CA2187734A1 - Use of ultrasonics in connection with paper making - Google Patents
Use of ultrasonics in connection with paper makingInfo
- Publication number
- CA2187734A1 CA2187734A1 CA 2187734 CA2187734A CA2187734A1 CA 2187734 A1 CA2187734 A1 CA 2187734A1 CA 2187734 CA2187734 CA 2187734 CA 2187734 A CA2187734 A CA 2187734A CA 2187734 A1 CA2187734 A1 CA 2187734A1
- Authority
- CA
- Canada
- Prior art keywords
- added
- ultrasonic
- ultrasonic energy
- energy
- flocculation
- 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.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/10—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing sonic or ultrasonic vibrations
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/0018—Devices for dispensing fibres in a fluid
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/02—Head boxes of Fourdrinier machines
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/02—Head boxes of Fourdrinier machines
- D21F1/028—Details of the nozzle section
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Paper (AREA)
Abstract
Method for preventing fibre floccula-tions to occur and to disperse already formed fibre flocculations, better to distribute additive chemicals, to increase fibrillation, to improve reaction and yield from two component chem-icals, to prevent the forming of microbiologi-cal and other types of build-ups onto machine parts and other parts of the white water cir-culations, to prevent the filling of wires and felts, to prevent flocculation in coating equip-ments, to reduce content of air in the stock, and to reduce the foaming. This is achieved by that ultrasonic energy with a frequency of 15 - 60 kHz is added to the stock, machine parts, washing trays or coaters via externally mounted ultrasonic transducers or internally applied submersible ultrasonic units. The ul-trasonic energy is added preferably by means of externally onto the head box mounted ul-trasonic transducers or internally applied sub-mersible ultrasonic units. The level of ultra-sonic energy is controlled by in-line installed formation or flocculation size measurement systems to arrive at desired flocculation. The measured flocculation is used as a criterium for set point optimisation of weight per unit area for the paper or the board produced, and for maximum production per unit of time.
Description
WO 95128521 2 1 8 7 7 3 4 r ~
USE OF ULTRASONICS IN I llON WITH PAPER MAltING
This patent application deals with the Arpl;r~t;nn of ultrasonic energy to the pAr~rr-lr;n~ procegg in order to achieve gi~n;f;rnnt advantages. The ultrasonic energy is hereby added to the part of the process g~n~rA1 1y ~ d to ag the short white water system, i . e . headbox or h~P~ , the white water which is separated in the wire part and which i9 used for ~;lu~;nn of the stock to a desired stock consistency and to white water trays and tanks within this white water system. In addition ultr~Qnn;c energy is added to wash systems for wires and felts in order to r~-;nt~;n them completely clean and to prevent the bln~k;n~ of them, which leads to constant and high dewatering capacities for those parts of the r~r--rr-k;n~ process. In summary this means, paper quality, increased yield for paper constituents, reduced steam rnn _ tion and increased production capacity per rrq~ t;nn unit.
The addition of ul~-~Qnn;c energy to the white water system is ~lone in order to prevent the forming of fibre fln~lrlllAtinn in the paper, and to prevent microbiological growth, which leads to the forming of lumps of slime which in comhination with lumps of fibres will cause breaks and machine stops for wash-ups and thereby 1088 of production time. It will in some cases, when a micrnh;olo~;~al cnni ~n;nAtion has been found to come from a certain raw mAterial which is added to the white water system be n~c~Q~ y to add ultrasonic energy also to that raw material in order to prevent the dev~l ~, t of such a source of contamina-tion .
The utilization of ul~-AQnn~c energy in the pulp and paper industry is known earlier, but has been limited to the pro~rt;nn of pulp and within the stock preparation system and it has been added far ahead of the actual paper machine.
Patent GB A 1 577 664 describes a method whereby one uses ul~ra~on;c energy to remove a very tro~hl~F type of resin from WO 95/Z8~Z1 2 1 ~ 7 7 ~ ~ r~ 7~
a pulp manufactured $rom sperific wood 8pecies, a resin which caused big prnhl - in the form of percipitations of resin of different paper machine parts. The patent thus addresses a completely different problem than thoge addre8sed in this patent, and the addition of ul~rnann;~ energy is made far ahead of the paper ~chine.
Derwen~:' 8 Abstract No. 82-97003E/45, SIJ 896130 describes a method whereby ul~A~nn;c energy is ~dded to high consistency screens, used for the screening of pUlp p_rticularily to prevent the form~n~g of fibre knots, i.e. far ah~ad of the paper machine.
Derwent' 8 Abstract No. 82-85514E/40, S~r 887610 describes a method whereby ul~annn;c energy has been used in the stock prepAration in order to improve the coloring of the stock, which also is done far ahead of the paper m~chine. The patent describes a batch processing method, which has not been f~ ~3~- ' to be used in a ~ nn~;nll~ process .
Derwent~s Abstract No. 81-17053/D, S~ 746012 is also dealing with a batch process in the stock prernrAt;nn, where ultrn~nn;c energy h_s b~en u3ed in order to be able to add a pAr~ff;n-wax di8-persion and copolymers in order to manufacture a paper with ; _ ~,v~d - ' ; rAl strength and with water r~r~l l;n~ properties.
In addition, it is known from Tappi Journal Vol. 77, ~o. 3, that ultrasonic energy can be used to improve the ~ ;nl~;ng of recycled fibre stock made from paper which ha8 b~en laser printed, which means, that the toner has been fixed onto the sheet u8ing high temperature and is very ~;ff;c~lt to remove.
The use of ul~rn~nn;c energy in above - 'inn~d ~ ucesse~ aims at solving completely different problems that does this patent, and i~volve dif~erent processes .g. - ~~ ing of pulp from wood and 3~--n-l_- y fibres, and stock preparation far ahead of the actual pnr~rr~k;n~ process.
W095/28521 2 i 8 7 7 3 4 p~l/~7e The utilization of ull rA~rn;c energy to 801ve the rrrhl-covered by this patent l~rpl;~rnt;rn calmot be An~;c;rAted by the abovce - ; rnrcl publicationg and i8 algo not obvious to th~
~ expert in these f ields .
~PACT ON ECONOIIY
The uneven distribution of fibres in the paper sheet caused by fiber flocc~ tion is cons;~1 DrAh1 e. The 8t~tistical fibre weight variation when tested with paper r~n~ q with an area of 23.5 square m;ll; ters was 7-10% wherea8 it wa8 0.5 - 0.8% when the trAdition~ll rrn~ llpq of 20 000 gguare m;ll; t~:, were used.
