black liquor recovery boilers
TRANSCRIPT
Integral Valve InterlocksApplication Data Sheet
Black Liquor Recovery Boilers
In the paper and pulp industries, black liquor recovery boilers are used to burn the black liquor from the processing plant to provide additional steam and to recover sodium salt from the liquor. If conducted improperly, this process could result in a reaction between water and sodium salt, low solid liquors, or the uncontrolled ignition of unburned fuel and gases which could cause a furnace explosion. Due to the complexity and high risks of this process, careful control of the operations are required to ensure safety.
To minimize the possibility of an explosion, the control of the black liquor injection guns and the flow of the black liquor through the indirect liquor heater or washout procedures are synchronized by using the KIRK Eagle Series valve interlocks and access interlocks.
A typical black liquor recovery process using a KIRK® trapped key interlock system is detailed on the reverse of this page.
www.kirkkey.comProcess safety Control
Indu
stri
esPulp
Paper
Kraft
Multi-Turn Valve Interlock
Type DM Access Interlock and Latch Bolt
Quarter-Turn Valve Interlock
INITIAL SYSTEM STATUS: i) Liquor gun ports are all locked closed – Key A is trapped in the switch / solenoid unit.ii) Liquor supply / washout system – Supply Valves V1, V2, V4 & V5 are locked open.
Bleed Valves V3 & V6 are locked closed. Washout connections isolated and spool pieces removed. Key B trapped in the switch lock.
Interlocking Logic
Operation
Integral Valve interlocksApplication Data Sheet
Interlocking Sequences can be designed to suit any operational or Process Requirements
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Black Liquor Recovery Boilers
SYSTEM OPERATION: To Operate Black Liquor Guns 1) The operator is given a Permit to Work (PtW)
and a permissive is given from Control to operate the switch / solenoid and release Key A.
2) Key A is then entered into any one of the Recovery Boiler Gun Ports to allow black liquor to be supplied to furnace. Note: If more than one port is to be used at anytime, a Key exchange box will be included in the system.
3) On completion of firing black liquor, reverse the process to obtain Key A and enter into the switch / solenoid key release unit to signal to Control that all liquor guns are out of furnace.
SYSTEM OPERATION: To Preform Water Washout Procedure 1) The operator is given a Permit to Work (PtW)
and a permissive is given from Control to operate the switch / pump to OFF position and release Key B.
2) The operator enters Key B into supply valve V1 to unlock and allow valve to be closed. Lock valve open by removing Key C.
3) The operator continues in sequence through the supply and bleed valves using the keys to open or close them until Key G is released. The liquor supply is now isolated for water washout.
4) The spool pieces are now inserted in the wash connection pipelines and the isolation valves opened to allow washing to proceed. Note: The spool pieces and associated wash valves may also be part of the interlock system depending on plant requirements.
5) When washout is completed, reverse the procedure and enter Key B into the switch / pump and turn pump ON.
LegendDual Key Valve Locked Open
Dual Key Valve Locked Closed
Key Free Key Trapped
The interlocking logic shown illustrates a typical black liquor arrangement with washout connections. Note: The operating details given below should be read in conjunction with the logic diagram above.
DE
C B C D
GH
E F F G
A A A A
AON
OFF
BON
OFF
Liquor to Boiler
Spool Pieces RemovedMay Also be interlocked
Wash Connections
Valve V1 Valve V2 Valve V4 Valve V5
IndirectHeater
Recovery Boiler Gun PortsNumber of Ports Dependent on Boiler Design
Bleed Valve V3
Pump
Bleed Valve V6
Key SwitchPump Control
Key Switch / SolenoidKey Release Unit
FiringAccess Door
FiringAccess Door
FiringAccess Door
FiringAccess Door