US3820943A

US3820943A - Power burner

Info

Publication number: US3820943A
Application number: US00257110A
Authority: US
Inventors: Lancey W De; M Cooperridge
Original assignee: BECKETT R CORP
Current assignee: BECKETT R CORP
Priority date: 1972-05-26
Filing date: 1972-05-26
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28

Abstract

A power burner for fluid hydro-carbons whose blower housing has a chamber outletting to an air tube mounting a burner head. A tube delivers gas from a manifold extending into said chamber and axially to said burner head. An air restricting static disc perforated throughout is mounted on the gas tube adjacent said chamber building up air pressure therein and creating a uniform air flow through said air tube at reduced velocity. The gas tube is apertured in said chamber and with a scoop, receives primary air to mix with the gas passing through said gas tube. A pilot flame assembly is mounted in the air tube adjacent the burner head and a pilot air intake tube delivers primary air from said chamber to stablize the pilot flame. The burner head assembly includes a concave centrally apertured plate receiving the gas tube and having radially extended slots therethrough to deliver uniform streams of air. A concave diffuser cap forwardly of said plate reverse deflects and radially diffuses the flowing gas and primary air uniformly between the streams of air flowing through said plate for efficient combustion. A screen forwardly of said plate entrains the flame of combustibles slowing its forward movement. The gas manifold has an apertured partition seat between its inlet and outlet, and a pair of orifice plates with different openings are spring biased apart and removably positioned in the manifold, with one orifice plate seated in the partition, the orifice plates being reversible depending upon which size orifice plate is required for a selected fuel.

Description

United States Patent [191 De Lancey et al.

[ POWER BURNER [75] Inventors: Warren H. De Lancey, Elyria; Myron T. Cooperridge, North Royalton, both of Ohio [73] Assignee: R. W. Beckett Corporation, Elyria,

Ohio

[22] Filed: May 26, 1972 [21] Appl. No.: 257,110

Primary Examiner-Edward G. Favors Attorney, Agent, or FirmCullen, Settle, Sloman & Cantor t [5 7 ABSTRACT A power burner for fluid hydro-carbons whose blower housing has a chamber outletting to an air tube "[111 3,820,943 [45] June 28,1974

mounting a burner head. A tube delivers gas from a manifold extending into said chamber and axially to said burner head. An air restricting static disc perforated throughout is mounted on the gas tube adjacent said chamber building up air pressure therein and creating a uniform air flow through said air tube at reduced velocity. The gas tube is apertured in said chamber and with a scoop, receives primary air to mix with the gas passing through said gas tube. A pilot flame assembly is mounted in the air tube adjacent the burner head and a pilot air intake tube delivers primary air from said chamber to stablize the pilot flame. The burner head assembly includes a concave centrally apertured plate receiving the gas tube and having radially extended slots therethrough to deliver uniform streams of air. A concave diffuser cap forwardly of said plate reverse deflects and radially diffuses the flowing gas and primary air uniformly between the streams of air flowing through said plate for efficient combustion. A screen forwardly of said plate entrains the flame of combustibles slowing its forward movement. The gas manifold has an apertured partition seat between its inlet and outlet, and a pair of orifice plates with different openings are spring biased apart and removably positioned in the manifold, with one orifice plate seated in the partition, the orifice plates being reversible depending upon which size orifice plate is required fora selected fuel.

21 Claims, 13 Drawing Figures PATENTEBMMM slezoe aia SHEET 1 m 1 POWER BURNER BACKGROUND OF THE INVENTION This invention relates to new and unique principles which greatly improve the ability of power gas burners to provide steady combustion and constant BTU input irrespective of the combustion chamber pressure. By combustion chamber pressure is meant the pressure in the zone of a furnace where the combustion process is taking place. Depending on the type and design of the particular device in which combustion of gas is taking place, coupled with the stack or chimney draft conditions, the pressure in the combustionzone can vary from sub-atmospheric to substantially aboye atmospheric pressure.

In all types of gas burners the gas is delivered to the burner metering means at a carefully regulated pressure. This metering means, combined with regulated gas pressure, is the method in universal use to insure the correct BTU input on all types of gas burners.

This method of controlling the gas input has been generally satisfactory over the history of the burners, particularly in the lower input ranges. However, it does have one substantial deficiency. It is an established premise that with closely regulated gas pressure of a known gas, coupled with a fixed metering means of a known size and configuration, the flow rate of the gas will be a constant.

This premise is true if the pressure on the downstream side of the metering means is always at exactly atmospheric pressure. If the downstream pressure is below atmospheric pressure, the gas flow rate will be greater; if the downstream pressure is above atmospheric pressure, the gas flow will be reduced.

On applications where an exact gas input is required, this deficiency presented severe problems. Many unique and elaborate innovations were applied in overcoming this problem, all of which were quite expensive to produce and/or maintain.

Another problem encountered in the evolution of furnace (the word furnace in this description applies to all types of combustion devices) design was as the need for smaller and more compact furnaces evolved, it became impossible to continue the use of atmospheric burners.

An atmospheric burner in general is one in which the gas is introduced into a venturi tube by a metering means at a pressureabove atmospheric pressure. The gas velocity then entrains or induces a certain portion of combustion air into the venturi. This portion of air is commonly known as primary air. The pressure in the furnace combustion zone is below atmospheric pressure, so there is a natural flow of air through the furnace. This natural flow of air provides the additional air to complete the combustion process. This flow is called secondary air.

As newer and smaller designs evolved, a point was reached on many furnace designs in which there was no longer a natural draft (sub-atmospheric pressure) in the combustion zone. When that point is reached it is no longer practical, and in many cases is impossible, to use an atmospheric burner. It then became necessary to create a powered means of providing the correct amount of total combustion air. This is typically done by the use of an electric motor, or turbine driving a fan or blower to overcome the draft deficiency.

