CA1174530A - Method and system for producing a liquid spray curtain - Google Patents
Method and system for producing a liquid spray curtainInfo
- Publication number
- CA1174530A CA1174530A CA000377396A CA377396A CA1174530A CA 1174530 A CA1174530 A CA 1174530A CA 000377396 A CA000377396 A CA 000377396A CA 377396 A CA377396 A CA 377396A CA 1174530 A CA1174530 A CA 1174530A
- Authority
- CA
- Canada
- Prior art keywords
- liquid
- air
- curtain
- streams
- continuous
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/02—Spray pistols; Apparatus for discharge
- B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
- B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/02—Spray pistols; Apparatus for discharge
- B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
- B05B7/0884—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point the outlet orifices for jets constituted by a liquid or a mixture containing a liquid being aligned
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G7/00—Damping devices
Abstract
METHOD AND SYSTEM FOR PRODUCING
A LIQUID SPRAY CURTAIN
ABSTRACT
A method and a system are provided for producing a continuous liquid spray curtain which, when sprayed onto a moving surface, covers essentially the entirety of that sur-face without substantial streaking thereof. The subject spray curtain is produced by discharging a continuous air curtain at a relatively high velocity of at least 600 feet per second. A plurality of liquid streams are at the same time discharged from a liquid discharge means at a relatively low velocity of not more than about 20 feet per second. The air curtain contacts the liquid streams at a minimum contact angle of between about -10° and about +30°, measured from the center line of the liquid discharge means. The contact-ing air curtain atomizes the liquid streams and forms the subject high velocity, uniform, liquid spray curtain.
A LIQUID SPRAY CURTAIN
ABSTRACT
A method and a system are provided for producing a continuous liquid spray curtain which, when sprayed onto a moving surface, covers essentially the entirety of that sur-face without substantial streaking thereof. The subject spray curtain is produced by discharging a continuous air curtain at a relatively high velocity of at least 600 feet per second. A plurality of liquid streams are at the same time discharged from a liquid discharge means at a relatively low velocity of not more than about 20 feet per second. The air curtain contacts the liquid streams at a minimum contact angle of between about -10° and about +30°, measured from the center line of the liquid discharge means. The contact-ing air curtain atomizes the liquid streams and forms the subject high velocity, uniform, liquid spray curtain.
Description
1 ~74530 BACKGROUND OF THE IN~ENTION
This inYention relates to a method for producin~ a continuous liquid spray curtain capable of uniformly covering essentially the entirety of a moving sur~ace, without substan-tial streakin~ thereof, Prior art systems have been provided for spraying a liquld onto a moving surface For example ! a plurality of hydraulic nozzles can be employed for liquid spraying, the number of nozzles employed being determined by the width of the surface to be sprayed. However, hydraulic nozzles emit a spray in a circular or elliptical pattern. This causes non-uniform coverage of the moving surface because the respective sprays emanating from adjacent hydraulic nozzles are difficult to interface one with the othèr over the entire width of the moving surface. Thus, streaking results due to these respect-ive oversprayed or undersprayed areas, Streaking is a parti-cular pro~lem in certain applications, such as ! for example, spraying a creping adhesive onto a cellulosic web, or onto a thermal drying cylinder, since nonuniform adhesion of the web to the thermal drying cylinder results in a nonuniformly creped sheet having substandard physical properties. Fur-thermore, the dried, creped web will not wind evenly into a parent roll on the papermaking reel if creping is nomln:iform.
~hîs will lead to substantial problems when the parent roll is converted to product.
~ nother serious problem associated with certain nozzles, such as hydraulic noz21es~ is plugging of the nozzle tips. Plugging terminates liquid flow causiny widespread streaking to occur due to the aforementioned nonuniform spray application. Hydraulic no2zles operate at a relatively high ~ ~7~530 solution flow rate, Therefore, If an adhesive is the li~uid material sprayed, a total solids level must be selected at a given liquid flow rate which will not provide too large an amount of adhesive to be sprayed onto the moving surface.
This will cause a boardy sheet to be formed. Thus~ a lower, overall total solids liquid must be employed at a higher total solution ~low rate in order to supply the prescribed amount of solids add-on to the surface to be sprayed. This results in the use of much higher water consumption level~ as well as a substan-tial increase in the thermal energy required for drying purposes, The exit velocity of the liquid in a hydraulic nozzle system determines the requisite degree of atomization of the liquid, In the case of a hydraulic no~zle, the liquid e-xit velocity is relatively high, The exit velocity is pri-marily a function of the liquid supply pressure, A high liquid supply pressure presénts severe operating ha~ards to e~uipment and personnel, Another approach in spraying a li~uid onto a moYing surface is the use of sonic noz~les. These nozzles typically spray particles of a smaller, more uniform size particle dis-tribution than those produced by hydraulic sprayin~ A dis-cussion of this t~pe of spraying appears in Canadian applica-tion No,29~152~ which is assigned to the assi~nee herein, One of the m~jor problems ~hich c~n result from th~ u~e oE ~
plurality of sonic no2zles ~or spraying onto a movin~ su~ce is that the finer the spray ~hich is producedr the lower the momentum of the spray particles~ ThiS~ in turn~ reduces the effect of penetration by the spray particles o~ the boundar~
air layer between the nozzle and the moving surface~ xesulting in a significantly higher level of spray migration and a ~ 17fls530 lower solids addition to the moving surfacer ~urthermore!
the same coverage problems associated with hydraulic nozzles are present herein because of the circular spray p~tterns produced by each adjacent sonic nozzle. Finally, the sonic nozzles exhibit plugging problems similar to those described above for hydraulic nozzles, Other prior art systems have attempted to provide a plurality of sprays from a common source. U. S. Patent 1,888,791 to Cole, for example, describes an apparatus which discharges liquids through jets 1-3. The discharge liquid intersects air streams 4-6 outside the discharge ori-fices at a substantially maximum angle with respect to the : central axis of the liquid jets so that the air streams impede the progress of the liquid jet flow and creates a back-pressure, Any change in the air velocity or impinge-ment angle will change the back pressure, For example, any increase in the back-pressure, such as caused by an increase in the ai~ velocity, will result in a decrease in both the li~Uid velocity and in the-amount of li~uid sprayed, Thus, since the velocit~v and amount of liquid sprayed, respect-ivel~, ~rill be changed b~v chan~es in the back-pressure, spray uni~ormit~ in both the lateral (coverage) and longi-~udin~l ~.uni~orm rate~ directions will be dlff.icult to main-tain, ThereEore/ higher relative li~uid pressures and velo-cities then desired must be maintained with respect to the Cole apparatus in order ~or the system to ~unction since small variations in either the air or li~uid discharge velo-city will result in substantial changes in the lateral and longitudinal spray~ pattern, This results in the aforemen-tioned streakin~, uniformity~ and coverage problems. Fin-allyr the a~r stream in Cole emanates from individual sets ~ 17~530 of jets 4-6 Therefore, the air stream is discontinuous over the entire longitudinal extent of the apparatus A dis-continuous air stream will create a discontinuous spray flow pattern, resulting in streaking and nonuniform coverage of the surface being sprayed.
With respect to certain moving surfaces, such as cellulosic webs, and the like, a nonuniform moisture pro~ile typically exists in which the edges of the webs are much drier than the central portion. Coverage of these webs with moisturizing liquids to a desired moisture leyel can be accomplished by the addition of water to increase the mois-ture level at the edges of the web. Some prior art systems, such as sonic no~zles attempt to correct this problem by changing the flow rates of a plurality of individual sonic no2zles in a given system so as to alter the moisture profile of the web~ Instead, the system provides a random, nonuni-formr uncoordinated spray pattern t SUMMARY OF THE INVENTION
The above described problems associated with prior art systems have been overcome by the method of the present i~lYention The subject method provides an essentially con-tinuous liquid spray curtain capable of uniformly covering essentiall~ the entirety o~ a movin~ web without substantial streakin~ thereo~, The liquid spray curtain is produced by dischar~in~ a plurality o~ streams o~ liquid to be sprayed ~rom a dischar~e means at a relatively low discharge velocity.
