Dowtherm System and Heater (H-530)

• The Dowtherm System is a closed-loop system that supplies heat to exchangers.
• This system is especially useful when steam is impractical due to high temperature requirements.
• Kettle-type reboilers, which supply heat to many towers, primarily use Dowtherm.
• Boiler feed water is heated in the convection section of the heater to increase efficiency.

H-530 (Dowtherm Heater)

• H-530 is fired using natural gas from Unit 1092, purge gas from Unit 1797, and purge gas from Unit 1798.
• Cooled Dowtherm is routed by P-530A/B (Dowtherm Circulation Pumps) to the convection section of H-530 for preheating.
• From there, it routes internally to the radiant section for superheating.
• The superheated Dowtherm is then supplied to: E-385, E-405, E-435, E-436, E-445, E-455, E-465, E-475, and E-760.
• After heat transfer, the cooled Dowtherm returns to H-530 via P-530A/B to repeat the process.
• Furnaces/heaters are complex systems that require frequent monitoring to maintain the balance between fuel, air, and temperature.
• Monitoring and adjustment is vital for safe, stable, and efficient operation.

D-545 (Dowtherm Drain Drum)

• Each user has a drain line to D-545 (Dowtherm Drain Drum).
• D-545 has dimensions of 4’6”D x 8’L.
• D-545 collects Dowtherm when a user is emptied and Dowtherm enters the top and exits the bottom of the drum.

E-545 (Dowtherm Drain Plate Coil)

• E-545 (Dowtherm Drain Drum Plate Coil) maintains the temperature of the Dowtherm in D-545 using 60 psig steam.
• Steam condensate from E-545 is routed to the 60 psig Steam Condensate Header.

P-545 (Dowtherm Drain Drum Pump)

• P-545 is a single-stage centrifugal pump driven by a 10 HP 3560 RPM horizontally-mounted induction electric motor.
• P-545 routes Dowtherm from the bottom of D-545 to D-530 (Dowtherm Surge Drum).

D-530 (Dowtherm Surge Drum)

• D-530 has dimensions of 10’D x 30’L.
• It ensures a constant feed of Dowtherm to the unit.
• Dowtherm enters the top of the drum, exits the bottom, and vapor vents from the top.
• Spent Dowtherm is loaded, and fresh Dowtherm is unloaded, using a tank truck via the outlet line of D-545 to the suction line of P-545.

E-530 (Dowtherm Surge Drum Plate Coil)

• E-530 maintains the temperature of the Dowtherm inside D-530 using 60 psig steam.
• The steam condensate from E-530 goes to the 60 psig Steam Condensate Header.

E-535 (Dowtherm Surge Drum Vent Condenser)

• The overhead of D-530 is routed to the shell side of E-535 (Dowtherm Surge Drum Vent Condenser).
• E-535 is cooled with cooling water on the tube side.
• Nitrogen is used to purge the condensed liquid to the LP Flare Header.
• The bottom of D-530 merges with the Dowtherm return to the suction of P-530A/B to repeat the process.

P-530 A/B (Dowtherm Circulation Drum Pumps)

• P-530 A/B are single-stage centrifugal pumps.
• They are driven by 200 HP 1750 RPM horizontally-mounted induction electric motors.
• They route Dowtherm from D-530 and the Dowtherm return header to H-530.

D-531 (Vent Header K.O. Drum)

• D-531 has dimensions of 1’6”D x 8’6”L and receives vent gas before it goes to the LP Flare.
• Vent gas enters and exits the side of the drum.
• Non-condensable vapor from the vent header is routed to D-531.

Z-532 (D-531 Vent Gas Ejector)

• Z-532 lowers the pressure of vent gas from D-531 to the LP Flare.
• Non-condensable vapor from D-531 is purged to the LP Flare using nitrogen via Z-532 (D-531 Vent Gas Ejector).