US3698379A

US3698379A - Orchard heater

Info

Publication number: US3698379A
Application number: US80886A
Authority: US
Inventors: Harold L Cheney
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1970-10-12
Filing date: 1970-10-12
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17

Abstract

An orchard heater is provided which has improved combustion properties and, consequently, reduced soot deposit problems. The orchard heater is provided with a primary combustion chamber, a stack mounted thereon and an air-fuel mixer in combination with directional means which directs the primary combustion flame to more evenly distribute the heat generated thereby insuring complete combustion and little, if any, build-up of soot.

Description

United States Patent Cheney 1 Oct. 17, 1972 [54] ORCHARD HEATER 2,284,157 5/1942 Leonard ..l26/59.5 X [72] Inventor: Harold L. Cheney, Richmond, Calif. P a E r Charles] y e llm ry xamme r 1 u Chevljw Resemh p y San Anomey-J. A. Buchanan, Jr., c. J. Tonkin and a. o.

Francisco, Calif. Fehringer [22] Filed: Oct. 12, 1970 [57] ABSTRACT [2|] Appl. No.: 80,886

An orchard heater is provided which has improved combustion properties and, consequently, reduced [52] 1.8. CI ..l26/59.5 wot deposit problems The orchard heater is provided i with a primary combustion chamber, a stack mounted e 0 6 thereon and an air-fuel mixer in combination with I directional means which directs the primary combustion flame to more evenly distribute the heat [56] Cmd generated thereby insuring complete combustion and UNITED STATES PATENTS little, if y. p of s00!- 3,5i5,l2l 6/1970 Scheu et a]. ..l26/59.5 6Claims,6Drawing Figures X a i l u o o 1 9 j 7- I o 0 W) 5 llllli 2 14 T II Q$f r PATENTEDnm 17 1972 3 698 3 79 sum 2 or 2 INVENTOR HAROLD L. CHENEY ORCHARD HEATER BACKGROUND OF THE INVENTION Orchard heaters have been used for many years during inclement weather to prevent frost damage to the trees and fruit. A wide variety of heaters have been used with varying degrees of success.

The old standard-type of heater consists of a burner pot in which a liquid fuel is contained and a stack portion mounted on the burner pot for dissipation of the heat to the immediate areas surrounding the heater and for improved combustion, due to the draft rising upwardly through the stack portion which is normally perforated at the bottom to allow intake of air for combustion.

A second type of burner which allows better control of combustion employs a similar burner pot with a stacked section mounted thereon. However, the fuel is injected through a nozzle into the burner pot area as a spray, rather than having the burner pot also function as a liquid fuel reservoir. Typical of such burners are the Jumbo and Return-Flo models shown in the drawing which are products of the Schou Products Company (which have been modified as proposed by this invention). The result of the fuel injection into the burner pot is better control of combustion due to the adjustability of the spray nozzles which are maintained under pressure. Typical of such nozzles are those shown in the brochure entitled Monarch Oil Burner Nozzles," No. 4,164 (Copyright 1964) put out by Monarch Manufacturing Works, Inc.

While the use of injection nozzles has resulted in better control of the combustion process, some problems have developed in their use. The build-up of soot deposits on the bottom, top and walls of the burner pot results from some operating circumstances. When build-up is severe, the effectiveness of the orchard heater is reduced significantly, resulting in the need for disassembly, cleaning, and reassembly, with the resultant down-time and decreased efficiency and economy of operation. Further, during periods when orchard heaters are required, continuous operation is often necessary for substantial periods of time and it is imperative that the heaters operate effectively. Ignition of orchard heaters utilizing pressurized fuel sources has also been a problem in the past. While initial ignition and operation was satisfactory, the flame under some operating conditions was extinguished after a relatively short period of operation requiring that the heater be reignited.

Also, when an orchard burner utilizing an injection nozzle is operating properly, a phenomenon which can be referred to as motorboating occurs. This condition is a form of controlled instability in the combustion areas of the heater. The stack of the standard-type heaters has air slots in the bottom portions thereof through which air is drawn to promote better combustion in the stack where secondary combustion occurs, and slots or holes in the wall portions through which heat is dissipated. When the burner is operating properly, flames intermittently shoot out these slots in the sides of the stack and the entire burner vibrates with a characteristic sound which, to a skilled operator, indicates proper operation.

