US1874341A - Process of burning heavy oils - Google Patents

Description

Aug. 30, 1932. -W.,OSTHOFF 4 PROCESS OF BURNING HEAVY OILS Filed llarch 30, 1928 2 Sheets-Sheet 1 In yen for Aug. 30, 1932. w OSTHQFF 1,874,341

PROCESS OF BURNING HEAVY OILS I Filed March 30, 1928 2 Sheets-Sheet 2 r II llflaooooooooo II 2 only by the heavy Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE WALTER. osrnorr, or maxim, GERMANY IROCESS OF BUBNIN G HEAVY'OILS Application filed March 30, 1928, Serial No. 265,921, and in Germany November 8, 1927.

The arrangements hitherto well known for the combustion of large quantities of heavy oils, as for example, 011 furnaces or burners for marine boilers, for smelting furnaces,

\ hardening furnaces, annealing'furnaces and other industrial urposes operate with oil that is sprayed, t e spraying being brought aboutwith the aid of steam or compressed air and the combustion of the oil taking in place with a white flame and the flame playing on an incandescent body. The consequence of this is that even when the oil un- 'dergoes complete combustion, which in reality is not attained'inthe case of most furw naces of this kindgthe thermal e'fliciency nevertheless remains comparatively small. The attainment of the highest flame temperature and consequently a better utilization of the heat can on the contrarybe obtained oil being vaporized before leaving the burner and by this fuel, converted into the formof'vapour and mixed intensively with air, beingbrought into a state of combustion. This combustion is moreover to occur with blue'fla'mes in contradis tinction to the'fiames which have been white hitherto.

Attempts, it is true have hitherto been made, to obtain in the case of these oils combustion in the form of blue jet flames. All these attempts have however failed on account of the fact that it was not possible to obtain a design of burner requisite for this purpose. and which would be reliable for plant running permanently, because the burners themselves and the supply pipes leading to .these burners were according to the kind of after a short time, more or less, 'stoppe up by tar residues and formed, particularly w was employed.

The attempt has been made to avoid these defects by conducting the oil to be vaporized through incandescent tubes with the object of carrying the vaporization as far as posen tar-containing oil etroleum coke as itoil emplo ed,

is being mixed with it sible and in addition also to effect at least partially a decomposition into pure gasof' the oil vapour alongside of the incandescent walls. But in this case also there occurs even after a comparatively short time a thick inm crustation of the burner opening by means of coke and the collection of other residues in the burner pi e, particularly when it is a matter of employing oils containingtar. For this reason also regular running for a cobmparatively long time has not been poss1 e. a

- According to the present invention the defects mentioned are substantially avoided by the fuel to be vaporized being heated prefero0 ably not materially above the temperature of 350450 centigrade requisite for the we porization and then while air of combusti n being cooied (Lara-1 again considerably on the Way to the burner 55 mouth. The cooling down of the oil vapor may take place most simply by an ample admixture of the air of combustion which has been preheated only slightly or not at all, the amount of which is many times as great as that of the fuel vapor. The combustible mixture may be cooled down suitably to 50 centigrade or to a still lower temperature. In consequence of the compara-- tively large quantity of air the vaporized oil is suspended in the form of mist in the added air and passes with the latter out of the mouth of the burner. In order to prevent the combustible mixture from becomlng heated again by the burner head which is exposed to the heat of-the .fire it is to be recommended to cool said burner with water or with another suitable medium. This construction at the same time advantageously renders it possible to arrange the burner in the interior of 86 the furnace, for example, in the case of steam boilers in the interior of the furnace tube, and this may be donein such a manner that its nozzles or the flames leaving them, are directed about at right angles against the sur- '0 shell of the tube, so that the heating does not take place as otherwise usual in most cases principally on the upper half of the furnace tube, but at the side portions and con-- sequently a more lively generation of steam and circulation of water is effected, which results in the boiler having a greater workinglpapacity.

order to obtain an advantageous flame formation and to guide the flames advantageously, it is to be recommended'to arrange by the side of the burner tube one or more tubes which serve to supply secondary air and which,'if desired, may also be united with the burner tube, so that the water cooling arrangement of the latter simultaneously protects the secondary air tube from excessive heating.

