IE50554B1 - A radiant heating system having an improved burner head - Google Patents

Abstract

A radiant heating system has a plurality of burner heads (10) operatively arranged in a burner branch (12-14) at spaced locations therealong. A combustible gas, having a desired fuel-air mix, is ignited and burned at each burner head. Such combustion heats a downstream length (12) of pipe, which radiates heat within an environment to be warmed. A vacuum pump associated with the system ensures a flow of air products of combustion through the burner branch. The burner head projects into and is arranged within a combustion chamber (13), in series with the radiant pipe. The projected cross-sectional area of the improved burner head is not more than sixty-five percent of the cross-sectional area of the combustion chamber. The improved burner head reduces, within practical limits, velocity attenuation of the flow around the burner head, and also reduces the pressure drop of such flow around the burner head.

Description

The present invention relates generally to the field of radiant-type heating systems, and more particularly to such a heating system having an improved burner head.

Radiant-type heating systems have been developed heretofore. Generally, these systems contemplate the combustion and burning of a fuel within a closed pipe, which, when heated, radiates heat within an area to be warmed.

In one known type of system, a vacuum pump is employed to create a positive flow of inlet air and products of combustion along the pipe to be heated. This flow serves to distribute the heat along the pipe, so that heat may be more uniformly radiated from the pipe. In one system, typically shown and described in U.S. Patent Nos. 3,115,302 and 3,394,886, a plurality of burners may be installed in series in a single burner branch. Normally, the magnitude of the vacuum is relatively small, and significant pressure differentials have existed across each burner head. These large pressure differentials have unnecessarily reduced the number of burners that could he associated with any particular burner branch, and have also adversely affected the flow and temperature gradients within the entire length of pipe.

According, to the present invention there is provided a radiant heating system having a radiant pipe, a combustion ..chamber operatively arranged within said pipe, means for introducing: a;'£estricted amount of air proximate one end of said pipe, vacuum means operatively arranged to reduce the pressure within said pipe proximate its other end so as to create a flew of air in said pipe, a control device operatively arranged to selectively supply a flow of combustible gas having a desired fuel-air mix, ignition means operatively arranged in said combustion chamber for igniting said flow of combustible gas, and a burner head operatively arranged within said combustion chamber and communicatively connected to said control device for supplying said combustible gas to said combustion chamber, in which system the projected crosssectional area of said burner head is not more than sixtyfive percent of the internal cross-sectional area of said combustion chamber.

The improved burner head of the heating system according to the invention minimizes, in a practical way, velocity attenuation of a flow of fluid around the burner head and has the effect of reducing the pressure differential thereacross.

Moreover, the improved radiant-type heating system of the present invention permits an increased number of burner heads to be positioned within a flow path.

Xn order that the invention may be readily understood, an embodiment thereof will now be described, by way of example, with reference to the accompanying drawing, in which: Figure 1 is a longitudinal vertical sectional view of a 25 portion of a radiant heating system embodying the invention and incorporating an improved burner head; and Figure 2 is an enlarged fragmentary transverse vertical sectional view of the system, taken generally on line 2-2 of Fig. 1. - 4 At the outset, it should be clearly understood that like reference numerals are intended to identify the same elements and/or structure consistently throughout the several drawing figures, as such elements and/or structure may be further described or explained by the entire written specification of which this detailed description is an integral part.

Referring now to the drawings, and more particularly to Fig. 1 thereof, the present invention provides an improved burner head of which the presently preferred embodiment is generally indicated at 10, for use in a known type of radiant heating system, generally indicated at 11.

This radiant heating system is more fully shown and described in U.S. Patent Nos. 3,115,302 and 3,394,886, the aggregate disclosures of which are hereby incorporated by reference, and to which the reader should refer if a more complete understanding of such system is needed. Hence, the description of such heating system will be somewhat abbreviated herein.

The radiant heating system 11 includes a downstream radiant pipe 12 having a combustion chamber 13 operatively arranged therein, and an upstream pipe 14 to the right of combustion chamber 13. The upstream pipe 14 is provided with means, such as an end vent 15, for introducing a restricted amount of air proximate the upstream end 16 of the pipe.

In the preferred embodiment, such means 15 may simply be a closure cap or plate 18 provided with one or more apertures 19 through which air may pass to enter the upstream pipe.

In other words, the size of opening 19 is related to the capacity of the burner head 10. 0 5 51 The system also includes vacuum means, such as a vacuum pump (not shown), operatively arranged to reduce the pressure within the burner branch proximate its other end so as to create a flow of gases through the burner branch, this flow being from right to left in Fig. 1, in the direction of arrow 20. In Fig. 1, the burner branch includes radiant pipe 12, combustion chamber 13 and upstream pipe 14, which are series connected.

In Fig. 1, the heating system is shown as further comprising a control device, generally indicated at 21, operatively arranged to selectively supply a flow of combustible gas having a desired fuel-air mix. This control device 21 broadly comprises an enclosing air-tight cover 22. Air may be admitted to the volume within cover 22 through a damper 23 and a filter 24. A fuel supply conduit 25 has its right end connected to a suitable fuel source (not shown). This fuel supply conduit 25 is shown as feeding a burner supply conduit 26 and a pilot supply conduit 28. The burner supply conduit includes a damper-operated valve 29, an electricallyoperated value 30, and a downstream restricted orifice 31.

The pilot supply conduit 28 includes a damper-operated valve 32, an electrically-operated valve 33, and a downstream restricted orifice 34.

When it is desired to fire the burner head valve 30 is electrically opened to permit a flow of fuel from the fuel supply conduit 26 to enter a mixing chamber 35, to which air may be supplied through a variable-sized aperture 36.

