EP0762054A1

EP0762054A1 - Pressure ring for roof duct

Info

Publication number: EP0762054A1
Application number: EP96202391A
Authority: EP
Inventors: Ietse Jan Pestoor
Original assignee: Muelink and Grol BV
Current assignee: Muelink and Grol BV
Priority date: 1995-08-28
Filing date: 1996-08-28
Publication date: 1997-03-12
Anticipated expiration: 2016-08-28
Also published as: ATE179791T1; NL1001077C2; DE69602326D1; DE69602326T2; EP0762054B1

Abstract

Fluid-carrying duct element having, at its outside in its longitudinal direction, delimiting members (8,15) facing one another at a distance, for generating a flow resistance in the longitudinal direction of the duct element, having, in that space in between, a mouth (9) for connection inwards in the duct element and one or more resistance elements (16) with a space in between in a direction transverse to the longitudinal direction of the duct element, set up for generating a flow resistance in a direction transverse to the longitudinal direction of the duct element and in cooperation, so as to control the fluid flow, with one of the delimiting members.

Description

The invention relates to conducting a fluid flow along the outside of a fluid-carrying duct element, for example the combustion air supply of a flue gas discharge of a combustion chamber. In particular, but not exclusively, the invention relates to flues projecting beyond a building, which flues may be directed vertically, horizontally or at any angle in between. A specific example of such flues are the combustion air supply pipes and flue gas discharge pipes which, with a space in between, run essentially concentrically and whose orifices opening into the environment (the air intake orifice and the combustion gas discharge orifice, respectively) open into the environment at a considerable distance from one another.
The object of the invention is the improved control of a fluid flow along the outside of the duct element, in particular with an eye to improved control of the flow conditions within the duct element, such as the uniformity of the fluid flow velocity or the level of the fluid pressure.
To this end, the present invention presents an arrangement in accordance with the combination of measures summarized in the appended Claim 1. Due to the cooperation of the delimiting members and the resistance elements, the fluid flow at the outside of the duct element encounters a flow resistance so that it can be directed into a direction suitable for the intended effect. It will be obvious to those skilled in the art how the delimiting members and the resistance elements have to be designed in order to achieve a flow resistance in the direction essentially parallel to the fluid-carrying duct element and essentially in the circumferential direction of said fluid-carrying duct element, respectively. For example, the delimiting member is designed, to that end, as a projecting circumferential flange, whereas the resistance elements are protrusions designed to be spaced from one another around the circumference of the duct element, a principal plane of said protrusions forming an angle with the direction transverse to the longitudinal direction of the duct element.
It was found that the greatest control effect by means of the invention is achieved if the delimiting members and resistance elements are used in conjunction with a shell section having an end baffle being arranged loosely around the duct element and around the mouth for connection to the inside of the duct element, so that the shell section with end baffle, preferably positioned essentially concentrically around the duct element, forms a preferably annular feeder duct towards said mouth (i.e. the inflow mouth of the duct element), and which opens in the direction of, and at a distance from, the resistance elements. Such a shell section with end baffle is, in the context of flues, sometimes referred to as ventilation bowl, which in that context cooperates with the duct for supplying combustion air to a furnace.
Preferably, the resistance elements and delimiting members, at least one of the delimiting members, are designed as components which are separate from the fluid-carrying duct element, so that they can be kept in stock as separate components and it is also possible for their position with respect to the mouth for inward connection in the duct element to be adjustable.
According to an advantageous embodiment a cowl which comprises one of the delimiting members, is positioned around and over the mouth of the duct element so as to form a feeder duct towards said mouth, the inlet of the feeder duct being delimited by the cowl and the duct element and opening towards the opposite, other delimiting member which is situated outside the cowl, preferably at a distance from the inlet, and the resistance elements being positioned around the duct element, outside the cowl, at that side of the other delimiting member which faces the inlet, and preferably at a distance from the inlet. As a result of the resistance elements outside the cowl, which may be a cowl known per se, an additional thrust effect inside the cowl and the duct element is accomplished, the throughput of fluid through the duct element consequently being improved. Surprisingly it proved possible thus to improve the throughput delivery of known, relatively ineffective cowls. It is therefore possible, by fitting a relatively simple and inexpensive additional component on the duct element, underneath the cowl fitted thereon, to improve the supply of combustion air to a furnace without having to make fundamental changes to the system as a whole.
The invention is hereinafter explained in more detail on the basis of a non-limiting illustrative embodiment with reference to the accompanying drawing, in which:

Figure 1 schematically shows a side view of a flue having concentric tubes, constructed according to the invention;
Figure 2 shows a perspective side view of the topmost section of the flue shown in Figure 1; and
Figure 3 shows a view corresponding to Figure 2 of a section of an alternative embodiment.

