Systems and methods for on-line pigging and spalling of coker furnace outlets

A method for on-line pigging in a tube coil for a furnace in a delayed coking system, which comprises:

• terminating a process fluid supply flow to the furnace;
• introducing high pressurized steam from a first pressurized steam source through the tube coil and a main line, and from a second pressurized steam source through a second line connected to the main line;
• isolating a vent, in fluid communication with the second line, from the main line by introducing high pressurized steam from a third pressurized steam source through the second line to maintain a constant pressure against one side of first and second closed valves positioned in fluid communication with the vent between the vent and the main line while introducing the high pressurized steam from the first pressurized steam source and the second pressurized steam source;
• terminating the introduction of the high pressurized steam from the first pressurized steam source, the second pressurized steam source and the third pressurized steam source;
• isolating a drum input line, in fluid communication with the main line, from a portion of the main line by introducing high pressurized steam from a fourth pressurized steam source through a third line connected to the main line to maintain a constant pressure against one side of third, fourth and fifth valves in fluid communication with the drum input line;
• disconnecting the tube coil from the main line and the first pressurized steam source;
• connecting the tube coil to a pigging unit after the main line reaches atmospheric pressure;
• and
• introducing water from a water source to the pigging unit for driving a pig through the tube coil.