In detail the process may be carried out in the following manner. After the burner has been sufficiently preheated suitably by means of a readily volatile fuel or in some other suitable manner, the

liquid fuel is led through a vaporizing chamber, which may be heated by the waste heat of the heatin flame. The temperature and the supply of heat to this vaporizing chamher is advantageously so controlled that the highest boiling temperature of the fuel be ing vaporized at the time is not materially exceeded. In the case of the most ordinary heavy oils the oil vapor produced in the vaporizing chamber should consequently while being generated in so far as is possible not be carried above a tem erature of 350450 C. The fuel vapor is rought by means of the pressure develo ed inthe vaporizing cham er by virtue o the vaporization through a suitable supply pipe into the burner tube proper. This burner tube is fed with compressed air. The fuel vapor and compressed air flow into this burner tube together and form an intimately mixed mixture of fuel vapor and air. It'is important for this primary air to be supplied to the burner head proper either in a cold condition or an onlyvery moderately preheated cond tion. From the burner tube the mixture of fuel vapor and air flows through one or more nozzles into the combustion chamber proper. In the case of all these burners on account of the reflected heat the burner head and the nnozz1e walls are heated to a greater or less extent] According to the invention it is coning flame always remains at temperatures.

which are as far as possible below the boilinggpoint of the liquid fuel.

y means of thorough tests and experiments during permanent running it has been ascertained that the greatest reliability in operation is attained when the temperature of the outflowing mixture is permanently maintained even under 50 centigrade. This mixture, which is explosive on account of the intensive admixture of air, in consequence of the temperature of discharge which is kept artificially low and of a hi h discharge pressure which is intentional y brought about and also in consequence of the high velocity of discharge connected therewith, does not burn until at some distance from the nozzle- 'head of the burner, through playing on an incandescent surface by means of which the mixture is continuously explosively ignited, so that the combustion is thus maintained. The formation of a ure blue jet flame with the development of t e highest flame temperature is brought about by said mixture of fuel vapour and air being decomposed (as in'the case of the oil-gas process) into pure gases on making contact with the said incanescent body, so that consequently these a maximum temperature which does not matf erially exceed the highest boiling limit of the uel. v

2. This fuel vapour isintimately mixed before reaching the discharge nozzle with a comparatively large uantity of cold or very moderately preheate atmospheric air.

3. This mixture containing a great deal of air is kept permanentl cool until reaching the burner mouth, so t at there cannot take place a decomposition of the fuel vapour and a deposition ofpertoleum coke and tar incrustations in the burner and on the walls of the fuel nozzle. 1

4. This mixture which is kept cool is blown with a high discharge pressure and at a correspondingly great velocity of discharge against a previously heated incandescent body and thus kept continuously explosively burning with pure blue jet flames secondary air being supplied if desired.-

The result of this is that all heating arrangements hitherto employed for industrial purposes which are now run with heav oil and thus burn with white flames may urn in future according to the present invention with blue jet flames and thus obtain with a considerably less quantity of fuel the same heating effect, so that-they can effect a material saving in fuel. Moreover the combus tion is always perfectly free from smoke and soot.

In the drawings there are represented for the purpose the better elucidation of the process several constructional examples of such a furnace, the same being shown by way of example as a steam boiler furnace. .In said drawings Fig. 1 is a vertical longitudinal section through the furnace of a furnace tube boiler havingtgge burner arranged at the front'end of the fl nace tube,

Fig. 2 a front elevation cording to Fig. 1.

