GB2167545A

GB2167545A - Flue assembly

Info

Publication number: GB2167545A
Application number: GB08429917A
Authority: GB
Inventors: Craig Funke
Original assignee: NRG Systems Inc
Current assignee: NRG Systems Inc
Priority date: 1984-11-27
Filing date: 1984-11-27
Publication date: 1986-05-29
Also published as: GB8429917D0

Abstract

A flue assembly for use in conjunction with a heating plant has a cap (30) which is pivotally mounted adjacent the flue outlet (24) to move between a closed position occluding the outlet and an open position permitting exit of flue gas. Adjustable counterbalancing means (40) is associated with the cap for adjusting the flue gas pressure necessary to move the cap to open position. An adjustable stop (70) determines the open position of the cap (30). Downstream of the outlet (24) is a flue box which has an interior cross-sectional area greater than that of gas inlet (17) and outlet (18) and is provided with a pivotal damper plate (60). <IMAGE>

Description

SPECIFICATION Flue box assembly This invention relates to a flue box assembly for use in conjunction with a heating plant.

Heretofore, flue box assemblies have been developed for installation along outlet exhaust pipes emanating from a heating plant, the flue box assembly being designed to ensure the complete combustion of the fuels utilised. It has been known, for example, that in a typical heating plant, a certain percentage of the fuel will remain unburned and will escape from the heating plant along with the flue gases representing the products of combustion of that portion of the fuel which has in fact been combusted. In addition, the heat transfer process is substantially reduced, thereby creating an improper balance in the combustion zone. In general, flue boxes of this nature have heretofore been developed as shown by United-States Patent No. 4,372,289 as well as United States Patent No. 4,136,676.As is described therein, the flue box is designed with a pivotally movable damper plate located within an interior portion of the housing of the flue box assembly, the damper plate being movable between an open and closed position. Under normal conditions, the damper plate will stay substantially closed, and will block the flow path of the flue gases being exhausted from the heating plant. Since these flue gases contain unburned fuels as well, the gases are restrained in the heating plant such that a more complete combustion of the fuels will be achieved, and better heat transfer attained. Furthermore, by having the damper plate pivotally movable therein, under conditions of extreme back pressure or explosion, the damper plate is designed to move pivotally to a complete open position thereby to provide an immediate exit path for the flue gases emanating from the heating plant.

Further improvements have been achieved by creating the flue box assembly having a greater diametric opening than either the inlet or outlet openings therefrom. Hence, it has been found that by providing an expanded chamber for the flue gases to enter the flue box from the heating plant, stratification of the denser unburned fuel products will occur. As hot exhaust gases are produced, a channelling effect occurs so that a central column of hotter gas is created which may cause a buildup of the unburned fuel vapours below the damper plate in the flue box assembly. Hence, further efficiencies in connection with energy conservation can be effected where the damper plate is provided with one or more flue openings or apertures positioned therein, thereby avoiding or minimising the danger of back pressure of the unburned gases or other gases caused by stratification under the damper plate.

It has further been observed that in some installations, it is necessary to provide the flue box with an additional device in order to ensure that the unburned fuels will in fact be forced back into the furnace for total combustion. In this connection, it has now been found that by providing the flue box with a pivotal cap, which is designed to move between an open and a closed position thereby either occluding, or rendering the outlet opening from the flue box unobstructed, further efficiency of fuel combustion is achieved, including an increased efficiency in heat transfer and the restoration of proper combustion zone balance. This is especially true when the pivotal cap is provided on a flue box of the type having a pivotal damper plate mounted therein.However, in order to provide a cap for a flue box assembly, it is again necessary that the cap not only be pivotally adjustable, thereby to move between an unobstructed open position, and an occluded closed position relative to the flue box, but that the cap must be designed to achieve a delicate counterbalancing relationship with respect to the pressure of the flue gases exiting from the furnace via the flue box assembly.

