ATFD
ATFD is a unit operation usually used to achieve final liquid-solid(salt) separation in Zero Liquid Discharge (ZLD) plant.
Process Description :-
Agitated Thin Film Dryer or ATFD is the most efficient and mandatory equipment to separate out salt from high concentrated feed to achieve complete ZLD for any type of industry.
Agitated thin film dryer consists of:
- The dryer with scrapper assembly
- Small vapor separator,
- Surface condenser,
- blower.
Dryer is perfect combination of Gear assembly, distribution plate, shaft with rotating blades (ROTOR) and inner shell with steam jacket. Prior to start evaporation process first cooling water circulation is started and some negative pressure is maintained in the system by blower.
Through feed pump Feed from the feed tank enters into the inside surface of the ATFD through distribution plate which generates the even distribution the feed.
Steam is being provided in the jacket attached with the inner side of the shell. And by this contact conductive heat transfer occurs which leads to evaporation of water from the concentrated liquid and salt will be precipitated out and deposited on to the inner surface of the shell.
Water-Vapor mixture generated in system, by the help of blower passes through the small vapor separator where water particles are drawn off and vapor rises and drawn to the surface condenser where it gets condensed and this pure water can be used in a various application.
Shaft with blades is continuously rotating in the inner shell, maintaining small clearance from the wall and removing precipitated salt from the wall surface.
Giving salt with max. moisture contain of 10-15 %. This is how system works continuously and we can achieve TRUE MEAN OF ZERO LIQUID DISCHARGE.
As ATFD is giving complete separation of water and salt, leads to a complete, most efficient and true mean of zero liquid discharge system
Advantages :-
- Low residence time
- Low liquid hold-up
- Less fouling/ Minimum fouling
- Uniform concentrate
- Solids(Salt) with lowest moisture content
- Overcomes the issue related to centrifuge-mother liquor handling
- Provides complete solution for ZLD
Application :-
- Zero Liquid Discharge
- Waste water treatment
- Salt recovery
- Caustic recovery
- Product concentration
