GLYCERINE DISTILLATION

PLANT

MMuhammad uhammad FFahad ahad AAnsari nsari 12 12 IEEM 14IEEM 14

Method Of Production: The Glycerol is derived from the direct

Saponification of Fats & Oils with Caustic Soda and recovery as a By-product from the resulting Soap.

During the Saponification Process, glycerol is librated and then extracted by the counter current washing of soap to obtain Spent Lye which contains maximum concentration of glycerol in water and impurities i.e. Soap, fatty acids, color bodies, insoluble materials and phosphorous and nitrogen compounds.

Saponification Reaction:Saponification Reaction:

Triglyceride + Caustic Soda ---- Glycerol + Soap

Glycerine Manufacturing Process:Glycerine Manufacturing Process: The Process Of Recovering glycerol

from soap lyes can be divided into the following stages;

• Chemical Treatment (Purification Of Soap Lye)

• Evaporation (Concentration Of Lye To Crude Glycerine)

• Separation Of Salt And Preparation Of Brine• Crude Glycerine To Produce marketable

Grades

1. Purification Of Soap Lye:1. Purification Of Soap Lye: The Chemical Treatment Of Soap Lye is designed to

maximize the removal of dissolved soap and other organic impurities prior to evaporation and distillation. The most common method for the purification of Soap Lyes consist of two stages.

• The addition of Hcl (acid) and a Alum (coagulant) followed by filtration

• The addition Alkali (Caustic Soda) to the filtrate to precipitate the excess of Coagulant followed by filtration.

• Then the final filtrate is used as the feed to the evaporators.

Filtration: Filtration is important in the Chemical treatment. When the

well agitated mixture is pass through the filter a clear filtrate is produce. Plate & Frame type filter is commonly used.

2. Concentration Of Glycerol 2. Concentration Of Glycerol Liquors:Liquors:

Purified soap lye are concentrated by evaporation under reduced pressure (vacuum) to produce crude glycerine containing 80-85% glycerol. Evaporation may be achieved by two stages.i.e Single Effect Evaporator(40% half crude) and then followed by finishing to 80-85% concentration at Double Effect Evaporators.

Operation: In the evaporation process, Concentration of glycerol is

accomplished by boiling out water. With soap lye liquors the evaporation must be carried out in such a way that the salt, as it Crystallizes from hot liquors,can be removed without allowing it to be deposited on the heating surfaces of the evaporator.

Single Effect Evaporation: Steam is used as a heating medium in an Internal Shell

and tube heat exchanger.The liquor goes through the tubes by natural circulation.Salt is removed from the system using a salt box.

Double Effect Evaporation: This type consists of two evaporators coupled in series.

Live steam is admitted to the first effect (evaporator). The resultant vapour is used as a heating medium in the Second effect. The transfer of process liquor between effects is achieved by utilizing the difference in pressure in each effect. Effective condensate removal is necessary between each effect.The second effect usually operates at about 760 mm Hg of vacuum,and the first effect about 300 mm Hg lower. Salt is continuously removed from the system along with glycerol liquors.

Salt Crystallization: During the evaporation process,as water evaporates, salt

and glycerol concentration increases and solid salt starts crystallizating.

The solubility of salt is seldom effected by temperatures, and is principally controlled by the concentration of glycerol present. Salt can be removed by using Salt Box.

Salt Box: This is fitted to the bottom of the evaporator. It is

designed to steam the glycerol out of the salt, and return the liquor to the evaporator.

Storage and Handling Of Crude: After that, Crude glycerine is stored into large conical

tanks to allows a large amount of salt is settle down for at least six hours is recommended that.

3. Refining Of Glycerine:3. Refining Of Glycerine: Refining Of Glycerol is accomplished by Steam

distillation to separate high boiling, heat sensitive substances like glycerol from water soluble and other impurites.The distillation process utilizes two principles, Steam distillation coupled with fractional condensation, followed by fractionation to produce extra pure refined glycerine.

Distillation: The concentration of glycerol in the crude feed to the

still is around 85-88%. To distill glycerol, it must be heated to a temperature where its vapour pressure is greater than the partial pressure of the glycerol vapours in the still. The vapour pressure of pure glycerol is 760 mm (atmospheric) at 270 Centigrade. Since glycerol polymerizes at 160 Centigrade, the partial pressure of glycerol is reduced by Vacuum System, maintaing the same total pressure, and thereby allowing the glycerol to vaporize at a lower temperature.

Chemical Reactions: At the Still temperature, glycerol polymerizes in the

presence of caustic soda to form polyglycerols which adversely effect the yield.

Condensation of Vapors: After the vapors leave the still, they must be condensed.

Vapors contain water vapor and volatile impurites as well as the glycerol. Success in producing good quality of refined glycerine lies in the effectiveness of partial condensation. As the vapors pass through these condensers, partial condensation takes place. Since the vapor pressure of glycerol is much higher than that of water, relatively pure glycerol is condensed at higher temperatures. Volatile substances close to the boiling points of glycerol will condense along with pure gkycerine, which acts as an impurity needing either redtisllation, fractionation, bleaching deodorization.

Product removed from the condenser (99.5% wt. percent) are subjected to a continuous Carbon Bleaching.

Deodorization: Impurities found in crude Glycerine, especially MONG (Matter

Organic Non Glycerol), it can cause odor, taste, color problems in the refined Product. Trimethylene glycol, a constituent of MONG, often effects the color of the product.

In the Deodorizer (Carbon Bleaching System), 3-5% Charcol (Activated Carbon) is introduced in the Bleacher to improve the color.

Such an effectiveness system to produces a product of 99.5% high quality of CP (Chemically Pure) Grade Glycerine.