According to the present invention there is provided a flue box assembly for use in conjunction with a heating plant, the assembly including a housing, a cap pivotally mounted on said housing adjacent an outlet passage thereof, said cap being adapted pivotally to move between a closed position in which it occludes the outlet passage of the housing and an open position, and adjustable counterbalancing means associated with said cap for adjusting the relative pressure necessary to move said cap into its open and closed positions in relation to the force exerted by flue gases passing through said outlet passage.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way ot example, to the accompanying drawing, in which: Figure 1 is an exploded perspective view, partly cut-away, of a flue box assembly, and Figure 2 is a side view of part of the assembly shown in Figure 1.

As shown in Figure 1, a flue box assembly 10 has a housing 12, which is enclosed on all four sides by side walls 13, 14, 15 and 16 respectively.

The housing 12 includes a gas inlet opening (not shown), which is connected to a gas exit pipe 17 leading from a heating plant or other furnace device (not shown). At the opposed end of the housing 12 is a gas outlet opening 18 which is fitted with an outlet collar 19 to which is attached a gas outlet pipe 20. The housing 12 has a greater crosssectional area than that of either the inlet opening or the outlet opening As has been previously indicated, a flue box assembly of the type shown is more clearly described in United States Patent No. 4,136,676 as well as United States Patent No. 4,372,289, wherein the precise details of construction of such a device, and the manner in which it interconnects with an existing heating plant or furnace is described.

The gas outlet pipe 20 is provided with a closed top member 22 having an exit collar 24 centrally positioned thereon. As is more fully shown in Figure 2, the exit collar 24 has an open top end 26, which is opened and closed by a cap 30. The top member 22 includes a circumferential flat surface 25 which provides a mounting surface for a Ushaped bracket 27 which is, in turn, provided with a pair of opposed mounting apertures 28.

The cap 30 is provided with an L-shaped pivot bracket 32 which is joined at its forward end 33 to the cap 30 and includes a mounting collar 34 at its opposed end. The L-shaped pivot bracket 32 and the mounting collar 34 forming a part thereof are in turn fixedly secured to and unitary with opposed side mount brackets 35 and 36 respectively. The Lshaped pivot bracket 32 including the mounting collar 34 and the side mount brackets 35 and 36, respectively are pivotally mounted to the U-shaped bracket 27 carried on the circumferential flat surface 25 of the top member 22 by means of a pivot pin 38 which is mounted through the internal confines of the mounting collar 34 and appropriate apertures provided in the side mount brackets 35 and 36 respectively, and journalled in the mounting apertures 28 carried in the U-shaped bracket 27.

The cap 30 is further provided with a holding bar 40 which is mounted at its forward end 42 to the cap 30, and extends radially outwardly therefrom.

The holding bar 40 is a flat bar having an upper mounting surface 44 which carries a pair of opposed upright brackets 45 and 46 respectively. A threaded round bar 48 is shown to be carried between the opposed upright brackets 45 and 46 respectively, the threaded round bar 48 being fixedly secured to the upright brackets 45 and 46 at the opposed ends thereof.

A weight 50 is carried on the threaded round bar 48 and movabty along the length thereof, by being provided with a central aperture 52, the weight 50 being held in position by a pair of opposed threaded nuts 53 and 54 respectively. As shown in Figure 2, in phantom, the weight 50 may be moved forwardly or rearwardly along the length of the threaded round bar 48 merely by screwing and unscrewing the threaded nuts 53 and 54 respectively such that the weight 50 may be positioned at any point along the length of the bar 48.

It will be appreciated that, where the weight 50 is positioned adjacent the outward end 43 of the holding bar 40, the cap 30 will be counterbalanced to a point such that it takes a relatively small amount of pressure against the undersurface of the cap 30 to open the same to permit the release of flue gases through the opening in the top member 22. On the other hand, where the weight 50 is screwed to a point closer to the cap 30, it will take a relatively greater amount of flue gas pressure against the undersurface of the cap 30 to open the same and permit the release of flue gases.