Large profits can thus be achieved, if flr,rc~ tion of fibres can be eliminated or reduced, which in turn _akes it possihle to arrive At the same ~L ~yLh properties with less weight per unit Are~. For the Swedish pAper market the totAl profit potential i8 SER 350 625 000 per percent reduction of the weight per unit area .
The reduction of the number of breaks and stops for rl~An;n~ due to the elimination of slime and fibre agg7~ ~t;~n~ gives a direct profit for the Swedish paper production of SER 730 000 000 per ye~r in Addition to enviL~ 1 profits, since no pll~ ;
rh~.m;rAlq are used for the slime control.
The impact on profits fro_; _ uv~:d dewatering in the wire- and drying gections is also crnqi~l~rAhle. ~rn~;nl-~--q rloAn;n~ of all pressfelts should re8ult in a 0.4 - 0.5% higher dry solids content after the press part. A 0.5% higher dry solids content cu ~ ~ds to a posq;hle production incre~se of 2.21% cc ~,,uu~-ding to a profit potential for the Swedish paper industry of SER
620 000 000 per year.
DESCRIPTION OF INSTALLATION
Fig. 1 is a schematic, p~rtly sectioned profile of a head box wlth an air cu8hion ~nd equipped with ultrasonic 1 rAnq~ r~r8 1, suitable to utilize for this invention.
_ .. . _ . . .. . . . _ .. . . . . _ _ _ Flgs. ~-5 are schematic, partly sectioned proflles of ii; ffPr~nt hydr~ulic head boxes equipped with ultrasonic suitable to utilize for thls invention.
Fig. 6 is a two layer hydraulic head box equipped with ultrasonic tL~..Ddu.;t:La 1, 8uitable to utilize for this invention.
Fig. 7 is a head box where the pelLoLaLed roll has been replaced by submersible units equ;rpPA with ultrasonic L.c,---du-el~ 1, sultable to utillze for this lnvention.
Figs. 8 and 9 are ~- ,1 pc~ of washing systems for wires and felts, PqllippPti with ultrasonic LL...."'1"'.~ 1, suitable for the utilization of this invention.
Above mentioned arrangements are l 1 PC only of how the invention can be applied, but other solutions are r~ hle which are i~tended to be within the scope of this invention.
~;v~;h.lON OF FrflCClJr,A~ION
In the r~rPrr~kin~ process one trles by means of various - ' ;cAl devices to prevent the forming of flocs within the flbre SllcpPnQ;r~n whlch flows onto the fourdrinier wire from the head box, so that one gets as even flbre and filler distribution in the f; n; ~hP~i paper product as p~ l hl P, The f locs are built up by fibres and fillers but are initially made up by fibres.
Higher pulp consistency, higher degree of refining and longer fibres will increase the fl~ c~ tion, which in turn forces the paper ~ 'a~;LuL~La to work with very low consistencies during the production of e.~. sack paper. The size and form of the flocs can e;~sily be detPrm~ nPd by observing the paper sheet by means of tr~ncll~Pnt light. The flocs are then L~Lc~ Le:~ by the darkel- parts of the paper with lighter parts between them. The paper is thus built-up by darker parts with a higher weight per unit area and lighter parts with lower weight per unit area. The Lll ~lyLII properties of the paper are in~,L~ d by higher and de~;Lt:aaed by lower weight per unit area. This means, that the ~ Llt:lly Ll- properties of the paper are controlled by the lighter parts between the darker parts of the paper. Filler and fibre retention, particularily the retention of fines, is higher in the flocs, whereas they in the lighter parts tend to follow ~ W09~/28521 2 ~ 87i~ r~
the white water which is drained from the paper machine wet end, i.e. the wire and press sections.
A reduction of the florr~ tion~ L~ d to a8 i _ vv. t of the fr~-l-;nn by the paper maker, thus leads to either thAt one can manufacture a paper with ' ~ vv~d strength properties with the same weight of fibres per unit ~rea, or manufActure a paper with the same strength properties from less fibres per unit ~rea.
An; _ vv~ t of the formation thug gives the possih; l; ty of better fibre yield and in turn to an; _ vv~d raw material economy. The flocs also contain re water and will reduce the dewatering on the wire Ag well as in the press section which in turn leads to an increased tendency of crushing in the press section which is caused by the fast water flow caused by that more water must be s~rat~ from the sheet will teAr fibres aw~y from it, and when the hydraulic pressure is large enough cause a break. In order to reduce the number of bre~ks, one then will have to work with less pressure in the presses, which reduces the dry solids content from the press section for the pAper entering into the dryer s~ction. This in turn leads to a higher steam consu~ption per ton, which also m~kes a lower pro~llr~ n speed n~r~elg~. . y unle8g the dryer 8ection capacity is increased. In summary:; _ vv.l formAtion leAds to a better raw material ~nd energy ~~nr t, and offers a p~ss;h;l;ty to increase produc-tion per unit time which in turn reduces the sp~c;f;c capital costs. The largest cost reductions will be achieved when one can take total advantage of the poss;h; l; ty to produce p~per with reduced weight per unit area, but still ~-;n~A;n the same strength properties of the ~vduced paper.
An; _ vv. t of the formation is thus of vital interest terl~n;rAlly Ag well as ~ r~-lly. Different degigns of head boxes have been developed in order to achieve that goal, ~An~Al ly by b~ ;n~ in rotating p~rfr~-~t~l rolls and/or repeated ~ n~irn~ and reductions of the through flow Area which cAuses stock flow ~ h~ nre, which at least in theory should prevent the f orming of new f locs . vne could say that the W095/28521 21 8773~ I~1,~7~.
situation has been; _ ~,v.d but that the problem remains unsol~ed.
The addition of ultr~l~^n;~A energy in the range of 15 kEz - 60 k~Iz to arrive at the advAntages ~;^n-d above solves or s;~n;f;rAl_ ly reduces these problems. The ul~rAA^n;r en~ryy is in this case added to the stock in the head box either by gluing the ultraso-nic ~ A 9--~ which are mounted on ~1 'n; bars onto the head box for air cushion And open head boxes preferably l~n~orn~Ath the head box, and all around the head box for hydraulic head boxes (figs. 1-6~ . One could also mount the ~rAn9~r~Ar8 within a number of suhmersible units installed inside the head box (fig. 7) or by means of a corbination of the different ways of installation.
