Testing the Method for Diagnosis of Gas Turbine Engines Condition Using Optical Emission Spectrometry of Lubricating Oil
Authors: Mariasov Maksim , Markina Elena 
Published: October 2018

For instance, stationary gas turbine engines (GTE) are used at gas-compressor stations or power plants. These GTEs are often converted from aircraft gas turbine engines operated on military and civil aircraft. Accordingly, the methods for diagnosis of stationary gas turbine engines conditions have "migrated" from the aircraft engines diagnosis.

Gas turbine engines tribodiagnostika - this is one of the types used for condition diagnostics of bearing blocks and other friction units; this type is based on the phenomenon that microscopic wear particles getting into the lubricating oil are separated from the parts exposed to contact loads during running. The tribodiagnostics methods are aimed at studying the properties of these particles: amount, size, composition for early detection of increased wear of any assembly.

The paper deals with the problems regarding the implementation of laboratory studies of operational synthetic lubricating oil for tribodiagnostic monitoring of gas turbine engines at the gas compressor station of the main gas pipeline. The studies are carried out with the inductively coupled plasma-optical emission spectrometer (ICP-OES).

The main reasons that make the introduction of atomic emission spectrometry difficult for monitoring condition of friction units in stationary gas turbine engines are identified: Non-compliance of analysis procedure with its conditions. The tribodiagnostics methods involve determining a metals amount in the oil, which are represented in the form of oil contained metal particles separated from the engine friction units. At the same time spectrometer ICP-OES is intended to determine a dissolved metals content in samples. To analyze these metal particles, special sample preparation with dissolution in acids shall be carried out. For this purpose the approved standard procedure shall be used, however, it was not found for the lubricating oil.High filtration degree of up-to-date oil filters. In many cases, the up-to-date units are equipped with the filters having a filtration degree of 3 to 15 μm. Wear particles being the subject of tribodiagnostics study get into the filter and remain inside due to which they cannot get into the sample for analysis.High analysis cost comprising high cost of the spectrum analyzer and consumables for its operation and high cost of maintenance. It leads to increasing operating costs.

There are several other factors that make difficult the implementation of tribodiagnostics methods, such as the need for frequent oil sampling that in the case of a large fleet of operating equipment also leads to increased costs of analysis. In some cases aircraft engines tribodiagnostics allows to prevent the engine failure in flight. And the feasibility of tribodiagnostics implementation for operation of stationary engines is left to the discretion of operating organizations that shall decide whether it is ready to bear somewhat higher operating costs to obtain an unlikely realized opportunity for early diagnosis of engine failure.