US3373704A

US3373704A - Method of and furnace for burning fine granular substances in moist condition

Info

Publication number: US3373704A
Application number: US548487A
Authority: US
Inventors: Jung Richard
Original assignee: L&C Steinmueller GmbH
Current assignee: Hitachi Zosen Inova Steinmueller GmbH
Priority date: 1965-05-15
Filing date: 1966-05-09
Publication date: 1968-03-19
Anticipated expiration: 1985-03-19
Also published as: DE1526105A1; FI46435C; FI46435B; DE1526105B2; SE332678B

Description

March 19, 1968 R. JUNG 3,373,704

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Filed May 9, 1966 4 Sheets-Sheet 1 rior art IA/VZA/ 7'08 March 19, 1968 R JUNG 3,373,

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Filed May 9, 1966 4 Sheets-Sheet 2 prior art! l/WE/l/TUB March 19, 1968 R JUNG 3,373,704

METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Filed May 9, 1966 4 Sheets-Sheet 3 WI fA TOH March 19, 1968 R. JUNG 3,373,704 METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Filed May 9, 1966 4 Sheets-Sheet 4 WWW m 25% a? 73 United States Patent Ofi ice 3,373,704 METHOD OF AND FURNACE FOR BURNING FINE GRANULAR SUBSTANCES IN MOIST CONDITION Richard Jung, Gurnmersbach, Germany, assignor to L. & C. Steinmuller G.m.b.H., Gummersbach, Germany Filed May 9, 1966, Ser. No. 548,487 Claims priority, application Germany, May 15, 1965, St 23,827 6 Claims. (Cl. 110-7) ABSTRACT OF THE DISCLOSURE A method of and furnace for burning fine granular substances in moist condition characterized primarily in that combustion air is at an acute angle directed toward at least one of the respective adjacent front or rear walls in downward direction along said wall or walls, while a locally defined back and upward flow area of the combustion flow is created, and at least the by far major portion of the wet fine granular substance to be injected is, in the form of jets, in upward direction injected into the lower end of the back and upward flow area of the combustion air flow.

The present invention relates to a method of and furnace for burning fine granular substances in moist condition.

It is known to convey through nozzle means into a combustion chamber the waste liquor obtained during the production of cellulose together with water steam as atomizing substance, and subsequently to burn the thus obtained mixture in a hot air c-ountercurrent. The course and the result of the combustion are due to the reaction inertia of the liquor dependent to a great extent on the course of the flow of the combustion air and on the flue gases being'formed. This tendency has not been sufii ciently taken into consideration with heretofore known structures of the type involved so that such combustion chambers are not satisfactory from a combustion standpoint.

The combustion air is blown into the preferably prismatic combustion chamber from which the flue gas flows downwardly into the next flue through the ceiling of from two to four rows of nozzles parallel to the front wall while flowing from the top in jets parallel to each other. The liquor is passed into the combustion chamber through a plurality of atomizing nozzles extending through the front wall and the side wall. These last mentioned nozzles are so arranged that when the individual jets can spread in a cone-shaped manner without being interfered with, the atomized liquor would approximately be uniformly distributed over the chamber cross section in the neighborhood of the chamber ceiling. Since, however, the originally parallel air jets combine in the chamber to one or more air strands non-uniformly distributed over the cross section of the chamber, and since between the said strands the hot flue gas flows back from an area of advanced combustion, the length of the paths over which the individual droplets of the atomized liquor flow in the combustion chamber vary considerably. Thus, for a liquor component injected into an air str-and, a retarded combustion is to be expected which may be delayed up to the next following flue, whereas the liquor component carried along in a hot return flow will completely burn out within the chamber.

It is, therefore, an object of the present invention to provide a method of burning fine granular substances in 3,373,704 Patented Mar. 19, 1968 liquid condition in a combustion chamber, which will overcome the hereabove mentioned drawbacks.

It is another object of this invention to provide a method as set forth in the preceding paragraph, in which the individual jets will combine to a flow which will be uniformly distributed over the width of the wall of the combustion chamber.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIGS. 1 and 2 illustrate a method of burnin fine granular moist material in the manner heretofore known.

FIGS. 3 and 4 illustrate in corresponding views the method according to the present invention, FIG. 4 differing from FIG. 3 in that one nozzle row only is provided.

The above outlined different lengths of the combustion paths and the uncertainty inherent thereto in connection with the design and operation of such combustion chambers can be overcome according to the present invention by producing in the combustion chamber a flow form with a pronounced locally fixed return flow area. To this end, in conformity with the present invention, the air nozzles are suitably arranged and the entire liquor is injected into this area. Such a flow form is obtained for instance when introducing air through two rows of nozzles arranged in the chamber ceiling symmetrically with regard to the central longitudinal plane while the air jets leaving the nozzles are inclined relative to the adjacent front and rear walls at an angle of from 5 to 10. As a result thereof, a downward flow is obtained which is uniformly distributed over the width of the chamber and between the said flow along the walls there is obtained an extended double turbulence with a central return flow of hot combustion gases directed toward the ceiling. In conformity with the present invention, the liquor is bloWn into this return flow through a plurality of upwardly directed atomizing nozzles.

