Steam boilers are gas powered both for direct electricity generation, up to 660MW of power, and for auxiliary services, in the range of 35-70 MW of power.
The valves are positioned in front of the boiler, and are installed on gas and air inlets for boiler feeding. They perform the function of Emergency shut down, closing with perfect tightening and short time the line in case of emergency and blocking the flow of fuel and comburent.
The specific configuration designed for these valves is a double block and bleed assembly, consisting of two emergency shut down (ESD) valves and a blowdown (BDV) valve in the middle for venting. This design allows the closing of the two main valves and the opening of the blowdown valve, which allows gas/air left inside the system to be flowed to a dedicated line. In case of emergency, these two mechanisms are activated simultaneously for a very high safety level.
This type of valve is covered by ATEX and SIL 3 certifications, and are featured by both single-acting pneumatic actuators and command/control accessories, such as solenoid valves, limit switch boxes, regulating filters, quick exhaust…
Typically these are A64 and A60 floating valves or T2 and T3 trunnion mounted with ANSI 150/300 rating size diameters from DN 15 (Ø ½”) to DN 300 (Ø 12”).