GAS TURBINE OPTIMIZATION

gas turbine ingestive cleaning

GAS TURBINE INGESTIVE CLEANING

Operation of the unit may be performed only when conditions indicate it is safe to proceed. Dangerously explosive natural gas accumulations, fuel fumes, oil tank vent leakage, and solvent fumes must be avoided. This is done by proper ventilation, elimination of Leaks, and by confining the use of solvents to appropriate maintenance facilities. The operator must understand gas turbine and driven equipment operation, function, and systems and know and understand all indicators, normal indications, controls, and operating limits. Operating and maintenance personnel must use fair hearing and eye protection near the operating gas turbine.

Table of Content
  1. Purpose of Axial Compressors Cleaning
  2. Performance Evaluation on Saturn Gas Turbine
  3. Recording Pre/Post-Cleaning Performance Data
  4. Cleaning Modes
  5. ON-CRANK MODE
  6. ONLINE MODE
  7.  Cleaning Fluids
  8.  WATER WASH
    1. CAUTION
  9.  Standard Ambient-Temperature Water Wash
  10. Low Ambient-Temperature Water Wash
    1. CAUTION
  11. CLEANING SOLUTIONS
  12. NOTE

Purpose of Axial Compressors Cleaning

Contaminants such as dust, salt, and oil-laden air pass through the gas turbine air filters. They adhere to the engine compressor blades and decrease engine performance. Ingestive cleaning may eliminate the following engine performance-related problems:

  • An increase in turbine temperature (T5) causes the topping machine occurs.
  • General lack of acceleration.
  • Failure to accelerate to full speed.
  • Compressor surge.
  • Inability to develop full output power.
  • Loss of compressor discharge pressure.

 

Sometimes, the need for compressor on-crank cleaning is indicated when

contamination is visible at the air inlet and through the compressor borescope ports. When cleaning the engine axial compressor, ensure that any sources of contamination, including poor air filtration, the oily mist from the oil tank vent, and the exhaust of nearby equipment, have been eliminated.

Performance Evaluation on Saturn Gas Turbine

 

Evaluate engine performance to determine if the engine axial compressor should be cleaned on the crank. Cleaning should be performed if the trend of the per cent-of-change approaches 5 % (measured from the baseline or the final reading of the most recent cleaning). You must evaluate follows critical factors:

  • Turbine gas temperatures (T5, T7)
  • Compressor inlet temperature (Tl)
  • Barometric pressure (or site elevation)
  • Gas producer speed (Ngp)
  • Compressor discharge pressure (PCD)
  • Output power
  • Inlet and exhaust duct pressure drop
  • Water injection rate (if applicable)
  • Fuel flow

 

Recording Pre/Post-Cleaning Performance Data

 

To accurately measure the performance of the compressor cleaning system and determine necessary changes to cleaning frequency and dosage, the essential engine operating parameters should be recorded before each cleaning and about 30 minutes after the water rinse. If this data is recorded carefully, a performance trend will soon be established to show how the cleaning system performs.

 

Cleaning Modes

CLEANING TOOLS
CLEANING TOOLS

The gas turbine axial compressor can be cleaned while the engine is cranking (on-crank mode) or while the engine is operating in the simple cycle mode (online mode).
On-crank and online compressor cleaning system is specifically designed to maintain the engine compressor. Its effectiveness will depend on the proper use and monitoring of engine performance parameters regularly. Monitoring engine performance can indicate the effectiveness of on-crank and online engine cleaning. However, degradation of engine output is not necessarily related to gas turbine compressor degradation only and, therefore, should not be the sole basis for evaluating the effectiveness of on-crank or online engine cleaning.

ON-CRANK MODE

 

In the on-crank mode, the engine operates at the maximum speed obtainable by the starter alone, with the fuel and ignition systems de-activated. On-crank cleaning is more effective than online cleaning. The waste stream produced during the on-crank cleaning procedure is discharged through the drain ports. Online cleaning may be used between on-crank cleaning cycles to extend the time between on-crank cleaning and to minimize further contamination of the gas turbine compressor.

