US2043991A - Liquid fuel combustion apparatus - Google Patents

Description

June 16, 1936. G. DALEN ET AL LIQUID FUEL COMBUSTION APPARATUS Filed March 2l, 1954 25 Sheets-Sheet 1 I ToRs l 1 PZSERNEY 7 June 16, 1936. G, DALN ET AL 2,043,991

LIQUID FUEL COMBUSTTON APPARATUS Filed March 2l, 1934 3 Sheets-Sheet 2 ugr-regs F' .2. Y y afg/f {TTORNEY June 16, 1936. '6, DALN ET AL I 2,043,991

LIQUID FUEL COMBUSTION APPARATUS Filed March 2l, 1954 3 Sheets-Sheet 3 AL ATTOR EY Patented June 16, 1936 l UNITED STATES PATENT OFFICE LIQUID FUEL coMUs'noN APPARATUS Gustar nalen and Gustar Erik mrkiund, 'mama Sweden,

assignors to Svenska Aktiebolaget Gasaccumulator, Stockholm, Sweden, a corpcf ration of Sweden Application March 21. 1934-,l Serial No. 716,555

In Sweden December 13, 1933 7 claims. (C1. y15s- 5) Ihe present invention relates to control for liquid fuel combustion apparatus. More particul Still more particularly, theinvention relates.4

to the control of the liquid fuel supply to combustion apparatus of the vaporizing type in which vaporized fuel is continuously supplied to a burnerifrom a plurality of liquid fuel vaporizers which are operated 'alternatively with individual vaporizers in intermittent operation. lk The invention is particularly applicable to fuel combustion apparatus for devices such as domestic cook stoves of the heat accumulating type which require continuous burner operation and will be hereinafter described in its yapplication to a domestic cook stove of the above character. It

is to be understood, however, that the invention is not limited to cook stoves, nor is it limited .in its application to fuel combustion apparatus of the specificy kind illustrated by way of example.

Amongst the several'objects of the invention are; to provide novel and improved means for shutting offthe supply of fuel to a burner of the vaporizing type in the event proper vaporization of the fuel ceases;

-taining a desired constant temperature of a part or parts heated by heat from the burner; and to provide Asafety and control means as above stated for liquid fuel combustion apparatus of the vaporizing type in which vaporization of the fuel is effected by intermittent and alternative operation of a plurality of fuel vaporizers.

Further and more detailedobjects, together.

with the specific nature of the invention and the 0 advantages -to be derived from its use, may best be understood from a consideration of the follow-v ing description of one suitable form of apparatus for carrying the invention into effect.

In the accompanyingdrawings,forming part l;

Fig. 3 is a section taken on thermes-a of Fig. 2;

Fig. 4 is a sectiontaken on the line 4 4 ofr Fig. 2; l

to provide, in combination I i0 with such means, fuel regulating means for mainis provided bythe bottom wall of the vaporizing Fig. 5 is a section on an enlarged scale taken on the lines 5-6 of Figs. 1 and 2; and

Fig. 6 is a view taken on the line 6 6 of Fig. 2.

' Referring now to Figs. 1 and 2, the stove indi'- cated generally at A is of the type adapted to be v5 continuously maintained at elevated temperature and comprises a relatively heavy metal structure indicated generally at I0 and providing hot plates ,n I2 and i4 and an oven i6. A second low -temperature oven i8 may also be provided. 'I'he hot 10 plates I2 and I 4. and also oven I6 are adapted to be heated by conduction of heat through the metal from gases of combustionA which pass through channel 28 to a suitable stack opening 22 adapted to be connected to the chimney. The 15 metal structure l 0 is adapted to accumulate heat and is surrounded by suitable insulating material, such as asbestos or kieselguhr, indicated at 24, and the hot plates I2 and i4 are covered when not in use by insulated cover plates 26 and 28. v 20 The hot combustion 'gases for heating the structure I 0 are provided by a burner indicated generally -at 30 and adapted to burn a gaseous fuel mixture comprising air and hydrocarbon fuel vapor. Air for combustion'lis supplied to burner 25 30 through the passage 32 which is in communication with the surrounding atmosphere through the opening 34. Around the base of the burner 30 there is provided a metal mass 36 having two vaporizing chambers 38 and 40 therein (see Figs. 3Q 3 and 4).

Chambers 38 and 40 are each placed in communication with the lower portion of the burner 30 by means of passage .42 and the ports- 44 and 46. Chamber 38 has associated therewith a liquid fuel feeding'member 48, the lower. por- 35,

tion of lwhich provides a central fuel feeding tip from which liquid fuel is adaptedhto fall onto a vaporizing surface 52, which in this instance chamber. The vaporizing chamber and the lower 0 part of the fuel feeding member are connected by means of a pipe 54 and an annular space 56 communicating withpipe 54 surrounds the fuel feeding tip'oi' the member 48. Chamber 4,0 has associated therewith a like fuel feeding member 58 455 havinga fuel feeding tip 60 adapted to cause fuel to fall onto the vaporizing surface 62. Chamber 40 andmember 58 are connected by pipe 64 and tip 60 is surrounded` by annular space 66. 50

Fuel is supplied alternatively to one or the other of the -fuel feeding members by apparatus which will now be described. oLiquid hydrocarbon fuel is fed,vpreferably by gravity, from a suitable reservoir (not shown) through the supply line 68 (Fig. 5) through a strainer 10. in a chamber l2,

from which it flows through the passage 14 to a oat chamber 16 in which the level of iuid is maintained substantially constant by the float 18, which operates to control ow of fuel through the passage 14. From the oat chamber 16 fuel ows through the pipe 80, the labyrinth 82 and pipe 84 to a. feeding orifice 86 controlled by a needle valve 88. The orifice 86 is positioned above a cup-shaped receptacle 90 in which is plivotally mounted a plate 92 adapted to direct fuel either to the outlet passage 94 leading from chamber 98 in receptacle 90, or to the outlet passage 96 leading from chamber |00 therein. Chambers 98 and |00 are separated by the web |02. Passages 94 and 96 communicate vrespectively with the fuel feeding members 58 and 48, the connection between passage 94 and fuel feeding member 58 being shown in Fig. 2 and comprising an inclined conduit |04.` The fuel feeding members 48 and 58 and the receptacle 90 are preferably formed by a single integral casting, as shown in Fig. 2,

through which the severalfuell feeding passages are bored.

The annular spaces 56 and 66 surrounding the tips of each of the fuel feeding members are placed in communication with the surrounding atmosphere to permit a restricted amount of air to be admitted at these-places for a purpose to be explained later. In Fig. 2 the connection for this air supply to the fuel feeding member 58 -is shown at |06. l The vaporizing chambers 38 and 40 and the' lower portion of the burner are in communication with the overflow pipe |08, theouter end of this pipe terminating in a discharge opening ||0 (Fig. 5), beneath'which there is suspended an overow receptacle ||2. Receptacle ||2 is suspended from a spring bar or strip ||4, to which is attachedv stem l| I6 of the needle valve 88. As shown in Fig. 5, the-needle valve 88 is preferably made adjustable .with respect to the strip ||4 by means of suitable adjusting nuts'. The end of the strip I4 opposite that from which the receptacle ||2 is supported is fixed to the free end of a hollow curved expansion element |20 of the Bourdon tube type. The opposite end of the expansion element |20 is connected by means of a tube |28 to a thermostat element such as that shown at |29 in Fig. 1, which is placed in a position such that it will be responsive to the temperature of any desired 4part receiving heat froml the burner. Tube |28 and elements'l 29 and |20 are adapted to be filled with any suitable expansible thermostat fluid. The position of the end of the element |20 to which the tube position of lever |24, whichfis pivoted at |26 and is provided with an arm |22 bearing against or attached to the element |28 so as to cause movement of this element upon movement of the lever |24. The position of lever |24 is determined by the positionl of a cam |34 mounted on a shaft or spindle |35, which is advantageously carried to the exterior of the stove.V Lever |24 is held in contact with cam |34 by the action of a. spring |30 working against any suitable fixed abutment as that indicated at |32. Intermediate the enof the spring strip ||4, to which the element |2||\ attached,'andthe`place of attachment of the s `rn ||6 of the needle valve 88, there is attached an\adjus'tab'le stop |8, the position of which with respect to th strip may be adjusted by means of suitable adjusting nuts, and which is adapted in certain positions of the |28 is attached, is determined by the is bent so as to project through an arcuate slotV |44 in the outer casing |46 of the stove, and terminates in an indicator arm |48 having an actuating handle |50. The outer casing |46 of the stove preferably has marked thereon the scale or index |-|5, |5-|, as indicated in Fig. 6. 1

The metal mass 36 is preferably enclosed in insulating material indicated at |52, and air passing to` the air supply pipe 32 of the burner also advantageously circulates in the space |54 around the insulation |52 and alsol around the fuel feeding members and the parts providing the channels vfor supplying fuel and air to these members.

While the form of fuel burner employed constitutes per se no part of the present invention, the burner arrangement shown herein by Way of example, which forms the claimed subject matter Vof my copending application Serial No. 695,883,

filed October 30, 1933, is of advantageous form.

'In this burner arrangement the metal mass 36 provides. a cup-shaped space with the bottom of which passage 42 is in communication, and in the center of which there is disposed the perforated burner pipe |56. A second and larger perforated burn'er pipe |58, the lower end of which is above the lower end of pipe |56, surrounds pipe |56 to provide between the two pipes an annular space |60. 'A third pipe |62, larger in diameter than pipe |58 and imperforate, surrounds pipe |58. The lower end of pipe |62 is above the lower end of pipe |58. The space |60 between pipes |56 and |58 is in` communication with the pipe |64, which serves to place the burner in communication with the combustion gas channel in the structure I0.

The operation is as follows: Fuel vapor is burned in the space |60 by combustion air admitted' thereto through perfo- Irated pipes |56 and |58, both of which pipes are in communication with the air space |54. The heat of combustion heats the mass 36 to high temperature,a high temperature of this mass being readily maintained because of the fact that the mass is well insulated, and by conduction through the metal the vaporizing Asurfaces 52 and 62 are maintained at very high temperature, for example, 900 F. or higher. Liquid fuel drops or falls through the orifice 86 onto the plate 82 and flows through the associated fuel conduit to one of the fuel feeding members. From the tip ofthe fuel feeding member the fuel falls onto the hot vaporizing surface and lis substantially,

instantaneously vaporized. The vapor formed in the vaporizing chamber is drawn by the draft created by the burner through the passage 42 tothe space between the two perforated burner pipes. Due to the suction created by the burner' shaft, air is drawn through thepipes (one of which is shown at |06 ,in Fig. 2) to the spaces around the fuel feeding tips 50'an'd 60 of the two fuel feeding members, this admission of air being continuous with respect to both of the fuel feeding members since both of the vaporizing chambers are in uninterrupted communication with the burner and therefore are continuously subject tov draft from the burner whenever the burner is4 in operation. The quantity of air admitted around the fuel feeding orifice isrestrlcted, being insufficient in amount to form a combustible gas mixture with the fuel vapors being formed in the vaporizing chamber to which fuel is being admitted. As will be evident, the air admitted through a pipe such as pipe |06 will be relatively cool as compared with the temperature ofthe mass 36 and the parts associated therewith, and the purpose of this air supply is to enshroud the falling fuel so as to prevent premature vaporization thereof. By so enshrouding the falling fuel and conducting it to the fuel feeding member through passages which are relatively coolthe formation of carbon deposits at or adjacent to the fuel feeding member due either to premature vaporization or recondensation of fuel vapors on the wall surfaces is materially retarded if not entirely eliminated, and the formation of a carbonaceous deposit f a coke-like'nature on the f vaporizing surface is also retarded because of the fact that the oxygen content of the restricted quantity of air, while insufficient to form a combustible gas mixture in the vaporizing chamber, will tend to burn away such carbonaceous deposit as it forms.` Due to the introduction. of this restricted air supply to the vaporizing chamber, the accumulation of carbonaceous deposits of fuel residue in the chamber is very slow, but in time suflicient accumulation may occur to adversely effect the efficient operation of the vaporizer, particularly when a substantial accumulation of residue or coke forms on the vaporizing surface.

In order to permit the continuous operation of the burner for long periods Without interruption, and also in order to effect removal of carbonaceous accumulations from the vaporizers, a plurality of vaporizers is provided and after one vaporizer has been in operation for a period of time, which experience has indicated will result in the accumulation of an undesirable amount of residue in the vaporizing chamber, the supply of fuel to such vaporizer is cut off, and fuel is directed to another vaporizing chamber. It will bev evident that in a construction such as that disclosed, fuel vapor will be substantially immediately formed in -the vaporizing chamber to which fuel has been directed,so that there will be no interruption in the supply of fuel vapor to the burner. Even if there were sufficient inten ruption inthe supply of fuel vapor to cause the burner flame to be extinguished, the entire ap-y paratus is at such high temperature that ignition would automatically occur immediately upon the resumption of the supplying of fuel vapor.V The restricted supply of air admitted to the vaporizing chamber from which fuel has been cut off continues to fioW through this chamber under the influence of the burner draft, and because of the fact that the vaporizing chamber is continuously maintained at very high temperature, the'oxygen in the air continuing to ow to the vaporizing chamber combines with the carbonaceous residue therein and gradually burns away the deposits in the chamber while another vaporizing chamber is in operation.

With a fuel vaporizing arrangement of the kind shown, the formation of carbonaceous deposits' in the vaporizing chambers is so slow that continuous operationof the burner may readily be effected with but ltwo vaporizing chambers adapted to be operated in alternation. Experience has shown that where the apparatus is utilized in connection witluthe heating of a cook stove of the type illustrated, vaporization of the requiredv amount of fuel may be effected continuously by a single vaporizer for a period of vabout a month, but it is preferable to change operation ofA the vaporizers somewhat more frequently, and in order to insure the shifting of operation of the vaporizers at proper intervals, the index indicated in Fig. 6 is advantageously employed inr conjunction with the shifting lever |48. This index is advantageously marked ||5 and |5-I, the figures representing the days of a month, it being vintended that the shifting lever |48 be in the position shown in Fig. 6 during the period from the first to the fifteenth day of a given month, and in the opposite position during the period from the fifteenth of a given month to the rst of the succeeding month.

With fuel combustion apparatus-of the vaporizing type such, for example, as that hereinbefore described, it will be evident that serious difiiculty and even danger may arise if for any reason vaporization of the liquid fuel fed to the apparatus ceases, since in such event the apparatus is subject to ooding and overflow of liquid fuel. In order to prevent any possibility of this occurring, we have, in accordance with the present invention, provided the overfiow ves'sel ||2 acting on the needle valve 8B, the position of which is also under the` influence of the thermostat, the action of which is as follows: when the part which-is inheat conducting relation with the sure of the expansible thermostat fluid in the expansion element 20 is low, and this element contracts so as to lift the end of the spring strip I I4 to whichthe needle valve 88 is attached, thus providing for increased flow of fuel from the orifice 86. As the temperature of the parts" heated by the burner increase the pressure of the thermostatic uid increases in the element |20'.

-thermostat element |28 is relatively cold, the presand due to the expansion of this element under pressure, tending to straighten the element in the manner common to all Bourdon tubes the needle valve 88 is depressed, and the supply of fuel flowing over orifice 86 is .decreased until a stabilized condition is arrived at with only sufficient fuel being supplied to maintain the parts heated by the burner at the desired temperature. The adjusting means on the valve stem I I6 are ordinarily employed only for initial adjustment when setting up the apparatus, and adjustment of the thermostat to vary the temperature at which equilibrium is established by the thermostat is effected by adjustment of cam |34; It will be evident that if the cam |34 is moved in i clock-wise direction, as from the position shown in Fig. 5, the lever |24 will be moved in counterclock-wise direction about the pivot |26, and the element' |20 will be turned so as to effect an increase in the amount of fuel supplied through n the needle valve 88.

If for any reason, vaporization of the liquid fuel supplied to either of the vaporizing chambers ceases to occur at its proper rate, the'excess unvaporized liquid fuelwill accumulate and flow through pipe |08 toft'he receptacle ||2 ,and the j liquid fuel vaporizer for supplying gaseous fuelf Aadiusting the position of the stop H8. When this stop is not in contact withsa fixed abutment the receptacle H2 is supported by a lever the length of which is the full length of the part H4, but when the part i I4 is pulled downwardly to a position such that the stop I i8 comes in contact with a fixed abutment, the length of the lever is shortened. and its resistance to bending, due to the weight of the receptacle H2, increases. Consequently, by adjusting the position of the stop H8, the weight of liquid in the receptacle H2 necessary to eect closure of the needle valve may be readily fixed at any predetermined value.

By the above described arrangement, effective safety and control apparatus is provided which is very simple and reliable in operation. Also, by means of apparatus of the kind disclosed, it is possible to secure effective regulation and also safety of operation with vaporizing apparatus of the kind in which a plurality of separate vaporizers are employed. As previously stated, however, it is to be distinctly understood that in its broader aspects the present invention is not limited to combustion apparatus for any specific use, nor is it in its broader aspects to be limited to liquid `fuel combustion apparatus of the specific kind hereinbefore described by way of example. The invention is capable of embodiment in many different specific forms of apparatus, and is accordingly to be understood as including all such forms of apparatus as may fall within the scope of the appanded claims.

What we claim is:

1. Apparatus of the character described come. prising a device adapted to be maintained atelevated temperature due to'the heat of gases of combustion, a burner adapted to burn a gaseous fuel mixture for supplying heat to said device, a vaporizer adapted to vapor ze liquid fuel for combustion in the burner, a supply conduit for sup-V plying liquid fuel to the vaporizer, a control valve in saidconduit having a movable valve member, a curved tube expansible upon' increase in the temperature of said device, a spring element fixed to the free end, of said tube said movable valve member being mounted on said spring element to move toward closed position upon expansion of said tube, and an overflow vessel for receiving un- 4vaporized liquid fuel from the vaporizer suspended vfrom saidvspring element to close said valve in the event vof fluid fuel overflow.

2. In apparatus of the character described, a,`

vapor to Ia burner, a curved tubular thermostat element having,a fixed end and a free end, said element being expansible in response to increase in heat supplied by the burner, a spring element secured at one end to the free end of said tubular element, a supply conduit for supplying liquid fuel to the vaporizer, a control valve in said conduit having a movable valve member secured to said spring element so as to be moved toward closed position by expansion of said tubular element, means for adjusting the position of said tubular element, and means actuated by the weight of unvaporized liquidv fuel overflowing from Asaid''valgxnlzer and acting onsaid spring member for closing said valve.

3. In apparatus of the character described, a liquid fuel vaporizer for supplying gaseous fuel vapor to a burner, a curved tubular thermostat element having a fixedend and a free end, said element being expansible in response to increase in heat supplied by the burner, a spring element secured at one end to the free end of said element. a supply conduit for supplying liquid fuel to the vaporizer, a control'valve in said conduit having a movable valve member secured to said spring element so as to be moved toward closed position by expansion of said tubular element, 5 means for adJusting the position of said tubular element, an overflow vessel suspended from said spring element for closing said valve due to overflow of unvaporized liquid fuel from the vaporizer to said vessel a fixed abutment, and adjustable 10 means associated with said spring element and contacting said fixed abutment in certain positions of the spring element for determining the weight of liquid fuel in said overflow vessel required to effect closure of the valve.

4. Apparatus of the character described comprising a device to be maintained at elevated temperature due to the heat of gases of combustion, a burner for burning a gaseous fuel mixture for supplying heat to said device, a plurality of liquid 20 fuel vaporizers for supplying fuel vapor to said burner, each of said vaporizers comprising a vaporizing chamber and a vaporizing surface arranged to be heated from said burner to a temperature suilicient to vaporize liquid fuel, fuel feeding members for causing liquid fuel'to fall on said vaporizing surfaces, passages providing uninterrupted communication between said vaporizing chambers and said burner. means for supplying fuel alternatively to different fuel feeding members including a common fuel supply conduit, a control valve in said conduit. and a thermostat for regulating said valve in response to variations in the heat requirements of said device. 35

5. Apparatus of the character described comprising a device to be maintained continuously at elevated temperature due to heat of gases of combustion, a burner for burning a gaseous fuel mixture for supplying heat to said device, a plu- 40 rality of liquid fuel vaporizers for supplying fuel vapor to said burner, each of said vaporizers comprising a vaporizing chamber and a vaporizing surface arranged to be heated from said burn- Y er to a temperature sufficient to vaporize liquid fuel, fuel feeding members for causing liquid fuel to fall on said vaporizing surfaces, passages providing uninterrupted communication between said vaporizing chambers and said burner, means for supplying fuel alternatively to different fuel feeding members including a common fuel supply conduit, a control valve in said conduit. and means responsive to overflow of unvaporized liquid fuel from any one of said vaporizing cham- -fuel vapor to said burner. each of said vaporizers comprising a vaporizing chamber and a vaporizing surface arranged to be heated from said burng er to a-temperature sumcient to vaporize liquid fuel, fuel feeding members for causing liquid fuel -to fall on said vaporizing surfaces. passages providing uninterrupted communication between said vaporizing chambers and said burner, means for supplying fuel alternatively to different fuel feeding members includingv a4 common fuel supply conduit. a control valve in said conduit, means for regulating said valve in response to variations in the heat requirements of said device, and

means responsive to overow of unvaporized 75 liquid fuel from any one of said vaporizing chambers for closing said valve.

' 7. Apparatus of the character described com-- prising a device to be maintained continuously at elevated temperature due to heat of gases of combustion, a burner for burning a gaseous fuel mixture for supplying heat to said device, a plurality of liquid fue] vaporizers for supplying fuel vapor to said burner, each of said vaporizers comprising a vaporizing chamber and a vaporizing surface arranged tov be heated-from said burner to atemperature suflcient to vaporlze liquid fuel, fuel feeding members for causing liquid fuel to fall on said vaporizing surfaces, passages providing uninterrupted communication between said vaporizing chambers and said burner, means for supplying fuel alternatively to different fuel feeding members including a common fuel supply conduit, a control valve in said conduit, thermostat means for regulating theposition of said valve in response to variations in the heat requirements of the device, and manually operable means for adjusting saidthermostat means.

GUsTAF DALN. GUs'I-AF ERIK BJRKLUND.

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