The flue box assembly 10 further includes a pivotal damper plate 60 which is provided with venting apertures 62, the venting apertures 62 in combination with the pivotal damper plate 60 controlling the movement of the flue gases through the flue box assembly 10. The cross-sectional area of the flue opening in the damper plate 60 is smaller than that of either the housing inlet opening or its outlet opening 18. By providing the cap 30 with the counterbalancing weight 50 which is adjustable such that relative pressure necessary to open the cap 30 may be adjusted and tuned, relative to the flue gas pressures which operate against the damper plate 60, a fine balance may be achieved as between the cap 30, and the operation of the damper plate 60 within the flue box assembly 10.In this manner, one is able to achieve a very fine control over the dwell time of the flue gases within the system thereby to ensure that all or substantially all of the unburned fuels will be burned prior to exiting from the system.

It will also be appreciated that the cap 30 and the counterbalancing weight 50 may be positioned at the top end of the stack emanating from the flue box assembly 10 at a point removed therefrom such that they are remote from the furnace or other heating plant itself, and externally of the corresponding building in which the heating plant or furnace is located. In that event, it becomes even more clear that the ability to adjust the counterbalancing weight 50 relative to the cap 30 and the pressures of flue gases against the undersurface of the cap 30 are important since, as the gases pass up the chimney or stack, there might be a loss of velocity because there is a loss of heat as the gases travel therethrough.By being able to counterbalance the cap 30 relative to the pressure necessary to open the same, the same fine degree of control may be obtained regardless of the positioning of the cap 30 and the counterbalancing weight 50.

It is contemplated that by providing a counterbalance adjustable weight in combination with a closure cap relative to a flue box assembly of the type described, a more efficient system may be obtained wherein unburned fuels may be more fully combusted prior to exiting from the system, thereby achieving a greater degree of energy conservation.

It will be observed that the top member 22 of the outlet pipe 20 is provided with an ear 70 fixedly secured thereto and extending laterally outwardly therefrom. The ear 70 includes a central aperture (not shown), which accommodates a threaded stop 72 therethrough. The threaded stop 72 is held in position by a pair of opposed threaded nuts 74 and 76 respectively, such that the threaded stop 72 may be adjusted along its vertical axis. The threaded stop 72 functions to limit the degree of opening of the cap 30, thereby further to enhance the heat conservation characteristics of the device by permitting the cap 30 to open to a very extended position, or, to be limited to a very small degree of opening, as is illustrated by the phantom lines in Figure 2.

Thus, the degree of the opening of the cap 30 relative to the housing may be limited to any desired maximum capacity despite the location of the adjustable weight 50 relative to the cap 30.

Claims

1. A flue box assembly for use in conjunction with a heating plant, the assembly including a housing, a cap pivotally mounted on said housing adjacent an outlet passage thereof, said cap being adapted pivotally to move between a closed position in which it occludes the outlet passage of the housing and an open position, and adjustable counterbalancing means associated with said cap for adjusting the relative pressure necessary to move said cap into its open and closed positions in relation to the force exerted by flue gases passing through said outlet passage.

2. An assembly as claimed in claim 1, wherein said housing has an inlet opening for flue gases and an outlet opening, the housing having a greater internal cross-sectional area than that of either said inlet opening or said outlet opening.

3. An assembly as claimed in claim 1 or 2, wherein a damper means is pivotably mounted in said housing so as to be able to pivot between an open and a closed position.

4. An assembly as claimed in claim 2 and 3, wherein said damper means has a flue opening therein, the cross-sectional area of said flue opening being smaller than that of either said inlet opening or said outlet opening.

5. An assembly as claimed in any one of the preceding claims, wherein said counterbalancing means includes a bar mounted on said cap in juxtaposition with respect to the pivotal mounting point of said cap and extending outwardly therefrom, a counterbalance weight being movable parallel to said bar, thereby to adjust the force required to open and close said cap.

