts emitted from turbines, and can be particularly severe if less clean fuels such as crude oil are used. Oil leaks are another major problem and even smoke from surrounding industries, cities and vehicles contribute toward the fouling.
As the air ingested into the compressor is heated the moisture in the air evaporates, leaving salt and dissolved constituents to deposit on the blades. Not all salts are soluble and when exposed to the operating temperatures inside the compressor these deposits can become firmly baked onto the compressor surfaces. Salt also gives rise to blade corrosion and should be promptly removed.
Dust and sand
They generally cause erosion and can lead to fouling when combined with other constituents such as oily vapours.
The atmosphere also contains numerous other contaminants including farming chemicals, plant spores, insects, smog. Even some additives in cleaning products, if not rinsed off properly, can all contribute to the fouling.
HOW TO CLEAN THE FOULING ?
What do we have to do ? you really need gas turbine cleaner
Off-Line (Soak or Crank) Washing;
Off-line washing is conducted with the gas turbine in a cooled state, by injecting cleaning solution into the compressor while it is being turned at cranking speed. Once the chemicals are injected into the compressor, the gas turbine is shut off and allowed to come to a halt. The chemicals are then left to soak for 20-30 minutes, before being thoroughly rinsed with demineralised or deionised water. The efficiency of crank washes is very high, and the power recovery is close to the original level or the level reached after a major overhaul. When to Wash? Online washing needs to be performed regularly to decrease the fouling rate but the timing of offline washing is a more complex proposition. When determining the best time to perform an offline wash all of the following must be considered.
- Environmental Factors such as the amount and type of contaminants in the local air supply.
- Time Constraints on the operator owing to demand for the turbine to be operational.
- Acceptable Level of Power Degradation to the user.
Minco is happy to work with operators to help them develop the best washing solution for their specific needs. Our products are tailored to meet the online and offline washing requirements of all types of gas turbine compressors, and to deal with all types of fouling effectively.
There's no substitute for washing with quality cleaning chemicals.
Washing will remove fouling deposits and restore performance, but full power may not always be regained once significant fouling occurs.
It is vital that the compressor is washed regularly to help maintain performance. Regular washing may also slow the progress of corrosion, thereby increasing blade life and reducing the contribution of corrosion to the formation of fouling deposits.
On-Line (Fired) Washing;
On-line washing is the process of injecting a solution into the compressor while running at full speed, usually at base load. This is advantageous as it can be performed without having to shut the machine down. High operating temperatures of compressors, the high centrifugal forces on the injected liquid and the short contact time of the wash solution with the fouling all mean this method only has a limited effectiveness. It should only be used as a preventative measure to prolong the time between off-line washes and not as a substitute.
For more details, please make a contact with the sole agent in Indonesia is Pt Zefa Valindo Jaya, Phone: (o21) 8873531 Fax: (021) 8873532 Email: email@example.com