- •Contents
- •Preface
- •1. Classification and physicochemical properties of surface-active substances
- •1.1 Synthetic detergent production
- •1.2 Classification of surface-active substances
- •1.3 Detergents and surfactants
- •1.4 Synthetic surfactant or soap
- •What's the difference?
- •1.5 Soaps and detergents
- •Cleansing action of soap
- •1.7 Synthetic detergents
- •1.8 Advantages and disadvantages of synthetic detergents with respect to soaps
- •Washing powders
- •1.9 Structure and properties of surface-active substances
- •Critical concentration of cluster formation
- •Control questions
- •1.10 Surface tension
- •1.11 Physical and chemical action of washing substances and detergent solutions
- •Control questions
- •1.12 Solubilization
- •1.13 Washing action
- •Control questions
- •2. Synthetic detergents composition
- •2.1 Inorganic compounds in synthetic detergent compositions
- •Alkaline salts of inorganic acids
- •Purposes of alkaline electrolytes
- •Control questions
- •2.2 Organic components used in synthetic detergents structure
- •Main components of synthetic detergents’ compositions
- •Hydrotropic substances.
- •Control questions
- •2.4 Production of enzyme-based detergents
- •2.5 Enzyme stabilization
- •2.6 Applications of enzyme-based detergents
- •3. Synthetic detergents production
- •3.1 Reception, storage and preparation of raw material for synthetic detergent manufacture
- •3.2 Technology of compositions preparation
- •Control questions
- •3.3 Classification of synthetic detergents. Kinds of pollutions.
- •Control questions
- •3.4 Technology of washing compositions drying
- •3.5 Spray drying technology
- •Control questions
- •3.6 Basic technological circuits of powdery synthetic detergent manufacture by periodic and continuous ways
- •Control questions
- •3.7 Capital equipment at granulated synthetic detergents manufacture
- •3.8 Technology of drying in fluidized layer
- •Control questions
- •3.9 Technology of granulated synthetic detergents by combined methods
- •3.10 Packaging of powders
- •Basic raw material
- •Auxiliary raw material
- •Control questions
- •4.3 Chemistry and technology of soap production
- •Control questions
- •4.4 Cake synthetic detergents
- •4.5 Production of cake synthetic detergents by forming method
- •4.6 Production of cake synthetic detergents by pressing method
- •Control questions
- •4.7 Manufacture of paste and liquid detergents
- •4.8 Compositions and production technology of paste-like synthetic detergents
- •Control questions
- •4.9 Compositions and technology of liquid synthetic detergents production
- •Control questions
- •5. Chemical means of hygiene and cosmetics
- •5.1 Shampoos
- •Jump of quality
- •Electrostatics laws in operation
- •To expect, to prevent
- •Laziness -- the engine of progress
- •Content and form
- •5.2 Teeth care means
- •Literature list:
Control questions
Which components take part in washing process?
What is pollution? What kinds of pollutions you know?
Call water-soluble organic and inorganic pollutions.
Which compounds concern to water-insoluble organic and inorganic compounds?
Kinds of synthetic detergents?
Lumpy synthetic detergents. Its advantages and disadvantages in comparison with soap.
Content of active substance in lumpy SD and lumpy soaps.
What are the most widespread form of synthetic detergents? Which methods are used for preparation of powder and granule synthetic detergents?
Which kinds of surface-active substances are used for production of paste synthetic detergents?
Properties of liquid synthetic detergents.
Classification of synthetic detergents according to a purpose.
3.4 Technology of washing compositions drying
Modern synthetic detergents make basically as granulated powders at drying of washing compositions. Depending on a way of heat supply for evaporation of liquid and a way of removal of formed vapours distinguish gas and contact ways of drying. At gas (convective) drying heat is transferred by gas (heated air, smoke gases, nitrogen, etc.), which is directly touched with dried material. Formed at evaporation steams of liquid are mixed with a stream of gas and go away from system. At contact drying heat is transferred to dried material by the hot surface warmed by the heat-transfer medium. As the heat-transfer medium are used saturated water steam which is condensed in this process. At contact to surface of heat exchange the material get warm, vapours of liquid go away from the dryer and can be directed on condensation or are returned in a work cycle. In contact dryers vacuum is frequently created that allows to raise of process speed and to carry out it at lower temperature.