The need for a satisfactory solution to the build-up of soot and incomplete combustion and poor ignition is obvious. One method which has been proposed is that shown in U.S. Pat. No. 3,020,906. In this patent, scrapers are maintained on the interior walls of the burner pot which are operated by a handle on the outside of the burner pot. Movement of the handle causes the scrapers to be wiped over the interior walls of the burner pot to relieve the sides of any adhering carbon.

This solution to the problem is temporary in nature since carbon is then deposited on the bottom of the burner pot and must eventually be removed by disassembly of the heater.

This invention is directed toward a method of preventing the buildup of soot by improved combustion throughout the burner pot. The amount of carbon being formed is reduced (a preventative type of operation) and a removal process once the carbon has been formed (a remedial type of operation) is not required. A secondary, though important aspect, of this invention is improved ignition characteristics.

DESCRIPTION OF PRIOR ART U.S. Pat. No. 2,284,157 discloses an orchard heater having a recirculation means for returning a portion of the products of a continuing combustion and adding these to the combustion mixture before it is burned in the burner pot. The arrangement disclosed is taught as reducing the tendency of the heater to form soot and smoke by adding to the combustion mixture some gaseous material that will not, itself, take part in the combustion to any substantial degree.

SUMMARY OF THE INVENTION An improved orchard heater is provided which has a burner pot with a stack mounted thereon and an airfuel mixer preferably mounted on an opening in the upper portion of the burner pot. Directional means operate in conjunction with the air-fuel mixer and direct the primary combustion flame toward the center and downward toward the bottom in the nonreturn flow type of heater where the air-fuel mixture is introduced through an opening in the upper portion of the burner pot. In the return flow type of system, the air-fuel mixture is introduced through an opening preferably in the upper portion of the burner pot. An air-fuel mixer is mounted on the opening. The directional means preferably directs the primary combustion flame horizontally toward the center of the burner pot in the return flow type of system where the air-fuel mixture is introduced through an opening in the upper portion of the burner pot. Resulting distribution of the hot gases toward all metal surfaces of the burner pot results in reduced soot deposits caused by cold surfaces and incomplete combustion.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are elevation views partially in section of two typical types of orchard heaters showing the flame directional means and their angle of deflection of the flame in the primary combustion area.

FIG. 3 is an elevation view partially in section of the spray nozzle in combination with the air-fuel mixer and the flame directional means.

FIG. 4 is a cross-section taken along Line 4-4 of FIG. 3 showing the bracket for holding the spray nozzle and the air intake holes in the cover of the air-fuel mixer.

FIG. is a cross-section taken along Line 5-5 (just below the air-fuel mixer cover) of FIG. 3 and showing the configuration of a typical air-fuel mixer.

FIG. 6 is an exploded elevation view of the nozzle, nozzle bracket, cover, air-fuel-mixer, sleeve, and flame directional means with the air-fuel mixer cover and bracket rotated 90 from the view shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION A more comprehensive understanding of the concept of this invention can be obtained by reference to the drawings. FIG. 1 shows a typical orchard heater having a burner pot 1 comprised of a chamber with a removable cover 2. The cover 2 has an opening upon which is mounted a flame directional means 3 which extends into the burner pot 1 and through which spray nozzle 4 discharges gaseous fuel mixed with air into the chamber. The removable cover 2 has an opening 5 in its central portion, upon which is mounted a truncated cone stack portion 6, having slots or holes such as 7 in the bottom portion thereof through which air is drawn. Stack portion 6 also has slots or holes such as 8 and 9 in the angled portion thereof and an upper open end 10. Mounted on stack portion 6 is a second stack portion 11 which is substantially cylindrical in nature and with an open upper end 12 which can be closed by a hinged cover 13. An air-fuel mixer 14 operates in conjunction with nozzle 4 and flame directional means 3.

