US2678615A - Method for burning sticky, watercontaining liquid fuel - Google Patents

Description

y 18, 1954 G. K. SODERLUND ETAL 78,615 I METHOD FOR BURNING STICKY, WATER-CONTAINING LIQUID FUEL l Filed Jan. 25, 1950 w (NV may,

WA WV Patented May 18, 1954 METHOD FOR BURNING STICKY, WATER- CONTAINING LIQUID FUEL Gustav Kristian Siiderlund, Sten Giista Lindberg,

and Torsten Magnus Georg Simmons, Norrkoping, Sweden, assignors to Rosenblad Corporation, New York, N. Y., a corporation of New York Application January 25, 1950, Serial No. 140,358

Claims priority, application Sweden December 20, 1949 1 Claim.

This invention relates to an improved method of burning liquid fuels and toy an improved construction and operation of fuel burning apparatus especially designed for carrying out this method. The main object of the invention is to enable effective burning of water-containing liquid fuels such as, for instance, sulphite waste lye evaporated to say 50 to 60% dry substance. Burning of such fuel directly, without any additions, in a modern boiler furnace having cooled walls will not be possible, as a rule, since the temperature in the boiler furnace will be too low. In noncooled boiler furnaces, on the other hand, burning of such fuel may be possible under particularly favourable conditions. For example, the dimensions of theboiler furnace should be Sllfilciently large to give the suspended particles of the fuel injected in finely divided or atomized condition time enough to dry into an inflammable, or at least a non-sticky, condition before they meet an obstacle. In addition, for a complete combustion an air supply specially adjusted to the fuel will be necessary. Changes in an already existing boiler furnace in order to comply with these requirements may be costly and may sometimes be impossible to carry into effect.

One object of the invention is to render the burning substantially independent of the type of furnace chamber of the boiler. For this purpose the fuel is burnt in a pre-furnace in which a high temperature is maintained, and in which fuel and at least the major portion of combustion air efiect will take place and in which the combus- .tion air supplied and the resulting gases of combustion are caused to whirl along the internal more or less cylindrical wall of the cyclone chamber in a cylindrical and/or conical, helical flow.

In order to accomplish the desired interference the fuel is injected in or from, or in a direction clone type, in which a cyclone-like separating towards, the central portion of the cyclone and along axially or radially, or both axially and radially, directed paths relative to the cyclone chamber, the fuel particles being introduced gradually into the whirling flow so as-to get completely dried, and, in most cases, also ignited, before being centrifuged against the cylindrical internal surface of the cyclone chamber. Subsequently, the fuel particles, without any risk of sticking, may be carried by the whirl in :a sliding movement against the cylindrical surface through the cyclone chamber, so as to complete the combustion if not already completed during the centrifuging process. Especially, the particles which are most difiicult will, in uncompletelly burnt condition, reach the outermost zone of the whirl where the contents of oxygen are highest and, therefore, the conditions for combustion are most favourable. In addition, due to the friction against the wall, the velocity of the particles will be decreased in relation to the velocity of the whirl in this region, whereby an extraordinary intimate mixing with the air is obtained.

. A still further object of the invention is to distribute the combustion air at a multiplicity of places along the length of the cyclone chamber and the path of movement of the whirl, so that the particles carried by the whirl will enter into a cross-current contact with the combustion air whereby the combustion process is enhanced. A specific object of the invention is to introduce the air from the peripheral region of the whirl so as to cause the air to flow from that region helically inward and thus to decelerate the particles moving radially outward to be separated. The time during which the latter particles are in suspension to be dried, ignited and burnt, will thus be increased so that a major portion of the fuel will burn in suspended condition in the central region of the whirl, whereby the ignition of freshly inmaximum temperature which is of great advantage, especially when burning low-grade fuelsof the kind with which the invention is concerned.

Another specific object of the invention is to effect a certain cooling of the interior wall of the cyclone chamber by means of the air thus supplied so as to prevent the temperature of the brickwork from exceeding the permissible maximum value.

A further object of the invention is to reduce the radiation of. heat from thefuel particles as well as from. the brickwork to cold surfaces arranged beyond the gas discharge exit. To this purpose the cyclone chamber may have a relatively large length in relation to its diameter.

A still further object of the invention is to cause the ash particles resulting from the fuel. to be crushed or ground against the wall of the cyclone chamber on moving along said wall contact with the same so as to reduce the volume of the ashes.

