US3626924A

US3626924A - Down draft space heater

Info

Publication number: US3626924A
Application number: US849385A
Authority: US
Inventors: Kenneth J Sheppard
Original assignee: SPOT HEATERS Inc
Current assignee: SPOT HEATERS Inc
Priority date: 1969-08-12
Filing date: 1969-08-12
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14

Abstract

The heater comprises a large volume vaporization-combustion chamber formed by bottom, side and top walls of sheet metal. An outlet-radiation stack extends upwardly from a central outlet opening the the top wall. A fuel nozzle extends downwardly through a central opening in a mounting cap and primary air inlet openings are formed in the cap about the fuel nozzle. The cap fits on an upstanding flange which borders an inlet opening formed in the top wall, radially outwardly of the outlet opening. Fuel flow regulation is used to automatically control the amount of primary air induced into the chamber. The flame travel is initially downwardly towards the bottom wall.

Description

United States Patent 43l/l56 X l26/9l 126/595 126/595 MS E C "N E nua .uu fi e m mlmwR ahR r-CE YCFS m 8 80 5667 9999 HHHH 60 6 11 32 9 02 ,5 9295 300 2333 d r N. am h 1 SW d mwfin n J n98 eu4um KS8A f d m w m M w V phm .m AF? 1 l1] 2 25 7 224 i. [ll

[73] Assignee Spot Heaters, Inc. Sunnyside, Wash.

Primary Examiner-Charles J. Myhre Attorney-Graybeal, Cole 8!. Barnard [54] DOWN DRAFT SPACE HEATER 7 Claims, 5 Drawing Figs.

ABSTRACT: The heater comprises a large volume vaporization-combustion chamber formed by bottom, side and top "A0lg13/06 walls of sheet metal An outlet radiation stack extends u pwardly from a central outlet p i g the the p A f l nozzle extends downwardly through a central opening in a (51] Int.

156; 263/19 A mounting cap and primary air inlet openings are formed in the cap about the fuel nozzle. The cap fits on an upstanding flange which borders an inlet opening formed in the top wall, radially outwardly of the outlet opening. Fuel flow regulation is used 7 to automatically control the amount of primary air induced [56] References Cited UNITED STATES PATENTS into the chamber. The flame travel is initially downwardly towards the bottom wall.

PATENTEnuEmm 3'626924 Hill/E0706 KENNETH J. 5I/EPP/4BD ATTORNEYS DOWN DRAFT SPACE HEATER BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to space heaters, and particularly to outdoor space heaters for use in orchards, to prevent frost damage to growing fruit. More particularly, it relates to apparatus for converting a pot heater system over to a centrally controllable pressurized fuel system, and to an improved heater for use in a pressurized fuel system.

2. Description of the Prior Art Pressurized fuel orchard heating systems are presently used quite extensively and their advantages are well known. These systems comprise a plurality of fuel burning space heaters which are distributed throughout the orchard or grove to be heated, a large storage tank for the fuel, and a system of conduits for distributing the fuel from the tank to the fuel nozzles of the individual heaters. Examples of this type of system are disclosed by U.S. Pat. No. 3,409,000, granted Nov. 5, 1968, to Carl H. Brader and Arthur E. Tanasse, and by US. Pat. No. 3,409,001, granted Nov. 5, 1968, to Harry Franke.

Prior to the development of pressurized fuel systems orchards were heated during the frost periods by means of a plurality of pot-type heaters. This type of heating system is still in use today by many orchard owners. The heaters or pots" are essentially a large vessel or pot" for containing a body of heating oil. Such vessel usually includes a top or cover and a stack extending upwardly from an outlet opening in the top. A principal disadvantage of this type of system is that the pots must be individually filled, individually lit (usually by use of a hand-held torch), individually regulated and individually shut down. Ignition involves directing the torch downwardly through a fill opening into close contact with the surface of the oil, a time-consuming procedure. Also, it is usually quite difficult to ignite the oil. Once ignited the oil burns at its surface and continues to burn until either extinguished or until the pot runs out of oil. The fill opening includes a cap which carries a variable area inlet for the primary air needed to support combustion. The person igniting the pots initially sets the air inlet control prior to igniting the oil. The he or another person must walk back through the orchard and adjust the air inlets one or more additional times during use of the pots. Another trip through the orchard is necessary to extinguish the fires. As can be readily appreciated the individual handling of the pots during the filling, igniting, air regulating and extinguishing operations are time consuming and usually require the availability of several persons on a cold night in order to put the pots into operation before frost damage occurs.