Practically by manufacture of synthetic detergents convection drying by heated air and hot smoke gases is applied.
3.5 Spray drying technology
Spray drying is carried out in a vertical cylindrical device. For creation of a big surface of contact of heat-transfer agent with particles of suspension it is sprayed by atomizers. Depending on sizes of industrial drying devices their productivity as follows:
Table 3. Dependence of productivity of drying apparatuses from their sizes.
General height, m |
26,3 |
32 |
39,6 |
Height of a drying part, m |
10 |
16 |
19 |
Diameter of a drying part, m |
5,7 |
8 |
9 |
Volume of a drying part, m3 |
255 |
612 |
803 |
Number of atomizers |
10 |
20 |
20 |
Pressure upon submission of a composition, MPa |
7 |
7 |
8 |
Yield of a powder, thousand tons per year |
30 |
40 |
60 |
The spray dryer (which is named a drying tower) is supplied with atomizers with diameter of aperture 2,5-3,5 mm productivity 1,2-1,5 t/h. Atomizers are located under the corner 900 to a wall of tower that at dispersion the drops of composition stuck to a wall less. In manufacture of powder synthetic detergents atomizers of swirl type are used. Basic elements of such atomizer are the chamber and the nozzle. The composition is entered in swirl chamber of atomizer under pressure 6-8 МПа. As a result of rotary movement on exit from nozzle the cone-shaped hollow film is formed. This film on distance 1m from nozzle is broken up on separate drops. These drops at drying are turned to granules of average diameter 50-200 microns. Particles in size less than 0,4 mm are difficultly besieged and carried away in atmosphere.
In quality of heat-transfer agent at spray drying of synthetic detergents flue gases are applied. Gazes are formed at burning of gaseous or liquid fuel. Heat-transfer agent in a drying tower can move in counter-current flow or in co-current flow movement concerning movement of particles of composition. Parameters of drying determine the direction of movement of heat-transfer agent in spray dryer, its quantity and temperature and influence on characteristics of granules.
The counter-current flow movement of heat-transfer agent is used in most case.
At counter-current drying of composition drying of particles occurs in zone of maximal temperature of heat-transfer agent. Humidity of sprayed particles thus achieves 17-20% that corresponds to destruction of crystal hydrates.
At co-current drying suspension drops at once get in zone of high temperatures. In the given zone there is the removal both superficial and capillary moisture. It leads to destruction of drops and formation of plenty of fine particles, hence, and plenty of a dust. It causes low density of a ready product. Besides, increase of number of fine particles increases speed of removal of crystallization water and speed of decomposition of pentasodiumphosphate up to pyrophosphates. So, at moisture content in powder 11, 9 and 5 % (weights) the degree of hydrolysis of pentasodiumphosphate makes 20, 33 and 45% accordingly. It is obvious, that thus complex-forming ability of composition is decreased. Most strongly the crystallization water is kept by carbonate of sodium, therefore its quantity in a powder should be possible minimal. At the counter-current of drying the temperature influences on decomposition of pentasodiumphosphate less. In this case more important factor is the quantity of heat-transfer agent. Increase of the input of heat-transfer agent increases a degree of decomposition of pentasodiumphosphate.
Usually the duration of drying of composition at temperature 250-4000С on inlet in tower makes 15-30 seconds; thus the temperature in dispersion zone is reduced up to 160-2200С.
With reduction of water content in submitted composition it is possible to reduce the temperature of drying and to raise the productivity of dryer. Productivity of dryers depending on the content of water in composition changes as follows.
Table 4. Dependence of SD output from water content in compositions.
Content of water, % (mass) |
Output of powder (kg/h) after dryers with designed power on evaporated water |
|
|
3000 |
5000 |
45 |
4715 |
7815 |
40 |
6000 |
10000 |
35 |
7800 |
13000 |
30 |
10500 |
17500 |
Increase of productivity of a drying tower without increase in sizes is achieved by tangential submission of heat-transfer agent, it provides the uniform drying on section of device. The density of powder at counter-current drying makes 0,4-0,6 kg/m3, at co-current drying - 0,2-0,4 kg/m3.