EP0132141B1 - Centrifugal cleaning of paper making stock - Google Patents

Centrifugal cleaning of paper making stock Download PDF

Info

Publication number
EP0132141B1
EP0132141B1 EP84304812A EP84304812A EP0132141B1 EP 0132141 B1 EP0132141 B1 EP 0132141B1 EP 84304812 A EP84304812 A EP 84304812A EP 84304812 A EP84304812 A EP 84304812A EP 0132141 B1 EP0132141 B1 EP 0132141B1
Authority
EP
European Patent Office
Prior art keywords
vessel
tube
chamber
housing means
outlet port
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
Application number
EP84304812A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0132141A3 (en
EP0132141A2 (en
Inventor
Terry L. Bliss
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Black Clawson (France) SA
Black Clawson Co
Original Assignee
Black Clawson (France) SA
Black Clawson Co
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Black Clawson (France) SA, Black Clawson Co filed Critical Black Clawson (France) SA
Publication of EP0132141A2 publication Critical patent/EP0132141A2/en
Publication of EP0132141A3 publication Critical patent/EP0132141A3/en
Application granted granted Critical
Publication of EP0132141B1 publication Critical patent/EP0132141B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
    • D21D5/18—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force
    • D21D5/24—Purification of the pulp suspension by mechanical means; Apparatus therefor with the aid of centrifugal force in cyclones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C11/00—Accessories, e.g. safety or control devices, not otherwise provided for, e.g. regulators, valves in inlet or overflow ducting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C3/00—Apparatus in which the axial direction of the vortex flow following a screw-thread type line remains unchanged ; Devices in which one of the two discharge ducts returns centrally through the vortex chamber, a reverse-flow vortex being prevented by bulkheads in the central discharge duct
    • B04C3/06—Construction of inlets or outlets to the vortex chamber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/22—Apparatus in which the axial direction of the vortex is reversed with cleaning means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B04C5/24—Multiple arrangement thereof
    • B04C5/28—Multiple arrangement thereof for parallel flow