With a power gas burner (the use, of a driven fan or blower to provide combustion air), the ability of a burner to provide a definite controlled input became worse. In many cases the pressure in the combustion zone was now above atmospheric pressure. This posi tive pressurebiased the regulated gas pressure and reduced the gas flow rate through the metering means. In addition, most power burners have the metering means located in the static pressure zone of the blower housing or the duct that delivers the combustion air to the combustion zone. The pressure in these areas'is always higher than that of the combustion zone. This pressure too can make a material reduction in gas flow rates through the metering means.

The design of most power gas burners of a given size and configuration incorporates the ability to fire over a 3 to 1 range of rates, and in some cases as much as an 8 or 10 to 1 range. When burners of this type are fired at the low end of their range, there is generally little problem encountered in the reduction of gas flow caused by the static pressure encountered in the blower housing and air duct. However, when the same physical sized burner is fired at the top end of its range, the air flow may be 8 to 10 times as great. This will always creat a greater static pressure in the blower housing and air duct, resulting in a greater percentage of reduction in the gas flow rate through the gas metering means. With the present state of the art, there does not appear tobe any satisfactory and/or inexpensive means of overcoming this condition.

This invention relates to a technically sound and inexpensive means of overcoming the reduction of gas flow created by the static pressure encountered in the blower housing and air duct system, as well as the pres sure in the combustion zone of the furnace.

This invention utilizes known fan or blower laws and, coupled with appropriate design engineering, the variation in gas metering means flow rates is for all practical purposes reduced to zero.

In addition, when using a burner of a given size and configuration incorporating these principles and operated over its entire firing rate range, the ratio of premix or primary air to the gas input is essentially a constant. This condition is true if the pressure in the furnace combustion zone is below or above atmospheric pressure. The statement is based on the assumption that under either condition the burner is fired at identical rates and adjusted for the same combustion efficiency.

When this burner is adjusted for the correct combustion efficiency, the difference between the pressure in the premix tube and the pressure in the combustion zone will remain essentially the same, irrespective of the pressure in the combustion zone. The pressure in the premix tube is always the higher.

This constant premix air-gas ratio is accomplished by using the velocity pressure off the periphery of the fan or blower wheel rather than using the static pressure in the blower housing or air duct.

The present invention relates to power burners adapted to use fluid hydro-carbons as for example, natural gas or liquified petroleum and which will operate and be stable under a variety of unfavorable conditions. Such burners are currently and widely used to replace liquid fuel burners in mobile homes and generally to operate under conditions where no original provisions were made to provide a uniform natural draft.

There are two types of gaseous fuels in general use today. One of these is natural gas which is a complex mixture of a variety of gases occurring naturally at wells usually drilled to obtain petroleum. Such gas has a heating content when burned under standardized conditions of about 1,025 BTU. per cubic foot. The other gas in common usage is referred to as L.P. (for liquifled petroleum), and is a mixture of the light ends of petroleum known as propane, which has been liquified through pressure to a compact form for ready transportation. The heating content of LP. per cubic foot is more than double that of natural gas or close to 2,500 B.T.U.

It is, therefore, an object of the present invention to provide a power gas burner by which one is able to burn either type of gas equally well and be capable of conveniently shifting from one to the other. In general a power gas burner must perform the following functions in a highly reliable manner as set forth in these objects:

It is an object of the present invention to provide in the power gas burner a source of air for combustion under sufficient pressure to overcome the variation of firing conditions commonly encountered, with only minor variations in volume. This is accomplished by a blower that discharged into an air tube wherein the combustion air is conducted to a burner head.

It is a further object to provide a connection to a gas main to receive natural gas or LP. gas under low pressure. The actual pressure of natural gas may fluctuate considerably so a means of regulation down to a uniform pressure is provided in the gas valve. UL. and A.G.A. require the gas valve combination to have LP. regulation in addition to the tank regulator. LP. gas has its own source from a nearby tank hich has to be equipped with an accurate pressure regulator. It is, therefore, an object of this invention to provide a simple orifice adjustment by which change over can be effected between natural gas and LP. gas.

It is a further object to provide for the metering of the supply of gas into a gas tube for delivery to the combustion area and with a mechanism for introduction of primary air into the gas flow to make it more combustible. It is, therefore, a further object to provide a positive novel mechanism for the pressure introduction of primary air into the main gas flow within the burner air tube to the combustion area.

The mixture of gas and primary air is now mixed with the main air supply and ignited either by a standing pilot consisting of a continuous small gas flame or by an electric spark. The gas and swiftly moving air do not tend to mix readily, and the means of doing this is one of the important features of the present invention. The flame tends to blow away from the head and otherwise have an unstable and rapidly moving front, which causes noise and pulsation. It is an object of this invention to mix the air and gas uniformly over a considerable area in order to obtain low forward velocities with a compact fire, and at the same time to position the fire origin or flame front so as to be fixed and stable.

It is a further object to provide a continuously buming gas pilot flame for igniting the main burner and to utilize an orifice-to increase velocity and inject primary air for forwardly projecting the pilot gas flame into the main gas supply as it issues from the burner mixing head for providing positive ignition of the main flame. The primary air supply-to the pilot flame is thus augmented when the burner is running by providing an air scoop facing the origin of the air movement within the air tube, to thus provide a pilot flame which is stable and more intense for preventing vibrations and fluctuations which might otherwise occur due to the high air velocity surrounding it.

These and other objects will be seen from the follow ing specification and claims in conjunction with the appended drawings in which:

FIG. 1 is a front elevational view of the present power burner looking directly into the burner head.

FIG. 2 is a longitudinal section taken in the direction of arrows 2--2 of FIG. 1.

FIG. 3 is a rear elevational view of the burner shown in FIG. 1.

FIG. 4 is a fragmentary plan view of the gas tube, pilot flame assembly.

FIG. 5 is a fragmentary section taken in the direction of arrows 5-5 of FIG. 2.

FIG. 6 is a front elevational view of the burner head with the screen removed.

FIG. 7 is front elevational view of the burner head with screen in position.

FIG. 8 is a vertical section of the gas manifold and orifice assembly.

