Mubashar khurshid sp12-bec-031Umair ashraf

sp12-bec-091

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Dewaxing

CONTENTSIntroduction

Process of dewaxingChilling and pressing processSolvent dewaxingUrea dewaxingDeoilingconclusion

INTRODUCTION

Removal of waxes from petroleum product(mainly lubricant oil) is called dewaxing.

PURPOSE OF DEWAXING Over laping of boiling point with crude oilAt low temprature the waxes precipate and crystalizeTo maintain fluidity at low temprature

THE METHOD OF DEWAXINGThere are three method of dewaxing

Chilling and pressing processSolvent dewaxing processUrea dewaxing process

CHILLING AND PRESSING PROCESS

The oldest methodWaxes bearing oil are refrigerated by double pipe heat exchangerCrystalise and precipates are madeWaxes are separated by filteration and settling

DRAW BACK OF CHILLING AND PRESSING PROCESSAt cooling, the viscosity of oil increaseFilteration become difficultTime consumingCostly

PROCESS SOLVENT DEWAXING Solvent dewaxing is used to remove wax from

either distillate or residual basestock at any stage in the refining process.

There are several processes in use for solvent dewaxing, but all have the same general steps, which are:: mixing the feedstock with a solvent; precipitating the wax from the mixture by

chilling; and recovering the solvent from the wax and

dewaxed oil for recycling by distillation and steam stripping.

PROCESS SOLVENT DEWAXING Usually two solvents are used: toluene, which

dissolves the oil and maintains fluidity at low temperatures, and methyl ethyl ketone (MEK), which dissolves little wax at low temperatures and acts as a wax precipitating agent.

Other solvents sometimes used include benzene, methyl isobutyl ketone, propane, petroleum naphtha, ethylene dichloride, methylene chloride, and sulfur dioxide.

In addition, there is a catalytic process used as an alternate to solvent dewaxing.

SOLVENT DEWAXING UNIT

SOLVENT DEWAXING UNIT

PROPERTIES OF DEWAXING SOLVENT

It should miscibilty with oilIt should negligible solubility of waxesIt should thermal stable and non corrosiveIts boiling point should be low so to easily separate

UREA DEWAXING PROCESS

urea form solid filterable complexesThis process is effective on higher stocksThis is important for low cold test oil from light oilWaxes have high percentage of straight chain hydrocarbon there fore urea dewaxing is effective

UREA DEWAXING PROCESS

Dewaxing ProcessesDewaxing is important from two points of view: producing products with suitable pour points from waxy feedstock. particularly in the case of higher average molecular weight petroleum distillates and distillation residues no sharp dividing line can be drawn between the hydrocarbons forming solid paraffins and those that cannot be considered as solid.

Dewaxing Operation

Dewaxing Processes Methods Dewaxing Crystallizer

1. Large and well-developed crystals can be readily pressed and filtered.

2. The needle-shaped crystalline types can be easily sweated 3. Microcrystalline paraffin waxes cannot be separated by filter

pressing, but are readily separated by centrifuging.Dewaxing processes using solvents In these processes, organic solvents are used as diluents which, at the temperature of filtering, dissolve paraffin waxes only to a very slight extent, while they are good for dissolving the other components of lubricating oils. Rotary filters are mostly used to separate crystallized paraffin wax.

1. Methyl ethyl ketone dewaxing2. The propane dewaxing process3. Dewaxing with a mixture of propylene and acetone4. Dewaxing with chlorinated hydrocarbons5. Dilchill dewaxing process6. Filter aids

De-oiling and fractional crystallization of slack waxes and petrolatumsOil and low-melting fractions removed from the slack wax. The process is called de-oiling.De-oiling is fractional crystallization of slack or paraffin waxes by their melting point.Slack waxes obtained from light distillates by cooling and pressing were formerly-oiled exclusively by a process called sweating.

CONCLUSION

In deed the dewaxing is important process in crude oil separation in different component because by dewaxing tranportation become easyIn cold temp

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