Definitions

  • Centrifugal cleaners have been employed for many years in the paper industry for removing small particles of higher specific gravity than paper fibers from slurries of paper making fiber, especially waste paper stocks.
  • centrifugal cleaners used for that purpose in what is hereinafter referred to as "conventional centrifugal cleaning technique," the discharge outlet at the apex (tip) of the cylindrical-conical vessel is relatively small in comparison with the inlet and accepts outlets, e.g. 3.2 mm (1/8 inch) in diameter as compared with 13.4 mm (5/8 inch) diameters for the other two ports in a conventional cleaner 7.62 cm (3 inches) in diameter.
  • the reject discharge through the apex outlet is correspondingly small in comparison with the accepts flow, e.g. 3% and 97% by volume respectively.
  • centrifugal cleaners In comparatively recent years, there has been an increasing use of centrifugal cleaners to separate good paper fibers from contaminants of closely similar or lower specific gravity such that they cannot be readily separated by conventional centrifugal cleaning technique.
  • cleaners for such "reverse" centrifugal cleaning have been made by modifying the construction and/or operation of a conventional cleaner to provide operating conditions which cause the good fiber to be discharged through the apex outlet as the accepts flow while the lights are discharged as reject through the base (top) outlet which is the accepts outlet in conventional centrifugal cleaning.
  • the preamble of claim 1 is known from US-A-4 155 839 insofar as it discloses system for separating paper making fibers from light contaminants of similar and lower specific gravities, comprising
  • a cyclone separator comprising an internally conical vessel having an inlet port adjacent the base end thereof and the apex end being open, housing means defining a chamber surrounding said open apex end, an outlet tube extending through said chamber and into the open apex end.
  • a cyclone type cleaner comprising an internally conical vessel having an inlet at the base thereof and the apex end being open, a housing defining a chamber surrounding the open apex and an outlet tube extending through the chamber into the open end, the tube being adjustable axially of the vessel.
  • An object of the invention is to provide an improved centrifugal cleaner particularly adapted for reverse centrifugal cleaning wherein both of the discharge ports, for the two fractions into which the cleaner separates the feed flow, are located adjacent the apex end of the cleaner, so that there is no reversal of flow within the cleaner as in past practice for both conventional and reverse cleaning.
  • the invention also includes a centrifugal cleaner having the features acknowledged as known from US-A-4 155 839 and being characterised by
  • the invention further includes a multiple centrifugal cleaner assembly having the features acknowledged as known from GB-A-1 349 465 characterised by:
  • FIG. 1 A typical reverse centrifugal cleaner indicated generally at 10 is shown in Fig. 1 is housed in a casing 11 which has its interior divided by partitions 12 and 13 into a supply orfeed chamber 15 at one end of the casing 11, a reject chamber 16 at the other end of the casing, and an accepts chamber 17 located intermediate the chambers 15 and 16, each of these chambers being provided with its own port 20, 21 and 22, respectively.
  • the cleaner 10 comprises a main tubular vessel 25 the interior of which is cylindrical over a portion of its length and frusto-conical throughout its remaining portion.
  • a housing 26 is threaded on the smaller end of the vessel 25, and a tubular tip piece 27 is secured within the housing 26 by a retainer nut 28 as shown.
  • the cylindrical bore 29 within the tip piece 27 forms a continuation of the interior of housing 25 which leads to the discharge port 30.
  • the housing 26 has one or more radially or tangentially arranged ports 31 therethrough which provide a total flow area larger than that of the port 30 leading into the interior of the reject chamber 16.
  • the lower end of the housing 26 is closed by a threaded cap 33 which extends through an opening in the end wall 34 of the casing 11 and clamps the casing wall againstthe end of housing 26 to the casing wall.
  • the base end of the vessel 25 is provided with a closure plug 35 which is threaded into the end of the vessel 25 and also clamps the partition 13 between itself and the vessel 25.
  • a helical groove 40 on the outer surface of the plug 35 forms the inlet port to the interior of the cleaner vessel 25, the spiral configuration of this groove assuring that stock to be cleaned will be delivered from the interior of the feed chamber 15 to the interior of the vessel 25 with a substantial circumferential flow component.
  • the plug 35 is otherwise solid, but it includes a cylindrical extension 41 on its inner end which acts in part as a vortex finder but more particularly as a stabilizer for the air core which forms during operation of the cleaner.
  • the groove 40 may be duplicated around the periphery of plug 35 to increase the effective inlet port size as needed.
  • the cleaner 10 is provided with one or more outlet ports 44 at the lower end of the frusto-conical portion of vessel 25.
  • the outlet ports 44 are preferably arranged tangentially of the vessel 25, in the same direction as the circulatory movement of stock within the vessel, and these ports lead into the chamber 17 within the casing 11.
  • the tip piece 27 includes a cylindrical extension 45 which projects upstream therefrom into the interior of the vessel 25 sufficiently far so that it at least radially overlies the outlet port or ports 44 and thus serves as a baffle preventing direct flow therefrom to the interior of tip piece 27 and the outlet port 30, and the upstream end of the extension 45 thus effectively is the apex outlet port of the vessel 25.
  • the inlet construction shown in Fig. 1 has special advantages in that it assures that all stock entering the cleaner will continue to flow with a substantial component lengthwise of the cleaner, rather than having some heavy particles tend to orbit the inlet end of the cleaner and thereby wear away its inner wall surface.
  • the invention can be practiced, however, with the alternative inlet construction shown in Fig. 2, which is essentially the same as in the above noted patent No. 4,155,839.
  • the slurry to be cleaned is delivered to the supply chamber 15 at the appropriate pressure to cause it to enter the inlet port 40 or 40' at the desired flow rate and velocity as described in patent No. 4,155,839, to develop within the vessel 25 centrifugal force conditions causing vortical separation of the slurry into an outer fraction containing the large majority of the paper fibers, an inner fraction containing the large majority of light contaminant particles, and commonly also an innermost air core.
  • the outer fraction will travel down the frusto-conical portion of the interior of vessel 25 until it reaches the discharge port or ports 44, and it will exit through those ports to the accepts discharge chamber 17 and its outlet port 22.
  • the inner fraction will enter the upstream end of the extension 45 and travel therethrough and through the interior of the tip piece 27 and the outlet port 30 to the reject discharge chamber 16 and its port 21.