FIG. 9 is a side elevational view of one of the two gas orifices shown in FIG. 8, but on an increased scale.

FIG. 10 is a fragmentary schematic side view of a blower housing, air tube and burner head.

FIG. 11 is a similar view from the opposite side.

FIG. 12 is a schematic side view of a burner head and diffuser.

FIG. 13 is a schematic view of the pilot flame and ram jet air assembly.

It will be understood that the foregoing drawings illustrate merely a preferred illustrative embodiment of the invention, as other embodiments are contemplated within the scope of the claims hereafter set forth.

Referring to the drawing, the force air burner assembly generally indicated at 11, FIG. 1, includes housing 13, FIG. 2, with blower motor 15 mounted upon one end thereof including shaft 17 projected into said housing mounting a sirocco type of centrifugal blower wheel Said housing includes the inwardly extending baffle 21 within pressure air chamber 23 which is closed by the cover and manifold mounting plate 25 suitably secured to said housing.

Within the outlet 29 in said housing is projected and mounted the air tube 27 which extends laterallyof said housing. The apertured mounting flange 31 on the housing provides a convenient means for mounting the power burner upon a furnace in such a manner that the burner head assembly 33 is projected forwardly thereinto.

As shown in FIG. 3 and FIG. 1, the junction box 35 is mounted upon said housing upon the opposite side thereof from motor 15. This box contains a step-down transformer and a single pole-single throw relay, not shown. The transformer provides three volts for illustration for the pilot flame ignitor and 24 volts for the thermostat circuit which operates the relay and the conventional gas valve. Though not shown in the drawing, the relay coil when energized, upon pulling in of the relay armature is adapted to close the volt circuit through the blower motor. At the same time, another 24 volt circuit through the gas valve is completed pilot is lighted and its associated thermo-couple energized. On the top of the junction box there is a terminal board for connecting wires to the thermostat and to the ignitor. The circuit to the ignitor is normally open and can be energized by depressing a control button on the terminal board which closes a switch while the pressure is maintained.

The foregoing control mechanism is reasonably conventional in power burners, gas fired or oil or otherwise and, therefore, the full detail and description thereof is omitted.

As shown in FIG. 3, however, the junction box is anchored at 37 to a portion of the air inlet boot 38 upon housing 13 and which includes a series of adjustable air inlets 39 for determining the flow of air into the blower housing, depending upon the desired firing conditions.

The present motor is of the two pole type which revolves at about 3,300 R.P.M. under full load and 120 volt input. Within the structure of the motor is a centrifugal switch which is normally open, but when the motor speed exceeds 2,500 R.P.M., this switch closes and forms part of a 24 volt circuit to the solenoid valve in the main combination gas valve. There can be no flow of gas, therefore, unless the motor is substantially up to speed and thus full air delivery is assured. Regulation of the air intake thus determines the firing rate which can be fixed or adjusted as desired. The air volume can, thus, be set to five proper combustion within the firing range of the burner which is the present case is 50,000-200,000 B.T.U. This construction is conventional in burners of this type and thus the details thereof are omitted.

Gas valve 41 is provided with a gas intake 43 to which may be connected natural gas or L.P. (liquified and the metering means 209 under all firing rates of pressure conditions encountered in the blower housing, air duct, or furnace combustion zone, FIGS. 10, 11 and 12.

Due to the velocity pressure or ram air effect off the blower wheel 202 the pressure in the premix air tube between the eductor and the burner head diffuser 206 is always at essentially the same positive pressure above that encountered in the furnace combustion zone, irrespective of the firing rate.

Referring to FIGS. 8 and 9 within bore 65 of manifold body 63 there is provided a partition 67 which has a tapered aperture providing an orifice seat. The orifice valve disc 69, shown on increased scale in FIG. 9, is seated in said aperture.

Said orifice disc has an annular tapered undersurface 71 providing a seat for registry with thepartition valve seat 67 and includes a plurality of axially extending arcuate legs 73. Said disc has a central fuel control aperture 75 whose diameter is predetermined, depending upon the amount of fuel to be metered through the manifold as well as the type of fuel, whether it be natural gas or L.P., or other gas.

A second orifice disc 77 of the same construction as the first orifice disc is spaced laterally of said first orifice disc and includes a central aperture 79 which is of petroleum) or other fluid hydro-carbon to which the present power burner is adapted.

Upright manifold 45, FIGS. 2 and 8, includes a body 63 with an inlet bore 65 adapted for communication with and support of said gas valve 41. Body 63 at its lower end includes mounting flange 47 which bears upon housing cover 25 and is suitably secured and sealed thereto. Said flange retainingly engages annular support flange 51 of gas tube 49 which is in communication with outlet 85 of said manifold and extends downwardly into pressure air chamber 23 and laterally outward through air tube 27.

Referring to FIGS. 2 and 4, primary air inlet 53 is provided upon the undersurface of gas tube 49 within chamber 23 and is in the form of an elongated slot,

through a series of apertures could be provided.

Bifurcated air scoop 55 projects upwardly over the opposing sides of the gas tube, is secured thereto by fasteners 57 and includes outwardly diverging air intake 59. Air under pressure within chamber 23, which is greater than the pressure of the gas flowing through the gas tube, is injected into the flowing gas. Due to the close relationship between the blower 202 and premix air tube 204, FIG. 10, the eductor scoop 205 senses the velocity pressure off the blower wheel before this pressure is converted to static pressure in the blower housing.

The eductor 205 creates a slightly sub-atmospheric pressure in the premix air tube between the eductor a different size, as for example, smaller than the aperture of the first orifice disc. The second orifice disc also includes corresponding legs 73 which are opposed to the legs of the first orifice disc 69.

In the assembly shown in FIG. 8, the respective prongs or legs of

orifice discs

69 and 77 project into the opposite ends of spring 81. With orifice disc 69 seated within partition seat 67, the nut 83 which receives the second orifice disc is threaded into position within manifold body 63.

