Technology
Spray drying is the most widely used industrial process involving particle formation and drying. It is highly suited for the continuous production of dry solids in either powder, granulate or agglomerate form from liquid feedstocks as solutions, emulsions and pumpable
suspensions. Therefore, spray drying is an ideal process where the end-product must comply to precise quality, and particle shape. Spray drying involves the atomization of a liquid feedstock into a spray of droplets and contacting the droplets with hot air in a
drying chamber, The sprays are produced by either rotary(wheel) or nozzle atomizers. Evaporation of moisture from the droplets and formation of dry particles proceed under controlled temperature and airflow conditions. powder is discharged continuously from
the drying chamber, Operating conditions and dryer design are selected according to the drying characteristics of the product and powder specification.

Consists of

Principle

1、Atomizing
Used to feed liquid atomizer (which may be the solution, emulsion, suspension or molten liquid) dispersed into a uniform droplet;

2、Contact Droplets with Hot-air
All hot air from the hot air distributor into the drying chamber after the wind, and mix according to certain rules of droplet movement (air and droplets can form and flow of contacts, it can be countercurrent or mixed);

3、Drying Process
The droplet surface area as great in the temperature and humidity on the hot air has significantly with the “gradient”, thus strengthening the “thermal mass” transfer process so that the rapid evaporation of water contained in the droplet evaporation (the process of only a few seconds to tens of seconds) to form product particles;

4、Seperate product from Air
Product powder separated from the air, wet exhaust discharge standard after a thorough dusting.

Atomization
The formation of sprays having the required droplet size distribution is vital to any successful spray dryer operation so that powder specifications can be met. Atomization is a high technology area where Niro has played a central role in the development and use of nozzles and rotary atomizers in spray drying.

Atomizer
Three types of atomizers are used in industrial drying
● Rotary atomizer
Atomization by centrifugal energy
● Pressure nozzle
Atomization by pressure energy
● Two-fluid nozzle
Atomization by kinetic energy

The choice of atomizer depends upon the properties of the feed and the dried product specification. In cases where more than one atomizer type is suitable,the rotary atomizer is generally preferred due to it's greater flexibility and ease of operation.The
adcantages include:
● Handling of high feed rates without need for atomizer duplication
● Handing of abrasive feeds
● No blockage problems
● Low pressure feed system
● Ease of droplet size control through wheel speed adjustment

Airflow
The initial contact between spray droplets and drying air controls evaporation rates and product tempera-tures in the dryer. There arethree modes of contact:

Co-Current

Drying air and particles move through the drying chamber in the same direction .Product temperatures on discharge from the dryer are lower than the exhaust air temperature,and hence this is an ideal mode for drying heat sensitive products.When operating with rotary atomizer,the air disperser creates a high degree of air roration,giving uniform temperatures throughout the drying chamber.However,an alterna- tive non-rotating airflow is often used in tower or Filtermat-type spray dryers using nozzle atomizers with equal success.

Counter-Current
Drying air and particles move through the drying chamber in opposite directions.This mode is suitable for products which require a degree of heat treatment during drying.The temperature of the powder leaving the dryer is usually higer than the exhaust air temperature.

Mixed Flow
Particle movement through the drying chamber experinces both co-current and counter-current phases.This mode is suitable for heat stable products where coarse powder requirements necessitate the use of nozzle atomizers,spraying upwards into an incoming airflow,or for heat sensitive products where the atomizer sprays droplets downwards towards an integrated fluid bed and the air inlet and outlet are located at the top of the drying chamber.

Spray Drying System
The essential elements of the spray dryer: atomizer, air disperser, drying chamber, inlet and exhaust air handling are combined into a system that meets individual operational safety, environmental protection, and powder handing requirements. All systems can be
provided with post-treatment equipment: fluid bed dryer/cooler, agglomerator, de-duster and conveyor.

