AU2013202508A1 - Improved infrared float bar - Google Patents

Abstract

Infrared air float bar for use in floating and drying a continuous planar web of a material in a dryer. Direct radiated or reflected infrared electromagnetic energy from an infrared light source in a removable channel assembly accelerates drying, or evaporation of solvents, or curing of web material passing in proximity to the bar, either by infrared electromagnetic energy, or in combination with convention airflow. The infrared source is cooled by pressurized air passing through an interior portion of the removable air bar channel assembly, and the air is further conducted into fluid contact with the web in an air gap between the emitter and web to promote convective heat transfer and to contribute to the air pressure field supporting web flotation. The removable channel assembly is configured for replacement of the infrared emitter and to allow the setting of the pressurized cooling air flow to the optimum level.

Description

IMPROVED INFRARED FLOAT BAR The present application is a divisional application from Australian patent Application No, 2010256680, the entire disclosure of which is incorporated herein by reference. BACKGROUND Embodiments disclosed herein relate to an air float bar for use in positioning, drying or curing a continuous generally planar flexible material such as a web, printed web, newsprint, film material, or plastic sheet. More particularly, they pertain to an air float bar whose pressure pad area includes an infrared light source, such as an infrared bulb, a reflector surface and a lens to enhance accelerated infrared heating of web material to cause solvent evaporation, drying and/or curing. Electromagnetic infrared heat energy in combination with jets of air impinging upon the web surface provide for concentrated heating of the web material, thereby providing subsequent rapid evaporation, drying and/or curing from the surface of the material. U.S. Patent No. 5,035, 066 (Wimberger) teaches the integration of an infrared emitter into a Coanda-type flotation air bar. Cooling air is brought through a channel assembly that encloses the emitter. A quartz lens is used to encose the emitter while allowing transmission of electromagnetic energy in the range of infrared wavelengths to pass from the channel assembly enclosure to the web. In one embodiment, said cooling air, after passing around the emitter inside said channel assembly, is discharged through holes in a quartz lens of said emitter channel assembly. Although this arrangement provides some recovery of heat by discharging said

