Altering product output with innovative process
enhancements
Faced with the loss of a fuel gas contract, CITGO was forced into a hard choice -
make less fuel gas or reduce overall refinery throughput. CITGO has
an excellent safety program and emphasises safe and reliable
projects. Aggreko's engineering operation produced a comprehensive
process design for each of the two projects.
Aggreko's solution: temperature control rental
Aggreko approached the refiner with solutions to reduce fuel gas
generation. A review of the process units showed that if
intermediate steam temperatures were reduced, more unsaturated gas
would be absorbed, reducing gas flow to the fuel gas section of the
plant.
Aggreko's recommended temperature control scheme (water-cooled version)
and the process and economic logic for this solution was based on
the quantity of gasoline to be cooled and the enthalpy to be
removed. The gasoline inlet temperature is low enough to achieve
the desired heat removal in one exchanger. The mechanical chiller
was cooled by water; Aggreko supplied a dedicated portable cooling
tower.
Two process points were identified: a mechanical chiller for API
51° gasoline; and a heat exchanger for cooling naphtha-range lean
oil. CITGO accepted the solutions and embarked on a fast-track
program to install them. From the initial point of discussion to
project start-up took approximately six weeks.
Process design
The documentation permitted the refiner to carefully analyse the
project for performance, safety and reliability. This documentation
also facilitated a smooth and trouble-free installation and
start-up.
The saturates plant process engineer reported an observation
that fuel gas in his unit had been reduced by 500,000 scf/d. This
is equivalent to about 340 barrels per day. The cost to benefit
ratio was 6.8 to 1.