Integrated method to measure the on-site efficiency of a Synthetic Oil Mist Separator (SOMS) employed as an auxiliary system for an aeroderivative gas turbine

摘要

Auxiliary systems like the Synthetic Oil Mist Separator (SOMS) are used as an essential service to gas turbines. They are designed mainly to restrict aerosol emissions to the atmosphere. Aerosols emissions from gas turbines are composed of small oil particles of varying sizes, ranging from lnm to 1,000 nm. For this application, the aerosol is called "oil mist" because the temperature of the fluid is lower than vapor temperature during the dispersed phase resulting in the mist. It is a sub-product of the gas turbine during operations. The amount of oil mist produced is influenced by time and other operational conditions of the gas turbine (rpm, energy production, wear, etc.). In this study, we analyzed oil mist production from a gas turbine on site at two different operational conditions: Core Idle, when the gas turbine did not produce energy, and Full Load during energy production. The SOMS was designed to collect and separate oil from air, by coalescence, whereby millions of oil droplets moving through the SOMS and the microfiber cartridges combine together to form larger size drops. These larger drops drain downwards and are collected at the bottom of the SOMS. Knowing the actual efficiency of the SOMS at operational conditions of the gas turbine is important, due to environmental limitations for emissions. Indeed, there are regulated limits to the total amount of oil that can be released into the atmosphere in these applications. This limit is recommended to be lower than 5 mg/m~3[l] in accordance with OSHA Permissible Exposure Limits (PEL). Nevertheless, it is not trivial to estimate the actual amount of oil released into the atmosphere. Literature shows that researchers are still involved in studying procedures to make a comprehensive and standard method for qualitative and quantitative analysis. In this paper, we present our approach and results for in situ measurements. The measurement methods presented here were first evaluated in laboratory on a SOMS. Then these methods were used to evaluate the performance of the SOMS in situ on a gas turbine under operational conditions. Based on these results we believe that this protocol can be a good candidate to become a standard for in situ measurement of the efficiency of SOMS. Currently, many other improvements are under investigation.