This document discusses different types of nozzles used in spray drying processes. It describes rotary atomizers, pressure nozzle atomizers, two-fluid nozzle atomizers, and pneumatic nozzles. Rotary atomizers can handle large feed rates but use more energy. Pressure nozzles have a simple design but are prone to clogging. Two-fluid nozzles produce a range of droplet sizes using compressed air. Pneumatic nozzles also produce very small particles but use more energy. Common applications of spray drying nozzles include dairy products, foods, chemicals, and more.

1. Presented to- Mrs. Neha Singh
Presented by- Ridham Walia
Roll No.- 14/PFT/003
NOZZLE DRYERS

2. CONTENTS
* Spray Drying
* Types of atomizers: Rotary atomizer
* Pressure Nozzle atomizer
* Two- fluid nozzle atomizer
* Pneumatic nozzle
* Common uses
References

3. Spray Drying
Definition-
A special process which is used to transform the feed from a
liquid state into a dried particulate form (Powder or Particles)
by spraying the feed into a hot drying medium.

5. Contd.
*Atomizer or spray nozzles are used to disperse the liquid or slurry into a
controlled drop size spray.
*Most common of these are rotary disks and single-fluid high pressure swirl
nozzles.
*Atomizer wheels are known to provide broader particle size distribution.
*Alternatively, for some applications two-fluid or ultrasonic nozzles are used.
*Depending on the process needs, drop sizes from 10 to 500 µm can be achieved
with the appropriate choices.
*Most common applications are in the 100 to 200 µm diameter range. The dry
powder is often free-flowing.
*For many industries a standard pressure nozzle operating in the 3,000-4,000 psi
and 175-400°F will excel.

6. Types of atomizers: Rotary atomizer
*Advantages:
•Handles large feed rates with single wheel or disk
•Suited for abrasive feeds with proper design
•Has negligible clogging tendency
•Change of wheel rotary speed to control the particle size distri
bution
•More flexible capacity
*Limitations :
•Higher energy consumption compared to pressure nozzles
•More expensive
•Broad spray pattern requires large drying chamber diameter

7. Pressure nozzle atomiser
*Liquid is forced at a high pressure (700-2000 kPa) through a small
orifice. Nozzles have a maximum flow rate of 1 L/h.
*Typical pressures range from 300 to 4000 psi.
*Dryers with pressure nozzles typically contain drying chambers that
are narrow in diameter and tall in height.
* The small orifice facilitates clogging, so pressure nozzles are
seldom used when the feed is highly concentrated.
*Grooves on the inside of the nozzle cause the spray to form into a
cone shape and then reform to use the full volume of the drying
chamber.

8. Pressure Nozzle
*Advantages:
* Simple, compact and cheap
* No moving parts
* Low energy consumption
*Limitations:
* Low capacity (feed rate for single nozzle)
* High tendency to clog
* Erosion can change spray characteristics

9. Two - fluid nozzle atomiser
*Compressed air creates turbulence, which
atomises the liquid.
*The operating pressure is lower than the
pressure nozzle, but a wider range of droplet
sizes is produced.
*Both types of nozzle atomiser are susceptible to
blockage by particulate foods, and abrasive
foods gradually widen the apertures and
increase the average droplet size.

10. Pneumatic nozzles

11. *Advantages:
* Simple, compact and cheap
* No moving parts
* Handle the feedstocks with high‐viscosity
* Produce products with very small size particle
*Limitations:
* High energy consumption
* Low capacity (feed rate)
* High tendency to clog
Pneumatic nozzle

13. Common Uses / Installations of
Spray Drying Nozzles
Dairy Industry: drying full cream and skim milk, cheese, whey, and
baby formula.
Foodstuffs: instant coffee, edible plant proteins, tomato, egg, baking
products, yeasts, and other extracts.
Chemical industry: polycarbonate and polyvinyl products among many
other organic and inorganic chemicals. Ceramics, soaps and detergents,
agricultural products, dyestuffs, mineral and ore products, and cellulose.

14. REFERENCES
 en.wikipedia.org
 ppt on spray drying of foods
 PDF file on Classification of dryers
 Spray drying technology: An overview
Indian Journal of Science and Technology