  • Separation of the heavy and light fractions which form within the cleaner as they discharge therefrom is readily controlled by regulating the respective discharge flows from the chambers 16 and 17, by means such as valves 50 and 51 on the lines 52 and 53 leading from the ports 21 and 22. Determination of the proper flow splits from the two discharge chambers will usually involve some experimentation, depending upon the nature of the feed stock, the feed flow rate and the feed pressure, and satisfactory results have been obtained under test conditions with this split varied from approximately equal flows from both discharge chambers to approximately 90% from the accepts chamber 17 and 10% from the reject chamber 16.
  • test runs were made with a cleaner constructed as shown in Fig. 2 wherein the inlet port 40' had a flow area of 4.03cm 2 (0.625.sq.in.), the minimum flow area of the apex outlet port was 5.06cm 2 (0.785 sq.in.) and there were two outlet ports 40 each of a flow area of approximately 1.6cm 2 (0.25 sq.in).
  • the feed flow rate was 189 litres/minute (50 gallons/minute) at 2.1 kg/cm (30 p.s.i.g)
  • satisfactory results were obtained with flows from the discharge chambers 16 and 17 of approximately 98.4 and 90.8 litres/min.
  • the invention has also been tested with a cleaner constructed as shown in Fig.1 wherein the inlet port flow area was 4.03 cm 2 (0.625 sq.in), the minimum flow area of the apex port was 1.97 CM 2 (0.306 sq.in), and the accepts port 40 was rectangular, similarly to the inlet port 40' in Fig. 2, with dimensions of 3.81 cm x 9.5 mm (1.5 inches x 3/8 in.) and a flow area of 3.07 cm 2 (0.47 sq.in).
  • the invention is especially applicable to cleaner assemblies of the canister type, as illustrated in Fig. 3, wherein the canister 60 has internal walls 61 and 62 dividing its interior into a central chamber 63 and opposite end chambers 64 and 65.
  • Multiple cleaners 10 of the construction described in connection with Fig. 1 are shown as mounted within the canister 60, with the interior walls 61 and 62 and end wall 66 providing the same mounting and partitioning functions as the partitions 12 and 13 and end wall 34 in Fig. 1.
  • a canister cleaner assembly of the invention as shown in Fig. 3 is the same as already described in connection with Fig. 1.
  • the chamber 64 serves as the feed chamber and is provided with an appropriately located port for receiving the inletflow of feed stock, and the chambers 63 and 65 become the reject and accept chambers as described in connection with the chambers 16 and 17 in Fig. 1.
  • the canister cleaner of Fig. 3 can in effect can be made double-ended by doubling the length of the canister, installing a second set of partition walls and cleaners opposite the set shown in Fig. 3, and then using chamber 64 as the feed chamber for both sets of cleaners.
  • the modified cleaner 100 in accordance with the invention shown in Fig. 4 is mounted in a canister casing 110 provided with an end head 111 and having its interior divided by a partition 113 into a supply or feed chamber 115 and an accepts (heavies) chamber 117.
  • Each of these chambers is provided with its own port 120 and 121 respectively, but each cleaner 100 has its own outlet port for reject (lights) from the casing 110 provided by a tube 123 as described in more detail hereinafter.
  • the cleaner 100 comprises a main tubular vessel 125 of essentially the same construction as the vessel 25 except that it is extended somewhat longer at its apex end, and it has no outlet port in its side wall.
  • the tip housing 126 is threaded on the smaller end of the vessel 125 in clamping relation with the partition 113, and it also serves as a mounting for the tube 123, the bore 130 of which forms the discharge port for lights from the cleaner.
  • a guide member 131 within the housing 126 has an axial bore 132 sized to receive the tube 123 freely therein. The outer portion of the tube 123 passes through a center bore in the threaded cap 133 which clamps the end of the housing 126 to the end head 111 of the casing 110.
  • the bore 132 of the part 131 is provided with a circumferential groove for receiving an O-ring 135 sized to form a seal between the.bore 132 and the tube 123.
  • releasable locking means are provided between the tube 123 and the part 131, namely bayonet locking means comprising radial projections 136 on the tube 123 which are sized to cooperate in locking relation with the slotted and grooved portions at the outer end of the part 131.
  • the projections 136 will seat on the bottoms of those slots, and then a quarter-turn of the tube will effect locking engagement of the projections 136 in the grooves 138.
  • the feed inlet port to the interior of the vessel 125 is provided by one or more tangential slots 140 of rectangular shape in the wall of the vessel adjacent its base end, which is closed by a threaded plug 142.
  • An extension 141 on the plug 142 acts both as a vortex finder and as a stabilizer for the air core which forms during operation of the cleaner, and it may be solid as shown or of the hollow cylindrical form shown in Figs. 1 and 3.
  • the locking projections 136 on the tube 123 are in predetermined spaced relation with the inner end of the tube so that when they are locked in the grooves 138, the inner end of the tube is located at or within the apex end of the vessel 125 so that it defines an annular discharge port 144 from the interior of the vessel 125 into the annular chamber 145 surrounding the tube 123 on the upstream side of the part 131.
  • a plurality of ports 146 in the wall of the housing 126 lead from this chamber 145 into the accepts chamber 117 and then to the port 121.
  • the operation of the cleaner assembly shown in Fig. 4 is essentially the same as described in connection with Fig. 1, with the centrifugal force conditions developed within the vessel 125 causing vortical separation of the feed slurry into an outer fraction which is discharged through the annular port 144 and an inner fraction which is discharged through the tube 123.
  • the major advantage provided by this cleaner is that in the event of plugging of the annular port 144 by solid material, virtually immediate relief of the blocking can be effected by manually retracting the tube 123 from outside the casing 110 for a long enough interval for the flow to clear the apex end of the vessel 125, and then returning the tube 123 to its operating position established by the locked relation of the parts 136-138.
  • each tube 123 projects to the outside of the canister, and each is provided with its own flexible tubing 150 for conducting the reject flow therefrom to a common collection receiver.
  • each tube has its tubing 150 secured thereto by a clamp 151 which also acts as a handle by which the associated tube 123 can be twisted to unlocked position, temporarily retracted, and then returned and locked in its operative position.
  • the inner diameter of the cylindrical portion of the vessel 125 is 7.62 cm (three inches)
  • the inner diameter of the apex end of the vessel is 2.9 cm (1.14 inches)
  • the tube 123 has and outer diameter of 1.59 cm (0.625 inch) and an inner diameter of 1.27 cm (0.500 inch), and it is preferably beveled at its upstream end to minimize turbulence in the flow therepast.
  • the space between the inner end of the cap 133 and the downstream end of the member 131 provides for at least 2.54 cm (one inch) of axial movement of the tube 123 to assure complete opening of the apex end of the vessel 125 when the tube is retracted.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Cyclones (AREA)
  • Paper (AREA)
EP84304812A 1983-07-14 1984-07-13 Centrifugal cleaning of paper making stock Expired EP0132141B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US51357983A 1983-07-14 1983-07-14
US513579 1983-07-14

