A BOILER CONSTRUCTED USING A COMPOSITE MATERIAL

Abstract: The invention falls into the field of boilers made of polymeric matrix composite materials. The said boiler is constituted of two layers composed, in order from the inside to the outside, of a first layer (4) made of thermoplastic or elastomeric matrix material, and a second layer (5) composed of a plurality of filaments or strips of a synthetic material covered with resins which agglomerate by means of reticulation or fusion. The said first laser is built as a single body and is designed to come into direct contact with the water and the said second layer is also built as a single body and is designed to create structural resistance for the said boiler.

Description: DESCRIPTION A boiler constructed using a composite material. Technical field The invention relates to a polymeric matrix composite material boiler for use, in particular, in a water heater. Background Art For some time now, the applicant has been increasingly interested in the use of synthetic polymeric matrix materials as suitable materials for manufacturing components for containing water, for sanitary purposes, heated by either gas or electricity. This interest arises from a number of advantages that these materials have in comparison with the metallic materials used until now. A first drawback of the metal boilers traditionally used in water heaters is constituted by the phenomenon of electrolytic corrosion which occurs on the internal surfaces of the said boilers. To counteract the said electrolytic corrosion which occurs, protective systems are adopted, such as the application of suitable internal claddings or special sacrifical or impressed current anodes. A further drawback of the traditional metal boilers is the negative environmental effects caused during the production phase by the use of chemical substances to prepare the metal surfaces. A still further drawback is constituted by the short working life of the traditional metal boilers. When selecting materials, the designs proposed until now for the manufacture of synthetic material boilers for water heaters have tended, in general, to prefer materials with particular mechanical features and particular forms of structural strengthening. The international patent application PCT/IT97/00186, for example, examines the use of alloy polymeric materials modified with other technical polymers since the said materials have positive mechanical stress resistance features, which are due also to the addition of reinforcing agents. The international patent application PCT/EP98/07982, proposes a way of reaching the considerable mechanical resistance features of a boiler for water heaters made of a synthetic material with structural reinforcing ribs. In both inventions indicated the boiler used is manufactured by means of the joining together of two or more components by welding or using adhesives. These solutions, which are structurally weak, require suitable adaptations to guarantee the functioning conditions of the article do not create potentially dangerous situations for the user due to the pressure which develops, in particular conditions, inside the boiler during the heating process or when the water is stored in the said boiler. Disclosure of Invention A first aim of this invention is to make it possible to manufacture a boiler made of a synthetic polymeric material as a single body without a structurally weak design. A second aim of the boiler in question in this invention is that the production costs shall be similar to those of a boiler with an identical capacity but made of metal. Further aims are constituted by the ease with which the components can be recycled and a guaranteed working life of at least ten years. Furthermore, the said aims are achieved with the least impact on the environment possible during the production phase and with the energy consumption, both during the production phase and when the water heater fitted with the boiler is in use, being extremely low in comparison with the other water heaters available on the market. The boiler in question in the present invention, for use, in particular, in a water heater, fitted with a heating element and which is preferably, but not exclusively, electric and of the kind made entirely of a polymeric matrix composite material, is characterised by the fact that it is constituted of the two following layers, positioned one after the other in order from the inside to the outside of the said boiler: - a first layer of thermoplastic or elastomeric matrix material, the said layer being manufactured as a single body and the said layer having characteristics which make it suitable for contact with water; - a second layer composed of a plurality of filaments or synthetic strips wrapped around the first layer, the said filaments or strips being covered with resins which agglomerate by reticulation or fusion; the said second layer being manufactured as a single body and designed to create a structural resistance for the boiler; the said first and second layers being detachable from each other only after the said boiler has been destroyed, the said destruction being such as to allow the said boiler to be recycled at the end of its working life. These and other characteristics will better emerge in the description that follows of a preferred embodiment of this invention provided in the form of a non-limiting example with accompanying drawings, in which: Figures 1 shows a boiler fitted into an electric water heater; Figure 2 shows, schematically and out of scale, a section of the boiler; With reference to figure 1 , the number 1 is used to denote a water heater in which a boiler 2 is fitted. Inside the boiler 2 is a heating element 3, of an electric kind. In figure 2, the number 4 indicates a first layer which comes into direct contact with the hot water or the water to be heated and the number 5 denotes a second layer which is outside the first. The first layer 4 is made of a thermoplastic matrix material constituted of polyolefinic, homopolymeric, copolymeric, metalocenic resins or PET- based resins, or PPE/PPO-based resins or even, a mixture of other compatible polymeric materials or those which have been made compatible, either semi-crystalline ones or amorphous ones. The first layer 4 can also be made of an elastomeric matrix material constituted of PB or PLB-based resins or even a mixture with other compatible polymers or those which have been made compatible, either semi-crystalline ones or amorphous ones. The two layers 4 and 5, both being in a single body, are completely detachable from each other. One layer 6 of the water heater 1 containing the boiler 2 is wrapped around the outside of the said boiler and is designed to provide thermal insulation for the said boiler; the layer 6 being detachable from the external surface of the second layer 5. A first advantage of the boiler in question in the present invention is that the second layer, designed to supply the necessary structural resistance for the said boiler, guarantees, at the least, a bursting value, when hot, of no less than 30 bar at 70°C and a number of mechanical fatigue cycles, from 1 to 8 bar, of more than the 20,000 required by the specific safety standards. A second advantage is constituted by the fact that the industrial cost of the boiler object of the present invention is substantially identical to that of a boiler with the same capacity but made entirely of metal. A further advantage is constituted by the ease with which the single components when ground up or the entire boiler unit in question in this invention can be recycled. A still further advantage is constituted by the low impact on the environment during the production phase and the energy consumption during both the production phase and when the said boiler is in use, which is extremely low in comparison to that of other products available on the market today. Other further advantages are constituted by the physical lightness of the unit and the lack of any element designed to combat the corrosion of the internal surface of the boiler. Lastly, the boiler object of the present invention has the further advantage that its heat production levels, as well as its mechanical performance levels, are no lower than those of the metal boilers. A further embodiment, not shown, envisages the application of a layer composed of a plurality of filaments or strips of synthetic material covered with resins which agglomerate by means of reticulation or fusion outside the said polymeric material boiler, for use, in particular, in a water heater, fitted with a heating element and which is preferably, but not exclusively, electric and characterised by the fact that it is assembled from two or more elements fitted together by welding , adhesive, or another method. The said covering is applied to the said composing elements when fully assembled. The said layer and the boiler created after the full assembly of the said two or more elements are fitted together in such a way as to allow their total separation. In this description, specific reference has been made to a water heater inside which the boiler object of the present invention is fitted, however, the said boiler can naturally also be used beneficially in fields of application other than that of the water heater.