The labor saving and other advantages of a centrally controllable pressurized fuel system are known to orchard owners presently still using the pot type burners, and such owners would like to have the advantages of the centrally controllable system. However, many of them have delayed shifting to a central system because they have a quite large investment in still usable pots and feel they must obtain a full life of use from their pots before discarding them in favor of a pressurized fuel system.

SUMMARY OF THE INVENTION This invention relates to the provision of apparatus which can initially be used for converting pot heaters for use in a centrally controllable pressurized fuel system, and which later, after the pots have worn out and must be replaced, can be utilized with a simpler and less expensive stack and base assembly of a type used in a known pressurized fuel system is use today.

The present invention also relates to an improved type of space heater, one which comprises a large volume vaporization and combustion chamber in which the fuel is substantially completely vaporized and burned, and which has a relatively large heat radiating zone. In these heaters combustion is substantially complete and heat radiation commences close to the ground and occurs throughout essentially the full height of the heater.

Space heaters of the present invention are characterized generally by a sheet metal vessel having a large volume base chamber and a stack projecting upwardly from a central outlet opening in a top wall of the base chamber. An inlet opening is formed in the top wall of the heater radially outwardly from the outlet opening. A burner assembly is incorporated into a cap or cover for the inlet opening. The cap includes a central opening for receiving the discharge end portion of a downwardly directed fuel injection nonle. A plurality of arcuate air inlet openings are formed in the cover member about the fuel nozzle, and such openings are outwardly bounded by inwardly sloping vanes or louvers which serve to direct the incoming primary air into a converging stream flowing about the fuel injection nozzle. The fuel is injected from the nozzle as a diverging conical spray or flow pattern, resulting in the fuel being intercepted by the converging ailstreams, and in a good initial mixing contact of the fuel with the primary air.

According to the invention there is no independent control means for the primary air. The primary air inlet openings are of a fixed size and are sufficiently large to pass the full demand of primary air to support combustion throughout the full range of heater operation. The fuel distribution system is provided with means for directly controlling the-rate of fuel flow into the heaters, and in that manner indirectly controlling the quantity of primary air induced into the heater. The larger volume base chamber of the heater serves as both 9 vaporization and combustion chamber. Because of ignition delay, combustion occurs several inches inwardly of the fuel nozzle. The incoming fuel and primary air flow downwardly unimpeded until the fuel is sufficiently vaporized, a combustable mixture is created, and such mixture is ignited. The flame flow is initially downwardly and its direction is not changed until contact is made with the bottom. Then the flame moves across the bottom and eventually rises and moves towards the central outlet opening, in countercurrent relationship to any unvaporized fuel droplets present in the intermediate portion of the chamber. Combustion occurs very low in the large volume base of the heater and continues upwardly through such chamber and also through the stack. As a result, heat is radiated outwardly from the heater commencing at at a location relatively near the ground.

According to the invention the fuel used can be either heating oil, L-P gas or natural gas.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a pictorial view of a downdraft burner exemplifying the present invention, such view showing the heater being connected to a service line which delivers fuel to a series of like heaters; 7

FIG. 2 is a vertical section view of the heater shown by FIG. 1, with the nozzle assembly shown in full line and with an upper portion ofthe stack being cut away;

FIG. 3 is an enlarged view of the portion of FIG. 2 immediately surrounding the fuel nozzle;

FIG. 4 is a cross-sectional view taken though the mounting cap of the burner assembly, substantially along line 4-4 of FIG. 3; and

FIG. 5 is a fragmentary view similar to FIG. 4 but relating to a modified construction of the cap and the inlet flange.

