Download - Group Seminar on Desalter
TOPIC
1. Importance of Desalting2. Operating Principles of Desalting3. Desalter efficiency and its significance
Submitted by:Inderdip ShereSuma ShettigarSuraj ShahShraddha Potdukhe
IMPORTANCE OF DESALTING
WHAT IS DESALTING?
Removal of impurities from crude oil.
Contaminants are broadly classified into:
1. Water2. Salts3. Bottom sediments4. Trace metals
PROBLEMS DUE TO CONTAMINANTS
Corrosion Damages refinery tower trays, pumps ,
lines and valves Scaling in preheat exchangers Poisoning of catalysts Excessive down time
MERITS OF DESALTING
Removes contaminants Prevents corrosion and fouling Saves energy Reduces maintenance Increases the capacity of CDU Stabilizes the operation
TYPES OF DESALTING
Single stage Double stage
1ST STAGE 2ND STAGE
CRUDEWATERMIXTURE
WASH WATERPUMP
HOT TRAINEXCHANGERS
COLDTRAIN
RAW CHARGE PUMP
BRINEEXCHANGER
MIXVALVE
MIXVALVE
RAW CRUDE
WASH WATERTO FIRST STAGE
TO Atmos Column
TWO STAGE DESALTERFLOW DIAGRAM
METHODS
Settling
Addition of chemicals
Electrical desalting
STEPS:
Heating Mixing: emulsion Settling
CHEMICAL ADDITION
The Desalter removes contaminants from crude oil by first emulsifying the crude oil with chemicals and wash water to promote thorough contact of the water and oil.
The salts containing some of the metals that can poison catalysts are dissolved in the water phase.
After the oil has been washed and mixed as an emulsion of oil and water, demulsifying chemicals are then added.
Solids present in the crude will accumulate in the bottom of the desalter vessel.
ELECTRICAL DESALTERS
Forming an emulsion Demulsification process:breaking of
emulsion is accomplished by coalescing the small particles of emulsion.
• When emulsion is made to pass through an electric field:
• The particles of water become polarized• Orientation.• Random collision resulting in • Settling
Electrical Coalescence
Dipole Coalescence +++ ++ +
--- -- -
+++ ++ +
--- -- -
Force of Attractio
n F = K E2 r6/a4
K = Dielectric constant of
oil E = Voltage
gradient r = Droplet
radius a = Distance
between droplet
centers
Where:
SCHEMATIC FLOW DIAGRAM OF ELECTRICAL DESALTING PROCESS
Desalted crude oil
Effluent waterMixing
valveHeat exchanger
Crude oil
Pressure water
Desalter
Electrical power
Heated to temp in the range 120-130 oC
Water is added to the crude stream and passed through a mixing valve.
The emulsified crude oil is subjected to high voltage (20000 to 24000 volts) electric field.
OPTIMUM PRESSURE FOR DESALTER
FACTORS THAT AFFECT DESALTER OPERATION AND PERFORMANCE
Crude Oil Feed Rate and Quality Temperature/Viscosity/Density Relationships Electrical Field Intensity Wash Water Rate, Quality and Flow Configuration
Emulsion Formation (Pumps, Exchangers, Valves, Mixers)
Control of Water Level and Emulsion Layers Demulsifier Technology and Addition Rate Mud Washing and Brine Recycle
Factors That Affect Desalter Operation And Performance
Performance Evaluation
Desalting efficiency
Si - inlet salt concentration
So-outlet salt concentration
Dewatering/ dehydrating efficiency• Wi - inlet water content• Ww - wash water rate• Wo-outlet water content
Performance Evaluation Mixing index
A – optimum salt content.
So-outlet salt concentration
Metal Contaminants
Metal contaminants such as• FCC Iron• Cadmium• vanadium
Jersey Nickel Equivalent Index
1000 * (Ni + 0.2V +0.1 Fe) Shell Contamination Index
1000 * (14Ni + 14Cu + 4V + Fe)
THANK YOU