The subject invention centers around the fuel inlet, the air-fuel mixer 14, and the flame directional means 3.

In operation, fuel is fed through nozzle 4 into burner pot 1 where primary combustion occurs as denoted by flame 15. In the nonreturn flow model of FIG. 1 where the air-fuel mixture enters through an opening in the burner pot cover 2, the flame directional means directs the air-fuel mixture and, consequently, the flame at an angle downward from the horizontal. Secondary combustion occurs in the stack in the area of stack portion 6. By directing the primary combustion flame in the burner pot to distribute the generated heat properly, cold surfaces are avoided, combustion efficiency is improved and the build-up of soot is greatly reduced. The increased efficiency of the burner is also due in part to the air-fuel mixer which provides the proper air-fuel ratio to obtain proper burning characteristics in the burner pot.

Considering now FIG. 2, substantially the same configuration is used except that an inverted truncated cone first stack portion 16 is utilized and a return tube I7, having an opening on first stack portion 16, feeds a portion of the warm gases rising through the stack back into the pot burner 18. The recirculation of these warm gases partially serves to prevent build-up of soot by distribution of heat to the areas of cool metal and incomplete combustion. However, by use of the air-fuel mixer 19 in combination with flame directional means 20, which directs the air-fuel mixture from spray nozzle 21 and, consequently, the primary combustion flame 22 substantially horizontally, it has been found that soot build-up can be reduced to near zero.

A better understanding of the relationship between the spray nozzle, the air-fuel mixer and the directional means can be obtained by referral to FIGS. 3-6. FIGS. 3-6 describe in detail the air-fuel mixer assembly and directional means denoted as 19 and 20, respectively, in FIG. 2 together with the fuel nozzle 21 of FIG. 2.

Referring now to FIG. 3, nozzle 21 is held in position over air-fuel mixer 23 by nozzle adapter 24 which is seated on bracket 25. Bracket 25 aligns nozzle 21 with hole 26 in the air-fuel mixer cover 27. Air-fuel mixer (swirl cone) 23 is seated in sleeve 28 which fits over the upraised portion 29 of the burner pot cover. Directional means 20 flts over the downward extending circular portion 30 of sleeve 28.

Referring now to FIG. 4, a plane view of air-fuel mixer cover 27 is shown. Air holes 31 in the top portion of cover 27 surround the central opening through which fuel as a spray is injected. Bracket 25 is attached to air-fuel mixer cover 27 by

rivets

32 and 33.

FIG. 5 shows the configuration of air-fuel mixer 23. In operation, air enters through holes 31 in air mixer cover 27 (see FIG. 4) as a result of the reduced pressure resulting from the rush of sprayed fuel through. the central hole 34 in air-fuel mixer (swirl cone) 23. A number of vanes, such as 35 and 36, impart a swirling motion to the air and promote good mixing with the sprayed fuel. The well mixed air-fuel mixture is then directionally introduced into the burner pot by directional means 20.

Considering now FIG. 6, nozzle adapter 24 is seated in bracket 25 which allows nozzle 21 to have its tip 37 level with the top of the air-fuel mixer 23 when the structure is assembled (see FIG. 3). Bracket 25 is attached to air-fuel mixer cover 27 by

rivets

32 and 33. Air-fuel mixer 23 sits in the upper portion of sleeve 28 and directional means 20 fits over the downward extending circular portion 30 of sleeve 28. Sleeve 28 fits over the upraised portion 29 of the burner pot. When assembled, the relative positions of the parts of the structure are shown by the short horizontal lines of FIG. 6.

The invention can be better understood by reference to the following examples which are offered by way of explanation and not by way of limitation.

EXAMPLE 1 Using the orchard heater shown in FIG. 1 and a Monarch 0.85, 45 AR, nozzle (product of Monarch Manufacturing Works, Inc.) with the air-fuel mixer described in FIGS. 3-6, a combustion test was initiated and run for a period of about 20 hours. After an initial adjustment of the nozzle, combustion was excellent with constant motorboating. Initial ignition was excellent and no problems were encountered with extinguishment of the flame. The angle of orientation of the longitudinal axis of the primary combustion flame downward from the horizontal was about 23 with the flame being directed toward the vertical axis of the burner pot. The outside skin temperature of the stack ranged from 650 to 700 F. After completion of the test, the heater was disassembled and inspected. A very light build-up of soot was noticed on the internal walls of the burner pot.

