AU2014203812B2 - Improved infrared float bar - Google Patents

Abstract

A method of drying a web of printed material having at least one region of wet ink coverage and at least one 5 region without wet ink coverage is provided. The method comprises applying both convective flux and infrared heat flux simultaneously to said web and in the same region of said web such that said at least one region having wet ink coverage is heated by an infrared emitter source and by 10 convection air while simultaneously said at least one region without wet ink coverage is heated by said infrared emitter source while simultaneously being cooled by said convection air.

Description

IMPROVED INFRARED FLOAT BAR The present application is a divisional application from Australian patent Application No. 2013202509 which is a 5 divisional of Application No. 2010256680, the entire disclosure of which is incorporated herein by reference. BACKGROUND Embodiments disclosed herein relate to an air float 10 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 15 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 20 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 25 assembly that encloses the emitter. A quartz lens is used to enclose 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 30 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 1 coo &o Hr to the web surface aer flowtov zaroud said emd t hb flow path is not optimized for both col IIO seeenty implied on the w . the arrangemet with passage of air through holes i the quanrt cnv does not provide optimm fluid cot effectively cool the emitter and lens as is Lesired in order to maintman longevity of these componts against thermal degradation or or does at medarise the recowvy of heat ftom the emitter lens and reo ector, it is ntuter desirale to eep the emitter od iens free rom co da inat? n by ago tst s vagor .l icvni h such as lakes ndo coat ii1 nimaterial- s, Wno other cotainnt onc as paper dust or charts ot ter i farom rokoen webs. Q2oung and prevent o o nat th reflector is also sira for the SMAi reonst as dirscussed fo she ensfsc contamination occus, the infrad energy by the guatz menial of the ellitte an nro ln insugad of being transmitted thrno sai uart! t h web SVrrCO 1 which results in I 8 DE clyinc a bt t rooser ci en., d also promot$s t h er m isqddtonr as te design tiprt r fCtheemitrlan tens ma terals may san C"d' con fa~nato will reduce the ref lcti0 Sy or th refloLro resltn in l ossn of dryi ng and heat trvansfer efficiency Cotinrd ltero erdto As is known to those In dryers in is desired to prn t possible oii on of combutible awtrialay suoh a soud sa comustible materialn cOM into contact VLt hot surfaces, it is further dessco to have A o o aci means of interrupting the bat fun from the infar erot.er f om teachig the web to preven igniLion ok a stationary or broken web. A means of bino rhe infrate nea f is tauht n u Sateor Non 6,049 995 and 6.195 909 (Ronne ct. dl but rquoie dietection and an active machnanical means to assure that the web is not exposed to temratures exceeding the ? mimOn temperature of matias ben processed AS is known to those skilled in the art, it is often desirble to use fast-cooling tungsten or c on filament emtters AS are milabnjle from Heraeu s Nobl Ion.t or anac, Germany These fast- conlam elAe m minimize the tie necssay moving the lot raeod nmat f lx and n %Ascrxe norftaco temperatres low enocs aor ni coWbustible material sho th we i an \p3et to the dryin Process. Evn with such <told eo!ing Emtter, it i$v desirable to keep the exposed surfaces of the a floa bar as Ool as possible at Ql times to prevent possibe ignition or said mbustibe materials, nevn when web stoppage or a0 nbrk may go undented it i& also known to those skilled in the at of drying materials by means of infrared energy nhat vhe amount of neat effect vely absorbed by the ateri i eydan C a mber of e tor include empratre of the the ydefiing t infrared light paths to the matedala, ad the absorption hracteristi the matriais o be red desired to select an emten type gno1 that it temperature wil emit manimm jctIromagneti enerx i tse range A wavelengths that orresp wi t wavelnnths of maximum M paanti il e dred in the case of a coe we thial typioaly include the base wet substrate 1 and a coating nmgrieed of olids, and a solvent such as water Or en oganic solvent, Said solvent to bearrest EBc 3 materials exhibits an infrared absorption characteristic a a furotion of infrared wavelength 1 or spectra, which is to be considered in the selection of the type or emitter to be used, In some cases, such as printing, the coating or ink is not applied to the substrate uniformly in all areas. n 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 coated and uncoated areas ar 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, Tn 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 aras 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 of drying a web of printed material having at least one region of wet ink coverage and at least one region without wet ink coverage, said method comprising applying both convective flux and infrared heat flux simultaneously to said web and in the same region of said web such that said at least one region having wet ink coverage is heated by an infrared emitter source and by convection air while simultaneously said at least one region without wet ink coverage is irradiated by said infrared emitter source while simultaneously being cooled by said convection air. A channel assembly adapted to be inserted into an air bar, may be provided, said channel assembly having a compartment defined by a bottom having at least one adjustable aperture and a pair of opposing sides, said compartment comprising an infrared light source, a reflector of infrared light, and a lens transmissive to infrared light. 