Figure 1 shows a flue 1 according to the invention. This comprises two tubes 2, 3, fitted concentrically inside one another and at a distance from one another. The inner tube 2 is designed to be connected to the flue gas discharge of an otherwise essentially closed combustion chamber, for example of a hot-water supply or a central heating facility for domestic application, said combustion chamber optionally being situated inside a building. The tube 3 is suitable for connection to the combustion air supply of such a furnace. To this end, the lower end, in the drawing, of the tube 3 may be connected in a conventional manner, via a branchpipe part of known design, to the air supply orifice of said furnace. As indicated at 4, the flue 1 is provided with a circumferential recess, running all the way round, in a pipe 3 section thickened for insulation purposes, to achieve an essentially airtight penetration through the roof 5 of a building. The tube 3 ends within a ventilation cowl 6 (sometimes referred to as ventilation bowl), whereas the tube 2 continues past said ventilation cowl 6, so that the respective mouths of the tubes 2 and 3 open into the environment, outside the building, at a distance from one another, seen in the longitudinal direction of the flue 1. As can be seen more clearly from Figure 2, the ventilation bowl 6 comprises a loosely fitting shell 7 which surrounds the tube 3 at a distance and essentially concentrically and, at its end facing away from the mouth 9 of the tube 3, carries an end baffle 8 via which the ventilation bowl 6 is fastened to the tube 2. The cowl 6 forms a feeder duct towards the (inflow) mouth 9 of the tube 3. The latter's inlet 20 situated on the underside of the cowl 6 is delimited by the cowl 6 and the tube 3. As depicted, the shell section 7 is of conical shape. Other suitable shapes are also conceivable, however. The end baffle 8 can further be formed by a continuation of the preferably conical design of the shell section or may exhibit a different shape, tapering towards the tube 2. The shell section 7 and/or the end baffle 8 may carry further ventilation facilities such as orifices, so that a gas flow from the environment towards the mouth 9 (said mouth 9 forming the inflow mouth of the so-called duct element, in this case the tube 3) is not exclusively restricted to the area at the end of the shell section 7, facing away from the end baffle 8. That end 10 of the tube 2 which opens into the environment carries a cowl 11, provided with a condensate drain, a leakage ring 12 and a condensate collecting bowl 13 by means of which condensate is passed back into the tube 2. As it happens, the design of the end 10 is not essential for the invention; other designs are likewise conceivable.
At a distance below the ventilation bowl 6 there are, at the outside of the pipe 3, features 14 for the purpose of directing the fluid flow along the outside of the tube 3. What is shown is a flange 15, which projects essentially radially from the tube 3 and, at the side of said flange which faces the mouth 9 of the tube 3, a series of lips 16 which have spaces in between and which project in a ring-shaped pattern from the circumference of the tube 3. The principal surface of the lips 16 is directed essentially perpendicularly to the principal surface of the flange 15. Other angles between the principal surfaces of the lips 16 and the flange 15 are, however, likewise conceivable. It will be obvious to those skilled in the art how the flange 15 and the lips 16 should be designed to achieve a flow resistance in the longitudinal direction and the circumferential direction, respectively, of the tube 3. As shown, the lips 16 are punched from a ring 17 which is designed, integrally with the flange 15, as a separate component 14. Instead of being rectangular, the shape of the lips may also take any other conceivable form, such as rounded or, for example, tapering to a point. The principal surfaces of the lips 16 and the flange 15 may be planar, but may also, for example, be corrugated, fluted or nonplanar in some other way, for example so as to exert an additional flow resistance on the fluid flow. The features 14 may be made of any suitable material such as metal or plastic.
Even if the ventilation bowl is omitted, the elements 14 will have a beneficial effect on the flow behaviour along the outside of the tube 3. If the ventilation bowl is absent there is in fact only one delimiting member within the scope of the claims. Alternatively, for example, it is possible to employ just the baffle 8 of the ventilation bowl 6, so that it is then again a matter of two delimiting members with the resistance elements and the mouth in between them.
Figure 3 shows a variation on the elements 14 giving rise to a flow resistance. The lips 16 have now been replaced by dish elements which have arisen from a pleated collar which is fitted around the tube 13.
Both the flange 15 and the baffle elements or lips 16 may be provided with, for example, further profiling or alternatively orifices for further control of the fluid flow. By means of, for example, orifices in the flange 15 and/or the baffle elements 16 it is possible to allow a portion of a fluid flow to pass said elements 15 and/or 16.
The invention is based on the insight that by means of the cooperation of elements which cause a flow resistance or an obstacle to a flow to achieve control, in the longitudinal direction of the duct element and in the circumferential direction, respectively, of the fluid flow outside the duct element in the direction to or from the mouth. This is advantageous, in particular, in the case of, for example, flues which are subject to varying wind directions, so that the prevailing wind direction and wind speed has a verifiable effect on, for example the behaviour of the fluid flow and, for example, the pressure within the duct element. The abovementioned effect can be achieved very simply by positioning, below the air inlet cowl at some distance from its inflow orifice situated underneath, a ring which fits around the duct element, extends transversely to the duct element and, at its top side facing the inflow orifice, is provided with baffles which essentially extend vertically. The invention therefore also relates to an annular disc for fitting on/around a duct element, the annular disc at one of its sides being provided with baffles which essentially extend transversely with respect to the disc.

