INTERNALS FORRADIAL FLOW REACTORS

WHEN CLEAN, HIGH-VOLUMEFLOW WITH MINIMAL PRESSUREDROP IS NEEDED, RADIAL FLOWSYSTEMS ARE YOUR BESTCHOICE.

The direction of your process flowcan have a lot to do with youroverall process efficiency. Radialflow systems produce far lesspressure drop across the bed – a controlling process parameter forsome applications. Not only doesthis produce a higher yield, it’smore energy efficient as well.Radial flow systems increasecontact efficency between theprocess stream and catalyst bed.Because of this, vessel size can bedramatically reduced. Given equalvessel diameters, for example,a 20 ft / 6.1m tall radial flowsystem can handle the same flowas a 40 ft / 12.2m long horizontalbed. Processors can save onvessel capital cost and theequipment operating costs neededto push the flow through it.

Some processes achieve thehighest production rate of desiredproduct by operating with very lowpressure drops across the screenand bed. Johnson Screens is thepremier supplier of screen setsrequiring tight annulus tolerances.

Performance, economy andefficiency make radial flow systemsespecially well suited for suchprocesses as:

• Catalytic reforming (fixed bed and continuous/regenerative)

• Styrene dehydrogenation

• N0x removal systems

• Solvent recovery

• Hydrodesulphurizing units

• Tertiary recovery

• Ammonia converters

• Isomerization systems

• Other thin bed annulus systems

Johnson’s® expertise with radialflow processes, earned inhundreds of installations, enablesus to provide you with superiorreactor internal designs andproducts.

THE PROCESS

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The outer screen may either be a basket or anarrangement of scallops — either Vee-Wire®

screen, perforated sheet or OptiMiser TM.

In downflow radial flow systems the processstream passes through the outer basket, acrossthe catalyst and is collected in a center screenwhere it passes out the vessel bottom.

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THE DESIGN

THE SYSTEM EFFICIENCYAND ITS COST-EFFECTIVENESSARE STRONGLY INFLUENCED BYTHE SCREEN DESIGN.

We’ve supplied critical componentsfor hundreds of radial flow systemsaround the world.

This experience has made us theindustry leader in radial flow vesselinternal design. In designing andmanufacturing these internals, wedraw from a full range of options.We can offer Vee-Wire® screens –the top-of-the-line product invessel screen internals. Thesescreens are fabricated by attachingVee-shaped profile wire to an arrayof support rods, welding eachintersection of wire and rod. Thisforms an extremely robust screenwith continuous slot openings ofvery close tolerance.

The benefits to radial flowprocessors are substantial:

• A stable screen/catalyst interfaceis created. The rigid, smoothsurface of the Johnson® screen eliminates catalyst attritioncaused by flexing of wire mesh.

• Screens have vertical slots to allow easier movement of the catalyst vertically, reducingcatalyst damage during operationand under upset.

• Because the catalyst beads are not abraded or broken, the bed permeability remains high. Even flow distribution is maintained.

• Strong all-welded screenprovides excellent resistanceto high temperatures andpressures for long service life, less downtime.

• The interface between thecatalyst and screen does not become a plugged surfaceinducing high pressure drops. Two-point contact with catalyst does not entrap the pills, allowingfull movement and complete regeneration in continuously replenished units. If a pillbecomes fractured duringoperation, the outwardly enlargingslot allows the fragments (or fines) to move clear of theinterface virtually eliminating slot blinding.

In addition to these generaladvantages, we can apply ourdesign and fabricating expertise tospecial areas to give you evenbetter results: we choose the sizeand shape of the wires and rodsto arrive at the best combinationof open area and mechanicalstrength.

We can treat our screens during orafter fabrication by pickling andpassivation, annealing or othermetallurgical processes to furtherenhance corrosion resistance andmechanical strength.

The results of these efforts can beimpressive. For example we canbuild a 24 ft / 7.3 m diameterscreen, 40 ft / 12.2 m high with aslot width tolerance of ± 0.004 in. /0.1 mm, using heavy wires.

If your process doesn’t demand thehigh performance characteristics ofVee-Wire® screen construction,we can find the solution with theright combination of wire mesh andperforated plate to producesatisfactory results.

Whether for new installations orretrofits, the goal of all our efforts isto give you the best product foryour process.

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Each intersection of Vee-wire andsupport bar is welded to produce anextremely strong structure.

Vee-Wire® screens have outwardly enlargingslots which allow only two-point particlecontact. Smaller particles pass freelythrough without plugging.

Smooth wire surface and vertical slotorientation allow the catalyst to movevertically against the screen face withoutbeing abraded.

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THE PRODUCTS

JOHNSON OFFERS ALL THE SCREEN INTERNALSAND RELATED ASSEMBLIES NEEDED TO PRODUCEA RADIAL FLOW SYSTEM THAT OPERATES AT PEAKEFFICIENCY.