At the same time, a continuous~ high velocity air curtain is also discharged which is directed toward the liquid streams and contacts same at a minimum contact an~le ~, measured from the centex line of said liquid discharge means, of from about -10~ and preferably from about -5~ up to about ~30~f and ~. ~ 7~53~
more preferably up to about +10. When the high velocity air curtain contacts the low velocity liquid at the above pre-scrihed minimum contact angle, the liquid veloci,ty is substan-tially increased and the liquid is atomized, thereby forming a high velocity, continuous, uniform liquid spray curtain. The high velocity liquid spray curtain exhibits a relati~ely high boundary layer penetration level in a controled, extensive particle range, Accordingly, essentially the entire moving surface is covered with the liquid spray in a uniform manner, and without substantial interfacing or streaking problems, as ; previously described r : Spraying of a-relatively high total solids liquid ,can be accomplished when the process of this invention is : employed without the problems associated with the prior art.
Thus, the total liquid fl:ow rate can be decreased at a given total solids level, This will, in turn, decrease the total water consumption and-the thermal drying costs associated with the prior art solution levels t The total amount of liquid sprayed on the mo~ing surface'in the method o the present invention is preferably onl~ u~ to about 50%, and more preferably up to about 25%~
as compared to h~draulic no2zles at khe same total solids level, The use of a higher total solids li~uid results~
to a great degree, from the subject liquid discharge means having a substantially higher total cross-sectional flo~
a~ea per ~oot ~Ax) than that of a comparable hydraulic dis-charye meanS (Ah), The ratio of AX:Ah at a giYen total solids flow rate is generall~ at least about 30, and prefer-abl~ at least about 60, and more preferably at least about120, The liquid discharge velocity ~or the method of the present invention is relatively low and preferably is not greater than about 20 feet per second ! and more preferably not greater than about 5 feet per second, and most preferably not more than about 2 feet per secon~. This is in total con-tradistinction to the aforementioned prior art methods which employ substantially high liquid flow velocities to overcome an impeding air flow, as in the case of the Cole patent, and, in the case o~ the hydraulic and sonic no2~1es, for overcom-ing the air boundary layer between the system and the surface.
~ t is not only important for the liquid flow rateto be lowr it is also important for the discharge velocity of the air curtain to be substantially higher than that of the discharge-~elocity of the li~uid The discharge ~elocity o~ the air curtain is preferably at least about 600 ~eet per second~ and more preferably at least about 1,000 feet per second~ ~nd most preferably at least about 1,200 feet per second. Furthermore, the respective liquid and air veloci-ties are maintained so that substantial atomization of the liquid will result.
Moving surfaces of differing widths can be effect-ively sprayed by employing a method of this invention In the a~orementioned prior art systemst accurate, controled~
uni~orm coverager especially at the surface edges~ is dif~icult to maintain since the spray pattern produced by these prior systems is discontinuous The subject method, on the other hand~ pxovides ~or readily adjusting the width of the continu-ous spray curtainr depending on the width of the moving sur-~ace to be sprayed, This is done by closing off or openingr in a controled manner, only the outermost liquid sprays so that the width of the curtain will correspond to the width of ~ ~74530 the moving surface. Such an ad~ustment can be made to quite a narrow tolerance range since the liquid discharge means are in close proximity one to the other.
In order to substantially eliminate prior art prob-lems associated with variabilities in the respective flow rates as, for example, caused by disparities in the liquid or air supp~y pressure, certain modifications have been provided.
Specifically, each liquid header system includes labyrinth means ~hich internally meters and lon~itudinally distributes the liquid flow, causing a constant span-wise pressure or static head to be maintained in a liquid reservoir which extends across the entire longitudinal distance of the dis-charge means. The presence of this liquid reservoir insures that a constant, static liquid head will be maintained at the discharge means and that the liquid spray curtain will there-fore operate at steady-state conditions.
Certain moving surfaces, such as cellulosic webs on the paper machine, have a substantially nonuniform mois-ture profile, i.e., the moisture level is substantially lower at the edges than at the center, The previously described conventional systems are not capable of effectively controling the spra~ ~rom both a quality and quantit~v standpoint so that the moisture profile of the weh cannot be modified to the extent that it becomes uniform across the entire web surface.
By Var~in~ the liquid flow supply at various points in the respective individual headers, an inverted moisture profile is provided in the method of the present invention in which more moisture is sprayed at the ed~es of the moving surface than in the interior portion thereof while, at the same time, maintainin~ the same total amount of liquid spray addition.
Moi~ture profile measurement means can be provided for con-tinuously-monitoring the moisture profile of the web at a .
~ 17~5~Q
point upstream from the subject spray system, The flow rate can then be adjusted at various points in the individual liquid supply headers to compensate f~r these disparities.
DETAILED DESCRIPTION OF THE DRAWIN~S
FIGURE 1 is a sectional view of the subject liquid spray curtain system 10 supported by beam 70 and including liquid and air supply means 20 and 40, respectively.
FIGURE 2 is a detailed, enlar~ed sectional view o~
the syste~ 10 of FIGURE 1 per se.
FIGURE 3 is a detailed, sectional view taken along line 3-3 of FIGURE 2.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGURE 1! the present invention comprises a system 10 for producing a liquid spray curtain, as generally depicted therein. More specifically, the system 10, which, in FIGURE l! is attached to and supported by beam 70, includes a liquid supply means 20 and an air supply means 40~ respectively. The liquid supply means~ in general, comprises at least one liquid supply header, in this case denoted "21"
and "21"', having a plurality of liquid supply lines 23 attached~ at one end, thereto. The liquid supply lines 23 are, at the other end, connected to a liquid supply conduit 22 which ~ransports the liquid ~rom a liquid storage means (not shown~
employing a pump or other like means to provide the driving ~orae ~or transporting the liquid.
Air supply means 40 comprises an air supply header 41 to which a plurality of air supply lines 61 are connected.
; At the other end~ the air supply lines 61 are connected to air supply conduit 60 which transports air~ under pressure~ employ-ing ~ compressor or like means to provide the driving force.
3 ~
As set ~orth ~n FIGURES 2 and 3 ! liquid supply headers 21 and 211, which. discharge a plurality of liquid streams fr~m discharge means 37 at a relatively low velocity, include inlet supply means 24 and 24' which supply the appro-priate lIquid to supply chambers 25 and 25'. Preferably~
li~uid supply headers 21 and 21~ are disposed at right anyles one ~ith respect to the other. Liquid supply cha~ers 25 and 25l ha~e located there~ithin labyrinth means 26 and 26~ for internally meter~ng and.longitudinally distributiny the liquid flow, Specificallyr labyrinth means 26 and ~6' comprise, pre-fera~ly, X~rst compartments 27 and 27', in which the liquid is initi,a1ly collectedl the l~quid being restrained from flowing freely by first barrier means ~9 and 29'. Liquid supply ori-fices 30 and 30' are also provided which permit a reduced flow of liquid to the second compartments 28 and 28', where the liquid is again collected. The flow is restricted in this case by second barrier means 31 and 31'. The liquid then moVeS to a li~uid reservoir means 33 and 33' from labyrinth means 26 and 26'~ respectively~ through liquid supply slots 32and 3Z' in the respective second barrier means 31 and 31'.
Both the liquid reservoir means and the liquid supply slots, xespectively, extend along the entire longitudinal distance of the liquid supply headers 21 and 21'. When the reservo:ir is filled with li~uid, it rema.ins in liquid communication with discharge mean~ 37, having an exit orifice 37', whi.ch is adapted for liquid communication with said reservoirr to pro-vide a continuousr uniform flow rate of liquid, The liquid mo~es to dischar~e means 37 from reservoirs 33 and 33', through exit passageways 35 and 35~, Liquid flow tubes 38 and 38' ~in pha,ntom~.~ having exit orifices 39 and 39l~ are preferably disposed within discharge means 37 for further controling the ~ ~,7~3~
discharge of the liquidt The dischar~e means 37 preferabl~
has a narrowed end section 36 which provides, if necessary, means for readily maintaining liquid flow tubes 38 and 38' in prope~ position and alignment. As depicted in ~IGURES 2 and 3, liquid flow tubes 38 and 38' are preferably in individual and a.lternative communication with the liquid in a pair of liquid supply headers 21 and 211, respectively, This permits a more controled liquid flow and allows the system to continue in operation even if one.of the headers requires maintenance.
As depicted in-FIGURE 2 r air supply means 40 com-prises an air supply header 41, which discharyes a continuous, hi~h ~elocity air curtain, from exit air slit 50, for contact with said liquid streams, as hereinafter provided, The air supply header 41 in~ludes means denoted "43" and "51" for adjusting the respective ma~nitudes of the exit air slit 50 and the aiX contact angle ~, as hereinafter described. Exit ~ir slit 50 is preferably continuous along the entire longitu-dinal extent of the system 10, .