DESCRIPTION OF THE PREFERREDEMBODIMENT In FIGS. 1 and 2 the heater is shown to comprise a portable pot" or vessel 10 having a large volume base chamber 12, and an upwardly extending stack 14, both constructed from sheet metal. The chamber 12 is both a vaporization and combustion chamber. It is defined by a circular bottom wall 16, an integral, frustoconical sidewall 18 extending upwardly therefrom, and by frustoconical top wall 20. The top wall 20 is shown to be integrally formed with a downwardly extending rim wall 22 and an upwardly extending neck flange 24. The lower end of the stack 14 surroundedly engages the neck wall 24 enveloping a central outlet opening. The rim wall 22 frictionally engages an upper edge portion 26 of the base chamber 12, and in that manner removably secures the top wall 20 and the stack 14 carried thereby onto the lower tub" portion of the base chamber 12, consisting of the bottom wall 16 and the sidewall 18.

An inlet opening is formed in the top 20 radially outwardly of the central outlet opening. An upstanding rim flange 28 borders the inlet opening.

The burner assembly 30 comprises a mounting cap 32 including a flanged central opening 34 which snugly receives a mounting neck portion 36 of a fuel nozzle 38. By way of typical and therefore nonlimitive example, in an oil burning installation the fuel nozzle 38 may be of the type disclosed in detail by the aforementioned Carl H. Brader and Arthur E. Tanasse U.S. Pat. No. 3,409,000, the contents of which patent are hereby expressly incorporated herein by this specific reference. In a gas burning installation a nozzle is used which is designed to deliver a diverging conical pattern of gas jets.

The burner assembly 30 also includes a rigid (preferably iron, steel, a steel alloy, or a similar metal) delivery pipe 40 which is connected at one end to the outer portion of the fuel nozzle 38, at a right angle to the nozzle axis, and at its opposite end to the stern portion of a tee type coupler 42. The branch portions of the coupler 42 are connected to oppositely extending sections 44, 42 of a flexible feeder line which extends from a main or trunk line (not shown) leading from a fuel storage tank (also not shown) for the fuel.

According to one aspect of the invention, the mounting cap 32 is retained in place by means including a locating flange 48 which surroundingly engages the upstanding rim flange 28 of the inlet opening. Flange 48 may frictionally grip flange 28. Or, the top 20 may be fitted with a retainer member 49 (FIG. 1) which is movable into a position over a plate portion 50 of cap 32, and when so extended serves as a barrier to prevent the cap 32 from falling off from its position on wall 28. Member 49 is shown to include a base connected to the top wall 20 by means of a pivot pin 51. A steam extends upwardly from the base and a retaining lip extends transversely from the stern. Member 49 may be rotated between a lock position in which the lip extends over cap 32 and a release position in which the lip is clear of the cap 32. The tee 42 may rest on the ground or on some object between it and the ground, so that the outer end of pipe 40 is ground supported.

Fuel discharges from the outlet portion 52 of the nozzle 30 as a conical spray 54 (when the fuel is oil) or a conical pattern of jet streams (when the fuel is gas). Arcuate primary air inlet openings 56 are formed in the plate 50 closely about the nozzle 30. These openings 56 are radially outwardly bounded by arcuate vanes or louvers 58 which slope radially inwardly as they extend axially inwardly of the chamber from plate 50, so that they function to direct the inflowing primary airstrearns radially inwardly, forming a converging flow pattern. As shown by FIG. 3, the discharge end portion 52 of the nozzle 38 is located a substantial distance inwardly of the air openings 56. During heater operation the incoming air flows first over the inner end portion 52 of the nozzle, cooling and cleaning it, and then impinges upon the rear side of the diverging fuel cone 54, resulting in an early contact between, and good mixing of, the primary air and the fuel.

In FIG. 3 the nozzle assembly 30 is schematically shown to be connected to a line portion 56 of the fuel distribution system which includes a control valve 58. Valve 58 may be either a single control valve for all heaters of the system, or a control valve for only a portion of the heaters, such as for a single row of heaters, for example.

