Duske Advantages

We offer triple pass as well as single pass drums in our systems.

Our triple pass drums are really drums with seven drying zones which optimize the drying of hygroscopic products, using well established principle of heat transfer. This is done by applying high air temperature with high velocity to the wet product (inlet of drum) and low temperature with low velocity to the dry product (outlet of drum).

For some products and where space allows it, we offer our single pass drums which are of course of simpler construction than the triple pass. To obtain the same high inlet velocity as with the triple pass drum, we use an inlet cone which expands to the drum diameter. In order to increase contact between product and drying surfaces and to improve dispersion of the product in the hot air streams, some of our single pass drums have a central displacement tube, or “bullet”.

The single pass drums rotate slower and require more force on the drum drive. Therefore, we have located the drive above the drum on a bridge structure. As a result, the loading on the drum rollers and tire is reduced increasing their useful life.

Both types of drums have bolted-on tires which can easily be replaced and squared, with all fasteners accessible from the outside drum.

So called “quad pass” drums are really also three pass drums with only four drying zones. The inlet air velocity is very low. This reduces convective heat transfer resulting in higher product temperatures reaching a level of boiling water. This type of “backward flow” drum operates at higher outlet temperatures and lower efficiency. The high drum outlet temperatures can cause product break-up and increased dust.

Another special feature of Duske Dryers is its unique recirculation system. Our dryers take hot exhaust gases and bring them back to the burner housing. There are two major benefits here. First is fuel efficiency. Since the gasses are already hot, less energy is required from the burner to heat the air. Secondly, the amount of exhaust going to the scrubber system is decreased. Typically, at least a third of the airflow through the dryer can be recirculated. The volume of recirculation is modulated with the burner firing rate. With the higher exhaust humidity we have systems in operation which make hot water through a heat exchanger.

Our dryers incorporate a control system which requires minimal effort from the operator. We use Fireye Flame Control with annunciator system housed in a stainless steel cabinet. A series of temperature and hi-limit controls, motion switches, pressure switches and shut-off valves insure a safe system. Our controls meet ISO specifications and are UL approved. Each panel is custom designed to fit the needs of the customer. When required the controls can be built to C.S.A. standards. Also, if PLC interfacing is required we can provide that service also.