Fig. 3' a furnace for a furnace tube boiler having a burner extending throughout the whole length of the furnace tube,

3 Fi 4 a cross-section on the line AB Fig.

, ant

Fig. 5 a further constructional form in cross-section of the burner for a furnace according to Fig. 3. i

In the caseof the example according to Figs. 1 and-2, 6 is the supply pipe for supplying the liquid fuel to the vaporizing chamber 7 which is heated to such an extent by the radiant heat of the flame 4 that the complete vaporization of the liquid fuel employed is brought about. This fuel vapour is supplied through the pipe 8 in the direction of the arrow 8a to the burner tube proper 1. To the burner tube 1 there is supplied compressed of the furnace ac air inthe direction of the arrow 9a. The fuel vapour and the compressed air are intimately mixed without special devicesat the place where. they meet in the burner tube 1. In this manner the fuel vapour, which on being r0- duced has a temperature of about 350 to a maximum of 450 0,, isefiectively cooled down in consequence of its quantity being small relatively to the primary air admitted. The temperature of this fuel mixture is thus according to the invention in consequence of the preceding circumstances veryconsiderably below the vaporization temperature." The burner tube 1 for the supply of thecombustible mixture possesses at its mouththe burner head proper 1b and adjacent thereto the cooling chamber 1a. The same is so arranged that the cooling medium, ,preferably water, flows in the direction of the arrow 10 in the pipe 21 and is conducted away again in the direction of the arrow 11 through thepipe 12. The cooling chamber 111 is'so arranged and constructed that the walls of the outlet nozzle 10 are kept efiectively'eool' with absolute certainty. The greatest reliability in operation and the most eflicient cooling are obtained when the temperature of the mixture of fuel vapour and air is below centigrade at the outlet. The combustible mixture is nevertheless kept sufficiently cool if to the burner either through the action of the suctional draught or .in the form of compressed air.

In the constructional example according to Figs. 3 and 4, 1 is the burner tube which extends through the whole length of the furnace tube 15 and is 'held at the front end in the cover 17 of the furnace tube and at the back end on the contrary in a fixed wall 18 of masonry. The latter is situated at a certain distance from the back boiler-wall l3 and serves at the same time to guide the gases of combustion leaving the furnace tube.

, Below thevburner l is situated the vaporizing tube 7 to which there is led in the direction of the arrow 6a through the pipe 6 the fuel to be vaporized. The vaporizing tube 7 is inclined towards the front end of the boiler and is there connected through a rising pipe 8 with the burner tube 1 which for its part likewise possesses a slight fall in the direction of motion of the fuel, that is, it has an inclination in the opposite direction. Both tubes 1, 2 are provided at their lowest parts with a double U-shaped escape-pipe 20 or 20a which enables the possible automatic escape of non-vaporized liquid to take. place and at' the same time by means-of the seal of liquid in the lower U-bend prevents the escape of the fuel vapour from the'vaporizer tube or the burner tube. v e

The burner tube 1 is provided at both sides with a series of nozzle-openings 10 or 1:0 so that the escaping flames 4 or 4a are directed approximately horizontally towards opposite sides against-the furnace tube walls and at these are turned upwards and downwards in the direction of the arrow 5. In this man-.,

ner an extremely effective heating of the Whole concave surface takes place, and indeed most powerfully so, at the lateral surfaces of the furnace tube and over its whole length, the distribution being uniform, so that steam is generated powerfully and the boiler is worked to its maximum capacity, as is indi cated in Fig. 4 by means of the arrows 14 and 14a, V

The burner tube 1 is provided in the neigh- 55 a tively stated is as follows borhood of the rising .pipe 8 for the fuel vapour with a connecting union 9 for the secondary air flowing in the direction of the arrow 9a andit'is provided throughout the whole of its length lying within range of the fire with coolin channels 1a which are formed by' angle-irons 24 welded on the burner tube and which are traversed by water or another suitable cooling medium, which is supplied through the pipe 21 and led away again through the pipe 12, and which consequently keeps the burner tube cooled throughout the entire length.

Above and below the burner tube 1 there bodies 3, 3a consisting of ceramic matter or other refractory material, which bodies are suspended in such a manner as to be capable of being readily exchanged, on bars 25 passing from end to end, said bodies having upper ends curved in the form of hooks.