The ultrasonic tr~ns~ r-~rs~ are installed such that the ultrasonic energy is added to the stock within the entire length, width and height of the head box using several pArAl 1 ~1 combinations of ~rAn~ldllA~r~. In this way one assertains that s~ff;;~nt amount of ultrasonic energy to solve the problem is added to the stock.
The stock is pumped into the head box via a ;fo~d and a diffusor b~nk. When it enters into the head box after the diffuaor b~nk, a very rapid reduction of flow velocity occurs which assertains th_t the flocs are tl;Ar~ar5erl The reforming of the flocs occurs very rapidly and it i8 desirable that one assertains that the r~form;nAJ of the flocs is prevented. The prese~lt t~rhn~lo~y has not made it possihl ~ to arrive at these results in 8pite of the many different designs that have been tested and been in operation during decades.
The dispersing effect of the ul~rAs^n;r energy is caused by the well known cavitation which is uged for u1l rAsnn; ~ An;n~ Of different ~ _ ~s, e.g. anilox rolls or y.~vu d rolls for flexo- and rotGy --vU ~ printing and where it is also poss;hle to remove even dried watorhA~d ink from the y ~vu ~d cell8. When an ultrasonic sound wave LLC~V~ :.e5 a material, the ~ cl~l C~9. of the material are induced to vibrate longitudinal in the direction of the wave propagation. This results in pressure v~rirtions 2 1 8 7 7 3 4 P~
which in a liquid leads to cavitation or the f t;nn of small bubbles about 0.1 - 0.2 mm in r1;~ teL. When these small bubbles are ~r~ tQcl with u~ o~n~l~ they will continuously absorb energy from the compression and QYp"n~i"n cycles of the ultraso-nic sound waves and grow to their critical size which is t upon wave length after which they start to grow in size very rapidly and will finally implode which they do in less than a mi.L.secvnd. The; _lo~l;ng bubbles will transmit energy to the nearby medium which in a fibre s~RF~n~ n means that they disperse existing ~locs as well as prevent new flocs to occur and in addition increase the fibrillation. That the fibri~ t;rn occurs has been verified by mea~L~ ta of LL_~e3s ralues, where the difference of freeness values before and after the ~ddition o~ ul~ ARnn;c energy has been verified. The dispersing effect has also been documented in the Swedi8h patent ~ppl ;r~ n 9002006-6 (468 754) where the ~ IpQ. ~;ng effect of the ultrasonic energy has resulted in print quality; ~ ,vc 1 ~ and to ink savings .
The addition of ull ~Rnn;~ energy will prevent the r~-J ~- ~t;~-n o~ flocs and di8perse already formed flocs. If the ultrasonic energy is added over a range of wavelengths with wavelength gweeps over that range, it will since the length of one wave-length is directly ~1 L' "~' - t upon frequency, cause, that wavelengths of different LLcs~ ;eR are located on different distances ~rom the t~nRd~rQ~ and is trAnsmitted throu~h the medium in multiples of these distances. In that way the ultraso-nic cavitation will be distributed in the entire ~ibre s~ p~n~ n and prevent L.~c~_Lc.tion or forming of flocs. It will furthermore contribute to ~ RR;n~ and reduced foaming.
.
Other rh~.m;r~ are also used in the production of paper, e.g.
re~n~;~m aids, which are polymers, often two - _ t types whic_ are used for improvi~g the retention of fibres and filler_ in the web in the wire section and thus reduce the content of these paper constituents in the white water and to increase them in the web leaving the wire section entering into the press _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ . . _ . _ _ . _ . _ _ W0 95128S21 ~ 8 ~ r~
section. The ul~rA- ;c energy disperses each - _ ~ of these ~h~;rAln which increases the reactivity and improves the yield.
They will in addition distribute them more evenly which leAds to impro~ed retention ~or the same amount of retention aid or the same ret^n~; nn with less ret-ntinn aids .
Fi~re a~ tions on _achine parts which a~ter 80me time will ce off and eventuAlly cAuse breaks, are other areas wehre the di3persing e~fect of ul~rAr ;c energy can be used. They are lly formed at lonAl-;nn where there are eddy currents e.g.
around trnnn~-lr~l-8, innpert;~n doors, deckel boards and the like.
An instilllation of ultr~nn;r ~r~n~11r~rR near these lorAt;nnn will prevent the forming of such fibre agglomorations.
Other parts of the paper machine can also take advantage of the dispe~:sing _nd c~An;n~ effect of the ultrA~ ~n;c energy. r _t~R
o1' this are felt8 and wires where one, if they are passed through a tray with an Ull-rAnnn; c rl~An~ng bath, ~ '; also contai-ning rh~m;rAln to prevent m;rrnhjolo~ l growth, percipitation of pitch and other organic and inorganic guL.. L~;.ce,3 which c~n reduce dewatering effect and useful life. r _~l^ of applicAtion as per f lgs . 8 and 9 .
One ~1as earlier been of the opinion that the presence o~
r~ll1llnne fibres in the stock, the large stock flow and the large volume in the head box has made it; _ s;h~e to apply ultrasonic energy to the pAr~rr-lr;n~ process since it will be rapidly Ah8n~h~1 and th~cec~,Le cannot have an impact within the entire stock volume. It ha8 been demonstrated that this is not the case and 1:he application of ultr;~nn;c energy to the pAr~~~k;
process thus ~ ts a _ let~ly new thinking and it is therefore a terhn;r~Al novelty. The ultrAnnn;c energy is very rapidly distributed in a fibre s~p^nsin~. It is true that the lnqe fibre8 absorb part of the ultr~snnic energy due to an increase of f ibrillation and a decrease or prevention of flo~11lA~;nn, but this is a n~n~n~qAry and desired function a~d will not prevent the distribution of ul~rAnnn;c energy ~1 ,, ~1 .~"
Wo95/28S21 21 ~7~3~
the entire volume in the head box . The reason f or thi8 is that the lumen is 1 _ let~ly filled with water and that the cell walls also absorb a large volume of water. In such a way the entire volume of r~ lose s~Rron~inn actg ag a liquid and the ultrAso-nic energy can, if s~ff;r;^nt ull r~Rnn;c energy i9 added, be distributed tL v~yLuut the entire stock volume in the head box.
Increased degree of refining, increa8ed pulp consistency and increased speed of stock flow will increAse the spec;f;c energy requirements .