Advanced Industrial Automation Control
Automation control system adopted the Siemens PLC controller’s programmable logic controllers S7-315 2DP based programming software STEP7 5.5. with starting，stopping and interlock device, PID loop control of process parameters and alarm processing functions. First, the control system is to accept the command of operator , and then if the conditions are according to the logic of the scene to gather information to determine the process to be executed by the program are met. If the condition is satisfied, the control program in a specific order output signal to enable or disable the control process of various types of equipment.

HMI human-machine interface is using the Siemens SIMATIC WinCC’s configuration software to achieve drying equipment control system to operate, monitor, analysis data, record and print. It completed the combination of on-site equipment and operating personnel. Through HMI, the operator can enter a command, or a different formula or process parameters to complete the different products; at the same time getting information about system status; and query the system information about the current production process or retroactive (query) historical production important data recording process; in case of abnormal, the system will send an alarm signal.
Field data gathering via S7-315 PLC, with the module CP343-1 via TCP / IP, information will be collected and displayed on the computer whichconfiguration software is WinCC.
Data in the PLC will also be sent to a remote computer through a collection of industrial router (HUB).
PLC software and PC software programming with the program structure S88, modular design.
For different controlling objects, it wrote motor templates (including the inverter control and direct control of two starts), the valve templates, analog input modules, analog output modules, PID control loops templates.
For process control, using Siemens’s GRAPH to program, making the process more clear.
The dry production process is refined into several smaller processes (such as cold run, run hot, running water, solid run, drying, etc.).


Automation control system is to monitor the spray dryer process parameters to ensure the well operation of the equipment, and the product with constant quality.

Drying Media

Open Cycle System

Featuring once-through airflow with exhaust to atmosphere.The majority of industrial spray dryers handle aqueous feedstock and use this system. Both direct and indirect air heating are applicable.Exhaust air cleaning in cyclones.bag filters,electrostatic precipitators,
and scrubbers.

Closed Cycle System

Featuring drying in an inert gas atmosphere where nitrogen recycles within the dryer. This system must be used for the spray drying of feedstock containing organic solvent or where the product must not contact oxygen during drying.Closed cycle plants are gas
and powder tight,and are designed to the strictest safety standards.The inflammble solvent vapours are fully recovered in liquid form.

Semi-Closed Cycle

Featuring either the partial recycle mode (recycle of up to 60% of the exhaust air as inlet air to the dryer,for effective waste heat utilization) or the self-inertizing mode,where direct air heating and a minimal air bleed create the low oxygen atmosphere necessary for
drying aqueous feedstocks that form explosive powder-air mixtures.If odour is generated during drying,the small vol

Aspetic

Featuring sterile feed atomization and air filtering system. These dryers are used where any form of powder contamination must be avoided. They are fabricaed to special standards of finish and operate under a slight pressure. Fully automatic cleaning and
sterilization systems are available. Plant layout is integrated with the laminar flow packing room.


Several Industrial Applications of Spray Dryer
Rotary spray dryer
● Precision pharmacy spray dryer
● Aspetic spray dryer
● Nozzle spray dryer
● Precision fluid-bed spray dryer
● Closed cycle spray dryer
● Spray dryer for Fine ceramics
● Spray heat reactor
● Spray cooler
● Gas-reacting spray dryer
● Gas-cooling spray dryer

Typical Sets Introductions

Standard Rotary Spray Dryer

The rotary spray dryer is designed to dry the liquid material into fine powder. Droplets through the atomizer on the top of the drying chamber. It is featured with quick drying process, high efficiency and advanced automatic-control, all this makes the powder have good dispersity flexiability and dissolvability. This system can be used extensively in chemical industry, light industry, food process, pharmacy and biochemical industry.
Scope of the supply: Water evaporation capacity: 5～50,000 kg/h

Nozzle Spray Dryer System

This kind of dry system is designed to complete the drying process by forcing liquid material into the middle of the drying chamber where the spray nozzle shall atomize it into fine spray which will be mixed with the hot air coming from the system features good flexiability and uniformed graininess. This system can be used in porcelain and ferrite magnetic material industrial trades .
Scope of the supply: Water evaporation capacity:12.5～50,000kg/h