Both the burner tube 1 and also the vaporizing tube 7 are at both ends led outwards out of the range of the fire and they are provided outside the closure wall 17 or 18 with flanges 27, 28 or 29, 30 respectively. This arrangement renders the two tubes readily accessible and enables them to be well cleaned and indeed in such a manner that the burner requires to be put out of action for only a very short time and in particular it is possible to conduct the cleaning operation without the burner and the other tubes requiring first to cool down, because the places of admittance requisite for the cleaning are all situated below the range of the fire and the tubes pass without bends rectilineally from one up to the other outside place.

In order to avoid. the secondary air tubes 2, 2a becoming too highly heated, the same may suitably be arranged, as represented in Fig. 5, in the-direct neighbourhood of the burner tube and be enclosed jointly with the latter by a casing 26, which at the same time also contains the'cooling channels 1a.

The mode of action of the device consecu- Through the tube 6 there is first admitted,

.-on setting the burner in action, gas, benzine or other volatile fuel, which passes in the form of gas or in a vaporized form via the tubes 7 and 8 into the burner tubel from which it flows out through the nozzle-open-i ings 10 or 1:1: into the furnace chamber where it can be ignited. After in this manner bymeans of gas or volatile fuel the'whole burner arrangement and in particular the vaporizing tube 7 and also the igniting bodies 3, 3w have been brought to a sufliciently high temperature, the heavy oil is now introduced through the pipe 6 into the vaporizing tube 7 where it is va orized by means of the radiant heat of the urnace. The position of the tube 7 is preferably such that the fuel is heated to about 350-450 centigrade and is thereby vaporized. The fuel apour thus generated is supplied through t 1e rising pipe 8 to the burner tube 1 and mixed with the primary air supplied from the left through the union 9. This burner air is preheated not at all or only very slightly and is mixed to such an ample extent with the fuel vapour that the latter is cooled down to about 50 centigrade or still lower. In consequence of the large admix-.

ture of air and of the slight saturation resulting therefrom the fuel vapour remains as mist suspended in the primary-air and then passes jointly with the latter out of the nozzle openings 10 or 1:1: in the burner tube. The velocity of discharge is suitably so regulated that the flame is unable to formuntil at a certain distance from the nozzle-opening, and this indeed beingeflt'ected by making contact with the incandescent impact or checking surfaces or ignition surfaces 3, 3a which maintain the flames explosively burning by means of continuous ignition and at the same time effect the decomposition of the fuel vapour into pure gases.

In this manner one obtains an extremely hot'blue flame 4 or 4a which is directed towards the right and left horizontally against the furnace tube wall and which is turned against the latter upwards anddownwards. At the same time the supply of secondary air takes place through the tubes 2, 2a, the jets of secondary air passing out of the nozzle openings of said tubes being able to be utilized to aid in the correct guidance of the flames so that the flame plays as much as is possible against the whole concave surface of the furnace tube and an extremely effective heating of the furnace tube takes place, which heating extends uniformly over its whole length. This heating in contradistinction to the commonest well known furnaces with furnace tubes is most powerful at the two sides of the furnace tube and this circumstance is of special importance because thereby the steam bubbles being generated can rise quickly and also an inflowof fresh water can take place more quickly, so that in this manner the quantity of evaporation and consequently the capacity of the boiler can-be materially increased.

As already previously mentioned the temperature in the vaporizing tube-7 is suitably not raised above 350450 "centigrade. In the event of there being present in the 051 additional constitutents which do'not articipate in the vaporization process, t ese constituents in consequence of the inclinaand at the same time to obtain an increased.

development of heat.

It may also particularly be pointed out that in the case of the present processthe admixture of the primary air with the fuel vapour may also be undertaken on such a large scale as is requisite to-render superfluous the demand for secondary air for the complete com: bustion of the fuel mixture.

It is obvious that it is perfectly feasible to provide any desired number of fuel outlet nozzles for a furnace plant which is under consideration, and to coolseparately or together the outlet nozzles and that any desired number of separate/chambers or common chambers for vaporizing the liquid fuel may be arranged. In the case of the heating of steam boilers it is also possible to utilize a portion of the water in the steam boiler or the generated steam as a medium for keeping the burner head cool.

Obviously there may also be consumed with the devices for carrying out the processliquid fuels which are already free from tar or which in consequence of their special qualities do not tend to form incrustations orto form coke. By means of the process for keeping cool the combustible 'mixture and the'outlet openings for the combustible mixture the great additional advantage is also obtained that the quantity of fuel mixture flowing out remains always uniform in its calorific.

value, since a diminution of the outflowing specific calorific value by means of the gradually increasing heating of the outflowing jet of fuel mixture then takes place .no longer.

I claim 1. The herein described process of burning heavy oils which consists in vaporizing the oil, cooling the oil vapor below the temperature of liquefaction before combustion, conducting the ,cooled vapor to a combustion zone, and then gasifying the oil' and burning the oil gas.

2. Process according to claim 1, consisting of the cooling down of the vaporized fuel being effected by the intensive admixture of primary air v preheated no more than to a slight extent.

3. Process according to claim 1, consisting of the cooling down of the vaporized fuel being effected at least partially by passage along a relatively cold surface.v

4. Process according to claim 1, consisting of the heating of the fuel for the purpose of vaporization not materially exceeding the boiling point of the heavy oils employed.

5. Process according to claim 1, consisting of the mixture consisting of the vaporized fuel and air being cooled down on the way to the mouth of the burner to a temperature not exceeding about 50 C.

a 6. The herein described process of burning heavy oils which consists in vaporizing the oil, cooling the oil vapor below the temperature of liquefaction before combustion, mixing withithe cooled oil vapor air in such quantity to produce complete combustion without excess of air, projecting the mixture from a'predetermined point at such velocity as to prevent formation of flame at said point, bringing the project-ed mixture into contact with incandescent checking surfaces to ignite and explosively burn the oil.

' 7. The process of burning heavy oils which consists in vaporizing the oil, introducing the oil vapor into a conduit and conducting it therethrough, introducing air into the conduit at such a temperature that the oil vapor V will haye its temperaturelreduced below the vaporization point and mixing the air and oil,- discharging the mixture in a jet from the conduit, and gasifying and burning the discharged mixture.

8. Theprocess of burning heavy oils which consists in vaporizing the oil, introducing the oil vapor into aconduit and conducting it therethrough, introducing air into the conduit at such a temperature that the oil vapor will have its temperature reduced below the vaporization point and mixing the air and oil, discharging the mixture in a jet from the conduit, and gasifying and burning the discharged mixture in spaced relation to the point of discharge from the conduit.

9. The process of burning heavy oils which consists in vaporizing the oil, introducing the oil vapor into a conduit and conducting it therethrough, introducing air into the conduit at such a temperature that the oil vapor will have its temperature reduced below the vaporization point and mixing the air and oil, discharging the mixture in a et from the conduit, and gasifyingnnd burning the more readily combustible portions of the mixture while separating therefrom the more refractory portions. ,1"

10. The process of burning heavy oils which consists in vaporizing the oil, intro- ,ducing the'oil vapor into a conduit and conducting it therethrough, introducing air into the conduit at such a temperature that the oil vapor will have its temperature reduced 11. The process of burnin heavy oils which consists in vaporizing t e oil, intro ducing the oil vapor into a conduit and. con ducting it therethrough, introducing air into 5 the conduit at such a temperature that the oil vapor will have its temperature reduced below the vaporization point and mixing the air and oil, discharging the mixture in a jet from the conduit, maintaining the zone of 10 discharge in a cooled condition, and gasifying and burning the discharged mixture whereb a high temperature difference is maintained between the zone of dischar and the combustion zone and the more readi y 15 combustible constituents of the mixture are quickly separated from the more refractory constituents. p

In testimony whereof I aflix my si ature.

WALTER 0ST OFF.

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