• Rapid drying of many types of chemicals, foodstuffs and minerals with up to 80% moisture content
• Drying of heat sensitive materials at low temperatures under accurately controlled and uniform conditions.
• Determining the moisture content of substances such as adhesives, tobacco, dried foods and building materials.
• Mixing of compounds that are hydroscopic e.g. NH₄NO₃, KOH or air sensitive ( by fluidising with an inert gas ).
• Converting cake or precipitate from chemical or pharmaceutical production into powder or granular form.
• Removing solvents such as methanol or heptane from plastics and polymers by accelerated vaporization.
• Determining thermodynamic parameters for industrial dryer design e.g. heat/mass balances, thermal efficiency and calculating heat transfer coefficients.
• Obtaining uniform coatings of evaporation residues on particles.
• Simulating large scale process installations to monitor quality, efficiency and carry out small batch treatment.

Nylon and terylene are normally chosen as filter bag materials; nylon is resistant to alkali vapours while terylene shows greater stability with acids. Polypropylene is inert to most chemicals but degrades more rapidly than the above materials over 100°C. A special alkali-tolerant material, nomex, is available for sustained high-temperature drying, e.g. around 200°C. Finally, a fluorocarbon filter bag can be used when tolerance to both high temperature and a broad range of chemicals is required.

• The laboratory fluid bed dryer offers significant advantages over conventional drying techniques:

• The high rates of heat and mass transfer ensure much faster and more homogeneous drying than other methods such as oven and vacuum drying.

• Drying times range from a few seconds to minutes. Complete drying is usually achieved in under 15 mins, the exact time for a given sample, airflow rate and temperature setting being very repeatable. A uniform reproducible moisture content can also be achieved with the appropriate settings.

• Materials with moisture contents from a few per cent to over 80 per cent may be dried.

• The temperature range from ambient to 200°C covers the majority of drying and solvent removal operations. Due to good mixing, the sample temperature is uniform and under close control during drying. This proves advantageous when drying heat sensitive materials or coating particles.

• Among the wide range of materials that can be processed are pharmaceutical, chemicals, minerals, foods, coals, wood chips, plastics, resins, etc. Ask for our specific applications sheet on your material.

• The high performance characteristics of this instrument allow it to be used for many applications in addition to drying, such as:-

• Quick determination of moisture content (eg.coal, tobacco, food products) by correlation with weight loss over 5 mins. using specified drying conditions

• Mixing and blending of solids

• Granulation and agglomeration

• Rough classification of particle size (ie. Stokes law)

TEMPERATURE CONTROL

Air flow from the fan passes over a 2 kW electrical heater before delivery to the sample container. The temperature of the heated air is regulated by a closed-loop system that can achieve temperature stability within 1°C. The homogeneity of the fluidising process and the close temperature control are ideal for reproducible and uniform drying.

TIMED CYCLES

A timer built into the dryer allows the unit to operate unattended in many routine applications. Drying period is set on a simple analogue dial, time remaining is indicated by a count-down pointer and at the end of the cycle or set temperature point an alarm sounds and the dryer switches off automatically.

AIR FLOW

Control of fan speed and hence fluidisation velocity is continuously variable over the whose range. Drying is much more rapid than with other methods because of the high mass and heat transfer rates achieved with the fluidising process. Fan speed can be set subjectively by observing the sample behaviour in a glass tub or optimised by calculation using measurements from experiments at a number of different operating conditions.