Altering product output with innovative process
enhancements
The challenge to the customer
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 emphasizes safe and reliable projects. Aggreko's
engineering operation produced a comprehensive process design for
each of the two projects.
Aggreko's solution
Aggreko approached the refiner with solutions to reduce fuel gas
generation. A review of the process units showed that if
intermediate stream temperatures were reduced, more unsaturated gas
would be absorbed, reducing gas flow to the fuel gas section of the
plant.
Aggreko's recommended 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.
The benefits to the customer
The documentation permitted the
refiner to carefully analyze 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.