Boiler Equpement Interlock And Logic

Bagasse and Coal base Travailing grate boiler

  ID Fan Start / Stop 

 

   ID fan shall be started from DCS if following Preconditions are fulfilled. 

1. If DCS mode (remote) selected. 
2. No ID fan stop command 
3. Furnace pressure no very low  

• If VFD mode is selected, ID fan start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the ID fan running feedback signal is received by DCS then ID fan start signal gets latched & fan is running.

•  Incase of selection of  'SOFT STARTER' mode inlet damper shall be fully closed to enable starting. Once 'RUNNING' feedback is obtained the inlet damper can be opened.

  
  

  FD  FAN Start / Stop

  
  
  

  
  

  FD fan shall be started from DCS if following Preconditions are fulfilled. 

  1. DCS mode (remote) selected.
  2. Furnace pressure not very high. 
  3. Drum level not very low. 
  4. ID fan running condition. 
  5. No FD fan stop command.
   
• If VFD mode is selected To start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the FD fan running feedback signal is received by DCS then FD fan start signal gets latched & fan is running. 
•   If Soft Starter mode is selected the inlet damper shall be fully closed to enable starting. Once 'FAN RUNNING' feedback is obtained damper can be opened.

 

 

SA Fan Start / Stop

  SA fan shall be started from DCS if following Preconditions are fulfilled.

1. DCS mode (remote) selected.
2. Drum level not very low. 
3. ID fan running condition.
4. FD fan running condition.
5. No SA fan stop command. 

• If VFD mode is selected To start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the SA fan running feedback signal is received by DCS then SA fan start signal gets latched & fan is running. 
•   If Soft Starter mode is selected the inlet damper shall be fully closed to enable starting. Once 'FAN RUNNING' feedback is obtained damper can be opened.

 

Screw (Fuel) Feeder Start / Stop

The bagasse screw  feeder can be started from DCS if following Preconditions are fulfilled. 

1. SA fan is on mode. 
2. DCS mode selected from MCC. 
3. No screw feeder stop command. 

Then, 

screw feeder start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the 'Screw Feeder' running feedback signal is received by DCS then Screw feeder start signal gets latched & feeder is running.

 

 

Drum (Fuel) Feeder Start / Stop

The bagasse Drum feeder can be started from DCS if following Preconditions are fulfilled.

1. DCS mode (remote) selected.
2. ID fan running condition.
3. FD fan running condition.
4. SA fan running condition. 
5. Corresponding screw feeder running.
6. Drum level not very low   
7. No Drum feeder stop command. 

 

Then, 

Drum feeder start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the 'Drum Feeder' running feedback signal is received by DCS then Drum feeder start signal gets latched & feeder is running.

 

 

 Coal Spreader Start / Stop

The Coal Spreader can be started from DCS if following Preconditions are fulfilled.

1. DCS mode selected from MCC. 
2. No Coal spreader stop command.

 Then, 

Coal Spreader start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the 'Coal Spreader' running feedback signal is received by DCS then Coal Spreader start signal gets latched & feeder is running.

Coal Feeder Start / Stop

The Coal Feeder can be started from DCS if following Preconditions are fulfilled.

 

1. DCS mode (remote) selected.
2. ID fan running condition.
3. FD fan running condition.
4. SA fan running condition. 
5. Corresponding Coal Spreader running.
6. Drum level not very low   
7. No Coal feeder stop command. 

Then, 

Coal Feeder start signal is initiated in DCS as a 5sec pulse. Within the 5sec if the 'Coal Feeder' running feedback signal is received by DCS then Coal Feeder start signal gets latched & feeder is running.

Boiler Feed Water Pump (BFP) Start / Stop

The Boiler Feed water Pump (BFP) shall be started from DCS if following Preconditions are fulfilled.

1. DCS selected. 
2. Deareator level not low. 
3. No stop command. 

Then, 

BFP start is initiated in DCS as a 5sec pulse. Within the 5sec if the 'BFP' running feedback signal is received by DCS then BFP start signal gets latched & the pump is running.

Main Steam Stop Valve (MSSV) Open

Main Steam Stop valve can be opened if following Preconditions are fulfilled.

1. MSSV remote selected. 
2. MSSV bypass valve is open. 
3. MSSV not fully open. 
4. No MSSV close command present. 

If the above conditions are fulfilled MSSV 'OPEN' signal is initiated in DCS as a 2sec if 'MSSV OPENING' feedback is obtaned from MCC, MSSV 'OPEN' signal is latched. MSSV opens and when it is fully open, through 'MSSV OPEN' contact from MCC stops 'MSSV OPEN' command. 

Main Steam Stop Valve (MSSV) Close

Main Steam Stop valve can be Closed if following Preconditions are fulfilled.

1. MSSV remote selected. 
2. MSSV not fully closed. 
3. No MSSV open command present. 

If the above conditions are fulfilled MSSV 'CLOSE' signal is initiated in DCS as a 2sec pulse. Within 2 sec if 'MSSV CLOSING' feedback is obtaned from MCC, MSSV 'CLOSE' signal is latched. MSSV Closes and when it is fully closed, through 'MSSV CLOSED' contact from MCC stops 'MSSV CLOSE' command. 

 

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