� Idlers� Belts and splices.

TurnheadReplace:� Rotor bearing� Swivel chute� Plunger seal.

Feeders� For screw type, replace gear-box and bearing/seals� For vibratory type, replacefeeder liners and re-tunefeeders.

Cullet crusherReplace:� Jaw plates, rotary drums orimpact bars� Wear plates� Drive belts.MixerReplace:� Bottom and side liners� Plows and paddles� Wall scrapers� Gear-box and drive belts.

Pneumatics� Have pressure vesselsrecertified as safe pressurevessels� Replace pneumatic valvesand associated filter regulatorunits� Reline or replace elbows andspool pieces.

Control system� Check all limit switches andsensors � Recalibrate all scales andcheck scale repeatability� Evaluate repair versus new

control system.

SpecialconsiderationsThe mixer Where a furnace isrebuilt with greatermelting capacity, itneeds more mixedbatch. If the batchplant must operatemore than 16 hours

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ORIGINALLY PUBLISHED IN GLASS INTERNATIONAL NOVEMBER/DECEMBER 2004

Batch plants require repair and modernisation.Douglas D Burgoon* offers advice.

Batch plants aremodernised toaccommodateglass productionincreases and/or

product quality improvements.It is easier to modify a batchplant at furnace rebuild time,but they can be modernisedduring a campaign withoutinterrupting production. Theycan be repaired during a cam-paign, but it requires moreplanning and effort.

A scope of work for batchplant cold repair should bedeveloped alongside that forfurnace rebuilding. Someimportant considerations areas follows:

General� Clean raw material silos� Replace dust skirts/vent bags� Replace dust collector bags� Rebuild gear-boxes formechanical equipment� Rebuild/rewind motors formechanical equipment� Replace all cullet chutes anddiverters� Replace compressed aircomponents.

Bucket elevatorsReplace:� Gear boxes, shafts,bearing/seals, and pulleys � Belts and splices� Buckets.

ConveyorsReplace:� Gear-box, shafts, bearings,seals and pulleys

Batch plant modernisation

per day, it needs more capacityand this usually starts with abigger mixer.

Mixer replacement requiresplanning. The major problemis getting the mixer inside thebatch plant and into position(see Figs 1A and 1B).

Modernise scalesConsider replacing mechanicalscales with a modern load cell-digital electronic type. Typicalscale sensitivity is in the 1:1000graduation range; for example,1000 lbs. by 1 lb., 2000 lbs. by 2lbs., etc. This can be increasedup to 1:10,000 graduations; forexample, 1000 lbs. by 0.1 lbs.,2000 lbs. by 0.2 lbs., etc butneeds the resolution of theweigh feeders to be examinedand revised.

Maximising scale perfor-mance is very important. TECOrecently replaced a three-fur-nace batch plant with a new onewith sensitive electronic loadcell scales. Fig 2 shows theglass density variation for eachfurnace 30 days before batchplant switchover and 30 daysafter start up. Tighter controlof glass density increased prod-uct pack efficiency.

Automatic micro ingredient weighingEliminate manual premixingof microingredients with a

� Fig 1A. Building modifications toinstall a new mixer in the batch plant.

� Fig 1B. New 4 cubic yard mixerreplacing 3 cubic yard unit.

dilutent. Today, thecolourant ingredients can beautomatically handled andcontrolled and automaticscales can work satisfactorilyas low as 10 lb. by 0.001 lb.range. (See Fig 3.)

Total weight check scaleA total weight check scale paysfor itself, many times, if it pre-vents just one off-tolerancebatch from getting into the fur-nace. Check scales can beadded to the weighed batchsurge hopper, the mixer or themixed batch surge hopper inthat order of preference. Thesupport structure for the hop-per or mixer must be altered sothe installation is free of erro-neous forces. Load cells can besuccessfully added to pneumatictransporters or blender/trans-porters with careful installationof the pneumatic piping andelectrical conduit. TECO hasinstalled check scales on mixersand pneumatic vessels withrepeatability of ± 2 lbs. (SeeFig 4.)

Control systemEvaluate replacing the controlpanel with a modern one.Control systems usually last 5-10 years, after which spareparts availability gets to be aproblem. Also, a new controlsystem will have new softwarewith automatic weighing algo-rithms. The TECO system con-tains special algorithms tominimise feeder jogging.

� Fig 2. Glass density history 30 days before and30 days before/after batch plant change.

ConclusionBatch plant upgradingshould be a basic part ofevery furnace rebuild pro-gramme and can be doneduring a campaign.Including provisions toaccommodate future batchsystem requirements canminimise future constructionwork and complications.

TECO has the experienceand wherewithal to be ofassistance in planningbatch plant modernisa-tion programmes. It hasdesigned and built 16new batch plants andmodernised 65 over thepast 35 years.

tem is debugged. TECOswitched over a five-furnacecontrol system while the glassplant maintained normal pro-duction.� Storage capacity increase:A batch plant should bedesigned to accommodate addi-tional raw materials storage in asimple, easy manner. It shouldbe predetermined where theadditional silos will be locatedand how these new raw materi-als will be weighed and mixed.The original design must pro-vide extra positions on the rawmaterial distributor.

Process alterations during productionBatch plant modification donewhile maintaining productionrequires thorough planning toassure continuous mixed batchdelivery. Some useful practicesin this regard are:� Spare storage:Use a spare silo, or portablestorage such as super sacks,rail hopper car, etc to storemixed batch.� Electrical switchover: It is best if control systemchanges are made during fur-nace rebuild time. If that is notpossible, a switchingnetwork must beinstalled. Every inputand output must beswitched to allow theexisting control sys-tem to function whilethe new control sys-

Additional furnaces:Make basic plans for futureproduction requirements, suchas number of furnaces andtypes of glass produced. Theaim is to establish the ultimatenumber of mixed batch deliv-ery loops that will be required.The diverting and deliveryequipment need not beinstalled, just the space provi-sions for the future.

ORIGINALLY PUBLISHED IN GLASS INTERNATIONAL NOVEMBER/DECEMBER 2004

* Douglas D Burgoon, seniordirector project management,Toledo Engineering Co Inc (TECO),Toledo, OH, USA. Tel: +1 419 5379711. Fax: +1 419 537 1369. Email: form on website; Website: www.teco.com

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� Fig 4. Blender/Transporter check scaleon load cells (5000 lb. x 2.0 lb.).

� Fig 3. Automatic microscale system (20 lb. x.002 lb.).