Publications (3)

Publication Number Publication Date
EP0132141A2 EP0132141A2 (en) 1985-01-23
EP0132141A3 EP0132141A3 (en) 1985-07-17
EP0132141B1 true EP0132141B1 (en) 1988-07-13

Family

ID=24043860

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84304812A Expired EP0132141B1 (en) 1983-07-14 1984-07-13 Centrifugal cleaning of paper making stock

Country Status (8)

Country Link
EP (1) EP0132141B1 (fi)
JP (1) JPS6039495A (fi)
AU (1) AU3034884A (fi)
BR (1) BR8403495A (fi)
CA (1) CA1232587A (fi)
DE (1) DE3472692D1 (fi)
ES (1) ES8602999A1 (fi)
FI (1) FI74059C (fi)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4605495A (en) * 1984-03-19 1986-08-12 Bird Machine Company, Inc. Hydrocyclone separator apparatus
CA1328629C (en) * 1987-09-05 1994-04-19 Peter Gregory Michaluk Separator
JP4881977B2 (ja) * 2009-07-24 2012-02-22 ヤマホ工業株式会社 インラインストレーナ

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE111887C1 (fi) *
DE953601C (de) * 1955-10-15 1956-12-06 Krauss Maffei Ag Zyklon
EP0058484A2 (en) * 1981-02-14 1982-08-25 Beloit Corporation Improvements in and relating to cyclone separators