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cooling air to the web source after flowin! arond gaid emitter, the flow path is not optimized for both cooling of the emitter arnd recovering of heat to the air which is subsequently impinoed on the web. The prior art arrangement with passage o1 air though holes in the quar ens does n 4 de Optimum fuid oIntact to e cool the emitter and Jens as is desreed in ode to Malintain longevity of teecmoet gis therma degradatin or conamrnarion, dN does t reflctor ,: is d further desirable to keep the emitter and lens free from contamination by aggressive sowvenu OapOts, irguAS such As inks and/or cOating mateials, and other contaminantS such as paper dust or Chodr Of materii fion hroken webs. Cling and prevention 01 contamination of tih f reflector is also desirae for t same reasons as discussed for the lenes f sonh 000t21a10 Lion occurs the infrared ener is aboredb the qurtz material of e emitter and quart Z ens instead of being transmitted through said quartz tot wet surface, which results in loss or trying and at transfer efficiency, and also Eomotes degradation as the design temperatures of the emitter and lins Mneriais ay easily Ws exceeded. i iy, contaminat iOO wi.l reduce the reflectity o the reflOctor resulting in los of drying and hean ansfar efficient and material therma degradation As is known to tone Skilled i c Ato i a dryer, it is Aesired to prevent possible i9ntin of cobstibise materials, such a paper web, shoumc said combustible materials come into contact wi th hot surfaces, it is further deired to hae a quick acting means of interrupting the hoEt flux from the infrared emittor from reaching the we o prevent ignition of a 2 stationary or broken web. A means or < ctng the infrared heat fux is taught in 1.S. Patent pon ,043,995 and 6,195,909 (Rogne et cL) but requires deteti on ad an active mecheninc means to assure that the web ite not expOsed to temperatures exeeing the known to those skilled in the art, it is oten desirable to un fastcooin tungrton or carbon filament voters as are salable from Heraus 1oleieAht of :aIa, Germany, These est-cooling elments minImize the time necessary to bring the infrared heat fNx and associated surfaceN temperatures wow enouca avoavc tin nofsaid cogstwtble ma'oe.ial a should the web stop or cra drn an Os no the drying process Even w s cooingemthers, it is0 desrrab10Le o keep the expwoe surfaces of the air flA oat bar as cool as possi at al times to event possibe inniton o said ombustible materials, oven when web stoppage ora web breakage upset may go undetected it is also known to those Skild i the aft of drying materials y means of infrared enerOy tat anont of het effective absrbed by the material i eperatue of the emitter te gom y defnng th infrared light pats t th mateals and the asorpion characteristic or the materials to e dried, It is desired to select an emt pe su tempratue w~ .t t emt zSixi~flhe electr roanei en ryfu n the range of wavelen ths that oe pond w h the typical include the base web substrate, and a coating Comprised of solids, and a solvent suca as waer or an organic sovent. said silent to be dried. Each of these materials exhibits an infrared absorption characteristic as a function of infrared wavelength, or spectra, which is to be considered in the selection of the type of emitter to be used. In some cases, such as printing, the coating or ink is not applied to the substrate uniformly in all areas. In such cases it is desirable to maximize the infrared energy flux to the areas having coating or ink while minimizing the energy flow to uncoated (unprinted) areas. The locations of the acated and uncoated areas are variable according to the product to be dried. One prior art method used to effect the direction of drying energy to areas requiring drying while limiting energy to areas not requiring drying prescribes the selection of the emitter such that it will provide high infrared heat flux at a range of wavelengths that match high absorption wavelengths for the solvent, while minimizing the emission of infrared energy at wavelengths where absorption in the dry solids and the substrate is low. Another prior art method arranges a plurality of emitter lamps in an array wherein the emitter lamps may be activated (energized) or deactivated (de-energized) to emit infrared energy approximately matching the physical location of the areas to be dried. In the drying of moving continuous webs having widely variable patterns of printed and unprinted areas, this method of activating and deactivating a fixed array is only practically capable of directing drying energy on a spatially coarse scale, The infrared energy can be applied more or less in lanes along the length of the web to be dried, which does not address the need to limit drying heat to the unprinted areas that lie between printed areas along the direction of web travel 4 A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission or a suggestion that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims, SUMMARY According to a first aspect, the present invention provides a method for regulating the drying of a web in a dryer by convective and radiative heat transfer, comprising providing in said dryer a plurality of air flotation bars having an infrared light source for emitting electromagnetic energy and a reflector for reflecting electromagnetic energy emitted by said infrared light source, and regulating the air temperature of the air responsible for said convective heat transfer to a predetermined temperature. According to a second aspect, the present invention provides a method of regulating the drying of a web in a dryer by convective and radiative heat transfer, comprising providing in said dryer a plurality of air flotation bars having an infrared light source for emitting electromagnetic energy and a reflector for reflecting electromagnetic energy emitted by said infrared light source, and regulating the air temperature of the air responsible for said convective heat transfer to a temperature 30 to 100F higher than said web bulb temperature. The embodiments disclosed herein offer an improvement over the prior art by guiding the cooling air in a path which maximizes the cooling of an emitter, an optional lens and reflector surfaces while providing additional convective heat transfer to the web and additional web flotation support, while shielding surfaces of said emitter, lens and reflector from contaminants described earlier. Exposed surfaces of the air float bar are kept at the lowest possible temperature to 5 minimize the risk of ignition of the web or other materials being processed without the use of mechanical shutters or shields. The general purpose of the embodiments disclosed is to provide an infrared air float bar for use in the heating and/or drying of webs, such as for use in a web dryer. The design of the air float bar element may be selected from several types as are known to those skilled in the art. Example designs of float bars are taught by Frost, U.S. Patent No. 3,549,070, and Rocheleau, U.S. Publ. No. 2005/223593, but it is to be understood that the flotation bar element of the present invention is not limited to these particular examples. Included are one or more infrared emitters integrated into the air float bar for the generation and transmission of infrared electromagnetic radiation to the web, and additional heat is transferred to the web by convection air having been heated convectively in the process of cooling the emitter and associated reflector and lens elements, It can be appreciated by those skilled in the art that air flotation bars provide connective heat and/or mass transfer owing to the action of the air jets on the web as it is floatingly supported in an array of one or more air bars. The air supplied to said jets may be Sa MCeated by an independent heat sourcesucnh as an eiectric res31si ance col, hot oM i es U Om 06>1 or a earner ocred i n roe ductiq supplying the a1 tO One moo 7r bars nte rver in Tre case 0A n infren wr : 0a p bna, cooiinq air ins hated h Ta nfraed emitrer a ndh su a red bncmes a md im For enhanced convecian heat trans fcr an mass tr ane c to e web wnthn the dryen 2 Sar cooling Ea22r, now neated, mayno h brought in a04 ete contact wit the meb to enhance hear rasfer In embodmns I oen he ad use teo pr i esfiient col U0 to cr0 ut cemn surfaces as preomentoned and to avoid pontial Igo> i. io of wen materi als whe 5..5C izt >n rru tempeeratu re an oh hero et c the 3001 a 2u50k e nr taken u vthe 006110 air for' Use 10 a nndE.2 OP the weA Lu> ihroa th etDIco o i t tIK i -sare d isohargcoe n mole nteae y between the neb and ar bar a tAn wniamv han Sy a payircuLod again no qpl yp n rmr covectaver Eofl fanmt r After he m l cent n the. reb, the comaiN axta izd, oan bxa soe ve a r u al f ecre a a p~tin re create ofgapvlb tqo VCOLT thE 0 C0110>l abr bar a within o te o un that the a air M&KitCZe CO onldi )-ea f rSu to maintai at de 0. ad WE' 1 0 to - f the total conrc tion dcrion 1r fio supp ied to the air a s n ea hzammae (6 the venbiLat ion safety requirements requiring the dryer to operate well below, rycically li% of, the lower erplosive .£xmit OonoetraCtian of the solvent or solvents being dried~ In a preterred embodiment the supply air to ne: r more sfrared flotation air bars nozles is heated onl v h the infrared emitter lements' Ma is no other indeendet hater is required to heat the supply a1r, this Saving space and component osts o ir handling equipment. In a most preferred embodiment, by maximizn the rec r .aed air within the dryer i a range frm 7 to 95%, he convection ae r soed to the Infared otation naozes mar be heated to a desired temperature, efmably in theorange of 150 to 00 for drying of aterdbasod coaLqs and inkso n a further embd ment the fon ad tempera e o he air supplied to the infrared air ar i regl ated ta a d s red convecon heat flux to comp e en the anf d hel ... to .. i rd. hipr ..