~ The air from air suppl~ line 61 enters central air supply chambe~ 49 through an inlet means 44, Air supply cham-ber 49 i~ formed within ~e confines of said air supply header 41 and c~nverges at its outermost end to form a continuous exit air slit 50, The header 41 comprlses a first sidewall member 46, a pair of endwall members 45 ~.only one shown~, and a 100x member 47~ respectively, joined one to the other, and a second si.dewall member 42 adapted for movement to a pluraliky of positions with respect to said first sidewall member 46. By properl~ positioning movable second sidewall member 42 with ~espe¢t to first sidewall member! such as position "42a" ~.in phantom).r exit slit 50 can be adjusted to said plurality of set magnitudes~
o The supply pressure of the air in conduit 60 sub-stantially controls the velocity of the air bein~ emitted from air slit 50~ Preferably, the air supply pressure in conduit 60 is maintained at from about 5 psig, up t~ about 40 psig, and more preferably from about 10 psig, up to about 25 psig, The quantity of air emitted from exit air slit 50 is controled by the maynitude of the opening of slit 50, The quantity o$ air emitted from slit 50, to a great extent, con-trols the penetration of the li~uid spray curtain with respectto the boundary air layer, The magnitude of slit 50 is chosen depending on the viscosity and quantity of the spray li~uid, the distance from the spray exit to the moving surfacer and the velocity of.the moving surface. Preferably, the magnitude of exit air slit 50 is maintained at a slit opening of from about 0.002 inch, up to about 0.010 inch, and more preferably from about 0.003 inch, up to about 0.006 inch, . The rèlative position of second sidewall member 42 with respect to first sidewall member 46, employing air slit adjustment means 43, such as nut-and-bolt arrangement 43a' passing through bracing member 43b. Bracing member 43b is connected to air supply header 41 ~y attachment means 43c~
whichr in this case, is a nut-and-bolt assembly An air flow guide means 48 .is located at the outer-most end of first sidewall member 46, Guide means 48 is dis-posed with respect to the center line 37a of liquid discharge means 37 such that when said second sidewall member 42 is pos.itioned with respect to air guide means 48, a high velocityt continuous air curtain is dischargecl from said exit slit which will contact said liquid streams at the previously described minimum contact angle. Preferablyr air flow guide means 48 is ^il 1~7~530 disposed parallel to the center line of said liquid discharge means 37. The movement of sidewall member 42 to various posi-tions with respect to guide means 48 within the limits of angle ~, as previously described herein, is preferably pro-vided employing adjustment means 51, which is preferably a screw arrangement. As shown in FIGUR~ 2, adjustinent means 51 is con-nected to bracing member 43b and air supply header 41, respect-ively. Thus, by moving adjustment means 51 to position "51"' ~n ph,a,nto~l~ side~ll 42 can also be moved io position "42"' lQ ~n.ph,a,ntoml. ~ith respect to guide means 48 ! thereby adjusting the magnitude of an~le ~.
: In order to reduce the variations in the inlet air flbw, a means "44" for creating a pressure drop and thereby reducing the pressure peaks in the inlet air flow can be pro-vided~ Means 44 is preferably in the form of screen means which modifies the inlet air so that it assumes a uniform span-wise pressure distribution and a uniform exit velocity.
In use, the liquid spray curtain 16 which is emitted is capable of uniformly covering essentially the entirety of the moving surface. The liquid spray curtain 16 is formed by discharging a plurality o~ liquid streams from discharge means 37 and~ in this case, through liquid flow tubes 38 and 38', at low discharge velocity, At the same time, continuous air cur-tain ,is discharged from air slit 50, and is directed toward the dischar~ing liquid streams emanatiny from discharge means 37.
The ~ir and liquid~ respectively, intersect at the minimum contact angle described above, When the continuous r high velocity air curtain contacts the low velocity liquid streams 15~ a hi~h velocity~ continuous, uniform liquid spray curtain 16 ~not shown) is formed, without impeding the liquid flow!
but~ contrarilyt the liquid velocity, after the liquid exits 5 3 ~
from the orifices~ is substantially increased, causing atomi-zation of the liquid Curtain 16 exhibits a high boundary layer penetration level over a controled, extensive particle size range without causing substantial streaking when sprayed onto a moving surface, and without exhibiting interfacing problems between the respective spray streams~
When, as described in the preceding discussion, an aqueous solution of a processing liquid, such as a creping adhesive, and the like, is employed/ the total amount of liquid 15 being discharged from liquid discharge means 37 can be sub-stantially lower than for the same liquid, at the same total solids le~el, employing, for example, a hydraulic nozzle system.
The use of a lower amount of liquid results to a large extent frc~ the use o~ a larger number of indi~idual discharge means 37, preferably including liquid flow tubes 38 and 38', having a relatively lar~e total cross-sectional flow area per longitu-dinal foot~ of said header means 21 and 21', i.e., Ax, and a lower solution velocity. Thus, if a 1% solution is employed, for example, the preferred Ax of the discharge orifice 37' is from about 0.01 square inch per foot to about 0.09 square inch per foot~ and more preferably from about 0~02 square inch per foot to about 0,06 square inch per foot ~t the same time~ a high veloc:ity air stream is supplied from air supply header 41. The velocity of the air exiting from the air slit 50 must be signi~icantly higher than the velocity of the liquid 15 exiting from clischarge means 37~
The ma~nltude of this difference has been previously described.
A critical ~eature of this invention is the minimum contact an~le ~ at which a continuous, high velocity air curtain is directed with respect to the liquid 15 being discharged at low velocity from discharge means 37. Instead of impeding the flow ~ 17~
of the discharging liquid, the method of the present invention provides that a continuous air curtain contacts the liquid at an angle which will impel the liquid at a high velocity and will form a continuous, uniform li~uid spray curtain having a relatively high boundary layer penetration level over a con-troled, extensive particle-size range. The minimum contact angle is preferably controled, as in FIGURE 2, by air flow guide means 48 disposed in a plane substantially parallel to the center line 37a of discharge means 37. The air flow guide means in conjunction with movable sidewall means 42a, respect-ively, cause the air to be discharged so as to produce the requisite minimum~cont~ct ~ngles Rxeviously descxibed~
A continuous, uniform, low velocity liquid stream is emitted from discharge means 37 due, to the most partr to the maintenance of a positive static pressure head on said discharge means The static head on dischar~e means 37 is, in turn, maintained by the positive static ~ressure within liquid reservoir 33 More specificall~, by emplo~ing a liquid reserYoir which extends below the entire extent of the inlet portions of discharge means 37, the reservoir 33 is substan-tiall~ f~lled with liquid under pressurer and all o~ the discharge means 37 will, in turn, be filled with liquid under pressurer which will result in the uniform~ continu~us dis-ch~rge o~ s~id liquid from said discharge means, As previ-o~sl~ described~ the positive pressure wh.ich is maintained in the liquid reservoir 33 is a direct consequence o labyrinths ~6 ~nd 26l which internally meter the liquid flow and facili-tate the li~uid communication from liquid reservoir 33 to discharge means 37 Longitudinal extent of the liquid spray curtain can be adjusted, depending on the width of the moving surface to be sprayed, by providing, such as by inserting within discharge means 37, or by substitutin~ for liquid flow tubes 38 and 38' which are hollow in construction, means for plug~ing said liquid s~reamsr at points beyond the width of the moving sur-face, so that the liquid lS cannot pass therethrough.
The moisture profile of a moving surfàce having a lower moisture content at its edges than at its central por-tion can be adjusted employing the system of this invention.
Specifically~ a means can be provided for measuring the mois-ture profile of the moving surface at a point prior to thesubject linear nozzle sy-stem By increasing the liquid flow to the outermost points in the subject system, i.e r to the outermost points in the liquid header the liquid flow rate to the innermost points in the respective headers is reduced, thereby producing a liquid spray curtain having a moisture profile in which the outer edges of the moving surface are moisturized to a much greater extent than the central portion thereof~ and a moisture profile results, The spray liquld 15 can comprise any liquid material which can be effectively discharged from discharge means 37 without causing substantial plugging thereof. The magnitude o~ the liquid materials whioh can be employed is far more sub--stantial than those liquids which can be sprayed from hydraulic and sonic systems. The method of the present invention requires only a low exit ~eloc.ity and the area o~ liquid flow is sub-stantially greater than in the previously described prior art s~stems. Typically, various aqueous liquid solutions are employed as the liquid 15 Water, itself, can also be sprayed on a moving surface in order to moisturize the same, as described above.