ONLINE MODE

 

In the online mode, the engine operates at any power level ranging from idle (no load) to full-rated power with engine temperature stabilized at operating speed.
In online mode, an engine compressor can be cleaned with the gas turbine operating

normally within minutes. Cleaning does not affect engine operation and should be performed on a scheduled basis. This allows the operator to avoid engine downtime while preventing a fouled and inefficient gas turbine compressor.

The online cleaning system is based on the injection of finely atomized water and cleaning fluid, thus avoiding the many problems associated with abrasive cleaning methods, which can erode blades, damage special coatings and bearings, and block up turbine blade cooling holes.

 Online cleaning in a salt-laden environment is not recommended.

Adequate air treatment must be employed to remove the bulk of airborne constituents, such as dried salt particles. Airborne salts removed during the cleaning process can cause serious damage to the hot section of the turbineOn-line cleaning is intended as a supplement to on-crank cleaning, not a substitute. The compressor must be cleaned in the on-crank mode regularly.

 Cleaning Fluids

The two cleaning fluids are water and cleaning solutions. Either fluid may be used in either cleaning mode (on-crank or online). The concentrations will vary depending on the cleaning mode selected.

 WATER WASH

Water removes water-soluble contaminants such as salt, chemicals, dust, or other non-oily nonwaxy substances from the compressor air path. Standard ambient-temperature water wash and low ambient-temperature water wash are the two water washing methods. It is recommended that deionized water be used. A recommended method for measuring water purity would be a conductivity meter. Acceptable values should be four megohms resistance or 0.25 micromhos conductance.

CAUTION

Low-ambient temperature water wash may be done only in the on-crank mode.

 Standard Ambient-Temperature Water Wash

Standard ambient-temperature water wash is used at inlet plenum temperatures above +39F (+4C) and may be conducted in either the on-crank or online cleaning mode. If the inlet plenum is not easily accessible to verify the temperature, the water wash may be conducted at ambient temperatures above +50F (+10C)

Low Ambient-Temperature Water Wash

Low ambient-temperature water wash is used at inlet plenum temperatures from
+39F to -4F (+4C to -20C) and can be conducted only in the on-crank mode. The solution for low ambient-temperature water wash is a mixture of water with equal parts-by-volume ethylene glycol (per MIL-E-9500) or isopropyl alcohol (per ASTM M 70). The water used in the mixture must meet the requirements for water used in ingestive cleaning. It is recommended that deionized water be used.

CAUTION

Engine cleaning is not recommended when the ambient temperature is below -4 F (-20C)' Automotive or commercial antifreeze products are not acceptable. The use of such products may cause severe damage to engines.

Use of Antifreeze Materials in Cold Weather Operation recommends that the operator consider using antifreeze for on-crank washing when the inlet plenum temperature is at or below +39F (+4C) and ambient temperature below +50F (+10C).

CLEANING SOLUTIONS

Solar cleaning solutions should never be used for online cleaning unless a properly designed and installed injection system is fitted. Solar cleaning solutions can be used with any on-crank cleaning system. Solar Turbines recommended cleaning solutions may be used in the on-crank and online cleaning systems. Other cleaners may not work effectively.
Before use, mix the applicable concentrates with deionized water. Cleaning solutions will not chemically attack special blade coatings. For cold weather, refer to standard procedures and mix cleaning solutions with commercially available antifreeze agents such as isopropyl alcohol or methanol.

NOTE


The water and antifreeze must be pre-mixed before adding the concentrate, cover, on-crank washing, and on-crank rinsing.

The liquid detergent and antifreeze/water solution must be a homogenous mixture during the injection. If a mixture of concentrate, antifreeze, and deionized water is allowed to sit for an extended time, the solution should be constantly agitated to regain homogeneity.

 

If you want to know other articles similar to GAS TURBINE OPTIMIZATION you can visit the category Maintenance Tips & Tricks.

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