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 minimize the risk of ignition of the web or other materials 5 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 5 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. 10 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 15 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 20 air flotation bars provide convective 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 5a bate e e t i o u e sCh a, a eler oated in dti yppa the air t o 01 OL m-' air bars An tWe dryer In nnea a , and thuns heated becme s aTzj\3 for enhanced convec ion hat transfer and mass trans far to the web, within Vhe ryer. VaOW coolVi air, now heated, may orwth in nn con ive avrta= with th "eo enc heat tIansW t~' N emboo meet Wci osed he reina the, c00% tny air ath is a rraned an te aiA flW maws s do pro de c Ci opt cool :n snand t avd potential .iinton o wo materi als while Sax ittilng tP, ak en up by the ooging4aro us wo aating andi dryin SUrt beror t ;ee co a tl tSion air sets areblcacdanm nSointera direcn between tK ,e and air heat 0M ur'nser heat convectively while float y xprting th e b After cavectvely contact te we th combe i5 rma be 0la a to supy of ne r and a portion fl>.r iTculace 49 9> ~ya''-~05 rmr ai ho S. bErgoy "Inumtn tofntoVA WWrWaazed when the amount ox aiar r'e-yci Soo laei max$mv1a:cd' -h'xhaust Vont .atinj rate 4 that is the ha lance of at, not ne-Ocx ate. c. y be s b toe skilled in the art o Vying to ma intin a deal red wet Thuittcxpe~ftrcwithin the dryer such. that she dryla!op 1 aa abe pe Q vKYqa smae so~Iree' W oo as itg r the, A.0" rOn ei ony rate 50' to ShN ofthe tona cnvection dr I ppi t no the air bars. in the cane of A l 6 solvents, the ventilation rate is most often set to meet the ventilation safety requirements requiring the dryer to operate well below, typically 25% of, the lower explosive limit concentration of the solvent or solvents being dried. In a preferred embodiment, the supply air to one or more infrared flotation air bars nozzles is heated only by the infrared emitter elements, that is no other independent heater is required to heat the supply air, this saving space and component costs for air handling equipment. In a most preferred embodiment, by maximizing the re-circulated air within the dryer in a range from 70 to 95%, the convection air supplied to the infrared flotation nozzles may be heated to a desired temperature, preferably in the range of 65.55 0 C to 148.89'C for drying of water-based coatings and inks. In a further embodiment, the flow and temperature of the air supplied to the infrared air bar is regulated to obtain a desired convection heat flux to complement the infrared heat flux to the web being dried. This provides a unique means to preferentially direct the heating of the web while drying both wet and dry areas on the same web, as in the case of printing. While drying under conditions of constant infrared emitter temperature and constant convection air velocity and temperature, the wet areas of the web are substantially cooled by the evaporative energy needed to vaporize the solvent, such as water. As is well known to those skilled in drying, the wet areas tend to approach the wet bulb temperature and remain at approximately that temperature during the constant rate drying period, until sufficient liquid is evaporated and the evaporation rate is limited by the falling rate drying period. Upon entering the falling rate drying period, the web temperature then climbs as the evaporative cooling diminishes. In the case of 7 Pa'lotimq soa-ar ass of the web axe he av covredwit ink while sore areas may have 1itle or. a These w coverneS areas are relatively dy asd often enter the calling rea dying period almost immndately upon enter te drr h te we te r in rhese areas increases aignificanty in cn at to relatIvely wet areas, noen ress a tat the Tez oF the dryer which exceeds the desired level This say rease tin damage to the web product as well as westing energy inoverheating ttese in embpditnttst~ dict osed here in the high convection neat transfer characteristC of Se nad 1M tion bars is applied in combination wth nfrard rad mode etch t,,.t the web tempera rolatie aet and y aMe O eni o h S e a be reOuced Ths in acp i shed b t c d action ofl the two hat 12ra55.t0 MOKPO convection and rThose skilled in the art of heat raste recsira teyt the heat i4 via the two Nones at s imutanecRsi v and th ontiuto ro ahOoetcvb aditive Or rk opposite to another Tha infard anerjyis heating an Aojec it mya h ~n time he losing heat via convection. it is an "bort of the eMbdiments drscioned heren to prede a a the wa menined h mode sc that orheatin of re latively diy areas AT, as areas is avOided or 9aiontec witout the nura i r al Sreedy described Typically whe h e trmetestedyr ti ooler than the air temperatue an hs a etv beatnd addi tivelybct aito n ovcinmds s the web increases in tempertre spcaly i relatvely dry (low cov0 ck areas~ th inred nry Oeintitde& to heat the web, but as the we temperatue 8 evtvaiv eceeds the regulated air temperte dry areas, the convection neat trante now acs OPoppst to the infrared rediation and t tnd to ep as of the we retieLY colr. Meanwbxle th wetter areas (hinher coverage) will remain t a tempera t -re (bhow the regulated air te ing to the evaporative coaling efect reious 4 d e C sequenth the dving rate is d by oth beat tanstes moos in the wetter a :ea om heat ng by Nn ''~~~"~ ofru ar radiation and convectod :ueg t3 temperature a lI jut above the Wet MRl tIfl4?C! &uVSev i n the dryer. thQonnd nrrc and onveco ying characteristics of the present invention a selective dryin9 cCion enbdwhrn fast dryng n gEonoted i high CovEace aras whle. m . t iesting the tendency to o e th e coverage aress in prior art, the pply regnirment of No, coo!in i a been to te eof te asscffed lemntssuch as the ret lecno: an0 iens.A metioned bove it I an obictof h m~iet disclosed herein to regule the t the ax spng 4 to she infrared air bar to meet& a Ae trmOO.