The utilisation of systems for installation in the paper machine wet end for inspection and mea2..- ~ ts of formation and fibre weight, can be used for the optimisation and control of stock consitency, ul~rA#nn;c power and other ,~ ;nn } ~ ~rR~
e.g. ~s~ff;~ nt paper __ to meet paper ~, .,y,, Ly sp~r;f;~A-tions . The sp~n; f; c u~ ; nn of raw materials such as paper making pulp, nho~n;cAl~ and energy can be optimised in a way that until now has not been possihle, and with revolut;nn~ry possibi-lities for; ~ # of quality and prof itability.
~icrobiological growth in the stock and water circulations has traditionally been a big problem in the pAper making process.
Aerobic as well as an~erobic slime forming mi-; U~l yc-~isms form slime build-up onto machine c _ ~R and walls of white water and stock tanks. The ~ _~:L.,ce of anaerobic growth i8 cl~lA;n~
by the fact, that the aerobic growth forms anaerobic conditions under itself due to the fact that the aerobic organisms will consume all available oxygen. The anaerobic growth of, particula-rily sulphate reducing bacteria such as Desulfovibrio Desulfuric-nas, will increase metal corrosion, and will directly ;nflvC~nne br;~htn~#s, particularily when reducing b~A~h;n~ with zinc or sodium L~ ,~hite is used.
The microbiological growth causes slime build-up onto machine parts, which build-up, sooner or later will come off as lumps, which are very ~;fflc~lt to dissolve. They are e.g. passing through fan pumps or other pumps and through ~; ff~#nr banks and W0 95128521 2 1 8 7 7 3 4 r~ ~ ~
perforated rolls and cAuses slime spots and production breaks.
The lumps consists m~ny times as well o_ ~ungi and bacteria as of or~anic and inorganic subst~nces. The ç, .s- ce of eddy curre~ts in water and stock systems will favour the growth and formi~g of fibre lumps, which will agravate the situation.
The control of these problems have traditionally been carried out bymeans of biolog;rlly active subst~nce8, kior;~R andbiostats, o_ten - :n~l with a dispersant. Initially organic mercury c __ '~ or r7~lo~tnAt~ phenols were used which cused much envir~ t~l harm to the ~-Yt-.rnAl env; t and this was the reason for demands of non-toxic control. It is certainly d;ff;c-~lt or t _-~sihle to come up with A rh~m;e~l both, b;nlo~;rAlly active, which at the same time must not ;nf7~1Qnre on bi olo~; onl life.
lJltrasonic energy will solve this problem. An addition of ultrasonic energy to the part wh~re microbiological growth occurs will effectively prevent agglomeration3 there. The ultrasonic energy can be ad~led ~Yt~nAlly a8 i~ done onto the head box for - t~l and tankg made of metal, particularily stainless steel. In tanlcs _ade o_ concrete, tiled or plastic coat~d, it will ~ave to be added by means of submersible units, in which case the distance to the wall and the e~nergy level will have to be matched so that the cavitation is powerful enough to ~olve the problem, but not so powerful that it will peel of the tile or coating .
The addition of ult ~Rnn;c energy to the paper making process is not limited to the ~ 1 R - t;nned above, but gimilar problems can be solved with other instAll~t;nnq e.g. in decculators to A' _~;qh; _ ~v~ tl~ in deaeration, or to prevent the _orming of flocr~~lAtions in different coating gtationg or lAm;n~t;n~
-h; n~R where water baged ~,du~ ~s are applied. The expert in the field will find, that this t~-rhnnlo~y can be ~pplied in many diffQrent parts of the paper machine or coater, in- or off-line, ~ 2 1 8773~ -but tho~e applicatio~s are ~nt~n~l~d to be withi~ the scope o~
. 2187734 WO 95/2~521 1 _I S'~ _ ~1/1 Iext regarding ara~ings PIG, 1 - 4 1. Ultralju~9ss~nd~re / ultrasonic L~ s~7, FIG. 5 . ultra~ ss~$n~Are / ultrasonic tr;lnsr~lCPr 2. Tubpaket med stegdiffusor / tube pack ~;h step diffuser 3. Tvarsfordelare / cross distributer FIG_ 6 1. Ultralj~ss~n~re / ultrasonic transducer 2. Tvarsfordelare / cross distributer 3. Tubpaket / tube pack 4. Plastfolie / plastic film FIG. 7 1. Ultralj~ss~ln~9~re / ultrasonic transducer FIG. 8 1. Ultral~ ss~nr~iqre / ultrasonic transducer 2. Vattenfyllt tvbttrag med overlop / water filled wash tray with overflow pipe 3. Pressfilt / press felt 4. Filtledvals / felt guide roll s Vakuumsuglada / vacuum suction ~ox 6. Vattenforsor~ning / water supply 1. Ul tral judssandare / ul trasonic transducer 2. Vattenfyllt tvbttrag med overlop / water filled tray with overflow pipe 3. Formeringsvlra / formlng wire 4. Viraledvals / wire guide roll . Sprltsror for skblJ'ning av viran och vattenfyllning av tvbttrag / spray pipe for rinstng of w~re and water filllng of wash tray
USE OF ULTRASONICS IN I llON WITH PAPER MAltING
This patent application deals with the Arpl;r~t;nn of ultrasonic energy to the pAr~rr-lr;n~ procegg in order to achieve gi~n;f;rnnt advantages. The ultrasonic energy is hereby added to the part of the process g~n~rA1 1y ~ d to ag the short white water system, i . e . headbox or h~P~ , the white water which is separated in the wire part and which i9 used for ~;lu~;nn of the stock to a desired stock consistency and to white water trays and tanks within this white water system. In addition ultr~Qnn;c energy is added to wash systems for wires and felts in order to r~-;nt~;n them completely clean and to prevent the bln~k;n~ of them, which leads to constant and high dewatering capacities for those parts of the r~r--rr-k;n~ process. In summary this means, paper quality, increased yield for paper constituents, reduced steam rnn _ tion and increased production capacity per rrq~ t;nn unit.
The addition of ul~-~Qnn;c energy to the white water system is ~lone in order to prevent the forming of fibre fln~lrlllAtinn in the paper, and to prevent microbiological growth, which leads to the forming of lumps of slime which in comhination with lumps of fibres will cause breaks and machine stops for wash-ups and thereby 1088 of production time. It will in some cases, when a micrnh;olo~;~al cnni ~n;nAtion has been found to come from a certain raw mAterial which is added to the white water system be n~c~Q~ y to add ultrasonic energy also to that raw material in order to prevent the dev~l ~, t of such a source of contamina-tion .