EXAMPLE 2 Using the orchard heater shown in FIG. 2 and the same nozzle and air-fuel mixer as in Example 1, the

combustion test was carried out for approximately 50 hours. After ignition, the nozzle was adjusted for 0ptimum operation. The angle of orientation of the longitudinal axis of the primary combustion flame was substantially horizontal with the flame being directed toward the vertical axis of the burner pot. Combustion was excellent with constant motorboating. Initial ignition was excellent and no problems were encountered with extinguishment of the flame. The outer skin temperature of the stack ranged from 650 to 700 F. After completion of the 50 hours of burning, the heater was disassembled for inspection. No build-up of soot in the pot was observed.

The invention has been exemplified by means of conventional orchard heaters having means for introducing an air-fuel mixture into the burner pot through an opening in the upper portion of the burner pot, i.e., through an opening in the removable cover. The airfuel mixture is formed and introduced into the burner pot through a flame directional means.

This flame directional means is preferably a tube such as a stovepipe elbow. The only criterion for the directional means, however, are (1) that the flame directional means be fully enclosed, i.e., a chute-like guide open on one side and upon which the flame impinges is not satisfactory, and (2) the angle of direction of the flame must be closely controlled. For heaters in which the air-fuel mixture is introduced into the burner pot through an opening in the top portion of the burner pot the angle at which the longitudinal axis of the primary combustion flame should be directed lies between about the horizontal and about 30 downward from the horizontal. In the type of heater having a tube for the return flow of warm gases from the stack to the burner pot 2 as shown in FIG. 2, the preferred angle is substantially horizontal. However, any angle up to the 30 downward specified above is satisfactory.

On the general type of heater shown in FIG. 1, the permissible range on the angle of flame orientation downward from the horizontal is tighter. For satisfactory operation, the angle at which the longitudinal axis of the primary combustion flame is directed should be between about and 30 downward. Particularly preferred is an angle of about 23.

in the event that the air-fuel mixture is introduced to the burner pot through an opening in the side or bottom of the burner pot, the flame directional means will be required to direct the flame at a horizontal or even an angle upwards from the horizontal to properly distribute the heat.

In all cases, regardless of the point of introduction of the air-fuel mixture into the burner pot, the orientation of the flame is toward the vertical axis of the burner pot. While some minor deviation from this may be acceptable, it should not exceed about 10 or soot buildup will occur in the portions of the pot which are cool clue to improper distribution of the generated heat.

To achieve satisfactory operation, good air-fuel mixing must be obtained. Attempts to operate the devices disclosed herein without the use of the air-fuel mixer were unsuccessful. A lazy" yellow flame resulted due to incomplete combustion from lack of oxygen. By the same token, if too much air is mixed with the fuel, complete combustion will occur in the burner pot and the required secondary combustion in the burner stack and consequent heat distribution will not be achieved. Proper adjustment of the heater is required to obtain the desired flame characteristics.

The method and apparatus used to obtain good mixing is not critical. However, when using an air-fuel mixer with swirling vanes, (a swirl cone) as in the preferred system described herein, the position of the nozzle in relation to the mixer is critical. Preferably, the tip of the fuel nozzle is aligned with the mixer's topmost portion as shown in FlG. 3 so that the nozzle tip touches the plane formed by topmost portion of the mixer. No more than three-eighths inch leeway either above or below this plane can be tolerated, preferably no more than one-fourth inch. if these limits are exceeded, satisfactory mixing is not obtained.

it is apparent that many widely different embodimerits of this invention may be made without departing from the scope and spirit thereof; and, therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. in an orchard heater having a burner pot with a first opening and a second opening upon which is mounted a burner stack and constructed to operate with a fuel introduced into said burner pot as a spray and ignited to give a primary combustion flame in said burner pot and a secondary combustion flame in said burner stack during operation of said orchard heater, the improvement comprising (1) an air-fuel mixer mounted on said first opening and constructed to operate in conjunction with (2) directional means constructed to direct the longitudinal axis of said primary combustion flame away from the walls of said burner pot and towards the vertical axis of said burner pot at an angle of from about 20 to 30 downward from the horizontal to more evenly distribute the heat generated by said flame, and to assure that between l said pri mary combustion flame in said burner pot and (2) said secondary combustion flame in said burner stack, complete combustion is achieved, thereby avoiding soot build-up during operation of said orchard heater.

