GEA Niro has invented an innovative feed system for the SWIRL FLUIDIZER™, called the ‘Dual Feed System’ (patent pending).

 

The Dual Feed System makes it possible to dry products that has previously been impossible to dry on flash dryers like the SWIRL FLUIDIZER^™ - because either their solid content or viscosity was too low.

 

The problem has previously been solved by mixing dry powder back into the liquid feed product in the feed tank to increase the solids content and/or viscosity before it is fed into the drying chamber. This requires a rather difficult and power-consuming mixing process. Furthermore, the mixing process often results in an inconsistent moisture content of the feed product that is fed into the drying chamber, which in turn has led to unstable operation of the dryer and large variations in the final powder’s moisture content.

 

The new principle of operation is based on using the mixing that already takes place in the drying chamber, driven by its rotating disintegrator. The liquid feed product is now pumped into the drying chamber and dry powder is conveyed into it either pneumatically or by a screw feeder. The two inlet streams are arranged in such a way that the dry powder is immediately mixed with the liquid feed so that the moisture is distributed over the entire available powder surface. The enlarged, moist surface ensures a rapid evaporation of the liquid. 

In some cases, the addition of dry powder has been limited to the start-up sequence of the dryer, leading to a quicker arrival at stable operating conditions.

 

The advantage of the system is that the liquid feed-rate can be controlled very accurately by adjusting the pump speed. This means that the evaporation load of the dryer can be kept very constant and thus results in a stable operation. Furthermore, there is no need for additional mixing equipment.

 

The Dual Feed System has been applied to products like silica, titanium dioxide and others. It is also applicable where the filter cake is thixotropic and will become a liquid by mechanical stress. The Dual Feed System is available for new SWIRL FLUIDIZER™ units as well as for the retrofitting of existing units.