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
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D25/00—Details of other kinds or types of rigid or semi-rigid containers
  • B65D25/14—Linings or internal coatings

Definitions

• the present invention belongs to the field of equipment intended to contain potentially corrosive fluids, especially intended for the production of hot water.
• It relates to a vessel whose wall is made from a composite material comprising three associated layers, which ensures both the rigidity of the wall and its physical and chemical stability vis-à-vis a corrosive fluid or can be in certain conditions of use.
• Another object of the invention is a method of manufacturing such a composite wall.
• the balloons used to supply hot water to individual or collective equipment are generally made from a steel shell, covered with a thermal insulating material.
• the internal surface must be treated to resist corrosion as the domestic hot water contains impurities and aggressive treatment products with respect to the steel, especially as the temperature is maintained at a high level to be distributed at 65 ° C. Not only does the installation deteriorate, which is a problem in itself, but also corrosion promotes biofouling by bacterial growth on the inner wall. It is obvious that the production of hot water, intended especially for food use, can not be subject to this kind of hazard.
• a protective material on the inner surface of the steel shell in contact with the liquid.
• the deposited material must be chosen so that its coefficient of expansion is close to that of the steel so that the protective layer remains integral with the steel shell during temperature variations of the system. It is for example known to project a molten metal material on the shell whose surface has previously been roughened. Also this technique called "metallization" due to the addition of material is in the form of fine metal droplets sprayed 'and cooled, is commonly implemented with F aluminum, which offers the advantage of a cathodic protection steel.
• the solution provided by the present invention is to coat the inner face of the tanks with a material resistant to corrosion, such as a plastic material:
• a material resistant to corrosion such as a plastic material
• the walls of the tanks are commonly made of steel, a material that provides the rigidity and the necessary mechanical strength at a moderate cost price.
• steel does not have a particular affinity for plastics, and on the other hand, it has a significant coefficient of expansion in the range of temperatures concerned, ranging from -2O 0 C to 100 0 C during various handling, storage, transport and operation, while plastics have a very different coefficient of expansion. In tanks of large volume, expansion can cause deviations of several millimeters, leading to dissociation of the coating and deterioration of the wall. It is therefore imperative to ensure a strong cohesion of the coating with the wall.
• thermoplastic polymeric compounds can be used as anticorrosive inner lining of tanks, when they are applied to a metallized steel shell, i.e. the inner face of the shell has been spray-treated with a molten metal material, which has the effect of rendering the surface porous.
• the coating technique used is inspired by well-known rotational molding techniques and brings an unexpected result. Indeed, the thermoplastic properties of many polymers are known and implemented to achieve all kinds of objects, by different molding techniques, and among them rotomolding. This method of transformation of plastics is carried out in three steps: filling of a mold with a thermoplastic polymer in the form of granules or powder, melting of the plastic material, then solidification.
• An object of the present invention is therefore to provide a tank useful for receiving corrosive liquids, for example for the production of hot water, the wall of which, while retaining its previous mechanical properties, is insensitive to chemical attack and more particularly to oxidation and chlorine.
• Another object of the invention is to provide a vessel whose wall is resistant to stress due to thermal expansion.
• Another object of the present invention is to provide a tank meeting the above requirements for periods of several years, and with a moderate manufacturing cost.
• Another object of the invention is to provide a method of manufacturing said tanks which is reliable and easy to implement.
• the present invention makes it possible to offer establishments such as hotels or hospital centers a means of distributing hot water in complete safety, without significant additional cost of equipment or operation.
• the present invention relates to a tank intended to contain a corrosive fluid, original in that it has a composite wall comprising an outer shell of steel, a metal or ceramic intermediate layer, and an inner layer based on a thermoplastic polymeric compound.
• the outer shell is the element ensuring the mechanical strength of the composite wall. It gives its shape to the tank and also serves as a support for other layers. It is commonly made of steel. It is possible to use, for example, non-alloyed hot-rolled structural steels that meet the standards in force. Its thickness is chosen according to the operating pressure and the diameter of the tank, in accordance with the pressure vessel code and / or the regulations in force in the country of use. It can thus be between 2 mm and 15 mm, more frequently between 4 mm and 8 mm. Manufacturers of heating equipment are familiar with these standards and the qualities of steel to be implemented.
• the surface of the part to be coated is previously prepared to remove oxides and calamines, increase its roughness and allow particles to anchor in the irregularities of the surface .