e a unique means to preferental die he9 Aing of the web whil drying Mth t and dry areas on the same we, as n the ase or or esn n Whi e d&.ng under conditines of costant infrared emitter temperature and cons tant cvectonair veloci y adtmertr, th wt aeas of the web are uebtantialy cold bythe evaporaineanveg needed to vap rie th I oIavet such a water. As is well known to those stilled in rng the wet areas tend to approach the wet bub temperature and toe in at approxiatel tat temiperature drn h cons tent rate drying period, until suficent liui is evanoanted and the evaporainrt.. lmedb th faling rate drying Npeiod Uponetrn h el rate drying period, the web temperature then clmb as me evaporatle OeimAg diminishes Inte cast o0 printing, some areas of the web are heavy covered Wh ink whie some areas may han litt or n0 COVeage These low coveraqe areas aerltvl r n fe enter th falli Ung rate drying ~ oe oo asn meitl oon entering re Aier. Tus the web temperavure in thesr areas increases significant in aontpast to relatively wet areas, and often aches a temperatre at oe exit of the dryer which exceed the desired level. This may result in damage to the web product as well as heat trnfrcaatrsti fteifae tro bars is app ied n binato with inrared radiation mode Sch that t eratre d b reduced this accmpl y thle cbin actin of the two heat tra nse oes convectionan aiatin Those skilled in the art of ea i recognize that the heat t lux via the tmoe ac smtaneously and the nti tion re additive o work opposite to another That is. WAIle idnfraed energy is heating an object it may at te sa tima b losing heat via convectn It is n o the embodiments disclosed herein to prvie a balance of the two aoeat fux modes son that t overheating ofzeatively dry areas, s on as non-p oe areas is avoded or migated without the lmi prior art already desce d.C Typicaly en the web first eers te dr t is cooler than ne air temrerture and the L eeivelv heated addtively by bo ad r and convds, relatvely dry (lo cveragn) areas, the infur cont nlen to heat the webnuL as the web temeraure 8 evetunily eceedst the regulated ai tempretre in the dr aea, tec onvection heat tansier flow act opposit to the infrared radiation and the air tends tseep those areas o. the web elativAv cooler, MeanwhlIe the wette areas (higher coverage) will remain at a rower teertur beow the reu lated air tempertre w to the evaporative cooling effect previously des consequently, the dn rate is enamneA by bot heat transfer modo in the wettr areas frm hating by both radiation and convection.,B regulation of the ai temperature to a level nst aoove te wet oulb emperature in toe dryer te comedy infr red and convection drying chaacceriet ics of the present fast dryig s promoted inhn oeac ra hl mitiga i enden coverage areas. in or io art, the on& reqo W At 01 Lh cooinA air a e to limit ne temperature of thee associted elements such as the reflector and lens, mentioned above it is an OK-ect o te e disclosed neein to reguate toe temperature of the air stppied to the infrared air bar to meet a wb tempert Cur heating b nce An wet vens dry areas one cooling air temperature 0 now desire to e a regulated variable, this places additional design requr ements on thne embodimgent of the coolin9 proisr Semtter an assiatd eemente In 'he m described herein, the coolng a flow vInme and path take into anide n sir temperatore. Vookne more specie c y to the desio of the infrared air bar infrared selectrmagnetic engy ' waves pass from an emitter filament by tranmon in a, straightforward direct manner to impigge on a rsing web. Said infrared waves pass transmissively through the emi ter bulb casino used to hold and P:CGtge the fiament, and through a panar lens. The bulb casing and lens materials Ore typically of quarlZ materiMal ha trunsmissive proper ties in the wavelength orange Infrared electref~gingitZ energy. Inrarged electromagnetic waves are aiso reflected in ad indrAc manner from the emitter to a refl ector surfae that rol eins te wanes, which then fAther ass tArogh the lanav lens to impinge upon the traersing web As is kno to thos skille in the art o IfAreod enery. portion he eletromagnetic energy that enters a transmissive material ce impinges on a elciv ufc is anbed This absbed energy raises the temperatu to degradation of th transmissivye or rleciv property, substantially reducing te energ recig the web 5 and also result i early allure of the emitte an drying the web when recovered in an air stream 1 which is then brought into .lui contact with the woo. En gy recovery anncoo .tling effed&c~xenGessM -a~'' d we carried nt in a manner tou r depSr00ie un flu0d contact with a controlled quantyo ir. Opt aio of the present @bodients has shown that ths can c accomplished by pasin frm S to 40a prfabyro 7 to 15%. of thenota a~Dir spl eiee ne ~esr to inthe Aonn YA Y) cae Aa though an air d-ist nionmas t uniform fluid contact wi the emitter hul 1 an fute nformly guide t n 1ow path An fail cont over the Su ffaco of the reflector, anod ther into niform flid contact with hoth faces OK thre plana lesost pere rably this flow of coing air is in the range of 7 to of the ita supnly a:r to tne floater bar 10 addition, the uni form f luid cont act of conl ng a1 w ith n emitter bulb, rrAfientor and len surfaces prevent contaminatin by solents and other materials mentioned previously cis Yi5C Lo e a channeli air har, wheein ne change assembly has a comparment defined by a bottom having at least one aperture and a pa i r of opposing sides, the cmpartment comprasrng an infred light source, a refletor nf inftared light, and a ns transmss ave to inrared lght. The apertue alows for the f i cooing fluid about Me infamre light source, reflector and lens in the oompartment The remnovable channl asemly t on figured for relaemt of the infrared emitter an to a o e setting Of the pressure cooling ai flow tote optmmlvlTus the chnel can be removed and the infrared light source replaced or repaired, and the channel then reinsrte into the air bar o N the choe e emove ad a n channel can be inserted into the air bar In a peered embodiment the set adjustablea The flow thouh the at least one aperture 1s Set by ad ute t of a moveable element in re0atio1 to afixed element, so a to allow a inra eo a derae in the aperture flow arna of the caNombie moveable anO stanonay eemets. hissetingi-s made byajutn ne posi tron r SAid mWvable element to obtain s en ooling of the e tter ad associated elements wih te maximum regulation setino for the in oder to avod herme of the maerals selected In aditon the corinq air flOw is set to and other surfaces that may cnatthe web), sol h web break or otherwise lose tension, to a temperature below the ignition temperature of| the web material, preferbly <40 . The practical range for te coong air :.ow setting has been found to be from $ to 40%, most :rete rabiy 7 to 15%, of uhe totel 5UyppiJ air deliuerec to me infrared alc bar. BRIEF DESCRIPTION O THE DRAWINGS YiG I is a cross 3-secrt na± view ofh an IR f loat oar inaccdnance win certain embodiments; FfIG 2 is crossI float barf FIG. 3 is a crsssectiana W of the I fat bar of u a 1 N showing ain rdlw patterns; PIG 64is a crvsietionl vew of a inqe-side nation IR air foil in e wi certain embodiments; PIG. C as a cronseSKCtidflai view or a sii-so fltaion .? step foim in accoronce winr certain emodiments; PIGS. 6 SDae scoemamic ilstra tions o f various JR bar confagu rations in accordance with ccrtai embodiments;i FIG. 7 is a cVOss-e onal ciew of a coanda air f A oat bar hAving two R I sore accrance w certain embodiments; nA is a mop vi an air ar showing an air embodimnts; PEG0. 