This provides a means of controlling the flow of gas from the valve into the inlet bore 65, through aperture 75 in orifice disc 69 and to the outlet 85 for direction into gas tube 49 of FIG. 2.

In the above embodiment, for example, the aperture 75 within the seated orifice disc 69 is larger with respect to the aperture 79 in the second orifice disc. This is because in the illustrative embodiment, natural gas is employed which provides less BTU. per cubic foot of heating than L.P. Accordingly, when it is desired to use L.P. fuel instead of natural gas, it is merely necessary to manually remove nut 83, reverse the two

orifice discs

69 and 77 end to end with respect to said nut and reintroduce the assembly including the spring so that the second orifice disc 77 is then seated within the tapered seat of partition 67. Here the orifice 79 is smaller than the orifice of the first valve disc since the LP. gas has higher heating quality and better restricts the flow of LP. gas into the gas tube 49.

This provides a simple means by which the present power burner may be switched easily from natural gas to LP. and visa-versa.

Referring to FIG. 2, the restrictor static disc 87 has a hub 89 mounted and securing upon gas tube 49 adjacent the inlet end of air tube 27. Said disc has a series of concentric rows of

different size apertures

93, 94 and 95 for restricting the flow of pressure air from chamber 23 into and through air tube 27.

By regulating diameter of the

apertures

93, 94 and 95, said restrictor disc provides a uniform cross section of pressure air flowing through the air tube, at a uni- Pilot light flame assembly 97 includes a frame 99 mounted upon the air tube inwardly of the restrictor static disc and is secured to disc 87. This securing includes an elongated thermo-couple nut 1111 upon the thermo-couple lead 103 to thermo-couple 105. The latter is supported upon and projects through the pilot frame 99 and forwardly thereof to a position adjacent to and under the control of a branch of the pilot flame.

The pilot orifice 128 and forwardly arranged venturi tube 107 FIG. 13 extends through and is supported upon pilot frame 99 and includes an air inlet adjacent the pilot orifice and an outlet 109 facing into and closely adjacent the flame spreader 111, FIG. 5.

Said spreader includes outlet 113 for the pilot flame which projects axially parallel to and adjacent the gas tube outlet 61 within the upright pilot shield 1 15. Said fitting is secured to the pilot shield and forms a part of the pilot light flame assembly.

The flame spreader 117 is so formed as to direct a branch of the forwardly extending pilot flame upwardly to heat the thermo-couple 105 for operation in a conventional manner to control operation of a solenoid controlled gas valve.

Upon one side of the pilot flame orifice tube, there is provided a pilot air inlet duct 119 which is suitably secured by fasteners to the pilot light flame assembly and which extends to the corresponding aperture in the restrictor disc 87 and has an inlet 121 FIG. 2 for receiving primary air directed into the air tube 27.

The forward down stream end of duct 119 outlets into the pilot shield closely adjacent the gas orifice outlet 128 to the pilot flame for the purpose of supplying second primary air thereto, note FIG. 13.

The reason that the pilot flame is stabilized is because the ram air effect acting on the inlet of the pilot shield 119 balances out the static pressure effect encountered on the area of the open face of the heat guide when the blower is running. This balancing effect must be maintained throughout the operating range of the burner. If the static pressure ram air effect gets out of balance too far in either direction, the pilot burner will either starve out for air or blow out.

This hardens or stabilizes the pilot flame so as to maintain a steady burning forwardly extending flame and to improve its igniting efficiency despite the streams of pressure air flow through the burner head. This eliminates objectionable pulsations and vibrations in the flame front designated schematically at 153, FIG. 2.

Thus, the primary air supply to the pilot flame is augmented when the main burner is running by the air scoop or inlet 121 which faces the origin of air movement through tube 27. Thus, when the burner is operating, the pilot flame becomes more intense and harder. This is most important to prevent it from being disturbed by the high air velocities which surround it and to obtain uniform output on the thermocouple.

Projected within the lower end of the pilot shield 115 is a hot wire ignitor 123 which employs 3 volts, for example, to which is connected an ignitor lead wire 125 which extends rearwardly through the restrictor disc 87 and is connected into the junction box 35 for manual control.

While a hot wire is described as one form for igniting the pilot flame, this is merely illustrative and is reasonably conventional in construction, and further detail is omitted.

BURNER HEAD ASSEMBLY Within the down steam end of air tube 27 is positioned a generally concave burner head plate 131 whose outer annular flange 133 extends around the outlet end of said air tube and is affixed thereto.

The inner annular portion of the burner head plate 131 is centrally apertured to receive the gas tube 49 and is reversed curved axially forward defining a throated flange 135 which snugly registers against the outlet end of said gas tube.

As shown in FIG. 6, within the outer portion of the burner head plate 131 are a series of elongated arcuate slots 137 in alignment adjacent the inner wall of the air tube to provide for the flow of a solid air annulus out from the burner head. This annulus surrounds and entrains the flame front 153, shown in dotted lines FIG. 2. Plate 131 includes a series of elongated radial slots or jet air outlets 139 which are arranged within the path of pressure air moving through the air tube for delivering a series of streams of forwardly moving air through the burner head in a uniform pattern for making up the main body of the flame front 153, when mixed with gaseous fuel.

The concave gas diffuser cap 141 is spaced forwardly of plate 131 and likewise forwardly of and in axial opposition to the outlet 61 of the gas tube for deflecting the flowing gas and its primary air radially outward and reversely. The diffused gas moves along the outer surface of curved portions of burner head plate 131 for uniform diffusion and radial projection into and between the streams of air passing through the jet air outlets 139 in said plate. This provides a uniform homogenious mixture of gas and air for ignition by the pilot flame.

In the illustrative embodiment, the diffuser cap includes three legs 143, FIG. 2, which extend and are secured to plate 131 to provide suitable passageway for the laterally moving primary air and gas mixture into and between the streams of forwardly flowing pressure air for mixing therewith.

