B&W/Purge/Blowdown Power lab

What is the normal operating pressure of the B&W boiler?

150 PSI

At what PSI does the first safety valve pop?

170 PSI (1132 KPa)

At what PSI does the second safety valve pop?

At 190 PSI (1310 KPa)

What are the 4 safety limit permissives on the B&W boiler?

FD damper open (FDDO), Flue gas recirculation damper (FGR), Low fire gas switch, and Purge Air Flow (PAF)

What is the trip value for the 3M operating steam limit interlock, and what happens?

trip value is 157 PSI. Prevents overpressure. boiler restarts once boiler pressure returns back to 147 PSI

What is the trip value of the high limit steam pressure 2M transmitter and what happens?

Trips at 164 PSI. Secondary protection to overpressure. Trips the boiler fuel safety shut off valves at 164 PSI if first 3M transmitter fails. 

At approximately how much water in the gauge glass do the Low water fuel cut out (primary) and the auxiliary low water fuel start up at?

1” in gauge glass

What is the trip value for the Low instrument air pressure?

80 PSI

What temperature do the cooling water valves make the water when doing a blow down procedure?

65 degree celcius when entering building drainage system

At what level should the gauge glass be at before doing a blow down procedure?

just below half glass

What order do you open the valves on the back of the boiler before doing a bottom blow down?

Open the inner slow opening valve, then slowly open outer slow opening valve

What order do you close the valves behind the boiler when doing a blow down?

Close the outer slow opening valve first, then close the inner slow opening valve second THEN check drum water level

Why should you never blow down the boiler when steam load is in a state of change?

Blow down will effect your water level due to swell and shrinkage

What is the purpose for boiler pressurizing?

To increase the pressure in the boiler after initial start up in preparation for putting the boiler in service

What is the first step when boiler pressurizing?

Drum the air vent, which should still be open

How much should the drum water level be in the boiler while doing boiler pressurizing?

Should be at normal level (just below half glass) or lower

How much should water temperature increase by per hour while doing a boiler pressurization?

Rate of steam pressure increase. The water temperature should increase by no more than 60 celcius per hour

At what boiler pressure do you throttle the drum vent valve when pressurizing the boiler?

When pressure reaches 3 PSI (20 KPa) and steam is visibly exiting the vent piping at the floor drain

At what pressure do you close the drum vent valve when boiler pressurizing?

20 PSI (140 KPa)

What’s the purpose of a manual purge on the B&W boiler?

To blow air through the furnace and flue gas lines to remove any unburned gases.

What happens if unburned fuel is still in the boiler/flue gas lines upon start up and it’s not purged out?

If can ignite and cause an explosion

How do you manual purge the B&W boiler?

Make sure interlocks and limit switches are satisfied. Leave gas valves closed. Verify the burner louvres are open. Press start. then once high purge is complete click STOP. Programmer will post purge and shut down. Boiler can now be prepared for normal start up.

What pressure is the B&W boiler designed to run at?

250 PSIG (1724 KPa)

What are the steam drum internals?

A feedwater pipe, an open ended continuous blow down line, a chemical feed line, and steam separators

What are the mud drum components?

steam heating coil with safety valve and steam trap, blow down line and 2 blow down valves, and a drain valve at the front which must be locked closed during operation

What is the pressure of gas at the inlet?

9.5 PSI (66 KPa)

What is the pressure of gas going to the pilot?

1 PSI (6.895 KPa)

What is 3 element feed water control

Drum level, steam flow and feedwater flow

What controllers, as well as values of them should be set to manual when starting B&W boiler

Boiler master, and Plant master (drum pressure or header 2) both must have output of 10%

What is the purpose of a blowdown on the B&W boiler?

Intermittently and safely blow down the boiler for removal of sludge and sediment

What level should gauge glass be before starting the boiler?

At least 2 inches above the bottom of the gauge glass

What order do you blow down the boiler when starting up for operation?

Water column first, then gauge glass to prove level

Why must lower drum heating coil be isolated prior to boiler start up?

May adversely affect boiler water circulation and result in tube failures

How do the high pressure steam headers (1 and 2) work?

They receive steam (input) from B&W boiler to then distribute (output) the steam to areas which require high pressure steam or low pressure steam after going through a pressure reducing valve.

What’s the purpose of the orifice place in the steam line?

Measures the steam flow

What pressure must the steam be reduced to going from the high pressure header to the low pressure header?

must go down to 100 KPa

How does the steam control valve lower the steam pressure?

It is a pneumatically powered, remote operated automated steam control valve

What is the typical downstream setpoint used in lab?

around 70 KPa

What kind of valves are the upstream and downstream isolation valves?

Both gate valves

What kind of valve is the manual bypass valve for the pressure reducing station?

Globe Valve

What is the downstream pressure relief valve set at for low pressure downstream overpressure protection?

100 KPa

What kind of valve is the downstream manual control valve?

Butterfly Valve