2. Claim 1, wherein said first opening is on the top portion of said burner pot, said air-fuel mixer is a swirl cone and said directional means is a tube.

3. Claim 2, wherein said tube is a stovepipe elbow and said angle is about 23.

4. in an orchard heater having a burner pot with a first opening, a second opening upon which is mounted a burner stack, a duct running from said stack to said burner pot constructed to provide for the return of warm gases to said burner pot during operation of said orchard heater, and constructed to operate with fuel in troduced into said burner pot as a spray and ignited to give a primary combustion flame in said burner pot and a secondary combustion flame in said burner stack during operation of said orchard heater, the improvement comprising (1) an air-fuel mixer mounted on said first opening and constructed to operate in conjunction with (2) directional means constructed to direct the longitudinal axis of said primary combustion flame away from the walls of said burner pot and toward the vertical axis of said burner pot at an angle of from horizontal to about 30 downward from the horizontal to more evenly distribute the heat generated by said flame, and to assure that between (1) said primary combustion flame in said burner pot lIld (2) said secondary comcone and said directional means isa tube.

bustion flame in said burner stack, complete 6. Claim 5, wherein said tube is a stovepipe elbow Pusuoms q avoldmg soot bulld'up constructed to direct said longitudinal axis of said mg operation of said orchard heater.

. fl i 5. Claim 4, wherein said first opening Is on the top ame hot zomany portion of said burner pot, said air-fuel mixer is a swirl LII

Claims

1. In an orchard heater having a burner pot with a first opening and a second opening upon which is mounted a burner stack and constructed to operate with a fuel introduced into said burner pot as a spray and ignited to give a primary combustion flame in said burner pot and a secondary combustion flame in said burner stack during operation of said orchard heater, the improvement comprising (1) an air-fuel mixer mounted on said first opening and constructed to operate in conjunction with (2) directional means constructed to direct the longitudinal axis of said primary combustion flame away from the walls of said burner pot and towards the vertical axis of said burner pot at an angle of from about 20* to 30* downward from the horizontal to more evenly distribute the heat generated by said flame, and to assure that between (1) said primary combustion flame in said burner pot and (2) said secondary combustion flame in said burner stack, complete combustion is achieved, thereby avoiding soot build-up during operation of said orchard heater.

3. Claim 2, wherein said tube is a stovepipe elbow and said angle is about 23*.

4. In an orchard heater having a burner pot with a first opening, a second opening upon which is mounted a burner stack, a duct running from said stack to said burner pot constructed to provide for the return of warm gAses to said burner pot during operation of said orchard heater, and constructed to operate with fuel introduced into said burner pot as a spray and ignited to give a primary combustion flame in said burner pot and a secondary combustion flame in said burner stack during operation of said orchard heater, the improvement comprising (1) an air-fuel mixer mounted on said first opening and constructed to operate in conjunction with (2) directional means constructed to direct the longitudinal axis of said primary combustion flame away from the walls of said burner pot and toward the vertical axis of said burner pot at an angle of from horizontal to about 30* downward from the horizontal to more evenly distribute the heat generated by said flame, and to assure that between (1) said primary combustion flame in said burner pot and (2) said secondary combustion flame in said burner stack, complete combustion is achieved, thereby avoiding soot build-up during operation of said orchard heater.

5. Claim 4, wherein said first opening is on the top portion of said burner pot, said air-fuel mixer is a swirl cone and said directional means is a tube.

6. Claim 5, wherein said tube is a stovepipe elbow constructed to direct said longitudinal axis of said flame horizontally.