Session: 20-03 Gas turbine package and expanders

Paper Number: 103144

103144 - Experimental and Numerical Investigation of Forced Ventilation Loss in Gas Turbine Package 

Whenever a gas turbine is installed inside an acoustic enclosure, a ventilation system is required to cool down the package and dilute any accidental gas leakage. Due to the possible presence of gas, all items installed inside the enclosure shall be suitable and hence certified as per hazardous area requirements to prevent them from being source of ignition. For this reason, the correct operation of the ventilation system is essential to meet the certification limits and consequently to safely run the gas turbine train. A malfunction of this system can result in a reduction or a complete loss of ventilation flow in the worst case. In this event, an emergency shut down of the gas turbine train is triggered by the control system after a short transient operating condition. A robust design of a gas turbine package shall also consider such transient condition of ventilation loss to encompass all possible operating scenarios and to verify for each item the certification limits during this time frame. Furthermore, each item, including the engine itself, must maintain its reliability and immediate readiness for use for the next restart.

Since ventilation fans are usually driven by AC power motors, AC power loss is the most common cause of ventilation loss. For this reason, Baker Hughes performed an experimental test on a real scale package of a Nova LT family turbine. The real scenario occurring in situ in case of AC loss was exactly replicated and several measurements were acquired with dedicated instrumentation installed inside the package. The purpose of this test was to check the thermal field inside the gas turbine enclosure and the amount of natural convection flow which is generated by the “chimney effect”, in order to verify that the certification limits were not exceeded during the transient event of ventilation loss.

Additionally, the natural convection flow inside the GT internal path (intake, engine and exhaust) was also measured to better understand the contribution given by this flow in terms of heat removal from the engine casing. Measurements confirmed that the combined effect of both flows was sufficient to guarantee an adequate ventilation cooling of the package without impacting the package design. Moreover, the naturally established flow was sufficient also to avoid any possible rotor lock in, so that the engine stays ready for restart as soon as normal conditions are restored.

From the numerical point of view, a CFD model was built and run replicating the same transient scenario. The model was then fine-tuned and validated using the experimental data. In this way, having a reliable predictive method, it was also possible to simulate the natural convective flow and its related thermal field when modifications are introduced in the ventilation ducts design, as well as for other gas turbine models.

Presenting Author: Stefano Minotti Baker Hughes

Presenting Author Biography: MSc degree in Mechanical Engineering and PhD in Energy Engineering at Sapienza University of Rome.
From 2011 to 2017 Design Engineer for gas turbine auxiliary systems in Baker Hughes (former Ge Oil&Gas).
From 2017 to 2020 Design Engineer for CFD analyses of ventilation systems in Baker Hughes.
From 2020 Senior Engineer and from 2022 Principal Engineer for CFD and ventilation systems in Baker Hughes.

Authors:

Antonio Asti Baker Hughes
Federico Crugnola Baker Hughes
Elena De Leo Baker Hughes
Gabriele Lucherini Baker Hughes
Stefano Minotti Baker Hughes
Rajnish Kumar Singh Adarsh Solutions