Presentation on theme: "BRABENDER PRESENTATION"— Presentation transcript:
1BRABENDER PRESENTATION FEEDER DESIGN FOR ENERGETICAPPLICATIONS INVOLVING CONTINUOUSMIXERS AND EXTRUDERSPRESENTED October 31, 2002By: Andy KovatsBrabender Technologie Inc.
2Presentation Agenda 1.0 Introduction 2.0 Feed Device Selection: 2.0 Feed Device Selection: Feed Device Selection Criteria- Single screw, twin screw, vibratory tray Modifications for XP Requirements3.0 Continuous Loss-in-Weight Feeders: LIW Feeder Scales – besides weighing performance,what are some noted features Sizing the Refill Rate for a LIW Feeder Venting Alternatives and Flexible Connection of LIWFeeders Loss-in-Weight Feeder Modifications for XP Requirements4.0 Continuous Loss-in-Weight (LIW) Feeder PerformanceConsiderations when Designed to meet XP Requirements5.0 Summary
31.0 Introduction Energetics feeders feed explosive ingredients in explosive atmospheres.Special design considerations include:screw or feed device non-sparking; low shear;scale design to counteract heavy dead load –e.g.: explosion proof motors;explosion proofing components;feed rate accuracy expectations.
42.0 Feed Device Selection Feed Device Selection Criteria E.g.: Ammonium Per chlorateBulk Density – 80 lbs./cu. ft.Feed – 40 lbs./hr.Volumetric Feed Rate – 40/80 = 0.5 cu.ft./hr.Using this as an example, we will compare the relativesizes of 3 common feed devices.SCREW DIA.SCREW PITCHSCREW RPMVOLUMETRIC FEED RATECU. FT./HR.Single Screw18mm13mm2201.1Twin Screw20mm12mm4250.9Tray Width(V)Vibratory Tray30mm3.2
5Common Screw Types TYPE DESCRIPTION FEED CHARACTERISTICS Single Spiral Screwopen flights (pigtail), have a small surface area for ingredient adherencewith center rod stiffeningstainless steel material of constructionlow build-up on screws, low shear on ingredientfor higher bulk densities and where an outboard bearing is required (to avoid screw/tube (metal-to-metal) contact)Single Blade Screwclosed flightswith extended shaftmore surface area for build up on screw, higher shear on ingredientfor outboard bearingTwin Concave Screwintermeshing, self-wiping screws, low volume per flight relative to screw diameter large inlet to screws compared to single screw – same ratesince flight volume is low, screws can operate at higher rpm and achieve a high fill efficiency, larger inlet reduces chance of bridging, self-wiping maintains geometry integrityVibrating Tray - for heavy powders (above 40 lbs./cu. ft.) and granules;- especially good for abrasive ingredients;- since there are no rotating shafts/metal-to-metal contact, device is simple;- requires amplitude feedback/resonant frequency control to achieve accuracy.
6Modifications for XP Requirements All screws with outboard bearings;All seals/bearings purged inboard, outboard, agitators;Internal surfaces 2B finish with welds ground smooth;Some processes need No. 4 polish (180 grit);All welds dye penetration checked;Grounding straps across gaskets;External grounding lug on feeder;Vibration tray feeders are typically not manufactured withthe electromagnetic drive meeting HazardousEnvironment Codes. As a result, care must be taken toensure that this is achieved.
