US3814574A

US3814574A - Heater

Info

Publication number: US3814574A
Application number: US00291299A
Authority: US
Inventors: R Darley
Original assignee: SCHEU Manufacturing Co
Current assignee: SCHEU Manufacturing Co
Priority date: 1972-09-22
Filing date: 1972-09-22
Publication date: 1974-06-04
Anticipated expiration: 1991-06-04
Also published as: ES418988A1; IT993926B; FR2200948A5; GB1449009A; DE2346375A1

Abstract

A heater having primary and secondary fire combustion chambers, the primary chamber being formed by a bowl and the secondary chamber being formed by a stack vertically disposed atop the bowl and communicating with the primary combustion chamber. A nozzle assembly is provided for spraying fuel into the primary chamber, and the stack has secondary fire draft holes therein. The primary combustion chamber has a plurality of primary draft or air entry holes in the upper surface thereof, and a fire stabilizing device in the form of an arcuate shield is disposed between the primary draft holes and the nozzle assembly. The shield deflects the incoming air about the inside periphery of the primary chamber for providing thorough mixing of the fuel and air, the burning of a portion of the mixture in the primary combustion chamber. Ultimate complete combustion occurs in the secondary combustion chamber. The heater may be used as a pipeline heater in an automated system with a plurality of similar heaters.

Description

United States Patent [191 Darley 1 1 HEATER [75] Inventor:

[73] Assignee: Scheu Manufacturing'Company, Upland, Calif.

[22 Filed: Sept. 22, 1972 211 Appl. No.: 291,299

Reginald Darley, Santa Ana, Calif.

[52] US. Cl 431/338, 431/342, 126/595 [51] Int. Cl. F23d 5/02 [58] Field of Search 126/595; 431/171, 333, 431/338, 341, 342, 352

[56] References Cited UNITED STATES PATENTS 325,779 7/1906 Vraalstad et a1 431/171 1,435,939 11/1922 Pomeroy 431/342 2.120.291 6/1938 Morin 431/342 3,515.121 6/1970 Scheu et a1. 431/341 Primary Examiner-Carroll B. Dority, .1 r. Attorney, Agent, or FirmLyon & Lyon 1 June 4,1974

[ 5 7 ABSTRACT vA heater having primary and secondary fire combustion chambers, the primary chamber being formed by a bowl and the secondary chamber being formed by a stack vertically disposed atop the bowl and communicating with the primary combustion chamber. A nozzle assembly is provided for spraying fuel into the primary chamber, and the stack has secondary fire draft holes therein. The primary combustion chamber has a plurality of primary draft or air entry holes in the upper surface thereof, and a fire stabilizing device in the form of an arcuate shield is disposed between the primary draft holes and the nozzle assembly. The

shield deflects the incoming air about the inside periphery of the primary chamber for providing thorough mixing of the fuel and air, the burning of a portion of the mixture in the primary combustion chamber. Ultimate complete combustion occurs in the secondary combustion chamber. The heater may be used as a pipeline heater in an automated system with a plurality of similar heaters.

10 Claims, Drawing Figures HEATER BACKGROUND OF THE INVENTION Various types of heaters have been devised over the years, and exemplary types of heaters to which the present invention is directed are those used as field heaters, construction site heaters, factory heaters, and the like. Substantialprogress in the art of such heaters has been made in recent years; for example, centrally controlled heating systems have been introduced wherein the individual heaters are in communication with a central fuel supply. In such systems, the fuel is sprayed into each of the heaters through a nozzle device, thereby providing an automated system with relatively efficient burning in each of the individual heaters. A principal desire in providing an automated system of this nature is to enable a savings in labor.

Automated systems, for example, eliminate the necessity of periodically, such as each day, re-filling each heater with fuel. In addition to the labor savings aspect, it is desirable to preserve or increase the heating effectiveness. Of particular significance today is the provision of a clean burning heater inasmuch as there is increasing emphasis placed on pollution generated by conventional heaters. Furthermore, there is a desire to minimize or eliminate maintenance, as wellas to provide heaters of relatively low cost construction. Although automated heater systems have been devised as noted above, they have not been entirely satisfactory in meeting the aformentioned objectives, particularly those of clean burning and minimum maintenance.

