In the high temperature working condition, there is a working condition with thick dust interference. It is recommended to use high frequency 120GHz, continuous frequency modulation wave FMCW, convex lens antenna radar level gauge. For high temperature conditions, it is recommended to use a high temperature isolation device. With nitrogen cooling interface, the maximum temperature resistance is 1200°C. Moreover, the radar level gauge is completely isolated from the inside of the tank, making inspection and maintenance safer.