TDBFP Rolling

What happens in case any Protection acts

• On actuation of any of the TDBFP Protection, the drain solenoids get energize. They disconnect the Governing (Control) oil from the Main circuit
• The Trip device gets operated, draining the Trip oil of the Circuit. Thus ESV and MCV,ACV get close immediately

TDBFP Rolling

1. Before rolling, ensure TDBFP is charged through all of the sub-systems: Oil, Feed water, Seal steam/ Vacuum and Steam side
2. The rolling of TDBFP Shall have the following steps: 

• Reseting the Turbine
• Reseting Trip device
• Reseting & Opening Stop valve 
• Rolling to 1500 rpm
• Rolling to 3000 rpm and further loading

Following sequential events occur:

• Solenoids SOV 2220, SOV 2221 get energize
• On SOV 2220 energizing, the oil below piston shall get connected to drain; Energizing of SOV 2221 shall develop start up oil pr (should be > 5.5 ksc) above piston by which  the spring and cone assembly shall get latch
• Solenoids SOV 2220, SOV 2221 de-energize
• On De- energizing of SOV 2221, the oil above piston shall get connected to drain; De-Energizing of SOV 2220 shall allow trip oil (should be > 4.5 ksc) flow below the piston and ESV shall open
• If sufficient Start up oil & Trip oil pressures are not developed, take second LOP into service and stop it after ESV gets open
• Nr BFP Ctrl shall increase which shall be followed by MCV opening and actual Speed rise of BFP
• Observe for Turning gear valve closing and JOP Auto cut-off
• At 1500 rpm, Start up vent shall close in Auto
• Wait for Turbine casing temperature to reach at least 100 deg C to proceed further
• Now, Set speed reference to 3000 rpm
• Close casing drains.
• The rpm can further be raised to the value (either by typing the value or by pressing UP arrows) at which it starts taking load.
• The Recirculation valve shall get close in Auto if flow across BFP crosses 550T/hr. At that time, open the Recirculation valve of the other BFP which has to be stopped
• Load further and put TDBFP into Auto. If two TDBFP are in service, ensure both rpm are near to each other for smooth load sharing and drum level- control
•  For putting into Auto, open L/R Pop-up and press Remote