The burner head assembly includes a flame restricting screen 145, FIGS. 1 and 7 which is peripherally secured to plate 131 inwardly of its air flow slots 137. Said screen extends across plate 131 forwardly thereof and is suitably apertured to receive the forwardly ex tending diffuser cap 141, FIG. 7.

Said screen includes a plurality of apertures 147 and the central aperture 151 to receive the diffuser cap 141 for entraining the flame 153, for slowing down the velocity of the forwardly moving burning gases and pressure air, retaining the flame front so as not to extend out too far longitudinally for the most efficient heating purposes and for maintaining a uniform flame pattern.

Thus, the forwardly moving mixture of gas and primary air through the outlet 61 of the gas tube 49 is uniformly diffused radially outward by the diffuser cap to move between the jet streams of pressure air flowing through plate 131 for uniform mixing therewith and for I 9 ignition by the axially projecting pilot flame from the pilot flame outlet 113, FIG. 5. I

The gas and primary air as it comes out the air tube through the burner head assembly has been earlier deflected by the diffuser cap 141 radially outward in a uniform sheet over the ignition port into and between the series of radial air slots 139 and the jets of air passing therethrough. The gas air mixture is surrounded ultimately by the annulus of of air which is delivered through the plate outlet slots 137 with the flame entrained by the perforated screen 145. This provides for a very stable flame, a compact fire and-a low forward velocity.

Referring to FIG. 5, the

apertures

93, 94 and 95 are arranged in such a manner and of such varying size as to assure even distribution of air uniformly through the cross section of the air tube before it arrives at the combustion head. It is most important that a relatively constant velocity be established across all points in the cross section of the air tube so that a combustion head with relatively low air resistance can be used. This permits the combustion air to pass through the apertures of the head uniformly with relatively low velocity which sharplyvreduces noise and unsteadiness of the fire.

When the air leaves the blower wheel, the maximum pressure is in the upper left hand corner of chamber 23, looking from down stream view. Accordingly, the perforations 95 are smaller at this point, as shown in FIG. 5.

The air pattern leaving the blower wheel may vary from burner to burner depending upon the size and type of blower wheel, scroll-type and amount of air being handled. Perforations in the static disc are distributed in size so that in any given situation, air velocity down stream arriving at the combustion head as measured by a sensitive manometer, is substantially uniform at any point in the cross section of the air tube and is used in conjunction with the relatively open combustion head, permitting low velocity air. This function has equal application on oil firing and, accordingly, it is regarded as equivalent in the present invention that the fuel employed referred to as a fluidized hydro-carbon may be natural gas, LP. or oil.

Uniform air'velocity throughout a burner head is an important design consideration in any combustion head, either gas or oil, present or past designs.

FIGS. 10, 11 and 12 are schematic illustrations of the present invention.

FIG. 10 shows a cross section of a typical blower housing 201 and air duct configuration 203, with a typical relationship established between the blower or fan 202 and the premix air tube204. In addition, it shows the relationship between the premix air tube and the burner head 207.

FIG. 10 shows the close relationship between the blower wheel and the premix air tube with an eductor or asperator 205 attached to the premix air tube. 209 shows a gas metering means located outside the blower housing. This can be located quite remote from the blower housing. 210 shows a typical gas pressure regulator. Even though the premix air tube 204 is located in the static pressure zone of the blower wheel, the close proximity of the eductor 205 to the blower wheel periphery creates a condition whereby the eductor senses essentially the velocity pressure off the blower wheel and before this pressure is converted to static pressure in the blower housing.

blower wheel 202, the pressure in the premix air tube between the eductor and the burner head diffuser 206 is always at essentially the same positive pressure above that encountered in the furnace combustion zone, irrespective of the firing rate.

FIG. 10 shows a cross section of the burner head 207 and attached diffuser 206 with the premix air tube 204 entering the center of the head and extending a short distance through it. The diffuser is located'concentric with the premix air tube and spaced a distance away from its end. The purpose of the diffuser is to uniformly distribute the premixed air and gas across the face of the burner head.

FIG. 12 shows a typical burner head 207 with attached diffuser 206. This view illustrates the means used to uniformly distribute the premixed air and gas across the face of the burner head.

As a general rule, a burner head with fixed size openings only has a practical firing range of 2 to 1. This means that a given physical size burner with a firing rate range of 8 or 10 to 1 would require four or five similar burner heads with varying size air openings to accommodate the wide variation in air delivery required.

FIG. 11 shows a typical means of adjusting the volume of combustion air that is required for any firing rate within the scope of the specific burner.

211 shows a typical adjustable air wicket or air gate that is used on most burners to control the volume of combustion air. We are assuming that the blower wheel or fan that is used can deliver sufficient air volume to fire the highest gas input with some reserve of unused air potential, as well as being adjusted down to cover the lowest firing rate.

To illustrate the constant air-gas rate principle, as typical conditions we will take a burner operating at 100,000 BTU per hour and the same burner operating at 300,000 BTU per hour. Any rates from the lowest to the highest gas burner capacity required for firing the furnace could be used.

We will assume first of all that in both cases the burners are operating at the same sub-atmospheric pressure in the furnace combustion zone and are adjusted for the same combustion efficiency.

For the 100,000 BTU per hour rate a burner head is selected whose openings, for passage of secondary air, are correct for that input. The air gate 211 is adjusted for the correct combustion efficiency. We now have a certain static pressure in the blower housing and air duct and a certain velocity pressure off the periphery of the blower wheel.

We now make the required burner changes for firing at 300,000 BTU per hour. Since burner heads with fixed air openings generally have only a 2 to 1 ratio, we must select a head 207 with larger air openings. The gas metering means 209 must be adjusted or changed to three times the initial rate and the air gate must be adjusted so that the blower wheel 202 can deliver three times the volume of combustion air.

In both cases if the burner heads are correctly sized, the air pressure drop across the heads will be the same.

If the pressure drop across the heads is the same, we will have essentially the same static pressure in the blower housing and air duct. However, since the blower wheel is now required to deliver three times the volume of air, the velocity pressure off the blower wheel will be substantially greater than at the lower firing rate. This increased velocity pressure enables the eductor 205 to handle the increased gas flow and primary air to maintain the basic premix air-gas ratio.