In operation the valve 58 is controlled to deliver the fuel to the heater at a sufiicient pressure (e.g., within the range of 0-200 p.s.i. for fuel oil, within the range of 0-30 p.s.i. for L-P gas, and within the range of 0-30 p.s.i. for natural gas). A torch or some other suitable ignition means is used to ignite the combustible mixture initially existing inside the chamber 12, consisting of the fuel first injected into chamber 12 and of the air initially in chamber 12. Due to ignition delay the flame pattern that is created starts at a location that is several inches inwardly of chamber 12 from the discharge end 52 of the nozzle 30. The flame pattern or stream initially moves unimpaired as a colinear continuation of the flow path of the fuel injected into the chamber 12 until it strikes the bottom. Then it strikes the bottom 16 and somewhat flattens out the next flows first across the bottom and then upwardly, partially due to a draft created force and partially due to a physical turning by the sidewall 18. Eddy currents are established in the flame pattern as the flame changes direction, resulting in a lengthening of the flow path of each burning increment of fuel-air mixture within chamber 12. Eventually the burning mixture finds the outlet opening 24 and rises out of the pot 12 into the stack 14. The stack 14 is provided with a plurality of louvers, some of which are designated 60, through which secondary air may enter so that combustion may continue within the stack 60.

Combustion within the heater 10 is quite complete and is based quite low in the chamber 12. The flame makes contact with a substantial portion of the sidewall [8, including near the bottom 16. As a result, the heater 10 starts to emit radiant heat starting quite close to the ground and continues to emit such heat as the flame moves upwardly. The zone in chamber 12 above and around the flame is quite hot and this is where vaporization occurs.

No independent control is necessary for the primary air entering through the openings 56. Rather, the inflow of primary air is controlled by regulation of the fuel flow rate. This is because of the system is a draft system and the primary air is drawn into the pot 12 by the moving combustion gases. An increase in the quantity of fuel being burned causes an increased demand for primary air, and automatically results in an increased inflow or primary air through the inlet openings 56. If necessary, additional primary air inlet openings may be provided in the plate 50 about the louvers 58.

Heater pot 10 may be constructed new'for the purpose of being a part of the heater of this invention. The efficient operation of the heater of this invention justifies constructing the heater pot anew specially for use in the system of the present invention. Alternatively, it may be a converted pot burner, such as one of the types made by Scheu HY-LO of Upland, California, e.g. the HY-LO Return Stack Heater, the HY-LO Large Cone Heater, the I-IY-LO 230-A Stack Heater or the HY-LO Sliding Cover Heater. Conversion of some pot burners requires the removal from them of internal draft tubes, or the like. The burner cap 30 may replace the till opening cap on the already existing flll opening, or an inlet opening may be specially formed in the heater pots top.

In the embodiment of FIG. 5 the rim flange 28' which surrounds the inlet opening is shown to curve at its upper end first radially inwardly, then axially inwardly, and then radially inwardly again, terminating in a narrow radial lip 62. The radially outer portion of the cap plate 50' is shown to reset on the upwardly convexed rim 64 and the cap flange 48 is shown to concentrically surround the flange 28. The flange 48' is spaced radially outwardly from the flange 28', i.e. the cap 32' fits loosely on the inlet flange 28'. A plurality (e.g. three) of circumferentially spaced apart louvers are formed in the plate 50'. The struck out sections or tabs of sheet metal, one of which is designated 66 in FIG. 5, are turned inwardly of the cap 32'. These tabs 66 may be used as spring elements for frictionally engaging the inner edge of the radial rim 62, for in that manner holding the cap 32' on the flange 28'. Or, the tip 68 of a screwdriver may be inserted downwardly through the openings 70 and used to forcibly turn or curl back the lower free end portions of the tabs 66 into positions underlying the rims 62, for securely retaining the cap 32 on the rim flange 28'. In an installation where this is done the cap 32' may be left attached to the top wall 20. When it is desired to dismantle the system and remove it from the orchard the nozzles 38 are simply unplugged from the central openings 34 in the caps 32'. This disconnects the fuel distribution system from the individual heater vessels.

The openings 70 serve as additional primary air inlet openings and the size of these openings 70 is in part dictated by the primary air demands of the heater.

in the heater of this invention the tubular neck portion 72 of the burner nonle 38 is adapted to simply plug into the central opening in the cap. The weight of the delivery pipe 30 located on one side only of the nozzle 38 tends to tilt the nozzle 38 somewhat and bind the noule neck 72 into a secure engagement with the rim wall or flange 34.

