QuadPass Rotary Drum Dryer Brochure

Inspection PortHot Gas TurbulatorMaterial Infeed ChuteWater SprayNozzleMan Access Doorsurface at a modest temperature. And sincethere’s no foam or fiber, there’s no insulationbreakdown—a common problem with otherdrum dryers.Flexible fuel choicesTo heat the air flowing through the dryer,Dupps offers burners that operate on naturalgas and fuel oil as well as a solid fuel VDC(vertical dry cell) burner. The VDC canoperate using wood, coal, or other formsof biomass fuel.Get lower VOC emissions, better product color, and moreuniform drying than single- or triple-pass rotary drum dryersReduces VOC’sWet feed is exposed to the hot furnace gasesin a controlled “lift and fall” manner. Theparticles are exposed to the hot gas as theyfall, but not while they are resting in theflighting. This exposure to high heat, followedby a brief rest, prevents the gases fromheating the solids too long, greatly reducingthe amount of VOCs generated.Better product colorA QuadPass Dryer gives you better color inyour finished product because the solids areless likely to be charred or over-dried. This isdue to the unique way the QuadPass designpresents the wet feed to the drum, as well asthe controlled manner in which the feed isexposed to the hot gas.Solids dried uniformlyThe Hot Gas Turbulator swirls the gas as itenters the feed zone. This turbulent air helpsthe feed solids to spread out, allowing the hotgas to contact nearly all particle surfaces.Good heat distribution prevents clumping andgenerates a more uniformly dried product.Reduces fire dangerA unique feed arrangement all but eliminatesoperating dryer drum fires. Because the wetfeed enters the drum off-center, away fromthe “blowtorch” of hot gases, it is much lesslikely to catch fire.No insulation to break downThe QuadPass drum has NO insulation, onlyair sandwiched between the drum’s outershell and its stainless steel cladding. Thisannular air gap keeps the drum’s outerA Superior Solution For...• Agribusiness Industries• Forest Products Industry• Municipal & Industrial Wastes• Animal Protein Recycling IndustryRevolutionary QuadPass™ Four-ZoneRotary Drum DryerRevolutionary QuadPass™ Four-ZoneRotary Drum DryerMaterial Infeed ChuteEnergySourceTrack 2nd ZoneFeed Zone 3rd Zone 4th ZoneSeal 2nd Zone 3rd ZoneInitial Drying Final DryingExitAdvantages of QuadPass• An off-center feed chute allows wetfeed to enter the drum away from the“blowtorch” of hot gases.• Wet solids are exposed to the highheat in a controlled way, through asequence of “lift and fall.” The solidsfall through the hot gas, then get abrief “break” from the heat as they liein the drum’s flighting.• The feed zone is the entire drumdiameter. Feeding into such a largevolume allows the particles to spreadout and travel individually rather than inclumps. Falling through a much largervertical distance ensures that the hot gasreaches all particle surfaces.• Drying gas velocity is slowest in the feedzone, then gets progressively faster ineach successive zone. This increasingvelocity helps material conveying anddecreases any chance of drum plugging.How it worksWet solids enter at the largest diameter of thedrum, away from hot gases. Hot air enters thefeed zone at the centerline while the wetsolids enter away from the center, landingdirectly on the flighting. As the drum rotates,the flights lift the wet feed upward. Withfurther rotation, the particles are graduallyreleased to fall downward through the hotgases in a thin curtain.The repeating cycle of “lift and fall” throughthe hot gas occurs in an environment of lowair velocity, which assures enough residencetime in the Feed Zone. Most of the evaporationtakes place in this zone, quickly reducinggas temperatures.Zones 2 through 4 comprise the final dryingsection of the QuadPass drum. This sectionconsists of two annular passageways and onefinal pass through the drum’s center tube. Eachsuccessive zone has a smaller cross sectionalarea, so the gas velocities increase as the producttravels through the drum.In Zones 2 through 4, the fines tend to separatefrom the larger particles and exit the drumquickly. This prevents overdrying and charringand reduces VOC emissions. The smaller, faster-drying particles are picked up and carried away.Larger, wetter particles stay in the drum longerand continue to give up moisture as they arepushed along by the airstream. Each particle exitsthe dryer system at the desired moisture content.Problems with 3 Pass Dryers• Wet feed is introduced in the dryer’scenter throat, directly into a “blowtorch”of hot gases.• Wet solids are constantly exposed tounrelenting heat as they travel the entiredrum length. This leads to charring,over-drying, and even fires.• By feeding into the center throat, thewet solids are forced into a tight space.Even though flighting lifts and stirs, feedhas less distance to fall and tends toform clumps.• Drying gas in the center throat is at a highvelocity, but the velocity drops as it travelsthrough the annular passageways. Thisdrop in velocity reduces conveying forceand makes drum plugging more common.Ordinary three pass drums can over-dry.Material starts drying at high air velocity then drops at each stage,so particles can accumulate, overheat and clog.Dupps QuadPass™Flighting to meet your applicationFor small, granular particles, the QuadPassoffers saw-tooth flighting.For elongated products (e.g. strands, hay, grass,bagasse) curved, smooth-edged flighting keepsproducts from hanging up in the flights.Drum replacementThe QuadPass dryer is yourfastest and most economicalway to improve productquality, color, and reduceVOC emissions.If your drums are broken,burned up, worn out, ordon’t meet production quality, we can replace any size, make or modelwith a new state-of-the-art drum using the same footprint.U.S. Patent Numbers 4,729,176 and 4,802,288.Other U.S. and foreign patents pending. © 2005 The Dupps Company Printed in U.S.A.Complete turnkey systemsEverything you need — including biomass/wood burners, materialfeeding and conveying equipment, recycle air systems, high-efficiencyparticulate collectors, and state-of-the-art PLC controls — available now.More Free FactsSee how to boost product quality, lower energy costs and easily meetemissions requirements. Contact us today for a free heat and materialsbalance using your application specs. The Dupps CompanyThermal Technology DivisionP.O . Box 189Germantown, Ohio 45327Phone 937-855-6555Fax 937-855-6554www.dupps.comE -ma i l : info@dupps.comDue t o o ngo i n g p r o du c t imp r o v emen t s ,d a t a s h own i n t h i s p ub l i c a t i o n i s s u b j e c tt o c h ange w i t h ou t n o t i c e . C on t a c t T h eDupp s Company f o r l a t e s t s p e c i f i c a t i o n s .