US1223308A - Diaphragm apparatus for burning gases. - Google Patents

Description

W.A. BONE, J. W. WILSON & C. D. McCOURT.

DIAPHRAGM APPARATUS FOR BURNING GASES. APPLICATION FILED 5.20. 1912. RENEWED mm. 7. 1917. A

1,223,308. A Patented Apr. 17, 1917.

WITNESSES Q dNVEI/TORS ilhd '%:Ih -4hmr ATTORNEYS STATES PATENT oFFIoE. j

RTHUR DONE, or mains, JAMEs WILLIAM wILsoN, or ARMLRY', LEEDS, .AN' CYRIL ouGLAs MoCOUBT', OF LONDON, ENGLAND, AssIGNoRs To RADIANT HEATING LIMITED, or LoNDoN, ENGL ND, A coRPoRATIoN or GREAT BRITAIN.

. DIAPHRAGM APPARATUS roR BURNIN GASES.

Speciflcation of Letters Patent. "Patented Apr. 17, 1917.

Original application filed October S, 1910, Serial No. 586,058. Divided and this application filed February 20, 1912, Serial No. 678,912. Renewed March 17,1917. Serial No; 155,618.

To all whom it may concern:

Be it known that We, WILLIAM ARTHUR BONE, of Leeds, in the county of York, Eng land, JAMES WILLIAM WILsoN, of Armley, Leeds, in said county, and CYRIL DOUGLAS MoCo'UR'r, of 45 Braxted' Park', Streatham Common, London, S. W., England, subjects of the King of Great Britain, have made certain new and useful Inventions Relating to Diaphra -Apparatus for Burning Gases, of which the following is a specification, taken in connection with the accompanying drawing, which forms part of this application, which is based upon and contains subject-matter taken from our 0.0-" ending United States application Serial 0. 586,058, filed October 8, 1910. This invention relates to apparatus for utilizing the accelerating influence of the 1n-- candes'cent surface of a highly porous refractory diaphragmupon the' combustion of a suitable explosive mixture of gaseous fuel and air fed in large volume through the diaphragm toward its heated outer surface, so that a -largefproportion'of the .potentlal energy of the fuel is liberated as radiant energy from theincandescent surfaceso as to be available in connection with many Industrial gas heating operations. When an. ex-. plosive mixture of coal gas and air, for 1n stance, in their combining proportions .or with air in slight excess thereof is passed at suitable veloclty, or suitable quantity, through the pores or interstices of a suitable porous refractory diaphragm into its incandescent surface layer a highly accelerated and substantially fiameless combustion of the gas takes place within the interstices,

pores or parts of the incandescent diaphragm layer which aremore or less 1m-.

pregnated or in-contact with the'gaseous;

mixture; and ener thus developed in large amounts by this intensified, complete and eflicient combustion is absorbed by 'theadjacent surface layer of the diai hragm and maintains it in a state of incandescence thus securing a very convenient and efiicient source ofradiant energy. This highly-accelerated, or intensified surface combustion seems to be t6 the emission of char ed corpuscles ore'isctrons from such incan escent solids, and the consequent formation of,

layers of electrified or ionized gas in which the temperature attainable in any particupressure an phragm unit.

the chemical changes incident to combustion proceed with extraordinary rapidity. It has been demonstrated that the incandescent solid plays an active and important part in I the combustion of the explosive gaseous mix* ture under these conditions, the particles of the incandescent solid apparently forming a composite system with the adjacent molecombustible vapors, natural gas and mix-' tures thereof, all of which are hereinafter referred toas combustible gases, although lar case Will naturally depend upon the calorific intensity of the gaseous material employed. The combustible gas is combined with air orother available supporter of-combustion in preferably substantially the. combimng proportions or with'a slight excess or' deficiency of air, although the proportions of the constituent gaseous materials may vary considerably and still's'ecure an explosive gaseousmixture, such as is capable of explosive combustion or inflammation, possibl under conditions of increased temperature. 7

In the illustrative embodi-'me n'ts of this inventionshown in the drawings in a somewhat diagrammatic way,-

v Figure 1 is a vertical central section through a form of diaphragm apparatus.

Fig. 2 is a similarvlew through a pair of; opposed diaphragms, r

Fig: 3 is a similar view showing-an inverted convex diaphragm in connectionwith a hood and flue. v

Fig. 4; shows in section a tubular dia- Fig. 5, is a" diagrammatic view showing a magnified'section of the diaphragm structure;and I Fig. 6 is similar view showing diagram; matically one of thechannels in'such porous 1 diaphragrns.

'cules of the combining gases, so that such I The porous refractory diaphragm may be given any suitable shape so as to have the desired form of incandescent outer surface from which the heat is transmitted. In the illustrative form of diaphragm unit shown in Fig. 1 the porous and permeable diaphragm 1 may be in the form of a flat plate of sufliciently refractory material preferably formed of. agglomerated or united particles or grains of substantially uniform size so as to form tortuous channels for the passage of the explosive gaseous mixture through the diaphragm. The diaphragm which may be an inch or so thick may be mounted in any desired way, as for instance, by being supported in a suitable casing 2 of iron or other suitable material which -may be formed with a suitable recess behind the diaphragm communicating with the injecting pipe 3 for the explosive gaseous mixture which for example may be formed by forcing the combustible gas through the inlet pipe 6 in the desired amounts controlled by the gas valve 7 while air is similarly supplied under the desired pressure through the air inlet pipe 1 to the extent determined by the adjustment of the air valve 5. In order to keep the edge of the diaphragm cool it is desirable to minimize the discharge of gas from this part of the outer or discharge surface 8 of the diaphragm in any suitable way, as for instance 'applying a suitable impervious coating 11 to the edge and adjacent inner face of the diaphragm. A suitable impervious coating for this purpose may be formed of a mixture of finely ground burned fireclay and sodium silicate which may be applied in moistened condition and then warmed sufficiently to cause setting of this cement-like material which forms a hard material somewhat like Portland cement or limestone. plaster of Paris or other impervious cementlike material may also be used for this impervious coating or the desired part of-the diaphragm, may be rendered impervious by a suitable glaze formed during its manufacture. The diaphragm is preferably mounted within a suitable seat 10 in the casing of such shape as to substantially conform to the edge of the diaphragm which is preferably located so as to be protected by the edge or flange 9 of the casing. Any suitable cement or luting material, as shown at 12, may be used to hold the diaphragm within the casing, as for instance, fire-clay or preferably a mixture of finely ground burned fire-clay and sodium silicate which may be caused to set by suitable warming, or other suitable cementitious material, such as plaster of Paris, asbestos's passe, or whitelead compositions may be use Such incandescent diaphragms may be arranged horizontally, vertically or at any.

cated in Fig. 2 the incandescent diaphra'gms' l5 and 16 are placed at any suitable distance apart so as to heat both sides of the article placed between them. The diaphragm 15 may be mounted within a suitable casing 17 connecting with the injecting pipe 18 and formed with a suitably connected support, if desired. The opposing diaphragm 16 may be mounted in a similar support 19 .having the injecting pipe .20.

In some cases instead of using plain diaphragms many other special forms or contours suited to special purposes may be used, such, for example, as the dome-shaped or convex diaphragm shown in Fig. 3. In this case the porous refractory diaphragm 21 is shown mounted in inverted position in the iron or other suitable casing 22 so as to have the outer hot surface of the diaphragm pointed downward so as to be suitable, for instance, for heating a room when mounted in its upper portionor for heating or evaporating liquids or other material placed beneath the diaphragm. As indicated, the diaphragm and its connected casing may in thisinstance be conveniently supported by the injecting pipe 23 for explosive gaseous mixture, and if desired a suitable hood 24 may be mountedin connection with the diaphragm so as to carry oil the products of combustion therefrom in connection with a suitable flue, such as 25. A form of tubular diaphragm 26 is shown in Fig. 4 as mounted within a suitable casing or support 27 of iron or other suitable material so that the explosive gaseous mixture supplied to the diaphragm through the injecting pipe 28 maintains the outer surface of the porous diaphragm in incandescent condition. The explosive gaseous mixture may be formed and fed to any such refractory diaphragms which are sufliciently porous by a suitable injector device in which either the combustible or combustion supporting constituent may be under pressure and be discharged with suflicient velocity to draw in and mix the other component of the explosive mixture and feed the same with sufficient pressure through the diaphragm.

In Fig. 4 the injector device may as indicated comprise the curved injector throat 29 with which the injector nozzle 31 cooperates so as to draw in additional gaseous material through the annular passage 32 the size of which may be regulated by adjusting theposition of the valve 34 threaded or otherwise adjustably mounted on the nozzle, for instance. The supporting casing 33 communicating with a suitably valved supply pipe may be used to connect the injector throat with the pipe 30 communicating with the nozzle sons to allow the entrance of air or other gaseous supporter of combustion around the nozzle when the combustible gas is discharged therefrom at a velocity pressure of a few pounds per square inch which is sufficient to produce a pressure behind the diaphragm of an eighth or a quarter of an inch of water or more.

The valve in thegas supply pipe may be used to regulate the amount of gas discharged from the injecting nozzle and the valve indicated in the air supply pipe may regulate the amount of air drawn in.

These refractory diaphragms .of a high and quite uniform degree of porosity may bemanufactured in a number of ways, as for instance, by suitably uniting refractory porous granules of substantially uniform size so as to give a high degree of porosity and permeability to the diaphragm'which is penetrated by tortuous gas passages formed by the network of spaces or interstices between the refractory particles or grains of which the diaphragm is made up. Porous fireclay is a satisfactory material for such diaphragms and may be readily crushed or ground in any desired way into particles or grains ofthe desired size. The granules for making any particular class of diaphragms 5 are substantially uniformly sized, that is,

for instance, the granules passing a sieve having 30 meshes to the linear inch are selected and freed from objectionable fine material by separating therefrom all particles which will pass a -mesh sieve. Another size of granules useful for such diaphragms for less explosive gaseous mixtures are those passing a lfi-mesh sieve and retained by a 32-mesh sieve. Still larger sized granules, such as are suitable for making diaphragms which may be generally used for burning coal gas and illuminating gas are those passing an S-m'esh sieve and retained by a 16- me'sh sieve. These porous granules may be united in any desired way preferably by means which will not destroy or undesirably impair the porosity of each of the granules. This may be accomplished by the use of suitable binding agents, as by incorporating with the. granules a small percentage of feldspar or a mixture of feldspar with a little fluospar to the extent of ten per cent. or so of the granules. Such binding material in dry finely powdered form may be incorporated with thegranules by first wetting them and then thoroughly stirring them with the dry binding material which thereby coats the particles which may then be ims.

mediately molded while in this moistened coated condition. The molded diaphragms are then burned at a high temperature in a suitable pottery kiln orother furnace so that,

the temperature is carried considerably beyond the fusing point of the binding material and this causes the binding material .sufiicientlyrigidly held in position. For ina stance, diaphragms may be burned at temperatures of 1300 to 1400 degrees C. and operated at temperatures of 800 or 900 degrees C. with good results. It is also desirable to carefully mold these diaphragms so as to prevent the destruction of the tortuous passages which naturallv form between the rough granules and for this reason moistened material is preferably only compacted very slightly as with an ordinary rolling pin in molding the diaphragms and it is for some purposes even better to merely remove the surplus material supplied to the diaphragm molds so as to prevent any possibility of crushing the particles or'undesirably packing them. It is also desirable to remove the surface of the baked diaphragms where the particles have become alinedasby being in contact with the smooth mold surface and this may be done in any desired way as with a rasp before they are used. For some purposes also it 1s not desirable to use as the discharge or outer active surface of the diaphragms the surface which has been in contact with the mold,butto use thissurface for the inner surface through which the gas enters. In this way. diaphragms may be formed of extremely high and uniform porosity, the degree of po- 'rosity, that is, the proportion of porous cavities and spaces between the particles 'or granules being as high as 50 per cent. or

. so in some cases. For some special purposes t is sometimes deslrable to form the (1111-.

phragms with outer discharge surfaces of coarser partlcles and with bodles or inner layers of finer particles which can of course be'conveniently effected when molding the moist material.

"The substantially uniform size of the granules and the tortuous nature of the gas passages between them are especially desirable in highly permeable diaphragms suit able for operation under low gas pressures.

The size of the granules and consequent size of gas passages and permeability of diaphragms of this character should be so chosen as to give the proper operation with the particular kind of gas with whichthey are tobe used, the size of granules being in all cases small enough so that together with the tortuous character of the gas passages and the greatly increased cooling effect due to the impinging action and rough surfaces of the granules forming these passages,

flashbackthrough the diaphragm passages is greatly minimized and practically eliminated under operating conditions with the particular explosive gaseous mixtures used. Diaphragms an inch and a quarter or so thick may be formed in this way of porous fireclay granules of between one-eighth and one-sixteenth inch mesh, which give good results with explosive coal gas and air mixtures supplied under pressures of about oneeighth of an inch of water, and such diaphragms may burn as much as 7 5 cubic feet or so of coal gas or 400 to 500 cubic feet of explosive coal gas and air mixture per hour for every square foot of diaphragm surface, thus maintaining the outer heated surface of the diaphragm'at a temperature of about 850? C. or so under freely radiating condi tionsl; A diaphragm similarly formed of granules of substantially sixteen-mesh size will burn a similar amount of explosive coal 50 mesh or even of still finer granules of between 50 and 100 mesh size in the case of more inflammable water gas mixtures.

The action of such porous refractory diaphragms in eflecting the accelerated surface combustion of explosive mixtures can be understood by reference to Fig. 5 which diagrammatically illustrates the diaphragm structure on a greatly magnified scale. The outer granules or particles 40 of porous refractory material are the ones maintained in a highly heated or incandescent condition by the combustion of the explosive gaseous mixtures injected against them so as to maintain'them in this highly heated condition in which they can radiate heat to each other and from the exposed outer surface of the diaphragm. As may be seen by reference to the portion of these granules within the plane of this section the granules not only have rough outer surfaces, but have internal pores such as 42 communicating in many instances with the outer surfaces to form cavities which the gases may readily penetrate. These particles and the similar inner particles 41 are firmly united, but". have between them relatively large cavities or interstices 43, so that the entire diaphragm is formed with a network cit-concatenation of these communicating spaces or channels. Fig. 6 illustrates diagrammatically the character of one of these tortuous gas passages or channels 44 through a diaphragm of this character, the section being taken along the irregular line following the greatest crosssection of this particular channel through the porous particles. These same factors promote the surface combustion action occurring in the hot outer layer of the 'diaphragm several granules thick. The explosive gases are here brought. into impingement with the rough incandescent surfaces of the granules so that penetration and contact with the gas is greatly promoted and the highly accelerated combustion takes place much more effectively than would be possible in the case of a dense porcelain plate, for example, drilled with separate small holes.

For the proper operation of these diaphragms it seems desirable or necessary to have sufiiciently free radiation or dissipation of-the heat from the incandescent outer diaphragm layer to prevent the accumulation of heat in this layer to such an extent that it can undesirably heat by conduction the rearward layers of the diaphragm and thus cause the zone of surface combustion of the explosive gases to slowly and progressively move back away from the outer surface. This back heating action occurs when, for example, two coal gas diaphragms are arranged with their incandescent surfaces close together, or when a refractory nonconducting plate or the like is moved against or close to a hot diaphragm, and may also take place when excessive amounts of the gaseous mixtures are being burned in the diaphragm so that the heat developed exceeds that which can be properly dissipated from the radiating diaphragm surface or otherwise. at the relatively moderate incandescent temperatures at which it seems preferable to operate these diaphragms.

When such back heating takes place the outer diaphragm surface actually frequently cools as after the combustion zone or incandescent layer has moved backward into the diaphragm, and instead of a substantially uniform incandescent surface darker spots appear and in many instances the outer surface cools below a bright heat when the combustion layer has retreated some distance. When this slow retrogression or penetration of the hot combustion zone through the diaphragm occurs the explosive gases in the diaphragm chamber may become ignited, and it is of course desirable to quickly correct this undesirable action as by shutting oifthe gas supply and cooling the diaphragm or by considerably increasing the proportion of air mixed with the combustible gas supplied so that normal conditions are restored. Then the relatively freer radiation of heat from the incandescent diaphragm surface should be insured so as to cause the heat to be radiated and dissipated as fast as it is generated by surface combustion, and prevent the progressive accumulation of heat and rise of temperature in the incandescent surface layer which undesirably heats the adjacent material and initiates such backheating. In normal operation of such refractory diaphragms the explosive gaseous mixture continues to burn with accelerated surface combustion in the incandescent surface-layer and this combustion may be definitely localized and maintained at the desired intensity by regulating the supply of explosive gases and the amount of heat radiation as by increasing or diminishing the freedom of radiation, so

tem. This back heatin as to insure equilibrium and counteract any unbalancing tendencies in the heating sysaction is distinct from the ordinary bac flashing or quick backfiring of explosive gaseous mixtures in tubes, such backfirin action being suppressed or eliminated in the'diaphragms of the present inventionby the greatly increased cooling effect on the gases of the small granules and the relatively large surface of the tortuous gas passages there- 'through, For instance, in the coal gas dia- ,phragms referred to having granules of between one-eighth and one-sixteenth inch mesh, the passages are of appreciable size and the porosity is so great that the total area of the passages throu h the diaphragm is in the neighborhood 0 30 to square inches for each square foot of diaphragm surface. But nevertheless, no backfiring occurs with. a properly made diaphragm of this character, and the importance of the tortuous roughened character of the gas passages in preventing backfiashing can be appreciated from the fact that only as much gas will pass through 'a square foot diaphragm of this character as will issue from an orifice or nozzle about one-quarter or one-half inch in diameter under e ual pres sures. In gradually shutting o the gas supply to diaphragms of this character the speed of the explosive mixture passing through the' tortuous channels of the diaphragm "is gradually reduced to zero, but

the cooling action of the diaphragm structure is such as to prevent backiiashing of the explosive gases n contact w1th the incandescent outer face ofzthe diaphragm even under these conditions.

It is of course understood that many other refractory substances such as magnesia,

bauxite, ganister, preferably those having a suificiently porous character may be used to form the granules which may be-united in many ways to formporous diaphragms of this character. Various firebrick' compositions have proved highly desirable, especially the more of this character.

Having described the invention in connection with a number of illustrative em:

bodiments, arrangements, proportions, ma terials, pressures, conditions, processes and orders of steps, to the details of which disporous refractory materials closure the invention is not of course to be limited, what is claimed as new and What is desired to be secured by Letters Patent is set forth in'the appended claims:

1; Apparatus for burning gaseous fuel .comprislng a porous and permeable refractory diaphragm composed of granules'ofre fractory material bonded together to form a network of tortuous-irregular gas passages,

and means for maintaining a supply of an explosive gaseous mixture against one face of the diaphragm whereby the mixture will be caused to flow through the tortuous pas-' the diap ragm whereby the mixture will be caused to flow through the tortuous passages of the dia hra to cause accelerated substantially ame ess combustion to take place within the outer layer of the diaphra when the latter becomeshighly heated, and

means for preventing the entrance of the explosive gaseousmixture' into the outer edge portions of'the diaphragm to prevent said portions from becoming highly heated.

3. In an apparatus for burning gaseous fuel, a fporous refractorydiaphragm composed o fire clay granules united by a relatively fusible material'to form a network of tortuousv irregular gas passages, a casing within which the diaphragm is mounted, an

impervious cement connecting the edge of said diaphragm with said casing, and means to feed an explosive gaseous mixture through said casing to said diaphragm, the burning of the ex losive mixture causin the outer face of t e diaphragm to be eated and thereby producing a flameless combustion within the outer layer of the diaphragm.

.' 4. In an apparatus for burning gaseous porous refractory diaphragm comfuel, a

posedo granules of refractor material united by relatively fusible material to form a network of tortuous irregular gas passages, a casing within which the diaphragm is mounted, an impervious cement connecting the edge of said diaphragm with said casing, and means to feed an explosive gaseous mixture through said casing to said diaphragm, the burning ofthe explosive mixture causing the outer face of the diaphragm to be heated and thereby producing a substantially flameless combustion within the outer layer of the diaphragm.

5. Apparatus for burning gaseous fuel, comprising a porous and permeable refractory diaphragm composed of granules of refractory material of substantially uniform size bonded together to form a network of tortuous irregular gas passages, and means for maintaining a supply of an explosive gaseous mixture against one face of the diaphragm whereby the mixture will be caused to flow through the tortuous passages of the diaphragm to cause accelerated substantially flameless combustion to take place 'within the outer layer of the diaphragm when the latter becomes highly heated, the said tortuous passages of the diaphragm being of a size to prevent back-flashing of the explosive gaseous mixture theretllrough, and th( diaphragm having a rough outer surface.

WVILLIAM ARTHUR BONE. JAMES WILLIAM WVILSON. CYRIL DOUGLAS MCCOURT.

Witnesses:

P. G. ALExANDuE, CHARLES E. TAYLOR.

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