SUMMARY OF THE INVENTION Briefly, the present invention involves a heater principally for use in an automated system with a plurality of similar heaters, each in communication with a common fuel supply. The heater has a primary combustion chamber formed by a bowl and a secondary combustion chamber formedby a stack communicatingwith the bowl. The primary combustion chamber has primary air draft, or air entry, holes therein disposed opposite a nozzle assembly which in turn introduces fuel into this chamber. A fuel nozzle aperture allows an amount of air to be pulled therethrough and into the primary combustion chamber. A curved fire shield, forming a flame or heat stabilizing device, is placed within the chamber and disposed between the draft holes and the nozzle assembly, and causes the entering air to be deflected around the interior of the primary chamber. This arrangement enables proper vaporization, and mixing of fuel and air, for causing primary combustion at a location within this chamber remote from the nozzle assembly thereby aiding in minimizing the temperature of the nozzle assembly. Partial burning occurs in the primary combustion chamber and the mixture passes to the secondary combustion chamber, and draft air for the secondary combustion chamber is provided by apertures in the sidewall of the stack. The overall arrangement thereby provides a thorough mix- .ing of the sprayed fuel with moving air within the heater, resulting in effective heating and clean burning with a significant reduction in'polluting emissions.

Accordingly, it is a primary object of this invention to provide an improved heater.

A further object of this invention is to provide a simple heater for use in an automated heater system, such as for protection of agricultural crops from frost,.and for industrial and construction heating uses, which is characterized by clean burning characteristics and is relatively maintenance free.

Another object of the present invention is to provide a new heater having good heating effectiveness, and which is relatively clean burning and is characterized by minimum maintenance and low initial cost.

It is a further object of this invention to provide an improved heater for automated systems which is capable through remote control of operating over a range of heat outputs without changing the heater configuration.

It is a still further object of the present invention to provide a fuel heater for automated systems which is capable of exceeding air pollution emission standards.

These and other objects and advantages of the present invention will become apparent upon the following detailed description taken in conjunction with the accompnaying drawing.

IN THE DRAWINGS FIG. 1 is an elevational view of an exemplary heater according to the present invention; and

FIG. 2 is a partial sectional plan view of the heater showing the relation of the primary draft holes to a tire shield and a nozzle assembly.

' Referring now in detail to the drawing, the heater, generally designated 10, includes a circular primary combustion chamber 12 in the form of a bowl which is supported by legs 14, a nozzle assembly 16, and a stack 18 forming a secondary combustion chamber. The primary combustion chamber 12 has a cylindrical wall portion 20, lower floor portion or bottom 22 anda cover 24. The nozzle assembly 16 is secured to the combustion chamber by a bracket 26 and is adapted to direct a spray of fuel 28 through an aperture 30 in the wall 20 of the combustion chamber. .T he nozzle assembly 16 is in fluid communication with a central fuel supply through a fuel hose [neither the supply nor hose being shown in the drawing]. The cover 24 has a plurality of apertures 32 therein defining primary draft holes, or a primary air entry area, which'holes are disposed across the primary combustion chamber from the nozzle assembly 16. An arcuate flame shield 34 is housed within the primary combustion chamber and is supported from the cover 24 thereof as shown in FIG.

1. This shield 34 forms a flame or heat stabilizing or distributing device, and extends from the cover 24 to the floor 22. The stack 28 is vertically disposed atop the bowl and is in communication with the interior thereof. The stack forms a secondary combustion chamber, and includes an upper stack portion 36 and lower stack portion 38. The lower portion of the stack has a plurality of apertures'40 therein defining secondary draft holes for secondary combustion.