Nozzle Spray Drying System

This kind of system is designed to have the dry process by forcing liquid material under the pressure into the spray nozzle on the top lf the drying chamber, where the liquid material shall be atomized to fine spray and flowing down parallelly with the hot air coming from the top .Featuring with high dust-collecting rate, nonadhesion- to-wall, energy thermosensitive material and also can be used in food process, dyestaff and medium material process.
Scope of supply: Water evaporation capacity:50-12000kg/h

Precision Pharmacy Spray Dryer

This system is designed specially for giving a spray dry to Chinese Traditional Medicine(CTM) herb process. Provided with air wiper and cold-air jacket, the system is preferred dryer for thermosensitive material or the material with softening point: Any gas entering high efficient filters .All the pipes in the system are convenient to clean, asepticises, take off and meet the GMP Requirements.

Closed Cycle Spray Dryer

With inert gas as the circulating gas for the system, it has the performance to keep dry material well preserved and enable a repeti-tivuse of the medium. The system can be used for drying volatile material or the raw material inhibitten to be contacted with oxygen gas in process, or inflammables and explosive material, or the material, which may make out odour and poison gas during drying process.
Scope of Supply: Solvent evaporation capacity:50-2,000kg/h

Precision Fluidized Spray Dryer

This system is designed to make pills by mixing fine powder in the drying column with atomixed liquid spray. Featuring with the functions to make even-sixe pills and to be adjustable for pill size, the system can be used in chemical industry, food process and pharmacy industry.
Scope of Supply: Water evaporation capacity:5-12000kg/h


Spray Dryer Application
◆ Food：Amino acide, products related to amino acids, natural, seasoning, protein foodstuffs, miso, soy based products, vital gluten, soy bean protein, soup mixes, extract, etc.
◆ Carbohydrate：Glucose, thick malt Syrup, corn steep Liquor, corn syrup, Gum aiabic, Pectin,Sweetened starch Liguid, caramel, Alpha starch, colored Starch, etc.
◆ Ceramics：Aluminum oxide,Aluminum silicate,Ferrite,talc Zirconium,PZT,zinc Pxide,ma gnesia,Beryllia,Titanium oxide,Barium carbonate,Barium titanate,Magnesium titanate,Various oxidized Metals,Tiles,clay,Refractory clay,Kaolin,dolomite,Special metals,etc.
◆ Pharmaceutical product：Algae,antibiotics,Drugs,enzymes,Tabletting Constituents yeast,Vaccines,vitamins ,Aluminum hydroxide.

Chemical product：
Organic:
Organic catalyst, Melamine resin, urea Resin, phenolic resin, Surface activator, Vinyl chloride, P.V.C. lignin,Ribonucleic acid, Pigment, cosmetic, Pentachlorophenol, Sodium, sodium Nitrohumic acid, Sodium phthalate, Neutral detergent, Oil and fat, fatty Acid, monoglyceride Stearic acid, urea, Waxes, perfumds, etc.
Inorgani:
Methanoic silica, aluminate, magnesium, calcium chloride, cements, copper oxide, graphite, kaoline, lime slurry sodium phosphate, potassium phosphate, powdered meatals, silicate of soad, calcium carbonate, tungsten carbide, potassium pyrophosphate, potassium fluoride, sodium tripolyphosphate, white carbon, ammonium sulfate, diammonium hydrogen sulphate, ingorganticpigment, catalyst, P.A.C., ferrous oxalate, neochromnite, etc.

Liquid waste：

Brewing waste water, Starch waste water, Fermentation waste water, black liquid, etc.

Others：

Baby food, Cheese, Yeast, perfume, Enzyme, Fish or meat Extract, Seaccharin, Chorella, cocoa milk, Coffee, Coffee whitener, Tea extract, Glucomannan, Full fat milk, Skim milk, Egg, Beef broth, Fish proteins, Flavorings, Food coloring, Garlic, Fruit, Vegetables, Additives for Foodstuffs, Animal Protein, Blood, Gelatin, etc.

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