The utilization of ul~-AQnn~c energy in the pulp and paper industry is known earlier, but has been limited to the pro~rt;nn of pulp and within the stock preparation system and it has been added far ahead of the actual paper machine.
Patent GB A 1 577 664 describes a method whereby one uses ul~ra~on;c energy to remove a very tro~hl~F type of resin from WO 95/Z8~Z1 2 1 ~ 7 7 ~ ~ r~ 7~
a pulp manufactured $rom sperific wood 8pecies, a resin which caused big prnhl - in the form of percipitations of resin of different paper machine parts. The patent thus addresses a completely different problem than thoge addre8sed in this patent, and the addition of ul~rnann;~ energy is made far ahead of the paper ~chine.
Derwen~:' 8 Abstract No. 82-97003E/45, SIJ 896130 describes a method whereby ul~A~nn;c energy is ~dded to high consistency screens, used for the screening of pUlp p_rticularily to prevent the form~n~g of fibre knots, i.e. far ah~ad of the paper machine.
Derwent' 8 Abstract No. 82-85514E/40, S~r 887610 describes a method whereby ul~annn;c energy has been used in the stock prepAration in order to improve the coloring of the stock, which also is done far ahead of the paper m~chine. The patent describes a batch processing method, which has not been f~ ~3~- ' to be used in a ~ nn~;nll~ process .
Derwent~s Abstract No. 81-17053/D, S~ 746012 is also dealing with a batch process in the stock prernrAt;nn, where ultrn~nn;c energy h_s b~en u3ed in order to be able to add a pAr~ff;n-wax di8-persion and copolymers in order to manufacture a paper with ; _ ~,v~d - ' ; rAl strength and with water r~r~l l;n~ properties.
In addition, it is known from Tappi Journal Vol. 77, ~o. 3, that ultrasonic energy can be used to improve the ~ ;nl~;ng of recycled fibre stock made from paper which ha8 b~en laser printed, which means, that the toner has been fixed onto the sheet u8ing high temperature and is very ~;ff;c~lt to remove.
The use of ul~rn~nn;c energy in above - 'inn~d ~ ucesse~ aims at solving completely different problems that does this patent, and i~volve dif~erent processes .g. - ~~ ing of pulp from wood and 3~--n-l_- y fibres, and stock preparation far ahead of the actual pnr~rr~k;n~ process.
W095/28521 2 i 8 7 7 3 4 p~l/~7e The utilization of ull rA~rn;c energy to 801ve the rrrhl-covered by this patent l~rpl;~rnt;rn calmot be An~;c;rAted by the abovce - ; rnrcl publicationg and i8 algo not obvious to th~
~ expert in these f ields .
~PACT ON ECONOIIY
The uneven distribution of fibres in the paper sheet caused by fiber flocc~ tion is cons;~1 DrAh1 e. The 8t~tistical fibre weight variation when tested with paper r~n~ q with an area of 23.5 square m;ll; ters was 7-10% wherea8 it wa8 0.5 - 0.8% when the trAdition~ll rrn~ llpq of 20 000 gguare m;ll; t~:, were used.
Large profits can thus be achieved, if flr,rc~ tion of fibres can be eliminated or reduced, which in turn _akes it possihle to arrive At the same ~L ~yLh properties with less weight per unit Are~. For the Swedish pAper market the totAl profit potential i8 SER 350 625 000 per percent reduction of the weight per unit area .
The reduction of the number of breaks and stops for rl~An;n~ due to the elimination of slime and fibre agg7~ ~t;~n~ gives a direct profit for the Swedish paper production of SER 730 000 000 per ye~r in Addition to enviL~ 1 profits, since no pll~ ;
rh~.m;rAlq are used for the slime control.
The impact on profits fro_; _ uv~:d dewatering in the wire- and drying gections is also crnqi~l~rAhle. ~rn~;nl-~--q rloAn;n~ of all pressfelts should re8ult in a 0.4 - 0.5% higher dry solids content after the press part. A 0.5% higher dry solids content cu ~ ~ds to a posq;hle production incre~se of 2.21% cc ~,,uu~-ding to a profit potential for the Swedish paper industry of SER
620 000 000 per year.
DESCRIPTION OF INSTALLATION
Fig. 1 is a schematic, p~rtly sectioned profile of a head box wlth an air cu8hion ~nd equipped with ultrasonic 1 rAnq~ r~r8 1, suitable to utilize for this invention.
_ .. . _ . . .. . . . _ .. . . . . _ _ _ Flgs. ~-5 are schematic, partly sectioned proflles of ii; ffPr~nt hydr~ulic head boxes equipped with ultrasonic suitable to utilize for thls invention.
Fig. 6 is a two layer hydraulic head box equipped with ultrasonic tL~..Ddu.;t:La 1, 8uitable to utilize for this invention.
Fig. 7 is a head box where the pelLoLaLed roll has been replaced by submersible units equ;rpPA with ultrasonic L.c,---du-el~ 1, sultable to utillze for this lnvention.
Figs. 8 and 9 are ~- ,1 pc~ of washing systems for wires and felts, PqllippPti with ultrasonic LL...."'1"'.~ 1, suitable for the utilization of this invention.
Above mentioned arrangements are l 1 PC only of how the invention can be applied, but other solutions are r~ hle which are i~tended to be within the scope of this invention.
~;v~;h.lON OF FrflCClJr,A~ION
In the r~rPrr~kin~ process one trles by means of various - ' ;cAl devices to prevent the forming of flocs within the flbre SllcpPnQ;r~n whlch flows onto the fourdrinier wire from the head box, so that one gets as even flbre and filler distribution in the f; n; ~hP~i paper product as p~ l hl P, The f locs are built up by fibres and fillers but are initially made up by fibres.
Higher pulp consistency, higher degree of refining and longer fibres will increase the fl~ c~ tion, which in turn forces the paper ~ 'a~;LuL~La to work with very low consistencies during the production of e.~. sack paper. The size and form of the flocs can e;~sily be detPrm~ nPd by observing the paper sheet by means of tr~ncll~Pnt light. The flocs are then L~Lc~ Le:~ by the darkel- parts of the paper with lighter parts between them. The paper is thus built-up by darker parts with a higher weight per unit area and lighter parts with lower weight per unit area. The Lll ~lyLII properties of the paper are in~,L~ d by higher and de~;Lt:aaed by lower weight per unit area. This means, that the ~ Llt:lly Ll- properties of the paper are controlled by the lighter parts between the darker parts of the paper. Filler and fibre retention, particularily the retention of fines, is higher in the flocs, whereas they in the lighter parts tend to follow ~ W09~/28521 2 ~ 87i~ r~
the white water which is drained from the paper machine wet end, i.e. the wire and press sections.