In a ~xe~erxed m,ethod o~ this invention~ a li~uid adhesive solution can be sprayed on a cellulosic papexmakin~
web~ and after bei~ sprayed with the subject liquid spray curtainr the web can be adhered to a thermal drying cylinder and then uniformly creped to produce a softer, bulkier cellu-losic web product. Furthermore ! this same li~uid spray curtain can also be sprayed directly onto a moving sur~ace crossing the thermal drying cylinder per se, Typical creping adhesi~es include yarious natur~l and synthetic materials which are well-knQwn in the papermaking art. Exemplary materials includeca~boxymethyl cellulose~ polyvinyl alcohol~ animal glue, and : the Iike.
;
, t
This inYention relates to a method for producin~ a continuous liquid spray curtain capable of uniformly covering essentially the entirety of a moving sur~ace, without substan-tial streakin~ thereof, Prior art systems have been provided for spraying a liquld onto a moving surface For example ! a plurality of hydraulic nozzles can be employed for liquid spraying, the number of nozzles employed being determined by the width of the surface to be sprayed. However, hydraulic nozzles emit a spray in a circular or elliptical pattern. This causes non-uniform coverage of the moving surface because the respective sprays emanating from adjacent hydraulic nozzles are difficult to interface one with the othèr over the entire width of the moving surface. Thus, streaking results due to these respect-ive oversprayed or undersprayed areas, Streaking is a parti-cular pro~lem in certain applications, such as ! for example, spraying a creping adhesive onto a cellulosic web, or onto a thermal drying cylinder, since nonuniform adhesion of the web to the thermal drying cylinder results in a nonuniformly creped sheet having substandard physical properties. Fur-thermore, the dried, creped web will not wind evenly into a parent roll on the papermaking reel if creping is nomln:iform.
~hîs will lead to substantial problems when the parent roll is converted to product.
~ nother serious problem associated with certain nozzles, such as hydraulic noz21es~ is plugging of the nozzle tips. Plugging terminates liquid flow causiny widespread streaking to occur due to the aforementioned nonuniform spray application. Hydraulic no2zles operate at a relatively high ~ ~7~530 solution flow rate, Therefore, If an adhesive is the li~uid material sprayed, a total solids level must be selected at a given liquid flow rate which will not provide too large an amount of adhesive to be sprayed onto the moving surface.
This will cause a boardy sheet to be formed. Thus~ a lower, overall total solids liquid must be employed at a higher total solution ~low rate in order to supply the prescribed amount of solids add-on to the surface to be sprayed. This results in the use of much higher water consumption level~ as well as a substan-tial increase in the thermal energy required for drying purposes, The exit velocity of the liquid in a hydraulic nozzle system determines the requisite degree of atomization of the liquid, In the case of a hydraulic no~zle, the liquid e-xit velocity is relatively high, The exit velocity is pri-marily a function of the liquid supply pressure, A high liquid supply pressure presénts severe operating ha~ards to e~uipment and personnel, Another approach in spraying a li~uid onto a moYing surface is the use of sonic noz~les. These nozzles typically spray particles of a smaller, more uniform size particle dis-tribution than those produced by hydraulic sprayin~ A dis-cussion of this t~pe of spraying appears in Canadian applica-tion No,29~152~ which is assigned to the assi~nee herein, One of the m~jor problems ~hich c~n result from th~ u~e oE ~
plurality of sonic no2zles ~or spraying onto a movin~ su~ce is that the finer the spray ~hich is producedr the lower the momentum of the spray particles~ ThiS~ in turn~ reduces the effect of penetration by the spray particles o~ the boundar~
air layer between the nozzle and the moving surface~ xesulting in a significantly higher level of spray migration and a ~ 17fls530 lower solids addition to the moving surfacer ~urthermore!
the same coverage problems associated with hydraulic nozzles are present herein because of the circular spray p~tterns produced by each adjacent sonic nozzle. Finally, the sonic nozzles exhibit plugging problems similar to those described above for hydraulic nozzles, Other prior art systems have attempted to provide a plurality of sprays from a common source. U. S. Patent 1,888,791 to Cole, for example, describes an apparatus which discharges liquids through jets 1-3. The discharge liquid intersects air streams 4-6 outside the discharge ori-fices at a substantially maximum angle with respect to the : central axis of the liquid jets so that the air streams impede the progress of the liquid jet flow and creates a back-pressure, Any change in the air velocity or impinge-ment angle will change the back pressure, For example, any increase in the back-pressure, such as caused by an increase in the ai~ velocity, will result in a decrease in both the li~Uid velocity and in the-amount of li~uid sprayed, Thus, since the velocit~v and amount of liquid sprayed, respect-ivel~, ~rill be changed b~v chan~es in the back-pressure, spray uni~ormit~ in both the lateral (coverage) and longi-~udin~l ~.uni~orm rate~ directions will be dlff.icult to main-tain, ThereEore/ higher relative li~uid pressures and velo-cities then desired must be maintained with respect to the Cole apparatus in order ~or the system to ~unction since small variations in either the air or li~uid discharge velo-city will result in substantial changes in the lateral and longitudinal spray~ pattern, This results in the aforemen-tioned streakin~, uniformity~ and coverage problems. Fin-allyr the a~r stream in Cole emanates from individual sets ~ 17~530 of jets 4-6 Therefore, the air stream is discontinuous over the entire longitudinal extent of the apparatus A dis-continuous air stream will create a discontinuous spray flow pattern, resulting in streaking and nonuniform coverage of the surface being sprayed.
With respect to certain moving surfaces, such as cellulosic webs, and the like, a nonuniform moisture pro~ile typically exists in which the edges of the webs are much drier than the central portion. Coverage of these webs with moisturizing liquids to a desired moisture leyel can be accomplished by the addition of water to increase the mois-ture level at the edges of the web. Some prior art systems, such as sonic no~zles attempt to correct this problem by changing the flow rates of a plurality of individual sonic no2zles in a given system so as to alter the moisture profile of the web~ Instead, the system provides a random, nonuni-formr uncoordinated spray pattern t SUMMARY OF THE INVENTION
The above described problems associated with prior art systems have been overcome by the method of the present i~lYention The subject method provides an essentially con-tinuous liquid spray curtain capable of uniformly covering essentiall~ the entirety o~ a movin~ web without substantial streakin~ thereo~, The liquid spray curtain is produced by dischar~in~ a plurality o~ streams o~ liquid to be sprayed ~rom a dischar~e means at a relatively low discharge velocity.
At the same time, a continuous~ high velocity air curtain is also discharged which is directed toward the liquid streams and contacts same at a minimum contact an~le ~, measured from the centex line of said liquid discharge means, of from about -10~ and preferably from about -5~ up to about ~30~f and ~. ~ 7~53~
more preferably up to about +10. When the high velocity air curtain contacts the low velocity liquid at the above pre-scrihed minimum contact angle, the liquid veloci,ty is substan-tially increased and the liquid is atomized, thereby forming a high velocity, continuous, uniform liquid spray curtain. The high velocity liquid spray curtain exhibits a relati~ely high boundary layer penetration level in a controled, extensive particle range, Accordingly, essentially the entire moving surface is covered with the liquid spray in a uniform manner, and without substantial interfacing or streaking problems, as ; previously described r : Spraying of a-relatively high total solids liquid ,can be accomplished when the process of this invention is : employed without the problems associated with the prior art.
Thus, the total liquid fl:ow rate can be decreased at a given total solids level, This will, in turn, decrease the total water consumption and-the thermal drying costs associated with the prior art solution levels t The total amount of liquid sprayed on the mo~ing surface'in the method o the present invention is preferably onl~ u~ to about 50%, and more preferably up to about 25%~
as compared to h~draulic no2zles at khe same total solids level, The use of a higher total solids li~uid results~
to a great degree, from the subject liquid discharge means having a substantially higher total cross-sectional flo~
a~ea per ~oot ~Ax) than that of a comparable hydraulic dis-charye meanS (Ah), The ratio of AX:Ah at a giYen total solids flow rate is generall~ at least about 30, and prefer-abl~ at least about 60, and more preferably at least about120, The liquid discharge velocity ~or the method of the present invention is relatively low and preferably is not greater than about 20 feet per second ! and more preferably not greater than about 5 feet per second, and most preferably not more than about 2 feet per secon~. This is in total con-tradistinction to the aforementioned prior art methods which employ substantially high liquid flow velocities to overcome an impeding air flow, as in the case of the Cole patent, and, in the case o~ the hydraulic and sonic no2~1es, for overcom-ing the air boundary layer between the system and the surface.
