Development of an air cooled borescope for infrared thermal load monitoring in industrial gas turbine combustors and operational experience

Abstract

Within the last three years, Kawasaki Heavy Industries Ltd. and B&B-AGEMA have worked on a technology to support experimental tests for development of the Micromix combustor of pure hydrogen, allowing a very close online visual (Visible and Infrared light) access to the burner. The invented borescope has been designed by means of Conjugate Heat Transfer (CHT) and Finite Element (FE) simulations. Different design variations have been tested numerically. Within this course, the internal cooling pathways have been improved and the structure enhanced to ensure an acceptable life time of the highly loaded borescope head located directly downstream of the flame. Here, the local temperature reaches values around 1600 K. After digital development and manufacturing, the first borescope prototype could have been successfully operated in two low pressure and two high pressure tests (two times with a visible light (VIS) and two times with an Infrared (IR) camera). In the paper, the development process as well as the operational experience and the experimental test results are presented. The information on the Micromix combustor behavior revealed by the borescope technology help to better understand the behavior of the combustor, improve the design and plan the operation strategy within the real gas turbine.