US1101790A - Process of burning liquid fuels. - Google Patents

Description

PATENT OFFIGE.

HENRY L. DOHERTY, OF NEW YORK, N. Y.

PROCESS OF BURNING LIQUID FUELS.

To all whom it may concern:

Be it known that I, HENRYL. DoHEn'rr,

a citizen of the United States, and a res1- well known gas producer reaction,

dent of New York city, in the count of New York and State of New York, ave invented certain new and useful Improvements in Processes of Burning Liquid Fuels, of which the following is a specification.

This invention relates to processes of burning liquid fuels and, in particular, to the burning of such fuels in connection with lime kilns, brick kilns, furnaces, etc., in which the air .for combustion maybe preheated either by thehcat of the waste combustion gases or by contacting it with the burned charge to cool the same.

The object of my invention is to provide an improved method of burning liquid fuels in such furnaces with a comparatively smokeless flame with the use of preheated air-in such a manner that the flame temperature may be thoroughly controlled, whereby I am able to restore to the furnace at large part of the heat that would otherwise be'wasted by transferring such-heat to the air supply of the furnace without the;

production of an injuriously high temperature in the combustion.

To this end my invention consists, briefly I stated, in, first, atomizing the liquid fuel by means of a jet of combustion. or other gases containing carbon dioxid under .pressure; second, conducting the mixture of atomized fuel and C0 COI1ta1Il1ng gases 1nto a primary combustlon chamber and there subjecting'the atomized liquid to a partial combustion with a limited supplyof air,.

whereby the said atomized liquid is subjected to a temperature suiiiciently high to split upthat portion ofthe original heavy hydrocarbons of the liquid which was not consumed in the said partial combustion, in the presence of the CO of the gas usedin the atomization. of the liquid, whereby the carbon liberated in the breaking down of the hydrocarbons is caused toi react with the ()0, present to form CO according to the and the atomized liquid is wholly converted into gaseous products practically free from suspended carbon or soot; and, third, in burning the combustible constituents of the; gas mixture from the primary.combustion,' with a second portion of air (which may or Specification of Letters Patent.

Patented June so, rare.

Application filed April13, 1911, Serial No. 620,862.

shown, in rather diagrammatic form, an apparatus capable of carrying out my invention in the burning of limestone.

The drawing represents a vertical diametral section through two of the furnaces of ,the limekiln.

1 is the kiln shaft, of which the lower polrtion', 2, I designate the cooler of the x1 n. l

'3, 3, etc., are the primary combustion chambers, ithe atomizing nozzles, which may be of any approved construction.

5 are the injector passages through which the jets from the nozzles 4 discharge, thereb inducing an inflow of air through the 'dampered air inlet passages 6.

7, 7, etc., are the passages through which the gases encrated in chambers 3 discharge into the k1ln-shaft 1. I v

8, 8, etc., are the passages through which the air for supporting thesecondary combustion is introduced into the gases from the primary combustion, in one method of operating my apparatus. A v

1 9 is the discharge hopper of the kiln,

16 is the discharge pipe of blower 15 which communicates with the flue 17.

18 is an oil pump which draws the oil air distributing from a suitable storage tank and forces it through the pipe 19 to the oil distributingpipe 20. An elevated tank may of course 6 substituted for pump 18.

21 are the oil pipes to the nozzles 4, havingwalves, 22. y

23 is a down-comeri-for drawing oif a portion of the kiln gases from the upper having a gate, 10, for the dischargeof the connected by the blower is enabled to draw off from part of shaft 1 and which communicates ,with the suction connection 24 of positive 'blower 25.

' of blower 25 havin the valve 34.

is a valve on downcomer 23-.

36 isa valve on pipe 16.

37-, 37 are flues connectedwith distribut ing flue 17 whichpermit of the diversion of a portion of the heated airpassing through distributing flue 17 to the passage 5 of each furnace of the kiln.

38, 38 are dampers on flues 37 connecting with distributing flue 17. By manipulating the dampers on air'inlets 6 and dampe s 38 it is readily seen that either or both cold or heated air may be used for support- 1 ing the primary combustion.

39 isa dampered air port on suction pipe 14 of blower 15, so that the blower 15 may draw the air directly from the atmosphere, if this is for any reason desired.