A reduction of the florr~ tion~ L~ d to a8 i _ vv. t of the fr~-l-;nn by the paper maker, thus leads to either thAt one can manufacture a paper with ' ~ vv~d strength properties with the same weight of fibres per unit ~rea, or manufActure a paper with the same strength properties from less fibres per unit ~rea.
An; _ vv~ t of the formation thug gives the possih; l; ty of better fibre yield and in turn to an; _ vv~d raw material economy. The flocs also contain re water and will reduce the dewatering on the wire Ag well as in the press section which in turn leads to an increased tendency of crushing in the press section which is caused by the fast water flow caused by that more water must be s~rat~ from the sheet will teAr fibres aw~y from it, and when the hydraulic pressure is large enough cause a break. In order to reduce the number of bre~ks, one then will have to work with less pressure in the presses, which reduces the dry solids content from the press section for the pAper entering into the dryer s~ction. This in turn leads to a higher steam consu~ption per ton, which also m~kes a lower pro~llr~ n speed n~r~elg~. . y unle8g the dryer 8ection capacity is increased. In summary:; _ vv.l formAtion leAds to a better raw material ~nd energy ~~nr t, and offers a p~ss;h;l;ty to increase produc-tion per unit time which in turn reduces the sp~c;f;c capital costs. The largest cost reductions will be achieved when one can take total advantage of the poss;h; l; ty to produce p~per with reduced weight per unit area, but still ~-;n~A;n the same strength properties of the ~vduced paper.
An; _ vv. t of the formation is thus of vital interest terl~n;rAlly Ag well as ~ r~-lly. Different degigns of head boxes have been developed in order to achieve that goal, ~An~Al ly by b~ ;n~ in rotating p~rfr~-~t~l rolls and/or repeated ~ n~irn~ and reductions of the through flow Area which cAuses stock flow ~ h~ nre, which at least in theory should prevent the f orming of new f locs . vne could say that the W095/28521 21 8773~ I~1,~7~.
situation has been; _ ~,v.d but that the problem remains unsol~ed.
The addition of ultr~l~^n;~A energy in the range of 15 kEz - 60 k~Iz to arrive at the advAntages ~;^n-d above solves or s;~n;f;rAl_ ly reduces these problems. The ul~rAA^n;r en~ryy is in this case added to the stock in the head box either by gluing the ultraso-nic ~ A 9--~ which are mounted on ~1 'n; bars onto the head box for air cushion And open head boxes preferably l~n~orn~Ath the head box, and all around the head box for hydraulic head boxes (figs. 1-6~ . One could also mount the ~rAn9~r~Ar8 within a number of suhmersible units installed inside the head box (fig. 7) or by means of a corbination of the different ways of installation.
The ultrasonic tr~ns~ r-~rs~ are installed such that the ultrasonic energy is added to the stock within the entire length, width and height of the head box using several pArAl 1 ~1 combinations of ~rAn~ldllA~r~. In this way one assertains that s~ff;;~nt amount of ultrasonic energy to solve the problem is added to the stock.
The stock is pumped into the head box via a ;fo~d and a diffusor b~nk. When it enters into the head box after the diffuaor b~nk, a very rapid reduction of flow velocity occurs which assertains th_t the flocs are tl;Ar~ar5erl The reforming of the flocs occurs very rapidly and it i8 desirable that one assertains that the r~form;nAJ of the flocs is prevented. The prese~lt t~rhn~lo~y has not made it possihl ~ to arrive at these results in 8pite of the many different designs that have been tested and been in operation during decades.
The dispersing effect of the ul~rAs^n;r energy is caused by the well known cavitation which is uged for u1l rAsnn; ~ An;n~ Of different ~ _ ~s, e.g. anilox rolls or y.~vu d rolls for flexo- and rotGy --vU ~ printing and where it is also poss;hle to remove even dried watorhA~d ink from the y ~vu ~d cell8. When an ultrasonic sound wave LLC~V~ :.e5 a material, the ~ cl~l C~9. of the material are induced to vibrate longitudinal in the direction of the wave propagation. This results in pressure v~rirtions 2 1 8 7 7 3 4 P~
which in a liquid leads to cavitation or the f t;nn of small bubbles about 0.1 - 0.2 mm in r1;~ teL. When these small bubbles are ~r~ tQcl with u~ o~n~l~ they will continuously absorb energy from the compression and QYp"n~i"n cycles of the ultraso-nic sound waves and grow to their critical size which is t upon wave length after which they start to grow in size very rapidly and will finally implode which they do in less than a mi.L.secvnd. The; _lo~l;ng bubbles will transmit energy to the nearby medium which in a fibre s~RF~n~ n means that they disperse existing ~locs as well as prevent new flocs to occur and in addition increase the fibrillation. That the fibri~ t;rn occurs has been verified by mea~L~ ta of LL_~e3s ralues, where the difference of freeness values before and after the ~ddition o~ ul~ ARnn;c energy has been verified. The dispersing effect has also been documented in the Swedi8h patent ~ppl ;r~ n 9002006-6 (468 754) where the ~ IpQ. ~;ng effect of the ultrasonic energy has resulted in print quality; ~ ,vc 1 ~ and to ink savings .
The addition of ull ~Rnn;~ energy will prevent the r~-J ~- ~t;~-n o~ flocs and di8perse already formed flocs. If the ultrasonic energy is added over a range of wavelengths with wavelength gweeps over that range, it will since the length of one wave-length is directly ~1 L' "~' - t upon frequency, cause, that wavelengths of different LLcs~ ;eR are located on different distances ~rom the t~nRd~rQ~ and is trAnsmitted throu~h the medium in multiples of these distances. In that way the ultraso-nic cavitation will be distributed in the entire ~ibre s~ p~n~ n and prevent L.~c~_Lc.tion or forming of flocs. It will furthermore contribute to ~ RR;n~ and reduced foaming.
.
Other rh~.m;r~ are also used in the production of paper, e.g.
re~n~;~m aids, which are polymers, often two - _ t types whic_ are used for improvi~g the retention of fibres and filler_ in the web in the wire section and thus reduce the content of these paper constituents in the white water and to increase them in the web leaving the wire section entering into the press _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ . . _ . _ _ . _ . _ _ W0 95128S21 ~ 8 ~ r~
section. The ul~rA- ;c energy disperses each - _ ~ of these ~h~;rAln which increases the reactivity and improves the yield.