Claims

Fluid-carrying duct element having, at its outside in its longitudinal direction, at least one, preferably two delimiting members (8, 15) facing one another at a distance, for generating a flow resistance or an obstacle to the flow in the longitudinal direction of the duct element (3), having a mouth (9) for connection inwards in the duct element (3) and one or more resistance elements (16) arranged with an interspace in a direction transverse to the longitudinal direction of the duct element (3) for generating a flow resistance or obstacle to the flow in a circumferential direction around the duct element (3) transverse to the longitudinal direction of the duct element (3) and in cooperation, so as to control the fluid flow, with one of the delimiting members (8, 15), said resistance elements being located at that side of the delimiting member (8, 15) which faces the mouth (9), and in the case of two or more delimiting members situated at a distance from one another the mouth (9) being located between two delimiting members (8, 15).
Fluid-carrying duct element according to Claim 1, a cowl (6) which comprises one of the delimiting members, being positioned around and over the mouth (9) of the duct element (3) so as to form a feeder duct towards said mouth (9), the inlet (20) of the feeder duct being delimited by the cowl (6) and the duct element (3) and opening towards the opposite, other delimiting member (15) which is situated outside the cowl, preferably at a distance from the inlet (2), and the resistance elements (16) being positioned around the duct element (3), outside the cowl (6), at that side of the other delimiting member (15) which faces the inlet (20), and preferably at a distance from the inlet (20).
Fluid-carrying duct element according to any one of the preceding claims, the resistance elements comprising lip-shaped protrusions (16) whose plane is at an angle with respect to the direction perpendicular to the longitudinal direction of the fluid-carrying duct element, preferably being directed essentially parallel to the longitudinal direction of the duct element.
Fluid-carrying duct element according to any one of the preceding claims, at least one of the delimiting members being a flange (15, 8), discontinuous or continuous, which essentially runs around the fluid-carrying duct element.
Fluid-carrying duct element according to any one of the preceding claims, one of the delimiting members (8) loosely around the fluid-carrying duct element (3) and over the mouth (9) for inwards connection in the duct element being provided with a shell section (7) which, at that side of said mouth which faces away from the opposite delimiting member, has an end baffle (8) facing the duct element.
Fluid-carrying duct element according to any one of the preceding claims, the mouth (9) being situated in the vicinity of the one (8) and the resistance element (16) being situated in the vicinity of the other delimiting member (15).
Fluid-carrying duct element according to any one of the preceding claims, suitable for connection to a combustion chamber.
Fluid-carrying duct element according to any one of the preceding claims, the duct element being one of two duct elements essentially concentrically surrounding one another with a space in between; the one for connection to the combustion air supply; the other for connection to the flue gas discharge of a preferably otherwise essentially closed combustion chamber.
Fluid-carrying duct element according to any one of the preceding claims, one of the delimiting members and the adjoining resistance element cooperating therewith being elements which are separate from the fluid-carrying duct element and preferably form part of a separate sleeve section which surrounds the fluid-carrying duct element.
Sleeve section suitable for being placed around a fluid-carrying duct element, to which end said sleeve section has an internal profile which essentially matches the outer periphery of the fluid-carrying duct element, having a flange which projects beyond the circumference of the sleeve section, discontinuous or continuous, for defining a delimiting member, and having protrusions which are lip-shaped or have some other shape and project beyond the circumference of the sleeve section, the plane of said protrusions forming an angle with the plane in which said flange is situated.