What is claimed is:

1. A portable down draft space heater, comprising:

sheet metal wall means forming an enclosed vaporization and combustion chamber, including a top wall with an outlet opening that is small in area in comparison with the total area of the top wall, and an inlet opening in said top wall laterally spaced from said outlet opening: and

a burner assembly comprising a cover member for said inlet opening including a fuel nozzle opening and primary air inlet means, a downwardly directed fuel injection nozzle extending downwardly through said fuel nozzle opening and discharging into said chamber, and fuel delivery conduit means for delivering fluid fuel under pressure to said fuel injection nozzle, wherein said fuel nozzle includes means for discharging the fuel downwardly into the chamber in a diverging conical flow pattern, and wherein said primary air inlet means comprises arcuate air openings surrounding said fuel nozzle, and air directing vane means outwardly bounding said openings and being inclined inwardly so as to direct entering primary air into a conveying flow pattern, resulting in the incoming air impinging on and mixing with the incoming fuel in a zone close to where both the air and the fuel enter the chamber 2. A down draft heater according to claim 1, wherein said top includes a upstanding tubular rim wall bordering said inlet opening and said cover member includes a tubular wall surrounding said rim wall and serving to at least assist in locating said burner assembly in a set position with respect to said inlet opening.

3. A down draft heater according to claim 2, also comprising control means for varying the flow rate of fuel through said conduit means and said injection nozzle, with said primary air inlet means comprising a plurality of openings of fixed size, and collectively being of sufficient size to deliver by draft induced flow at least most of the primary air demand of the heater, throughout the full range of fuel flow regulation.

4. A down draft heater according to claim 1, wherein said conduit means comprises a supply line including a tee connection and a rigid burner pipe extending from said tee correction to said fuel nozzle, and being rigidly connected thereto.

5 A portable orchard heater, comprising:

wall means forming an enclosed vaporization and combustion chamber, including a top wall having an outlet opening that is small in area in comparison with the total area of the top wall;

fuel nozzle supporting socket means on said top spaced laterally from said outlet opening;

a fuel nozzle received in said socket means and projecting inwardly from the top wall into said chamber, said fuel noule being oriented to discharge fuel downwardly into the inner space of the chamber; and

primary air inlet means closely surrounding said fuel nozzle but spaced outwardly therefrom, for delivering by draft induced flow a supply of primary air first around the nozzle, for cooling and cleaning same, and then into contact with fuel emerging from said fuel noule,

with said chamber being open in the path of the incoming fuel and air so that a flame pattern is established which is directed first downwardly to the bottom of the chamber, then spreads across the bottom and then turns upwardly towards the outlet opening, thereby following an elongated tortuous path based low in said chamber, and wherein said top wall includes an inlet opening bounded by an u standing flange having a radially inwardly directed rp, and a cap extends over said inlet opening, said cap carrying said fuel nozzle support socket and said primary air inlet means, and including a plurality of retaining tabs which project inwardly from said cap and engage said lip.

6. A down draft heater according to claim 5, also comprising control means for varying the flow rate of fuel through said conduit means and said injection nozzle, with said primary air inlet means comprising a plurality of openings of fixed size, and collectively being of sufficient size to deliver by drafi induced flow at least most of the primary air demand of the heater, throughout the full range of fuel flow regulation.

7. A portable orchard heater, comprising:

wall means forming an enclosed vaporization and combustion chamber, including a top wall having a centrally located outlet opening therein that is small in area in comparison with the total area of the top wall;

fuel nozzle supporting socket means on said top wall spaced laterally from said outlet opening;

a fuel nozzle received in said socket means and projecting inwardly from the top wall into said chamber, said fuel noule having an outlet portion oriented to discharge fuel generally downwardly into the chamber; and

primary air inlet means surrounding said fuel nozzle but spaced laterally outwardly therefrom and rearwardly from said outlet portion, for delivering by draft induced flow a supply of primary combustion air substantially around the nozzle, for cooling and cleaning same, and then into contact with fuel emerging from said fuel nozzle, with said fuel nozzle and primary air inlet means being arranged to deliver both fuel and primary air into said chamber along an unimpeded common path that extends generally axially of the fuel nozzle and slopes downwardly and radially inwardly of the chamber from vertical,

with said chamber being internally close in the path of the incoming fuel and air so that a flame pattern is established which is directed first downwardly to the bottom of the chamber, then spreads across the bottom, and then turns upwardly towards the outlet opening, thereby following an elongated tortuous path based low in said chamber.

