- What boiler vents and main steam vents should be open when lighting off the boiler for a Hot start? Cold Start?
Hot Start- Dry & wet vents, Radiant Roof Inlet Header drains, final vertical superheat outlet header drains, back pass drains, economizer recirc valve and main steam drains & vents
Cold Start-Vents on penthouse (superheat link vents reheat link vents, & economizer link vents), wet & dry vents, radiant roof inlet header drains, final vertical superheat outlet header drains, back pass drains, economizer recirc valve, main steam drains & vents
- At what temperature can the pre-heaters be shut off when trying to cool the boiler?
400 degrees Fahrenheit
- What are the green light permissives on the I.D. fans?
Precip or bathhouse in service “NAT” indication Breaker racked in Safe/Run in “run” Aux oil pump running Aux air dampers in auto Fluid drive at minimum Shut off damper for ID fan to be started is closed or both dampers closed if you are starting the 1st ID fan FD fan shutoff damper open
- What are the green light permissives on the F.D. fans?
“NAT” indication
Breaker racked in
Safe/Run in “run”
Aux oil pump running
Fluid drive at minimum
Shut off damper closed on fan to be started
Associated ID fan running and proven (white light indication)
- In what position would the fan shut off dampers be if one set of fans tripped out of service? All fans tripped?
If one set of fans tripped the shut off dampers on that set would drive closed and if all fans tripped all shut off dampers would stay open to allowing a natural draft of air through the boiler.
- What would happen to the fans in the event of high furnace pressure? Low furnace pressure? At what pressures will this occur?
High furnace pressure-(+3inwc) there is a block built into the control logic that will prevent the fan speed from decreasing but, will allow fan speed to increase. This will happen in either auto or manual fan control
Low furnace pressure-(-3inwc) there is a block built into the control logic that will prevent the fan speed from increasing but, will allow fan speed to decrease. This will happen in either auto or manual fan control.
- Describe the procedure to put the fans in service.
Observe stack opacity while putting fans in service or when making airflow adjustments during this procedure. Ensure Precip or baghouse is in service, seal on boiler, air preheaters in service, and aux air dampers open and modulating.
ID FANS:
• Ensure green light permissives have been met for ID fan to be put in service
• With fan graphic pulled up, unlock breaker and start ID fan while observing graphic and ensuring you get a “NAC” on motor control station, let fan stabilize
• Open ID fan shutoff damper with control station to 100%, then increase fluid drive output until you get a “fan proven” light • Place ID fan shut off damper control station in “auto” • Establish -.5 to -1.0 inch furnace pressure and put ID fan control station in “auto”
- FD FANS:
- Ensure green light permissives have been met for FD fan to be put in service o • With fan graphic pulled up, unlock breaker and start FD fan while observing graphic and ensuring you get a “NAC” on motor control station, let fan stabilize
- Open FD fan shutoff damper with control station to 100%, then increase fluid drive output until you get a “fan proven” light
- Place FD fan shut off damper control station in “auto”
- Establish 25%-30% airflow and put FD fan control station in “auto”
- Repeat this procedure for the opposite set of fans and ensure that all control stations are in “auto” for both ID and FD fans
- When should the ID fans be put in auto? What should the furnace pressure set point be?
Once ID fans have been proven and furnace draft point of -.5 to -1.5 has been met
- Explain the procedure for shutting down one set of fans with the unit on line.
Reduce load to 150-180 MW
When taking one set of fans out watch opacity, leave chemical pumps I/S on the other side and observe six-minute average before proceeding
Slowly decrease FD fan fluid drive to min
Slowly decrease associated ID fan fluid drive to min watching opacity and baghouse DP
O2 select must be swapped to set of fans in service Trip selected FD fan, watch opacity and ensure shut off damper drives closed
Trip selected ID fan, watch opacity and furnace pressure and ensure shut off damper drives closed
Leave air preheater I/S
- Why does the O2 go high on low loads?
Fuel flow is decreased significantly while minimum air flow permissives must be met
- What would happen to the boiler controls if you were to get furnace pressure normal transmitter failed?
If two of three transmitters fail the boiler controls trip to manual which will put you in turbine follow, when that happens ID, FD, feeder master and boiler master will trip to manual
- What can an operator do If he has unbalanced fans?
Bias the FD fans to balance air flow
- What anticipation signal is used by the furnace pressure controller when in auto?
FD fan air flow tracking
- What is the procedure for blowing out the duct work before starting up?
Baghouse or precipitator I/S
ID and FD fans I/S
Increase air flow to 80% for about 10 min while watching opacity
Return air flow to 30%
- What are the opacity restrictions that an operator has to be aware of?
27% or > for 1 six-minute period
20.5% or > for 2 six-minute periods in same clock hour
- What are the air flow requirements to purge the boiler?
Min of 25% air flow
- What are the air flow requirements before lighting off the boiler?
Min of 25% Air flow and less than 40% air flow.
- How long does the boiler purge timer purge the boiler?
5 minutes
- What permissives have to be met before the purge timer will start timing?
Purge will auto start once the permissives have been met No trips Air flow >25% Aux air dampers modulating Scanners “no flame” All mills off All gas valves closed
- Name the first out indications on the Boiler Status screen.
Low drum level 2 circ. pumps off Turbine valves closed MFT button pressed F.D. fans off I.D. fans off Furnace pressure high Furnace pressure low Air flow low Flame failure Loss of fuel
- What permits must be met before putting in the first elevation of fuel?
Total air flow must be greater than 25% but less than 40%
Tilts at 0°
Purge completed
2 Boiler circ pumps running
At least 3 of 4 igniters proven for that elevation
Igniter fans I/S
Scanner fans I/S
Main gas trip valve open- What is the temperature restriction when firing with the furnace temperature probe in service? Why?
Not to exceed 1000 deg. Fahrenheit during startups.
To protect the reheat tubes from overheating.
- When can the main gas valve be put in auto?
Once FD fan master is in auto
- How would you operate the condensate recirculation valve on Unit #2 you are starting up Unit #2 and using the recovery system?
While monitoring the booster pump suction pressure, open the condensate recirculation valve 25% in manual, this will prevent the system from being robbed of too much flow, this will increase flow to the recovery system.
