A Naphtha Minus Complex was constructed as an addition to the Shell Haven refinery in Essex , United Kingdom . The complex was built to enhance the refinery’s ability to produce unleaded gasoline and to upgrade the quality of gasoline and lighter fractions produced by the refinery.
The complex was a “fast-track” project, so we utilized modular construction techniques to accelerate the schedule. The project consisted of eight pipe rack modules, nine process modules, two furnaces, one 25-megawatt gas turbine and waste heat boiler and three reciprocating compressors.
The modules were large, with some weighing up to 600 metric tons. We transported them by barge from the fabrication facility on the Thames Estuary directly to Shell Haven and unloaded them at a specially constructed jetty.
The components we installed included:
Recontracting Unit
The recontracting unit acts as a maximizing and buffer storage unit that reduces process fluctuations to the other units.
Naphtha Hydrotreating Unit
In the naphtha hydrotreating unit, the oil reacts with hydrogen in the presence of a catalyst. Once this occurs, the product then splits into the lighter gas stream, middle fractions and bottom fractions.
Total Isomerization (TIP) Unit
The TIP unit converts the normal pentane and gasoline fractions to isomerate products, which results in a higher octane rating without the addition of lead. The middle cut from the splitter and a further stream from the platform splitter are treated to produce an isomerate product. The lighter byproducts are then removed in the TIP stabilizer, and the bottom product goes to tankage for eventual blending into unleaded gasoline.
LPG Recovery Unit
The light gas stream, consisting mainly of liquefied petroleum gases (LPG), goes to the LPG recovery unit, via the ADIP absorption column, where the hydrogen sulfide is removed. In the LPG recovery unit, each of the individual components is separated and sent to storage for eventual sales or for use in the refinery.
Hot Oil System
In order to provide heat to various streams, the hot oil system combines with various other systems to provide water, fuel gas and steam as necessary throughout the plant.
Cogeneration Unit
The cogeneration unit is a 25-megawatt gas turbine and waste heat boiler unit that produces power and steam for use in the refinery.