2/16/2015 NPTEL :: Chemical Engineering Petroleum Refinery Engineering
data:text/html;charset=utf8,%3Ctable%20width%3D%2280%25%22%20border%3D%220%22%20align%3D%22center%22%20cellpadding%3D%220%22%2… 1/5
CRUDE DISTILLATION Overview Purpose
To recover light materials.Fractionate into sharp light fractions.
Configuration —May be as many as three columns in seriesCrude Stabilizer/Preflash Column
Reduce traffic in the Atmospheric ColumnAtmospheric ColumnVacuum Column
Reduced pressure to keep temperatures below 650o F Crude Oil Fractionation / Distillation
Crude oil is heated to 750 oF (400 oC)Heated crude is separated into rough "cuts“
Different boiling point are drawn from the distillation tower.Light compounds (fuel gas and LPG) rise to the top of the tower, Heavy material(asphalt) falls to the bottom of the tower.
Petroleum Refining Operations.
Petroleum refining begins with the distillation, or fractionation, of crude oils intoseparate hydrocarbon groups like Light ends, naphtha/gasoline kerosine dieseland residue etc.The resultant products are directly related to the characteristics of the crudeprocessed.(T 650750 deg oF) or (310 oC350 oC)Most distillation products are further converted into more usable products bychanging the size and structure of the hydrocarbon molecules through cracking,reforming, and other conversion processes.
2/16/2015 NPTEL :: Chemical Engineering Petroleum Refinery Engineering
data:text/html;charset=utf8,%3Ctable%20width%3D%2280%25%22%20border%3D%220%22%20align%3D%22center%22%20cellpadding%3D%220%22%2… 2/5
Fig 1.10 Atmospheric Distillation[19]
Fig:1.11 Typical Configuration Atmospheric Column w/o Preflash[19,20]
2/16/2015 NPTEL :: Chemical Engineering Petroleum Refinery Engineering
data:text/html;charset=utf8,%3Ctable%20width%3D%2280%25%22%20border%3D%220%22%20align%3D%22center%22%20cellpadding%3D%220%22%2… 3/5
Fig:1.12 ADU & VDU OVERVIEW [24,25]
Wash Zone
Couple trays between flash zone & gas oil draw.Reflux to wash resins & other heavy materials that may contaminate theproducts.
Condenser
Typically 0.5 to 0.2 psig.Balancing act
Low pressure reduce compression on overhead system.High pressure decrease vaporization but increases flash zone temperature &furnance duty: affects yields.
Pumparounds
Reduces overhead condenser load & achieves more uniform tower loading.provides liquid reflux below liquid draws.
Side draws & strippers cut point related to final boiling point of draw steam.
2/16/2015 NPTEL :: Chemical Engineering Petroleum Refinery Engineering
data:text/html;charset=utf8,%3Ctable%20width%3D%2280%25%22%20border%3D%220%22%20align%3D%22center%22%20cellpadding%3D%220%22%2… 4/5
Side strippers remove light component tail & return to main column.Steam strippers traditional.Reboiled strippers reduce steam usage & associated sour water.
Trays & pressure profile [19,20,24,25]
Typically 32 in tower 0.1 to 0.2 psi per tray.Condenser & accumulator 3 to 10 psi across condenser liquid static head inaccumulator.Typically 6 to 16 psi across entire column.
Fig:1.13 A typical configuration of Atmospheric column with stripping section
and reflux drum arrangement.
2/16/2015 NPTEL :: Chemical Engineering Petroleum Refinery Engineering
data:text/html;charset=utf8,%3Ctable%20width%3D%2280%25%22%20border%3D%220%22%20align%3D%22center%22%20cellpadding%3D%220%22%2… 5/5
Fig:1.14[19]A typical configuration of two stage hydrocracking unit.
Table:1.4
Typical Crude Tower Cut Points[19,20]
CUT TBP IBP(oF) TBP EP(oF)
Light Naphtha(LSR Gasoline) 80 to 90 180 to 220
Heavy Naphtha 180 to 220 330 to 380
Distillate (Kerosene) 330 to 380 420 to 520
AGO(Atm Gas Oil) 420 to 520 650
LVGO(Light Vac Gas Oil) 650 800
HVGO(Heavy Vac Gas Oil) 800 950 to 1100
Vaccum Resid 950 to 1100