Dehydration and Desalting Pumping of WAXY crude Heating of crude Distillation of petroleum & Types of Reflux

1. FRACTIONATION OF PETROLEUM
NAME : SAKHARELIYA SHUBHAM ATULBHAI
ENROLLMENT NO. : 180470105047
BRANCH : CHEMICAL ENGINEERING
SUBJECT : PETROLEUM REFINING AND PETROCHEMICALS

2. CONTENTS
• PRETREATMENT OF CRUDE (DEHYDRATION AND
DESALTING)
• PUMPING OF WAXY CRUDE
• HEATING OF CRUDE
• DISTILLATION OF PETROLEUM & TYPES OF
REFLUX

3. DEHYDRATION AND DESALTING
• THERE IS PRESENCE OF WATER AND SALT IN CRUDE AT
DIFFERENT DEGREES.
• THE CRUDE NEED TO BE DEHYDRATED FOR REMOVING THE
SALTS. REMOVAL IS DONE IN THE FORM OF BRINE.
• SALTS OF CHLORIDES AND MAGNESIUM ARE HARMFUL, AS THEY
REACT WITH THE STEAM AND FORM HYDROCHLORIC ACID AND
MAGNESIUM HYDROXIDE, WHICH CAUSES TANK CORROSION.
• ANY CRUDE THAT CONTAINS 5 KG OF SALT PER 1000 BARRELS
(1BARREL=159 KGS) IS CALLED SALTY CRUDE.
• IF THE CRUDE ARE KEPT FOR LONGER DURATION, THEY PERMIT
SEPARATION.
• GENERAL METHODS OF DEHYDRATION:
1) CHEMICAL TREATMENT
2) GRAVITY SETTLING
3) CENTRIFUGAL SEPARATION
4) ELECTRIC DESALTER

4. CHEMICAL TREATMENT AND GRAVITY SETTLING
• AT THE OIL FIELD THE SALT IS REMOVED BY THE SETTLING OR BY
ADDING THE CHEMICALS.
• BUT THOSE WHICH HAVE EMULSIFIER (WHICH DO NOT MIX
WITH WATER) DOES NOT SETTLE, HENCE WE USE DEMULSIFIERS
TO INCREASE THE COALESCENCE OF WATER DROPS.
• DEMULSIFIERS EXAMPLE: SODA ASH, SODIUM HYDROXIDE,
SALTS OF FATTY ACIDS.
• AFTER ADDING THE WATER, THE CRUDE MIXTURE IS ALLOWED
TO STAND FOR 48 HOURS AT 75-80ºC.
• THE STORAGE CAPACITY OF TANKS IS 3000 KILOLITRES.
• COALESCENCE IS FOLLOWED BY PASSING THE MIXTURE
THROUGH TOWERS OF GRAVEL.
• DISADVANTAGES:
• SETTLING METHOD IS TIME CONSUMING
• NOT CONTINUOUS
• LARGE SPACE
• LARGE EQUIPMENT

6. ELECTRIC DESALTING
• SIMULTANEOUS DESALTING AND DEHYDRATION IS ACHIEVED.
• MORE THAN 90% OF SALT IS REMOVED IN 30MINS.
• PRINCIPLE: UNDER THE CHARGED ELECTRIC FIELD THE POLAR
MOLECULES ORIENT.
• 20,000 – 30,000 VOLTS IS APPLIED BETWEEN ELECTRODES
THROUGH WHICH CRUDE IS PASSED.
• WATER TAKES UP SALT.
• BRINE COLLECT AT THE BOTTOM OF DESALTER.
• WHILE CRUDE FLOATS ABOVE AND FORM A STREAM.
• TEMPERATURE MAINTAINED: 90º C AND PRESSURE 5-6 KG/CM3

8. ADVANTAGES:
1. COMPACT
2. EFFICIENT
3. EASY TO OPERATE
4. LOW POWER CONSUMPTION
APPLICATION:
1. ELECTRIC DESALTING IS APPLIED IN TREATMENT OF
DISTILLED STOCKS.
2. ACID AND CAUSTIC STOCKS FORM EMULSIONS,
ELECTROSTATIC FIELD BREAKS THEM.
3. CATALYST POISONED SALTS ARE ALSO REMOVED.

9. PUMPING OF WAXY CRUDES
• THE MAJOR FACTOR IN PUMPING IS POUR POINT.
• INDIAN CRUDES ARE WAXY AND HENCE POUR POINT IS
HIGHER.
• FOR TRANSPORTATION OF WAXY CRUDES, THEY ARE FIRST
CONDITIONED.
• CONDITIONING IS DONE, IS BASED UPON THE BEHAVIORS
OF WAX.
• THERE ARE CYCLES OF HEATING AND COOLING.
• FIRSTLY THEY ARE HEATED UP TO 95 0C, FOLLOWED BY
COOLING IN 2 STAGES.
• FIRST COOLING GOES DOWN TO 65 0C FOLLOWED BY
ANOTHER CYCLE TO 18 0C
• THE RATE IS 0.5 0C PER MINUTE.
• THIS WAY THE CRYSTALS IS MODIFIED TO WAX TO PERMIT
THE FLOW.