In use, fuel 28 is sprayed into the primary combustion chamber 12, and the fuel in both the primary and secondary combustion chambers is ignited by a torch, hot wire, spark plug or other suitable igniting means. The use of a hot wire, spark plug, or the like allows the heater to be remotely ignited. As the spray enters the primary chamber, it displaces air therein and aspirates a metered supply of air into the primary chamber through the aperture 30 about the spray nozzle. Metered draft air is also caused to enter the chamber through the primary draft apertures 32. The air entering therethrough is deflected by a flame shield 34 toward the inner wall of the combustion chamber (as illustrated by arrows in FIG. 2) where the moving air mixes with the incoming fuel spray. This mixture is ignited causing a primary flame in the vicinity of the flame shield. The size and configuration of the flame shield 34 tends to stabilize this primary fire and achieve uniform heat distribution in the combustion chamber. It should be noted that although the bottom outer edges (or ears) of the shield 34 touch the floor portion 22, a gap exists between the central portion of the bottom of the shield 34 and the floor portion 22 because of the angle of the shield with respect to the floor portion 22 to prevent unburnt fuel from accumulating behind (to the left) the shield. It also should be noted that the primary draft, or primary air entry, holes 32 are sized to allow sufficient air for primary fire combustion and fuel vaporization but not sufficient to allow all the fuel to burn in chamber 12. A percentage of unburnt gases from the primary fire enters the lower portion 38 of the stack and mixes with metered air entering through apertures 40 therein. A secondary fire is created within the lower portion of the stack, which completes the combustion process without flames belching from the top of the stack. The secondary draft, or secondary air entry holes, 40 in the lower portion 38 of the stack 18 are sized to allow sufficient air-for complete combustion in the secondary fire over a desired burn range. The upper portion of the stack creates the draft necessary for air movement into the combustion chamber for the primary fire, into the lower portion of the stack for the secondary fire, and generates heat for frost protection and/or personnel or equipment heating. It should further be noted that the positioning of the aspirated air entry 30 across the primary combustion chamber from the primary draft apertures 32 enhances the air and vapor mixing process carried on within the combustion chamber and causes the primary combustion flame to exist in an area generally between the center of the bowl and the left side thereof (as viewed in FIG. 2). ln addition, the positioning of the fuel nozzle with respect to the area of the primary flame avoids excessive temperatures in the immediate vicinity of the nozzle [little exposure to flame], while the arrangement of the nozzle protects the same from dirt, rain and so forth. Fi-

nally, it should be noted that the spray rate, i.e., fuel consumption, can be adjusted over a range to vary the heat output of the heater without additional configuration alterations.

As an example, a heater according to the present invention has been constructed with the following dimensions: a-4 inches, b-2 inches, c-2l inches, d-7 /z inches (center of circle of primary air entry holes 32 from center of bowl 12), e-3 inches (radius of circle of primary air entry holes 32) f-l9 inches, g-2l inches, h-8% inches, i-6 inches. Also, this exemplary heater included a fuel nozzle aperture 30 having an area of 1.2 square inches, a Delevan nozzle 16 having a rated capacity of 0.9 gallon per hour at 100 psi, and with a 70 spray ancircumferential direction); however, the number and size of these holes can vary considerably. The radius of the shield 34 was about one-half inch larger than the radius (e) of the hole circle for holes 32. The configuration of the holes 32 (three of which are triangular) and the arcuate shape of the shield 34 cause a swirling action and aid in mixing and flame retention in a localized area. With an exemplary heater asdescribed above. typical spray-rates are from 0.4 to 1.2 gallons per hour with the single nozzle 16. These different spray rates can be obtained by varying the fuel pressure to the nozzle.

Of course, the configuration and dimensions of a heater can deviate from these exemplary values but several dimensions are particularly important. For example, it is desired that the area of the aperture 30 and the total area of the primary air entry holes 32 be approriately selected to enhance but control the quantity of primary combustion in a location away from the noz-' zle. More than one'primary entry hole 32 is desired in order to obtain sufiicient local mixing of air and fuel and to enhance burning in the primary combustion chamber 12 in a localized area near the primary entry holes and flame shield. If the aperture 30 is closed, the mixture within the bowl 12 tends to be pulled toward the nozzle; and if the aperture 30 is too large, the combustion process tends to start close to the nozzle 16. With an arrangement as illustrated and described, for example, the primary combustion area principally is from near the middle of the bowl as shown in FIG. 2 over close to the left inner edge thereof. With the primary combustion flame in this area, the nozzle remains relatively cool and the gas mixture can readily pass to the secondary combustion chamber.