~ t is not only important for the liquid flow rateto be lowr it is also important for the discharge velocity of the air curtain to be substantially higher than that of the discharge-~elocity of the li~uid The discharge ~elocity o~ the air curtain is preferably at least about 600 ~eet per second~ and more preferably at least about 1,000 feet per second~ ~nd most preferably at least about 1,200 feet per second. Furthermore, the respective liquid and air veloci-ties are maintained so that substantial atomization of the liquid will result.
Moving surfaces of differing widths can be effect-ively sprayed by employing a method of this invention In the a~orementioned prior art systemst accurate, controled~
uni~orm coverager especially at the surface edges~ is dif~icult to maintain since the spray pattern produced by these prior systems is discontinuous The subject method, on the other hand~ pxovides ~or readily adjusting the width of the continu-ous spray curtainr depending on the width of the moving sur-~ace to be sprayed, This is done by closing off or openingr in a controled manner, only the outermost liquid sprays so that the width of the curtain will correspond to the width of ~ ~74530 the moving surface. Such an ad~ustment can be made to quite a narrow tolerance range since the liquid discharge means are in close proximity one to the other.
In order to substantially eliminate prior art prob-lems associated with variabilities in the respective flow rates as, for example, caused by disparities in the liquid or air supp~y pressure, certain modifications have been provided.
Specifically, each liquid header system includes labyrinth means ~hich internally meters and lon~itudinally distributes the liquid flow, causing a constant span-wise pressure or static head to be maintained in a liquid reservoir which extends across the entire longitudinal distance of the dis-charge means. The presence of this liquid reservoir insures that a constant, static liquid head will be maintained at the discharge means and that the liquid spray curtain will there-fore operate at steady-state conditions.
Certain moving surfaces, such as cellulosic webs on the paper machine, have a substantially nonuniform mois-ture profile, i.e., the moisture level is substantially lower at the edges than at the center, The previously described conventional systems are not capable of effectively controling the spra~ ~rom both a quality and quantit~v standpoint so that the moisture profile of the weh cannot be modified to the extent that it becomes uniform across the entire web surface.
By Var~in~ the liquid flow supply at various points in the respective individual headers, an inverted moisture profile is provided in the method of the present invention in which more moisture is sprayed at the ed~es of the moving surface than in the interior portion thereof while, at the same time, maintainin~ the same total amount of liquid spray addition.
Moi~ture profile measurement means can be provided for con-tinuously-monitoring the moisture profile of the web at a .
~ 17~5~Q
point upstream from the subject spray system, The flow rate can then be adjusted at various points in the individual liquid supply headers to compensate f~r these disparities.
DETAILED DESCRIPTION OF THE DRAWIN~S
FIGURE 1 is a sectional view of the subject liquid spray curtain system 10 supported by beam 70 and including liquid and air supply means 20 and 40, respectively.
FIGURE 2 is a detailed, enlar~ed sectional view o~
the syste~ 10 of FIGURE 1 per se.
FIGURE 3 is a detailed, sectional view taken along line 3-3 of FIGURE 2.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGURE 1! the present invention comprises a system 10 for producing a liquid spray curtain, as generally depicted therein. More specifically, the system 10, which, in FIGURE l! is attached to and supported by beam 70, includes a liquid supply means 20 and an air supply means 40~ respectively. The liquid supply means~ in general, comprises at least one liquid supply header, in this case denoted "21"
and "21"', having a plurality of liquid supply lines 23 attached~ at one end, thereto. The liquid supply lines 23 are, at the other end, connected to a liquid supply conduit 22 which ~ransports the liquid ~rom a liquid storage means (not shown~
employing a pump or other like means to provide the driving ~orae ~or transporting the liquid.
Air supply means 40 comprises an air supply header 41 to which a plurality of air supply lines 61 are connected.
; At the other end~ the air supply lines 61 are connected to air supply conduit 60 which transports air~ under pressure~ employ-ing ~ compressor or like means to provide the driving force.
3 ~
As set ~orth ~n FIGURES 2 and 3 ! liquid supply headers 21 and 211, which. discharge a plurality of liquid streams fr~m discharge means 37 at a relatively low velocity, include inlet supply means 24 and 24' which supply the appro-priate lIquid to supply chambers 25 and 25'. Preferably~
li~uid supply headers 21 and 21~ are disposed at right anyles one ~ith respect to the other. Liquid supply cha~ers 25 and 25l ha~e located there~ithin labyrinth means 26 and 26~ for internally meter~ng and.longitudinally distributiny the liquid flow, Specificallyr labyrinth means 26 and ~6' comprise, pre-fera~ly, X~rst compartments 27 and 27', in which the liquid is initi,a1ly collectedl the l~quid being restrained from flowing freely by first barrier means ~9 and 29'. Liquid supply ori-fices 30 and 30' are also provided which permit a reduced flow of liquid to the second compartments 28 and 28', where the liquid is again collected. The flow is restricted in this case by second barrier means 31 and 31'. The liquid then moVeS to a li~uid reservoir means 33 and 33' from labyrinth means 26 and 26'~ respectively~ through liquid supply slots 32and 3Z' in the respective second barrier means 31 and 31'.
Both the liquid reservoir means and the liquid supply slots, xespectively, extend along the entire longitudinal distance of the liquid supply headers 21 and 21'. When the reservo:ir is filled with li~uid, it rema.ins in liquid communication with discharge mean~ 37, having an exit orifice 37', whi.ch is adapted for liquid communication with said reservoirr to pro-vide a continuousr uniform flow rate of liquid, The liquid mo~es to dischar~e means 37 from reservoirs 33 and 33', through exit passageways 35 and 35~, Liquid flow tubes 38 and 38' ~in pha,ntom~.~ having exit orifices 39 and 39l~ are preferably disposed within discharge means 37 for further controling the ~ ~,7~3~
discharge of the liquidt The dischar~e means 37 preferabl~
has a narrowed end section 36 which provides, if necessary, means for readily maintaining liquid flow tubes 38 and 38' in prope~ position and alignment. As depicted in ~IGURES 2 and 3, liquid flow tubes 38 and 38' are preferably in individual and a.lternative communication with the liquid in a pair of liquid supply headers 21 and 211, respectively, This permits a more controled liquid flow and allows the system to continue in operation even if one.of the headers requires maintenance.
As depicted in-FIGURE 2 r air supply means 40 com-prises an air supply header 41, which discharyes a continuous, hi~h ~elocity air curtain, from exit air slit 50, for contact with said liquid streams, as hereinafter provided, The air supply header 41 in~ludes means denoted "43" and "51" for adjusting the respective ma~nitudes of the exit air slit 50 and the aiX contact angle ~, as hereinafter described. Exit ~ir slit 50 is preferably continuous along the entire longitu-dinal extent of the system 10, .
~ The air from air suppl~ line 61 enters central air supply chambe~ 49 through an inlet means 44, Air supply cham-ber 49 i~ formed within ~e confines of said air supply header 41 and c~nverges at its outermost end to form a continuous exit air slit 50, The header 41 comprlses a first sidewall member 46, a pair of endwall members 45 ~.only one shown~, and a 100x member 47~ respectively, joined one to the other, and a second si.dewall member 42 adapted for movement to a pluraliky of positions with respect to said first sidewall member 46. By properl~ positioning movable second sidewall member 42 with ~espe¢t to first sidewall member! such as position "42a" ~.in phantom).r exit slit 50 can be adjusted to said plurality of set magnitudes~
o The supply pressure of the air in conduit 60 sub-stantially controls the velocity of the air bein~ emitted from air slit 50~ Preferably, the air supply pressure in conduit 60 is maintained at from about 5 psig, up t~ about 40 psig, and more preferably from about 10 psig, up to about 25 psig, The quantity of air emitted from exit air slit 50 is controled by the maynitude of the opening of slit 50, The quantity o$ air emitted from slit 50, to a great extent, con-trols the penetration of the li~uid spray curtain with respectto the boundary air layer, The magnitude of slit 50 is chosen depending on the viscosity and quantity of the spray li~uid, the distance from the spray exit to the moving surfacer and the velocity of.the moving surface. Preferably, the magnitude of exit air slit 50 is maintained at a slit opening of from about 0.002 inch, up to about 0.010 inch, and more preferably from about 0.003 inch, up to about 0.006 inch, . The rèlative position of second sidewall member 42 with respect to first sidewall member 46, employing air slit adjustment means 43, such as nut-and-bolt arrangement 43a' passing through bracing member 43b. Bracing member 43b is connected to air supply header 41 ~y attachment means 43c~
whichr in this case, is a nut-and-bolt assembly An air flow guide means 48 .is located at the outer-most end of first sidewall member 46, Guide means 48 is dis-posed with respect to the center line 37a of liquid discharge means 37 such that when said second sidewall member 42 is pos.itioned with respect to air guide means 48, a high velocityt continuous air curtain is dischargecl from said exit slit which will contact said liquid streams at the previously described minimum contact angle. Preferablyr air flow guide means 48 is ^il 1~7~530 disposed parallel to the center line of said liquid discharge means 37. The movement of sidewall member 42 to various posi-tions with respect to guide means 48 within the limits of angle ~, as previously described herein, is preferably pro-vided employing adjustment means 51, which is preferably a screw arrangement. As shown in FIGUR~ 2, adjustinent means 51 is con-nected to bracing member 43b and air supply header 41, respect-ively. Thus, by moving adjustment means 51 to position "51"' ~n ph,a,nto~l~ side~ll 42 can also be moved io position "42"' lQ ~n.ph,a,ntoml. ~ith respect to guide means 48 ! thereby adjusting the magnitude of an~le ~.
