how does fractional distilation work using crude oil?

what happens once the crude oil is heated and then turns into gas.
Please could uoy tell me step by step on how it works
much appreciated, thanks

3 Responses to “how does fractional distilation work using crude oil?”

  1. Norrie Says:

    The process is very involved. Following is, as far as possible a very condensed idea of the process.

    *…In the distillation process, the crude oil feed is first heated by exchanging heat with some of the hot products leaving the column. This cools the products and, at the same time reduces the fuel requirements in the main heater – the fuel fired furnace.
    *…The hot feed now enters the tower into the ‘Flash Zone’. At this point, due to the greatly increased volume of the column, the lighter components of the crude oil ‘ Flash Off ‘ (vaporise), and rise up the column. The hot liquid will fall towards the column bottom.
    *…The bottom section of the column, below the Flash Zone, called the ‘Stripping Section’, contains trays – generally Bubble-cap or Sieve type. The tower bottom liquid is re-circulated & re-heated in a steam or fired ‘Reboiler’ which drives off vapours of light ends and some of the heavy ends contained in the liquid. These vapours rise upwards through the trays and contact the down-flowing liquid. This action further removes (strips out), light ends from the liquid.
    *…The top section of the tower, above the flash zone, is called the ‘Rectifying Section’. Here again, the rising vapour passing through the trays, contacts the liquid flowing across them.

    *…Action of the Trays
    Each tray in the tower is acting as a simple distillation process.
    *…As we rise above the flash zone, each succeeding tray is slightly cooler than the tray below.
    The down-flowing liquid, as it passes across the trays is becoming hotter and heavier as light ends boil off into the vapour phase. Conversely, the rising vapour is becoming cooler and lighter as heavier ends condense into the liquid on the tray.
    *…The down-flowing liquid is called ‘Internal Reflux’ and works by the liquid returned to the preceding tray.

    *…At pre-determined points in the column, the process conditions (mainly temperature and pressure), are such that, the liquid components are at the required purity to meet the specification desired as a product – like ‘Kerosene’ for example. At these points, the tower will contain ‘Collecting Pans’ from which the desired product can be drawn from the tower.
    *…The lightest components of the crude oil mixture leave the top of the tower as vapour. This is fed through condensers – generally water-cooled – and the condensate, usually Naphtha and water, passes into the ‘Overhead Receiver or Accumulator’.
    *…In the receiver, light gases also build up. The control of these gases, (to a fuel system or flare), also controls the pressure on the distillation process at the required level.
    *…The Naphtha liquid forms an interface above the water. The water is drained away under control, to disposal. The Naphtha, also under level control, is divided into two – some is returned to the tower top tray as ‘External Reflux’ which is used to control the tower top temperature and thereby help to control the naphtha quality.
    *…The remaining naphtha from the receiver is piped to storage and / or to other processes.
    The products leaving the side of the column – called ‘Side-streams’, are usually passed through ‘Stripping Towers’ where an injection of superheated steam removes final traces of light ends to meet the specification required for the product. The light ends and steam are passed back into the main tower.
    *…The control of the quality of the side-stream products is generally helped by a controlled flow of ‘Intermediate Reflux’ of some of the product into the column just above the section producing the product.
    *…The side-stream products pass from the stripping towers through feed / product exchangers and water coolers to storage.
    *…The tower bottom product as already mentioned, is reheated in a reboiler to remove light ends and to provide stripping gases in the tower. The final bottom product, such as heavy fuel oil is pumped away via feed/product heat exchangers and water coolers to storage.
    *…Crude oil distillation is often carried out under vacuum conditions. The vacuum is produced by pulling the overhead vapour from the tower by steam ejectors via surface condensers.
    *…The explanation of crude oil separation given above, is that of a basic system. Crude oils also produce chemicals, waxes, gasolines, lubricants and many other products in everyday use.

  2. kishorekchokshi Says:

    There are BOOKS AND BOOKS on this subject.

    take a little pain to read.

    KishoreKChokshi@yahoo.com

  3. i love my strarry jumper! Says:

    omg! this is soo boring,
    we learnt this the other day in chemo!
    theres like 7 oils that come out of crude oil, they boil it through a tube with like 7 terminals or some shit like that lol