The preferred method of operating my invention'is as follows In beginning operations, the blower 25 is started and at first air alone forced through discharge pipe 26, bustle-pipe 27 and plpes 28 to the 1102- zles 4. Oil is now turned on by opening valves 22 and ignited in the passages 5. At first, dampers on air inlet 6 or dampers 38 are so adjusted that the air admitted through them, in addition to that entering through atomizing nozzle 4, will be sufficient for perfect combustion of ,the oil. The products of 'the combustion pass from the chambers 3 through gas'passages 7 into the kiln-shaft 1 and thence ascend through the latter. By partially closing valve 33 and opening valve 35 the blower 25 may fthe kiln shaft (which latter should have now be made to draw in more or less combustion gases from shaft 1' and force the same to the nozzles 4. When the chambers 3 have been heated up to a suitable temperaturesay 18 00 to 2000 F.--the apparatus is in condition to start operating on my process proper. At this time, the charge in been filled with limestone before starting the operation), opposite the ports 7, should .have been heated 'to a temperature sufliciently high to insure the ignition of any combustible gases entering the shaft from ports 7. When this condition has been estz lflished the blower .15 is started (the dampen-11 being properly adjusted to ad- "mit the quantity of air required for the secondary combustion) and air forced through discharge-pipe 16, air distributing flue 17 and passages 8 into the gaseous cur- .rent passing through gas passages or ports 7. At the same time, the valve 34 is closed, whereby the pressure fluid supplied to the nozzles 4 is made to consist wholly of kiln gases, and dampers on air passages 6 and dampers 38 adjusted so that only the proper proportion of air to effect the complete gaslfication of the liquid fuel is admitted to chambers 3. The gaseous currents leaving the chambers 3 now contain a large proportion of combustible gases. These are burned in theshaft 1 by the secondary air entering through the assages S.

In the primary com ustion, it is my aim to use only sufiicient air to effect the proper and thorough gasification of the fuel. In this operation the combustion proper is chiefly to CO, only a relatively small proportion of the hydrogen of the hydrocarbons burning owingto the presence of free carbon liberated in the breaking down of the hydrocarbons. That portion of the fuel which does not react directly with the oxygen of the limited quantity of air used in the primary combustion, is subjected to reaction withfth'e CO present in the charm her 3,' and to direct dissociation by the heat of the-flame, into permanently gaseous compounds and free hydrogen. Since the heavy petroleum oils and the heavy residual oils of petroleum and coal tar, have an exceedingly complex composition and the reactions vary also with the temperatureof the flame in the prima'ry combustion chambers, as well as with the proportion of CO in the draft current, I do not limit myself to the use of any specific proportion of CO to fuel. I use, in any case, that proportion of CO -bearing gas which, in. connection with the primary air, will convert the hydrocarbon liquids into gaseous compounds and free hydrogen that will burn in the furnace chamber, with a slight excess of sec- .ondary air, with the production of little or no soot.

A reaction, typical of those which I aim to bring about between the hydrocarbon constituents of the primary flame and the CO, would be in the case of dodccanc,

any given hydrocarbon compound present in the original fuel to react Wholly with the CO in a manner similar to that given in equatlon (b) above. As 18 well known, the

oxygen of the primary air would be divided between the various hydrocarbons of the fuel in accordance with the principles of I mass action wh creby a reagent capable of reacting with all of-the'componcnts of a v mixture of substances, when introducedinto the mixture in quantity insufficient to satisfy all of the components, will be distributed among them in proportion to their relative hydrocarbons of the greatestpossible quantity of CO without having an undue quantity of the latter in the gas. The proportion of air used in the primary combustion is therefore adjusted to that which will best favor the accomplishment of the abovestated object, 11. e. to develop the quantity of heat "and the temperature in the primary combustion chamber which will best favor the maximum degree of reaction between,

and kiln gas to the primary combustion may be determined with fair accuracy by the operator from the appearance of the primary flame. This should be of a golden yellow color and should show but little, if any, smoke. v I

It is manifest that, with the comparatively great variation in composition which exists in the oils (including coal tars) which are in common use as fuel oils, and the widely different percentages of CO which are contained in kiln and combustion gases from different sources, it is impossible' 'to prescribe any specific relativeproportions for oil, kiln gas and primary air. In the case ofthe application of my invention to a lime kiln the proportions 'of the several substances in the primary draft current, might, advantageously, be fixed per gallon of oil as follows, viz., kiln gas 100 cu. ft. (at normal temperatures and pressure) and primary air 400 cu. ft. With these proport1ons the temperature in the'primary cham bers should be maintained uniformly at about 1800 F. Since the quantity of air theoretically required for the complete combustion of the oil considered above (which is a petroleum residue) would'amount to about 14.1 lb. per lb. of oil, or about 1350 cu. ft. (normal) per gallon of oil, the air used in the primary current, in the example given above, would be somewhat less than 30% of the theoretical air. While not limitingmyself to this proportion, I may say that, with most fuel oils and for ordinary combustion uses, I find it advantageous to use in the primary current an amount of air equivalent to about one-third, or less, of the air theoretically requisite for the complete combustion of the oil.

Since the dissociation of CO by carbon does not take place actively below 1300 F.

and practically ceases below 1200", while most of the hydrocarbons occurring'in the ordinary .heavy oils are cracked readily at-tfhe latter temperature, it is readily seen that I may, when I haveno objection to carry on the primary combustion at 1300"" 14EOO, inject into the primary current a much greater proportion of the kiln gases. When this is done the combustible gas produced in the primary combustion is diluted by the excess of the kiln gas so that its calorific value is reduced. The relatively large volume of inert gases present in the combustiblegas in this case proportionately reduces the intensity of the secondary combustion as well as the flame temperature. stead of the oil-producer-gas burning with a comparatively short flame of high temperature, as is the case when only the proportion of CO is introduced into the primary chamber that can be dissociated therein, when an excess of kiln gases s used, the gas-burns with a long voluminous, slow burning flame of comparatively low tem .perature.

Therefore by varying the excess of kiln gas (or other (JO -bearing gas) introduced into primary chamber I may, without varying the secondary air supply, vary the temperature in the kiln (or other furnace) at pleasure. This is, of itself, important in that it permits of the burning of liquid fuels in kilns or furnaces which require a flame of moderate temperature but of high heat-carrying capacity. Besides this advantage, the use of an excess of kiln gas in the primary combustion permits of the preheating of the secondary air. It thus enables me to effect a; great economy in'fuel in that I am enabled to returir to the kiln (or other furnace) a large part of the otherwise wasted heat contained in the efiiuent products of the kiln, using the air as'the vehicle for transferring the heat. In the apparatus figured the air is heated only by contact with the burned lime. It is obvious that by passing through suitable recuperators, which are common in the art and need no specific description to enable one skilled in the art to install them, that portion of the kiln gases not returned to the combustion a portion of the air may be heated by the otherwise wasted heat carried out of the kiln by the efiluent gases. The quantity of heat in these gases, however, is usually low, and such modification I do not herein claim specifically, as a part of my invention. In the at present known methods of burning liquid fuels, it is seldom possible to use preheated air for sustaining the combustion owing to the intensity of the combustion thereby engendered.- Oil burned by preheated air in the apparatus known tome -as being in industrial use at present would quickly burn out the most refractory firethe temperature of the air, the greater is the quantity of heat available for sustaining the dissociation of the CO introduced in the kiln gas into the primary chamber, and therefore the greater the quantity of combustible gas reaching the kiln for any given volume of air used in the primary combustion. It is evident that all of the carbon monoxid formed from the CO of the kiln gas by the aid of the heat so re-, cuperated and="*ret1.1rned to the kiln in the primary air is so much fuel saved to the operation of burning.

Instead of securing the presence of diluent gas in the draft current supplied for the secondary eolnloustion by introducing an excess of kiln gas into the oil-producergas formed in the primary combustion I ma insteadmix the diluent gas with the secon ary air. This is accomplished by simply opening the valve 32 to the proper extent and partially (if necessary) closing'the air valveor damper 31.- The blower 15 would now draw in more or less of the kiln gases from the pipe 23 through the pipe 30. These would mix with the secondary air drawn in from the cooler 2 through the pipe 14 thus diluting the oxygen of the air" Substantially the same result will be secured whether the diluent gas is introduced into the air oroil-producer-gas, i. e. the production in the kiln of a long slow-burning flame of moderate temperature but, owing to its relatively Igl'rezilzt volume, carrying a large quantity of When deemed desirable, the blower 15 may be omitted and the air admitted at air damper 11 simply permitted to ascend through thekiln shaft until its meets with the gas issuing from the passages 7 I, however, do not consider this method of operation as desirable as the one first described since it is more difficult, in this case, to secure a uniform distribution of the flame across the"'horizontal section of the kiln. The air and gas do not mix uniformly at the level of the ports 7 and there is therefore a considerable irregularity in the temperatures to which the '11. aterial in the region of the ports 7 is exposed. The combustion takes'place very graduallyas the air and gas currents mix and is extended over a considerable region. For the above reasons therefore I prefer the first-described method of operation in which the secondary air is drawn off from the kiln shaft below the gas inlets and injected into the gas near its point of entry'into the kiln shaft. In this way 1 Secure a uniform mixture of gas and air and a-inore uniform temperature across the kiln" shaft in the high temperaturezone.

' aving described my invention, what I claim is i i -1.-The .fprocess'. of burning liquid fuels Ttfli h comprises atomizing the said to combine with nascent carbon lating the proportion '0 mixing the atomized liquid fuel with carbon dioxid and air, regulating the relative pro portions of said carbon dioxid and air to supply suflicient of said constituents to effect the gasification and breaking up of heavy hydrocarbons of the liquid fuel with the minimum liberation of free carbon, and subjecting the said mixture to reaction to produce fixed gaseous products with the forma tion of a minimum quantity of soot.

2. The process of burning liquid fuels, which comprises, atomizing the said liquid fuel, mixing the atomized fuel with carbon dioxid and air, regulating the proportion of said carbon dioxid admixed with said atombine with nascent carbon produced in the combustion of the said liquid fuel, and regulating the proportion of air admixed wlth said liquid fuel tothat proportion required to generate a temperature in excess of 1300 ized fuel to that proportion required to com- F. in the combustion of said liquid fuel but below the proportion required .to completely burn said fuel, and subjecting the said mixture of liquid fuel, carbon dioxid and air to reaction to produce fixed gaseous products.v i

3. The process of burning liquid fuels, which comprises, atomiz'ing the said liquid fuel, mixing the atomized fuel with carbon dioxid and air, regulating the proportion of said carbon dioxid admixed with said atomized fuel to that proportion required roduced in the combustion of the said liquid fuel, and regulating the proportion of air admixed with said atomized liquid fuel to that proportion required to produce a temperature of between 1300 and 2000' F. on the combustion of said mixture, and subjectingthe mixture to a temperature sufiicient to insure. ignition, to produce fixed gaseous carbon products.

4. The process of burning liquid fuel, which comprises forming a draft current of carbon-dioxid-eontainin gas and air, reguf carbon-dioxid-containing gas in said draft current to that proportion required to supply the quantity of carbon dioxid necessary to substantially prevent the presence .of'free carbon in the gases during t e combustion (of said fuel, and regulating the proportion of air in said draft current to that proportion required to said draft current, subjecting the resulting mixture of li uid fuel, carbon-dioxidcontainl'ng gas an auto reaction to congas, mixing the said combustible gas with" mixture. a

5. The process of burning liquid fuel el at the desired point,

-a second portion of air, and burning the vert the said liquid fuel into a combustible fuel throughout a body of carbon-dioxidcontaining gas, adding air to the fuel-laden .carbon-dioxid-containing gas to that proportion required to generate suflicient heat by reaction with said liquid fuel to maintain the temperature of the gas mixture above 1800 F2, subjecting the gas mixture containing the liquid fuel to react-ion to cause partial combustion of the said mixture to convert the said mixture into combustible gas With a minimum separation of free carbon, mixing the so-formed combustible gas with a second portion of air and burning the mixture.

6. The process of burning liquid fuel which comprises disseminating said liquid fuel throughout a body of carbon-dioxidcontaining gas, regulating the proportion of air added to the fuel-laden carbon-dioxidcontaining gas to that proportion required to generate sufiicient heat by reaction with said liquid fuel to maintain the temperature of the gas mixture between 1300 and 2000 F., subjecting the gas mixture containin the liquid fuel to reaction to cause partia combustion of the said mixture to convert the said mixture into combustible gas with a minimum proportion of free carbon, mixing the so-formed combustible gas with a second portion of air and burning the mixture,

7. The process of burning liquid hydrocarbon fuel to form a flame of moderate temperature and comparatively free from soot which comprises, atomizing said liquid fuelinto a carbon-dioxid-containing gas,

regulating the relative proportipns of atom ized liquid fuel and carbon dioxid in the resulting mixture so that the proportion of carbon dioxid present will be that proportion required to react withnascent carbon produced in the subsequent heating of the mixture, and subjecting the said mixture to a temperature of between 1300 and 2000 F. by the partial combustion of the liquid hycgrocarbon of said mixture, to decompose saic hydrocarbon and to cause reaction between the carbon dioxid of said mixture and nascent carbon liberated in the decom position ofsaid hydrocarbon, whereby said mixture is concerted into a combustible gas.

8. The process of burning liquid fuels, which comprises, a-tomizing liquid fuel by a body of combustion gas under pressure, mixing with the fuel-laden combustion gas a quantity of air approximatingone-third of that theoretically required for the complete combustion of said liquid fuel, regulating the quantity of said combustion gas used in atomizin said liquid fuel to approximately one-fourth of the quantity of air added, subjecting the resulting mixture of'liquid fuel combustion gas and air to ignition to institute partial combustion thereof to convert said mixture into a body of permanent gases, and burning the so -formed permanent gases by a secondary air supply to generate heat.

Signed at, New York city "in the county of New York and State of New York this 12th J. M. MoMnL N, ]E. L. BLACKBURN.

day of April

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