VSD Spray Drying Technology

Particle Production – Process Overview

Spray drying is a method for producing a dry powder directly from a solution or slurry.  In a continuous process, the liquid feedstock is dispersed as a mist of fine droplets into a stream of hot drying gas, all within a cylindrical drying chamber.  In aqueous processes, the drying gas is typically air.  For solutions composed of flammable solvents such as ethanol and acetone, the inert drying gas is nitrogen and the system operated in a closed cycle as illustrated below.  In addition, an inert closed cycle is also useful for drying chemical and biologic materials that are sensitive to oxygen.  Because the kinetics of drying are so rapid, materials are dried in a fraction of a second which helps to make the process viable for thermal sensitive materials such as foods, extracts and other organic substances.

Closed-cycle system shown with organic solvent recovery, inert drying gas (N2) loop and atomizing liquid feed
Open Loop system shown for aqueous processing

Process Example for Drug Products

Flexibility by Design

Our VSD spray dryers were designed with one thing in mind, YOU!  This purpose built, variable scale machine is capable of multiple configurations to suit your everyday processes.

Standard Configuration
This all-in-one portable unit is perfect for product development and for GMP production of clinical supplies and small batch commercial products.

Drying Chamber Extension
Increases residence time to allow lower inlet temperatures. Used with pressure nozzle and pressurized solution delivery vessel.
Improves drying of larger droplets/larger particle size.

Discovery Module

Powder is collected directly on filter disk without using a cyclone to maximize recovery of small samples.

Spray Nozzles and Rotary Atomizers

Freund-Vector spray dryers can operate with a choice of feedstock atomizers or spray nozzles. These include several types of rotary discs, two-fluid atomizing nozzles, single-fluid pressure nozzles, inline mixing nozzles and some commercially available ultrasonic nebulizers as well.  Selection is made based on the feedstock properties and engineered particle requirements such as size, shape, density, solubility and powder flow.  Particles as small as 10 microns are possible and up to 500 microns or more.  The reproducible process yields sharp, consistent particle size distribution.

Types of Spray Nozzles & Atomizers

 

Diagram shows particle size and feed rate for reference only.

Particle sizes are influenced by the liquid properties and choice of nozzles & atomizers.
Consult Freund-Vector for specific applications.

Freund-Vector now offers a range of equipment models and sizes.  Our small-scale VSD-200 is built to the same standards you would expect to find in production class systems.  It is thoughtfully designed for workflow flexibility, from feasibility and formulation up through GMP clinical supplies.  The equipment is configurable with a range of options to help simplify scaleup into our VSD-800 for pilot and small scale commercial production.  Larger models are also available and can be customized to meet specific customer requirements.

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