: In order to reduce the variations in the inlet air flbw, a means "44" for creating a pressure drop and thereby reducing the pressure peaks in the inlet air flow can be pro-vided~ Means 44 is preferably in the form of screen means which modifies the inlet air so that it assumes a uniform span-wise pressure distribution and a uniform exit velocity.
In use, the liquid spray curtain 16 which is emitted is capable of uniformly covering essentially the entirety of the moving surface. The liquid spray curtain 16 is formed by discharging a plurality o~ liquid streams from discharge means 37 and~ in this case, through liquid flow tubes 38 and 38', at low discharge velocity, At the same time, continuous air cur-tain ,is discharged from air slit 50, and is directed toward the dischar~ing liquid streams emanatiny from discharge means 37.
The ~ir and liquid~ respectively, intersect at the minimum contact angle described above, When the continuous r high velocity air curtain contacts the low velocity liquid streams 15~ a hi~h velocity~ continuous, uniform liquid spray curtain 16 ~not shown) is formed, without impeding the liquid flow!
but~ contrarilyt the liquid velocity, after the liquid exits 5 3 ~
from the orifices~ is substantially increased, causing atomi-zation of the liquid Curtain 16 exhibits a high boundary layer penetration level over a controled, extensive particle size range without causing substantial streaking when sprayed onto a moving surface, and without exhibiting interfacing problems between the respective spray streams~
When, as described in the preceding discussion, an aqueous solution of a processing liquid, such as a creping adhesive, and the like, is employed/ the total amount of liquid 15 being discharged from liquid discharge means 37 can be sub-stantially lower than for the same liquid, at the same total solids le~el, employing, for example, a hydraulic nozzle system.
The use of a lower amount of liquid results to a large extent frc~ the use o~ a larger number of indi~idual discharge means 37, preferably including liquid flow tubes 38 and 38', having a relatively lar~e total cross-sectional flow area per longitu-dinal foot~ of said header means 21 and 21', i.e., Ax, and a lower solution velocity. Thus, if a 1% solution is employed, for example, the preferred Ax of the discharge orifice 37' is from about 0.01 square inch per foot to about 0.09 square inch per foot~ and more preferably from about 0~02 square inch per foot to about 0,06 square inch per foot ~t the same time~ a high veloc:ity air stream is supplied from air supply header 41. The velocity of the air exiting from the air slit 50 must be signi~icantly higher than the velocity of the liquid 15 exiting from clischarge means 37~
The ma~nltude of this difference has been previously described.
A critical ~eature of this invention is the minimum contact an~le ~ at which a continuous, high velocity air curtain is directed with respect to the liquid 15 being discharged at low velocity from discharge means 37. Instead of impeding the flow ~ 17~
of the discharging liquid, the method of the present invention provides that a continuous air curtain contacts the liquid at an angle which will impel the liquid at a high velocity and will form a continuous, uniform li~uid spray curtain having a relatively high boundary layer penetration level over a con-troled, extensive particle-size range. The minimum contact angle is preferably controled, as in FIGURE 2, by air flow guide means 48 disposed in a plane substantially parallel to the center line 37a of discharge means 37. The air flow guide means in conjunction with movable sidewall means 42a, respect-ively, cause the air to be discharged so as to produce the requisite minimum~cont~ct ~ngles Rxeviously descxibed~
A continuous, uniform, low velocity liquid stream is emitted from discharge means 37 due, to the most partr to the maintenance of a positive static pressure head on said discharge means The static head on dischar~e means 37 is, in turn, maintained by the positive static ~ressure within liquid reservoir 33 More specificall~, by emplo~ing a liquid reserYoir which extends below the entire extent of the inlet portions of discharge means 37, the reservoir 33 is substan-tiall~ f~lled with liquid under pressurer and all o~ the discharge means 37 will, in turn, be filled with liquid under pressurer which will result in the uniform~ continu~us dis-ch~rge o~ s~id liquid from said discharge means, As previ-o~sl~ described~ the positive pressure wh.ich is maintained in the liquid reservoir 33 is a direct consequence o labyrinths ~6 ~nd 26l which internally meter the liquid flow and facili-tate the li~uid communication from liquid reservoir 33 to discharge means 37 Longitudinal extent of the liquid spray curtain can be adjusted, depending on the width of the moving surface to be sprayed, by providing, such as by inserting within discharge means 37, or by substitutin~ for liquid flow tubes 38 and 38' which are hollow in construction, means for plug~ing said liquid s~reamsr at points beyond the width of the moving sur-face, so that the liquid lS cannot pass therethrough.
The moisture profile of a moving surfàce having a lower moisture content at its edges than at its central por-tion can be adjusted employing the system of this invention.
Specifically~ a means can be provided for measuring the mois-ture profile of the moving surface at a point prior to thesubject linear nozzle sy-stem By increasing the liquid flow to the outermost points in the subject system, i.e r to the outermost points in the liquid header the liquid flow rate to the innermost points in the respective headers is reduced, thereby producing a liquid spray curtain having a moisture profile in which the outer edges of the moving surface are moisturized to a much greater extent than the central portion thereof~ and a moisture profile results, The spray liquld 15 can comprise any liquid material which can be effectively discharged from discharge means 37 without causing substantial plugging thereof. The magnitude o~ the liquid materials whioh can be employed is far more sub--stantial than those liquids which can be sprayed from hydraulic and sonic systems. The method of the present invention requires only a low exit ~eloc.ity and the area o~ liquid flow is sub-stantially greater than in the previously described prior art s~stems. Typically, various aqueous liquid solutions are employed as the liquid 15 Water, itself, can also be sprayed on a moving surface in order to moisturize the same, as described above.
In a ~xe~erxed m,ethod o~ this invention~ a li~uid adhesive solution can be sprayed on a cellulosic papexmakin~
web~ and after bei~ sprayed with the subject liquid spray curtainr the web can be adhered to a thermal drying cylinder and then uniformly creped to produce a softer, bulkier cellu-losic web product. Furthermore ! this same li~uid spray curtain can also be sprayed directly onto a moving sur~ace crossing the thermal drying cylinder per se, Typical creping adhesi~es include yarious natur~l and synthetic materials which are well-knQwn in the papermaking art. Exemplary materials includeca~boxymethyl cellulose~ polyvinyl alcohol~ animal glue, and : the Iike.
;
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Claims (39)
1. A method for producing a liquid spray curtain, which comprises a) discharging a plurality of streams of said liquid from a discharge means at a relatively low discharge velocity of not greater than about 20 feet per second; and b) discharging a continuous air curtain, at a relatively high velocity of at least about 600 feet per second, which contacts said liquid streams, at a minimum air contact angle, of between about -10°
and about +30°, measured from the center line of said liquid discharge means, which substantially increases the liquid velocity and atomizes the liquid, thereby producing a uniform liquid spray curtain hav-ing a relatively high boundary layer penetration level capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof,
and about +30°, measured from the center line of said liquid discharge means, which substantially increases the liquid velocity and atomizes the liquid, thereby producing a uniform liquid spray curtain hav-ing a relatively high boundary layer penetration level capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof,
2. The method of claim 1, wherein the minimum contact angle is between about -5° and about +10°,
3. The method of claim 1, wherein the liquid discharge velocity is not greater than about 5 feet per second, and the discharge velocity of the air curtain is at least about 1,000 feet per second.
