Question

.   Draw a block flow diagram for a petroleum refinery that includes three different separation processes, five different conversion processes along with one or more finishing processes, and one supporting process to produce altogether nine commercial fuels and materials from a sour crude oil. Clearly label all the feedstocks, processes, and products on your diagram including the type of process (separation, conversion, finishing, and support) and the intermediate products.    Make sure that all processes are correctly connected. Write down the principal objectives of this refinery.

Answer 1

refining of petroleum:

• ​Crude oil or Petroleum obtained from the mine is not fit to be marketed. It contains a lot of soluble and insoluble impurities which must be removed. Previously purification of crude oilis done by fractional distillation.
• further treatments of the products is done by refining.
• refining can be defined "as the process by which petroleum is made free of impurities, seperation of petroleum into different fractions having different boiling points and their further treatement to impart specific properties"

​refining of petroleum is done in different stages.

1. ​​Removal of Solid Impurities : ​ The crude oil is a mixture of solid, liquid and gaseous substances. This is allowed to stand undisturbed for some time, when the heavy solid particles settle down and gases evaporate. The supernant liquid is then centrifuged wherein the solids get removed.
2. _​​Removal of water (Cottrell's Process) : ​The crude oil obtained from the earth's crust is in the form of stable emulsion of oil and brine. This mixture when passed between two highly charged electrodes wil destroy the emulsion films and teh colloidal water droplets coalesce into bigger drops and get seperated out from the oil.
3. ​Removal of Harmful Impurities:​ In order to remove sulphur compounds in the crude oil. it is treates=d with copper oxide. The sulphur compounds get converted to insoluble if present will corrode the refining equipment and result in scale formation. these can be removed by techniques like desalting adn dehydration.
4. ​Fractional Distillation:​ The crude oil is fractionally distilled in a fractioanting column, which is a tower like structure having a bubble tower laid inside. The crude oil or the petroleum enters through the bottom of the still by an inlet. this is made to pass about 400 degree celcius. As move to the top of the fractionating still to a temperature goes on decreasing. A number of side pipes are fitted at different heights of the column to collect fractions.

​Details of fractions obtained on fractional distillation

Name of the fraction	Boiling range	Approximate Carbon Composition
uncondensed gas	< 30 oC	C1 to C4
Petroleum ether	30-70oC	C5 to C7
Gasoline or Petrol	40-120 oC	C5 to C9
Naptha or solvent spirit	120-180 oC	C9 to C10
kerosene oil	180-250oC	C10 to C16
diesel oil	250-320oC	C10 to C 18
Heavy oil	320-240oC	C17 to C38
Residue	above 400oC	>C38