Assessment of the effectiveness of ventilation for gas turbine generator set safety

Abstract

Increasing global warming problems appeal to the employment of clean power generation machineries such as gas turbines. Gas turbine is gas-fired engine which is usually enclosed in an acoustic enclosure for higher reliability and lower operating noise. However, it may face the risk of fuel gas accumulation inside the package which can be extremely dangerous. For the safety of a gas turbine generator set, proper ventilation system is crucial to prevent it from danger by diluting the potential leaked gas. Inspired by the significance of ventilation, this paper aims to present and propose study for the assessment of the effectiveness of ventilation for gas turbine packages in worst-case gas leak. A 2 MW ZK2000 gas turbine was chosen for the study. Method of assessment was introduced and numerical studies by Computational Fluid Dynamics (CFD) were adopted, including both transient and steady state analysis. Aiming to figure out the conditions for worst-case gas leak, the location of leak that may cause the most dangerous gas accumulation was obtained by identifying the poorly ventilated regions within the enclosure. After that, the leak rate was estimated that just to trigger the gas detector at the ventilation outlet according to ISO 21789. Worst-case gas leak simulations were performed in cold engine situation because of the possibility analysis of gas leak. The results at standard conditions show great compliance with the limited value in the code thus indicates that the capability of the current ventilation design. Effect of dilution was studied with various ambient temperatures and ventilation flow rates. One of the key findings is that the flow uniformity has the major impact on enhancing dilution of gas cloud. Structures improvements within enclosure and operation instructions were suggested for the safety of gas turbine unit in the event of gas leak.