C16 Tower Process

• C16 feed from T-450 bottom goes to F-463 (C16 Tower Feed Strainer), then to T-460 between the top and bottom beds.
• A chimney tray with down comers delivers liquid to the feed distributor tray in T-460.
• The feed separates into C16 overhead vapor (product) and C18-C24 bottom liquid.
• T-460 overhead vapor goes to the shell side of E-460 (C16 Tower Condenser) and is cooled by boiler feed water in the tubes; steam condensate goes to the 60 psig Steam Header.
• Condensed vapor is routed to D-460 (C16 Tower Reflux Drum); non-condensable vapor goes to the shell side of E-461 (C16 Tower Vent Condenser) and is cooled by cooling water in the tubes.
• A slip stream of cooled condensed vapor returns to D-460; condensate goes to D-433.
• Cooled overhead gas from D-460 joins non-condensables from E-480 for pressure control and goes to Z-460 (C16 Tower 1st Stage Ejector).
• 100 psig steam pulls a vacuum, routing the cooled overhead gas to the shell side of E-469 (C16 Tower Ejector Interstage Condenser), cooled by cooling water in the tubes.
• Condensate from E-469 goes to D-433; gas goes to Z-461 (C16 Tower 2nd Stage Ejector).
• 100 psig steam pulls a vacuum, routing the gas to E-480.
• Liquid from D-460 goes to F-460 (C16 Tower Reflux Strainer) by P-460A/B (C16 Reflux & Product Pumps) and returns to T-460 as reflux.
• P-460A/B also routes liquid to the shell side of E-462 (C16 Product Cooler), cooled by cooling water in the tubes.
• The cooled C16 product is routed to TK-1816/TK-18/TK-33/TK-34 (C16 Product Tanks).
• Off-spec C16 goes to Unit 1791 Heavy Rerun or TK-800.
• T-460 bottom liquid goes to the shell side of E-465 (C16 Tower Reboiler), heated by Dowtherm in the tubes.
• Overhead vapor from E-465 returns to T-460 for temperature control.
• Liquid from E-465 goes via P-465A/B (C16 Tower Bottoms Pump) to T-470 (C18 Tower) as feed.

Equipment Details

• Details are provided about the size, shape, internals, and features of each piece of equipment.
• Knowing the equipment size is not required, this is for understanding relative sizes in the field.

F-463 (C16 Tower Feed Strainer)

• Purpose: Removes particulate matter from the T-460 feed.

T-460 (C16 Tower)

• Dimensions: 4’6”D x 81’4”L
• Function: Separates C16-C24 into a C16 overhead product; the remaining bottoms are a C18-C24 blend used as feed for T-470.
• Key Control Objectives:
• Maintain C18 concentration in the overhead product within specification.
• Maintain C16 concentration in the bottoms within specification.
• Feed enters the side of the tower: C16 exits the top, and C18-C24 exits the bottom.

E-460 (C16 Tower Condenser)

• Type: Shell and tube exchanger.
• Function: Cools and condenses overhead vapor from T-460 on the shell side using boiler feed water on the tube side.
• Purpose: Condense overhead for reflux in T-460 or as C16 product for storage.

D-460 (C16 Tower Reflux Drum)

• Dimensions: 3’6”D x 8’L
• Function: Separates liquid for reflux to T-460 and C16 product for storage from non-condensable vapor.

E-461 (C16 Tower Vent Condenser)

• Type: Shell and tube exchanger.
• Function: Cools and condenses overhead vapor from D-460 on the shell side using cooling water on the tube side.
• Purpose: Condense overhead to be used as reflux on T-460.

Z-460 (C16 Tower 1st Stage Ejector)

• Function: First stage ejector to lower the pressure of T-460 overhead.

E-469 (C16 Tower Ejector Interstage Condenser)

• Type: Shell and tube exchanger.
• Function: Cools and condenses steam from Z-460 on the shell side using cooling water on the tube side.

Z-461 (C16 Tower 2nd Stage Ejector)

• Function: Second stage ejector to further lower the pressure of T-460 overhead.

F-460 (C16 Tower Reflux Strainer)

• Purpose: Installed to remove any particulate matter.

P-460A/B (C16 Reflux & Product Pumps)

• Type: Single-stage centrifugal pumps.
• Motor: 15 HP, 3550 RPM, horizontally-mounted, induction electric motors
• Function: Circulate reflux to T-460 and route C16 product to Unit 1791 or off-spec C16 to Heavy Run or TK-800 Rerun.

E-462 (C16 Product Cooler)

• Type: Shell and tube exchanger.
• Function: Cools C16 product on the shell side using cooling water on the tube side before it is routed to storage.

E-465 (C16 Tower Reboiler)

• Type: Kettle-type reboiler.
• Function: Heats T-460 bottoms on the shell side using Dowtherm on the tube side.
• Kettle Shape: Provides internal space for vapor expansion.
• Purpose: Boil bottoms into a vapor; vapor exits the top nozzle, and remaining liquid exits the bottom nozzle.

P-465A/B (C16 Tower Bottoms Pump)

• Type: Single-stage centrifugal pumps.
• Motor: 7.5 HP, 3500 RPM, horizontally-mounted, induction electric motors.
• Function: Route liquid bottom from T-460 to T-470.