US1700961A - Apparatus for heating fluids - Google Patents

Description

Feb. 5, 1929. 1,700,961

s. P. VAUGHN APPARATUS FOR HEATING FLUIDS Filed Sept. 5, 1924 2 Sheets-Sheet 2 Ooo oooooooocboooo /WI/NVENTOR Patented Feb. 5, 1929.

UNITED STATES PATENT OFFICE.

SlDNEY P. VAUGHN, OF THE UNITED STATES NAVY, ACKERMAN, MISSISSIPPI, AS- SIGNOR T0 THE SURFACE COMBUSTION COMPANY, INC., OF NEW YORK, N, Y., A COR- PORATION 0F NEW YORK.

APPARATUS FOR HEATING FLUIDS.

Application led September 3, 1924. Serial No. 735,638.

'Ihis invention relates to apparatus for heating fluids in which combustible gaseous mixtures or gaseous mixtures of an explosive nature are burned to heat the fluid. It relates particularly to apparatus for generating steam. heating water and air, but it may be used for other purposes to meet the demands for an efficient method of transmitting the heat of combustion to a fluid to be heated. lVhile such an apparatus is particularly adapted for use with gaseous or vaporized fuels of various kinds. it may be used with good results with liquid fuels atomized or s raycd in a finely divided state and combined) with a. suitable quantity of combustion supporting gas such as air.

The principal object of this invention is to provide an apparatus of this character in which a large proportion of the potential energy of the fuel is liberated in the form of' radiant heat localized in close proximity to fluid heating elements that absorb the radiant heat and transmit the heat to a fluid to be heated.

Another object of my invention is to maintain the gaseous combustible mixture while in a state of combustion under a pressure nearly equal to the pressure of the mixture in the supply chamber. By keepingr the gases while in a state of combustion under a pressure, combustion is accelerated and the higher the pressure the more rapid the combustion and resultant increase in the temperature olA the combustion space.

Another object is to provide a simple and effective method to prevent back-flash or backwa rd propagation of the flame through the advancing mixture toward the source of supply, or into the. combustible mixture supply chamber. Back-flash may be prevented either by causing the explosive mixture to flow toward the combustion zone with a velocity greater than the rate of propagation of inflammation, or, when the velocity of the mixture is less than the rate of propagation of inflammation, by interposing a flame interrupting screen or passage way between the source of explosive mixture supply and the zone of combustion, and maintaining the flame interrupting properties of' such screen or passage Ways. To accomplish this object when the flow of the mixture is either greater or less than the rate of' propagation of' inflammation, I provide in the burner, passage ways 0r burner ports between the combustible mixture supply chamber and the zone of combpstion, of sufficiently small cross sectional area as to have the property of llame interruption when maintained below the ignition temperature of the mixture, and I maintain the flame interrupting property of the passage ways or burner ports by forming said passage ways or burner ports in one of the fluid heating elements forming the burner and using the fluid to be heated as the cooling medium. In such an arrangement all the heat absorbed by the burner is utilized and not lost as would be the case ifjvater was used only to cool the passage Ways.

Another object is to provide a simple and effective means to warn one when the fluid to be heated is not being supplied to the fluid heating element forming the burner in sufficient quantity to keep the fluid heating element at a temperature below a predetermined safety temperature. I accomplish this object by using the fluid to be heated as a means for maintaining the flame interrupting properties of the passage Ways or burner ports formed in the fluid heating element forming the burner for the passage of the combustible or explosive mixture to the zone of combustion.y By utilizing a. fluid heating element to form that part of the burner containing the flame interrupting passage ways leading from the combustible mixture supply chamber to the zone of combustion it will be seen that if the fluid to be heated is not supplied to said fluid heating element at a rate to maintain its flame interrupting properties the combustible of explosive mixture in the supply chamber will become ignited either by spontaneous combustion due to heating the said fluid heating element above the ignition temperature of the combustible or explosive mixture, or by back-flash through the flame interrupting passage Ways when the velocity of the explosive mixture through the passage ways is less than the rate of propagation of inflammation. lVhen the combustible or explosive mixture is ignited in the supply chamber a noise similar to a blow torch or an explosion will Warn one that the fluid supply to the element forming the burner is not sufficient for safety.

Another object is to provide an apparatus in which the resistance to the flow of the combustible gaseous mixture and products of combustion is reduced to a minimum. A further object is to provide a means to prevent the fluid heating elements becoming too hot and burning for lack of flow of fluid through them to keep them cool by incorporating a thermostatic device to automatically stop the flow of fuel when the fluid heating elements become too hot.

The invention in its preferable form comprises three cylindrical fluid heating elements, spaced and concentrically arranged around a central combustible gas supply chamber, having connected parallel fluid heating passages circumferentially or vertically formed therein and gas passages or openings extending through the walls of the element from the interior to the exterior of the cylinder, and between but not connected with the fluid heating passages and adapted to conduct the gases. The inner or first fluid heating element forms the walls of a combustible gas supply chamber in which a fuel in a gaseous or vaporous state is mixed with a suitable quantity of combustion supporting gas to form a combustible mixture. The space between the inner or first fluid heating element and the second fluid heating element forms a. combustion chamber in which a combustion bed consisting of granular refractory material in loose or bonded form is placed to form a porous and permeable element against which or in which the combustion of the gaseous mixture takes` place around and against the granules in the form of surface or flameless combustion. The first and second fluid heating elements absorb the greater portion of the radiant heat of combustion and the third fluid heating element absorbs the remainder of the heat in the products of combustion. The combustible gaseous mixture passes from the mixing chamber through the gas passages in the first fluid heating element into the combustion chamber or combustion bed where combustion takes lace. The products of combustion are disc arged through the gas passages in the second and third fluid heating elements. The gas passages in the second fluid heating element through which the products of combustion escape are ot' such a size that a pressure will be maintained in the combustion bed nearly equal to the pressure acting upon the combustible mixture entering the combustion space, or of such a size that the products of combustion are discharged with a velocity nearly equal the velocity of the gaseous mixture entering the combustion space. The velocity of the colnbustible mixture entering the combustion space and the velocity of the products of combustion leaving the combustion space may be of any desired velocity and the pressure in the combustion space of any desired pressure, but the velocity of the mixture at the point of combustion in the combustion space must not exceed the rate of propagation of inflammation through the mixture. or have a velocity that will cause the mixture to pass through the combustion space before combustion of the mixture is complete. In such an arrangement the refractory combustion bed will be kept incandescent practically throughout its entire thickness and radiate heat to all coils in any particular part of' the bed.

While any one of' the various methods of combusting fuel by the ,so-called surface or flameless combustion processes as well as the flame type of combustion may be utilized, the preferred method is that of using a thin refractory combustion bed composed of loose granular material of about 1,61 t-o 1% in size supported between two fluid heating elements and directing a combustible gaseous mixture in a state of combustion into the bed to raise it to an incandescent state. In such a bed the resistance to the flow of the mixture is reduced to a minimum and incandesccnce is produced throughout the entire thickness of the bed which results in radiant heat being transmitted to all fluid heating elements. In such an arrangement a wide variation in the amount of' fuel combusted may take place without lowering the efficiency of the apparatus.

Heretofore apparatus for burning explosive gaseous mixtures have provided various devices to prevent back-flash into the gas mixing chamber. In addition to causing the gaseous mixture to flow into or against the Combustion bed with a velocity greater than the rate of propagation of inflammation through the mixture to prevent back-flash, some have a very thick diaphragm made up of bonded refractory granules from ,i to 1/8 in size which requires a considerable pressure in the mixing chamber to overcome the resistance to the flow of the mixture through the bed. Others have a considerable quantity of heat conducting metals to conduct the heat away from the gas passages through which the gases pass into the combustion bed to keep the passages at the proper temperature to prevent back-flash. All of these methods are rather expensive and can be used for certain purposes and under certain conditions only and are not adaptable to an apparatus for heating fluids in which compactness is desired. By having the fluid to be heated act as a cooling agent to keep the gas passages in the fluid heating element forming the supply chamber cool, back-flash in the supply chamber will be eliminated in a simple and efficient manner.

In the accompanying drawings I show a simple form of apparatus made in accordance with the invention together with moddll ifications thereof, in which like numerals refer to like parts and like elements throughout the several drawings.

In the drawings:

Fig. 1 shows a vertical sectional View of an arrangement of the apparatus for heating liquids.

Fig. 2 shows a plan view of the apparatus, partly in section, of the apparatus illustrated in Fig. 1.

Fig. 3 shows a vertical sectional view of another arrangement of the apparatus for heating air as Well as liquids.

Fig. 4 shows a sectional plan view on line A-A Fig. 3.

Fig. 5 shows a modified arrangement of the combustion bed.

Fig. 6 shows another modified arrangement of the combustion bed.

Fig. 7 shows still another modified arrangement of the combustion bed.

Fig. 8 shows a modified construction of the fluid heating elements.

Fig. 9 shows another modified construetion of the fluid heating elements.

Figs. 10 and 11 show a modified construction of the gas passages in the fluid heating elements forming the combustible mixture supply chamber. Fig. 10 is a sectional view on line B-B Fig. 11.

The apparatus illustrated in Figs. 1 and 2 represents a simple form of construction of my invention in which is provided three cylindrical fluid heat-ing elements7 (I, 7;, and c, constructed of tubing coiled in cylindrical helical coils concentrically arranged within a casing 1 around a combustible mixture supply chamber 2 and connected at the bottom with a feed header 3 and at the top with a discharge header 4. The inner coil (a) forms the Walls of the chamber 2 from which a combustible mixture is supplied to the combustion chalnber 11". One end of chamber 2 is closed by an impact element 5 against which the combustible mixture entering the chamber impinges. The impact element is arranged to absorb sulicient heat from the adjacent combustion chamber 11L to vaporize any particles of liquid fuel that may enter the chamber with the gaseous or vapor mixturc. The other end of the chamber 2 is closed with the exception of an o ening 6 formed by an injector 7 secured) in the closure through which the fuel and a combustion supporting gas are admitted in proper proportions to form a combustible mixture. In the apparatus illustrated the fuel in a gaseous or vapor state is supplied under pressure from an injecting nozzle 8 suitably positioned over the opening 6 and attached to a pipe line 9 connected with a suitable source of fuel supply. When the gaseous or vaporized fuel leaves the injecting nozzle 8 under pressure and at a high velocity it ex ands, mixes with and carries with it a su cient amount of air or other combustion supporting gas to form a combustible or explosive mixture. Small openings 10 in the fluid heating element to) coil. Such an arrangement will prevent back-flash into the supply chamber 2 so long as the proper amount of fluid to be heated is passing through the coils. A

is arranged eoncentrieally second coil (b around coil (ai but is spaced therefrom to form a combustion chamber between the two coils in which is placed a suitable qualitity of loose granular refractory material that forms a combustion bed of a porous and permeable nature in which combustion of the combustible mixture takes place in the form of surface of flameless combustion. Openings or gas passages 12 are formed in the second coil or fluid heating element (b) by spacing the turns of the coil of the element the required distance apart through which the products of combustion are discharged. A third coil or fluid heating element (c) with gas passages formed therein by spacing the turns of the eoil is concentrieally arranged around the second eoil (Il) and spaced therefrom a suitable distance to permit the escape ot' the products of' combustion which are discharged from the easing 1 through a suitable opening 13 formed therein.

An electric sparking element 19. or pilot flame if desired. is provided between the second and third heating elements to ignite the combustible mixture. the combustion zone of which reeedes into the refractory colnbustiou bed immediately upon ignition.

To prevent the burning ot' the fluid heating elements should the fluid supply passing through them to keep them cool fail, there is provided a suitable cut-off valve 1H in the fuel line operated by a diaphragm 17 that is acted upon by the expansion of a suitable fluid contained in thermostatie tubes 14 and 15. One of the thermostatie tubes 14 is placed in the combustible mixture supply chamber :2 and the other is placed between the outer coil and the easing. Both are connected by a pipe lf3 to the diaphragm 17. Then back-flash oecurs in the supply chamber 2 due to overheating ot' the fluid heating element (a) forming the supply chamber, the heat of the burning mixture causes the fluid in the thermostatie tube 14 to expand and operate the valve 18, and when the outer fluid heating coils (li) and (e) become so hot as to cause excessive heating of the products of combustion the fluid in the thermostatic tube 15 expands.

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The expansion of the fluid in either thermostatic tube operates the valve 1S and stops the flow of fuel.

In Figs. 3 and 4 an apparatus is shown in modified form in which 3 sets of vertical tubes, (a) (7)) and (c), are concentrically spaced around the combustible mixture supply chamber 2 in the place of coils for fluid heating elements. The refractory combustion bed is placed between the first (a) and second (b) set of" tubes. The operation of this arrangement is the same as for the arrangement shown in Figs. 1 and 2, and the elements comprising the structure which perform the same function as like elements in Figs. 1 and 2 are referred to by the same numerals used to designate the parts in Figs. 1 and 2.

In Fig. 5 the application of the method of combustion described in Patent No. 1,308,364 issued to C. E. Lucke and Patents Nos. 1,223.248 and 1,222,922 issued to W. A. Bone, J. IV. IVilson and C. D. McCourt is shown, in which the combustion Zone is con'- fined to the outer surface of a porous and permeable refractory bed or diaphragm. rIhe heat arrows show the flow of' the gases through the apparatus.

In Fig. 6 the application of the method of combustion described in Patents Nos. 1,146,724 and 1,146,726 issued to C. E. Lucke is shown, in which the combustible gaseous mixture is caused to flow with a velocity greater than the rate of propagation of inflammation through the mixture against a porous and permeable refractory bed 11 and causing the mixture to burn at the impact surface and discharging the products of combustion through the bed.

In Fig. 7 the application of a dense refractory impact bed against which the combustible mixture in a state of combustion impinges is shown. The products of combustion are discharged around the open ends of the impact bed and directed against the outer fluid heating elements so that the heat of the products of combustion may be absorbed. Since the impact surface is raised to a state of incandeseence the greater part of the heat is transmitted by radiation to the inner fluid heating element and a part of the heat is transmitted through the impact bed and absorbed by the second fluid heating element (b adjacent thereto.

In Fig. 8 a modi led form of construction of the fluid heating elements particularly suited to heating air is shown. Heat conducting vanes 20 are provided in the fluid heating passages for transmitting the heat from the Walls to the air to be heated.

In Fig. 9 another modified form of fluid heating element of one piece construction is shown in which the gas passages 10 are formed in the element at the time it is moulded.

In Fig. 10 a method of forming a series of gas passages 10 between the turns of the coils of a fluid heating element (a) instead of having one continuous passage is shown.

While I have shown only a few modifications of the structure of the apparatus it is apparent that many modifications in the structure and arrangement may be made without departing from the spirit of the invention as set forth in the following claims.

lVhat I claim is:

1. In a fluid heating apparatus a structure providing fluid heating elements with passages formed therein to receive the fluid to be heated, a combustible mixture supply chamber formed by one of the fluid heating elements, a porous and permeable combustion bed between the fluid heating element forming the combustible mixture supply chamber and a second fluid heating element, gas passages in the fluid heating element forming the combustible mixture supply chamber connecting said chamber with said combustion bed and adapted to be cooled by the fluid to be heated, and gas passages in the second fluid heating element through which the products of combustion are discharged from the combustion bed.

2. In a fluid heating apparatus, a structure providing a. porous and permeable combustion bed formed of granular refractory material supported between two fluid heating elements having passages formed therein to receive a fluid to be heated, a combustibIe' mixture supply chamber formed -by one of the fluid heating elements, openings in said fluid heating element connecting said supply chamber with the combustion bed and adapted to be cooled by the fluid to be heated, openings in the other fluid heating element through which the products of' combustion are discharged, and a third fluid heating element adapted to absorb heat from the products of combustion.

3. In a fluid heating apparatus a porous and permeable combustion bed in a combustion space between fluid heating elements adapted to heat a fluid and having gas passages or openings formed therein and cooled by the fluid to be heated, one of said fluid heating elements forming the Walls of a combustible mixture supply chamber and having said gas passages formed therein for the passage of a combustible mixture from the supply chamber to the combustion space, and the other fluid heating elements having said gas passages formed therein for the passage of the products of combustion from the combustion space.

4. In a fluid heating apparatus a combustion space between two fluid heating elements, one of which forms the walls of a combustible mixture supply chamber and having openings formed therein adapted to be cooled by the fluid to be heated and through which the combustible mixture from the said supply chamber enters the combustion space, and openings in the other fluid heatin element for the passage of the products ofg combustion from the combustion space.

5. In an apparatus for heating fluids, fluid heating elements comprising an inner cylindrical helical coil of tubing and a seca ond cylindrical helical coil of tubing concentrically spaced around said Yinner coil, a combustible mixture su pply chamber formed by said inner coil, a porous and permeable combustion bed composed of granular refractory material su ported between the said coils, apertures ormed between the turns of the coils of said inner coil for the passage of a combustible mixture from the suppl chamber into the combustion bed and coole by the fluid to be heated, apertures between the turns of the coil of the outer coil through which the products of combustion are discharged, means for supplying a combustible mixture to the combustion bed, and means for automatically cutting off the fuel supply if the combustible mixture in the supply chamber becomes ignited or if the fluid heating elements attain a predetermined temperature.

6. In an apparatus for heating fluids, a combustion c amber, a combustible mixture supply chamber formed by a fluid heating element having apertures therein cooled by the fluid to be heated for the passage of a combustible mixture from the supply chamber to a combustible chamber adjacent said supply chamber, means for supplying a combustible mixture to the supply c amber and through said apertures into the combustion chamber, and means for automatically cutting ofl' the fuel supply and stopping combustion if back-flash occurs to said supply chamber.

In an apparatus for heating fluids, a combustible mixture su ply chamber, a combustion chamber, a uid heating coil forming the wall of the combustible mixture supply chamber, the turns of the coil being spaced to form narrow apertures, saidapertures beingI cooled by the fluid in the coil, a second vcoil surroundin the firstmentioned coil, the two coils orming the combustion chamber, and a porous and permeable combustion bed composed of granular 'refractory material arranged between the said coils.

8. In an apparatus for heating fluids, a combustible mixture supply chamber, a combustion chamber, a fluid heating coil forming the wall of the combustible mixture supply chamber, the turns of the coil being slightly spaced to form narrow apertures, said apertures being cooled by the fluid in the coil, a second coil surrounding the first-mentioned coil, a porous and permeable combustion bed composed of granular refractory material arranged between the said coils, a third coil surrounding the second-mentioned coil, a thermostatic tube arranged in the combustible mixture chamber, and another thermostatic tube arranged between the two outer coils, said thermostatic tubes controlling the supply of fuel.

9. In a fluid heating apparatus, the combination of a tubular chamber into which combustible gases ma be introduced prior to being combusted, tlie walls of the chamber having openings through which said gases may pass to the exterior thereof, said walls being constructed to permit the fluid to be heated to be passed therethrou h, and a layer of porous and permeable re ractory material adjacent the outer surface of said element and in the interstices of which material the combustible gas issuing out of said chamber may be combusted.

10. In a fluid heating apparatus, the combination of a tubular chamber into which combustible ases ma be introduced prior to bein com usted, t e walls of the chamber having openings through which said gases may pass to the exterior thereof,

said walls belng constructed to permit the l fluid to be heated to be passed therethrough, a second fluid heating element surrounding the walls of said chamber in spaced relation therewith, and a body of orous and permeable refractory materia interposed between said elements and in the lnterstices of which material the combustible gases issuin out of said chamber may be combuste 11. In a fluid heating apparatus, the combination of a pair of telescopically arranged and laterally spaced fluid heating elements, the space with1n the confines of the innermost elements constituting a chamber into which combustible gases may be introduced prior to being combusted, the walls of said elements havlng openings therethrough, a body of porous and permeable refractory material lnterposed between the fluid-heating elements and in the interstices of which material said gases flowing out of said chambers may be combusted.

12. In a fluid-heating apparatus, the combination of a refractory body having an interior chamber, the walls of said body being porous and permeable and constituting a combustion bed for combustible fluids, means for introducing combustible fluids into said chamber, means within said chamber having a heat-absorbing capacity suflicient to revent the combustible fluid within said c amber from becoming ignited by the heat from said combustion bed, and heat-absorbing means surrounding the exterior of said refractory body and constructed to contain fluid to be heated.

13. In an apparatus for heating fluids,

fluid-heatingr elements comprising an inner cylindrical element and a second cylindrical clement concentrically spaced around said inner element, a combustible mixture supply chamber formed bv said inner element, a porous and permeable combustion bed composed of granular refractory material supported between said elements, apertures formed in the inner element for the passage of a combustible ,mixture from the supply chamber into the combustion bed and cooled by the fluid to be heated, apertures formed in the outer element through which the products of combustion are discharged, means for supplying a combustible mixture to the combustion bed, and means for automatically cutting off the fuel supply if the combustible mixture in the supply chamber becomes ignited.

In testimony whereof I have hereunto set 20 my hand.

SIDNEY P. VAUGHN.

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