US2606108A - Multiple gas feed system for internal-combustion engines or the like - Google Patents

Description

Allg. 5, R K- ENS|GN- 'MULTIPLE GAS FEED SYSTEM FOR INTERNAL.-COMBUSTION ENGINES OR THE LIKE Filed Dec. 6, 1949 QOY 1K. s/GM IN VEN TOR.

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Patented Aug. 5, V1952 MULTIPLE GAS FED SYSTEM FOR INTER- NALf-COMBUS'IION ENGINES OR THE LIKE Roy K. Ensign, San Marino, Calif., assignor to Ensign arburetor'Compan'y, Huntington Pai-k,

' Calif.; acci-poration of California I Applieetien neeember 6, 1949, serial No. 131,397

` s Claims. (ol. 1s-191) This invention Vhasto do with feeding gaseous fuelfrom multiple sources to such a gas using funit as aninternal combustionv engine. The invention, although not limited to that, can best be 'initially describedgin, connection'with ause to which it is being currentlyput: e

Sewer and sludge gases, generated'in sewage disposal andftreatingsystems, have combustible .components which create Y re, and explosion hazards. As' thegases havea utilizable heat content (averaging about-600B. t. 11perV cubic foot) it is desirable to burn'them for some useful purpose and in many instances itis usefulto 'usethem for power generation. The amount of gas Aavailablel from any given source per unittime commonly varies greatly, and a power plant capable of utilizing a peakor near-peak supply of gases must 'be fed with a supplemental fuel .when the supplyr drops, in order to maintain` a VAs uiiiciently uniform power production to be ec'onomically'useful.

The general purpose ofthe invention-is to pro- `vide a 'fuel feed system which willautomatically supply aV supplemental fuel when, and to the'extentl that, it is necessary.` The nature of the-invention will be understood from the following Adescription in connection with the accompanying drawing in which the single gure isa schematic representation of one illustrative form and application of the invention embodied in a dual gas feed system as applied to feeding the carbureter of an internal combustion engine.

In the drawings the element `Ill may represent an internal combustion engine having its intake Il connected to a carbureter I2. Operation of -the vengine draws air through the vcarbureter venturi I3. creating a sub-'atmospheric pressure f (depression) at gas port I4 at the Venturi throat. 'Anl adjustable valve I5 controls communication between" port I4 and the gas intake 'I6 of the carbureter.' Such an engine and carbureter system,'jat any given adjustment of valve I 5 and any 4given level of engine operation, draws gas in at a pressure which is considerably below atmospheric. That is, the depression at gas portlll isconsiderable.

In the drawingy a feed pipe 20 feeds gas intake 'I6.;from pressure .regulator R which is fed via pipe 2|, from any suitable source of the low-heat "gas orv vaporysuchfa's is illustrated here by the Ytank 22. (The unitV in pipe 2I will be described later.) Anyvordinary regulator will suffice, such 'as'the simple regulator shown schematicallyfwith 4its pressure responsive diaphragm 25, highpressure intake 26, low` pressure outlet 21, and its j inlet controlling vvalve 2 8 operatedby its diaphragm Vand loaded by spring 29. In this particular instance where thejdelivery pressure of the regulator is setto bebelow atmosphere; the loading spring tends to close the valve, 'and inward movement-ofthe diaphragm", exposed on its outer face to atmospheriopressure, opensthe valve when the pressure in diaphragm'chamber 30 falls'to the set-pressure; The system asso far described will operate normally as long as the pressureof thegas supply, at 2 6 does-not fall below the pressure which the regulator'is set to maintain at its outlet 2 'IfandatA the carbureter gas intake' aIE. lFor purposes of illustrative de- 'scription-will be assumed that the' regulator is edjestedrje; g. bysemng theedjustment'si--of spring 2S A(to normallyvmaintain, at' outlet`21 a pressure equal `toone-Hqu'arter inch of water below atmospheric pressure. The' Venturi throat'V depression, in normalenginevoperation is considerably greater than one-quarter inchyfand valve I5 is set so thatthe pressure differential across'the Aset valve opening lisy sufficient to draw in from I6 the volume of fuel required to properly jcarburet or make a combustible mixture with "the air "'passinghthrough" lthe venturi.' Utilizing gas'of such a relatively low heat content, the

required full volume is, relatively large and valve 1 fuel, say, as butano.

lf the gas supply at 26 becomes exhausted Vto the point that its pressure falls below the set delivery' pressure of the regulator. the suction at IE immediately tends to lower the pressure in 20 and 'in regulator chamber to a pressure which is increasingly lower thanthe set pressure. Using an ordinary regulator, in which valve 28 I5 is setI widerwopen'vthan it would be for such a remains open for any 'pressure below the set pressure, the continued operation willalso lower the gas pressure in 2|v and 2'2` (assumingthat 2I connects openly with tank 22).' However, itis immaterial whethervalve A2li remains open or not; in any case the continued draft onthe gas at I6 lowers the pressure at that point and in feed pipe 20. It may here be remarked that, pipe 20 being large enough that thereis no appreciable pressuredrop of gases flowing through it, the Vpressure in that pipe is always the same as at gas intake I6. For that reasonpipe 2li may be regarded asa' part or extension of the gas intake |16 which connects with gas draft port I4 via the restriction at I 5.

Connecting also with gas intake I6 (here shown as connecting via intake pipe 20) is a second intake or feed pipe which connects, via another its gas at a pressure which is preferably slightly,

but definitely, below the delivery pressure of R.

In the particular illustrationfa'tzhand, with Reet` at one-quarter inch depression, RI isset to-de liver at say, one-half inch depression. .Y

I have said that the setdelivery pressure l-o'f= RI is definitely below that of R. I mean by that, that the difference between these set pressures is valve I5, determine the normal rate of primary fuel flow. Regulator RI remains closed, and there is therefore no flow of supplementary fuel and no pressure drop at valve 42.

If now the supply pressure at 26 drops slightly below the set delivery pressure of regulator R, ther actual delivery pressuregasintake I6 is 1 lowered correspondingly..L reduces slightly the pressure drop available across the orifice at I'5, and hence reduces the rate of fuel flow from '20 to carburetor I2. That reduction of flow 1 c'ntinues'with continuing decline of supply pres- Y sure22 until the pressure at I6 and in 20 becomes. justequalto the set delivery pressure of ,supplementary fuel regulator RI. At that pressureffregulatorfftlopens and maintains the delarge enough that with the set deliverypressure of R present in intake I6, and in the delivery pressure chamber o fj RI-that is, with regulator. R Yoperating 4normally-valve 28.- of RII will bepositively closedlso Ythat RI --doesnot normally feed` gas to 4the intake'. 1A .one-quarter yinch difference has been .found to be practically ample ,fo'r'thatfpurpo`se. '.Howmuch'f'larger theffdiffer- .ence maylbe depends in .practice Vonfjh'ow 'much drop. Afrom .normal o,pferatiii'gipressureV at intake IBcan be tolerated; ,In feeding an internal combustion. er'rgire,l any considerable pressure'vdrop .seiitiaryalist:sumeliga-ming .er .iiiezvelve .-Qf. reulaiioiffl lai/liti R' is @bemhe normallycommonly :used Yfuel gas- Willsa'tisfy lthatrequire- "ment; natural gas."produc'e`r'gas, butane, etc. are examples. Butane,- which `ghas .alieatcontent Vof about three thousand Bft; 5ux'. .per` cubic. foot, may be taken as illustrative. Becauseef .itshigh'er fuel content Aitneeds to be .fe'dftitakei I6- in smallerA 'v 'olume than then gas' of" low heathen- -t'entlj Consequently .the '..restrictio'n' L, atf. control valves y42 is` adjusted to vsuchY size rithat, ating in serieswith vthe"restriction atvalve. I5,,the correctamount Vof kthe high' heatllgasfisfed. `When twogases having a large disparityff .heat 4content.are beinglusei such asl vthose I. here named, theforifice-atlzis adjusted to `a lsi'ze'c'n'- siderablyfs'inall'er thantlatl at I5. In"I the followfingf description of 'op'eratic'nri, it vis assumed that 'fall pipe connections, such as 20, T40, 44, are'jlarge enough .thatlprssuredrops due toy fiowthr'ugh ,mehrere negug'ibie, i y; tr

. Inconside'ring theoperationof thefuel feeding systmgfit 1is convenient initially'to consider. the Venturi sfuction pressure atv I 4to be substantially 'const'ntf'and to assume that pipe 2| which feeds .regulatorRconnects directlywith tank; 2 2. Under I ijo'rnalA operation, whenthe supply pressure at25 i'rsmpigjthe pressure in iinehzu' and: intakene is'substantlally the set delivery. Pressure of` regyulator R,so that the pressure drop. across the 4orifice at valve I5 is determinate. Thatdenite pressure drop, together with.` theisetoriiicelof livery pressure Vinline 44 at the set lower value. At rst, that action results in the delivery of rela- `tively little of the supplementary fuel to I 6, since the pressure drop available across the orice at valve 42 is v'relatively ,sxr'.1'all. y 4Nevertheless there is `some ilow of supplementary fuel, which tendsimmediately to counteractthe eif'ect ofthe decreasing' `flow' ofl primary fuel.. In" .other1words;;.the transfer of.- operati'O.1i'` from.4 prirriary4 .tof 'supplmentary fuel begins when "the lprimary "supply pressure. at 26 allowsjthe,pressureat",I6`tojdrop togth'ev s'et delivery pressure vof supplementary regulator RI. That pressure will be referred to as the ,initial transfer' pressure. since it ,isjthe pressure'v atiwhich ,transfer froni' primary .t'osupplenflefrit'ary fuefisfinltiated.,

erablyl Onlyslightly (say 1/4' lnch'of water) ,less thanthe normal operatingV pressure `at 20, as already explained? Ongthe other. hanathemrmal Venturi pressure l at j I4 'is very considerably (say. severalinches of water) below that DIT-555km: at I6.' 1Hence assuming i reulatorjjRito' heini 'smcient capacitwla; reiduttioninlprimarvfmel pressure can result 1n onlya relatlvelylmllgduction, in tprinnarv .fuel owfitayilabntjw) before thei initial transfer; ,pressui'slireathea with resulting 'enrichment'vofr the fu'el by admixtu'reof. the relatively riebsupplementarymet 1 vIf the supply Vpressure.atgZI continuestbgde- G1inaj-tenlinato carry the. 'pressure' .at llgflwn withitgthe ypressure drqnacrpsslia.@Klimaat v'42'"gradually increases. That increase oflpres'- "sure, 'differential across l42 leads to' increased 'now of simplex,nentarylV fuel.. from ...4.4. .teintake Il Thus the supplementary ."fu'el gradually "replaces thev primary fuel .at theas lintake'. lai-n'cl hereby maintains effective ,fuel "supply .to the4 enginepr other'. vfiwlccon.sinner 1.0....1 i As" the ow of supplementary fuelincreas'es. 4it tends' more` .and ,more to maintain. .thegnrsssureat `I61anditherebyfto reduce th'e flow 'of primary fuel from tank 22 to I 6. That eifect becomes more. pronounced as supply pressure .from 2lv continuesj'to decline.' until a definite' poin'fls reachedat which the pressure at I6 has sunkto a'. value that' ifs fullyL `r'ralntanedby thefflowof supplementary Vfuel alone. Primaryv fuel' then ceases to flow through regulator R, even though regulator valve 28 remains open.,.'lhelsys tem hasA then been transferred completelyl iid? pera.- .tion byjthe supplementarvfuel... vThe prehsure at I6 -at which that takes place is'` heref called. for,convenlntreference, the rial transfeiii'es- Sii'r-e.` Anygclecrease olf, primary, fuel-Supply pres sure at" 'I6 .below. the final transfer pressure .(whichnrnightvbecaused, 4for instance, by other drafts. on the gaS in 22, if pipeZI. connects ilrectlyhwith 22 hvasno "effect upon.` the 'operation .of the fuelsystem, sincepressure at I6 smain- "tained bysf-the now of-supplementarygfuet wAssuming regulator' RI and the'l .pipe connections to b e'of.-suicientcapacity,' the only. effect of lsuch a pressure'drcp in .'22-:w'ould'fbe a reverseiflowof -high heat gasfromiZ: :to 22. The same'condiv`tion might beset up;;for instance if the yoperatingnlevel of unit 'I 0.; is Alowered-while regulator RI isfeeding the-systems" But any suchv'back flow may be prevented-by thesimple expedient of installing. a check valve any place in thefprimary feed line: between tank; 212:.'and thefpint. where vAny increase ifi-:primary fuel supply' pressure at I6 tends to carrythe system 'backlover the Vcourse-'that has just been described. In ypracy.tice Athe systeml rapidly stabilizes in response to the existing primary supply 'pressurethe ratio of primary to supplementary fuel fedv to Venturi :inlet /I 4 `automatically accommodating itself? to rvaryingsup'ply conditions.. -v .irffz vThe description so far',.f'or purposes .of 'simplici- .-ty', hasassumed that feed pipe 2I forregulator R connects directly lto supply .22.' Under 'those conditions-the pressure. in the supply-'22 may atl times fall4 below atmospheric; .and thatis to' be .prevented in' order. to avoidv 'the-hazard rofY air leaking vinto the tank. For that purpose a valve such as that shown 4at V isinstalled in pipe ZI.

As shown the valve has a'fdiaphragm chamber 50 with a diaphragm 5I exposed to .atmosphere and also preferably loaded.- as with a spring 52 so that valve 53 lwill closeon. pipe Zlat a pressure somewhat above atmosphere. 'Pipe 2 I a leads from/ tank 22 to chamber' 50; so that valy'e53 .i IVwill be operi as longaspressu're' in 22 is somewhat above atmospheric and close whenever the tank pressure drops below that.V The action of .the system with this valve included, in it is the same as before described, except' that the complete change-over from primary to secondary supply the'heatzcontents were two to-one,.orice1f42 lwould vbe equal .to` orifice I5; 'and for la1 lower ratio, the orifice at 42' would be the larger.` 'With orice 42 .relatively '-larger, 'the pressurev drop across it is relatively' smaller and the final transfer pressure at which vregulatcirfl. solelyfeeds the gas intake Izwill be: relativelyirhigher.'f

The process of transferring operation' from primary to supplementary fuel takes place'v .very gradually as the primary supply.pressurefallsibelow normal, that is, below theset Vdeliverypressure of regulator Only a relativelylslightreduction (typically about 1/4 inch of water) ztakes place before the initial transfer :,jpressuref'is .15.

reached, and feeding of supplementaryffuelfbegins. But a relatively large fur-therreduction in I .primary supply pressure v(gtypicallyl or 5 Vinches ofwater.. with valves I5.V and 42,set1 for gases having the ratio of heat `conten-there-:being illustratively considered)` Ymay be required before ,the final transfer Ypres sure. -,is i reached. Throughout that latter reduction, .the supplementary fuel progressively provides a larger and larger proportion of thefuel. fed,to.Venturi.inlet.I4. 1 Because of. the-gradualness of that transfer ,.the system-,tends to stabilizeitself effectivelyfat virtually .any existing rate ofsinoplygofl primary fuel to container 2,2.` fIf .that raterof supply @changes-inv either directiongth'e ratio of ,primary .tosecondary fuel fed by the system changesaccordingly in such a way. as to use all, oras much .as possible', of the availableprimary fuel.' f

`Althoughthe above description of .typical operz'aftionf of my systemhas been based for clarity upon thesupposition of a constant Venturi' pressureatv I4, itfwillbeunders'tood thatvariations in. thatl pressure Vwithin gthe operating .rangefof may be more abrupt, depending 0n the Capacity fjof the piping system including that of pipe 2I between regulator R and valve V. Under vno conditions, however, can the tank pressure at 22 be reduced below that for which valve V is set.

And, that valve V being set to close at a pressure.

higher than that which either regulator maintains (or which regulator RI particularly maintains) at intake I6, there cannot be at any time any back flow of gas from supply 48 into supply 22.

The final transfer pressure (under given conditions of engine operation) is definitely determined by the various parameters of the system. It lies between the Venturi pressure at I4 (conthe'- operation.

the feed system dojnot affect the.principles `.of

As has been implied, the restriction at valve I5 may be physically a part of the engine or other gas consuming unit, or physically a part of the feed system which is applied to the unit. In any case, the feed system functionally includes the restriction at I5, restricting the gas intake I6; but from a practical or commercial standpoint the system may be regarded as one which is adapted to feed gases to such a restricted intake I6.

sidered constant) and the set delivery pressure K of regulator Rl; and its value is determined by the orifices at valves 42 and I5 acting as a pressure dividing network. The rate of flowof supplementary gas under that condition is such that the sum of the two resulting pressure drops at the two valves 42 and I5 equals the total pressure differential from 44 to I4. The ratio of the pressure drops at the two valves equals the inverse ratio of their effective cross-sectional oriflce areas. As already stated, the orifice of valve 42 is ordinarily considerably smaller than that of I5, so that the pressure drop `at I5 is much smaller than. that at 42. The final transfer pressure may then be only slightly higher than the Venturi pressure at I4.

However, if the two gases are more nearly equal in their heat content the orifices at 42 will be more nearly equal to that at I5. If the ratio of Both the restrictions at I5 and 42 are conveniently in the form of adjustable valves, but can be orifices or passages of chosen sizes.

I have spoken of the regulators being set to deliver at defined pressure. Although that setting may conveniently be done by adjustments such as described, it may also be and commonly is done by proper selection of the appropriate design factors of the regulators and/or by selection of springs of proper strengths.

I have mentioned other gas-drawing units which may be fed by my system. A gas and air `mixer for any purpose, say for a burner, may be taken as typical. It may be assumed for instance that element I0 of the drawing represents a gas burner, and that air under pressure is supplied to the air intake 9 of carbureter (mixer) I2. Depending on air velocities through the venturi I3, the relative depression (the negative velocity head) at I4 may be such that the pressure at I4 is above atmospheric. (The same of course may be the case when an engine is being fed with air under pressure.) In any such case the set delivery pressure of both R and RI may be above atmospheric, but the system, with the same relative settings as before described, will operate inthe samek mannen 1 Andi: the burner unit is illustrative 'of any gas drawing unit which -does not depend for its gas drawing operation von, continued uniformngas feed. In any. such case the pressure .difference between the two regulators may be relatively large. Y The system as described' may be modiiied for .the successive supplies of two or more supplefirst pressure regulator adaptedvto be set to' in- .surel a predetermined delivery'pressure and toi have-the inlet thereof connectedto a pressurizedsource' ofgas of relatively'low heat vcontent; a irst' conduitf connectedrto the outlet' of said lfirst regulator'for `delivering gasto the gas using unit; a ilow restriction in saidrst'conduit for throttling -the flow oflcwheat content gas to rates required by thev usingu'nit; a'second pressureregulatoradapted to be set to` insure a delivery pressure less than that of said rst regulator andfto have the inlet thereof connected to asecond pressurized source of gas of relatively high'heat content; a second conduit having one en d thereof connected to the outlet of said secondvregulator and the other end thereof tosaid first conduit upstream of said y flow restriction therein; andy afiow restriction in said ysecond con- .duitwhich acts in series with saidfrst conduit iiow restriction for throttling ther flow of high lUnit-v.v

,heat content gas to rates required by the using gas feed system for feeding combustible gases 'of different heat contents to a Vgas using unit, the combination comprising: a

- I' 2; -.Th' structure i de ned v. inficlaim.' l. in which the .using-unitifdraws' gas at sub-atmospheric "pressurefand includingagas inlet: conduit con- :fnected to the inlet oftheiflrst regulator. and pressure-responsive va'lvefmeans controlling said inl'et conduit, said valveme'ansfbeing closed 'atf'con- Alduit" pressures belowl substantially atmospheric pressure. `and openwatl pressures' rthereabove. i '1 ,3.:In fa multiple ygas feedzsystem' for'feeding combustible gasesof different heat contents to a carburetor suctionr port of an'int'ernal combustion'- engine,- the .combination comprising: two pressure regulators one adapted to besetto invvs.ure,a"higher;. delivery pressure.. than the other yandtoehaveitsinlet connected to aipressurized sourcevof low.: vheat content: gas,l Vand the .other plower. delivery pressureregulatoradapted to have its inletconnected to a pressurized source o1' high l-heaiffcontent gas; 'feed'conduits connecting the outlets? of saidV regulators tothe ,l suction port; means restricting the: suctionport forlr throttling the flow of lowheat content gas therethrough to ratesrequired by the engine; and al restriction in the feed conduit from said other lower pressure ,Y .regulator which acts in `series with said suction port restriction to throttle the flow of the vhigh heat content gas to rates required by the engine.

Y 1 ROY K., ENSIGN.

REFERENCES CITED The followingreierences are of record in the illeof this patent: n UNITED s'rA'rEs PAJI'EN'IS Number Dfe A Name 1,854,893 Farrar et al. -c-- Apr. 19, 193 r f FQREIGN PATENTS Number Country Date ...148,201 Great Britain July 9.1920

Claims (1)

1. IN A MULTIPLE GAS FEED SYSTEM FOR FEEDING COMBUSTIBLE GASES OF DIFFERENT HEAT CONTENTS TO A GAS USING UNIT, THE COMBINATION COMPRISING: A FIRST PRESSURE REGULATOR ADAPTED TO BE SET TO INSURE A PREDETERMINED DELIVERY PRESSURE AND TO HAVE THE INLET THEREOF CONNECTED TO A PRESSURIZED SOURCE OF GAS OF RELATIVELY LOW HEAT CONTENT; A FIRST CONDUIT CONNECTED TO THE OUTLET OF SAID FIRST REGULATOR FOR DELIVERY GAS TO THE GAS USING UNIT; A FLOW RESTRICTION IN SAID FIRST CONDUIT FOR THROTTLING THE FLOW OF LOW HEAT CONTENT GAS TO RATES REQUIRED BY THE USING UNIT; A SECOND PRESSURE REGULATOR ADAPTED TO BE SET TO INSURE A DELIVERY PRESSURE LESS THAN THAT OF SAID FIRST REGULATOR AND TO HAVE THE INLET THEREOF CONNECTED TO A SECOND PRESSURIZED SOURCE OF GAS OF RELATIVELY HIGH HEAT CONTENT; A SECOND CONDUIT HAVING ONE END THEREOF CONNECTED TO THE OUTLET OF SAID SECOND REGULATOR AND THE OTHER END THEREOF TO SAID

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