03 is a side view Ot2: an air barshW an air ow ajustent mechanism in ac ordance w certain embodiments; pIG. 60v ottom view ccbn air bar showing an air flow ad ustment mOOKOiM in locoroanoc with certain embodiments; FIG. fSD is an end cros sscinlve fa i a showio an air flow ad ustment mechani in accordaneZ with cs aim esoodimens FIG, 9A is a top vew an airK br Show1oan sir tiow adIustmen mechanism in, acordaYnce with certain embodiments; Vie. 9B is an coo. ross sectionax vew cf an aiba showing an air flow achoitment mechanism in accordance wink nc00i Lai ebomnts; FIG. 0A is a snheasic diagram of a dryer ncorporating a iliin cnunc wish supply air 7 re-ciruatng~ and exhaus air features so accordance Wss ceti rhoi&o . 1is a schematic d IS deposit ing supply air ro-circultn i n xa air ienz youn;5 asi Io paths; a j Y V 12 is a schemati diagraM of a drer V Pcop ratiKg a plu ality of I flat ba i con t pi a e-iuan V, aust a r features in accordance with erane odmn;ad FIG 1 is a schomat diagram of a iyT incorgpating a pluaiyo Rfotbr iocnrl exhaust ain features in accrdaC nc with cert' "n DETAILED DESCRIPTION nenera bs discs n support a we The air supn id to se primary jets may 13 for drying of the web, Air for coolang the eiOrwv reflector and lens elements contained in a removable channel may be taken from the same supply plenum as the primarv flotation air 1 or altenately ded fom a separate ar r to the chane assr contacting the emitter reflector and otional planar lens the cooling air is discharged throtch one or more scondary jets wach sween the face or Phe panar lens anoprevent contact of the web and solvent materiasN fro RGS I and 2 sAn a peferred enodiment wherein the floater bar element 10 is of the Coanda tge having tWO Primary flatiton jetsf a First primary faton Lt 12A and a second primary flotation sl 12I8. Two secondary air slots 14A and 14B, chat are prefeabaly 5 tEo 40% of the primary alan ' 2A 1 ISP most prelegaly 15 to 300 are also provided as snown. Supply air enters une supply plenum 15 of the a bar 10 via a supply air feed inlet 1 (g 2 a plurality of oval saged apertures located at the bottom 18 of the air bar 10 and is dstributed along te length of the ai Lai to obain stable distribution to the flotation ets as i knoAw in the art A infrared element s configued A a channel assemhl c omprsie of a suppOrt ng cnanner 20 the supply air plenum 1 or a separate conling air source as mentioned eOrliv, hy means of on or more apertures 22 which pnetrate rho base channel and are in substantial aignment with comparabe apetues 23 i the rnelectA 21 at tW point of tangent contct wth t case nanel 20. The total area of the apetur s is preferaly equivalent in lt area to 20 to lOn o t h area of the primary rotation slots 12A, 12B, that IS, slot length x S ot width n number of slot. The active area af the apertues may be adjusted by alining the array or aoerturea in the reflentor 21 with a omprbnle array of apertures n the base channel 20 ranging from ful alignment to complete cIosure 1 thu act q as an adustale damper for stt fthe (n ng an w, Suitable mechanical means of sliding the refnlentor wMi resent to the base channel to achieve the desired aligment can easily be acconmprishe hy those skiled in the art 3:1.5 0>SD show pareferred embodiments for the slidin adstationry elements in the chnnel assembly to enable the adiustmen of the infrared emitter cooling air flow. FIGS. 0 and BB show a sliding adjustment elemt 2 t c apertures 22a t c b in the removable channel 20 s>ep~ iing oesised ap res are located in reec e that. the:4& pertures noiK ide wi the p22 removabe chanel 20 Siding adjustment elemdn 27 has adjustment slots 2 a t allowNh oebe lmn 7t slide in uosi ion elative to reflector 2and eoal channG 20 suc that the aperture 2 open area is reduced from une Rlly concentric alignment pos ii Once appropriate position of the adjustment e lemenis found the adjustent element an be fixed in place such as by tightening bots o e lke in t slo Z IG and S shw a mor preferred embodiment whern apertre 2a n the slidin; adistn elemn 27 and the th a wn a finer adjustment of lo when movin the ae Apertues 23 in the refleo 1 1S tatdistrbuon member 24, and opposite SMde members A that each terminal in iwadly facincr terminal ends 111 IE The outer surface ofthe chamber 20 trsnsitonnz between the sides 411 1 nd the respoectie terminal onds 1 I 1 11 ae ueye so as to 7, VD of he air bar 10, Goanda slots which a the primary station sots 12A, 1. The ?effoVl. chane 20 can be slidinlyy removed from the air ar 10, alo ng. wih its c nts, pad e me replaced by anoh annel on by te sae nannel. a in al tnar or replacement of- the lens and/or bulYo contained therein. An initial a distrn'tion member 2 9, such as a e ted ptate can be prvied air ar 10 ennae uonorm supply ai istribuhn nopnarao 9t1v n such a meber has been fona to be sa seundary air distribution member 24, such as p ate perforated with slots or holes, can be posotcone donsotream of tho initia a distribution mnembevr 19 as shown 1 and also can serve to s::or the rmovable The channel 20 conain an feared lht sore sun as an iPi emitter bb commercial available fro lerau Noei Gmbh A lens 3, preably a p ana 30 as shon Th lens e es t tense of.infrared waeets topsnhog n rahe the web 0 floaing aov the ba 0 ( . 2 Electromagnetic energy emitted from e I. liht source 30 passes through the Ins 32 and dircl aitsot the eb 50. A reflectr 21is also contained in one chanrm 1 20, and |is preferably parabolic and made of a suite reflective material such as stainless telo ns doardly be the R C y surrounding the 1 ih oreecp ntete onnupied by the lens so that light emitt f the tsoue radiates either directly through the lens o S reflected by the e tor towards te lensand is then ultimately radiated on to t a s diagrammailly in 2.2 The secondary snts 14, s are defined by the ce arance (eg 0 . 