Spray Dryer

Spray Dryer

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This is the preferred method of drying of many thermally-sensitive materials such as foods & pharmaceuticals. A consistent particle size distribution is a reason for spray drying some industrial products such as catalysts. Air is the heated drying medium; however, if the liquid is a flammable solvent such as ethanol or the product is oxygen sensitive then nitrogen is used.

A spray dryer takes a liquid stream & separates the solute or suspension as a solid & the solvent into a vapour. The solid is usually collected in a drum or cyclone. The liquid input stream is sprayed through a nozzle into a hot vapour stream & vaporised. Solids form as moisture quickly leaves the droplets. A nozzle is usually used to make the droplets as small as possible, maximising heat transfer & the rate of water vaporisation.

Application of Spray Dryer

  • Perfumes
  • Ceramics & Materials
  • Soaps & Detergents
  • Blood
  • Beverages
  • Flavours & Colourings
  • Milk & Egg Products
  • Plant & Vegetable Extracts
  • Pharmaceuticals
  • Heat Sensitive
  • Polymers & Resin
  • Dyestuffs
  • Foodstuffs
  • Adhesives
  • Oxides
  • Textiles
Image of Inert loop

Spray Dryer LAB SCALE

Variants: 0.5 ltr to 1.5 ltrs/hr water evaporation rate.

  • Attributes:
  • CGMP Model.
  • For Aqueous & Solvent Feeds.
  • Hot Air Flow : Co-Current / Counter Current.
  • Nozzle Type: Two Fluid / Three Fluid.
  • Orifice Diameter: 0.5 to 2 mm with D-Blocker Assembly.
  • Ultrasonic Atomizer with Generator.
  • Integration of Hot Plate with Magnetic Stirrer.
  • Inert Loop System (Optional).
  • PLC Based/Scada / 21 CFR Compliance (Optional).
  • Containment Model Possible with Isolator Chamber.
  • Complete unit on Wheels.
  • Minimal Floor Area Consumption.

Spray Dryer PILOT SCALE

Variants: 5 ltrs to 25 ltrs/hr water evaporation rate.

  • Attributes:
  • CGMP Model.
  • For Aqueous & Solvent Feeds.
  • Multiple atomization techniques possible.
  • Hot air flow type mixed flow/co-current/counter current.
  • Handling of high potend drug possible.
  • PLC Based/Scada/21 CFR Compliance (Optional).
  • Maximum inlet temperature 300°C.
  • Twin Cyclone Possible for better collection efficiency.
  • Control over RH %.
  • Inert Loop System (Optional).
  • Minimum air pollution controlled through. Filteration / Scrubbing.
  • CIP/WIP Possible.
Image of spray dryer pilot scale
Image of spray dryer production scale

Spray Dryer PRODUCTION SCALE

Variants: 50 Itrs to 100 Itrs/hr water evaporation rate.

  • Attributes:
  • CGMP Model.
  • For Aqueous & Solvent Feeds.
  • Multiple Atomization techniques possible. Integrated Fluid Bed/Static/Vibratory Continuos Dryer Possible.
  • Maximum inlet temperature 300°C. Twin/Triple/Quadrupal Cyclones Possible for better. Energy Efficient Technology ensuring Low Energy Consumption. Control over critical Process Parameters to achieve the Particle Properties.
  • Inert Loop System (Optional).
  • Minimum Air Pollution through Filtration / Scrubbing. Built in CIP / WIP Possible.

There Are 4 Types Of Atomization Techniques

Image of spray dryer pressure nozzle

Pressure Nozzle

  • A spray is created by forcing the fluid through an orifice. The energy required to overcome the pressure drop is supplied by the spray dryer feed pump.
  • The narrowest particle size distribution is possible with this technique. Must be used when minimization of "fines" is important to the product.
  • The average particle size produced, for a given feed is a function of the flow per nozzle & the spraying pressure. Spraying pressure depends on feed characteristics & desired particle size, & can range from 300 to 3,000 PSI. The most energy efficient of the atomization techniques.
  • Requires a positive displacement, high pressure feed pump, such as a plunger pump or a piston diaphragm pump. Requires routine changing of the nozzle internal pieces, usually made of tungsten carbide. Changing schedule depends upon the application.
  • Requires a minimum of approximately 0.10 GPM feed rate, depending upon the size of un-dissolved particles in the dryer feed, due to potential plugging with the small orifice required.
  • With multiple nozzle spray dryers, a problem with one nozzle does not shut operations down. Control of spray dryer wall buildup can be achieved through variations of the spray angle.

Two-Fluid Nozzle Atomization

  • A spray is created by contacting two fluids, the feed & a compressed gas The atomization energy is provided by the compressed gas, usually air. The contact can be internal or external to the nozzle.
  • A broader particle size distribution is generated.
  • The average particle size produced for a given spray dryer feed is primarily a function of the feed flow per nozzle, & the compressed gas rate & pressure.
  • The least energy efficient of the atomization techniques.
  • Useful for making extremely fine particles (10-30 micron) because of relatively high wear resistance. Also for the small flow rates typically found in pilot scale dryers.
  • Requires periodic changing of the air & liquid caps.
  • Can typically use any type of spray dryer feed pump.
  • Control of the spray angle is limited.
Image of Two Fluid Nozzle Atomization
Image of spray dryer ultrasonic nozzle

Ultrasonic Nozzle

  • Narrow particle size distribution.
  • Produces soft spray.
  • Continuous operation with out clogging.
  • Desired particles information can be achieved through different spray angle & controlling the frequency.
  • All contact parts are made of titanium.

Rotary Atomizer

  • Disk diameter ranges from 50mm-425mm.
  • Broader particle size distribution.
  • No clogging issue due to high rotation speed.
  • Inter changeable inserts possible to increase or decrease the droplet size.
Image of spray dryer Rotary Atomizer

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