Again: a valve

This time it's one of the four Sempell safety valves, which prevent feedwater from entering the preheater when a pipe inthe heater cracks.
These valves can be found at unit EC 20.

Better in LARGE...

Bhanu gave me a hint to show not only objects but also the part of the plant where it's located.

Here is a view at where the valves are situated at the so-called "machine floor".