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Petroleum and Gas Processing(TKK-2136)
14/15 Fall semester
Instructor: Rama OktavianEmail: [email protected] Hr.: M.13-15, Tu. 13-15, W. 13-15, Th. 13-15, F. 09-11
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 (CDU)
Crude Distillation Unit (CDU)
Crude Distillation UnitCrude desalter unit
Salt content crude oil is usually denoted as pounds salt (measured as NaCl) per thousand barrels of crude oil (ptb)
Crude Distillation UnitCrude desalter unit
Crude Distillation UnitCrude desalter unit
The salt content should be lowered to between 5.7 and 14.3 kg/1000 m3 (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 equipment3. The salts carried with the products act as catalyst poisons
in catalytic cracking units
Crude Distillation UnitCrude 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 point5. Demulsifier injection rate6. Type of washing water - relatively soft to prevent scaling, slightly acidic
with a pH in the range of 6, free from hydrogen sulphide and ammonia7. 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 UnitCrude electrostatic desalting unit
Crude Distillation UnitAtmospheric 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 UnitAtmospheric 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 UnitAtmospheric distillation unit
Crude Distillation UnitAtmospheric distillation unit
Crude Distillation UnitProduct stabilization
Crude Distillation UnitCondition parameter
Column PressureControlled 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 Temperaturemust 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 UnitCondition parameter
Crude Distillation UnitCrude material balance
Crude Assay Data
Crude Distillation UnitCrude material balance
Crude Assay Data PROPERTIES OF TBP CUTS
Cuts Yield YieldDen 15°C S RSH RON MON Napht. Aro. RVP
LIGHT °C wt% vol % kg/m3 wt% mg/kg clear clear vol% vol% kPa
NAPHTHA 15-65 3.52 4.52 644 0.0032 0 86.2 81.5 4.6 0.1 185.28
15-80 5.29 6.62 661 0.0037 1 86.1 81.2 9.9 0.3 150.93
Cuts Yield YieldDen 15°C S RSH Napht. Aro.
HEAVY °C wt% vol % kg/m3 wt% mg/kg vol% vol%
NAPHTHA 80-150 16.41 18.03 752 0.0081 2 32.2 11.3
80-175 22.45 24.29 764 0.0103 2 32.0 13.3
100-150 12.35 13.38 763 0.0090 2 32.9 14.5
Cuts Yield YieldDen 15°C S RSH Smoke Acidity Cetane Freez. Pt Aro. Visc cSt Flash
KEROSENE °C wt% vol % kg/m3 wt% mg/kg Pt mmmgKOH/
g Index °C vol% 50°C Point
150-230 21.72 22.08 813 0.029 2 16 0.08 35.6 -54 16.2 1.0 -
175-230 15.68 15.82 820 0.033 2 16 0.09 36.9 -50 15.1 1.2 -
150-250 27.87 28.16 818 0.034 2 16 0.09 37.9 -49 16.2 1.2 -
Cuts Yield YieldDen 15°C S Anilin Cetane Cloud Pt CFPP Pour Pt Visc cSt Visc cSt UOPK Flash
GASOIL °C wt% vol % kg/m3 wt% Point °C Index C C C 50°C 100°C Point
175-400 55.55 53.75 854 0.072 64 45.3 -6 -9 -12 2.5 1.2 11.7 -
230-400 39.86 37.93 869 0.088 68 48.1 -1 -1 -2 3.6 1.5 11.7 -
230-375 34.31 32.90 862 0.083 67 48.4 -7 -7 -8 3.1 1.4 11.7 -
Cuts Yield YieldDen 15°C S Conrad. Anilin Ni Va Total N Bas N Pour Pt Visc cSt Visc cSt UOPK Asp C7
VACUUM °C wt% vol % kg/m3 wt% wt% Point °C mg/kg mg/kg wt% mg/kg C 100°C 150°C wt %
DISTILLATE 375-550 17.84 15.73 937 0.15 0.5 80 0 0 0.027 102 41 6.1 2.5 11.6 0.1
375-565 18.53 16.31 939 0.15 0.8 80 0 0 0.031 110 41 6.6 2.7 11.6 0.1
375-580 19.09 16.77 941 0.16 1.2 80 0 0 0.041 117 42 7.0 2.8 11.6 0.2
400-580 13.54 11.74 953 0.18 1.7 81 0 1 0.052 152 47 10.1 3.7 11.6 0.2
Cuts Yield YieldDen 15°C S Conrad. Acidity Ni Va Total N Pour Pt Visc cSt Visc cSt Pene Asp C7
RESIDUE °C wt% vol % kg/m3 wt% wt%mgKOH/
g mg/kg mg/kg wt% C 100°C 150°C mm/10 wt%
> 375 20.77 18.11 948 0.17 4.2 0.3 1 2 0.179 34 9 3 587000 0.4
> 550 2.93 2.38 1020 0.32 26.5 0.4 5 15 1.100 48 869 74 199 2.0
> 565 2.24 1.80 1028 0.34 31.8 0.4 6 19 1.400 51 2470 145 124 2.4
> 580 1.68 1.34 1036 0.36 37.6 0.4 8 23 1.750 55 8420 321 91 2.7
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 / AM Mar-14
Crude Distillation UnitMaterial balance
Crude Distillation UnitSolution
Step 1: Construct fifth order polynomial fit of TBP data versus vol%
Crude Distillation UnitSolution
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 UnitSolution
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 1.33 + 7.27/2 or 4.965%Average boiling point - to be 43.6 C
Crude Distillation UnitSolution
Step 4: Calculating Molecular weight.
Crude Distillation UnitSolution
Step 5: Calculating specific gravity.
Crude Distillation UnitSolution
Crude Distillation UnitMaterial balance
Vacuum Distillation UnitProducts
Light vacuum gas oil (LVGO)
Medium vacuum gas oil (MVGO)
Heavy vacuum gas oil (HVGO)
Vacuum residue
Vacuum Distillation UnitProcess overview