01 000) p 5rovded betwen the lens 32 and the inward IEa clg termnal ends llA, 1li o the chamber 20 A illustrate diarammatlcally in 3 npply air fe ino the a ar at inlet s16 Ows through the perforated initial air dIstribution memoor 1 through perforated secondly a distrbtin nmme 24, out through pima Votati s 2B re*ure pad or reid is created o fLa9y support the web 0. Supply air also paSseO rough nhe 00.ng eKr entry jets in the member 24, the botom 40 of tee channel 20, and the rerlectr 21, and flows in re aea aned b He refletor 2i and the lens 2 Tht air thus nnl the emitter 30, the relectora The resuling heated airthen hows ont A the interior f the channel 20 through one o the secdary slos 14B, and sweeps the face or the loon 32 thereby peenig contact o the web and ovont materials and o Ser debri or ontr m na nt s w 3 th the lens 32.Ths skilled in the art will appreciate that Mae fluid for co ing the emitter, rflector and les elements may be duted from a separate air souree to the channel In certain embodiments, the .ens 32 can beoitd and the air discharged from the channel assembly can be 17 used as a virtual len, e-fective sheng9 the emitter 30fom the web and porentiat 1y hazardous debris or containan ts. IC. 4 illustrates an embodiment wherein e float Ibar i a sinede ibis on sar n s embodiment, a single primary flotation oct 1 is provided t o discharge supply air to float the web 50, and coo Ing art from the removabe channel assemb The air foA 10' s defined i p a header which n the embodiment shown, is generally rectanguwa 3. crEs~ section except fnt its tCop polion Oppost sides ?A' ' of the header terminate in respective top flange porins Top flang portion 8 is an gd ermina es n a bent por tn 13' Aslga porto n 81 extends towards opposite side 7A in a substantal horizontal fashion. The header deins an interior space 15 that serves as a olenum for the gas tha is reeie via the one or more holes (not shon t e b air foil M' that are in gas - entering nommunrcat on Aw a gas upply (not show . Toe heater 15 poo vioned on suitable dusting by aligning the aligners 3 at eh end doate of the header and is sealed by reta ask c a :dffuser plate having a plualtyorspce hls ca b positioned in the hader to ho)lp distribute te~ S3plv of nas evenly as it fows towards e slots The illagge porgLin Oh and bent portan .1 .s otte heaer, together wAh the flat portion 23 od the member 25, defines the p rimary slot of the air toil Air flows ot the primary slot 2A , and contnues in tho direGWo of we travel tow;as thle wing 5ouh i ol hc wino 35 rernates in a fiance 34 exenin downwarly a a riht anel abnt 0.5 inhes. The air hen tave 18 along the top face of the wing in the dirnetion of web travel to Support the web. As in the emoimnt of FIG. 3, n optionally removable channel assembly 20 is provded, and contains a reflector 21, a lens 32, and a n lR light source 30 Air enters the channel assembly 20 through one or more apertures 22' in the member 25, each aligned with a respective aperture 2s in the ttom 0 of the channel 20 and cools the reflecto 1, the light source 30, and the lens 32, the cooling air (now heated) is discharged from the channel 20 via the clearance between the les 32 and the flat port: 2 Flo, 5 ilssates an emodment wherein the flat bar is a singlside flotation step f 10" such as that disclosed in 'a Y Patnt No 7 3017 the disclosure of wh is hereby noorpnratod Dy reference. Like the air toll 10' of F 3In.4 an optinaly removable channel assembly 20 can be provided that contains the efector 21 I g sourO 30 and ConS 32 Dif ferences between the embodiLment of FI and thato FG, 1 inoude in the IG 5 embodimen the provision c a second sendary slt iP spaced fom and stepped down from the primary slot 121k, is to ai ing the l4B traels parallel to the web Ai dicharged from the stream 01 the secondary discharge slot IlB' in a directron cparalei to the web transport direc< on, Betwen the primary di charge slAt and the secondary dscharge slot is a rallv fat web saort s nace, incui ngtyhe face of the les 32, Downstream ot the secondary discharge slot, in te diection of web tiavC± is a second web support su ace that o s a n portion that slopes dwnwardly as ait extends away from the second ry discarge slt l4B' This second web 19 support surace optronary can include a second lens 2 htforms pn of an opiona setiG channel ssembl 200 comprising a reifeor 22, an IR light source 3005 and te lens 32 the side of the stepIil can include one or more apertures 60 to allow suppl air (or air from annher snorce) to enter the channel assembly and Cool the components therein as above. 1-. 7 illustrates a further embodiment in a oanda noz ze hav ng two Goanda discharge slots T2w 12", n the embodment shown, an R .ght urce 30 is positiond upstrea in tSe direction or we travel, or the first Coanda discharge slot I. ent mernberO" tha ef ined In ysrL the Coanda disc harge slot 120' includes one or me apertures that allow air to pass UAgh ano flow about the 1? ngt Souc 3 o cool toe same. A iens 3" an be positioned above the light source 0t trnsmissive to oleotromagneti c enery. n f poviedt'he lens is ale., Coo1ed 15Y tnve flow or air that cools the light sour rnativel the nooling air can function as a virtual lens keein e ligh souce 3 cool and free of a be positioned downs the ret A web trave 1 of ho scondConaso.lB aand na manner similar to the upstream assemhy, The downstea asemlry is shon without a lens, althOugh one cOMl be used as in te upstream assemblv F IGS. 65GA iD Ins trat su itable arragemnts of plurawitres f infaed ars w A respect to a traversing web 20 s is noted that the ag as shon are disclosed herein r ,, Cada, air foil? Step fol etc. can be used Oher arrangements are also possibe. 20 m7a-272 oosrumoeo below a traversin wen 20 274a-2n positioned above a traversing web 27 FIG. 6 illutrates a plity of infrxd air bars 2! a-27Gn and a pliality of infraed ai bas 270-21 an an Opposing vertaally siged aranoemeot about a traversins web 20for rapid drying of the traversan we 27G10 D mutates p alt o inf ed air ears w0oo. 280n and apn hluratet ofifardariasl8a attanged in alternati g opposing vertica arangement about a traversing web 270 cremang a sinsoidal shape for the traversing web 2f0. FIGS, 10K illustrate pre ed modiments & infraed air float bars arranged in a dryer enclosure 301 havng a web20etrn sad ncouetruhwblt 30a and ea i ng through extso Od) si e floatingl traer is throoh a cobndcneto n inraed radianion heat in zone oreatec by infrared ai bars w ah rea inra ed ener y to the wein and handle disribt so heat spply airjes to 00 imine lnuh 'web Th enlsur 0 onas the scent heatdsi least a nortio of the spent air may 0 e rsovn d o re circulatin to the air bars, At least a oorrn o the spent air is eausted from the enclosure as described in te embodiments herein. FIG. 10 illuinraes a dryer embodiment SO0a comprised of a plurality of infrare air car 2a10 moted to and :l nlidcomnctnwthan irspl distribution header %0a, and a pluait finfrare i bas 282a82n mounted to and in feol communication wt an ai r supply di stibto hedr 3O. Ii d 21 andBl~ ismad thoug fed openings 3l5a'315n. the ai ed openings 315a-315n are conneomeet and seale to air bar feed inlet 16 (FIG l by means of epa aon joints 31 La3JI Onwich allow easy disconnect i on ano remoal ofte infrared air bars from the dryer. The joinits 3l a ol~n may be sealed with gasket material coprscAON seats. o'r othtr similar means as are known to hnose skilled in the art ai flotation dryer design. IG 11 illustrates roe air flow paths created by the air flow e lements witin av enclsue 30 oC dryer 3O2a of FG, 10 herein described. A one supl a 2 olcs hated air from anside the encrosure 30 ac orcarges said air onder prsuePne 9 n32 aiga optional heat sore36 Tisha ore a eare hot water steam> or thermal ol or prefeaby an eletric elementdc hetr Afe pasn trog opional heater 32 the heated ai is dietdt i distribution headers Bla and 31b via duct 326 ad may ho cotrolled by a air temperature control on30 airoahavebendescrbdpeiul. latma oe fed toa the emitters is regulated by an operate hog a use interface in cmnrion with an TO acodigt dried product. Once disoarod fom the air bar the zvi comes into fluid contact wrh the web to consraevl cxchanoe heat and mass wihte web 270.Floigti 22 305a and 305b. An exhaust fo bancng thi room ar Nu any evanoated solvenls fom the web must be purpoee a separate emaust fa 3 dasa least a p.an or said spend air through exhaust duct 332 and flow control damper 336 and discarges it to atmosphere. ran iI ineadofcotrol dame. e, hesprt rxhau a~n 331 of dryer embodmen 00a is necessary for saflyhandlin volatile fammable sorven materals and/ c~ i hecse a di rect fie ulbre s 'e ta vorumte and treatmnt ecupoent (otswn fa ai palluntain' ma renias in sa pd exhaust may he required aed on requirements set arth by partie havin 'uc jurisdiction as will be understeoc by these familiar wt such reguations an thei locale. FIG 12 illustrates a preferred dryer embodiment3200b ;or dryin a nan-flammable solvent 1 such as water? whcrein supplemental heat beyndthat pro &de byth infrated ar bars is not needed to mecc the thermal load required by the web. In same oases,. where web drying heat load requiremens are less than would beouptb fly populating all air bar positions in distribution headers 310da and 31Ob. ONE or OOE mor pstos ta9ontn i bars may be occupied by anarn0c.wrout an acrrv air headed 3%lCa is not full poput td wit infrared ai ears, but includes twoa nan- nrared ai bars Ma aned 23 20h Note these -onifrared ai bas may be of a nuaer era har des ig The nninrrd rs ae preferentially located near the webs exit end of the drver and tn the case of a single-side coating on te wea lated on the unncated sideo Elan trial power red to the emitters is regulated by an operator through a user interface n compni ction AitA an SP according to the we drying loadl in order to achieve a satmactorily dried product . The suppi ai temperature as eouaed by control loop 34 to maintain a set point by moduating the amount of nxhaust troug eriao duos 330 by meQans-; of damper 3$5 pi, iurates a rerered emodiment for a singleside coad or p d we wherein the nk or oatie is o the bottom sne of the web. Electrical power fed to emiter 282a282n is regulated by an roperator: though a user interface in comemiatinwt an SCR 342 acoroing to the web drying lod in o achieve a satisfactrily dried prduct The a repiaaste nwer setti ng to SCR 3ll whion in tu rn modulates the power so the emitters an infrared air bars 2a8n facing the u ated si o t The operation or she air hars will be illustrated wath reference to the embodiment shown i P., A plurality of infrared electromagnetic energy rays increase Orying anp cAy because the infrared Source is located at rhe point of highest heat transfer 1 e.g. beaten the discharge slots and radiate from the anrarec sGoe3 either directy o nietytr tteln 32 Tne inrreed cyn enery i transmitted for 9ing a trnaesing "eb beig processed in a dryer~ A portion of the infrared rays reit off the paraboic refle r 21 24 and throuch she lens 32 to impart :infrared drying energy upon and heating she w'd The wae inength of she inrare can so snort wave with a wave lenth of .8t . mcos 7 edium wave length wrth a wave length of12t u microns or wong wave tengtn 0£ n 0 to arteast i- r more micrnsn In certain embodimnts 7 the infrared soure Pressurizd ai to float the web e:nterrsne intrared air oar through the plurality of oval shaed air inlets IC to float tha web. Prom the air inlets 7 the pressurized air proceeds as indicated by dashed arrow lines (FIG.3 19.ehruoh the holes or thme secondary ai distrbutin memoer 2.4 through te oanda slots 12A and l13B along the Coanda curggeA defind by the side members l.113o the channel assembly 27and ten inwardly along the coper surface of the lns 32 and upward thus F:rimog flat lift for the web 30 and also cariying away sol.vent vapors in te web, Air also flows into the channel 20 and aroond the elements disposed therein to cool the same 7 and then ul Smaer 7 eaks out through theclane netween the les 3 and the side member 4t,11 n sweeps cnxer the outer face o tone lens 32. Direct and indirect infrared energy rays ipneo the web 50 and heat tyhe web as it passes over the oressue sad ceated by the Coanda blots 7 thos drying and evaporating solvents fromn the web. This? in co tination wtn impinging flow of air 7 maximises toe heat t ransfer in the area ol: the pressure pad. controlled? such as by n SCA sosa h muto energ output transmitted from the infrared sourcee 25 snouce aranqe frKom full power to no power, and any ba i e rage ereenetween points Nisc 3ced hee tv an bar wth lteast oe primry stm or flotatinfo and ho t oter or the we an at les n itqae energy to. best. and/r" dry tie web' hnnc-XO~~tif with at least one secondary air !et. The at least one-. secondryaati suppi ed by about S no IC 1 a otairpreferably 7 to 15 whn i s o h d PaLs ein in fluid conta at Tas wt one r e"mitter a nQ is prae feal - vAlso quxded ino fluid contact th retacmtr and further Guided in fluid contact wit ales that is tranami ssible to infrared enmy skos cantilly pall Q Ald low irection to the lens air in n. n oe a: east on r0, - ar jet tho ens nrale flo proK0 Vin 1 ng sufficien co a to t emitted retor an lens elements to peeto igniion of combustible web orcati ma tart s even under uoet Oesdtion s An optmm a ot coos n r g in canhact wt h the emite rldcoer nd ens su" ace3 io promote elfetse cryxling cf tne emitter reflector and lens, and further the cooping air is guided after tontatian and gnn eat from said safaces to delrie mass flow and t nai nergy to the web by co dryn nclsure from coats ctin said sar cs~t P rom t he forgo eing discuss5 iona it can apprcae that the combined cgaeC~uton ad ranrat