The volume of the primary combustion chamber 12 is less than that of conventional pot type field heaters so as to control and minimize the amount of fuel burned in the primary combustion chamber or zone. For example, as noted above, a typical volume for the primary combustion chamber 12 is 1.1 cubic feet as distinguished from a typical volume of the bowl of a conventional pot type field heater which is approximately 2 cubic feet. The short height and clam shell arrangement of the present combustion chamber 12 provides a suitable vaporizing and mixing chamber, but is not one which is so large as to result .in high heat loss or one having a large amount of heat loss surface,

therefore, less fuel is required to be burned in the primary combustion chamber in maintaining a vaporizing temperature therein for incoming fuel from the nozzle. Constructions of significantly larger volume having large heat loss surface areas require more fuel to be burned in the primary combustion chamber to maintain vaporizing temperature, and this is undesirable since more combustion products pass to the secondary combustion chamber thereby affecting secondary combustion (e.g., results in smoke and other undesirable byproducts).

ln the present invention the primary combustion chamber 12 is essentially a vaporizing and mixing chamber so that a sufficient amount of air is mixed with fuel to enable a. small portion of the fuel to be burned within the primary combustion chamber, but the chamber 12 is sufficiently large to enable mixing of gas, hot gas, vapor and air, and thereby enable a gas mixture of relatively uniform concentration to pass into the secondary combustion chamber. The primary air entry apertures 32 provide a local concentration of air along with a portion of heated fuel from the primary flame so as to cause a small portion of the fuel to burn as noted above.

Furthermore, the volume of the stack 18 is large enough to allow the secondary combustion flame to be contained in the stack, which is important in the case of industrial heating for example.

Various changes and modifications may be made in carrying out the instant invention without departing from the spirit and scope thereof. Insofar as these changes and modifications are within the purview of the appended claims they are to be considered as part of the invention.

what is claimed is: l. A heater for use in a system or the like having a central fuel supply, said heater comprising enclosure means forming a primary combustion chamber and stack means coupled therewith forming a secondary combustion chamber communicating with the interior of said bowl means, said enclosure means having a primary air entry area and a fuel nozzle aperture, and said stack means having a plurality of draft apertures in a lower portion thereof, spray means adapted for fluid communication with a central fuel supply and including a nozzle for directing a spray of fuel through said fuel nozzle aperture into said primary combustion chamber and being disposed with respect to said primary air entry area for enabling mixing of air with said fuel as said fuel enters said primary combustion chamber, and flame baffle means disposed within said primary I combustion chamber near said primary air entry area and between this area and said fuel nozzle aperture. 2. The combination of claim 1 wherein said primary air entry area includes a plurality of primary air entry apertures. 3. The combination of claim 1 wherein said fuel nozzle aperture has an area of approximately 1 to 1% square inches, said fuel nozzle aperture being disposed about said nozzle for enabling a flow of fuel from said nozzle entering said primary combustion chamber to aspirate a supply of air into said primary combustion chamber through said fuel nozzle aperture, and said primary air entry area is approximately 6/ lOths to 1 square inch. 4. The combination of claim 1 wherein said primary combustion chamber is formed by a sidewall member and top and bottom cover-members thereon, said fuel nozzle aperture is in said sidewall member and said primary air entry comprises a plurality of apertures in said top cover member and disposed across said primary combustion chamber from said fuel nozzle aperture, the area of said primary air entry area being approximately 6/ l0ths to 1 square inch. 5. The combination of claims 4 wherein said sidewall and cover members encloses a volume of approximately 1 cubic foot, said primary air entry apertures have an area of approximately 8/l0ths square inch and said fuel nozzle aperture has an area of approximately 1 2/ l0ths. square inch.

6. The combination of claim 1 wherein said flame baffle means comprises a flame shield having a curved surface and extends from said top cover substantially to said bottom cover for directing air entering said primary air entry area around the periphery of said primary combustion chamber.

7. A heater for use in a system having a central fuel supply, said heater comprising a primary combustion chamber found by a cylindrical wall portion, upper cover and floor portion, said wall portion having an opening therethrough and said upper cover having a plurality of primary draft apertures therein,

a stack vertically disposed atop said upper cover and communicating with the interior of said primary combustion chamber, said stack having a plurality of draft apertures in the lower portion thereof and forming a secondary combustion chamber,

a spray assembly adapted for fluid communication with said central fuel supply and having a nozzle for directing a spray of fuel into said primary combustion chamber, said nozzle being disposed adjacent said opening in said cylindrical wall for enabling aspiration of a supply of air into the chamber through said opening when fuel is sprayed into said primary combustion chamber from said nozzle, and

an arcuate flame shield disposed within said primary combustion chamber between said nozzle and said plurality of primary draft apertures for directing air entering said primary combustion chamber through said primary draft apertures about the periphery of said primary combustion chamber for causing air to mix with said fuel spray and heat distribution within said primary combustion chamber.