We now install the same burners in furnaces that operate with pressures higher than atmospheric pressure in the combustion zone. In both cases the higher pressures encountered in the furnace combustion zones are overcome by opening the air gate 211 on the burner. The increased air opening increases the static pressure in the blower housing and air duct and overcomes the increased furnace pressure. The increased air openings increase the velocity pressure of the blower wheel and enable the eductor to overcome the increase in furnace pressure. When the burners are now adjusted for the same combustion efficiency as before, the premix airgas ratio will become essentially the same as before.

NOVEL CONCEPTS l. The principle of using velocity pressure instead of static pressure for primary air-gas mixing in a power gas burner.

2. The use of an eductor to create a slight asperating effect on the gas metering means.

3. The use of an eductor to create a higher positive pressure in the premix air tube down stream of the eductor than is possible when static pressure only is used.

4. The use of velocity pressure combined with an eductor to maintain essentially a constant premix airgas ratio throughout the entire firing rate range of the burner.

4a. The use of velocity pressure combined with an eductor to create an asperating effect on the metered gas flow.

4b. The use of velocity pressure combined with an eductor to create a higher gas tube pressure than the pressure in the combustion zone.

5. Extending the premix air tube through the burner head and diffusing the air-gas mixture on the face of the head instead of behind the head as is common practice.

6. Extending the premix air tube through the burner head rather than ending it behind the burner head to prevent the static air pressure in the housing and combustion air tube from biasing the metered gas flow and thereby reducing the burner input.

7. A new and novel method for quick orifice changeover from one type gas to another. This consists of a coil spring with an orifice plate attached to each end with the orifices sized for the correct BTU input. (orifice sizes are determined by the BTU content of the gas, regulated pressure and specific gravity of the gas.)

8. The use of ram jet effect to provide additional air to the airated pilotand stabilize it when the burner is running This makes possible the placing of the pilot in the air tube.

9. In conjunction with the static disc, the perforations therein give a highlyuniform air flow in the air tube, and permit the use of low resistant burner heads.

Having described our invention, reference should now be had to the following claims.

We claim:

1. In a power burner for fluidized hydro-carbons, a blower housing having an air inlet, a cover, and a pressure air chamber with a lateral outlet;

a motor operated blower in said housing outletting into said chamber;

a laterally extending air tube at one end projected into said outlet and secured to said housing, with its outer end open;

an apertured burner head assembly mounted over the air tube outer end;

a gas manifold on said cover having an outlet through said cover;

a gas valve on and connected to said manifold adapted for connection to a source of fluidized hy dro-carbon;

an elongated gas tube within said chamber at one end connected to said manifold outlet, extending axially through said air tube and at its outer end extending through and concentric with said burner head assembly;

and an air restrictor static disc centrally mounted on said gas tube and within and spaced from the wall of said air tube, and having a series of perforations therethrough for building up air pressure in said chamber and for delivering through the cross section of said air tube a uniform air flow to said burner head.

2. In the power burner of claim 1, there being a primary air inlet into said gas tube located in said pressure air chamber; and an air scoop mounted on said gas tube enclosing said air inlet and having an outwardly diverging air intake to facilitate the flow of air under velocity pressure into said gas tube for mixing with gas flowing therethrough, said scoop sensing and responsive to the high velocity of air from the blower forcing primary air into the gas tube by a ram jet effect.

3. In the power burner of claim 1, a pilot flame assembly mounted on said gas tube, including a pilot gas tube at one end connected to said gas valve, pilot gas orifice extending forwardly and terminating in a venturi .tube having an air inlet and having an outlet adjacent said burner head assembly; a hollow upright pilot shield receiving said venturi tube including a pilot gas spreader with a plurality of flame outlets; a pilot air inlet duct parallel to and mounted on said venturi tube, at one end having an inlet adjacent said air restrictor disc and an outlet connected to said venturi inlet for the ram jet flow of primary air under pressure to render the pilot flame stable and more intense, eliminating flicker and pulsation.

4. In the power burner of claim 3, a hot wire ignitor assembly arranged below and secured to said pilot shield adjacent said pilot tube outlet.

5. In the power burner of claim 1, said burner head assembly including a concave burner head plate on the end of said air tube and extending thereinto with its central portion apertured and curved forwardly in engaging registry with and supportably receiving said gas tube adjacent its outlet; there being a series of elongated radial air outlets formed through said plate throughout its surface, and an inwardly opening concave diffuser cap spaced forwardly of and in opposition to the gas pipe outlet and forwardly of said burner headplate and secured thereto; for reverse deflecting and radially diffusing the flow of combustion gas and primary air to move uniformly and radially outward between the streams of air flowing through said burner head plate.

6. In the burner of claim 5, a screen within the air tube outlet end peripherally secured to an outer annular portion of said burner head plate and extending across and spaced forwardly of said radial air outlets for entraining the flame flowing down its forward velocity and maintaining a stable flame front.

7. In the power burner of claim 5, there being a series of elongated arcuate air flow slots formed through said burner head plate adjacent the wall of said air tube and extending around said plate, providing an annulus of moving flame confining air.

8. In the power burner of claim 1, said gas manifold having a body with an inlet bore connected to said gas valve; a partition between said inlet bore and manifold outlet having an aperture; an orifice disc having a central opening seated in said aperture for regulating the flow of gas to said manifold outlet; a nut threaded into said body spaced from said partition; and a compression spring interposedbetween said nut and said orifice disc.

9. In the power burner of claim 1, said gas manifold having a body with an inlet bore connected to said valve; a partition between said inlet bore and manifold outlet having an aperture; an orifice disc having a central opening seated in said aperture for regulating the flow of gas to said manifold outlet; a second orifice disc having a central opening smaller than the opening in said first orifice disc; a compression spring interposed between and spacing said discs; and a nut receiving said second orifice disc and threaded into said body; whereby depending upon the nature of the fuel, the positioning of said orifice discs can be reversed by temporarily removing said nut so that the second orifice disc is seated within said partition aperture.

