EP3054235A1 - Procédé de revêtement pour réservoirs métalliques avec échangeur de chaleur à bobine - Google Patents

Procédé de revêtement pour réservoirs métalliques avec échangeur de chaleur à bobine Download PDF

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Publication number
EP3054235A1
EP3054235A1 EP16000284.6A EP16000284A EP3054235A1 EP 3054235 A1 EP3054235 A1 EP 3054235A1 EP 16000284 A EP16000284 A EP 16000284A EP 3054235 A1 EP3054235 A1 EP 3054235A1
Authority
EP
European Patent Office
Prior art keywords
powder
coil
coating method
previous
electrostatic
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.)
Withdrawn
Application number
EP16000284.6A
Other languages
German (de)
English (en)
Inventor
Stefano Standardi
Fausto Betti
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.)
Merloni Termosanitari SpA
Ariston SpA
Original Assignee
Merloni Termosanitari SpA
Ariston Thermo SpA
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 Merloni Termosanitari SpA, Ariston Thermo SpA filed Critical Merloni Termosanitari SpA
Publication of EP3054235A1 publication Critical patent/EP3054235A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
    • F24H1/18—Water-storage heaters
    • F24H1/181—Construction of the tank
    • F24H1/183—Inner linings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/08—Plant for applying liquids or other fluent materials to objects
    • B05B5/12—Plant for applying liquids or other fluent materials to objects specially adapted for coating the interior of hollow bodies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
    • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
    • B05D1/06—Applying particulate materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2202/00—Metallic substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/22—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes
    • B05D7/227—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to internal surfaces, e.g. of tubes of containers, cans or the like
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23D—ENAMELLING OF, OR APPLYING A VITREOUS LAYER TO, METALS
    • C23D5/00—Coating with enamels or vitreous layers