The'method according to the invention may also be realized by guiding the combustion air downwardly only along the rear wall and by guiding the hot return flow with the injected liquor upwardly along the front wall. In both instances, the fuel will pass into the combustion air flow only after it has reached the vicinity of the combustion chamber ceiling. In the preceding section, the aqueous component of the liquor evaporates, and the remainingdry substance is ignited. After this refining operation of the fuel which in its initial condition is rather reaction .inert, only a relatively short path is necessary for a complete combustion in the hot air flow.

In order more clearly to bring out the difference between the heretofore known method and the method according to the present invention, FIGS. 1 to 4 show the characteristic nozzle arrangements and the flow forms obtained thereby.

More specifically referring to the drawings, FIG. 1 shows a longitudinal section through a combustion chamber 1 with

nozzle rows

3 and 4 in the ceiling 5 of the chamber for supplying combustion air, the longitudinal section being substantially perpendicular to the front wall 2. FIG. 1 also shows atomizing nozzles 7 extending through opening 6 in front Wall 2. The arrangement of the nozzles is evident from FIG. 2 in the longitudinal plane perpendicular to the front wall.

The air jets which flow into the combustion chamber along paths parallel to the longitudinal walls combine in conformity with the drawn flow lines to a single strand which engages the front wall and one of the two

side walls

8 or 9. In that area which is not covered by this strand, an extensive return circulatory turbulence with a return flow preferably directed along the return wall 10 will occur. In this unsymmetric flow the starting conditions for the course of the reaction of the liquor in jected into the return flow or the air strand vary consid erably with regard to each other. The liquor component passing directly into the air strand will in view of the retarded ignition even at an increased excess in air not burn out completely or only in an inadmissible great distance in a downfiow direction of the combustion chamber.

In contrast to this heretofore known method illustrated in connection with FIGS. 1 and '2, with the method according to the present invention, as illustrated in FIGS. 3 and 4, the air jets leaving the

nozzle rows

3 and 4 are directed against the rear wall 8 and the front wall 2. In this connection, the illustrated symmetric flow form with the central return flow will be obtained which carries the injected liquor. This return flow is combined with the partial fiows of the combustion chamber which flow downwardly along the walls. Moreover, the inclined position of the air nozzles brings about that the individual jets expand along the walls in a direction perpendicular to the intermediate plane and thus flow together to a flow which is uniformly distributed over the width of the wall. The constriction of the downward flow detached from a side wall as it occurs with wall parallel feed according to FIG. 2, will not occur.

FIG. 4 shows an arrangement with only one nozzle row 3 directed toward the rear wall 8. In this instance, the liquor is injected into the return flow area adjacent to the front wall. The inclined position of the ceiling favors the return flow into the outer zone leading to the mouth area of the air nozzles.

The method according to FIG. 3 or 4 is also suitable for burning moist fine granular substances, as for instance coal sludge or slurry, which is dried within the hot return flow and ignited and can be burned when mixed with the preheated air.

It is, of course, to be understood that the present invention is, by no means, limited to the particular method set forth above but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. A method of burning moist and wet fine granular substance in a combustion chamber having at least approximately parallel front and rear walls, which includes the steps of: passing combustion air at an acute angle toward at least one of the respective adjacent one of said walls in downward direction along the same while creating a locally defined back and upward flow area of the combustion air flow, and directing at least the by far major portion of the said wet fine granular substance in the form of jets in upward direction into the lower end of the said back and upward fiow area of said combustion air flow.

2. A method according to claim 1, which includes the step of: passing the combustion air in downward direc tion in the form of two spaced relatively fiat flows along said front and rear walls respectively while said flows extend on opposite sides of the longitudinal central plane of said combustion chamber and while creating the locally defined back and upward fiow area of the combustion air flow along the said longitudinal central plane.

3. A method according to claim 1, which includes the steps of: passing the combustion air in downward direction in the form of a relatively fiat flow along said rear wall only while creating the locally defined back and upward flow area of the combustion air flow along said front wall.

4. A furnace comprising a combustion chamber having a front and a rear wall and a ceiling, first nozzle means arranged in said ceiling and having the mouths thereof directed at an acute angle toward at least one of the respective adjacent walls for passing combustion air downwardly in the form of a relatively flat flow along at least one of said walls, and second nozzle means having the mouths thereof directed substantially vertically upwardly and spaced from at least one of said walls by at least approximately half of the distance between said front and rear walls for injecting waste liquor into the lower end of the back and upward flow area of the combustion air flow halfway between said front and rear walls.

5. A furnace according to claim 4, in which said first nozzle means comprises a first row of nozzles with the mouths thereof directed at an acute angle to said rear wall and also includes a second row of nozzles with the mouths thereof directed at an acute angle toward said front wall, said acute angles substantially equalling each other, the mouths of said second nozzle means being located at least approximately along the central plane between said front and rear walls.

6. A furnace according to claim 4, in which said first nozzle means have all of their mouths directed toward said rear wall, whereas the mouths of said second nozzle means are adjacent said front walls for directing said substance along said front wall in the form of a relatively flat flow, said ceiling being inclined in upward direction so as to ascend from said front wall towardsaid rear Wall.

References Cited UNITED STATES PATENTS 1,770,987 7/1930 Lundgren -28 2,531,810 11/1950 Fyffe. 2,582,792 1/1952 Paren. 3,306,?) 34 2/1967 Goubsky 1584 JAMES W. WESTHAVER, Primary Examiner.