Petroleum and Gas Processing(TKK-2136) 14/15 Fall semester Instructor: Rama Oktavian Office Hr.: M.13-15, Tu , W , Th , F

Outlines 1. Crude distillation unit: Desalter 2. Distillation column configuration 3. CDU material balance 4. Crude oil products uses

Crude Distillation Unit (CDU)

Crude Distillation Unit Crude desalter unit Salt content crude oil is usually denoted as pounds salt (measured as NaCl) per thousand barrels of crude oil (ptb)

Crude Distillation Unit Crude desalter unit

Crude Distillation Unit Crude desalter unit The salt content should be lowered to between 5.7 and 14.3 kg/1000 m 3 (2 and 5 PTB) Poor desalting has the following effects: 1.Salts deposit inside the tubes of furnaces and on the tube bundles of heat exchangers creating fouling, thus reducing the heat transfer efficiency 2.Corrosion of overhead equipment 3.The salts carried with the products act as catalyst poisons in catalytic cracking units

Crude Distillation Unit Crude desalter unit operation variable 1.Desalting temperature – affect settling rate, typical desalting temperature can vary between 50 and150 C (122 and 302 F) 2.Washing water ratio – affect in salt removal, Kuwait crude (31.2 API) requires 7–8 vol% water addition relative to the crude rate 3.Water level - Raising the water level reduces the settling time for the water droplets in the crude oil, thus improving the desalting efficiency 4.Washing water injection point 5.Demulsifier injection rate 6.Type of washing water - relatively soft to prevent scaling, slightly acidic with a pH in the range of 6, free from hydrogen sulphide and ammonia 7.Pressure drop in the mixing valve - A pressure drop between 0.5 and 1.5 bar (7.4 and 22 psi) is used

Crude Distillation Unit Crude electrostatic desalting unit

Crude Distillation Unit Atmospheric distillation unit Crude oil from the desalter is heated in a train of heat exchangers up to a temperature of 250°C–260°C and further by a tube-still heater (also known as a pipe-still furnace) to a temperature of 350°C–360°C Top pressure is maintained at 1.2–1.5 atm Vapours from the top of the column, consisting of hydrocarbon gases and naphtha, emerge at a temperature of 120°C–130°C A few plates below the top plate, the kerosene fraction is drawn at a draw temperature of 190°C–200°C A few plates below the kerosene draw plate, the diesel fraction ) is drawn at a temperature of 280°C–300°C The temperature of the stream at the bottom reaches around 340°C–350°C

Crude Distillation Unit Atmospheric distillation unit A typical atmospheric distillation column contains 41 plates The hot feed crude oil is flashed in the fifth plate Products: -top distillate (IBP–140°C cut) -straight run kerosene (140°C–270°C cut) -straight run diesel (270°C–340°C cut) -JBO (340°C–365°C cut) -the bottom residue (RCO, 365°C +cut)

Crude Distillation Unit Atmospheric distillation unit

Crude Distillation Unit Atmospheric distillation unit

Crude Distillation Unit Product stabilization

Crude Distillation Unit Condition parameter Column Pressure Controlled by the back pressure of the overhead reflux drum The top tray pressure is 0.4–0.7 bar gauge (6–10 psig) higher than the reflux drum The flash zone pressure is usually 0.34–0.54 bar (5–8 psi) higher than the top tray Overhead Temperature must be controlled to be 14–17 C (25–31 F) higher than the dew point temperature for the water to prevent water liquid condensation

Crude Distillation Unit Condition parameter

Crude Distillation Unit Crude material balance Crude Assay Data

Crude Distillation Unit Crude material balance Crude Assay Data PROPERTIES OF TBP CUTS CutsYield Den 15°CSRSHRONMON Napht.Aro.RVP LIGHT °Cwt%vol %kg/m3wt%mg/kgclear vol% kPa NAPHTHA CutsYield Den 15°CSRSH Napht.Aro. HEAVY °Cwt%vol %kg/m3wt%mg/kg vol% NAPHTHA CutsYield Den 15°CSRSHSmokeAcidityCetaneFreez. Pt Aro.Visc cSt Flash KEROSENE °Cwt%vol %kg/m3wt%mg/kgPt mm mgKOH/ gIndex°C vol%50°C Point CutsYield Den 15°CS Anilin CetaneCloud PtCFPPPour PtVisc cSt UOPKFlash GASOIL °Cwt%vol %kg/m3wt% Point °C IndexCCC50°C100°C Point CutsYield Den 15°CSConrad.AnilinNiVaTotal NBas NPour PtVisc cSt UOPKAsp C7 VACUUM °Cwt%vol %kg/m3wt% Point °Cmg/kg wt%mg/kgC100°C150°C wt % DISTILLATE CutsYield Den 15°CSConrad.AcidityNiVaTotal N Pour PtVisc cSt PeneAsp C7 RESIDUE °Cwt%vol %kg/m3wt% mgKOH/ gmg/kg wt% C100°C150°Cmm/10wt% > > > > This crude oil data sheet is for information purposes only. No guaranty is given as to its accuracy or as to any consequences arising from its use. TOTAL DTS / AMMar-14

Crude Distillation Unit Material balance

Crude Distillation Unit Solution Step 1: Construct fifth order polynomial fit of TBP data versus vol%

Crude Distillation Unit Solution Step 2: From the end point of each cut, calculate the cumulative volume percent, example: the cumulative volume percent for the off gas and the light straight run naphtha is 1.33 and 8.6%, respectively

Crude Distillation Unit Solution Step 3: Calculating average normal boiling point. The average normal boiling point for each cut is calculated at the mid percent of each cut. in this case the light straight run naphtha is /2 or 4.965% Average boiling point - to be 43.6 C

Crude Distillation Unit Solution Step 4: Calculating Molecular weight.

Crude Distillation Unit Solution Step 5: Calculating specific gravity.

Crude Distillation Unit Solution

Crude Distillation Unit Material balance

Vacuum Distillation Unit Products Light vacuum gas oil (LVGO) Medium vacuum gas oil (MVGO) Heavy vacuum gas oil (HVGO) Vacuum residue

Vacuum Distillation Unit Process overview