4. The method of claim 1, wherein the ratio of the total cross-sectional flow area per foot (Ax) of the liquid discharge means to the cross-sectional flow rate per foot (Ah) of a comparable hydraulic discharge stream, at the same total solids flow, is at least about 30.
5. The method of claim 4, wherein the Ax:Ah ratio is at least about 60.
6. The method of claim 1, wherein the discharge velocity of the air curtain is at least about 1,200 feet per second.
7. The method of claim 1, wherein a liquid spray curtain is provided, capable of moisturizing the outer edges of a mov-ing surface to a much greater extent than the central portion of said moving surface.
8 A method for spraying a moving surface which com-prises a) discharging a plurality of streams of liquid at a relatively low discharge velocity of not greater than 20 feet per second;
b) discharging a continuous air curtain which contacts the liquid streams, at a minimum contact angle of between about -10° and about +30°, to pro-duce a uniform liquid spray curtain having a rela-tively high boundary level penetration level, a discharge velocity of said air curtain of at least about 600 feet per second;
c) spraying onto a moving surface said liquid spray curtain so that essentially the entire web of said moving surface is uniformly covered by said liquid without substantial streaking thereof,
b) discharging a continuous air curtain which contacts the liquid streams, at a minimum contact angle of between about -10° and about +30°, to pro-duce a uniform liquid spray curtain having a rela-tively high boundary level penetration level, a discharge velocity of said air curtain of at least about 600 feet per second;
c) spraying onto a moving surface said liquid spray curtain so that essentially the entire web of said moving surface is uniformly covered by said liquid without substantial streaking thereof,
9. The method of claim 8, wherein the liquid discharge velocity is not greater than about 5 feet per second, and the discharge velocity of the air curtain is at least about 1,000 feet per second.
10. The method of claim 8, wherein the liquid is a creping adhesive and the moving surface is a cellulosic web,
11. The method of claim 8, wherein the liquid is a creping adhesive and the moving surface is a thermal drying cylinder.
12. A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) a liquid supply means comprising at least one liquid supply header for discharging a plurality of liquid streams at low velocity, said liquid supply header comprising (i) a liquid supply chamber, (ii) labyrinth means located within said liquid supply chamber for internally metering and longitudinally distributing the liquid flow, (iii) liquid reservoir means extend-ing across essentially the entire longi-tudinal distance of said header, and (iv) means for discharging said liquid streams at a continuous, uniform flow rate which are adapted for liquid communication with the liquid reservoir means so that when said reservoir means is filled with liquid, said continuous, uniform flow rate is maintained by a constant, static pressure head in said reservoir means; and b) air supply means comprising an air supply header which includes means for discharging a con-tinuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising a first sidewall member, a pair of end wall members, and a floor member, respectively, joined one to the other, and a second sidewall member adapted for movement-to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which con-verges at its outermost end to form a continuous exit air slit through which said air curtain exits, said first sidewall member having an air flow guide means located at its outermost end which is disposed with respect to the center line of said liquid discharge means such that when said second sidewall member is positioned with respect to said air guide means, a high velocity, continuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from said center liner of between about -10° and +30°,
13. The system of claim 12, wherein said air flow guide means is disposed parallel to the center line of said liquid discharge means,
14. The system of claim 12, wherein the cross-sectional flow area of said discharge means per longitudinal foot of said liquid supply header is from about 0.01 to about 0.09 square inch per longitudinal foot.
15. The system of claim 12, wherein said discharge means has disposed therewithin liquid flow tubes for further controling the discharge of liquid.
16. The system of claim 15, wherein a pair of liquid supply headers is provided, and said liquid flow tubes are in individual and alternative communication with the liquid in the liquid supply headers so that the system will continue to operate even if one of said headers requires maintenance,
17, The system of claim 12, wherein said headers are disposed at right angles one with respect to the other,
18. The system of claim 12, wherein the longitudinal extent of the liquid spray curtain is adjusted, depending on the width of the moving surface to be sprayed, by providing means for plugging said liquid streams, so that the liquid cannot pass therethrough, at points beyond the width of said moving surface.
19. The system of claim 12, wherein a liquid spray curtain is provided, capable of moisturizing the outer edges of the moving surface to a much higher extent than the central portion thereof by maintaining the liquid flow rate to the outermost points of said liquid header at a higher rate than the rate to the innermost points of said liquid header,
20. A system for producing a liquid spray curtain cap-able of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, compris-ing a) a liquid supply means comprising at least one liquid supply header for discharging a plurality of liquid streams at low velocity;
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising first and second sidewall members, respectively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits;
c) air-flow guide means located at the outermost end of said first sidewall member;
d) air flow adjustment means for adjusting the quantity of air being admitted from said air slit; and e) means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, con-tinuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of between about -10° and +30°,
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising first and second sidewall members, respectively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits;
c) air-flow guide means located at the outermost end of said first sidewall member;
d) air flow adjustment means for adjusting the quantity of air being admitted from said air slit; and e) means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, con-tinuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of between about -10° and +30°,
21, The system of claim 20, wherein said air flow guide means is disposed parallel to the center line of said liquid discharge means.
22, The system of claim 20, wherein said discharge means has disposed therewithin liquid flow tubes further controling the discharge of liquid,
23. The system of claim 22, wherein a pair of liquid supply headers is provided, and said liquid flow tubes are in individual and alternative communication with the liquid in the liquid supply headers so that the system will con-tinue to operate even if one of said headers requires main-tenance.
24. The system of claim 20, wherein said liquid supply headers are disposed at right angles, one with respect to the other.
25. A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving sur-face to be sprayed, without substantial streaking thereof, comprising a) liquid supply means for discharging a plurality of liquid streams at low velocity;
b) air supply means for discharging a continuous, high velocity air curtain for contact-ing said liquid streams to produce said liquid spray curtain, said air supply means including an exit air slit, means for adjusting the magnitude of said exit air slit, and means for adjusting the magnitude of the minimum air contact angle, the angle at which the air curtain contacts said liquid streams measured from the center line of said liquid discharge means, to between about -10° and +30°.
b) air supply means for discharging a continuous, high velocity air curtain for contact-ing said liquid streams to produce said liquid spray curtain, said air supply means including an exit air slit, means for adjusting the magnitude of said exit air slit, and means for adjusting the magnitude of the minimum air contact angle, the angle at which the air curtain contacts said liquid streams measured from the center line of said liquid discharge means, to between about -10° and +30°.
26.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) a liquid supply means comprising at least one liquid supply header for discharging a plurality of liquid streams at low velocity;
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity, air curtain for contacting said liquid streams to produce said liquid spray curtain; and c) air flow guide means, disposed parallel to the center line of said liquid discharge means, located at the outermost end of said air supply header.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) a liquid supply means comprising at least one liquid supply header for discharging a plurality of liquid streams at low velocity;
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity, air curtain for contacting said liquid streams to produce said liquid spray curtain; and c) air flow guide means, disposed parallel to the center line of said liquid discharge means, located at the outermost end of said air supply header.
27.
The system of claim 26, wherein said air supply header comprises first and second sidewall members, respect-ively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, and said air flow guide means located at the outermost end of said first sidewall member.
The system of claim 26, wherein said air supply header comprises first and second sidewall members, respect-ively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, and said air flow guide means located at the outermost end of said first sidewall member.
28.
The system of claim 26, wherein said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits, and said air supply means includes air flow adjustment means for adjusting the quantity of air being emitted from said air slit.
The system of claim 26, wherein said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits, and said air supply means includes air flow adjustment means for adjusting the quantity of air being emitted from said air slit.
29.
The system of claim 26, wherein said air supply means includes means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, continuous air curtain is discharged from said exit slit and will contact said liquid streams at a minimum contact angle measured from the center line of said liquid discharge means.
The system of claim 26, wherein said air supply means includes means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, continuous air curtain is discharged from said exit slit and will contact said liquid streams at a minimum contact angle measured from the center line of said liquid discharge means.
30.
The system of claim 29, wherein said minimum contact angle is between about -10° and +30°.
The system of claim 29, wherein said minimum contact angle is between about -10° and +30°.
31.
The system of claim 26, wherein said discharge means has disposed therewithin liquid flow tubes further controling the discharge of liquid.
