Boiler Non-Return Valve
Boiler Non-Return Valve
(OP)
What is the function of a boiler non-return valve? Is it, as the name implies, a check valve that prevents backflow into the steam drum?
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RE: Boiler Non-Return Valve
In many boiler application this the valve is an angle globe type and is positioned on top of the boiler in the outlet line.
RE: Boiler Non-Return Valve
RE: Boiler Non-Return Valve
The purpose of the non-return was two-fold. Under the interpretation that it is a combined stop-check valve, then it can be used as one of 2 required stop valves that will prevent steam ingress into a steam drum while a maintainence person is inside the drum of an idle boiler, so he doesn't get cooked. The check valve works even if the control system is fouled up and inadvertantly opens a stop valve .
The second reason is to enable startup of a second boiler after the main steam lead is already pressurized. For a drum type boiler to startup and fire at more than a 10% firing rate, it is neccesary that the water in the waterwalls not be excessively "subcooled", that is , the waterwall fluid temp must be close to the saturation temperature associated with the current drum pressure. If teh drum pressure were artificailly raised due to a lack of a closed steam valve, then the water would not boil when a high heat flux is experienced and would lead to tube overheat. Proper startups require an outlet steam valve to be closed and a drum vent opened to ensure the drum pressure is as close to the saturation pressure that is adssocaited with the restart waterwall fluid temperature. This is automatically assured if a nonreturn valve is supplied.
RE: Boiler Non-Return Valve
Thanks,