aon neat trans:er nodas of the present invenion are driven sustially irdependentl by virtue of the cynecion ai t mperaue and emitter temperature respectively This feature can ce used to advantage inte embodiments disclsed herein tor he prpoe ci r aihy drIc g hoigh mOsre aea dispariies mees'fture across a weh are common in pnting where heavy ink images are prsnnt alosie of now coverage or urinated Weas. The emdi ments disposed heren provide a selectvity in heating wet areas in that the heavy print areas require large neat flux to dry quickly and remain at r near tne we temperature due to the evapat ve coo lng efe thUs these areas il be ubsta aly heated by nth radiation and the high velocrty convection modes provid by this infrared foa tation air bar. On the Ote hand. those areas having ittle o no coverage will Lend to increases in temipertue y he id raced Taitonfo the emitters, bt near the exit of the dyer can be cooled by 0 onvection air to avoid overheang e electrmaete i energy from the intraed eleents is emitted at a relatively hig temperatre (typicaly 00 0P) compared to nhe web temperature typialy to 300 ll As a resu acading to the Stean-osltrnan law tOne emrssive heat flux to the web changes relatively litle as theeb teoaue i ncrsSneus th emitter temperature is uie hgh n h mte aocordinq tthe foth power of absolute temperature. By conta the heat transfer by onvecnn is cA ven by a near otenti al between air temoeratuis and web temperature, The maximum web temperate for a gvn web material being .hermally prcessed is often limited dun ng the drying opertion in order to 27 avoid qal ity defects in toe e or coating When in or therma ra!n assemue.b h auathrer theymar rde in tunctn and appearance often becoming thermal raing as specific V y UY ei manfWaturr theyma dleg radiiein meonanical performnce as wel as appearance Aop heoiny dicood biteoodsotd o example, polymer web materias suc as PET may sotn n stretch can ini distortion of th initially piea w' esu 1tine i n waves or cooc- mn espec:ially at temperatures exceeding 2 0 00 Paper webs may exhit slirnoace of over-cried area ha-wino less than 3% masuro in proo neavy cmaed or printed areas navlng moisture levels sveraiv poeren higher than the adjoings areas. Paperboard tends to curs. i misture n oe sin e s educed to levels several percent lowe tha the opposite sine Aditonally eome hr e at temp t s te a of to 100 FOnd eventually burn at higher temperatures order to aod tese prbes rnes9n uvreso we materials wil b faiar wt h :maximum temperature . imtatiostoprcs-i otewb and coatin tArough spec iicatins oEovrded bv the suppliers of te material, or fro pot tialIs or t eeri-n it a-leri in prior production processing. In embodiments dislsd hein; if the air temperature set point is s-elected at a emperue just below 0e maNimumm eb temp tur to tAlerated in te hatest (driest) areas of nhe web, the inhared eating in these areas wil be bcunto y 28 neoevi coolino, thus mitigating excessive temperature in said driest areas Air temperature set points from ] to 50 Fahrenheit degrees below the maximum web temperamure to be tolecrated were found to be effective in teperatre may be selected and regulated ao e y i in the nge of 0 to 10 Fahrenheit degrees above the wet buo temperature in toe dryer (wet bulb typically jg)A the o nvctive flux potential isa dimi Died and even reveteed, thus slowing tho rate of heating of the web in the driest areas once he web temperature in those areas exceeds te ai tmperature. In order to limit tne oveheatig o areas as described, the convetin oefcintprvie that os conventional cooling air systems employc sd nodn lotatio nrared dryers. Suitable air boar heat convection oat transfer coefficnts are in the ran of' about n t0o abu Ka 4 0 BT /hrft Suitbl a h1F Ir bar slot jet veloities are in the ranne of from at 5000 about 1600 feet oe~r minute The air temperature sapgied to the ozeCs maY he regulated b adding a controlled input of heat from an independent heat SOOOce sun as an electrt resisatlance c0l, hot oil or steam coi or a n the ducting supplvyg the ai r to bars in preferred embodments the need for an indeendent source of heat is obviated by rncsverinq the heat from t he emitters toot in not absoed by the radiation mode int the We into the emitter oo ing ar as prevousl dec similar the heat recovered from stray infrared energy (ectomagnetic waves that reflct or otherniA impinge on surfaces other than the web\ that tends to Nee the 29 ofthe web that have neen heated above tesupply ai temperature by the radation mode as described earlier This neat recovered in the re--circlation air may be retained by miimiing the amount ar enausted to about 1 0% or less of the a~ bar supply air thus maximizing the re-cr rculatcig air temneraure. On the other hand, if i~t is desired to lower the air temaerature, the amount of: exhaust may be increased to about 20% or more thus drawing in more ambient air that must be heated n herccultn lolse shld exhaust flow by mans o a dan eed die, der to accomplish the a manyl by an operator or by a closed--lop cotroller sensing air temperatures and mdlating the exhaustfo accordingly. In annot pr6ererdemoint th ar temperature may be regulated by mRoduaigth9nu power to at least one ifared emitter through a coei loo control er n teen mst prfr mbdmnt h noarv reo reuating the ai teprtueismdeb ettin o the dryer eutat to c Pev a deP-e to the at least one emitter^. In one application example, a printed paper webwt a waterabased ink, i tb dr T expcedbl temperature is ISO'F and the convection air temperature 1s set to 170 "F. The net; radiative heat flux from the emi tters to th unorisgted web is 6 O500 fihhr-df nd the 30 convection coefficient per side is 25 BTU/hr-ft--F. Thus the initial combined convection and radiation heating rate is 11,500 BTU/hr-ft and the terminal temperature of the web, where radiation flux is offset by convection cooling in the unprinted areas of the web, will be ~300 0 F. Without the contributing effects of the flotation air bar convection air, the initial heating rate is only 6,500 BTU'hr-ft 2 resulting in slower heating, and the calculated terminal temperature is over 8001F, well above the ignition point of paper, In the preferred dryer embodiment, the infrared air bars are placed 8 to 20 inches apart on each side of the web, with nozzle air jet velocities in the range of 5000 to 16,000 fpm, with the total emitter heat flux per emitter element mounted in each air bar in the range of 100 to 200 watts per inch for medium wave carbon emitters, and 200 to 400 watts per inch for near IR emitters. Air temperature set points in the range of 150 to 2501F are preferred for water based coatings on paper substrates. Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other feature, integer, step, component or group thereof. 31