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE361268B (fi) * 1972-03-16 1973-10-29 K Robinson
CA941753A (en) * 1970-09-28 1974-02-12 Elast-O-Cor Products And Engineering Limited Hydrocyclones
JPS531655Y2 (fi) * 1972-08-18 1978-01-18
US4155839A (en) * 1977-11-28 1979-05-22 The Black Clawson Company Reverse centrifugal cleaning of paper making stock
SE411104B (sv) * 1978-02-22 1979-12-03 Celleco Ab Dubbelmantlad hydrocyklonseparator med leckage indikerande organ

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE111887C1 (fi) *
DE953601C (de) * 1955-10-15 1956-12-06 Krauss Maffei Ag Zyklon
EP0058484A2 (en) * 1981-02-14 1982-08-25 Beloit Corporation Improvements in and relating to cyclone separators

Also Published As

Publication number Publication date
CA1232587A (en) 1988-02-09
EP0132141A3 (en) 1985-07-17
FI74059B (fi) 1987-08-31
DE3472692D1 (en) 1988-08-18
JPH059559B2 (fi) 1993-02-05
ES534312A0 (es) 1985-12-01
FI74059C (fi) 1987-12-10
JPS6039495A (ja) 1985-03-01
ES8602999A1 (es) 1985-12-01
FI842839A (fi) 1985-01-15
BR8403495A (pt) 1985-06-25
FI842839A0 (fi) 1984-07-13
AU3034884A (en) 1985-01-17
EP0132141A2 (en) 1985-01-23

Similar Documents

Publication Publication Date Title
US3684093A (en) Method and apparatus for separating particles from particle-laden fluid
EP0068809B1 (en) Cyclone separator
EP0017481B1 (en) Self-sealing valve assembly to facilitate unplugging of a centrifugal cleaner
EP0493950A2 (en) Centrifugal cleaner
CA1288731C (en) Fiber recovery elutriating hydrocyclone
US4711720A (en) Tangentially staged hydrocyclones
CA1197478A (en) Cyclone separators
EP0368849B1 (en) Cyclone separator
US4927536A (en) Hydrocyclone separation system
US4309283A (en) Hydrocyclone
US4564443A (en) Reverse centrifugal cleaning of paper making stock
EP0132141B1 (en) Centrifugal cleaning of paper making stock
EP0360357A2 (en) Apparatus for separating solid particles from a fluid
GB2263652A (en) Hydrocyclone
US5133861A (en) Hydricyclone separator with turbulence shield
US3543932A (en) Vortex chamber reject control
US11779937B1 (en) Method and apparatus for hydrocyclone
CA1222220A (en) Reverse centrifugal cleaning of paper making stock
JP3773536B2 (ja) 滞在時間の長い逆ハイドロサイクロンクリーナ
EP0522686A2 (en) Hydrocyclone separators for separating less and more dense liquids
US4451358A (en) Noncircular rejects outlet for cyclone separator
AU598505B2 (en) Cyclone separator
CA2235011C (en) Hydrocyclone separator
EP0080036A2 (en) Noncircular rejects outlet for cyclone separator
SU889049A1 (ru) Сепаратор

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): DE FR GB IT SE

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Designated state(s): DE FR GB IT SE

17P Request for examination filed

Effective date: 19860115

17Q First examination report despatched

Effective date: 19870113

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT SE

ITF It: translation for a ep patent filed
REF Corresponds to:

Ref document number: 3472692

Country of ref document: DE

Date of ref document: 19880818

RAP2 Party data changed (patent owner data changed or rights of a patent transferred)

Owner name: BLACK CLAWSON (FRANCE) S.A.

Owner name: THE BLACK CLAWSON COMPANY

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

REG Reference to a national code

Ref country code: FR

Ref legal event code: AR

REG Reference to a national code

Ref country code: FR

Ref legal event code: BR

ITTA It: last paid annual fee
EAL Se: european patent in force in sweden

Ref document number: 84304812.5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 19970723

Year of fee payment: 14

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 19980713

Year of fee payment: 15

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19980714

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 19980724

Year of fee payment: 15

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19980725

Year of fee payment: 15

EUG Se: european patent has lapsed

Ref document number: 84304812.5

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19990713

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 19990713

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000331

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20000503

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST