Model 501 Fluid Bed Dryer
What is fluid bed drying?
By forcing enough air through a bed of particles, the particle bed may assume a fluid-like state (resembling a boiling liquid). Heating the incoming air and managing the air flow rate through the sample, a Fluid Bed Dryer provides thorough mixing and maximum contact of solid with moving air.
Fast:
Delivering up to 2.5m3 per minute of air, the Model 501 Fluid Bed Dryer can break up wet samples and ensure vigorous mixing and rapid moisture removal. 5kg of wet “ideal” sample (80% moisture) can be dried in 15-20 minutes (5 Litre tub).
Mild:
High air flow rate gives:
• High moisture removal rates at relatively low temperatures
• Thorough mixing, so no wet spots require extra thermal energy to penetrate
• An air cushion between particles to reduce abrasion and particle size alteration
Non-agglomerating:
Air-separated particles prevent lumps and caking, both of which make other drying processes much slower.
Homogeneity of sample:
Static drying methods leave evaporation residues at the sample surface giving a heterogeneous sample. Fluid Bed Drying achieves the opposite. Mixing during Fluid Bed Drying gives homogeneous samples, making an ideal method of representative sample preparation for subsequent material analyses.
Reproducible:
Microprocessor control of airflow, inlet air temperature, and drying period coupled with fluid bed action gives highly reproducible experiments and finished samples. After preliminary experiments, a known moisture content in the final sample (ideal for tablet forming) or removal of external (surface) moisture only, may be achieved. Drying times to required moisture content may be optimized and drying patterns studied to aid scale-up and plant design.
Without a PC connected the Model 501 Fluid Bed Dryer can run one stored program of up to 16 steps (previously downloaded from a PC), or may be used as a conventional (manually controlled) Fluid Bed Dryer.
Additional features of this advanced in-lab dryer technology include:
• Precise airflow feedback control
• Membrane-sealed controls to prevent ingress of particles into the instrument
• Reduced operating noise
• Advantages of the Model 501 Fluid Bed Dryer
The Model 501 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, e.g. oven and vacuum drying
• Drying times range from a few seconds to minutes. Complete drying is usually achieved in under 15 minutes; the exact time for a given sample, airflow rate, and temperature setting are very repeatable. A uniform, reproducible moisture content may also be achieved with experience*
• Materials with moisture contents from a few percent to over 80 percent may be dried
• The inlet air temperature range of ambient (+15°C) to 200°C covers most drying operations. Due to good mixing, the sample temperature is uniform and under close control during drying; advantageous for drying heat-sensitive materials
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 (e.g. coal, tobacco, food products) by correlation with weight loss over 5 mins, using specified drying conditions
• Mixing and blending of solids
• Rough classification of particle size (i.e. Stokes Law)
• Among the wide range of materials that can be processed are pharmaceuticals, chemicals, minerals, foods, coals, wood chips, plastics, resins, etc.
*Microprocessor control of airflow, inlet air temperature, and drying period coupled with fluid bed action gives highly reproducible experiments and finished samples. After preliminary experiments, a known moisture content in the final sample (ideal for tablet forming) or removal of external (surface) moisture only, may be achieved. Drying times to required moisture content may be optimized and drying patterns studied to aid scale-up and plant design. Without a PC connected the Model 501 Fluid Bed Dryer can run one stored program of up to 16 steps (previously downloaded from a PC) or may be used as a conventional (manually controlled) Fluid Bed Dryer.
Why choose the Model 501 Fluid Bed Dryer?
The Model 501 can be considered as three Dryers in one:
• Standalone Fluid Bed Dryer:
- The base unit and specified tub assembly for standalone operation.
- Microprocessor control of airflow, inlet air temperature, and drying period; coupled with fluid bed action gives highly reproducible experiments and finished material samples.
- The Model 501 Fluid Bed Dryer is the latest model from Sherwood and has membrane-sealed controls to prevent particle ingress and reduce operating noise.
• Programmable Fluid Bed Dryer:
- Dryer base with specified tub assembly, connected to a PC hosting Sherwood’s fluid bed dryer software program.
- The software allows control of all variable functions, data monitoring, feedback, and creation of multi-step drying protocols designed to dry samples in the most efficient manner. The Model 501 Fluid Bed Dryer can be programmed (via the computer interface) to step through up to 16 drying steps with the following parameters defined and controlled: timer, blower motor speed, and inlet air temperature. An optional pulse flow module can also be controlled using the software package. These variable parameters may be monitored and recorded throughout the drying program. Each program step may be terminated manually or when a pre-set time or condition (outlet temperature or relative humidity) has been achieved; whichever conditions occurs first.
• Analytical Fluid Bed Dryer:
- The base unit and specified analytical tub assembly (fitted with auxiliary combined temperature and relative humidity probe) connected to a PC hosting Sherwood Scientific Ltd’s fluid bed dryer software program.
- The ability to monitor in the tub (above sample) “outlet” temperature and relative humidity allows for the capture of additional data which may be used to understand better the drying behavior of a material. The ability to transfer that data for post-run processing expands the scope for material drying behavior studies, for example, material drying curve generation is possible.
How to specify your dryer and accessories:
The user has to specify the tub together with the Inlet and Outlet Filters required for their application as follows:
• Material of construction: Glass. (Stainless steel tubs discontinued 2022)
• Tub Volume: 5 Litre, 2 Litre or Mini-Tub (for use with Multi-Tub Base Adapter)
• Tub Type: Ordinary (Bags), Sealed, Analytical (GL32 side port), Dynamic Moisture Analysis, Classifier, Mini, Custom
• Inlet Filter: Material type, pore size
• Outlet Filter: Bag, Top Cap, Material type, pore size
Bag Material Selection:
• (Terylene is normally chosen) Terylene shows greater resistance to acids
• Polypropylene is resistant to most chemicals but degrades more rapidly (than the other two) over 100°C
• Nomex is an alkali-tolerant material suited to sustained high-temperature drying, e.g. ~200°C.
Accessories also to be specified include:
• With a Pulse Flow Module (501 86 001) you can pulse air into the sample and adjust the frequency and duration of pulsing. Pulsing the airflow has been found analogous to providing external shaking and mixing. Samples that are difficult to fluidize, like long wet strands of irregularly shaped leaves, e.g. tobacco or tea, are ‘blown apart’ and mixed by pulsing the flow.
• The addition of a Humidity/Temperature Probe (501 86 500) to the Programmable Fluid Bed Dryer upgrades the instrument to an Analytical Dryer.
• RS232 Cable (926 09 052) for downloading program steps to the Fluid Bed Dryer and for collection of data for real-time feedback of temperature and relative humidity.
• Software (501 86 700) for control of variable functions, data monitoring, data feedback, and creation of multistep drying programs designed to dry samples in the most efficient manner and taking into account the changes in the material’s behavior as its moisture content changes.
• The table below lists the available options for Tubs, Inlet, and Outlet Filters for the M501 Programmable Fluid Bed Dryer.
