Capacity Enhancement of Naphtha Splitter Reboiler Service
Furnace Improvements (FIS) was employed by a Southern refinery in Indiana to carry out a capacity enhancement study of Naphtha Splitter Reboiler service. The operating heat duty of the service was around 11.74 MMBtu/hr. This was supplied by Naphtha Splitter Reboiler Heater and by Platformer Heater Convection coil. Client wanted to increase the Naphtha Splitter Reboiler service heat duty by 5 MMBtu/hr to achieve total duty target of 13.7 MMBtu/hr.
FIS reviewed the design and operating data of Naphtha Splitter Reboiler heater (900-H-1) and modeled the heater operation. The heater was running at a very high heat release rate. Any heat duty increase in this heater was not viable. Burner used in this heater required frequent maintenance, client wanted to replace this burner.
FIS also reviewed the design and operating data of Platformer Heater (300-H1/H2/H3). In this heater, there are 3 radiant cells and a common convection section. The Convection section had #1 Inter Heater preheat coil, followed by Naphtha Stripper coil. It was possible to shift part of the #1 Inter Heater convection duty to the radiant cell of the heater. This way part of this convection coil could be used to provide heat duty for Naphtha Splitter service. This required an increase in the firing rate of the Inter Heater cell and in turn, new burners of higher capacity.
The client had an Old Platformer Charge Heater (900-HXX) which was built in 1956, later abandoned in 1990. The inspection of the Old Platformer Charge Heater from outside portrayed that it was in good condition. FIS proposed using this heater to provide the required heat duty requirement for Naphtha Splitter Reboiler service. FIS proposed three revamp options:
Option 1: Reconfiguring the convection of Platformer heater (300-H1/H2/H3)
Option 2: Old Platformer heater with all convection heater
Option 3: Old Platformer heater with new radiant tubes, burners and convection section
Client selected Option 3, being the most cost-effective option and following modifications were adopted:
New convection section
Radiant section tubes were removed, and new tubes, hangers were installed
Radiant section and radiant floor refractory were replaced
The existing stack was reused
New burners were installed
Existing Naphtha Stripper Reboiler Heater (900-H-1) was abandoned
The revamped design has following advantages:
The duty of the heater increased by 139%
Volumetric heat release of the heater is alleviated significantly
Efficiency of the heater increased by 8.2%
