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