Triple Pass Drum
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 principles of heat transfer applying high air temperature with higher velocity to the wet product (inlet of drum) and low temperature with low velocity to dry product (outlet of drum).
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High Thermal Efficiency
The multiple drying zones and the high inlet air velocity result in relatively low dryer outlet temperature required for good efficiency. The unique exhaust gas recirculation system further increases efficiency and it also reduces the exhaust volume to a scrubber system downstream. The recirculation also raises the water vapor dew point and allows heat recovery to make hot process water in tube and shell heat exchanger by recovering the latent heat in the dryer exhaust. This condensing process is also an effective particulate scrubber.
Single Pass 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 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 surface and also improve dispersion of the product, some of our single pass drums have a central displacement tube, our “bullet”.
"Big Belly" Drum
We also have developed higher capacity drums which use the same tires, length, and bases as the standard drums. This we do by an increased drum diameter between the tires resulting in 15% to 20% more capacity.
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Drum Drive
Since the single pass drums usually require more force by the drum drive, we have located the drive above the drum on a bridge structure. As a result, the loading on the drum rollers and drum tires 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 form outside the drum.
Heliclone Separator™
The separator is a combination dust skimmer/air fan which can be used in the drying system, this allows for a compact layout of the smaller system which can be factory assembled on a steel frame for over the road shipment and easy field installation requiring no or minimal foundations.
Blood Coagulator
Several different types from inclined augers to vertical augers. The lastest unit is vertical and is only 5 feet tall and is equipped with a ribbon blender to break up lumps.
Bone Screening
We offer screening systems for separating dried bone chips from the meat and sinew fraction. These systems are used after the dryer and consist of a primary screen separator followed by vacuum gravity separator tables made by Forsberg, Inc. with an air system. The bone can be separated into large and small chips and are used for the extraction of gelatine for film emulsions.
Flash Tube Dryers
There are certain applications where a rotary dryer is not the best selection. Flash Tube Dryers can be a more economical technology to use. The Flash Tube Dryer is the same in many ways as the direct fired rotary dryer using a long tube instead of a rotary drum. The flash tube is designed in such a fashion that the product remains air born throughout the length of the tube. The tube is sufficiently long enough to create a retention time in the hot air stream to accomplish the required drying. The tube can be designed as a serpentine shape to fit a limited space.
Factory Assembled
Our smaller model dryers can be assembled at the factory. The dryer is mounted on a steel frame with all motors, piping and switches installed and wired. The control panel can be mounted on the frame as well. If a remote location of the control panel is selected, the wiring on the frame is connected to a junction box. The dryer can be placed on a concrete floor and no support piers are required.

All that is required at the plant is wiring from the Motor Control Center to the junction box on the frame, connection to the infeed/outfeed conveyors, and connection of an exhaust duct to the scrubber if required.

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Wet Scrubbers
Often a scrubbing system is required to remove particles from the dryer exhaust gas. Duske Engineering designs particulate scrubbers which incorporate a venturi scrubber and cyclone demister. The dirty gases flow through the adjustable throat of the venturi where a series of spray nozzles force water droplets onto the dust particles. Inside the demister the swirling action forces particles to the outside of the cyclone and ultimately out the bottom drain. The clean gas exits from the exhaust stack.

The majority of the water is recirculated by a pump at the bottom of the demister. A small portion of the water is bled off to the drain. A set of level switches insures that the proper amount of water remains in the sump of the scrubber.

Our scrubbers are of stainless steel construction and are custom designed to accommodate the layout of the plant. An adjustable throat is used in the venturi to optimize the pressure drop in the venturi which is critical for the efficiency of the scrubber

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