10. • OTHER METHODS FOR TREATMENT OF WAXY
CRUDE(FOR IMPROVING POUR POINT/ FLUIDITY)
(a) DILUENT ADDITION
(b) CHEMICAL ADDITIVES
(A) DILUENT ADDITION:
• SOLVENTS CAN BE ADDED, ALTHOUGH THEY
MIGHT CONTAMINATE THE CRUDE.
• BEST DILUENT IS WATER, BUT WE NEED IT IN
HIGHER AMOUNTS.
• HIGHER PUMPING COST AND PIPE LINES.

11. (B) CHEMICAL ADDITION:
• CHEMICAL USAGE CAN REDUCE THE POUR POINT OF THE
CRUDE.
• THIS CAN REPLACE THE CONDITIONING PLANTS WHERE
LARGE TANKS ARE USED.
• THESE CHEMICALS CHANGE THE STRUCTURE OF THE
CRUDE AND RETARD THE CRYSTAL GROWTH.
• THIS REDUCES VISCOSITY.
• IT IS STABILIZED FOR 40 – 60 HOURS, THEN
TRANSPORTED.
• THIS CRUDE WILL BE STABLE IN PRESENCE OF
ADDITIVES FOR A MONTH ONLY BEFORE COMPLETION.
• EXAMPLES: POLYACRYLATES, ACRYLATE-STYRENE
COPOLYMERS, ALKYLATED POLYSTYRENE ETC.

12. HEATING OF CRUDE
HEATING OF CRUDE: PIPE STILL HEATERS
• EARLIER THE FUELS WERE HEATED CONVENTIONALLY, IN HUGE
TANKS.
• THERE WERE NON UNIFORM HEATING OF THE CRUDE.
• PIPE STILL HEATERS ARE MORE EFFICIENT.
• THEY ARE COMPACT IN SIZE.
• THEY ARE ACCURATE IN CONTROL.
• THEY ARE MORE FLEXIBLE, WHEN WE NEED CERTAIN QUALITY
AND QUANTITY.
• THE HEAT TRANSFER IN RADIANT SECTION IS HIGHER AS 70%.
• STACK LOSS REDUCED BY 12%
• HEATER LOSS REDUCED BY 5%
• THEY ARE OF 3 TYPES:
1) BOX/RECTANGULAR
2) CYLINDRICAL
3) RADIANT WALL

13. DISTILLATION OF PETROLEUM
• IT IS A METHOD OF SEPARATING THE SOLUBLE LIQUID
MIXTURES INTO INDIVIDUAL COMPONENTS.
• DISTILLATION OF CRUDE MAINLY TAKES PLACE IN TWO STAGES.
• FIRST STAGE, IS CARRIED OUT IN ATMOSPHERIC PRESSURE
CALLED ATMOSPHERIC DISTILLATION UNIT.
• THE UNDISTILLED CRUDE, CALLED REDUCED CRUDE IS
DISTILLED UNDER LOWER PRESSURE CALLED VACCUM
DISTILLATION UNIT.
ARRANGEMENT OF TOWERS
• THERE ARE 3 TYPES OF TOWER ARRANGEMENTS:
(a) TOP TRAY REFLUX
(b) PUMP BACK REFLUX
(c) PUMP AROUND REFLUX TOWERS

14. TOP TRAY REFLUX
• HERE THE REFLUX IS AT THE TOP TRAY
ONLY AND THE REFLUX IS COOLED AND
SENT INTO THE TOWER.
• HEAT INPUT IS FROM THE BOTTOM AND
THE REMOVAL IS FROM THE TOP.
• THIS CREATES A BUILD UP OF VAPOURS,
HENCE WE NEED LARGER DIAMETERS.
• THE REFLUX HERE IS NOT PROPER AND
QUALITY IS POOR.

15. PUMP BACK REFLUX
• REFLUX IS PROVIDED AT REGULAR
INTERVALS.
• HENCE EVERY PLATE ACTS AS A TRUE
FRACTIONATORS BECAUSE THERE IS
ALWAYS GOOD AMOUNT OF LIQUID.
• THE TOWER IS UNIFORMLY LOADED.
• HENCE LESSER DIAMETER TOWER WILL
DO.
• THEY ARE COSTLY, BUT QUALITY OF
PRODUCTS ARE BETTER.

16. PUMP AROUND REFLUX
• REFLUX FROM A LOWER PLATE IS TAKEN
AND COOLED AND FED TO A HIGHER
SECTION BY 2 TO 3 PLATES.
• THERE IS UNEVEN MIXING OF REFLUX AND
LIQUID PRESENT ON THE TRAY.
• HENCE, THE DESIGNERS TREAT ALL THE
PLATES IN THE ZONE AS ONE SINGLE PLATE.
• THIS INCREASES THE TOWER HEIGHT.
• HERE PUMP IS NOT PLACED IN MORE THAN
TWO SECTIONS.

17. THANK
YOU