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BP: Modernising for heavier crudes
BP’s refinery in Whiting, Indiana is the company’s most complex refining project undertaken in its recent history and is drawing the largest private sector investment in the US state to date. Located near Lake Michigan, Whiting is undergoing a USD 3.8bn modernisation plan called the Whiting Refinery Modernization Project (WRMP).
The third largest refinery and biggest in-land refinery in the US, Whiting is currently able to process approximately 410,000 barrels per day (bpd) of crude oil into gasoline, diesel, aviation fuel, propane, and 10 per cent of the asphalt used in the US. The facility’s feedstock comes from three different sources: heavy crude from Canada, sweet and sour crude from south-west US domestic sources and mixed grades of foreign and domestic offshore oil. According to BP, at the moment the refinery has a capacity to refine only 20 per cent of heavy crude in its overall energy mix.
The Whiting Refinery Modernisation Project
BP’s WRMP project aims to propel the facility to new heights, making it the “premier refinery in North America,” the company has said. The oil major plans to increase the refinery’s capacity to process Canadian heavy crude from oil sands via the Alberta-Illinois Enbridge pipeline from 20 to 85 per cent.
Improvements include changing the refinery’s process units to handle an extra 260,000 bpd of heavy Canadian crude, more than four times its current capacity. The project will also increase the refinery's ability to process petrol and diesel production by 1.7 million gallons a day or approximately 15 per cent of its annual output.
In order to achieve these goals, several enhancements are required. The refinery’s largest crude distillation unit will be reconfigured to process heavier crude. A new coker is also being built to replace the existing one and enhance process safety through increased automation, petroleum coke production and naphtha output. BP claims this is the world’s second largest delayed coker, with around 102,000 bpd of throughput. Finally, the Whiting refinery will see its existing sulphur recovery capabilities enhanced by a new 105,000 bpd gas oil hydrotreater to remove additional amounts of sulphur from the fuels product streams. In total, BP says 600 kilometres of pipe, 1200 pieces of major equipment, 600 shop-fabricated modules and 50,000 tonnes of steel will be installed.
New crude demands, new cracking technologies
While complex and unique, the core aim of BP’s modernisation project is following in the footsteps of a larger trend within the global oil and gas industry. As heavier crudes become a more prevailing raw material in downstream plays by replacing depleting conventional light crudes, several refiners are mobilising their resources to upgrade their processing facilities to digest heavier, higher sulphur and higher naphthenic acid crudes.
Central to this is either the implementation of delayed coker units or ebullated bed hydrocracking technologies, as these will greatly increase refining margin. BP opted for the delayed coking technique, a cyclic process which cracks residue feedstocks and converts them into petroleum coke, gas and light products.
For the modernisation project underway at Whiting, BP awarded Foster Wheeler Ltd subsidiary Foster Wheeler USA Corporation contracts for the engineering, procurement and fabrication of a 102,000 barrels per stream day (bpsd) six-drum delayed coking unit, three delayed coking heaters and gas plant facilities. The technological backbone of the delayed coking unit sits upon what the company has named as the SYDEC process.
Foster Wheeler's SYDEC technique is a thermal conversion process to upgrade heavy residue feed and process it into high-value transport fuels. The Foster Wheeler delayed coker heaters, based on Foster Wheeler’s proprietary Terrace-Wall design, are an integral component of SYDEC.
SYDEC’s key process steps include heating the feedstock to approximately 500°C in the coker furnace, after which the hot residue is moved to the coke drum before coke is formed. The drum is then filled and the heavy tars are converted, before the drum is switched on a time cycle which varies between 12-24 hours. Following this step, the full drum is subject to hydraulic decoking. Finally, the cut coke is recovered, crushed and prepared for shipment. Additional steps also include recycling the water to eliminate waste, fractioning cracked products into gas, coker naphtha, light coker gasoil and heavy coker gasoil, as well as the further processing of fractioned products in downstream units.
Matching distillation and hydro treatment
While delayed coking seems to be the big gun in BP’s Whiting modernisation project, such heavy crude processing power needs to be accompanied by equally efficient technologies to boost two preceding and crucial steps in the refining process – these are distillation and hydrodesulphurization.
Crude oil is composed of many substances with varying size, weight and boiling point. These are separated through distillation, when the feedstock is heated until it reaches boiling point and vapour is produced. The vapour then enters the fractional distillation unit, where component separation occurs by condensation at different temperatures.
However, heavy crudes are more difficult to distil than lighter crude blends. First and foremost, they possess higher viscosity; some have higher salt content; while several have high naphthenic acid content. Flow schemes and adequate equipment must be considered thoroughly to maintain crude charge rate and product yield, as technologies which may have been efficient when treating lighter crudes raise several constraints when heavy crude becomes the prevailing component in a refinery’s energy input mix.
After distillation, trays collect the liquid feed that forms from the process, which is then moved into the hydrotreater, where sulphur and nitrogen are removed from the gasoil.
For these important steps, BP looked to global services company Fluor Corporation to handle the management, engineering, procurement, fabrication and construction of multiple projects including the revamped crude distillation unit, the new gas oil hydrotreater, as well as major upgrades to a crude/vacuum unit and the modernisation of utilities and off-sites to support the additional heavy crude oil processing.
Whiting’s WRMP operations began in May 2008 and the project was 70 per cent complete as of September 2012, with more than 8,000 contractors on site, according to BP. The distillation unit will be operational by mid-2013, while the coker and gas oil hydrotreater will come on-stream in the second half of 2013, when the modernised refinery is slated to be launched.