Claims (18)

1.A method for regulating the drying of a web in a dryer by convective and radiative heat transfer, comprising providing in said dryer a plurality of air flotation bars having an infrared light source for emitting electromagnetic energy and a reflector for reflecting electromagnetic energy emitted by said infrared light source, and regulating the air temperature of the air responsible for said convective heat transfer to a predetermined temperature.

2.The method of claim 1, wherein said predetermined temperature is 10 to 50 0 F lower than the maximum thermal rating of the web material.

3. The method of claim 1, wherein said predetermined temperature is 30 to 100 0 F higher than the web bulb temperature.

4.The method of claim 1 including the step of regulating the air temperature of the air responsible for said convective heat transfer to a temperature 10 to 50 0 F lower than the maximum thermal rating of the web material.

5.A method of regulating the drying of a web in a dryer by convective and radiative heat transfer, comprising providing in said dryer a plurality of air flotation bars having an infrared light source for emitting electromagnetic energy and a reflector for reflecting electromagnetic energy emitted by said infrared light source, and regulating the air temperature of the air responsible for said convective heat transfer to a temperature 30 to 100 0 F higher than said web bulb temperature.

6.The method of claim 1, wherein at least one of said infrared light sources comprises a medium wave carbon 32 emitter, and wherein the heat flux of said emitter is in the range of 100 to 200 watts per inch.

7.The method of claim 5, wherein at least one of said infrared light sources comprises a medium wave carbon emitter, and wherein the heat flux of said emitter is in the range of 100 to 200 watts per inch.

8.The method according to any one of claims 1 or 6, wherein at least one of said infrared light sources comprises a near IR emitter, and wherein the heat flux of said emitter is in the range of 200 to 400 watts per inch.

9.The method according to any one of claims 5 or 7, wherein at least one of said infrared light sources comprises a near IR emitter, and wherein the heat flux of said emitter is in the range of 200 to 400 watts per inch.

10.The method according to any one of claims 1, 6 or 8, wherein said plurality of air bars provide heat convection heat transfer coefficient in the range of 10 to 40 BTU/hr-ft2 -F.

11.The method according to any one of claims 5, 7 or 9, wherein said plurality of air bars provide heat convection heat transfer coefficient in the range of 10 to 40 BTU/hr-ft 2 -F.

12.The method according to any one of claims 1, 6, 8 or 10, wherein at least one of said plurality of air bars has an air bar slot jet velocity in the range of from about 5000 to about 16000 feet per minute.

13.The method according to any one of claims 5, 7, 9, or 11, wherein at least one of said plurality of air bars has an air bar slot jet velocity in the range of from about 5000 to about 16000 feet per minute.

14.The method according to any one of claims 1, 6, 8, 10 or 12, wherein the air temperature in said dryer is controlled by regulating the exhaust rate of air in said dryer to from 5 to 30% of the supply air to said air flotation bars. 33

15.The method according to any one of claims 5, 7, 11, or 13, wherein the air temperature in said dryer is controlled by regulating the exhaust rate of air in said dryer to from 5 to 30% of the supply air to said air flotation bars.

16.The method according to any one of claims 1, 6, 8, 10, 12 or 14, wherein the air temperature in said dryer is controlled by regulating the power supplied to at least one of said infrared light sources.

17.The method according to any one of claims 5, 7, 9, 11, 13 or 15, wherein the air temperature in said dryer is controlled by regulating the power supplied to at least one of said infrared light sources.

18.A method of regulating the drying of a web in a dryer by convective and radiative heat transfer substantially as herein described with reference to the examples. 34