Refining, the Four Main Stages in Processing Crude Oil
Refining processes, crude oil is converted in four main stages:
- Atmospheric distillation — distillation at close to atmospheric pressure — separates the oil into different "fractions" or "cuts." When heated, the lightest and most volatile products such as butane, propane and light gasoline rise to the top of the distillation column and are drawn off. Other products, such as heavy naphtha jet fuel, diesel and home heating oil fractions, are recovered at different heights in the column. The residue, or heavy fuel oil, is drawn off at the bottom. Subjecting the residue to a second distillation process known as vacuum distillation yields additional diesel. The residue then left at the bottom of the column, which no longer contains diesel or light products, is used to manufacture asphalt and heavy fuel oil.
- Various conversion processes are carried out to alter the chemical structure of the base fractions produced by distillation. Catalytic cracking uses a catalyst and high temperatures of around 500°C to break down the heavy molecules and convert them into lighter products, such as gas, gasoline and diesel. Hydrocracking acts in a similar way but can also produce ultra-low sulfur diesel, with the help of hydrogen. Deep conversion processes such as coking further boost the amount of light products obtained from heavy fuel oil.
- Treatment processes remove or neutralize acidic, corrosive or environmentally harmful components. Desulfurization, or sulfur recovery, is a key treatment process in the refining industry today. Despite heavier feedstock containing more sulfur, refineries have to be able to produce automotive and other fuels with ever-lower sulfur contents, in line with increasingly stringent environmental standards.
- Blending — the final stage — is decisive in ensuring that the finished products meet very precise technical specifications.
Petrochemicals, from Naphtha to Plastic
Night view of the Normandy refinery
in Gonfreville-l’Orcher, France.
The naphtha fraction produced by atmospheric distillation and refining is used as a petrochemical feedstock. There are two steps in plastics manufacturing:
- Steam cracking breaks down the naphtha hydrocarbons into light unsaturated molecules that consist of only two or three carbon atoms, ethylene and propylene, and others that consist of four or more carbon atoms — the C4+ family, which includes aromatics.
A less common type of steam cracker is an ethane cracker, which primarily produces ethylene. The QAPCO and Qatofin crackers in Qatar are ethane crackers.
- Polymerizationconverts these unsaturated molecules (olefins) into very long carbon chains (polymers or plastics). We produce three main types of polymer:
- Polyethylene, a plastic created by polymerizing ethylene. It is primarily used in the packaging, automotive, food, cable and pipe industries.
- Polypropylene, a plastic created by polymerizing propylene. It is primarily used in the automotive and packaging industries and in household appliances, electrical devices, fibers and hygiene products.
- Polystyrene, a plastic created by polymerizing styrene (benzene + ethylene). It is primarily used in packaging, insulation and refrigeration applications.
Adapting Refineries to Global Market Trends
The ethane cracker at the Qatofin
petrochemical plant in Ras Laffan, Qatar.
Demand for lighter, low sulfur fuels will have spread to all consumer markets by 2030. The future of refining therefore rides on large-scale, deep-conversion refineries located close to both heavy oil resources and customer markets.
With this in mind, we are leveraging our capacity for innovation to adjust our production base.
- The Port Arthur refinery in the United Stateshas undergone a sweeping upgrade. The installation of new deep conversion, vacuum distillation, sulfur recovery and related units has expanded the refinery’s ability to process heavy, sour crude oil and increased its output of ultra-low sulfur diesel.
- In partnership with Saudi Aramco, we are building the full-conversion SATORP refinery in Jubail, Saudi Arabia. With a capacity of 400 000,000 barrels per day, the new refinery will be able to process heavy oil from some of the world’s biggest fields to produce automotive fuels and other light products that comply with the strictest specifications. Most of its output will be exported.
Increasing Diesel Production and Reducing Sulfur Content in Europe
We are upgrading our European refining base to meet new challenges, which include a supply of increasingly sour crude oil, a surplus of gasoline and heavy fuel oil but a shortfall of diesel, and increasingly strict fuel specifications.
In France, for example, work is under way at the Normandy refinery to shift the production emphasis to diesel. Investments have scaled back distillation capacity, expanded the distillate hydrocracker (DHC), enhanced energy efficiency and reduced carbon emissions.
Refocusing Petrochemicals on Growth Markets
To expand our market share and meet new customer expectations, we must take into account the major changes occurring in the global market:
- Asia has emerged as the primary growth region for polymer demand. Total and Samsung jointly own the integrated Daesan facility in South Korea. So far, $1.8 billion has been invested in a major project to double the platform’s sizeas part of our expansion strategy in fast-growing markets. And the integrated paraxylene unit at the SATORP refinery in Jubail, Saudi Arabia will also primarily supply Asian markets.
- The Middle East is becoming a global hub for polymer production and export. Total is participating in the trend, thanks to our in-depth knowledge of the countries in this region and natural synergies with our Exploration & Production activities. This integrated approach will also give us easier access to other raw materials, such as ethane, which comes from natural gas.
Natural Gas and Renewables, New Feedstock for Petrochemicals
We are also looking at how we can use alternative resources to produce the plastics of the future, with a particular focus on:
- Ethane from natural gas.
- The production of compostable or depolymerizable plant-based bioplastics from the lactic acid contained in certain plants, such as sugar beets, corn, wheat and sugar cane.
- The conversion of gas-, coal- or biomass-derived strong>methanol into olefins and polyolefins.
We also support intelligent, innovative solutions for recovering and recycling end-of-life plastics.