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1. Producing natural gas

Qatar's North Field is the world's largest natural gas field. It contains over 900 trillion cubic feet of natural gas, about 15% of the global total. Two unmanned offshore platforms each operate 11 wells. The gas flows through two pipelines to processing facilities at the onshore Ras Laffan industrial zone.

QUICK FACTS

1. The steel used in the pipelines weighs as much as 18 Eiffel Towers.
2. Special chemicals are injected with the gas to protect the carbon steel pipelines against corrosion and to stop ice crystals forming inside.

2. Separating the gas

Water and condensates are separated from the gas. Other components, such as sulphur, are also removed and cleaned. The gas is then cooled and the natural gas liquids are removed via distillation. The remaining pure natural gas (methane) flows to the gasification unit.

QUICK FACTS

1. The extracted sulphur is used for other purposes, such as producing fertilisers, in asphalt and concrete.
2. The natural gas liquids are piped to Ras Laffan port and sold as chemical feedstocks and LPG fuel for heating appliances and vehicles.

3. Making synthesis gas

In the gasifier at around 2,200-2,650°F (1,400-1,600°C) the methane and oxygen are converted into a mixture of hydrogen and carbon monoxide known as synthesis gas, or syngas.

QUICK FACTS


1. The reaction produces heat, which is recovered to produce steam for power.

4. Making liquid waxy hydrocarbons

The synthesis gas enters one of 24 reactors. Each reactor holds a large number of tubes containing a Shell proprietary catalyst. The catalyst serves to speed up the chemical reaction in which the synthesis gas is converted into long-chained waxy hydrocarbons and water. 

QUICK FACTS

  1. The catalyst consists of tiny granules, just millimetres long with microscopic holes, containing minute metal particles. The total surface area of the microscopic holes in the catalyst granules is more than eighteen times the surface area of Qatar.
  2. The synthesis process generates a lot of heat, which is also used to produce steam that in turn powers the GTL plant via steam turbines.
  3. All water in the GTL process is purified and reused in the utilities system of the plant to generate steam.
  4. Placed end-to-end the tubes would stretch from Qatar to Japan.

5. Making GTL (gas to liquids) products

The plant creates a range of products from natural gas that would otherwise be produced from oil.
Using another Shell proprietary catalyst, the long hydrocarbon molecules from the GTL reactor are contacted with hydrogen and cut (cracked) into a range of smaller molecules of different length and shape. Distillation separates out the products with different boiling points. 

GTL PRODUCTS

  1. GTL Naphtha is used as a chemical feedstock for plastics manufacture.
  2. GTL Kerosene can be blended with conventional Jet Fuel (up to 50%) for use in aviation – known as GTL Jet Fuel – or used as a home heating fuel.
  3. GTL Normal paraffins are used for making more cost-effective detergents.
  4. GTL Gasoil is a diesel-type fuel that can be blended into the global diesel supply pool.
  5. GTL Base oils are used to make high-quality lubricants.

Part A

Extracting pure oxygen 

Pure oxygen for the gasification process is extracted from the air through eight vast air separation units. Air is cooled to liquefy the oxygen and nitrogen. Distillation separates out oxygen in a “cold box” – like an icebox, this helps to maintain the low temperature that is required to separate the oxygen. 

QUICK FACTS

  1. Each distillation cold box is as tall as a 10-storey building.
  2. The air separation units produce over 28,000 tonnes of oxygen each day. If this were not produced on-site, more than 1,000 trucks per day would be needed to bring it in.


Part B

Generating power using residual heat

Residual heat from various steps of the process makes steam that helps drive large compressors.

QUICK FACTS

  1. Around 8,000 tonnes of steam are generated and distributed each hour.

Reusing water (Formerly Effluent Treatment Plant)

The plant does not draw on any water from Qatar’s resources. It reuses process water as cooling water and to generate steam for power.

QUICK FACTS

  1. Water passes though filters with openings 200,000 times thinner than a human hair.

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