Claims: Claims 1. A boiler (2), for use, in particular, in a water heater, fitted with a heating element (3) preferably, but not exclusively, of the electric kind, and of the kind made entirely of a polymeric matrix composite material, wherein the said boiler is composed of the two following layers positioned one after the other from the inside to the outside of the said boiler: - a first layer (4) of thermoplastic or elastomeric matrix material, the said layer being manufactured as a single body and the said layer having characteristics which make it suitable for contact with water for sanitary purposes; - a second layer (5) composed of a plurality of filaments or synthetic strips wrapped around the first layer (4), the said filaments or strips being covered with resins which agglomerate by means of reticulation or fusion; the said second layer being manufactured as a single body and designed to create a structural resistance for the boiler (2); the said first and second layers being detachable from each other only after the said boiler has been destroyed, the said destruction being such as to allow the said boiler to be recycled at the end of its working life. 2. A boiler, according to claim 1, wherein the thermoplastic matrix material of which the first layer (4) can be produced is constituted of polyolefinic, homopolymeric, copolymeric, metalocenic resins or PET- based resins, or PPE/PPO-based resins or even, a mixture of other compatible polymeric materials or those which have been made compatible, either semi-crystalline ones or amorphous ones; the choice of the said possible thermoplastic matrix materials depending on the resistance, in particular the thermal resistance, that is to be given to the first layer (4). 3. A boiler, according to claim 1, wherein the elastomeric material of which the first layer (4) can be produced is composed of PB- or PIB-based resins or even, a mixture of other compatible polymeric materials or those which have been made compatible, either semi-crystalline ones or amorphous ones; the choice of the said possible thermoplastic matrix materials depending on the resistance, in particular the thermal resistance, that is to be given to the first layer (4). 4. A boiler , according to claims 1, 2 and 3, wherein the material of the first layer (4), which comes into direct contact with the water, has a high level of resistance to the thermal expansion and the cyclical mechanical warping due to the water pressure. 5. A boiler , according to claim 1, wherein the filaments or strips of the second layer (5) can be constituted of fibre glass, carbon or even a type of fabric. 6. A boiler, according to claims 1 and 5, wherein the resin covering made of filaments or strips of synthetic material of the second layer (5) is constituted of a pre-impregnation; the said resins used in the said pre- impregnation can be of either a heat-setting kind or of a thermoplastic matrix kind with suitable fusion points, the selection of the said resin depending on both the mechanical and the thermal resistance that is to be given to the second layer (5). 7. A boiler, according to claims 1, 5 and 6, wherein the plurality of filaments or strips of a synthetic material is applied according to the most suitable technology, design and thickness for the final performance levels required of the boiler (2); for the sake of an example, depending on the said technology, design and thickness, the said boiler can reach bursting values, when hot, of 38 bar at 70°C and a number of mechanical fatigue cycles due to the inconstant pressure of the water of over one million at 1-6 bar. 8. A boiler, according to claim 1, wherein a layer (6) of the water heater (1) containing the boiler (2) put to use in the said water heater with the intention of guaranteeing the thermal insulation of the said boiler, is positioned outside the second layer (5) of the said boiler and can be detached from the said second layer; the fact that this is detachable is designed to allow the boiler (2) to be fully disassembled after its destruction, if it is required to be recycled at the end of its working life. 9. A boiler made of a polymeric material, for use, in particular, in a water heater, fitted with a heating element and which is preferably, but not exclusively, electric and constituted of the joining together of two or more components, fixed together by welding, adhesive or any other method, wherein one layer, composed of a plurality of filaments or strips of a synthetic material covered with resins which agglomerate by reticulation or fusion, is wrapped around the outside of the said boiler, the said wrapping constituting a single body once the said composing elements are fully assembled and being designed to create a structural resistance for the boiler; the said layer and the said boiler being entirely separable.

Inventors: LATINI LUCIO, LATINI, LUCIO
Applicants: LATINI LUCIO, MERLONI TERMOSANITARI SPA, LATINI, LUCIO, MERLONI TERMOSANITARI S.P.A.
Application year: 2001
Main classification: F24H
IPC codes: F24H1, F24H9