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Vacuum breaker valve
- Thread starter Kash2013
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TugboatEng
Marine/Ocean
Steam turbines and condensers should not have a vacuum breaker valve.
There may be a sentinel valve on the LP turbine. That is supplied by the turbine manufacturer.
There may be a sentinel valve on the LP turbine. That is supplied by the turbine manufacturer.
Vacuum breaking is used on large steam turbine-generators to minimize damage to the turbine-generator under certain emergency shutdown conditions. Please see the excerpt below from Westinghouse Steam Information Manual, CT-24035, August 1983, Revision 0.
“Vacuum should be broken immediately after a unit is tripped and in free coast-down if any condition exists where possible damage to the unit can be reduced by shortening coast-down time. Examples of incidents requiring vacuum to be broken immediately after a trip include, but are not restricted to: loss of AC power, loss of DC power, low bearing oil pressure, loss of lubricating oil, loss of cooling water to turbine oil coolers, thrust bearing trip, water in the turbine, any indication of rubbing between rotating and stationary parts, or excessive vibration on coast-down.”
Please note that for some large steam turbine-generator units, coast-down time with vacuum maintained can exceed 90 minutes.
The turbine manufacturer must provide requirements for the selection (sizing criteria) for the vacuum breaker valve(s). The turbine manufacturer must also provide the internal volume of the turbine downstream of the reheat inlet valves. The condenser manufacturer must provide the volume of the vacuum space in the condenser.
As for supply of the vacuum breaker valves, either the turbine manufacturer or the condenser manufacturer may supply the valves.
Best of luck!
“Vacuum should be broken immediately after a unit is tripped and in free coast-down if any condition exists where possible damage to the unit can be reduced by shortening coast-down time. Examples of incidents requiring vacuum to be broken immediately after a trip include, but are not restricted to: loss of AC power, loss of DC power, low bearing oil pressure, loss of lubricating oil, loss of cooling water to turbine oil coolers, thrust bearing trip, water in the turbine, any indication of rubbing between rotating and stationary parts, or excessive vibration on coast-down.”
Please note that for some large steam turbine-generator units, coast-down time with vacuum maintained can exceed 90 minutes.
The turbine manufacturer must provide requirements for the selection (sizing criteria) for the vacuum breaker valve(s). The turbine manufacturer must also provide the internal volume of the turbine downstream of the reheat inlet valves. The condenser manufacturer must provide the volume of the vacuum space in the condenser.
As for supply of the vacuum breaker valves, either the turbine manufacturer or the condenser manufacturer may supply the valves.
Best of luck!
TugboatEng
Marine/Ocean
My experience was limited to marine turbines. In that case there is an astern turbine which can be used for shaft bursting in the event of a fault.
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