Johnson® fabricates the centerpipes,scallops, outer baskets and otherassemblies required in a radial flowreactor vessel.In the case of a system upgradeor retrofit, we custom build to useexisting vessel hardware whereverfeasible to minimize or eliminatewelding to the vessel envelop.

Every design option is carefullyengineered in all radial flow vesselinternals we supply including:

• Centerpipes

• Scallops

• Outer Baskets

• Coverplates

• Ventilation Screens

• Expansion Bellows

• Catalyst Placement Pipes

• Thermowell Guides

• Access Doors and Others Manway Arrangements

To assure consistent quality forJohnson products, our manufacturingfacilities follow a structured qualitycontrol program which is reviewedand updated on a continuousbasis. We operate under the ISO9001 standard in Asia-Pacific,Europe and the USA - yourasurance that reactor screeninternals from Johnson will alwaysmeet your specifications.

Our radial flow internals are mostoften made of 321 and 347stainless steel but 304, 316, 410S,alloys 600 and 800 or other metalsmay also be used.Johnson follows ASME coderequirements for carbon content onmaterial operating at elevatedtemperatures.

Field service is readily availablefrom experienced crews. This caninclude on-site technicalsupervision, analysis of productcondition, labor during installation/repair or engineering consultationon difficult process issues.

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Many coverplate designs are available.This segmented coverplate is designed toaccomodate catalyst transfer pipes.

Ultrasonic device allows on-site inspectionof annulus between inner and outer screens.

Our engineering staff is available fortechnical consultation at any point in theprocess from product design to fabricationto installation and start-up.

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CENTERPIPES ANDOUTER BASKETS

In its simplest form, a radial flowsystem consists of two concentricscreens with an annulus filled withcatalyst or sieve.The system efficiency is a directresult of the effectiveness of thescreen internals. Made of weldedwires and rods, they offerexceptional strength and resistanceto collapse, buckling or breaking.Equally important, their plug-resistant slot design and high openarea percentage providesdependable media retention, highvolume flow and long service life. As a further refinement, slots onboth the center screen and outerbasket are oriented vertically toallow media to slide against thescreen surface during processingwithout becoming abraded by theslot edges.Screen dimensions arereadily adaptable to any new builtor retrofitted vessel.

How to increase flow rates anddecrease vessel size

• Cover plates, manways and otheroptions may be provided asneeded.

• Screen baskets and centerpipes may be any height and diameter.

• Slots are as small as 0.010 in. / 0.25 mm and up in 0.001 in. /0.025 mm increments.

• Screen wire & rod shapes and sizes will be determined based on operating conditions.

• Quality documentation isavailable including statisticalprocess control charts, millcertificates, welding procedure specifications and various other reports and certifications.

• Screens can be made in sectionsto facilitate installation through the manway ID.

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For maximum efficiencyin radial flow systems

VEE WIRE SCALLOPS

Compared to a single large outerbasket, installation and repair canbe much faster and simpler withindividual scallop screens. Made of welded Vee-Wire and rodsor perforated sheet, Johnson®

screen scallops have exceptionalresistance to bending, twisting orcollapsing – all essential qualitieswhen faced with extreme loadscaused by expansion orcontraction during temperaturecycling operations.

Buckling -a common problem intall reactors- is virtually eliminated,as is damage caused duringinstallation.

Once installed, the screens areeasily maintained. Their special slotdesign virtually eliminates plugging.

Johnson Vee-Wire screen scallopshave distinct operating advantages.Vertical slots, for example, allowthe catalyst to slide up and downsmoothly during operation withoutabrading. Slots can be as narrowas 0.010 in. / 0.25 mm to retainsmall size catalyst.

Despite the narrowness ofindividual slots, the JohnsonVee-Wire scallop arrangement hasa much higher total open area thana single large outer basket orperforated sheet scallops of thesame size. This increased openarea translates directly intoreduced pressure drop andenhanced process efficiency.

Standard Johnson screen scallopsare available in any width or length,and in a wide variety of metal alloys.

• Scallop size is determined by process engineers.

• The upper section of the scallops(and the centerpipe) is a length ofblank material equal in height to the horizontal thickness of the bed. This prevents shortcircuiting flow if the catalyst beads settle.

• Cover plates are available and can be easily attached to the top of the scallops and/or centerpipe.

• Scallops are provided with expander rings on request.

Vee-Wire screens have inwardly enlargingslots which allow only two-point particlecontact. Smaller particles pass freelythrough without plugging.

Perforated sheet scallops are the standardin the industry. They are light, easy to installand a low cost product.

