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WO2024156780A1 - Utilisation d'un guide-fil pour une machine à tricoter pour tamis en métal noble - Google Patents

Utilisation d'un guide-fil pour une machine à tricoter pour tamis en métal noble Download PDF

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Publication number
WO2024156780A1
WO2024156780A1 PCT/EP2024/051705 EP2024051705W WO2024156780A1 WO 2024156780 A1 WO2024156780 A1 WO 2024156780A1 EP 2024051705 W EP2024051705 W EP 2024051705W WO 2024156780 A1 WO2024156780 A1 WO 2024156780A1
Authority
WO
WIPO (PCT)
Prior art keywords
precious metal
use according
thread guide
metal wire
deflection
Prior art date
Application number
PCT/EP2024/051705
Other languages
German (de)
English (en)
Inventor
Dirk Born
Dieter Prasch
Sait OEZTAS
Original Assignee
Umicore Ag & Co. Kg
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 Umicore Ag & Co. Kg filed Critical Umicore Ag & Co. Kg
Publication of WO2024156780A1 publication Critical patent/WO2024156780A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04B—KNITTING
    • D04B15/00—Details of, or auxiliary devices incorporated in, weft knitting machines, restricted to machines of this kind
    • D04B15/38—Devices for supplying, feeding, or guiding threads to needles
    • D04B15/54—Thread guides
    • D04B15/56—Thread guides for flat-bed knitting machines

