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Atmospheric distillation unit refers to a key component in the refining process of crude oil, designed to separate the various hydrocarbon fractions at or near atmospheric pressure. Here’s a detailed look at its components and operation:

  • Pipe Still: This is where the crude oil is initially heated. The pipe still is a type of furnace or heater that brings the crude oil to a temperature where it vaporizes. This heating is done at atmospheric pressure, and the crude oil is typically heated to temperatures between 316°C and 400°C (600°F to 750°F).
  • Fractionation Tower (Distillation Column): The vaporized crude oil then enters the fractionation tower, where it is separated into different components based on their boiling points. The tower is equipped with various trays or packing materials that allow for the condensation of different hydrocarbon fractions at different heights.
  • High Boiling Point Fractions: These condense at lower levels of the tower and typically include heavy residues like asphalt.
  • Medium Boiling Point Fractions: These include products like diesel and kerosene, which condense at intermediate levels.
  • Low Boiling Point Fractions: The lightest fractions, including gases like propane and butane, condense at the top of the tower.
  • Vaporization and Condensation: The separation process involves continuous vaporization and condensation. The crude oil is heated until it vaporizes, and as it rises through the fractionation tower, different components condense at different heights, allowing for their collection and further processing.
  • Processing Scheme: The exact boiling ranges for separation and the setup of the distillation unit depend on the specific processing scheme, the characteristics of the crude oil, and the desired product specifications. This includes setting the temperature and pressure conditions to optimize the separation of desired products.
  • Product Specifications: The unit is designed to meet specific product requirements, which can vary based on the intended use of the separated fractions, such as gasoline, diesel, kerosene, or other petrochemical products.

The atmospheric distillation unit is essential in the petroleum refining industry, providing the foundational separation of crude oil into its various useful components.

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