• the method called impact treatment can be used. It consists in projecting a natural or artificial abrasive onto the surface to be treated. The projection can be done by compressed air, either by a vacuum system (suction, suction, Giffard effect), or by a direct pressure system (overpressure). Depending on the size of the abrasive particles we are talking about sanding (fine particles) or shot blasting (larger particles).
• the depth of the roughness profile is between 5% and 25% of the thickness of the subsequent coating, with an optimum value around 25% which has the effect of increasing the contact area by a factor of 3 or 4.
• the inner face of the steel shell advantageously has a roughness Ra corresponding to the mean arithmetic mean deviation from the mean line of the surface, between 10 ⁇ m and 35 ⁇ m, preferably from 10 ⁇ m to 35 ⁇ m. about 15 ⁇ m. It is completely covered by the intermediate layer which adheres to it by a mechanical phenomenon with a force which can vary from 20 to 115 MPa after sanding, according to the processes and the materials.
• the intermediate layer of the wall according to the invention is a layer of metallic or ceramic nature. It can consist essentially of a metal chosen from aluminum, zinc, copper, tin, nickel, molibdene, manganese, or a base alloy. FR2007 / 000098
• metals selected from zinc, copper, nickel, tin.
• the intermediate layer consists essentially of a ceramic selected from nitrides such as NiAl, NiCrBSi, the aluminides as Al 2 O 3, Al 2 O 3 -TiO 2, or oxides such as Cr 2 O 3 , ZrO 2 -CaO.
• a treatment with a supply of reactive gas may be used.
• a substrate here the steel shell
• the reactive chemical species metal or ceramic to be supplied
• LCVD laser assisted chemical vapor deposition
• the material to be deposited is in the form of powder, wire, cord or rod. It is melted totally or partially in a source of heat (flame, electric arc, plasma).
• a carrier gas allows spraying the material, and transporting the droplets thus formed to the surface to be coated on which they solidify. The surface of the substrate does not undergo any fusion.
• the intermediate layer is porous, the porosity coming either from microcavities due to imperfect stacking of the droplets, or gas locked during solidification.
• the porosity rate varies according to the process and the materials used. Whatever the nature of the intermediate layer chosen, it advantageously has a porosity level of 0.1% to 25%, preferably between 5% and 10%.
• the deposits include inclusions such as oxides or other materials from the torches themselves, unmelted or partially melted particles that have not undergone a complete heat cycle (because of their size or their heat source). Due to the very fast cooling rate of the particles in contact with the substrate, the presence of intragranular microcracks within the deposits is possible. Furthermore, since the projections are made in the air, the droplets and the substrate are subjected to the oxidation phenomenon. It is not uncommon to see an increase in the oxygen level during the projection. It should be emphasized here that the characteristics of the intermediate layer (metallic or ceramic) should have led the 00098
• the invention has made it possible to use, in order to meet the desired objective of chemical stability with respect to corrosive fluids, its fixing properties of a polymeric coating.
• the wall of the vessel may further comprise an underlayer hooking between the steel shell and the intermediate layer.
• an undercoating layer is then used, which can be made of different materials, among which mention may be made of nickel durninide, molibdene, or alloys of the NiCr (80/20) or MCrAlY (M designating Ni) type. , Co or NiCo). It can be applied by any technique available to those skilled in the art, and advantageously according to the same technique as that used for the metallization of the steel shell.
• additives or technological aids such as a load up to 40% by weight (talc or calcium carbonate for example), reinforcing additives, for example fiberglass or mica at 20 to 30% by weight.
• Polyethylene taken from among the many existing types, for example from low density polyethylenes (or LDPE) having a density of between 0.92 g / cm 3 and 0.94 g / cm 3, or from high density polyethylenes can be used. (HDPE), having a density of between 0.95 g / cm 3 and 0.97 g / cm 3 . It is also possible to use polypropylenes, those used in the industry being almost always isotactic. They are often associated with a copolymer.
• polystyrene polypropylenes grafted with acrylic acid, maleic anhydride or styrene, polypropylenes crosslinked with silanes can be used which are thus functionalized as required.
• This list is not exhaustive and concerns all thermoplastics, including graft thermoplastic sub-families.
• a method of manufacturing a vessel for containing a corrosive fluid said vessel having a composite wall comprising an outer shell of steel, a metal or ceramic interlayer and an inner layer of a polymeric compound thermoplastic process, which essentially comprises the following steps:
• the deposition of the intermediate layer on the steel shell can be achieved by a technique known per se.
• the flame-wire projection technique is preferred for the practice of the present invention.
• the flame serves to melt the supplied material, which is introduced in the form of wire, cord, or rod at its center.
• the filler material is then projected onto the surface of the shell by a stream of compressed air.
• the steel shell before the metallization step, may be subjected to an impact treatment to increase its roughness.
• This treatment consists in projecting a natural or artificial abrasive onto the surface to be treated.
• the conditions of implementation are easily chosen by those skilled in the art who already practice these techniques of sanding (fine particles) or shot blasting (larger particles).
