Your efficient partner for modern and effective bulk material handling PLANT DESIGN - ENGINEERING - EPC-CONTRACTING + 49 (0) 40 36 13 090 [email protected]www.ibauhamburg.de I BAU HAMBURG CEMENT - THERMAL POWER - MINERALS Single silos. Ring silos. Multicompart- ment silos. From 2 to 22 chambers, diameters: 14 to 27 m. Advanced technology for self-discharging Cement Carriers including the Midship tunnel. Marine Cement Terminals Central Cone Silos EPC-Contracting Silo Conversions Components Spare Parts Cement Carriers Ship Unloaders Floating terminals. Mini terminals. Silo systems. Dome systems. Flat storage terminals. Stationary or mobile types: From the 5,000 class up to the 60,000 class. Piling. Civil works. Steel structure, supply/erection. Electrical/ mechanical supply and erection. Economic modifications with advanced cutting-edge technology. The key for a well functioning plant: Components, all made to measure. High stock availability: Just-in-time supply of spare parts. After-sales Service. I BAU HAMBURG I BAU HAMBURG Multi-Compartment Silos Compact Terminals for the Cement Industry A HAVER & BOECKER Company Z/12/15/Multi-Compartment Silos
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Your efficient partner for modern and effective bulk material handling
2 x La Cemento Nacional2 x Ciments LuxembourgeoisDyckerhoff Mark II / Geseke
Dyckerhoff AmöneburgUnicem Vernasca
Cementownia NowinyCementos Hispania SA. Yeles
Many Thousands of IBAU Silos
CBR Gent
Central Cone Silo
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shape, which also hasstatic-structural advan-tages, is used from theprocess engineering pointof view, because itforms a slip surface anddisplaces the bulkmaterial outwards in agravity-induced flow.
The annular fluidizingbase at the foot of thecone together with theoptimum span widthsallow for the fluidizationof the bulk material overthe full surface. Bulkflows of 3 to 500 t/h can be controlled andextracted absolutely continuously from thesesections.
If the outer ring silo isnot divided into compart-ments, the flow-controlgates positioned along acircular base line areopened individually inturn or simultaneously tosuit the level of thebulk flow. The geometryof the silo floor,the arrangement of theextraction openingsat the foot of the inclinedconical slip surface anda variable level offluidization of the bulkmaterial enable the massflow of the bulk material.
In many ways the undi-vided silo with a centralcone already fulfils theseconditions, so additionalpressure-relievinginternal chambers withconnected venting sys-tems are not needed inmulti-compartment silosof this basic design.It is possible to derivevery different compart-ment cross-sections fromthe circular shape of thesilo to suit the flow cha-Fig. 2: Ring silo
Multi-Compartment Silos with Central Cone
1. Introduction
Intensive developmentduring the last few deca-des in the field of silotechnology has producedpneumatic emptying andblending systems whichprovide reliable storageand good homogenizationof the powdered bulkmaterials.
Changes in the productionof binders and fillers, forexample by grinding themixing components sepa-rately or utilizing wastematerials, fly ash, etc.,have had an effect on silotechnology, the prepara-tion of the bulk materialsand ultimately the dis-patch technology.
The concentration of storage, blending and dispatch for a greatlyincreased number of bulkmaterials, intergroundadditives and mixed products has eventuallyled to the concept of amulti-compartment, high-capacity silo systemwith integral positivemixer and dispatch station.
2. Design and processtechnology ofmulti-compartment silos
The internal compartmentdivisions result in clearexternal diameters of 14to 27 metres, recognizableoutwardly as cylindricalsilo units. The base of theentire silo floor is formedby the central cone whichhas proved its worth overmany years in single-cell,cylindrical silos (Fig. 1)and ring silos (Fig. 2).The cantilevered conicalFig. 1: Central cone silo
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Multi-Compartment Silos with Central Cone
Fig. 5: Ring silo with ring compartment subdivided into 8 sections, and one inner silo cellFig. 3: 4-chamber Central cone silo Fig. 4: 5-chamber Central cone silo
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Multi-Compartment Silos with Central Cone
cement, limestone meal,fly ash, etc. are only flu-idized to a limited extenton part of the silo basezone so that the restrictedoutlet cross-sectionsachieve air saturation ofthe mixture with verylow extraction quantitiesand sharply reduced per-centages of air. A self-regulating air overflowsystem which depends onthe set pressure is inoperation under theseconditions; this reducesthe air supply in therespective fluidizing sec-tion without changing thestate of fluidization.