~tttOieatting balace, in wet versus dry areas. Q, tne cooling irt teto be a reoiated vriale, ts pConal A reqMiaems a the am;dlJod cn or te coollry fviiiw00 for emitter and Macde eleme the erhients described aeiKn, the cooling air flow volume and path are i cry onslieraition this va cto I i LOneaua ooking mN NP the infrared a fr, fared elect:CwveCiO energy waves pig s from fo emitter H lament by tas in a strach~forarddirct annr t iminc ona traversing w eb I aditrrc waves pass romsiey b'OT h center bub aslq use $ t ,o and rtC the filament and though a planar nanil lens aerials are typ ailly of quartz material havin tranamIssve properties in the waVeisngth ranoe of ira red e Q!e $: )ttti gne e t. infrared lomtroegne tic wanes ace also ref .te d in an indlirct manner from the emitter to a reflecto srre tft eewots te taves aih men furtneLr ns throuc the planar lens to impinge upon the trowe" in woo, As As known to thosesl in the ar of infrared eney, a no b e Q~ oX e; a Lotroa 9 ret iC tarNnM Y that e ntoor S a nransuinswe material or .impi qe on a to fleotive surface iaAguet Ti nW'Ao 4 Nc4 dnrvrie ho 'ortr of the troansoivSrre or ler wvnj V tarl and may to doradaton of es e o reflootve property, substantially reduin gn energy eachngnq the WEn> and as result in earl alure of the enILM and, lens mariyral. This enemy is useu in heating coo drying ths web when recovered in an ai stream; is then bragnht into ftid contact with we web. recovery and cooling effect ess ae n Carrion out i a no00cr Wat "&Y' t,.AVin MO." oon co w2tta con tror quntity ofOz o air OCO i-a io 0: the present oodimen t SaN shown ta t-5 can be accomplished ny passing fow 5 to M, prefralyf to 1o f the total air suplyde e der kes to te later ar throh an airt S unoiform titni" cntact~' with the emitter bulb, and! further niromlt flow at n fid contact over t contao With11 beotn races 0 teO ia1 es ot preferably; hs a i)w 0 Otf9er sath rng.o to 100 Of the total supply Ar to the Wlter bar 1 10 viddageno the unifom fluid contact of cooing air wttt the Emter bulb relector wa lens nerces parent. (XtfaAnfl by solvents and otter maltzrals mentioned aSwembly adapted to be neestec on :etrotv no an. alr bar, whe:ein the channel assembly has a oofet oeHn by o nottam having at least one arre and a paiv WE opposing 3ideng no c40m tmunt compriiga in 'ed Ofht Nl~noC N a s Cfcimp o oc V and loo tvrmosni ia- tofnN l .a ight. The 'nevtUre a'lows for the 1low of rmoln Y a ab- th d' iqSt souLeY Teflcs h 0a e t tan a . inienl asmnly i s coio red for c of the Loonfrt ed enier and to allow the of the p 4essn Id ecoll air flow to the opt u hus the Ctn 0an be etovedi and IQ= s retalced or repaic, and t he dMe! then into the a br Wa nr the onu ae anda channel cnbinserted bSnt t N> ba ajxted . TOe Mlys turcuoh the at lelaswt ne o abatinna n~de nti e~cL 'aston of said moba e lemnto so n aa C et asp to ow a Aor a a e%<es il to aperin Hlow ara f t h A 'CS 100 -. ,Invasents. TOOsetting i 'U ">j 0 enr'' the pos Maon of aaid- toVOC5mH41'~a-~r n mcnlinn A the mnttst nd t ind mder Sclo Lhat oay AOr the OZ sir tpxat-S sereotad. in adoloNIn tvn Conlinai flow is set to mnaiAn not' n te aon-cctrsI'nlnsnd a,,, b ar oterantaces that may cnatte e wold th web break or otherwise lose tension, to a temperature below the ignition temperature of the web material, preferably <204.44*C. The practical range for the cooling air flow setting has been found to be from 5 to 40%, most preferably 7 to 15%, of the total supply air delivered to the infrared air bar. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an IR float bar in accordance with certain embodiments; FIG. 2 is a cross-sectional view of the IR float bar of FIG. 1 showing infrared energy waves; FIG. 3 is a cross-sectional view of the IR float bar of FIG, I showing airflow patterns; FIG. 4 is a cross-sectional view of a single-side flotation IR air foil in accordance with certain embodiments; FIG. 5 is a cross-sectional view of a single-side flotation IR step foil in accordance with certain embodiments; FIGS. 6A-6D are schematic illustrations of various IR bar configurations in accordance with certain embodiments; FIG. 7 is a cross-sectional view of a Coanda air float bar having two IR light sources in accordance with certain embodiments; FIG. 8A is a top view of an air bar showing an air flow adjustment mechanism in accordance with certain embodiments; FIG, 8B is a side view of an air bar showing an air flow adjustment mechanism in accordance with certain embodiments; 12 no,' OA is attom view Of an n . ba shwnga air flow ad]an ment diani'Sm in accordanld With vzurxts emibodiments; G an od co-scti vae of an showing sn air flow adujutmEmt eahnne in accorlanaa with artain embodimentS; I. 9A is a. nop view Of an a f low ada osbert rnnohnism; in as'Cosctanacestacta a mbodimenra; F'IG. 9B is an end oross aeotioal view anaioa snowi ei air fi w aijastment rManonn e min tacoone with coetan embodix'ents; FIT, l is a schematic diagram of a dyer ancr aqa plurality of R