8. The combination of claim 7 wherein said flame shield is secured to the cover of said combustion chamber, a lower edge portion of said shield being in spaced relation from the floor portion of said combustion chamber.

9. A heater as in claim 1 wherein said flame baffle means comprises a flame shield having a concave surface on a side thereof adjacent said primary air entry area, and

said primary air entry includes a plurality of primary entry apertures having a configuration cooperating with said flame shield to cause a swiveling action to aid in air and fuel mixing and to aid in flame retention in an area near said primary air entry aperatures and said flame shield.

10. A heater as in claim 7 wherein said nozzle is mounted with respect to said wall portion to spray fuel horizontally and evenly into said primary combustion chamber.

Claims

1. A heater for use in a system or the like having a central fuel supply, said heater comprising enclosure means forming a primary combustion chamber and stack means coupled therewith forming a secondary combustion chamber communicating with the interior of said bowl means, said enclosure means having a primary air entry area and a fuel nozzle aperture, and said stack means having a plurality of draft apertures in a lower portion thereof, spray means adapted for fluid communication with a central fuel supply and including a nozzle for directing a spray of fuel through said fuel nozzle aperture into said primary combustion chamber and being disposed with respect to said primary air entry area for enabling mixing of air with said fuel as said fuel enters said primary combustion chamber, and flame baffle means disposed within said primary combustion chamber near said primary air entry area and between this area and said fuel nozzle aperture.

2. The combination of claim 1 wherein said primary air entry area includes a plurality of primary air entry apertures.

3. The combination of claim 1 wherein said fuel nozzle aperture has an area of approximately 1 to 1 1/2 square inches, said fuel nozzle aperture being disposed about said nozzle for enabling a flow of fuel from said nozzle entering said primary combustion chamber to aspirate a supply of air into said primary combustion chamber through said fuel nozzle aperture, and said primary air entry area is approximately 6/10ths to 1 square inch.

4. The combination of claim 1 wherein said primary combustion chamber is formed by a sidewall member and top and bottom cover members thereon, said fuel nozzle aperture is in said sidewall member and said primary air entry comprises a plurality of apertures in said top cover member and disposed across said primary combustion chamber from said fuel nozzle aperture, the area of said primary air entry area being approximately 6/10ths to 1 square inch.

5. The combination of claims 4 wherein said sidewall and cover members encloses a volume of approximately 1 cubic foot, said primary air entry apertures have an area of approximately 8/10ths square inch and said fuel nozzle aperture has an area of approximately 1 2/10ths. square inch.

7. A heater for use in a system having a central fuel supply, said heater comprising a primary combustion chamber found by a cylindrical wall portion, upper cover and floor portion, said wall portion having an opening therethrough and said upper cover having a plurality of primary draft apertures therein, a stack vertically disposed atop said upper cover and communicating with the interior of said primary combustion chamber, said stack having a plurality of draft apertures in the lower portion thereof and forming a secondary combustion chamber, a spray assembly adapted for fluid communication with said central fuel supply and having a nozzle for directing a spray of fuel into said primary combustion chamber, said nozzle being disposed adjacent said opening in said cylindrical wall for enabling aspiration of a supply of air into the chamber through said opening when fuel is sprayed into said primary combustion chamber from said nozzle, and an arcuate flame shield disposed within said primary combustion chamber between said nozzle and said plurality of primary draft apertures for directing air entering said primary combustion chamber through said primary draft apertures about the periphery of said primary combustion chamber for causing air to mix with said fuel spray and heat distribution within said primary combustion chamber.

9. A heater as in claim 1 wherein said flame baffle means comprises a flame shield having a concave surface on a side thereof adjacent said primary air entry area, and said primary air entry includes a plurality of primary entry apertures having a configuration cooperating with said flame shield to cause a swiveling action to aid in air and fuel mixing and to aid in flame retention in an area near said primary air entry aperatures and said flame shield.