The system of claim 26, wherein said discharge means has disposed therewithin liquid flow tubes further controling the discharge of liquid.
32.
The system of claim 31, wherein a pair of liquid supply headers is provided, and said liquid flow tubes are in individual or alternate communication with the liquid in the liquid supply headers so that the system will continue to operate even if one of said headers requires maintenance.
The system of claim 31, wherein a pair of liquid supply headers is provided, and said liquid flow tubes are in individual or alternate communication with the liquid in the liquid supply headers so that the system will continue to operate even if one of said headers requires maintenance.
33.
The system of claim 26, wherein said liquid supply means comprises liquid supply headers, said liquid supply headers being disposed at right angles, one with respect to the other.
The system of claim 26, wherein said liquid supply means comprises liquid supply headers, said liquid supply headers being disposed at right angles, one with respect to the other.
34.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, compris-ing a) means for discharging a plurality of liquid streams at low velocities;
b) air supply means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply means including an air flow guide means disposed parallel to the center line of said liquid discharge means, an exit air slit, means for adjusting the magnitude of said exit air slit, and means for adjusting the magnitude of the minimum air contact angle, the angle at which the air curtain contacts said liquid streams, measured from the center line of said liquid discharge means.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, compris-ing a) means for discharging a plurality of liquid streams at low velocities;
b) air supply means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply means including an air flow guide means disposed parallel to the center line of said liquid discharge means, an exit air slit, means for adjusting the magnitude of said exit air slit, and means for adjusting the magnitude of the minimum air contact angle, the angle at which the air curtain contacts said liquid streams, measured from the center line of said liquid discharge means.
35.
The system of claim 34, wherein said minimum contact angle is between about -10° and +30°.
The system of claim 34, wherein said minimum contact angle is between about -10° and +30°.
36.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) liquid supply means comprising liquid supply headers for discharging a plurality of liquid streams at low velocity, said liquid supply headers being disposed at right angles, one with respect to the other; and b) air supply means comprising an air supply header including means for discharging a continuous, high velocity, air curtain for contacting said liquid streams to produce said liquid spray curtain.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) liquid supply means comprising liquid supply headers for discharging a plurality of liquid streams at low velocity, said liquid supply headers being disposed at right angles, one with respect to the other; and b) air supply means comprising an air supply header including means for discharging a continuous, high velocity, air curtain for contacting said liquid streams to produce said liquid spray curtain.
37.
The system of claim 36, wherein said high velocity air curtain contacts said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of from about -10°, up to about +30°.
The system of claim 36, wherein said high velocity air curtain contacts said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of from about -10°, up to about +30°.
38.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) a liquid supply means comprising liquid supply headers, disposed at right angles one with respect to the other, for discharging a plurality of liquid streams at low velocity, each of said liquid supply headers comprising (i) a liquid supply chamber;
(ii) labyrinth means located within said liquid supply chamber for internally metering and longitudinally distributing the liquid flow, (iii) liquid reservoir means extending across essentially the entire longitudinal distance of said header, and (iv) means for discharging said liquid streams at a continuous, uniform flow rate which are adapted for liquid communication with the liquid reservoir means so that when said reservoir means is filled with liquid, said continuous, uniform flow rate is main-tained by a constant, static pressure head in said reservoir means; and b) air supply means comprising an air supply header which includes means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising a first sidewall member, a pair of end wall members, and a floor member, respectively, joined one to the other, and a second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits, said first sidewall member having an air flow guide means located at its outermost end which is disposed with respect to the center line of said liquid discharge means such that when said second sidewall member is positioned with respect to said air guide means, a high velocity, continuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from said center line, of between about -10° and +30°.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising a) a liquid supply means comprising liquid supply headers, disposed at right angles one with respect to the other, for discharging a plurality of liquid streams at low velocity, each of said liquid supply headers comprising (i) a liquid supply chamber;
(ii) labyrinth means located within said liquid supply chamber for internally metering and longitudinally distributing the liquid flow, (iii) liquid reservoir means extending across essentially the entire longitudinal distance of said header, and (iv) means for discharging said liquid streams at a continuous, uniform flow rate which are adapted for liquid communication with the liquid reservoir means so that when said reservoir means is filled with liquid, said continuous, uniform flow rate is main-tained by a constant, static pressure head in said reservoir means; and b) air supply means comprising an air supply header which includes means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising a first sidewall member, a pair of end wall members, and a floor member, respectively, joined one to the other, and a second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits, said first sidewall member having an air flow guide means located at its outermost end which is disposed with respect to the center line of said liquid discharge means such that when said second sidewall member is positioned with respect to said air guide means, a high velocity, continuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from said center line, of between about -10° and +30°.
39.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising:
a) a liquid supply means comprising liquid supply headers, disposed at right angles, one with respect to the other, for discharging a plurality of liquid streams at low velocity;
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising first and second sidewall members, respectively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits;
c) air flow guide means located at the outermost end of said first sidewall member;
d) air flow adjustment means for adjusting the quantity of air being admitted from said air slit; and e) means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, continuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of between about -10° and +30°.
A system for producing a liquid spray curtain capable of uniformly covering the entirety of a moving surface to be sprayed, without substantial streaking thereof, comprising:
a) a liquid supply means comprising liquid supply headers, disposed at right angles, one with respect to the other, for discharging a plurality of liquid streams at low velocity;
b) air supply means comprising an air supply header including means for discharging a continuous, high velocity air curtain for contacting said liquid streams to produce said liquid spray curtain, said air supply header comprising first and second sidewall members, respectively, said second sidewall member adapted for movement to a plurality of positions with respect to said first sidewall member, said air supply header having formed therewithin an air supply chamber which converges at its outermost end to form a continuous exit air slit through which said air curtain exits;
c) air flow guide means located at the outermost end of said first sidewall member;
d) air flow adjustment means for adjusting the quantity of air being admitted from said air slit; and e) means for adjusting the position of said second sidewall member with respect to said air flow guide means such that a high velocity, continuous air curtain is discharged from said exit slit which will contact said liquid streams at a minimum contact angle, measured from the center line of said liquid discharge means, of between about -10° and +30°.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15102380A | 1980-05-19 | 1980-05-19 | |
| US06/151,023 | 1980-05-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1174530A true CA1174530A (en) | 1984-09-18 |
Family
ID=22537014
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000377396A Expired CA1174530A (en) | 1980-05-19 | 1981-05-12 | Method and system for producing a liquid spray curtain |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0040927B1 (en) |
| JP (1) | JPS57500636A (en) |
| AT (1) | ATE10261T1 (en) |
| CA (1) | CA1174530A (en) |
| DE (1) | DE3167158D1 (en) |
| WO (1) | WO1981003372A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5115972A (en) * | 1991-02-06 | 1992-05-26 | Minnesota Mining And Manufacturing Company | Spray die for producing spray fans |
| GB9519692D0 (en) * | 1995-09-27 | 1995-11-29 | Quillin Helen | Atomising nozzle |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US958999A (en) * | 1909-12-16 | 1910-05-24 | Oscar Fordice | Hydrocarbon-burner. |
| US1888791A (en) * | 1930-09-27 | 1932-11-22 | Harry C Cole | Spraying method and machine |
| JPS522408B2 (en) * | 1971-09-10 | 1977-01-21 | ||
| US4072772A (en) * | 1973-08-09 | 1978-02-07 | Ppg Industries, Inc. | Linear curtain spray applicator |
| JPS516362A (en) * | 1974-07-05 | 1976-01-19 | Hitachi Plant Eng & Constr Co | Gesuiodeitono kyokyusochi |
-
1981
- 1981-05-11 JP JP56501813A patent/JPS57500636A/ja active Pending
- 1981-05-11 WO PCT/US1981/000664 patent/WO1981003372A1/en unknown
- 1981-05-12 CA CA000377396A patent/CA1174530A/en not_active Expired
- 1981-05-13 DE DE8181302126T patent/DE3167158D1/en not_active Expired
- 1981-05-13 EP EP81302126A patent/EP0040927B1/en not_active Expired
- 1981-05-13 AT AT81302126T patent/ATE10261T1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| ATE10261T1 (en) | 1984-11-15 |
| WO1981003372A1 (en) | 1981-11-26 |
| EP0040927B1 (en) | 1984-11-14 |
| EP0040927A1 (en) | 1981-12-02 |
| JPS57500636A (en) | 1982-04-15 |
| DE3167158D1 (en) | 1984-12-20 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |