US2941586A

US2941586A - Liquid fuel heater

Info

Publication number: US2941586A
Application number: US545407A
Authority: US
Inventors: Foley Daniel Murray
Original assignee: WEST COAST STEEL PRODUCTS CO
Current assignee: WEST COAST STEEL PRODUCTS CO
Priority date: 1955-11-07
Filing date: 1955-11-07
Publication date: 1960-06-21
Anticipated expiration: 1977-06-21

Description

June 21, 1960 D. M. FOLEY LIQUID FUEL HEATER Filed Nov. 7. 1955 l I l *l l l INVENTOR.

BY Wyw;

UnitedStates Patent O LIQUID FUEL HEATER Daniel Murray Foley, New York, N .Y., assignorto West Coast Steel Products Co., Riverside, Calif., a corporatiouof California Filed Nov. 7, 1955, Ser. No. 545,407

3 Claims. (Cl. 15S-91) liquidA fuel, suchas fuel oil. Qn the top of this receptacle there is a cover in which there is an opening through which the receptacle can be refilled and through which'ia torch may be inserted for the purpose of igniting the fuel oil in starting the heater. This opening is normally covered by an adjustable air regulator which permits air .to enter the receptacle and to mix with vapors generated from the surface of the fuel oil. The usual cover has an upstandng collar which has now been more or less standardized to have a 6 diameter. On this collar there is positioned an upstanding stack. The stack frequently is made up of two or even more sections of sheet metal which telescopically fit together. The lower of these sections usually has air inlet openings formed in the walls thereof throughwhich' additional air may enter the stack to complete combustion. This lower section frequently f has the air inlet `openings in the form of downwardly directed louvers and consequently, it is frequently re'- erredto as the louvered `section of the stack. It consti- `tutes thevcombustion chamber of the heater inasmuch as most of the intense burningof the fuel takes place therein. This is highly desirable in that the walls of the louvered section become quite hot and tend to radiate 4the -heat laterally, it being desirable that a direct ascent of the hot gases and products of combustion be minimized.

It has heretofore been recognized in heaters of this character that it is highly desirable to return to the covered fuelreceptacle a portion of the heated products of '2,941,586 Patented June 21, 1960 ICC4 relatively expensive to manufacture. Also, the presence of the auxiliary stack or stacks at the sides of the main stack is such as to frequently interfere with the positioning of the heater beneath a tree which is to be heated and kept from freezing during cold weather.

A primary object of the present invention is to provide an improved liquid fuel heater wherein a portion of the products of combustion and/ or air are returned to the liquid fuel receptacle so vas to gain the advantages of more complete combustion elimination of smoke and elimination of soot deposits. However, instead of adding an auxiliary stack to the exterior of the main stack I have found that if a tube is positioned in the main stack which has proper dimensions or proportions with respect to the main stack, the desirable return or rte-circulation of a portion ofthe gases in the stackwill be self-induced through the tube. Consequently, it is possible for me to gain all of the advantages of more complete combustion and at the same time reduce expense of manufacture and the objection of having an auxiliary stack at the side of the main stack which interferes with the positioning of the heater beneath a tree.

With the foregoing and other objects in view, which will be made manifest in the following detailed description and specifically pointed out in the appended claims, reference is had to the accompanying drawings for an illustrative embodiment of the invention, wherein:

Figure 1 is a top plan view of a heater embodying the present invention; and

Pig. 2 is a sectional view taken substantially upon the line 2-2 upon Fig. l.

combustion and/ or some of the air that is admitted tothe staclcthrough the louver openings.` The advantages of "returning or re-circulating some of the products of cornbustion and/ or air admitted to the stack have been recognized in VUnited States Letters Patent No. 2,284,157, issued May 26, 194,2,` to Arthur Stephen Leonard. When a portion of the products of combustion and/or air admitted to the stack are returned to the fuel receptacle, a

frnore complete combustion seems to result in that heater Vinthe main stack. A portionY of the gases rising in the main stack, whether they be air or products of combustion, or a mixture of both, encounter the downwardly -directed entrance `to the auxiliary stack and on. passing therethrough are returned by the auxiliarystack to the Afuel receptacle.

An objection to that form` of construction which is disclosed in the Leonard patent is that the construction is Referring to the accompanying drawings wherein similar reference characters designate similar parts throughout, the improved heater employs for purposes of convenience, expense, and simplicity of manufacture, a fuel receptacle 10 vthat may be conventional. This fuel receptacle is designed to receive and hold an adequate supply of liquid fuel, such as fuel oil 11. It is equipped with a cover 12 and in conformity with conventional practice this cover has an upstanding, centrally located, collar 13. The diameter of'such collar has been more or less standardized by manufacturers of heaters of this type `to have a 6" diameter. `In the cover there is an opening M through which air may be admitted to the receptacle 1.0.V

The size of this'opening can be adjusted or varied by a rotatable `damper 15. The extentto which the opening is opened and the extent to which air is admitted tol the fuel receptacle lil governs to a large extent the rate of burning and the magnitude of the iiame. Y t Y On the collar 13 there is positioned an npstanding stack and this stack is usually formed of twolsections, the lower section being-indicated at 16 and th'e upper section at 17. These` two sections telescopically iit together and the lower section telescopes over the collar 13. The lower section 16 forms the combustion chamber of the heater and is commonly referred to as the louvered sectionin that downwardly directed louvers 18 are formed in its walls. These louvers are formed by horizontally slitting the sheet metal from which the lower section i6 is formed and depressing inwardly the metal below the'slit as indicated at 19. That portion of the metal which is immediately above theslit is pressed outwardly as indicated at 19 so thatthere are air openings formed in the walls of the louvered section for the ingress of air. As indicated on Fig. l, I prefer to ha've ten vertical rows of louvers in a louvered section whose diameter at the collar 13 is approximately 6, and whose diameter at the top is approximately 8". These louvers are arranged in circumferential rows, the lowermost row being located approximately 35/16 above the bottom of the louvered section. The uppermost row is preferably .located-12%" above the bottom of the louvered section. i

9 utransparent material.

3 The upper portion '17 ofthe stack 'is generally imperforate and is cylindrical and its height seems to have no important bearing upon .the present invention.

Within the louvered section there is disposed a central t tube 20 preferably formed of seamless steel tubing having a Wall Vthicltness'ofV l/s". Adjacent the top of 'this section of tubing steel straps 21 are welded to opposite sides thereof. Near the bottom ofthe tubing 20 a similar pair of straps 22 are welded toopposite sides thereof. These straps provide outwardly extending arms of upper and lower spiders, the lengths of which are such that they will engage the interior of thelouvered section between the louvers and support the .tubing therein with the top of the tubing v20 disposed atv an elevation that is preferably even with the rstrow-of lonvers beneath the top row of louvers. At all events the tcp of the tubing Zt? isY disposed below the top row of' louvers. The bottom of the tubing 20 extends down into the receptacle 10 a short distance. That is, itV extends below the collar 13 on the cover and below the. bottom edge of the louvered section.

I am aware that liquid fuel heaters of this general character have Aheretofore been provided wherein an 'openended tube is supported within the lower portion of the stack. However, in order to develop or self-induce a downward liow of air and/or products of combustion through the tube 20 .in order to gain the advantages of re-circulation, the relative proportions :of the tubing with relation to the louvered section are somewhat critical. ln the preferred embodiment of my invention the length of the tubing 20 is 12". and has an outside diameter of 2." with al wall thickness. It extends below the ,bottom of the collar 13 a distance of 11/2". In effect, there fore, the diameter of the tubing 2G is approximately one'- third of the diameter of the collar 13 vand the bottom of the louvered section. Also, the distance that the bottom of the tubing extends below the bottom of the collar 13 is approximatelyV three-fourths of the diameter of the tubing. The length of the tubing may be regarded as being roughly six times its diameter with the tubing extending downwardly beneath the collar on the. cover slightly less than a diameter.

' When the tubing and louvered: section have these relative proportions andthe position of the tubing in the louvered section is as vabove described, it will be found ythat a relatively strongldown-draft is self-induced in the vtubing returningto the fuel receptacle 10. products of combustion. and/ or air-thatis; admitted through. the uppermost louver openings. This down-draft. is readily observable ifl the upper section 17 of the stack is made of Also, if a lighted wick is lowered Vthroughthe upper section 17 to Va location immediately above the top of the tubing 20 the time from the wick Y will bfe observed tovbe drawn downwardly into the tubing. f

1; Exactly why these .relative proportions of tubing and louvered section Vwill..induce this. down-draftvand recirculation through the tubingI am unprepared testate.

,It is obvious, however, that for such adown-draft to 12 i als exist that pressure "over the'top of the tubing 20 must `the tubing 2.0 and the walls of the louvered section between the louver openings. The llame appears .to be generally circular with indentations therein opposite the Vlouver openings. The walls of the louvered section become quite hot and radiate heat laterally. The ascending products of combustion which ascend through the stack 17 are relativelyY cool and are readily observable tofbe free from smoke. ln fact, withthe opening 14 givenV an adjustment providing for a desired rateY of burning, if the. tubing 20 and its, spiders vare .removed from the stack, the heater will immediately begin to smoke noticeably.