One embodiment of a cyclone chamber for carrying the invention into effect is shown diagrammatically in the accompanying drawing in which:

Fig. 1 shows a cross-section of the chamber taken along the line II- of Fig. 2, and

Fig. 2 shows a longitudinal section of the same chamber taken along the line IIII of Fig. l. Referring to the drawing, the cyclone. chamber I is-substantially cylindrical and hasv at one -end-arestricted gas outlet 2. The chamber I is arranged as a pre-furnace and communicates through the gas outlet with any suitable furnace, boiler or combustion chamber, one wall of which is shown at 3. At the opposite end of the cyclone chamber there is arranged one or more substantially central supply pipes d for liquid fuel, each bfsaid pipes having an atomizer or spraynozzle 5,"ithr0ugh which the liquid is sprayed into the chamber 1 more or less axially, but the direction of the spray may also be more or less radial, ort-he supply may be effected along any suitable c-hord toward or away from the axis of the chamber i, or a combination of any' given axial and radial or chord direction maybe resorted'to. 'The major portion of or the whole amount of the combustion air is introduced through'a number of air inlets 5, extending substantially tangentially to the inner wall of the cylindrical chamber I and being distributed along at least .the substantial part of the length of the cyclone 'chamber, or consisting ofone elongated intake. .Said inlets may be controlled individually or in common by means of throttles 1 .or any suitable other means.

. .In. operation, the water-containing liquid fuel, such as evaporated sulphite waste lye, is. introduced through the nozzle 5.and intimately mixed with the air supplied through the inlets 6 so as to form a whirl passing through the chamber Qin a. helical path. The fuel particles are introduced gradually into the whirl, the apparatus ,acting like acyclone so that each .fuel particle ,will be suspended in the whirl of gases for a sufficiently long time to get completely dried, or dried and ignited, before they will be contrifuged againstthe cylindrical wall or chamber 1 where- ..upon the particles are completely burnt in the chamber. Due to the cyclone effect the nonburnt, dried particles will be flung towards the .cylindrical wall of the chamber 1 and. caused tomove along said wall together with the whirl. .As aforesaid, such. particles will be ground and "their velocity reduced due to the frictionagainst the. wall, so that the air will get suflicient time all!) burn the. particles before they leave the chamber I. Thus, when the combustion products leave the chamber 1 and enter the furnace 3 there will be no sticky particles which may deposit on the cooled surfaces of the furnace.

Burning of sulphite waste lye is also intimately bound up with the problem of handling the ashes obtained. A lye droplet which burns in suspended condition givesa thin-walled hollow ash-particle of the approximate shape of the shell of a blown egg and of the same order of .magnitude as that of the droplet. Obviously ashes in this form, amounting to a quantity of about 10% of the dry-substance of the lye, will ;b.e unreasonably bulky. On account of its extremely low weight by volume the major part of the ashes will accompany the combustion gases through the furnace or boiler 3 causing a deposit on the tubes therein, and will finally be discharged through the chimney, to th detriment of the surroundings, if the ashes cannot be separated before their exit.

In accordance with this invention, on the other hand, the ash-particles will be subjected to a continuous crushing and/or grinding action against the cylindrical wall-surface of the cyclone chamber I, so that they will lose th ir hollow character, whereby their weight by volume isincreased so thattheir separation and removal bydynamical means will be facilitated. Inaddition, the whole quantity of the ashes will be densified, so that it will be less troublesome to remove the same and to store it as a waste product.

tomake the cyclone chamber l of greater length then would be necessary, solely-from the point of view of effecting complete cornbustio'ngin order to obtain length in excess for ensuring grinding of the ashes even from allburnt particles.

A minor portion of the combustion air may be introduced with the fuel, if desired.

Ignition of the fuel on starting the device may be effected by heating the chamber l internally in a suitable manner. g 'It should be noted that it is not necessary that the fuel is supplied in the central region of the whirl. butit may also be introduced in a direction toward or from said region.

What we claim is: v v

A method of obtaining self-sustaining burning of a water-containing liquid fuel of highly sticky consistency in a moist comprising in combi, nation the steps of introducing at axially spaced intervals substantially tangentially to the circumferential. inner wall of a hot combustion chamber of substantially circular cross section at least the major portion of air required for complete combustion of said fuel so as to produce and maintain in the combustion. chamber a series of free spiral vortexes of said air in coaxial relation to each other in which the air moves in spiral paths towards an outlet for combustion gases from said combustion chamber, introducing said fuel under pressure in. finely divided liquid state in a substantially straight line axial direction only into the central zone of those of the vortexes most remote from said outlet, the expanding fuel and air action thereby causing the wet. fuel particles to be gradually brought from said central Zone outwardly into the whirling motion of the .air vertexes and by action of the centrifugalforce being dried to solid substantially non-sticky par- From this point of view it may be advantageous 5 tioles which are ignited before they reach the References Cited in the file of this patent radial wall oi the combustion ohamberiand at UNITED STATES PATENTS least substantially completing the combustmn of the dried fuel particles while they are f'moving' Number Name Date axially, with the outer layers of the vortxes re- 5 473,980 Blackman u 19, 1892 ceiving fresh air from vortex to vortex,;thereby 1530321 Pollock 17, 1925 maintaining the combustion chamber sumciently Burg 1927 hot to provide continuous self-sustaining burn- Saba 26, 1937 mg of said fuel and removing the products of 2342553 Maxwell May 1941 combustion from said chamber. 10 2-483-728 Glaeser 1949

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