Definitions

  • the object of the present invention is an electrostatic powder coating method suitable for metal tanks intended to contain water or similar fluids and internally provided with one, or more, coil-wound heat exchangers also metallic and constrained by welding to the walls of the same tank.
  • the method refers to the electrostatic deposition of enamel powder of the vitreous type, said coating consisting more correctly in enamelling.
  • composition of the powder is a very important factor in order to ensure both its adherence with the metal substrate and the duration of the coating over time.
  • the enamels for a correct application, must have preferred distributions of various granulometries and a suitable electrostatic charge otherwise known undesirable situations are produced such as the "Faraday cage” effect or the phenomenon of "back ionization”; phenomena that negatively affects the result of the enamelling.
  • this requires a distribution of enamel free of gaps or local accumulations of powder, with thickness comprised between a lower limit, below which the layer applied cannot be considered as protective, and an upper limit, above which enamel gaps are very likely.
  • a thickness of enamel comprised between 180 and 500 ⁇ m is considered as adequate for the purposes.
  • the present invention aims to provide a solution or at least clear improvements, that is the enamelling of steel tanks provided with one or more coil-wound exchangers is particularly difficult due to the need of coating with enamel the walls supporting the coil, which the latter keeps for a good part shaded with respect to the lance and due to the fact that the turns of the coil, side by side, make a uniform application difficult, presumably due to undesired "Faraday cage” effects.
  • An object of the present invention is to provide a method for the application of electrostatic powder enamelling in steel tanks provided with an inner heating coil also of steel that ensures a coat of enamel of a thickness comprised between the lower and upper limits required on the entire inner surface.
  • a further object of the present invention is that of providing a method that reaches the previous object through steps of a reduced number and simpler than the method currently known.
  • Figure 1 shows, of tank 1, the covers 2 joined by means of welding seams 3 to the cylindrical wall 4 (called in jargon "shell”); a single coil 5, welded to said shell 4; the water inlet and outlet tubes 6 and 7 respectively, the opening 8 intended for maintenance inspections, the optional insertion of temperature control and heating means and, as regards the present invention, the insertion of the lance for dispensing enamel powders to be applied electrostatically (not shown).
  • tank 1 is not necessarily to scale; in particular the turns of coil 5 may actually be thicker than as shown.
  • the tank 1 is shown arranged with vertical axis, with the opening 8 below, which is the position that it is made to take during the enamel application process; such a position is not necessarily that taken in operating conditions.
  • Both the known methods and the method according to the invention provide multiple steps each of which consisting of one or more upwards and downwards passes of the powder dispensing lance in predetermined stretches, the number of passes depending on the quantity of powder that can be deposited in each of them and, ultimately, on the thickness of enamel that is desired to be achieved.
  • tank 1 there are indicated some zones identified by corresponding vertical stretches and horizontal planes of separation.
  • the total height Hscb consists of, from top to bottom, a first stretch Hc that goes from the top of the upper cover 2 to the welding seam 3, lying on an upper welding plane ⁇ ; an intermediate stretch D follows that goes from said welding plane ⁇ to an upper plane ⁇ where coil 5 begins; the central stretch Hsp follows that goes from said upper plane ⁇ to a subsequent lower plane P where coil 5 ends; then there is another intermediate stretch D from said lower plane ⁇ to a lower plane ⁇ where the welding seam 3 of the shell 4 to the lower cover 2 lies.
  • critical zones are the zones of the welding seams 3 (zones from just above to just below the planes ⁇ ), due to the rather rough surface thereof, and the end turns of the coil 5 (the higher and lower turns).
  • Figs. 2 (a) to 2 (f) The method substantially used up to now is shown in Figs. 2 (a) to 2 (f) that illustrate each one of the consecutive four to six steps provided.
  • the first step consists in applying powder exclusively in the stretch Hsp occupied by the coil 5 (that is, in the space comprised between the two coil 5 start/end planes ⁇ ).
  • the second step consists in applying powder in a stretch H.sup that goes from a centre plane ⁇ to about half the height of the coil 5 up to an end plane ⁇ inside the upper cover 2 and sufficiently close to the top of the same cover 2 to allow powders to cover it entirely. Therefore, this step has the purpose of depositing additional powder on the upper turns and covering entirely the interior of the cover 2.
  • the third step geometrically symmetrical to the previous one, consists in applying powder in a stretch H.inf that goes from the same centre plane ⁇ up to an end plane ⁇ sufficiently inside the lower cover 2 to allow the entire coating with the powders.
  • a fourth and fifth step consisting, respectively, in the further application of powder in the stretches D1 and D2 corresponding to the zones of the shell 4 free from the coil 5 (zones comprised, at the top and bottom, between the planes ⁇ and ⁇ ). These are intended to thicken the enamel in the critical zones (welding seams 3 and end turns of the coil 5).
  • the last step consists in passing again the entire tank 1 for a stretch that goes from the interior of the upper cover 2 to the interior of the lower cover 2 (that is, from the one to the other end plane ⁇ ).
  • the powder application method according to the invention has solved such problems by providing the following simple one or more steps.
  • the method according to the invention provides, in the preferred variant, the following three steps and preferably in the order in which they will now be listed.
  • a main step consists in applying powder in the stretch H1 comprised between two limit planes ⁇ which are planes spaced from coil 5 start/end planes ⁇ only by the amount necessary to ensure that the lance is able to apply powder on the entire surface of the coil 5, including the upper and lower surfaces, respectively, of the outermost turns.
  • said limit planes ⁇ are spaced from coil 5 start/end planes ⁇ by a distance substantially equal to around 30 mm; said measure allows an uniform and complete deposition of the powder on the surface of the coil.
  • a complementary step consists in applying powder in the stretch H2 comprised between the upper limit plane ⁇ and the interior of the upper cover 2 up to the upper end plane ⁇ as defined above.
  • said upper end plane ⁇ is spaced from the top of the upper cover 2 by around 20 mm.
  • a further complementary step consists in applying powder in the stretch H3 comprised between the lower limit plane ⁇ and the interior of the lower cover 2 up to the lower end plane ⁇ as defined above.
  • said lower limit plane ⁇ is spaced from the bottom of the lower cover 2 by around 40 mm.
  • the lower limit plane ⁇ is more spaced from the lower cup 2 in respect of the similar distance between the upper end plane ⁇ and the top of the upper cover 2, since the powder falls by gravity and is deposited uniformly on the surface of said lower cup 2.
  • the method according to the invention provides a main step (that illustrated in Fig. 3 (a) ) in which the powder dispensing lance runs entirely through the stretch H1 concerning the coil 5, with a margin above and below the same coil 5 just sufficient to ensure the coating with powder of the entire coil 5.
  • said margin is substantially equal to around 30 mm above and below the coil 5.
  • steps in which it is avoided depositing powder on the coil 5; that is, steps, in which the lance does not dispense powder on that stretch H1 in which it has already previously operated.
  • the complementary steps in which the lance does not dispense powder in the stretch H1 are only optional and not mandatory because the main step, although only the stretch H1 has been processed, might also be sufficient to coat satisfactorily with powder also the entire inner surface of one or both covers 2, if these are sufficiently compressed or the coil 5 comes sufficiently close to them.
  • a feature of the method according to the invention is that no step substantially provides, except unavoidable slight overlaps to the ends of each stretch H1, H2 and H3 of application, to deposit powder where it has already been deposited in an earlier step.
  • the invention which has been illustrated for simplicity with reference to a tank 1 provided with a single coil 5, can now be clearly generalized to a tank 1 provided with one or more coils, specifying that the method according to the invention provides
  • the one or more main steps and any complementary steps follow one another in a particular chronological order, the second ones being able, if necessary, to be put before the first ones.
  • the invention in addition to cylindrical tanks 1 as illustrated, is also suitable for tanks of spherical or ellipsoidal shape provided with coil 5 with axis substantially parallel to the axis according to which it can move, inside, the dispensing lance penetrating through the opening 8.
  • tanks of such geometrical shapes make it possible steps in which the powder dispensing lance runs entirely through a stretch H1 as defined above and any further steps in which such stretch H1 is ignored by the lance.
  • the method easily allows a thickness of vitreous enamel comprised between 180 and 500 ⁇ m as generally desired.
  • the method is perfectly usable for the electrostatic application of any powder, also of a polymeric nature where an excessive thickness cannot affect the reliability of the corrosion protection but nevertheless constitute a waste of material.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrostatic Spraying Apparatus (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
EP16000284.6A 2015-02-09 2016-02-04 Procédé de revêtement pour réservoirs métalliques avec échangeur de chaleur à bobine Withdrawn EP3054235A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
ITAN20150017 2015-02-09