The utilization of spacein the compartments isvirtually 100 % becauseof their comparativelysmall horizontal dimen-sions, thus plannedchanges of the type ofmaterial cause no problems. The samegeometrical conditionsand the intermittentextraction operationwhich normally occur,result in mass flowswith turbulent mixingwhich further improvesthe quality of the bulkmaterial.
3. Separation andmixing of typesof material and thedispatch system
Measures to keep thetypes separated apply tothe silo and compartmentfeeding system andto the interconnectedconveyors below the silocompartments. Pneumaticconveying systemswith pipes are preferredfor providing absolutelyresidue-free silo feeding
racteristic of fluidizablebulk materials. Fig. 4, forinstance, shows a centralcone silo with 5 compart-ments. Appropriate back-filling and secondaryslopes at the base areused to avoid trappingthe bulk material atacute-angled walljunctions which canoccur in the central silocompartments.
In Fig. 5 a ring silodesign with a central siloand 8 outer compart-ments can be seen. Fig. 6shows a different subdi-vision of the ring silocross-section with 5 compartments in thecentral silo.
The multicompartmentsilo shown in Fig. 7 isparticularly interesting.In the upper level thereare fairly large storagecompartments, i.e. 1 central silo and 6 ringcompartments, and in the lower level there are12 multi-purpose com-partments for mixedcomponents and finishedproducts.
These conditions forcontinuity were achievedboth for bulk flowsgreater than 100 t/h andfor very small flows ofless than 10 t/h. Variousrecipes for the mixedproducts which are madeup in weighing hoppersabove the positive mixerrequire correspondinglylow fine flows which areextracted and meteredby the flow-control gatesat the discharge boxes.
Under these fluidizingconditions bulk materialssuch as various types of Fig. 6: Ring silo with inner silo subdivided into 5 sections Multi-compartment ring silo during construction
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Multi-Compartment Silos with Central Cone
systems, especially whenseveral, chemically verydifferent bulk materialshave to pass through onetransport line in turn.
High levels of wearmake it necessary to payattention in this tech-nology to wear-resistantsealing of the conveyingdiverter. Conveyingcombinations consistingof airslides and bucketelevators or verticalpneumatic conveyorsoffer energy-saving andvirtually wear-freesolutions; here again it isimportant to seal thediverting elements andthe problem was solvedby using solid designs.
Airslides are always themost suitable means oftransport for the general-ly short interconnectingconveyors below the silocompartments. Operationof the exhaust air filtra-tion system can only becombined where thereare compatible bulkmaterials.
Otherwise decentralizedfilter installations anddust return systems are needed for the entireplant for the sake ofquality assurance.
The production of adiversity of mixedproducts has also set newtrends. Separate grindingor the use of furtherinterground additives aswell as the adaptation ofthe production processhave lead to the integra-tion of a mixing stationinto the multi-compart-ment silo plant. Recipeswhich have been checkedand combined by weigh- Material transport after mixer via I BAU Pump
Batch-type mixer with toggle lever system
Fig. 7: Ring silo (mixing system) with 7 + 12 = 19 compartments
ing hoppers are mixed inbatches in a “single shaftmixer” (Fig. 8) in theshortest possible time toform a homogenousmass. The mixer iscompactly designed, hasa trough lined withwearing tiles and a lowenergy consumption andruns extremely quietly.
Depending on the plantdesign the mixedproducts can either betransferred directly to thedispatch system orconveyed to silo com-partments provided forthe purpose (Fig. 9).
The cantilevered designof the multi-compartmentsilos ensures a generoushousing space and accessfor all the equipment andmachines for operatingthe system.
The silo cells and hencethe silo floors are normally elevated fortwo reasons: Firstly, theextraction devices andthe necessary mechanicalequipment have to behoused under the cellsand, secondly, direct lorryor rail loading is usuallyan objective to eliminateadditional transportand loading points, thusvehicle access isprovided under the silo.
The systems are veryextensively automatedand are fitted withprotective circuits andelectronic monitoringadapted to the require-ments of the operator.
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Multi-compartment silo with 6 compartments, silo diameter 26,0 m for Cementa AB HeidelbergCement Group, Malmö Sweden
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Multi-Compartment Silos with Central Cone
2 Multi-compartment ring silos with 2 compartments each, silo diameter 26,3 m and 24,2 mfor Pan United, Singapore
Multi-compartment silo with 5 compartments, silo diameter 28,0 m for Hatien I Cement Company, Ho Chi Minh City, Vietnam
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Multi-compartment silo with 7 compartments, silo diameter 21,0 m for Holcim France, Val de Seine Works, France