Claims

1. A portable down draft space heater, comprising: sheet metal wall means forming an enclosed vaporization and combustion chamber, including a top wall with an outlet opening that is small in area in comparison with the total area of the top wall, and an inlet opening in said top wall laterally spaced from said outlet opening: and a burner assembly comprising a cover member for said inlet opening including a fuel nozzle opening and primary air inlet means, a downwardly directed fuel injection nozzle extending downwardly through said fuel nozzle opening and discharging into said chamber, and fuel delivery conduit means for delivering fluid fuel under pressure to said fuel injection nozzle, wherein said fuel nozzle includes means for discharging the fuel downwardly into the chamber in a diverging conical flow pattern, and wherein said primary air inlet means comprises arcuate air openings surrounding said fuel nozzle, and air directing vane means outwardly bounding said openings and being inclined inwardly so as to direct entering primaRy air into a conveying flow pattern, resulting in the incoming air impinging on and mixing with the incoming fuel in a zone close to where both the air and the fuel enter the chamber

2. A down draft heater according to claim 1, wherein said top includes an upstanding tubular rim wall bordering said inlet opening and said cover member includes a tubular wall surrounding said rim wall and serving to at least assist in locating said burner assembly in a set position with respect to said inlet opening.

4. A down draft heater according to claim 1, wherein said conduit means comprises a supply line including a tee connection and a rigid burner pipe extending from said tee correction to said fuel nozzle, and being rigidly connected thereto. 5 A portable orchard heater, comprising: wall means forming an enclosed vaporization and combustion chamber, including a top wall having an outlet opening that is small in area in comparison with the total area of the top wall; fuel nozzle supporting socket means on said top spaced laterally from said outlet opening; a fuel nozzle received in said socket means and projecting inwardly from the top wall into said chamber, said fuel nozzle being oriented to discharge fuel downwardly into the inner space of the chamber; and primary air inlet means closely surrounding said fuel nozzle but spaced outwardly therefrom, for delivering by draft induced flow a supply of primary air first around the nozzle, for cooling and cleaning same, and then into contact with fuel emerging from said fuel nozzle, with said chamber being open in the path of the incoming fuel and air so that a flame pattern is established which is directed first downwardly to the bottom of the chamber, then spreads across the bottom and then turns upwardly towards the outlet opening, thereby following an elongated tortuous path based low in said chamber, and wherein said top wall includes an inlet opening bounded by an upstanding flange having a radially inwardly directed lip, and a cap extends over said inlet opening, said cap carrying said fuel nozzle support socket and said primary air inlet means, and including a plurality of retaining tabs which project inwardly from said cap and engage said lip.

6. A down draft heater according to claim 5, also comprising control means for varying the flow rate of fuel through said conduit means and said injection nozzle, with said primary air inlet means comprising a plurality of openings of fixed size, and collectively being of sufficient size to deliver by draft induced flow at least most of the primary air demand of the heater, throughout the full range of fuel flow regulation.

7. A portable orchard heater, comprising: wall means forming an enclosed vaporization and combustion chamber, including a top wall having a centrally located outlet opening therein that is small in area in comparison with the total area of the top wall; fuel nozzle supporting socket means on said top wall spaced laterally from said outlet opening; a fuel nozzle received in said socket means and projecting inwardly from the top wall into said chamber, said fuel nozzle having an outlet portion oriented to discharge fuel generally downwardly into the chamber; and primary air inlet means surrounding said fuel nozzle but spaced laterally outwardly therefrom and rearwardly from said outlet portion, for delivering by draft induced flow a supply of primary combustion air substantially around the nozzle, for cooling and cleaning same, and then into contact with fuel emerging from said fuel nOzzle, with said fuel nozzle and primary air inlet means being arranged to deliver both fuel and primary air into said chamber along an unimpeded common path that extends generally axially of the fuel nozzle and slopes downwardly and radially inwardly of the chamber from vertical, with said chamber being internally open in the path of the incoming fuel and air so that a flame pattern is established which is directed first downwardly to the bottom of the chamber, then spreads across the bottom, and then turns upwardly towards the outlet opening, thereby following an elongated tortuous path based low in said chamber.