• a sub-layer of attachment is applied to the shell. It can be carried out according to the same process as that used for the deposition of the intermediate layer, with different materials, among which mention may be made of nickel aluminide, molibdene, or alloys of the type 7 000098
• NiCr 80/20
• MCrAIY M designating Ni, Co or NiCo
• the third layer can be applied. This is to reproduce the inner shape of a cavity (the inner surface of the wall of the tank) which can range from one to 100,000 liters.
• a cavity the inner surface of the wall of the tank
• one proceeds in three phases, by analogy with discontinuous processes of plastics processing: filling the cavity, melting of the polymeric material, solidification of the polymeric material.
• the tank rotating in all directions, is then heated to the temperature of good melting, the melting temperature of the thermoplastic polymers being generally between 150 ° C and 30O 0 C 1
• the molten plastic powder flows by; gravity on the walls.
• the rotational speeds being low the effect of the centrifugal force is negligible.
• the melting of the polymer compound in powder form is obtained by heating the metallized shell 1c; containing, by an external heating means.
• the heat input is achieved at; oven, gas bar or infrared panels.
• the heated tank transmits its heat to the powder whose grains melt and stick on the wall.
• the thermoplastic whose temperature is above its melting point has a viscous consistency.
• the device is removed from the oven and allowed to cool. Cooling can be accelerated by projecting fresh air and / or water mist onto the tank.
• a particularly advantageous embodiment of the process according to the invention uses a powdered polymeric compound comprising polar groups of electronegative character. 7 000098
• the polymeric powder compound used in the process according to the invention may be chosen from ethylene polymers, propylene polymers, fluorocarbon resins, polyoxymethylenes.
• said polymeric powder compound is a diacid modified polymer. More preferably, said polymeric powder compound is a polypropylene modified with maleic anhydride.
• the tank as described and claimed in the present application may be manufactured by the method of the invention or by any other suitable method. It finds application in various industrial fields, such as the production of hot water, but also the industrial production of chemical or biological substances in reactors, or the road or rail transport of corrosive fluids.
• the fluids used in these applications may be at low, medium to high temperatures and may be more or less aggressive.
• the characteristics of the tank allow its use in all conditions without long term degradation.
• another object of the present invention is a device for storing, transporting, storing or producing a corrosive fluid, comprising a composite wall vessel as described above. More particularly, is claimed a hot water production device comprising a composite wall vessel according to the invention.
• This wall was made from a steel shell of unalloyed construction, complying with the European standard bearing the N 0 EN 10025: 1993 (symbolic designation: S235JR, numerical designation: 1.0037) and with the French standard N ° NF A 35-501 (designation: E 24-2), of thickness 3 mm, and forming a cylindrical tank with a volume of 50 liters.
• the composite wall has been subjected to various tests to evaluate its performance. It has been found on the one hand that during temperature variations, the layers remain united even though their coefficient of expansion is different. This result is assumed to be due to the fact that the intermediate layer absorbs the differential expansion between the materials of the outer and inner layers of the wall.
• Each test piece 1 consists of an aluminum metallized steel plate 2 covered with a layer 3 of polypropylene melt-modified in an oven at 220 ° C.
• the specimen 1 is removed from the furnace and a second aluminum metallized steel plate 4 is deposited on its surface, identical to the previous one, and provided with a hook 5 placed perpendicularly to the plane of the test tube 1. Then the whole thing is put back in the oven for 14 minutes.
• a sandwich structure is obtained with a polymeric layer 3 fixed to the two metal plates 2, 4.
• the lower plate 2 has a dimension of 200 mm ⁇ 100 mm, it is further provided with mass suspension means, by example of rings 6, while the upper plate 4 has a surface of only 50 mm x 50 mm. Their thickness is about 3 mm, as well as that of the polymeric layer.
• the polymer layer 3 is sliced in its thickness around the upper plate 4, so as to laterally isolate a polymeric coating sample 7 of 50 mm side centered on the axis of the hook 5.
• the test piece 1 is suspended by the hook 5 and attaches loads to the rings 6, mass increasingly high (10 kg in 10 kg).
• the mass required to take off the sample 7 from at least one of the plates 2 or 4 is thus measured in less than one minute and the corresponding force, expressed as daNcnr 2, is calculated.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Laminated Bodies (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Coating By Spraying Or Casting (AREA)

Applications Claiming Priority (2)

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• 2006
  • 2006-01-20 FR FR0600506A patent/FR2896489B1/fr not_active Expired - Fee Related
• 2007
  • 2007-01-19 WO PCT/FR2007/000098 patent/WO2007083029A2/fr not_active Ceased
  • 2007-01-19 EP EP07718014A patent/EP1993923B1/de not_active Not-in-force
  • 2007-01-19 AT AT07718014T patent/ATE434572T1/de not_active IP Right Cessation
  • 2007-01-19 DE DE602007001390T patent/DE602007001390D1/de active Active
  • 2007-01-19 CN CNA2007800066596A patent/CN101389539A/zh active Pending
• 2008
  • 2008-07-21 TN TNP2008000307A patent/TNSN08307A1/fr unknown
  • 2008-08-11 MA MA31168A patent/MA30215B1/fr unknown

Non-Patent Citations (1)

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