6. An assembly as claimed in claim 5, wherein said weight is threadably mounted on a threaded rod which is carried by said bar.

7. An assembly as claimed in claim 1 or 2, wherein a stop means is provided to limit the degree of opening of said cap.

8. An assembly as claimed in claims 5 and 7, wherein said stop means is adjacent the pivotal mounting point of said cap and is formed by an ear secured to said housing and extending outwardly therefrom, said ear having a threaded aperture with a threaded rod mounted in said aperture so as to be movable along an axis normal to said ear such that the stop point of said holding bar can be adjusted.

9. A flue box assembly, substantially as hereinbefore described, with reference to the accompanying drawing.

10. A flue box assembly of the type for use in conjunction with a heating plant, having a housing with an interior diametric opening substantially greater than the exhaust gas inlet to and outlet from the interior of the housing, the housing having an inlet opening for flue gases under pressure to exit from the housing, and the housing including damper means pivotably mounted therein to permit movement between an open position and a closed position, the damper means further having a flue opening positioned therein, the flue opening being diametrically smaller than either the inlet or the outlet openings of the housing, the improvement comprising in combination, a cap pivotally mounted on said housing adjacent the outlet opening thereof, said cap adapted to pivotally move between a closed position occluding the outlet opening of the housing and an open position whereby the outlet opening is unobstructed, said cap further including a holding bar mounted on said cap in juxtaposition with respect to the pivotal mounting point of said cap and extending radially outwardly therefrom, and adjustable counterbalancing means associated with said cap for adjusting the relative pressure necessary to move said cap into an open and closed position respectively in relation to the force exerted by flue gases escaping through said outlet opening, said counterbalancing means comprising a threaded rod associated with and extending radially outwardly from a pivotal mounting point of said cap, said threaded rod including a threaded weight, threadedly carried thereon thereby to be threadedly movable along the length of said rod such that said weight may be moved toward and away from said cap thereby to adjust the relative pressure necessary to move said cap into an open and closed position, said threaded rod being mounted on and carried by said holding bar having said threaded weight threadedly secured thereon for movement along the length of said threaded rod, whereby said cap is adapted to pivotally move to an open position in response to pressure exerted thereagainst by the flue gases exiting through the housing outlet opening, said counterbalancing means permitting the adjustment of the pressure exerted by said cap against the flow of flue gases thereby to adjust the degree by which said cap will open.

Amendments to the claims have been filed, and have the following effect: (a) Claims 1-6 and 10 above have been deleted or textually amended.

(b) New or textually amended claims have been filed as follows: (c) Claims 7 - 9 above have been re-numbered as 2-4 and their appendancies corrected.

1. A flue box assembly for use in conjunction with a heating plant, the assembly including a housing, a cap pivotally mounted on said housing adjacent an outlet passage thereof, said cap being adapted pivotally to move between a closed position in which it occludes the outlet passage of the housing and an open position, and adjustable counterbalancing means associated with said cap for adjusting the relative pressure necessary to move said cap into its open and closed positions in relation to the force exerted by flue gases passing through said outlet passage; said housing has an inlet opening for flue gases and an outlet opening, the housing having a greater internal cross-sectional area than that of either said inlet opening or said outlet opening, there being a damper means pivotably mounted in said housing so as to be able to pivot between an open and a closed position, said damper means having a flue opening therein, and the cross-sectional area of said flue opening being smaller than that of either said inlet opening or said outlet opening; and said counterbalancing means includes a bar mounted on said cap in juxtaposition with respect to the pivotal mounting point of said cap and extending outwardly therefrom, a counterbalance weight being movable parallel to said bar, thereby to adjust to adjust the force required to open and close said cap and thereby. to adjust the degree to which said cap will open, and said weight being threadably mounted on a threaded rod which is carried by said bar.