Catalytic Feed Hydrotreater Heater Performance Improvement and Low NOx Burners
The refinery had a Catalytic Feed Hydrotreater heater (CFHT) in their Fluid Catalytic Cracking (FCC) unit. It is a natural draft vertical cylindrical furnace, with a horizontal overhead convection section. The convection section had been experiencing tube failures for many years. Furnace Improvements (FIS) was contracted to review the design and operation of the CFHT Heater and requested to provide an improved design of convection section, which will eliminate tube failures in the convection section. Furnace Improvements carried out a thorough analysis of the heater. The existing convection section had a very high heat flux leading to high skin temperatures and subsequent tube failures. FIS designed the new convection section within one week. It not only solved tube failure problems, but also improved its performance. In the revamped convection section:
Radiant section skin temperature was reduced from 740 to 675°F.
Thermal efficiency was improved from 79.5% to 86%.
Stack flue gas temperature was reduced from 764°F to 537°F.
In May 2003, FIS carried out a burner replacement project on the same heater. This (CFHT) had three up fired Natural Draft Burners. These burners had a very high heat release rate, and were leading to long flames and uneven heat distribution. These were replaced with six new low NOx burners. FIS developed the burner specifications and evaluated the vendor quotations as well as witnessed the burner test. FIS also developed a complete detailed engineering and fabrication drawings for this project designing the floor, wind box and dampers.
The heater was successfully commissioned in July 2003.