Detergents - Manufacturing Process

Chemical Process Technology II - Lab

CHEMICAL PROCESS TECHNOLOGY II - LAB

Process description of a Chemical Industry

Submitted to: Ms. Zahra Khan

Date: 13-6-2013

Prepared by:

NOAMAN AHMED CIIT/SP10-BEC-037/LHR

Department of Chemical Engineering

COMSATS Institute of Information Technology

Defence Road off Raiwind Road Lahore

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Noaman Ahmed CIIT/SP10-BEC-037/LHR


Detergents

A detergent is a chemical compound that is commonly used for washing and cleaning of various

materials, surfaces, and products such as clothes, floors, tableware, chemical processing equipment

etc. Detergents can be classified into various types based on their application. Some common types

include,

Detergent Powders – Used for washing clothes

Liquid Detergents – Used for washing tableware

Floor detergents – Used for cleaning floors

Metal cleaning detergents – Specially formulated detergents for cleaning metals

Oil/Grease removal detergents – Specially formulated detergents for removal of oil and grease

stains from clothes and various surfaces

Based on their physical appearance and manufacture, detergents can be classified as,

Powdered detergents

Detergent bars or cakes

Liquid detergents

Detergent paste

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Raw Materials

Detergents may contain varying percentages of linear alkyl benzene sulfonates, sulfates, fatty acids,

fatty alcohols and amines. Most of inorganic materials such as oleum (H2S2O7), NaOH, various sodium-

phosphates and a large number of builders and additives are also added during the manufacture of

detergents.

1. Surfactants

These are organic derivatives such as sodium salts of high molecular weight alkyl sulfates and

sulfonates.

2. Builders

These are inorganic chemicals that are added to detergents. Builders boost detergent power and

prevent re-deposition of soil from the wash water on fabrics. Complex phosphates such as Sodium Tri-

Polyphosphate (STPP) and Tetra-Sodium Pyrophosphate, are used as builders. Although, zeolites are

being used as substitutes for phosphates.

3. Additives

These chemicals enhance the properties of detergents and act as a medium for distinguishing various

brands of detergents based on their additive power and enhanced capabilities. Some common type of

additives include,

Corrosion inhibitors

Fabric shiner

Fabric softener

Bluing agents (improvement of whiteness of clothes)

Enzymes (help remove stains consisting of proteins)

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Chemical Reactions

The chemical reaction that occurs during the manufacture of detergents is linear alkyl benzene

sulfonation. This reaction is divided into one main reaction and two secondary reactions

Main Reaction

Alkyl benzene reacts with oleum to form alkyl benzene sulfonate and sulphuric acid. The reaction is

exothermic.

R-C6H5 + H2SO4.SO3 R-C6H4-SO3H + H2SO4 ΔH = -420 kJ/kg

Secondary Reactions

Alkyl benzene sulfonate reacts with oleum to form di-sulfonate and sulphuric acid.

R-C6H4-SO3H + H2SO4.SO3 R-C6H3-(SO3H)2 + H2SO4

Alkyl benzene sulfonate reacts with alkyl benzene to form sulfone and water.

R-C6H4-SO3H + R’- C6H5 R-C6H4-SO2-C6H4-R’ (1%) + H2O

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Manufacturing Process

Figure 1 –Simplified continuous flowchart for the production of heavy-duty detergent granules (Procter & Gamble Co.) Source: George T. Austin, “Shreve’s Chemical Process Industries”, 3rd ed., 1998.

http://www.google.com.pk/search?tbo=p&tbm=bks&q=inauthor:%22GEORGE+T+AUTOR+AUSTIN%22

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SURFACTANT MANUFACTURE

Sulfonator unit

The main reaction, as mentioned previously, occurs in the sulfonator unit. Alkyl benzene and oleum

are added to the sulfonator unit where the reaction takes place and alkyl benzene sulfonate is formed.

As the reaction is exothermic, cooling coils are integrated with the reactor to cool off the excess heat.

Sulfator unit

The secondary reactions take place in the sulfator and disulfonate and sulfone are formed. Oleum and

the alkyl benzene sulfonate, from the sulfonator, are added to the sulfator unit and maintained at

operating temperature of 55°C.

Mixer

The product streams from the sulfonator and the sulfator are properly mixed in a mixer and passed

on to the surge tank.

Surge Tank and Cooler

The product from the mixer is pumped into the surge tank. The surge tank’s function is to mitigate

pressure variations that occur due to rapid changes in the velocity of the mixer product stream. Once

the required pressure condition is obtained, the product stream is passed on to the cooler where it is

cooled down to a specified temperature. After cooling, the product stream is passed on to the

neutralizer.

Neutralizer

Sodium hydroxide is added to the neutralizer to neutralize the surfactant mixture stream and this

process also helps to clean the mixed stream. Any unprocessed or un-neutralized product is recycled

to the mixer and follows through the surge tank and back into the neutralizer. After the neutralization,

the newly made surfactants are sent to a warehouse or a storage building to be stored as raw material

for detergent manufacture.

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DETERGENT MANUFACTURE

Crutcher

The crutcher is a mixing unit that is steam and water jacketed from inside and is incorporated with

agitators for homogenous mixing. Raw materials for detergents which include surfactants, builders,

and additives are added to the crutcher. Various other chemicals such as colour pigments,

naphthalene and TiO2 are added to the crutcher unit. Naphthalene acts as a germicide. During the

crutching process, water is removed from the detergent mixture and a thick paste is formed which is

then forwarded to a drop tank, which is also used for pressure adjustment of the detergent paste

being pumped into the tank. From the drop tank, the detergent mixture is passed on to the spray

tower.

Spray Tower

The spray tower is usually a 24 m high column-shaped vessel which is primarily used for granulating

the detergent paste/mix. A furnace is integrated with the spray tower and the temperature inside the

spray tower is maintained at 115°C for proper/optimum granulation. Dried granules of acceptable size,

density and shape are obtained at the optimum operating conditions. The spray tower is also

integrated with a cyclone separator and a stack removal system in order to remove light weight

impurities and flue gases, thus forming an environmental protection approach.

Cyclone Separator, Screening and Filtration

The granules from the spray tower are passed on to the cyclone separator which separates the heavy

granules from the light ones on the principle of centrifugal forced separation. The product from the

cyclone separator is subjected to a screening chamber where granules of required size pass through

and the remaining are sent to the filter unit.

The light weighted granules from the cyclone separator are also sent to the filter unit, in order to

separate granules of required size.

Perfume addition and Packing

Finally, perfume and fragrant smells are added to the detergent granules. Afterwards, the granules

are forwarded to the packing section for sale and distribution.

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References

George T. Austin, Shreve’s Chemical Process Industries, 3rd ed., McGraw Hill Publications, 1998.

http://en.wikipedia.org/wiki/Surge_tank

http://en.wikipedia.org/wiki/Detergent

http://en.wikipedia.org/wiki/Surge_tank

http://en.wikipedia.org/wiki/Detergent

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Detergents - Manufacturing Process