Definitions

  • the invention relates to the use of a thread guide for a knitting machine for knitting precious metal nets for the catalytic oxidation of ammonia, in particular for the oxidation to NO, as used for nitric acid production.
  • precious metal catalysts in the form of gas-permeable spatial structures on or in which the reaction takes place.
  • Precious metal nets in the form of woven fabrics (DE4028916 C2) or knitted fabrics (EP0364153 B1, DE4206199 C1) made of fine precious metal wires have been used for some time.
  • the catalyst nets are usually arranged in a flow reactor in a plane perpendicular to the flow direction of the gas mixture. Conical arrangements are also known. It is advisable to arrange several precious metal nets one behind the other and combine them to form a net stack.
  • FIG. 1 shows a schematic representation of the reactor with the mesh stack installed in it, using the example of catalytic ammonia oxidation (Ostwald process), the function of which is described below:
  • the mesh stack (3) is arranged in a plane perpendicular to the flow direction.
  • the mesh stack consists of several catalyst meshes (4) arranged one behind the other on the inlet side and downstream separation and getter meshes (5). This mesh stack is held in position by clamping.
  • reaction gas (ammonia-air oxygen mixture with an ammonia content of 9 - 13 vol.%) (6) flows through the mesh stack (3) under atmospheric or elevated pressure, whereby the gas mixture is ignited in the inlet area and the combustion reaction to nitrogen monoxide (NO) and water covers the entire reaction zone (2):
  • the NO2 in turn reacts with water in a downstream absorption to form nitric acid, which is used in fertilizer production, for example:
  • Precious metal wires made of platinum, rhodium or alloys of these metals with other precious or base metals are used to produce the precious metal nets.
  • Platinum-rhodium or platinum-palladium-rhodium alloys with 88 to 97 wt.% platinum are typical. Platinum is required to achieve the highest possible ammonia conversion, rhodium improves the selectivity to NO, thereby reducing the emission of nitrous oxide, and increases the mechanical strength [G. R. Maxwell: "Synthetic Nitrogen Products - A Practical Guide to the Products and Processes", Springer Science + Business Media, Inc. 2005, page 220], while palladium is used to reduce the precious metal costs by replacing platinum, depending on the precious metal prices.
  • Flat knitting machines are used to knit precious metal nets.
  • the structure of the flat knitting machine is shown in Figure 2.
  • the flat knitting machine has a front (8) and a rear needle bed (9) in which the latch needles (10) are installed.
  • the thread or precious metal wire is fed through a thread guide (13).
  • the description below is limited to knitting precious metal wire.
  • Knitted precious metal nets have a number of advantages over woven precious metal nets, which is why they are preferred in industrial use today.
  • the knitting technique offers the possibility of a high degree of flexibility in terms of knitting patterns, the thickness of the precious metal wire used and the resulting weight per unit area.
  • the precious metal knits can be produced more economically, as the knitting technique requires shorter set-up times than the weaving technique. In particular, this means that precious metal binding in production is significantly reduced.
  • Precious metal nets of any length can be produced on flat knitting machines.
  • the minimum mesh size i.e. the density of the knitted fabric, is limited by the maximum number of latch needles per given width.
  • Gold, silver and the platinum metals are considered precious metals.
  • Catalyst networks are those networks whose catalytic activity is used for the conversion of ammonia with oxygen.
  • Getter nets are the nets that are installed in the reaction gas flow on the outlet side of the catalyst nets in order to capture volatile platinum oxide for recycling by alloying with the palladium of the getter nets and thus minimize platinum loss.
  • the totality of the catalyst and getter nets is referred to as precious metal nets.
  • Separation nets are nets made of high-temperature-resistant steel, which are installed between the precious metal nets to prevent the precious metal nets from sintering together.
  • the mesh stack consists of the catalyst meshes on the inlet side of the mesh stack, and optionally the getter meshes on the outlet side of the mesh stack, as well as the separation meshes, which may be installed between the precious metal meshes.
  • a flow reactor is the reactor that ensures that the reaction gas is passed over the mesh stack installed in it.
  • the knitting process is carried out using the latch needles.
  • a latch needle is required for each wale in a knitted fabric.
  • the precious metal wire is fed to the latch needles via the thread guide. Precise positioning is important so that the latch needles can grip the precious metal wire and no insertion errors occur, which would result in a knitting defect in the product.
  • Needle bed single-bed fabric, double-bed fabric, pile thread:
  • the needle bed is the element of the flat knitting machine over which the latch needles are guided.
  • the flat knitting machine usually has a front and a rear needle bed, on each of which a knitted fabric can be knitted (single-bed fabric). If these two knitted fabrics are knitted together using pile threads during the knitting process, the newly created knitted fabric is a double-bed fabric.
  • a loop is created by connecting two loops.
  • a catch is a loop that is inserted from one needle bed to the opposite needle bed in an R/R weave.
  • the terms 'loop', 'loop' and 'R/R weave' are familiar to those skilled in the art.
  • Row and wale stitches The stitches formed one after the other using the same precious metal wire are collectively referred to as a row of stitches.
  • the parallel rows of stitches are held together by intertwining the stitches of a wale stitch.
  • the precious metal wire is subjected to bending stress and friction.
  • the thread guide (13) which has to feed the precious metal wire to the latch needles (10) in the correct position, places a strain on the precious metal wire, as the precious metal wire is deflected by approximately 90° at the wire outlet via an eyelet and runs over the edge of the eyelet at high speed. This leads to damage to the precious metal wire surface and possibly even to the precious metal wire breaking off and to wear of the thread guide eyelet.
  • precious metal wire is more difficult to hold in position than a textile thread due to its bending stiffness, which can result in insertion errors in the stitch formation process of knitting.
  • the object of the present invention is therefore to reduce the wear of the precious metal wire and the thread guide and to improve the positioning of the precious metal wire for gripping by the latch needles.
  • precious metal wire is therefore always mentioned as the starting material. If necessary, steel wire or yarn can also be knitted.
  • the task is solved by using a thread guide for a
  • Figure 3 shows an example of a thread guide according to the invention.
  • the deflection rollers (14) can be clearly seen.
  • a pulley consists of a wheel that is mounted on an axle with as little friction as possible and over which a precious metal wire is guided. This minimizes the friction between the precious metal wire and the pulley, which minimizes wear on the precious metal wire and thus reduces the risk of the wire breaking.
  • the thread guide is moved back and forth above the latch needles so that the exit direction of the precious metal wire changes by 180° at each end of the knitting bed used.
  • the thread guide is preferably equipped with two deflection rollers at the end, the axes of which run parallel, with the precious metal wire exiting the thread guide between the deflection rollers. The precious metal wire is thus guided over a deflection roller in both directions of movement without the thread guide having to be rotated.
  • the deflection roller should be able to rotate as easily and quickly as possible in order to keep the friction between the precious metal wire and the deflection roller as low as possible.
  • One variant of the thread guide is therefore equipped with deflection rollers with plain bearing bushes. Teflon or bronze are suitable as plain bearing bush materials, as they run with little friction and enable a long service life. Plain bearings have the advantage over roller bearings that they are less sensitive to impacts and vibrations and less susceptible to dirt. In addition, their construction is very simple.
  • the deflection rollers are preferably equipped with roller bearings, as these are technically more complex but can further reduce the friction between the precious metal wire and the deflection roller.
  • Ball bearings are particularly preferred as they keep the bearings stable in the axial direction and can also reduce the friction generated by the axial forces acting on the deflection roller.
  • Steel is particularly suitable as a rolling bearing material because it is resistant to wear.
  • steel is also very suitable for the deflection pulley.
  • the deflection pulley can also be the outer ring of the rolling bearing.
  • the deflection roller or the deflection rollers are guide rollers which have a radial groove in the middle of their outer running surface, which prevents the wire or thread from slipping off the roller. Slipping of the Wire requires an interruption of the knitting process and should be avoided at all costs.
  • This groove preferably has a width of 0.2 to 2 mm.
  • the groove has a round cross-section with a radius of curvature of this cross-section that is greater than the width of the groove. This prevents damage to the wire surface by the edges running on both sides of the groove, thus preventing potential wire breakage.
  • the wire is preferably installed in the flat knitting machine in such a way that the axes of the deflection rollers are arranged at right angles to the plane of movement of the thread guide. This ensures that the precious metal wire always runs at right angles to the axis of the deflection roller and this arrangement minimizes the friction of the precious metal wire with the deflection roller and the risk of slipping off the deflection roller.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Knitting Of Fabric (AREA)

