Technical Field

The present invention relates to a tube in a fire tube boiler.

Background art

The constructive embodiment of boilers for the production of hot water known as "fire tube", which comprises a plurality of tubes designed to convey inside them the products of combustion generated by a burner before sending them to the stack and to be lapped externally by the water to be heated, is known.

In order to improve heat exchange, elements shaped in the most disparate manners are arranged inside the tubes in order to increase the exchange surface directed toward the exhaust gases, and in the background art such elements are locked due to deformation by compression of the tubes designed to accommodate them, i.e. by thermal hysteresis of the tubes proper.

Disclosure of the invention

The aim of the present invention is to provide a tube designed to be inserted in a fire tube boiler which comprises internally elements which are adapted to increase the exchange surface directed toward the exhaust gases and are locked without requiring any intervention on said tube.

This aim and other objects that will become more apparent hereinafter, are achieved by a tube in a fire tube boiler, according to the invention, comprising the features disclosed in the appended claims.

Brief description of the drawings

Further characteristics and advantages of the present invention will become better apparent from the description of some preferred but not exclusive embodiments of the tube in fire tube boiler, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figures 1 to 4 are transverse sectional views of different embodiments of the tube in fire tube boiler according to the invention; Figure 5 is a transverse sectional view of a further embodiment;

Figure 6 is a longitudinal sectional view of the tube, taken along the line VI- VI in Figure 5;

Figure 7 is a view of the operating principle of the variation shown in Figures 5 and 6.

Ways of carrying out the invention

With reference to the Figure 1, the reference numeral 1 generally designates the tube, which has a wall 2 with a constant thickness and a plurality of elements 3 which are all perfectly identical.

The element 3 comprises the arc-like portion 3 a, which is adapted to make contact with the inner surface of the wall 2 and is provided, at its ends, with protrusions 3b, 3c, which do not join.

The elements are in mutual contact at the protrusions with which they are provided, as occurs for example for the element 3, which is in contact with contiguous elements 4 and 5 respectively at protrusions 4a and 5a of the elements, and the protrusions are designed to undergo, upon assembly, such an elastic deformation as to cause a reaction that is sufficient to keep in position the entire set of elements.

The embodiment shown in Figure 2 provides for the presence, inside a wall 6, of a plurality of closed elements 7 and 8 and of a single element 9 which comprises, like the elements of the tube of Figure 1, an arc-like portion 9a, which is adapted to make contact with the inner surface of the wall 6, and is provided, at its ends, with protrusions 9b, 9c, which upon assembly are designed to undergo such an elastic deformation as to keep locked in position, due to the reaction that is produced thereby, all the elements that are present.

Figure 3 is a view of an embodiment that provides for the presence, inside a wall 10, of three identical elements 1 1, 12, 13, each of which comprises an arc-like portion 1 1a for the element 11 , which is adapted to make contact with the inner surface of the wall 10, provided with protrusions l ib, 1 1c for the element 1 1 for supporting a curved member such as l i d.

The curved member 1 id, together with similar curved members 12a, 13a of the elements 12 and 13, delimits a portion of space that is designed to receive an expander element constituted by an elastic pin 14, which, being deformed upon insertion, applies an elastic reaction which locks all the elements.

Instead of the elastic pin, the expander element might be constituted by a conical body which, pushed inside the portion of space delimited by the curved members, forces the elements 11, 12, 13 into contact with the wall 10, causing their locking.

Figure 4 is a view of an embodiment in which, inside a wall 15, two identical elements 16 and 17 are provided, each comprising an arc-like portion 16a, which is provided with fins, 16b for the element 16, which is adapted to make contact with the inner surface of the wall 15 at half of the circumference. A flat element 18 is also provided, which is interposed between the elements 16 and 17 and is wedge-shaped at ends 18a, 18b so as to lock the elements.

A further embodiment is shown in Figures 5, 6, 7, and such embodiment comprises two elements 19, 20, which comprise arc-like portions 19a, 20a, which are adapted to make contact with the inner surface of a wall 21 and are provided with fins 19b, 20b. The elements 19 and 20 are in contact at a plane 22 that does not pass through the axis of the tube, and thus the action of a longitudinal force, indicated by the arrow of Figure 7, on the element 19 and of a force that is opposite thereto on the element 20 determine, upon insertion, a forcing action which leads to the locking of the elements.

The described invention is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; the materials used, as well as the shapes and dimensions, may further be any according to requirements.

The disclosures in Italian Patent Application No. MI2010A001086 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.