Publications (1)

Publication Number Publication Date
EP3054235A1 true EP3054235A1 (fr) 2016-08-10

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Family Applications (1)

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EP16000284.6A Withdrawn EP3054235A1 (fr) 2015-02-09 2016-02-04 Procédé de revêtement pour réservoirs métalliques avec échangeur de chaleur à bobine

Country Status (2)

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EP (1) EP3054235A1 (fr)
CN (1) CN105855082B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3839099A4 (fr) * 2019-10-25 2022-01-26 Sohome Houseware (Nanjing) Co., Ltd Procédé de fabrication de récipient en émail et récipient en émail

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3207358A (en) * 1961-07-27 1965-09-21 Gen Electric Water storage tanks and methods of making the same
DE1812031A1 (de) * 1968-11-30 1970-06-18 Franz Woellhaf Verfahren zum Beschichten mit Kunststoffmaterial von Gegenstaenden,vorzugsweise von voluminoesen Gegenstaenden,und Vorrichtung zur Durchfuehrung des neuen Verfahrens
DE19515425A1 (de) * 1994-04-28 1995-11-02 Vaillant Joh Gmbh & Co Innen emaillierter Speicherbehälter für einen Wasserspeicher
DE202011051419U1 (de) * 2011-09-22 2013-01-08 Frauenthal Deutschland Gmbh Anlage zur Herstellung eines Druckbehälters und damit hergestellter Druckbehälter, insbesondere Druckluftbehälter

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1256235B (it) * 1992-12-23 1995-11-29 Himont Inc Processo per rivestire la superficie interna di contenitori metallici con materiali poliolefinici
DE59403711D1 (de) * 1993-06-05 1997-09-18 Vaillant Joh Gmbh & Co Wasserbehälter und Verfahren zu dessen Herstellung
SG74728A1 (en) * 1998-06-02 2000-08-22 Kuroda Precision Ind Ltd Method for electrostatic coating a metallic cylindrical body
JP5794512B2 (ja) * 2009-11-30 2015-10-14 日本ペイント・サーフケミカルズ株式会社 アルミニウム材製熱交換器の耐食処理方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3207358A (en) * 1961-07-27 1965-09-21 Gen Electric Water storage tanks and methods of making the same
DE1812031A1 (de) * 1968-11-30 1970-06-18 Franz Woellhaf Verfahren zum Beschichten mit Kunststoffmaterial von Gegenstaenden,vorzugsweise von voluminoesen Gegenstaenden,und Vorrichtung zur Durchfuehrung des neuen Verfahrens
DE19515425A1 (de) * 1994-04-28 1995-11-02 Vaillant Joh Gmbh & Co Innen emaillierter Speicherbehälter für einen Wasserspeicher
DE202011051419U1 (de) * 2011-09-22 2013-01-08 Frauenthal Deutschland Gmbh Anlage zur Herstellung eines Druckbehälters und damit hergestellter Druckbehälter, insbesondere Druckluftbehälter

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3839099A4 (fr) * 2019-10-25 2022-01-26 Sohome Houseware (Nanjing) Co., Ltd Procédé de fabrication de récipient en émail et récipient en émail

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Publication number Publication date
CN105855082B (zh) 2018-04-24
CN105855082A (zh) 2016-08-17

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