10. In the power burner of claim 9, the undersurface of said orifice discs being tapered for registry with said partition aperture; and a series of axial prongs on said discs extended inwardly towards each other supportably projecting into the ends of said spring.

11. In the power burner of claim 10, said partition aperture being tapered.

12. In the power of claim 2, a gas metering means in said manifold, said primary air intake and air duct functioning as an eductor creating a sub-atmospheric pressure in the premix air gas tube between said air intake and metering means creating an asperating effect on said metering means.

13. In the power burner of claim 2, said primary air intake and air scoop functioning as an eductor creating an increased positive pressure in the premix air gas tube down stream of said eductor.

14. In the burner of claim 2, said gas tube with concentric primary air duct functions as an eductor, the use of velocity pressure creates a most efficient eductor creating a slight subatmospheric pressure in said gas tube maintaining substantially a constant premix airgas ratio throughout the entire firing range of the burner irrespective of the combustion chamber pressure.

15. In a power burner, a gas manifold having a body with an inlet adapted for connection to a gas valve connected to a source of fluidized hydro-carbon, and an outlet;

a partition between said inlet and manifold outlet having an aperture;

and orifice disc having acentral opening seated in said aperture for regulating the flow of gas to said manifold outlet; a second orifice disc having a central opening smaller than the opening in said first orifice disc; a compression spring interposed be tween and spacing said discs; and a nut receiving said second orifice disc and threaded into said body; whereby depending upon the nature of the fuel, the positioning of said orifice discs can be reversedby temporarily removing said nut so that the second orifice disc is seated within said partition aperture, providing thereby a quick orifice changeover from one type gas to another, said orifice sizes being determined by the BTU content of the gas, regulated pressure and specific gravity at the gas.

16. In a power gas burner,

a housing;

a blower wheel in the housing;

a motor connected to the blower;

a tube connected to said housing to conduct the air to a point of combustion;

a gas tube extending through said air tube and connected to a metered supply of gas for delivery of same to the combustion zone;

and an air intake in said gas tube for delivering primary air into the gas tube, shaped to provide entrance of velocity pressure air from the blower wheel; the air and gas mixture moving through said gas tube to the combustion zone without creating any back pressure on the gas flow and its metered volume;

an orifice assembly for measuring the main gas flow and consisting of at least two different sizes of orifices arranged for selectively restricting the flow of gas from a pressure regulator to the combustion zone; and a means for rapidly and conveniently switching one orifice for the other.

17. In the power gas burner as described in claim 16, and with the access to the orifice being located outside of the blower housing and air tube.

18. A power gas burner as described in claim 16, said gas orifices being connected by a spring and arranged so that one restricts the gas flow at a time, but can be readily changed by reversal of the orifices end to end.

19. In a power gas burner,

a housing;

a blower wheel in the housing;

a motor connected to the blower;

a tube connected to said housing to conduct the air to a point of combustion;

said power gas burner having a standing pilot for igniting the air-gas mixture at the combustion zone;

said pilot being of the primary air injection type, and having its primary air inlet arranged so that the air movement from the blower increases the primary air inlet pressure.

20. In a power gas burner,

a housing;

a blower wheel in the housing;

a motor connected to the blower;

a tube connected to said housing to conduct the air to a point of combustion;

a burner head on the outer end of the air tube with a central opening for introduction of the gas primary air mixture; a diffuser cap on the burner head forwardly of the gas tube, to reverse the flow of gas and primary air back against the head; and a series of radial slots for secondary air in the burner head for the passage of secondary air therethrough, to pass through said head; and a finely perforated mesh screen on the head downstream thereof to decelerate the resulting burning mixture.

21. In a power burner, a blower housing having an air inlet and a pressure air chamber with a lateral outlet;

a blower in said housing outletting into said chamber;

an air tube at one end projected into said outlet;

a gas manifold having an outlet;

a gas valve connected to said manifold adapted to connection to a source of fluidized hydro-carbon;

an elongated gas tube within said chamber at one end connected to said manifold outlet, extending axially through said air tube, there being a primary air inlet into said gas tube located in said pressure air chamber;

and an air scoop mounted on said gas tube enclosing said air inlet and having an outwardly diverging air intake to facilitate the flow of air under velocity pressure into said gas tube for mixing with gas flowing therethrough, said scoop sensing and responsive to the high velocity of air from the blower forcing primary air into the gas tube by a ram jet effect;

gas ratio.

- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 2 943 I Dated une 28 1974 Warren II. he Lanccy et a1 It is Certified that error appeafs in" the aboveidenti fied. patent I and that said Letters Patent are hereby corrected as shown below:

On t'tIe cover sfteet 175'] I lyrcvn' T. Cooperridge" should read Myron T. 'Cooperrider signed and sealed this 1st day of October 1974.

(SEAL) Attest: V v

McCOY M. GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Pa tents USCOMJM-DC 60376-P69 u s covimmzm rmmmc orncz: 930

OHM PO-IOSO (10-69)

Claims

1. In a power burner for fluidized hydro-carbons, a blower housing having an air inlet, a cover, and a pressure air chamber with a lateral outlet; a motor operated blower in said housing outletting into said chamber; a laterally extending air tube at one end projected into said outlet and secured to said housing, with its outer end open; an apertured burner head assembly mounted over the air tube outer end; a gas manifold on said cover having an outlet through said cover; a gas valve on and connected to said manifold adapted for connection to a source of fluidized hydro-carbon; an elongated gas tube within said chamber at one end connected to said manifold oUtlet, extending axially through said air tube and at its outer end extending through and concentric with said burner head assembly; and an air restrictor static disc centrally mounted on said gas tube and within and spaced from the wall of said air tube, and having a series of perforations therethrough for building up air pressure in said chamber and for delivering through the cross section of said air tube a uniform air flow to said burner head.

