Altering product output with innovative process
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
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
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
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.