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OPTIMISERTM

SCALLOPSJohnson® has developed a newscreen system that combines theprocess efficiencies of an outerbasket with the installation andmaintenance advantages ofstandard scallops. Called theOptiMiser system, it maintainsa uniform bed thickness in orderto make maximum use of the bed.Among the many advantages ofthis new Johnson OptiMiserscallops:

• Install easily.

• Create high flow capacity.

• Make more effective use ofcatalyst than conventionalscallops.

• Adapt to all size vessels.

• Stronger than conventionalscallops.

• Create a uniform thicknessannulus for predictable process flow and pressure drop.

• Can be made with slots sized 0.010 in. / 0,25 mm upin 0.001 in. / 0,025 mm increment.

• Include system sealingcomponents and coverplate connections.

Johnson OptiMiserTM scallopsenhance process efficiency

JOHNSON PERFORMANCESOLUTIONS TO RADIAL FLOWREQUIREMENTS

Johnson OptiMiser scallops can befabricated to nearly any size,all with the following key features:

• Blank interval at screen topprevents “short-circuiting” of flowif the catalyst bed settles.

• Longitudinal and horizontal platesseal spaces between screens. The space between the back of the screen and the vessel wall isalso sealed.

• Vertical slots and smooth Vee-wire face prevent abrasion of catalyst beads as the bed movesvertically in operation.

• Rugged welded construction of the OptiMiser scallops creates high column strength.

• Expander rings are not required for maintaining scallop in position,which removes impediments to catalyst movement vertically along the face.

StandardScallop

OptiMiserTM

Catalyst

OverallLength

Clamor Weld

SupportRing

Vessel Wall

Screen Support Rods

Plate orScreenBottom

ThicknessWidth

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GLOBAL SERVICE SUPPLIER : FROM EXPERTISE ANDINSPECTION TO INSTALLATION AND MAINTENANCE

Our experience with a great varietyof industries ranging from refining,petrochemical applications andchemical uses to water well,pulp & paper processing, miningand architecture gives us a wealthof knowledge which we makeavailable to you through our fieldservice teams and in-housetechnical support groups.

We are experts in major processesincluding Catalytic Reforming,Styrene Dehydrogenation, LAB,Sulfur Treatment, HDS/HDT,Ammonia Conversion, MercuryRemoval, Claus, etc.

We apply this expertise from initialproduct design through proprietaryfabrication to testing, installationand start-up and have the peopleto solve a problem that may ariseat any point in a product life cycle.

A TEAM OF HIGHLYSKILLED WELDERS

No matter how distant or difficultthe problem, we can get a team ofexperienced welders to your site.Each of them has personalexperience in repair and installationof screens and other vesselinternals. All have considerableexpertise in TIG/MIG and otherwelding techniques, including workon exotic alloys.

Thanks to their experience, thesewelders can operate autonomouslywith little or no supervision underthe most demanding conditions,including confined space work inremote sites. These teams need nointermediate contractor to directtheir work and typically reportdirectly to our client’s on-sitemanagement.For new project installations,we will field a team of experiencedfitters, technicians and supervisoryengineers to ensure a smooth,trouble-free start-up.

MININGCentrifuge BasketsPipo Two™ Modular ScreeningSystemsPipo Three™ Modular ScreeningSystemsPolyurethane & Rubber Screen PanelsWoven WireVee Wire™Sieve BendsTrommel Mats

WATERWELL SCREENSWell screensRiser PipesEnvironmental Monitoring ScreensDrilling FluidsRehabilitation Chemicals/Nuwell

ARCHITECTURE & CONSTRUCTIONColumn covers Urban development Frontages Floor gratingsVentilation grids Sun control screens Custom lighting Furniture Walls/Wall partitions

GENERAL INDUSTRIALFlat PanelsSieve BendsCylindrical ScreensArchitectural ProductsCustom Polyurethane CastingCorn Wet Milling (Starch and Sieves)Sugar Processing Products

WATER PROCESSPassive Intake ScreensIn-Line Self-Cleaning FiltersNozzlesTriton® Underdrain SystemsFish Diversion ScreensCollectors/DistributorsVessel Internals

It is our aim to assist you inmaximizing your operational efficiencyand supporting you in finding long termtrouble-free solutions. Discover ourever expanding range of products,designed with your needs in mind:

PETROCHEMICAL AND REFININGCentrepipesOuter BasketsScallopsSupport Grids & BeamsOutlet CollectorsLateralsDistributor Trays

AT JOHNSON SCREENS®, OUR LARGERANGE OF PRECISION ENGINEERINGEQUIPMENT IS SUITABLE FOR MOREAPPLICATIONS THAN EVER.

Innovation andcustomer satisfaction

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NORTH & SOUTH AMERICASJOHNSON SCREENS - USATel. : +1 651 636 3900Fax : +1 651 638 3132sales@johnsonscreens.com

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