Abstract

L'invention concerne l'utilisation d'un guide-fil (13) pour une machine à tricoter rectiligne destinée à tricoter du fil en métal noble, l'extrémité du guide-fil (13) étant équipée d'un ou de plusieurs galets (14) de déviation par l'intermédiaire desquels le fil en métal noble est dévié.
PCT/EP2024/051705 2023-01-26 2024-01-25 Utilisation d'un guide-fil pour une machine à tricoter pour tamis en métal noble WO2024156780A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP23153366.2 2023-01-26
EP23153366.2A EP4407083A1 (fr) 2023-01-26 2023-01-26 Guide-fil pour machine à tricoter pour des réseaux de métaux précieux

Publications (1)

Publication Number Publication Date
WO2024156780A1 true WO2024156780A1 (fr) 2024-08-02

Family

ID=85122318

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2024/051705 WO2024156780A1 (fr) 2023-01-26 2024-01-25 Utilisation d'un guide-fil pour une machine à tricoter pour tamis en métal noble

Country Status (2)

Country Link
EP (1) EP4407083A1 (fr)
WO (1) WO2024156780A1 (fr)

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE30190C (de) * 1884-03-05 1885-01-28 Prinz A. THURN-TAXIS und R. Graf WESTPHALEN in Wien Machine zum Verstricken von Metalldraht
DE1236712B (de) * 1961-02-09 1967-03-16 Scott & Williams Inc Fadenfuehrerbruecke fuer Rundstrickmaschinen
DE7403104U (de) * 1974-01-30 1977-07-14 Skf Kugellagerfabriken Gmbh, 8720 Schweinfurt Rollenlagerung in textilmaschinen
EP0364153B1 (fr) 1988-10-12 1992-03-04 Johnson Matthey Public Limited Company Tissu métallique
DE4206199C1 (fr) 1991-03-16 1992-11-12 Degussa Ag, 6000 Frankfurt, De
DE4028916C2 (de) 1990-09-12 1994-05-05 Heraeus Gmbh W C Aus Draht gewebtes Katalysator-Netz aus den Edelmetall-Legierungen Platin/Rhodium oder Platin/Rhodium/Palladium
DE29515458U1 (de) * 1995-09-28 1997-02-06 Palitex Project-Company GmbH, 47804 Krefeld Fadenführungsrolle für Textilmaschinen
DE19642051A1 (de) * 1995-10-12 1997-04-17 Du Pont Verfahren und Vorrichtung zum Stricken oder Wirken von Maschenware aus unelastischem Garn und blankem elastomerem Garn und Konstruktion einer abgepassten Maschenware
EP1358010B2 (fr) 2001-02-08 2008-07-23 Umicore AG & Co. KG Gazes catalytiques tridimensionnelles tricotees en deux couches

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE30190C (de) * 1884-03-05 1885-01-28 Prinz A. THURN-TAXIS und R. Graf WESTPHALEN in Wien Machine zum Verstricken von Metalldraht
DE1236712B (de) * 1961-02-09 1967-03-16 Scott & Williams Inc Fadenfuehrerbruecke fuer Rundstrickmaschinen
DE7403104U (de) * 1974-01-30 1977-07-14 Skf Kugellagerfabriken Gmbh, 8720 Schweinfurt Rollenlagerung in textilmaschinen
EP0364153B1 (fr) 1988-10-12 1992-03-04 Johnson Matthey Public Limited Company Tissu métallique
DE4028916C2 (de) 1990-09-12 1994-05-05 Heraeus Gmbh W C Aus Draht gewebtes Katalysator-Netz aus den Edelmetall-Legierungen Platin/Rhodium oder Platin/Rhodium/Palladium
DE4206199C1 (fr) 1991-03-16 1992-11-12 Degussa Ag, 6000 Frankfurt, De
DE29515458U1 (de) * 1995-09-28 1997-02-06 Palitex Project-Company GmbH, 47804 Krefeld Fadenführungsrolle für Textilmaschinen
DE19642051A1 (de) * 1995-10-12 1997-04-17 Du Pont Verfahren und Vorrichtung zum Stricken oder Wirken von Maschenware aus unelastischem Garn und blankem elastomerem Garn und Konstruktion einer abgepassten Maschenware
EP1358010B2 (fr) 2001-02-08 2008-07-23 Umicore AG & Co. KG Gazes catalytiques tridimensionnelles tricotees en deux couches

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
ANDREAS JESSPETER WASSERSCHEID: "Chemical Technology", 2013, WILEY-VCH VERLAG
G. R. MAXWELL: "Synthetic Nitrogen Products - A Practical Guide to the Products and Processes", 2005, SPRINGER SCIENCE + BUSINESS MEDIA, INC

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