They will in addition distribute them more evenly which leAds to impro~ed retention ~or the same amount of retention aid or the same ret^n~; nn with less ret-ntinn aids .
Fi~re a~ tions on _achine parts which a~ter 80me time will ce off and eventuAlly cAuse breaks, are other areas wehre the di3persing e~fect of ul~rAr ;c energy can be used. They are lly formed at lonAl-;nn where there are eddy currents e.g.
around trnnn~-lr~l-8, innpert;~n doors, deckel boards and the like.
An instilllation of ultr~nn;r ~r~n~11r~rR near these lorAt;nnn will prevent the forming of such fibre agglomorations.
Other parts of the paper machine can also take advantage of the dispe~:sing _nd c~An;n~ effect of the ultrA~ ~n;c energy. r _t~R
o1' this are felt8 and wires where one, if they are passed through a tray with an Ull-rAnnn; c rl~An~ng bath, ~ '; also contai-ning rh~m;rAln to prevent m;rrnhjolo~ l growth, percipitation of pitch and other organic and inorganic guL.. L~;.ce,3 which c~n reduce dewatering effect and useful life. r _~l^ of applicAtion as per f lgs . 8 and 9 .
One ~1as earlier been of the opinion that the presence o~
r~ll1llnne fibres in the stock, the large stock flow and the large volume in the head box has made it; _ s;h~e to apply ultrasonic energy to the pAr~rr-lr;n~ process since it will be rapidly Ah8n~h~1 and th~cec~,Le cannot have an impact within the entire stock volume. It ha8 been demonstrated that this is not the case and 1:he application of ultr;~nn;c energy to the pAr~~~k;
process thus ~ ts a _ let~ly new thinking and it is therefore a terhn;r~Al novelty. The ultrAnnn;c energy is very rapidly distributed in a fibre s~p^nsin~. It is true that the lnqe fibre8 absorb part of the ultr~snnic energy due to an increase of f ibrillation and a decrease or prevention of flo~11lA~;nn, but this is a n~n~n~qAry and desired function a~d will not prevent the distribution of ul~rAnnn;c energy ~1 ,, ~1 .~"
Wo95/28S21 21 ~7~3~
the entire volume in the head box . The reason f or thi8 is that the lumen is 1 _ let~ly filled with water and that the cell walls also absorb a large volume of water. In such a way the entire volume of r~ lose s~Rron~inn actg ag a liquid and the ultrAso-nic energy can, if s~ff;r;^nt ull r~Rnn;c energy i9 added, be distributed tL v~yLuut the entire stock volume in the head box.
Increased degree of refining, increa8ed pulp consistency and increased speed of stock flow will increAse the spec;f;c energy requirements .
The utilisation of systems for installation in the paper machine wet end for inspection and mea2..- ~ ts of formation and fibre weight, can be used for the optimisation and control of stock consitency, ul~rA#nn;c power and other ,~ ;nn } ~ ~rR~
e.g. ~s~ff;~ nt paper __ to meet paper ~, .,y,, Ly sp~r;f;~A-tions . The sp~n; f; c u~ ; nn of raw materials such as paper making pulp, nho~n;cAl~ and energy can be optimised in a way that until now has not been possihle, and with revolut;nn~ry possibi-lities for; ~ # of quality and prof itability.
~icrobiological growth in the stock and water circulations has traditionally been a big problem in the pAper making process.
Aerobic as well as an~erobic slime forming mi-; U~l yc-~isms form slime build-up onto machine c _ ~R and walls of white water and stock tanks. The ~ _~:L.,ce of anaerobic growth i8 cl~lA;n~
by the fact, that the aerobic growth forms anaerobic conditions under itself due to the fact that the aerobic organisms will consume all available oxygen. The anaerobic growth of, particula-rily sulphate reducing bacteria such as Desulfovibrio Desulfuric-nas, will increase metal corrosion, and will directly ;nflvC~nne br;~htn~#s, particularily when reducing b~A~h;n~ with zinc or sodium L~ ,~hite is used.
The microbiological growth causes slime build-up onto machine parts, which build-up, sooner or later will come off as lumps, which are very ~;fflc~lt to dissolve. They are e.g. passing through fan pumps or other pumps and through ~; ff~#nr banks and W0 95128521 2 1 8 7 7 3 4 r~ ~ ~
perforated rolls and cAuses slime spots and production breaks.
The lumps consists m~ny times as well o_ ~ungi and bacteria as of or~anic and inorganic subst~nces. The ç, .s- ce of eddy curre~ts in water and stock systems will favour the growth and formi~g of fibre lumps, which will agravate the situation.
The control of these problems have traditionally been carried out bymeans of biolog;rlly active subst~nce8, kior;~R andbiostats, o_ten - :n~l with a dispersant. Initially organic mercury c __ '~ or r7~lo~tnAt~ phenols were used which cused much envir~ t~l harm to the ~-Yt-.rnAl env; t and this was the reason for demands of non-toxic control. It is certainly d;ff;c-~lt or t _-~sihle to come up with A rh~m;e~l both, b;nlo~;rAlly active, which at the same time must not ;nf7~1Qnre on bi olo~; onl life.
lJltrasonic energy will solve this problem. An addition of ultrasonic energy to the part wh~re microbiological growth occurs will effectively prevent agglomeration3 there. The ultrasonic energy can be ad~led ~Yt~nAlly a8 i~ done onto the head box for - t~l and tankg made of metal, particularily stainless steel. In tanlcs _ade o_ concrete, tiled or plastic coat~d, it will ~ave to be added by means of submersible units, in which case the distance to the wall and the e~nergy level will have to be matched so that the cavitation is powerful enough to ~olve the problem, but not so powerful that it will peel of the tile or coating .
The addition of ult ~Rnn;c energy to the paper making process is not limited to the ~ 1 R - t;nned above, but gimilar problems can be solved with other instAll~t;nnq e.g. in decculators to A' _~;qh; _ ~v~ tl~ in deaeration, or to prevent the _orming of flocr~~lAtions in different coating gtationg or lAm;n~t;n~
-h; n~R where water baged ~,du~ ~s are applied. The expert in the field will find, that this t~-rhnnlo~y can be ~pplied in many diffQrent parts of the paper machine or coater, in- or off-line, ~ 2 1 8773~ -but tho~e applicatio~s are ~nt~n~l~d to be withi~ the scope o~
. 2187734 WO 95/2~521 1 _I S'~ _ ~1/1 Iext regarding ara~ings PIG, 1 - 4 1. Ultralju~9ss~nd~re / ultrasonic L~ s~7, FIG. 5 . ultra~ ss~$n~Are / ultrasonic tr;lnsr~lCPr 2. Tubpaket med stegdiffusor / tube pack ~;h step diffuser 3. Tvarsfordelare / cross distributer FIG_ 6 1. Ultralj~ss~n~re / ultrasonic transducer 2. Tvarsfordelare / cross distributer 3. Tubpaket / tube pack 4. Plastfolie / plastic film FIG. 7 1. Ultralj~ss~ln~9~re / ultrasonic transducer FIG. 8 1. Ultral~ ss~nr~iqre / ultrasonic transducer 2. Vattenfyllt tvbttrag med overlop / water filled wash tray with overflow pipe 3. Pressfilt / press felt 4. Filtledvals / felt guide roll s Vakuumsuglada / vacuum suction ~ox 6. Vattenforsor~ning / water supply 1. Ul tral judssandare / ul trasonic transducer 2. Vattenfyllt tvbttrag med overlop / water filled tray with overflow pipe 3. Formeringsvlra / formlng wire 4. Viraledvals / wire guide roll . Sprltsror for skblJ'ning av viran och vattenfyllning av tvbttrag / spray pipe for rinstng of w~re and water filllng of wash tray
Claims (9)
1 Claims l. Method for preventing fibre flocculations to occur and to disperse already formed fibre flocculations, for increasing fibrillation, for improving reaction and yield from two component chemicals, for preventing forming of microbiological and other types of build-up onto machine parts and other parts of the white water circulations, for preventing filling of wires and felts, preventing flocculation in coating stations or machines, reducing content of air in the stock, and reducing foaming, characterized by that ultrasonic energy with a frequency of 15 - 60 kHz is added to the stock, machine parts, washing trays and coaters via externally mounted ultrasonic transducers or internally applied submersible ultrasonic units.
2. Method according to claim 1, characterized by that the ultrasonic energy is added by means of externally onto the head box mounted ultrasonic transducers or internally applied submersible ultrasonic units as per Fig. 2 or 3, and that the ultrasonic energy is used to improve formation and retention.
3. Method according to claim 1 or 2, characterized by that the level of ultrasonic energy is controlled by in-line installed formation or flocculation size measurement systems to arrive at desired flocculation, and that this measured flocculation is used as a criterium for set point optimisation of weight per unit area for the paper or the board produced, and for maximum production per unit of time.
4. Method according to claim 1, characterized by that the ultrasonic energy is added to machine parts or tanks in the white water circulation to prevent the build-up of microbiologic, organic or inorganic nature.
5. Method according to claim 1, characterized by that the ultrasonic energy is added to special washing trays to prevent the filling of felts and wires of microbiologic, organic or inorganic nature.
6. Method according to claim 1, characterized by that the ultrasonic energy is added to the coating substance in coating or lamination stations to prevent forming of different types of flocculations in the coating substance circulation or forming build-ups onto machine parts in the station.
7. Method according to claim 1, characterized by that the ultrasonic energy is added to the stock in order to reduce foaming and to improve deaeration.
8. Method according to claims 1 - 7, characterized by that the added ultrasonic energy will sweep over a frequency range within 15 kHz - 60 kHz.
9. Method according to claims 1 - 7, characterized by that the added ultrasonic energy has one or several predetermined frequencies between 15 kHz - 60 kHz.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9401272A SE9401272L (en) | 1994-04-14 | 1994-04-14 | Use of ultrasound in papermaking |
| SE9401272-1 | 1994-04-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2187734A1 true CA2187734A1 (en) | 1995-10-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2187734 Abandoned CA2187734A1 (en) | 1994-04-14 | 1995-04-12 | Use of ultrasonics in connection with paper making |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0755469A1 (en) |
| JP (1) | JPH09512063A (en) |
| CN (1) | CN1149898A (en) |
| AU (1) | AU2377895A (en) |
| CA (1) | CA2187734A1 (en) |
| FI (1) | FI964078A (en) |
| SE (1) | SE9401272L (en) |
| WO (1) | WO1995028521A1 (en) |
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|---|---|---|---|---|
| DE1185468B (en) * | 1958-11-27 | 1965-01-14 | Schickedanz Ver Papierwerk | Method for eliminating resin difficulties in papermaking |
| GB1577664A (en) * | 1977-05-10 | 1980-10-29 | Mitsubishi Corp | Process for preparing paper from lauan pulp |
| FI61735C (en) * | 1981-03-16 | 1982-09-10 | Valmet Oy | FOERFARANDE I SAMBAND MED PAPPERSTILLVERKNING |
| US4552781A (en) * | 1984-04-09 | 1985-11-12 | Westinghouse Electric Corp. | Method utilizing ultrasonically induced cavitation to impregnate porous sheet passing through a resin bath |
-
1994
- 1994-04-14 SE SE9401272A patent/SE9401272L/en not_active Application Discontinuation
-
1995
- 1995-04-12 WO PCT/SE1995/000398 patent/WO1995028521A1/en not_active Application Discontinuation
- 1995-04-12 CA CA 2187734 patent/CA2187734A1/en not_active Abandoned
- 1995-04-12 AU AU23778/95A patent/AU2377895A/en not_active Abandoned
- 1995-04-12 JP JP7526899A patent/JPH09512063A/en active Pending
- 1995-04-12 EP EP95916891A patent/EP0755469A1/en not_active Withdrawn
- 1995-04-12 CN CN 95193438 patent/CN1149898A/en active Pending
-
1996
- 1996-10-11 FI FI964078A patent/FI964078A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| FI964078A0 (en) | 1996-10-11 |
| CN1149898A (en) | 1997-05-14 |
| AU2377895A (en) | 1995-11-10 |
| SE9401272D0 (en) | 1994-04-14 |
| JPH09512063A (en) | 1997-12-02 |
| SE9401272L (en) | 1995-10-15 |
| WO1995028521A1 (en) | 1995-10-26 |
| EP0755469A1 (en) | 1997-01-29 |
| FI964078A (en) | 1996-10-11 |
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| Date | Code | Title | Description |
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| FZDE | Dead |