float bars in cnocuwon ih sppl it rlati t nd qxanst air FIG. 12 is a sea t iram of the dryer of FG 1MA depictni e appayvai, cair tar t LW r Sn MG 2 in a scheataic dingrzam of R Id z e Its, 13 is a~na ofh a dre anromaOating a plurality of flat bars i , control wa conapnctiork wick suplt air osi av: exhaust air stores in accord wit Certain em~boo a m :tSa DETAILE$ D CZRIPTTIt ocenotalb te float bars daclosed heenhv n Or moan patinary san jets wic disohag rmsoo he primary rs cr ate a pressure fdf t foa ting SUPPOk as>. The air app ld to te : rlts 133 be optroaily heated to enance bea and/or mass tansfe fox diig of te wet Air for cooling Le emier refleacnr and iens eremnts conan in a removable ornamel may be taken fom the same supply penm m the p iary flotat ion aixr orcteartely ducted I or a separate aiv 5Oiee to the channel assembly Ater cOntacting oe emitter reflectOr and optional 8pla3 1=t, to cooling air is discharged through one on more seandary jets whih Sweep the fa or the planer lens Ord prevent Contact of the web and sfrom the ions , rIGs. I and 2 h referred shoi t the floater bar element 10 is of the Coanda type hvn two primary flotataan jevs; a fts rst primary loation, Slot 1A av a second pdmary Flotation Sot 12. Two secondary alt slots LIP 5211 B . at are prefeaby S to 40k of the prmar slots l 1 m ys eferably 15 to 301 are also provided as shown. Soply any enters t0e supply plenum t of tMe air ar 10 via a ppY at: VMa nidet 16 (e .g. a plurality o soaped a tre locaed at the botoOm 18 of the dstnu'iuted along the lenoth of the Mc bar no oWtai suitable distribution to the fotation lets as is nown Ste art A Infrared emt is conf igured as chane assembly comprised of a supporting ae1 20 which contains a reflector 21 in trv omu nioc n t t upply aIr plenuM 15, or a separate coo9ing ar Source 8 ment ioned earn by eans of one at MO apetues22which penettate thw e chnel and are in' rUect t the nof tmagen contact with the base charnel 20. The total area of the a pertuores isN preferable eivalen in lowarea to 20 to 1004 of the area of the pmary flotation sOtS 12A 1 M, that is, 14 s1ot length X SIO Width X wmOw of slo The avc acea of the apetuares may be adjuated by aligni g the array of apertues in the reflects 2 :ith a comparable array of apertures in te basse channel 209 ranging from fll alignmnt to Ccmplt 01S0ve thus acting as an urahle damper for sting of the cooling air flow, sucitable meschanihcal Meano of 3UNKY inq e rector With, resneot to the base' cAnnel to achieve the desired aignment can easily be acomplished by tnose sIe Pa the art 2 &\.,. ASV( shOW <i4.t-NVnd embodi ad fsr the sliding and tat ionary element in the channel assembly to enable the adjastment of the infrared emitter cooling air flow. 0IGS. 3A and B show a - i-dig atustent oment 7 wdth circular apertures 22 at can be alignd with corresponding prererably large aertursi s in the removable channel 20 Orenondin oe saJed apoCntitS are located v rs elector e nt. 21 suck that these apeurtures coinide with the aertures 22 i ao.'e nne! 20. 8dng adj ustment <lots 270 t aow the oveable e1e1e:7 o ge 50 gS t treantive to reflector 21 and removable channel 20 such that th aperture 22 open area s reduced Srm the fuly concentric alignment posiu . Once tohe appropriate potion of the edgonsMent element a Awnc 1 the acnatment Qeleen Cap be fixed in 1,lace such as b tightengno bolts or the like in the sit 27o. F10S. and 9B show a more preferred embodiment werexn age tres AN. in the sldino adjutmen element 27 and the Zpetttsit 22 retmovable channel 20 aen dian dah ads thus allowtog a finer adjustment of nl; hen maing the sliding adjustment elnent when reducing the apertue 22 flow area. Apertures 23 in the reflector 21 are chlong.

that is supported on istrroutiOfn eo $ ide menwber' A l 0 that each te lnate in inwardly Wing terminal ends lA h oter surface of the chamber 1 ansition bWen t the Sye tri nt ar00 A u e so as to deise, with the oo tshe sidle TA Bo the air bar 10 yo&503 Acts, whion are te primary flont.on Li±ts 12A, i 2B. hen TPoV&X2. CKne 20 can be S1idily remo vd t rom th On ha r C0 aO No with Ins contents, and mitho he I O b another 2nht' A by WO he ame htc replacement of the lens andox bcl coti teen S itia x di str ra h M C z peroXatd 0taecan be provided in the air howr 10 to enhance n torm supply arr Ann arS Of about r such a mem to be suitobie A' all ditibn~ peoe 2,sc anplte & SOCOndaryV CiX 01 rbtdt,?~&X pserxorated wsth slots or hes cn nopstoe downstrain of toe KO O air s sOn can serve to suqyina the OanqV a) cunel 20 coa as an TP enit Lr bulb oomme ' a .. e from Ileracus Nohlelt h(mb> A lens 2 r.frbyapa quaxt T' enn, can be positioned aove the tR C i ht so1UML 3 la shownsmisiAn e s em r i e rarye or inf rard wavelengths to pass through and reach. the web 50 float no ahove SOe harX 10 WOiG. 2) Lieca ernery emited from the IR llqht source 20 passe roOugh the tens :2 and Cix'etly radiatoto the wet 50. A reflnetor 21 is alsn contained in the channel 20, and is preferaily par:abowic and made of a 16 sujtableo re1tecttvve material such as stainless vteel w.4 Aleetnem, ji otorauly the relco 1ext-ends r h ans dOwnwardly nbbo the IK o- r C h coewpd by the lena" o thetI igt emittd trom the n sorce a r re t r h t lns or is reflected L arwo toward the lens and Is then nitdiinvte 1ed '4 "" the web b0 a diaqreimtati8 u The W 104O2 one Jolined by the clears to, t ' 3 provnw't tnon the An 32 and the > .,WK u sa afe ch nhandov 20 A 3- supply ai fed into toe air bar at inlet in flows: through the ;vvigravel inihial air distT on roenvr iS tob 4,p4,N C sew enosy air d istc bmeMb flon' stin~+-4 i w '- 12A N 2 Q 5 Am=N'wh GM essweated to loatiiglyChuPt0d the Wab m supply ai mis. posses trYoc t noo0 Mg ait en into in ? t herner ,:if "he cno! 2D, cld the ref-ga" r -$c / nd 19erea defined byre 'e< ator 21 and the 32 Wr ar thus oo the emi-ter 10, the r-fvot and Y ' 1-'r' The rose in noe----- ar Ahen Rnf cut oi theN WiMr O' T4 d eeps the faceofte lee dt ree in tact o the wb aosenn 100toia an teatr icr±6 0o contaminants wih the ns 32-. Thos slld i the art will apeciate tat the: fluid for covnicec st a o'r K&l"'' acd en 12mot ma- WOcane as cor e s to y 65a8h aA in certain eand-sena- Av lens 32 ca-n be - omiudt-ed and the air dis-hared from the channel 17 ujsed a virktutal. lens, effect iv she mn he cl ~C LCIO t3.t WisandI potenV -, Vl-zaco1.ders o Ott0 a nets PiG, K 11lW traves an embod5 bent wherein the finat DO ~ ~ ~ ~ ~ ~ i toi ID' sre'ideLot3is v"In thiS ebon, single primary n ontat i oni it ~ ist d d . .. % the web )0 Nd a 53i000 $.da j~~En t 1 i plxyided to dsceharge cooling air Crom the removable <'ace) rsmm3 20' The fild 1W i deh' ed in part by & he~Aa f: n h e~tNeP oenn 1; bowt is gen e ra Jy CCUr- 0 QS sacon excegg for its top prton o Oppcs:Lte sides W V of ithe header terminate i respective top nlawjo t o A Top f2ne portion W angled pre.fnd i- rebouivCte to NetNa and eXTfdOS towas nopsit Sid T' in a arigental fashioa. The header9$0 1 N hat sec-Cs as a plenam fat r te gas tN h "' "n"'C vi& the one Or : re 501m; 'N' Qon at. th ase lot the ix: il iL Qtat ato in gmanoC 1l with a goo soQ i y (not shown) . - Th ,aet is O' t 100 0 sUitahbe Auting by alignin the 9a.m arS in each ariA e' ot f I hei header and0 :5 seeded bi 31ainr gaskret 4 A di sr pate hing a r tof Sp o s can be positi oncd in0 the hecder so hep ditiute te Stu9 c gas3 er.l 10' n itS lows towerds the s The flange pm o" O on z aption 13? the header, roget w th the L t 0 2n of the mber 2i di the one Primly S0. PC ot out the Primry VVV1 ,an cotnues in tha W on 4f N tKo l.,t,0 of web tiara! owi'-rdn thy !g1 of She sit foii, whinnh Wing It teminasea in a oe a e di dl t a rght angle abot. O inches The air then travel s along the top MCC Qf the wing in the dire~tin of wet travel to SUPpert the W . As in the eomdiment of F I an optionaly remsovable channels 2m is proidedteand COntains a reflector 21r a aMs 32, and un i igjh Source 30 Air enters tCe cnnrlea3 aneady 20 through one ox mOre aperturs 2' in h ember 25, eada Wl n th a t$epC apIC esure 23 the bottom 401 of the channel 20, an OCoo the C . & ligt esuro 2, and the lone 32. Thn c0n i '. is dishage from the cnhannel 2z <ia the clearance between the lens 2 and the fMat port 23. MG, i5usarates an eabodymentt wherein the floa bar is a igl id ation step foil o uO a" that dIC OWee in U.S. patel No. 530. 179> the eof which is heb ncoporated b eenl V W alt th r r 10' of FIG, t an opt1onalY removable va'e! a1 ssebly 20 can be provided at contans the refecte 21, ZR light source 30 and len 3 ULn. erences between the ermodiment of FLU S arnd that of RIG i d ne e the FIG 5 embocdiment the pravsi-on ci send seconday SLt lT , spaced from anOd stepped donr rm the i stiy, ist o aid in floating tWe web 50. AVt discharged from the e dairy diechargr s1 Olt travels pafallei to the we Air Ob fromnthe pma ry dia Th$qC <'10> 12 <U c98~csx Ptwmi .wf th a r'Q' 4 n w secondary dShr Hetven the p 0argy dischaige 11l, and rhe a 4n9q, discharge sio $ a gonetally f$et a &h tsnrface, inctuding oh face of tHe len 32. Dene m of the second r' d "hrg a slot, in the dirOctin af web trann-t is a scnd wenb "appot snface that comn ses a wing portion chat .gges downwardly as it extenos away from sg gecondary isecharge slot. 14BI <5 second weoh 19 ponrt urzae option "y san include a 5eco0d lens 332 that forms par or an oopional second onhnn1 asenmbly 00 >t~ng ing a retlector 21. an 90 Pht 501CO20 and the lens L22 the sde . o te stepil CeO one re ox me aperturco 60 to at ow sp. UPairA (or ad CO L th1 colione s therein s iG illustrats a futer embodment in a onda n le havm' two Goo di Char~ stin te embodiment shown an i lg e positned tushee i ai r, s st0 ndfdshag that def ined in poit the conndisoata ltI icludes Onge'rt100 t~~' ht lo w ro top nMS as through and flow about tee IAlgtSotS$0 oC~ the ame. A 2 Con be pos tinR ICQ h in source 3 Y that is'rnm osetoeetrmgei 110w ot air n b. ,A. h I t source eenotivey, the toon a v lens., keeping the lih sourc 0 oL n reo can be posrrned downstren.t o ieto e taelg, of 'the second onastlD" ornedia manner 5II.. 4032 t theu pt 2a1asby. hedwtro 055*AESUy is shown withoua les, alsolhoe o&d0 usead as 3.n the upt ream assembiys P10$ 6A- 62 ilmlstroe agta erae;n piuratities of iinared bars wint respeCt to a traversing web 20, Ic is noted that the air bars show are into at tiv Oigi any o tnearbremoint di scasocd nerein (e oanda ir131 t0 o etc. oan so Usod) , Othe' Aaagements ar loesiIe 20 2 SB i statess aity ,a irared a r 27a- t n's 3>t bgic traversing We}h 1s ) 4O raUtes a &biralivo rrr aror . S PreArs r3 E~n 0e 0 arr 28s9' 0r vgd a piurity of I a aN t aEaWigMU$ il rr at c'~i~ng vearrtl ya l nge a 4 .dryer e e cabore traveisgly wt27 o xpAdyr4 metravere&r'thweU tom ina Kd diut r heatig n Ued ir ar 23a-taan- hichra dire4. n no ah ez an Ehand0 d (rbto *bf hete suppe y ai r ecs T'~ P a ts o f desr"bed in n elat-- n rd oer>' n 'r'1~ atrstbu action or ae0 spend ai: ayb rco re fr hen~ at a i dvs ehutd oi terr ue a oonmnoU~O btwen the PlurSAlat o2 On>aed ail bars 2S0a-210n and 20023'n to wnh ce speo 1 2ive neadsr 3 2.C and 3 s 1e tin me oU fed oenWs 315a<Ai01 The air feed openings vcOM aeV nne d edAd to srr tar feed inlet 6 nri C 1 by means o p Seasrt on -~~o~ha! ili Pani Wo which. alE iay dscns on a n:0 reoinval o the infrared air bars rown the &ver The 'oints so-C H2 n may b eld wt eue:mtr& reason Seats; or er similar means as ar Inown to tsne skilled n the art A f 1OA on Oyer design 'instrates' the air flow pahS -'reated by the ai elellents w thin tu en closaye Kd of "ry 1 of 0 KOW 1' herein described. A rony supply fan 320 110cm KeAte air from ns'de the enOsur 30 and d scharge said air ande 9o pes e intw a plrnoz z' hwng an optional heat soron 223 This hat soremy burnr a heat change cnil ftrom a hating ' !a eW ; a hot water steom, ortEo' e, ctriO eMvn PO MOateM ;t P 0- o optional heaer 3, On hen$e$ air i 0A" "td to air dsibtoiOn on heater, 3 ao nd 31% via c-c' C and 32Gb, resec v. O-ptional eate f provided, a i c'tz " ed iyntrol lorot inC Thu hk -a d opr inthe r outod to Of r5e5 Wr owr= th1rrYon feed' cqstq 31 75, whcXYC% 0it Qis~esd to' arr foW path -, r ol lg Unction inin each infrared air ha e been&~ ooscred cevc-OO5 Y. I& CtnqiPoe fed to the sitners ted the web dryinq road UCh a dried product Oc ds hsrged c"'es into fAud ct exchange heat and mass with woth6is exchanc step. at least a portion o har P drawn acko the inlet of supply tan M. An ot rcom air is drawn into enOosun 3% through sob aicts 3M5A and 30S. An exhaust JOw baLanng this room ai and tov evaporated aIyts front tha web must be cetu ly vntilaed u e eTo this pao&. a separate exhaust fan 31 draws at least a portion of said sper w roagh exhaust duct 2 3 low control damper 326 and sit t alternative vtO e xlaos fow rata cou c variabl spe motor and dive on an 331 instead of cons! damper u0, The separate xhus fa fr embodiment 00a i cessary for safely band incr volatile fl amable solvent raterials and/ or in the case a Odect. fired uel burnear as usod for ptional ha tr 325. AuSC Now sat ventation vol ume and trem t e u1 (Iot shon) for air eel.lu tne a tertal> i sa A exhaust qmy be rnoufrd based on requi rements Set fot bK parties having oon 8uch inS Wheordei on e whrein a orplemon al W et be wood chat Fmyded by' the inn a ad air ru ar s notneddometheheal1 a reguiredbthwe. I Esoecse whrwb load rerouomeus are leis Van Wou d be ouu y fully populating all air bar P06sAtrnA ill cvtrIutn heads 1 Oa and! 510b, one or are positions for mountrog air hars may be oCcupinad by an air ha rwiout an active infared emiter, thus reduce te conncted powe load air header 310a is not fully popated with infrarda bars hut includes two non-if areu air bars 2.6a an 23 Note tin-ese n~- rrdarbr nvb fsnombes of types which are familjar to Ru skilled in the art of a abar des ign The acn warea dar bars ai re. rsatiail %oate& near t w d C t ryer and int the ca e Cof a J Osid 00atin 0 t a e b, Iocted anheucated sid8 Rle Srical 0me f ed L0 the e x'ons is '\9lated by an o0erato rrO0 9u user inverfane in SAmnikAG W anvo200409E nhe wnb d'A 'no 0ad in order no achivn # atIafC dd-cn -0 dut Them$pl y al tempex'te as gntdb con trol loop 0 to intain a set point by mO&Uoqi theI 111000k of a 3Xhawn 14 0nugh nx au sL duot 330 by 030 of p 13 illustrates a preferr embodiment for a .iriae sid a oated or p nted k-ob Whe re- W he ior ocat o is on the botto G -d th & Pcctia power fed tO &St6 S 42->501) 0 h~ 7e an S tR 342 aording to the ob dr ot achieve a satisfactory d tried P-ot. The ai tempratre is controlled throhyn 3 xS MA . reg-oAtes the aoer seting to -CR 341 which in Turn aloduites the power Q& the emi-a 2 4 N)faCg r )rrate A d ' f w The orar n o A thV i ary AL '41 b 1strat With r.4 nt' tc V0 -3 dine own in Flo,$O , pIuali uL> f inaraed a Ot agk I e2: Vs increase dryin csapacKV bneero the inrared sozran A, located an tn pot of 'ighVqE he 9 sfar between the IS v-oe s ''*t3~ I ~ v 4oyrce 32 either diren" ov Airt '- Y rvirr 10 la 3.Tthe tnfraed drying energy i3 trel' ned0 for WeA!,n a traversing web being proosaso n a yer. A portiono the infrared rays nelact off the parabolrio 21 24 and throvgb the lens 32 to .impart in ed ryine efle9o ;onol and heating tho web. The wave length of tha iWlNOrCd .EcOtromagnic rays emitted from the inar~lo not o N32. can be short wave with a wave length of O 78 t 2 irons, gedim wave ienth with a wave length of 1 he 40 microns or 'ong q ae length of 4a"'0 t0 or more tacCt1onst ebodiments th cerrtaid souode 2 is posititond at a venint of axinni eneryy wns Pxessoi'd afr to Kloat the web enters the i ed air bar nrough the plurality of oval snaped air "00s * 'to ft t hue web. rsay the air i rhe pilo air proceeds as indica ted by dashed arrow lines rW 2 tho cc' thne hoes of the in nt ;a air distri n =W, 19, through the holes of the seondary air dit M uO member 24. through the Coandas"WEI 12A so 1210 along the Cogada crN'b defined by ne Sid ebers 4A 41 of the channel assawol' 20 nod th-n inwardy along the ppoer t sec c ts lens 32 and uPWS 'td thserovt9 float ift uaor the web 50 an also carrying say solvent enor in the wb, Air also K into the Chnnel 20 and around the elements disposed threin to cool the same, and ther dtinateiv leak co hrough tec9sac between the roes 3 a e side members &A, &B2 and swoops OVei te ' )t2 W' We lIns is Direot and d rent inaa od W energy ras; min, on the web anK host he n v3 it passes a-eX the pressure p:<ad "veated by the Coanda slots thus ig and ev0p: tanng fonmtr tYanr the web, This, in 05025on with impinhg flow cy air, maximizes the heat oranwK an ones reas o the pressure pad. Otputi of the anrarso source 30 can be ar l control ed, spuh as by an SCP so that the amont of energy ourpot transmitted from the itirared saourc 25 inoludes a range from fll power to no powe, and any Chrein provide a b f loat and heat traoa.e si 0 U tho at .01 00 9 Iu~t~.0 .Lfrsare.W etitt for use in ron nryi ng or negLt trestment. of webs, so to to animitt Oe utilizatiof nrared q nrgy to beat an Ucory the web when to c001tion with at iasat Ooe qe"oroaro air jet The at leastcne seoondar a ret is suppl v by about 5 tc 40 A of Se tI air Qpreterably 7 to 'a51) whic ied G I V pa£sing i £ d Ct me UML er an is prel-- onol alsoquo . i ma'er Vit a relectot and dter co wim o lens tt is twansmassibie to hinared enro The seaord y is goAed in Li 0d contact 0 a sufa l j4 fl'tide at a--- tnLn r" a t in ennjunctimn flow c'Set o to the l the n9aNA o providing suftiic$en c&Wv; to 9he ot: c oeb re Wonaor odas 00 t a VAM> ondit~ionse An 0a 0r 'N ~ ~ Uh emL~r r 2 30 -llte eltor anid Letns tcn ionin ofthnMnezeadtn to promote etfecrive cola'sn0heeite:9o and lenrs And turtle t cooing nir is ed- atkP ontanting and '-aea t from st-Ps S -f>-E M deliver mies flow and theima a rcr to t a -nmve=tnt 0001 l~nipq 0n is als (401100 over- Pe -. aces to The -eln SaO prevnat CoCtact n ' Ole dhe n2e enno eiW f Com " OA '0 From the forgoing sC-S 0 it a ap that toe COtined convention and radia e r 26 modes of the present invention are driven substantially independently by virtue of the convection air temperature and emitter temperature, respectively. This feature can be used to advantage in the embodiments disclosed herein for the purpose of rapidly drying high moisture areas without excessively heating low moisture areas. Such disparities in moisture across a web are common in printing where heavy ink images are present alongside of low coverage or unprinted areas. The embodiments disclosed herein provide a selectivity in heating wet areas in that the heavy print areas require large heat flux to dry quickly and remain at or near the wet bulb temperature due to the evaporative cooling effect, thus these areas will be substantially heated by both the radiation and the high velocity convection modes provided by this infrared floatation air bar. On the other hand, those areas having little or no coverage will tend to increase in temperature by the infrared radiation from the emitters, but near the exit of the dryer can be cooled by the convection air to avoid overheating. The electromagnetic energy from the infrared elements is emitted at a relatively high temperature (typically >1093.3 0 C) compared to the web temperature (typically 65.55 0 C to 148.89)C) . As a result, according to the Stefan-Boltzman law the emissive heat flux to the web changes relatively little as the web temperature increases because the emitter temperature is quite high and the emitter temperature dominates the radiation flux potential according to the forth power of absolute temperature. By contrast, the heat transfer by convection is driven by a linear potential between air temperature and web temperature. The maximum web temperature for a given web material being thermally processed is often limited during the drying operation in order to avoid quality defects in the web or coating. When ink or coating materials are overheated beyond their maximum thermal rating as specified by the manufacturer, they may degrade in function and appearance often becoming discolored, brittle or chalky. Similarly, if the web substrate materials are overheated beyond their maximum thermal rating as specified by the 27 manufacturer they may degrade in mechanical performance as well as appearance, often becoming discolored, brittle or distorted. For example, polymer web materials such as PET may soften and stretch causing distortion of the initially planar web resulting in waves or cockling, especially at temperatures exceeding 93.33'C. Paper webs may exhibit similar out-of-plane distortion due to hygroscopic shrinkage of over-dried areas having less than 3% moisture in proximity to heavy coated or printed areas having moisture levels several percent higher than the adjoining areas. Paperboard tends to curl if the moisture on one side is reduced to levels several percent lower than the opposite side. Additionally, paper and paperboard material will tend to brown and become brittle at temperatures in the range of 176.77 0 C to 204.44 0 C, and eventually burn at higher temperatures. In order to avoid these problems, printers and converters of web materials will be familiar with the maximum temperature limitations for processing of the web and coating through specifications provided by the suppliers of the materials, or from pilot drying trials, or by experience with same or similar materials in prior production processing. In embodiments disclosed herein, if the air temperature set point is selected at a temperature just below the maximum web temperature to be tolerated in the hottest (driest) areas of the web, the infrared heating in these areas will be countered by convective cooling, thus mitigating excessive temperature in said driest areas. Air temperature set points from 5.56 to 27.78 degrees Celsius below the maximum web temperature to be tolerated were found to be effective in avoiding overheating of the web. Alternatively, the air temperature may be selected and regulated to be typically in the range of 16.67 to 55.56 degrees Celsius above the wet bulb temperature in the dryer (wet bulb typically < 82.22 0 C) the convective flux potential is diminished and even reversed, thus slowing the rate of heating of the web in the driest areas once the web temperature in those areas exceeds the air temperature. 28 In order to limit the overheating of the driest areas as described, the convection coefficient provided by the infrared air bars must be suitably high, exceeding that of conventional cooling air systems employed in non-flotation infrared dryers. Suitable air bar heat convection heat transfer coefficients are in the range of about 56.7 to about 227.1 W/(m^2*K). Suitable air bar slot jet velocities are in the range of from about 1524 to about 4876.8 metres per minute. The air temperature supplied to the nozzles may be regulated by adding a controlled input of heat from an independent heat source such as an electric resistance coil, hot oil or steam coil, or a burner located in the ducting supplying the air to bars. In preferred embodiments, the need for an independent source of heat is obviated by recovering the heat from the emitters that is not absorbed by the radiation mode into the web into the re-circulated air. This includes the heat taken up in the emitter cooling air as previously described, and similarly the heat recovered from stray infrared energy (electromagnetic waves that reflect or otherwise impinge on surfaces other than the web) that tends to elevate the 29 temperature of other surfaces inside the dryer over which the re-circulation air flows, and heat from those areas of the web that have been heated above the supply air temperature by the radiation mode as described earlier. This heat recovered in the re-circulation air may be retained by minimizing the amount of air exhausted to about 10% or less of the air bar supply air thus maximizing the re-circulating air temperature. On the other hand, if it is desired to lower the air temperature, the amount of exhaust may be increased to about 30% or more thus drawing in more ambient air that must be heated in the re-circulating flow. Those skilled in the art of dryers will be familiar with regulation of exhaust flow by means of a damper, or fan with a variable speed drive, in order to accomplish the air flow regulation described. This regulation may be done manually by an operator or by a closed loop controller sensing air temperature and modulating the exhaust flow accordingly. In another preferred embodiment, the air temperature may be regulated by modulating the input power to at least one infrared emitter through a closed-loop controller. In the most preferred embodiment, the primary regulation of the air temperature is made by setting the dryer exhaust to achieve a desired temperature as previously mentioned, and further controlled by regulating the power to at least one emitter with a closed-loop controller which regulates the set point for the power output of an SCR supplying power to the at least one emitter. In one application example, a printed paper web with a water-based ink, is to be dried. The expected wet bulb temperature is 57.22*C and the convection air temperature is set to 76.66*C. The net radiative heat flux from the emitters to the unprinted web is 20504 W/mA2 and the 30 convection coefficient per side is 142 W/ (m^2*K) . Thus the initial combined convection and radiation heating rate is 36278 W/mA2 and the terminal temperature of the web, where radiation flux is offset by convection cooling in the unprinted areas of the web, will be -148.89 0 C. Without the contributing effects of the flotation air bar convection air, the initial heating rate is only 20504 W/m^2 resulting in slower heating, and the calculated terminal temperature is over 426.67 0 C, well above the ignition point of paper. In the preferred dryer embodiment, the infrared air bars are placed 20.32 to 50.80 centimetres apart on each side of the web, with nozzle air jet velocities in the range of 1524 to 4876.8 mpm, with the total emitter heat flux per emitter element mounted in each air bar in the range of 15.5 to 31 watts per centimetre for medium wave carbon emitters, and 31 to 62 watts per centimetre for near IR emitters. Air temperature set points in the range of 65.55'C to 121.114C 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 features, integers, steps or components, or group thereto. 31

Claims (7)

1. A method of drying a web of printed material having at least one region of wet ink coverage and at least one region without wet ink coverage, said method comprising applying both convective flux and infrared heat flux simultaneously to said web and in the same region of said web such that said at least one region having wet ink coverage is heated by an infrared emitter source and by convection air while simultaneously said at least one region without wet ink coverage is irradiated by said infrared emitter source while simultaneously being cooled by said convection air.

2. The method of claim 1, wherein said convective flux is created by a plurality of air jets impinging on said web.

3. The method of claim 2, wherein said infrared flux is emitted from at least one infrared source located between discharge slots creating said air jets and directing said air jets to impinge on said web creating a pressure field on the surface of said web, said infrared flux impinging simultaneously on said pressure field.

4. The method of claim 3, wherein said air jets discharge air at a velocity of from 5000 to 16000 feet per minute.

5. The method of claim 3, wherein the heat flux from each infrared light source is in the range of 100 to 200 watts per inch across the web direction.

6. The method of claim 3, wherein said air jets are regulated to a temperature 5.56 to 27.78 0 C below the maximum thermal rating temperature of the web material. 32

7. The method of claim 3, wherein said air jets are regulated to a temperature 16.67 to 55.56 0 C above the wet bulb temperature of the drying air impinging on said web. 33