3. In the power burner of claim 1, a pilot flame assembly mounted on said gas tube, including a pilot gas tube at one end connected to said gas valve, pilot gas orifice extending forwardly and terminating in a venturi tube having an air inlet and having an outlet adjacent said burner head assembly; a hollow upright pilot shield receiving said venturi tube including a pilot gas spreader with a plurality of flame outlets; a pilot air inlet duct parallel to and mounted on said venturi tube, at one end having an inlet adjacent said air restrictor disc and an outlet connected to said venturi inlet for the ram jet flow of primary air under pressure to render the pilot flame stable and more intense, eliminating flicker and pulsation.

5. In the power burner of claim 1, said burner head assembly including a concave burner head plate on the end of said air tube and extending thereinto with its central portion apertured and curved forwardly in engaging registry with and supportably receiving said gas tube adjacent its outlet; there being a series of elongated radial air outlets formed through said plate throughout its surface, and an inwardly opening concave diffuser cap spaced forwardly of and in opposition to the gas pipe outlet and forwardly of said burner head plate and secured thereto; for reverse deflecting and radially diffusing the flow of combustion gas and primary air to move uniformly and radially outward between the streams of air flowing through said burner head plate.

8. In the power burner of claim 1, said gas manifold having a body with an inlet bore connected to said gas valve; a partition between said inlet bore and manifold outlet having an aperture; an orifice disc having a central opening seated in said aperture for regulating the flow of gas to said manifold outlet; a nut threaded into said body spaced from said partition; and a compression spring interposed between said nut and said orifice disc.

11. In the power burner of claim 10, said partition aperture being tapered.

14. In the burner of claim 2, said gas tube with concentric primary air duct functions as an eductor, the use of velocity pressure creates a most efficient eductor creating a slight subatmospheric pressure in said gas tube maintaining substantially a constant premix air-gas ratio throughout the entire firing range of the burner irrespective of the combustion chamber pressure.

15. In a power burner, a gas manifold having a body with an inlet adapted for connection to a gas valve connected to a source of fluidized hydro-carbon, and an outlet; a partition between said inlet and manifold outlet having an aperture; and orifice disc having a central opening seated in said aperture for regulating the flow of gas to said manifold outlet; a second orifice disc having a central opening smaller than the opening in said first orifice disc; a compression spring interposed between and spacing said discs; and a nut receiving said second orifice disc and threaded into said body; whereby depending upon the nature of the fuel, the positioning of said orifice discs can be reversed by temporarily removing said nut so that the second orifice disc is seated within said partition aperture, providing thereby a quick orifice changeover from one type gas to another, said orifice sizes being determined by the BTU content of the gas, regulated pressure and specific gravity at the gas.

16. In a power gas burner, a housing; a blower wheel in the housing; a motor connected to the blower; a tube connected to said housing to conduct the air to a point of combustion; a gas tube extending through said air tube and connected to a metered supply of gas for delivery of same to the combustion zone; and an air intake in said gas tube for delivering primary air into the gas tube, shaped to provide entrance of velocity pressure air from the blower wheel; the air and gas mixture moving through said gas tube to the combustion zone without creating any back pressure on the gas flow and its metered volume; an orifice assembly for measuring the main gas flow and consisting of at least two different sizes of orifices arranged for selectively restricting the flow of gas from a pressure regulator to the combustion zone; and a means for rapidly and conveniently switching one orifice for the other.

19. In a power gas burner, a housing; a blower wheel in the housing; a motor connected to the blower; a tube connected tO said housing to conduct the air to a point of combustion; a gas tube extending through said air tube and connected to a metered supply of gas for delivery of same to the combustion zone; and an air intake in said gas tube for delivering primary air into the gas tube, shaped to provide entrance of velocity pressure air from the blower wheel; the air and gas mixture moving through said gas tube to the combustion zone without creating any back pressure on the gas flow and its metered volume; said power gas burner having a standing pilot for igniting the air-gas mixture at the combustion zone; said pilot being of the primary air injection type, and having its primary air inlet arranged so that the air movement from the blower increases the primary air inlet pressure.

20. In a power gas burner, a housing; a blower wheel in the housing; a motor connected to the blower; a tube connected to said housing to conduct the air to a point of combustion; a gas tube extending through said air tube and connected to a metered supply of gas for delivery of same to the combustion zone; and an air intake in said gas tube for delivering primary air into the gas tube, shaped to provide entrance of velocity pressure air from the blower wheel; the air and gas mixture moving through said gas tube to the combustion zone without creating any back pressure on the gas flow and its metered volume; a burner head on the outer end of the air tube with a central opening for introduction of the gas primary air mixture; a diffuser cap on the burner head forwardly of the gas tube, to reverse the flow of gas and primary air back against the head; and a series of radial slots for secondary air in the burner head for the passage of secondary air therethrough, to pass through said head; and a finely perforated mesh screen on the head downstream thereof to decelerate the resulting burning mixture.

21. In a power burner, a blower housing having an air inlet and a pressure air chamber with a lateral outlet; a blower in said housing outletting into said chamber; an air tube at one end projected into said outlet; a gas manifold having an outlet; a gas valve connected to said manifold adapted to connection to a source of fluidized hydro-carbon; an elongated gas tube within said chamber at one end connected to said manifold outlet, extending axially through said air tube, there being a primary air inlet into said gas tube located in said pressure air chamber; and an air scoop mounted on said gas tube enclosing said air inlet and having an outwardly diverging air intake to facilitate the flow of air under velocity pressure into said gas tube for mixing with gas flowing therethrough, said scoop sensing and responsive to the high velocity of air from the blower forcing primary air into the gas tube by a ram jet effect; an apertued burner head mounted over the air tube outer end; said premix air gas tube extending concentrically through said burner head; and an inwardly opening concave diffuser cap on said burner head spaced forwardly of and in opposition to the gas tube outlet, whereby the air-gas mixture is diffused onto the forward face of the burner head preventing build up of static pressure behind the burner head and thus maintaining the premix air-gas ratio.