The open area of aperture 36 is controlled by the position of plate 38, which may be adjusted for the desired firing rate of the burner. Fuel supplied from pilot supply conduit 28 enters a relatively small mixing chamber 39, to which air is supplied through an aperture 40, the open area of which is likewise determined by the position of a plate 41. From mixing chamber 39, a fuel-air mix is directed along a passageway 42 to be discharged through a plurality of ports 43 surrounding a suitable ignition device, such as spark plug 44. Suitable electrical means are provided to selectively activate spark plug 44 to ignite a pilot flame immediately beneath holes 43. A combustible fuel-air mixture is supplied through passageway 45 to the burner head, later described. Persons skilled in this art will appreciate that control device 21 functions to selectively supply a flow of combustible gas having a desired fuel-air mix, independently of changes in the pressure within the radiant pipe and the pressure within the control device cover 22. As previously noted, additional details on the structure and operation of this control device may be found in U.S. Patent No. 3,394,886.

Referring now collectively to Figs. 1 and 2, the improved burner head 10 is shown as being operatively arranged within the combustion chamber 13 and communicatively connected to the control device 21 for supplying such combustible gas delivered through passageway 45 to the combustion chamber. Hence, burner head 10 has a lower portion 46 which extends downwardly into the combustion chamber and creates an obstacle to otherwise unimpeded flow therethrough. This burner head lower portion 46 is shown as having a planar vertical downstream face 48 provided with a plurality of ports 49 communicating with passageway 45, planar vertical left and right side faces 50, 51 respectively, and a contoured front of upstream face 52. As best shown in Fig. 2, - 7 the wall of the combustion chamber has a cylindrical inner surface 53, and the burner head is indicated as having a concentrically rounded lower or bottom surface 54. Hence, the burner head bottom surface 54 forms a first wall portion which is spaced substantially uniformly from a proximate wall portion of the combustion chamber through an arc of about 100 degrees. The burner head left side wall 50 forms a second wall portion which is spaced non-uniformly from a proximate second wall portion of the combustion chamber. Similarly, the burner head right side wall 51 forms a third wall portion which is also spaced non-uniformly from a proximate third wall portion of the combustion chamber. In the preferred embodiment, the burner head second and third wall portions 50, 51 are substantially parallel to one another, and the inner wall of the combustion chamber is substantially cylindrical. However, this preferred arrangement need not be invariably provided as the present invention contemplates that the shape of these wall portions may be readily changed.

However, the cross-sectional clearance area between the burner head and the combustion chamber wall should not be less than thirty five percent of the internal cross-sectional area of the combustion chamber. In other words, the projected cross-sectional area of the burner head should not be more than sixty-five percent of the internal cross-sectional area of the combustion chamber. This relationship mandates that the clearance area have a certain minimum value, -which is felt to materially affect the design and performance of the system in which such improved burner head is incorporated.

It must be recalled that a typical burner branch is intended to have a number of burner heads projecting into com50554 - 8 bustion chambers spaced therealong. Considering the sources of inlet air, through the end vent and the burners themselves, the vacuum pump is only capable of producing a subatmospheric pressure of 1-2 inches of water at the down5 stream end of the burner branch. Each obstruction extending into the burner branch creates a pressure differential thereacross. Hence, if the pressure differential is relatively large, by a relatively large burner head providing only a relatively small clearnace area between itself and the combustion chamber, this will produce a relatively large pressure differential across such burner head, and therefore limit the number of burners that can be placed in any particular burner branch. In the present invention, it has been empirically determined that by requiring that the projected area of the burner head occupy no more than sixty-five percent of the avail able cross-sectional area of the combustion chamber, the reduction in the pressure differential across such burner head will allow a greater number of burners to be installed in a branch conduit for a given magnitude of vacuum. The shape of the preferred burner head is felt to be particularly advantageous since the pressure differential across such burner head is directly proportional to the square of the velocity of the gases passing through the clearance area. In other words, the improved burner head minimizes, in a practical way, the attenua tion of the velocity of the flow through the clearance area, with a substantial reduction in pressure differential across such burner head. Hence, if such velocity alternation is halved, the pressure differential is reduced by three-quarters.

Claims (7)

1. CLAIMSιΙ. A radiant heating system having a radiant pipe, a combustion chamber operatively arranged within said pipe, means for introducing a restricted amount of air proximate one end of said pipe, vacuum means operatively arranged to reduce the pressure within said pipe proximate its other end so as to create a flow of air in said pipe, a control device operatively arranged to selectively supply a flow of combustible gas having a desired fuel-air mix, ignition means operatively arranged in said combustion chamber for igniting said flow of combustible gas, and a burner head operatively arranged within said combustion chamber and communicatively connected to said control device for supplying said combustible gas to said combustion chamber, in which system the projected cross-sectional area of said burner head is not more than sixty-five percent of the internal cross-sectional area of said combustion chamber.

2. A system according to claim 1 wherein a first wall portion of said burner head is spaced uniformly from a proximate first wall portion of said combustion chamber.

3. A system according to claim 1 or 2 wherein a second wall portion of said burner head is spaced non-uniformly from a proximate second wall portion of said combustion chamber.

4. A system according to claim 3 wherein a third wall portion of said burner head is spaced non-uniformly from a proximate third wall portion of said combustion chamber.

5. A system according to claim 4 wherein said second and third wall portions of said burner head are substantially parallel to one another. - 10

6. A system according to any preceding claim wherein said combustion chamber wall is substantially cylindrical.

7. A radiant heating system substantially as hereinbefore described with reference to, and as illustrated in,the 5 accompanying drawing.