73.0 Continuous Loss-in-Weight Feeders LIW Feeder Scale – Besides WeighingPerformance, what are some noted features?Description of ScaleNumber of Load CellsFeeder Connection to ScaleFlexure Frame Scale1Feeder base sits on weighed supportPlatform Scale1 – normallyFeeder base sits on top plate of scaleThree load cell suspension3Feeder hopper supported (feeder may be suspended from the hopper)Two load cell suspension2Feeder base supported at hopper elevation
8Check List for LIW Feeder Scale Evaluation Type of Load Cell digital/analogNumber of Load Cells one, two, threeLoad Cell Response fast/slow – a function of load cellmovement from full load to no loadLoad Cell Filter included/not included, one load/several loads, selection easy/difficultScale Lock Down included/not included, easy/tediousJunction Boxes for Motor/Load Cell supplied/not supplied, wired/not wiredExternal Process Connection included/not included, mounted/not mounted, with/without flexFeeder Mounted Wired -Tested Locked at Factory yes/no
21Sizing the Refill Rate for a LIW Feeder Using 10 seconds as a desired refill time, the following calculations are made:Max. Feed Rate lbs./hr. (min. rate 60 lbs./hr.)Bulk Density lbs./cu. ft.Number of Refills/Hr at max. feed rateWeigh Hopper Refill Volume % (20% heel before refilling and 20% free board)CalculationWeigh Hopper Volume= Max. Feed Rate bulk density refills/hr. refill volume %= 40 15 6= cu. ft.Refill Volume= Weigh Hopper Volume X refill Volume %= X 0.6= cu. ft.Refill Time = 10 secondsRefill Rate = cu. ft. in 10 seconds= 144 cu. ft./hr. (5,760 lbs./hr.)Rule of Thumb – Multiply the max. feed rate X 24 to determine the refill rate to achieverefill in 10 seconds (assumes weigh hopper volume calculated as per example above).
22Venting Alternatives and Flexible Connection for LIW Feeders
23LIW Feeder Modifications for XP Requirements CLDIVGRMOTORS ACMOTORS DC SPEEDSENSORENCLOSURES&JUNCTION BOXESLOAD CELLWIRING & CONDUITDIGITALANALOGFLEXIBILITYNOTREQUIREDI1ABTEFC/TENVWITH TYPE “X” PURGEDIGITAL PICKUPCONNECTED THRU INTRINSICALLY SAFE BARRIERSPURGED ENCLOSURE (USE TYPE “X” PURGING)INTRINSICALLY SAFE LOADCELL OR CONNECTED THRU INTRINSICALLY SAFE BARRIERSRATED CLIDIV 1 OR CONNECTED THRU INTRINSICALLY SAFE BARRIERSTHREADED RIGID CONDUIT WITH APPROVED FITTINGS AND SEALSFLEXIBLE CONDUIT APPROVED FOR CLI DIV 1 AND APPROVED FITTINGS & SEALSCRATED CLI GRCNEMA 7DRATED CLI GRD2TEFC ORTENVWITH TYPE “X”PURGINGDIGITAL PICKUP CONNECTED THRU INTRINSICALLY SAFE BARRIERSDIV 2 ORCONNECTEDTHRUINTRINSICALLYSAFE BARRIERSHARD USAGE SO CABLE WITH APPROVED SEALSIIETEFC OR TENVWITH TYPE “X” PURGINGNEMA 9RATED CLII DIV 1OR CONNECTEDHARD USAGE SO CABLE WITH BUSHED DUST TIGHT FITTINGSFRATED CLII GRGRATED CLII GRFGANALOG TACH GENERATOR TENV ENCLOSUREDUST TIGHTNEMA 9 ORNEMA 12ENCLOSURE
244.0 Continuous Loss-in-Weight (LIW) Feeder Performance Considerations When Designed to Meet XP RequirementsDimensional Size Increase.Increased Dead Load.External Connections.
255.0 SummaryThe following is a list of comments relating to information and conclusions presented in this discussion:Feed rate accuracy is jeopardized when the various components are modified to meet XP requirements. The results achieved in a lab test need to be considered with regard for the equipment modifications necessary to meet the Hazardous Environment Classification.The acceptable method of equipment design to meet an XP requirement is determined by the end user. The technique to supply equipment capable of meeting the XP Classification should be reviewed with the equipment supplier carefully since there is more than one method of meeting the XP requirement.For Loss-in-Weight feeders, select scale mounted electrical components that have a low weight for XP requirements.Feeders for low feed rates need careful design to ensure feed rate repeatability accuracy is not compromised.
26Brabender Technologie Inc. 6500 Kestrel Rd.Mississauga, OntarioL5T 1Z6OfficeFaxtoll-freePresented By:Andy Kovats