Experiments have been conducted to ascertain what variation from the above given preferred dimensions as it is obvious that if the tubing 20 is made relatively short and of large diameter as compared with the diameter of the collar 13 that no .downward flow through the tubing will take place, On the contrary the flame Vwithin the receptacle iti will rise inside of the tubing as well as on the outside. On the other`hand if the tubing 20 is made very long and of very small diameter there will be no downward ow therethrough, or even if such ow does exist, its effect inproducing smokeless and sootless heater will be negligible.

Experiments that have been conducted as to possible variations are as follows:

TEST #1.

Tube Dimensions Other Facts Diameter,

Length, inchesv inches Comments: Fire burns up center of tube, inclined to choke, dleult, to light--very dirty-uncombusted gases are. not returned Comments: Return action ls present---retnrnl action not as strongcs. 12"

length x 2" diameter TEST #4 Comments: Length is ideal-diameter'allows slight return action 1% is; as small as you may go on diameter VTEST #EY 1% below bottomofstack.

Comments: ',Return action is present-not as strong as with 2" diameter "TEST #e 14 2 {ifg Wan' elowbottom of stack.

Comments: Return action is slight and only noticeable when regulator is Y' wide open-no returnl action present under normal adjustment. Tube 1s too long-top of tube is above top louver TEST #7 Y 1%" below bottomol stack:

Comments: No return action present-tube is too long TEST #8 y Y l/6"wal1. f l 15% 254e Tube flush; with bottom-ol' stack.

Comments: Return action 1s strongest As a conclusion from the results of these and other tests it is apparent that the length, diameter, and position of -tne tubing in the louvered section is somewhat critical. ln order to obtain the desired down-flow through the tubing, in a louvered section fitting on a 6 collar 13 the diameter of the tubing should be between 1%" and 3%. The length of the tubing should be between 10i/2" and 131/2. The tube must project downwardly below the collar 13 a minimum of 1" and not more than 2". The top of the tubing must be below the top of the top louver openings. Some downward ow through the tubing takes place if Ithe top of the tubing is slightly below the top of the top louver openings but the downward ow through the tubing is best when the top of the tubing 20 is approximately even with the row of louver openings next below.

It will be appreciated from the above described construction that the manufacture and installation of the tubing 20, together with its spider-forming arms is relatively simple and inexpensive. The tubing may be installed in a conventional heater very easily and at minimum expense. It is not essential that the louvered section have a 6 diameter at its bottom and an 8" diameter at its top. If the louvered section yis tapered in the opposite direction and has a shape somewhat similar to that illustrated in Figs. 1 and 2 of the Leonard patent above referred to, similar results are obtainable as long as the tubing has approximately the same relative proportions with respect to the collar 13, projects downwardly into the fuel receptacle below the collar from 1 to 2 and terminates at its top below the uppermost louver opening.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as deiined by the appended claims.

I claim:

1. A heater comprising a covered liquid fuel receptacle having an air inlet in the cover and a stack extending upwardly from the cover, said stack having air inlets in the walls thereof and a central tube supported therein, the top of which terminates below the uppermost air inlet openings in the walls of the stack, the bottom of the tube extending downwardly below the cover a distance approximately equal to three-fourths of the diameter of the tube, the internal diameter of the tube being approximately one-third of the diameter of the stack at its juncture with the cover whereby down-flow of gases through the tube is induced.

2. A heater comprising a covered liquid fuel receptacle having an air inlet in the cover and a stack extending upwardly from the cover, said stack having air inlets in the walls thereof, the top of which terminates below the uppermost air inlet openings inthe walls of the stack, the relative sizes of the parts being in approximately the following proportions:

Diameter of stack at juncture with the cover-6",

Air openings in wall of stack disposed between 3%6" and 121/2" measured vertically from juncture of stack with cover,

Diameter of tube 1% to 3%",

Length of tube lOl/2" to 13%", v

Distance to which bottom of tube extends below cover-1 to 2".

3. A heater comprising a covered liquid fuel receptacle having an air inlet in the cover and a stack extending upwardly from the cover, said stack having air inlets in trie Walls thereof and a central tube supported therein, the top of which terminates below the uppermost air inlet openings in the walls of the stack, the relative sizes of the parts being in approximately the following proportions:

Diameter of stack at juncture with cover-6",

Air openings in wall of stack disposed between 3%5 and 121/2 measured vertically from cover,

Diameter of tube-2",

Lenth of tube-12",

Distance to which bottom of tube extends below cover-11/z".

References Cited in the le of this patent UNITED STATES PATENTS 877,871 Snitjer Jan. 28, 1908 2,132,021 Forster Oct. 4, 1938 2,517,399 McCollum Aug. 1, 1950 FOREIGN PATENTS 697,100 France Oct. 21, 1930