Flash dryers are the most economical for drying solids that have been de-watered or inherently have a low moisture content. Also known as "pneumatic dryers," they are the simplest gas suspension dryers with the smallest footprint. A single operation provides mixing, heat transfer, and mass transfer to dry a solid. Residence time within the dryer is very short, usually less than three seconds, producing almost immediate surface drying.
Feeds are :
- Moist, powdery, granular, or crystallized
- Wet solids discharged from centrifuges, rotary filters, and filter presses
- Small in particle size
- Reasonably dry, friable, and not sticky
Due to the very rapid drying process, flash dryers are not suitable for diffusion-controlled drying processes. Figure 1 shows a typical drying curve as obtained in a fixed or fluidized bed; the constant drying-rate area where surface moisture is removed is ideal for the flash-drying operation. The process is strictly controlled by the heat input without a residence-time requirement; the drying occurs "in a flash".
- Relatively simple in operation
- Take little space
- Generally require lower capital investment than other types of dryers
- Excellent choice for processing heat-sensitive or easily oxidized feed materials
- Product inventory in the flash-drying system is very low
- Easy to change product or product grade with minimum downtime
- Control of the flash-drying process is very simple
- Control system responds very quickly to operational changes
Flash drying systems are designed based on feed and product characteristics, available or permissible heating source, and operational safety requirements. Such systems can be designed in a closed-cycle arrangement suitable for evaporation of organic solvents rather than water. The drying gas is inert (typically nitrogen), and the solvent evaporated in the flash dryer is subsequently condensed.
Exlusive features of flash drying plant
- Reduced running cost.
- Continuous producation machine without human touch.
- Ideal replacement for tray drying of wet cakes.
- Extramely sticky/pasty wet cake can be handled .
- Particle size as fine as 500 mesh is achievable.
- Low residence time-minimum exposure to hear-ratains original product quality.
- On line particle size reduction-eliminating need of separate pulverizer.
- Fully automatic - needs little running attention.
- Negligible material dusting.
- No products degradation or charring .
- Proprietary design of disintegrator ensures uniform mixing of wet cake and hot air giving consistent and homogeneous powder quality.
- High volume processing
- Large filtering area of bag filter-reduced pressure drop -large savings in power consumption of blower.
- Measurement of pressure drops at various places facilitates easy troble shooting and maintenance.
Our Flash Dryer is a versatile machine and ideal for wet/pasty press cakes. we list below industries where it can be used.
Chemicals - Inorganic & Organic
Pesticides and Agricultural Chemicals
Dyestuff and pigments- Organic & Inorganic
Fertilizers,mineral ore Concentrares,technical ceramics
food industry,pharmaceutical industry , agricultural extraces
Comparison Between Tray Dryer & Transparent Flash Dryer
|Tray Dryer||Flash Dryer|
|1. Batch Type Operation equipment.||1. Continuous Operation equipment.|
|2. Extensively labour oriented, as labour is required for changing, arranging trays, pulverizing etc.||2. No manual handling involved hence substantial saving in labour cost.|
|3. seperate purverizing operation needed.||3. Pulverzing and drying operation takes place simultaneously.|
|4. Due to considerable manual handling lot of material wastage and dusting takes place.||4. Negligible materail wastage and dusting takes place.|
|5. The material being stacked in layers in the tray, uniform heating is not quaranteed and hence variation in product quality , moisture content or the possibility of meterial in top layer getting charred exists..||5. Material being disintegrated uniformaly and thorough mixing of hot air & feed in disintegrator , consistent product quality is ensured.|
|6. System effciency is low due to: -low inlet air temperature is required to avoid charring of material , hence low thermal efficiency.- Drying time is very high and much heat is wasted in the exhaust.||6.High system efficiency due to :- High inlet air temperature can be used due to unique design of cage mill type disintegrator.- Low pressure drops in various components,requiring less power for blowers.- High efficiency hot Air Generator.- Fully automatic plant.|
|7. Material has to be conveyed from dryer to purverizer,purverizer to bagging plant.This results in more manpower requirement and higher material wastage.||7.No material coveying needed.bagging plant can be installed directly below bag filter of flash dryer.|